gas supply system

Abstract

To provide a gas supply system that allows for the replacement of gas tanks without interrupting the gas supply. [Solution] The gas supply system comprises two support members that support the gas tank and are movable between a detachable position and a connected position. The controller of the gas supply system opens the main shut-off valve of the first gas tank while keeping the main shut-off valve of the second gas tank closed to start supplying gas. When the pressure in the first gas tank reaches the lower pressure limit, the controller closes the main shut-off valve of the first gas tank, opens the main shut-off valve of the second gas tank, and moves the first support member to the detachable position for the first gas tank.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a gas supply system that supplies gas to a gas utilization device.

Background Art

[0002] Patent Document 1 discloses a gas supply system in which a plurality of gas tanks are connected and gas is supplied from each gas tank to a gas utilization device. In that gas supply system, when all the gas tanks are empty, the gas utilization device is stopped and the gas tanks are replaced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the system of Patent Document 1, during the replacement of the gas tank, the gas supply is interrupted, so the gas utilization device has to be stopped. This specification provides a gas supply system that can replace the gas tank without interrupting the gas supply to the gas utilization device.

Means for Solving the Problems

[0005] The gas utilization device disclosed herein comprises a first support for supporting a first gas tank, a second support for supporting a second gas tank, a gas supply pipe for leading gas to the gas utilization device, a first / second actuator, a first / second main shut-off valve, and a controller. The first (second) actuator can move the first (second) support between a connection position, to which the first (second) support with the first (second) gas tank attached is connected to the gas supply pipe, and a detachment position, to which the first (second) gas tank can be attached and detached. The first (second) main shut-off valve opens and closes the gas flow path between the first (second) gas tank and the gas utilization device. When the first (second) gas tank is set on the first (second) support, the controller controls the first (second) actuator to move the first (second) support to the connection position. The controller opens the first main shut-off valve while keeping the second main shut-off valve closed to supply gas from the first gas tank to the gas utilization device. The controller closes the first main shut-off valve and opens the second main shut-off valve when the pressure in the first gas tank reaches the lower pressure limit, and simultaneously moves the first support to the detachable position. Note that "gas tank pressure" refers to the pressure inside the gas tank (i.e., the internal pressure of the gas tank).

[0006] The user operating the gas supply system can replace the first gas tank when its internal pressure becomes low. While the user is replacing the first gas tank, gas continues to be supplied to the gas-consuming devices from the second gas tank. The gas supply system disclosed herein allows for the replacement of gas tanks without interrupting the supply of gas to the gas-consuming devices.

[0007] Details of the technology disclosed herein and further improvements are described in the following "Modes for Carrying Out the Invention". [Brief explanation of the drawing]

[0008] [Figure 1] This is a block diagram of the gas supply system in the embodiment. [Figure 2] Cross-sectional view of the gas tank and gas supply pipe (connection (valve closed) position). [Figure 3]Cross-sectional view of the gas tank and gas supply pipe (connection (valve open) position). [Figure 4] This is a flowchart for the gas tank replacement preparation process. [Figure 5] This is a time chart showing the replacement timing for the two gas tanks. [Modes for carrying out the invention]

[0009] The gas supply system 2 of this embodiment will be described with reference to the drawings. Figure 1 shows a block diagram of the gas supply system 2. The gas supply system 2 of this embodiment is connected to a fuel cell 90, and the gas supply system 2 supplies hydrogen gas from multiple gas tanks 10a and 10b to the fuel cell 90. The fuel cell 90 is an example of a gas utilization device to which the gas supply system 2 supplies gas.

[0010] The gas supply system 2 includes two gas tanks 10a and 10b, a gas supply pipe 30, support members 18a and 18b, actuators 19a and 19b, pressure sensors 41a, 41b and 42, check valves 31a and 31b, a controller 50, and a display device 51.

[0011] Gas tanks 10a and 10b are filled with high-pressure hydrogen gas. Gas tanks 10a (10b) are attached to support bodies 18a (18b). Support bodies 18a (18b) can be repositioned by actuators 19a (19b). The movement of actuators 19a (19b) will be described later. Gas tanks 10a (10b) can only be attached or detached when support bodies 18a (18b) are in a specific position (the detachment position described later).

