Numerical investigation of syngas oxy-combustion inside a LSCF-6428 oxygen transport membrane reactor

Abstract

The present work provides an investigation of the oxy-fuel combustion of syngas (mixture of CO and H2) inside an OTR (oxygen transport reactor) of tubular shape and surrounded by air in an annulus. The syngas is generated from solar thermal reforming of methane. CFD (Computational fluid dynamics) calculations were performed using FLUENT 14.0 commercial code, where a series of UDFs (user defined functions) that enable the transfer of oxygen across the membrane were written in VC++, then compiled and hooked to FLUENT software. The models of oxygen permeation and reaction kinetics are validated against the available experimental data under similar oxy-combustion conditions. Simulations were performed considering non-reactive and reactive flow conditions. The results showed that the reactive flow results in increase in oxygen permeation flux of about four times the case of non-reactive flow. Oxy-combustion characteristics of synthetic gas in a medium of recirculated CO2 are investigated. Considering reactive flow conditions, the effects of inlet temperature, CO2 circulation, fuel composition and sweep gas flux on oxygen permeation and combustion temperature are studied. It was found that increase in inlet temperature, inlet fuel concentration, inlet hydrogen concentration and sweep flow rate result in high combustion temperature and improved oxygen permeation flux.