The document discusses proposed improvements to the circulating water treatment system at NLC TPS II power plant. It analyzes water parameters from the current system and identifies high hardness, alkalinity, dissolved solids and oxygen that promote corrosion and scaling. A new treatment system is proposed using increased chlorine dosing to control microbes, along with corrosion and scale inhibitors. Annual chemical consumption and costs are estimated for different cycles of concentration to reduce specific water consumption below 3.5 m3/MWh. Improving the treatment process aims to control corrosion, scaling and fouling in the circulating water system.

1. Project study report prepared by M G
Morshad , ADGM
CIRCULATING WATER TREATMENT
SYSTEM
Project Consultant
LAHMEYER INTERNATIONAL(INDIA) pvt. Ltd.
Client : NLC / TPS II
Clients Representative
1. GM Operation
2. DGM / Chemical
3. DGM / Turbine Auxiliaries
4. CM / Chemical
5. CM / C& I
6. CM/ Turbine (O&S)
7. CM/ Electrical Mtce

2. 1. To reduce/control the corrosion, scaling and
microbiological fouling in circulating water system
by improving water treatment procedure based on
recent water analysis report.
2. To reduce specific Water consumption of
circulating water system below 3.5 m3/MWH by
increasing COC from 1.2 to 5 as result of
improvement in water treatment procedure.
Project Objective

3. Process flow diagram
CT
CWPump
House
ForeBay
Lake
Power
House
Hot CW
Cold CW
Blow Down
water
ADPH
( Utilized for wet
ash disposal )
Excess water is
discharged out
side of TPS II at
village Nallahs
Evaporation
loss
Drift loss
Make up water
Bore well /TPSII
Make up water
Mine II

4. Circulating water parameters for stage I Units (3 x 210MW)
Parameters Formula Design Actual
Unit Load MW 210 210
Total load TL = 3 x MW 630 630
Circulating water flow per unit (m3/Hr) Q 30810 16500
Total flow (m3/Hr) TQ = 3 x Q 92430 49500
Hold up capaciy (m3) HC 114698 114698
Water untilazation U = (TQ/HC)x100 80.59% 43.16%
Reserve water R = 100 -U 19.41% 56.84%
Inlet Temperature T1 42.5 46
Outlet Temperature T2 34 38
Total Evaporation loss (m3/Hr) TE = 0.00085 x2.03 x TQx(T1-T2) 1355.65 683.30
% Evaporation Loss TE/TQ 1.47% 1.38%
Total Drift Loss (m3/Hr) TD = 0.02% x TQ 18.49 9.9
Blow down per unit (m3/Hr) BD 2193.3 670.3
Total Blow down (m3/Hr) TBD = 3 x BD 6579.9 2010.9
COC 1 + {TE / (TBD + TD)} 1.21 1.34
Total Make up (m3/Hr) TM = TE + TBD + TD 7954.03 2704.10
SWC (m3/MWhr) TM/TL 12.63 4.29

5. Circulating water parameters for stage I Units (4 x 210MW)
Parameters Formula Design Actual
Unit Load MW 210 210
Total load TL = 4 x MW 840 840
Circulating water flow per unit (m3/Hr) Q 31000 16500
Total flow (m3/Hr) TQ = 4 x Q 124000 66000
Hold up capaciy (m3) HC 120000 120000
Water untilazation U = (TQ/HC)x100 103.33% 55.00%
Reserve water R = 100 -U -3.33% 45.00%
Inlet Temperature T1 42.5 46
Outlet Temperature T2 34 37
Total Evaporation loss (m3/Hr) TE = 0.00085 x2.03 x TQx(T1-T2) 1861.47 1024.95
% Evaporation Loss TE/TQ 1.50% 1.55%
Total Drift Loss (m3/Hr) TD = 0.02% x TQ 24.80 13.2
Blow down per unit (m3/Hr) BD 2193.3 2011
Total Blow down (m3/Hr) TBD = 4 x BD 8773.2 8044
COC 1 + {TE / (TBD + TD)} 1.21 1.13
Total Make up (m3/Hr) TM = TE + TBD + TD 10659.47 9082.15
SWC (m3/MWhr) TM/TL 12.69 10.81

