JPH0226609A - Production and device for highly pure oxygen by pressure swing adsorption process - Google Patents

Abstract

PURPOSE:To obtain a highly pure product O2 by supplying a raw gas composed of O2 and Ar into an adsorption tower to adsorb O2, next washing the adsorption tower with the product gas and then evacuating the adsorption tower to desorb and recover O2 as the product gas. CONSTITUTION:A mixed gas composed of O2 and Ar flowing out of the primary O2-PSA apparatus I is sent to the secondary O2-PSA apparatus II, O2 is adsorbed by synthetic zeolite etc., in the first adsorption tower 21 and Ar is discharged. In the meanwhile, a product gas is supplied from an O2 gas holder 6 to the third adsorption tower 23, wherein an adsorption process has been finished, to wash Ar out of the tower 23, and the second adsorption tower 22, wherein a washing process has been finished, is evacuated by a vacuum pump 50 to desorb and recover O2.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention utilizes a polar adsorbent such as synthetic zeolite to substantially absorb oxygen (02) and argon (Ar).
This invention relates to a pressure swing adsorption type high purity oxygen production method and apparatus for producing high purity 02 by separating 02 and A'' from a raw material gas consisting of

[Conventional technology]

Conventionally, the sixth method for separating and recovering 02 from raw air is
A pressure swing adsorption type 02 production apparatus as shown in the figure (hereinafter simply referred to as conventional 02-PSA apparatus).

) is known. This is Air Proa 11
Adsorption tower 2 filled with synthetic zeolite as an adsorbent through which raw material air under pressure is passed through raw material gas supply pipe 1a by a.
1a, 22a, and 23a, the adsorbent preferentially adsorbs N2 components in the raw air, and the remaining 02-rich gas is passed through the 02 recovery pipe 3a to the 02 receiver 4a.
During the adsorption/recovery step), the adsorbed N2 component is desorbed under reduced pressure by the vacuum pump 51a, and the desorbed gas is discharged through the desorption gas discharge pipe 5a.
After this, the 02 receiver 4
The 02 gas in a is introduced into the adsorption towers 21a, 22a, 23a through the pressure accumulating gas supply pipe 6a to increase the pressure (pressure accumulating step) and repeating the above adsorption step. That is, the 02 receiver 4a and the adsorption towers 21a, 22a, 23
The purity of 02 is gradually increased by repeatedly adsorbing and removing components other than 02 by circulating 02 gas between a and a. In addition, three adsorption towers 21a, 2
2a, 23a and each pipe line 1a, 3a, 5a.

By switching operation of switching valves (not shown) connected to 6a, each of the above steps of adsorption/recovery - desorption - pressure accumulation can be carried out in 3 steps.
The three adsorption towers 21a, 22a, and 23a are operated at the same time with one step at a time.
The two component gases are collected continuously.

[Problem to be solved by the invention]

Since Ar is not adsorbed by the adsorbent in the adsorption/recovery step of the conventional method, A remains as an impurity in the 02 gas. Therefore, even if the above steps are repeated in the conventional pressure swing adsorption method, There is a limit (for example, 93-95%) in improving the purity of product 02.
will contain at least 5% A.

Conventionally, as a method for separating Ar and 02 to produce highly pure 02, a cryogenic separation method is generally known in which Ar is cooled to the liquefaction point and separated using the difference in boiling point. However, this method has the disadvantage that the equipment becomes complicated and large because it requires cooling to the liquefaction point.

Therefore, there is a demand for the development of a method and apparatus for producing a product 02 with even higher purity by removing Ar using a pressure swing adsorption method that can reduce the size of equipment.

This invention was made in order to solve such conventional problems, and it is a pressure swing adsorption method for producing high purity 02 that can recover product 02 of higher purity than before by using the pressure swing adsorption method. and equipment.

[Means to solve the problem]

In order to achieve the above object, in claim 1 of the present invention, a pressure swing adsorption tower is filled with a polar adsorbent, and the pressure swing adsorption tower is used to recover oxygen from a raw material gas mainly consisting of oxygen and argon. A pressure swing adsorption method for producing high-purity oxygen, which comprises an adsorption step of supplying the raw material gas to the adsorption tower and adsorbing the 02 component to the adsorbent and discharging the argon component, and an adsorption step after this adsorption step. a cleaning step of supplying a product gas to the tower and discharging the remaining argon component with the product gas;
The present invention is configured to include a desorption step in which oxygen components are desorbed under reduced pressure from the adsorbent after this washing step.

