JP3347373B2 - High purity oxygen production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing high-purity oxygen, and more particularly to a PSA method (Pressure Swi
ng Adsorption Process: A PSA device that uses adsorbed gas as a product and a P that uses non-adsorbed gas as a product using a gas adsorption separation method based on pressure fluctuation adsorption or pressure swing adsorption.
Purity 9 from air with simple configuration combined with SA device
The present invention relates to a method for producing high-purity oxygen of 9.5% or more.

[0002]

_2. Description of the Related Art Conventionally, distillation methods (cryogenic separation method, hereinafter abbreviated as cryogenic method), as methods for producing oxygen (abbreviated as O ₂ ),
An air separation method such as an adsorption method (a typical example is a PSA method) and a membrane separation method. The cryogenic method uses high-purity O ₂
(99.5% or more) and high-purity nitrogen (abbreviated as N ₂ ) (9
(9.99% or more) that can be co-produced, which is a feature not found in the other two methods, but among the above three methods, the system is the most complicated and the miniaturization is difficult, and it is economically feasible unless it is a large-scale production There is a drawback that you can not. The membrane separation method is configured but is simple, the product purity is lower than the 30 to 40% O ₂ and the other two methods. In contrast, the PSA method has a simple structure and is suitable for small-scale production, but the obtained product purity is only 95%, which is lower than that of the cryogenic method. This is an N ₂ adsorbent commonly used for O ₂ production by the PSA method [eg, MS-5A
(Molecular Sieve 5A)] In the O ₂ and Ar (argon)
Is not possible. O ₂ for MS-5A
And Ar exhibit the same behavior, and O ₂ and Ar are concentrated in the product while maintaining the abundance ratio in air (21: 1). That is, when O ₂ is concentrated from 21% to 94%, Ar is also concentrated from 1% to 1 × 94/21 = 4.5%. PSA
Substantially O ₂ also actual measurements of product purity obtained by law 9
4%, Ar is 4.5%, and the remaining (N ₂ ) is 1.5%. On the other hand, the purity of O ₂ supplied in cylinders and small liquid containers for small-lot applications is 99.5% or more, but it is heavy and difficult to move, and it is dangerous because it is a high-pressure gas. And there are drawbacks such as inconvenient replenishment and troublesome management. Therefore, there is a strong demand for a method of producing 99.5% or more of O ₂ by a simple apparatus using the PSA method.

Various systems have been applied for patents for the conventional high-purity O ₂ production method by the PSA method, but in principle the system 1 (S1) or the system 2 shown in FIG.
(S2). S1 is air → D [air drying device (filled with moisture adsorbent, activated alumina etc.)] → C [O ₂
Adsorption device (MSC filling) (Molecular Sieving Carbon)
→ 70% or more of O ₂ → A [N ₂ adsorption device (MS-5A,
MS-13X (Molecular Sieve 13X) etc.) → 9
This is a system for producing 9.5% or more of O ₂ . S2 is air → A [N ₂ adsorber (MS-5A, MS-13X, etc.)] → 90% or more O ₂ → C [O ₂ adsorber (MS
C filling)] → This is a system for producing 99.5% or more of O ₂ . FIG. 2 shows an example of a high-purity O ₂ production system constituent unit by the conventional PSA method combining D and A (see Japanese Patent Application Laid-Open No. 3-52615 by the present inventor). Examples of high-purity O ₂ production system configuration unit according to the conventional PSA process using a C in FIG. 3 (JP-A-4-2 by the inventors
No. 60416).

When the S1 system is constructed by combining the units shown in FIGS. 2 and 3, five adsorption towers, three pumps,
Reservoir [intermediate and final products (99.5% O
₂ ) For storage] has three towers, many parts and valves, a complicated system, large equipment, and very troublesome operation and maintenance. Both equipment cost reduction and energy cost reduction It is necessary to make a remarkable improvement.

[0005] Using the structural unit shown in FIG.
An example of producing O ₂ by adsorbing and removing ₂ will be described.
1 ^' to 10 ^' : Automatic valve (valve 9 ^' , valve 10 ^' is pump P ^'
Is used only when pressure and vacuum are used together), P ^' : pump, 1
2 ^′ (C-1) and 13 ^′ (C-2): Adsorption towers, filled with silica gel, activated alumina, etc. in the case of air drying,
For the purpose of producing O ₂ , MS-5A,
Fill with MS-13X or the like. 14 ^' : source gas supply line, 15 ^' : product gas sampling line.

[0006] The O ₂ concentration operation is divided into the following four steps. Feed air pressurization - Product O ₂ extraction - vacuum (to atmospheric pressure or vacuum pressure) - Purge ... returns to again. Hereinafter, the steps will be described in order. Source air pressurization The source air (14 ^' ) is sent under pressure to the lower part of the adsorption tower (C-1) via a pump (P ^' ) and a valve (1 ^' ). The adsorption tower (C-1) is filled with activated alumina (for removing moisture in the air) and MS-5A (for adsorbing N ₂ ) in layers. The moisture in the air is first removed by the activated alumina layer at the C-1 inlet end, and the dried air is deposited on the upper layer (the adsorbent layer height of 7).
(To 90%) of the MS-5A layer. So N in the air
₂ is adsorbed. At this time, an N ₂ adsorption band is formed below the MS-5A layer, and the adsorption band expands forward as the supply of the source gas continues. At the same time, the gas reduced by N ₂ (concentrated O
₂ ) is pushed toward the outlet end of the adsorption tower (C-1).

