Feed Water and Steam Circuit and Cooling Water Circuit of Thermal Power Plant
Feed Water and Steam Circuit
- The steam from turbine is condensed in the condenser, then it is heated in a closed feed water heater by means of extracted steam from the low pressure extraction point of the turbine.
- This heated water then passes through evaporator and few more water heaters before it is made to go to the boiler through the economizer.
- The reduced quantity of water is made up by adding water in the feed water system.
- Raw water from river or canal system passes through evaporator, is heated to steam and condensed into water in the evaporator and then passes through feed water pump into the feed water system in the boiler. Refer Figure.
- In the boiler drum and tubes water circulates, steam which contains particles of water from the boiler drum is further heated in the superheater before used for turbines.
- The steam then expands in the high pressure turbine and is taken to the reheat boiler where its temperature is increased or it is superheated and then passed to low pressure turbine, from this turbine it is exhausted through the condenser into the hot well.
Cooling Water Circuit
- Ample quantity of cooling water is required to condense the steam from turbines in the condenser and maintaining low pressure in it.
- If river or canal is nearby, cooling water may be taken from the upper side of the river or canal and after passing it through the condenser may be discharged to the lower side of the river or canal; such a system will be possible only when ample water is flowing through the river or canal throughout the year.
- When sufficient quantity of water is not available, water from the condenser may be used either in a cooling pond or cooling towers and reused.
- The quantity of water reduced in the cycle is made up by other sources of water.