Abstract: A char 7 feed rate at a rated point determined from a relationship between a current water vapor 3 flow rate and a current raw material 5 charge rate to a gasification furnace 1 is multiplied by a proper number determined from a relationship between a current gasification furnace 1 temperature and a current bed material 4 circulated rate to calculate an actual char 7 feed rate. A subtraction is performed between a gross heat value of the char 7 flowing into the combustion furnace 2 determined on the basis of the calculated char 7 feed rate and a heat value required for keeping a top of the combustion furnace 2 at a commanded temperature determined from a relationship between the commanded temperature and an air flow rate in the furnace 2 to determine a heat value required for keeping the combustion furnace 2 at the commanded temperature.

Abstract: A fluidized bed gasification furnace has a fluidized bed formed and a freeboard section F above a bed material so as to produce a produced gas by a reaction of raw material with a gasifying agent and take out the produced gas through the freeboard section. Upon shutdown of the furnace, inert gas is fed from below to the furnace for purging of gas in the fluidized bed with inert gas while steam is supplied to a freeboard section above the fluidized bed to purge a gas in the freeboard section with steam.

Abstract: Upon cold startup of a gasification facility, a fluidized air 10 is supplied to a combustion furnace 9 to fluidize a combustion-furnace fluidized bed 11 while a preheating fuel 22 is supplied to the combustion furnace to preheat the fluidized bed 11 up to an autoignition temperature of coal. Then, a coal 23 is charged to the combustion furnace 9 to heat the fluidized bed 11 and bed material is circulated between the combustion and gasification furnaces 9 and 1 for heating. Upon startup and shutdown of the gasification facility, steam 2 from an exhaust heat recovery boiler 20 in heat exchange with an exhaust gas 15 from the combustion furnace 9 is supplied to the gasification furnace 1 to purge the gasification furnace 1 and a lead-out passage 6 with the steam 2 utilizing the exhaust heat.

Abstract: A char 7 feed rate at a rated point determined from a relationship between a current water vapor 3 flow rate and a current raw material 5 charge rate to a gasification furnace 1 is multiplied by a proper number determined from a relationship between a current gasification furnace 1 temperature and a current bed material 4 circulated rate to calculate an actual char 7 feed rate. A subtraction is performed between a gross heat value of the char 7 flowing into the combustion furnace 2 determined on the basis of the calculated char 7 feed rate and a heat value required for keeping a top of the combustion furnace 2 at a commanded temperature determined from a relationship between the commanded temperature and an air flow rate in the furnace 2 to determine a heat value required for keeping the combustion furnace 2 at the commanded temperature.

Abstract: Upon cold startup of a gasification facility, a fluidized air 10 is supplied to a combustion furnace 9 to fluidize a combustion-furnace fluidized bed 11 while a preheating fuel 22 is supplied to the combustion furnace to preheat the fluidized bed 11 up to an autoignition temperature of coal. Then, a coal 23 is charged to the combustion furnace 9 to heat the fluidized bed 11 and bed material is circulated between the combustion and gasification furnaces 9 and 1 for heating. Upon startup and shutdown of the gasification facility, steam 2 from an exhaust heat recovery boiler 20 in heat exchange with an exhaust gas 15 from the combustion furnace 9 is supplied to the gasification furnace 1 to purge the gasification furnace 1 and a lead-out passage 6 with the steam 2 utilizing the exhaust heat.

Abstract: A fluidized bed gasification furnace has a fluidized bed formed and a freeboard section F above a bed material so as to produce a produced gas by a reaction of raw material with a gasifying agent and take out the produced gas through the freeboard section. Upon shutdown of the furnace, inert gas is fed from below to the furnace for purging of gas in the fluidized bed with inert gas while steam is supplied to a freeboard section above the fluidized bed to purge a gas in the freeboard section with steam.