Further, in claim 3 of the present invention, as an apparatus for implementing the method of claim 1, a pressure swing adsorption tower is filled with a polar adsorbent, and this pressure swing adsorption tower is used to mainly absorb oxygen and argon. This is a pressure swing adsorption type high-purity oxygen production device that recovers oxygen from a raw material gas consisting of a raw material gas supply pipe, an exhaust gas discharge pipe, a cleaning gas supply pipe, and a desorption gas recovery pipe. One end was connected to the adsorption tower, and the other ends of the desorption gas recovery pipe and cleaning gas supply pipe were connected to a product oxygen holder containing high-purity oxygen.

[Effect]

According to the above configuration, substantially 02 and A
By bringing a mixed gas consisting of Polarization exists, and as a result, 02 is attracted to the polar adsorbent, and as a result, 02 is adsorbed to the adsorbent.On the other hand, since Ar molecules are monoatomic molecules, they can be approximately treated as hard spheres. Since it is thought that there is no polarization like in an electric quadrupole, no attractive force is generated between Ar molecules and the adsorbent, and therefore Ar passes through the adsorption tower without being adsorbed by the adsorbent. I will do it.

In the cleaning process, A remaining on the surface of the adsorbent is replaced and desorbed by 02 in the high-purity product gas supplied as cleaning gas, so the purity of 02 desorbed and recovered after this is higher than that of the raw material gas. ``The higher the purity is, the more that is removed.

(Example) FIG. 1 shows an apparatus for producing high purity product 02 gas from air. This device is a primary pressure swing type oxygen production device (hereinafter simply referred to as the primary 02-PSA device) I that uses air as a raw material to produce a primary product 02 gas having a predetermined 02 purity (for example, 95%). A secondary pressure swing adsorption type oxygen production device (hereinafter simply referred to as "secondary pressure swing adsorption oxygen production equipment") which separates and removes Ar from the primary product 02 gas to produce a secondary product 02 gas with even higher purity (for example, 96 to 99%) (referred to as the secondary 02-PSA device).

The first 02-PSA equipment engineering was performed using the conventional 02-PSA equipment shown in Figure 6.
The same configuration as the PSA device is used, and this first
The method for producing the primary product 02 gas using the 2-PSAI device I is also produced by applying the conventional method. This 1st 02-P
SA ffT 02 holder 7a and 2nd 02-PSA
The raw material gas blower 10 of the device (1) is connected, whereby the primary product 02 gas (02:95%, A':5%) is supplied to the second 02-PSAVR device I as the raw material 02 gas.

The second 02-PSA device ■ consists of three adsorption towers 21.22
．． 23, the raw material gas supply pipe 1 that connects the raw material gas blower 10, the connecting pipe 31.32° 33 that connects the three adsorption towers 21.22.23, and the adsorption tower 21.22.
．． 23 to A "exhaust gas discharge pipe 4 for discharging exhaust gas,
A desorption gas recovery pipe 5 for desorbing and recovering 02 adsorbed in the adsorption towers 21, 22, and 23 to the secondary product 02 gas holder 6 via the vacuum pump 50, the secondary product 02 gas holder 6, and the adsorption tower. 21, 22, and 23.

Each adsorption tower 21, 22, 23 is filled with a polar adsorbent (for example, synthetic zeolite) to a predetermined height relative to the adsorption tower with a cross-sectional area A (foot).

Then, the raw material 02 gas is distributed to this adsorbent based on the above-mentioned cross-sectional area A (foot) and velocity V (1 t/see).
A predetermined superficial velocity U (77L/5(
IC).

Next, the primary product 02 gas is used as the raw material 02 gas to produce the second product.
The process of producing the next product 02 gas is carried out using the equipment shown in Figure 1 and the second product.
The first adsorption tower 21 will be mainly explained based on the process explanatory diagram in the figure and the explanatory diagram for each stage in FIG. The valve 11 is opened to supply the first 02-PS to the first adsorption tower 21, which has been depressurized to approximately 100 Torr by the desorption process in the previous step.
The raw material 02 gas from the A device I is supplied through the raw material gas supply pipe 1 at the above-mentioned predetermined superficial velocity U, thereby raising the pressure to approximately atmospheric pressure (760 Torr). Next, valve 41
△" which remains without being adsorbed in the first absorption tower 21
Ar wanders as r-rich exhaust gas through the exhaust pipe 4.
02 in the raw material 02 gas is introduced into the exhaust gas holder 8.
Following the pressure increase, the components are adsorbed onto the adsorbent (pressure increase/adsorption step). During this time, the second adsorption tower 22 is in a desorption process, and the third adsorption tower 23 is in a rest process.

