Exhaust-gas treatment apparatus and exhaust-gas treatment method

Abstract

An object is to provide an exhaust-gas treatment apparatus capable of realizing a dissolved-salt spray method easily and at low cost. An exhaust-gas treatment apparatus that removes SO 2 and SO 3 contained in combustion exhaust gas includes a desulfurization apparatus based on the lime-gypsum method. Desulfurizing effluent, containing dissolved salt, from the desulfurization apparatus is sprayed to an upstream side of the desulfurization apparatus to remove SO 3 . A wet electrical dust precipitator may be provided downstream of the desulfurization apparatus. Furthermore, effluent from the wet electrical dust precipitator may be made to merge with the desulfurizing effluent from the desulfurization apparatus.

1 . An exhaust-gas treatment apparatus that removes SO 3  and dust contained in a combustion exhaust gas, comprising:
 a dry electrostatic precipitator that removes dust;   a dust-dissolving section that supplies an alkaline solution to dust collected by the dry electrostatic precipitator to dissolve the dust; and   a spray section that sprays effluent from the dust-dissolving section to an upstream side of the dry electrostatic precipitator.   
     
     
         2 . The exhaust-gas treatment apparatus according to  claim 1 ,
 wherein a desulfurization apparatus based on a lime-gypsum method is provided downstream of the dry electrostatic precipitator, and   desulfurizing effluent from the desulfurization apparatus is introduced to the dust-dissolving section.   
     
     
         3 . The exhaust-gas treatment apparatus according to  claim 2 , further comprising:
 a gypsum separator that separates gypsum from the desulfurizing effluent from the desulfurization apparatus,   wherein the effluent discharged from the dust-dissolving section is supplied to the gypsum separator.   
     
     
         4 . An exhaust-gas treatment method of removing SO 3  and dust contained in combustion exhaust gas, comprising:
 supplying an alkaline solution to dust collected by a dry electrostatic precipitator for removing dust to dissolve the dust; and   spraying effluent resulting after the dust is dissolved to an upstream side of the dry electrostatic precipitator.