Gas separation device

Abstract

To provide gas separation equipment which can supply separated gas at a flow volume desired by a user.SOLUTION: Gas separation equipment 100 comprises: an adsorption vessel 19 which separates second gas from gaseous starting material based on a pressure swing adsorption method; a flow passage 48 which supplies a demand end 70 with the second gas separated in the adsorption vessel 19 and comprises a flow volume adjustment mechanism 60 which adjusts purity of the second gas separated in the adsorption vessel 19 to be a prescribed purity by flow volume adjustment of the flowing second gas; a pressure sensor 49 which measures pressure of the flow passage 48 at the downstream side of the flow volume adjustment mechanism 60; and a control device 50, wherein the control device 50 controls the flow volume adjustment mechanism 60 in such a manner that: when the measured value of the pressure sensor 49 is less than the prescribed pressure, the flow volume of the second gas flowing in the flow passage 48 becomes a first prescribed flow volume at which the purity of the second gas becomes the prescribed purity; and when the measured value of the pressure sensor 49 is the prescribed pressure or more, the flow volume of the second gas becomes the maximum flow volume permitted by the flow passage 48.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a gas separation device position .

Background Art

[0002] Patent Document 1 describes "providing a method and a system for purifying carbon dioxide gas that can increase the purity of carbon dioxide gas purified by pressure swing adsorption without reducing the recovery rate." Further, Patent Document 1 also describes "In each adsorption tower, an adsorption step, a depressurization step, a desorption step, and a pressure increase step are sequentially executed. The carbon dioxide gas contained in the raw material carbon dioxide gas is adsorbed by the adsorbent under pressure, and the impurity gas not adsorbed by the adsorbent is discharged as off-gas. By introducing the internal gas of any one of the adsorption towers in the depressurization step into any one of the adsorption towers in the state after the desorption step and before the pressure increase step, a gas extrusion step is executed in any one of the adsorption towers in the state after the desorption step and before the pressure increase step to extrude the carbon dioxide gas staying inside to the outside. The carbon dioxide gas discharged from each adsorption tower in the desorption step and the carbon dioxide gas extruded in the gas extrusion step are recovered as purified gas."

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technology described in Patent Document 1, the gas separated in the adsorption tower is taken out through a first pressure regulating valve that regulates the adsorption pressure in the adsorption tower (paragraph 0022, FIG. 1 of Patent Document 1). Depending on the installation form of the gas separation device, the pressure on the downstream side of the first pressure regulating valve may be high. In this case, the differential pressure between the adsorption tower and the downstream side of the first pressure regulating valve is small, and the separated gas, for example, hardly flows through the first pressure regulating valve. As a result, the flow rate is restricted in the first pressure regulating valve, and the user may not be able to secure the desired flow rate. The problem to be solved by the present disclosure is to provide a gas separation device capable of supplying the separated gas at a flow rate according to the user's desire. of the position

Means for Solving the Problems

[0005] The gas separation device of the present disclosure includes an adsorption tank that separates the second gas by adsorbing the first gas based on the pressure swing adsorption method from a raw material gas that partially contains the first gas and the remainder is composed of the second gas, a flow path that connects the adsorption tank and the demand end and through which the second gas separated in the adsorption tank flows, a flow rate adjustment mechanism provided in the flow path that adjusts the flow rate of the second gas supplied from the adsorption tank to the demand end by flowing through the flow path and makes the purity of the second gas separated in the adsorption tank and supplied to the demand end a predetermined purity by the adjustment, a pressure sensor that measures the pressure on the downstream side of the flow rate adjustment mechanism in the flow path, and a mechanism provided between the adsorption tank and the flow rate adjustment mechanism that suppresses the transmission of the fluctuation of the discharge pressure, which is the pressure of the second gas when the second gas is discharged from the adsorption tank due to pressure swing adsorption in the adsorption tank, to its downstream side and sets the pressure on its downstream side to be equal to or lower than a set pressure. When the flow rate of the second gas flowing through the flow path and supplied to the demand end is less than a predetermined pressure at which the second gas easily flows through the flow rate adjustment mechanism due to the differential pressure between the upstream and downstream of the flow rate adjustment mechanism as measured by the pressure sensor, the control device controls the flow rate adjustment mechanism so that the flow rate becomes a first predetermined flow rate that makes the purity of the second gas the predetermined purity. When the measured value of the pressure sensor is equal to or higher than the predetermined pressure at which the second gas hardly flows through the flow rate adjustment mechanism due to the differential pressure, the flow rate becomes a second predetermined flow rate that is higher than the first predetermined flow rate. make the purity of the second gas the predetermined purity, and The control device is provided.

