Deposit velocities of gas-liquid-solid mixture flows in a horizontal pipe were experimentally investigated in this study. The following conclusions were obtained through this experiment.
(1) When the volumetric flow rate of air is small, both the deposit velocity and the limit deposit velocity were observed in gas-liquid-solid mixture flows. On the other hand, when the volumetric flow rate of air is large, only the deposit velocity was observed and the limit deposit velocity was not observed.
(2) The velocity at which the pressure loss becomes minimum for gas-liquid-solid mixture flows was larger than the deposit velocity when the volumetric flow rate of air was small. However, when the volumetric flow rate of air was large, it was less than the deposit velocity.
(3) The deposit velocity decreased with increasing the volumetric flow rate of air and showed minimum at a certain air rate. After that, the deposit velocity was almost constant regardless of the volumetric flow rate of air. On the other hand, the limit deposit velocity decreased rapidly with increasing the volumetric flow rate and showed zero at a certain air rate. After that, the limit deposit velocity was not observed.
