Wetted area of packing materiels in a packed column

Abstract

Wetted area was measured for the four types of packing materials such as Raschig ring, half ring, half square and square. In order to obtain dyed area for the wetted area, paper was pasted on the surface of these packing materials and reddish dye, rhodamine, was added to the water to colour the paper on the surface of these packings. The water tand the air were contacted countercurrently in a 8-cm I. D. packed column. The effects of several variables which affect the wetted area were investigated. The variables investigated were gas flow rate, liquid flow rate, viscosity and surface tension. The experimental results showed that gas flow rate had no effect on the wetted area up to loading point, the values of $a_w/w_t$ were same as the value of no gas flow. The results also showed that the wetted area was affected by liquid flow rate and surface tension remarkably for all of the packing materials used. The effect of viscosity was appreciable for half ring, half square and square, but for Raschic ring, its effect was so small that it could be neglected. To generalize the results, dimensional analysis was undertaken with L,$\mu,\sigma,\rho,g$, and $a_t$, and the following correlations were obtained. For Raschig ring; $$\frac{a_w}{a_t} = 1.75 \times 10^1 \Bigg(\frac{L}{a_t\mu} \Bigg)^{0.036} \Bigg( \frac{L^2}{a_t\sigma\rho} \Bigg)^{0.295} \Bigg( \frac{L^2g}{\sigma^2a_{t^3}} \Bigg)^{0.318}$$ For half ring; $$\frac{a_w}{a_t} = 3.456 \times 10^2\Bigg( \frac{L}{a_t\mu} \Bigg)^{0.118} \Bigg( \frac{L^2}{a_t\sigma\rho} \Bigg)^{-0.490} \Bigg( \frac{L^3g}{\sigma^2a_{t^3}} \Bigg)^{1.356}$$ For half square; $$\frac{a_w}{a_t} = 2.095 \times 10^2 \Bigg( \frac{L}{a_t\mu} \Bigg)^{0.155} \Bigg( \frac{L^2}{a_t\sigma\rho} \Bigg)^{-0.065} \Bigg( \frac{L^2g}{\sigma^2a_{t^3}} \Bigg)^{0.894}$$ For square; $$\frac{a_w}{a_t} = 1.744 \Bigg( \frac{L}{a_t\mu} \Bigg)^{0.171} \Bigg( \frac{L^2}{a_t\sigma\rho} \Bigg)^{0.126} \Bigg( \frac{L^2g}{\sigma^2a_{t^3}} \Bigg)^{0.400}$$