Gas and Liquid Axial Mixing in the Column Packed with Mellapak 250Y, Pall Rings 25, and Intalox Saddles 25 under Flow Conditions Prevailing in Distillation Columns

Abstract

The axial dispersions of gas and liquid phase in a column of inner diameter 0.297 m packed with random packing of metal Pall rings 25 and Intalox saddles 25 and structured packing of Mellapak 250Y were measured using a dynamic method under hydraulic conditions common in distillation columns, i.e., liquid flow rate from 6.94 × 10−4 to 0.0111 m/s and gas flow rate from 0.25 to 2 m/s. The two-response method with a diffusion-type model was used to reproduce the experimental response curves. Axial mixing in the gas increases with gas and liquid rates for both random and structured packings, but the dependence on the gas rate is very weak for the structured packing. The largest gas mixing was found for the Pall rings at the highest gas rate; the least was found for the structured packing at the lowest gas and liquid rates. Liquid-phase axial mixing increases with decreasing liquid flow rate and is independent of gas flow rate for both random and structured packings. The largest liquid mixing was found for the Intalox saddles at the lowest liquid rate; the least was found for the structured packing. The correlations of BoL and BoG numbers deduced for all types of packings used reproduced the experimental data within ±22%.