Reactor design, high-pressure

If higher hydrogen pressures could be used, the rates of desulfurization could be substantially increased. However, this is a limited option. As discussed in the beginning of this report, some refineries were able to purchase new high-pressure reactors during a time of low equipment and construction costs. However, new construction will not benefit from this luxury. Many of the presently installed reactors were designed for moderate pressures, less than 5 MPa. It would therefore be desirable to devise new processes around these pressures. 

The total molar concentration is proportional to the pressure, [M] = p/(RT). Thus the rate of CO oxidation appears to increase with increasing pressure. In our design of the high-pressure reactor, we would choose a comparatively small reactor, since we would expect the postflame oxidation of CO be faster (i.e., less time-consuming) at higher pressure than at atmospheric pressure. 

In our design considerations we have extrapolated the global rate expression for CO oxidation outside the conditions for which it was derived, and this extrapolation leads to erronous results. Experimental results on oxidation of CO in a flow reactor at varying pressure are shown in Fig. 13.3. The results clearly show that in the medium temperature range around 1000 K, an increased pressure acts to lower, not increase, the rate of CO oxidation. To secure adequate oxidation of CO, we would probably need to increase the postflame residence time in a high-pressure reactor compared to an atmospheric pressure reactor. 

The circulation flow method is applicable for the studies of almost any heterogeneous catalytic reaction. At high pressures steel equipment is used instead of glass. The first circulation flow reactor for high pressures was designed by Sidorov (6) the gas mixture is circulated in this reactor by means of steel bellows that are actuated by a rod introduced into the reactor also through bellows, without any packing. 

The ammonium salt of Rh(III) Anderson type heteropolymolybdate [RhMo6024H6] has been prepared and characterized by powder X-ray diffraction, spectroscopic [FTIR-Raman, DRS (UV-visible)] and SEM-EDAX electron microscopy techniques. The water soluble salts were used in the design and preparation of Y-AI2O3 supported catalysts. The varied Mo Rh ratio of both olution and solid samples was measured by AAS technique. The supported oxidic system was characterized by DRS spectroscopy and SEM-EDAX microscopy. The HDS and HYD activity for different bimetallic catalysts was measured in a high-pressure reactor. In addition, some conventional catalysts and some C0M06 and combined supported systems [(RhMoe + AIM06)] have been tested for comparative purposes. The discussion about the performance of the new catalysts is made on the basis of the structural and physicochemical heteropolyanion properties as well as the preparation conditions. 

Much information is available on the deformation and fatigue behavior of simple thick-walled cylinders [10-17], but it must be remembered that most process reactors will not be a simple hollow cylinder. Components such as connectors, threads and sleeves, windows, and removable closures make a complete analytical solution for a high-pressure system design problem quite involved. Useful design criteria for thick-walled vessels can be derived, however, under the assumption that the material of which the vessel is made is isotropic and that the cylinder is long (more than five diameters) and initially free from stress. The radial and tangential stresses in the walls are then only functions of the radius coordinate (r) and the internal pressure. Given the outer-to-inner wall radius ratio as o/i = w, and the yield point (To) of the material, the yield pressure (py) is... 

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