Overview of methods to control the liquid distribution in distillation columns with structured packing: Improving separation efficiency

Abstract

The paper presents experimental results on the effect of characteristics of liquid spreading over the surface of a structured packing, distribution of local flow parameters over the cross-section and height of the distillation column under various conditions of initial packing irrigation. It is shown that the corrugation angle of the structured packing sheets, microtexture parameters, presence of perforation and size of holes, as well as liquid flow rate determine the patterns of liquid spreading and wetting of the packing surface. The test results for a new method of dynamic control of the liquid distributor with independent valves for each drip point are presented with the aim of influencing large-scale flow maldistribution in the column and increasing the separation efficiency. The data obtained in these experiments showed that a targeted change in the position of active irrigation points based on the actual distribution of local parameters in the separation column can lead to a noticeable increase in the efficiency of mixture separation up to 20% compared to a regular distributor with a fixed position of drip points. The effect of variation of the turn angles of the structured packing layers (20°, 45°, 70°, and 90°) on the efficiency of mixture separation was studied. Using a passive method to decrease the nonuniformity of distribution of local flow parameters by increasing the rotation angle of the structured packing layers in the column also leads to an increase in the separation efficiency. For the rotation angles of the packing layers (70–90) degrees, the HETP decreased in comparison with the rotation angle of 20° by (10–12) %.