Feedwater heating applications span almost all industries. Any heat added at
any temperature level above the incoming makeup water temperature is heat that
is saved in terms of fossil fuel consumption (or power consumption in an
electric boiler or water heater). Many boiler steam end users consume steam or make
the condensate return impractical. Therefore, many boilers require
considerable feedwater makeup. In addition, many processes require heated feedwater that
is consumed by or used in the process itself. Some of this feedwater heating
can economically be supplied by heat exchange and heat pump concepts using
suitable sources of waste heat available in the plant.
Boiler or process feedwater heating applications are open-loop systems. In an open-loop system, incoming feedwater is heated through a relatively high temperature range and then supplied to the process load and consumed or not returned for other reasons.
To get the most energy out of the heat source with the least electrical input to the heat pump, it is usually desirable to transfer as much heat as possible using heat exchange. The remaining temperature amplification can then be provided (according to the economics) through use of a heat pump.
