Heatup paths equilibrium curves

Fig. 7.5. Heatup path for gas descending the Fig. 7.1 catalyst bed. It begins at the feed gas s input temperature and 0% SO2 oxidized. Its temperature rises as S02 oxidizes. Maximum attainable S02 oxidation is predicted by the heatup path-equilibrium curve intercept, 69% oxidized at 893 K in this case. This low % SO> oxidized confirms that efficient SO-> oxidation cannot be obtained in a single catalyst bed. Multiple catalyst beds with gas cooling between must be used.

Table 12.1 shows heatup path and equilibrium curve % S02 oxidized-temperature points near a heatup path-equilibrium curve intercept. They are for ... 

Fig. 12.3. Heatup paths, equilibrium curves and intercepts for 7, 10, and 13 volume% S02 feed gas. Volume% 02/volume% S02 ratio =1.1. Intercept temperature increases with increasing S02 strength. Intercept % S02 oxidized decreases with increasing S02 strength. The intercepts have been calculated as described in Appendix J.

Fig. 12.4. Effect of pressure on equilibrium curves and heatup path-equilibrium curve intercepts. Equilibrium curves and intercepts are affected by pressure. Heatup paths are not. Intercept temperature and % S02 oxidized both increase slightly with increasing pressure. The intercepts have been calculated as described in Appendix J.

Fig. 12.5. Effect of feed gas 02 strength on constant S02 strength heatup paths, equilibrium curves and intercepts. Intercept temperature and % S02 oxidized increase slightly with increasing 02-in-feed-gas. Heatup path is barely affected by 02 strength - 3 paths are superimposed on this graph. The effect is small because ...

Fig. 12.8. Heatup path, equilibrium curve and intercept for 660 K, 13 volume% S02 feed gas. With 13 volume% S02 and higher, catalyst degradation is likely even with 660 K feed gas. 660 K is about the lowest temperature at which V, alkali metal, S, 0, Si02 catalyst is fully active.

Fig. 13.2. 1st catalyst bed heatup path, equilibrium curve and intercept point, from Fig. 12.1. The 1st catalyst bed s exit gas is its intercept gas, Section 12.12. It is cooled and fed to a 2nd catalyst bed for more S02 oxidation.

Table 15.1. 2nd catalyst bed % S02 ox/d/zed/temperature points near heatup path-equilibrium curve intercept. They have been calculated as described in Appendices K and D. 

Effect ofSO on heatup path-equilibrium curve intercepts Appendix Q shows how ... 

Fig. 17.1. Effect of C02-in-feed-gas on 1st catalyst bed heatup path and heatup path-equilibrium curve intercept. C02 increases heatup path slope and slightly increases intercept (equilibrium) % SO2 oxidized. Section 17.4. Appendix Table R.l describes the 10 volume% C02 intercept calculation.

Heatup Path Equilibrium Curve Intercept Calculation... 

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.

Fig. 21.1 s catalyst bed input and output gas enthalpies can be calculated directly on our heatup path-equilibrium curve worksheets, Table 21.1. Table 21.1 s 3rd catalyst bed input gas enthalpy is, for example ... 

Table 21.1. Bottom half of Table O.l s 3rd catalyst bed heatup path-equilibrium curve intercept worksheet. Input and output gas enthalpies are shown in rows 43 and 44. Note that they are the same. This is because our heatup path calculations assume no convective, conductive or radiative heat loss during catalytic SO2+V2O2 —> SO3 oxidation, Section 11.9. 1st and 2nd catalyst bed enthalpies are calculated similarly - using Tables J.2 and M.2. 

Catalyst bed gas enthalpies are readily calculated on our heatup path-equilibrium curve intercept worksheets. 

Table J.l. Worksheet for calculating 1st catalyst bed heatup path-equilibrium curve intercept. Preparation instructions are given in Section J.3. Operating instructions are given in Section J.4. Notice that equilibrium curve % S02 oxidized (cell FI 1) heatup path % S02 oxidized (cell 139). So 894.2 K in cells A14 and J30 is not the intercept temperature. The intercept value is calculated in Table J.2. 

Table J.3 is a worksheet for 13 volume% S02, 14.3 volume% 02 and 72.7 volume% N2, 690 K feed gas and a 1.2 bar equilibrium pressure. The heatup path-equilibrium curve intercept for this new gas is determined by ...

Table J.2. Table J. 1 worksheet after Goal Seek has found the heatup path-equilibrium curve intercept 893.3 K, 69.2% S02 oxidized. 

Table 0.1 is a 3rd catalyst bed heatup path-equilibrium curve intercept worksheet. It is a copy of Table M.2 with ... 

Table Q.l is a 1st catalyst bed worksheet for calculating heatup path-equilibrium curve intercepts with S03-in-feed-gas. The worksheet is similar to those in Appendices M and O.

Table R.1 is a worksheet for calculating 1st catalyst bed heatup path-equilibrium curve intercepts with CO and SO in feed gas. It is similar to that in Appendix Q.

Worksheet for Calculating After-Intermediate-H2S04-Making Heatup Path Equilibrium Curve Intercepts... 

Table U.l. Excel worksheet for calculating after-H2S04-making heatup path/equilibrium curve intercept with S03 and CO, in innnt one... 

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