Abstract: A combustor 110 is operative to effect therewith the combustion of fossil fuel 114? in order to thereby both heat to a working fluid 102 and generate a flue gas 104. An air preheater 144 receives the flue gas 104 generated in the combustor 110. A blower 180 causes air 188 to flow to the air preheater 144 when operating in an air fired mode, and causes both O2 and recycled flue gas 188? to flow when operating in the O2 firing mode. The air preheater 144 is operative to transfer heat from the flue gas 150 received thereby to the air 188 that is received when operating in an air fired mode or to both the received O2 and the recycled flue gas 188? that is received when operating in the O2 firing mode in order to thereby effect a preheating of the air 188 or of both the O2 and recycled flue gas, 188? depending upon the specific nature of the mode of operation thereof, and to thereby effect therewith a cooling of the flue gas received thereby.

Abstract: A combustor 110 combust a fluidized bed of fossil fuel 114, 114? to heat a working fluid 102 and generate flue gas 104. An air preheater 144 has first and second gas passageways 144a, 144b for respectively directing the generated flue gas 150 and another gas 250 with captured CO2 generated by combustion outside of the combustor 110. When operated in a non-CO2 capture, the air preheater 144 receives the flue gas 150, but not the other gas 250, and the first gas passageway 144a directs the flue gas 150 so as to preheat the air 188. However, when operated in the CO2 capture mode, the air preheater 144 receives the flue gas 150 and the other gas 250, and the second gas passageway 144b also directs the other gas 250 so as to preheat the air 188?. In either mode, the preheated air 188, 188? is applied by the combustor 110 to fluidize a bed of fossil fuel 114, 114?.

Abstract: A combustor 110 combust a fluidized bed of fossil fuel 114, 114? to heat a working fluid 102 and generate flue gas 104. An air preheater 144 has first and second gas passageways 144a, 144b for respectively directing the generated flue gas 150 and another gas 250 with captured CO2 generated by combustion outside of the combustor 110. When operated in a non-CO2 capture, the air preheater 144 receives the flue gas 150, but not the other gas 250, and the first gas passageway 144a directs the flue gas 150 so as to preheat the air 188. However, when operated in the CO2 capture mode, the air preheater 144 receives the flue gas 150 and the other gas 250, and the second gas passageway 144b also directs the other gas 250 so as to preheat the air 188?. In either mode, the preheated air 188, 188? is applied by the combustor 110 to fluidize a bed of fossil fuel 114, 114?.

Abstract: A combustor 110 is operative to effect therewith the combustion of fossil fuel 114? in order to thereby both heat to a working fluid 102 and generate a flue gas 104. An air preheater 144 receives the flue gas 104 generated in the combustor 110. A blower 180 causes air 188 to flow to the air preheater 144 when operating in an air fired mode, and causes both O2 and recycled flue gas 188? to flow when operating in the O2 firing mode. The air preheater 144 is operative to transfer heat from the flue gas 150 received thereby to the air 188 that is received when operating in an air fired mode or to both the received O2 and the recycled flue gas 188? that is received when operating in the O2 firing mode in order to thereby effect a preheating of the air 188 or of both the O2 and recycled flue gas, 188? depending upon the specific nature of the mode of operation thereof, and to thereby effect therewith a cooling of the flue gas received thereby.

Abstract: A circulating fluidized bed steam generator 10 and a method for operating the circulating fluidized bed steam generator are provided which offer the flexibility to use carbon dioxide (CO2) both as a desirable end product and as support to the combustion process. The method includes the step of introducing a substantially pure oxygen feed stream into the circulating fluidized bed steam generator 10 and the step of combusting a fuel in the presence of the substantially pure oxygen feed stream to produce a flue gas having carbon dioxide and water vapor as its two largest constituent elements by volume. The method also includes the step of passing the flue gas through an oxygen feed stream pre-heater 144 at which heat from the flue gas is transferred to the oxygen feed stream. Furthermore, the method includes the step of separating the flue gas into an end product portion and a recycling portion.

Abstract: An advanced overfire air system for NO.sub.x control designed for use in a firing system of the type that is particularly suited for use in fossil fuel-fired furnaces and a method of operating such a furnace which embodies an advanced overfire air system. The advanced overfire air system for NO.sub.x control includes multi-elevations of overfire air compartments consisting of a plurality of close coupled overfire air compartments and a plurality of separated overfire air compartments. The close coupled overfire air compartments are supported at a first elevation in the furnace and the separated overfire air compartments are supported at a second elevation in the furnace so as to be spaced from but aligned with the close coupled overfire air compartments.

Abstract: An advanced overfire air system for NO.sub.x control designed for use in a firing system of the type that is particularly suited for use in fossil fuel-fired furnaces and a method of operating such a furnace which embodies an advanced overfire air system. The advanced overfire air system for NO.sub.x control includes multielevations of overfire air compartments consisting of a plurality of close coupled overfire air compartments and a plurality of separated overfire air compartments. The close coupled overfire air compartments are supported at a first elevation in the furnace and the separated overfire air compartments are supported at a second elevation in the furnace so as to be spaced from but aligned with the close coupled overfire air compartments.