Dissolved Air Flotation(DAF) 접촉조의 수리동력학적 조건이 입자의 제거에 미치는 영향

Abstract

Hydrodynamic conditions for optimum solids capture within the contact zone, which are governed by the geometry and flow, are not yet well understood. In this research, dimensionless parameters which represent hydrodynamic conditions in the contact zone were derived, using the Buckingham π theorem. Those parameters are Reynolds No. (Re), Froude No. (Fr), Weber No. (We), Local Weber No., and Bubble Capacity No. (Bc). The particle removal rate was investigated by changing each value of the dimensionless parameters. The experimental results indicate that particle removal rate, when gravity dominates and the flow is semi-turbulent (Fr < 0.3, Re < 8000), is higher than when inertia dominates and flow is turbulent. For the We, higher removal rates were obtained in the range of the We < 40. Relative to the Local We, smaller bubbles which are influenced more by surface tension than inertia, demonstrated a higher particle removal rate than larger bubbles. For the Bc, the optimal range is from 0.3 to 0.5. We suggest that these dimensionless parameters can be used to diagnose the performance of and to design a DAF reactor.