Removal of product O ₂ (C-1) The pressure in the adsorption tower is a predetermined pressure (for example, 1.0 to 3.0).
When the pressure reaches kg / cm ² G), the valve (2 ^′ ) is opened, and the concentrated O ₂ is discharged to the product gas line (15 ^′ ). The product O ₂ is taken out during or immediately after the supply of the raw material air. Close the pressure reducing valve (1 ^' ) and the valve (2 ^' ) and open the valve (4 ^' ) (simultaneously, the valve (5 ^' ) is opened, and (C-2) pressurization of the raw material air in the adsorption tower is started. ]. (C-1) The gas in the adsorption tower is supplied to the atmospheric release line (16 ^' ) via the valve (4 ^' ). As shown by a dotted line in FIG. 2, a-b may be connected, and the pressure may be reduced by a pump (P ^' ) to promote desorption. In this case, a valve (9 ^' ) and a valve (10 ^' ) are required. (C-
1) N ₂ adsorbed due to atmospheric release of adsorption tower gas
There disengaged portion, but is discarded from the line (16 ^') into the atmosphere, yet unnecessary components substantial amount (H ₂ O, N ₂₎ is (C-
1) It remains in the adsorption tower. The following purge operation is performed to release the residual gas (mostly the adsorbed gas).

[0008] Due to the purging operation, the adsorption tower (C-1) is under atmospheric pressure. Supplied by opening the valve (7 ^') part of (C-2) the product gas of the adsorption tower (concentration O ₂₎ to (C-1) adsorption tower top (outlet end). (C-1) product gas supplied to the adsorption tower top (C-1) adsorbed N ₂ desorbed during flowing through the adsorption column in the counter current direction, the N ₂ is the valve with the product gas stream (4 ^' ) To the atmosphere. When the purging is completed, the supply of the raw material air is started again. The above operations are performed at regular intervals [1 cycle time, T
(Seconds)]. (C-1) When the adsorption tower is in the adsorption process [+] (C-2) The adsorption tower is in the regeneration process [+]
And (C-2) the adsorption tower is in the adsorption process [+], and the (C-1) adsorption tower is in the regeneration process [+]. Thus, any one of the towers is constantly in a pressurized and product-removable state.

An example in which O ₂ is produced from dry air using the constituent unit (device using adsorbed gas) of FIG. 3 will be described. 1 ^{"to 7"} in Figure 3: Automatic valve, 8 ^": the needle valve (flow-rate adjustment), ^P": pump (pressure - vacuum combination type), 12 ^": selective adsorption the adsorption column [target gas O ₂ Sorbent, ie, MSC.
There are two cases : C (a1) alone [FIG. 3 (a)] and a case where a drying agent (b1) such as activated alumina and MSC (b2) are filled in layers (FIG. 3 (b)) . Normally, FIG. 3B is used when the raw material gas is air, and FIG. 3A is used when the raw material gas is dry air or concentrated oxygen (90 to 95%). ], 13 ^": product reservoir (flexible container is preferred), ^14": feed introduction line, 15 ^": waste gas line (N ₂ rich gas), ^16": product line 1
7 ″: Pressure release line.

The steps of the unit shown in FIG. 3 are divided into the following four steps. Feeding of raw air (pressurized), cocurrent discharge, recycling of product gas, and recovery of product gas (O ₂ ). Feeding of raw material air [when using FIG. 3 (a)] Dry air is fed from the air introduction line (14 ^" ), and the valve (6)
^") Through a pump ^(P" sent to), the pump (P ^') is pressurized, the valve (1 ^"" to fed to the lower portion of) (at this time valve 2 ^"adsorption tower (12 through) to ^5", 7 ^" Is closed). Feeding tower (12 ^') with inlet continue the pressure increases. O ₂ in the air is adsorbed from the lower end portion of the adsorbent (a1), the adsorption zone is formed. As a band gradually expanded to the outlet end.

The pressure inside the co-current discharge adsorption tower (12 ^" ) is a predetermined pressure (for example, 0.5 to
When 3.0 kg / cm ² G) is reached, ^"opening the) valve ^(8" valve (2 ^"while adjusting the flow rate of the exhaust gas from), the adsorption tower ^(12" adsorption tower (12 by)) in The gas (unnecessary gas, N ₂ ) that has not been adsorbed is released to the atmosphere. Exhaust gas purity is initially N ₂ rich but gradually rich in O ₂ . The valve (6) is used when the nitrogen content in the exhaust gas approaches the N ₂ concentration in the air, or at an appropriate time during that time.
Open ^") closing the stops air introduction. Product gas recycle introduction valve ^(7"), product O ₂ in the reservoir (13 ^")
Gas (O ₂ gas collected in previous operation)
^The liquid is fed into the lower part of the adsorption tower (12 ^" ) via a ^" ) -pump (P ^" )-valve (1 ^" ). In this step, the adsorption tower (1
2 ^") gas and gas other than O ₂ attached to the surface of the adsorbent is between adsorbent particles in substituting the product concentration O _2. Adsorption tower (12 ^') the exhaust gas from the valve ^(2" ) —Discharged into the atmosphere via a needle valve (8 ^" ). When the O ₂ concentration in the exhaust gas becomes sufficiently high, the valve (7 ^" ), (1
^" ) And (2 ^" ) are closed.

