Computational Fluid Dynamics-Discrete Element Model Simulation of Flow Characteristics and Solids' Residence Time Distribution in a Moving Bed Air Reactor for Chemical Looping Combustion

In our previous experimental study, a novel multistage moving bed air reactor was proposed for chemical looping combustion; some operating mechanisms including the gas flow carrying capacity and gas leakage performance were investigated. In this paper, a quasi-2D computational fluid dynamics-discrete element model cold flow model is developed for the experimental air reactor. Effects of the operating parameters, geometric parameters, and internals on solids' flow characteristics and residence time distributions are studied by using the tracer particles. Results show that with increase in the loop seal gas velocity, the solids' mass flux increases and the average solids' residence time decreases. The reactor angle has more influence in solids' movements in the near-wall region, while the wedge angle has more effect on the solids' movements in the lower part of the reactor. With decrease of the reactor angle, increase of the wedge angle, or increase of the down-comer diameter, the solids' flow gets closer to ideal plug flow in the reactor. The internals can accelerate the particles in the near-wall region; internals in triangular arrays are better than those in square arrays to slow down the central particles.