Cooling Towers

1. SAURABH BISWAS [001511502004]
SATYAKI CHANDRA [001511502006]
SWAROOP MONDAL [001511502016]
POWER ENGINEERING DEPARTMENT
J.U. (S.L. CAMPUS)

2.  In a thermal power plant about 40-45% of total heat input
to the plant is finally dissipated as waste heat. The waste
heat from the power plant is carried away by circulating
water and ultimately gets dissipated in cooling tower.
 A cooling tower is an air and water management device,
which consists of fan stacks, fans, drift eliminators, fill and
water/air distribution systems.
 It uses principle of evaporation of water in unsaturated air.

3. A cooling tower is a specialized heat exchanger in which two fluids (air & water)
are brought into direct contact with each other to effect the transfer of total heat.
The water vaporizes and steam+air goes out and thus rejects latent heat of
evaporation.

6. Structure
Cooling tower
[natural draft type]

7. Water distributing system and nozzles
Fills [heat exchanger surfaces]

8. Fan
Drift eliminators

9. Natural draft Induced draft Forced draft
|_______________________|
Mechanical draft

11. Range = hot CW inlet temperature
-cold CW outlet temperature
Approach = cold CW outlet temperature
- wet bulb temperature
Cooling
Efficiency
Actual cooling
Maximum possible cooling
_____Range______
Range + Approach
=
=
Cooling Capacity = mass flow rate of water X specific heat
X temperature difference

12. The findings of a typical trial pertaining to the Cooling Towers
of a Thermal Power Plant 2 x 200 MW
Total Load of the Station = 398 MW
Inlet Cooling Water Temperature = 44°C (Rated 43°C)
Outlet Cooling Water Temperature = 37.6°C (Rated 33°C)
Air Wet Bulb Temperature near Cell = 29.3°C (Rated 27.5°C)
Air Dry Bulb Temperature near Cell = 40.8°C
Total Measured Cooling Water Flow = 70426.76 metre cube /hour
Measured CT Fan Flow = 989544 metre cube/hour
Range = (44 – 37.6)°C = 6.4°C
Approach = (37.6 – 29.3)°C= 8.3°C
Cooling efficiency = 6.4/(6.4+8.3) = .4353 or 43.53%

14. References
1. Power Plant Engineering by P.K.Nag
2. D.V.C. : cooling tower slides
3. Bureau of Energy Efficiency : cooling tower handout
4. S.P.X. cooling tower reference guide
5. Google
6. Wikipedia

15. SAURABH BISWAS [001511502004]
SATYAKI CHANDRA [001511502006]
SWAROOP MONDAL [001511502016]
POWER ENGINEERING
DEPARTMENT
J.U. (S.L CAMPUS)