Abstract: The present invention is concerned with a process and a plant for the production of sulphuric acid wherein a sulphur dioxide-containing feed gas is converted, at least in part, with oxygen in at least two contact stages of main contacts arranged in series, to generate sulphur trioxide, and wherein generated sulphur trioxide-containing gas is conducted to an absorber and converted therein to sulphuric acid. In order to be able to economically process feed gases of a sulphur dioxide content of between 13 and 66% by volume to sulphuric acid, using conventional catalysts, it is suggested to withdraw from a contact stage connected upstream of the last main contact stage, a partial stream of the sulphur dioxide- and sulphur trioxide-containing gas, to mix the said partial stream with the feed gas to generate a contact gas of a sulphur dioxide content of more than 13% by volume, and to return the same to the first contact stage.

Abstract: The present invention is concerned with a process and a plant for the production of sulphuric acid wherein a sulphur dioxide-containing feed gas is converted, at least in part, with oxygen in at least two contact stages of main contacts arranged in series, to generate sulphur trioxide, and wherein generated sulphur trioxide-containing gas is conducted to an absorber and converted therein to sulphuric acid. In order to be able to economically process feed gases of a sulphur dioxide content of between 13 and 66% by volume to sulphuric acid, using conventional catalysts, it is suggested to withdraw from a contact stage connected upstream of the last main contact stage, a partial stream of the sulphur dioxide- and sulphur trioxide-containing gas, to mix the said partial stream with the feed gas to generate a contact gas of a sulphur dioxide content of more than 13% by volume, and to return the same to the first contact stage.

Abstract: The invention relates to a novel method for producing high-purity sulfuric acid for use in the semiconductor industry. The method comprises the addition of a hydrogen peroxide solution to an engineered oelum in order to reduce the SO2 concentration, evaporation of the SO3 and separation of acid traces. The high-purity SO3 is then enriched with inert gas and the SO3 is absorbed into sulfuric acid.

Abstract: A process is provided for manufacturing sulfuric acid from a gas containing sulfur dioxide and steam. The sulfur dioxide and steam containing gas is subjected to a catalytic oxidation to convert the sulfur dioxide into sulfur trioxide so as to produce a gas having a sulfur trioxide to steam mole ratio of at least 1:1 at a temperature of 400 to 600.degree. C. This sulfur trioxide and steam containing gas is injected into an indirect heat exchanger where it is indirectly cooled with a cooling fluid so that at least 80 percent of the theoretically possible sulfuric acid is formed and condensed in this heat exchanger. The cooling fluid exiting the heat exchanger is fed into a turbine for the generation of electricity. The gas mixture exiting the heat exchanger is contacted with sulfuric acid in a separate contact vessel to form additional, concentrated sulfuric acid. The sulfuric acid formed in the heat exchanger is discharged.