Modeling and Simulation of Chemical Looping Combustion Using a Copper-Based Oxygen Carrier in a Double-Loop Circulating Fluidized Bed Reactor System

In this work, a computational fluid dynamics simulator has been developed for a novel double-loop circulating fluidized bed reactor which is used for a chemical looping combustion process. The simulator is implemented in an in-house code including the kinetic theory of granular flow and reaction models. Methane is used as fuel, and copper oxide-based particles are used as oxygen carrier. The process is configured with an air reactor and a fuel reactor. The two reactors are modeled and solved by a sequential approach. The connection between the two reactors is realized through time-dependent inlet and outlet boundary conditions. The model is validated with the experimental data obtained in the current work. At a thermal input of 100 kW, a methane conversion of 98% was achieved. For the cases studied in this work, temperature is the most important factor for the reactor performance, followed by the gas velocity and methane concentration of fuel. The increase of the methane concentration could decrease the methane conversion, which is due to the decrease of specific inventory. As the gas velocity is increased, the residence time and the degree of gas–solid contact decreases, causing a decrease in reactor performance. Besides the effect of the single factor, the combination effect of the gas velocity and methane concentration is also important to the reactor performance.