Gas separation method and gas separation apparatus

Abstract

To provide a gas separation method and a gas separation apparatus capable of quickly obtaining a target gas having excellent concentration quality after restarting separation cycle.SOLUTION: In a gas separation method where a target gas is separated from a raw material gas by a separation cycle repeating an adsorption step to adsorb the target gas to the adsorption part by sending the raw material gas containing the target gas from a raw material gas storage tank and a separation step where the target gas adsorbed to the adsorption part is desorbed from the adsorption part by the absorption step, the target gas adsorbed by the adsorption step just before stopping from the adsorption part before stopping the separation cycle is desorbed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a gas separation method and a gas separation apparatus. [Background technology]

[0002] In the process of manufacturing semiconductor products such as semiconductor integrated circuits or display devices such as liquid crystal panels, plasma generated by high-frequency discharge in a rare gas atmosphere is used. Argon has traditionally been used as the rare gas in such processes, but krypton and xenon have been attracting attention in recent years for more advanced processes. In the field of lamps, argon has traditionally been used as the gas filled in light bulbs, but in recent years, high-value-added products using krypton or xenon have been manufactured to reduce power consumption and improve brightness. In the field of glass, argon has traditionally been used as the gas filled in double-glazed glass, but in recent years, high-value-added products using krypton have been manufactured to improve thermal insulation performance.

[0003] However, krypton and xenon are extremely rare and expensive gases due to their abundance in the air used as raw materials and the complexity of the separation process, and their use disrupts the supply-demand balance and significantly increases costs. In order to make the use of such gases economically viable, it is extremely important to separate and recover used rare gases at a high recovery rate and reuse them.

[0004] 2. Description of the Related Art Known methods for separating and recovering xenon or krypton at high concentrations and at high recovery rates include those that utilize pressure swing adsorption (PSA) (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2006-61831 A Summary of the Invention [Problem to be solved by the invention]

[0006] When a target gas such as xenon or krypton is separated from a raw gas by using a pressure swing adsorption separation method, heat is generated (temperature rise) due to the adsorption action in the adsorption section in the adsorption step, and heat is absorbed (temperature drop) due to the desorption action from the adsorption section in the separation step. Therefore, in the separation cycle, the temperature of the adsorption section periodically changes within a predetermined temperature change range. Since the upper limit of the above-mentioned predetermined temperature change range is usually higher than the environmental temperature, if the separation cycle is stopped, for example, at the completion of the adsorption step, the temperature of the adsorption section will decrease from the temperature at the time of stopping to the environmental temperature over time. If the separation cycle is resumed after the temperature of the adsorption section reaches the environmental temperature, the temperature change will start from a state in which the temperature change range of the adsorption section has shifted below the above-mentioned predetermined temperature change range, and the concentration quality of the separated target gas may decrease. It takes a very long time for the temperature change range that has shifted once to return to its original state.

[0007] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS An object of the present invention is to provide a gas separation method and gas separation apparatus which are capable of quickly obtaining a target gas with good concentration and quality after the separation cycle is restarted. [Means for solving the problem]

[0008] One aspect of the present invention is as follows.

[0009] [1] A gas separation method for separating a target gas from a raw gas by repeating an adsorption step of sending a raw gas containing a target gas from a raw gas storage tank to an adsorption unit to adsorb the target gas to the adsorption unit, and a separation step of desorbing the target gas adsorbed to the adsorption unit by the adsorption step from the adsorption unit and sending the target gas to a target gas storage tank and storing the target gas, The gas separation method comprises desorbing the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption section before stopping the separation cycle.

[0010] [2] The gas separation method according to [1], wherein the target gas adsorbed in the adsorption step immediately before stopping the separation cycle is desorbed from the adsorption section by reducing pressure to below atmospheric pressure before stopping the separation cycle.

[0011] [3] The gas separation method according to [1] or [2], wherein the target gas adsorbed in the adsorption step immediately before stopping the separation cycle is desorbed from the adsorption section until the temperature of the adsorption section becomes equivalent to the environmental temperature before stopping the separation cycle.

[0012] [4] the adsorption step includes passing the raw gas from the raw gas storage tank through the adsorption unit and the auxiliary adsorption unit in this order and sending the raw gas to a post-separation gas storage tank, thereby adsorbing the target gas into the adsorption unit and the auxiliary adsorption unit; The separation cycle includes a recovery step in which the target gas adsorbed in the auxiliary adsorption section by the adsorption step is desorbed from the auxiliary adsorption section, and the target gas is sent through the adsorption section to the raw material gas storage tank and stored therein, and the adsorption step, the separation step, and the recovery step are repeated in this order, The gas separation method according to any one of [1] to [3], wherein the target gas adsorbed in the adsorption step immediately before stopping the separation cycle is desorbed from the auxiliary adsorption section before stopping the separation cycle.