The product (O ₂ ) gas recovery valve (3 ^″ ) and valve (5 ^″ ) are opened, and the adsorption tower (12 ^″ ) is evacuated to a pressure lower than the atmospheric pressure by the pump (P ^″ ), and the adsorbent ( a1) a O ₂ which has been adsorbed is desorbed, ^"collecting a). At this time, the adsorption tower ^(12" reservoir (13 pressure) inside is preferably below 200 mmHg (absolute pressure). The above steps (1) to (4) are defined as one cycle operation. FIG. 4 shows the open / close state (valve sequence) of each valve in the one-cycle operation. The hatched portion in FIG. 4 indicates the time during which the valve is open. One cycle time varies depending on the scale of the apparatus, adsorbent specifications, operating conditions, and the like, but is generally 30 to 120 seconds.

Using the structural unit shown in FIG. 3, O
_There are the following three cases of the raw material air in the case of producing 2. In the case where the air dried in advance as described above is used, the adsorption tower shown in FIG. 3A is used. The adsorption tower shown in FIG. 3B is used (in this case, it is necessary to add a desorption operation every cycle to prevent accumulation of water). In the case of using the O ₂ enriched in 90% to 95% may be either of the adsorption tower in FIGS. 3 (a) or FIG. 3 (b), the product gas of this case is more than 99.5% O ₂ can be obtained.

[0014]

When configuring the high-purity O ₂ production apparatus with the most simplified device unit in the prior art by the above-described PSA process [0006] it has the following problems. First, there is a problem in selecting the S1 system or the S2 system. If the S1 system is selected, 2 + 1 + 2 = 5 adsorption towers, 3 pumps, and a reservoir
The bar has three towers. When the S2 system is selected, the number of adsorption towers is 2 + 1 = 3, the number of pumps is two, and the number of reservoirs is two. The number of system elements in S1 may be smaller, but the S2 system has the following problems. There is. That is, the product O ₂
Is obtained in the vicinity of atmospheric pressure, a pump-up is required to send the product to the consumption end, and a product feed pump is required. Also, when the product feed pump is pumped up (pressurized), the high purity O ₂ may be contaminated, and the product is stored at atmospheric pressure, so that the contaminants (H ₂ O, N
₂ ) may enter, and because of the low storage pressure, there is a risk of outgassing contamination from the reservoir inner wall. Therefore,
The complexity of the configuration is not much different between the S1 system and the S2 system, and the S1 system is more preferable in terms of purity control.

However, when a high-purity O ₂ producing apparatus is constructed using the S1 system, there are the following problems. The device configuration becomes complicated, the device becomes large, and the device price increases.
That is, the most simplified DCA of the prior art 3
When two units are connected via a reservoir, the number of adsorption towers is 2 + 1 + 2 = 5, the number of reservoirs is 3, and the number of pumps is 3. Thus, the number of device elements is large, the number of manufacturing steps is large, and the price of the device is increased. In addition, the size of the adsorption tower and the specifications of the pump are varied and not compact, and there is a problem in terms of installation space. There is no rational exchange between the valuable gas (gas of O ₂ 21% or more or gas having pressure) generated from the second-stage device (C) and the third-stage device (A), and the individual gas is processed individually. Product acquisition rate is poor. Since the first to third stage devices are operated by independent valve sequences, the product gas of the preceding stage is stored in the reservoir, and the latter device uses the stored gas as a raw material. In this case, the yields of the _first and second stages are η ₁ , η
_If it is set to ₂ , the total yield η = η ₁ η ₂ and the three-stage treatment will further reduce the yield. Therefore, it is necessary to devise not only individual processing of valuable gas emitted from each stage apparatus but also the most rational processing of the whole system so as to prevent the effective component (O ₂ ) from being discharged outside the system as much as possible. .

Since the three devices are operated with their own valve sequences, the number of operations from the start of operation to the steady operation, or when the operation is stopped, is larger than when one device is operated. There is a problem in safety management. In order to make driving safe and smooth, use a large reservoir,
It is necessary to introduce high-grade control equipment, which also causes an increase in equipment price and a decrease in yield.

[0017]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in view of the above problems, and as a result, have found that the following problems can be solved to achieve the present invention. The drying device (D) and the oxygen adsorbing device (C) were combined and integrated in order to avoid the size increase, and the two reservoirs in the conventional system (one each after D and C) were unnecessary. D and C are combined into one valve sequence, and then in one cycle of this valve sequence, the valve sequence related to A (concentrated O ₂ 70-80% → 99.5% O ₂ or more high purity oxygen) ) Was interrupted. In this way, the entire apparatus is integrated into one system, and high-purity O ₂ can be stably produced with one valve sequence. By arranging the valve sequence of the entire system in a reasonable time, the valuable gases coming out of C and A are effectively used in the system, and depreciated before being taken out of the system. In general, the gas coming out of each device becomes higher in value as it goes to the later stage, so that the gas coming out of C is recycled to D and the gas coming out of A is recycled to C or D in principle. Basically, two pumps are used to smoothly implement the above-mentioned means to meet the demands of gas processing every moment.
Use two pumps individually, 2) use in series, or 3) use them in parallel, etc. [Use 3) when a flow rate is needed, 2) when a pressure difference is needed].

