VERFAHREN ZUR REINIGUNG UND WIEDERAUFHEIZUNG VON ABGASEN.

摘要

Removal of dust and SO2 from hot waste gases (I) with low H halide conent and reheating of purified (I) involves : (a) cooling (I) to under 135 deg. C in a H2SO4 scrubber; (b) sepg. H2SO4 contg. solids and dissolved metal sulphates from (I); (c) cooling (I) to 50-70 deg. C by scrubbing with 15-50% H2SO4; (d) desulphurisation, with H2SO4 formation; (e) heating to 50-90 deg. C again by scrubbing with 50-65% H2SO4, with simultaneous concn. o the acid from stage (c); and (f) cooling the H2SO4 contg. solids from (a) by heat exchange with the pure H2SO4 from (e). 70-80% H2SO4 contg. solids and metal sulphates is used in (a) and the solids deposited in (a) are sepd. from a side stream of 0.2-10, pref. 1-5% of the circulating acid. A droplet separator is used in stage (b), pref. a lamellar droplet separator, esp. of PVDF. H2SO4 is formed in stage (d) by adding H2O2 and/or peroxysulphuric acid to scrubbing in (c); or by catalytic reaction on moist activated charcoal, the H2SO4 formed being removed with water at 2-20% soln. and passed to stage (c). The pure H2SO4 formed in (d) is discharged from the system as 50-65% pure H2SO4.