In this paper, numerical tests of fluidization between the tubes are presented. In some selected flow systems, calculations were performed for two kinds of comminuted materials of the fluidized bed under different flow rates. Two systems (triangular and rectangular) of tubes were analysed. Calculations were performed with the Euler's method for multiphase flows. A local growth of the solid phase concentration causes non-uniform resistances of flow, and their estimation is one of the problems connected with service of tubular heat exchangers. Obtained test results proved that the applied calculation method allowed to reproduce a flow of the fluidized bed in the space between tubes.