A hydrogen release and recovery system when the compressor of a hydrogen refueling station is shut down

Abstract

The present invention provides a hydrogen gas discharge and recovery system when the compressor of a hydrogen filling station stops, which belongs to the field of hydrogen energy utilization technology. The system includes: an air intake buffer tank, a first-stage cylinder head, an interstage buffer tank, a first-stage cooler, a second-stage cylinder head, a second-stage cooler and a high-pressure hydrogen storage tank connected in sequence. The air intake buffer tank is connected to the discharge port of the long tube trailer. The hydrogen in the long tube trailer enters the high-pressure hydrogen storage tank for storage after two buffering, compression and cooling. The second-stage cooler is connected to the recovery hydrogen storage tank through a discharge recovery pipeline near the side of the high-pressure hydrogen storage tank. A flow regulating valve and an air-driven booster pump are provided on the discharge recovery pipeline. The recovery hydrogen storage tank is equipped with a first pressure sensor, and the first pneumatic valve and the air-driven booster pump are both electrically connected to the controller. The system can recover the discharged hydrogen when the compressor stops due to excessive boost, and utilize the recovered hydrogen after starting up, so as to avoid safety hazards and economic losses caused by hydrogen discharge.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrogen energy utilization, and in particular to a hydrogen gas release and recovery system when a compressor of a hydrogen filling station is shut down. Background Art

[0002] Energy is the cornerstone of human existence and the driving force of development. With the development of society and the challenge of fossil fuel depletion, countries around the world have recently focused on the development of new energy sources. Hydrogen energy, among other advantages, has gained popularity due to its cleanliness, pollution-free nature, and high efficiency.

[0003] Currently, the relevant technologies and engineering applications for hydrogen refueling stations have been gradually promoted. Processes and equipment are becoming increasingly mature, standards and specifications are becoming increasingly complete, and operations are generally safe and reliable. Among the various equipment in a hydrogen refueling station, the hydrogen compressor is the most important piece of equipment, boosting the low-pressure hydrogen gas and passing it to high-pressure hydrogen storage equipment or vehicles. There are various types of hydrogen compressors, including hydrogen diaphragm compressors, piston compressors, gas-driven pumps, and liquid-driven pumps. Diaphragm compressors are the preferred compressor for hydrogen refueling station construction due to their advantages such as pollution-free operation, high pressure ratio, no leakage, and near-isothermal compression. Since foreign passenger cars all use 70MPa hydrogen storage cylinders, while domestic commercial vehicles currently primarily use 35MPa cylinders, 70MPa hydrogen refueling stations will be the future development direction of hydrogen refueling stations due to the limitations of driving range and hydrogen storage capacity. Therefore, the economic and safety of diaphragm compressors used in 70MPa hydrogen refueling stations will also attract much attention. Because diaphragm compressors require light-load startup, diaphragm deformation during shutdown, and positive pressure within the system, they must release hydrogen during shutdown to meet these requirements. However, hydrogen release directly impacts the economic benefits of hydrogen refueling stations and poses safety risks. Invention patent applications CN115653879A, "A Hydraulically Driven Multi-Stage Diaphragm Compressor," and CN115750299A, "A 90MPa Diaphragm Compressor," both address diaphragm compressors, but neither addresses the recovery and reuse of hydrogen released during compressor shutdown.

[0004] When the high-pressure hydrogen compressor in the hydrogen refueling station is working, the hydrogen in the long tube trailer is discharged into the high-pressure hydrogen storage tank after being cooled through the air intake buffer tank, the first-stage cylinder head compression, the interstage buffer tank, the first-stage cooler, the second-stage cylinder head compressor, and the second-stage cooler for hydrogen refueling of hydrogen fuel cell vehicles. During the entire compression process, the hydrogen pressure in the long tube trailer decreases, and the hydrogen pressure in the high-pressure hydrogen storage tank increases, which is a non-steady-state compression throughout the process.

