JP3071314B2 - High productivity gas separation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pressure swing adsorption method (also referred to as a pressure vibration adsorption method or a pressure fluctuation adsorption method) for separating and extracting a required gas from a mixed gas as a raw material. (Abbreviation).

[0002]

2. Description of the Related Art FIG. 8 is a diagram showing a basic configuration of a known two-cylinder system (first prior art) used for implementing a PSA method. FIG. 9 shows the operation state of each valve in one cycle (the time required for performing two adsorption separation operations) when the known PSA method is performed using the above system [hereinafter referred to as a valve sequence: A hatched portion indicates that the valve is open (the same applies hereinafter)].

In FIG. 8, two suction cylinders 1a, 1b
Are filled with adsorption columns a and b of an adsorbent. Each of the adsorption columns 1a and 1b has inlets 11a and 11b for introducing a mixed gas to be separated, and outlets 12a and 11b for collecting required gas separated from the gas mixture.
12b. The entrance 11a,
11b are connected to each other by valves via valves 13a and 13b. The pipeline between the valves 13a and 13b is connected to a gas mixture supply source 14.

[0004] A compressor (pump: P) is provided on a pipeline leading to the gas mixture supply source 14. The inlets 11a and 11b are further provided with valves 15a and 15b.
And are connected to each other through a pipeline.
The pipeline has a waste gas line 16 communicating with the atmosphere between the valves 15a and 15b. Exit 1 above
2a and 12b are connected to each other through a pipeline via valves 17a and 17b, respectively. The pipeline between the valves 17a and 17b is connected to the product gas reservoir R. The outlets 12a and 12b are connected to each other through an orifice 18. In addition, adsorption cylinder 1
a, 1b and the product gas reservoir R each have a pressure gauge S
_A , S _B and S _R are provided, respectively. The above valves are all automatic control valves that can be opened and closed by electric force or pneumatic pressure.

[0005] The PSA method is implemented in the system shown in FIG. 8 by the following method. Gas mixtures (for example,
Air or an industrially produced mixed gas) enters the adsorption tube 1a from the gas mixture source 14 under continuous pressurization into the adsorption column 1a.
1a. The introduction of the gas mixture is made by opening the valve 13a. During this operation, the adsorption cylinder 1a
, All the valves 15a and 17a around are closed. By introducing the gas mixture into the adsorption column 1a, the unnecessary gas component (adsorbed gas) is adsorbed by the adsorbent of the adsorbent column 1a from the inlet side, thereby forming an adsorbed gas zone. With the introduction of the gas mixture, the leading end of the adsorption gas zone advances along the adsorption column. When the pressure in the adsorption cylinder reaches a substantially predetermined maximum pressure, the valve 17a is opened, a required gas component is taken out from the outlet 12a, and collected in the product gas reservoir R. Just before the end of the adsorption gas zone reaches the end of the column 1a, the valve 13a is closed and the introduction of the gas mixture into the adsorption column is stopped. Almost at the same time, the valve 17a is closed.

Subsequently, the valve 15a is opened, and a part of the unnecessary gas component remaining in the adsorption cylinder in a pressurized state is discharged through the waste gas line 16. In addition, the waste gas line 16 may be connected to a vacuuming system (not shown) in order to more effectively release the gas in the adsorption cylinder. By this discharging step, most of the gas portion remaining in the adsorption column is removed. However, a considerable portion of the gas component adsorbed by the adsorbent of the adsorbent column 1a remains in the adsorption column. This is because the simple operation described above does not sufficiently desorb the adsorbed gas components.

The desorption of the adsorbed gas component is performed using a part of a desired gas component (product gas). That is, the desorption operation is performed by introducing and flowing a part of the product gas into the adsorbent column from the outlet 12a of the adsorption cylinder 1a in a direction opposite to the flow direction of the gas mixture. The introduced product gas desorbs the adsorbed gas component, and is released and removed from the adsorption column 1a together with the desorbed gas component via the waste gas line 16. In this case, desorption can be performed more effectively by connecting the evacuation system to the waste gas line 16. The above-mentioned desorption procedure of the gas component adsorbed using the product gas is called a barge method. The introduction of the product gas is continued until the adsorbed gas components are desorbed and released from the waste gas line 16, and thereafter,
Valve 15a is closed.

[0008] The gas separation operation for the adsorption cylinder 1a consisting of the above steps is similarly performed for the adsorption cylinder 1b.
However, the gas separation operation of the adsorption cylinder 1a and the gas separation operation of the adsorption cylinder 1b are performed in the product gas collection step in the operation of the adsorption cylinder 1a (or 1b) and the desorption of adsorbed gas components in the operation of the adsorption cylinder 1b (or 1a). The process is performed at a time interval so that the process and the process proceed at the same time. That is, the ninth
As shown in the figure, while the product gas collecting step of the adsorption cylinder 1a (the valve 17a is in the open state) is in progress, the adsorption gas component desorbing and removing step of the adsorption cylinder 1b (the valve 15b is in the open state). A), or while the product gas collecting step (the valve 17b is open) of the adsorption cylinder 1b is in progress, the adsorption gas component desorbing and removing step of the adsorption cylinder 1a (the valve 15a is opened) (In a state), the gas separation operation of each of the adsorption cylinders 1a and 1b is performed. The product gas used in the adsorption gas component desorption / removal step of the adsorption cylinders 1a and 1b is a part of the product gas collected in the adsorption cylinder 1b or the product gas collection step of the adsorption cylinder 1a, respectively. . Specifically, a part of the product gas separated in the adsorption cylinder 1a (or 1b) through the orifice 18 by the pressure difference between the cylinder 1a and the cylinder 1b is directly transferred to the adsorption cylinder 1
By introducing the gas into the adsorbent column b (or a) from the outlet 12b (or 12a) of b (or 1a), the adsorption gas component desorbing and removing step of the adsorption cylinder 1b (or 1a) is performed.

