project
TRANSCRIPT
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 1
Chapter-1
INTRODUCTION
Many chemical reactions supply liquid or gas mixture that has to decompose by
heat Some mixtures occurring in nature must be broken down to recover specific
constituent such as aromatics petroleum distillate serving as fuel air liquefied to produce
nitrogen oxygen and rare gases or water distilled for use in nuclear installations
Distillation is a method of separating the components of a solution which depends
on the distribution of the substances between a liquid and gas phase applied to cases where
all components are present in both phases
In order to make clear the distinction between distillation and the other operations
let us site a few specific examples In the separation of solution of common salt and water
evaporation is used Salt is non-volatile at the prevailing conditions On the other hand
distillation is concerned with the separation of solution where all the components of a
liquid solution are appreciably volatile
The advantages of distillation as a separation method are clear In distillation the
new phase differ from the original by their heat content but heat is readily added or
removed cost of this is considerable
Distillation in crude form was practiced before the time of Christ usually for the
concentration of alcoholic spirit The first formalized documentation of the process appears
to have been the treatise by Brunswig published in 1500 (2) Despite the emergence in
recent year of many new separation techniques distillation retains its position of
supremacy among chemical engineering unit operation
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Dr Babasaheb Ambedkar Technological UniversityLonere 2
Chapter-2
TYPES amp METHODS FOR DISTILLATION
21Batch Distillation ndashthe simplest form of batch still consist of a heated vessel (pot or
boiler) a condenser and one or more receiving tanks no trays or packing are provided The
feed is charged into the vessel and brought to boiling Vapors are condensed and collected
in a receiver no reflux is returned The rate of vaporization is some times controlled to
prevent ldquobumpingrdquo the charged and to avoid overloading the condenser
22Single-Stage Operation ndashFlash Vaporization
in this method a liquid mixture is partially vaporized the vapors allowed to come to
equilibrium with the residual liquid and the resulting vapor and liquid phases are separated
and removed from apparatus The liquid feed is heated in the conventional tubular heat
exchanger
23 Continuous Distillation
1 For binary system
Binary distillation is probably the most common and important of the unit
operationrsquos basic principle in binary distillation is that one component in binery
mixture is more volatile than other and concentration of this component in the
vapor phase is greater than liquid phase
2For multicomoponent system
Multicomponent distillation is more difficult than binary distillation in that
graphical techniques are not really useful except in special cases
For multicomponent calculations we use the following
1material balance
2energy balance
3 vapor liquid equilibrium
4 estimation procedure
5facilities limitations
6a well organized approach
Various kinds of devices such as random or structured packings or plates or trays are used
to bring the two phases into intimate contactThe feed material which is to be separated
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 3
into fraction is introduced at one ir more points along the column shell because of the
difference in gravity between vapor and liquid runs down the column while vapor flows up
the column Liquid reaching the bottom of the column is partially vaporized in heated
reboiler to provide boil up which is sent back to the column the remainder of the column
is withdrawn as bottomor bottom productVapor reaching the top of the column is cooled
and condensed to liquid in the overhead condenser part of this liquid is returned to the
column as reflux to provide liquid over flow The remainder of the overhead stream is
withdrawn as distillate The lighter component tends to concentrate in the top distillate and
heavier in the bottom products The result is a vapor phase that becomes richer in lighter
component as it passes up the column and a liquid phase that becomes richer in heavy
component as it cascades downward The overall separation achieved between the
distillate and the bottom depends primarily on the relative volatilities of the components
Key Components
When it is necessary to separate a mixture of many components as is frequently the
case in the petroleum industry the two key components are selected to produce a product
mixture having specified characteristics It is then likely that the keys do not fall adjacent to
each other but have an intermediate boiling component between them referred to as ldquoas a
distributed keyrdquo
Two components whose concentrations or fractional recoveries in the distillate and
bottom products are good index of the separation achieved Since the keys must be differ in
volatilities the more volatile identified as light key and less volatile as heavy key
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 4
Chapter- 3
MULTICOMPONENT DISTILLATION METHODS
31 Fenske-Underwood-Gilliland (FUG) Shortcut Method ndash
311 Fenske equation ndashthe fenske equation estimates the minimum number of theoretical
stages at the total or infinite reflux This equation assumes the relative volatility remains
constant throughout the column If the equilibrium data have some interaction between
components it is desirable to determine a third set of equilibrium data The third set of data
can be obtained by using the arithmetic mean average of the condition
3
bottomHK
LK
middleHK
LK
topHK
LKavgLK K
K
K
K
K
K
Otherwise the average relative volatility can be obtained using a two-point geometric
mean
3
bottomHK
LK
topHK
LKavgLK K
K
K
K
The Fenske equation yields the minimum number of the equilibrium stages via the
equation
avgLK
bottomLK
HK
distHK
LK
m
moles
moles
moles
moles
Nln
ln
312 Distribution of non-key component
The relationship to be used is the component material balance
fi = bi + di
The original form of Fenskey equation written in terms of an arbitrary component i and
reference component
r
N
avgr
avgii
i b
d
b
dm
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 5
In determining the product composition values using the combination of these
two equations one takes advantages of whether a component is very volatile or not
volatile
2
avgHKavgLK
avgmean
Following sets of equations can be used to revise the estimate of the distillate
and bottom products
If light component ii bd avgmeanavgi
Reference component is heavy key then
mN
avgHK
avgi
HK
ii
b
d
fb
1
iii bfd
For heavy component avgmeanavgiii db
Reference component is the light key
mN
avgi
avgLK
LK
ii
d
b
fd
1
iii dfb
313 Calculation of minimum reflux-The Underwood equation
The equation developed by Underwood in based on the assumptions
1constant molar flow rate
2knowledge of the component at the pinch zone
Based on the degree of feed vaporization the value of θ is solved of using
qZ
av
feediavi
1
The value of (1-q) is the fraction of the feed that is vapor
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
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Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
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Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
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Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
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Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
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Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 2
Chapter-2
TYPES amp METHODS FOR DISTILLATION
21Batch Distillation ndashthe simplest form of batch still consist of a heated vessel (pot or
boiler) a condenser and one or more receiving tanks no trays or packing are provided The
feed is charged into the vessel and brought to boiling Vapors are condensed and collected
in a receiver no reflux is returned The rate of vaporization is some times controlled to
prevent ldquobumpingrdquo the charged and to avoid overloading the condenser
22Single-Stage Operation ndashFlash Vaporization
in this method a liquid mixture is partially vaporized the vapors allowed to come to
equilibrium with the residual liquid and the resulting vapor and liquid phases are separated
and removed from apparatus The liquid feed is heated in the conventional tubular heat
exchanger
23 Continuous Distillation
1 For binary system
Binary distillation is probably the most common and important of the unit
operationrsquos basic principle in binary distillation is that one component in binery
mixture is more volatile than other and concentration of this component in the
vapor phase is greater than liquid phase
2For multicomoponent system
Multicomponent distillation is more difficult than binary distillation in that
graphical techniques are not really useful except in special cases
For multicomponent calculations we use the following
1material balance
2energy balance
