Catalytic single contact acid plant

Most of the mathematical chapters analyze catalytic SO2+/2O2-> S03 oxidation in single and double contact acid plants. The remainder examine temperature control and H2S04 making. 

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).

The single absorption contact process for sulfuric acid is characterized by four main process steps gas drying, catalytic conversion of S02 to S03, absorption of S03, and acid cooling. The maximum S02 conversion for a single absorption plant is about 97.5-98 percent. By adding a second S03 absorber with one or two catalyst beds between absorbers, the S02 conversion can be increased to 99.5-99.8 percent or even as high as 99.9 percent with a cesium-promoted catalyst, resulting in lower S02 emis-... 

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