Input and Output Gas Enthalpies

11 volume% O2, 79 volume% N2 gas from sulfur burning furnace and boiler 

30 Third catalyst bed input gas temperature = 710 Intercept temperature, cell A14 = 721.1  

33 Matrix results equivalent to suggested intercept temperature in oeii J30 (and A14) M0.0311 F30-9.797)  

38 kg mol SOsOuf 0.0980 Heat ip path % SO ox tf/zed ( ) equiv 3lent to third catalyst bed Intercept tt mpetature In cell J30=  

47 Equilibrium curve % SOj oxidized - heatup path % SOj oxidized = 0.0 =F11-I39  

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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. 

First and second catalyst bed input and output gas enthalpies are calculated from Tables J.2 and M.2 exactly as described earlier. They are summarized in Table 21.2. 

The enthalpy change, AH, can be calculated for a steady-state process, using H°f, which is the enthalpy of formation of the various output and input components. Under the assumption that the inputs and outputs are at ambient conditions, the enthalpy of the components corresponds to the standard enthalpy of formation of each component. The kinetic and potential energy terms are neglected from the energy balance. It is also assumed that water enters the process as a liquid and hydrocarbon products leave the process as a liquid. All other components are in the gas phase. 

Table 7.4 shows the summarized material and energy balance. Compared with Table 7.2, the large quantity of waste gas and the use of high-value pure materials, such as CH4 and O2, are noteworthy. The enthalpies of the input and output materials are... 

Use your Prob. 16.1 3rd catalyst bed output quantities and Eqn. (21.3) to calculate H2S04 making s input gas enthalpy. 

Table 21.2. Summary of Fig. 21.1 s temperatures, enthalpies and heat transfers. Note the continuing decrease in the gas s enthalpy as heat is transferred from gas to water and steam in Fig. 21.1 s boiler, superheater and economizer. All temperatures but the last are from Tables J.2, M.2 and 21.1. Note that a catalyst bed s input enthalpy is always the same as its output enthalpy. This is due to our assumption that there is no conductive, convective or radiative heat loss from the gas.

Figure 24.4 shows the effect of Fig. 24.1 s input gas SO3 concentration on its output acid temperature. Output acid temperature decreases slightly with increasing SO3-U1-input-gas concentration. This miniscule effect is caused by the slightly smaller amount of N2 (and enthalpy) entering the absorption tower per kg mol of SO3. 

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