Advantages of the Invention

[0006] According to the present disclosure, a gas separation device capable of supplying a gas separated at a flow rate according to a user's desire position can be provided.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0008] Hereinafter, modes for carrying out the present disclosure (referred to as embodiments) will be described with reference to the drawings. In the description of the following one embodiment, descriptions of other embodiments applicable to the one embodiment will be made as appropriate. The present disclosure is not limited to the following one embodiment, and different embodiments can be combined with each other or arbitrarily modified within a range that does not significantly impair the effects of the present disclosure. Also, the same members will be denoted by the same reference numerals, and overlapping descriptions will be omitted. Further, those having the same function will be given the same name. The illustrated content is merely schematic, and may be changed from the actual configuration within a range that does not significantly impair the effects of the present disclosure for the convenience of illustration.

[0009] FIG. 1 is a system diagram showing a gas separation apparatus 100 according to the first embodiment. The gas separation apparatus 100 separates a second gas from a raw material gas that partially contains a first gas and the remainder is composed of a second gas, based on the pressure swing adsorption method. The raw material gas is, for example, air, the first gas is a gas containing, for example, oxygen, etc., and the second gas is a gas containing, for example, nitrogen, etc. However, the raw material gas, the first gas, and the second gas are not limited to these.

[0010] The gas separation apparatus 100 includes a compressor 8, a compressed gas tank 5, an adsorption tank 19, a second gas tank 41, a filter regulator 47, and a flow path 48 provided with a flow rate adjustment mechanism 60.

[0011] The compressor 8 compresses the raw material gas and is composed of, for example, a reciprocating compressor, a screw compressor, a scroll compressor, etc., or a booster compressor that is supplied with a primary pressure from the outside and recompresses. The compressed raw material gas is supplied to the compressed gas tank 5 provided at the subsequent stage of the compressor 8.

[0012] The adsorption tank 19 separates the second gas by adsorbing the first gas based on the pressure swing adsorption method from the raw material gas. In the illustrated example, the raw material gas is compressed by the compressor 8 provided at the previous stage of the adsorption tank 19. The adsorption tank 19 includes a first adsorption tank 191 and a second adsorption tank 192, and continuous separation is performed by separating the second gas while switching the supply destination of the raw material gas. The adsorption tank 19 is configured by housing an adsorbent (not shown), such as molecular sieve carbon or zeolite, inside an adsorption tank body (not shown). The separated second gas is supplied to the second gas tank 41 installed at the subsequent stage of the adsorption tank 19.

[0013] The filter regulator 47 is provided downstream of the second gas tank 41 and removes dust while maintaining the downstream pressure at a predetermined pressure. However, instead of the filter regulator 47, a regulator (not shown) may be provided, or any decompression mechanism (not shown) capable of maintaining the pressure on the downstream side constant may be provided. Since the filter regulator 47 is provided on the downstream side of the second gas tank 41, fluctuations in the discharge pressure of the second gas due to pressure swing adsorption can be suppressed from being transmitted to the downstream side of the filter regulator 47.

[0014] The flow rate adjustment mechanism 60 adjusts the purity of the second gas separated in the adsorption tank 19 to a predetermined purity by adjusting the flow rate of the second gas flowing through the flow path 48 (described later). By reducing the flow rate of the second gas flowing through the flow path 48 by the flow rate adjustment mechanism 60, the residence time of the raw material gas in the adsorption tank 19 can be ensured. Thereby, the purity of the second gas separated in the adsorption tank 19 can be made a predetermined purity (for example, 99% by volume or more).

[0015] The gas separation device 100 includes flow paths 16 and 48 configured with, for example, piping. The flow path 16 supplies the raw material gas compressed by the compressor 8 to the adsorption tank 19. The flow path 48 is connected downstream of the adsorption tank 19 and supplies the second gas separated in the adsorption tank 19 to a demand end 70 configured by, for example, a piping connection port. A flow path 73 configured with, for example, piping is connected to the demand end 70. The flow path 73 includes a tank 71 and a flow rate adjustment valve 72. The second gas taken out from the gas separation device 100 through the demand end 70 is stored in the tank 71 and then taken out from the tank 71 when the user appropriately opens and closes the flow rate adjustment valve 72. When the flow rate adjustment valve 72 is fully closed, the pressure on the downstream side of the flow rate adjustment mechanism 60 such as the tank 71 usually becomes the set pressure of the filter regulator 47. When adsorption is further performed in the adsorption tank 19 in this state, although the second gas does not flow, the purity of the second gas further increases.

