Patent ID: 7832191

Claim:
An integrated gasification combined cycle provided with a gasification unit and a combined power generation unit that uses a gas produced in the gasification unit as a fuel and generates power by rotating a gas turbine and a steam turbine using a fuel gas produced in the gasification unit, in the combined power generation unit comprising: a power load control system that controls the combined power generation unit so that the power generation output corresponds to a power load request; a gasification furnace load control system that controls the gasification unit so as to produce fuel gas with a production rate corresponding to the power load request; an auxiliary fuel supply device capable of supplying an auxiliary fuel instead of the fuel gas; a flare stack which is connected to a fuel gas feed line and emits the fuel gas as a flare when the pressure of the fuel gas becomes a predetermined pressure or more; and a flare valve that controls a flaring amount emitting from said flare stack and a control system thereof; wherein the integrated gasification combined cycle enables a fuel change over operation from the fuel gas to the auxiliary fuel and from the auxiliary fuel to the fuel gas; in the fuel change over operation, the control system of the flare valve has a dead time compensation circuit that compensates a dead time and a control delay of the gasification unit and the gasification furnace load control system that controls the operation of the gasification unit uses a request of the degree of opening for said flare valve as an advanced signal.