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Bryan PicouJames Roberts

12/6/13Final Paper

ET 493

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Our project that we are proposing to do is called the Evaporator

Optimization project, for a company called the American Sugar Refining Group.

They have a refinery in Chalmette, Louisiana, which is about 1 hour from here.

This company has many different projects that their engineers do throughout the

year. The Evaporator Optimization project has many different systems involved in

this project. We are proposing to do this project over two semesters. We have

met with different engineers over at the American Sugar Refinery about this

project. They have not started on this project and they said it would be a great

project for two young engineers.

This project consists of thermodynamics, statics, fluid mechanics, solid

mechanics, and properties of materials. All of these are classes that we have

taken or are taking this semester in our curriculum. The overall picture of this

project is to take the existing evaporators that they are using in the refinery and

make them more efficient. The evaporators use steam to evaporate the sugar

liquor lowing the density of the sugar liquor. As steam is injected vapors of the

evaporators from the steam goes back to the river in the current operation. This

is a lost of money because these vapors can be used to heat up different things

in the refinery causing the evaporators to become more efficient. We are going to

take the vapors from the evaporator and use them to melt the raw sugar in

another part of the plant, called the melter.

Engineering to be done in this project consists of figuring out the energy in

the steam and vapors coming in and out of the evaporators. Sizing up the heat

exchangers, and figuring the energy part that would be transferred through the

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Heat Exchangers throughout this project. Sizing the pipeline depending on the

gas flow rate that will transport the vapors from the evaporator to the melter.

Redesigning the melter depending on the energy in the vapor from the

evaporator. Designing the structure to support the pipeline that goes to the

melter. Designing how to use compressible vs. non-compressible gasses that will

be in the pipeline. Designing the thickness of the insulation so there is minimal

thermal loss in the pipeline. Engineer the pipe stress and thermal stress in

pipeline. Sketch a drawing of the project as a whole. Those are just some of the

deliverables we intend to have completed in May with more that will pop up along

the way.

This project is a good project for us to do because we learn how to

engineer in the real world instead of perfect scenarios. It is also good for us to

meet different engineers that are already out in the industry for possible future

jobs. Our advisor is Dr. Junkun Ma, we meet with him usually on Tuesday about

3:30 in the afternoon during his office hours. Dr. Ma has approved our project to

be two semesters long and has already given us assignments and we have

already started doing things for this project.

To begin working on the project it was necessary to get an understanding

of all the factors that needed to be taken into account when designing the

system. The system has to produce eight million pounds of sugar every day

which requires a vast amount of energy in the form of steam that is acquired from

the boiler. With the purpose of the project being to reduce the energy that is

required from the boiler we are utilizing left over steam from the evaporation

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process that is currently being dispersed into the environment. The first step in

this project was determining how much energy is actually needed to melt the

sugar so that it can move on to the next stage in the system. The sugar is

already a liquid when it enters the melters as a sugar we do not need to account

for the energy Q=c p∗m∗∆T --- 1 it is possible to determine the energy required

to dissolve the sugar to a finer solution after the specific heat of Sugar is known.

If the specific heat of sugar is C p sugar=0.65 Btulb℉ and the sugar enters the

melters at 130℉ and leaves at 170℉ we can use these values in equation 1 and

find a result.

Energy to melt sugar per hour

Q=0.65 Btulb℉∗478,800 lb

hr∗(170℉−130℉ )

Q=12,448,800 Btuhr

The next step was then figuring out how much energy steam provides to the

sugar per hour through heat transfer in equation 1 if the steam is at 188.5℉ and

cannot drop below 170℉. The C p for steam was found to be 0.45 Btulb℉ and is

supplied at a rate of 18100lbhr . However, simply using the steam and transferring

heat from the evaporation process was not going to be sufficient in terms of the

energy required to melt the sugar. To acquire the amount of energy needed from

the steam we have to change the phase of the steam to a liquid in a condenser.

By doing this we can utilize the latent heat of vaporization from the steam and will

be able to get a lot more energy that only changing the temperature of the steam

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to match the sugar through heat transfer. The equation for the latent heat is

Q=m∗L --- 2 where L is the latent heat of the steam, Q is the energy required to

melt the sugar, and m is the amount of water that will need to be condensed.

The latent heat of vaporization for water is found to be 976.6 Btulb at 12psi.

Energy provided by steam per hour through condenser

12,448,800 Btuhr

=m∗976.6 Btulb

- Solving for m yields that 12,746.26 lb of steam will need to be condensed

to provide adequate energy to melt the sugar.

Remaining steam will enter the melter through direct steam injection and heat the

sugar through heat transfer cooling the left over steam to 170℉.