[0016] The flow rate adjustment mechanism 60 includes a first flow path 61 having a flow rate fixing valve 63 with a pre-fixed flow rate for flowing the second gas at a first predetermined flow rate to make the purity of the second gas the above-mentioned predetermined purity, and a second flow path 62 for bypassing the flow rate fixing valve 63. Both the first flow path 61 and the second flow path 62 are provided as part of the flow path 48.

[0017] The flow rate fixing valve 63 is, for example, a flow rate adjustment valve with an adjustable opening degree. For example, before the shipment of the gas separation device 100 or during the trial operation, etc., it is adjusted (for example, throttled) to a first predetermined opening degree in advance and then the opening degree is fixed. The first predetermined opening degree mentioned here is the opening degree for flowing the second gas at a first predetermined flow rate to make the purity of the second gas the above-mentioned predetermined purity, and is the opening degree corresponding to the first predetermined flow rate. During the operation of the gas separation device 100, the opening degree of the flow rate fixing valve 63 is not changed. By using a flow rate adjustment valve, it is easy to adjust the predetermined opening degree for each gas separation device 100 according to the design conditions, etc., of the gas separation device 100.

[0018] The flow rate adjustment mechanism 60 includes an on-off valve 64 in the first flow path 61 and an on-off valve 65 in the second flow path 62. The on-off valves 64 and 65 are constituted by, for example, electromagnetic valves, etc., and are connected to a control device 50 described later through electric signal lines shown by broken lines.

[0019] The gas separation device 100 includes a flow rate sensor 45 and a purity sensor 46. The flow rate sensor 45 measures the flow rate of the second gas flowing between the adsorption tank 19 and the flow rate adjustment mechanism 60 in the flow path 48. The purity sensor 46 measures the purity of the second gas flowing between the adsorption tank 19 and the flow rate adjustment mechanism 60 in the flow path 48. Both the flow rate sensor 45 and the purity sensor 46 are connected to a control device 50 described later through electric signal lines shown by broken lines. The purity sensor 46 is constituted by a sensor that directly measures the purity of the second gas by measuring the amount of the second gas, a sensor that measures the amount of the first gas to indirectly calculate the purity of the second gas based on a raw material gas with a known concentration, etc. In the illustrated example, the purity sensor 46 is a sensor that measures the concentration of the first gas.

[0020] The gas separation device 100 includes a pressure sensor 49 that measures the pressure on the downstream side of the flow rate adjustment mechanism 60 in the flow path 48. The pressure sensor 49 is connected to a control device 50, which will be described later, through an electrical signal line indicated by a broken line. In the illustrated example, the pressure sensor 49 measures the pressure of the second gas between the flow rate adjustment mechanism 60 and the demand end 70. The pressure sensor 49 may measure the pressure of the tank 71 connected to the demand end 70.

[0021] The gas separation device 100 includes a control device 50 that controls the gas separation device 100 including the flow rate adjustment mechanism 60.

[0022] When the measured value of the pressure sensor 49 is less than the predetermined pressure, the control device 50 adjusts the flow rate of the second gas flowing through the flow path 48 to the first predetermined flow rate that makes the purity of the second gas the predetermined purity. When the measured value of the pressure sensor 49 is greater than or equal to the predetermined pressure, the control device 50 controls the flow rate adjustment mechanism 60 so that the second gas flows at a second predetermined flow rate greater than the first predetermined flow rate.

[0023] In the illustrated example, the second predetermined flow rate is the maximum flow rate of the flow path 48. The flow path 48 is configured such that when flowing at the maximum flow rate, the set pressure of the filter regulator 47 and the measured value of the pressure sensor 49 coincide. Here, the coincidence is assumed to allow a deviation due to a pressure loss or the like that cannot be avoided due to the flow through piping or the like. By flowing the second gas at the maximum flow rate, it is possible to cope even if the usage amount of the second gas becomes particularly large.

[0024] When the pressure on the downstream side of the flow rate adjustment mechanism 60 is less than the predetermined pressure, the differential pressure between the upstream and downstream of the flow rate adjustment mechanism 60 in the flow path 48 is large, and the second gas easily flows. However, if the second gas flows too easily, the residence time of the raw material gas in the adsorption tank 19 cannot be ensured, and the purity of the second gas may decrease. Therefore, in order to ensure the purity of the second gas to the predetermined purity, the flow rate adjustment mechanism 60 adjusts the flow rate of the second gas to the first predetermined flow rate. By setting the thus adjusted first predetermined flow rate to, for example, the specification value (catalog value, etc.) of the usable flow rate of the gas separation device 100, the user can use the second gas within the flow rate according to the specification value.