In the PSA method, the gas separation operation of the adsorption column 1a and the gas separation operation of the adsorption column 1b are repeated in order to produce a required gas amount. In this way, product gas is alternately withdrawn from each cylinder into the product gas reservoir, resulting in continuous collection.

Next, Japanese Unexamined Patent Publication No. Hei.
A PSA method having a configuration according to the second conventional technique disclosed in Japanese Patent Application Laid-Open No. 52615/1995 and Japanese Patent Application Laid-Open No. 3-123617 will be specifically described with reference to FIGS. In FIG. 10, adsorbents 2a and 2b are provided on adsorption cylinders 1a and 1b, respectively.
Are housed, each having the same configuration, in which a mixed gas is fed in from the lower side in the figure, unnecessary gas is adsorbed, and a required gas is discharged from the upper side. The pump 3 pressurizes the gas mixture supplied from the intake port 14 and sends out the gas mixture to the pipe 4.
a and 11b are fed from below the adsorption cylinders 1a and 1b. The required gas obtained from the upper side of the adsorption cylinders 1a and 1b is collected from the pipes 12a and 12b to the storage tank 6 via the pipe 5, and is used for a required application. Line 16 is
This is a path for releasing the pressure of the gas remaining in the adsorption cylinders 1a and 1b or sucking out the gas during the later-described process.

Each on-off valve 13a, 13b, 15a, 15
Reference numerals b, 17a, 17b, 18a, 18b, and 20 denote valves for opening and closing the passage of the pipe gas, respectively. The opening and closing operations are performed by a control unit (not shown) so as to accomplish required steps. The on-off valves 13a, 1
3b contributes to the above-mentioned feeding operation, and includes on-off valves 15a, 15b.
Contributes to the discharge operation described above, the on-off valves 17a and 17b contribute to the sampling operation described above, the on-off valves 18a and 18b contribute to the desorption operation and the pressure equalizing operation, and the valves 21a and 21b equalize the valve 18a. , 18b, the valve 18a-valve 21
a, the valve 18b and the valve 21b are operated simultaneously to contribute to pressure equalization, and the on-off valve 20 contributes to the mitigation or release of the transient pressure rise in the pipeline 4 during the switching operation of each valve.

Each of the pressure gauges 7a and 7b is
The pressure in the inside of the storage tank 6 is visually monitored by the pressure gauge 8 by monitoring the pressure in the insides a and 1b. The pump 3 operates continuously, and only the operation start and operation stop are manually operated by a control unit (not shown). Each open / close valve is controlled to open and close during a process of one cycle as shown in FIG. 11 in a valve sequence. In FIG. 11, each on-off valve is open only during the hatched period, and is closed during the other periods. On-off valve 18a and valve 21a, valve 18b and valve 21b
Are valves of the same specification, which open and close for the same time in the same time zone in the valve sequence. The valve 18a and the valve 21a are simultaneously operated, and substantially the same amount of gas flows from both the upper and lower directions in the direction of the arrow, and the two cylinders are equalized in pressure. The same applies to the valves 18b and 21b.

The material and function of each part are as follows: for example, the adsorption cylinders 1a and 1b are made of stainless steel, each pipe is made of a soft plastic pipe, the adsorbents 2a and 2b are made of activated alumina for absorbing moisture in the lower layer, and MS-5A in the upper layer. The pump 3 is a diaphragm pump, and each open / close valve is an electromagnetic valve.

[0014]

The problem of the first prior art will be described. Referring to FIG. 8 and FIG.
The main parts of the apparatus of the method are the adsorption column and the pump. Therefore,
To reduce the size of the apparatus, it is necessary to first reduce the size of the adsorption cylinder. When the size of the adsorption cylinder is reduced, the pressure of the adsorption cylinder rises quickly (the adsorption capacity is quickly lost), so that the usage time of the adsorption cylinder is shortened. That is, by shortening the cycle time, the number of cycles per minute or hour increases,
If the sampling rate in one cycle is almost constant regardless of the cycle length, the product sampling rate is increased in liter / hour.

