METHOD FOR REMOVING SULFUR DIOXIDE IN FLUE GAS, PARTICULARLY POWER PLANT WASTE GAS AND WASTE GAS FROM RUBBISH INCINERATION FURNACE

摘要

PROBLEM TO BE SOLVED: To effectively attain the separation of SO2 by using a mixture composed of an aqueous ammonia, an ammonium sulfite-containing cleaning liquid and an ammonium sulfate solution as an absorbing liquid and in such a case, specifying the mixing ratio of ammonium sulfite to ammonium sulfate. SOLUTION: In a cleaning zone 8, the flue gas loaded with SO2 is brought into contact with the absorbing liquid composed of the aqueous ammonia, the ammonium sulfate aq. solution and the newly generated ammonium sulfite liquid. In such a case, the mixing ratio of ammonium sulfite and ammonium sulfate is controlled to 15:1 to 3:1. And the divided stream of the absorbing liquid withdrawn in the collecting bottom part 9 below the cleaning zone 8 is supplied to an oxidation device 5 through a conduit pipe 10. Then, the oxidation to ammonium sulfite and ammonium sulfate is performed. Another part of the absorbing liquid is mixed with the aqueous ammonia from the conduit pipe 12 and the ammonium sulfate solution from the oxidation device 5 and supplied to the upper side of the cleaning zone 8.