Pressure-swing adsorption (PSA) gas separation technology

Abstract

The invention relates to a pressure-swing adsorption (PSA) gas separation technology which enhances the productivity of product gas through carrying out twice adsorption on replacement tail gas and overcomes the defect that part of the product gas is lost resulting from the discharge of the replacement gas in gas separation. The PSA gas separation technology comprises seven processes, i.e. adsorption, pressure decrease, displacement, blowdown, evacuation, pressure increase and pressurization; the adsorption process means series adsorption, which is finished by two absorption towers together; the two absorption towers are divided into a primary absorption tower and a secondary absorption tower; the primary absorption tower generates intermediate gas through absorbing and forwardly transfers the intermediate gas to the secondary absorption tower; the product gas is obtained through absorbing the intermediate gas by the secondary absorption tower; and the product gas enters a next process section. Two parallel absorption towers are in series connection to together finish the adsorption process, the intermediate gas is obtained after the primary absorption tower which is positioned in the front and is in series finishes absorbing, and the product gas is obtained through transferring the intermediate gas to the secondary absorption tower, thus the purity of the product gas is always ensured to be high.

Description

technical field [0001] The invention relates to a gas separation process, in particular to a pressure swing adsorption gas separation process which utilizes displacement tail gas to undergo two adsorptions to increase the yield of product gas. Background technique [0002] At present, in the existing PSA gas separation technology, whether it is the product obtained from the easy-adsorbed phase, such as PSA to produce pure carbon dioxide, or the product obtained from the difficult-adsorbed phase, such as PSA hydrogen production technology, or it needs to be obtained from Obtaining products from the easily adsorbed phase needs to obtain products from the difficultly adsorbed phase. For example, pressure swing adsorption decarburizes the shift gas from synthetic ammonia for urea production. Inflow, after being adsorbed by the adsorbent inside the adsorption tower, the product flows out from the top of the adsorption tower, or enters the next adsorption tower for concentration p...

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Problems solved by technology

[0006] The invention solves the defect that the replacement gas is discharged during the gas separation, resulting in the loss of part of the product gas, and provides a replacement gas that is not emptied and used as a pressurized gas for another adsorption tower, and can also separate and obtain the product gas in the replacement gas , a gas separation and pressure swing adsorption process that improves the yield of product gas

[0007] The present invention also solves the defect in the prior art that the purity of the product gas is not high due to the discharge of the product gas through the adsorption tower once through the gas adsorption, and provides a pressure-changing device that can obtain a higher-purity product gas through two adsorption towers for continuous adsorption. Adsorption Gas Separation Process

[0008] The present invention also solves the defect in the prior art that the countercurrent venting of the adsorption tower after two adsorptions will take away the product gas in the first adsorption tower while reducing the product gas yield, and provides a method that undergoes two adsorptions, And the residual gas in the adsorption tower is transferred to another adsorption tower in the forward direction, which improves the adsorption effect and increases the product purity. The pressure swing adsorption gas separation process

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