Energy provided by steam per hour through direct steam injection

Q=0.45 Btulb℉∗5353.74 lb

hr∗(188.5℉−170℉)

Q=44569.88 Btuhr

Total energy provided by the steam

Energytot=Energy latent heat+Energy heat transfer

Energytot=12,448,800 Btuhr

+44569.88 Btuhr

Energytot=12493368.89 Btuhr

- The extra heat provided by the steam in direct steam injection should

compensate for the safety factor to make sure that the sugar will

adequately melt.

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We will be using a barometric condenser for the project. instead of water as the

coolant inside the condenser we will use the sugar itself to pull heat of the steam.

In this condenser steam flows through while sugar is sprayed by a nozzle in a

circular fashion inside the condenser. The information that we acquired from the

energy calculations will enable us to determine the size of the condenser that will

be needed to handle to amount of steam and sugar that will be flowing inside.

The next step that has to be taken in the project to correctly size the condenser is

determining how much sugar will be needed to condense 12,746.26 lbs of steam.

Once again the equation for the latent heat will be used, but this time it will be for

sugar. The latent heat of sugar 82.42 Btulb

Amount of sugar flowing through the condenser

12,448,800 Btuhr

=m∗82.42 Btulb

m=151,041 lbhr

Now that we know the mass of the sugar going through the condenser and the

amount of steam that needs to be condensed inside, we can select a condenser

of the correct size for the project.

The next phase of the project deals with the steam in the pipeline that

supplies the condenser in another location of the factory. The distance the

pipeline will have to travel is 377.95 ft from the evaporation process. Distance

between these two points is a possible from because the friction between the

pipe itself and the steam can interfere with the process in a way such that there

could be pressure loss at the end of the pipeline. The steam is pressurized to

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8 psi on the evaporation side of the process. We will need to use Bernoulli's

equation to determine what the pressure loss will be at the end of the pipeline

and determine if it needs to be taken into account.

P1

γ+z1+

V 12

2 g−H L=

P2

γ+Z2+

V 22

2 g

Z1−¿ Z2=20 ft∧V 1=V 2¿

Since the fluid is steam the added weight of the fluid due to a height change will

be negligible because a gas has a very small weight.

- The new equation will be P2Loss=P1−HL γ

H L is found from the equation: H L=

f∗LD

∗V 2

2g Where L = length of Pipeline, D

= Pipe Diameter, V = velocity of steam, g = gravity, and f = friction factor.

Given that D = 16in , g = 32.2fts2 , L = 377.95ft. To determine the value of H L we

need to find the friction factor and the velocity.

Solving for velocity

-In solving for velocity of the fluid volumetric flow rate and the area of the

pipe must be determined since V=QA . The density of steam is 47.34 ft

3

lb

and the mass flow rate is 18,100 lbhr . multiplying these two terms together

will yield the volumetric flow rate of Q=238.015 ft3

sec. The area of the pipe

will be A=π D2

4=

π162¿2

4∗1 ft

144 ¿2 =1.396 ft2.

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V=0238.015 ft 3/sec1.396 ft2 =170.49 ft

sec

To find out what the friction factor is we need to use Reynolds's number. and

determine the relative roughness and plot these points on moody's diagram.

N R=VDρζ where ζ is the dynamicviscosity∧ρis the density. The dynamic viscosity

was found to be ζ=8.064∗10−6 and the density is ρ=0.0193 lbft3 .

∴N R=6.528E6 > 4000 meaning that the steam is in a turbulent state. Relative

roughness is found fromDϵ . Epsilon was found to be 1.5∗10−6 ft from table 8.2 in

the book applied fluid mechanics 6th edition. Dϵ

=4444.44. Based on the values

for Reynolds's number and relative roughness the friction factor f=0.014.

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Solving for H L

H L=0.014∗377.95 ft

16/12∈¿∗170.49 ft2

2 g=1791.16 ft¿

Solving for loss of pressure

P2=8 psi∗144¿2

1 ft2 −1791.2 ft∗0.0193 lbft3 =1117.42

lbft2∗1 ft2

144 ¿2 =7.759 psi

The pressure loss at the end of the pipeline is very small so it is not necessary

for this factor to be taken into account when designing the supply system for the

condenser.

The Melters in the wash house are dissolving the washed raw sugar at

around 170 °F. Depending on the melt rate for that day will determine the optimal

temperature that the Melters must be in order to dissolve the sugar to the 72 brix

solution. The melters must completely dissolve all of the sugar into the

sweetwater solution before the solution leaves the melters. The higher the

temperature that the melters are, the faster the sugar will completely dissolve in

the sweetwater. The higher the temperature in the melters the more energy is

being used in order to dissolve the sugar. Energy could be saved if the melters

are run at the lowest temperature possible to fully dissolve the sugar. Finding the

rate of dissolution of sugar in the sweetwater will determine the time it takes for

the sugar to completely dissolve at various temperatures. Comparing the rate of

dissolution of sugar in the sweetwater to the retention time of the melters will

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determine the lowest temperature the melters need to run at to completely

dissolve the sugar.

