JPH02251217A - Adsorption and separation tower for gas separation - Google Patents

Abstract

PURPOSE:To contrive the recovery of a difficultly adsorbable gas with a good degree of efficiency by providing a porous resistance plate perpendicularly to a gaseous stream on an adsorbent bed of an adsorptive separating tower filled with adsorbent. CONSTITUTION:A mixed gas (e.g. air) is separated into a difficultly adsorbable gas (e.g. oxygen) and an easily adsorbable gas (e.g. nitrogen) by pressure swing process using an adsorbent (e.g. zeolite) for effecting a selective adsorption of the gas of a specific component. A porous resistance plate 13 is provided perpendicularly to a gaseous stream on an adsorbent bed 11 of an disruptive separating tower 10 filled with the adsorbent. This reduces the amount of the easily adsorbable gas being carried off with the difficultly adsorbable gas in the process of recovering the difficultly adsorbable gas, which, therefore, can be efficiently recovered as a whole.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an improvement in an adsorption separation column that separates a mixed gas into component gases by a pressure swing method.

[Conventional technology]

Using an adsorbent that has the property of preferentially (selectively) adsorbing specific component gases, crystalline iron and layered gases are adsorbed under pressurized conditions, and gases that are difficult to adsorb are separated. The method of regenerating adsorbents by desorbing easily adsorbable gases is called the pressure swing gas separation method (PSA method), and is widely used in industrial applications such as air separation equipment (O, gas, Nt gas production). It is used in

An example of this PSA type gas separation device is shown in FIG. 3, and its structure and function will be explained. This equipment mainly consists of the following equipment.

1 is a raw material gas blower, which is a device that supplies raw material gas under pressure to an adsorption tower; 2A and 2B are adsorption towers; iA and 3B are adsorbent beds provided inside the adsorption towers 2A and 2B, 4 is a vacuum pump that reduces the pressure in the adsorption towers 2A and 2B and regenerates the adsorbent, 5 people, 6 people, 7 people, 8.5B , 6E and 7B are switching valves that switch the flow of gas according to a predetermined cycle time.

Next, the functions of the most widely used PSA type gas separation apparatus, a gas production apparatus, will be explained using FIG. 3 as an example.

PSA formula 0. In the case of gas production equipment, generally 5A type or 13
Zeolite MoV Cuosieves, called type X, is used as an adsorbent, and is operated through the following three operating steps to produce O gas using air as a raw material gas.

(1) Adsorption step: 0.0% in this step. Gas is produced.

Air serving as a raw material gas is sent to two adsorption towers by an air blower 1 through a switching valve 5Af. The two adsorption towers are filled with zeolite MoV cup sieves, which have the property of preferentially adsorbing N and gases compared to O and gases, as an adsorbent bed 3A.

N gas, which is about 79% contained in the raw air, is gradually adsorbed by the adsorbent as it passes through this adsorbent bed 5A, and as a result, O gas, which is difficult to adsorb, is gradually concentrated at the same time.
Concentration 0.0 through 7 switching valves. Produced as gas in 4R minutes.

As this adsorption process progresses, the N adsorption capacity of the adsorbent 13A decreases, so this adsorption process is completed at 0. The process ends before the gas concentration drops to a predetermined concentration.

Usually 90~b in the second step It will be done.

+210. Gas recovery step: In this step, the O8-enriched gas remaining in the upper part of the adsorption tower at the end of the adsorption step is recovered. As a result of the adsorption process being completed before the product ata degree has decreased to a predetermined degree, 0.0% is left in the space above the adsorption tower and the adsorbent voids in the adsorbent bed 3A. Enriched air remains. This gas is transferred to the switching valve 5A,
7A is closed, the switching valve 8 is opened, and the adsorption column 2B is recovered. Since the adsorption tower 2B has previously completed the desorption and regeneration process and is in a reduced pressure state, there is no residual 0.0% from the two adsorption towers to the adsorption tower 2B. Transport of enriched air occurs naturally. This O,
By performing the gas recovery process efficiently, 0. Product yield can be increased.