[0012] The gas tanks 10a and 10b and the fuel cell 90 are connected by a gas supply pipe 30. The gas supply pipe 30 is a gas passage that guides hydrogen gas from the gas tanks 10a and 10b to the fuel cell 90. The gas supply pipe 30 is divided into a first branch pipe 30a and a second branch pipe 30b. The gas tank 10a is connected to the end of the first branch pipe 30a, and the gas tank 10b is connected to the end of the second branch pipe 30b. The first branch pipe 30a and the second branch pipe 30b are connected to a common pipe 30c by a three-way joint 33. The fuel cell 90 is connected to one end of the common pipe 30c. The first branch pipe 30a, the second branch pipe 30b, and the common pipe 30c constitute the gas supply pipe 30.

[0013] A check valve 31a and a pressure sensor 41a are connected to the first branch pipe 30a, and a check valve 31b and a pressure sensor 41b are connected to the second branch pipe 30b. A pressure reducing valve 32 is connected to the common pipe 30c. The pressure reducing valve 32 is located downstream of the check valves 31a and 31b. Here, "downstream" means the side of the gas supply pipe 30 closer to the fuel cell 90 (gas utilization device), and "upstream" means the side closer to the gas tank 10a or 10b.

[0014] The pressure reducing valve 32 reduces the pressure of the hydrogen gas supplied from gas tanks 10a and 10b to a pressure suitable for the operation of the fuel cell 90. In other words, the gas pressure suitable for the fuel cell 90 is lower than the gas pressure supplied from gas tanks 10a and 10b. Initially, gas tanks 10a and 10b are filled with hydrogen gas to a pressure higher than the pressure suitable for the operation of the fuel cell 90.

[0015] The check valves 31a and 31b allow gas to pass from upstream to downstream, but prevent gas from flowing from downstream to upstream. The check valves 31a (31b) prevent hydrogen gas from leaking to the outside from downstream of the check valves 31a (31b) when the gas tank 10a (10b) is disconnected from the gas supply pipe 30. In addition, the check valves 31a (31b) prevent hydrogen gas from leaking to the outside from downstream of the check valves 31a (31b) if a gas leak occurs at the connection point between the gas tank 10a (10b) and the gas supply pipe 30.

[0016] The pressure sensor 41a (41b) measures the pressure inside the gas supply pipe 30 upstream of the check valve 31a (31b). If the gas tank 10a (10b) is connected to the gas supply pipe 30, the value measured by the pressure sensor 41a (41b) is equal to the pressure in the gas tank 10a (10b). As mentioned earlier, "pressure in the gas tank 10a (10b)" means the pressure inside the gas tank 10a (10b) (i.e., the internal pressure of the gas tank).

[0017] The pressure sensor 42 measures the pressure in the gas supply pipe 30 downstream of the check valves 31a and 31b. While gas is being supplied from the gas tank 10a (or gas tank 10b), the value measured by the pressure sensor 42 is equal to the value measured by the pressure sensor 41a (or 41b). When the gas tank 10a (10b) is disconnected from the gas supply pipe 30, the pressure in the first branch pipe 30a (second branch pipe 30b) drops to atmospheric pressure, but because the check valve 31a (31b) is present, the value measured by the pressure sensor 42 (i.e., the pressure in the common pipe 30c) does not drop.

[0018] A main shut-off valve 20a (20b) is incorporated into the valve 11 of the gas tank 10a (10b). The lower part of Figure 1 shows a cross-sectional view of the valve 11 of the gas tank 10a and the end of the gas supply pipe 30 (the end of the first branch pipe 30a). The valve 11 of the gas tank 10a is equipped with a main shut-off valve 20a. The main shut-off valve 20a includes a sleeve 21, a valve body 22, and a spring 23. The sleeve 21 is mounted inside the valve 11. The valve body 22 is positioned adjacent to the sleeve 21 inside the tank. The spring 23 presses the valve body 22 against the opening of the sleeve 21 (the opening that is open inside the tank) from the inside of the tank. The opposite end of the spring 23 is supported by the inner wall of the tank.

