Three Dimensional Modeling of a Coal-Fired Chemical Looping Combustion Process in the Circulating Fluidized Bed Fuel Reactor

摘要

In this work, a comprehensive three-dimensional numerical model was developed to simulate the coal-fired chemical looping combustion (CLC) process using ilmenite as oxygen carrier in a pressurized circulating fluidized bed (CFB) fuel reactor. Both gas—solid flow and chemical reactions were considered. The chemical reactions contain steam gasification of coal and subsequent reduction reactions of intermediate gasification products with the oxygen carrier. This model predicted the main features of the complex gas—solid flow behaviors from the velocity and voidage profiles. The concentrations of gas—solid components, the conversions of char and oxygen carrier, and the distributions of reaction rates were also obtained. Meanwhile, further simulations were performed to evaluate the effects of operating variables on the fuel conversion in the fuel reactor. The conversion of carbon in char is directly related to the extent of gasification, which is promoted by increasing the temperature or the fraction of steam in gasification agent. This work indicates a promising way to research the CLC process of solid fuels in a CFB fuel reactor.