Numerical Investigations to Quantify the Effect of Horizontal Membranes on the Performance of a Fluidized Bed Reactor

Reactive simulations of gas-solid flows occurring in fluidized beds with horizontal membrane insertion were carried out using computational fluid dynamics based on the kinetic theory of granular flows. The effect of altering the membrane arrangement on the overall reactor performance (degree of conversion achieved) was investigated by means of fractional factorial designs. When membranes served only as hydrodynamic modifiers to the flow, it was found that significant improvements could be obtained by optimising the membrane arrangement. A slightly larger improvement could be attained by injecting some of the reacting gas through the membranes. When compared to the improvements that can be attained by simply scaling up the reactor height and especially the reactor width, however, these improvements were of less significance. The use of membranes solely for altering reactor hydrodynamics by serving as obstructions and gas injection points can therefore not be merited. Further optimisation studies into membrane arrangement are therefore only recommended for specific processes in which the membranes play a central role by extracting some of the process gasses.