Patent ID: 7874140

Claim:
A method of generating power in a power plant by combusting carbonaceous fuel with substantially pure oxygen, the method comprising the steps of: (a) feeding carbonaceous fuel into a furnace; (b) feeding substantially pure oxygen from an oxygen supply into the furnace for combusting the fuel with the oxygen to produce exhaust gas comprising mainly carbon dioxide and water; (c) discharging the exhaust gas via an exhaust gas channel from the furnace; (d) recovering a total amount of low-grade heat from the exhaust gas by using multiple exhaust gas coolers arranged in a downstream portion of the exhaust gas channel, wherein a first portion of the recovered low-grade heat is used for preheating feedwater; (e) converting preheated feedwater to steam by recovering high-grade heat in heat exchange surfaces arranged in the furnace and in an upstream portion of the exhaust gas channel; (f) pressurizing a first portion of the exhaust gas in multiple exhaust gas compressors so as to produce liquid carbon dioxide; (g) recycling a second portion of the exhaust gas to the furnace via an exhaust gas recycling channel; (h) expanding the steam in a steam turbine system for driving a power generator; (i) extracting a total amount of steam from the steam turbine system, and using a first portion of the extracted steam to preheat feedwater, wherein the first portion of the recovered low-grade heat is more than 50% of the total amount of recovered low-grade heat allowing minimizing of the first portion of the extracted steam, and the method comprising a further step of: (j) expanding a second portion of the extracted steam in at least one auxiliary steam turbine for driving at least one compressor or at least one pump of the power plant.