The document provides information on the various cooling water systems used at the Nandipur 425/525 MW CCPP power plant, including: 1) Circulating water system which uses cooling towers and pumps to cool condenser water and includes chemicals added to prevent scaling. 2) Once-through cooling water system which takes in water directly from a water source for single-pass cooling and returns it. 3) Close cycle cooling water system which cools components like lube oil coolers in a closed loop using additives to prevent corrosion. 4) Service water system which provides cooling water for various plant equipment and customers. Modifications were made to the vacuum pump heat exchanger to lower its cooling water temperature and

1. Nandipur 425/525 MW CCPP
Training Course
Xiao Caifang
Operation Management
Department

2. COOLINGWATER SYSTEM
1.Circulating water
2.Once-through cooling water
3.Close cycle cooling water
4.Service water
5.Condensate water

3. 1.1 Main component
3 circulating water pumps(1900KW×3)
3 outlet hydraulic butterfly valves
9 cooling tower fans(200KW×9)
1. Circulating water

4. 1. Circulating water
1.2 Function
Condenser cooling water
ST heat exchanger
ST vacuum pump heat exchanger
GT heat exchanger

5. 1. Circulating water
1.3 Chemical dosing
HCO3
- ⇌ CO3
2- + H+
CO3
2- + Ca2+⇌CaCO3
H2SO4
Reduce the alkalinity of circulating water(HCO3
- )
Phosphate（ SHMP ）
Stabilizer——prevent the condenser from scaling
NaCLO——oxidizing fungicide
Quaternary-N QN-1400——non-oxidizing fungicide

6. 1.4 Auxiliaries
Sponge ball system
1. Circulating water

7. 1.4 Auxiliaries
Water strainer
1. Circulating water

8. 2.1 Main component
3 once-through cooling water pumps(1400KW×3)
3 outlet hydraulic butterfly valves
3 travelling screens
3 spray water pumps
1 travelling trash rake
3 sand and mud lifting pumps
2.Once-through cooling water

9. 2.2 Chemical dosing
NaClO——oxidizing fungicide
Quaternary-N QN-1400——non-oxidizing fungicide
2.Once-through cooling water

10. 2.Once-through cooling water
Once-through system
4200KW
Much trash
Low temperature
More maintenance work
Circulating system
7500KW
High hardness
2.3 Compare

11. 2.Once-through cooling water

12. 2.Once-through cooling water

13. 2.Once-through cooling water

14. 3.1 ST CCCW
Lube oil cooler(P oil＞P water）
EH oil cooler
Generator air cooler
Condensate pump mechanical seal
Condensate pump motor
3.Close cycle cooling water

15. 3.2 GT CCCW
Lube oil cooler
GT leg
Flame detector
Atomizing air cooler
Generator air cooler
3.Close cycle cooling water

16. 3.2 GT CCCW
3.Close cycle cooling water

17. Sodium nitrite
（NaNO2） + Borax
（ Na2B4O7·10H2O ）
Form a passivation
film on the inner
surface of the pipe to
prevent corrosion on
the inner surface of
the pipe
3.Close cycle cooling water
3.3 chemical dosing

18. 4.1 Customer
CW pump cooling water (once-through)
CW pump motor cooling water(once-through)
HRSG flash tank cooling water
Spray water pump cooling water
Sand and mud lifting pump cooling water
Sand filter
Vacuum pump heat exchanger
Evaporation and cooling unit
……
4.Service water

19. 4.2 modification of vacuum pump heat exchanger
4.Service water
Effect of working water temperature on pumping capacity of vacuum pump

20. 4.2 modification of vacuum pump heat exchanger
4.Service water

21. 4.2 modification of vacuum pump heat exchanger
4.Service water
工作液进口水温working water
inlet temp
60℃
工作液出口水温working water
outlet temp
37.5℃
循环水进口水温CW inlet temp 34℃
循环水出口水温CW outlet temp 40℃
工作液进口水温working water
inlet temp
52.5℃
工作液出口水温working water
outlet temp
30℃
循环水进口水温CW inlet temp 25℃
循环水出口水温CW outlet temp 32.5℃
Before
modification
After
modification

22. LP cylinder spray water
HP/LP desuperheating water
LP gland steam desuperheating water
Condenser flash tank
5.Condensate water

23. Thank you！