[0013] [5] The gas separation method according to [4], wherein the target gas adsorbed in the adsorption step immediately before the separation cycle is stopped is desorbed from the auxiliary adsorption section by reducing pressure to below atmospheric pressure before the separation cycle is stopped.

[0014] [6] The separation cycle includes a rinsing step in which the separated gas stored in the separated gas storage tank by the adsorption step is passed through the auxiliary adsorption section and the adsorption section in that order to desorb the target gas from the auxiliary adsorption section, and the target gas is sent to the raw gas storage tank and stored therein, and the adsorption step, separation step, recovery step and rinsing step are repeated in that order. The gas separation method described in [4] or [5].

[0015] [7] The separation cycle includes a purging step of adsorbing the target gas to the adsorption section by sending the target gas from the target gas storage tank to the adsorption section, and repeating the adsorption step, the purging step, and the separation step in this order. The gas separation method according to any one of [1] to [6], wherein the target gas adsorbed in the purge step immediately before stopping the separation cycle is desorbed from the adsorption section before stopping the separation cycle.

[0016] [8] a raw material gas storage tank for storing a raw material gas including a target gas; an adsorption section that adsorbs the target gas; a target gas storage tank for storing the target gas desorbed from the adsorption section; a control unit for separating the target gas from the raw gas by controlling a separation cycle that repeats an adsorption step of adsorbing the target gas to the adsorption unit by sending the raw gas from the raw gas storage tank to the adsorption unit, and a separation step of desorbing the target gas adsorbed to the adsorption unit by the adsorption step from the adsorption unit and sending the target gas to the target gas storage tank and storing the same, The control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit before stopping the separation cycle.

[0017] [9] A vacuum pump is provided. The control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit by reducing the pressure to below atmospheric pressure using the vacuum pump before stopping the separation cycle.

[0018]

[10] A thermometer for measuring the temperature of the adsorption section, The gas separation apparatus according to [8] or [9], wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit until the temperature of the adsorption unit measured by the thermometer becomes equivalent to the environmental temperature before stopping the separation cycle.

[0019]

[11] an auxiliary adsorption section that adsorbs the target gas; and a post-separation gas storage tank, the adsorption step includes passing the raw gas from the raw gas storage tank through the adsorption unit and the auxiliary adsorption unit in this order and sending the raw gas to the separated gas storage tank, thereby adsorbing the target gas into the adsorption unit and the auxiliary adsorption unit; The separation cycle includes a recovery step in which the target gas adsorbed in the auxiliary adsorption section by the adsorption step is desorbed from the auxiliary adsorption section, and the target gas is sent through the adsorption section to the raw material gas storage tank and stored therein, and the adsorption step, the separation step, and the recovery step are repeated in this order, The gas separation apparatus according to any one of [8] to

[10] , wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the auxiliary adsorption unit before stopping the separation cycle.

[0020]

[12] An auxiliary vacuum pump is provided. The gas separation apparatus according to

[11] , wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the auxiliary adsorption unit by reducing the pressure to below atmospheric pressure using the auxiliary vacuum pump before stopping the separation cycle. Effect of the Invention

[0021] According to the present invention, it is possible to provide a gas separation method and a gas separation apparatus that can quickly obtain a target gas with good concentration and quality after the separation cycle is restarted. [Brief description of the drawings]

