waterloss
TRANSCRIPT
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Project: 450MW combined
heat power plant ulaanbaatar
Job no. : PP0074
PT PLANT
CAPACITY CALCULATION
PT plant Calculation
A) Cooling Tower make-up Requirement
1
Cooling Tower Flow (CW +ACW
FLOW) m3/hr 57110
Refer Cooling tower
calculation
2
Evaporation [email protected]% of Cooling
tower flow (E) m3/hr 942.315 Assumption
3
Drift [email protected]% of cooling tower
flow(D) m3/hr 1.1422 Assumption
4 Cycles of Concentration (C') - 5 Assumption
5 Blowdown (B) m3/hr 234.43655
Formula used is
Blowdown =
(E-D(C-1))/(C-1)
6
Filtered water required for makeup to
cooling tower m3/hr 1177.8938 B + E +D
m3/hr 1178
B) Boiler blow down quenching water requirement
1 Total steam flow for three units tons/hr 1693.8 HBD (TMCR case)
2 Specific Gravity of FW @147.4deg C - 0.9193 Steam Table
3
Blowdown quantity for all three boiler @
3% blowdown for each boilerm3/h 55.27
Assumption
4
Flashing in Blowdown tank (10% of
Blow down assumed)m3/hr 5.53
Assumption
5 Blowdown quantity to waste water m3/hr 49.756 Temperature of Blowdown water Deg C 100.00 Assumption
7
Service water temperature (Quenching
Water)Deg C 26.00
Assumption
8 Maximum outlet temperature at outfall Deg C 60.00 Assumption
9 Service water makeup flow rate m3/hr 58.53
10 Service water makeup flow rate (SAY) m3/hr 60
C)
Make-up requirement for District
Heating System
1
Total water requirement for district
heating system kg/hr 7711200
Three times the HBD
CHP mode flow2 Make-up considered % 2 Assumed
3 Density at 70 deg C kg/m3 978.7008 Steam Table
4 Flow per pump m3/hr 157.58
m3/hr 160
D) Filtered Water requirement
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Project: 450MW combined
heat power plant ulaanbaatar
Job no. : PP0074
PT PLANT
CAPACITY CALCULATION
1 Make up to Cooling Tower m3/hr 1178 Refer Calculation above
2 HVAC Requirment m3/hr 10 Assumption
4
Input to DM Plant (Considering 85 % as
DM Plant Effciciency) (SAY) m3/hr 65.88
Refer Calculation fior DM
water requirement5 Service water requirements m3/hr 5 Assumption
6
Boiler blowdown quenching water
requirements(Service Water) m3/hr 60 Refer Calculation above
7 Total service water required m3/hr 65
8 Make up for District Heating Requiremen m3/hr 160 Refer Calculation above
9 Ash Handling requirement m3/hr 25 Assumption
10
Total Filtered Water Requirement
(SAY) m3/hr 1503.88
E) Total raw water requirement (PT plant capacity)
1 Total Raw Water Requirement m3/hr 1579.0765
1.05 times filtered water
requirement
PT Plant Capacity m3/hr 1580
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CT
Based on Nalco formular
1. Cooling tower
Qh= 7179 kW heat rejection capacityR= 344 m3/hr cooling water circulating flow rate
Ti= 50.0 cooling tower inlet temp.
To= 32 cooling tower outlet temp.
Tad= 27 ambient dry bulb temp. 15
T= 18.0 temp. defference between C.W supply and C.W return
Cn= 1 EA the number of cooling tower
Cp= 1 kcal/kgspecific heat
DM= 1 m3/hr water treatment capacity
Hr= 85 % relative humidity
Km= 0.0019 evaporation contant, please refer to table
A) Evaporation loss (E)
Ev(%)= T x[(Tad-1.6667)xKm + 0.1098]
= 2.84 %
E = R x Ev(%)/100
= 9.7696 m3/hr
Et= 9.7696 m3/hr total evaporation loss
B) Windage loss (W)
Dp= 0.1 % drop loss percent (0.05 - 0.2 %)
Normally, 0.1 % has been used for plant
Ds= 0.34 m3/hr
Dt= 0.344 m3/hr total windage loss
C) Blow down loss
Cm= 500 ppm TDS content in make-up water(mg/l)
Cr= 2500 ppm TDS content in recirculating water(mg/l)
N= Cr concentration factor
Cm
= 5
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CT
1. Cooling tower
Qh= 7179 kW heat rejection capacityR= 344 m3/hr cooling water circulating flow rate
Ti= 50.0 cooling tower inlet temp.
To= 32.0 cooling tower outlet temp.
Tw= 27 wet bulb temp.
T= 5 approach temp. range
Cn= 1 EA the number of cooling tower
Cp= 1 kcal/kgspecific heat
DM= 1 m3/hr water treatment capacity
A) Evaporation loss (E)
E= R x Cp x (Ti-To)
latent heat for water
= 10.9 m3/hr
Et= 10.9 m3/hr total evaporation loss
B) Windage loss (W)
Dp= 0.1 % drop loss percent (0.05 - 0.2 %)
Normally, 0.1 % has been used for plant
Ds= 0.34 m3/hr
Dt= 0.344 m3/hr total windage loss
C) Blow down loss " to be consider the water quality for following parameters"
*** TDS limit for economical chemical treatment
Cm= 600 ppm TDS content in make-up water(mg/l)
Cr= 3000 ppm TDS content in recirculating water(mg/l)
N= Cr concentration factor
Cm
= 5 The recommended TDS limit for economical chemical treatment is about 2100 ppm, please reduce concentrat
*** Alkalinity limit for economical chemical treatment
Cm= 300 ppm Alkalinity content in make-up water(mg/l)
Cr= 1500 ppm Alkalinity content in recirculating water(mg/l)
N= Cr concentration factor
Cm
= 5 The recommended Alkalinity limit for economical chemical treatment is about 400 ppm, please reduce concen
*** Chrolide limit for economical chemical treatment
Cm= 132 ppm Chrolide content in make-up water(mg/l)
Cr= 660 ppm Chrolide content in recirculating water(mg/l)
N= Cr concentration factor
Cm
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DM water
DM water consumption
A) blow-down 1) Chemical Dilution
(1-M-CA-021:Calc
Sc= 4.8 t/h total steam evaporation quantity 1:
Bf= 3 % boiler blow-down rateBd= 0.144 m3/hr boiler blow-down 2) Feed Water Make
3.456 m3/day ) HRSG C
,
B) Other water consumption for J.W cooler, LO cooler, etc.