[0005] The storage pressure of the high-pressure hydrogen storage tank in a 70MPa hydrogen refueling station is 87.5MPa. The compressor needs to be shut down when the pressure reaches 87.5MPa. Since the compressor needs to start under light load, that is, the gas pressure in the compression chamber cannot be too high, to prevent the compressor from failing to start the next time (i.e., the compressor starts and dies). In addition, the compressor diaphragm should be in a non-deformed state when it is stopped to extend the diaphragm service life. At the same time, the hydrogen in the compression system should maintain a certain positive pressure to prevent air from entering and causing the potential explosion risk of hydrogen and air mixing. For the above reasons, when the compressor is stopped, the hydrogen medium pressure in the compressor system itself needs to be vented to 0.3-0.6MPa.

[0006] Because the 90MPa high-pressure compressor at a hydrogen refueling station has a relatively high pressure, two-stage compression is required. The compressor needs to be equipped with an intake buffer tank and an interstage buffer tank. For example, assuming an average intake pressure of 12.5MPa, an exhaust pressure of 87.5MPa, an intake buffer tank of 29L, and an interstage buffer tank of 8L, and ignoring hydrogen storage in the compressor system pipelines, the mass of hydrogen released during a shutdown is calculated to be 0.44kg. Based on a 12-hour operation with four starts and stops per day, the total amount of hydrogen released per day is 1.76kg, 52.8kg per month, and 633.6kg per year. At the current price of 50 yuan per kg, the annual loss is approximately 31,680 yuan, seriously affecting the economic benefits of the hydrogen refueling station. Furthermore, each hydrogen release during a shutdown poses a safety hazard.

[0007] In order to solve the above problems, the present invention proposes a hydrogen release and recovery system when the compressor of a hydrogen refueling station is shut down, which can recover and reuse the hydrogen medium in the compressor system when the compressor is shut down. Summary of the Invention

[0008] The purpose of the present invention is to provide a hydrogen gas leakage and recovery system when the compressor of a hydrogen refueling station is shut down. The system can recover the leaked hydrogen when the diaphragm compressor is shut down due to excessive boost, and utilize the recovered hydrogen after restarting, thereby avoiding safety hazards and economic losses caused by hydrogen leakage.

[0009] The present invention provides a hydrogen discharge and recovery system when the compressor of a hydrogen refueling station is shut down, comprising: an air intake buffer tank, a first-stage cylinder head, an interstage buffer tank, a first-stage cooler, a second-stage cylinder head, a second-stage cooler and a high-pressure hydrogen storage tank connected in sequence, the air intake buffer tank is connected to the discharge port of a long tube trailer through a first pneumatic valve, the first-stage cylinder head and the second-stage cylinder head are respectively connected to the two ends of the crankcase, the hydrogen in the long tube trailer enters the high-pressure hydrogen storage tank for storage after two buffering, compression and cooling, the side of the secondary cooler close to the high-pressure hydrogen storage tank is connected to the recovery hydrogen storage tank through a discharge and recovery pipeline, a flow regulating valve and an air-driven booster pump are provided on the discharge and recovery hydrogen storage tank, a first pressure sensor is installed on the recovery hydrogen storage tank, and the first pneumatic valve and the air-driven booster pump are both electrically connected to a controller.

[0010] Preferably, the discharge recovery pipeline includes a first branch, a second branch and a third branch, wherein the first branch is connected to the vent through the flow regulating valve, the second pneumatic valve and the first one-way valve in sequence, the second branch is connected to the intake buffer tank through the third pneumatic valve, and the side of the flow regulating valve close to the second pneumatic valve is connected to the recovery hydrogen storage tank through the third branch. The air-driven booster pump is arranged on the third branch, and the fourth pneumatic valve and the second one-way valve are connected to the two sides of the air-driven booster pump respectively. The second pneumatic valve, the third pneumatic valve and the fourth pneumatic valve are all electrically connected to the controller.