The invention of claim 1 of the present inventionOne tower each
Alternatively, the following first to third steps using two towers are performed in one cycle.
Using one device implemented by a dynamic valve opening and closing operation,Continuous
For producing high-purity oxygen from air in JapanAt Removes unnecessary components such as moisture, carbon dioxide and nitrogen in the air
The first step using an adsorbent that selectively adsorbs oxygen Process
The second step of concentrating the oxygen in the passed gas The above-mentioned step using an adsorbent for selectively adsorbing nitrogen Process
3rd process to make oxygen in passed gas high purityThis one device is connected to one valve sequence (valve opening time to
From the first step to the second and third steps
And implement it to be valuable as you go to the later stage, this valve
By performing rational time allocation of the sequence,
Unnecessary gas is recycled to the first step, and the third step is unnecessary
The gas is enriched with valuable components according to its purity classification.
And recycle the residue to the first process.
High purity oxygen production method.

According to a second aspect of the present invention, the one device is
Each of the adsorption towers performing the first to third steps is a reservoir.
One that is connected directly to the piping without using
2. The device according to claim 1, wherein the device is a simplified device.
This is the method .

[0020] The invention of claim 3 of the present invention is the above-mentioned one device.
The device is operated by a dedicated power.
Or a method according to claim 2 .

According to a fourth aspect of the present invention, the one device is
Only start and stop the operation of the
4. The method according to claim 1, wherein no member is required.
The method according to any one of the above .

According to a fifth aspect of the present invention, a start button is provided.
All automatic valves are set to cooperate instantly when pressed
The method according to any one of claims 1 to 4, wherein
This is the method described above.

[0023]

[Function] Reasonable ratio of 2 to 4 adsorption towers and O ₂ adsorption towers of almost the same specifications, _two N ₂ adsorption towers much smaller than that, and one O ₂ reservoir tower on one stand Since the three units of DCA are combined into one device system, the number of components of the device can be reduced, and the price of the device can be reduced. By using a pump or a differential pressure in the above one system, valuable gas in the system can be moved quickly and without gas loss in the shortest distance, and valuable gas loss is reduced as compared with the prior art.
The product acquisition rate could be improved. By operating one of the above systems with one valve sequence, the operation can be stopped with a single button, and since the reservoir is small and the piping distance is short, the rise time from the start of operation to the delivery of the product is shortened. When two pumps are used and the supply speed is increased, two pumps are used in parallel, and when it is desired to increase the differential pressure, two pumps are used in series. This made it possible to depressurize one column and pressurize the other column above atmospheric pressure. One O ₂ without reservoir
When the gas was transferred from the adsorption tower to another O ₂ adsorption tower and / or N adsorption tower , a sequential (sequential) concentration distribution was formed, and the mixture was allowed to move without being mixed with this distribution. As a result, valuable gas loss was reduced, and the product yield could be improved.

[0024]

EXAMPLES Hereinafter, the method for producing high-purity oxygen of the present invention will be described in detail with reference to examples, but the present invention is not limited to the examples without departing from the gist of the present invention. FIG. 5 is a diagram showing a basic configuration of an apparatus for carrying out the high-purity oxygen production method of the present invention. FIG. 6 shows a partial variant of the device of FIG. FIG. 7 shows a partial variant of the device of FIG. FIG. 8 shows the base of another high-purity oxygen production apparatus using the method of the present invention .
It is a figure showing this structure. FIG. 9 shows an example of a valve sequence in one cycle of the basic configuration of the device shown in FIG. FIG.
Shows an example of a valve sequence in one cycle of the basic configuration of the device shown in FIG.

Embodiment 1 Referring to FIG. 10 Drying tower [10A: activated alumina, 10B: MS-
5A] 20,21 O ₂ adsorption tower (20C, 21C: MSC) 30, 31 N ₂ adsorption tower (30A, 31A: MS-5)
A) 32 product oxygen reservoirs 2e, 2f: needle valves (flow control valves) 1 to 7, 1a to 4a, 1b to 4b, 1c to 4c, 1d to
4d Automatic valve P1, P2 Pump 13 Raw material air supply line 14 Waste gas line 15 Concentrated O ₂ supply line (to N ₂ adsorption tower) 16 Countercurrent depressurized gas line (from N ₂ adsorption tower) 17 Recycle supply line 10 Is a first-stage device (D), 20, 21 are second-stage devices (C), 30, 31 are third-stage devices (A), and these are one system through piping. The production of high-purity O ₂ is upgraded in the order of the first-stage device, the second-stage device, and the third-stage device, and finally becomes 99.5% or more O ₂ , which is stored in a product storage tank (32). From the consumer end.