Ms= 0.02 m3/hr Amount of water consumption
0.48 m3/day
C) Regeneration water waste(10 % of product)
Wt= #REF! m3/hr water treatment unit capacity
#REF! m3/day
Rs= #REF! m3/hr
#REF! m3/day Regeneration water waste
D) Condensate water return loss
Cs= 0.024 m3/hr (Water loss rate 0.5 %)
0.576 m3/day
Required sub-total make-up water #REF! m3/hr
3. FO/LO Purifier water consumption
A) FO purifier x 2 1012.8 /day B) LO purifier x 4 1113.6 /day
Required sub-total make-up water 2126.4 /day
0.09 m3/hr
4. Service water consumption for office
A) Sp= 0.10 m3/hr Amount of water consumption
based o 20 persons
B) Cw= 0.42 m3/hr Cleaning water
Required sub-total make-up water 0.52 m3/hr
*** Total water consump. (1+2+3+4) #REF! m3/hr
#REF! m3/day
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DM water
1. Evaporation loss is the water loss to the atmosphere in the cooling process.
The evaporation rate is dependent on the amount of water being cooled(R)
and temperature difference, humidity and cooling water inlet temp. etc.
2. Windage loss 1
Even though evaporating water is pure, some water driplets escape as
mist throughout the evaporation equipment. ) HRSG Bl
=
Where, the windage loss in the conventional cooling tower is in the range 1
of 0.05 to 0.2 % loss of the circulating cooling water flowrate (R).
) Deaerat
3. Blow-down loss Feed Wa
(
Since the water vapor is discharged by evaporation, the dissolved and =
suspended solids in the circulating water will be concentrated and 1
bring and cause the massive scale and corrosion.
4. Boiler blow-down rate is approximately 5%(design max.) ) Laborato
5. Regeneration water waste is the necessary water loss to regenerate 1
the resin. The water loss is approximately in the range of 8 to 10 % of
water treatment capacity. ) Samplin
(1)
6. Service water is bas 20 persons 2,500 /day (2)
- toilet bowl : 5 l/person x 1 frequency/day(8hr 5 /day person
- urine : 2l/person x 8 frequency/day(8hr 16 /day person
- washbowl : 3l/person x 3 frequency/day(8hr 9 /day person
- sink : 5l/person x 3 frequency/day(8h 15 /day person
- shower : 80l/person x 1 frequency/day(8 80 /day person
Total service water consumption per 1 person : 125 /day person
3)
7. cleaning water :
Width(m)Length( Water cleaning quantity(m)
39.5 50.8 0.005 10,033 /day 1) GT & HRSG Area
2)
3)
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DM water
based o 20 persons
B) Cw= 0.42 m3/hr Cleaning water
Required sub-total make-up water 0.42 m3/hr
*** Total water consump. (1+2+3+4) 14.0 m3/hr
337 m3/day
Remarks 1. Evaporation loss is the water loss to the atmosphere in the cooling process.
The evaporation rate is dependent on the amount of water being cooled(R)
and temperature difference, humidity and cooling water inlet temp. etc.
2. Windage loss
Even though evaporating water is pure, some water driplets escape as
mist throughout the evaporation equipment.
Where, the windage loss in the conventional cooling tower is in the range
of 0.05 to 0.2 % loss of the circulating cooling water flowrate (R).
3. Blow-down loss
Since the water vapor is discharged by evaporation, the dissolved and
suspended solids in the circulating water will be concentrated and
bring and cause the massive scale and corrosion.
4. Boiler blow-down rate is approximately 5%(design max.)
5. Regeneration water waste is the necessary water loss to regenerate
the resin. The water loss is approximately in the range of 8 to 10 % of
water treatment capacity.
6. Service water is bas 20 persons 2,500 /day
- toilet bowl : 5 l/person x 1 frequency/day(8hr 5 /day person
- urine : 2l/person x 8 frequency/day(8hr 16 /day person
- washbowl : 3l/person x 3 frequency/day(8hr 9 /day person
- sink : 5l/person x 3 frequency/day(8h 15 /day person
- shower : 80l/person x 1 frequency/day(8 80 /day person
Total service water consumption per 1 person : 125 /day person
7. cleaning water :
Width(m)Length( Water cleaning quantity(m)
39.5 50.8 0.005 10,033 /day
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DM water
ater()
lation for())
1.6 t/day
up
ntinuous Blow down Tank Spray Water()
low down MCR 2%.
