A method for steam generation having reduced emissions, the method comprising: (a) providing an oxidant enriched gas stream having an oxygen content of 21 to 100% by volume; (b) combusting at least a portion of a fuel stream in the presence of the oxidant enriched gas stream in a combustion zone to produce a flue gas and heat, wherein the fuel stream comprises impurities selected from group consisting of nitrogen, sulfur, and combinations thereof, wherein the combustion zone is comprised of at least two combustion chambers (10,20), and wherein each combustion chamber has an internal temperature gradient; (c) regulating said internal temperature gradients of each combustion chamber using a plurality of heat exchangers (HX1,HX2) such that the flue gas temperature at the exit of the combustion chambers is within a predetermined temperature range of 800 to 1400° Celsius, wherein said heat exchangers employ the use of water, wherein the enthalpy of the water is increased, the water having a phase, the phase selected from the group consisting of gaseous phase, liquid phase, or combinations thereof; and (d) introducing the flue gas into a flue gas cleaning chamber to produce a third product stream comprised of spent adsorbent and desulfurized flue gas, wherein the desulfurized flue gas has reduced amounts of SO x as compared to the flue gas, the flue gas cleaning chamber having an amount of adsorbent contained therein that is operable to remove at least a portion of SO x from the flue gas; and (e) recycling the spent adsorbent back to the flue gas cleaning chamber wherein the step of recycling the spent adsorbent comprises sending a portion of a spent adsorbent recycle stream via an adsorbent regenerator to produce a regenerated adsorbent, and combining the regenerated adsorbent with the remainder of the spent adsorbent recycle stream prior to an inlet of the flue gas cleaning chamber. (a) providing an oxidant enriched gas stream having an oxygen content of 21 to 100% by volume; (b) combusting at least a portion of a fuel stream in the presence of the oxidant enriched gas stream in a combustion zone to produce a flue gas and heat, wherein the fuel stream comprises impurities selected from group consisting of nitrogen, sulfur, and combinations thereof, wherein the combustion zone is comprised of at least two combustion chambers (10,20), and wherein each combustion chamber has an internal temperature gradient; (c) regulating said internal temperature gradients of each combustion chamber using a plurality of heat exchangers (HX1,HX2) such that the flue gas temperature at the exit of the combustion chambers is within a predetermined temperature range of 800 to 1400° Celsius, wherein said heat exchangers employ the use of water, wherein the enthalpy of the water is increased, the water having a phase, the phase selected from the group consisting of gaseous phase, liquid phase, or combinations thereof; and (d) introducing the flue gas into a flue gas cleaning chamber to produce a third product stream comprised of spent adsorbent and desulfurized flue gas, wherein the desulfurized flue gas has reduced amounts of SO x as compared to the flue gas, the flue gas cleaning chamber having an amount of adsorbent contained therein that is operable to remove at least a portion of SO x from the flue gas; and (e) recycling the spent adsorbent back to the flue gas cleaning chamber wherein the step of recycling the spent adsorbent comprises sending a portion of a spent adsorbent recycle stream via an adsorbent regenerator to produce a regenerated adsorbent, and combining the regenerated adsorbent with the remainder of the spent adsorbent recycle stream prior to an inlet of the flue gas cleaning chamber.