Foster Wheeler North America Corp.

Horst Hack

Zhen Fan

Andrew H Seltzer

A method of controlling a boiler plant during a switchover period from an air-combustion mode to an oxygen-combustion mode. The method includes steps of feeding fuel into a furnace of the boiler plant at a rate determined by a fuel feeding scheme, feeding air into the furnace at a rate determined by a descending air feeding scheme, feeding substantially pure oxygen into the furnace at a rate determined by an ascending oxygen feeding scheme, and recirculating flue gas into the furnace at a rate determined by an ascending flue gas recirculating scheme. The fuel feeding scheme, the air feeding scheme and the oxygen feeding scheme are such that the fuel is combusted and the flue gas containing residual oxygen is produced. Also, the fuel feeding scheme, the air feeding scheme and the oxygen feeding scheme are such that the content of residual oxygen in the flue gas is, during at least a portion of the switchover period, greater than during any of the air-combustion mode and the oxygen-combustion mode. The method makes it possible to reduce COemissions and Oconsumption quickly during the short switchover period.

Method of controlling a boiler plant during switchover from air-combustion to oxygen-combustion

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.

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Lebanon, NJ, United States of America

Horst Hack