Patent ID: 8075646

Claim:
A method for increasing efficiency of an integrated gasification combined cycle system comprising the steps of: producing a nitrogen gas product stream and an oxygen gas product stream using an air separation unit; feeding the oxygen gas product stream to a gasifier; producing a syngas stream in the gasifier using the oxygen gas product stream and coal; forming a fuel mixture stream using the syngas stream; heating at least a portion of at least one of the oxygen gas product stream, the fuel mixture stream, or both using heat from a heat recovery steam generator; heating the nitrogen gas product stream using heat from the heat recovery steam generator; heating the syngas stream with nitrogen gas product stream heated in the heat recovery steam generator; reheating the nitrogen gas product stream using heat from the heat recovery steam generator after heating the syngas stream with nitrogen gas product stream heated in the recovery steam generator; and mixing the heated nitrogen gas product stream with the syngas stream before being injected into a combustor.