A novel cyclic reactor system is proposed for heterogeneous, catalytic, gas-phase reactions. This system utilises the inherent characteristics of the thermal regenerator to impose favourable reaction temperature profiles along the catalyst bed without setting up radial temperature gradients. This control of the longitudinal profile enables higher conversions to be obtained than those from steady state reactors. The reactor system is investigated by computer simulation using the endothermic, reversible dehydrogenation of ethylbenzene to styrene in the presence of steam as an example. The higher conversions obtained from the proposed system produce utility cost savings in this process. Kinetics presented in the literature for this reaction are compared and assessed. None of these is entirely satisfactory and a more representative set is derived. Models for the reacting and regenerating bed are discussed and suitable models are presented. A comparative study of solution methods for these models is carried out in order to determine one which gives an accurate solution and also minimises computing requirements. The most suitable operating policy lor the system, with an endothermic reaction, is the use of constant heat inputs with constant flow during each period of operation, This allows the bed inlet temperature to vary with time, but it seems likely that the damping effect of the system will be large and the inlet temperatures may be assumed constant Counter-current, rather than co-current, operation of the system is preferred, A simple design procedure, which does not require the solution of the cyclic model, is described. This is found to give good predictions of the cyclic steady state performance of the system. Che effect of the various system parameters on the performance is investigated. The major parameters for a given bed size are the period time, reactor and regenerator steam flows and regenerator inlet temperature. It is shown that the system can give higher conversions than a steady state reactor but i.t may be desirable to operate at lower conversions to reduce the operating cost. Guidelines for optimising the system are discussed.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:557314 |
| Date | January 1976 |
| Creators | Cockcroft, C. S. |
| Contributors | Heggs, P. J. |
| Publisher | University of Leeds |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://etheses.whiterose.ac.uk/2626/ |
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