3 vapor liquid equilibrium
4 estimation procedure
5facilities limitations
6a well organized approach
Various kinds of devices such as random or structured packings or plates or trays are used
to bring the two phases into intimate contactThe feed material which is to be separated
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 3
into fraction is introduced at one ir more points along the column shell because of the
difference in gravity between vapor and liquid runs down the column while vapor flows up
the column Liquid reaching the bottom of the column is partially vaporized in heated
reboiler to provide boil up which is sent back to the column the remainder of the column
is withdrawn as bottomor bottom productVapor reaching the top of the column is cooled
and condensed to liquid in the overhead condenser part of this liquid is returned to the
column as reflux to provide liquid over flow The remainder of the overhead stream is
withdrawn as distillate The lighter component tends to concentrate in the top distillate and
heavier in the bottom products The result is a vapor phase that becomes richer in lighter
component as it passes up the column and a liquid phase that becomes richer in heavy
component as it cascades downward The overall separation achieved between the
distillate and the bottom depends primarily on the relative volatilities of the components
Key Components
When it is necessary to separate a mixture of many components as is frequently the
case in the petroleum industry the two key components are selected to produce a product
mixture having specified characteristics It is then likely that the keys do not fall adjacent to
each other but have an intermediate boiling component between them referred to as ldquoas a
distributed keyrdquo
Two components whose concentrations or fractional recoveries in the distillate and
bottom products are good index of the separation achieved Since the keys must be differ in
volatilities the more volatile identified as light key and less volatile as heavy key
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 4
Chapter- 3
MULTICOMPONENT DISTILLATION METHODS
31 Fenske-Underwood-Gilliland (FUG) Shortcut Method ndash
311 Fenske equation ndashthe fenske equation estimates the minimum number of theoretical
stages at the total or infinite reflux This equation assumes the relative volatility remains
constant throughout the column If the equilibrium data have some interaction between
components it is desirable to determine a third set of equilibrium data The third set of data
can be obtained by using the arithmetic mean average of the condition
3
bottomHK
LK
middleHK
LK
topHK
LKavgLK K
K
K
K
K
K
Otherwise the average relative volatility can be obtained using a two-point geometric
mean
3
bottomHK
LK
topHK
LKavgLK K
K
K
K
The Fenske equation yields the minimum number of the equilibrium stages via the
equation
avgLK
bottomLK
HK
distHK
LK
m
moles
moles
moles
moles
Nln
ln
312 Distribution of non-key component
The relationship to be used is the component material balance
fi = bi + di
The original form of Fenskey equation written in terms of an arbitrary component i and
reference component
r
N
avgr
avgii
i b
d
b
dm
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 5
In determining the product composition values using the combination of these
two equations one takes advantages of whether a component is very volatile or not
volatile
2
avgHKavgLK
avgmean
Following sets of equations can be used to revise the estimate of the distillate
and bottom products
If light component ii bd avgmeanavgi
Reference component is heavy key then
mN
avgHK
avgi
HK
ii
b
d
fb
1
iii bfd
For heavy component avgmeanavgiii db
Reference component is the light key
mN
avgi
avgLK
LK
ii
d
b
fd
1
iii dfb
313 Calculation of minimum reflux-The Underwood equation
The equation developed by Underwood in based on the assumptions
1constant molar flow rate
2knowledge of the component at the pinch zone
Based on the degree of feed vaporization the value of θ is solved of using
qZ
av
feediavi
1
The value of (1-q) is the fraction of the feed that is vapor
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
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Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
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Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
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550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
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For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
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Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
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0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
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Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
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Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
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Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
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Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 3
into fraction is introduced at one ir more points along the column shell because of the
difference in gravity between vapor and liquid runs down the column while vapor flows up
the column Liquid reaching the bottom of the column is partially vaporized in heated
reboiler to provide boil up which is sent back to the column the remainder of the column
is withdrawn as bottomor bottom productVapor reaching the top of the column is cooled
and condensed to liquid in the overhead condenser part of this liquid is returned to the
column as reflux to provide liquid over flow The remainder of the overhead stream is
withdrawn as distillate The lighter component tends to concentrate in the top distillate and
heavier in the bottom products The result is a vapor phase that becomes richer in lighter
component as it passes up the column and a liquid phase that becomes richer in heavy
component as it cascades downward The overall separation achieved between the
distillate and the bottom depends primarily on the relative volatilities of the components
Key Components
When it is necessary to separate a mixture of many components as is frequently the
case in the petroleum industry the two key components are selected to produce a product
mixture having specified characteristics It is then likely that the keys do not fall adjacent to
each other but have an intermediate boiling component between them referred to as ldquoas a
distributed keyrdquo
Two components whose concentrations or fractional recoveries in the distillate and
bottom products are good index of the separation achieved Since the keys must be differ in
volatilities the more volatile identified as light key and less volatile as heavy key
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 4
Chapter- 3
MULTICOMPONENT DISTILLATION METHODS
31 Fenske-Underwood-Gilliland (FUG) Shortcut Method ndash
311 Fenske equation ndashthe fenske equation estimates the minimum number of theoretical
stages at the total or infinite reflux This equation assumes the relative volatility remains
constant throughout the column If the equilibrium data have some interaction between
components it is desirable to determine a third set of equilibrium data The third set of data
can be obtained by using the arithmetic mean average of the condition
3
bottomHK
LK
middleHK
LK
topHK
LKavgLK K
K
K
K
K
K
Otherwise the average relative volatility can be obtained using a two-point geometric
mean
3
bottomHK
LK
topHK
LKavgLK K
K
K
K
The Fenske equation yields the minimum number of the equilibrium stages via the
equation
avgLK
bottomLK
HK
distHK
LK
m
moles
moles
moles
moles
Nln
ln
312 Distribution of non-key component
The relationship to be used is the component material balance
fi = bi + di
The original form of Fenskey equation written in terms of an arbitrary component i and
reference component
r
N
avgr
avgii
i b
d
b
dm
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 5
In determining the product composition values using the combination of these
two equations one takes advantages of whether a component is very volatile or not
volatile
2
avgHKavgLK
avgmean
Following sets of equations can be used to revise the estimate of the distillate
and bottom products
If light component ii bd avgmeanavgi
Reference component is heavy key then
mN
avgHK
avgi
HK
ii
b
d
fb
1
iii bfd
For heavy component avgmeanavgiii db
Reference component is the light key
mN
avgi
avgLK
LK
ii
d
b
fd
1
iii dfb
313 Calculation of minimum reflux-The Underwood equation
The equation developed by Underwood in based on the assumptions
1constant molar flow rate
2knowledge of the component at the pinch zone
Based on the degree of feed vaporization the value of θ is solved of using
qZ
av
feediavi
1
The value of (1-q) is the fraction of the feed that is vapor
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Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
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The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
