Patent ID: 7350471
Filing Date: 2008-04-01
Classification: F22B,F23C,F23L,Y02E

Abstract:
1. A method of combusting a fuel comprising the steps of: feeding an oxidizing gas stream and a fuel stream to a separate combustion chamber to form a hot flue gas stream, where the oxidizing gas stream comprises an effective oxidizing amount of an oxidizing agent stream and an effective cooling amount of a first recycled flue gas substream; mixing the hot flue gas stream with a second recycled flue gas substream to form a reduced temperature flue gas stream; transferring a portion of heat from the reduced temperature stream to a stream to be heated associated with a separate heat recover unit or a separate unit to be heated; forwarding a portion of the spent flue gas stream to a fan to increase its pressure to form a recycle flue gas stream; and splitting the recycled flue gas stream into the first and second recycled flue gas substreams, where the effective amount of the oxidizing agent stream is sufficient to produce a stoichiometric amount of oxygen to fuel or to produce a 25% or less excess of oxygen to fuel and the effective cooling amount of the recycled flue gas stream is sufficient to control a temperature of the hot flue gas to a desired high temperature and where the reduced temperature is sufficient for use in conventional heat exchangers without thermally damaging the heat exchanger.