Method and apparatus for extracting high-purity nitrogen from air

Abstract

The invention, which belongs to the technical field of gas separation and adsorption, particularly relates to a method and an apparatus for extracting high-purity nitrogen from the air. The apparatus comprises adsorption towers loaded with carbon molecular sieves, a vacuum pump for desorption, a pipeline for supplying the raw air to the adsorption towers, necessary control valves thereof, a pipeline for carrying out atmospheric-pressure desorption and capable of being switched to the inlet of the vacuum pump to carry out vacuum desorption, necessary control valves thereof, a gas product buffer tank, an oxygen transfer-preventing balance tank and the like. The method includes the following steps that: adsorption is carried out with adsorbent under the condition of pressurization, desorption is carried out under the vacuum condition, an enhanced circulation step for controlling the transfer of target gas and an effective method for preventing oxygen transfer are adopted for assistance, high-purity nitrogen with less than 3ppm of oxygen content is directly produced with the gas mixture of nitrogen and oxygen as raw gas, and moreover, the method is characterized by short starting time.

Description

technical field [0001] The invention belongs to the technical field of gas separation and adsorption, and in particular relates to a method and a device for extracting high-purity nitrogen from air. Background technique [0002] High-purity nitrogen is the basic gas for important basic industries such as electronics and metallurgy. Analytical industries such as chromatography also require a large amount of standard gases. Most of these standard gases require very low impurity content. At present, these gases basically rely on cryogenic air. The production of liquid nitrogen is obtained by vaporization and purification by various methods. The production process is complicated and the cost is high. [0003] In the field of non-cryogenic air separation technology, the production of high-purity nitrogen with an oxygen content of less than 3ppm generally adopts pressure swing adsorption technology or membrane separation technology to first produce crude nitrogen with a purity of ...

AI Technical Summary

Problems solved by technology

However, technical personnel in this field will understand that even so, the technical index of its product gas is difficult to meet the technical index of GB / T8980-1996 "High Purity Nitrogen", and its purity range is still limited to 5ppm oxygen content

9995%(no oxygen content, oxygen content is less than 5ppm), the product gas produced by these methods is difficult to meet the high-purity nitrogen (oxygen content is less than 3ppm) that meets the technical indicators of GB / T8980-1996 "High Purity Nitrogen"

Moreover, even if high-purity nitrogen with low oxygen content is produced, the adsorption process is difficult to stabilize the product gas composition at the required level due to many factors such as gas feed flow rate, ambient temperature, and differences in the double adsorption bed due to manufacturing. In the range

Images