HRSG HP Drum
- Pressure : 101 kg/cm2.a
- Temperature : 310.3
- Steam Flow : 288.6 t/h
- Enthalpy : 335.4 kcal/kg
- Blow down rate : 5.77 t/h (2% B/D)
HRSG LP Drum
- Pressure : 6.3 kg/cm2.a
- Temperature : 159.7
- Steam Flow : 26.7 t/h
- Enthalpy : 161.0 kcal/kg
- Blow down rate : 0.53 t/h (2% B/D)
HP+LP Blow down Mixed Steam
- Enthalpy
( 5.77 x 335.4 + 0.53 x 161 ) / (
= kcal/kg
- Blow down rate : 6.3 t/h (0.53+5.77)
Continuous Blowdown Tank(Assumed)- Pressure : 2 kg/cm
2.a
- : 146.2 kcal/kg
- : 119.9 kcal/kg
Continuous Blow down Tank Blow down
- Steam
( 5.77 + 0.53 ) x ( 320.7 - 119.9 ) / (
= 2.403648109 t/h
- Water : 3.37 t/h
Blow down Tank
- Pressure : 1 kg/cm2.a
- Temperature : 100 (sat)
- : 638.2 kcal
- : 100.1 kcal
Blow down Tank Hot Water
- Steam
= 3.37 x ( 320.7 - 100.1 ) / ( 638.2
= 1.381568482 t/h
- Hot water : 1.99 t/h
320.7
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DM water
Spray Water
- Spray Water : 15
- B/D Water : 85
- Spray Water
= 1.99 x ( 100.1 - 85 ) / ( 85
= 0.429271429 t/h
: 0.43 t/h x 24 hr = 10.32 t/day
ow down()
1.99 t/h + 0.43 t/h = 2.42 t/h
: 58.1 t/day
r Vent Steam()
ter Flow(315.3 ton/h) 0.023%, Assumed
ES, Vendor data Update)
x = 0.072519 t/h
: 1.75 t/day
: 1 t/day 2
ry()
0.05 m3/h
: 1.2 t/day
Devices(#2)()
8 : 1,000cc/min x 60min/h x 8 = 0.48 t/h
1 : 11.52 t/day
: 12
B/D water 15 Spray 85
.
: 85
Cleaning() : 5
: 12
: 17
315.3 0.00023
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DM water
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DM water
5.77 + 0.53
646.2 - 119.9
- 100.1 )
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DM water
- 15 )
t/day
t/day
t/day
t/day
t/day
t/day
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NOTE)
- Office: 120 liter/day/person(Based on 40 persons)
- The blow-down loss of cooling tower is based on concentration factor 5 and
TDS 313 ppm of water quality at cooling tower inlet and discharge limit 1565 ppm.
WATER MASS BALANCE OF THE PROPO
WATER TREATMENT SYSTEMCAPA. : 0.5 M3/HR
ENGINE COOLING SYSTEMEVAPORATION & LOSS: 0.02 M3/H
STEAM TRACING2.0 T/HR
HFO, SLUDGE TANK &
HFO,LO PURIFIEROPEATING WATER
0.04 M3/HR
OFFICE &CLEANING
W.H.R.B
BLOW DOWN:0.1 M3/H
WASTE WATER :0.05 M3/HR
RAW WATER:20.69 M3/HR
0.70 M3/HR
MAKE-UP WATER0.02 M3/HR
COOLING TOWER
RETURN WATER : 1.99
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water quality for CT
Company Name Based on Han Su LTD. Based on Han Su LTD. Based on Nalco Korea Based on Han Su
UNITRecommended CoolingTower make-up water
quality
Recommended Cooling
Tower circulating water
quality(economical
treatment)
Recommended Cooling
Tower circulating water
quality(economical
treatment)
Max. circulating watequality for chemical
treatment
PH 6.5-7.5 - 7.0-8.5 8.0-9.0
Suspended Solid(SS) ppm < 1 < 7 < 100 < 25
Turbidity NTU < 2
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water quality for CT
Based on HEC
Circulating waterquality requirement for
CT
7.5-8.5
< 100
< 500
-
< 2500
< 400
< 750(960*) *:max.
design valvue
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Purifier data(samgong)
Description SJ10FH SJ15FH SJ30FH SJ40FH SJ50FH SJ80FH REMARKS
Actual capacity l/h BASED ON HFO OF
Regulating water l/time 1 1 1.1 2 3.4 3.9 380 cSt
Replacement water l/time 0.4 0.4 1 1.6 2.5 3.5
Drained high press. water l/time 1.5 1.5 1.5 2.5 2.5 3.5
water Low press. water l/day 24 24 24 24 24 24from
operating Total l/day 42 42 42 54 54 54
water l/day 84 84 84 108 108 108drain side
Discharged Discharged sludg l/day 3.1 3.1 3.9 7.1 12.6 16.6
water& sludge
from l/day 79.2 79.2 88.8 139.2 205.2 253.2
sludge Total l/day 158.4 158.4 177.6 278.4 410.4 506.4
outlet side
l/day 58.8 58.8 67.2 97.2 124.8 142.8
Water consumption l/day 117.6 117.6 134.4 197.4 249.6 285.6
1. The values mentioned in the above indicate the quantity(presumed value) per one(1) set of Oil Purifie
2. Number of times of sludge discharge
1) Marine diesel oil and lubricating oil for cross head engine : Normal 12 times/day
2) Heavy fuel oil and lubricating oil for trunk piston engine : Normal 24 times/day
3. In the case of SJ-FH, we assumed no sludge discharge caused by the working of Water Detector.
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Purifier data(samgong)
r
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WATER EXPANSION
Water expansion 10 20 30 40
1000 liter x liters 1000 1002 1004 1008
Expansion % - 0.2 0.4 0.8
Evaporation pressure mWG - - - -(10mWG = 1bar)
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WATER EXPANSION
50 60 70 80 90 100 110 120 130
1012 1017 1023 1029 1036 1043 1052 1060 1069
1.2 1.7 2.3 2.9 3.6 4.3 5.2 6 6.9
- - - - - 0.4 4.7 10.3 17.5
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water treatment summary
1) Objective of boiler water treatment
The need or objective for boiler water treatment can be explained with respect to following problems on water
- corrosion
- Scale & deposit
- Carryover
The dissolved oxygen, carbon dioxide which converts into carbonic acid in condensate line, high dissolved
solids, Low PH are the main reasons behind corrosion in boiler system.
