Nitrogen instrument air system for hydrogen production and hydrogenation integrated station and gas supply control method thereof

Abstract

The application relates to a nitrogen instrument air system for a hydrogen production and hydrogenation integrated station and a gas supply control method thereof, belongs to the technical field of gas supply of a hydrogen production and hydrogenation station, and aims to solve the technical problem that the existing instrument air system lacks a backup gas source and is insufficient in pressure when a compressor fails. The system comprises a nitrogen gas supply unit, an instrument air supply unit, a backup communication pipeline, a gas supply distribution unit, a pressure detection assembly and a control unit; a nitrogen gas supply trunk line and an instrument air supply trunk line are communicated through the backup communication pipeline provided with a backup cut-off valve and a pressure regulating valve; when the instrument air pressure is insufficient, the control unit interlocks to open the backup cut-off valve, nitrogen gas is supplemented to the instrument air, the system supply reliability can be improved, the air compressor can be prevented from failing to open the pneumatic valve in the station due to insufficient pressure, hydrogen production equipment and hydrogenation equipment can be supplied with gas through a branch trunk line gas supply distribution mode, the end gas supply pressure can be stabilized, and pressure abnormalities can be found in time and the gas quality can be ensured through the setting of multiple pressure detectors and dew point detectors.

Description

Technical Field

[0001] This invention relates to the field of gas supply technology for hydrogen production and refueling stations, and in particular to a nitrogen instrument air system for integrated hydrogen production and refueling stations and its gas supply control method. Background Technology

[0002] Integrated hydrogen production and refueling stations can simultaneously complete hydrogen production, storage, and refueling operations, serving as a crucial infrastructure for the practical application of the hydrogen energy industry. Numerous pneumatic regulating and shut-off valves within the station rely on instrument air as their power source. The continuous, stable, and qualified air supply from the instrument air system directly determines the controllable operation and safe operation of all process equipment within the station. Furthermore, maintenance and purging of the hydrogen production and refueling units require an independent nitrogen purging system to replace the inert gases in the pipelines and equipment, mitigating safety risks such as hydrogen leaks and explosions.

[0003] Currently, most integrated hydrogen production and refueling stations set up their air instrument ventilation system and nitrogen purging system independently. The gas sources and pipelines of the two systems are completely separate, and the instrument ventilation system has no backup gas supply, relying entirely on the air compressor skid as its sole power source. The hydrogen production unit and the hydrogen refueling unit are two process units with significantly different operating conditions. They do not always operate synchronously, and the gas consumption fluctuates greatly under different operating conditions, placing high demands on gas supply distribution and terminal pressure stability.

[0004] The existing instrument air system is highly dependent on the operating conditions of the air compressor skid. If the air compressor skid malfunctions and shuts down, or if an emergency occurs such as system overpressure venting, it will directly cause insufficient instrument air supply pressure, preventing various pneumatic valves from opening and closing properly, creating a significant safety hazard. Furthermore, conventional instrument air systems only have basic filtration and drying equipment and lack online dew point monitoring. Instrument air easily carries liquid moisture, which can corrode internal components of pneumatic valves, damaging them and, in severe cases, causing valve jamming and malfunction, interfering with the safe operation of the entire system.

[0005] Existing publicly available technologies have already conducted research on instrument air pressure loss faults, and some of these technologies have proposed emergency protection solutions: For example, CN203892873U discloses a multi-line supply guarantee system for instrument air in an LNG plant, which uses a nitrogen system as a backup gas source for instrument air. It sets up regulating valve groups, shut-off valve groups and check valves to replenish nitrogen into the instrument air system in case of failure. However, it is designed for the continuous chemical production scenario of LNG plants, where the gas load of the unit is relatively stable. It does not consider the working conditions where two sets of process units are not put into operation at the same time and the gas consumption fluctuates greatly, nor does it design a branch line distribution gas supply scheme for the differentiated gas demand of different process units.

[0006] For example, CN205938508U discloses an automatic nitrogen replenishment instrument air control and regulation system that relies on DCS and automatic valve group to realize automatic nitrogen replenishment when the instrument air pressure decreases. A bypass valve is configured to deal with the failure of the automatic valve. However, this solution only solves the control logic of automatic nitrogen replenishment and lacks multi-point pressure monitoring, gas dew point quality monitoring, and does not design for pipeline condensate discharge and stable pressure distribution at multiple user ends. It cannot adapt to the working conditions of hydrogen production and hydrogen refueling integrated station equipment being dispersed and devices operating alternately.

[0007] For example, CN224086384U discloses an emergency pressurization system for sudden interruption of instrument air in a factory. This system is equipped with multiple air compressors as backups for each other, and two nitrogen sources, namely nitrogen generator and liquid nitrogen vaporization, are set up as emergency pressurization sources for the instrument air. The entire system has a large number of devices, including multiple air compressors, nitrogen generator adsorption tanks, liquid nitrogen storage tanks, and supporting heat exchange equipment. The system is complex and the equipment investment is high. For integrated hydrogen production and hydrogen refueling stations, this will significantly increase the project construction cost. Moreover, this solution does not distinguish the gas usage differences between the two process units and lacks interlocking control over the gas usage conflicts between purging gas and instrument backup gas. When nitrogen purging operations are carried out simultaneously in the station, there is a risk that the nitrogen source will be largely occupied, making it impossible to guarantee emergency pressurization of the instrument air.

[0008] For example, CN217736934U discloses an automatic interlocking control system for emergency safety instrument air. This system uses a booster to pressurize and store instrument air as an emergency safety gas source and relies on a high-pressure air storage tank to store emergency gas volume. This solution requires the configuration of a booster and a high-pressure, large-capacity storage tank, resulting in large equipment size and high investment costs. Furthermore, it still uses compressed air as the backup medium and does not reuse the nitrogen purging gas source already configured in the station, causing redundant construction of public works equipment. It is also impossible to use the existing nitrogen purging system in the station to achieve backup gas supply, which is not conducive to controlling project investment.