[0011] Preferably, the secondary cooler is connected to the high-pressure hydrogen storage tank through the second pressure sensor, the third one-way valve, the fifth pneumatic valve and the main exhaust valve in sequence, and the fifth pneumatic valve is electrically connected to the controller.

[0012] Preferably, the tank port of the hydrogen recovery tank is connected to a sixth pneumatic valve, the sixth pneumatic valve is communicated with the third branch, and the sixth pneumatic valve is electrically connected to the controller.

[0013] Preferably, the discharge port of the tube trailer is further connected to a seventh pneumatic valve, and the seventh pneumatic valve is electrically connected to the controller.

[0014] Preferably, an inlet filter is connected between the seventh pneumatic valve and the air intake buffer tank.

[0015] Preferably, the recovered hydrogen storage tank is connected to the air intake buffer tank via an eighth pneumatic valve, and the eighth pneumatic valve is electrically connected to the controller.

[0016] Preferably, a third pressure sensor is connected between the intake buffer tank and the first-stage cylinder head.

[0017] Preferably, a fourth pressure sensor is connected between the primary cooler and the secondary cylinder head.

[0018] Preferably, the controller is a PLC host.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. By connecting a flow control valve, an air-driven booster pump, and a recovery hydrogen storage tank to the hydrogen compression storage system of the hydrogen refueling station, the controller controls the first pneumatic valve to close when the compressor stops, stops the delivery of hydrogen from the long tube trailer to the high-pressure hydrogen storage tank, and activates the discharge and recovery control logic through the controller. The hydrogen in the compression system that needs to be discharged is passed through the flow control valve and the air-driven booster pump to the recovery hydrogen storage tank for recovery, avoiding the safety hazard caused by direct discharge of hydrogen when the compressor stops, and recovering and reusing hydrogen to improve economic benefits;

[0021] 2. When starting up, the hydrogen in the recovered hydrogen storage tank can be used first, which is independent of the normal operation process of the compressor. This makes up for the defect of hydrogen release when the compressor is shut down, thereby improving the economic benefits of the hydrogen refueling station and reducing the safety hazards caused by hydrogen release. At the same time, it can provide a reference for other types of compressors that are shut down and released. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 Schematic diagram of the connection principle and medium flow direction of the system of the present invention;

[0024] Description of reference numerals:

[0025] 1: Tube trailer; 2: Intake buffer tank; 3: First stage cylinder head; 4: Interstage buffer tank; 5: First stage cooler; 6: Second stage cylinder head; 7: Second stage cooler; 8: High-pressure hydrogen storage tank; 9: Crankcase; 10: Drain recovery pipeline; 101: First branch; 102: Second branch; 103: Third branch; 11: Hydrogen recovery tank; 12: Flow control valve; 13: Air-driven booster pump; 14: Controller; 15: Vent port; 16: Main exhaust valve; 17: Inlet filter;