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460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
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componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
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Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
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Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
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diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
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50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
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Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
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Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
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Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
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Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
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Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
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001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
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01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
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For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
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Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
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971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
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For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
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The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
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3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
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992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
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Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
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4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
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Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
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001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
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Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 4
Chapter- 3
MULTICOMPONENT DISTILLATION METHODS
31 Fenske-Underwood-Gilliland (FUG) Shortcut Method ndash
311 Fenske equation ndashthe fenske equation estimates the minimum number of theoretical
stages at the total or infinite reflux This equation assumes the relative volatility remains
constant throughout the column If the equilibrium data have some interaction between
components it is desirable to determine a third set of equilibrium data The third set of data
can be obtained by using the arithmetic mean average of the condition
3
bottomHK
LK
middleHK
LK
topHK
LKavgLK K
K
K
K
K
K
Otherwise the average relative volatility can be obtained using a two-point geometric
mean
3
bottomHK
LK
topHK
LKavgLK K
K
K
K
The Fenske equation yields the minimum number of the equilibrium stages via the
equation
avgLK
bottomLK
HK
distHK
LK
m
moles
moles
moles
moles
Nln
ln
312 Distribution of non-key component
The relationship to be used is the component material balance
fi = bi + di
The original form of Fenskey equation written in terms of an arbitrary component i and
reference component
r
N
avgr
avgii
i b
d
b
dm
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 5
In determining the product composition values using the combination of these
two equations one takes advantages of whether a component is very volatile or not
volatile
2
avgHKavgLK
avgmean
Following sets of equations can be used to revise the estimate of the distillate
and bottom products
If light component ii bd avgmeanavgi
Reference component is heavy key then
mN
avgHK
avgi
HK
ii
b
d
fb
1
iii bfd
For heavy component avgmeanavgiii db
Reference component is the light key
mN
avgi
avgLK
LK
ii
d
b
fd
1
iii dfb
313 Calculation of minimum reflux-The Underwood equation
The equation developed by Underwood in based on the assumptions
1constant molar flow rate
2knowledge of the component at the pinch zone
Based on the degree of feed vaporization the value of θ is solved of using
qZ
av
feediavi
1
The value of (1-q) is the fraction of the feed that is vapor
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 5
In determining the product composition values using the combination of these
two equations one takes advantages of whether a component is very volatile or not
volatile
2
avgHKavgLK
avgmean
Following sets of equations can be used to revise the estimate of the distillate
and bottom products
If light component ii bd avgmeanavgi
Reference component is heavy key then
mN
avgHK
avgi
HK
ii
b
d
fb
1
iii bfd
For heavy component avgmeanavgiii db
Reference component is the light key
mN
avgi
avgLK
LK
ii
d
b
fd
1
iii dfb
313 Calculation of minimum reflux-The Underwood equation
The equation developed by Underwood in based on the assumptions
1constant molar flow rate
2knowledge of the component at the pinch zone
Based on the degree of feed vaporization the value of θ is solved of using
qZ
av
feediavi
1
The value of (1-q) is the fraction of the feed that is vapor
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 6
point)(bubblehpoint)(dewH
condition)(feedhpoint)(dewHq)1(
ff
ff
In the determination of the thermal conditions the average pressure should be
2ombolumnbuttcolumntop
feedstage
PPP
Use of the so found in the equation
avgi
idavgim
xR
1
Rm can be determined
314 Stage-Reflux co-relation
The two widely accepted co-relations are Gilliland correlations and the Erbor-Madox
corelations each relates the minimum column operating limits to the reflux and stage
actually required The values of reflux generally used lies in the range of
00201 mR
R
Fig 41 Gilliland stage-reflux co-relation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
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Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
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Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
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Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
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Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
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Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
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Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
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001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
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Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
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For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
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Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
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Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
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For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
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The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
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Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
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Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
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Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
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Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
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550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
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abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
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For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
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Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 7
The following analytical expressions for the Gilliland stage-reflux co-relations
440ln1050
1
1
1
XB
XY
N
NNY
R
RRX
B
m
m
315 Feed location (Kirkbride equation)
The Kirkbride equation yields the ratio of the number of theoretical stages in the rectifying
section lsquomrsquo to the number of theoretical stages in the stripping section lsquoprsquo
20602
distillateHK
bottomLK
feedLK
HK
x
x
x
x
D
B
p
m
and
Npm
Feed stage can be determined
32 The Winn equation
The Fenske equation has a weakness as the relative volatility difference between column
top and bottom increase the estimated minimum number of stages get increasingly too