Hardness compounds like Calcium, Magnesium form scale in boiler.
Phosphate based chemicals form sludge in boiler. Due to corrosion several leakages, tube failure occur,
whereas scale and deposits decrease heat transfer, damage tubes, turbine blades, etc.
Carryover problems also lead to improper functioning of whole boiler network.
To take care & provide preventive measures, not only external treatment, but also right and compatible interna
treatment is required, which will inhibit the problems mentioned above.
Dissolved oxygen is the main culprit behind corrosion(pitting corrosion) in boiler system.
This dissolved oxygen if not scavenged quickly, shall attack the base metal and oxidise it, Localised attackof oxygen result into puncturing, pin-holes, tube failures, and so on.
Hence, oxygen scavenging forms heart of boiler water management.
2) Objective of water treatment for cooling tower cooling water
Corrosion, scale deposition, fouling and microbiological growths have for long posed challenges for proper
management of cooling water treatments, the heart of any cooling medium. It is this water if not treated
properly, which can damage equipment, impair product quality and threaten productivity, So main objective
of any cooling water chemical treatment is to control
- Corrosion
- Scale & Deposition- Fouling
- Microbiological growth
Corrosion
The physical factors contribting to corrosion are high temperature, low or high velocity and metallurgy.
The high temperature always increase the corrosion by oxygen depolarization
The high velocity promotes erosion corrosion, whereas low velocity permits sedimentation and hence
under deposit corrosion by developing diffential aeration cell.
Surface flows, grain boundaries, stress on metal, difference in type of adjacent metal can also cause
galvanic and stress corrosion.
The chemical factors, that affect corrosion are mainly pH, dissolved solids, dissolved gases, suspended
solids and micro-organisms either present in the make up water source or from contamination.
Generally ferrous metals are observed to be more susceptible to acidic PH whereas noble metals havent's an
effect f pH on them.
The hardness and bicarbonates can form barrier of deposits and may decrease corrosion or may also pose
under doposits and may decreas corrosion or may also pose under deposit corrosion.
The aggresive ions like chlorides, sulfattes promote local attack I.e pitting due to their antagonistic properties.
Carbon dioxide dissolved oxygen oxygen, hydrogen sulfide may promote acid or local corrosive to copper bas
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water treatment summary
metals, the suspended solids and micro organisms may promote localized attack, under deposits corrosion, et
Scale deposition
Deposition is nothing but the conglomerates that accumulate on water wetted surface.
The formation of insoluble particles in the bulk water and the subsequent adherence of these particles to meta
is termed as scale. Anything dissolved in cooling water has potential to develop scale due to it's primary
characteristic of having inverse solubility at and with increased temperature or elevated pH.
Problems which are caused by scale and deposits include loss of heat transfer efficiency, reduction of
water flow, increased under deposit corrosion and in most cases, higher usage of water due to
increased blow down.
Calcium and bicarbonates are almost present in water. The addition of heat or sharp rise in pH cause
bicarbonate ions to decompose to carbon dioxide and carbonates.
The calcium carbonates is reported to be having low solubility due to which it forms scale by precipitation.
Another most common scale found in cooling water system is calcium sulfate, which is 50 times more
soluble than calcium carbonate.
This phenomenon provides that basis for sulfuric acid addition to avoid calcium carbonate formation.But excess sulphate may cause scale deposition problems.
Due to phosphate deposits are found tobe very common in cooling water system.
The salts of silicious matters, magnesium, metal oxides, iron and corrosive products are other reported scales
and deposit in cooling water system.
The low velocity, bulk water, heat transfer surface temperature, cooling water temperature, high heat flux,
bio fouling have a serious impact on scale and deposits formation.
Fouling
Water borne deposits, commonly known as foulants are loose,porous, insoluble materials suspended in
water. They include particulate matter scrubbed from air, migrated corrosion products, silt, clay and
suspended in make-up water, organic matter, biological matter and floc carry over from clarifiers, etc.
Fouling can reduce heat transfer, interference with flow of cooling water by plugging the exchanger tubes.
High flow velocity( 1 to 3 m/sce) can sweep away ordinary fouling deposits, but low flow velocity
less than(0.8 m/sec) cause the suspended foulants to drop out and deposit over metal surface.
These low velocity conditions exists in shell side cooling compressor jackets, water boxes and cooling
tower basins.
Microbiological growth
Recirculating cooling water systems are ideal incubator for promoting the growth and proliferation of
micro-organism. Water saturated with oxygen, exposed to sunlight with a temperature between 30 deg.C to
60 deg.C and having a pH between 6 to 9 ensure abundant nutrients and appropriate for life sustaining
growth of micro-organisms.
The build up of biofilm is initiated with the absorption or organic material on metal surface and grows
through assimilation of nutrients. Eventually some of the biofilm is sheared away and re-entrained
in the water stream to repeat the biofilm development process elsewhere.
Biofilm can cause losses in heat transfer of its insulating property. The soft elastic rippled surface of
biofilm absorbs the kinetic energy from the flowing water.
Increased pumping energy is required to overcome the frictional resistance of the biofilm.
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water treatment summary
System problems
1) High pH(>1.8) of circulating water further increases its scaling/fouling tendency in cooling system.
