Catalyst beds after intermediate

Fig. 20.3. S02 oxidation efficiency of acid plants with 1 catalyst bed after intermediate H2S04 making. Oxidation efficiency increases with increasing number of before-intermediate-H2S04-making beds. However, the difference between 3 - 1 and 4 - 1 plants is very small.

Catalyst beds before intermediate H2SO4 making + beds after intermediate H2SO4 making. 

Their equivalent before-intermediate-H2S04-making details are given in Table 7.2. Catalyst beds before-intermediate H2SO4 making + beds after-intermediate H2SO4 making. 

The latter causes S02+ /202 — S03 oxidation to go almost to completion in the after intermediate H2S04 making catalyst bed, Chapter 19. 

Table 19.1. Heatup path matrix for after-intermediate-inSCri-making catalyst bed. The 1st three rows represent the equations ... 

Fig. 19.4. Equilibrium curve and partial heatup path for after-intermediate-fESO -makint catalyst bed. The heatup path has been calculated with matrix Table 19.1 as in Appendix I. The steepness of the heatup path is due to the small amount of S02 fuel in the input gas. The equilibrium curve and heatup path are only valid for the specified inputs. The S02 and 02 inputs are equivalent to 0.234 volume% S02 and 7.15 volume% 02.

Fig. 19.5. Equilibrium curve, heatup path and heatup path-equilibrium curve intercept for after-intermediate-FESOj-making catalyst bed. Attainment of equilibrium in the catalyst bed gives 98.9% oxidation of the bed s input S02. The lines apply only to the graph s specified inputs and bed pressure. This graph is a blowup of Fig. 19.6. Its intercept is confirmed by a Goal Seek calculation in Appendix T. The S02 and 02 inputs are equivalent to 0.234 volume% S02 and 7.15 volume% 02.

So far, this chapter has examined after-intermediate-HiSO -tnaking SO oxidation efficiency. However, Section 19.6 also provides the information needed to calculate total % S02 oxidized after S02 oxidation in all of Fig. 19.2 s catalyst beds. The values are ... 

Cs catalyst is costly so many acid plants use it in only one catalyst bed. From the S02 oxidation efficiency point of view, it is best used after intermediate H2S04 making. 

SO2 oxidized after all 4 beds (with intermediate H2S04 making after the 3rd catalyst bed). 

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