An experiment needed to be created in order to find the rate at which

washed raw sugar dissolves in the sweetwater for a given temperature. The main

problem that was encountered with running the experiment was when heating up

the sweetwater and sugar, some of the sweetwater began to evaporate. When

some of the sweetwater evaporated, the solution soon became a supersaturated

solution. In the saturated solution, the washed raw sugar was at equilibrium and

could not fully dissolve in the sweetwater (Endpoint to experiment could not be

determined). To stop the evaporation a rubber stopper was put on the top of the

container holding the solution. This kept the vapor of the sweetwater in the

container and the loss of sweetwater due to evaporation was minimal. Another

difficulty in the experiment was the heat loss across the outside wall of the

container to the inside wall of the container. The temperature of the inside of the

container had to be recorded, not the outside of the container wall.

The retention time was found based on the amount of pounds that is

melted per day. The washed raw sugar that is melted in the Melters is 94% of the

melt rate. When the sugar is dried in the centrifugal 6% of the total melt solids is

spun off during that process and the sugar that comes out of the centrifugals has

1% moisture. The amount of washed raw sugar solids being dissolved is found

by the equation: Was hed Raw Sugar Solids=94 %∗Melt Rate.

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The amount of washed sugar liquor produced by each melter can be determined

using the equation, Washed Sugar Liquor=Sugar Solids+SweetwaterTota l+SugarMoisture.

Where SugarSolid is Sugar before it is washed and dried, SweetwaterTotal is the

amount of sweetwater in the melter, and SugarMoisture is the moisture in the sugar.

To calculate the solids in the sweetwater is found by the equation,

SweetwaterSolid=SweetwaterTotal∗10 %

To calculate the total amount of sweetwater added to make a 72 brix solution in

each melter is found in the equation;

Sugar Solid+Sweetwater SolidSugarTotal+Sweetwater Total

=72%.

Where SweetwaterSolid is the amount of sugar solids in the sweetwater and

SweetwaterTotalis the total amount of sweetwater.

The equation for the actual retention time is found in the following equation and is

measured in minutes,

RetentionTime=VQ

The variable Q is the flow of the sugar from the Melter, measured in GPM, and V

is the volume of the Melter, measured in gallons.

To calculate the volume for the melter the volume of a cylinder formula is used,

Volumeof acylinder=π∗r2∗h.

To find the retention time for the South Melter an equation is shown in the

equation, RetentionTime for Sout h Melter=V

2∗Q .

The total amount of retention time is calculated from the equation,

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Total RetentionTime=RetentionTimeEast∨West+RetentionTimeSout h

The retention time for various melt rates is located at the end of this paper on an

Excel document. The retention time for the East or West Melter is a power

function given by the equation, Time=6.0∗107∗melt rate−1. The retention time for

the South Melter is given by the following equation, Time=3.0∗107∗melt rate−1.

The total retention time is given in the equation Time=9.0∗107∗melt rate−1 it is also

a power function.

4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 1.00 3.00 5.00 7.00 9.00

11.00 13.00

f(x) = 57887748.2987328 x^-1.00000000000001R² = 1

Retention Time for East or West Melter

Series2

Power (Series2)

lb/day

Tim

e (m

in)

4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 -

2.00

4.00

6.00

8.00

f(x) = 28943874.149365 x^-1R² = 1

Retention Time for South Melter

Series2Power (Series2)

lb/day

Tim

e (m

in)

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4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 -

5.00 10.00 15.00 20.00

f(x) = 86831622.4480868 x^-0.999999999999997R² = 1

Total Retention Time

Series2Power (Series2)

lb/day

Tim

e (m

in)

If the melters were increased in volume by 10% the retention time for the melters

would rise as well. As the retention time increases the lower the temperature has

to be to completely dissolve to sugar. The power equation to find the retention

time with a 10% increase in volume for the east or west melter is,

Time=1.0∗108∗melt rate−1. The equation for the retention time to the south melter

with a 10% increase is, Time=6∗107∗melt rate−1. The equation for the total

retention time with a 10% increase in volume, Time=1∗108∗melt rate−1.