small The relation relates the equilibrium K of component i and reference heavy key as
i
rii KK
Where amp are constant at fixed pressure Determination of A and B The equation has
the structure of a modified Antoine equation is
460
ln
T
BAPK i
ii
P is average column pressure and T is temperature (0F)
460
ln
T
BPKA i
topii
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 8
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
Winn equation amp can be obtained
rr
ir
i
r
ii APK
APK
PK
B
B
ln
ln
1 iPAAEXP rii
The Winn equation for two minimum number of stages require the use of mole
fraction and is as follows
LK
HKD
B
LKB
D
m
LK
x
x
x
x
N
ln
ln
Using molar flow rates
LK
LK
m
LK
HKd
b
b
d
N
ln
ln
The Winn equation molar form can be combined with the column component
material balance to estimate the fractionation of the nonkey components
d 1d
b
D
B
d
bβ
d
b
fbd
i
θ1θi
HK
N
i
iii
m
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 9
componentheavy
componentlight
bd 1d
b
bfd
d
b1
d
bf
b
bd 1d
b
iii
iii
i
ii
i
iii
iii
i
ii
dfb
d
b
fd
1
Three basic energy inputoutput location within the fractionation column system The
energy associated with the feed preheats QF This energy requirement must be consistent
with the degree of feed vaporization and is obtained by enthalpy balance
FFF hHFQ
HF amp hF are in Btulb of feed The condenser duty Qc is obtained by writing an energy
balance around the condenserreflux drum
L = RD
V = D 1 R
Case 1 ndash all-liquid distillate
QC = D DV hHR 1
Case 2 ndash all vapor distillate
DVDVC HHDhHRDQ
Case -3 distillate is liquid and vapor
Qc = D R (Hv - hD) + Vapor (Hv - HD)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 10
Hv- enthalpy of vapor entering the condenser
HD - enthalpy of vapor leaving the drum accumulator
hD- enthalpy of liquid leaving the drum
with the condenser duty calculated the reboiler duty QR can be obtained as
QR=Qc+[DV HD+DLhD]+B hB-F HF
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
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Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 11
Chapter -4
Packed Tower
41 Packing Hydraulics
At low liquid flow rates the open cross sectional area of the packing is about the same as in
a dry bed The pressure drop is entirely by frictional losses through a series of opening and
proportional to the square of gas flow rate In random packing the pressure drop is due to
expansion contraction and changes of direction A portion of the gas kinetic energy is
used to support the liquid the column and the pressure drop becomes proportional to the gas
rate raised to power different The point where the packing voids fill up with liquid ie
when tower operation switches from vapor continuous to liquid continuous is termed phase
inversion For all liquid flow rates as gas flow rate is raised a point is reached when the gas
velocity begins to interfere with the free drainage of liquid The accumulation of liquid
reduces the cross section area available for gas flow and therefore accelerates the pressure
drop rise Further increase in gas rate more liquid accumulates until the liquid surface
becomes continuous across the top of packing
Efficiency flow regimes
When the liquid distribution is poor it will take more liquid to wet the entire bed Turbulent
liquid film produces good wetting of the packing and essentially contact efficiency As
liquid rate increases more vapor is entrained down the bed These drops efficiency
Because structured packing permits far less lateral movement of fluid than random
packings
Flood point
Appearance of liquid on top of the bed excessive entrainment a sharp rise in pressure
drop a sharp rise in liquid hold up and a sharp drop in efficiency flood point can be
predicted far more reliably than packing pressure drop and maximum operational capacity
Pressure drop
This is often used to specify packed tower capacity In small columns (lt3 ft in dia )
pressure drop varies with tower diameter With random packings smaller the tower
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
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For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
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Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
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Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 12
diameter the lower the pressures drop possibly due to enhancement of wall effects Dry
packed beds have a higher-pressure drop than wet ndash packed beds Pressure drop
measurement under deep vacuum (lt50 mmHg) is affected by the pressure drop and the
pressure gradient along the bed Pressure drop measurements in a pressure tower include
the static head of the vapor To obtain the actual packing pressure drop the static head
must be subtracted from pressure drop measurement Pressure drop for foaming systems
are higher than for non-foaming systems
42 Flood Point Prediction
421 Sherwood ndashEckert generalized pressure drop correlation (GPDC)
The Sherwood ndashEckert GPDC chart has been the standard of the industry for predicting
flood points and pressure drops
GPDC chart ordinate describes the balance between the vapor momentum force that acts
to entrain swarms of liquid droplets and the gravity force that resists the upward
entrainment GPDC chart abscissa is the flow parameter the ratio of liquid kinetic energy
to vapor kinetic energy
422 The Kister and Gill correlation
Zens discovered that packing pressure drop at the flood point decreases as the packing
capacity increases A simple flood point correlation
FLP =0115 70PF
this equation expresses pressure drop at the flood point as a function of packing factor
alone Once this pressure drop is known the flood velocity can be calculated The flood
velocity calculated by the Kister and Gill correlation is tolerant to inaquaracies in flood
pressure drop predictions
43 Pressure Drop Prediction By GPDC Interpolation
Interpolation of pressure drop data is more accurate than correlation prediction
Superimposing experimental data points on the curves of generalized pressure correlation
chart converts the GPDC chart into an interpolation chart Pressure drops are calculated by
interpolating the plotted pressure drop data For all charts (random structured or grid
packings) the abscissa of the correlation is the flow parameter given by
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 13
50
L
GLV G
LF
And the ordinate of correlation as the capacity parameter given by
GL
GSS uC
FP is the packing factor which is an empirical factor characteristics of the packing size
and shape
44 Packing factors
Several of the predictive methods above use a packing factor to account for the type and
size of packing With the evolutions of the general pressure drop correlation the packing
factor shifted away from the ratio ap ε3 to become an imperial constant that must be
experimentally determined for each packing
Loading point
The point of transition from the preloading regime to the loading regime is termed the
loading point It is the point where liquid hold up starts increasing with gas velocity rapid
deterioration in efficiency loading point where the flow rate at which the vapor phase
bagans to interact with the liquid phase to increase interfacial area in a packed column the
loading points occurs at 70 percent of the flood point
Pressure drop
Packed tower are designed so that the pressure drop at any point in the tower does not
exceed a recommended maximum value Maximum pressure drop criterioa for packed
tower are listed in table
Average pressure drop
Specific pressure drop can be calculated at the top of the bed and at the bottom of the bed
the average pressure drop is
25050 5050 bottomtop PPP
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
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Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
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Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
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For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
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Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
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Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
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For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
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Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
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Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
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Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
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Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
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P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 14
Type of system Maximum pressure drop in of water ft
packing
Atmospheric fractionator 05-100
Low to medium pressure fractioantor 07-10
High pressure distillation
006ltρG ρGlt 020
020lt ρGρL
019 )( 270
OHGPF
0099 )( 270
OHGPF
Vacuum distillation 001-06
Liquid holdup
