Gas recovery apparatus and recovery method

Abstract

To provide a gas recovery apparatus and recovery method, enabling a reduction in the apparatus size.SOLUTION: A recovery apparatus employs pressure swing adsorption to recover a first gas from a mixed gas, which contains the first gas and a second gas, with the second gas having a higher adsorption capacity than the first gas. The recovery apparatus includes: an adsorption tower containing a first adsorbent that adsorbs the first gas and a second adsorbent that adsorbs the second gas; a first supply pipe for supplying a pressurized high-pressure gas containing the mixed gas to the adsorption tower; and a desorption part for separating a gas containing the first gas desorbed from the first adsorbent from the adsorption tower, and subsequently separating a gas containing the second gas desorbed from the second adsorbent from the adsorption tower.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a recovery device and a recovery method for recovering a specific gas from a mixed gas containing a plurality of gases. [Background technology]

[0002] Regarding technology for recovering a specific gas from a mixed gas containing multiple gases, Patent Document 1 discloses a prior art technology for recovering carbon dioxide from a mixed gas containing carbon dioxide and moisture, in which a dryer is placed upstream of a carbon dioxide recovery vessel and the mixed gas is cooled to about -20°C using the dryer to remove the moisture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-74657 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, a dryer that reduces the amount of moisture through condensation is placed upstream of a carbon dioxide recovery device, which has the problem of making the device larger.

[0005] The present invention has been made to solve this problem, and has an object to provide a gas recovery device and recovery method that can reduce the size of the device. [Means for solving the problem]

[0006] A first aspect for achieving this object is a recovery device that recovers the first gas from a mixed gas containing a first gas and a second gas having an adsorption capacity (amount of gas adsorbed per unit amount of adsorbent) greater than the first gas by pressure swing adsorption, and includes an adsorption tower that accommodates a first adsorbent to which the first gas is adsorbed and a second adsorbent to which the second gas is adsorbed, a first supply pipe that supplies high-pressure gas in which the mixed gas is pressurized to the adsorption tower, and a desorption section that separates from the adsorption tower a gas containing the first gas desorbed from the first adsorbent, and then separates from the adsorption tower a gas containing the second gas desorbed from the second adsorbent.

[0007] In the second aspect, in the first aspect, the pressure of the gas containing the second gas is lower than the pressure of the gas containing the first gas when separated from the adsorption tower.

[0008] A third aspect is the first or second aspect, further comprising a first desorption tube for separating a gas containing a first gas desorbed from the first adsorbent from the adsorption tower, and a second desorption tube for separating a gas containing a second gas desorbed from the second adsorbent from the adsorption tower, wherein the first supply pipe and the first desorption tube are connected to the adsorption tower, and the high-pressure gas supplied to the adsorption tower from the first supply pipe passes through the second adsorbent and enters the first adsorbent, and the first gas desorbed from the first adsorbent enters the first desorption tube without passing through the second adsorbent.

[0009] A fourth aspect is the first or second aspect, further comprising a second supply pipe that supplies low-pressure gas containing the first gas separated from the adsorption tower to the adsorption tower, and a cleaning section that supplies the low-pressure gas from the second supply pipe to the adsorption tower, and the low-pressure gas passes through the first adsorbent and enters the second adsorbent.

[0010] A fifth embodiment is the fourth embodiment, further comprising a second desorption tube that separates the low-pressure gas containing the second gas desorbed from the second adsorbent from the adsorption tower, the second supply pipe and the second desorption tube being connected to the adsorption tower, and the low-pressure gas containing the second gas desorbed from the second adsorbent entering the second desorption tube without passing through the first adsorbent.

[0011] A sixth aspect is any of the first to fifth aspects, further comprising a first desorption tube that separates a gas containing a first gas desorbed from the first adsorbent from the adsorption tower, a second desorption tube that separates a gas containing a second gas desorbed from the second adsorbent from the adsorption tower, a first vacuum pump connected to the first desorption tube, and a second vacuum pump connected to the second desorption tube.

[0012] A seventh aspect is the sixth aspect, wherein an ultimate pressure on the suction side of the first vacuum pump is higher than an ultimate pressure on the suction side of the second vacuum pump.

