Air-fired co2 capture ready circulating fluidized bed steam generators

A method of generating steam either in an air fired mode or an O2 firing mode comprising the steps of:

• effecting the fluidization of fossil fuel to create a fluidized bed therefrom;
• effecting the combustion of such fossil fuel in order to effect both the heating therewith of a working fluid and the generation of flue gas;
• effecting the transfer of heat from such generated flue gas (i) to air in order to thereby effect both a preheating of such air and a cooling of such generated flue gas, when operating in the air fired mode, or (ii) to both O2 and recycled flue gas in order to thereby effect a preheating of both such O2 and such recycled flue gas and a cooling of such generated flue gas, when operating in the O2 firing mode;
• and
• effecting a fluidization of such fossil fuel with (i) such preheated air, when operating in the air fired mode, or (ii) with both such preheated O2 and such recycled flue gas, when operating in the O2 firing mode.

The method as claimed in 7, wherein such working fluid is a first working fluid, the combusting of such fossil fuel also generates residual hot solids that become entrained in such generated flue gas, and said method further comprises the steps of:

• effecting the separation of such entrained hot solids from such generated flue gas, wherein such generated flue gas that effects the transfer of such heat therefrom comprises separated flue gas;
• effecting the transfer of heat from such separated hot solids to a second working fluid in order to thereby effect a cooling therewith of such separated hot solids;
• effecting the fluidization of such cooled solids with air, when operating in the air fired mode, or with recycled flue gas, when operating in the O2 firing mode;
• and
• effecting the combustion of such fluidized cooled solids in order to thereby both heat such first working fluid and generate such flue gas.

An O2 firing steam generating system comprising:

• a fossil fuel combustor configured so as to be operative to (i) effect the fluidization of fossil fuel to thereby create a fluidized bed therefrom, (ii) to combust such fossil fuel for purposes of heating a first working fluid therewith and for generating a flue gas from such combustion of such fossil fuel, and (iii) to thereafter effect the exhausting of both such heated first working fluid and such generated flue gas;
• an air preheater configured so as to be operative to receive such generated flue gas from said fossil fuel combustor;
• a blower configured so as to be operative to cause both O2 and recycled flue gas to flow to said air preheater;
• a turbine configured so as to be operative to be driven by such exhausted heated first working fluid;
• wherein said air preheater (i) is operative to effect the transfer of heat from such received flue gas to both such O2 and recycled flue gas in order to thereby effect a preheating therewith of both such O2 and such recycled flue gas and a cooling of such received flue gas;
• and
• wherein said fossil fuel combustor is operative to effect the fluidization of such fossil fuel with both such preheated O2 and such recycled flue gas.