Effect of first catalyst exit gas recycle on overall acid plant performance

6 Effect of first catalyst exit gas recycle on overall acid plant performance 

It also specifies that all of the third catalyst bed s exiting SO3 is removed as 112804(0 between the third and fourth beds. 

As Fig. 27.6 shows, the first catalyst bed gas % SO2 oxidized advantage with gas recycle persists throughout the catalytic converter. However, the advantage decreases 

Of course, improved SO2 recycle efficiency is not the goal of the gas recycle. The goal is to prevent first bed catalyst degradation while at the same time treating feed gases with SO2 concentrations greater than 13 volume% (Section 27.9). 

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