6. COC and SWC for Stage I Units
Cycle of
Concentration
COC 1.2 1.7 2 2.5 3 3.5 4 4.5 5
CW flow
(m3/Hr)
Q 92430 92430 92430 92430 92430 92430 92430 92430 92430
Evaporation Loss
(m3/Hr)
E 1357 1357 1357 1357 1357 1357 1357 1357 1357
Drift loss
(m3/Hr)
D 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6 18.6
Blow Down
(m3/Hr)
BD =[E/(COC-1)]- D 6766.4 1920 1338 886.07 659.9 524.2 433.7 369.11 320.65
Make up
(m3/Hr)
MU =E +D+BD 8142 3295.6 2714 2261.7 2036 1900 1809 1744.7 1696.25
Unit Generation
(MW)
MW 630 630 630 630 630 630 630 630 630
Specific Water
Consumption
(m3/MWhr)
MU/MW 12.92 5.23 4.31 3.59 3.23 3.02 2.87 2.77 2.69

7. COC and SWC for Stage II Units
Cycle of
Concentration
COC 1.2 1.8 2 2.5 3 3.5 4 4.5 5
CW flow
(m3/Hr)
Q 93000 93000 93000 93000 93000 93000 93000 93000 93000
Evaporation Loss
(m3/Hr)
E 2077.44 2077.4 2077 2077.4 2077 2077 2077 2077.4 2077.44
Drift loss
(m3/Hr)
D 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6 39.6
Blow Down
(m3/Hr)
BD = [E/(COC-1)]- D 10347.6 2557.2 2038 1345.4 999.1 791.4 652.9 553.95 479.76
Make up
(m3/Hr)
MU =E +D+BD 12464.64 4674.2 4155 3462.4 3116 2908 2770 2671 2596.8
Unit Generation
(MW)
MW 840 840 840 840 840 840 840 840 840
Specific Water
Consumption
(m3/MWhr)
MU/MW 14.84 5.56 4.95 4.12 3.71 3.46 3.30 3.18 3.09

8. 1
10
100
1000
10000
1 2 3 4 5 6 7 8 9
COC
SWC
MU
BD

9. Water analysis report
I. The turbidity and TSS are below detection level for CW makeup water, Circulating
water for both stages This is due to the filtration property of soil for ground water.
Turbidity & Total
Suspended Solids
Unit
Limiting value :As per
IS-8188
Make up
water
Stage I /
Fore bay
Stage II /
Fore bay
Turbidity NTU
Not Greater than 50
NTU
BDL BDL BDL
Suspended solid(TSS) (mg/l ) or ppm NA BDL BDL BDL

10. I. As the feed water is from bore wells, the degree of hardness of CW makeup is Very
hard and so are the circulating water of both stages.
Water analysis report
Total
Hardness
Unit Limiting value :As per IS-8188
Make up
water
Stage I
/Fore bay
Stage II
/Fore bay
Total hardness (caco3) (mg/l ) or ppm Not Greater than 250 ppm as CaCO3 370 425 470
Mg+Fe (mg/l ) or ppm Not Greater than 0.5 ppm 31.59 39 46.17
Fe (mg/l ) or ppm ****** BDL BDL BDL
Na (mg/l ) or ppm NA 72 96 98
No3 (mg/l ) or ppm NA 4.32 4.92 5.06

11. I. Alkalinity is found to be higher in make up and circulating water in both stages
II. Higher the alkalinity, greater is the capacity of water to neutralize the acids.
III. Alkalinity is an important factor for calcium carbonate scales formed on the heat
exchanger surfaces.
Total
Alkalinity
Unit Limiting value :As per IS-8188
Make up
water
Stage I
/Fore bay
Stage II
/Fore
bay
Total Alkanity (caco3) (mg/l ) or ppm Not Greater than 200 ppm as CaCO3 240 250 320
Bi carbonate (mg/l ) or ppm NA 240 290 300
Carbonate (mg/l ) or ppm NA BDL 20 29
Water analysis report

