(187b) Fundamental Study On Washing Characteristics of a Novel Multiphase Flow System

When small quantities of water (typically 10% by vol) are added to a gas-fluidized bed of relatively large non-wettable particles, such as 6 mm Polystyrene spheres, the added water can cause a dramatic improvement in the extent of fluidization. The resulting unique fluidized bed has advantages for soft-abrasion, due to the movement of light rounded particles, and also for reducing the water needed for washing. These characteristics are desirable for industrial washing of some farm products or fragile industrial devices, which require soft abrasive washing. In this paper, the mechanism of washing in this unique fluidized bed is discussed as a combination of calm abrasive washing by liquid movement and hard attritable washing by particle collision. It can be explained in the light of results from four kinds of experiments: particle collision force on the cylinder surface, attrition of plaster cylinder, whitening of a test cylinder covered with soiled cloth, and observations of liquid distribution on the cylinder surface.The experimental results support our proposed washing mechanism.