Concentrated hardness salt come out of solution and adhere to heat transfer surfaces thus giving
rise to scale. Scaling, fouling, and deposits formed above pH 8.5 are normally hard in nature and are
extremely difficult to remove.
2) Open recirculating cooling tower acts as a natural scrubber for air and hence all the ari-borne impurities
like dust etc. find their way in to cooling water thereby contributing to fouling and deposition on heat transfer
surfaces. Fouling and deposition add to the problems caused by scaling.
3) Micro Biological Problem
The cooling towers may suffer from severe algal growth/presence in the cooling system. These algae
if not take care of lead to severe problems of nozzle choking in the tower deck. They also damage/block the
fills and in heat exchangers they accumulate and flourish on heat transfer, efficiency and capacity of the syste
4) TDS in make up water gets further concentrated in cooling water thus making your cooling water an
excellent. Electrolyte which creates a corrosive enviroment in the cooling system by accelerating the
following Electro Chemical reaction.
Fe ----> Fe ++ + 2e- Anode
Cu----> Cu++ + 2e-
O2 + H2O + 4e- ----> 40H- Cathode
The above dissolution of iron continues, leading to thining of metal etc.
5) Under deposit corrosion: This form of corrosion is considered to be the most dangerous form as it
results into pin holes, punctures & tube failures. It normally occurs at places where scaling & fouling have
formed. The driving force behind this form of corrosion is the creation of differential concentration oxygen cells
in regions between the scale layer and metal surface.
Leakages of MS pipelines occur because of under deposit corrosion due to high pH of recirculating water etc.
Scale/Corrosion/Fouling control
The calcium carbonates has very low solubility even at 20 deg.C in water than any other dissolved salt in it.
whereas calcium carbonate scale formation. But only acid addition alone cannot effectively contol salt.
Again as you are adding acid, it required some additives to take care against disadvantages of acid.
The organophosphonate is reported to be having best calcium carbonate scale inhibition ability. It also
can be used to protest metal from corrosion, It provides corrosion protection to metal by forming iron oxide
and iron phosphate film over metal surface. The precipitation of this orgono phosphonate with calcium cannot
be denied t at high temperature which can be avoided by the use of unique co-polymer TRC-233 of
sulphonic acid/Acrylic acid manometer. The co-polymer not only inhibits calcium phosphate scale but also
control carbonate, sulfate and other scale effectively. It also disperses precipitaed matter, silt, clay, suspendeparticles inhibition and dissolved solids in water. The high hardness support for corrosion inhibition due to
its natural corrosion inhibition tendency.
The Ortho/Poly/Organophospate combination increases rate of corrosion inhibition by dual corrosion
protection methodology like anodic & cathodic inhibition
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water treatment summary
Bio Control
The high solid content, hardness and sulfate level as well as phosphate added as corrosion inhibitor may pos
the problem of bio-growth with micro organisms like algae, fungus, sulfate reducing bacteria, iron oxidising sli
forming bacteria in cooling water where cooling water temperature and pH is very ideal for their growth.
This can get carried over to the system and may accelarate the biological problems. It may also decrease
the pH of circulating water drastically and causes heavy corrosion. As volume of water used for coolingpurpose is very high, the cheapest biocide available is Chlorine, but chlorine has its own limitations like handli
compatibility with pH corrosive nature, inability to withstand and control all types of micro-organism.
The performance of chlorine is also affected by contamination. The additionally used biodispersant works
as dispersant, surfactant, penetrant and chlorine enhancer.
This bio-dispersant enhance the performance of biocide by keeping cooling system very much clean.
The use of biodispersant permits the TCV count within the set norms 5 x 10^5 with no adverse effect on
cooling system.
Precleaning and passivation
Before starting any cooling water chemical treatment program, it is very much necessary to have clean
cooling water system for better performance of selected program. So precleaning becomes first improtant
step in any cooling water chemical treatment program.It is always better to have a frequent cleaning at least once in a year or two for better cooling water mangeme
However for new systems precleaning is not necessary.
The corrosion process must be polarised completely to avoid further corrosion or to inhibit the same.
Such polarization can be achieved by passivation. The complete and proper passivation ensures the
successful performance of the treatment at least against corrosion. thus passivation plays very improtant key
role in any cooling water chemical treatment programme and it must before starting regular treatment.
The passive film by corrosion inhibitor has always to be on metal surface to protect it from corrosion.
Any damage to this film allows acceleration of corrosion.
This damage to passive film over metal surface is expected due to frequent shutdown, load fluctuations,
cleaning of cooling system etc. This has to be taken care by passivating the cooling system again properly.
if any damage to passive film occurs.
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water treatment summary
R/O & IE(ion exchanger)/
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water treatment summary
ide
l
d
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water treatment summary
c
l
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water treatment summary
.
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e
g
t
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Physical water-quality parameters
Physical parameters define those characteristics of water that respond to the senses of sight, touch, taste,
or smell. Suspended solids, turbidity, color, taste and odor, and temperature fall into this category.
1) Suspended solid
Solids can be dispersed in water in both suspended and dissolved forms. Although some dissolved solidsmay be perceived by the physical senses, they fall more appropriately under the category of chemical
parameters and will be discussed more fully in a later section.
Sources
Solids suspended in water may consist of inorganic or organic particles of of immiscible(not mixed) liquids.
Inorganic solids such as clay, silt and other soil constituents are common in surface water.
Organic material such as plant fibers and biological solids(algal cells, bateria,etc) are also common constituents
of surface waters.
These material is seldom a constituent of groundwater.