(3) Desorption and regeneration process: This process is the process of desorption and regeneration of the adsorbent. When the two adsorption towers are in the adsorption process, the adsorption tower 2B is in the desorption and regeneration process, and conversely, when the adsorption tower 2B is in the adsorption process. Two adsorption tower workers are in the desorption and regeneration process. This desorption and regeneration step is performed in the O gas recovery step of item 12) above. This is carried out following the step in which enriched gas is discharged to another column. FIG. 5 shows that the adsorption tower 2B is in the relevant step.

The adsorption tower 2B is depressurized by the vacuum pump 4, so that the adsorbent gas adsorbed by the adsorbent in the adsorbent bed 3B is desorbed from the adsorbent and discharged to the outside of the tower through the switching valve 6B.

This gas is a gas rich in N, a component.

[Problem to be solved by the invention]

As mentioned above, 0. The gas recovery process has a major impact on the separation efficiency and the purity of the separated gas.

In other words, the purity is as high as possible and as much as possible. It is possible to collect and collect gas. Improved gas yield and 0
．． Necessary to maintain gas purity.

Generally, the amount of N adsorbed by the adsorbent is the amount of N adsorbed.

Proportional to the partial pressure of the gas. The closer to the air inlet side of the adsorbent in the adsorption tower, the more N and gas are adsorbed, and the closer to the gas outlet the less N and gas are adsorbed.

0.0 with the conventional method mentioned above. If gas recovery process is performed, 0
．． As the gas is transferred to another adsorption tower, the pressure inside the adsorption tower gradually decreases. That is, since the total pressure within the adsorption tower (mainly approximately equal to the sum of the N1 partial pressure and the false partial pressure) falls, the N1 partial pressure in each part also falls. In this case, for the reasons mentioned above, a large amount of N and gas (N and gas) are desorbed from the adsorbent near the air inlet side. This gas is Ot
Since the gas is mixed with the recovered gas, 0. This is a major cause of poor gas recovery efficiency.

In other words, the total pressure of the adsorbent bed where sufficient positive adsorption has been performed should be kept as low as possible to drop to 0! 0 on the exit side that contains a large amount of gas! Ideally, only the enriched gas should be recovered.

In addition, numerically speaking, when feed air is supplied from the supply pipe at the end of the vacuum desorption process, the total pressure is low, that is, N, the gas partial pressure is low and N is supplied, and the adsorption force is low, so N is supplied in a low order. , the gas flows to the outlet side in a short time, and the O2 purity can only be concentrated by 40 to 66%. In order to overcome this drawback, product O,
A method has been adopted in which a portion of the gas is refluxed to the adsorption tower in advance, but this leads to a decrease in the O2 yield.

In view of the above-mentioned state of the art, it is an object of the present invention to provide an adsorption/separation column for gas separation that can eliminate the problems in the prior art described above.

[Means to solve the problem]

The present invention provides an adsorption separation column for mixed gas separation that separates a mixed gas into a poorly adsorbable component gas and an easily adsorbable component gas by a pressure swing method using an adsorbent that preferentially adsorbs a specific component gas. This adsorption/separation tower for mixed gas separation is characterized in that the adsorbent bed of the adsorption/separation tower filled with an adsorbent is provided with a resistance plate having porous holes in a direction perpendicular to the gas flow direction.

In a preferred embodiment of the present invention, the resistance plate in the above-mentioned configuration of the present invention is moved from half of the height of the adsorbent packed in the adsorption tower (or the length of the adsorbent packed when the adsorption tower is oriented horizontally) to the position where the adsorption of the adsorbent bed is difficult. An example of this is to provide it on the exit side of the gas. The resistance plate may optionally have a single-layer structure or a multilayer structure, but it is preferable to use a resistance plate whose porosity is 10 to 50% of the cross-sectional area of the adsorption tower.

[Effect]

(1) By providing a porous resistance plate, 0. Ga;L
In the recovery process, the flow of gas from the adsorbent bed on the air inlet side, which has adsorbed a large amount of N and gas, is restricted by one resistance plate, so that, for example, the 0. Only component-rich gas can be efficiently recovered to other towers.

(2) Furthermore, the provision of this resistance plate is effective in improving performance during the adsorption process. That is, even during the adsorption process, the flow of feed air is also resisted, and for example, the total pressure at the bottom of the adsorption tower rises in a short period of time before reaching the top of the adsorption tower, so the above-mentioned drawbacks such as air blowing through the feed air also occur. It is multiplied by a large cloth.