[0013] In an eighth aspect, in any one of the first to seventh aspects, the volume of the first adsorbent is greater than the volume of the second adsorbent.

[0014] A ninth aspect is a method for recovering the first gas from a mixed gas containing a first gas and a second gas having an adsorption capacity larger than the first gas by pressure swing adsorption, the method comprising: an adsorption step of supplying a high-pressure gas obtained by pressurizing the mixed gas to an adsorption tower containing a first adsorbent for adsorbing the first gas and a second adsorbent for adsorbing the second gas; and a desorption step of recovering the first gas desorbed from the first adsorbent and then separating the second gas desorbed from the second adsorbent from the adsorption tower. Effect of the Invention

[0015] According to the present invention, the second gas, which has a larger adsorption capacity than the first gas, is removed to recover the first gas. The part for removing the second gas can be made smaller, allowing the device to be made more compact. The desorption part separates the first gas, which has a small adsorption capacity and is easy to desorb, from the adsorption tower, and then separates the second gas, which has a large adsorption capacity and is difficult to desorb, from the adsorption tower, thereby reducing the amount of the second gas mixed into the recovered gas. [Brief description of the drawings]

[0016] [Figure 1] FIG. 2 is a piping diagram of a recovery device according to an embodiment. [Diagram 2] 1 shows the adsorption and desorption isotherms of a first gas and a second gas. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings, in which: Fig. 1 is a piping diagram of a recovery device 10 according to one embodiment.

[0018] The recovery device 10 utilizes pressure swing adsorption to recover the first gas from a mixed gas containing a first gas and a second gas having an adsorption capacity larger than that of the first gas. The recovery device 10 is exemplified by a device that recovers carbon dioxide from a mixed gas such as an exhaust gas containing carbon dioxide, moisture, nitrogen oxides, etc. In this case, the first gas is carbon dioxide, and the second gas is moisture or nitrogen oxides. The mixed gas is exemplified by exhaust gas from a power plant, a factory, a waste treatment facility, a natural gas field, an oil field, etc.

[0019] Another example of the recovery device 10 is a device that recovers nitrogen from a mixed gas such as air containing nitrogen, moisture, etc. In this case, the first gas is nitrogen and the second gas is moisture, and the recovery device 10 can recover nitrogen from air. In this recovery device 10, it is also possible to recover gas containing oxygen that was not recovered when recovering nitrogen from air.

[0020] The recovery system 10 includes adsorption towers 11, 12, 13, and 14, and a pressurizing device 18 that sets appropriate pressures in the adsorption towers 11, 12, 13, and 14. A first adsorbent 15 that adsorbs a first gas and a second adsorbent 16 that adsorbs a second gas are respectively contained in the adsorption towers 11, 12, 13, and 14.

[0021] The first adsorbent 15 and the second adsorbent 16 are appropriately selected according to the types of the first gas and the second gas contained in the mixed gas, so that the adsorption capacity of the second adsorbent 16 for the first gas is greater than the adsorption capacity of the first gas for the first adsorbent 15. Examples of the first adsorbent 15 and the second adsorbent 16 include activated carbon, silica gel, zeolite, molecular sieving carbon, mesoporous silica, metal-organic frameworks (MOFs), and porous coordination polymers (PCPs).

[0022] The first adsorbent 15 and the second adsorbent 16 are filled in the adsorption towers 11, 12, 13, and 14, respectively. The second adsorbent 16 is filled near the inlets of the adsorption towers 11, 12, 13, and 14, and the first adsorbent 15 is filled near the outlets of the adsorption towers 11, 12, 13, and 14. The volume of the first adsorbent 15 is larger than the volume of the second adsorbent 16. That is, the thickness of the layer of the first adsorbent 15 filled in the adsorption towers 11, 12, 13, and 14 is thicker than the thickness of the layer of the second adsorbent 16 filled in the adsorption towers 11, 12, 13, and 14.

