Power plants use many condensers to condense the steam for the turbine discharges.
After passing through the steam turbine, the steam becomes steam-exhausted and the pressure and temperature become lower. Had to pass this part of the condenser to dissipate heat. Turn steam into supercooled water. Then pump the water pressure hit high, into the boiler heating. If the lack of steam directly pressurized pump, due to lack of steam is the gas, the pump size will be large, unrealistic. Therefore, it is necessary to dissipate the heat of steam into water, liquid water volume, easy to pressurize, pump volume is moderate.