Patent ID: 8596075

Claim:
A method of power generation comprising: introducing a fuel, O 2 , and a CO 2 circulating fluid into a combustor, the CO 2 being introduced at a pressure of at least about 12 MPa and a temperature of at least about 400° C.; combusting the fuel to provide a combustion product stream comprising CO 2 , the combustion product stream having a temperature of at least about 800° C.; expanding the combustion product stream across a turbine to generate power, the turbine having an inlet for receiving the combustion product stream and an outlet for release of a turbine discharge stream comprising CO 2 , wherein the pressure ratio of the combustion product stream at the inlet compared to the turbine discharge stream at the outlet is less than about 12; withdrawing heat from the turbine discharge stream by passing the turbine discharge stream through a primary heat exchange unit to provide a cooled turbine discharge stream; removing from the cooled turbine discharge stream one or more secondary components that are present in the cooled turbine discharge stream in addition to CO 2 to provide a purified, cooled turbine discharge stream; compressing the purified, cooled turbine discharge stream with a first compressor to a pressure above the CO 2 critical pressure to provide a supercritical CO 2 circulating fluid stream; cooling the supercritical CO 2 circulating fluid stream to a temperature where its density is at least about 200 kg/m 3 ; passing the supercritical, high density CO 2 circulating fluid through a second compressor to pressurize the CO 2 circulating fluid to the pressure required for input to the combustor; passing the supercritical, high density, high pressure CO 2 circulating fluid through the same primary heat exchange unit such that the withdrawn heat from the turbine discharge stream is used to increase the temperature of the CO 2 circulating fluid; supplying an additional quantity of heat from a source other than withdrawn heat from the turbine discharge stream to all or a portion of the supercritical, high density, high pressure CO 2 circulating fluid one or more of prior to, during, or after passing through the primary heat exchange unit; and recycling the heated, supercritical, high density CO 2 circulating fluid into the combustor; wherein the temperature of the heated, supercritical, high density CO 2 circulating fluid entering the combustor is less than the temperature of the turbine discharge stream by no more than about 50° C.