The operation of separating high-purity O ₂ based on FIG. 5 will be described. First, (a) air is dried (first processing), and then the air is concentrated to concentrate O ₂ (70 to 80).
% O ₂ ) (secondary treatment). Then, (b) high-purity O ₂ (99.5% O ₂ or more) is produced from the concentrated O ₂ (third treatment).

Regarding (a): The process for producing concentrated O ₂ from the atmosphere (including moisture) comprises the following seven steps. Air drying (D), O ₂ adsorption (C), cocurrent discharge (1) (C),
Regeneration under reduced pressure (D), substitution of concentrated O ₂ (C → C), cocurrent discharge (2) (C → D), concentrated O ₂ (70-80% O ₂ )
₂ ) Recovery (C → A). Hereinafter, the adsorption tower (10) and the adsorption tower (2)
0) will be described. About air drying (0 to 30 seconds): The raw material air is introduced into the lower part of the air drying tower (10) through the valve (3), the pump (P1), the raw material introduction line (13), and the valve (1).
At this time, the valve (2) is closed. The pressure in the drying tower (10) rises, and the moisture in the air is adsorbed by the desiccant (10A) from the end of the inlet of the tower, and as the feeding of the raw air continues, the moisture adsorption zone expands upward. CO _{2 in} air with moisture removed
And N ₂ are removed while passing through the MS-5A layers of desiccant layer (10B), is forced gas consisted O ₂ concentration in air O ₂ rich into the drying tower (10) the outlet end under pressure .

Oxygen adsorption: When the pressure in the drying tower (10) reaches 1.0 to 3.0 kg / cm ² G, the valve (1a) attached to the O ₂ adsorption tower (20) of the second stage apparatus is opened. ,
The air after the pre-treatment is transferred under pressure to the O ₂ adsorption tower (20) (5 to 30 seconds). This air is the O ₂ adsorption tower (20)
O ₂ is MS in the air while moving the inner to the top in a pressurized state
The gas (unnecessary gas) adsorbed on C (20C) and reduced in O ₂ content is pushed to the outlet end of the tower.

Regarding the co-current discharge (1), the pressure in the O ₂ adsorption tower (20) is adjusted to a predetermined operating pressure (0.5 to 3.0 kg /
cm ² G), the valve (2a ′) is opened and the tower (2
0) Unnecessary gas is released into the atmosphere (20 to 30 seconds).
The release speed is adjusted by the needle valve (2e).

Regeneration under reduced pressure (30 to 55 seconds):
The valve (1) and the valve (1a) are closed immediately after the transfer of the secondary processing air to the secondary processing apparatus (O ₂ adsorption tower), and the valve (2)
Is released, and the drying tower (10) is regenerated under reduced pressure. Tower (1
Water and MS adsorbed on the desiccant (10A) in 0)
CO ₂ and N ₂ adsorbed on -5A (10B) are partially desorbed by decompression and released to the atmosphere via the valve (2).

Concentrated oxygen replacement (30-60 seconds) or recycle feeding: Next, the valve (3b) and the valve (4a) are opened, and the gas in the O ₂ adsorption tower (21) is pumped by the valve (3b) -pump. (P2) - valve (5) - pump (P1) - valve ended O ₂ adsorption tower of the transfer of the primary process air via (4a) (20)
MSC in O ₂ adsorption tower (20)
(20C) The gas between the adsorbent particles is replaced with concentrated oxygen.
At this time, the gas transferred from the tower (21) has an air composition (O ₂ = 21%) at the beginning of the operation, but the transfer progresses and gradually becomes an O ₂ rich gas as the decompression of the O ₂ adsorption tower (21) progresses. (The O ₂ concentration of the transfer gas becomes 70 to 80% throughout the entire transfer period and stabilizes as the operation continues.)
The maximum pressure in this step is preferably set to a pressure of 0.5 to 3.0 kg / cm ² G. In this step, the gas between the adsorbent particles and the gas adsorbed on the adsorbent surface other than the concentrated O ₂ are washed out with the replacement gas.

Regarding cocurrent discharge (2) (30 to 60 seconds): Valve (2) almost simultaneously with or slightly after the start of the process
a) is opened, and unnecessary gas in the adsorption tower (20) is released from the valve (2a).
And is fed countercurrently to the upper part of the drying tower (10). O ₂
The gas leaving the upper part of the adsorption tower (20) is a highly dry gas. Therefore, while flowing in the counterflow direction in the drying tower (10), the desorption of the gas adsorbed and remaining in the tower (10) is promoted, and the gas is purged (washed out) from the valve (2) into the atmosphere [drying tower (10)]. Play]. Since the gas discharged from the upper part of the O ₂ adsorption tower (20) is a gas rich in valuable components (O ₂ ), the valve (2) is closed at the end of this operation, especially in the part enriched in O _2, and the gas in the tower (10) is closed. In the next cycle,
O ₂ adsorption tower (20) or O ₂
It is preferable to recycle to the adsorption tower (21). At the end of the operation, the valve (2b ') is opened and the tower (20) is opened.
An operation of equalizing and collecting the internal gas to the tower (21) (or in the opposite direction) may be added.