[0022] [Figure 1]FIG. 2 is an explanatory diagram illustrating a state when an adsorption step (A) and a separation step (B) are performed in the gas separation method according to the first embodiment of the present invention. [Diagram 2] FIG. 2 is an explanatory diagram for explaining a state in which a recovery step (B) is performed while continuing the adsorption step (A) from the state shown in FIG. 1. [Diagram 3] FIG. 3 is an explanatory diagram for explaining a state in which a rinsing step (B) is performed while continuing the adsorption step (A) from the state shown in FIG. 2. [Figure 4] FIG. 4 is an explanatory diagram for explaining a state when a purge step (A) and a pressure equalization step (B) are performed from the state shown in FIG. 3. [Diagram 5] FIG. 5 is an explanatory diagram for explaining the state when a separation step (A) and an adsorption step (B) are performed from the state shown in FIG. 4. [Figure 6] FIG. 6 is an explanatory diagram for explaining a state in which the recovery step (A) is performed while the adsorption step (B) is continued from the state shown in FIG. 5. [Figure 7] FIG. 7 is an explanatory diagram for explaining a state in which a rinsing step (A) is performed while continuing the adsorption step (B) from the state shown in FIG. 6. [Figure 8] FIG. 8 is an explanatory diagram for explaining a state when a pressure equalization step (A) and a purging step (B) are performed from the state shown in FIG. 7. [Figure 9] FIG. 11 is an explanatory diagram illustrating a state when a separation cycle is stopped in a gas separation method according to a second embodiment of the present invention. [Figure 10] FIG. 11 is an explanatory diagram illustrating a state when a separation cycle is stopped in a gas separation method according to a third embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] As shown in Figures 1 to 8, in the first embodiment of the present invention, the gas separation method is a gas separation method in which a target gas is separated from a raw material gas by a separation cycle (A) that repeats an adsorption step (A) in which a raw material gas containing a target gas is sent from a raw material gas storage tank 1 to an adsorption section (A) 10A to adsorb the target gas to the adsorption section (A) 10A, as shown by a thick solid line in Figures 1 to 3, and a separation step (A) in which the target gas adsorbed in the adsorption section (A) 10A by the adsorption step (A) is desorbed from the adsorption section (A) 10A (for example, by reducing pressure) and sent to a target gas storage tank 2 for storage, as shown by a thick solid line in Figure 5. Before stopping the separation cycle (A), the target gas adsorbed in the adsorption step (A) immediately before the stop is desorbed from the adsorption section (A) 10A. The method of "desorbing the target gas adsorbed in the adsorption step (A) immediately before stopping the separation cycle (A) from the adsorption section (A) 10A before stopping the separation cycle (A)" is not particularly limited, and may be, for example, a separation step (A) performed before stopping the separation cycle (A), a separation step (A) performed before stopping the separation cycle (A) and then a recovery step (A) performed, a step of desorbing the target gas adsorbed to the adsorption section (A) 10A by the adsorption step (A) from the adsorption section (A) 10A and sending it to the raw gas storage tank 1 for storage before stopping the separation cycle (A) or, although not shown in the figure, a step of desorbing the target gas from the adsorption section (A) 10A and discharging it to the outside before stopping the separation cycle (A).

[0025] When the environmental temperature is below the lower limit of the temperature change range, which is the range of the temperature of the adsorption unit (A) 10A that changes periodically in the separation cycle (A), the target gas adsorbed in the adsorption step (A) immediately before the separation cycle (A) is desorbed from the adsorption unit (A) 10A before stopping the separation cycle (A), thereby suppressing a downward shift in the temperature change range in the adsorption unit (A) 10A at the time of restarting the separation cycle (A). In addition, when the environmental temperature is lower than the upper limit and higher than the lower limit of the temperature change range, the target gas adsorbed in the adsorption step (A) immediately before the separation cycle (A) is desorbed from the adsorption unit (A) 10A before stopping the separation cycle (A), thereby suppressing a downward shift in the temperature change range in the adsorption unit (A) 10A at the time of restarting the separation cycle (A). Therefore, according to the above configuration, a gas separation method that can obtain a target gas with good concentration quality immediately after the separation cycle (A) is restarted can be realized.

[0026] The gas separation method may be configured to desorb the target gas adsorbed in the adsorption step (A) immediately before the separation cycle (A) is stopped from the adsorption section (A) 10A by reducing the pressure to below atmospheric pressure before the separation cycle (A) is stopped. According to the above configuration, the temperature of the adsorption section (A) 10A at the time of stopping the separation cycle (A) can be easily reduced to approach the environmental temperature, so that the temperature change of the adsorption section (A) 10A over time after the stop can be suppressed, and as a result, the downward shift of the temperature change range in the adsorption section (A) 10A at the time of restarting the separation cycle (A) can be suppressed. The method of "desorbing by reducing the pressure to below atmospheric pressure" is not particularly limited, and for example, a vacuum pump 6 may be used as in the second embodiment shown in FIG. 9.

[0027] The gas separation method may be configured such that, before the separation cycle (A) is stopped, the target gas adsorbed in the adsorption step (A) immediately before the stop is desorbed from the adsorption section (A) 10A until the temperature of the adsorption section (A) 10A becomes equal to the environmental temperature (for example, by reducing pressure). With this configuration, the temperature change of the adsorption section (A) 10A over time after the stop can be further suppressed, and as a result, the downward shift of the temperature change range in the adsorption section (A) 10A at the time of restarting the separation cycle (A) can be further suppressed.