12. Total Dissolved Solids,
Conductivity & Silica:
Unit
Limiting value :As per IS-
8188
Make up
water
Stage I /
Fore bay
Stage II /
Fore bay
Total Dissolved solids (TDS) (mg/l ) or ppm Not Greater than 500 ppm 621 671 841
Ca (mg/l ) or ppm NA 96.19 106 112.22
Mg (mg/l ) or ppm ****** 31.59 39 46.17
K (mg/l ) or ppm NA 4 6 5
So4 (mg/l ) or ppm Not Greater than 600 ppm 96.24 105.62 125.01
Fluoride (mg/l ) or ppm NA 0.61 0.69 0.67
Electrical Conductivity (μS/cm) NA 1248 1547 1813
Sio2 (mg/l ) or ppm Not Greater than 75 ppm 12.84 28.86 47.08
Cl (mg/l ) or ppm Approximately 1.3 118.77 139.2 173.21
Free Cl (mg/l ) or ppm 0.2-0.5 ppm BDL BDL BDL
Water analysis report
1. TDS comprise dissolved inorganic salts (principally calcium, magnesium, potassium,
sodium, bicarbonates, chlorides, and sulphates ) and some small amounts of organic
matter are found to be higher side.
2. Dissolved Chlorine is higher but free chlorine is found to be below detection level.

13. I. The dissolved oxygen is higher than limiting values.
II. Higher values of dissolved oxygen in water (more than 3 mg/l) promotes healthy
environment for microorganisms and increases the tendency of corrosion.
III. As dissolved oxygen in water is on higher side, demand of oxygen (COD) is not
detected.
IV. COD is the amount of oxygen required for degradation of organic compounds of
water to occur.
Dissolved Oxygen &
COD
Unit
Limiting value :As per IS-
8188
Make up
water
Stage I
/Fore bay
Stage II
/Fore bay
Chemical Oxygen Demand(COD) (mg/l ) or ppm Not Greater than 4 ppm BDL BDL BDL
Dissolved O2 (mg/l ) or ppm Not Greater than 3 ppm 6.1 5.9 5
Water analysis report

14. Stability Indices
(LSI & RSI)
Formula Make up Stage I Stage II
pH pH 7.71 8.53 8.48
TDS 621 671 841
TDS Factor - A A 0.2 0.2 0.2
Temperature 28.7 28.9 29.1
Temp Factor - B B 1.9 1.9 1.9
Calcium Hardness 370 425 470
Hardness Factor -C C 2.2 2.2 2.3
Alkalinity 240 250 320
Alkanity Factor -D D 2.4 2.4 2.5
pHs pHs =9.3+A+B – (C+D) 6.8 6.8 6.6
Langelier Index (LSI) = pH- pHs 0.91 1.73 1.88
Ryznar Index (RSI) = 2 pHs – pH 5.89 5.07 4.72
LSI=0 or RSI=6: Water is chemically balanced or Neutral
Moderate Scale
forming
Tendency
Very sever
Scale forming
Tendency
Very sever Scale
forming
Tendency
LSI<0 or RSI>6: Water has a Corrosive Tendency
LSI>0 or RSI<6: Water has a Scale forming Tendency
Water analysis report

15. Desired Circulating Water Quality Parameters
As per IS-8188

17. Microbiological
fouling in NDCT
Fills area
Microbial slimes in NDCT outer columnsMicrobiological fouling in CW channel
Physical conditions

18. COLTCS sponge balls removed along with Scale from
condenser tubes
PHE plates with microbiological fouling
being cleaned
Physical conditions

19. Blow down Chlorination Scale inhibitor
dosing
Present chemical treatment system
It is carried out for
maintaining calcium
concentration around
200 ppm based on
the water analysis at
frequent intervals.
"Shock dosing of
Chlorine“ at the rate
of 1.08 ppm and 0.81
ppm for Stage-I & II
respectively.
Continuous dosing of
HEDP“ at the rate of
0.57 ppm and 0.42
ppm for stage-I & II
respectively.

