A method of and a power
plant for generating power by combusting carbonaceous fuel with substantially
pure oxygen, and a method of modifying a process of generating power by combusting carbonaceous fuel from combusting the fuel with air to combusting the fuel with substantially
pure oxygen. The methods include feeding substantially
pure oxygen into a furnace for combusting fuel with the
oxygen to produce
exhaust gas including mainly
carbon dioxide and water, recovering 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; pressurizing a first portion of the exhaust gas in multiple exhaust gas compressors so as to produce
liquid carbon dioxide, recycling a second portion of the exhaust gas to the furnace via an exhaust gas recycling channel, using a first portion of steam extracted from a
steam turbine system 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, or larger than the first portion of the recovered low-grade heat in the air-fired process, allowing minimizing of the first portion of the extracted steam, and the expanding of 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.