[0019] By the force of the spring 23, the valve body 22 adheres closely to the opening of the sleeve 21. While the valve body 22 is adhering closely to the opening of the sleeve 21, the main check valve 20a is closed. When the valve body 22 is pushed from the outside to the inside of the tank, the main check valve 20a opens. When the load on the valve body 22 disappears, the valve body 22 adheres closely to the opening of the sleeve 21 again by the force of the spring 23, and the main check valve 20a closes. Such a main check valve is sometimes called a "Self Closing Valve".

[0020] A push rod 35 is provided at the tip of the gas supply pipe 30 (the tip of the first branch pipe 30a). The push rod 35 is fixed to the tip of the gas supply pipe 30 by a rod support 36. The rod support 36 is provided with a hole, and gas can flow from the gas tank 10a into the gas supply pipe 30 through the hole.

[0021] When the gas tank 10a is set on the support 18a, the push rod 35 at the tip of the gas supply pipe 30 faces the base 11. The actuator 19a moves the first support 18a on which the gas tank 10a is set. The actuator 19a moves the support 18a (that is, the gas tank 10a) closer to or farther away from the gas supply pipe 30. In other words, the actuator 19a moves the main check valve 20a closer to or farther away from the tip of the gas supply pipe 30 (that is, the push rod 35). The cross-sectional view of FIG. 1 shows a state where the push rod 35 is separated from the main check valve 20a.

[0022] The actuator 19a moves the support 18a (gas tank 10a) relatively forward and backward with respect to the tip of the gas supply pipe 30. For the sake of explanation, the case where the support 18a (gas tank 10a) approaches the gas supply pipe 30 is called "forward movement", and the case where the gas tank 10a moves away from the gas supply pipe 30 is called "backward movement". The actuator 19a may move the gas supply pipe 30 forward and backward with respect to the support 18a (gas tank 10a).

[0023] A sealing 12 is positioned inside the valve 11. When the tip of the gas supply pipe 30 (push rod 35) approaches the main shut-off valve 20a, the outer circumference of the gas supply pipe 30 comes into contact with the sealing 12, sealing the space including the opening of the main shut-off valve 20a (the opening that opens to the outside of the gas tank 10a) and the tip of the gas supply pipe 30. For convenience, the space including the opening of the main shut-off valve 20a and the tip of the gas supply pipe 30 is referred to as the connection space S. More precisely, the connection space S refers to the space inside the valve 11 that includes the opening of the main shut-off valve 20a and the tip of the gas supply pipe 30. In the cross-sectional view of Figure 1, the push rod 35 is away from the main shut-off valve 20a, and a gap G is secured between the tip of the gas supply pipe 30 and the sealing 12. In this state, the connection space S is not sealed to the outside.

[0024] Figure 2 shows a cross-section when the tip of the gas supply pipe 30 is in contact with the seal 12. When the distance between the push rod 35 and the main shut-off valve 20a reaches L1, the seal 12 comes into contact with the outer circumference of the gas supply pipe 30, sealing the connection space S. In other words, when the distance between the push rod 35 and the valve body 22 of the main shut-off valve 20a becomes shorter than L1, the connection space S is isolated from the outside world. When the distance between the push rod 35 and the valve body 22 is L1, the main shut-off valve 20a remains closed. The distance L1 may be called the threshold distance.

[0025] The dashed line in Figure 2 shows the state where the support body 18a (gas tank 10a) has advanced until the valve body 22 contacts the tip of the push rod 35. When the gas tank 10a advances further than the dashed line, the push rod 35 pushes open the main shut-off valve 20a. Figure 3 is a cross-sectional view when the support body 18a (gas tank 10a) has advanced until the main shut-off valve 20a is open. The thick arrow A indicates the flow of gas. While the main shut-off valve 20a is open, the hydrogen gas in the gas tank 10a flows through the connection space S to the gas supply pipe 30. Since the connection space S is sealed by the seal 12, the hydrogen gas does not leak to the outside.

