Study of Mass Exchange between Steam and Liquid in Rectification
The relevance of this work is due to the need to obtain a criterion dependence for calculating the coefficient of mass transfer rate in the vapor phase on failure plates of distillation columns. For this purpose, mass transfer between vapor and liquid was studied during the rectification of binary mixtures. The article presents a description of a semi-industrial installation for the separation of a methanol-isopropanol mixture in full irrigation mode and the experimental procedure. A mathematical model of the process has been drawn up. The specific volume surface of the contact phases has been defined; its dependence on the liquid supply on the plate has been established. The increase in the specific volume surface with the increase in fluid supply is due to better steam fragmentation and the formation of smaller bubbles. The mass transfer rate coefficients are calculated. It was found that their values do not remain constant along the height of the vapor-liquid layer, but gradually decrease. An analogy of the processes of exchange of mass bubbling and single outflow of steam is noted. The dependences of the conductivity on the liquid supply on the plate and on the size of the vapor bubble are shown. As a characteristic linear size in the criteria, the average surface-volume diameter of the vapor bubbles was used. The obtained criteria dependence well generalizes the experimental results of other binary systems.