[0009] While the aforementioned publicly available technologies can address the emergency pressurization issue of instrument air depressurization to some extent, they are all developed for traditional chemical and LNG plant scenarios. The operating modes and gas consumption scale of hydrogen production and refueling units in integrated hydrogen production and refueling stations differ significantly from these scenarios. The hydrogen production and refueling units are not put into operation synchronously, resulting in large fluctuations in gas consumption. The station already has nitrogen purging cylinders for equipment pipeline replacement; adding independent standby air compressors, high-pressure air storage tanks, and nitrogen generators would result in redundant equipment investment. Existing technologies lack multi-point pressure monitoring and online dew point detection methods, and lack a systematic solution for the liquid carryover problem in instrument air. Furthermore, they do not consider the competition for gas sources between nitrogen purging operations and standby instrument air supply, lack corresponding interlocking logic, and do not design differentiated branch line gas distribution structures for hydrogen production skid-mounted equipment and decentralized refueling equipment. Therefore, it is difficult to simultaneously achieve reliable standby gas source switching and purging while controlling project investment. There are multiple requirements, including conflict control of gas supply to instruments, reasonable gas distribution to different process units, stable gas supply pressure, and gas quality control.

[0010] Therefore, there is an urgent need to develop a nitrogen gas suitable for the operating conditions of integrated hydrogen production and refueling stations. The instrument air integrated system reuses the existing nitrogen purging gas source in the station to solve practical engineering problems such as instrument air backup guarantee, conflict control between purging and instrument backup gas sources, stable pressure supply, gas quality control, and pipeline condensate protection. Summary of the Invention

[0011] The technical problem to be solved by this invention is to provide a nitrogen instrument air system and its gas supply control method for an integrated hydrogen production and refueling station, which ensures the instrument air supply pressure in emergency situations such as air compressor skid failure or system overpressure venting, and prevents pneumatic valves in the station from failing to open due to insufficient pressure; achieves stable gas supply pressure with less investment when there is a large difference between the gas used for hydrogen production and refueling; and reduces the adverse effects of liquid carried by the instrument air on the gas-using equipment.

[0012] To achieve the above technical objectives, the present invention adopts the following technical solution: This invention provides a nitrogen instrument air system and its gas supply control method for an integrated hydrogen production and refueling station. It reuses the existing nitrogen purging gas source in the station as a backup gas source for the instrument air, realizes automatic nitrogen replenishment under fault conditions, takes into account the differentiated gas supply needs of different hydrogen production and refueling units, suppresses pipeline condensation hazards, and controls the conflict between the purging and instrument backup gas sources. Under the premise of controlling project investment, it improves the gas supply reliability, pressure stability and gas quality safety of the instrument air system.

[0013] The nitrogen instrument air system for integrated hydrogen production and refueling stations includes a nitrogen supply unit, an instrument air supply unit, a backup connecting pipeline, a gas distribution unit, a pressure detection component, and a control unit.

[0014] The nitrogen supply unit includes a nitrogen source, a filter, a first pressure reducing valve, and a nitrogen-side shut-off valve. The nitrogen source output is connected to the nitrogen supply trunk line via the filter and the first pressure reducing valve in sequence. A nitrogen-side shut-off valve is installed on the nitrogen supply trunk line.

[0015] The instrument air supply unit includes an air compressor skid, an instrument air buffer tank, and an instrument air side shut-off valve. The outlet of the air compressor skid is connected to the inlet of the instrument air buffer tank via the instrument air side shut-off valve, and the outlet of the instrument air buffer tank is connected to the instrument air supply trunk line.

[0016] The backup connecting pipeline connects the nitrogen supply main line and the instrument air supply main line, and the backup connecting pipeline is equipped with a backup shut-off valve and a pressure regulating valve.

[0017] The gas supply and distribution unit is connected to the nitrogen gas supply trunk line and the instrument air gas supply trunk line, and includes a hydrogen production gas supply branch and a hydrogen refueling gas supply branch, which supply gas to the hydrogen production equipment and the hydrogen refueling equipment respectively.

[0018] The pressure detection assembly includes a nitrogen-side pressure detector, an instrument air pressure detector, and a combined pressure detector; the nitrogen-side pressure detector is located on the nitrogen supply main line, the instrument air pressure detector is located on the instrument air buffer tank, and the combined pressure detector is located on the gas supply pipeline after the two main lines merge.

[0019] The control unit is connected to the pressure detection component, the backup shut-off valve, and the pressure regulating valve. When the pressure detected by the instrument air pressure detector is lower than the first pressure threshold, the control unit interlocks and opens the backup shut-off valve. The nitrogen supply unit supplements the instrument air supply main line with gas through the backup connecting pipeline and adjusts the opening of the pressure regulating valve according to the detection value of the combined pressure detector.

[0020] Furthermore, the nitrogen source includes multiple sets of high-pressure nitrogen cylinders; a first safety valve is installed on the nitrogen supply line between the first pressure reducing valve and the nitrogen-side shut-off valve, and a nitrogen-side pressure detector is installed between the first pressure reducing valve and the first safety valve.

[0021] Furthermore, the volume of the instrument air buffer tank is configured to ensure a gas consumption of no less than 30 minutes for the entire station; a second safety valve is installed at the top of the instrument air buffer tank, and a drain valve and a condensate drain valve assembly are installed at the bottom; a buffer tank outlet dew point detector is installed on the outlet side of the instrument air buffer tank.

[0022] Furthermore, the air compressor skid outlet side is equipped with a compressor outlet dew point detector, which is interlocked with the instrument air-side shut-off valve; when the compressor outlet dew point detector detects a dew point exceeding the set range, the control unit interlocks to close the instrument air-side shut-off valve and interlocks to open the backup shut-off valve.

[0023] Furthermore, a check valve is installed on the backup connection line to prevent gas from flowing back from the instrument air supply line to the nitrogen supply line; the backup connection line is also equipped with a manual bypass connected in parallel with the pressure regulating valve, and the manual bypass is equipped with a manual shut-off valve and a self-regulating pressure regulating valve.

[0024] Furthermore, a gas source distributor is installed on the hydrogen supply branch line, which distributes the gas source to each hydrogen refueling equipment; each hydrogen refueling equipment inlet is sequentially equipped with a shut-off valve, a ball valve, and a second pressure reducing valve; and a drain valve is installed on the gas source distributor pipeline.

