The existence of stagnant zones in granular moving bed systems with louvered-walls cause major technical problems, especially in the filtration and adsorption processes. In this paper, we proposed the method of placement of flow-corrective elements in the moving bed to diminish the stagnant zones near the louvers. We experimentally studied the flow patterns and the velocity fields of filter granules in symmetric louver-walled moving bed systems with placement of a series of flow-corrective elements. The white PE beads were used as filter granules and colored PE beads served as tracer particles. Filter granules were discharged from and circulated to the bed. The image processing system was used to record the granular flow. A mixing experiment was performed to show that the moving bed can be processed in two separated parts with different filter granules. The observations of flow patterns showed that the placement of the flow-corrective elements diminishes the stagnant zone efficiently. The velocity fields in the moving bed were also measured. (C) 2003 Elsevier B.V. All rights reserved.