JP3610253B2 - Mixed gas adsorption separation method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mixed gas adsorption separation method for selectively adsorbing and separating components from a mixed gas such as air.
[0002]
[Prior art]
There are various methods for separating a specific component such as nitrogen or oxygen as a product gas from a mixed gas such as air. Recently, a separation method using an adsorbent has been widely used because of the ease of designing the apparatus and the low cost of equipment. Such a separation method using an adsorbent is called a pressure swing adsorption method (hereinafter abbreviated as “PSA method” from Pressure Swing Absorption). For example, JP-A-1-236914, JP-A-7-94917, or JP-A-8 Prior art related to -294613 has been disclosed.
[0003]
In the PSA method, a plurality of adsorption tanks are filled with an adsorbent, and operations such as supply of mixed gas to each adsorption tank, adsorption / desorption of specific component gases, regeneration of adsorbent, and return pressure are sequentially performed by switching valves. Like to do. Adsorption of the specific component in the mixed gas is performed in a pressurized state, and desorption of the adsorbed specific component is performed in a reduced pressure state. The PSA method makes use of such selective adsorption characteristics of the adsorbent. For example, in the separation of oxygen from air, the apparatus can be configured smaller than the cooling liquefaction method. In addition, there are features such as easy operation and continuous unmanned operation.
[0004]
FIG. 8 shows the operation of the adsorption tank used in the PSA method. The adsorption tank as shown in FIG. 8A is filled with an adsorbent, and a mixed gas is introduced from below and a product is taken out from above. FIG. 8B shows the amount of gas adsorbed by the adsorbent with respect to oxygen and nitrogen. When, for example, “Zeolite 5A” is used as the adsorbent, a larger amount of nitrogen can be selectively adsorbed than oxygen. However, there is a limit to the amount of adsorption, and if a certain amount of nitrogen determined by the pressure is adsorbed, it will lose more adsorption capacity for both nitrogen gas and oxygen gas. The boundary between the portion saturated with nitrogen gas and the portion not saturated becomes an adsorption zone, which selectively adsorbs nitrogen gas, and the concentration of nitrogen gas in the portion downstream of the adsorption zone Decreases and the concentration of oxygen gas becomes relatively high. Therefore, as shown in FIG. 8 (c), the concentration of oxygen gas is higher in the void portion that is not filled with the adsorbent in the adsorption tank as compared with the upstream side up to the adsorption zone.
[0005]
As described above, a large amount of oxygen gas as a product gas component is contained in the unused adsorbent portion and the void portion downstream of the adsorption zone. Conventionally, a pressure equalizing operation as shown in FIG. 9 has been performed to recover these useful gases. In the pressure equalization operation, when switching between the adsorption tank A that has completed production of gas by adsorption separation and the adsorption tank B that has been regenerated, only the inlet side and the outlet side, or only the outlet side are communicated, and both are close to each other. By performing the operation to make the pressure, the useful gas is recovered.
[0006]
JP-A-1-236914 discloses a prior art in which two adsorption tanks are switched alternately and regeneration is performed on the other side while performing adsorption. Japanese Patent Application Laid-Open No. Hei 7-94917 discloses a prior art for increasing the use efficiency of an adsorbent while sequentially switching between adsorption and regeneration in a plurality of adsorption tanks. Japanese Patent Laid-Open No. 8-294613 discloses a prior art in which pressure equalization is performed between adsorption and regeneration while performing adsorption and regeneration using two or more adsorption towers.
