Method for preparing oxygen and nitrogen by air separation

An air separation and oxygen technology, applied in separation methods, chemical instruments and methods, oxygen preparation, etc., can solve the problems of difficulty in oxygen purity higher than 95%, low oxygen production efficiency, poor adsorption selectivity, etc.

Inactive Publication Date: 2009-06-10
DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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Problems solved by technology

[0007] Molecular sieve adsorbent can adsorb both nitrogen and oxygen, and the adsorption selectivity is poor, and it has a strong adsorption to nitrogen, the highest content component in the air, which leads to low efficiency of oxygen production by pressure swing adsorption
Furthermore, the pressure swing adsorption method cannot effectively separate oxygen and argon, making it difficult for the oxygen purity to be higher than 95%, which limits the application of the pressure swing adsorption method to produce oxygen in many fields

Method used

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  • Method for preparing oxygen and nitrogen by air separation
  • Method for preparing oxygen and nitrogen by air separation
  • Method for preparing oxygen and nitrogen by air separation

Examples

Experimental program
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Effect test

Embodiment 1

[0024] Example 1 Oxygen separation performance of oxygen-permeable ceramic membrane

[0025] The prepared oxygen-permeable ceramic membrane tube is composed of figure 1The oxygen permeable ceramic membrane permeator shown in . The outer casing of the permeator is a stainless steel tube, and the length and diameter of the oxygen-permeable ceramic membrane tube are determined according to the size of the specific separator. The outer diameter of the membrane tube used in this embodiment is 2.5 mm, the inner diameter is 1.5 mm, and the length is 6 cm; one end of the membrane tube is sealed, and the other end is connected with a quartz tube, and the quartz inner tube is connected with an oil-free dry pump. After the membrane tube is sealed at high temperature, air is introduced. The air flow rate is 50-1000ml / min. At 925°C, the relationship between the oxygen permeability of the oxygen-permeable ceramic membrane and the oxygen recovery rate was studied by changing the air flow ...

Embodiment 2

[0026] Example 2 Oxygen adsorption and desorption cycle performance of complex metal oxides

[0027] The prepared complex metal oxide powder is ground and granulated. The adsorbent can be amorphous, spherical, cylindrical, honeycomb, etc. The particle size depends on the size of the adsorption separator. In this embodiment, an adsorption separator is used to realize the regeneration of the adsorbent by means of vacuum pumping, so as to study the adsorption-desorption cycle performance of the adsorbent. The particle size of the adsorbent used is 20-30 mesh, and the adsorbent consumption of the pressure swing adsorption separator is 23 grams. image 3 The adsorption and regeneration cycles of complex metal oxide adsorbents are given. from image 3 It can be seen that the adsorbent has a good cycle ability. The adsorption capacity of such adsorbents is generally small (<10ml / g). Using this kind of adsorbent alone to separate air has limited production capacity and is not su...

Embodiment 3

[0028] Example 3 Oxygen adsorption capacity of complex metal oxides

[0029] The particle size of the adsorbent used in this example is 20-30 mesh, and the adsorbent is regenerated by purging with inert gas (He) to study the oxygen adsorption capacity of complex metal oxides. The amount of adsorbent used is 7 grams, and the operating temperature is 470°C. Under these conditions, the adsorption capacity of the adsorbent is 4ml / g. Increase the adsorption pressure to 2MPa, and the adsorption capacity of the adsorbent increases to about 6ml / g.

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Abstract

The invention provides a method for producing oxygen and nitrogen through air separation. The whole process is carried out on a platform consisting of a mixed-conductor oxygen-permeable ceramic membrane separator and a pressure swing adsorption separator taking complex metal oxide as oxygen absorbent. The process comprises the following concrete steps: most oxygen in the air is adsorbed by a mixed-conductor oxygen-permeable ceramic membrane; the remained air is oxygen-deficient air; the pressure swing adsorption separator taking the complex metal oxide as the absorbent adsorbs oxygen in the oxygen-deficient air; and the oxygen is desorbed under the lower pressure between 1 Pa and 100 kPa to ensure that the remaining gas after adsorption is mainly nitrogen, so as to obtain high-purity nitrogen. The method has the advantages that the method can efficiently separate the oxygen from oxygen-containing gas and separate oxygen and nitrogen from the air in an energy-saving way.

Description

technical field [0001] The invention relates to a method for separating air by combining the separation of mixed conductor oxygen-permeable ceramic membrane and the pressure swing adsorption of complex oxide as adsorbent. Background technique [0002] Oxygen and nitrogen are very important chemical raw materials. At present, oxygen and nitrogen are generally obtained through low temperature distillation and pressure swing adsorption. The working principle of low-temperature rectification is to compress and liquefy the air, remove impurities and cool it down, and then conduct gas-liquid contact on the rectification tray according to the difference in the boiling points of oxygen and nitrogen; due to the high boiling point of oxygen, the oxygen in the air The components will continue to condense out of the steam and enter the downstream liquid, while the nitrogen components with low boiling points will continue to transfer into the rising steam, which makes the nitrogen conten...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B13/02C01B21/04B01D53/047
CPCY02P20/10
Inventor 朱雪峰杨维慎丛铀贺玉凤
Owner DALIAN INST OF CHEM PHYSICS CHINESE ACAD OF SCI
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