[0028] In the adsorption step (A), as shown by the thick solid lines in Figs. 1 to 3, the raw gas is passed from the raw gas storage tank 1 through the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A in this order and sent to the post-separation gas storage tank 3, thereby adsorbing the target gas to the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A. In the separation cycle (A), as shown by the thick solid lines in Fig. 6, the target gas adsorbed to the auxiliary adsorption section (A) 11A by the adsorption step (A) is desorbed from the auxiliary adsorption section (A) 11A and sent through the adsorption section (A) 10A to the raw gas storage tank 1 for storage. The adsorption step (A), separation step (A) and recovery step (A) are repeated in this order. In the gas separation method, before stopping the separation cycle (A), the target gas adsorbed in the adsorption step (A) immediately before stopping is desorbed from the auxiliary adsorption section (A) 11A. According to the above configuration, by using the auxiliary adsorption section (A) 11A in combination, a high-concentration separated gas with a high target gas removal rate can be easily obtained from the separated gas storage tank 3. Moreover, by "desorbing the target gas adsorbed in the adsorption step (A) immediately before stopping the separation cycle (A) from the auxiliary adsorption section (A) 11A before stopping the separation cycle (A)" as described above, it is possible to suppress a downward shift in the temperature change range in the auxiliary adsorption section (A) 11A at the time of restarting the separation cycle (A), so that a target gas with good concentration quality can be obtained promptly after restarting the separation cycle (A). The method of "desorbing the target gas adsorbed in the adsorption step (A) immediately before stopping the separation cycle (A) from the auxiliary adsorption section (A) 11A before stopping the separation cycle (A)" is not particularly limited, and for example, the recovery step (A) may be performed before stopping the separation cycle (A), or, although not shown, a step of desorbing the target gas from the auxiliary adsorption section (A) 11A before stopping the separation cycle (A) and recovering it in the raw gas storage tank 1 without passing it through the adsorption section (A) 10A may be performed, or, although not shown, a step of desorbing the target gas from the auxiliary adsorption section (A) 11A and discharging it to the outside before stopping the separation cycle (A).

[0029] In the gas separation method, before the separation cycle (A) is stopped, the target gas adsorbed in the adsorption step (A) immediately before the separation cycle (A) is stopped is desorbed from the auxiliary adsorption section (A) 11A by reducing the pressure to below atmospheric pressure. According to the above configuration, the temperature of the auxiliary adsorption section (A) 11A at the time when the separation cycle (A) is stopped can be easily reduced to approach the environmental temperature, so that the temperature change of the auxiliary adsorption section (A) 11A over time after the stop can be suppressed, and as a result, the downward shift of the temperature change range in the auxiliary adsorption section (A) 11A at the time when the separation cycle (A) is restarted can be suppressed. The method of "desorption by reducing the pressure to below atmospheric pressure" is not particularly limited, and for example, an auxiliary vacuum pump 7 may be used as in the third embodiment shown in FIG. 10.

[0030] 7, the separation cycle (A) has a rinse step (A) in which the separated gas stored in the separated gas storage tank 3 by the adsorption step (A) is passed through the auxiliary adsorption section (A) 11A and the adsorption section (A) 10A in this order to desorb the target gas from the auxiliary adsorption section (A) 11A and send it to the raw gas storage tank 1 for storage, and the adsorption step (A), separation step (A), recovery step (A), and rinse step (A) are repeated in this order. According to the above configuration, the recovery rate of the target gas can be increased.

[0031] As shown by the thick solid line in Fig. 4, the separation cycle (A) has a purge step (A) in which the target gas is sent from the target gas storage tank 2 to the adsorption unit (A) 10A to adsorb the target gas to the adsorption unit (A) 10A, and the adsorption step (A), purge step (A), and separation step (A) are repeated in this order, and the gas separation method desorbs the target gas adsorbed in the purge step (A) immediately before stopping the separation cycle (A) from the adsorption unit (A) 10A before stopping the separation cycle (A). According to the above configuration, the purge step (A) makes it easy to obtain a high concentration of target gas from the target gas storage tank 2, and furthermore, by "desorbing the target gas adsorbed in the purge step (A) immediately before stopping the separation cycle (A) from the adsorption unit (A) 10A before stopping the separation cycle (A)", it is possible to suppress a downward shift in the temperature change range in the adsorption unit (A) 10A at the time of resuming the separation cycle (A).

[0032] As shown in FIG. 1 to FIG. 8, the gas separation apparatus in this embodiment includes a raw gas storage tank 1 for storing raw gas containing a target gas, an adsorption section (A) 10A for adsorbing the target gas, a target gas storage tank 2 for storing the target gas desorbed from the adsorption section (A) 10A, and a control section for controlling a separation cycle (A) that repeats an adsorption step (A) in which the raw gas is sent from the raw gas storage tank 1 to the adsorption section (A) 10A to adsorb the target gas to the adsorption section (A) 10A, and a separation step (A) in which the target gas adsorbed to the adsorption section (A) 10A by the adsorption step (A) is desorbed from the adsorption section (A) 10A and sent to the target gas storage tank 2 for storage. The control section separates the target gas from the raw gas by controlling the separation cycle (A). Before stopping the separation cycle (A), the control section desorbs the target gas adsorbed in the adsorption step (A) immediately before stopping from the adsorption section (A) 10A. According to the above configuration, it is possible to realize a gas separation apparatus that can quickly obtain a target gas with good concentration and quality after the separation cycle (A) is restarted.