After that, the valve 11 is closed, and the valve 331 and the valve 41 are closed.
The outlet gas from the third adsorption tower 23 in the cleaning process is introduced into the first adsorption tower 21 through the connecting pipe 33, and the 02 component contained in the outlet gas is transferred to the first adsorption tower 21. The remaining gas is adsorbed onto an adsorbent and recovered, and the remaining gas is introduced into the exhaust gas holder 8 through the exhaust gas discharge pipe 4 (recovery process). During this time, the second adsorption tower 22 is continuously in the desorption process.

In these steps, the 02 component contained in the raw material gas and the outlet gas is adsorbed by the adsorbent, and the Ar component is discharged from the exhaust gas discharge pipe 4 without being adsorbed, and the
A very small amount of AI' component remains on the surface of the adsorbent. This is due to the action of Haggi. That is, since 02 is a diatomic molecule, there is polarization similar to an electric quadruple cell, and therefore it attracts a polar adsorbent, and as a result, 02 is adsorbed by the adsorbent. On the other hand, A: Molecules can be approximately treated as rigid spheres, and polarization as in an electric quadruple tank does not exist. is not generated, and therefore A' passes through without being adsorbed by the adsorbent.

Therefore, in order to efficiently separate 02 and A' in the raw material 02 gas, the superficial velocity U is made relatively small and the apparent contact time between the raw material 02 gas and the adsorbent is lengthened. It is desirable to have as much 02 as possible adsorbed on the adsorbent.In this case, even if the contact time between the raw material 02 gas and the adsorbent is relatively long, the amount of A co-adsorbed on the adsorbent is small; The adsorption does not proceed and remains on the surface of the adsorbent.

Next, by opening the valves 331 and 41, the recovery process is completed and a rest process is entered. During this time, the second absorption tower 22 is in the pressure increasing/adsorption step, and the third absorption tower 23 is in the desorption step.

After the above-mentioned suspension process, the valve 62, the valve 71, the valve 311, and the valve 42
By opening the first adsorption tower 21, the first adsorption tower 21 enters a cleaning process.

As a result, the secondary product O2 gas in the secondary product 02 gas holder 6 is introduced as a cleaning gas into the first adsorption tower 21 through the cleaning gas supply pipe 7, and this cleaning gas is applied to the surface of the adsorbent. A trace amount of co-adsorbed A is desorbed by substitution with 02 in the cleaning gas. The outlet gas containing this A is supplied to the second adsorption tower 22 through the connecting pipe 31, and the second adsorption tower At step 22, the 02 component in the outlet gas is recovered, and the remaining gas is passed through the exhaust gas discharge pipe 4 to Ar
It is introduced into the Ar exhaust gas holder 8 as rich exhaust gas.

Note that the above adsorption step and washing step are carried out at atmospheric pressure (760T
orr) slightly higher pressure (e.g. 0°1-0.2
It is performed under N9/caiG level).

Next, close the valves 62.71, 311.42, and close the valve 51.
By opening the valve 61 and operating the vacuum pump 50, the first adsorption tower 21 enters the desorption process. As a result, the 02 component adsorbed on the adsorbent is desorbed and pressure is accumulated in the secondary product 02 gas holder 6. As a result, the primary product 02 is placed in the secondary product 02 gas holder 6.
A secondary product 02 gas of high purity (for example, 96 to 99.5%) whose 02 purity is improved by the amount of Ar removed from the gas is accumulated. In this case, the second adsorption tower 22 is in the cleaning process, and the third adsorption tower 23 is in the recovery process.

After this, the pressure increase/adsorption step is repeated again.

These steps are repeated in other second adsorption towers and third adsorption towers with the steps shifted from each other as shown in FIG.
Two gases are continuously desorbed and recovered.

Superficial velocity U of raw material 02 gas supplied in the above method
is set based on the relational expression shown below.

