CFD simulations on hydrodynamics and performance of air reactor during chemical looping combustion

• The influences of multiple conditions on the air reactor performance were evaluated. • Fluidization rate mainly affects O 2 consumption and Fe 2 O 3 regeneration (p < 0.05). • The energy utilization efficiency can be greatly improved by lowering the bed height. • Higher solid circulation rate will increase the escape amount of unoxidized Fe 3 O 4 . The optimal design of the reactors is of great significance for the efficient operation and scaling-up of the chemical looping combustion system. Here, the hydrodynamics and performance of the air reactor on a 10 kW th series fluidized bed during chemical looping combustion were investigated via three-dimensional Eulerian-Eulerian multiphase simulations. The comprehensive influence of fluidization velocity, solid circulation rate, and bed height on axial pressure distribution, oxygen carrier conversion, and O 2 consumption was systematically evaluated through orthogonal experimental design. The simulation and variance analysis indicate that the fluidization velocity has a significant influence on O 2 consumption and Fe 2 O 3 regeneration (p < 0.05). The lower fluidization velocity can prolong the gas-solid contact time and improve the oxygen utilization efficiency, which is conducive to Fe 2 O 3 regeneration. The bed height exhibits a nonlinear relationship with the energy consumption of the system, and the energy consumption reaches its peak at 150 mm. The energy utilization efficiency can be greatly improved by lowering the bed height. The higher solid circulation rate will shorten the residence time of Fe 3 O 4 particles, resulting in an increase in the escape of unoxidized Fe 3 O 4 particles. When the solid circulation rate increases from 1 m/s to 3 m/s, the escape rate of Fe 3 O 4 rises to 65 %. Under the conditions of the fluidization rate of 1 m/s, the bed height of 100 mm, and the solid circulation rate of 1 m/s, the conversion rate of Fe 3 O 4 can reach 98 %, and the outlet O 2 concentration is the lowest. Hence, the optimal performance of the air reactor can be achieved by adopting lower fluidization velocity and solid circulation rate. This work provides important theoretical guidance for the design and operation optimization of air reactors during chemical looping combustion.