The centrifugal and double vortex (CDV) reactor is a novel downer reactor that harnesses centrifugal force and a double vortex, and it enables rapid pyrolysis of low-rank coal. However, further research is necessary to fully understand the heat transfer mechanisms to provide theoretical guidance for optimization. In this study, the flow and temperature distribu-tions of gas and solid in a CDV pyrolyzer was investigated, where heat-carrying particles serve as the heat source by the large eddy simulations and the MP-PIC (multiphase particle-in-cell) model. The results show that coal particles can be heated at a rate of 700 K/s , leading to rapid pyrolysis. Due to the centrifugal force, the solid hold-up near the reactor wall is much higher than that in the conventional donwer, resulting in an over 300 K/m of temperature rise gradient even in a small mass flow rate of heat-carrying particles. In addition, the cyclone length also has a signifi-cant effect on the heat transfer. The cyclone length within the base bleed reactor is much longer than that within the top bleed reactor, resulting in a much higher final temperature of coal parti-cles. Another advantage of the base bleed reactor is that the airflow temperature in the central re-gion is significantly lower than that near the wall. The primary pyrolysates are primarily genera-ted in the region with high temperature near the wall, then they are carried by the gas flowing in-to the central region with low temperature. Because the secondary reaction of the primary pyroly-sates is enhanced by the high temperature, the gas flowing into the central region helps to sup-press secondary reactions of the primary pyrolysates, resulting in higher tar yields and lower dust content.
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