[0007]
[Problems to be solved by the invention]
In a general PSA method, for example, when nitrogen gas is adsorbed and separated from air and oxygen gas is taken out as a product, not only nitrogen gas is adsorbed by the adsorbent but also part of the oxygen gas is adsorbed. In addition, there is a nitrogen gas that is not adsorbed by the adsorbent but is present together with the oxygen gas in the mixed gas. When performing regeneration, oxygen gas containing nitrogen gas is discharged, and a part of the oxygen gas that should be taken out as a product is lost, resulting in a problem that the yield of the product is impaired. The adsorbent in the adsorption tank forms an adsorption band in a layered manner from the inlet side to the outlet side, and performs adsorption separation while moving the adsorption band from the inlet side to the outlet side. The adsorbent on the inlet side of the adsorption zone becomes saturated due to adsorption of nitrogen gas. If all the adsorbents adsorb nitrogen gas and become saturated and then switch to regeneration, the adsorbents can be used efficiently. However, if the adsorption is continued even if all the adsorbents in one adsorption tank are saturated with nitrogen gas, the nitrogen gas is taken out without being adsorbed, and the product purity is reduced. In practice, it is very difficult to detect when all adsorbents are saturated. For this reason, it is not possible to use all the adsorbents until they are completely saturated, and at least a part of the adsorbents filled in one adsorption tank is left unused as a margin, It is necessary to maintain the quality by keeping the purity of the gas taken out as a product even if the adsorption state varies. However, since all the adsorbents are not used until they are completely saturated, there is a problem that the use efficiency of the adsorbents is poor. In the prior art disclosed in Japanese Patent Laid-Open No. Hei 7-94917, switching of a plurality of adsorption tanks is performed in a complicated procedure, and the number of switching valves and the like for switching the piping system is increased, so that complicated control must be performed.
[0008]
Further, in the pressure equalization method disclosed in Japanese Patent Laid-Open No. 8-294613, the downstream portion of the adsorbent tank is contaminated with the gas desorbed by the pressure equalization recovery operation at the outlet side with high recovery efficiency, and the product gas purity Can not be done until complete pressure equalization. Also, even if the pressure can be completely equalized, the amount of useful gas that can be recovered is about 50% of the amount of product gas components in the unused adsorbent portion and the void portion on the downstream side, and the remaining amount The portion is discharged out of the system by depressurization operation of the adsorption tank entering the regeneration process.
[0009]
An object of the present invention is to provide a mixed gas adsorptive separation method that can avoid the complexity of the apparatus and operation, increase the recovery efficiency of useful gas, and reduce the amount of adsorbent used.
[0010]
[Means for Solving the Problems]
The present invention relates to a method for separating components in a mixed gas using an adsorbent,
The adsorbent for performing the adsorption separation of gas is stored separately in two main adsorption tanks and one sub adsorption tank,
The following four stages of control are repeated in sequence, the main adsorption tanks are used alternately, and the secondary adsorption tank is always used for gas adsorption, while the adsorbent in the unused main adsorption tank is also regenerated. A mixed gas adsorption separation method characterized by
(1) The mixed gas whose pressure has been increased to the adsorption pressure is introduced into one main adsorption tank and one sub-adsorption tank, and gas is adsorbed and separated mainly by the adsorbent in one main adsorption tank. While taking out the gas that passed through the adsorption tank as a product, depressurize the other main adsorption tank,
(2) While continuing the adsorption separation of the mixed gas in one main adsorption tank and the sub-adsorption tank, the gas taken out as a product in the other main adsorption tank is in the opposite direction to the mixed adsorption separation adsorption. To regenerate the adsorbent,
(3) Disconnect one main adsorption tank and the sub-adsorption tank, connect the other main adsorption tank and the sub-adsorption tank,
{Circle around (4)} Depressurization of one main adsorption tank is started, and a mixed gas is introduced into the other main adsorption tank and sub-adsorption tank to raise the pressure to the adsorption pressure.