[0023] The pressurizing device 18 is disposed in the first supply pipe 17. Examples of the pressurizing device 18 include a compressor and a blower. The first supply pipe 17 is a pipe branched into four, and the branched parts are connected to the inlets of the adsorption towers 11, 12, 13, and 14, respectively. The pressurizing device 18 pressurizes the mixed gas and sends it to the first supply pipe 17. The mixed gas (high-pressure gas) pressurized by the pressurizing device 18 is sent to the adsorption towers 11, 12, 13, and 14 through the branched parts of the first supply pipe 17.

[0024] A four-branched portion of an exhaust pipe 19 and a four-branched portion of a second desorption pipe 20 are respectively connected to the branched portion of the first supply pipe 17. A second vacuum pump 21 is disposed in the second desorption pipe 20.

[0025] The exhaust pipe 22 is a pipe branched into four, and the branched portions are respectively connected to the outlets of the adsorption towers 11, 12, 13, and 14. The exhaust pipe 22 has a function of exhausting, to the outside of the adsorption towers 11, 12, 13, and 14, components of the high-pressure gas that has entered the adsorption towers 11, 12, 13, and 14 from the first supply pipe 17 that are not adsorbed by the first adsorbent 15 or the second adsorbent 16.

[0026] A four-branched portion of first desorption pipe 23 and a four-branched portion of second supply pipe 26 are respectively connected to the branched portion of exhaust pipe 22. A first vacuum pump 24 and a tank 25 are disposed in first desorption pipe 23. Tank 25 is disposed in first desorption pipe 23 downstream of first vacuum pump 24. An upstream end of second supply pipe 26 is connected to tank 25.

[0027] The ultimate pressure on the suction side of the first vacuum pump 24 is higher than the ultimate pressure on the suction side of the second vacuum pump 21. The lower the ultimate pressure on the suction side (the closer to zero), the higher the vacuum that can be achieved; therefore, the second vacuum pump 21 can achieve a higher vacuum than the first vacuum pump 24. Also, the pressure on the discharge side of the first vacuum pump 24 can be higher than the pressure on the discharge side of the second vacuum pump 21. Furthermore, the pumping speed of the first vacuum pump 24 is higher than the pumping speed of the second vacuum pump 21.

[0028] The control valves 27, 28, 29, and 30 are disposed in the branched portions of the first supply pipe 17 for the adsorption towers 11, 12, 13, and 14. The control valves 31, 32, 33, and 34 are disposed in the branched portions of the exhaust pipe 19 for the adsorption towers 11, 12, 13, and 14. The control valves 35, 36, 37, and 38 are disposed in the branched portions of the second desorption pipe 20 for the adsorption towers 11, 12, 13, and 14.

[0029] The control valves 39, 40, 41, 42 are disposed in the branched portion of the exhaust pipe 22 for each of the adsorption towers 11, 12, 13, 14. The control valves 43, 44, 45, 46 are disposed in the branched portion of the first desorption pipe 23 for each of the adsorption towers 11, 12, 13, 14. The control valve 47 is disposed in the first desorption pipe 23 downstream of the tank 25. The control valves 48, 49, 50, 51 are disposed in the branched portion of the second supply pipe 26 for each of the adsorption towers 11, 12, 13, 14.

[0030] The control device 52 is a device for controlling the opening and closing of the adjustment valve 27-51. The control device 52 is equipped with a CPU, ROM, and RAM (none of which are shown). The ROM stores a program for opening and closing the adjustment valve 27-51. The CPU executes processing for opening and closing the adjustment valve 27-51 in the adsorption section 53, the cleaning section 54, and the desorption section 55 based on the program stored in the ROM. The adjustment valve 27-51 operates by receiving an electrical signal from the control device 52.

[0031] The control device 52 executes processes so that the adsorption step, cleaning step, first desorption step, and second desorption step proceed in each of the adsorption towers 11, 12, 13, and 14 in that order, and the four steps proceed in parallel in the adsorption towers 11, 12, 13, and 14. The control device 52 opens and closes the control valves 27-51 so that the first gas can be continuously recovered from the mixed gas, and stores the gas rich in the first gas in the tank 25. The adsorption section 53 executes a process to advance the adsorption step. The cleaning section 54 executes a process to advance the cleaning step. The desorption section 55 executes a process to advance the first desorption step through the second desorption step.