[0025] On the other hand, when the pressure on the downstream side of the flow rate adjustment mechanism 60 is equal to or higher than a predetermined pressure, the differential pressure between the upstream and downstream of the flow rate adjustment mechanism 60 in the flow path 48 is small, and it is difficult for the second gas to flow through the flow rate adjustment mechanism 60. Therefore, in this case, by flowing the second gas into the second flow path 62 at a second predetermined flow rate, which is the maximum flow rate in the illustrated example, through the flow path 48, the difficulty of flow caused by the flow rate fixing valve 63 can be avoided. As a result, it becomes easier for the second gas to flow to the demand end 70, and the user can take out the second gas through the demand end 70 at the desired flow rate.

[0026] The predetermined pressure of the pressure sensor 49 serving as a threshold for changing the flow rate is, for example, a pressure lower than the set pressure of the filter regulator 47, and is a pressure that can suppress sudden flow rate fluctuations caused by the differential pressure between the upstream and downstream of the flow rate adjustment mechanism 60 and is lower than the set pressure. When the second gas is not used or the usage amount is small, the pressure on the downstream side of the flow rate adjustment mechanism 60 (the pressure measured by the pressure sensor 49. For example, it may be the pressure of the tank 71) increases. However, since the filter regulator 47 is provided upstream of the flow rate adjustment mechanism 60, the upper limit of the pressure on the downstream side of the flow rate adjustment mechanism 60 is usually the set pressure of the filter regulator 47. Therefore, by switching to the second predetermined flow rate when the pressure on the downstream side of the flow rate adjustment mechanism 60 reaches the predetermined pressure, the second gas can be flowed to the demand end 70 while suppressing sudden flow rate fluctuations. As a result, the user can use the second gas at the desired flow rate.

[0027] In the illustrated example, the control device 50 switches the flow path 48 so that the separated second gas flows into the first flow path 61 when the measured value of the pressure sensor 49 is less than the predetermined pressure, and flows into the second flow path 62 when the measured value of the pressure sensor 49 is equal to or higher than the predetermined pressure. By doing so, the second gas can be flowed into the flow path 48 with different flow rates that can be circulated according to the measured value of the pressure sensor 49, and the flow rate of the second gas supplied to the demand end 70 can be controlled. In particular, the second flow path 62 is arranged to bypass the flow rate fixing valve 63 and does not have a mechanism that causes a decrease in flow rate. Therefore, by flowing through the second flow path 62, the second gas can be circulated through the flow path 48 at a second predetermined flow rate (the maximum flow rate in the illustrated example) of the flow rate that can be circulated.

[0028] The switching between the first flow path 61 and the second flow path 62 can be performed by opening and closing the on-off valves 64 and 65 by the control device 50. When flowing the second gas through the first flow path 61, the control device 50 opens the on-off valve 64 and closes the on-off valve 65. On the other hand, when flowing the second gas through the second flow path 62, the control device 50 opens the on-off valve 65 and closes the on-off valve 64.

[0029] When the measured value of the pressure sensor 49 is equal to or higher than a predetermined pressure, the control device 50 causes the second gas to flow through the flow path 48 at a second predetermined flow rate regardless of the purity of the second gas discharged from the adsorption tank 19 measured by the purity sensor 46. If the measured value of the pressure sensor 49 becomes equal to or higher than the predetermined pressure, the second gas is considered to be at a sufficiently high pressure and a purity of at least the predetermined purity. Therefore, by flowing the second gas through the flow path 48 at the second predetermined flow rate without measuring the purity of the second gas, it is possible to obtain the second gas of the predetermined purity at the desired flow rate without confirmation by the purity sensor 46.

[0030] When the second gas is flowing through the flow path 48 at the second predetermined flow rate, the control device 50 controls the flow rate adjustment mechanism 60 so that the flow rate of the flowing second gas becomes the first predetermined flow rate when a predetermined condition that causes an abnormality in the purity of the second gas discharged from the adsorption tank 19 is satisfied. By doing so, when the purity of the second gas is likely to become an abnormal purity such as less than the predetermined purity, for example, the flow rate of the second gas can be decreased by the flow rate adjustment mechanism 60 to ensure the purity of the second gas. In the illustrated example, when the second gas is flowing through the second flow path 62, if the predetermined condition is satisfied, the control device 50 switches the flow path 48 so that the second gas flows through the first flow path 61.

[0031] The predetermined condition includes, for example, when the measured value of the flow rate sensor 45 is equal to or higher than a third predetermined flow rate and the measured value of the purity sensor 46 is less than a predetermined reference purity. By doing so, when the usage flow rate is high and the purity of the second gas decreases, the flow rate of the second gas can be controlled by the flow rate adjustment mechanism 60 to maintain the second gas at the predetermined purity.