Concentrated oxygen recovery (also included in the fifth step (90 to 120 seconds) of the O ₂ adsorption tower (21)): When the concentrated O ₂ replacement of the O ₂ adsorption tower (20) is completed, a valve ( 3a), and opening the valve (4b), the valve (3a) - pump (P2) - valve (5) - pump (P1) - through valve (4b), and countercurrent depressurization of the O ₂ adsorption tower (20) O ₂ adsorption tower (2
1) Co-current pressurization is performed. [A certain amount of the initial decompressed gas is supplied as a raw material gas of the third-stage apparatus via a valve (1C) (90 to 100 seconds), and the remaining part is an O ₂ adsorption tower ( 21)
To the process as a replacement gas. At this time, it is preferable that the pressure in the O ₂ adsorption tower (20) is as low as possible, but generally, the pressure may be 200 mmHg (absolute pressure) or less.

The above steps (1) to (4) are performed in one cycle (T,
Seconds). O ₂ adsorption tower (20) and O _{2 in} one cycle time
Seven operations of the adsorption tower (21) are performed. The same seven-step operation is performed in the O ₂ adsorption tower (21) with a delay of T / 2 seconds from the O ₂ adsorption tower (20). FIG. 9 shows the open / closed state of the valve in the one-cycle operation. In FIG. 9, the hatched portion indicates the time during which the valve is open. The time required for one cycle varies depending on the device specifications, adsorbent, and operating conditions, but is generally 30 to 240 seconds.

Regarding (b): concentrated O ₂ (70-80%
The third treatment for producing high-purity O ₂ (99.5% O ₂ or more) using O ₂ ) is performed by alternately using the N ₂ adsorption tower (30) and the N ₂ adsorption tower (31). It is performed in the process. Concentrated O ₂ supply (secondary processing gas), high-purity O ₂ extraction (purge provision), reduced pressure (up to atmospheric pressure or vacuum evacuation; described below in “evacuation”), purge / re-addition Pressure.
The following description focuses on the adsorption tower (30).

Concentrated O ₂ supply (90 to 100 seconds): The secondary treatment replacement gas is transferred to the O ₂ adsorption tower (21) → pump (P2) and pump (P1) → O ₂ adsorption tower (20). At the time [or at the time of transfer from the tower (20) → the pump → the tower (21)], a part thereof is passed through the valve (7) → the valve (1c) to be N
( ₂ ) Pressure feed to the lower end of the adsorption tower (30). Secondary processing gas N ₂ adsorbents MS-5A of (concentration O ₂₎ in (30A)
And an N ₂ adsorption band is formed at the inlet end, and expands to the outlet end together with the feed of the raw material gas.

Removal of high-purity O ₂ (100 to 120 seconds,
0-9 sec) for: a valve (7), close the valve (1c), to open the valve (2c), N ₂ purity O from the adsorption tower (30)
₂ is taken out through the valve (2c) and the valve (2f) and sent to the product storage tank (32). From there it is sent to the consumer.
The take-out speed is controlled by adjusting the opening of the needle valve (2f) [following the end of this operation, the valve (4c) is operated for a short time (5 to 10).
Sec), a part of the product gas is supplied as a purge gas to the outlet end of the N ₂ adsorption tower (31) under the following step (vacuum)].

Regarding the pressure reduction (35 to 40, 60 to 70 seconds): When the first step is completed, the valve (2c) is closed and the valve (3) is closed.
c) is opened, and the pressure in the N ₂ adsorption tower (30) is reduced via the valve (3c) → the pump (P2) → the pump (P1). A part of the decompressed gas is recirculated and supplied to the tower (30) → the tower (31) [shown as (3-1) in FIG. 9], and the rest is opened by opening the valve (1) of the first-stage apparatus. 10) Recycle supply [shown as (3-2) in FIG. 9].

About the purge (purge: 69 to 70 seconds, re-pressurization: 70 to 90 seconds): At the end of the first step, the column (3
1) Open the valve (4d) (under pressure) for a short time and supply part of the product gas to the outlet end of the column (30). This high-purity O ₂ promotes the desorption of N ₂ remaining in the adsorbent (30A) in the tower (30), and together with the desorbed N ₂ , passes through the valve 3c → pump (P2) → pump (P1) to the tower (10). Recycle supply to Thereafter, the valve (3c) is closed, and the tower (30) is counter-pressurized.

The above-mentioned steps are operated in one cycle (T seconds)
And While four steps are being performed in tower (30), tower (3)
In 1), the same operation is performed after T / 2 seconds.

FIG. 9 shows the valve open time (valve sequence) in one cycle time of the tower (30) and the tower (31). In FIG. 9, (A) to (F) show aspects of using the pump.
(A), (C), (D), and (F) show serial use, and (B) and (E) show parallel use time segments.

Referring to FIGS. 6 and 7, which show a partially modified embodiment of the apparatus having the basic structure shown in FIG. 5, FIG. 5 shows a case where the first processing is performed in one tower and the second processing and the tertiary processing are performed in two towers. FIG. 6 shows a case where the adsorption towers of the primary treatment and the secondary treatment are each one, and FIG. 7 shows a case where the adsorption tower of the tertiary treatment is one.

