Patent ID: 8529646

Claim:
A process for operating an integrated gasification combined cycle (IGCC) plant, the IGCC plant comprising a gasifier for gasifying coal to produce syngas, a syngas combustion system for combusting the syngas to produce electricity, and a premixed combustion system for combusting a combustion gas other than syngas to produce additional electricity, the process comprising: operating the gasifier to produce synthesis gas at a substantially constant rate less than a rate sufficient for the syngas combustion system to produce enough electricity to meet a peak electrical demand; when a current demand for electricity is below a base load that could be produced by supplying syngas to the syngas combustion system at the substantially constant rate, supplying a first portion of the synthesis gas from the gasifier to the syngas combustion system sufficient to meet the current electrical demand, and transforming a second portion of the synthesis gas into liquid fuel and storing the liquid fuel; and when a current demand for electricity is above the base load that could be produced by supplying synthesis gas to the syngas combustion system at the substantially constant rate, supplying all of the syngas from the gasifier to the syngas combustion system to meet a first portion of the current demand, producing, using the liquid fuel stored when the demand for electricity was below the base load, a fuel gas by vaporizing the liquid fuel and combining it with a first gas, the first gas having an oxygen content less than that of ambient air, contacting the fuel gas with a second gas, the second gas comprising at least one oxidizing agent, to form the combustion gas, and combusting the combustion gas in the premixed combustion system to produce sufficient electricity to meet a second portion of the current demand.