A transport‐oriented approach to residence time distributions and two‐phase chemical reactors

Abstract

This paper focuses on two‐phase (e.g., fluid‐solid catalyst) chemical reactors where one phase participates in the feed and effluent, first order chemical reactions proceed in the other phase and linear, species‐dependent, interphase transport connects the phases. A class of reactors exists in which the Laplace transform of the dynamic reaction/interphase transport equations reduces to essentially that of an effective set of first order reactions amongst effluent phase species only, in an imaginary single phase reactor. This result bears on scale‐up: Since the imaginary reactor simply scales with the usual residence time distribution, so too do reactors of this class scale with its analog. This easily measurable analog turns out to be just the non‐adsorbing tracer experiment. Significantly, certain reactors outside of this class do not scale likewise, even with first order chemistry; an example illustrates. The class in question includes, but is not limited to, fixed bed and Berty (CSTR) reactors. The analysis allows design inferences for two‐phase reactors, including fluidized beds.

A new technique for the determination of contact time distribution (CTD) from tracers experiments in heterogeneous systems

“…In the case of two phases isothermal reactors, one is interested in extending the approach (Shinnar and Rumschitzki, 1989;Rumschitzki, 1992) by defining a suitable time distribution so that an equation similar to Eq. (1) can be applied.…”