Sulfur dioxide reactor calculations

The principal use of Eq. (173) is in conjunction with a similar heat dispersion equation. Unfortunately, a system of coupled nonlinear partial differential equations then has to be solved, which is very difficult even with the aid of computers. In the oxidation of sulfur dioxide. Hall and Smith (HI) found relatively good agreement between theory and experiment near the center of the reactor. Their calculations were based on the heat-dispersion equation, and they did not take detailed mass dispersion into account. Baron (B2) later solved the mass and heat dispersion equations simultaneously by a novel graphical method, and found better agreement between his calculations and the data of Hall and Smith. 

Leitenberger s work (1939) is concerned with the oxidation of sulfur dioxide in adiabatic beds and tubular reactors. Using the Boresskow-Slinko kinetic equation he calculated the optimal tem-6... 

The entropy production of a sulfur dioxide oxidation (exothermic) reactor with heat exchangers was minimised in two different cases.Case 1 was a four-bed reactor with intermediate heat exchangers of a given total area, see Figure 8. The entropy production rate was calculated from the entropy balance over the system. All inlet and outlet flow conditions were kept constant, except the pressure at the outlet. Tlie... 

Olson and Smith measured the rate of oxidation of sulfur dioxide with air in a differential fixed-bed reactor. The platinum catalyst was deposited on the outer surface of the cylindrical pellets. The composition and the rates of the bulk gas were known. The objective was to determine the significance of external diffusion resistance by calculating the magnitude of — C. If this difference is significant, then the values must be used in developing a rate equation for the chemical step. 

Example 13-5 Using the one-dimensional method, compute curves for temperature and conversion vs catalyst-bed depth for comparison with the experimental data shown in Figs. 13-10 and 13-14 for the oxidation of sulfur dioxide. The reactor consisted of a cylindrical tube, 2.06 in. ID. The superficial gas mass velocity was 350 lb/(hr)(ft ), and its inlet composition was 6.5 mole % SO2 and 93.5 mole % dry air. The catalyst was prepared from -in. cylindrical pellets of alumina and contained a surface coating of platinum (0.2 wt % of the pellet). The measured global rates in this case were not fitted to a kinetic equation, but are shown as a function of temperature and conversion in Table 13-4 and Fig. 13-13. Since a fixed inlet gas composition was used, independent variations of the partial pressures of oxygen, sulfur dioxide, and sulfur trioxide were not possible. Instead these pressures are all related to one variable, the extent of conversion. Hence the rate data shown in Table 13-4 as a function of conversion are sufficient for the calculations. The total pressure was essentially constant at 790 mm Hg. The heat of reaction was nearly constant over a considerable temperature range and was equal to — 22,700 cal/g mole of sulfur dioxide reacted. The gas mixture was predominantly air, so that its specific heat may be taken equal to that of air. The bulk density of the catalyst as packed in the reactor was 64 Ib/ft. ... 

From the data of Tables II and III, it may be calculated that equilibrium conversion of hydrogen sulfide and sulfur dioxide to sulfur vapor in the secondary reactor is 78.0%. Cooling this gas stream to 140 °C (413 K) will lead to a liquid sulfur recovery of 76.1% of the secondary reactor output. Overall recovery in the two stages, then, may be calculated to be 94.9%. 

Thermodynamic equilibrium compositions were calculated by Okay and Short (5) for the sulfur dioxide reduction reactions in the reactor feed gases with and without water. Equilibrium was calculated by the technique of minimizing the free energy which uses a modified steepest... 

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