[0011]
According to the present invention, the adsorbent is divided and stored in two main adsorption tanks and one sub adsorption tank, so that the main adsorption tanks are alternately used to perform gas adsorption separation mainly. Can be used to maintain quality. In the method of performing adsorption separation and regeneration by switching two adsorption tanks alternately, if the entire adsorbent in one adsorption tank is used and then switched to regeneration, the purity of the product decreases and it is difficult to maintain quality. Therefore, it is necessary to switch from adsorption separation to regeneration with a certain margin. When the two adsorption tanks are switched alternately, it is necessary to provide a margin for maintaining quality in each adsorption tank. In the present invention, by giving the sub-adsorption tank a function as a margin for maintaining quality, it can function as a common margin for the two main adsorption tanks, reducing the amount of adsorbent used. can do. Even if the gas in the secondary adsorption tank, which contains many high-purity products, moves to the main adsorption tank side by pressure equalization, when performing adsorption separation using the main adsorption tank, it must be taken out again as a product through the secondary adsorption tank. Therefore, the collection efficiency of the product can be increased.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a configuration for applying and desorbing the adsorbent as an embodiment of the present invention and desorbing the adsorbent at a pressure lower than the normal pressure. The mixed gas as a raw material is pressurized by the gas compressor 1 in order to selectively adsorb the component gas at a high adsorption pressure according to the PSA method. A vacuum pump 2 is provided for pressure reduction. The adsorption separation of the raw material gas is performed using the two main adsorption tanks A3 and B4 and the sub adsorption tank 5. One of the main adsorption tank A3 or the main adsorption tank B4 and the sub-adsorption tank 5 are connected, and a specific component gas is adsorbed and separated from the mixed gas, and then other component gases are removed from the sub-adsorption tank 5. Take out to product tank 6 and use as product gas. Automatic valves 7 and 8 and automatic valves 9 and 10 are provided on the inlet side of the main adsorption tank A3 and the main adsorption tank B4, respectively. The automatic valve 7 and the automatic valve 10 are respectively provided between the supply side of the mixed gas as a raw material and the inlet side of the main adsorption tank A3 and the main adsorption tank B4. The automatic valve 8 and the automatic valve 9 are provided between the inlet side of the main adsorption tank A3 and the main adsorption tank B4 and the suction side of the vacuum pump 2. An automatic valve 11 is provided between the inlet side of the main adsorption tank A3 and the inlet side of the main adsorption tank B4. An automatic valve 12 and an automatic valve 13 are provided between the outlet side of the main adsorption tank A3, the outlet side of the main adsorption tank B4, and the inlet side of the sub adsorption tank 5, respectively. An automatic valve 14 and an automatic valve 15 are provided between the outlet side of the main adsorption tank A3 and the outlet side of the main adsorption tank B4 and the product tank 6, respectively.
[0013]
The main adsorption tank A3 and the main adsorption tank B4 are filled with the adsorbent 16 and the adsorbent 17, respectively. An adsorbent 18 is filled in the sub adsorption tank 5. The amount of the adsorbent 16 and the adsorbent 17 is the same as the amount excluding the surplus among the adsorbents used in the conventional two-tank PSA method. The amount of the adsorbent 18 is equal to the margin of the adsorbent per tank of the adsorbent used in the conventional 2-tank PSA method. Therefore, in the conventional two-tank PSA method, the total amount of the adsorbent 16 and the adsorbent 17 and twice as much adsorbent as the adsorbent 18 are used, but in this embodiment, the adsorbent 16 and the adsorbent 17 are used. By using the total amount and the amount of the adsorbent 18 alone, the same adsorption separation ability can be exhibited. A hygroscopic agent is disposed upstream of the adsorbents 16 and 17 in the main adsorption tank A3 and the main adsorption tank B4. Moreover, the mixed gas pressurized by the gas compressor 1 is supplied after being stored in the raw material tank 19, and a control device 20 is provided for overall control.
[0014]
FIG. 2 shows a procedure for switching between strokes when performing adsorption separation in the configuration of FIG. As shown in FIG. 2 (1), the mixed gas from the gas compressor 1 is adsorbed and separated using one main adsorption tank, for example, the main adsorption tank A3 and the sub-adsorption tank 5, and the product gas is supplied to the product tank. 6, the other main adsorption tank B4 is assumed to be regenerated by reducing the pressure. In the main adsorption tank B4, the filled adsorbent 17 adsorbs gas in a pressurized state, and by reducing the pressure to atmospheric pressure, the gas remaining in the voids of the adsorbent 17 is purged into the atmosphere. Done. Such an operation can be performed with the automatic valve 7, the automatic valve 12 and the automatic valve 9 of FIG. 1 opened and the other automatic valves closed. When oxygen is taken out from the air as a product, the pressure of the gas compressor 1 is increased to a water column of, for example, 5000 mm, and the main adsorption tank A3 and the auxiliary adsorption tank 5 filled with the zeolite molecular sieve as the adsorbent 16 and the adsorbent 18 are supplied. The nitrogen gas is introduced and removed, and the oxygen gas is concentrated and stored in the product tank 6. On the other hand, the main adsorption tank B4 that has completed adsorption opens the automatic valve 9 and sucks it with the vacuum pump 2, and desorbs it to a pressure lower than the normal pressure to regenerate the adsorbent 17.