[0026] The gas in the gas tank 10a passes through the open main shut-off valve 20a, through the hole in the rod support 36, and flows to the gas supply pipe 30. For the sake of explanation, the position of the support 18a (gas tank 10a) when the connection space S is sealed is referred to as the connection position. Figure 2 shows the connection position when the main shut-off valve 20a is closed. Figure 3 shows the connection position when the main shut-off valve 20a is open. The connection position when the main shut-off valve 20a is open (the position of the support 18a (gas tank 10a) when the connection space S is sealed and the main shut-off valve 20a is open) is specifically referred to as the connection (valve open) position. Conversely, the position of the support 18a (gas tank 10a) when the connection space S is sealed but the main shut-off valve 20a is closed is referred to as the connection (valve closed) position. Furthermore, the position of the support 18a (gas tank 10a) when the gas tank 10a is retracted and the sealing of the connection space S is released, allowing the connection space S to be connected to the outside world, is referred to as the detachment position (see Figure 1).

[0027] Although a detailed diagram of the mechanism is omitted, when the support 18a to which the gas tank 10a is attached is in the connection position, the gas tank 10a cannot be detached from the support 18a. The gas tank 10a can only be attached to and detached from the support 18a when the support 18a is in the detachment position.

[0028] Figures 2 and 3 show cross-sections in the connection position, and Figure 3 shows a cross-section in the connection (valve open) position. When the support 18a to which the gas tank 10a is attached is in the connection position (either the connection (valve closed) position or the connection (valve open) position), the gas tank 10a is said to be connected to the gas supply pipe 30.

[0029] When a new gas tank 10a is set on the support 18a, the controller 50 (see Figure 1) controls the actuator 19a to advance the support 18a (gas tank 10a) to the connected (valve open) position. The main shut-off valve 20a opens, and the gas from the gas tank 10a flows through the check valve 31a and the pressure reducing valve 32 to the fuel cell 90. The fuel cell 90 becomes operational. The controller 50 activates the fuel cell 90.

[0030] The structure of the gas tank 10b and the tip of the second branch pipe 30b is the same as the structure of the gas tank 10a and the tip of the first branch pipe 30a. The gas tank 10b has a main shut-off valve 20b. The structure of the main shut-off valve 20b is the same as the structure of the main shut-off valve 20a. The gas tank 10b is attached to the support 18b. The support 18b (gas tank 10b) moves between a detached position and a connected position by an actuator 19b.

[0031] Prior to operating the fuel cell 90, gas tanks 10a and 10b are set on supports 18a and 18b, respectively. The gas tanks 10a and 10b set on supports 18a and 18b are filled with gas to a pressure higher than the pressure suitable for operating the fuel cell 90. The controller 50 controls actuator 19a to move support 18a (gas tank 10a) from the detachment position to the connection position (connected (valve closed) position), and controls actuator 19b to move support 18b (gas tank 10b) from the detachment position to the connection position (connected (valve closed) position). In the connection position, gas tanks 10a and 10b are connected to the gas supply pipe 30.

[0032] The controller 50 alternately moves the supports 18a and 18b to the connected (open) position. The controller 50 alternately uses the gas tanks 10a and 10b, allowing the other gas tank to be replaced while gas is being supplied from one gas tank to the fuel cell 90.

[0033] Figure 4 shows a flowchart of the gas tank replacement preparation process performed by the controller 50. Hereinafter, gas tank 10a will be referred to as the first gas tank 10a, and gas tank 10b as the second gas tank 10b. Alternatively, main shut-off valve 20a will be referred to as the first main shut-off valve 20a, and main shut-off valve 20b as the second main shut-off valve 20b. Furthermore, support members 18a and 18b will be referred to as the first support member 18a and the second support member 18b, respectively, and actuators 19a and 19b will be referred to as the first actuator 19a and the second actuator 19b, respectively.

[0034] The controller 50 controls actuators 19a and 19b, moving the first support 18a to the connected (open) position while keeping the second support 18b in the connected (closed) position. That is, the controller 50 keeps the second main shut-off valve 20b of the second gas tank 10b closed and opens the first main shut-off valve 20a of the first gas tank 10a (step S12). Gas is supplied from the first gas tank 10a to the fuel cell 90. The controller 50 starts operating the fuel cell 90.

[0035] As the fuel cell 90 continues to operate, the pressure in the first gas tank 10a decreases. In other words, the remaining amount in the first gas tank 10a decreases. The controller 50 waits until the pressure in the first gas tank 10a reaches the lower pressure limit (step S13). The lower pressure limit is set to a value higher than the gas pressure suitable for the operation of the fuel cell 90 (the pressure downstream of the pressure reducing valve 32).