[0026] V1: first pneumatic valve; V2: second pneumatic valve; V3: third pneumatic valve; V4: fourth pneumatic valve; V5: fifth pneumatic valve; V6: sixth pneumatic valve; V7: seventh pneumatic valve; V8: eighth pneumatic valve; RV1: first one-way valve; RV2: second one-way valve; RV3: third one-way valve; P1: second pressure sensor; P2: second pressure sensor; P3: third pressure sensor; P4: fourth pressure sensor. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operate in a specific direction, and therefore should not be understood as limiting the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0030] like Figure 1As shown, the present invention provides a hydrogen discharge and recovery system when the compressor of a hydrogen refueling station is shut down, comprising: an air intake buffer tank 2, a first-stage cylinder head 3, an interstage buffer tank 4, a first-stage cooler 5, a second-stage cylinder head 6, a second-stage cooler 7 and a high-pressure hydrogen storage tank 8 connected in sequence, wherein the air intake buffer tank 2 is connected to the discharge port of the long tube trailer 1 through a first pneumatic valve V1, the first-stage cylinder head 3 and the second-stage cylinder head 6 are respectively connected to the two ends of the crankcase 9, and the hydrogen contained in the long tube trailer 1 enters the high-pressure hydrogen storage tank 8 for storage after being buffered, compressed and cooled twice at the hydrogen refueling station, and the side of the secondary cooler close to the high-pressure hydrogen storage tank 8 is connected to the recovery hydrogen storage tank 11 through a discharge recovery pipeline 10, and the discharge recovery pipeline 10 is provided with a flow regulating valve 12 and an air-driven booster pump 13, and the recovery hydrogen storage tank 11 is installed with a first pressure sensor P1. The first pneumatic valve V1 and the air-driven booster pump 13 are both electrically connected to the controller 14. The controller 14 can control the first pneumatic valve V1 to close when the compressor stops, stop the long tube trailer 1 from transporting hydrogen to the high-pressure hydrogen storage tank 8, and start the discharge and recovery control logic through the controller 14. The hydrogen in the compression system to be discharged is passed through the flow regulating valve 12 and the air-driven booster pump 13 to the recovery hydrogen storage tank 11 for recovery, avoiding the direct discharge of hydrogen when the compressor stops and causing safety hazards, and recovering and reusing the hydrogen to improve economic benefits.

[0031] Specifically, the discharge recovery pipeline 10 includes a first branch 101, a second branch 102 and a third branch 103, wherein the first branch 101 is connected to the vent 15 through the flow regulating valve 12, the second pneumatic valve V2 and the first one-way valve RV1 in sequence, the second branch 102 is connected to the intake buffer tank 2 through the third pneumatic valve V3, and the side of the flow regulating valve 12 close to the second pneumatic valve V2 is connected to the recovery hydrogen storage tank 11 through the third branch. The air-driven booster pump 13 is arranged on the third branch 103, and the fourth pneumatic valve V4 and the second one-way valve RV2 are connected to both sides of the air-driven booster pump 13 respectively. The second pneumatic valve V2, the third pneumatic valve V3 and the fourth pneumatic valve V4 are all electrically connected to the controller 14. When the compressor stops, the controller 14 controls the second pneumatic valve V2 to close to prevent hydrogen from leaking out of the vent 15. The residual hydrogen in the interstage buffer tank 4 is recovered to the recovery hydrogen storage tank 11 through the discharge recovery pipeline 10 and the third branch 103. The residual hydrogen in the intake buffer tank 2 is recovered to the recovery hydrogen storage tank 11 through the second branch 102, the flow regulating valve 12 and the third branch 103. It can be used after the subsequent compressor operates normally, avoiding waste caused by direct discharge.

[0032] In this embodiment, the secondary cooler 7 is connected to the high-pressure hydrogen storage tank 8 through the second pressure sensor P2, the third one-way valve RV3, the fifth pneumatic valve V5 and the main exhaust valve 16 in sequence. The fifth pneumatic valve V5 is electrically connected to the controller 14. When the compressor stops, the controller 14 controls the fifth pneumatic valve V5 to close to prevent hydrogen from continuing to flow into the high-pressure hydrogen storage tank 8.

[0033] In this embodiment, the outlet of the hydrogen recovery tank 11 is connected to a sixth pneumatic valve V6, which is in communication with the third branch 103 and electrically connected to the controller 14. Opening and closing the sixth pneumatic valve V6 controls whether hydrogen continues to be recovered from the hydrogen recovery tank 11. It also controls whether hydrogen is fed from the hydrogen recovery tank 11 to the intake buffer tank 2 when the compressor is turned on, thereby prioritizing the use of recovered hydrogen. The outlet of the tube trailer 1 is also connected to a seventh pneumatic valve V7, which is electrically connected to the controller 14. The hydrogen recovery tank 11 is connected to the intake buffer tank 2 via an eighth pneumatic valve V8, which is also electrically connected to the controller 14. When the hydrogen in the recovered hydrogen storage tank 11 is preferentially passed into the air intake buffer tank 2 for utilization, the controller 14 controls the sixth pneumatic valve V6, the eighth pneumatic valve V8 and the first pneumatic valve V1 to be in an open state, and the seventh pneumatic valve V7 to be in a closed state, so as to prevent the hydrogen from flowing out of the long tube trailer 1, and preferentially pass the hydrogen in the recovered hydrogen storage tank 11 into the air intake buffer tank 2, so as to realize the recovery and reuse of the hydrogen leaked when the compressor is shut down, thereby improving its economic benefits.