[0025] Furthermore, both the hydrogen production and refueling gas supply branches are led out from the top of the corresponding gas supply trunk line, with the high point of the gas supply branch sloping towards the gas supply trunk line, so that the condensate inside the branch flows back to the gas supply trunk line.

[0026] Furthermore, the hydrogen production equipment is a skid-mounted integrated unit, and the hydrogen production gas supply branch is a single gas supply trunk line that supplies gas to the hydrogen production equipment.

[0027] Furthermore, the control unit is also configured to: output a prompt when the nitrogen-side pressure detector detects a pressure lower than the second pressure threshold of 8 bar, confirming the valve position status of the first pressure reducing valve; and interlock and close the nitrogen-side shut-off valve when the nitrogen-side pressure detector detects a pressure lower than the first pressure threshold of 6 bar.

[0028] Furthermore, the pressure detection component also includes a purging pressure detector located on the nitrogen supply line; when the purging pressure detector detects a pressure lower than the second pressure threshold of 8 bar, and nitrogen purging is performed in the station, the control unit interlocks and adjusts the opening of the pressure regulating valve to reduce the supply of nitrogen to the instrument air supply line.

[0029] Furthermore, when the pressure detected by the merging pressure detector is lower than the preset merging pressure value, the control unit interlocks to increase the opening of the pressure regulating valve, thereby increasing the nitrogen supply volume and maintaining the gas supply pressure after merging at no lower than the preset merging pressure value.

[0030] This invention also discloses a nitrogen instrument air supply control method for an integrated hydrogen production and refueling station, based on the aforementioned nitrogen instrument air system for an integrated hydrogen production and refueling station, comprising: Step 1: Acquire instrument air pressure detection signal and merged pressure detection signal; the instrument air pressure detection signal is taken from the instrument air pressure detector on the instrument air buffer tank, and the merged pressure detection signal is taken from the merged pressure detector on the gas supply pipeline after the two main lines merge. Step 2: When the instrument air pressure detection signal is lower than the first pressure threshold, the interlock opens the backup shut-off valve, and nitrogen is supplied to the instrument air supply main line through the pressure regulating valve; the opening of the pressure regulating valve is adjusted according to the convergence pressure detection signal to maintain the supply pressure after convergence.

[0031] Furthermore, it also includes dew point interlock control steps: acquiring the compressor outlet dew point detection signal; when the compressor outlet dew point exceeds the set range, interlocking to close the instrument air-side shut-off valve and interlocking to open the backup shut-off valve.

[0032] Furthermore, it also includes nitrogen source pressure control steps: acquiring nitrogen-side pressure detection signals; outputting a prompt to confirm the valve position status of the first pressure reducing valve when the nitrogen-side pressure is lower than the second pressure threshold of 8 bar; and interlocking to close the nitrogen-side shut-off valve when the nitrogen-side pressure is lower than the first pressure threshold of 6 bar.

[0033] Furthermore, it also includes the following steps for controlling the conflict between purging and instrumentation gas supply: obtaining the purging pressure detection signal; when the purging pressure is lower than the second pressure threshold of 8 bar and nitrogen purging is being carried out in the station, interlocking the opening of the pressure regulating valve to reduce the nitrogen supply to the instrumentation air supply line.

[0034] Furthermore, when the convergence pressure detection signal is lower than the preset convergence pressure value, the opening of the pressure regulating valve is interlocked to maintain the gas supply pressure after convergence above the preset convergence pressure value; the preset convergence pressure value is the first pressure threshold of 6 bar.

[0035] The nitrogen instrument ventilation system and its gas supply control method for integrated hydrogen production and refueling stations provided by this invention have the following beneficial effects: 1. This invention reuses the nitrogen purging gas source in the station as a backup gas source for instrument air, eliminating the need for additional independent backup air compressors and high-pressure air storage tanks. It relies on the existing nitrogen supply unit in the station to achieve emergency gas replenishment, reducing the investment in public works equipment for integrated hydrogen production and refueling stations, and solving the safety hazards of insufficient instrument air pressure when the air compressor fails due to the lack of a backup gas source for the instrument air system.

[0036] 2. This invention sets up a multi-point pressure detection component to monitor the pressure on the nitrogen side, the instrument air buffer tank, and the combined pipeline, respectively, so as to realize full-process pressure monitoring of the nitrogen source side, the main instrument air side, and the mixed gas supply side. It can capture pressure anomalies at each node in real time, provide a complete data foundation for interlocking control, and solve the problem that single-point pressure monitoring cannot fully reflect the system operating status.

[0037] 3. This invention sets up a backup connecting pipeline with automatic interlocking logic of the control unit. When the instrument air pressure is lower than the first pressure threshold, the backup shut-off valve can be automatically opened to inject nitrogen to replenish the gas. The opening of the pressure regulating valve can be automatically adjusted according to the combined pressure to stabilize the gas supply pressure of the pipeline network and solve the problem that pneumatic valves cannot be opened or closed due to pressure loss in emergency situations such as air compressor failure and overpressure venting.

[0038] 4. This invention sets up a nitrogen gas source graded interlock control logic. When the nitrogen side pressure drops to the second pressure threshold, a valve position confirmation prompt is output. When the pressure drops to the first pressure threshold, the nitrogen gas supply is interlocked and cut off, realizing low pressure early warning and protection of the nitrogen gas source, avoiding ineffective gas replenishment when the nitrogen gas source pressure is too low, and protecting downstream gas-using equipment.

[0039] 5. This invention adds a purging pressure detector and a purging condition gas source conflict interlock. When nitrogen purging is carried out in the station and the nitrogen source pressure is insufficient, that is, when the pressure detected by the purging pressure detector is lower than the second pressure threshold, the nitrogen supply flow to the instrument air is automatically reduced to prioritize the gas supply for equipment pipeline purging and replacement, thus solving the technical problem of nitrogen purging operation and instrument air backup gas supply competing for gas source.

