Subsection 7.2.4 Recovery
The only thing that remains to complete the cycle is to return the condensate to the boiler to be heated up again. Unfortunately, the condensate leaving the condenser is at a low pressure and the boiler operates at a much higher pressure. Condensate won’t flow back into the boiler by itself. A pump is required to raise the pressure and return the condensate to the boiler.
The pump, known as the feed pump, draws condensate from the condenser discharge, raises its pressure slightly above the boiler pressure, and discharges it back into the boiler to restart the cycle. Condensate leaving the feed pump is known as feedwater.
Work is required to drive the feed pump, and this energy reduces the net work produced by the cycle and available to turn the shaft. Fortunately, since water is incompressible it takes much less work to raise its pressure back to the boiler pressure than we get from an equivalent pressure drop across the turbine, and so there is a net positive amount of work produced by the cycle.
