The velocity fields in three symmetric and two asymmetric louver-walled moving bed systems were studied experimentally. The horizontal and vertical velocity distributions at five levels of the louver section were plotted. The results indicate that the velocity profiles of filter granules are influenced by the louver geometry. When the louver angle is steep, the velocity profile of filter granules is close to plug how. When the louver section is shallow, the quasi-stagnant zones exist along the louver walls. The kinematic model for predicting the granule velocity distribution is used for analyzing the three symmetric louver configurations at different height levels. (C) 1998 Elsevier Science Ltd. All rights reserved.