[0015]
In FIG. 2 (1), the air that is the mixed gas in the gas compressor 1 is pressurized to, for example, a 5000 mm water column, and passes through the automatic valve 7 and the automatic valve 12, and the main adsorption tank A3 filled with zeolite molecular sieve as the adsorbent 16 and the auxiliary adsorption tank A3. It introduce | transduces into the adsorption tank 5, nitrogen gas is adsorbed and removed, oxygen gas is concentrated, and it stores in the product tank 6. FIG. On the other hand, the main adsorption tank B4 that has completed adsorption is decompressed to a pressure of 180 mmHg by the vacuum pump 2 through the automatic valve 9 to desorb the adsorbent 17 to regenerate the adsorbent 17.
[0016]
In FIG. 2 (2), the main adsorption tank A3 and the sub adsorption tank 5 continue to produce oxygen by adsorption separation. The main adsorption tank B4 opens the automatic valve 15 for 10 to 30 seconds at a flow rate of 0.8 to 1.5 times the amount of concentrated oxygen gas taken out from the product tank 6 as part of the concentrated oxygen gas as product gas. The gas is made to flow backward to clean and regenerate the main adsorption tank B4.
[0017]
In FIG. 2 (3), the desorption regeneration of the main adsorption tank B4 is completed. The operating states of the automatic valve 12 and the automatic valve 13 are switched on the outlet side of the main adsorption tank A3 and the main adsorption tank B4. The automatic valve 12 is closed, the automatic valve 13 is opened, the sub-adsorption tank 5 communicates with the main adsorption tank B4 that has been regenerated, a part of the concentrated oxygen gas from the product tank 6 is caused to flow back through the automatic valve 13, The pressure increase in the adsorption tank B4 is started. On the other hand, on the inlet side of the main adsorption tank A3 and the main adsorption tank B4, the automatic valve 11 is opened to perform the pressure equalization operation on the inlet side, and the raw material gas on the inlet side of the main adsorption tank A3 becomes the inlet side of the main adsorption tank B4. Is recovered. The automatic valves 7 to 10 and the automatic valves 14 and 15 are closed.
[0018]
In FIG. 2 (4), the main adsorption tank B4 is connected to the gas compressor 1 side on the inlet side, the product tank through the sub-adsorption tank 5 from the outlet side by the mixed gas from the gas compressor 1 and from the outlet side. 6, the inside of the main adsorption tank B <b> 4 is increased to the adsorption pressure with a part of the concentrated oxygen gas flowing backward from 6. At this time, the automatic valve 10 and the automatic valve 13 are opened, and the other automatic valves are closed.
[0019]
FIG. 3 shows the timing at which the automatic valve opens in the process described above. In this embodiment, the switching is performed using six automatic valves of the automatic valve 10 to the automatic valve 15, but this number is, for example, 11 shown in FIGS. 1 and 2 of JP-A-1-236914. The number of valves to be used can be reduced as compared with the case of using one switching valve. FIG. 1 of Japanese Patent Laid-Open No. 7-94917 shows a configuration using 20 switching valves, and FIG. 1 of Japanese Patent Laid-Open No. 8-294613 shows a configuration using 10 switching valves. it can.
[0020]
FIG. 4 shows the amount of useful gas adsorbed on the downstream side of the main adsorption tank A3 and the main adsorption tank B4, compared with the useful gas absorption amount by only the pressure equalizing operation of the conventional method shown in (1). The reason why the useful gas recovery amount of the present embodiment to be shown is increased will be described. The amount of useful gas recovered increases as the pressure difference increases. In the present embodiment, regeneration is performed at a regeneration pressure lower than the pressure equalization pressure, so that a large amount of useful gas can be recovered.
