Abstract: In order to investigate the gas/solid flow characteristics in CTD (Comas Tower Dryer), OpenFOAM, an open source hydrodynamics calculation software, was combined with high performance large scale parallel computing for solid particles to simulate the full three-dimensional gaseous flow field and particle residence time distribution in CTD numerically. Meanwhile, the variations of gas/solid flow fields before and after the installation of an arc deflection plate in CTD were comparatively analyzed. The results showed that solid particles unevenly distributed in the vertical duct in radial direction, there existed obvious dense phase area and dilute phase area. The arc deflection plate could improve the distribution of solid particles and allow tobacco distributed in the tower more evenly. The mean residence time of solid particles in CTD was reduced by 1.45 s after the installation of the arc deflection plate, and the variance of residence time distribution decreased significantly as well; which indicated that the residence time of tobacco particles was more uniform in the CTD with an arc deflection plate.