Patent ID: 6153168
Filing Date: 2000-11-28
Classification: C01B

Abstract:
A process for producing sulfuric acid from a gas containing sulfur dioxide and steam which comprises the steps of:(a) catalytically oxidizing the sulfur dioxide in said gas to sulfur trioxide to obtain a gas mixture which contains SO.sub.3 and H.sub.2 O in a molar ratio of at least 1:1 and is at a temperature of 400 to 600.degree. C.;(b) passing the gas mixture containing SO.sub.3 and H.sub.2 O through a condenser in which the gas mixture is indirectly cooled by means of a cooling fluid so that at least 80% of the theoretically possible sulfuric acid is formed and condensed;(c) withdrawing from said condenser condensed sulfuric acid at a concentration of at least 97 weight % at a temperature of 180 to 240.degree. C.;(d) withdrawing the cooling fluid from said condenser;(e) withdrawing an SO.sub.3 -containing residual gas mixture from the condenser;(f) directly charging the SO.sub.3 -containing residual gas mixture and concentrated sulfuric acid into a contact vessel at a temperature of 60 to 120.degree. C. to form additional concentrated sulfuric acid from the SO.sub.3 -containing residual gas; and(g) withdrawing the concentrated sulfuric acid obtained during step (f).