The development and design of reverse flow reactor systems.

摘要

The reverse flow reactor is a gas-solid, fixed bed, catalytic reactor that operates with periodic switches in the direction of the gas feed stream. These switches reduce the convective heat losses of the system and allow for significant autothermal behavior. This work strives to deeply analyze this behavior and to extend the basic principles to reactor systems beyond those initially considered for reverse flow operation.;A useful tool, the high switching frequency model, is developed. It is a limiting case of the full transient model, and is significantly easier to solve numerically. This model allows for rapid evaluation of reactor performance for a variety of processes. It also provides a reasonable means of studying long term dynamic reactor behavior of the reverse flow system.;The original concept was originally intended for exothermic systems, this work extends the reverse flow concept to endothermic systems. Reverse flow operation permits the hottest point of the reactor to be placed at the exit of the reactor, which favors the thermodynamic equilibrium. Results demonstrate that the reverse flow reactor is fundamentally superior to traditional unidirectional, steady state behavior. In addition to a core study, the dehydrogenation of ethylbenzene and the dehydrogenation of isobutane are studied.;One particularly important application of the reverse flow reactor is the catalytic combustion of volatile organic components in waste gas streams. A simple procedure for the near-optimal design of these reverse flow incinerators is presented. The design, using several charts, can be accomplished without the use of computer simulation. Previously, no design procedure, short of numerical simulations, existed.;The original concept considered only plug-flow reactors. A natural extension to a series of continuous stirred tank reactors is presented. By application of the high switching frequency model to a series of two continuous stirred tank reactors, the simplest model known to date that still retains reverse flow characteristics is developed. This model shows several behaviors of the plug-flow model, and also shows the existence of stable asymmetric cyclic steady states.;A further extension of the original concept, the ring reactor, is theoretically evaluated. The ring reactor consists of periodically shifting the position of the inlet feed point in a manner as to reduce convective heat losses. The ring reactor and the original reverse flow reactor are compared for several systems.