COMBUSTION METHOD FOR PRESSURIZED AND FLUIDIZED BED

PURPOSE:To provide a high efficiency of combustion and a high efficiency in operation of a plant by a method wherein a dead-burned alkaline earth metallic oxide substances are applied as fluidized bed substance, a temperature of the fluidized bed is kept at a high temperature and hot combustion gas is fed into a gas turbine. CONSTITUTION:Although dead-burned lime supplied to a fluidized bed forms a fluidized bed 7 together with coal ashes, the lime is gradually made into powder and scatters, so the dead-burned lime is supplied continuously or intermittently. A volume of a thermal conducting pipe 4 is defined in advance through a calculation of a thermal balance in the fluidized bed in such a way as a temperature of the fluidized bed is at least 950 deg.C. In this way, the fluidized bed has a major constituent of dead-burned lime, a reduction speed of thickness of a wall of the thermal conducting pipe 4 is quite slow and so the pipe can be used for a longer period. Hot combustion gas is sent to a gas turbine 12 after its dust is removed by a dust collector 11. The gas turbine 12 is connected to an air compressor 13 and a generator 14. Since hot combustion gas from a pressurized and fluidized bed 7 can be utilized, a high thermal efficiency can be attained.