However, if the suction cylinder is made similar and small, the following problems occur. 1. Trouble due to an increase in the flow rate of the raw material ・ Unbalanced: The flow velocity flowing through each cross section of the adsorbent layer needs to be constant at each cross section, but the flow velocity at the center becomes faster,
Slow in the periphery. -In severe cases, the adsorbent layer is lifted and expanded by high-speed flow. The adsorbent is worn and powdered due to expansion and contraction. -In the worse case, the gas, the adsorbent, and the in-cylinder structure collide with each other, causing abrasion, powdering, and destruction of the adsorbent. 2. Difficulty in controlling the purge flow ・ When the adsorption column becomes small, the cycle becomes faster, and with the existing purge feed means such as an orifice or flow control valve, it is difficult or impossible to control the flow rate of product gas quickly and precisely within a few seconds (short time). Becomes As a result of the above, separation becomes insufficient or impossible, resulting in an increase in the amount of inferior-purity products obtained, resulting in a decrease in yield, and a decrease in productivity [adsorbent productivity (for example, 90% O ₂ liter / adsorption). Agent kg ・ hour)].

The problem of the second prior art will be described.
See FIGS. 1. In the second prior art, the pump capacity is not increased or the transient pressure release valve 20 is used for 0.1 second to reduce the rush impact caused by the ejection of the material flow at the time of material supply. Open or close instantaneously or intermittently, etc.
Care was taken not to apply an abnormal pressure rise to the adsorbent. 2. As for the control of the pulse flow, the pulse valve was opened and closed intermittently, and the flow rate of the pulse flow was controlled within a short time.

As a result, the productivity is remarkably improved as compared with the first prior art. However, in order to further increase the adsorbent productivity over the second conventional technique, the following detailed considerations are required, and it is necessary to overcome these problems. Regarding the feed of raw material: The pump is operating at a constant speed, and the loss of feed of the raw material cannot be loosened even if it is discharged for a short time such as within 1 second. Therefore, it is necessary to avoid a loss such as discharging the source gas out of the system by the valve 20 or the like. Further, it is necessary to send a large amount of raw material gas to the adsorption column within a short time. Reduction of purge time (including reduction of the number of purges): 1
Since the ratio of the purge regeneration time during the cycle is high, it is necessary to reduce the required purge time as much as possible. Therefore, it is necessary to reduce the number of purges from two to five times to one or two times, and to reduce the gap between the opening and closing time of one valve and the opening and closing time of the next valve.

[0018]

SUMMARY OF THE INVENTION In view of the above problems, the present inventors have proposed (1) means for increasing the amount of raw material supplied per hour, and (2) means for shortening the purge operation time. Studied diligently. Regarding the problem (1): The feed amount of the raw material to the adsorption column (liter / sec) has been conventionally referred to as a volume load [raw material feed amount (liter / sec) / adsorption column (liter)]. The conventional volume load has no concept of the pressure of the adsorption column. The present inventors have suitable separation separation possible initial raw material infeed rate Q _p (l / sec) is found to increase in proportion to the fed just before the pressure (initial pressure). And the initial pressure is higher than atmospheric pressure, preferably 1 kg /
By setting it near cm ² G, it was possible to increase the feeding speed as compared with the prior art. The total cycle time can be reduced by increasing the feed rate of the source gas within a certain period of time or by shortening the feed time of the source material (the number of cycles within a certain period of time increases). We succeeded in improving it further.

Regarding the problem of (2), shortening of the time gap between the purging operation and the equalizing operation: The gap time between two open / close operations by one continuous valve or two open / close operations by two continuous valves is conventionally 1 sec ( 0.9se in most cases
c). This gap time indicates that the instantaneous pressure rise at the inlet side of the adsorption column due to the opening and closing operation of the purge valve suddenly drops,
This is the time required for the pressure difference on the outlet side to reach the initial value, which is longer when the gas supply amount is larger, and longer when the cylinder length is longer. Also, when the initial pressure difference is large, it becomes shorter. However, since the gas supply amount and the cylinder length have appropriate limits in design, in the present invention, the initial pressure difference is set to about 1.5 times as compared with the second conventional technique. As a result, the time gap between valve operations could be reduced by about 2 seconds per cycle without deteriorating the separation performance. As a result, the productivity (adsorbent productivity) can be improved without changing the product yield in one cycle, and the present invention has been accomplished.

Next, the present invention will be described in more detail. (1) As described above, one of the problems in the present invention is to increase the amount of raw material supplied per cycle and the amount of product to be obtained within a range where the separation operation is not impaired. As described above, the amount of raw material delivered per unit time is conventionally an empty tower (cylinder)
It is called speed (V _L ) and is expressed by the following equation. For small machines,

(2) As described above, another object of the present invention is to shorten one cycle time and increase the number of extractions per minute. Regarding (1): The reference value of the space velocity of the medium / large-sized oxygen-enriched PSA device is (Chemical Engineering Association, edited by Chemical Engineering Handbook, 5th revised edition, p. 608, Maruzen, 1988), 50-100 1
/H=0.014 to 0.028 1 / s. In the conventional PSA method, pressurization → constant operating pressure hold (product removal) →
As one cycle of pressure reduction →), in one cycle operation, from the viewpoint of preventing pressure fluctuations, increase the pressure to near a certain operating pressure by equalizing pressure with other cylinders or pressurizing product recycle, and then open the material feed valve. Pumping has begun.

Therefore, the pump capacity is designed based on the "discharge speed at a constant operating pressure", and no consideration is given to the boosting speed. In the case of the second prior art,
[Pressurization (product removal) → maximum pressure → decompression] is one cycle, and when there is a pressure rise during the feed of raw material gas (product is taken out during that time) and a predetermined maximum pressure is reached,
Immediately stop feeding the source gas and reduce the pressure. Therefore,
Unlike the conventional medium / large PSA apparatus, the supply (amount) speed of the raw material gas from the initial pressure to the maximum pressure becomes a problem.

