DEM simulation of the mixing process in downer reactor for the scaling-up of coal topping process

摘要

In this work, the discrete element method (DEM) is used to optimize the interior mixing structure in a CFB downer reactor for the scaling up of the so-called "Coal Topping" Process, proposed by Institute of Process Engineering of Chinese Academy of Sciences. The mixing structure is made up of a series of sloping chute, and is set up in the upper part of the downer for a good mixing of coal injected from the top of the downer with the recirculating ashes from the riser. Currently, numerical simulation is focused on the optimization of the angle and the number of the chutes, which should be the most crucial factors determining the mixing quality. The simulation results show that 3 chutes with an angle about 30~35 to the wall is expected to obtain the best mixing quality.