[0040] 6. The present invention installs a check valve on the backup connecting pipeline, which can prevent compressed air on the instrument air side from flowing back into the nitrogen supply trunk line, prevent compressed air from contaminating the purity of the nitrogen source, and avoid the process safety risks caused by cross-contamination of gas sources.

[0041] 7. The present invention sets up a parallel manual bypass in the backup connecting pipeline, and configures a manual shut-off valve and a self-regulating pressure regulating valve. When the automatic control circuit or pressure regulating valve fails, nitrogen emergency pressure regulation and gas replenishment can be achieved through the manual bypass, realizing automatic and manual dual redundancy and improving the system's fault tolerance under fault conditions.

[0042] 8. This invention sets up two levels of dew point detection and corresponding interlocking logic. Dew point detectors are respectively configured at the air compressor outlet and the instrument air buffer tank outlet. If the dew point exceeds the standard, the main air source of the air compressor can be disconnected through interlocking, and nitrogen backup air source can be automatically put into use, which solves the problem of gas quality control of excessive water content in instrument air and water vapor damage to pneumatic valves.

[0043] 9. The instrument air buffer tank of this invention is equipped with a reasonable volume, a safety valve, a drain valve and a condensate drain valve group. The gas storage capacity of the buffer tank can guarantee the gas supply of the entire station for no less than 30 minutes. The safety valve realizes overpressure relief. The drain and condensate drain valve group can periodically discharge the condensate in the tank, reduce the liquid water entering the downstream pipeline, and reduce the risk of valve corrosion and jamming.

[0044] 10. This invention adopts a gas supply distribution unit architecture adapted to hydrogen production and refueling conditions. It uses a single gas supply trunk line for skid-mounted integrated hydrogen production equipment, adapting to the characteristics of integrated skid-mounted hydrogen production equipment and simplifying the configuration of gas supply pipelines at the hydrogen production end.

[0045] 11. The present invention configures a gas source distributor for the hydrogen refueling gas supply branch, which is equipped with a front-end shut-off valve, a ball valve, and an air filter pressure reducing valve to centrally distribute the gas source to multiple dispersed hydrogen refueling devices. Each gas consumption point achieves impurity filtration and pressure regulation, ensuring stable gas supply and clean gas to each hydrogen refueling terminal device, and solving the problems of large pressure fluctuations at the terminal and impurities damaging valve internals caused by the dispersion of hydrogen refueling devices.

[0046] 12. The gas supply branch of this invention is led out from the top of the gas supply main line. The high point of the branch pipeline slopes towards the main line. The condensate generated inside the branch pipeline flows back to the gas supply main line by relying on the slope, which reduces the accumulation of condensate in the gas supply branch pipeline from the source and prevents the condensate accumulated in the branch pipeline from entering the gas valve with the gas, further reducing the probability of valve corrosion and jamming failure.

[0047] 13. The overall system of this invention is adaptable to the working conditions where hydrogen production and hydrogen refueling units are not put into operation at the same time and the gas consumption varies greatly. By combining the gas supply distribution of the branch-main line with the pressure closed-loop regulation of the control unit, the gas supply pressure of each gas terminal is kept stable under the condition that the two sets of units are started and stopped alternately and the gas load fluctuates greatly. This solves the problem that the traditional solution of directly applying the LNG plant system cannot adapt to the load fluctuation of the integrated station.

[0048] 14. The present invention is equipped with a complete gas supply control method, which relies on multi-point signal acquisition to complete interlock judgment, valve switching and opening adjustment, and automatic fault response. At the same time, it is compatible with manual intervention operation mode, reducing the difficulty of operation for on-site personnel and meeting the safety production management and control needs of hydrogen energy stations. Attached Figure Description

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the nitrogen instrument ventilation system for the integrated hydrogen production and refueling station of the present invention; Figure 2 This is a schematic diagram of the gas supply distribution of the branch line of the gas supply distribution unit of the present invention; In the diagram: 1. Nitrogen cylinder assembly; 2. Filter; 3. First pressure reducing valve; 4. First safety valve; 5. Nitrogen side shut-off valve; 6. Nitrogen side pressure detector; 7. Air compressor skid; 8. Compressor outlet dew point detector; 9. Instrument air buffer tank; 10. Instrument air side shut-off valve; 11. Second safety valve; 12. Drain valve; 13. Drain valve assembly; 14. Buffer tank outlet dew point detector; 15. Backup shut-off valve; 16. Pressure regulating valve; 17. Check valve; 18. Manual bypass; 19. Gas source distributor; 20. Shut-off valve; 21. Ball valve; 22. Second pressure reducing valve; 23. Hydrogen production supply branch; 24. Hydrogen refueling supply branch; 25. Connecting hose; 26. Purge pressure detector; 27. Combined pressure detector; 28. Instrument air detector; 29. ​​Manual shut-off valve; 30. Self-regulating pressure regulating valve. Detailed Implementation

[0050] The technical solutions of the present invention will be further described below with reference to the embodiments and accompanying drawings: Example 1 like Figure 1 As shown, this embodiment provides a nitrogen instrument air system for an integrated hydrogen production and refueling station, including a nitrogen supply unit, an instrument air supply unit, a backup connecting pipeline, a gas distribution unit, a pressure detection component, and a control unit.

[0051] The nitrogen supply unit includes a nitrogen cylinder group 1, a filter 2, a first pressure reducing valve 3, a first safety valve 4, and a nitrogen-side shut-off valve 5. The nitrogen source typically uses multiple high-pressure nitrogen cylinder groups 1 (approximately 15 MPa) as a nitrogen purging and backup supply source. The cylinder group is connected to the valve group via connecting hoses 25. When the nitrogen supply is insufficient, nitrogen cylinder group 1 can be directly replaced. The output end of nitrogen cylinder group 1 is connected to filter 2 to filter out impurities from the gas source. A first pressure reducing valve 3 is installed after filter 2 to reduce the nitrogen pressure to 8–10 bar. A nitrogen-side pressure detector 6 (PT1) is installed after the first pressure reducing valve 3, and a first safety valve 4 is installed before the nitrogen-side shut-off valve 5. The first safety valve 4 is an overpressure relief safety valve to ensure the safe operation of the pipeline. Nitrogen is connected to the nitrogen supply main line after passing through the nitrogen-side shut-off valve 5.