[0033] 9, the gas separation apparatus may have a vacuum pump 6, and the control unit may be configured to desorb the target gas adsorbed in the adsorption step (A) immediately before stopping the separation cycle (A) from the adsorption unit (A) 10A by reducing the pressure to below atmospheric pressure using the vacuum pump 6. With this configuration, it is possible to suppress a downward shift in the temperature change range in the adsorption unit (A) 10A when the separation cycle (A) is restarted.

[0034] The gas separation apparatus may have a thermometer (A) TA for measuring the temperature of the adsorption section (A) 10A, and the control section may be configured to desorb the target gas adsorbed in the adsorption step (A) immediately before stopping the separation cycle (A) from the adsorption section (A) 10A until the temperature of the adsorption section (A) 10A measured by the thermometer (A) TA becomes equal to the environmental temperature before stopping the separation cycle (A). With this configuration, it is possible to further suppress a downward shift in the temperature change range in the adsorption section (A) 10A when the separation cycle (A) is restarted.

[0035] The gas separation apparatus has an auxiliary adsorption section (A) 11A that adsorbs a target gas, and a post-separation gas storage tank 3. In the adsorption step (A), the raw gas is sent from the raw gas storage tank 1 through the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A in this order to the post-separation gas storage tank 3, thereby adsorbing the target gas to the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A. In the separation cycle (A), a recovery step (A) is included in which the target gas adsorbed in the auxiliary adsorption section (A) 11A by the adsorption step (A) is desorbed from the auxiliary adsorption section (A) 11A and sent through the adsorption section (A) 10A to the raw gas storage tank 1 for storage. The adsorption step (A), separation step (A) and recovery step (A) are repeated in this order. Before stopping the separation cycle (A), the control section desorbs the target gas adsorbed in the adsorption step (A) immediately before stopping from the auxiliary adsorption section (A) 11A. According to the above configuration, by using the auxiliary adsorption section (A) 11A in combination, it is possible to easily obtain high-concentration separated gas with a high target gas removal rate from the separated gas storage tank 3, and further, it is possible to obtain target gas with good concentration quality quickly after the separation cycle (A) is resumed.

[0036] 10, the gas separation apparatus has an auxiliary vacuum pump 7, and before stopping the separation cycle (A), the control unit desorbs the target gas adsorbed in the adsorption step (A) immediately before stopping from the auxiliary adsorption section (A) 11A by reducing the pressure to below atmospheric pressure using the auxiliary vacuum pump 7. With this configuration, it is possible to suppress a downward shift in the temperature change range in the auxiliary adsorption section (A) 11A when the separation cycle (A) is restarted.

[0037] As shown in FIGS. 1 to 8, the gas separation apparatus in this embodiment includes a raw material gas storage tank 1 for storing raw material gas containing a target gas, an adsorption section (A) 10A for adsorbing the target gas, an adsorption section (B) 10B for adsorbing the target gas, a target gas storage tank 2 for storing the target gas desorbed from each of the adsorption section (A) 10A and the adsorption section (B) 10B, a separation cycle (A) in which an adsorption step (A) of sending raw material gas from the raw material gas storage tank 1 to the adsorption section (A) 10A to adsorb the target gas in the adsorption section (A) 10A and a separation step (A) of desorbing the target gas adsorbed in the adsorption section (A) 10A by the adsorption step (A) from the adsorption section (A) 10A and sending it to the target gas storage tank 2 for storage therein, and A gas separation device having a control unit that separates the target gas from the raw material gas by controlling a separation cycle (B) that repeats an adsorption step (B) in which a raw material gas is sent to the adsorption unit (B) 10B to adsorb a target gas into the adsorption unit (B) 10B, and a separation step (B) in which the target gas adsorbed into the adsorption unit (B) 10B by the adsorption step (B) is desorbed from the adsorption unit (B) 10B and sent to a target gas storage tank 2 for storage. Before stopping the separation cycle (A) and the separation cycle (B), the control unit desorbs from the adsorption unit (A) 10A the target gas adsorbed in the adsorption step (A) immediately before the stopping, and / or desorbs from the adsorption unit (B) 10B the target gas adsorbed in the adsorption step (B) immediately before the stopping. According to the above configuration, by appropriately shifting the separation cycle (A) and the separation cycle (B) from each other, it is possible to realize a gas separation device that can efficiently separate the target gas and can quickly obtain a target gas of good concentration quality after the separation cycle (A) and the separation cycle (B) are resumed.

