CFD-DEM simulation of gas-solid flow of wet particles in a fluidized bed with immersed tubes

摘要

In an intensified fluidized bed processing of wet particles, it is often to use heat transfer immersed tubes to maintain reasonable temperature distribution. The wet particles could adhere to the immersed tubes, which hinders the normal fluidization. We studied the gas-solid flow in a pseudo 2D fluidized bed of wet particles with the presence of immersed tubes, by using CFD-DEM simulation with the hysteretic contact model. The gas-solid flow characteristics around the immersed tubes and the effects of immersed tubes, adhesive force and fluidization velocity on the fluidization of wet particles are analyzed. With the increase of the adhesive force the agglomeration mainly occurs near the bed wall and the channeling mainly appears in the middle of the bed. The immersed tubes can cause the particles to accumulate on the upper surface of the tubes. Also, it can break the bubbles and agglomerates when the fluidization velocity is high. As the fluidization becomes poor, the particle agglomeration becomes more obvious and coordination number increases. The local poor fluidization zone is observed mainly in the gaps between the wall and the immersed tubes.