[0021]
FIG. 5 shows the concept of the distribution of the adsorbent 16 and adsorbent 17 filled in the main adsorption tank A3 and the main adsorption tank B4 and the adsorbent 18 filled in the sub adsorption tank 5 in this embodiment. Fig.5 (a) shows the state which complete | finishes the adsorption separation using an adsorbent in one adsorption tank by the 2 tank type PSA method similar to FIG.8 (c). When the regeneration is performed after all the adsorbents in the adsorption tank are used, a problem arises in terms of product quality. Therefore, it is necessary to switch to regeneration while leaving a margin in the adsorbent tank. In the present embodiment, the portion that has been spared in the conventional two-tank PSA method is used as the adsorbent 18 in the sub-adsorption tank 5 in common for the two main adsorption tanks A3 and B4, and as a whole is conventional. The adsorption separation capacity equivalent to that of the two-tank PSA method can be provided, and the amount of adsorbent used can be reduced by one adsorbent 18 minutes.
[0022]
FIG. 6 shows a configuration in the case of performing normal pressure desorption as another embodiment of the present invention. In this embodiment, parts corresponding to those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted. In the present embodiment, the outlets of the automatic valve 8 and the automatic valve 9 are opened to the atmospheric pressure instead of the vacuum pump 2. The regeneration pressure shown in FIG. 4 is increased, and the amount of useful gas that can be recovered is reduced as compared with the embodiment of FIG.
[0023]
FIG. 7 shows the process repeated in the embodiment of FIG. In the process of the present embodiment, the gas that is sucked by the vacuum pump 2 and depressurized and discharged in the process shown in FIG. 2 is diffused into the atmosphere at normal pressure instead of being diffused into the atmosphere. In FIG. 7 (1), the air which is a mixed gas with the gas compressor 1 is pressurized to, for example, 2 kg / cm ² G, and filled with zeolite molecular sieve as the adsorbent 16 through the automatic valve 7 and the automatic valve 12. It introduces into A3 and the subadsorption tank 5, adsorbs and removes nitrogen gas, concentrates oxygen gas, and stores it in the product tank 6. On the other hand, the main adsorption tank B4 that has completed the adsorption is opened to the atmospheric pressure through the automatic valve 9.
[0024]
FIG. 7 (2) shows that a part of the concentrated oxygen gas is introduced from the product tank 6 into the main adsorption tank B4 while continuing the production of oxygen using the main adsorption tank A3 and the sub-adsorption tank 5, and the reverse flow Let it recycle. The amount of concentrated oxygen gas extracted is 0.8 to 1.5 times the amount of concentrated oxygen gas extracted as product gas, and the automatic valve 15 is opened for 10 to 30 seconds to perform cleaning regeneration.
[0025]
In FIG. 7 (3), the operation of the automatic valves 12 and 13 is switched on the outlet side of the main adsorption tank A3 and the main adsorption tank B4 in the state where the desorption regeneration of the main adsorption tank B4 is completed, and the auxiliary adsorption tank 5 is regenerated. Is communicated with the main adsorption tank B4, and a part of the concentrated oxygen gas is caused to flow backward from the product tank 6 through the automatic valve 13 to start boosting the main adsorption tank B4. On the other hand, on the inlet side of the main adsorption tank A3 and the main adsorption tank B4, the automatic valve 11 is opened to perform the pressure equalization operation on the inlet side, and the gas on the inlet side of the main adsorption tank A3 moves to the inlet side of the main adsorption tank B4. And recovered.
[0026]
FIG. 7 (4) shows the main adsorption tank B 4 with the inlet side connected to the gas compressor 1, the mixed gas from the gas compressor 1 from the inlet side, and the product tank 6 from the outlet side through the sub-adsorption tank 5. The concentrated oxygen gas is caused to flow backward through the automatic valve 13, and the pressure in the main adsorption tank B4 is started. On the other hand, on the inlet side of the main adsorption tank A3 and the main adsorption tank B4, the automatic valve 11 is opened to perform the pressure equalization operation on the inlet side, and the gas on the inlet side of the main adsorption tank A3 moves to the inlet side of the main adsorption tank B4. And recovered.
