SU1119718A1 - Method of separating gas mixtures - Google Patents

Abstract

METHOD OF SEPARATION OF GAS MIXTURES, including creating a high-pressure gas mixture stream on one side of a semipermeable membrane, enriching with difficult-to-penetrate components, a countercurrent low-pressure gas mixture stream on the other side of the semi-permeable membrane, enriching light-copying components, supplying the initial gas mixture to the intermediate point of the stream high pressure, compression of the exiting flow low pressure, separation of the compressed flow into two parts, supply of one part of and the input of the high pressure flow, the output of its second part as a product enriched with easily penetrating components, and the output of the high pressure flow as a product enriched with low-penetrating components, characterized in that, in order to reduce capital and energy costs at a given degree of separation and productivity for both products, the separation of the compressed stream i is carried out on an additional semi-permeable membrane with a stream penetrating through it as an enriched product easily penetrating; components.

Description

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The invention relates to the field of separation of gas mixtures and can be used in technological processes using semipermeable membranes.

In modern industry, methods based on the different ability of components to penetrate membrane partitions are used to obtain substances enriched in certain components of gas mixtures. In this case, the separation process is carried out in such a way that the mixture to be separated is passed on one side of the membrane septum to the high pressure area, and a concentration gradient is created on the membrane between the high and low pressure areas. To achieve a greater effect, use methods based on building upon cascade separation schemes, or on sequential separation of the mixture using membranes with different selective properties 1.

However, these methods are expensive, since for their implementation they require a large number of compressors, sophisticated technological equipment and high dimensions - in the first case, and are associated with difficulties in selecting membranes with the required selective properties - in the second.

A known method for separating gas mixtures using semipermeable membranes involves creating a stream of high-pressure gas mixture from one side of the membrane, which is enriched with impermeable through the membrane components, and a countercurrent flow of low-pressure gas mixture from the other side of the membrane enriched with easily penetrating components. The source gas mixture is fed to the intermediate point of the high pressure stream. The output stream is low, the pressures are compressed, divided into two parts, one of which is fed to the inlet of the high pressure stream, and the second part is used as a product enriched with light-penetrating components, and the quality of a product enriched with hard-penetrating components is used pressure. This separation method is often referred to as separation in a continuous continuous flow counter membrane 2.

However, with an increase in the degree of separation of the initial mixture along an easily penetrating component through the membrane, both the column length (the membrane area and capital costs are required) and the value of the flow being compressed (energy costs) increase significantly.

The purpose of the invention is to reduce capital and energy costs at a given

degrees of separation and performance for both products.

This goal is achieved in that according to the method of separation of gas mixtures, including creating a stream of high-pressure gas mixture on one side of a semipermeable membrane enriching with difficult-to-penetrate components, a counter-current flow of low-pressure gas mixture on the other side of a semipermeable membrane enriching with easily penetrating components, supplying the initial gas mixture to the intermediate point of the high pressure flow, compressing the output flow of the low

pressure, separation of the compressed flow into two parts, supplying one part to the inlet of the high pressure flow, outputting the second part of it as a product enriched with easily penetrating components, and outputting high pressure pulling as a product enriched with hardly penetrating components, separating the compressed flow an additional semipermeable membrane with a branch of a stream penetrating through it as a product enriched with easily penetrating components.

At THOM, an additional separation of the mixture occurs, which allows an increase in the concentration in the selection of the easily penetrating component, with a constant value of its selection flow. For given values of the degree of separation of the mixture and productivity of both products, additional separation makes it possible to reduce the membrane area in the column and

recyclable material flow. The reduction in the membrane area of the column significantly exceeds the area of the additional membrane.

The effect achieved is first

a queue with the fact that a small part of the compressed flow passes through the additional membrane and, accordingly, the separation capacity of its unit of area is close to the maximum possible and far exceeds the corresponding value for the membrane operating in the column. The decrease in the compressible flow (decrease in compressor power) is associated with a decrease in the circulation flow, due to a decrease in the required degree of enrichment of the light-penetrating component in the column.

The proposed method is used to obtain a CO2 gas of a concentration of 94.6% from a mixture of gases. The concentration of CO in the feed stream is 52.6%. Gas separation is carried out on a 5 m long membrane column. The membrane is made in the form of hollow fibers made of silicone rubber. High pressure is 220 kPa, and

low pressure 98 kPa. The magnitude of the circulating flow varies from 85 to 7 mol / s. The sampling stream enriched with easily penetrating components is 2.37 mol / s, and the sampling enriched with hardly penetrating components is 2.39 mol / s. If the low pressure output stream is subjected to additional separation on a membrane of the same material, while preserving the working parameters of the process, the concentration of CO 2 in the selection and the capacity of the installation, then by reducing the three-fold. With a low concentration of CO at the outlet of the low pressure flow to almost 90%, it is possible to reduce the length of the column by 35%. The area of the additional membrane is only about 5% of the initial membrane area of the column. Compressed value circulation flow and respectively

electricity costs are halved. In view of the low hydrodynamic resistance, the increase in energy consumption required for the operation of the additional membrane is insignificant.

The efficiency achieved when separating gas mixtures according to the proposed method as compared to the known method leads to significant savings in expensive membrane material, as well as to a significant reduction in capital and energy costs, regardless of the type of composition of the mixture to be separated and the membrane selectivity characteristics.

The efficiency of the use of the proposed method increases with an increase in the required concentration of the easily penetrating component in the stream of its selection.

Claims (1)

METHOD FOR SEPARATING GAS MIXTURES, including the creation of a high pressure gas mixture flow on one side of a semipermeable membrane enriched with difficult to penetrate components, a low pressure gas flow countercurrent flow on the other hand j. a semi-permeable membrane, enriched with easy-penetrating components, supplying the initial gas mixture to an intermediate point of the high pressure stream, compressing the output low pressure stream, dividing the compressed stream into two parts, supplying one part to the inlet of the high pressure stream, outputting the second part as an enriched product low-penetrating components, and the output of the high pressure stream in the form of a product enriched with difficult-penetrating components characterized in that, in order to reduce the capital At the specified degree of separation and performance for both products, the separation of the compressed stream _{s is} carried out on an additional semipermeable membrane with the removal of the flow penetrating through it in the form of a product enriched with easily penetrating components. SU.,., 1119718>