EXHAUST GAS TREATING METHOD AND APPARATUS

摘要

The following devices are successively disposed in the following order fr om the upstream side to the downstream side in the discharge gas duct of a c ombustion apparatus: an air preheater which preheats combustion air for use in the apparatus for discharge gas treatment; a heat collector which recover s discharge-gas heat at the outlet of the air preheater; a dust collector wh ich collects soot/dust contained in the discharge gas at the outlet of the h eat collector; a wet flue-gas desulfurizer which removes sulfur oxides conta ined in the discharge gas at the outlet of the dust collector; and a reheate r which heats the discharge gas at the outlet of the wet flue-gas desulfuriz er. The heat collector and the reheater each has a heat transfer pipe, and a circulation line which connects the heat transfer pipes is disposed. A sulf uric anhydride (SO3) remover is supplied to the upstream side of the heat co llector, and the temperature of the discharge gas at the outlet of the heat collector is regulated to or below the dew point of the sulfuric anhydride. As the sulfuric anhydride remover, use is preferably made of at least any on e of a sulfuric anhydride adsorbent, sulfuric-anhydride-reducing agent, and sulfuric-anhydride-neutralizing agent. Thus, even when coal having a high su lfur content is used as a fuel, heavy metal(s)contained in the discharge gas can be effectively removed from the discharge gas.