[0027]
In FIG. 7 (4), the main adsorption tank B4 is connected to the gas compressor 1 at the inlet side, the mixed gas from the gas compressor 1 is introduced from the inlet side, and from the product tank 6 through the auxiliary adsorption tank 5 from the outlet side. A part of the concentrated oxygen gas is caused to flow backward through the automatic valve 13, and the main adsorption tank B4 is increased to the adsorption pressure.
[0028]
In the conventional PSA method, there is a limit to the amount of generated gas collected during the pressure equalization operation at the upper part of the adsorption tank. However, in this embodiment, there is no need to perform the pressure equalization recovery operation as in the prior art. Since all product gas components are recovered in the main adsorption tank on the switched side, the product gas recovery rate can be greatly improved as compared with the conventional method.
[0029]
Further, in the conventional PSA method, there is a possibility that the downstream portion of the adsorption tank is contaminated with the gas desorbed by itself during the pressure equalizing operation, and the purity of the product gas is impaired. In the sub-adsorption tank 5 of the present embodiment, the gas always flows back from the downstream side to the upstream side except in the manufacturing process, so that a clean gas atmosphere is always obtained, and a product gas having a stable and high purity can be manufactured.
[0030]
Further, in this embodiment, the adsorption tank can be constituted by two main adsorption tanks and one sub adsorption tank without increasing the number of switching valves. Therefore, the pressure reduction or pressure increase is actually performed during the process of executing the PSA method. All that needs to be done is the main adsorption tank, and the time and power required for these strokes can be reduced. The volumes of the gas compressor 1 and the vacuum pump 2 can also be reduced.
[0031]
In this embodiment, since the adsorption tank is composed of two main adsorption tanks A3 and B4 and one sub adsorption tank 5, the amount of adsorbent required for filling is 5 to 15% as compared with the conventional two-tank PSA method. Can be reduced.
[0032]
As a result of the above, it is possible to significantly reduce both the equipment and operating costs, so that various industries and equipment that require gas adsorption separation improve operating efficiency and require gas separation and generation. Can greatly contribute to.
[0033]
【Example】
Example 1
Two main adsorption tanks A3 and B4 having a diameter of 200 mm and a height of 1100 mm, and a sub-adsorption tank 5 having a diameter of 150 mm and a height of 500 mm are filled with adsorbents 16, 17, and 18, respectively, with 5A zeolite molecular sieves manufactured by German Bayer. Then, the pressure of the air is increased to 0.5 kg / cm ² G by the gas compressor 1, and oxygen gas is adsorbed and separated by the configuration shown in FIG. Each stroke shown in FIG. 2 is 15 seconds for (1), 30 seconds for (2), 2 seconds for (3), 13 seconds for (4), and a total of 60 seconds. The operation was performed twice per cycle, ie 60 seconds × 2 = 120 seconds. Regeneration is performed by reducing the pressure to 180 mmHg with the vacuum pump 2 in 58 seconds. In the process (2), concentrated oxygen at a flow rate of 650 Nl / h was returned from the product tank 6 to the main adsorption tank where regeneration was performed, and washed for 30 seconds. As a result, a concentrated oxygen amount of 1400 Nl / h is obtained at a concentration of 93.5%, and the oxygen recovery amount is 58.7%.
[0034]
(Comparative Example 1)
As an example of a conventional two-tank system, according to JP-A-1-236914, an adsorption pressure of 500 mm water column and a regeneration pressure of 180 mmHg under almost the same operating conditions as in Example 1 have an oxygen concentration of 93.3% and an oxygen recovery rate of 55 .2%.