As shown in FIG. 12, a volume V (cc), a cross-sectional area S (cm ² ), and a length of one adsorption cylinder are shown.
The suction cylinder of L (cm) is made an empty cylinder, and the initial pressure P (at
In a), if there is a pressure increase of ΔP (ata) due to gas inflow for one second, Therefore, the cylinder speed, the linear speed, and the contact time are as shown in Table 1 below.

[0024]

[Table 1] In Table 1, the cylinder speed V _m is defined as Q (cc / s) V _m = ──────────────. Here V _m corresponds to the above constant K V (cc) · P ( ata).

When the cylinder speed V _m = 1, the linear velocity is equal to L, and the contact time is 1 sec. In an actual system, there is an adsorbent in the cylinder and rapid adsorption is performed initially (ΔP becomes small), so that the linear velocity is small and the contact time is long as compared with the values in Table 1. The appropriate cylinder speed is determined by the adsorption system (adsorption cylinder, adsorbent, raw material gas, temperature, pressure, etc.) and should be determined by experiments. 30-60 as adsorbent
Using a mesh MS-5A and conducting an oxygen concentration test from air at room temperature, it was found that the appropriate feed rate could be increased in proportion to the pressure. Delivery speed Q _P (liter / s) Q _P = K · P · VP: adsorption cylinder pressure (ata) V: adsorption cylinder volume (liter) K is a constant mainly determined by pump performance and adsorbent performance, and K = 1 to 4. LV and t ₁ are related to ΔP / P, and the adsorption speed has the largest effect on this value. The above equations are believed to be widely applicable to systems similar to the adsorption of nitrogen by MS-5A.

When determining the actual pump displacement, FIG.
As shown in the example, the discharge speed of the pump is a function of the pressure, and rapidly decreases as the pressure increases. Thus, for example, when the initial pressure P _1, after the pump delivery valve open, the discharge speed Qp ₂ after 2-3 seconds, for example 1 discharge rate Qp ₁ when the P ₁
/ 2 etc. In such a case, it is better to expect about twice the value as K = 2 as the appropriate pump capacity. There are various types of pumps, such as a diaphragm type, a piston type, and a rotary type, and the influence of the adsorption speed and the like can be considered. By doing so, it was possible to increase the feed amount of raw material in one cycle without causing phenomena such as rush of impact, incomplete separation, and the like, and without reducing the product acquisition rate.

(2) Reducing the cycle time and increasing the number of extractions: In order to reduce the cycle time without reducing the (product acquisition amount / cycle), it is important to shorten the decompression and regeneration time [see above]. In (1), the pressurizing speed was increased → the pressurizing time was shortened]. For this purpose, the individual valve opening and closing times in the purge operation and the equalizing operation are reduced, and the waiting time between the purge operation and the equalizing operation is shortened between the purge operations and the equalizing operation. It is necessary to shorten the time gap with the valve opening / closing operation. This gap time is required until the differential pressure ΔP ₂ between the inlet and the outlet, which is instantaneously generated by opening the valve, becomes ΔP _{1 at the} initial stage of operation (ΔP ₁ = 0 when there is no in-cylinder flow at the beginning). In the second prior art, this time is based on around 1 sec.

This time is large when the input amount is large,
When the length of the adsorption cylinder is large, when the time is long, above the purge valve, etc.
When the value of the downstream pressure difference ΔP is large, there is a small time relationship. However, in one adsorption cylinder system, the amount of feed and the length of the adsorption cylinder have an appropriate range for the separation operation. While the present invention the △ P second prior art was 1.0~1.5kg / cm ^2, was increased to 2.0 kg / cm ^2, as a result, the time to less than 0.5sec I found that it could be shortened. The time gap between two successive valve opening / closing operations could be reduced by about 0.5 seconds.

As described above, according to the present invention, the cycle time can be reduced without reducing the product acquisition amount per cycle by the high load operation by increasing the feed rate of the raw material, the proper arrangement of the purge and the equalizing pressure in the regeneration step, and the shortening of the regeneration time. This has shortened the number of extractions per minute, increased the productivity compared to the first and second prior arts, and made it possible to reduce the size and size of the apparatus.

[0030]

The feed rate of the raw material gas was successfully increased without impairing the separation performance of the adsorbent, and the amount of product obtained in one cycle operation could be increased. In supplying the purge gas to the cylinder near the minimum pressure, the opening and closing operation of the purge valve is reduced to about 0.1 second, and
By shortening the time gap between one valve opening / closing operation and the next valve opening / closing operation to less than 0.5 seconds, the cycle time can be reduced without changing the product acquisition amount per cycle, and the number of cycles per minute can be reduced. , The adsorbent productivity could be increased. With a simple configuration of three cylinders, the feed of raw material gas is increased,
The pressure equalizing operation is properly arranged, the product loss in one cycle operation is reduced, and the number of purging times is required in the prior art.
Increase the number of products obtained in one cycle operation by shortening the time gap of valve opening / closing operation by shortening the time gap of valve opening / closing operation to 1 to 2 times and shortening the cycle time, thereby increasing the number of extractions per minute I was able to. As described above, the productivity of the adsorbent was remarkably increased as compared with the related art, and the apparatus could be reduced in size and size.

