Patent ID: 8286595

Claim:
An integrated water coil air heater and economizer arrangement for improving log mean temperature difference for a boiler, comprising: a feedwater inlet for supplying feedwater to the boiler; split means for splitting the feedwater from the inlet into a first partial high temperature, lower mass flow stream, and a second partial higher temperature, higher flow stream; a water coil air heater for passage of air to be heated for the boiler, the water coil air heater containing at least one heat transfer loop in heat transfer relationship with the air, the heat transfer loop of the water coil air heater being connected to the split means for receiving the first partial stream; an economizer for passage of flue gas to be cooled for the boiler, the economizer containing at least one heat transfer loop in heat transfer relationship with the flue gas, the heat transfer loop of the economizer being connected to the heat transfer loop of the water coil air heater for receiving the first partial stream from the water coil air heater; mixing means near a downstream end of the economizer for receiving and reuniting the first and second partial streams; and a conduit connected between the split means and the mixing means for passing the second partial stream to the mixing means.