P. N. Drozdov

High purification of gas in radial membrane element

The process of high purification of gas from easily penetrating impurities in a countercurrent radial membrane element is investigated theoretically and experimentally. The mathematical model of process is developed in view of longitudinal mixing impurities in both cavities of an element, and with the consider recycle of a target flow from a cavity of high in a cavity of low pressure (retentate recycle). It is found that, the researched membrane elements have the high separation power. It is shown that the retentate recycle should be realized in membrane elements with high-selectivity and low permeability of the basic component membranes. The experimental and the calculation results are in agreement.

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank

Deep gas cleaning of highly permeating impurities using a membrane module with a feed tank has been considered. Two modes of the process has been studied, one with a constant degree of separation in the membrane module and the other with a constant concentration of impurities in the stream directed to the receiver tank. The degree of removal and the time of the process have been calculated. It has been shown that the second mode is somewhat more cost-effective because of the lack of mixing of streams with different concentrations and the absence of the lost work of separation.

Gas mixtures separation by an absorbing pervaporation method

Abstract This article discusses the results of research on absorption and pervaporation processes in combination. The processes realize in the volume of one mass-exchange device. The separating characteristics of the hybrid process were compared with the gas separation membrane process. It is shown why the separation factor absorbing pervaporation essentially increases. The influence of different factors on a separation factor has been studied. The mathematical model well describes the gas mass transfer through the absorbent—membrane system.

Fine Purification of Silane for Removal of Chlorosilanes by Membrane Gas Separation

The membrane separation of a silane, dichlorosilane, trichlorosilane, and tetrachlorosilane gas mixture has been theoretically and experimentally studied. The ideal separation factors have been determined experimentally and their values in the separation cell at pressures P1 and P2 have been found. The separation factor has been calculated for different ratios of flows in the compartments of a membrane module. The silane cleaning process for the removal of highly penetrating impurities in a radial membrane module and in a membrane module with a feed tank has been calculated.

Nitrous oxide high purification by membrane gas separation

In this work the scope of nitrous oxide high purification by membrane gas separation was presented. The permeability values of nitrous oxide and its limiting impurities were measured for “Lestosil” membrane at feed pressure in the range from 100 to 400 kPa. The values of ideal selectivity were determined. It was shown that nitrous oxide is more permeable than impurities components. Therefore the process of nitrous oxide high purification was calculated for it carried out in membrane module with a feeding reservoir which is used for purification from low permeable impurities.

Separation and concentration of a low-penetrating impurity by membrane gas separation

The process of concentrating low-penetrating impurities in membrane modules was studied theoretically and experimentally. An expression was derived for the degree of separation in a radial cross-flow module; the degree of separation substantially depends on the gas-phase diffusion coefficient of the impurity. The experimental results obtained for a mixture of carbon dioxide with an impurity of Freon 14 and a mixture of Freon 12 with an impurity of Freon 218 agree with calculated data.

Gases high purification from unreadily permeating impurities in one-compressor multistage membrane apparatuses

The present work is focused on gases high purification from unreadily permeating impurities by one-compressor multistage membrane apparatus (OMMA). It looks like a simple one way membrane cascade, consisting from several membrane modules with only one compressing point. In this operating regime the pressure of high pressure cavity is decreasing from one to another while the concentration of high penetrating component is increasing. The equation of purification degree calculation was obtained. It shows how the impurity concentration of permeate reduces in comparison with initial concentration of flow (feed flow), incoming to the membrane module or apparatus. The equation for purification degree calculation was obtained. For the case of low impurity concentration there was leaded the comparison of calculated and experimental (from patent) data. The dependence of purification degree on the number of membrane modules composed apparatus which has an extremum was shown.The description of one-compressor multistage membrane apparatus was determined. The equation of purification degree calculation was obtained. It shows how the impurity concentration of permeate reduces in comparison with initial concentration of flow (feed flow), incoming to the membrane module or apparatus. The equation for purification degree calculation was obtained. For the case of low impurity concentration there was leaded the comparison of calculated and experimental (from patent) data. The dependence of purification degree on the number of membrane modules composed apparatus was shown.

Membrane module with a feed tank for fine purification of gases

The process of fine purification of gas from readily and poorly permeating impurities using a membrane module with a feed tank from which impurities are continuously withdrawn is considered. Equations for the degree of separation of the initial mixture are obtained and phosphine purification from readily and poorly permeating impurities is calculated.

Ultrapurification of gases in a continuous membrane column cascade

The high purification of gases from easily penetrating impurities by a cascade of a continuous membrane column type has been investigated experimentally and theoretically. The equations for the separation power of cascades in the case of high purification of gases from low level impurities has been obtained. The efficiency of a continuous membrane column cascade is compared with exergetic efficiency of a multistage symmetric cascade in the case of non-mixed flows at different concentrations.

Separation of Gas Mixtures by the Absorption–Pervaporation Method

Absorption–pervaporation separation of gas mixtures is studied and compared with membrane gas separation. The absorption–pervaporation method ensures a much higher separation coefficient of the HCl–H2mixture. An equation is derived for calculating the fluxes of the mixture components through the absorbent–membrane system.