That is, the filling length of the adsorbent (length of the door) and the superficial velocity Ll
(m/sec) and T-L/U may be determined so that the value of the average contact time T (sec) is relatively large. Here, the filling length is the contact length between the raw material 02 gas supplied by the raw material gas blower 10 and the adsorbent, and in the above embodiment, one adsorption tower 21, 22, 23 is filled. This corresponds to the filling height Ω of the adsorbent. However, the larger the filling height of the adsorbent, the larger the equipment, which increases the construction cost of this equipment. Adjust the value of U. In addition, in order to make the adsorption tower relatively small, the raw material 02 gas in the pressurization and adsorption process is adsorbed in multiple adsorption towers so that a predetermined filling length is achieved with the adsorbent of multiple adsorption towers instead of one adsorption tower. May be supplied to the tower.

The relationship between the average contact time T and the O2 purity of the secondary product O2 gas is shown in FIG. This is an adsorption tower (diameter 8
Synthetic zeolite type 5A was packed at 8.5/(y) per column in 0M x height 2500 m, and 0 as raw material 02 gas.
The primary product 02 gas having a composition of 95% 2 and approximately 5% Ar is supplied to the adsorption tower 21°22.23, and by varying the superficial velocity U of this raw material 02 gas, the average The 02 purity of the secondary product 02 gas obtained by supplying the gas while varying the contact time T was measured.

According to this, when the average contact time T is approximately 100 seconds, 0
2 purity is 96%, similarly 97% at about 180 seconds, 98% at about 280 seconds, and 99% at about 400 seconds. Therefore, for example, in order to produce a secondary product gas as an 02 gas for fusing that requires an 02 purity of 97% or more, the superficial velocity U may be set so that the average contact time T is 180 seconds or more.

In addition, in the primary product 02 gas, which is the raw material 02 gas in the above example, except for 95% of 02, the remaining 5% is essentially Ar, but a very small amount of N2 (nitrogen) is present. It may be included. In this case as well, high purity secondary product 02 gas can be produced as in the above embodiment.

In addition, in the above embodiment, the first 02-PSA device 2
Although a device in which the following 02-PSA device (■) and the above-mentioned second 02-PSA device (■) are connected to each other is shown, the device is not limited to this. By separating and removing A from this raw material 02 gas, it is also possible to produce a product O2 gas with a higher 02 purity than that of the raw material 02 gas.In addition, in the above example, the raw material 02 gas, cleaning gas, etc. Adsorption tower 21.
22. The configuration is such that the gas is supplied from the lower end of 23 and flows upward in the adsorption tower, but this is not the only option. It may also be configured with an adsorption tower.

Furthermore, in the above embodiment, the adsorption tower 2 is
1.22.23 The raw material 02 gas is supplied until the pressure in the secondary product 02 gas holder 6 reaches almost atmospheric pressure.For example, as shown in Fig. The pressure of the secondary product 02 gas may be increased by supplying it to the adsorption tower, and then the adsorption step may be performed by supplying the raw material 02 gas.

That is, in FIG. 5, the first adsorption tower 21 is in a state where the pressure has been reduced to approximately 1QQTorr by the desorption step in the previous step.
, the valve 62 and the valve 71 are opened to supply the secondary product O2 gas from the secondary product 02 gas holder 6 to the cleaning gas supply pipe 7.
, and the inside of the first adsorption tower 21 is brought to approximately atmospheric pressure (76
The pressure is increased to 0 Torr (pressure increase step). After this, the valves 62 and 71 are closed, the valves 11 and 41 are opened, and the raw material gas blower 10 is operated to perform the first 02-PSA.
By supplying the raw material 02 gas for the apparatus through the raw material gas supply pipe 1 at the predetermined superficial velocity U, the 02 component in this raw material 02 gas is adsorbed by the adsorbent (adsorption step). Between the pressure increasing step and the adsorption step, the second adsorption tower 22 is in the desorption step, and the third step is in the rest step.

By doing this, at the start of the adsorption process, the inside of the adsorption tower is already filled with high-purity secondary product O2 gas, and from this state, adsorption, recovery, washing, etc. are performed and desorption is performed. Finally obtained secondary product 02
The purity achieved by the gas can be higher than that in the case where the pressure inside the adsorption tower is increased using the raw material 02 gas.