[0032] The operation of the recovery system 10 will be described below by taking as an example a case in which the adsorption step is carried out in the adsorption tower 11 in which the second desorption step has been completed, the cleaning step is carried out in the adsorption tower 12 in which the adsorption step has been completed, the first desorption step is carried out in the adsorption tower 13 in which the cleaning step has been completed, and the second desorption step is carried out in the adsorption tower 14 in which the first desorption step has been completed. The pressurizing device 18, the first vacuum pump 24, and the second vacuum pump 21 operate throughout the four steps.

[0033] In order to proceed with the adsorption process in the adsorption tower 11, the adsorption section 53 opens the control valves 27 and 39 and closes the other control valves. In the adsorption process, the high-pressure gas that has passed through the control valve 27 and entered the adsorption tower 11 from the first supply pipe 17 passes through the second adsorbent 16 and enters the first adsorbent 15. The second gas is adsorbed by the second adsorbent 16, and the first gas is adsorbed by the first adsorbent 15, and the off-gas, in which the partial pressures of the first gas and the second gas are lower than those of the high-pressure gas, passes through the control valve 39 and is discharged from the exhaust pipe 22 to the outside of the recovery device 10.

[0034] Figure 2 is an example of the adsorption and desorption isotherms of the first gas and the second gas. In Figure 2, the horizontal axis represents the partial pressure of the gas, and the vertical axis represents the adsorption capacity (amount of gas adsorbed per unit amount of adsorbent). Figure 2 shows that the adsorption capacity of the second gas to the second adsorbent is greater than the adsorption capacity of the first gas to the first adsorbent. The pressure (adsorption pressure) of the high-pressure gas in the adsorption tower 11 in the adsorption process is denoted as P3.

[0035] Returning to Fig. 1, the explanation will be given. During the adsorption process, while the high-pressure gas moves sequentially from the inlet to the outlet inside the adsorption tower 11, the second gas is adsorbed by the second adsorbent 16, and the first gas is adsorbed by the first adsorbent 15. Since the adsorption capacity of the second gas is larger than that of the first gas, the second gas is adsorbed and removed by the second adsorbent 16, and the concentration of the second gas contained in the high-pressure gas moving inside the first adsorbent 15 decreases. This makes it easier for the first gas to be adsorbed by the first adsorbent 15.

[0036] The cleaning section 54 opens the control valves 32, 49 to proceed with the cleaning process in the adsorption tower 12. The pressure in the adsorption tower 12, which is no longer supplied with high-pressure gas, drops to near atmospheric pressure when the control valves 32, 49 are opened. When the pressure in the adsorption tower 12 drops, a first gas corresponding to the difference between the adsorption capacity at pressure P3 (see FIG. 2) of the adsorption tower 12 in the adsorption process and the adsorption capacity at the lowered pressure is desorbed from the first adsorbent 15, and a second gas is desorbed from the second adsorbent 16.

[0037] In the cleaning process, the gas (low pressure gas) rich in the first gas present in the tank 25 is supplied to the adsorption tower 12 from the second supply pipe 26 through the control valve 49. The low pressure gas that enters the adsorption tower 12 from the second supply pipe 26 sequentially passes through the first adsorbent 15 and enters the second adsorbent 16. The unnecessary gas present in the adsorption tower 12 is pushed out by the low pressure gas flowing from the outlet to the inlet of the adsorption tower 12, passes through the control valve 32, and is discharged from the exhaust pipe 19 to the outside of the system of the recovery device 10. Since the low pressure gas is rich in the first gas, the concentration of the first gas increases in the adsorption tower 12 to which the low pressure gas is supplied, and the amount of the first gas adsorbed to the first adsorbent 15 increases. The cleaning process discharges unnecessary components that are not adsorbed to the first adsorbent 15 and the second adsorbent 16 to the outside of the system, thereby reducing the ratio of unnecessary components contained in the recovered gas and increasing the ratio of the first gas.

