Wet Type Flue-Gas Desulfurization Apparatus and Thermal Power Plant Having the Same

Abstract

A wet type flue-gas desulfurization apparatus, into which exhaust gas containing mercury goes, includes an upstream absorption tower, an upstream absorbent spray nozzle and a make-up water supply unit on an upstream side of a desulfurization apparatus body in a flow direction of the gas. The upstream absorption tower has a circulation tank reserving absorbent slurry. The make-up water supply unit supplies make-up water into the circulation tank to keep the chloride ion concentration of the absorbent in the circulation tank not lower than 50,000 ppm. Thus, it is possible to provide a wet type flue-gas desulfurization apparatus by which Hg can be prevented from being released again from the desulfurization apparatus, the purity of recovered gypsum can be increased and the usage of industrial water can be reduced.

1 . A wet type flue-gas desulfurization apparatus comprising:
 an absorption tower which has a circulation tank in a lower portion thereof, the circulation tank reserving absorbent slurry;   an absorbent spray nozzle which is placed inside the absorption tower to spray the absorbent slurry;   an oxidation gas supply portion which supplies oxidation gas to the absorbent slurry reserved in the circulation tank; and   a desulfurization apparatus body which includes the absorption tower, the absorbent spray nozzle and the oxidation gas supply portion, and in which gas to be treated, containing sulfur compounds, is introduced into the absorption tower and brought into gas-liquid contact with the absorbent slurry sprayed from the absorbent spray nozzle, so that the sulfur compounds in the gas to be treated can be absorbed by the absorbent slurry; wherein:   the gas to be treated contains mercury; and   the desulfurization apparatus further comprises:   an upstream absorption tower which includes a circulation tank reserving absorbent slurry;   an upstream absorbent spray nozzle which is placed inside the upstream absorption tower to spray the absorbent slurry; and   a make-up water supply unit which supplies make-up water into the circulation tank to keep a chloride ion concentration of the absorbent in the circulation tank not lower than 50,000 ppm, the upstream absorption tower, the upstream absorbent spray nozzle and the make-up water supply unit being disposed on an upstream side of the desulfurization apparatus body in a flow direction of the gas to be treated.   
     
     
         2 . A wet type flue-gas desulfurization apparatus according to  claim 1 , wherein:
 the make-up water is seawater.   
     
     
         3 . A wet type flue-gas desulfurization apparatus according to  claim 1 , wherein:
 the make-up water is chloride-ion concentrated water obtained by a concentrated water manufacturing apparatus.   
     
     
         4 . A wet type flue-gas desulfurization apparatus according to  claim 3 , wherein:
 the concentrated water manufacturing apparatus is a desalination apparatus which obtains water from seawater so that the water obtained by the desalination apparatus can be used as rinse water for gypsum obtained by reaction between the gas to be treated and the absorbent.   
     
     
         5 . A wet type flue-gas desulfurization apparatus according to  claim 1 , further comprising:
 an upstream mist eliminator which is provided between the upstream absorbent spray nozzle and the desulfurization apparatus body so that collected liquid obtained by the upstream mist eliminator can be returned to the upstream absorption tower.   
     
     
         6 . A thermal power plant comprising:
 a boiler apparatus; and   a wet type flue-gas desulfurization apparatus which eliminates sulfur compounds from exhaust gas discharged from the boiler apparatus;   
       wherein:
 the wet type flue-gas desulfurization apparatus is a wet type flue-gas desulfurization apparatus according to  claim 1 . 
 
     
     
         7 . A thermal power plant according to  claim 6 , further comprising:
 a denitration apparatus which is provided on an upstream side of the wet type flue-gas desulfurization apparatus in a flow direction of the exhaust gas.   
     
     
         8 . A thermal power plant comprising:
 a boiler apparatus; and   a wet type flue-gas desulfurization apparatus which eliminates sulfur compounds from exhaust gas discharged from the boiler apparatus;   
       wherein:
 the wet type flue-gas desulfurization apparatus is a wet type flue-gas desulfurization apparatus according to  claim 2 . 
 
     
     
         9 . A thermal power plant comprising:
 a boiler apparatus; and   a wet type flue-gas desulfurization apparatus which eliminates sulfur compounds from exhaust gas discharged from the boiler apparatus;   
       wherein:
 the wet type flue-gas desulfurization apparatus is a wet type flue-gas desulfurization apparatus according to  claim 3 . 
 
     
     
         10 . A thermal power plant comprising:
 a boiler apparatus; and   a wet type flue-gas desulfurization apparatus which eliminates sulfur compounds from exhaust gas discharged from the boiler apparatus;   
       wherein:
 the wet type flue-gas desulfurization apparatus is a wet type flue-gas desulfurization apparatus according to  claim 4 . 
 
     
     
         11 . A thermal power plant comprising:
 a boiler apparatus; and   a wet type flue-gas desulfurization apparatus which eliminates sulfur compounds from exhaust gas discharged from the boiler apparatus;   
       wherein:
 the wet type flue-gas desulfurization apparatus is a wet type flue-gas desulfurization apparatus according to  claim 5 .