[0052] The instrument air supply unit includes an air compressor skid 7, an instrument air side shut-off valve 10, and an instrument air buffer tank 9. The air compressor skid 7 can be a skid-mounted device that integrates filtration, oil removal, and drying. Its outlet is equipped with a compressor outlet dew point detector AT1 (8), and an instrument air side shut-off valve 10 is installed after it. The instrument air side shut-off valve 10 is connected to the inlet of the instrument air buffer tank 9. The volume of the instrument air buffer tank 9 is set to ensure the gas consumption of the entire station for no less than 30 minutes. An instrument air pressure detector 28 (PT3) and a second safety valve 11 are installed on the top of the tank, and a drain valve 12 and a condensate drain valve group 13 are installed at the bottom of the tank. An outlet dew point detector AT2 (14) is installed after the instrument air buffer tank 9 to monitor whether the gas quality at the outlet of the buffer tank meets the requirements. The outlet of the instrument air buffer tank 9 is connected to the instrument air supply trunk line.

[0053] A backup connecting pipeline is installed between the nitrogen supply main line and the instrument air supply main line, and is equipped with a backup shut-off valve 15, a pressure regulating valve 16, and a check valve 17. The pressure regulating valve 16 is used to reduce the nitrogen pressure from 8 to 10 bar to the instrument air supply pressure of 5 to 7 bar. To prevent instrument air from backflowing into the nitrogen system and contaminating the nitrogen purity, a check valve 17 is installed before the nitrogen enters the instrument air pipeline. To prevent control valve failure, a manual bypass 18 is connected in parallel with the pressure regulating valve 16. The manual bypass 18 is equipped with a manual shut-off valve 29 and a self-operated pressure regulating valve 30. This self-operated pressure regulating valve 30 does not require power and can achieve the pressure reduction effect by its own structure. It can be manually operated to maintain the gas supply when the automatic control fails.

[0054] The gas distribution unit is connected to the nitrogen supply trunk line and the instrument air supply trunk line, and includes a hydrogen production supply branch 23 and a hydrogen refueling supply branch 24. For example... Figure 2 As shown, hydrogen production equipment typically uses skid-mounted integrated units, with its own internal gas supply distribution. Therefore, hydrogen production gas supply branch 23 only needs to provide one main gas supply line. The hydrogen refueling equipment is more dispersed, so a gas source distributor 19 is used to integrate the gas supply distribution of the hydrogen refueling main line. The gas source distributor 19 has a certain capacity and can stabilize the gas source pressure for multiple users. In the hydrogen refueling gas supply branch 24, each hydrogen refueling device is equipped with a shut-off valve 20 to regulate the gas flow and pressure, a ball valve 21 as a manual gas supply switch for a single user, and a second pressure reducing valve 22. The second pressure reducing valve 22 is an air filter pressure reducing valve, used to ensure that the gas is free of impurities and does not damage the internal components of the user's valves. A drain valve 12 is also installed on the distribution pipeline of the gas source distributor 19. The branch pipe for user-end gas supply is led out from the top of the main gas supply line, sloping towards the main line at its highest point, draining the condensate on the branch pipe to the main line, thereby effectively preventing condensation from appearing in the branch pipe.

[0055] The pressure detection assembly includes a nitrogen-side pressure detector 6 (PT1), a purge pressure detector 26 (PT2), an instrument air pressure detector 28 (PT3), and a combined pressure detector 27 (PT4). Specifically, the nitrogen-side pressure detector 6 (PT1) is located between the first pressure reducing valve 3 and the first safety valve 4; the purge pressure detector 26 (PT2) is located on the nitrogen supply main line; the instrument air pressure detector 28 (PT3) is located on the top of the instrument air buffer tank 9; and the combined pressure detector 27 (PT4) is located on the supply pipeline where the nitrogen supply main line and the instrument air supply main line merge.

[0056] The control unit is connected to the pressure detection assembly, nitrogen-side shut-off valve 5, instrument air-side shut-off valve 10, standby shut-off valve 15, and pressure regulating valve 16 via signal connection, and is used to implement the following interlock control based on the detection signals from each detector: When the pressure detected by the nitrogen-side pressure detector 6 (PT1) on the nitrogen supply main line is less than the second pressure threshold of 8 bar, an output prompt is given to confirm the valve position status of the first pressure reducing valve 3. When the pressure detected by the nitrogen-side pressure detector 6 (PT1) is less than or equal to the first pressure threshold of 6 bar, the nitrogen-side shut-off valve 5 on the nitrogen supply pipeline is interlocked and shut off. When the pressure detected by the purging pressure detector 26 (PT2) is less than the second pressure threshold of 8 bar, it is first manually confirmed whether nitrogen purging is in progress at the station. If purging is in progress, the opening of the pressure regulating valve 16 is interlocked to reduce the amount of nitrogen supplied to the instrument air source. If purging is not in progress, the interlock is not triggered. When the compressor outlet dew point detector 8 (AT1) detects an abnormal dew point, it interlocks and closes the instrument air side shut-off valve 10, while simultaneously interlocking and opening the backup shut-off valve 15 on the nitrogen supply bypass. The buffer tank outlet dew point detector 14 (AT2) serves as an auxiliary criterion; when it alarms, manual verification is required to check if the drain valve assembly 13 at the bottom of the buffer tank is blocked. When the pressure detected by the instrument air pressure detector 28 (PT3) is less than the first pressure threshold of 6 bar, it interlocks and opens the backup shut-off valve 15 on the nitrogen supply bypass, using nitrogen as a supplement to the instrument air supply. When the pressure detected by the merging pressure detector 27 (PT4) is lower than the preset merging pressure value, it interlocks and controls the opening of the pressure regulating valve 16 to ensure that the merging supply pressure remains above the first pressure threshold of 6 bar.

[0057] The control unit can automatically control each shut-off valve and pressure regulating valve based on the above interlocking control logic, and can be linked with the station's audible and visual alarm device to issue an alarm signal when the pressure or dew point is abnormal, prompting the operators to handle it in time and ensuring the safe operation of the hydrogen production and refueling station.

