Minor effect—SO2 strength in feed gas

SO2 strength in industrial catalytic oxidation feed gas varies from 8 volume% to 12 volume%, Table 7.2. The strength depends mainly on the preceding SO2 production process. 

Industrial plants could send higher SO2 strength gas to their acid plant - by enriching their combustion air with oxygen (Miller and Parekh, 2004). This strong SO2 would  

It would, however, tend to give catalyst overheating and degradation in the T catalyst bed. Section 12.11. For this reason, 12 volume% SO2 is about the maximum strength used in industrial acid plants. 

Specified voiume% SO2. 1.1 voiume% 02/voiume% SO2 Ratio in first catalyst bed feed gas Remainder N2 1.2 bar pressure, all beds - 690 K input gas, all beds 

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