[0034] In this embodiment, an inlet filter 17 is further connected to the total inlet between the seventh pneumatic valve V7 and the air intake buffer tank 2. The inlet filter 17 can filter the hydrogen flowing out of the long tube trailer 1 and the recovery hydrogen storage tank 11, absorb impurities such as moisture and fine particles contained therein, and then perform subsequent buffering, compression and cooling steps.

[0035] In this embodiment, a third pressure sensor P3 is connected between the intake buffer tank 2 and the first-stage cylinder head 3, and a fourth pressure sensor P4 is connected between the first-stage cooler 5 and the second-stage cylinder head 6. When the pressure value of pressure sensor P4 reaches approximately 0.6 MPa, hydrogen recovery in the compression system is stopped. The next time the compressor is started, the controller 14 prioritizes the use of hydrogen recovered from the hydrogen storage tank. When the pressure value of the first pressure sensor P1 reaches approximately 2 MPa, the use of hydrogen recovered from the hydrogen storage tank 11 is stopped. This allows for the recovery and reuse of released hydrogen, reduces safety hazards caused by hydrogen release, and improves the economic benefits of the hydrogen refueling station.

[0036] In this embodiment, the controller 14 is a PLC host, which can realize automatic opening and closing control of each pneumatic valve and the air-driven booster pump 13.

[0037] The specific implementation steps of the present invention are as follows:

[0038] (1) When the high-pressure hydrogen compressor of the hydrogen refueling station is working normally, the hydrogen in the long tube trailer 1 is pressurized to the high-pressure hydrogen storage tank 8 of the hydrogen refueling station through the seventh pneumatic valve V7, the inlet filter 17, the first pneumatic valve V1, the air intake buffer tank 2, the first-stage cylinder head 3, the interstage buffer tank 4, the first-stage cooler 5, the second-stage cylinder head 6, the second-stage cooler 7, and the fifth pneumatic valve V5. At the same time, under the action of the controller 14, the eighth pneumatic valve V8, the sixth pneumatic valve V6, the fourth pneumatic valve V4, and the second pneumatic valve V2 in the discharge and recovery system are closed, and the air-driven booster pump 13 stops running, that is, the discharge and recovery system does not work;

[0039] (2) When the high-pressure hydrogen storage tank 8 in the hydrogen refueling station is pressurized to 87.5 MPa, the compressor must stop running, that is, the compressor main engine stops, the first pneumatic valve V1 and the fifth pneumatic valve V5 are closed, and at the same time the fourth pneumatic valve V4, the sixth pneumatic valve V6, and the third pneumatic valve V3 are opened, and the air-driven booster pump 13 is started. The hydrogen in the intake buffer tank 2 and the interstage buffer tank 4 is pressurized to the recovery hydrogen storage tank 11 by the air-driven booster pump 13 until the fourth pressure sensor P4 is about 0.6 MPa, and the compression and recovery of hydrogen stops;

[0040] (3) When the compressor is restarted, the seventh pneumatic valve V7 is closed, the sixth pneumatic valve V6 and the eighth pneumatic valve V8 are opened, and the hydrogen in the recovered hydrogen storage tank 11 is preferentially used for compression and pressurization to the high-pressure hydrogen storage tank 8. When the value of the first pressure sensor P1 on the recovered hydrogen storage tank 11 is 2MPa, the use of the hydrogen in the recovered hydrogen storage tank 11 is stopped, the sixth pneumatic valve V6 and the eighth pneumatic valve V8 are closed, and the seventh pneumatic valve V7 is opened. The hydrogen in the long tube trailer 1 is pressurized by the compressor and passed to the high-pressure hydrogen storage tank 8 of the hydrogen refueling station for storage.