[0036] When the pressure in the first gas tank 10a reaches the lower pressure limit, the controller 50 controls the first actuator 19a and the second actuator 19b to move the first support 18a, which is in the connected (open) position, to the connected (closed) position, and the second support 18b, which is in the connected (closed) position, to the connected (open) position. In other words, the controller 50 closes the first main shut-off valve 20a and opens the second main shut-off valve 20b (step S14). Gas begins to be supplied from the fully filled second gas tank 10b to the fuel cell 90. Next, the controller 50 controls the first actuator 19a to move the first support 18a (i.e., the first gas tank 10a), which is in the connected (closed) position, to the detachable position (step S15). The controller 50 outputs a first gas tank replacement permission signal to the display device 51 (step S16). Upon receiving the signal granting permission to replace the first gas tank, the display device 51 displays a message prompting the user to replace the first gas tank 10a (or illuminates a lamp prompting the user to replace the first gas tank 10a).

[0037] As mentioned earlier, when the first support 18a is in the detachable position, the first gas tank 10a can be detached from the first support 18a. The user, upon seeing the message on the display device 51, replaces the first gas tank 10a. Although not shown in the diagram, the first support 18a and the second support 18b are equipped with detachment sensors that detect when the gas tank has been removed and when the gas tank has been attached. The controller 50 detects that the first gas tank 10a has been replaced based on the signals from the detachment sensors.

[0038] Upon detecting that the first gas tank 10a has been replaced, the controller 50 controls the first actuator 19a to move the first support 18a (first gas tank 10a) from the detachment position to the connection (valve closed) position (step S17). In other words, the controller 50 connects the first gas tank 10a to the gas supply pipe 30 and prepares for the replacement of the second gas tank 10b.

[0039] The controller 50 waits until the pressure in the second gas tank 10b reaches the lower pressure limit. Subsequently, steps S14 to S17 are executed by swapping "first" and "second" in the flowchart of Figure 4. In this way, the first gas tank 10a and the second gas tank 10b can be alternately exchanged without stopping the fuel cell 90.

[0040] Figure 5 shows a time chart illustrating the replacement timing for each of the two gas tanks. The topmost of the three time charts shows the hydrogen gas supply status from the gas tank to the fuel cell 90. Between time T0 and time T1, the user sets the first gas tank 10a on the first support 18a, which is in the detachable position, and sets the second gas tank 10b on the second support 18b, which is also in the detachable position. The controller 50 moves the first / second support 18a and 18b to the connected (closed valve) position and connects the first / second gas tanks 10a and 10b set on the first / second support 18a and 18b to the gas supply pipe 30. At time T1, the controller 50 opens the first main shut-off valve 20a while keeping the second main shut-off valve 20b closed. The controller 50 starts operating the fuel cell 90. As the fuel cell 90 operates, the pressure in the first gas tank 10a decreases.

[0041] At time T2, the pressure in the first gas tank 10a reaches the lower pressure limit. At time T2, the controller 50 closes the first main shut-off valve 20a and opens the second main shut-off valve 20b. Gas is supplied from the second gas tank 10b to the fuel cell 90. The controller 50 moves the first support 18a (first gas tank 10a) to the detachable position. The first gas tank 10a of the first support 18a, which has moved to the detachable position, becomes detachable. Since the first branch pipe 30a to which the first gas tank 10a was connected is equipped with a check valve 31a, even if the first support 18a (first gas tank 10a) is moved from the connected (valve closed) position to the detachable position, gas from the second gas tank 10b will not leak to the outside through the first branch pipe 30a.

[0042] While gas is being supplied from the second gas tank 10b to the fuel cell 90, between time T3 and time T4, the user replaces the old first gas tank 10a with a new first gas tank 10a that is fully filled with gas. The controller 50 moves the first support 18a (first gas tank 10a) to the connected (valve closed) position. That is, the controller 50 connects the first gas tank 10a to the gas supply pipe 30.

[0043] At time T5, the pressure in the second gas tank 10b drops to the lower pressure limit. At time T5, the controller 50 closes the second main shut-off valve 20b and opens the first main shut-off valve 20a. Gas begins to be supplied from the first gas tank 10a to the fuel cell 90. The controller 50 moves the second support 18b (second gas tank 10b) from the connected (valve closed) position to the detachable position. The second gas tank 10b, having moved to the detachable position, becomes detachable. As in the previous case, the second branch pipe 30b is equipped with a check valve 31b, so gas from the second gas tank 10b does not leak to the outside through the second branch pipe 30b.

