Three-dimensional simulation of a gas-fueled chemical looping combustion system with dual circulating fluidized bed reactors

Chemical looping combustion (CLC) is a concept with inherent separation of CO2 and is the key strategy for CO2 capture at current stage. In this work, three-dimensional simulations of chemical looping combustion system using gaseous fuel are carried out for obtaining the flow behavior and reaction characteristics. The model is developed in the frame of Eulerian approach. The configuration with dual circulating fluidized bed reactors is built according to the experimental structure with designed power 120 kW. The oxygen carrier, a nickel based oxide, circulates between the reactors to transport the oxygen and heat. The time-averaged and local flow behaviour and reaction characteristic are analysed. The pressure, solid mass distribution and gaseous products are predicted numerically and compared with experimental measurement for the validation. The influences of operating temperature, solid inventory and fuel power on the performance of system are discussed. Results turn out that the numerical models developed in this work can be used for the design or scale-up of CLC system. The entrained solid circulating rate fluctuates around a constant value. The highest conversion rate of CH4 is 87.4% for reference case and it decreases with increasing the fuel power. With large amount of mass inventory is beneficial for getting high conversion rate of methane. The conversion rate reaching 0.978 when increasing the operating temperature to 1380 K. The largest reduction level of oxygen carrier is 0.29 for current work which is detected at the bottom of fuel reactor.