[0031]

Next, the present invention will be described in more detail with reference to Examples, but it should not be construed that the present invention is limited thereto without departing from the gist of the present invention. (Embodiments 1 and 2) Hereinafter, Embodiments 1 and 2 will be described with reference to FIGS. In these drawings, the portions denoted by the same reference numerals as those in FIGS. 8 to 12 indicate the same functional portions as those described in FIGS. 8 to 12. In FIG.
adsorbents 2a, 2b, 2c respectively
An operation example in which a mixed gas (air) is supplied from the lower side in the drawing to absorb unnecessary gas, and the required gas is transmitted to the upper side will be described. The pump 3 pressurizes the gas mixture supplied from the intake port 14 and sends out the gas mixture to the pipe 4. The pressurized gas mixture passes through the pipes 11 a, 11 b, and 11 c, and the adsorption cylinder 1 a,
1b and 1c are fed from below. Suction cylinder 1a, 1
The required gas obtained from each upper side of b, 1c
From a, 12b, 12c, it is stored in the storage tank 6 via the pipe line 5. The pipe 16 is used for the suction cylinder 1 during the process described later.
This is a path for releasing the pressure of the gas remaining in a, 1b, and 1c.

Each of the on-off valves 13a, 13b, 13c, 15
a, 15b, 15c, 17a, 17b, 17c, 18
a, 18b, 18c, 20, 21a, 21b, 21c
Are valves for opening and closing the passage of gas through the pipes in which they are arranged, and are operated to open and close by a control unit (not shown) so as to accomplish required steps. , 13c contribute to the above-mentioned sending operation,
The on-off valves 15a, 15b, and 15c contribute to the discharging operation, the on-off valves 17a, 17b, and 17c contribute to the sampling operation, and the on-off valves 18a, 18b, and 18c contribute to the purge desorption operation and the pressure equalizing operation. , 21b, 21c contribute to the pressure equalizing operation, and the on-off valve 20 contributes to the mitigation or release of the transient rise in the pressure in the pipeline 4 at the time of each valve switching operation. The on-off valves 17a, 17b, and 17c are configured such that an on-off valve with a flow rate adjustment or a simple on-off type valve is provided with a flow rate adjustment valve in series, and, for example, a needle valve is used for the flow rate adjustment. The pressure gauges 7a, 7b, 7c are respectively provided with the adsorption cylinders 1a,
The pressure inside 1b, 1c is monitored, and the pressure gauge 8 visually monitors the pressure inside the storage tank 6.

In the first embodiment, each open / close valve is controlled as shown in FIG. 2 in a sequence during one cycle of the process, and is controlled as shown in FIG. 4 in an actual operation time. The pressure changes seen at 7a, 7b, 7c are as shown in FIG. In the second embodiment, the sequence is controlled as shown in FIG. 3 during the process of one cycle, and the pressure change as seen by the pressure gauges 7a, 7b, 7c is as shown in FIG. 2 and 3, each on-off valve is opened only during the hatched period and closed during the other periods. Further, the pressure changes in FIGS. 5 and 6 are model diagrams, and in practice, there is a transient fluctuation of gas in each pipe line and each adsorption cylinder due to opening and closing of each on-off valve. Resulting in a deformation curve.

The order of each operation in the process of one cycle will be described in the case of (Embodiment 1). Basically, each pressure change of each of the adsorption columns 1a, 1b, and 1c is determined for one cycle period. That is, for example, the driving operation is performed with a three-phase change curve due to a phase difference obtained by dividing 12 seconds into three equal parts.
Specifically, the pressure in the adsorption cylinder 1a has a first phase pressure change having a change as shown by a thick line in FIG. 5, and the pressure in the adsorption cylinder 1b has a change as a thin line in FIG. The second phase pressure change and the pressure in the adsorption cylinder 1c are operated so as to perform a third phase pressure change having a change as indicated by the broken line in FIG. In addition, each of the pressure change, the maximum pressure P _H and the minimum pressure P _L
And an intermediate pressure P _M 1, P that divides these into approximately three equal parts
It operates so as to pass through four pressure points of _M2 .

First, when the operation is started, each pressure in each of the adsorption columns 1a, 1b, 1c follows various transitional courses for several cycles, but eventually, at the start of one cycle in FIG. In A, the pressure of the adsorption cylinder 1a is increased to a pressure P _{M1 during the} increase, and the pressure of the adsorption cylinder 1c is decreased to a pressure P _{M1 during the} decrease.
Adsorption column 1b is the starting point to rise from the pressure P _L. The operation from the start time A will be sequentially described mainly on the operation on the suction cylinder 1a, that is, the pressure change indicated by the thick line in FIG.

