Comparison between fluidised bed and packed bed reactors: non-catalytic gas–solid reactions

Abstract

Mathematical modelling of both fluidised and packed bed reactors has been carried out. In the fluidised bed reactor, a two-phase bubbling bed model has been used in order to estimate the interaction between gas bubbles and the dense phase in the bed. Modelling in the packed bed reactor was carried out based on that used by Ranade and Evans. The reduction behaviour of solid reactants has been expressed by the grain model, and computerised programs were developed in MATLAB software for solving the governing equations at conditions of different temperatures and pressures. The behaviour of both types of reactors for variations in temperatures, size of the pellets and inlet gas compositions has been studied, and a comparison between the reactors has been carried out. Excellent mixing of reactants in the fluidised bed helps to minimise temperature variations and renders this system attractive for carrying out gas–solid reactions. The fluidised bed reactors show better conversion of reactants in comparison with packed beds when solid reactants are used in the form of small pellets.