The operation shown in FIG. 6 is similar to that described above, but requires an intermediate product (concentrated O ₂ ) reservoir. Therefore, the first to first
The number of towers (including the reservoir) in the secondary treatment system is the same as in FIG. In the case of FIG. 7, the product gas is supplied to the valve (2c).
And temporarily stored in the product reservoir, and the reduced pressure purge is performed by opening the valve (4d) for a short time.

(Embodiment 2) A description will be given with reference to FIGS. First to third order processes are sequentially performed. Basically, it is the same as the case of FIG. The primary treatment is a drying tower (10) (10
A: carbon dioxide, N ₂ adsorbent, 10B: moisture adsorbent) and drying tower (11) (11A: carbon dioxide, N ₂ adsorbent, 1
1B: moisture adsorbent), and the secondary treatment is performed using an O ₂ adsorption tower (2
0) (20A: MSC) and O ₂ adsorption tower (21) (21)
A: MSC), and the third treatment is the N ₂ adsorption tower (30) (3).
0A: MS-5A or MS-13X, 30B: moisture adsorbent) and the N ₂ adsorption tower (31) (31A: MS-5A or MS-13X, 31B: moisture adsorbent). The main difference between the constituent units in FIG. 5 and the constituent units in FIG. 8 is that the primary processing device in FIG. 8 has a two-column configuration, whereas the primary processing device in FIG. The pump in FIG. 8 is used in series, whereas the pump in FIG. 5 is in a mixed mode of serial use or parallel use.

The second embodiment will be described with reference to a valve sequence diagram of FIG. 10 according to FIG. One cycle T (second) (in this case, 12
0 second) is divided into eight time zones (A) to (H). (A) (0 to 25 seconds) The raw material air is supplied to the tower (20) via the tower (10).
At this time, the tower (30) is substantially at atmospheric pressure. (B) (25 to 30 seconds) The supply operation of the raw material air in (A) is continuing. The tower (30) is purged by opening the purge valve (4f) of the tower (31). (C) (30 to 40 seconds) The valves (3d) and (4c) of the secondary treatment device are opened, and the intermediate product gas (enriched O ₂ ) is recycled and supplied from the column (21) to the column (20). At this time, part of the recycled gas
Through the valve (1e) as the raw material gas of the next treatment apparatus, the column (3)
0). (D) (40-60 seconds) B recycling operation is continuing. Tower (30) from valve (2e)
, A high-purity O ₂ product is taken out.

(E) (60 to 85 seconds) The removal of the high-purity O ₂ product of (D) is continuing. The feed air is supplied to the tower (21) via the tower (11). (F) (85 to 90 seconds) The supply operation of the raw material air in (E) is continuing. The tower (31) is purged by opening the purge valve (4e) of the tower (30). (G) (90 to 100 seconds) The valves (3c) and (4d) of the secondary processing apparatus are opened, and the intermediate product gas (enriched O ₂ ) is recycled and supplied from the tower (20) to the tower (21). At the same time, part of the recycled gas
The raw material gas is supplied to the tower (31) via f). (H) (100-120 seconds) Recycling of (G) is ongoing. Tower (31) from valve (2f)
, A high-purity O ₂ product is taken out. The steps (A) to (H) are delayed by T / 2 hours in the tower (1).
1), the tower (21) and the tower (31).

(Modifications) (1) The operating pressure range of the first processing apparatus is from vacuum pressure to atmospheric pressure or more (for example, 0.05 ata to 2.0 kg / cm ^2).
G). In the above Examples 1 and 2, the operation was performed at atmospheric pressure or higher (eg, 0.0 to 5.0 kg / cm ² G). (2) The operating pressure range of the secondary processing apparatus is set to be equal to or higher than the atmospheric pressure (for example, 0.0 to 5.0 kg / cm ² G). (3) The pump can be used in the following five ways. The pump (P1) shown in FIGS. 5 and 8 includes the primary processing device or the primary processing device and the secondary processing device, and similarly, the pump (P2) includes the secondary processing device or the secondary processing device and the second processing device. Operate separately up to the tertiary processing unit. DC is used (the same as in Example 2). Use in parallel. DC to co-current use (select according to time) (Example 1)
Same as). In the vicinity of atmospheric pressure, individual or parallel flow is used, and when ΔP is large, it is selectively used in series.

(4) Adsorbents At least one water adsorbent such as activated alumina or silica gel is used as an adsorbent for the primary treatment apparatus.
Packing in layers using at least one carbon dioxide adsorbent such as MS (Zeorite Molecular Sieve). Alternatively, one type of moisture adsorbent is used, and the upper layer is layered with activated carbon as a carbon dioxide adsorbent and ZMS as an N ₂ adsorbent. Filling the inlet end with a moisture desiccant as an adsorbent for the second treatment apparatus, and then filling MSC in a layered form thereon.
Filling the inlet end with a moisture desiccant as an adsorbent for the tertiary treatment apparatus, and then filling ZMS in a layered form thereon. Use of an adsorbent for removing a trace amount of unnecessary gas in the gas that has passed through the second step as an adsorbent for the tertiary treatment device.
(5) Adsorption towers The adsorption towers of the primary treatment device and the secondary treatment device must have the same specifications.

