Purificn. of flue gas from fluidised-bed combustor - by contact with iron oxide, vanadium pent:oxide and limestone

摘要

Removal of pollutants (SO2, NO2, HCl, HF) from flue gases generated in a fluidised-bed combustion unit is carried out by (a) injecting a Fe-contg. material (I) into the hot zone (above 850 deg.C) of the fluidised bed, (b) contacting the gas at 400 deg.C with a V205 catalyst, (c) injecting the gas into a fluidised bed of ground limestone at 180 deg.C, and (d) cooling the gas by heat exchange and separating CaSO4 in a filter unit. Specifically (I) is Fe2O3 and/or FeSO4 or some other Fe-contg. waste product convertible to Fe3O4 at the working temp. The combined catalytic action of the Fe3O4 and V205 provides practically 100% conversion of SO2 to SO3, which reacts with the limestone to form CaSO4 as a useful by-product (e.g. for cement mfr.).