Pressurized feeding operation of mixed gas: From time A,
The on-off valve 13a is opened for only 3.5 seconds, and a pressurized feeding operation of feeding the mixed gas pressurized by the pump 3, that is, the raw material gas, to the adsorption column 1a is performed, and the pressure of the adsorption column 1a is increased to the maximum pressure. moves to P _H, and sends the required gas on the upper side of the adsorption cylinder 1a by adsorbing adsorbent 2a unwanted gas. At the same time, from time A, the on-off valves 18b and 21b are opened for only 0.5 seconds to perform a pressure equalizing operation between the adsorption cylinders 1b and 1c, and the pressure of the adsorption cylinders 1b and 1c is increased to the intermediate pressure P. _Move to _M2 . Next, from time B, the on-off valve 15c is opened for only 3.0 seconds so that the gas in the pipe 11c can be discharged to the pipe 16, so that the pressure of the adsorption cylinder 1c is reduced to the minimum pressure P _L.
Move to

Sampling operation of required gas: From time C, the on-off valve 17a is opened for only 1.0 second, and the required gas is sampled from the upper side of the adsorption cylinder 1a into the storage tank 6 via the pipe line 5. I do.

Attaching / detaching purge operation: From time D, on-off valve 1
8c is opened for only 0.1 second to perform a purge for sending a required gas from above the adsorption cylinder 1a to above the adsorption cylinder 1c, and the purged required gas desorbs unnecessary gas components adhering to the adsorbent 2c. While moving downward, a desorption purge operation of discharging gas containing desorbed substances to the pipeline 16 through the open / close valve 15c which is already open is performed. During this time, the adsorption cylinder 1a
Is temporarily decreased, and the pressure of the adsorption cylinder 1c is temporarily increased, but returns to the original pressure as the desorption purge operation is completed.

First pressure equalization (pressure reduction) operation: From time point E, the open / close valves 18a and 21a are opened for 0.5 second to perform the pressure equalization operation between the adsorption cylinders 1a and 1b. At this point, the on-off valve 13a, 15c are closed, it moves the adsorption cylinder 1a, a pressure of 1b to an intermediate pressure P _M 1. At the same time, from time E, the on-off valve 20 is opened for 0.5 second to avoid overload of the pump 3.

Second pressure equalization (pressure reduction) operation: From time point F, the on-off valves 18c and 21c are opened for 0.5 second to perform the pressure equalization operation between the adsorption tubes 1a and 1c. migrating the pressure of the intermediate pressure P _M 2. At the same time, from time F, the on-off valve 13b is opened for only 3.5 seconds, and a pressurized feeding operation of feeding the mixed gas pressurized by the pump 3, that is, the raw material gas, to the adsorption cylinder 1b is performed. The pressure of the adsorption cylinder 1b is shifted to the maximum pressure P _H , the unnecessary gas is adsorbed by the adsorbent 2b, and the required gas is sent to the upper side of the adsorption cylinder 1b.

Discharge (pressure reduction) operation: From time point G, the on-off valve 15a is opened for only 3.0 seconds, and gas remaining in the adsorption cylinder 1a is discharged from the lower side of the adsorption cylinder 1a to the pipe line 16. Perform the discharge operation. This operation pressure of adsorption column 1a moves to the lowest pressure P _L. Next, from time point H, the on-off valve 17b is opened for only 1.0 second, and a sampling operation is performed in which the required gas is sampled from the upper side of the adsorption cylinder 1b into the storage tank 6 via the pipe line 5. Next, from time I, the on-off valve 18a
Is opened for only 0.1 second, and purging is performed to send out a required gas from above the adsorption cylinder 1b to above the adsorption cylinder 1a.
A desorbing purge operation in which the purged required gas moves downward while desorbing unnecessary gas components adhering to the adsorbent 2a, and discharges gas containing desorbed substances to the pipeline 16 via the open / close valve 15a which is already open. I do. During this time, the pressure of the adsorption cylinder 1b temporarily decreases, and the pressure of the adsorption cylinder 1a temporarily increases, but returns to the original pressure as the desorption purge operation ends. Further, from time point J, the on-off valves 18b and 21b are opened for only 0.5 seconds to perform the pressure equalizing operation between the adsorption cylinders 1b and 1c. At this point, the on-off valve 13b, 15a are closed, the adsorption cylinder 1b, and the pressure of 1c intermediate pressure P _M 1
Move to At the same time, from time J, the on-off valve 20 is opened for 0.5 second to avoid overload of the pump 3.

Third pressure equalization (pressure increase) operation: From time K, the opening / closing valves 18a and 21a are opened for 0.5 seconds, and the pressure equalizing operation between the adsorption tubes 1a and 1b is performed. 1
a, it shifts the pressure of 1b to an intermediate pressure P _M 2. At the same time, from time K, the on-off valve 13c is opened for only 3.5 seconds to perform a pressurized feeding operation of feeding the mixed gas pressurized by the pump 3, that is, the raw material gas, to the adsorption cylinder 1c. The pressure of the adsorption cylinder 1c is shifted to the maximum pressure P _H , the unnecessary gas is adsorbed by the adsorbent 2c, and the required gas is sent out to the upper side of the adsorption cylinder 1c. Next, from the time point L, the on-off valve 15b is opened for only 3.0 seconds so that the gas in the pipe 11b can be discharged to the pipe 16, so that the pressure of the adsorption cylinder 1b is reduced to the minimum pressure P _L.
Move to Next, from time M, the on-off valve 17c is set to 1.0
Opening for only a second, a sampling operation is performed in which the required gas is sampled from the upper side of the adsorption cylinder 1c into the storage tank 6 via the pipe line 5. Further, from time N, the on-off valve 18b is opened for 0.1 second to perform a purge for sending a required gas from above the adsorption cylinder 1c to above the adsorption cylinder 1b. A desorption purge operation is performed in which unnecessary gas components adhering to the gas are desorbed and shifted downward, and gas containing desorbed substances is discharged to the pipe 16 via the open / close valve 15b which is already open. During this time, the pressure of the adsorption cylinder 1c temporarily decreases, and the pressure of the adsorption cylinder 1b temporarily increases, but returns to the original pressure as the desorption purge operation ends.