[0058] Example 2 In another preferred embodiment, based on Embodiment 1, this embodiment provides a nitrogen instrument air supply system for an integrated hydrogen production and refueling station. The structure is basically the same as that of Embodiment 1, except that: in this embodiment, the high-pressure nitrogen cylinder group 1 is discarded as the nitrogen source, and a liquid nitrogen vaporization supply unit is used as the nitrogen source. The liquid nitrogen storage tank is equipped with a water bath heater and a liquid nitrogen vaporizer. After vaporization and heating, the liquid nitrogen outputs 8~10 bar nitrogen. The vaporized nitrogen is sequentially connected to the filter 2 and the first pressure reducing valve 3 before entering the nitrogen supply trunk line. Multiple sets of replaceable high-pressure nitrogen cylinder groups are no longer configured.

[0059] The remaining equipment configuration, instrument point layout, and pipeline structure are consistent with those in Example 1. This example is suitable for medium to large-scale integrated hydrogen production and refueling stations, where the total nitrogen consumption is high and the workload of frequently replacing nitrogen cylinders is high. The liquid nitrogen vaporization supply unit can achieve continuous nitrogen output for a long time, reducing the frequency of cylinder replacement.

[0060] The interlocking control logic in this embodiment is exactly the same as that in Embodiment 1. The control unit still collects signals from the nitrogen-side pressure detector 6, the purging pressure detector 26, the instrument air pressure detector 28, the combined pressure detector 27, and the two-stage dew point detectors to complete pressure interlocking, dew point interlocking, and purging-instrument gas conflict interlocking. Similarly, a check valve 17 and a manual bypass 18 with a self-regulating pressure regulating valve 30 are set to realize backflow prevention and manual redundant gas supply under automatic failure.

[0061] Example 3 In another preferred embodiment, based on Embodiment 1, this embodiment provides a nitrogen instrument air supply system for an integrated hydrogen production and refueling station. Based on the main structure of Embodiment 1, the difference is that the control unit has both local touch screen operation and remote DCS communication interface, which can complete parameter setting, interlock switching, and alarm viewing at the station site, and can also complete monitoring and operation remotely in the central control room; the gas source distributor 19 is equipped with a dual-mode drain valve 12 for manual drain and timed automatic drain; at the same time, the system adds an event recording function, and all interlock actions, valve status changes, and alarm information can be stored and archived.

[0062] The remaining hardware piping and testing instrument configurations are consistent with those in Example 1. This example is more suitable for unattended, remotely centralized hydrogen production and refueling stations. When the compressor outlet dew point detector 8 alarms, in addition to executing the interlock valve cutting action, the control unit simultaneously pushes a fault message to the central control room; when the nitrogen side pressure reaches the second pressure threshold and the first pressure threshold, in addition to on-site audible and visual alarms, remote alarm information is simultaneously uploaded, facilitating maintenance personnel to remotely monitor the equipment status.

[0063] Example 4 In another preferred embodiment, based on Embodiment 1, this embodiment provides a nitrogen instrument air supply control method for an integrated hydrogen production and refueling station, implemented based on the nitrogen instrument air system for the integrated hydrogen production and refueling station described in Embodiment 1, including the following steps: Step 1: The system is in normal operating condition. The air compressor skid 7 is working normally. The instrument air supply unit supplies instrument air to the hydrogen production supply branch 23 and the hydrogen refueling supply branch 24. The control unit collects the detection signals of the nitrogen side pressure detector 6, the purging pressure detector 26, the instrument air pressure detector 28, the combined pressure detector 27, the compressor outlet dew point detector 8, and the buffer tank outlet dew point detector 14 in real time.

[0064] Step 2: When the pressure detected by the instrument air pressure detector 28 is lower than the first pressure threshold, the nitrogen emergency gas replenishment process is triggered; the control unit interlocks and opens the backup shut-off valve 15 on the backup connecting pipeline, and the nitrogen in the nitrogen supply trunk line is replenished into the instrument air supply trunk line after being depressurized by the pressure regulating valve 16; the opening of the pressure regulating valve 16 is adjusted in a closed loop according to the real-time pressure signal of the merging pressure detector 27 to maintain the network pressure after merging not lower than the first pressure threshold.

[0065] Step 3: Nitrogen source pressure monitoring: When the nitrogen-side pressure detector 6 detects that the pressure has dropped to the second pressure threshold, the control unit triggers an audible and visual alarm and outputs a prompt message to remind maintenance personnel to check the valve position status of the first pressure reducing valve 3; if the pressure continues to drop to the first pressure threshold, the nitrogen-side shut-off valve 5 is interlocked and closed to stop nitrogen supply and output a fault alarm.

[0066] Step 4: Conflict control of purging gas: When the pressure detected by the purging pressure detector 26 is lower than the second pressure threshold, the maintenance personnel confirm on-site that nitrogen purging and replacement work is being carried out in the station. The control unit interlocks to close the opening of the pressure regulating valve 16, reducing the flow of nitrogen to the instrument air side and prioritizing the purging and replacement gas supply. If there is no purging work on site, the interlock will not activate.

[0067] Step 5: Fault Recovery: After the fault of air compressor skid 7 is resolved and the pressure of instrument air buffer tank 9 returns to the normal operating range, manually confirm that the operating conditions are stable, close the standby shut-off valve 15, and the system switches back to the main air supply mode of air compressor skid.

[0068] Example 5 In another preferred embodiment, based on embodiments 1 and 4, this embodiment provides a nitrogen instrument air supply control method for an integrated hydrogen production and refueling station. This method is implemented based on the nitrogen instrument air system for the integrated hydrogen production and refueling station described in embodiment 1. It is the control process for abnormal instrument air quality conditions under the present invention, and the steps are as follows: Step 1: The system is running normally. The air compressor skid 7 outputs instrument air. The control unit continuously collects the dew point signals from the compressor outlet dew point detector AT1 (8), the buffer tank outlet dew point detector AT2 (14), and various pressure detection signals.

