Multi-cycle normal temperature air separation system and method

Abstract

The invention relates to multi-cycle normal temperature air separation system and method. The multi-cycle normal temperature air separation system mainly comprises at least one film separator cycle group, at least two pressure swing adsorption systems, at least one recycle compressor and at least one buffer tank. The multi-cycle normal temperature air separation system is characterized in that a retained side outlet of a first film separator is communicated with an air inlet of a raw material gas of a second film separator; the backside of the first film separator is connected with the recycle compressor in series; the backside of the recycle compressor is connected with the first pressure swing adsorption system in series; the compressor is also communicated with the first film separator; a second pressure swing adsorption system is connected to the backside of the retained side outlet of the second film separator in series; the buffer tank is respectively communicated with permeate gas outlets of the first film separator and the second film separator and exhaust vents of the first pressure swing adsorption system and the second pressure swing adsorption system; and adsorbents are filled into the first pressure swing adsorption system and the second pressure swing adsorption system according to separation needs. Oxygen with purity more than 97% or even 99.5% and nitrogen gas with purity more than 99.999% can be synchronously separated.

Description

technical field [0001] The invention belongs to the technical field of mixed gas separation, and relates to a system and method for realizing the separation of raw gas mixtures through a non-cryogenic separation process, in particular to a method for separating a mixture containing various gas components by using a multi-cycle separation system. Systems and methods for recovering at least one of the product gases in Background technique [0002] At present, cryogenic rectification technology is undoubtedly the mainstream technology in the industrial air separation market. In the field of large-scale air separation, it has lower separation operating costs and higher product gas purity. Moreover, the more important feature of this technology is that it is The method can take into account oxygen products, nitrogen products and even argon products at the same time, forming the production capacity of multiple products in one device. However, for on-site gas supply in specific en...

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Problems solved by technology

[0007] In order to obtain a multi-product on-site gas supply method to replace the low-temperature cryogenic process, many universities, research institutes, and business units have proposed many methods. US patent US772867 describes a pressure swing adsorption and membrane separation for purifying dual products The technology-coupled separation system, in one of the embodiments, adopts the pressure swing adsorption oxygen production system with nitrogen adsorbent. Originally, this system can usually purify oxygen-enriched gas with a purity of 88-95.7%. In order to effectively utilize the waste gas, improve The purity of the exhaust gas is coupled with a membrane separation system that captures higher purity nitrogen and the kinetic energy of the exhaust gas discharge in appropriate steps to achieve dual product recovery. However, the purity of the product components that can be achieved by this method is not high. According to The method described in embodiment, its oxygen product is limited to 88~95.7%, nitrogen then is limited to below 95%, obviously, its application is limited;

[0008] U.S. Patent No. 772866 also describes a pressure swing adsorption separation system that realizes double product recovery by trapping waste gas flow from the PSA system. Like the above-mentioned system, the purity of the product components that can be achieved by this method is not high, as described in the examples method, its oxygen product is limited to 88-95.7%, nitrogen is limited to below 95%-99.9%, obviously, its application is also limited;

[0009] JP116836 / 2001 Japanese patent discloses a gas separation method and system, using a first adsorbent (such as zeolite) that is not easy to adsorb the first main gas component (oxygen) and easily adsorbs the second main gas component (nitrogen) Molecular sieve) enriches the first main gas component (oxygen) into the first product, and uses the second main gas component (oxygen) which is easy to adsorb the first main gas component (oxygen) and the second main gas component (nitrogen) which is not easy to adsorb. The adsorbent (such as carbon molecular sieve) enriches the second main gas component (nitrogen) into a second product. Macroscopically, the system adopts a parallel pressure swing adsorption system, which can simultaneously recover the oxygen and nitrogen components mixed in the air. However, because the system simply uses a single-stage system, the separation is not only limited by the separation selectivity of the adsorbent used, but also uses an unimproved process for this single pressure swing adsorption system, which makes it difficult to achieve high-purity gas Component recovery, for example, is difficult to achieve a high-purity product stream of more than 99% for oxygen, and it is difficult to achieve a high-purity product stream of 99.999% for nitrogen; in addition, the system has not considered recovery or thorough and effective recovery of each PSA The valuable waste gas components removed by the system and the kinetic energy formed by compression, therefore, the recovery rate of the separate separation system must be low and it is difficult to use industrially;

[0010] Regarding multi-stage membrane separation, U.S. Patent US626559 discloses a method and system for separating a pure component gas from a gaseous mixture. In a separation system constructed with at least three-stage membranes, the necessary Compression equipment, thereby reducing energy consumption, using commercialized oxygen and nitrogen separation membranes with less energy consumption, lower cost to improve the purity of at least one component of the mixed gas purification process as a product output, but, with As in the case above, it is difficult to achieve multi-product recovery of high-purity gases

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