Order-reduced simulation and operational regulation of a 10 MWth autothermal reactor for CH4-fueled chemical looping combustion

In this study, an order-reduced model, which is able to simulate simultaneously air reactor (AR) and fuel reactor (FR) as well as their heat/mass interaction via oxygen carrier (OC) circulation, is developed for a 10 MWth autothermal reactor for CH4-fueled chemical looping combustion (CLC). Initially, the gas-solid fluid dynamics, chemical reactions, and temperature/energy distributions within the two main reactors are discussed. The fluidization state of the entire setup meets expectations, achieving the combustion efficiency of 85.77 % with a generally reactive Fe-based OC, and confirming the feasibility of autothermal operation of the reactor. Additionally, a method utilizing the order-reduced simulation to determine whether the reactor can achieve autothermal operation is proposed. Based on this method, the effects of CH4 concentration in the FR fluidization gas, FR solid inventory, oxygen carrier to fuel ratio, and fuel power on the combustion efficiency and autothermal operation of the reactor are discussed. Subsequently, by setting the limits of combustion efficiency and heat absorption by the water wall, the operable range of each operating parameter can be delineated effectively. Moreover, CFD simulation is employed to compare with the order-reduced model results, and a good agreement between the order-reduced simulation and CFD results further confirms the accuracy of the order-reduced model in this work.