〔Example〕

Hereinafter, one embodiment of the adsorption separation column for male separation of the present invention will be described with reference to FIG. In Fig. 1, 9 is an inlet pipe for a raw material gas, such as air, 10 is an adsorption tower main body, 11 is an adsorbent bed, and 12 is an outlet pipe for a poorly adsorbed gas, such as oxygen. It is the same as an adsorption tower. 13 is a porous resistance plate provided in a direction perpendicular to the gas flow direction, which is a feature of the present invention.

In this embodiment, a porous resistance plate 15 is provided on the adsorbent bed 11 in the upper part of the adsorption tower main body 10 in a direction perpendicular to the gas flow direction, and the adsorbent bed 11 is divided into a section A and a section B.

By providing this resistance plate 13, 0. Since resistance is provided to the gas flow flowing from part B to part A during the pulp collection process, pressure drop in part B is prevented, and the pressure drop in part B is prevented. Mixing of N from part B and desorption gas into the gas recovery gas is largely prevented.

(9) When the adsorption tower main body 10 is switched to the adsorption step after the vacuum desorption process is completed, the flow of raw material air is also resisted by this resistance plate, and the flow of the raw material air flows through the lower part of the adsorption tower main body 1o before reaching the upper part of the adsorption tower main body 10. Since the total pressure of the air rises in a short period of time, the phenomenon of blowing out all the feed air all at once does not occur.

0. Taking the gas production equipment as a representative example, Fig. 2 and Table 1 show the effects when the adsorption tower shown in Fig. 1 is adopted in the Of gas production equipment configured with the flow sheet shown in Fig. 3. .

The equipment conditions in this case are shown in Table 1, and the adsorbent used is 15X type zeolite MoV Cylinder Sieves manufactured by Conion Carbide Co., Ltd. of the United States.

Table 2 shows the piping connected to the switching valve 8 in FIG.
This is a measurement of the concentration of 0 flowing during the gas recovery process.

In Figure 2, a is the porosity of the perforated plate (the cross-sectional area of the column is 100
%) is 10%, b is SOX.

c Id is set to 40%, and d shows a conventional method without a perforated plate for comparison.

0. The gas recovery process is normally performed for 5 to 15 seconds, but the method using the device of the present invention has a lower O,
It is characterized by a small decrease in gas concentration.

Table 1 shows the operating performance in case b of Fig. 2 (when using a resistor plate with an aperture ratio of 30X). Open area ratio 50
By attaching a resistance plate of % to the adsorption tower, O! The gas production base has been increased from the conventional 9% m''/H to 12 Nm'/m3.
A major improvement of 0% or more is observed.

Furthermore, an improvement of 0.7m degree in the false gas recovery gas was observed, and the range of O gas concentration fluctuation was reduced from the conventional ±tO% (L2%).
It is recognized that the concentration of gas has been significantly reduced and that a very stable gas with a concentration of zero can be produced.

〔Effect of the invention〕

(1) Since the amount of easily adsorbed gases (eg, Nt) accompanying the recovery process of poorly adsorbed gases (for example, I/4 OS) is reduced, it is possible to efficiently recover the poorly adsorbed gases as a whole.

(2) The primary gas (eg, air) is prevented from suddenly blowing through the adsorption tower after vacuum desorption, and as a result, the purity of the adsorbent gas (eg, Ol) can be increased.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an adsorption tower according to one embodiment of the present invention, Fig. 2 is a diagram for explaining the present invention in detail, and Fig. 3 is a flowchart of a conventional PSA type gas separation device. It is.

Claims (1)

[Claims] In an adsorption separation column for mixed gas separation, which uses an adsorbent that preferentially adsorbs a specific component gas to separate a mixed gas into a poorly adsorbable component gas and an easily adsorbable component gas using a pressure swing method, adsorption 1. An adsorption separation tower for separating a mixed gas, characterized in that a resistance plate having porous holes in a direction perpendicular to a gas flow direction is provided on an adsorbent bed of the adsorption separation tower filled with an agent.