Fourth pressure equalization (pressure increase) operation: From time point O, the on-off valves 18c and 21c are opened for 0.5 second to perform the pressure equalization operation between the adsorption cylinders 1a and 1c. At this point, the on-off valve 13c, 15b are closed, moves the adsorption cylinder 1a, a pressure of 1c to intermediate pressure P _M 1. At the same time, from time O, the on-off valve 20 is opened for 0.5 seconds to avoid overloading the pump 3. Thus, one cycle is completed, and thereafter are repeated.

From the above description, the operation in the case of the steps shown in FIGS. 3 and 6 in (Embodiment 2) can be easily understood. in the manner, as shown in FIG. 6, intermediate pressure P _M a flat portion at an intermediate pressure in the operating pressure of the respective phases
It means that it can be set to 1. The configuration of a control unit (not shown) for operating each on-off valve controls the on-off operation of each on-off valve by setting sequence control using a general microcomputer as shown in FIGS. I have.

(Modification) The present invention includes the following embodiments. 1. In the above (Embodiment 1) and (Embodiment 2), three cylinders have been described, but the method of the present invention can be applied to two cylinders or four or more cylinders. When the initial pressure is 3 kg / cm ² G or more, a four-cylinder type is desirable. 2. In equalizing operation, it is usual to equilibrate the pressure between the two cylinders by moving an equal amount of gas between the upper and lower cylinders at the same time. Modifications such as a method of connecting to the inlet end of the motor and a method of connecting the outlet ends of the motor are also possible. 3. The inside of one cylindrical body or box-shaped body is divided into, for example, three parts, and each of the divided parts acts as one adsorption cylinder to form a three-cylinder densely-packed type. The dead space can be eliminated and the device can be made more compact. 4. A spool valve system in which the inlet holes and outlet holes of the multi-channel are formed by displacing the positions in the axial direction on the opposing surfaces on the cylinder, and the internal piston is made into a spool valve shape and reciprocated back and forth at a constant speed in the axial direction, or At the inlet end, a cam valve or a cam valve that opens and closes by opening and closing by a cam or shifts its position in the axial direction on the cylindrical surface or changes the phase angle to form an inlet hole and an outlet hole, and a flow path during rotation of the inscribed cylinder By combining a well-known multi-flow switching valve mechanism such as a rotary valve formed so as to communicate in order with an adsorption cylinder, the whole product becomes extremely compact.

(Example 3) An oxygen concentration test for separating oxygen from air was performed using the same system as in FIG. 1 and by the valve sequence shown in (Example 1). Adsorption cylinder: inner diameter 5.3 cm, length 23 cm, inner volume 507 cc Adsorbent: MS-5A. 2a (497 g), 2b (501
g) and 2c (503 g) were charged. In addition, 18% of the adsorbent layer was filled with activated alumina. As a result, 90% O ₂ was continuously obtained at 10.8 liters per minute. Therefore, the adsorbent productivity was 432 liters (90% O ₂ ) / kg · Hr. In Example 3, the time gap between the pulse purge and the equalizing operation was reduced to 0.4 sec, compared to 0.9 sec in the following comparative example. At the start of pressurization (2 ata), PV = 1.014 (l-ata) and the pump capacity used was 1.2 l / s (at 2 ata). Therefore K is Met.

Comparative Example A gas separation method using a system composed of two adsorption cylinders shown in FIG. 10 was performed to produce oxygen from air. Adsorption cylinder: 5.3 cm in diameter x 37.0 cm in length (stainless steel cylinder) Internal volume 816 cc Adsorbent: Type: MS-5A Filling amount: 983 g / system The activated alumina was filled at the inlet end of the adsorption cylinder. All valves are electrode valves (valves 17a, 17b, 18a, 18b are 1 /
4 inch type, and 3/8 inch type for others). Pump: 60 liter per minute diaphragm compressor. Oxygen separation was performed based on the valve sequence shown in Table 2. In Table 2, ~ indicates the number of times the valve is opened and closed.

[0048]

[Table 2]

(Result) 1.9 l / min of 90% oxygen was obtained. Adsorbent productivity = 116 liters (90% O ₂ ) / kg ·
Hr PV at an initial pressure of 2 data = 1.632 (liter-
ata) Pump volume used Q _P (2ata) = 0.5 l / s Therefore K was Q _P /PV=0.3.