20. Continuous
monitoring
of water
parameters
Acid dosing
Proposed chemical treatment system
Dosing rate to
be increased
further to the
desire level
utilizing the
existing
facilities to
control the
growth of
microorganisms
Automatic
blow down
to maintain
the desire
parameters
Chlorination
To be
introduced to
reduce water
harness to
the desire
level
Dosing for
Corrosion
Inhibitor
To be
introduced
at the
require rate
to reduce
corrosion
Dosing for
Scale
Inhibitor
To be
introduced
at the
require rate
to reduce
scale
formation
Dosing for
Biocide
To be
introduced at
the require rate
to control the
growth of
microorganisms
New facilities to be created with capital investment

21. Chlorine Dosing Stage I Stage II Unit
Total Circulating Water Flow Q 92395 124000 m3/hr
Present Dosage Rate PDR 1.08 0.81 ppm
Maximum Dosage Rate MDR 7.79 7.74 ppm
Recommended dosing rate RDR = (MDR-PDR) 5 5 ppm
Required dosing per Hr RDH = Q x RDR/1000 461.975 620 Kg/Hr
Operating Hrs / day H 1.5 1.5 Hr
Required dosing per /day RDH x H 692.96 930.00 Kg/day

22. COC & water cost for Stage – I
COC
Corrosion
Inhibitor
Consumption
Scale
Inhibitor
Consumption
Biocide
Consumption
Chlorine
Consumption
Sulphuric Acid
Consumption
TotalannualchemicalcostCrRs
SWC(m3/MWhr)
Annualgen@85%PLF(MWHr)
Annualwaterconsumption(m3)
WatercostinRs/m3
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
5 217.7 250 1.99 217.7 85 0.68 9.9 46 0.02 692.9 85 2.15 1467 270 14.46 17.30 2.69 195457 525780 329.02
2 158.3 250 1.44 158.3 85 0.49 3.17 46 0.01 692.9 85 2.15 855.9 270 8.43 11.08 4.31 195457 842421 131.54
1.2 380 250 3.47 380 85 1.18 0 46 0.00 692.9 85 2.15 0 270 0.00 3.33 12.92 195457 2525310 13.18

23. COC & water cost for Stage – II
COC
Corrosion
Inhibitor
Consumption
Scale Inhibitor
Consumption
Biocide
Consumption
Chlorine
Consumption
Sulphuric Acid
Consumption
TotalannualchemicalcostCrRs
SWC(m3/MWhr)
Annualgen@85%PLF(MWHr)
Annualwaterconsumption(m3)
WatercostinRs/m3
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
Kg/day
Rs/Kg
AnnualcostCrRs
5 346.8 250 3.16 346.8 85 1.08 15.75 46 0.03 930 85 2.89 2385 270 23.50 27.49 3.09 260610 805284 341.39
2 252.2 250 2.30 252.23 85 0.78 5.04 46 0.01 930 85 2.89 1363 270 13.43 17.11 4.95 260610 1290019 132.62
1.2 832.6 250 7.60 832.6 85 2.58 0 46 0.00 930 85 2.89 0 270 0.00 5.47 14.84 260610 3867452 14.14

24. Water cost = 81.588 x COC- 60.291
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6
WatercostRs/m3
COC

25. Cost Analysis - Chlorination plant (Existing Plant)
CAPITAL COST RUNNING COST
Items Cr Rs
Consumable
Items
Annual cost
in Cr Rs
Operation &
maintenance
Annual cost
in Cr Rs
Construction of
building
0.00
Chlorine
(stage I +II)
5.04
Machine spare items
@10% of investment
0.00
Mechanical
equipment
0.25
Electrical
equipment
0.00 Manpower 0.00
Monitoring
equipment
0.00 Electrical energy for
250KW load at 65%
PLF @ Rs 3.90/Kwhr
0.00
Others 0.00
Total Investment 0.25
Total Annual
cost
5.04
Deprication @10% 0.03
Total Annual Cost 0.00Annual cost for
expected life span
of 20 years
0.01
Total annual Operation & maintenance cost of the plant : Rs 5.05 Cr

