Comparison with conventional acidmaking

The WSA process is best compared to a conventional single absorption acidmaking plant with three catalyst beds (Fig. 9.1). 

The principal advantage of WSA is that it directly produces strong ( 98 mass% H2SO4) acid from H20(g)-bearing, low SO2 strength feed gas. It does so by condensing the acid rather than by absorbing the SO3 in sulfuric acid. 

It thereby avoids gas dehydration and pumping of large quantities of sulfuric acid. It also usefully recovers considerable heat from H2S04(g) formation and H2S04( ) condensation, and cooling of the process gas to 100 °C (Fig. 25.1). 

The SO2 oxidation efficiency is higher for WSA due to H2S04(g) production in the catalyst beds. 

In 2013, 10% of the world s sulfuric acid plants use WSA technology. They produce about 3% of the world s sulfuric acid. 

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