Verfahren und Geraet fuer die Herstellung von Schwefelsaeure

摘要

A process for obtaining sulphuric acid comprises bringing a gaseous current containing SO3 at a temperature corresponding to the dew point of the gases into contact with a supply of an aqueous sulphuric acid solution containing 75 to 90% by weight of H2SO4, the volume and concentration of the solution being kept substantially constant by continuously extracting a quantity of this solution (corresponding to the acid formed by the absorption of the SO3) which is concentrated by being caused to flow in countercurrent and intimate contact with the gaseous current at a temperature of about 30 DEG C. above that corresponding to the dew point of the gases, before the current has come into contact with the sulphuric acid solution. The gaseous stream containing SO3 at, e.g. 250 DEG C. passes through heat exchanger 12 (Fig. 2) where it is cooled to a temperature of 30 DEG C. above that corresponding to the dew point of the gases; the gaseous stream then passes through the concentrator 14 in intimate contact with H2SO4 from the absorber 20 via 19; concentrated H2SO4, e.g. 94% by weight is withdrawn at 16; the gases now at the temperature corresponding to their dew point leave 14 at 18 and pass to absorber 20 where they are contacted with H2SO4 of, e.g. 80% by weight which is circulated via 23 and is cooled at heat exchanger 24; excess acid formed due to the absorption of SO3 passes to concentrator 14 via 19. The gaseous current may contain 0.8-9% by volume SO3 and originate from the burning of a residual gas containing vesicular S and/or S compounds with natural gas, the oxidation of SO2 to SO3 then being effected catalytically.