PURPOSE: To perform the recovery of gypsum in one tower by bringing a suspension into contact with an O2-contg. gas in the inside of a circulation tank incorporated in an absorption tower, regulating the amount of all Ag2SO3 contained in the suspension and thereafter adding CaCO3 or Ca(OH)2 to keep pH in a prescribed range and performing the gas-liquid contact with an exhaust gas.
CONSTITUTION: An exhaust gas 1 contg. SOx is introduced into an absorption tower 3 and the solid fine grains and SOx are collected in a suspension. One part of CaSO3 is brought into contact with O2 contained in the exhaust gas to make one part thereof gypsum and the amount of all Ag2SO3 is regulated so that it is made to ≤1.3 times of the saturated dissolved amount of CaSO3 in 3.8 pH. The greater parts of CaSO3 are oxidized with air in an oxidation reaction apparatus 23 to produce gypsum. On the other hand, the suspension of CaCO3, Ca(OH)2 and H2O is sent to the oxidation apparatus 23 through the feed lines 28, 29 and pH is kept to 3.8W5.0 and pH, the feed amount of limestone and SOx are detected to control the feed amount of air. After gypsum is retained in an oxidation reaction apparatus 8 for a specified time, it is recovered through a drawing-out line 102.
ARASHI NORIO
KAJI RYUICHI
OTSUKA KEIZO
| JPS60179120A | 1985-09-13 |