[0038] The desorption section 55 opens the control valves 33, 45 to proceed with the first desorption step in the adsorption tower 13. The low-pressure gas containing the first gas desorbed from the first adsorbent 15 is separated from the adsorption tower 13 by the first vacuum pump 24 and enters the tank 25 from the first desorption tube 23 through the control valve 45. Since the adsorption tower 13 is depressurized by the first vacuum pump 24, desorption of the first gas from the first adsorbent 15 and desorption of the second gas from the second adsorbent 16 proceed. If the pressure of the low-pressure gas separated from the adsorption tower 13 in the first desorption step is P2 (see FIG. 2), the first gas is desorbed from the first adsorbent 15 and recovered by an amount equal to the difference C1 between the adsorption capacity of the first gas at pressure P3 and the adsorption capacity at pressure P2.

[0039] In the first desorption step, the low-pressure gas containing the first gas desorbed from the first adsorbent 15 is separated from the adsorption tower 13 without passing through the second adsorbent 16 where a large amount of the second gas is present, and is recovered through the first desorption tube 23. Therefore, the amount of the second gas mixed into the recovered gas can be reduced.

[0040] Since the adsorption capacity of the second gas is larger than that of the first gas, the desorption rate of the second gas is smaller than that of the first gas. This makes it possible to reduce the amount of the second gas desorbed from the second adsorbent 16 mixed into the gas containing the first gas desorbed from the first adsorbent 15. Since the amount of the second gas contained in the gas entering the tank 25 can be reduced, a high concentration of the first gas can be stored in the tank 25. The gas in the tank 25 can be taken out by opening the control valve 47.

[0041] The desorption section 55 opens the control valves 38, 42 to proceed with the second desorption step in the adsorption tower 14. The gas containing the second gas desorbed from the second adsorbent 16 is separated from the adsorption tower 14 by the second vacuum pump 21, passes through the control valve 38, and is discharged from the second desorption pipe 20 to the outside of the system of the recovery device 10. If the pressure of the gas separated from the adsorption tower 14 in the second desorption step is P1 (see FIG. 2), the second gas can be removed by an amount equal to the difference C2 between the adsorption capacity of the second gas at pressure P3 and the adsorption capacity at pressure P1.

[0042] In the second desorption step, the gas containing the second gas desorbed from the second adsorbent 16 is separated from the adsorption tower 14 without passing through the first adsorbent 15, and is discharged from the second desorption tube 20. Since the amount of the second gas remaining in the first adsorbent 15 can be reduced, the amount of the second gas mixed in the gas when the gas containing the first gas desorbed from the first adsorbent 15 is recovered in the next first desorption step performed in the adsorption tower 14 can be reduced.

[0043] A portion of the first gas desorbed from the first adsorbent 15 in the first desorption step may remain in the adsorption tower 14 when the first desorption step is completed. In the second desorption step, the small amount of the first gas remaining in the adsorption tower 14 is separated from the adsorption tower 14 through the second adsorbent 16 by the second vacuum pump 21 and is discharged from the second desorption pipe 20 through the control valve 38 to the outside of the system of the recovery device 10.

[0044] The pressure P1 (see FIG. 2) of the gas separated from the adsorption tower 14 in the second desorption step is preferably set lower than the pressure P2 of the gas separated from the adsorption tower 13 in the first desorption step. When the pressure P1 decreases and the difference between the pressure P3 and the pressure P1 increases, the difference C2 increases, so that a large amount of the second gas is expelled from the second adsorbent 16, and the adsorption capacity of the second adsorbent 16 is largely restored. As a result, a large amount of the second gas can be adsorbed and removed by the second adsorbent 16 in the next adsorption step performed in the adsorption tower 14.

[0045] The desorption section 55 separates the first gas, which has a small adsorption capacity and is easily desorbed, from the adsorption tower 13 in the first desorption step, and then separates the second gas, which has a large adsorption capacity and is difficult to desorb, from the adsorption tower 14 in the second desorption step, thereby reducing the amount of the second gas desorbed from the second adsorbent 16 in the first desorption step and reducing the amount of the second gas mixed into the gas recovered in the first desorption step. This makes it possible to recover a high concentration of the first gas.

