Patent ID: 7475544

Claim:
A steam generator system comprising a coal-fired steam generator in fluid communication with a regenerative air preheater; said steam generator being adapted to receive a flow of heated combustion air exiting from said regenerative air preheater and to discharge a flow of hot flue gas to said regenerative air preheater; said regenerative air preheater adapted to receive a flow of cool air in counter flow to said flow of hot flue gas and to provide a heat exchange between said cool air and said hot flue gas to convert said cool air into said heated combustion air exiting to said steam generator; said steam generator system further comprising a first flow of heated air, routed through a source of pulverized coal to form a mixture comprising heated air and pulverized coal; said mixture being directed to said steam generator for combustion therein; and a recycle fluid flow consisting of an additional flow of air not required for combustion, diverted from the total air leaving said regenerative air preheater, directed by means of a fan to re-enter said regenerative air preheater at a location substantially separate from where said flow of cool air is received in said regenerative air preheater to be further heated therein and exit as part of the total flow leaving the regenerative air preheater.