[0069] Step 2: The dew point detector 8 at the compressor outlet detects that the dew point exceeds the preset qualified threshold, and determines that the water content of the instrument air source exceeds the standard; the control unit interlocks and closes the instrument air side shut-off valve 10, cutting off the air supply path from the air compressor skid 7 to the instrument air buffer tank 9.

[0070] Step 3: The interlock opens the standby shut-off valve 15, the nitrogen supply unit is put into standby gas supply, and the nitrogen is replenished into the instrument air supply main line after being depressurized through the standby connecting pipeline; the control unit reads the signal of the combined pressure detector 27 and dynamically adjusts the opening of the pressure regulating valve 16 to ensure the stability of the gas supply pressure of downstream hydrogen production and hydrogen refueling equipment.

[0071] Step 4: If the dew point detector 14 at the outlet of the buffer tank alarms, the control unit outputs a prompt to remind the operator to check on-site whether the drain valve group 13 at the bottom of the instrument air buffer tank 9 is blocked and to complete the sewage drainage operation in a timely manner.

[0072] Step 5: Maintenance personnel inspect and repair the filter and drying equipment of the air compressor skid 7. After the repair is completed, they confirm that the reading of the compressor outlet dew point detector 8 has returned to the qualified range. The instrument air-side shut-off valve 10 is activated, the standby shut-off valve 15 is closed, and the system is restored to the main air supply mode of the air compressor skid.

[0073] Step 6: During operation, if the nitrogen gas source low pressure condition is triggered synchronously, the nitrogen side low pressure early warning and cut-off logic will be executed synchronously, and alarm information will be output.

[0074] Example 6 In another preferred embodiment, based on embodiments 1 and 4, this embodiment provides a nitrogen instrument air supply control method for an integrated hydrogen production and refueling station. This method is implemented based on the nitrogen instrument air system for the integrated hydrogen production and refueling station described in embodiment 1. It is a control process for manual bypass emergency air supply in case of automatic control loop failure, and the steps are as follows: Step 1: The instrument air pressure detector 28 detects that the pressure is lower than the first pressure threshold, but the standby shut-off valve 15 and the pressure regulating valve 16 have no valve action feedback signal. The control unit determines that the automatic air replenishment circuit is faulty and outputs an audible and visual alarm and a remote alarm.

[0075] Step 2: When maintenance personnel arrive at the site, they first manually start the backup shut-off valve 15 on the backup connecting pipeline to connect the nitrogen supply channel; open the manual shut-off valve 29 on the manual bypass 18, and use the self-regulating pressure regulating valve 30 to adjust the nitrogen pressure to the instrument air supply range of 5~7 bar. Nitrogen is then supplied to the instrument air supply line through the manual bypass 18 to ensure the power source for all pneumatic valves in the station.

[0076] Step 3: The maintenance personnel observe the local pressure gauge of the pipeline after the connection and fine-tune the self-regulating pressure regulating valve 30 to maintain the pipeline pressure above the first pressure threshold. When nitrogen purging is carried out on site at the same time, the manual shut-off valve 29 is manually closed to prioritize the gas demand for purging and replacement.

[0077] Step 4: Complete the maintenance and replacement of the standby shut-off valve 15 and pressure regulating valve 16, and confirm that the automatic control circuit is intact; close the manual shut-off valve 29 of the manual bypass 18, restore the automatic interlock control of the standby shut-off valve 15 and pressure regulating valve 16, and switch the system back to the automatic interlock gas replenishment working mode.

[0078] Step 5: The control unit records all alarm information, interlock status, and manual operation events for this operation, and completes data archiving and storage.

[0079] In the preferred embodiment, the nitrogen source 1 includes multiple sets of high-pressure nitrogen cylinders. A first safety valve 4 is installed on the nitrogen supply line between the first pressure reducing valve 3 and the nitrogen-side shut-off valve 5. A nitrogen-side pressure detector 6 is installed between the first pressure reducing valve 3 and the first safety valve 4. This configuration allows for direct replacement of the nitrogen cylinder sets to replenish the gas source when gas supply is insufficient. Impurities are filtered out from the gas source, and the nitrogen pressure is stably reduced to 8-10 bar. The first safety valve 4 can monitor the pipeline pressure in real time and release pressure immediately when there is a risk of overpressure, preventing pipeline damage due to overpressure. The nitrogen-side pressure detector 6 can collect pressure data of this section of the pipeline in real time, providing accurate reference data for subsequent system interlocking actions, and comprehensively ensuring the operational safety of this section of the nitrogen pipeline.

[0080] In the preferred embodiment, the volume of the instrument air buffer tank 9 is set to ensure a gas consumption of no less than 30 minutes for the entire station; the top of the instrument air buffer tank 9 is equipped with a second safety valve 11, and the bottom is equipped with a drain valve 12 and a condensate drain valve group 13; the outlet side of the instrument air buffer tank 9 is equipped with a buffer tank outlet dew point detector 14, which is used to detect the gas quality at the outlet of the instrument air buffer tank 9; the above settings can maintain the instrument air supply for the entire station for 30 minutes by relying on the gas stored in the tank when the air compressor skid experiences a temporary failure, reserving sufficient buffer time for troubleshooting. The second safety valve 11 can prevent the internal pressure of the buffer tank 9 from exceeding the limit and causing safety hazards. The drain valve 12 and the condensate drain valve group 13 at the bottom of the tank can promptly discharge the condensate and impurities deposited in the tank. The buffer tank outlet dew point detector 14 can verify the gas quality flowing out of the buffer tank 9 in real time. Once an abnormality occurs, it can be used as an auxiliary judgment basis to remind maintenance personnel to promptly check whether the condensate drain valve group 13 is blocked, so as to prevent gas with liquid and impurities from flowing into the subsequent pipeline and damaging the gas-using equipment.

