Liquid film flow and area generation in structured packed columns

Several correlations are available in the literature for the prediction of wetted area or the effective interfacial area in packed columns. A careful examination shows considerable discrepancies in the calculated areas and co nflicting predictions concerning the influence of viscosity on the interfac ial areas. In this work, the effect of physical properties of liquids and o f surface treatment on wetted area of structured packings was experimentall y studied. Several wetting tests were performed on metallic and ceramic pla tes with flat, smooth or textured surfaces, using a circulation system, spe cially designed for this purpose. The liquid film width and thickness were measured for solutions with different surface tension and viscosities in a wide range (1 to 200 cP). The experimental results show that the liquid fil m width, and hence the wetted area, decreased with liquid viscosity, contra ry to earlier correlations in the literature. Also the influence of contact angle is not so strong as stated in the literature for random packings. In this study, a new statistical correlation for the estimation of the wetted area and for the liquid film thickness is proposed, reflecting the measure d variations with viscosity and advancing contact angles. (C) 1999 Elsevier Science S.A. All rights reserved.