Method for increasing concentration of gas easy to adsorb by using pressure swing adsorption method

Abstract

The invention provides a method for increasing the concentration of a gas easy to adsorb by using a pressure swing adsorption method. The method comprises the following steps: (1) feeding a raw material gas into a first adsorption tower, and performing adsorption operation till an adsorbent is saturated; (2) performing pressure equalizing operation on a first adsorption tower after adsorption; (3)introducing a product gas into an unadsorbed gas for exchange, and blowing an exchanged gas into other adsorption towers; (4) performing pressure equalizing operation on the first adsorption tower after exchange for a second time; (5) performing vacuum desorption on the first adsorption tower so as to obtain a product gas; (6) pressurizing the first adsorption tower after desorption. Through theprocedures, multiple adsorption towers cooperate to achieve concentration increase of the gas easy to adsorb, particularly the product gas is adopted as an exchange gas, the exchanged gas is fed intoother adsorption towers, and pressure equalizing operation is implemented after exchange, so that not only is the exchange effect improved, but also the concentration and the recycling rate of a component easy to adsorb can be increased.

Description

technical field [0001] The invention belongs to the technical field of gas adsorption, and relates to a method for enriching easily adsorbed gas by a pressure swing adsorption method, in particular to a method for enriching an easily adsorbed gas by a pressure swing adsorption method including product gas replacement. Background technique [0002] Pressure swing adsorption is a commonly used gas separation method in the chemical industry. It has been widely used in industry due to its advantages such as strong flexibility, low operating cost and good separation effect. According to the need, after adsorption and separation, the easily adsorbed gas can be recovered, and the remaining gas that is difficult to adsorb can also be recovered, or both can be recovered at the same time. Among them, the adsorbent is one of the factors affecting the separation effect, and the design optimization of the adsorption process is also crucial to the improvement of the separation effect. ...

AI Technical Summary

Problems solved by technology

[0003] At present, the process of gas adsorption separation generally includes the steps of adsorption, pressure equalization, desorption, and final filling. Replacement is also one of the commonly used operations in the adsorption process, which can be used to increase the product concentration to a certain extent. In addition to the impurity gas, the gas in the tower also has part of the product gas. The direct discharge of the replaced gas will cause the loss of the target product gas, reduce the product recovery rate and cause pollution at the same time. If the replaced gas is sent back to the raw material tank, will reduce the gas handling capacity of the adsorbent

In addition, when gas separation is carried out under high pressure conditions, low-pressure replacement is generally used. Low-pressure replacement operation not only has a limited effect on the enrichment of product gas, but also causes gas desorption due to the reduction of the partial pressure of the target gas, which reduces the treatment efficiency of the target gas. Amount and thickening effect

[0004] CN 107694284A discloses a multi-tower replacement vacuum pressure swing adsorption method for concentrating gas layer methane, mainly including pressurization, CH 4 Adsorption, CO 2 Substitution, pressure reduction, adsorbent vacuum desorption, vacuum purging and other steps, this method does not use pressure equalization operation before the replacement, the pressure of the replacement gas is relatively high, which will not only replace the unadsorbed gas in the tower, but also replace methane, resulting in gas The separation effect is not good, and the use of CO 2 The replacement will also introduce other impurity gases, which is not conducive to the enrichment of methane in coalbed methane

CN102350171A discloses a gas separation method using a replacement method. There are at least 6 adsorption towers combined together to realize cyclic adsorption. Each adsorption tower completes the processes of adsorption, depressurization, emptying, replacement, vacuuming, boosting and charging in sequence. Circulation process, at the same time, each adsorption tower completes a process, but this method is to absorb the impurity gas in the raw material gas, and complete the follow-up process on this basis, the focus is on gas separation, for the adsorption and enrichment of product gas The operating procedures and the coordination of each adsorption tower will be quite different

Images