Patent ID: 8555796

Claim:
An oxy/fuel combustion system comprising: a furnace arranged and disposed to combust a fuel to form a combustion fluid; a convective section, the convective section having at least a first heat exchanger and a second heat exchanger downstream from the first heat exchanger, each heat exchanger arranged and disposed to exchange heat between the combustion fluid and steam; a flue gas recycle arranged and disposed to recycle at least a portion of the combustion fluid as a recycled flue gas, the flue gas recycle having two expellant locations downstream of a primary combustion zone and wherein at least one of the expellant locations is downstream of at least one of the heat exchangers; and a flow control mechanism arranged and disposed to selectively provide the recycled flue gas to the combustion fluid, the flow control mechanism having a plurality of conduits and capable of controlling flow of recycled flue gas; wherein one of the expellant locations is immediately upstream of the first heat exchanger and another of the expellant locations is downstream of the first heat exchanger and immediately upstream of the second heat exchanger; and wherein the flow control mechanism provides controlled amounts of the recycled flue gas to the two expellant locations and independently controls temperature of the steam at the two expellant locations.