Multiobjective optimization of a flat-panel airlift reactor designed by computational fluid dynamics

Abstract

The optimization and scale-up process of industrial reactors maintaining optimum and homogeneous reaction conditions is a great challenge to engineers. For each final product, process and facility is necessary elaborate suitable strategies in order to allow a comprehensive and detailed process characterization to identify the most relevant process parameters influencing product yield and quality. Despite several research efforts to develop ideal reactors, these studies usually focus on trial-and-error optimization approach. This work was aimed to propose a numerical multiobjective optimization method and its application to the design of a flat-panel airlift (FPA) reactor. A preliminary study of the hydrodynamics of the reactor was conducted in a 61L FPA reactor. Experiments and computational fluid dynamics (CFD) simulations were compared to demonstrate the viability of usage of the simplifications applied to CFD model in order to reduce the computational effort. The inner structure key parameters of a FPA reactor, including the ratio of the cross-section area of the downcomer to the cross-section area of the riser, are optimized vis-à-vis the flow aspects portrayed by the performance parameters, such as shear stress and residence time variations. An in-house computer package was used for the automatic CFD simulations and the optimization process. A Pareto-optimal front with possible solutions to the problem and a detailed investigation of the mixing performance of the possible optimal geometries were presented in the study herein. The results also showed the high influence of the geometric parameters on the hydrodynamics of the FPA reactor, that have to be taken in account in the scaling-up process.