Liquid holdup is the liquid present in the void spaces of packing At flooding
essentially all the voids are filled with liquids or froth Reasonable liquid holdup is
necessary for good mass transfer and efficient tower operation but beyond that it should
be kept low
Static holdup is liquid remaining on the packing after it has been fully wetted and
drained for long time The contributation of static holdup to mass transfer rates is limited
Operational holdup is liquid on the packing attributed to dynamic operation and is defined
as the difference between total holdup and static holdup
Minimum Wetting Rate
The minimum wetting rate (MWR) is the lower stability limit of packing It is liquid
below which the falling liquid film breaks up and the liquid storage causes wetting of the
packing surface Gravity and viscous forces resists dewetting the surface tension and vapor
shear forces tend to dewett the falling film The MWR therefore rises with an increase in
surface tension and liquid density and with decrease in liquid viscosity
A thumb rule cited by Ludwi
QMW =3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
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For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
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Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
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Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
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Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
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Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
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P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
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TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 15
Underwetting
Underwetting is a packing surface phenomenon which brakes up liquid film
The tendency of liquid film to break is expressed by a contact angle A contact angle of
zero indicates perfect wetting an angle of 1800 indicates no wetting
The contact angle depends both on surface and a liquid and is a strong function of
composition Changing a material and surface roughness of the packing may significantly
affect the efficiency in system susceptible to underwetting
45 The HETP concept
The concept of HETP (height equivalent to theoretical plates) was introduced to
enable to comparison of efficiency between packed and plate columns HETP is defined as
HETP = Hn
A similar HETP value can be obtained for plate column if the tray spacing is known
HETP (trayed column) = 100 timesSE
The HETP approach is suitable for multicomponent systems while HTU approach is
difficult to apply for this
HETP prediction
Because there are only few variables that significantly affect HETP of random
packings For small diameter column the rule of thumb presented by Frank Ludig Vital
et al are identical The more conservative cause predicted from
HETP =15 dp helliphellipfor Pall rings or similar high efficiency packing
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 16
Chapter -5
Distillation Design
Problem statement-
A butane-pentane splitter is to be designed to process 4200 lbhr of C3 ndashC5 feed subjected to
specifications of
1maximum 3 of i-C5 in the distillate
2maximum 1 of C4 in the bottom product
The feed sink will be air (process design temperature) to be 130 0F
Components Wt molwt lbh molh
C3 5 441 210 4762
i-C4 15 581 630 10843
C4 25 581 1050 18072
i-C5 20 721 840 11651
C5 35 721 1470 20388
4200 65716
Solution-
Feed composition
Components lbgal(60F) galh Vol mol
C3 422 4976 592 725
i-C4 469 13433 1397 165
C4 487 21501 2563 275
i-C5 520 16154 192 1773
C5 525 28000 328 3102
Total 84124 100 100
Average molecular weight 650716
4200
= 6391
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 17
Average liquid density = 420065716
= 4993lbgal
x = mass of c4 in the bottom(i-wt)
y =mass of i-c5 in the distillate(3 wt)
51 Component Split
Assuming that the C3 and i-C5 have negligible concentration in the bottom and C5 has
negligible concentration in the distillate
Components F D B
C3 210 210 0
i-C4 630 630 0
C4 1050 (1050-x) x
i-C5 840 y (840-y)
C5 1470 0 1470
Total 4200 1890-x+y 2310+x-y
F =B+D
4200 =2310 + x ndashy +1890 ndashx + y
Distillate specification 3 in of i-c5 in distillate
yx
y
18900030
567 ndash 003 x -097 y =0
003 x + 097 y =567
Bottom specification 1 C4 in the bottom
003 yx
x
2310
231 -001 x + 001 y = x
099 x + 001 y = 231
x = 2275
y = 5775
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 18
Components D lbh B lbh D lbmolh B lbmolh
C3 210 0 4762 0
i-C4 630 0 10843 0
C4 102725 2275 1768 039
i-C5 5725 78225 0801 1085
C5 0 1470 0 20388
Total 1925 2275 34086 3163
52 Dew Point and Bubble Point calculation
1 The distillate and reflux will be a bubble point liquid The criteria for evaluation of
the bubble point condition are
1 like an air fin condenser to liquefy the distillate and reflux The criteria of
drum temperature will be assumed to be 130F ( design temperature for air is
about 120F
2 the bubble point design equation with temperature specified
01 ii xK
Average molecular weight of distillate
Components xid Ki
C3 01397 21
i-C4 03181 10
C4 05187 073
i-C5 00235 033
C5 0 027
For fixed temperature of 130F bubble point pressure is to be determined
4656 wtmolxid
9980 iDi xK
Pestimated = Pi-c4 = 120 lbin2
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 19
001
9980120calculatedP
= 1197 lbin2 (abs)
The result of distillate bubble point calculation is
T = 130 0F
P = 120 lbin2
The condition at the top of the column must be evaluated since the fractionator has a
total concentration and an equilibrium stage The criteria for evaluation of the dew
point condition are
Assumption of the pressure drop through the total condenser of 25 lbin2Thus the
pressure at the top of the column is established as
P = 120 lbin2 + 25 lbin2
P = 1225 lbin2
Dew point
01
i
i
k
y
Plk =1225 lbin2 T= 1320F
Components yi Ki1320
F Ki1450
F
C3 01397 220 240
i-C4 03181 100 115
C4 05187 073 085
i-C5 00235 035 042
C5 00000 028 033
For T =1320F
01
i
i
k
y
Kic4 = 1160 and Tcal =1450F
For T =1450F
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 20
01
i
i
k
y
The result of column top dew point calculation
T =1450F
P = 1225 lbin2
The column bottom condition Column ΔP =5 lbin2
The column bottom pressure
P = 1225 + 50 = 1275 lbin2
The bubble point design equation
ΣKiXi=10
Components B(mol) X
C3 0 0
i-C4 0 0
C4 0392 00124
i-C5 1085 03430
C5 20388 06446
3163 100
Average molecular wt = 6331
22750 =7193
The characteristic component is i-c5 an estimated bottom temperature is obtained
Components Xi Ki2380
F Ki2150
F
C3 0 38 45
i-C4 0 355 265
C4 00124 1925 205
i-C5 03430 10 1075
C5 06446 087 094
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 21
For T = 238 0F
ΣKiXi=0927
KHK = 108 Tcal =245 0F
For T =245 0F
ΣKiXi=100
The result of column bottom bubble point calculation
T =245 0F
P =1275 lbin2
53 Determination of the key component
Using the heavy key as column reference key The separation is clearly between
butane and isopentane
Reference component =i-C5
Key component
LK =C4
HK =iC5
The average relative volatility data for the column will be generated using three-point
geometric average
3321 avg
Point 1 ndash top of fractionation column
Point 2 ndash at the reboiler
Point 3 ndash arithmetic mean of condition at 1 amp 3
T2 = 05 [ T1 + T2 ] = 05 [ T1 + T2 ]
T2 = 05 [ 145 + 245 ] = 195 0F
P2 = 05 [ P1 + P3 ] = 05 [ 1225 +1275 ]
P2 = 125 lbin2
variable Point 1 Point 2 Point 3
T oF 145 195 245
P lbin2 1225 125 1275
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 22
Components Point 1 Point 2 Point 3
Ki αi Ki αi Ki αi αavg
C3 24 571 335 493 45 419 49
i-C4 115 274 175 257 25 237 256
C4 085 202 135 199 205 191 197
i-C5 024 100 068 100 1075 100 100
C5 033 079 058 085 094 087 084
54 Shortcut Method
541 Minimum stages at total reflux-the Fenske equation
LKavg
BLk
HK
DHK
LK
m
x
x
x
x
Nln
ln
Fi = bi + di
avgmeanavgiiir
rNavgi
i dbb
d
b
d for min
mN
avgHK
avgi
HK
ii
b
d
fb
1
or when ii db meanavgavgi
mN
avgi
avgLK
LK
ii
d
b
fd
1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 23
971ln
01240
3430
02350
51870ln
mN
4619mN
2
avgLKavgHKmean
2
001971
= 1485
For propaneC3
meanC 3
7624
904
3
3
C
C
f
4619
001
904
85010
80101
76243Cb
hmold
hmol
C 7624007624
1091
3
5
For isobutene(i-C4)
84310
562
4
4
4
iC
Ci
meanCi
f
4619
1
562
8500
80101
843104iCb
hmol 020
823104iCd
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 24
For butane (C4)
07218
971
4
4
C
C
meanavgi
f
4619
001
971
8510
80101
072184Cb
hmold
d
hmolb
C
C
C
68817
392007218
3920
4
4
4
For isopentane (i-C5)
meanavgiC
iCiC hmolf
5
5565111001
Hence
4619
001
971
6817
39201
651115iCd
hmolb
hmold
iC
iC
8510801065111
8010
5
5
For pentane (C5)
hmolb
hmold
d
C
C
C
meanavgC
C
105320
2850
840
971
6817
39201
38820
840
5
5
5
5
5
4619
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 25
The calculated data in the table
Components Fi(lbmolh) Di(lbmolh) Bi(lbmolh)
C3 4762 4762 0
i-C4 10834 10823 002
C4 18072 17680 0392
i-C5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Checking
Maximum 3wt of iC5 in the distillate
9772
1004656
172