[0044] While gas is being supplied from the first gas tank 10a to the fuel cell 90, between time T6 and time T7, the user replaces the old second gas tank 10b with a new second gas tank 10b that is fully filled with gas. The controller 50 moves the second support 18b (second gas tank 10b) to the connected (valve closed) position. That is, the controller 50 connects the second gas tank 10b to the gas supply pipe 30.

[0045] The above process is repeated while the fuel cell 90 is in operation. The gas supply system 2 can replace the gas tank without interrupting the gas supply to the fuel cell 90.

[0046] The following points concern the technology described in the embodiment. The gas supply system 2 of the embodiment is equipped with two gas tanks (first gas tank 10a and second gas tank 10b), and the two gas tanks are moved alternately to a position where they can be replaced (detachable position). While one gas tank is in the detachable position, the other gas tank is connected to the gas supply pipe 30, the main shut-off valve is opened, and gas is supplied to the fuel cell 90. The gas tank replacement preparation process performed by the controller 50 is as follows.

[0047] (1) When the first gas tank 10a is set on the first support 18a, the controller 50 controls the first actuator 19a to move the first support 18a to the connected (closed valve) position. When the second gas tank 10b is set on the second support 18b, the controller 50 controls the second actuator 19b to move the second support 18b to the connected (closed valve) position.

[0048] (2) The controller 50 moves the first support 18a to the connected (open) position while keeping the second support 18b in the connected (closed) position. That is, the controller 50 opens the first main shut-off valve 20a while keeping the second main shut-off valve 20b closed, and starts supplying gas from the first gas tank 10a to the fuel cell 90. (3) When the pressure in the first gas tank 10a drops to the lower pressure limit, the controller 50 moves the first support 18a to the detachable position and moves the second support 18b to the connected (open) position. That is, when the pressure in the first gas tank 10a drops to the lower pressure limit, the controller 50 closes the first main shut-off valve 20a, opens the second main shut-off valve 20b, and moves the first support 18a to the detachable position. When the first support 18a moves to the detachable position, the first gas tank 10a becomes replaceable.

[0049] The gas supply system may include three or more gas tanks. The fuel cell 90 in this embodiment is an example of a gas utilization device. The gas utilization device may be a device other than the fuel cell 90.

[0050] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. The technical elements described in this specification or drawings exhibit technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of symbols]

[0051] 2: Gas supply system 10a, 10b: Gas tank 11: Valve 12: Sealing 19a, 19b: Actuator 20a, 20b: Main shut-off valve 21: Sleeve 22: Valve body 23: Spring 30: Gas supply pipe 30a, 30b: Branch pipe 30c: Common pipe 31a, 31b: Check valve 32: Pressure reducing valve 35: Push rod 36: Rod support 41a, 41b, 42: Pressure sensor 50: Controller 51: Display device 90: Fuel cell

Claims

[Claim 1] A first support that supports the first gas tank, A second support that supports the second gas tank, A gas supply pipe that guides gas to a gas utilization device, A first actuator moves the first support between a connection position in which the first gas tank is connected to the gas supply pipe and a detachment position in which the first gas tank can be attached and detached, A second actuator moves the second support between a connection position in which the second gas tank is connected to the gas supply pipe and a detachment position in which the second gas tank can be attached and detached, A first main shut-off valve that opens and closes the gas flow path between the first gas tank and the gas utilization device, A second main shut-off valve that opens and closes the gas flow path between the second gas tank and the gas utilization device, It is equipped with a controller, The controller is When the first gas tank is set on the first support, the first actuator is controlled to move the first support to the connection position, and when the second gas tank is set on the second support, the second actuator is controlled to move the second support to the connection position. With the second main shut-off valve closed, the first main shut-off valve is opened to supply gas from the first gas tank to the gas utilization device. When the pressure in the first gas tank reaches the lower pressure limit, the first main shut-off valve is closed, the second main shut-off valve is opened, and the first support is moved to the detachable position. Gas supply system.

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