9. Example 3 A test for producing high-purity oxygen from air using the same system as in FIG. 5 and using the valve sequence shown in FIG. 9 was performed. As the primary treatment device and the secondary treatment device, adsorption towers having the same specifications were used. The following desiccants and adsorbents were used. Moisture desiccant for primary treatment equipment: activated alumina 1.5k
g Carbon dioxide adsorbent of the primary treatment device: MS-5A 6.0
kg Oxygen adsorbent of the second treatment unit: 15.0 kg of MSC Water desiccant of the third treatment unit: activated alumina 0.4 k
g Nitrogen adsorbent for the tertiary treatment apparatus: 2.6 kg of MS-5A As a result, 5.1 liters of high-purity oxygen of 99.7% was obtained per minute. Overall adsorbent productivity 12 (liter / kg (H)) Yield 38.2 (%)

[0050]

【The invention's effect】

1. The apparatus simplified according to the method of the present invention can arbitrarily produce high-purity oxygen of 99.5% or more by one button operation. 2. Heretofore, there has been only a method of transporting a small oxygen consumer to a heavy oxygen cylinder or a dangerous small liquid acid container at an extremely low temperature. 6 (medium (oxygen) if supplied by cylinder)
It transports iron containers twice as heavy, causing a large energy loss in transportation and handling is dangerous, requiring labor to replace containers and move inside buildings.However, the equipment simplified by the method of the present invention can be used at the place of use. By installing, such uneconomical and inconvenience are eliminated. 3. The device according to the method of the present invention operates at normal temperature and low pressure.
Therefore, it can be used in a laboratory or a working room in a building, in a building or a hospital or on a site without requiring a special qualification holder or an installation place. In addition, when the power supply is used as attached to a device or an apparatus, continuous operation can be performed unattended without worrying about the supply stop even at night as long as the power is supplied. 4. As described above, the apparatus according to the method of the present invention can be used in various fields of small-volume consumption, and is expected to bring about convenience such as energy saving and labor saving, and to exert a great effect. Is expensive.

[Brief description of the drawings]

FIG. 1 is a basic connection diagram showing the principle of a high-purity oxygen production apparatus.

FIG. 2 is a diagram showing a conventional oxygen production system using the PSA method.

FIG. 3 is a diagram showing another oxygen production system according to the conventional PSA method.

4 is an example of a valve sequence in one-cycle operation of the device shown in FIG.

FIG. 5 is a diagram showing a basic configuration of a high-purity oxygen production apparatus using the method of the present invention.

6 is a diagram showing an example of a partially modified embodiment of the device shown in FIG.

FIG. 7 is a diagram showing another example of a partially modified embodiment of the device shown in FIG. 5;

FIG. 8 is a diagram showing a basic configuration of another high-purity oxygen production apparatus using the method of the present invention.

9 is an example of a valve sequence in one cycle of the device shown in FIG. 5;

10 is an example of a valve sequence in one cycle of the device shown in FIG. 8;

[Explanation of symbols]

A: nitrogen adsorber C: oxygen adsorber D: air dryer C-1, C-2, a1, b2, 10B: adsorbent b1, 10A: desiccant 1 to 7, 1a to 4a, 1b to 4b, 1c ~ 4c, 1d ~
4d: Automatic valve 2e, 2f: Needle valve (flow regulating valve) 10: Drying tower 20C, 21C: Oxygen adsorbent 30A, 31A: Nitrogen adsorbent P1, P2: Pump 13: Raw material air supply line 14: Waste gas line 15: Concentrated O ₂ supply line (to N ₂ adsorption tower) 16: Countercurrent depressurized gas line (from N ₂ adsorption tower) 17: Recycle supply line 20, 21: O ₂ adsorption tower 30, 31: N ₂ adsorption Tower 32: Product oxygen reservoir (A) to (H): Pump usage mode

Claims (5)

(57) [Claims] (1)The following using one or two towers respectively
Perform the first to third steps by one cyclic valve opening / closing operation.
Using one device,Continuous production of high-purity oxygen from air
How to buildAt Removes unnecessary components such as moisture, carbon dioxide and nitrogen in the air
The first step using an adsorbent that selectively adsorbs oxygen Process
The second step of concentrating the oxygen in the passed gas The above-mentioned step using an adsorbent for selectively adsorbing nitrogen Process
3rd process to make oxygen in passed gas high purityThis one device is connected to one valve sequence (valve opening time to
From the first step to the second and third steps
And implement it to be valuable as you go to the later stage, this valve
By performing rational time allocation of the sequence,
Unnecessary gas is recycled to the first step, and the third step is unnecessary
The gas is enriched with valuable components according to its purity classification.
And recycle the residue to the first process.
High purity oxygen production method. 2. The one device is a simplified device in which each of the adsorption towers for performing the first to third steps is connected directly to a pipe without using a reservoir, heat exchange, or the like. The method of claim 1, wherein: 3. The method according to claim 1, wherein the one device is operated by dedicated power. 4. The method according to claim 1, wherein the operation of the one device is only started and stopped, and monitoring and operation adjustment personnel are not required. 5. The system according to claim 1, wherein all the automatic valves enter into a cooperative operation immediately when the start button is pressed.
The method according to any one of claims 1 to 4.