35134
8010
wt
Maximum of 1 wt C4 in the bottom
011
1009371
158
36531
3920
wt
The set of specification were not met The parameter reevaluated
Again performing same calculations
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 1050-x x
i-C5 840 y 840-y
C5 1470 2055 144945
Total 190939-x+y 229061+x-y
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 26
3658
5522
612290100
1
391909100
3
y
x
yx
x
yx
y
Components Fi(lbh) Di(lbh) Bi(lbh)
C3 210 210 0
i-C4 630 62884 116
C4 1050 102745 2255
i-C5 840 5836 78164
C5 1470 2055 144945
Total 4200 194520 224580
Components F(lbmolh) D(lbmolh) B(lbmolh)
C3 4762 4762 0
i-c4 10834 10823 002
C4 18072 17680 0392
i-c5 11652 0801 10850
C5 20388 0285 20103
Total 65716 34351 31365
Column operating condition
Distillate bubble point calculation on with temperature specified at 130 0F
Components D (lbmolh) K120 (lbin2)
C3 4762 210
i-C4 10823 10
C4 17680 073
i-C5 0801 033
C5 0285 027
Total 34351
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 27
992036334
07634
001
ii
iiii
xK
D
dKxK
Condition of the distillatereflux before 130 0F amp 120 lbin2overhead or column top
conditions are found by dew point calculation at the specified pressure of 1225lbin2
Components D (lbmolh) K1450
F K148 0
F
C3 4762 24 2425
i-C4 10823 116 1175
C4 17680 084 087
i-C5 0801 042 0425
C5 0285 033 034
01D
K
d
K
y i
i
i
i
For T=145 0F
018136334
9934
i
i
K
y K=1175 Tcal=148 0F
For T=148 0F
997036334
24334
i
i
K
y
Conditions of column overhead are revised to 148 0F and 1225lbin2column bottom
conditions are found by way of bubble point calculation
Components B(lbmolh) K2450
F
C3 0 45
i-C4 002 255
C4 0392 205
i-C5 10850 1075
C5 20103 094
Total 31365
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
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62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
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Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
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001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
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08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 28
Design equation
001B
bKxK ii
ii
For T =245 0F
00139331
39831ii xK
At column midpoint condition
2
0
1255127512250
519624514850
inlbP
FT
Summery of operating condition
Point 1 Point 2 Point 3
Temperature 148 1965 245
Pressure lbin2 (abs) 1225 125 1275
Equilibrium K data for column midpoint condition
Point 1 Point 2 Point 3
Components Ki i Ki i Ki i avgi
C3 2425 571 34 486 45 419 488
i-C4 1175 276 18 257 255 237 256
C4 087 205 138 197 205 191 198
i-C5 0425 100 07 10 1075 10 10
C5 034 08 06 086 094 087 084
Fenske equation
3919
001
981ln
3880
84210
8090
68417ln
m
m
N
N
Separation of non key component
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 29
4912
100198
2
avgLKavgHK
mean
molh09220bmolh 2920d
molh38820f840
)(CPentane
molh8090dmolh 84210b
molh65111f001
)C-(itan
68417dmolh 3880b
molh07218f981
)(CButane
hmol 82210d h mol0210b
hmol84310f562
)C-(iIsobutane
molh76240007624d
molh000molh101882
001
884
84210
80901
7624
7624f884
)(Cropane
C5C5
C5C5
5
C5-iC5-i
C5-iiC5
5
C4C4
C4C4
4
iC4iC4
iC4iC4
4
33C3
5
39193
C3C3
3
lblb
lb
lblb
lb
eIsopen
hlbmollb
lblb
lb
lbbf
lblbb
hmol
P
CC
C
Components Feed (lbmolh) Distillate (lbmolh) Bottom (lbmolh)
C3 4762 4762 0000
i-C4 10843 10822 0021
C4 18072 17684 03880
i-C5 11651 0809 10842
C5 20388 0292 20096
Total 65716 34369 31347
Maximum value of 3 wt of i-C5 in distillate is required
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 30
Calculated value =
wt 3
1004956
172
36934
8090
Maximum value of 1 wt of C4 in bottom is required
Calculated value
wt 1
1009163
158
34731
3880
Conditions are satisfied
542 Component split by Winn equation
The Fenske equation has a weakness as the relative volatility difference between
column top and bottom increase the estimated minimum number of stages gets
increasingly too small
460
1
460
1
lnln
bottomtop
bottomitopi
i
TT
PKPKB
460
ln
T
BAPK i
ii
110 irHKi PAAi
r
ii B
B
Components KTop148 F Kbottom245 F
C3 2425 450
i-C4 1175 255
C4 087 205
i-C5 0425 1075
C5 034 094
For P=125 lbin2
For butane (C4)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 31
550594460148
)271263()42525122log(
271263
460245
1
460148
1545127log42525122log
4
4
C
C
A
B
Heavy component is iso-pentane( i-C5)
955824460148
)711857()42505122log(
680010717185
271263
711857
460245
1
460148
1
07515127log4250125log
5
4
5
Ci
C
Ci
A
A
B
311344
)125(10
10)1680010()955824550594(
1
irHKi PAAi
Components Bi Ai θi βi
C3 -126327 45509 068001 43113
i-C4 -156377 473016 084177 24069
C4 -172167 48593 092677 191988
i-C5 -185771 49558 100000 10000
C5 -202840 49558 109189 086704
5339
919881log
)369348090(
)3473484210(
)347313880(
)3693468417(log
m
m
N
N
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 32
abvg
1
bdcomponent
orlightif
D
B
d
bb
d
HK
N
i
im
d
b1
fd
2dbkeyheavy
1
avgHKLKif
b
df
b
componentlight propanefor
5
032068
9533
101976
09120713402
4311
b
d
7624
0001097611
76245
bfd
b
For isobutene (i-C4)
f =10843 θ =0842 β =2407 (light component)
lh10821lbmo
002210843d
h0022lbmol
494151
10843b
4941509120713402
2407
b
d08417108417
9533
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 33
For Butane (C4)
f =18072 β=191988θ=092677
h0388lbmol
455771
18072b
4557709120713402
191988
b
d0926771092677
9533
d=18072-0388
=17684 lbmolh
For Isopentane (C5)
f =11651 β =100 θ =100
111
5339
91207040213
00001
b
d
=007461
βltβavg
)0746101(1
65111
d
= 0809 lbmolh
b = 11651-0809
=10842 lbmolh
For Pentane (C5)
f =20388 lbmolh β= 086704 θ =109189
0918911091891
5339
91207040213
867040
b
d
=0014959
βltβavg
)01495901(1
38820
d
= 0300 lb molh
b=20388-03
=20088
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 34
Components Feed lbmolh Distillate lbmolh Bottom lbmolh
C3 4762 4762 000
i-C4 10843 10821 0022
C4 18072 17684 0388
i-C5 11651 0809 10842
C5 20388 03 20088
65716 34376 3134
Components Feed lbh Distillate lbh Bottom lbh
C3 210 210 000
i-C4 630 62872 128
C4 1050 102745 2257
i-C5 840 5836 78164
C5 1470 2163 1448348
4200 194602 2253818
543 Calculation of Rm
From Underwood equation
qx
i
iFi
1
Components Flbmolhr xif xid αi
C3 4762 00725 01386 488
i-C4 10843 01650 03149 256
C4 18072 02750 05145 198
i-C5 11651 01773 002335 100
C5 20388 03102 00085 084
65716 1000 1000
Feed is at boiling conditions since q =1
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 35
0840
31020840
1
177301
981
27500981
562
16500562
884
07250884
θ =1284
from this value of θ
avgi
idavgim
xR
1
11284840
00850840
12841
023501
1284981
51450981
1284562
31490562
1284884
13860884
mR
Rm=1185
R=15 Rm
=15times1185
=17775
X=1
R
RR m
X=177751
185177751
=02133
From GillilandrsquoS correlation Y=1
N
NN m =042
We know the value of Nm 4201
5339
N
N
N=178 =18 stages
Feed location can be known by the use of Kirkbride equation
2
)376348090(
)34313880(
)07218(
)65111(
37634
34312060log
F
F
p
m
687890p
m
817 pm
m = 725=8
p =1054 =11
Feed is introduced on eight stage from top
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 36
Chapter- 6
PACKED COLUMN DESIGN
61 Stage AnalysisThe data shown in table are typical data generated by commercial simulation
Vapor liquidStage Temperature0F lbhr CFS
ft3sV
lbft3
Lbhr GPM
galminL
σ
dynecm
μ
cP
1 1349 00 00 00 3655 1423 3202 6867 0114
2 1474 5501 12050 12683 3720 1447 3204 6738 01132
3 1548 5566 12049 12831 3724 1447 3208 6699 01128
4 1609 5571 11987 12909 3707 1438 3214 6684 01130
5 1668 5553 11889 12974 3693 1430 3220 6665 01135
6 1726 5539 11794 13045 3689 1426 3224 6632 01142
7 1779 5535 11716 13122 3691 1426 3226 6590 01149
8 1824 5537 11650 13199 8032 310471 3226 6544 01156
9 1873 5678 11794 13373 8126 3142 3224 6507 01153
10 1917 5772 11871 13506 8201 3171 3224 6479 01151
11 1961 5847 11915 13631 8275 3201 3223 6447 01152
12 2010 5921 11946 13768 8360 3235 3222 6406 01156
13 2064 6006 12152 13928 8475 3274 3220 6348 01162
14 2122 6103 12013 14111 8574 3321 3218 6295 01170
15 2179 6220 12070 14310 8701 3374 3215 6236 01180
16 2232 6347 12148 14512 8829 3428 3211 6178 01191
17 2280 6475 12234 14701 8947 3477 3208 6128 01201
18 2321 6593 12317 14868 2354 91599 3204 6087 01212
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 37
62 Flood Point
15 inch pall ring will be used throughout the column for this packing the flood point can
be determined by interpolation
A-flood point by GPDC [generalized pressure drop correlation] interpolation
2
2
6593
5571
fthrlbA
G
fthrlbA
G
TBottom
TTop
Liquid flowrates ( 2 fthrlb )
LTop =TA
3724
LBottom = TA
8947
Vapor density( 3 ftlb )
48681
31991
BottomG
TopG
Liquid density ( 3 ftlb )
2432
2632
BottomL
TopL
1 Flow parameter
L
GLV ρ
ρ
G
LF
Top 05
LV 3228
13199
5571
3724F
1352110FLV
Bottom LVF =
2432
48681
6593
8947
= 029142
2 Capacity parameter from graphical correlation
Top =152
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 38
Bottom =119
3 Viscosity of the liquid L (cP)
Top L =01128 (cP)
Bottom L =01151 (cP)
4 Kinematic viscosity
=
L
L
462
Top =
2632
11280462
Top = 0218187
Bottom =
2432
11510462
Bottom = 022277
5 Packing factor ( 1ft )
Top FP = 40
Bottom FP = 40
6 Vapour capacity factor CSFI(fts)
Capacity parameter = CSFI FP05 005
Top 05050SFI 2181040
921C
Top SFIC =02593
Bottom 05050SFI 2181040