〔Concrete example〕

The first 02-PSA device shown in FIG.
The next product 02 gas (a gas with a composition of 95% 02 and approximately 5% A) is used as the raw material 02 gas, and this raw material 0
Based on the above example in which the adsorption tower is pressurized after the desorption step using two gases, the supply pressure is 200 AQ, and the desorption pressure is 10 AQ.
0-150T.

The raw material 02 gas was supplied at a rate of 2ON1 t/h to an adsorption tower of φ850 x 3000 so that the average contact time T was 300 seconds.

As a result, the purity of 02 was 98%, and the second
The next product 02 gas could be recovered.

In addition, the primary product 02 gas having the same composition as the above specific example is used as the raw material 02 gas, the supply pressure and the desorption pressure are the same as in the above specific example, and the above raw material 02 gas is supplied at a supply rate of 2ON1 t/h. Adsorption was carried out in an adsorption tower such that the average contact time T was 400 seconds.

As a result, 16 Nd/h of secondary product 02 gas with 02 purity of 99% could be recovered.

〔Effect of the invention〕

According to the pressure swing adsorption type high purity oxygen production method and apparatus of the present invention, a mixed gas consisting essentially of 02 and Ar is brought into contact with the polar adsorbent in the pressure swing adsorption tower. 02 with polarity by
is attracted to the adsorbent, so it is adsorbed, and A' passes through without being adsorbed. In the cleaning process, A' remaining on the surface of the adsorbent is replaced and desorbed by 02 in the cleaning gas, so it is adsorbed after this. By desorbing and recovering the 02, it is possible to obtain a product 02 gas with a purity equivalent to the amount of Ar removed from the raw material 02 gas.Therefore, the pressure swing adsorption method can produce a product 02 with higher purity than before. can do.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of the apparatus of the present invention, FIG. 2 is an explanatory diagram of the process of each adsorption tower of the apparatus of FIG. 1, and FIG.
An explanatory diagram of each process of the adsorption tower, Figure 4 shows the average contact time ■ and 0
Fig. 5 is a diagram corresponding to Fig. 3 showing another example of the pressurization/adsorption process in Fig. 2, and Fig. 6 is a diagram of the conventional 02-PS.
It is an explanatory view showing A device. 1... Raw material gas supply pipe line, 4... Exhaust gas discharge pipe line,
5...Desorption gas recovery pipe, 6...Secondary product 02 gas holder<m product gas holder), 7...Cleaning gas supply pipe, 21.22.23...Adsorption tower, 31.32
．． 33...Connection pipe.

Claims (1)

[Claims] 1. A pressure swing adsorption type high-purity system in which a pressure swing adsorption tower is filled with a polar adsorbent and the pressure swing adsorption tower is used to recover oxygen from a raw material gas mainly consisting of oxygen and argon. The method for producing oxygen includes an adsorption step of supplying raw material gas to the adsorption tower to adsorb the O_2 component to the adsorbent and exhausting the argon component, and supplying the product gas to the adsorption tower after this adsorption step. A pressure swing adsorption type high-pressure absorber characterized by having a cleaning step in which residual argon components are discharged using the product gas, and a desorption step in which oxygen components are desorbed under reduced pressure from the adsorbent after this cleaning step. Purity oxygen production method. 2. The pressure swing adsorption type according to claim 1, wherein in the adsorption step, the product gas is supplied into the adsorption tower in a reduced pressure state to increase the pressure inside the adsorption tower, and then the raw material gas is supplied. High purity oxygen production method. 3. A pressure swing adsorption type high purity oxygen production device in which a pressure swing adsorption tower is filled with a polar adsorbent, and the pressure swing adsorption tower is used to recover oxygen from a raw material gas mainly consisting of oxygen and argon. , one ends of the raw material gas supply pipe, the exhaust gas discharge pipe, the cleaning gas supply pipe, and the desorption gas recovery pipe are connected to the adsorption tower, and the desorption gas collection pipe and the cleaning gas supply pipe are connected to the adsorption tower. A pressure swing adsorption type high-purity oxygen production device, characterized in that the other end of the line is connected to a product oxygen holder containing high-purity oxygen. 4. The pressure swing adsorption type high-purity oxygen production apparatus according to claim 3, characterized in that it is constituted by a plurality of adsorption towers, and these adsorption towers are connected to each other by connecting pipes.