Experimentation, modeling and optimisation studies of an integrated-packed bed reactor (PBR) for the decomposition of sulphuric acid

Abstract

Decomposition of sulphur trioxide (SO3) is highly endothermic, catalytic and overall rate-controlling step, in three-step decomposition of sulphuric acid. SO3 decomposition in Packed Bed Reactor (PBR) involves transport resistances in two (multi) scales; macro-voids and micro-pores together with surface reaction. Objective of the present study is to develop a double porosity (multi-scale) model, DPM for the catalytic decomposition of SO3 in a heat recuperated (integrated)-PBR and also to maximize SO3 conversion. DPM and simulation studies are carried out using COMSOL® and the model is validated with experimental studies. Experiments are performed at different flow rates, wall temperature, feed concentration and with two catalyst loadings, where chromium doped iron oxide ‘foam’ type (porous particle) catalyst is used. Simulation study shows, increase in conversion with decrease in particle size, annular gap and with increase in porosity, thermal conductivity of catalyst. Catalyst size is found to be an insignificant parameter, for porosity >0.2 and thermal conductivity is found to be a significant parameter. A conversion close to isothermal conversion has been obtained with the tuned parameters.