CONTROL METHOD FOR BED TEMPERATURE IN MULTI-FUEL COMBUSTION FLUIDIZED BED BOILER

摘要

PURPOSE:To provide a multi-fuel combustion fluidized bed boiler with easy automatic operability by controlling the bed temp. of the boiler at a constant level in such a way that the height of the bed is changed according to the moisture content in combustibles when the combustibles containing moisture are burnt by mixed fuel in the fluidized bed boiler. CONSTITUTION:Coal is fed from a fuel supply hole 6 into a fluidized bed 4 and heated material 12 containing moisture is also fed at a constant volume into the bed 4 from a charge hole 14 for combustibles through a screw feeder 11 and a belt feeder 13 respectively and they are combusted in mixed state. The bed temp. in operation is controlled in the range of 800-900 deg.C by load control and the control of the bed height. In the control of the bed height, the bed temp. is reduced when the moisture content of combustibles containing moisture is increased and hence bed material is taken out by opening a take-out valve 17 for the bed material to reduce the bed height and the dipping area of a heat transfer tube 7 in the bed and the bed temp. is raised. The bed temp. is raised when the moisture content in the combustibles 12 is reduced and therefore, the bed material is increased in volume by opening a charge valve 16 for the bed material to increase the bed height h and the bed temp. is reduced.