26. Cost Analysis - CW treatment plant (New Plant)
CAPITAL COST RUNNING COST
Items Cr Rs
Consumable
Items
Annual cost in
Cr Rs
Operation &
maintenance
Annual cost in
Cr Rs
Construction of
building
3.00
Corrosion Inhibitor
(stage I +II)
5.15 Machine spare
items @10% of
investment
0.80
Mechanical
equipment
2.00
Scale Inhibitor
(Sage I+II)
1.76
Electrical
equipment
0.50 Biocide(Stage I +II) 0.05 Manpower 0.50
Monitoring
equipment
2.00 Acid (Stage I +II) 37.96 Electrical energy
for 250KW load at
65% PLF @ Rs
3.90/Kwhr
0.02Others 0.50 Others 0.5
Total Investment 8.00
Total Annual cost 45.42
Deprication @10% 0.80
Total Annual Cost 1.32Annual cost for
expected life span
of 20 years
0.36
Total annual Operation & maintenance cost of the plant : Rs 47.10 Cr

27. MCC1MCC2
CWPH TR 1
1250 KVA
CWPH TR 2
1250 KVA
Location Lay Out of the new plant
StageIICirculating
WaterPumpHouse
Fore Bay
Existing
Chlorination
plant
Proposed
plantof
250KWload
Circulation
waterpumpfor
dryflyash
compressor

28. Load on CWPH Tr - 2 Load on CWPH Tr - 1
Feeder
(A)
Fire water
pump P5
(KW)
Dry Ash
pump
(KW)
Chlorination
house
feeder (A)
Feeder
(A)
Fire water
pump P4
(KW)
Fire
water
pump M3
(KW)
600 160 75 200 600 160 75
KVA 249 136 63.75 83 249 136 63.75
Total KVA 531.75 448.75
Operating KVA
@75%
398.8125 336.5625
Transformer KVA
capacity
1250 1250
% Loading level 31.91% 26.93%
Existing loading level for transformer

29. Loading level calculation with additional load
Normal Emergency
Stages Stage II Stage II
Formula CWPH Tr 1 CWPH Tr 2 CWPH Tr 1 CWPH Tr 2
Rated KVA Capacity KVA 1250 1250 1250 1250
Rated primary KV KVp 6.6 6.6 6.6 6.6
Rated Primary Amps Ip = KVA/(1.732xKVp) 109.35 109.35 109.35 109.35
Rated secondary KV KVs 0.415 0.415 0.415 0.415
Rated Primary Amps Is = KVA/(1.732xKVs) 152.13 152.13 152.13 152.13
Operating primary current
(Amps)
A 35.00 35.00 70.00 0.00
Max operating KVA KVA1 = 1.732 xA x KVp 400.09 400.09 800.18 0.00
% Loading KVA1/KVA 32.01% 32.01% 64.01% 0.00%
Addition Load (KW) AL 125 125 250 0
Additional KVA KVA2= AL/0.85 147.06 147.06 294.12 0.00
Current additional Load KVA2/(1.732*KVs) 204.60 204.60 409.19 0.00
Operating additional KVA
@70%
KVA3 = (KVA2 x70%) 102.94 102.94 205.88 0.00
Operating KVA with
additional load
KVA4 = (KVA3+KVA2) 503.03 503.03 1006.07 0.00
Expected % Loading with
additional load
EL = (KVA3/KVA)x100 40.24% 40.24% 80.49% 0.00%

30. Clarification required
1. As per water analysis report , chlorine (Cl) level is 118 - 173 mg/l above the limiting
values 1.3mg/l . But free chlorine is found to be below detection level. It is to be
clarified.
2. When chlorine level is already very high, why additional chlorine dosing has been
recommended?
3. When chlorine dosing is already in practice , why biocide is required for controlling
micro organism
4. COC has been calculated on the basis of design water flow . Because of this reason
chemical requirement for the treatment is found to be too high and therefore the cost
of the water has become as high as Rs 340/ m3 or Rs 0. 34 / litre . Effort may be made
to minimize the cost of water by calculating the actual flow or some alternate water
treatment methods.
5. Huge quantity of acid dosing has been recommended. The impact of acid dosing on
metal corrosion is to be clarified. Environmental impact is also be clarified.
6. It is to be confirmed whether similar CW treatment method has been adopted by any
thermal power plant in India.

31. THANK YOU