CN1075742C

CN1075742C - Process for removing components from mixed gas with microporous membrane of hollow fibres

Info

Publication number: CN1075742C
Application number: CN99104230A
Authority: CN
Inventors: 徐又一; 徐红; 王建黎; 陈元胜; 王树源; 王红军
Original assignee: MEMBRANE SEPARATION ENGRG UNITED CO ZHEJIANG UNIV
Current assignee: Zhejiang University of Hangzhou Kai Hua Membrane Technology Co., Ltd.
Priority date: 1999-04-26
Filing date: 1999-04-26
Publication date: 2001-12-05
Anticipated expiration: 2019-04-26
Also published as: CN1240672A

Abstract

The present invention relates to a method for removing components from mixed gas by a microporous membrane made of hollow fiber. The microporous membrane made of hydrophobic hollow fiber is adopted. The mixed gas is at one side of the membrane, and corresponding absorption liquid is at the other side. The components which need to be removed from the mixed gas pass through a membranous wall and create an irreversible chemical reaction with the absorption liquid. Thus, an air pressure difference is formed at both sides of the membrane by the components and pushes the absorption liquid to continuously enter the other side of the membrane from one side of the mixed gas, and the rest of the components in the mixed gas can not create a chemical reaction with the absorption liquid so that no pressure difference is formed at both sides of the membrane. Therefore, the components in the mixed gas, which create the chemical reaction with the absorption liquid, are separated. Moreover, new useful products can be generated from the reaction of the components and the absorption liquid.

Description

Method for removing components in mixed gas by using hollow fiber microporous membrane

The invention belongs to a technology for separating components from mixed gas, and relates to a membrane method for separating the components of the mixed gas.

The existing membrane method for separating mixed gas components is applied in a wide field. The commonly used membrane materials are all dense membranes, such as polyimide, polyethersulfone and the like. The separation of the components of the mixed gas is realized by utilizing the dissolution and diffusion mechanism of the membrane material to the gas according to different selectivities of the membrane material to the gas.

This technique for separating the gaseous components with a dense membrane has the following disadvantages:

1. the large pressure difference between the two sides of the membrane is needed, which makes the equipment complicated and increases the production cost.

2. The selective separation factor of the dense membrane material to gas is often in inverse proportion to the gas permeation rate, namely, if the gas permeation rate is high, the separation factor is low, so that the gas separation efficiency is limited;

3. the compact membrane material has different selective permeability to gas, and if the gas is changed, different compact membranes are required to be selected, which brings inconvenience to production and use.

The invention aims to provide a membrane gas separation technology under the normal pressure condition aiming at the defects of the prior art, and the membrane gas separation technology has the advantages of high separation efficiency, simple structure and low cost.

In order to achieve the purpose, the technical scheme of the invention is as follows:

adopting a hydrophobic polypropylene or polyethylene hollow fiber microporous membrane, connecting mixed gas of which components (particularly acid and alkaline gases) are required to be removed on one side of the membrane, and arranging corresponding absorption liquid on the other side of the membrane; both sides of the membrane are at normal pressure; due to the hydrophobic nature of the membrane, the absorbed liquid cannot pass through the microporous membrane wall; although all components in the mixed gas can pass through the microporous membrane wall to one side of the absorption liquid, the gas components which do not require separation and removal do not react with the corresponding absorption liquid, only the components which require removal from the mixed gas immediately react with the absorption liquid irreversibly through the microporous membrane wall, so that the components form a large gas pressure difference on two sides of the membrane, and the component gas continuously enters the other side of the membrane from one side of the mixed gas and continuously reacts with the absorption liquid irreversibly. In this way, the removal of the gas components to be separated from the mixed gas can be achieved. At the same time, the component can produce new useful substances together with the absorption liquid.

The invention has prominent substantive characteristics and remarkable progress:

1. the microporosity and the air permeability of the polypropylene or polyethylene hollow fiber microporous membrane are utilized to ensure that gas can pass through the membrane wall at a large permeation rate;

2. the technology takes the membrane as a boundary, the gas phase and the liquid phase respectively flow, the two-phase flow and the pressure can be respectively controlled, the environmental pressure adopts normal pressure, a complex pressurizing device is not needed, the structure is simple, the cost is low, and the popularization and the use are convenient;

3. the gas component to be separated and the absorption liquid are subjected to irreversible chemical reaction, so that the gas pressure difference on two sides is used as a driving force, the component can be separated in a high selectivity manner, the removal rate of acidic components or alkaline gas components in the mixed gas can reach 90-98%, the purity of a product obtained on one side of the absorption liquid can be high, and the product can be used for preparing reagent-grade products.

Examples of the inventive scheme:

example 1: the mixed gas at one side of the membrane is synthetic ammonia copper washing regeneration gas as an example, and the components of the mixed gas comprise Co and NH₃、CO₂、N₂、H₂And the absorption liquid on the other side of the membrane adopts sulfuric acid, and the NH is required to be removed from the mixed gas₃。NH₃The gas enters the sulfuric acid solution through the hollow fiber microporous membrane to perform the following chemical reactions:

obtaining thiamine solution, and obtaining refined ammonium sulfate through post-treatment.

After treatment in this way, NH₃The content of (A) can be reduced from 18.4% to below 0.01%.

Example 2: the mixed gas at one side of the membrane is methane or natural gas, wherein the main component is CH₄、H₂S、CO₂And the like. The polypropylene hollow fiber microporous membrane is used as a separation membrane material, and NaOH is used as absorption liquid. H₂S and CO₂Can react with NaOH to remove CO₂、H₂S, etc. to realize CH₄Purification of (4).

Claims

1. A method for removing the components from gas mixture by the use of hollow-fibre microporous membrane features that a hydrophobic polypropylene or polyethylene hollow-fibre microporous membrane is used, one side of said membrane is communicated with gas mixture, and the other side of said membrane is filled with absorbing liquid.

2. The method for removing components from mixed gas by using a hollow fiber microporous membrane as claimed in claim 1, wherein the mixed gas on one side of the membrane is regenerated gas washed with synthetic ammonia copper, the absorption liquid on the other side of the membrane is sulfuric acid, and the components in the mixed gas comprise CO and NH₃、CO₂、N₂、H₂Removal of NH therefrom₃,NH₃The permeable hollow fiber microporous membrane and sulfuric acid solution are subjected to chemical reaction: obtaining ammonium sulfate solution, and removing NH₃At the same time, refined ammonium sulfate can be obtained.