Analysis and optimization of cross-flow reactors with staged feed policies—isothermal operation with parallel-series, irreversible reaction systems

Abstract

A general model was proposed for the simulation of cross-flow reactors with six types of feed policies. All of the six types of cross-flow reactors were analyzed for series-parallel reaction systems and their feed distributions were optimized by maximizing the desired product yield at the reactor outlet. The comparisons of reactor performance between reactors with different types of feed policies were made in terms of kinetic and operation parameters. In order for a reactor with staged feed to achieve higher yield and selectivity of the desired product than a conventional co-feed reactor operated at the same conditions, the reaction order in the distributed reactant in the desired reaction has to be lower than that in the undesired reactions. The improvement of the desired product yield by using staged feed reactors increases with the increase in residence time and increase in reaction order with respect to the distributed reactant of the undesired reactions. In addition, the dimensionless groups σ i (rate constant of reaction i multiplied by the residence time) should be within certain ranges for the distributed feed reactor to achieve higher desired product yield than the conventional co-feed reactor. Optimally fed reactors give only slightly higher maximum yields than uniformly fed reactors with the same number of feed points. The modeling study provides guidance in terms of kinetic and operating parameters for the evaluation of the effectiveness of using multiple-staged feed reactors and membrane reactors to improve the reactor performance.