[0038] The gas separation apparatus has an auxiliary adsorption section (B) 11B that adsorbs the target gas. The separation cycle (B) has a purge step (B) in which the target gas is sent from the target gas storage tank 2 to the adsorption section (B) 10B to adsorb the target gas in the adsorption section (B) 10B, as shown by a thick dashed line in FIG. 8. The separation cycle (A) has a purge step (A) in which the target gas is sent from the target gas storage tank 2 to the adsorption section (A) 10A to adsorb the target gas in the adsorption section (A) 10A, as shown by a thick solid line in FIG. 4. As shown in Fig. 1, the system includes an equal pressure pressurization step (A) in which the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A are pressurized by gas flowing out from the adsorption section (B) 10B and the auxiliary adsorption section (B) 11B in the purge step (B), and the adsorption step (A), purge step (A), separation step (A) and equal pressure pressurization step (A) are repeated in this order, and the control section desorbs the target gas adsorbed in the purge step (A) immediately before stopping the separation cycle (A) from the adsorption section (A) 10A before stopping the separation cycle (A). According to the above configuration, the purge step (A) makes it easy to obtain a high concentration of target gas from the target gas storage tank 2, and furthermore, it is possible to suppress a downward shift in the temperature change range in the adsorption section (A) 10A at the time of restarting the separation cycle (A). In addition, the pressure equalization step (A) enables the target gas contained in the gas flowing out from the adsorption section (B) 10B in the purging step (B) to be adsorbed by the adsorption section (A) 10A (and the auxiliary adsorption section (A) 11A), thereby increasing the recovery rate of the target gas.

[0039] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be modified in various ways without departing from the gist of the present invention. EXAMPLES

[0040] <Comparative Example> Using the gas separation apparatus of the first embodiment, separation cycle (A) and separation cycle (B) were carried out under the valve control shown in Table 1. The conditions at that time were as follows.

[0041] Gas introduced from outside the equipment to the raw gas storage tank 1: a mixture of xenon and argon gas (xenon concentration 10%) 2.0L / min (all below at 0℃ and atmospheric pressure) Highly adsorbed component (target gas): Xenon 0.2L / min Hardly adsorbed components: Argon 1.8L / min Adsorption section (A) 10A, adsorption section (B) 10B, auxiliary adsorption section (A) 11A, auxiliary adsorption section (B) 11B: 1.5 kg of activated carbon as an adsorbent is filled in a stainless steel tube 80A (inner diameter 83.1 mm) to a height of 500 mm. Compressor 4: Diaphragm compressor 20L / min Compressor 5: Diaphragm compressor 2.0L / min

[0042] [Table 1]

[0043] After 48 hours of continuous operation under the above operating conditions, the argon concentration discharged from the post-separation gas storage tank 3 and the xenon concentration discharged from the target gas storage tank 2 stabilized almost constant. The results are as follows: Argon concentration in xenon: 443ppm → Product xenon concentration: 99.95% Xenon concentration in argon: 387 ppm → Xenon recovery rate: 99.6% Temperature change of adsorption part (A) 10A and adsorption part (B) 10B: 26℃~38℃ Temperature change of auxiliary adsorption part (A) 11A and auxiliary adsorption part (B) 11B: 22℃~26℃ Environmental temperature 24℃

[0044] Thereafter, the operation was stopped when the adsorption section (A) 10A and the auxiliary adsorption section (A) 11A completed the equalization and pressurization step (A). The temperatures of each adsorption section at that time were as follows: Adsorption part (A) 10A 26.2℃ Adsorption part (B) 10B 37.5℃ Auxiliary adsorption part (A) 11A 22.8℃ Auxiliary adsorption part (B) 11B 25.8℃

[0045] After 12 hours of shutdown, the temperature of each adsorption section reached approximately 24°C. After that, the temperature changes of each adsorption section immediately after restarting the operation are as follows: Adsorption part (A) 10A 26~42℃ Adsorption part (B) 10B 7~25℃ Auxiliary adsorption part (A) 11A 22~26℃ Auxiliary adsorption part (B) 11B 18~22℃

[0046] After restarting the operation, it took 24 hours for the temperature change of each adsorption section to become equal to the temperature change before the shutdown. It also took 27 hours for the argon concentration extracted from the separated gas storage tank 3 and the xenon concentration extracted from the target gas storage tank 2 to become equal to the concentrations before the shutdown.

