CFD Simulation of Chemical Looping Combustion of Coal

Abstract

CLC is a promising cost effective, energy efficient technology that helps to separate CO₂ from the flue gas, with the aid of an oxygen carrier. It helps to reduce the atmospheric CO₂ concentrations, which is essential as per present environmental scenario. Chemical looping combustion process involves two reactors, namely air and fuel reactor, where subsequent heterogeneous oxidation and reduction reactions take place. In air reactor, metal gets oxidized to metal oxide reacting with inlet air, whereas in the fuel reactor, these metal oxides get reduced after reacting with fuel gas resulting in the formation of an effluent stream containing CO₂ and H₂O, from which CO₂ can easily be separated by condensing H₂O. In this study, a 2-dimensional computational fluid dynamics (CFD) model for a fuel reactor utilizing coal as the solid fuel and Fe₂O₃ as oxygen carrier is developed and is simulated using ANSYS—Fluent. The model accounts for fluid-particle and particle-particle interactions and fuel and oxygen carrier reaction kinetics as well as devolatilization and the rate limiting char gasification of coal. The performance of the reactor and coal conversion rates are studied and presented in this work.