[0032] The third predetermined flow rate to be compared with the measured value of the flow rate sensor 45 can be, for example, a design specification value (e.g., catalog value) of the gas separation device 100. Therefore, for example, when the flow rate of the second gas used exceeds the specification value, it can be determined that the measured value of the flow rate sensor 45 is equal to or greater than the third predetermined flow rate. In this case, since the second gas is used in an amount exceeding the specification value, it becomes difficult to ensure the residence time of the raw material gas in the adsorption tank 19, and the purity is likely to decrease. Note that the third predetermined flow rate may be, for example, the same as the first predetermined flow rate described above, but may also be different.

[0033] The reference purity to be compared with the measured value of the purity sensor 46 can be, for example, a predetermined ratio based on the design specification value (e.g., the predetermined purity described in the catalog value) of the gas separation device 100. Therefore, for example, when the purity sensor 46 is a sensor that measures the concentration of the first gas as an example, if the measured value of the purity sensor 46 is less than a predetermined value when the allowable amount of the remaining first gas concentration exceeds, for example, 50%, that is, when the purity of the second gas is likely to be less than the predetermined purity, it can be determined.

[0034] The control device 50 controls the flow rate adjustment mechanism 60 so that the flow rate of the second gas flowing through the flow path 48 becomes the first predetermined flow rate from the start of adsorption in the adsorption tank 19 until the measured value of the pressure sensor 49 reaches the predetermined pressure. Further, the control device 50 controls the flow rate adjustment mechanism 60 so that the flow rate of the second gas flowing through the flow path 48 becomes the second predetermined flow rate when the measured value of the pressure sensor 49 reaches the predetermined pressure. By doing so, when the purity of the second gas after the start of adsorption is low, the purity of the second gas can be improved by flowing it at the first predetermined flow rate. On the other hand, when the purity reaches the predetermined purity when the measured value of the pressure sensor 49 reaches the predetermined pressure, it can be increased more than the flow rate limited by the flow rate adjustment mechanism 60 by flowing it at the second predetermined flow rate, and the second gas of the predetermined purity can be obtained at the desired flow rate.

[0035] The control device 50, although not shown in the figures, is configured to include, for example, a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), etc. The control device 50 is realized by a predetermined control program stored in the ROM being expanded in the RAM and executed by the CPU.

[0036] Figure 2 is a flowchart showing the gas separation method of the first embodiment. Since the gas separation method shown in Figure 2 is carried out in the gas separation device 100 (Figure 1), Figure 2 will be described while appropriately referring to Figure 1.

[0037] The gas separation method of the first embodiment includes a separation step S20 of separating a second gas by adsorbing a first gas based on the pressure swing adsorption method in the adsorption tank 19 having a flow path 48 connected to the downstream side and provided with a flow rate adjustment mechanism 60 for making the purity of the second gas to be separated from the raw material gas reach the predetermined purity. The separation step S20 includes a first separation step S11 and a second separation step S12.

[0038] The first separation step S11 is performed when the measured value of the pressure sensor 49 is less than the predetermined pressure, and is a step performed while controlling the flow rate of the second gas by the flow rate adjustment mechanism 60 so that the flow rate of the second gas flowing through the flow path 48 becomes a first predetermined flow rate that makes the purity of the second gas reach the predetermined purity. In the illustrated example, the first separation step S11 is composed of steps S1 to S4, S6 to S8 described later. The second separation step S12 is performed when the measured value of the pressure sensor 49 is greater than or equal to the predetermined pressure, and is a step performed while controlling the flow rate of the second gas by the flow rate adjustment mechanism 60 so that the flow rate of the second gas flowing through the flow path 48 becomes a second predetermined flow rate (the maximum flow rate of the flow path 48 in the example of Figure 1) that is greater than the first predetermined flow rate. In the illustrated example, the second separation step S12 is composed of steps S4 to S6 described later. Hereinafter, the separation step S20, the first separation step S11, and the second separation step S12 will be described by explaining steps S1 to S8 along Figure 2.

[0039] When a driving start instruction by the user is input to the control device 50 through an operation unit (not shown), the control device 50 performs an initial operation (step S1). In the initial operation, the control device 50 closes the on-off valves 64 and 65, and the adsorption tank 19 adsorbs the first gas. As a result, the purity of the second gas is efficiently increased. When the purity of the second gas measured by the purity sensor 46 reaches the above-mentioned predetermined purity (for example, the concentration of the residual first gas is equal to or less than the specified value), the control device 50 starts discharging by opening the on-off valve 64, and the second gas flows through the first flow path 61 (step S2). Since the opening degree of the flow rate adjustment valve 72 installed downstream of the tank 71 is usually throttled, the second gas is stored in the tank 71. At this time, the pressure in the tank 71 is usually close to the atmospheric pressure immediately after the start of discharge, but the pressure increases as the discharge progresses.