191C
Bottom 20280CSFI
63 Flood point by the Kister amp Gill correlation
1 FTP packed bed specific pressure drop at flood point
FTP =0115 70PF
Top FTP =0115 7040
=1521
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 39
Bottom FTP =1521 inch of H2O per ft
2 Flow parameter
Top FLV =0135211
Bottom FLV =029142
3 Capacity parameter at flood point
Top =152
Bottom = 119
4 CSFl vapor capacity factor at the flood point
CSFl = capacity parameter
05050
1
PF
Top CSFl =02593
Bottom CSFl =02028
64 Diameter calculation
1 Vapor capacity factor Cs design (nonderated) fts
The column will be designed for 75 flood capacity
SFlS CC 750
Top CS = 075 02593
=0194475
Bottom CS = 075 02028
Bottom CS = 01551
2 CS vapor capacity factor (derated )fts
= 09 CSdesign
Top CS = 09 01944
Top CS =017496
Bottom CS =09 01521
Bottom CS =013689
3 Vapor superficial velocity based on the cross section of empty column u (fts)
GL
G
ss
ρρ
ρ
(derated)Cu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 40
Top su =
319912632
31991
174960
Top su =084737
Bottom su =
486812432
48681
136890
Bottom su = 062257
4 Vapor flow rate CFS ft3s
Top CFS =1205 ft3s
Bottom CFS =12316 ft3shellipfrom table
5 Tower area ft2
AT = s
T u
CFSA
Top AT = 847370
2051
Top AT =1422 ft2
Bottom AT = 622570
23161
Bottom AT =19782 ft2
6 Tower diameter ft
1587ftD
π
197824D
13455ftD
π
14224D
π
A4
BottomT
BottomT
TopT
TopT
TT
D
65 Diameter calculation using the maximum pressure drop criterion
1 L
G
calculation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 41
Top L
G
=2632
31991
= 00409
Bottom L
G
=2432
48681
= 004611
2OH
L
2
calculation
Top ( OHL 2 )=
4362
2632
= 05167
Bottom ( OHL 2 ) =
4362
2432
= 05164
3 FP packing factor
Top FP = 40
Bottom FP =40
4 Maximum pressure drops recommended for packed column with random packing
1902
70max
OH
LPFP
helliphelliphelliphellipfor 006 20L
G
Top maxP = 019 5167040 70
Top maxP = 12984helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
Bottom maxP = 019 5164040 70
Bottom maxP =12977helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
5 Surface tension dyne
Top =6544 cmdyne
Bottom =6128 cmdyne
6 Vapor capacity factor Csmax (fts)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 42
P
s
FCP
3342maxmax
Top 12984 =
5446
403342maxsC
Top maxsC =02634
Bottom 12977 =
1286
403342maxsC
Bottom maxsC =025628
7 Maximum vapor superficial velocity usmax
maxsC = usmax
GL
G
Top usmax =
319912632
31991
26340
= 12752
Bottom usmax =
486812432
48681
25620
=11651 fts
8 Tower area AT (ft2)
AT =smaxu
CFS
Top AT =27521
2051
Top AT =09449
Bottom AT = 16511
23161
= 1057 ft2
9 Tower diameter (ft)
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 43
TA4TD
Top TD =109685 ft
Bottom TD =116 ft
The flood point and the maximum pressure drop criteria gave comparable tower
diameter The more conservative criteria gives diameter of 134 and 158 ft for top and
bottom sections of tower respectively As the diameter for the top and bottom sections
are not much differentThe preliminary column diameter is the larger for the two
column section ie 158 ftThis diameter is normally rounded to the next nearest half
footA diameter of 158 is for closer to 158 than 2ftThe column is operated at high
pressure shells are expensiveTherefore the preliminary column diameter 2ft
66 Bed height calculation
1 Packing diameter dP in
Top dP = 15 in
Bottom dP =15 in
2Tower diameter DTft
Top DT = 2 ft
Bottom DT =2 ft
3Ratio of
12
d
D
T
T
Top
12
d
D
T
T =51
212
=16
Bottom
12
d
D
T
T =51
212=16
4HETP ft height equivalent to theoretical plate
HETP = Pd51 (for pall rings)
Top HETP = 2525151 ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 44
Bottom HETP = 2525151 ft
5Number of stages
Top N = 8
Bottom N = 10
6Total packed height
HETPNZ
Top 182528 Z ft
Bottom 52225210 Z ft
67 Column sizing second trial
1Tower diameter
Top DT = 2 ft
Bottom DT = 2 ft
2Packing diameter dPin
TopdP =15in
Bottom dP =15in
3Tower area AT
4
2T
T
DA
Top4
22
TA
=31415 ft2
Bottom 4
22
TA
=31415 ft2
4Vapor flowrate CFS ft3s
Top CFS = 1205 ft3s
Botttom CFS =12316 ft3s
5Vapor superficial velocity usfts
design T
s A
CFSu
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 45
Top 3835014153
2051su fts
Bottom 3920014153
23161su fts
6 Vapor capacity factor Csfts
Top sC = us
GL
G
Top sC =03835
319912632
31991
Top sC = 0079209 fts
Botttom sC =03920
486812432
48681
Botttom sC =008619 fts
68 Average bed pressure drop calculation
Most method for pressure drop calculation assume the column handles a
nonuniform mixture they do not strictly apply to the high pressure column
1 P calculation in H2O per ft
P =
425033 sP CFP
Top P =5446
079204033 4250
= 007255 helliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft Bottom
P =00949helliphelliphelliphelliphelliphelliphelliphelliphelliphelliphellipin H2O per ft
2 Stage 8 amp 9 calculation
Top 31991G lbft3
Bottom 33731G lbft3
Top L 3226 lbft3
Bottom 2432L lbft3
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 46
3CFS vapor flowrate ft3s
Top CFS = 11652 ft3s
Bottom CFS =117944 ft3s
4AT tower area ft2
Top AT =31415 ft2
Bottom AT =31415 ft2
5Superficial Velocity us fts
T
s A
CFSu
fts0375431415
117944uBottom
fts0370831415
11652uTop
s
s
6Cs Vapor Capacity factor
fts078090337312432
3373137540CBottom
fts07580319912632
3199137080C
s
s
Top
uCGL
Gss
7Surface Tension (σ) of liquid dynecm
Top σ = 6544 dynecm
Bottom σ = 6507 dynecm
8Packing Factor (FP)
Top FP = 40
Bottom FP = 40
9ΔP in of H2O per ft
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 47
070505076
0780904033
0652905446
075804033
σ
CF33ΔP
4250
4250
24s
05P
PBottom
PTop
10Average ΔP in of water per ft
25050 )5050( bottomtop PPP
25050 0652905007255050 P
Top P = 006887 in water per ft
Bottom P = 25050 07050500949050
P =00822 in water per ft
69 Maximum pressure drop by interpolation
1Flv = flow parameter
Top Flv =0135211
Bottom Flv = 029142
2Cs vapor capacity factor fts
Top Cs =0079209
Bottom Cs = 008619
3 kinematic capacity Cs
Top =0218187
Bottom =022277
4FP = packing factor ft-1
Top FP = 40
Bottom FP =40
5Capacity parameter at design
05050PF SC
Top = 04642
Bottom =05056
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 48
6 P at design in H2O per ft
P top = 008 in H2O per ft = 008
P bottom = 009 in H2O per ft = 009
610Minimum wetting rate
1GPM at design
Top =31037 galmin helliphellip For 8th amp 9th stages
Bottom = 3142 galmin
2GPM turndown
GPM 60
Top = 18622 galmin
Bottom = 18852 galmin
As 60 of turndown expected
3GPMft2 at turndown
Top 14153
62218 = 592
Bottom = 0077614153
85218
Since these rates are well above 3GPMft2 the column operate well above minimum
wetting
611 Total pressure drop
1ΔP average in H2O per ft
Top = 006887
Bottom = 00822
Top total ΔP = ΔP top height
= 006887 18
= 123966 in H2O
Bottom ΔP = 00822 225
= 1849 in H2O
2Total packing pressure drop = 1849 +123966
= 3089 in H2O
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 49
612 Design column summery
1Tower diameter (ft)
Top = 2 ft
Bottom = 2 ft
2Number of packed beds
Top = 1
Bottom =1
3Total packed heightft
Top = 15 in metallic pallR ring(M)
Bottom = 15 in 15 in metallic pallR ring(M)
613 Percentage flood
CSFlderated = 09 CSFl
Top = 09 02593
= 023337
Bottom = 09 02028
= 018252
flood = deratedSFl
s
C
designC
100
Top flood = 233370
0792090100
= 3394
Bottom flood = 182520
086190100
= 4722
614 Performance summery
1 flood
Top = 3394
Bottom = 4722
2Pressure drop in of H2O per ft
Maximum expected
top = 007255
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 50
bottom = 00949
Maximum allowable
Top = 12984
Bottom = 12977
Bed average
Top = 006887
Bottom = 00822
3Total bed pressure drop in of H2O
Top =123966
Bottom = 1849
4Number of theoretical stages
Top = 8
Bottom = 10
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 51
Chapter-7
DETERMINATION OF CONDENSER AND REBOILER
HEAT LOAD
Enthalpy data for calculations of heat load are
Vapor enthalpy Btulb at 125 lbin2
Component 100degF 200degF 300degF
C3 3075 3550 4070
i-C4 2775 3260 3790
C4 2980 3460 4000
i-C5 2880 3280 3820
C5 2800 3360 3790
Liquid Enthalpy Btulb
Component 100degF 200degF 300degF
C3 1700 2280 2880
i-C4 1540 2125 2725
C4 1600 2230 2850
i-C5 1480 2110 2775
C5 1525 2150 2800
In order to calculate the energy requirement for preheater the fed bubble point must be
deteremined Th feed pressure is 125lbin2 the final iteration is summerised below and the
bubble point is at 1750F
Component Feedlbmolhr K
C3 4762 29
i-C4 10843 1475
C4 18072 1125
i-C5 11651 055
C5 20388 045
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 52
001ii xK
The column feed at 1720Fthe bubble point found by linear interpolation of feed enthalpy at
1000F this last enthalpy is found using the feed rates
Temperature0F hfeed 610 Btuhr
100 06492
172 08364
200 09092
For the reflux ratio of 17775 calculate the condenser duty the enthalpy of the distillate
liquid and overhead vapors must be determined at their respective condition
Condenser duty
1)( 130148 RhHQ liqvapC
The enthalpy data at 100 and 2000F were given from that 0F hdist times106 Btuh Hvap times106 Btuh
100 03088 05681
130 03444 -
148 - 06128
200 04275 06021
177751103444062180 6 CQ
= 07704times106 Btuh
An overall energy balance yields the reboiler duty
hfeed172 + Qrebioler = hdistillate130 + Qcondenser +hbottom245
