Elements of Condensing Plant

• The various components of a condensing plant are shown schematically in Figure A and B depending upon the availability of cooling water needed for condensing the exhaust steam.
• In case of large capacity power plants, the requirement of cooling water is millions of litres per hour.
• If the water is available freely either from a river or lake then the water is directly pumped from the river to the condenser through the scrubbers or the filters in order to remove impurities.
• If the water is not freely available then a cooling tower or a similar arrangement for cooling the hot water of the condenser is needed.
• Because of large quantity of water requirements, the steam power plants are usually situated near the river or lake.

The main elements of the condensing plants are :

1. Condenser in which the exhaust steam of the turbine is condensed by circulating cooling water.
2. Condensate extraction pump to remove the condensate from the condenser and feed it into the hot-well. The feed water from hot-well is further pumped to the boiler.
3. Air extraction pump to remove air from the condenser. Such a pump is called dry air pump. In some type of condensers, a pump is used to remove both the condensate and air, such a pump is called wet air pump.
4. Circulating pump is used to supply feed water either from the river or from the cooling tower pond to the condenser.
5. A cooling tower in which the hot water from the condenser is cooled by rejecting heat to current of air passing in the counter direction .

• The cooling tower is made of ferro concrete, usually of hyperbolic shape. The hot water from the condenser is supplied to ring troughs which are placed at 8-10 m above the ground level.
• The nozzles are attached to the bottom side of ring troughs. The water drips down from the troughs into the nozzle, from where it falls into the form of thin droplets.
• The air rises up from the pond in the counter direction of water flow and absorbs heat from the water falling from the troughs.
• The cooled water is collected into a pond built below the cooling tower.
• This type of system for cooling the hot water is very efficient, however, it needs about 3 to 5% of makeup water in order to compensate the evaporation losses.