[0040] When the second gas flows through the first flow path 61, the control device 50 measures the pressure on the downstream side of the flow rate adjustment mechanism 60 by the pressure sensor 49 constantly or at predetermined time intervals (step S3). If the usage amount is less than the supply amount of the second gas, the pressure rises. The control device 50 determines whether the pressure measured by the pressure sensor 49 is equal to or higher than a predetermined pressure (step S4). The predetermined pressure mentioned here has the same meaning as the above-mentioned predetermined pressure described in the gas separation device 100 in FIG. 1. If it is not equal to or higher than the predetermined pressure (that is, if it is less than the predetermined pressure; No in step S4), the control device 50 performs step S3 again. These steps S1 to S4 are the above-mentioned first separation step S11.

[0041] On the other hand, if it is equal to or higher than the predetermined pressure (Yes in step S4), the control device 50 closes the on-off valve 64 and opens the on-off valve 65 to cause the second gas to flow into the second flow path 62 (step S5). Different from the first flow path 61, the second flow path 62 does not include a flow rate fixing valve 63 that causes difficulty in flow and a decrease in flow rate due to, for example, a reduced inner diameter. Therefore, the pressure on the downstream side of the flow rate adjustment mechanism 60 can be made equal to the set pressure of the filter regulator 47. By presetting the set pressure of the filter regulator 47 to the pressure desired by the user in advance, the user can use the second gas at the desired pressure.

[0042] When the second gas is flowing through the second flow path 62, the control device 50 determines whether or not a predetermined condition is satisfied constantly or at predetermined time intervals (step S6). The predetermined condition mentioned here has the same meaning as the above-described predetermined condition explained in the gas separation device 100 of FIG. 1. For example, if the usage amount of the second gas is small and the like, and the predetermined condition is not satisfied, the residence time of the raw material gas in the adsorption tank 19 is ensured, and an abnormality in the purity of the second gas is less likely to occur. Therefore, in this case (No in step S6), since the purity of the second gas can be maintained, the second gas continues to flow through the second flow path 62. These steps S4 to S6 are the above-described second separation step S12.

[0043] On the other hand, if the predetermined condition is satisfied (Yes in step S6), the control device 50 closes the on-off valve 65 and opens the on-off valve 64 to cause the second gas to flow through the first flow path 61 (step S7). When the second gas flows through the first flow path 61, it is subject to flow rate limitation by the flow rate fixing valve 63, and the supply amount through the demand end 70 of the second gas is limited. Thereby, the residence time of the raw material gas in the adsorption tank 19 can be ensured, and an abnormality in the purity of the second gas can be suppressed. These steps S6 to S8 are the above-described first separation step S11.

[0044] The control device 50 determines whether or not there is an operation stop operation by the user through an operation unit (not shown) (step S8). If there is no operation stop operation, the control device 50 determines that the operation has not ended (No in step S8), and steps S3 and subsequent steps are repeated. On the other hand, if there is an operation stop operation, the control device 50 determines that the operation has ended (Yes), stops the drive of the compressor 8, and fully closes the on-off valves 64 and 65.

[0045] According to the above gas separation method, the second gas (separated gas) can be supplied through the demand end 70 at a flow rate according to the user's desire.

[0046] FIG. 3 is a system diagram showing the gas separation apparatus 101 of the second embodiment. The gas separation apparatus 101 is the same as the gas separation apparatus 100 (FIG. 1) except that it includes a flow rate adjustment mechanism 601 instead of the flow rate adjustment mechanism 60 (FIG. 1). Further, the flow rate adjustment mechanism 601 is the same as the flow rate adjustment mechanism 60 (FIG. 1) except that it includes a constant flow rate valve as the flow rate fixed valve 631 instead of the flow rate adjustment valve (FIG. 1) as the flow rate fixed valve 63.

[0047] The constant flow rate valve is a valve manufactured for each gas separation apparatus 101, for example, by designing it so that a desired flow rate flows through. By providing a constant flow rate valve manufactured so that a first predetermined flow rate that makes the purity of the second gas separated in the adsorption tank 19 a predetermined purity can flow, the flow rate management can be accurately performed.