Other suspended material may result from human use of the water, Domestic waste water usually contains
large quantities of suspended solids that are mostly organic in nature. Industrial use of water may result in
a wide variety of suspended impurities of either organic or inorganic nature. Immiscible liquids such as
oils and greases are often constituents of waste water.
Impacts
Suspended material may be objectionable in water of several reasons. It is aesthetically displeasing and
provides adsorption sites for chemical and biological agents. Suspended organic solids may be degraded
biologically, resulting in objectionable by-products. Biologically active (live) suspended solids may include
disease-causing organisms as well as organisms such as toxin-producting strains of algae.
Measurement
There are several tests available for measuring solids. Most are gravimetric tests involving the mass of residues.
The total solids test quantifies all the solids in the water, suspened and dissoloved, organic and inorganic.
This parameter is measured by evaporating a sample to drynesss and weighting the residue. The total quantity
of residue is expressed as milligrams per liter(mg/L) on a dry-mass-of-solids basis.
A drying temperature slightly above boiling temperature(104 deg. C) is sufficient to drive off the liquid and thewater absorbed to the surface of the particles, while a temperature of about 180 deg. C is necessary to evaporate
the occluded water.
Most suspended solids can be removed from water by filtration. Thus, the suspended fraction of the solids in
a water sample can be approximated by filtering the water, drying the residue and filter to a constant weight
at 104 deg. C (+/- 1) and determining the mass of the residue retained on the filter. The results of this
suspened solids test are also expressed as dry mass per volume(milligram per liter).
The amount of dissolved solids passing through the filters, also expressed as milligrams per liter, is the differenc
between the total-solid and suspened soild content of a water sample.
It should be emphasized that filtration of a water sample does not exactly divide the solids into suspended
and dissolved solids fractions according to the definitions presented eariler.
Some colloids may pass through the filter and be measured along with the dissolved solids absorb to the filter
materials. The extent to which this occurs depends on the size and nature of the solids and on the pore size
and surface characteristics of the filter material. For this reason, the terms filterable residues and nonfilterableresidues are often used.
Filterable residues pass through the filter along with the water and relate more closely to dissolved solids.
While nonfilterable residues are retained on the filter and relate more closely to suspened solids.
"Filterable residues" and "non-filterable residues" are terms more frequently used in laboratory analysis while the
dissolved solids and suspened soilids are terms more frequently used in water-quality-management practice.
For most practical applications, the distinction between the two is not necessary.
Once samples have been dried and mesaured, the organic content of both total and suspened solids can be
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determined by firing the residues at 600 deg. C for 1 hour.
The toral organic fraction of the residues will be converted to carbon dioxide, water vapor, and other gased
and will escape.
The remaining material will represent the inorganic, or fixed, residue.
When organic suspened solids are being measured, a filter made of glass fiber or some other material that
will not decompose at the elevated temperature must be used.
The following example illustrates the calculations involved in suspened solids analysis.
ex1) Determining the concentration of suspended solids
A fiterable residue analysis is run on a sample of water as follows. Prior to filtering , the crucible and fitler pad
are kept overnight in the drying oven, cooled, and the dry mass(tare mass) of the pair determined to be
54.352 g . Two hundred and fifty milliliter of the sample is drawn through a filter pad contained in the porous-
bottom crucible. The crucible and fiter pad are then placed in a drying oven at 104 deg. C and dried until a consta
mass of 54.389 g is reached. Determine the suspened solids concentration of the sample.
Solution)
1. Determine the mass of solids removed.
Tare mass + solids = 54.389
- Tare mass = 54.352
----------------------------------------------------------------------------------------Mass of solids = 0.037 g
= 37 mg
2. Determine the concentration of the solids
mg solids x 1000 ml/l
-------------------------------------------------= conc in mg/l
ml of sample
37 x 1000
-------------------------------------------------= 148.00 mg/l
250
Suspended solids, where such material is likely to be organic and/or biological in nature, are an improtantparameter of waset water. The suspended solids parameters is used to measure the quality of the wastewater
influent, to monitor several treatment processes, and to measure the quality of the effuent.
EPA has set a maximum suspended-solids standard of 30 mg/l for most treated wastewater discharges.
2) Turbidity
A direct measurement of suspended solids is not usually preformed on samples from natural bodies of water or
on potable water supplies. The nature of the solids in these waters and the secondary effects they produce
are more important than the actual quantity. For such waters a test for turbidity is commmly used.
Turbidity is a measure of the extent to which light is either absorbed or scattered by suspended material in
water. Because absorption and scattering are influenced by size and surface characteristics of the suspended
materials, turbidity is not a direct quantitive measurement of suspended solids. For example, one small pebble
in a galss of water would produce virtually no turbidity. If this pebble were crushed into thousands of particlesof collodal size, a measurable turbidity would result, even though the mass of solids had not changed.
Sources
Most turbidity in surface water results from the erosion of collodial material such as clay, silt,rock fragments,
and metal oxides from the soil. Vegetable fibers and microorganisms may also contribute to turbidity.
Household and industrial wastewaters may contain a wide variety of turbidity-producing material. Soaps,
detergents, and emulsifying agents produce stable colloids that result in turbidity. Although turbidity
measurements are not commonly run on wastewater, discharges of wastewater may increase the turbidity of
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natural bodies of water.
Impacts
When turbid water in a small, transparent container, such as a drinking glass, is held up to the light, an
aesthetically displeasing opaqueness or milky coloration is apparent. The colloidal material associated with
turbidity provides absorbtion sites for chemicals that may be harmful or cause undesirable tastes and odors
and for biological organisms that may be harmful .
Disinfection of turbid waters is difficult because of the absorptive characteristics of some colloids and becausethe solids may partially shield organism from the disinfectant.