[0047] <Example 1> The operation was carried out as described in the comparative example, and was stopped when adsorption section (A) 10A and auxiliary adsorption section (A) 11A completed the equalization pressurization step (A), and then valve V11 was opened to release the highly adsorbable component in adsorption section (B) 10B into target gas storage tank 2. The temperatures of each adsorption section after the above operation were as follows: Adsorption part (A) 10A 26.1℃ Adsorption part (B) 10B 32.3℃ Auxiliary adsorption part (A) 11A 22.6℃ Auxiliary adsorption part (B) 11B 25.9℃

[0048] After 12 hours of shutdown, the temperature of each adsorption section reached approximately 24°C. After that, the temperature changes of each adsorption section immediately after restarting the operation are as follows: Adsorption part (A) 10A 26~42℃ Adsorption part (B) 10B 13~32℃ Auxiliary adsorption part (A) 11A 22~26℃ Auxiliary adsorption part (B) 11B 18~22℃

[0049] After restarting the operation, it took 18 hours for the temperature change of each adsorption section to become equivalent to the temperature change before the shutdown. In addition, it took 22 hours for the argon concentration extracted from the separated gas storage tank 3 and the xenon concentration extracted from the target gas storage tank 2 to become equivalent to the concentrations before the shutdown.

[0050] <Example 2> The operation was carried out as described in the comparative example, and was stopped when adsorption section (A) 10A and auxiliary adsorption section (A) 11A completed the pressure equalization step (A), after which valve V11 was opened to release the strongly adsorbed component in adsorption section (B) 10B into target gas storage tank 2, and then valve V11 was closed and valves V6 and V13 were opened to release the strongly adsorbed component and weakly adsorbed component in auxiliary adsorption section (B) 11B into raw gas storage tank 1 via adsorption section (B) 10B. The temperatures of each adsorption section after the above operations were as follows: Adsorption part (A) 10A 26.2℃ Adsorption part (B) 10B 29.3℃ Auxiliary adsorption part (A) 11A 22.7℃ Auxiliary adsorption part (B) 11B 24.5℃

[0051] After 12 hours of shutdown, the temperature of each adsorption section reached approximately 24°C. After that, the temperature changes of each adsorption section immediately after restarting the operation are as follows: Adsorption part (A) 10A 26~42℃ Adsorption part (B) 10B 15~33℃ Auxiliary adsorption part (A) 11A 22~26℃ Auxiliary adsorption part (B) 11B 20~25℃

[0052] After restarting the operation, it took 16 hours for the temperature change of each adsorption section to become equivalent to the temperature change before the shutdown. In addition, it took 21 hours for the argon concentration extracted from the separated gas storage tank 3 and the xenon concentration extracted from the target gas storage tank 2 to become equivalent to the concentrations before the shutdown.

[0053] <Example 3> The operation was carried out as described in the comparative example, and was stopped when adsorption section (A) 10A and auxiliary adsorption section (A) 11A completed the pressure equalization step (A), and then valve V11 was opened to release the highly adsorbable components in adsorption section (B) 10B into target gas storage tank 2, and the highly adsorbable components were further released using vacuum pump 6 until the temperature in adsorption section (B) 10B reached approximately 24° C. The temperatures of each adsorption section and the pressure in adsorption column adsorption section (B) 10B after the above operation were as follows: Adsorption part (A) 10A 26.1℃ Adsorption part (B) 10B 23.8℃ Auxiliary adsorption part (A) 11A 22.7℃ Auxiliary adsorption part (B) 11B 25.9℃ Pressure at suction part (B) 10B: -40kPaG

[0054] After that, the temperature changes in each adsorption section immediately after restarting operation are as follows. Adsorption part (A) 10A 26~42℃ Adsorption part (B) 10B 25~39℃ Auxiliary adsorption part (A) 11A 22~26℃ Auxiliary adsorption part (B) 11B 18~22℃

[0055] After restarting the operation, it took 3 hours for the temperature change of each adsorption section to become equivalent to the temperature change before the shutdown. In addition, it took 6 hours for the argon concentration extracted from the separated gas storage tank 3 and the xenon concentration extracted from the target gas storage tank 2 to become equivalent to the concentrations before the shutdown. [Explanation of symbols]

[0056] 1. Raw gas storage tank 2. Target gas storage tank 3 Post-separation gas storage tank 4~5 Compressor 6. Vacuum Pump 7 Auxiliary Vacuum Pump 10A Adsorption part (A) 10B Adsorption part (B) 11A Auxiliary suction part (A) 11B Auxiliary suction part (B) TA thermometer (A) TB thermometer (B) V1~15 valves

Claims

1. A gas separation method for separating a target gas from a raw gas by repeating an adsorption step of sending a raw gas containing a target gas from a raw gas storage tank to an adsorption unit to adsorb the target gas to the adsorption unit, and a separation step of desorbing the target gas adsorbed to the adsorption unit by the adsorption step from the adsorption unit and sending the target gas to a target gas storage tank and storing the target gas, The gas separation method comprises desorbing the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption section before stopping the separation cycle.