[0046] The recovery device 10 does not require a dryer that reduces the amount of moisture by condensation to be disposed upstream of the adsorption towers 11, 12, 13, and 14 as in the prior art, and therefore the device can be made smaller by the amount that the dryer can be omitted, and the power consumption rate can be reduced. Although the second adsorbent 16 to be filled in the adsorption towers 11, 12, 13, and 14 is necessary, the volume of the second adsorbent 16 is smaller than the volume of the first adsorbent 15, and therefore the increase in the volume of the adsorption towers 11, 12, 13, and 14 in which the second adsorbent 16 is filled can be reduced.

[0047] Since the concentration of the second gas contained in the mixed gas is lower than the concentration of the first gas, the volume of the second adsorbent 16 that adsorbs the second gas can be smaller than the volume of the first adsorbent 15 that adsorbs the first gas. Therefore, the increase in the volume of the adsorption towers 11, 12, 13, 14 in which the second adsorbent 16 is filled in addition to the first adsorbent 15 can be reduced.

[0048] Since the first vacuum pump 24 is disposed in the first desorption pipe 23 and the second vacuum pump 21 is disposed in the second desorption pipe 20, the amount of exhaust from each of the vacuum pumps 21 and 24 can be reduced compared to the case where one vacuum pump is connected to the first desorption pipe 23 and the second desorption pipe 20 to reduce the pressure in the adsorption towers 11, 12, 13, and 14. Since the vacuum pumps 21 and 24 can be made smaller, this is advantageous for miniaturizing the recovery device 10.

[0049] Since the ultimate pressure on the suction side of the first vacuum pump 24 arranged in the first desorption tube 23 is higher than the ultimate pressure on the suction side of the second vacuum pump 21 arranged in the second desorption tube 20, the pressure on the discharge side of the first vacuum pump 24 can be increased. If the temperature and mass of the gas are constant, the pressure of the gas in the tank 25 connected downstream of the first vacuum pump 24 can be increased, and the volume of the gas can be reduced, so that the tank 25 in which the gas is stored can be made smaller. A large amount of gas can be stored in the tank 25 of a constant volume. In addition, since the exhaust speed of the first vacuum pump 24 is higher than the exhaust speed of the second vacuum pump 21, the recovery speed of the first gas in the first desorption step can be increased.

[0050] The present invention has been described above based on an embodiment, but the present invention is in no way limited to the above embodiment, and it can be easily inferred that various improvements and modifications are possible within the scope of the present invention without departing from the spirit of the present invention.

[0051] For example, the piping system of the recovery device 10 is an example and can be set as appropriate. In the embodiment, the recovery device 10 is described as having four adsorption towers 11, 12, 13, and 14, but this is not necessarily limited to this. The number of adsorption towers can be set to one or more as appropriate.

[0052] In the embodiment, the adsorption towers 11, 12, 13, and 14 filled with the first adsorbent 15 and the second adsorbent 16 are arranged side by side, and the adsorption-regeneration cycle is performed by switching the control valve, but the present invention is not necessarily limited to this. It is of course possible to provide several chambers in one adsorption tower, fill the first adsorbent 15 and the second adsorbent 16 separately in those chambers, and perform the adsorption-regeneration cycle by using the first adsorbent 15 and the second adsorbent 16 in sequence.

[0053] In the embodiment, the recovery device 10 is described as sequentially performing the adsorption step, the washing step, the first desorption step, and the second desorption step, but the present invention is not necessarily limited to this. For example, it is of course possible to omit the washing step. By omitting the washing step, it is not necessary to return a portion of the first gas recovered in the tank 25 to the adsorption towers 11, 12, 13, and 14, and therefore the recovery rate of the first gas can be improved.

[0054] In the embodiment, the first gas is desorbed from the first adsorbent 15 using the first vacuum pump 24, and the second gas is desorbed from the second adsorbent 16 using the second vacuum pump 21, but this is not necessarily limited to the above. Depending on the types of the first gas and the second gas, it is naturally possible to desorb the first gas and the second gas from the adsorbent without using either of the vacuum pumps 21 and 24, or by using either of the vacuum pumps 21 and 24. Eliminating either or both of the vacuum pumps 21 and 24 is advantageous for reducing the size of the recovery device 10.

