CIRCULATING WATER SYSTEM

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CIRCULATING WATER SYSTEM


·      The circulating water system supply cold water to the condenser.
·      The cold water absorbs the latent heat of condensation from exhaust steam in the form of sensible heat.
·      Steam exhaust from low pressure steam turbine condenses in a condenser & condensed water reused in the cycle again.
·      In a surface condenser, the steam flows over a tube bundle & condensed and cooling water flowing inside the tubes.
·      Heat is transferred from steam to water with the help of tubes. Tubes are works as a barrier between cooling water and stem to be condensed.
·      Further the temperature of cooling water increases and become warm.
·      It is a continuous process in which heat is continues removed from the condenser.
·      This warm water reject their heat to the atmosphere through cooling towers or spray ponds or warm water dumped in to the natural water reservoir
·      In all thermal power plants surface condenser are used for condensing the steam
·      Two different systems are used to flow the water in to the condenser.
o   Once through system or open cooling system.
o   Closed loop system.


ONCE THROUGH SYSTEM OR OPEN COOLING SYSTEM.
In this system water from a large water reservoir (like sea, or river or lake) is pumped to the condenser.
When water become warm then returned back to the same source at different location.
So this system is used where a large quantity of water is available.

 Scheme of once through cooling system…

CLOSED LOOP COOLING SYSTEM

The second is the closed loop cooling system circulating water is in a closed circuit.
The Circulating water removes the heat from the condenser and flows to cooling towers.
In the cooling towers airflow, natural or forced, cools the water and the water returns to the condenser.
Power plants located away from large sources of water utilize this type.
The large concrete hyperbolic towers that you see near thermal power plants are used for cooling the circulating water.
In cooling towers loss of water takes place due to the evaporation to the atmosphere and it replaced by makeup water.

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