Abstract The performance of the mixer-type disperser has been studied experimentally with particular attention to the effect of the height of the vessel and the length of the inlet tube. The measurement of the particle residence time revealed that the vertical velocity component of the flow in the double-walled section constructed by the vessel and the inlet tube has a constant value. The short cut of particles from the inlet tube to the outlet tube occurred at the space between the inlet tube and the impeller. The experimental results of the newly designed dispersers revealed that the double-walled section and the space below the inlet tube caused deterioration of the dispersion performance. The double-walled section caused the agglomeration of the dispersed particles. On the other hand, the space below the inlet tube caused the particle short cut from inlet to outlet resulting in the discharge of agglomerated particles without experiencing the dispersing action.