[0050]

According to the method of the present invention, high-load operation and high-speed regeneration by the PSA method can be performed, which is five to five times that of the prior art.
A small and compact gas separator (for example, an oxygen concentrator) having ten times higher productivity and a high product yield becomes possible. As a result, there is an effect that it is attached to or built into many oxygen-using devices (for example, an ozonizer, a combustor, etc.) and is useful for energy-saving enhancement and promotion of oxidation and combustion. In addition, the adsorption cylinder and the automatic valve in the method of the present invention are integrated and integrated,
Very compact number 1 by combining with a high performance compressor such as an existing turbo or supercharger
Oxygen auto-concentrator of 0 liter / minute can be made. For example, by installing it on a car, it is possible to quickly and precisely control the air-fuel ratio (air / fuel) of the engine and to install it on a diesel vehicle exhaust particle filter trap. It is possible to burn out carbon, etc., and to exert a great effect on energy saving and reduction of emission of pollutant gas. Further, the method of the present invention can be applied to other mixed gas systems (for example, H ₂ —CO _2
2 system, N ₂ —CO ₂ system, N ₂ —H ₂ system, etc.) and can be applied to a small and compact gas separator such as a fuel cell to reduce the overall size of the device. It is expected to have the effect of saving energy, so its industrial utility value is extremely large.

[Brief description of the drawings]

FIG. 1 shows a configuration example of a three-cylinder gas separation method of the present invention.

FIG. 2 shows an example of a valve sequence of the three-cylinder gas separation method of the present invention.

FIG. 3 shows another example of the valve sequence of the three-cylinder gas separation method of the present invention.

FIG. 4 shows an embodiment of a valve sequence of the three-cylinder gas separation method of the present invention.

FIG. 5 shows a pressure sequence example of the three-cylinder gas separation method of the present invention.

FIG. 6 shows another example of the pressure sequence of the three-cylinder gas separation method of the present invention.

FIG. 7 shows a relationship diagram between a pump discharge speed and a pressure.

FIG. 8 shows a configuration of a first related art.

FIG. 9 shows a first prior art valve sequence.

FIG. 10 shows a configuration of a second conventional technique.

FIG. 11 shows a second prior art valve sequence example.

FIG. 12 is a view for explaining the principle of the principle of the method of the present invention.

[Explanation of symbols]

1a, 1b, 1c: adsorption cylinder 2a, 2b, 2c, a, b: adsorbent 3: pump 4, 14, 11a, 11b, 11c, 12a, 12b,
12c, 5, 16, 21: Pipe line 6: Storage tank 13a, 13b, 13c, 15a, 15b, 15c, 1
7a, 17b, 17c, 18a, 18b, 18c, 2
0,21a, 21b, 21c: on-off valve 7a, 7b, 7c, 8: pressure gauge P _H: the maximum pressure P _M 1, P _M 2: intermediate pressure P _L: minimum pressure Q _P: raw material infeed rate P: Initial Pressure ΔP: Pressure rise value V: Adsorption cylinder volume K: Constant n: Number of cylinders T: Cycle time L: Adsorption cylinder length S: Adsorption cylinder cross-sectional area

Claims (5)

(57) [Claims] 1. At least two or more adsorption columns (the number of columns is n) packed in a layer with an adsorbent capable of selectively adsorbing unnecessary gas components in a gas mixture composed of two or more gas components.
In a pressure vibration adsorption system consisting of: a raw material gas is pressurized and fed into the cylinder at an initial pressure equal to or higher than the atmospheric pressure, and unnecessary gas is adsorbed to the adsorbent from the inlet end of the cylinder, and the gas that has not been adsorbed is removed Advance to the outlet end and compress to maximum pressure,
A part of the gas not adsorbed from the end of the cylinder near the maximum pressure is taken out as a product gas, and the remaining part is supplied as a purge gas to another cylinder near the minimum pressure as an unsteady flow, and pressurization is stopped. The pressure in the cylinder is reduced by the (n-1) step equalizing operation, the gas in the cylinder is released to the atmosphere by the final step operation, the pressure is reduced to the minimum, the purge flow is received from the other cylinder by the unsteady flow, and the adsorption capacity is increased. It returns and (n-1) with another cylinder again
A series of pressure fluctuation operations that return to the initial pressure through the step equalizing operation is defined as one cycle operation (time; T), and this operation is shifted by T / n time, and in the circulation operation performed in another cylinder, the operation is performed from the initial pressure. Feed rate Q _p up to maximum pressure
(L / sec) at a feed rate represented by the following formula: Q _p = kPV _P (ata) is the initial pressure, V (liters) of the adsorption column volume, a k = 1 to 4, is a constant determined mainly compression characteristic of the pump and the adsorbent performance. 2. In the above-mentioned circulating operation, a time gap t (sec) between one valve opening / closing operation and a subsequent valve opening / closing operation is created by intermittent valve opening / closing operation of a valve in which a purge flow and a pressure equalizing flow continue. 2. The gas separation method according to claim 1, wherein 0.1) <t <0.5. 3. The gas separation method as described above, wherein the unnecessary gas adsorbent is MS-5A or MS-13X, and the raw material gas is air, and the method is an oxygen separation method performed in a three-tube configuration. The gas separation method according to claim 1. 4. The gas separation method according to claim 1, wherein in the gas separation method, one cylinder or the inside of the housing is separated into co-current sections, and one section is formed as one cylinder. 5. The gas separation method according to claim 1, wherein the multiple flow paths are formed and integrated into one valve mechanism such as a rotary valve, a cam valve, a spool valve, etc. as the flow path switching valve. Gas separation method.