2. The gas separation method according to claim 1 , wherein before the separation cycle is stopped, the target gas adsorbed in the adsorption step immediately before the stop is desorbed from the adsorption section by reducing pressure to below atmospheric pressure.

3. The gas separation method according to claim 1, wherein before the separation cycle is stopped, the target gas adsorbed in the adsorption step immediately before the stop is desorbed from the adsorption section until the temperature of the adsorption section becomes equivalent to an environmental temperature.

4. the adsorption step includes passing the raw gas from the raw gas storage tank through the adsorption unit and the auxiliary adsorption unit in this order and sending the raw gas to a post-separation gas storage tank, thereby adsorbing the target gas into the adsorption unit and the auxiliary adsorption unit; The separation cycle includes a recovery step in which the target gas adsorbed in the auxiliary adsorption section by the adsorption step is desorbed from the auxiliary adsorption section, and the target gas is sent through the adsorption section to the raw material gas storage tank and stored therein, and the adsorption step, the separation step, and the recovery step are repeated in this order, The gas separation method according to claim 1 , further comprising the step of desorbing the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the auxiliary adsorption section before stopping the separation cycle.

5. The gas separation method according to claim 4, wherein before the separation cycle is stopped, the target gas adsorbed in the adsorption step immediately before the stop is desorbed from the auxiliary adsorption section by reducing pressure to below atmospheric pressure.

6. 5. The gas separation method according to claim 4, wherein the separation cycle includes a rinsing step in which the separated gas stored in the separated gas storage tank by the adsorption step is passed through the auxiliary adsorption section and the adsorption section in this order to desorb the target gas from the auxiliary adsorption section and send it to the raw gas storage tank for storage, and the adsorption step, separation step, recovery step and rinsing step are repeated in this order.

7. The separation cycle includes a purging step of adsorbing the target gas to the adsorption section by sending the target gas from the target gas storage tank to the adsorption section, and repeating the adsorption step, the purging step, and the separation step in this order. The gas separation method according to claim 1 , further comprising the steps of: desorbing the target gas adsorbed in the purging step immediately before stopping the separation cycle from the adsorption section before stopping the separation cycle.

8. a raw material gas storage tank for storing a raw material gas including a target gas; an adsorption section that adsorbs the target gas; a target gas storage tank for storing the target gas desorbed from the adsorption section; a control unit for separating the target gas from the raw gas by controlling a separation cycle that repeats an adsorption step of adsorbing the target gas to the adsorption unit by sending the raw gas from the raw gas storage tank to the adsorption unit, and a separation step of desorbing the target gas adsorbed to the adsorption unit by the adsorption step from the adsorption unit and sending the target gas to the target gas storage tank and storing the same, The control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit before stopping the separation cycle.

9. A vacuum pump is provided. The gas separation apparatus according to claim 8, wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit by reducing the pressure to below atmospheric pressure using the vacuum pump before stopping the separation cycle.

10. A thermometer for measuring the temperature of the adsorption section, The gas separation apparatus according to claim 8, wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the adsorption unit until the temperature of the adsorption unit measured by the thermometer becomes equivalent to an environmental temperature before stopping the separation cycle.

11. an auxiliary adsorption section that adsorbs the target gas; and a post-separation gas storage tank, the adsorption step includes passing the raw gas from the raw gas storage tank through the adsorption unit and the auxiliary adsorption unit in this order and sending the raw gas to the separated gas storage tank, thereby adsorbing the target gas into the adsorption unit and the auxiliary adsorption unit; The separation cycle includes a recovery step in which the target gas adsorbed in the auxiliary adsorption section by the adsorption step is desorbed from the auxiliary adsorption section, and the target gas is sent through the adsorption section to the raw material gas storage tank and stored therein, and the adsorption step, the separation step, and the recovery step are repeated in this order, The gas separation apparatus according to claim 8 , wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the auxiliary adsorption unit before stopping the separation cycle.

12. An auxiliary vacuum pump is provided. The gas separation apparatus according to claim 11, wherein the control unit desorbs the target gas adsorbed in the adsorption step immediately before stopping the separation cycle from the auxiliary adsorption unit by reducing the pressure to below atmospheric pressure using the auxiliary vacuum pump before stopping the separation cycle.

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