[0055] In the embodiment, a case has been described in which the gas containing the second gas is discharged from the second desorption tube 20 to the outside of the system of the recovery device 10, but this is not necessarily limited to this. When a tank is disposed downstream of the second vacuum pump 21 of the second desorption tube 20, nitrogen (first gas) is recovered from the air (mixed gas), and moisture (second gas) is discharged from the second desorption tube 20, it is naturally possible to store the gas containing moisture in the tank. Oxygen and moisture can be recovered by the tank. It is naturally possible to recover oxygen (first gas) and remove moisture (second gas) from the mixed gas containing oxygen and moisture in the tank using the recovery device 10. [Explanation of symbols]

[0056] 10 Recovery device 11,12,13,14 Adsorption tower 15 First adsorbent 16 Second Adsorbent 17 First supply pipe 20 Second Desorption Tube 21 Second Vacuum Pump 23 First Desorption Tube 24 First Vacuum Pump 26 Second supply pipe 54 Cleaning Section 55 Detachment part

Claims

1. A recovery apparatus for recovering a first gas from a mixed gas containing a first gas and a second gas having an adsorption capacity larger than that of the first gas by pressure swing adsorption, comprising: an adsorption tower containing a first adsorbent to which the first gas is adsorbed and a second adsorbent to which the second gas is adsorbed; a first supply pipe for supplying a high-pressure gas obtained by pressurizing the mixed gas to the adsorption tower; a desorption section that separates a gas containing the first gas desorbed from the first adsorbent from the adsorption tower, and then separates a gas containing the second gas desorbed from the second adsorbent from the adsorption tower.

2. 2. The recovery apparatus according to claim 1, wherein the pressure of the gas containing the second gas when separated from the adsorption tower is lower than the pressure of the gas containing the first gas.

3. a first desorption tube that separates the gas containing the first gas desorbed from the first adsorbent from the adsorption tower; a second desorption tube that separates the gas containing the second gas desorbed from the second adsorbent from the adsorption tower, the first supply pipe and the first desorption pipe are connected to the adsorption tower; the high-pressure gas supplied from the first supply pipe to the adsorption tower passes through the second adsorbent and enters the first adsorbent; 3. The recovery apparatus according to claim 1, wherein the first gas desorbed from the first adsorbent enters the first desorption tube without passing through the second adsorbent.

4. a second supply pipe that supplies a low-pressure gas containing the first gas separated from the adsorption tower to the adsorption tower; a cleaning unit that supplies the low-pressure gas from the second supply pipe to the adsorption tower, 3. The recovery system of claim 1 or 2, wherein the low pressure gas passes through the first adsorbent and enters the second adsorbent.

5. a second desorption tube that separates the low-pressure gas containing the second gas desorbed from the second adsorbent from the adsorption tower; the second supply pipe and the second desorption pipe are connected to the adsorption tower; 5. The recovery apparatus according to claim 4, wherein the low pressure gas containing the second gas desorbed from the second adsorbent enters the second desorption tube without passing through the first adsorbent.

6. a first desorption tube that separates the gas containing the first gas desorbed from the first adsorbent from the adsorption tower; a second desorption tube that separates the gas containing the second gas desorbed from the second adsorbent from the adsorption tower; a first vacuum pump connected to the first desorption tube; The recovery device according to claim 1 or 2, further comprising: a second vacuum pump connected to the second desorption tube.

7. 7. The recovery apparatus according to claim 6, wherein an ultimate pressure on the suction side of the first vacuum pump is higher than an ultimate pressure on the suction side of the second vacuum pump.

8. The recovery apparatus according to claim 1 or 2, wherein the first adsorbent has a volume larger than the second adsorbent.

9. 1. A method for recovering a first gas from a mixed gas comprising a first gas and a second gas having an adsorption capacity greater than that of the first gas by pressure swing adsorption, comprising: an adsorption step of supplying a high-pressure gas obtained by pressurizing the mixed gas to an adsorption tower that accommodates a first adsorbent for adsorbing the first gas and a second adsorbent for adsorbing the second gas; a desorption step of recovering the first gas desorbed from the first adsorbent and then separating the second gas desorbed from the second adsorbent from the adsorption tower.

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