AN ALTERNATE SORBENT FEEDING SYSTEM TO EFFECTIVELY CAPTURE POLLUTANT SULPHUR DIOXIDE IN A CIRCULATIN FLUIDIZED BED COMBUSTER (CFBC) BOILER

摘要

The invention relates to an alternate sorbent feeding system to effectively capture pollutant sulphur dioxide in a circulating fluidized bed combustor (CFBC) boiler, comprising a combustor (1) connected to a primary air fan (2) through air preheater (3) and an air distributor plate (4); a secondary air fan (5) for supplying air through a plurality of ports (6) into the combustor (1) for fluidizing the bed material including permitting a secondary combustion of the solid fuel, the solid fuel stored in a bunker (10) fed to the combustor (1) through a draglink chain feeder (11) and an air-lock feeder (12), the entrained solid particles being collected in at least one cyclone (7) and recycled to the combustor (1) through a seal pot (8) which is connected to a first blower (9), the combustion resulting in production of the pollutant sulphur dioxide out of the sulphur present in the fuel, an ash cooler (16) recovering the sensible heat from the coarser particles settled in the combustor (1), before the flue gas being allowed to emit to the atmosphere through a vortex finder (17), a flue gas duct (18), and a back pass (19),wherein the heat available in the flue gas being recovered in a superheater assembly (20, 21, 23, 3). The CFBC boiler being injected with sorbent in the form of limestone or dolomite during the combustion in the combustor (1) by adapting the alternate sorbent feeding system, the system comprising a sorbent bunker (13) connected to the drag link feeder (11) via at least one rotary feeder (14) for the sorbent; a second blower (15) connected to a first plurality of air-mixing nozzles (24) to restrict the pressure drop in the sorbent feed line below a minimum, a second plurality of nozzles (26) allowing injection of sorbent material into the combustor (1), the second plurality of nozzles (26) disposed above the air distributor plate (4) and injecting the sorbent including the secondary air into the combustor a(1) enabling an uniform dispersion of the sorbent across the combustor (1); and the sorbent feed line and the secondary air line connected to the second plurality of nozzles (26) at an angle between 30° and 45° with an elevation between 2 and 5 meters.