Method and apparatus for controlling temperature in combustion furnace in gasification equipment

An apparatus for controlling a temperature in a combustion furnace in a gasification equipment comprising a gasification furnace for gasifying a raw material through formation of a fluidized bed by introduction of water vapor and a combustion furnace for blowing up with air the bed material introduced together with unreacted char from said gasification furnace to heat the bed material through combustion of said char, the bed material heated in said combustion furnace being separated from a combustion exhaust gas and returned to said gasification furnace, the apparatus comprising:

• water vapor rate detection means for detecting a rate of the water vapor to the gasification furnace;
• raw material rate detection means for detecting a rate of the raw material to the gasification furnace;
• gasification furnace temperature detection means for detecting a temperature in the gasification furnace;
• bed material circulated rate detection means for detecting a circulated rate of the bed material;
• combustion furnace air flow rate detection means for detecting a flow rate of air to the combustion furnace;
• combustion furnace temperature detection means for detecting a temperature in a top of the combustion furnace;
• auxiliary fuel feed rate detection means for detecting a feed rate of an auxiliary fuel to the combustion furnace;
• and
• a controller with
• a first map for defining a feed rate of the char from the gasification furnace to the combustion furnace on the basis of the rate of the water vapor and the rate of the raw material to the gasification furnace at a rated point;
• a second map for defining as number an influence of the temperature of the gasification furnace and the circulated rate of the bed material on said feed rate of the char;
• a multiplier for multiplying the feed rate of the char at a rated point read out from a current rate of the water vapor and a current rate of the raw material to the gasification furnace according to the first map by the number read out from a current temperature in the gasification furnace and a current circulated rate of the bed material according to the second map to thereby calculate an actual feed rate of the char;
• a third map for defining a gross heat value of the char flowing into the combustion furnace on the basis of said actual feed rate and heat value of the char and;
• a subtracter for a subtraction between the gross heat value of the char flowing into the combustion furnace read out according to said third map and the heat value required for keeping the top of the combustion furnace at the commanded temperature read out from the commanded temperature in the top of the combustion furnace and the flow rate of air to the combustion furnace according to the fourth map to determine an heat value required for keeping the combustion furnace at the commanded temperature;
• a fifth map for readout of an operation rate of an auxiliary fuel from said required heat value so as to output an advanced command to an auxiliary fuel feeder;
• and
• a subtracter for performing a subtraction between said commanded temperature and a detected temperature in the top of said combustion furnace and a proportional integrator for regulating said operation rate of the auxiliary fuel such that a difference obtained by the subtracter becomes zero so as to provide a feedback control for said auxiliary fuel feeder.