Studies of Freon mixture separation using a large-scale model of distillation column

Abstract

The operation efficiency of distillation columns with structured packing is maximal if the distribution of countercurrent vapor and liquid film flows over the column cross-section on the mass transfer surface is most uniform. Various types of structured packing are widely used in distillation columns. Formation of the temperature field maldistribution in the column cross-section is observed in large-scale distillation columns. The sizes of large-scale maldistributions on zones are commensurate with the column diameter. The aim of this work is to obtain experimental data on the separation efficiency in large-scale distillation columns and dynamics of formation of large-scale maldistributions of local parameters of vapor and liquid in a countercurrent flow over a structured packing during mixture separation. Separation of the R114/R21 freon mixture was carried out on a structured Mellapack 350.Y packing with a diameter of 0.9 m and height of 2100 mm. The experiments were carried out under conditions of complete reflux in the range of reduced vapor velocity of 0.017 < K v < 0.035 m/s. Experimental data were obtained on the efficiency of mixture separation, pressure drop over the structured packing and parameters determining the formation dynamics of the large-scale temperature field maldistribution in the column cross-section. The presented experimental data will be used for the construction and verification of a new model of mass transfer and efficiency of mixture separation in large-scale distillation packed columns.

Studying the process of freons mixture separation on a structured packing Sultzer 500X

“…Within (10-15) minutes, the uniform temperature field in the packing cross-section transforms into a stable largescale irregularity with diametrically located areas of minimum and maximum temperatures. The difference in the minimum and maximum temperatures in the middle cross-section of the packing is (4-5) K with a total temperature difference along the packing height of (5-6) K. Formation of large-scale non-uniformity in temperature distribution on the Mellapack 350.Y packing of a 0.9-m diameter at vapor velocities of 0.15 and 0.26 m/s is similar to [12,13]. Hydrodynamics of the gas (vapor) and liquid phases in counter-flow columns with packing is characterized by the presence of a liquid layer on the column wall, even when the contact surface of the packing with the wall is small [18].…”

“…The data on the efficiency of mixture separation and pressure drop across the structured Sulzer 500X packing are shown in Fig. 3 in comparison with the corresponding experimental data for the structured Mellapack 350.Y packing [13]. The packing heights are 2200 and 2100 mm, respectively.…”

“…3. Efficiency of mixture separation (HTU) and pressure drop on the structured Mellapack 350.Y [13] and Sulzer 500X packing. 1 -HTU Mellapack 350.Y [13]; 2 -HTU Sulzer 500X; 3, 4 -pressure drop on the packings, respectively.…”

“…Based on these studies, our efforts are directed towards development of a CFD model of a counter-current two-phase flow, proper for structured packings (as well as random packings). The experimental data obtained in this work and in [12,13,23] are currently used for the development and verification of the proposed model.…”