[0048] FIG. 4 is a system diagram showing the gas separation apparatus 102 of the third embodiment. The gas separation apparatus 102 is the same as the gas separation apparatus 100 (FIG. 1) except that it includes a flow rate adjustment mechanism 602 instead of the flow rate adjustment mechanism 60 (FIG. 1). The flow rate adjustment mechanism 602 is a control valve 632 whose flow rate is adjusted by the opening degree control by the control device 50.

[0049] When the measured value of the pressure sensor 49 is less than the predetermined pressure, the control device 50 controls the opening degree of the control valve 632 to a first predetermined opening degree corresponding to the first predetermined flow rate. When the measured value of the pressure sensor 49 is greater than or equal to the predetermined pressure, the control device 50 controls the opening degree of the control valve 632 to a second predetermined opening degree corresponding to the second predetermined flow rate. The second predetermined opening degree is an opening degree through which the second gas can flow through the flow path 48 at the second predetermined flow rate. When the second predetermined flow rate is the maximum, usually, the second predetermined opening degree is the maximum opening degree. By adjusting the opening degree of the control valve 632 according to the measured value of the pressure sensor 49, the flow rate of the second gas supplied to the demand side 70 can be controlled. In the example shown in the figure, the flow path 48 is configured so that when the opening degree of the control valve 632 is, for example, the maximum opening degree, the set pressure of the filter regulator 47 and the measured value of the pressure sensor 49 coincide. The interpretation of this coincidence here is synonymous with the explanation in the gas separation apparatus 100 (FIG. 1).

[0050] FIG. 5 is a flowchart showing the gas separation method of the third embodiment. The gas separation method shown in FIG. 5 is the same as the gas separation method shown in FIG. 2, except that it includes steps S21, S51, and S71 instead of steps S2, S5, and S7 shown in FIG. 2.

[0051] The control device 50 performs an initial operation by, for example, fully closing the control valve 632 (step S1). When the purity of the second gas reaches a predetermined purity, the control device 50 starts discharging the second gas by opening the control valve 632 and controls the opening degree of the control valve 632 to a first predetermined opening degree (step S21). The first predetermined opening degree mentioned here has the same meaning as the description in the gas separation device 100 (FIG. 1), and is the opening degree for flowing the second gas at the first predetermined flow rate that makes the purity of the second gas the above-mentioned predetermined purity. By controlling to the first predetermined opening degree, the residence time of the raw material gas in the adsorption tank 19 is ensured, and the purity of the second gas can be made equal to or higher than the predetermined purity.

[0052] During the flow of the control valve 632 with a predetermined opening degree, the control device 50 performs pressure measurement (step S3) and determines whether the pressure is equal to or higher than a predetermined pressure (step S4). As a result of the determination, if it is not equal to or higher than the predetermined pressure (No), step S3 is performed again. If it is equal to or higher than the predetermined pressure (Yes), the control device 50 controls the opening degree of the control valve 632 to a second predetermined opening degree (step S51). By controlling to the second predetermined opening degree, the flow rate of the flow path 48 can be increased, and the flow rate of the second gas through the demand end 70 can be made as desired by the user.

[0053] The control device 50 determines whether a predetermined condition is satisfied (step S6). If not satisfied (No), step S6 is performed again. On the other hand, if satisfied (Yes), the control device 50 controls the opening degree of the control valve 632 to the above-mentioned first predetermined opening degree (step S71). By controlling to the first predetermined opening degree, a decrease in the purity of the second gas can be suppressed. Thereafter, if the operation has not ended (No in step S8), steps S3 and subsequent steps are repeated. If the operation has ended (Yes), the control device 50 stops driving the compressor and fully closes the control valve 632.

[0054] According to the above gas separation method, similar to the gas separation method shown in FIG. 2, the second gas (separated) can be supplied through the demand end 70 at a flow rate according to the user's wishes.

Explanation of Signs

[0055] 100, 101, 102 Gas separation device 16 Flow path 19 Adsorption tank 191 First adsorption tank 192 Second adsorption tank 41 Second gas tank 42 Flow rate sensor 46 Purity sensor 47 Filter regulator 48 Flow path 49 Pressure sensor 5 Compressed gas tank 50 Control device 60, 601, 602 Flow rate adjustment mechanism 61 First flow path 62 Second flow path 63, 631 Flow rate fixed valve 632 Control valve 64, 65 On-off valve 70 Demand end 71 Tank 72 Flow rate adjustment valve 73 Flow path 8 Compressor S1, S2, S21, S3, S4, S5, S51, S6, S7, S71, S8 Steps S11 First separation step S12 Second separation step S20 Separation step

