Characteristics of Particle Velocity in an Unforced Air-Loop Mixer
1. State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing 102249, China;
2. Institute of Process Engineering, Chinese Academy of Science, Beijing 100080, China
Abstract In order to investigate the particle mixing efficiency of the unforced air loop mixer without draft tube and to enhance the mixing effect of the particles in the radial direction, a computational fluid dynamics (CFD) method was used to simulate the particle mixing modes and the related flow fields based on the energy minimization multi-scale (EMMS) inhomogeneous drag model. The simulation results showed that particles flowed in and out between the central zone and the side wall due to the disappearance of the draft tube, which strengthened the particle mixing. At the bottom of the mixer (h=0.04 m), particles flowed from the side wall to the center, while at the other heights, the particles moved outward along the radial direction. Due to the biased flow of feed to the central feed tube, the cross section of particles in the upper descending zone near h=0.16 m produced a significant circumferential movement. In the upper descending pipe area, the range of the side area decreased with increase of the apparent gas velocity and the axial heights. The simulation results provided the basis for further optimization of the structure of the air-loop mixer.
