Temperature profiles, reactors sulfur dioxide oxidation

Temperature profiles, reactors ammonia synthesis, 582, 584 cement kiln, 590 cracking of petroleum, 595 endo- and exothermic processes, 584 jacketed tubular reactor, 584 methanol synthesis, 580 phosgene synthesis, 594 reactor with internal heat exchange, 584 sulfur dioxide oxidation, 580... 

Figure 17.19. Reactors for the oxidation of sulfur dioxide (a) Feed-product heat exchange, (b) External heat exchanger and internal tube and thimble, (c) Multibed reactor, cooling with charge gas in a spiral jacket, (d) Tube and thimble for feed against product and for heat transfer medium, (e) BASF-Knietsch, with autothermal packed tubes and external exchanger, (f) Sper reactor with internal heat transfer surface, (g) Zieren-Chemiebau reactor assembly and the temperature profile (Winnacker- Weingartner, Chemische Technologie, Carl Hanser Verlag, Munich, 1950-1954).

Because the PPR is operated as an adiabatic reactor, the strongly exothermic oxidation reaction (iii) causes a temperature wave traveling through the bed, giving rise to a peak outlet temperature in the initial period of the acceptance cycle, as. shown in Fig. 26. In this figure, the temperature profile predicted by a mathematical model developed at the Shell laboratory in Amsterdam is compared with the profile measured in an industrial reactor to be described later. During the initial oxidation period, the copper is not yet active for reaction with sulfur oxides, so there is a slip of sulfur in the initial period, as can be seen in Fig. 27. It can be inferred that the sulfur dioxide concentration profile of the effluent of the industrial reactor is in close agreement with the profile predicted on the basis of a kinetic model developed at the Shell laboratory in Amsterdam. 

The form of the radial temperature profile in a nonadiabatic fixed-bed reactor has been observed experimentally to have a parabolic shape. Data for the oxidation of sulfur dioxide with a platinum catalyst on x -in. cylindrical pellets in a 2-in.-ID reactor are illustrated in Fig. 13-9. Results are shown for several catalyst-bed depths. The reactor wall was maintained at 197°C by a jacket of boiling glycol. This is an extreme case. The low wall temperature resulted in severe radial temperature gradients, more so than would exist in a commercial reactor, where the wall temperature would be higher. The longitudinal profiles are shown in Fig. 13-10 for the same experiment. These curves show the typical hot spots, or maxima, characteristic of exothermic reactions in a nonadiabatic reactor. The greatest increase above the reactants temperature entering the bed is at the center,... 

Use the two-dimensional method to compute the conversion for bed depths up to 0.30 ft for the oxidation of sulfur dioxide under conditions similar to those described in Examples 13-5 and 13-6. The same reactor conditions apply, except that the superficial mass velocity in this case is 147 lb/(hr)(ft"), and the temperature profile at the entrance to the reactor is as shown below ... 

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