[0041] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydrogen gas release and recovery system when the compressor of a hydrogen refueling station is shut down, characterized in that: include: The intake buffer tank, the first-stage cylinder head, the interstage buffer tank, the first-stage cooler, the second-stage cylinder head, the second-stage cooler and the high-pressure hydrogen storage tank are connected in sequence. The intake buffer tank is connected to the discharge port of the long tube trailer through a first pneumatic valve. The first-stage cylinder head and the second-stage cylinder head are respectively connected to the two ends of the crankcase. The hydrogen in the long tube trailer enters the high-pressure hydrogen storage tank for storage after two buffering, compression and cooling. The side of the secondary cooler close to the high-pressure hydrogen storage tank is connected to the recovery hydrogen storage tank through a discharge recovery pipeline. A flow regulating valve and an air-driven booster pump are provided on the discharge recovery pipeline. The discharge recovery pipeline includes a first branch, a second branch and a third branch, wherein the first One branch is connected to the vent through the flow regulating valve, the second pneumatic valve and the first one-way valve in sequence, the second branch is connected to the air intake buffer tank through the third pneumatic valve, the side of the flow regulating valve close to the second pneumatic valve is connected to the recovery hydrogen storage tank through the third branch, the air-driven booster pump is arranged on the third branch, and the fourth pneumatic valve and the second one-way valve are connected on both sides of the air-driven booster pump respectively, the second pneumatic valve, the third pneumatic valve and the fourth pneumatic valve are all electrically connected to the controller, the recovery hydrogen storage tank is installed with a first pressure sensor, and the first pneumatic valve and the air-driven booster pump are both electrically connected to the controller.

2. The hydrogen gas release and recovery system when the hydrogen refueling station compressor is shut down according to claim 1, characterized in that: The secondary cooler is connected to the high-pressure hydrogen storage tank through the second pressure sensor, the third one-way valve, the fifth pneumatic valve and the main exhaust valve in sequence, and the fifth pneumatic valve is electrically connected to the controller.

3. The hydrogen gas release and recovery system when the hydrogen refueling station compressor is shut down according to claim 1, characterized in that: The tank port of the hydrogen recovery tank is connected to a sixth pneumatic valve, the sixth pneumatic valve is communicated with the third branch, and the sixth pneumatic valve is electrically connected to the controller.

4. The hydrogen gas release and recovery system when the hydrogen refueling station compressor is shut down according to claim 1, characterized in that: The discharge port of the tube trailer is further connected to a seventh pneumatic valve, and the seventh pneumatic valve is electrically connected to the controller.

5. The hydrogen gas release and recovery system when the hydrogen refueling station compressor is shut down according to claim 4, characterized in that: An inlet filter is also connected between the seventh pneumatic valve and the air intake buffer tank.

6. The hydrogen gas release and recovery system when the hydrogen refueling station compressor is shut down according to claim 1, characterized in that: The recovered hydrogen storage tank is connected to the air intake buffer tank via an eighth pneumatic valve, and the eighth pneumatic valve is electrically connected to the controller.

7. The hydrogen gas release and recovery system when the compressor of the hydrogen refueling station is shut down according to claim 1, characterized in that: A third pressure sensor is connected between the intake buffer tank and the first-stage cylinder head.

8. The hydrogen gas release and recovery system when the compressor of the hydrogen refueling station is shut down according to claim 1, characterized in that: A fourth pressure sensor is connected between the primary cooler and the secondary cylinder head.

9. The hydrogen gas release and recovery system when the compressor of a hydrogen refueling station is shut down according to any one of claims 1 to 8, characterized in that: The controller is a PLC host.

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