The bottom enthalpy must be found before the reboiler duty The bottom flow rates are
calculated The liquid enthalpy is given earlier0F hbottomtimes106 Btuh
200 04817
245 05482
300 06294
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 53
08362times106 + Qreboiler =03444times106+07704times106 +05482times106
Qreboiler =08268times106 BtuhThe amount of stripping vapor generated by the reboiler is now calculated The reboiler is
assumed to be equilibrium stage the bottom temperature is 2450 using the enthalpy data for
the vapour is given above at 2000F and 3000F the molar enthalpy is calculated from
ivapi HwtmolyH
0F Hbottom Btulbmol
200 23897
245 25426
300 27294
Since the majority of energy supplied to the reboiler is used to generate the stripping vapor
the vapor rate can be estimated by calculating the latent heat
λ= enthalpy of vapor- enthalpy of liquid
vapor enthalpy = 25426 Btulbmol
liquid enthalpy =34731
1054820 6
= 17488 Btulbmol
λ = 25426-17488
= 7938 Btulbmol
Stripping rate =
reboilerQ
7983
1082680 6estimatedV
= 10355 lbmolh
= 1035571722
= 7426681 lbhr
Mass balance around the reboiler
BVL
= 10355 + 31345
=1348 lbmolh
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 54
The bubble point and the enthalpy of stream L are needed for the balance Pressure is 1275
lbin2 and the initial assumed temperature is 2450F
ComponentiL lbmolhr K245 K242
C3 0 45 440
i-C4 0194 255 250
C4 2556 205 200
i-C5 43098 1075 105
C5 72208 094 092
At 2450F
016105611894119 ii xK
At 242 0F
993008611828117 ii xK
Enthalpy at 2420F
Temperature0F Enthalpy Btulbmol
200 15336
242 17310
300 20036
Material balance
BVL and B=31347 lbmolhr
Energy balance
bottomreboiler hBVQL 2542617310
Bhbottom = 05482times 106 Btuhr
34731VL
17310 L -25426V =-02786times106
Solving two equations
5132L lbmolhr
V =10118 lbmolhr
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 55
Chapter-8
CALCULATION OF THE THICKNESS OF SHELL AND COST ESTIMATION
P =150 lbin2 = 11376 Nmm2
Di = 2ft s
Total column length 52 ft
mm
CPJf
DPt t
sh
32261371850952
66091371
2
Weight of head = 370387 N
Shell thickness at different height
1 Axial stress fap = Ct
DiP
s 4
= 232264
66091371
= 4009 N
2 for compressive stress due to the weight of shell up to distance lsquoXrsquo
shelloftioncross
ofshellwtf as sec
22
22
4
4
io
io
DD
XDD
=
622
322
106609244622
10776609244622
X
= 77times10-3 timesX Nmm2
3 FD compressive stress due to weight of insulation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 56
Ct
Xlengthunitperinsolutionofweightf
SD
mD
1023226
0770
X
= 567095 times 10-4times X Nmm2
4 Compressive stress due to liquid in the column up to height X
Compressive stresses due to liquid in the column up to height X
CtD
Xpackingliquidweightf
smliq
232266609
4071113490
X
= 18369 X Nmm2
CtD
Xheightunitperattachmentofweightf
smd
232266609
140026700
X
df =322 +01691X
Total compressive dead weight stress at a height X from equation
22301422
2231691083691106751077 43
Xf
X
dx
bending moment due to the wind load
2
70 20 XDP
M wwZ
2
620130070 2X
= 2821X2
Stream due to the wind load
CtD
PXf
so
wwX
241
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 57
2322624622
130041 2
X
= 02154 Nmm2
Tensile stress due to the sesmic load
Momentum due to sesmic load
2
2 3
3 H
XHXWCM SX
2
2
8415
84153
3
187581479480 XXM SX
9250
524728947 2 X
X Nm
CtD
Mf
s
SXSX
204
23226246224
10
2
3
SXM
=281314
SXMNmm2
SXf = 68077 timesX2
9250
5447 X Nmm2
To determine value of X combined stresses on the upward side as
dxapSXt ffff max
= 22301422094002710291 2 XXX
maxtf = 783601432291 2 XX
The equation
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 58
004D
41
m0
2
alls
i
ss
w fCt
DP
Ct
Xwtsdead
CtD
XP
85036009402230142221540 2 XX
X = 4521 mX = 147 ft
The thickness will be same for the entire height of the column the compressive stress as for
apdxSXwXC ffforff max
= 129 094022301422027102 XXX
= 129 8736987112 XX
The tower height is 1584 m
87368415987118415291 2 Cf
= 2512 Nmm2
This is well within the permissible stream for elastic stability
Cost estimationFrom graph ( Appendix -A) for 24 in diameter packed bed distillation column cost is 9000 $Cost of Packing is 20 $ft3soTotal volume of packed region in a column is
4
2 LDVP
4
54022
PV
= 12717 ft3
Total cost of packing =1271720
=2543 $
Total cost of column = 9000+2543
=115434 $
Cost in rupees = 1154350
= 577170 Rs
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 59
CONCLUSION
Distillation calculation shows the results are feasible from the literature data
Number of stages and reflux ratio is slightly varies with the different methods There are
eighteen theoretical stages 11775 are obtained by shortcut method Relative volatility of
component changes at different stages By considering this phenomenon the Winn equation
is used for the calculation of component distribution In the calculation of packed bed
limitations of pressure co-relations are systematic rather than random It has been
demonstrated that a co-relation that gives excellent stastical fit to experimental data can
give poor prediction for many situations commonly encountered in industrial practice
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 60
APPENDIX -A
Distribution coefficients (K=yx) in light hydrocarbon system high temperature
ranges
Figure1 Depriesterrsquos chart
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 61
Cost Of Packed Bed Distillation Column
4
6
8
10
12
14
0 5 10 15 20 25 30 35 40
Column diameterin
Co
st $
100
0
Figure 2 Cost of Packed bed distillation column
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 62
APPENDIX B
program fenskeimplicit nonerealc1c2c3c4c5k1k2k3k4k5dlkbhkalphalka1b1frealalpha1alphahkalpha2alpha5d1fdlkfdhkfd2fd5fb1fblkfrealbhkfb2fb5ff1flkfhkf2f5d1d2d3d4d5bb1b2b3b4b5realdtotalbtotalxlkdxhkdxlkbxhkbnminzyalphalkavgprinttype value of mole fraction of component in feedreadc1c2c3c4c5printType the value of feed flow ratereadfprinttype value of distribution coefficient of each componentreadk1k2k3k4k5printType the fraction of light key component in distillatereaddlkprintType the fraction of heavy key component in bottomreadbhkalphalk=k3k4alpha1=k1k4alpha2=k2k4alphahk=k4k4alpha5=k5k4printalpha1=alpha1printalpha2=alpha2printalphalk=alphalkprintalphahk=alphahkprintalpha5=alpha5z=dlk(1-dlk)y=bhk(1-bhk)a1=log10((1-bhk)bhk)b1=log10(zy)log10(alphalk)
printa1=a1printb1=b1d1f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))d2f=10(a1)alpha2(b1)(1+10(a1)alpha2(b1))dlkf=10(a1)alphalk(b1)(1+10(a1)alphalk(b1))dhkf=10(a1)alphahk(b1)(1+10(a1)alphahk(b1)) d5f=10(a1)alpha1(b1)(1+10(a1)alpha1(b1))printdf values= d1fd2fdlkfdhkfd5f
b1f=1(1+10(a1)alpha1(b1))b2f=1(1+10(a1)alpha2(b1))
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 63
blkf=1(1+10(a1)alphalk(b1))bhkf=1(1+10(a1)alphahk(b1))b5f=1(1+10(a1)alpha5(b1))printbf values= b1fb2fblkfbhkfb5f
f1=c1ff2=c2fflk=c3ffhk=c4ff5=c5fprintf1= f2= f3= f4= f5=f1f2flkfhkf5
d1=210d2=630d3=102725d4=5775d5=0printd1= d2= d3= d4= d5=d1d2d3d4d5
bb1=0b2=0b3=2275b4=78225b5=1470printb1= b2= b3= b4= b5=bb1b2b3b4b5
dtotal=d1+d2+d3+d4+d5btotal=bb1+b2+b3+b4+b5printdtotal= dtotalprintbtotal= btotal
xlkd=d3dtotalxhkd=d4dtotalxlkb=b3btotalxhkb=b4btotalalphalkavg=202nmin=log((xlkdxhkd)(xhkbxlkb))log(alphalkavg)
printN(min)= nmin end program fenske
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 64
OUTPUT
type value of mole fraction of component in feed0075016502750177303102Type the value of feed flow rate65716type value of distribution coefficient of each component2914751125055045Type the fraction of light key component in distillate05144Type the fraction of heavy key component in bottom03459alpha1= 5272727alpha2= 2681818alphalk= 2045455alphahk= 1000000alpha5= 8181818E-01a1= 2766936E-01b1= -8097797E-01df values= 3297785E-01 4596546E-01 5144000E-01 6541000E-01 3297785E-01bf values= 6702214E-01 5403454E-01 4856000E-01 3459000E-01 3101090E-01f1= f2= f3= f4= f5= 4928700 10843140 18071900 11651450 20385110d1= d2= d3= d4= d5= 210000000 630000000 1027250000 57750000 0000000E+00b1= b2= b3= b4= b5= 0000000E+00 0000000E+00 22750000 782250000 1470000000dtotal= 1925000000btotal= 2275000000N(min)= 9125515
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980
Project report Design Of Packed Bed Distillation Column
Dr Babasaheb Ambedkar Technological UniversityLonere 65
References
1Billet Reinbord rdquo Distillation Engineeringrdquo Chemical Publishing Co New York 19
2 Hines Anthony L Robert N MaddoxrdquoMass Transfer Fundamental and Applicationrdquo
Prentic ndashHall New Jersey 1985
3Joshi MVrdquoProcess Equipment Designrdquo3rd edition Macmillion India Ltd2004
4Kister Henry ZrdquoDistillation Design lsquorsquo McGraw Hill New York1989
5Matley JayrdquoModern Cost Engineering Methods and DatardquoVol II McGraw Hill
publicationsNY1984
6 Perry Robert H Green Don W James O MalonyrdquoPerryrsquos Chemical Engineering
Handbook ldquo7th edition McGraw Hill New York 1997
7 Rose LMrdquo Distillation Design In Practice ldquo Elsevier Amsterdam 1985
8 Schweitzer Philip ArdquoHandbook of separation techniques for chemical engineer ldquo2nd
edition McGraw Hill New York1988
9 Smith BDrdquo Design of Equilibrium Stage ProcessesrdquoMcGraw Hill Book Company
New York 1963
10 Treybal RErdquo Mass Transfer Operationrdquo McGraw Hill Book Company New York
1980