Claims

1. An adsorption tank that separates the second gas by adsorbing the first gas based on the pressure swing adsorption method from a raw material gas that partially contains the first gas and the remainder is composed of the second gas, a flow path that connects the adsorption tank and the demand end and through which the second gas separated in the adsorption tank flows, a flow rate adjustment mechanism provided in the flow path that adjusts the flow rate of the second gas supplied from the adsorption tank to the demand end by flowing through the flow path, and makes the purity of the second gas separated in the adsorption tank and supplied to the demand end reach a predetermined purity by this adjustment, a pressure sensor that measures the pressure on the downstream side of the flow rate adjustment mechanism in the flow path, a mechanism provided between the adsorption tank and the flow rate adjustment mechanism that suppresses the transmission of fluctuations in the discharge pressure, which is the pressure of the second gas when the second gas is discharged from the adsorption tank due to pressure swing adsorption in the adsorption tank, to its downstream side and sets the pressure on its downstream side to be equal to or lower than a set pressure, the flow rate of the second gas flowing through the flow path and supplied to the demand end, when the measured value of the pressure sensor is less than a predetermined pressure at which the second gas easily flows through the flow rate adjustment mechanism due to the differential pressure between the upstream and downstream of the flow rate adjustment mechanism, so that the purity of the second gas becomes the first predetermined flow rate that makes the purity of the second gas reach the predetermined purity, when the measured value of the pressure sensor is equal to or higher than the predetermined pressure at which the second gas hardly flows through the flow rate adjustment mechanism due to the differential pressure, so that the purity of the second gas becomes the predetermined purity and the second predetermined flow rate that is greater than the first predetermined flow rate, a control device that controls the flow rate adjustment mechanism, and a gas separation device characterized by the above.

2. The second predetermined flow rate is the maximum flow rate of the flow path The gas separation device according to claim 1, characterized by the above.

3. The control device is from the start of adsorption in the adsorption tank until the measured value of the pressure sensor reaches the predetermined pressure, controls the flow rate adjustment mechanism so that the flow rate of the second gas flowing through the flow path becomes the first predetermined flow rate, when the measured value of the pressure sensor reaches the predetermined pressure, controls the flow rate adjustment mechanism so that the flow rate of the second gas flowing through the flow path becomes the second predetermined flow rate The gas separation device according to claim 1 or 2, characterized by the above.

4. When the measured value of the pressure sensor is equal to or higher than the predetermined pressure, the control device causes the second gas to flow through the flow path at the second predetermined flow rate without confirming the purity of the second gas discharged from the adsorption tank with a purity sensor. The gas separation device according to claim 1 or 2, characterized in that.

5. The flow rate adjustment mechanism includes a flow rate fixing valve in which the flow rate is fixed in advance so that the second gas flows at the first predetermined flow rate for making the purity of the second gas the predetermined purity, a first flow path as a part of the flow path, a second flow path that bypasses the flow rate fixing valve and is a part of the flow path, and includes When the measured value of the pressure sensor is less than the predetermined pressure, the control device causes the separated second gas to flow through the first flow path, and when the measured value of the pressure sensor is equal to or higher than the predetermined pressure, switches the flow path so that the second gas flows through the second flow path. The gas separation device according to claim 1 or 2, characterized in that.

6. The flow rate fixing valve is either a flow rate adjustment valve fixed to a first predetermined opening degree for allowing the second gas to flow through at the first predetermined flow rate or a constant flow rate valve. The gas separation device according to claim 5, characterized in that.

7. The flow rate adjustment mechanism is a control valve whose flow rate is adjusted by opening degree control by the control device, The control device When the measured value of the pressure sensor is less than the predetermined pressure, controls the opening degree of the control valve to a first predetermined opening degree corresponding to the first predetermined flow rate, When the measured value of the pressure sensor is equal to or higher than the predetermined pressure, controls the opening degree of the control valve to a second predetermined opening degree corresponding to the second predetermined flow rate. The gas separation device according to claim 1 or 2, characterized in that.

8. When the second gas is flowing through the flow path at the second predetermined flow rate, the control device controls the flow rate adjustment mechanism so that the flow rate of the second gas flowing becomes the first predetermined flow rate when a predetermined condition that causes an abnormality in the purity of the second gas discharged from the adsorption tank is satisfied. The gas separation device according to claim 1 or 2, characterized in that.

9. a flow rate sensor that measures the flow rate of the second gas flowing between the adsorption tank and the flow rate adjustment mechanism in the flow path, a purity sensor that measures the purity of the second gas flowing between the adsorption tank and the flow rate adjustment mechanism in the flow path, and includes The predetermined condition includes when the measured value of the flow rate sensor is equal to or higher than a third predetermined flow rate and the measured value of the purity sensor is less than a predetermined reference purity. The gas separation device according to claim 8, characterized in that.

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