| 摘要 |
<p>PURPOSE:To recover pure-white by-product gypsum of enhanced value by adjusting a lime slurry which has absorbed SO2 in exhaust gas and left an oxidation tower to pH<=2.0; adjusting effluent in an effluent neutralization vessel to pH>=9.5; removing precipitates in the effluent; and returning the precipitates-free effluent to the absorption process. CONSTITUTION:SO2 gas in exhaust gas is allowed to be absorbed in a lime slurry in absorption towers 3,4 through cooling-washing tower 1 and pH adjusting tower 2. The slurry is then fed to oxidation tower 5 through raw fluid tank 14. A gypsum slurry formed in tower 5 is adjusted to pH<=2.0 at the outlet of tower 5, fed to thickener 6, and precipitation separated. The supernatant is adjusted to pH>=9.5 in effluent neutralization vessel 7. On the other hand, the thick gypsum slurry is fed to gypsum separator 9 through separation vessel 8 to recover gypsum. The neutralized effluent in vessel 7 is supplied to thickener 10, where a flocculant is added to precipitation separate impurities. Part of the supernatant is recovered and reused in the system, and the remainder is adjusted to pH 7-8 in reneutralization vessel 15 and discharged from the system.</p> |