4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 -

10.00

20.00

30.00

f(x) = 121564271.42733 x^-1R² = 1

Retention time for East or West Melter with 10% increase in Volume

Series2Power (Series2)

lb/day

Tim

e (m

in)

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4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 -

2.00 4.00 6.00 8.00

10.00 12.00 14.00

f(x) = 60782135.7136629 x^-0.999999999999999R² = 1

Retention Time for South Melter with 10% increase in Volume

Series2Power (Series2)

lb/day

Tim

e (m

in)

4,000,000.00 6,000,000.00 8,000,000.00 10,000,000.00 -

5.00

10.00

15.00

20.00

25.00

f(x) = 108057130.157623 x^-0.999999999999999R² = 1

Total Retention time with 10% increase in Volume

Series2Power (Series2)

lb/day

Tim

e (m

in)

Apparatus’ Required

1. Erlenmeyer Flask

2. Rubber Stopper

3. Hot Plate

4. Water Bath

5. Stirrer

6. Timer

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7. Thermometer

8. Scale

Chemical’s Required

1. Sweetwater between 5 and 15 brix

2. Washed Raw Sugar

Experimental Methods

1. Measure the brix in the original sweetwater solution.

2. Figure out how much sugar needs to be added to 10 grams of sweetwater, to

create a 72 brix solution. SolidsSweetwater+SolidsSugarTotalSweetwater+Total Sugar

=72Brix

3. Weigh out 10 grams of sweetwater in a beaker

4. Weigh out the amount of sugar calculated in order to create a 72 brix solution

in another beaker.

5. Put the Erlenmeyer flask in the hot water bath and heat it up to a certain

temperature.

6. Heat the 10 grams of sweetwater up to 165 °F on the hot plate.

7. Pour the sugar and the heated sweetwater into the Erlenmeyer flask and start

the timer.

8. Put the rubber stopper on the Erlenmeyer flask.

9. Stir the solution constantly.

10. Constantly check to see when the sugar fully dissolves

11. When sugar is fully dissolved stop the timer.

12. Take the solution and measure the amount of brix making sure it is a 72 brix

solution.

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Results

The results of all the sugar dissolution tests are located at the end of the report.

Tests were run at various temperatures multiple times, different time averages

were calculated at each temperature. The results show that the temperature (x-

component) vs. time(y-component) is a power relationship. The temperature is

measured in °F and the time is measured in minutes. The equation for the power

relationship is, Temperature=246.75 ¿ time−0.173.

5 10 15 20 25 30 35 40 450

20

40

60

80

100

120

140

160

180

200

f(x) = 246.754029262766 x^-0.17322576787728R² = 0.939380810072085

Sugar Dissolution

Temp (°F)Power (Temp (°F))

Time (min)

Tem

per

atu

re (

F)

Depending on what the melting rate is, will determine the optimal temperature

that the Melters will need to operate at. If the Melters would be increased in

volume by 10% than the retention time would increase and lower the optimal

temperature. The results are shown at the end of the report and are graphed to

show the decrease in temperature and rise in retention time. The equations for

the retention time and the dissolution rates of sugar could be linked together and

the Melters could automatically change their temperature when the melt rate

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increases and decreases. The equation for the East or West Melter with a 10%

increase in volume related to time is y= 1E+08x-1. The equation for the retention

time for the south melter with a 10% increase in volume related to time is

y=6E+07x-1. The total retention time equation for an increase in 10% volume

related to time is y=1E+08x-1. The experiment that was run was not an exact

replica of how the Melters melt the sugar. I conclude that the amount of time it

takes to dissolve the sugar at each temperature is lower in the Melter than what

was calculated in the experiment for each temperature. The reason for this is

because the experiment was not stirred the entire time, the melter is mixing it

constantly. Another reason is because the melter does not lose heat and its

temperature stays consistent, in the experiment the temperature fluctuated some.

It is unknown of how much lower the amount of time is in the Melter compared to

the experimental results.

Timeline

February Design Heat Exchangers

Size of Heat Exchangers Materials of Heat Exchangers Energy Transfer

Design Pipeline Support Structure Deflection Stress Analysis on Structure Distance Between Supports Material Selection

March Comsol

Pipeline Stress Analysis Structural Support Stress Analysis Pipeline Deflection Beam Deflection

Design New System Layout ACAD Sketch

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Instruments Selection Space Requirements

April Control Sequence

Safety Ladder Logic(PLC)

Cost Analysis Yearly savings from cutting down steam consumption

Project Cost Cost of New Materials and Machines Cost of a Contractor Installing all Materials Machines

James Roberts Responsibilities Design sugar liquor pipeline Sketch of future operation Residence Time Design melters Design structural support system COMSOL Design new system layout Control sequence

Bryan Picou Responsibilities Sketch of future operations Energy of vapors Design condenser Vapor flow rate Design vapor pipeline Design heat exchangers COMSOL Design new system layout Cost analysis, project cost analysis

References[1] Domino Sugar Corporation[2] Cane Sugar Refining Handbook[3] www.sugartech.co.za