[0035]
(Example 2)
The two main adsorption tanks with a diameter of 200 mm and a height of 1100 mm and a secondary adsorption tank with a diameter of 150 mm and a height of 500 mm are filled with adsorbents 16, 17 and 18 with 5A zeolite molecular sieves manufactured by German Bayer, as shown in FIG. To separate oxygen gas. The pressure is increased to 2.0 kg / cm ² G by the gas compressor 1 and the air is introduced into the adsorption tank, and the operation is performed according to the process shown in FIG. In each stroke of FIG. 7, a total of 60 seconds is allocated for 18 seconds for the stroke (1), 30 seconds for the stroke (2), 2 seconds for the stroke (3), and 10 seconds for the stroke (4). An operation of 60 seconds × 2 = 120 seconds is performed per cycle. For regeneration, a part of the regeneration line is opened to the atmosphere, and atmospheric pressure desorption is performed. In step (2), 750 Nl / h of concentrated oxygen is caused to flow backward from the product tank 6 to the adsorption tank where regeneration is performed, and cleaning is performed for 30 seconds.
[0036]
As a result, the amount of concentrated oxygen is 13.0 Nl / h at a concentration of 93.0%, and the oxygen recovery rate is 35.7%.
[0037]
(Comparative Example 2)
As an example of a comparative two-tank system according to the conventional method, in Japanese Patent Laid-Open No. 1-236914, an adsorption pressure of 4.0 kg / cm ² G, which is almost the same operating condition as in Example 2, and an atmospheric pressure regeneration system, an oxygen concentration of 93 An oxygen recovery rate of 25% is obtained at 0.5%.
[0038]
【The invention's effect】
As described above, according to the present invention, the amount of adsorbent used can be reduced as compared with the conventional two-tank type, and the efficiency at the time of gas adsorption separation can be increased. Since the operation of switching the adsorbents in the two main adsorption tanks to adsorption separation and regeneration can be performed in the same manner as the conventional two-tank type, the efficiency of separation can be increased without complicating the operation. .
[Brief description of the drawings]
FIG. 1 is a piping system diagram showing a schematic configuration for adsorption separation according to an embodiment of the present invention.
FIG. 2 is a diagram showing an outline of a process constituting a ½ cycle in the embodiment of FIG. 1;
FIG. 3 is a time chart showing timings at which each automatic valve operates in the configuration of FIG. 1;
4 is a graph showing the reason why the recovery gas recovery amount increases in the configuration of FIG. 1 as compared with the case of the conventional pressure equalization operation.
FIG. 5 is a view showing a concept of distributing an adsorbent divided into a main adsorption tank and a sub-adsorption tank.
FIG. 6 is a piping system diagram according to another embodiment of the present invention.
7 is a diagram showing a configuration per cycle in the embodiment of FIG. 6. FIG.
FIG. 8 is a graph showing an example of a relationship between a gas absorption amount and a gas concentration with respect to an adsorbent in a conventional absorption tank.
FIG. 9 is a view showing a concept of a conventional pressure equalizing operation.
[Explanation of symbols]
1 Gas compressor 2 Vacuum pump 3 Main adsorption tank A
4 Main adsorption tank B
5 Sub-adsorption tank 6 Product tank 7-15 Automatic valve 16-18 Adsorbent 20 Control device

Claims (1)

In a method for separating components in a mixed gas using an adsorbent,
The adsorbent for performing the adsorption separation of gas is stored separately in two main adsorption tanks and one sub adsorption tank,
The following four stages of control are repeated in sequence, the main adsorption tanks are used alternately, and the secondary adsorption tank is always used for gas adsorption, while the adsorbent in the unused main adsorption tank is also regenerated. A mixed gas adsorption separation method.
(1) The mixed gas whose pressure has been increased to the adsorption pressure is led to one main adsorption tank and one sub-adsorption tank, and gas is adsorbed and separated mainly by the adsorbent in one main adsorption tank. While taking out the gas that passed through the adsorption tank as a product, depressurize the other main adsorption tank,
(2) While continuing the adsorption separation of the mixed gas in one main adsorption tank and the sub-adsorption tank, the gas taken out as a product in the other main adsorption tank is in the opposite direction to the mixed adsorption separation adsorption. To regenerate the adsorbent,
(3) Disconnect the connection between one main adsorption tank and the sub-adsorption tank, connect the other main adsorption tank and the sub-adsorption tank,
{Circle around (4)} Depressurization of one main adsorption tank is started, and the mixed gas is introduced into the other main adsorption tank and sub-adsorption tank to raise the pressure to the adsorption pressure.

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