Patent ID: 7669403

Claim:
A method for operating a power plant, which power plant includes at least one compressor, at least one turbine, and at least one burner arrangement including at least one pre-burner and at least one afterburner, the method comprising: compressing an oxidizer gas containing oxygen gas in the compressor; burning the compressed oxidizer gas under lean conditions and with a fuel gas in at least one pre-burner of the burner arrangement; feeding a combustion exhaust gas from the pre-burner to an oxygen-removal device which removes part of the oxygen gas from the combustion exhaust gas in which said oxygen gas part is contained; burning the combustion exhaust gas with a reduced oxygen content with a fuel gas downstream of the oxygen-removal device in at least one afterburner of the burner arrangement; feeding a combustion exhaust gas from the afterburner to the turbine and expanding said combustion exhaust gas from the afterburner in the turbine; discharging the oxygen removed from the combustion exhaust gas from the pre-burner from the oxygen-removal device by a sweep gas, wherein the sweep gas is an inert gas or a fuel-free gas; providing a synthesis gas generator which generates a synthesis gas containing hydrogen gas from a fuel, steam, and oxygen gas; providing a synthesis gas cooler arranged in a synthesis gas path which leads from the synthesis gas generator to the at least one pre-burner, to the at least one afterburner, or to both; supplying oxygen gas removed from the combustion exhaust gas from the at least one pre-burner with the oxygen-removal device to the synthesis gas generator; feeding synthesis gas generated by the synthesis gas generator as fuel gas to the at least one pre-burner, to the at least one afterburner, or to both; and providing a steam generating device incorporated in an exhaust gas path of the turbine; evaporating a liquid with the aid of a turbine exhaust gas; cooling the turbine exhaust gas while evaporating said liquid; applying high pressure with the steam generating device to the steam; expanding the high-pressure steam in a steam turbine; and removing partially expanded steam from the steam turbine as medium-pressure steam, and admixing said partially expanded steam to the synthesis gas between the synthesis gas cooler and the at least one pre-burner, the at least one afterburner, or both.