In natural water bodies, turbidity may impart a brown or other color to water,depending on the light-absorbing
properties of the solids, and may interfere with light penetration and photosynthetic reactions in streams and
lakes. Accumulation of turbidity-causing particles in porous streambeds results in sediment deposits that can
adversely affect the flora and fauna of the stream.
Measurement
Turbidity is measured photometrically by determining the percentage of light of a given intensity that is either
absorbed or scattered. The original measuring apparatus, called a jacson turbidimeter, was based on light absorp
and employed a long tube and standardized candle. the candle was placed beneath the glass tube that was then
housed in a black metal sheath so that the light from the candle could only be seen from above the apparatus.
The water sample was then pours slowly into the tube until the lighted candle was no longer visible, I.e., complete
absorption has occured. The glass tube calibrated with readings for turbidity produced by suspensions of silica di
(SiO2) with one jackson turbidity unit(JTU) being equal to the turbidity produced by 1 mg SiO2 in l L of distilled wIn recent years this awkward apparatus has been replaced by a turbidity meter in which a standardized electric b
produces a light that is then directed through a small sample vial.
In absorption mode, a photometer measure the light intensity on the side of the vial opposite from the light sourc
while in the scattering mode, a photometer measures the light intensity at a 90 angle form the light source.
Although most turbidity meters in use today work on scattering principle, turbidity caused by dark substances that
absorb rather than reflect light should be measured by the absorption technique. Formazin, a chemical compoun
provides more reproducible standards than SiO2 and has replaced it as a reference. Turbidity meter readings are
now expressed as formain turbidity units, or FTUs, The nephelometry turbidity units(NTU) is often used to
indicate that the test was run according to the scattering principle.
Use
Turbidity measurements are normally made on "clean" waters as opposed to wastewaters. Natural waters may h
turbidities ranging from a few FTUs to several hundred. EPA drinking-water standards specify a maximum of 1 F
while the American water Works Association has set 0.1 FTU as its goal for drinking water.
3) Color
Pure water is colorless but water in nature is often colored by foregin substances.
Water whose color is partly due to suspended matter is said to have apparent color. Color contributed by
dissolved solids that remain after removal of suspended matter is known as true color.
Sources
After contact with organic debris such as levels, conifer needless, weeds, or wood, water picks up tannins
humic acid, and humates and takes on yellowish-brown hues, Iron oxides cause reddish water, and manganese
oxides cause brown or paper production, food processing, chemical production, and mining, refining and
slaughterhouse operations may add substaintial coloration to water in receiving streams.
Impacts
Colored water is not aesthetically acceptable to the general public. In fact, given a choice, consumers tend to
choose clear, noncolored water of otherwise poorer quality over treated potable water supplies with an
objectable color. Highly colored water is unsuitable or laundering, dyeing, papermaking, beverage
manufacturing, dairy produection and other food processing and textile and plastic production. Thus, the color
of water affects its marketability for both domestic and industrial use.
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While true color is not usually considered unsanitary or unsafe, the organic compounds causing true color
may exert a chlorine demand and thereby seriously reduce the effectiveness of chlorine as a disinfectant.
Perhaps more important are the products formed by the combination of chlorine with some color-producing
organics. Phenolic compounds, common constituents of vegetative decay products, produce very objectable
taste and odor compounds with chroline. Additionally, some compounds of naturally occuring organic acids
and chlorine are either known to be, or are suspected of being, carcinogens(cancer-causing agents).
Measurement
Althrough several methods of color measurement are avialable, methods involving comparison with standardized
colored materials are most often used. Color- comparison tubes containing a series of standards may be used
for direct comparison of water samples that have been filtered to remove apparent color. Results are
expressed in true color units(TCUs) where one unit is equivalent to the color produced by 1 mg/L of platinum
in the form of chlorplatinate ions. For colors other than yellowish-brown hues, especially for colored waters
originating from industrial waste effluents, special spectrophotometric techniques are usually employed.
In fieldwork, instruments employing colored glass disks that are calibrated to the color standards are often used.
Because biological and physical changes occurring storage may effect color. samples should be tested within
72 h of collection.
UseColor is not a parameter usually included in wastewater analysis. In potable water analysis, the common practice
is measure only the true color produced by organic acid resulting from decaying vegetation in the water.
The resulting value can be taken as an indirect measurement of humic substances in the water.
4) Taste and Odor
The terms and odor are themselves definitive of this parameter. Because the sensations of taste and smell are
closely related and often confused, a wide variety of tastes and odors may be attributed to water by consumers.
Substances that produce an odor in water will almost invariably impart a taste as well. The converse is not ture,
as there are many mineral substances that produced taste but no odor.
Sources
Many substances with which water comes into contact in nature or during human use may impart perceptibletaste and odor. These include minerals, metals , and salts from the soil, end products from biological reactions, a
constituents of wastewater. Inorganic substances are more likely to produce tastes unaccompanied by odor.
Alkaline material imparts a bitter taste to water, while metallic salts may give a salty or bitter taste.
Organic material, on the other hand, is likely to produce both taste and odor. A multitude of organic chemicals
may cause taste and odor problems in water, with petroleum-based products being prime offenders. Biological
decomposition of organics may also result in taste-and odor-products liquids and gases in water.
Principle among these are the reduced products of sulfur that impart a " rotten egg" taste and odor. Also,
certain species of algae secrete an oily substance that may result in both taste and odor. The combination of two
or more substances, neither of which would produce taste or odor by itselt, may sometimes result in taste and
odor problems. This synergistic effect was noted earlier in the case of organics and chlorine.
