Combustion Engineering, Inc.

Thomas J Dunn, Jr

Edward S Sadlon

Robert C Kunkel

Peter Kawa

An apparatus for introducing gas recirculation into a furnace to control steam temperature includes a hot air chamber for receiving hot air from an air preheater. The hot air chamber has at least one outlet communicating with the interior of the furnace. The apparatus includes a recirculation gas chamber for receiving recirculation gas from a recirculation fan and includes at least one outlet communicating with the interior of the furnace. Each of the chambers is disposed about at least a portion of the circumference of the furnace with one of the chambers disposed above at least a portion of the other. Ducts are provided between the hot air chamber and the air preheater and between the recirculation gas chamber and the recirculation fan to provide communication between the elements. A passageway is disposed between the hot air chamber and the recirculation gas chamber. The apparatus includes a valve movable between a first position wherein flow through the duct from the recirculation fan is blocked and flow through the passageway is open and a second position wherein flow through the passageway is blocked and flow through the duct from the recirculation fan in open.

Apparatus for introducing gas recirculation to control steam temperature

A method of operating a fossil fuel-fired power generation system (10, 10', 10', 10'') in order to thereby optimize the operating efficiency thereof. The fossil fuel-fired power generation system (10, 10', 10', 10''), which may or may not include an SCR (56), includes at least a fossil fuel-fired steam generator (12) having a burner region (16) wherein there is effected the combustion of fossil fuel and air such that gases of combustion are produced therefrom, a first heat transfer surface (32) located downstream of the burner region (16) of the fossil fuel-fired steam generator (12), a bypass (44,58,64) around the first heat transfer surface (32,32a), an air preheater (14) located downstream of the first heat transfer surface (32,32a), first and second flow paths from the burner region (16) of the fossil fuel-fired steam generator (12) to the air preheater (14) for the gases of combustion, a sensor (54) for sensing the temperature of the gases of combustion exiting from the air preheater (14), and when an SCR (56) is included a sensor (55) for sensing the temperature of the gases entering the SCR (56).

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Newington, CT, United States of America

Thomas J Dunn, Jr