H2SO4 making catalytic plants

Fig. 9.1. Single contact H2SO4 making flowsheet. SO3 rich gas from catalytic SO2 oxidation is reacted with strong sulfuric acid, Reaction (1.2). The reaction consumes H20(f) and makes H2S04(f), strengthening the acid. Double contact H2SO4 making is described in Fig. 9.6. A few plants lower the SO2 content of their tail gas by scrubbing the gas with basic solution (Hay et al., 2003).

Most of the mathematical chapters analyze catalytic S02+ /202—> SO3 oxidation in single and double contact acid plants. The remainder examine temperature control and H2SO4 making. 

Catalytic oxidation is now used by the smelting industry to convert SO2 into SO3. This is then dissolved in water to make solutions of H2SO4 (up to 80% by mass). The gases containing SO2 are passed through a series of condensers containing catalysts to speed up the reaction. In some cases the impure H2SO4 can be used in other operations in the same plant. 

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