Dynamics of a change in the local density of liquid flow rate and efficiency of mixture separation at periodic irrigation of the structured packing

Abstract

The use of modern structured packing in the distillation columns allows much more even distribution of the liquid film over the packing surface, but it does not completely solve the problem of uniform distribution of flow parameters over the entire height of the packing. Negative stratification of vapor along the packing height caused by different densities of vapor mixture components and higher temperature in the lower part of the column leads to formation of large-scale maldistributions of temperature and mixture composition over the column cross-section even under the conditions of uniform irrigation of packing with liquid. This work presents the experimental results obtained at periodic packing irrigation with total blocking of the spray nozzle. The experiments were carried out in the distillation column with the diameter of 0.6 m on 10 layers of the Sulzer 500X packing with the total height of 2.2 m. The mixture of R-21 and R-114 was used as the working liquid. To irrigate the packing, the liquid distributor with 123 independently controlled solenoid valves overlapping the holes with the diameter of 3.6 mm, specially designed by the authors, was used. Response of the column to the action of liquid distributor was observed in real time according to indications of 3 groups of thermometers mounted in 3 different cross-sections of the column. The flow meter located at a fixed point of the column cross-section allowed registration of dynamics of a change in the local flow rate density of liquid flowing from the packing.