Analysis and design of gas flow reactors with applications to hydrocarbon pyrolysis

Abstract

AbstractThe analysis and design of gas flow reactors are customarily based on a plug flow model. Because of transverse concentration and temperature gradients, however, kinetic constants and reactor lengths based on the plug flow model may be in gross error. This paper presents an approximate method of analysis which accounts for the effects of these gradients. We examine a gas in laminar flow which supports a first‐order irreversible reaction. Compressibility effects are considered, and the diffusion fluxes are calculated with the full ternary diffusion equations. Instead of solving exactly the full equations of change which describe this system, the well‐known Pohlhausen technique is adapted and approximate solutions which satisfy the integral forms of these equations are sought. This reduces the problem to the solution of a set of ordinary differential equations, which are integrated numerically. The main result is a set of graphs giving correction factors to be applied to plug flow kinetic constants and reactor lengths. Although primary interest is in hydrocarbon pyrolysis systems, the integral method graphs are applicable to other reaction systems.