ImpactsConsumers find taste and odor aesthetically displeasing for obvious reasons. Because water is thought of as
tasteless and odorless, the consumer associates taste and odor with contamination and may prefer to use a
tasteless, odorless water that might actually pose more of a health threat. And odors produced by organic
substances may pose more than a problem of simple aesthetics, since some of those substances may be
carcinogenic.
Measurement
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Direct measurement of materials that produce taste and odors can be made if the causative agents are known.
Several types of analysis are available for measuring taste-producing inorganics. Measurement of taste- and
odor-causing organics can be made using gas or liquid chromatography. Because chromatorgraphic
analysis is time-consuming and required expensive equipment. it is not routinely performed on water samples,
but should be done if problem organics are suspected. However, because of the synergism noted earlier, qnantif
the sources does not necessarily quantify the nature or intensity of taste and odor.
Quantitive tests that employ the human senses of taste and smell can be used for this purpose. An example istest for the threshold odor number(TON). varying amounts of odorous water are poured into containers and dilute
with enough odor-free distilled water to make a 200-ml mixture. An assembled panel of five to ten noses is used t
determine the mixture in which the odor is just barely detectable to the sense of smell. The TON of that sample
is then calculated using the formula.
A + B
TON = --------------- (2-1)
A
Where A is the volume of odorous water (mL) and B is the volume of odor-free water required to produce a 200 -
mixture. Threshold odor numbers corresponding to various sample volumes are shown in Table 2-2. A similar tes
can be used to quantify taste, or the panel can simply rate the water qualitatively on an " acceptability" scale.
Table 2-2 Threshold odor numbers corresponding to sample volume diluted to 200 mL
Sample volume(A) TON
mL
200 1
175 1.1
150 1.3
125 1.6
100 2
75 2.7
67 3
50 4
40 5
25 8
10 202 100
1 200
Use
Although odors can be a problem with wastewater, the taste and odor parameter is only associated with potable
EPA does not have a maximum standard for TON. A maximum TON of 3 has been recommended by the Public
Service and serves as a guideline rather than a legal standard.[2-18]
2-6. Temperature
Temperature is not used to evaluate directly either potable water or wastewater. It is, however, one of the most i
paramters in natural surface-water systems. The temperature of surface waters governs to a large extent the biol
species present and their rates of activity. Temperature has an effect on most chemical reactions that occur in na
water systems. Temperature also has a pronounced effect on the solubilities of gases in water.
Sources
The temperature of natural water system responds to many factors. the ambient temperature(temperature of the
being the most universal. Generally, shallow bodies of water are more affected by ambient temperature than
are deeper bodies. The use of water for dissipation of waste heat in industry and the subsequent dischage of the
may result in dramatic, though perhaps localized, temperature changes in receiving streams, Removal of forest c
irrigation return flows can also result in increased stream temperature.
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Impacts
Cooler waters ususally have a wider diversity of biological species. At lower temperatures, the rate of biological a
utilization of food supplies, growth, reproduction, etc., is slower. If the temperature is increased, biological activity
increase of 10 deg. C is usually sufficient to double the biological activity,if essential nutrients are present. At ele
increased metabolic rates, organisms that are more efficient at food utilization and reproduction flourish, while ot
and are perhaps eliminated altogether.Accelerated growth of algae often occurs in warm water and can become a problem when cells cluster into algae
Natural secretion of oils by algae in the mats and the decay products of dead algae cells can result in taste and o
Higher-order species, such as fish, are a function of temperature. Game fish generally require cooler temperature
dissolved-oxygen levels.
Temperature changes affect the reaction rates and solubility. levels of chemicals, a subject more fully explored in
Most chemical reactions involving dissolution of solids are accerated by increased temperatures.
The solubility of gases, on the other hand, decreases at elevated temperature. Because biological oxidation of or
and impoundments is dependant on an aduquate supply of dissolved oxygen. decrease in oxygen solubility is un
The relationship between temperature and dissolved oxygen levels is shown in Table C-3 of the appendix.
Chemical water-quality Parameters
Water has been called the universal solvent, and chemical parameters are related to the solvent capabilities of w
Total dissloved solid, Alkalinity, hardness, fluorides, metals, organics, and nutrients are chemical parameters of cin water quality management. The following review of some basic chemistry related to solutions should be helpful
in understanding subsequent discussion of chemical parameters.
2-7 chemistry of solutions
An atom is the smallest unit of each of the elements. Atom are building blocks from which molecules of elements
are constructed. For instance, two hydrogen atoms combine to form a molecule of hydrogen gas.
H+H = H2
Adding one atom of oxygen to the hydrogen molecule results in one molecule of the compound water.
A relative mass has been assigned to a single atom of each element based on a mass of 12 for carbon. The sum
atomic mass of hydrogen is 1 and the atomic mass of oxygen is 16. Thus the molecular mass of the hydrogen is
the molecular mass of water is 18. A mole of an element or compound is its molecular mass expressed in comm
mass units, usually grams. A mole of hydrogen is 2 g, while a mole of water is 18 g. One mole of a substance dis
sufficient water to make one lilter of solution is called a one molar solution.Bonding of elements into compounds is sometimes accomplished by electrical forces resulting from transferred e
When these compounds dissociate in water, they produce species with opposite charges. An example is sodium
NaCl = Na+ + Cl-
The charged species are called ions, Positively charged ions are called cations, and negatively charged ions are
anions. The number of positive charges must equal the number of negative charges to preserve electrical neutra
in a chemical compound. The number of charges on an ion is refered to as the valence of that ion.
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nt
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tion
xide
ter.lb
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water quality summary
d
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ing
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water quality summary
tivity, I.e,
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ated temperature
er species decline
mats.
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and higher
later sections of this chapter.
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