[0081] In a preferred embodiment, the air compressor skid 7 is equipped with a compressor outlet dew point detector 8 at its outlet side, which is interlocked with the instrument air-side shut-off valve 10. The control unit is also used to interlock and close the instrument air-side shut-off valve 10 and interlock and open the backup shut-off valve 15 when the dew point value detected by the compressor outlet dew point detector 8 exceeds the set range. The above settings can cut off the delivery path of the abnormal gas source as soon as possible when the moisture content of the gas output by the air compressor skid 7 exceeds the standard, and automatically switch to the backup nitrogen gas supply path to prevent high humidity gas from entering the subsequent pipeline and causing equipment corrosion and valve jamming. The gas source switching can be completed quickly without manual intervention, ensuring that the downstream gas-using equipment always receives instrument air that meets the quality requirements.

[0082] In the preferred embodiment, a check valve 17 is provided on the backup connection pipeline to prevent airflow from flowing in the reverse direction from the instrument air supply line to the nitrogen supply line. The backup connection pipeline is also provided with a manual bypass 18 connected in parallel with the pressure regulating valve 16. The manual bypass 18 is equipped with a manual shut-off valve 29 and a self-regulating pressure regulating valve 30. The above settings can completely prevent instrument air from backflowing into the nitrogen system and contaminating the purity of the nitrogen, ensuring that the nitrogen source always remains clean and compliant. When the automatically controlled pressure regulating valve 16 experiences power failure, valve jamming, or other malfunctions, it can be switched to the manual bypass 18. The self-regulating pressure regulating valve 30 can achieve self-pressure reduction without additional power supply, maintaining the normal operation of the nitrogen backup supply path and preventing the entire backup supply system from failing due to a single component failure.

[0083] In a preferred embodiment, the hydrogen supply branch 24 is equipped with a gas source distributor 19, which is used to collect the gas supply and distribute it to multiple hydrogen refueling devices. Each hydrogen refueling device is equipped with a shut-off valve 20, a ball valve 21, and a second pressure reducing valve 22 before its gas inlet. A drain valve 12 is provided on the distribution pipeline of the gas source distributor. The above configuration can integrate the gas sources of the dispersed hydrogen refueling devices, and the gas supply pressure fluctuation can be buffered by the storage capacity of the gas source distributor 19 to provide a stable gas supply for multiple dispersed hydrogen refueling devices. The shut-off valve 20 can adjust the gas flow rate and pressure of each branch slightly. The ball valve 21 can be used as a manual on / off switch for a single device, which can be used to cut off the gas supply when a single device is under maintenance without affecting the operation of other devices. The second pressure reducing valve 22 can further filter residual impurities in the gas, stabilize the gas supply pressure within the equipment's suitable range, and prevent impurities from damaging the internal components of the gas valves. The drain valve 12 on the distribution pipeline can periodically discharge the condensate impurities deposited in the pipeline to maintain the gas quality of the hydrogen refueling branch.

[0084] In the preferred embodiment, the hydrogen production and gas supply branch 23 and the hydrogen refueling and gas supply branch 24 are respectively led out from the top of the corresponding gas supply trunk line, and the high point of each gas supply branch slopes towards the corresponding gas supply trunk line, so that the condensate in the gas supply branch line flows back to the gas supply trunk line. The above arrangement can avoid the accumulation and retention of condensate in the branch pipe section, reduce the risk of liquid entering the terminal gas valve from the instrument air, prevent droplet corrosion and damage to the gas valve components, and ensure the long-term stable operation of the downstream gas-using equipment.

[0085] In the preferred embodiment, the hydrogen production equipment is a skid-mounted integrated device, and the hydrogen production gas supply branch 23 is a single gas supply trunk line supplying gas to the hydrogen production equipment. With the above configuration, there is no need to set up complex gas source distribution components on the hydrogen production side. The gas supply distribution can be completed by relying on the gas source distribution structure built into the skid-mounted equipment, which simplifies the gas supply pipeline layout on the hydrogen production side, reduces unnecessary equipment investment, and adapts to the overall layout requirements of the hydrogen production skid-mounted equipment, ensuring the stability of the gas supply of the hydrogen production system.

[0086] In a preferred embodiment, the control unit is further configured to: output a prompt to confirm the valve position status of the first pressure reducing valve 3 when the detected pressure of the nitrogen-side pressure detector 6 is lower than the second pressure threshold of 8 bar; and interlock to close the nitrogen-side shut-off valve 5 when the detected pressure of the nitrogen-side pressure detector 6 is lower than the first pressure threshold of 6 bar. These settings allow for advance maintenance reminders when the nitrogen supply pressure shows a downward trend, enabling staff to check the working status of the first pressure reducing valve 3 immediately, preventing a continuous drop in nitrogen pressure from affecting normal gas supply. When the pressure falls below the safety threshold, the nitrogen supply pipeline is promptly shut off to prevent low-pressure abnormal gas from flowing into downstream gas branches and causing supply failures, thus ensuring the safe operation of the entire nitrogen system.

[0087] In a preferred embodiment, the pressure detection component further includes a purging pressure detector 26 located on the nitrogen supply line; the control unit is also used to: interlock and adjust the opening of the pressure regulating valve 16 when the detection pressure of the purging pressure detector 26 is lower than the second pressure threshold of 8 bar and the hydrogen production and refueling station is carrying out nitrogen purging operations, so as to reduce the supply of nitrogen to the instrument air supply line; the above settings can prioritize the supply of gas source for on-site nitrogen purging operations, avoid the problem of insufficient pressure and incomplete purging due to the diversion of gas source, balance the gas demand of daily purging operations and instrument air backup gas supply, adapt to two different gas usage scenarios without the need for additional large-capacity nitrogen gas source, and reduce the overall investment cost of the system.

[0088] In a preferred embodiment, the control unit is further configured to: when the detection pressure of the merging pressure detector 27 is lower than the preset merging pressure value, interlock to increase the opening of the pressure regulating valve 16 to increase the supplementary nitrogen supply, so that the supply pressure after merging is maintained above the preset merging pressure value; the above settings can dynamically adjust the supplementary nitrogen backup gas source, compensate for pressure fluctuations in the instrument air system in real time, and quickly replenish the system pressure in emergency situations such as air compressor skid failure or system overpressure venting, avoiding insufficient instrument air pressure causing the pneumatic valves in the station to fail to open normally, and eliminating the corresponding operational safety hazards.

[0089] In the preferred embodiment, when the instrument air pressure detection signal is lower than the first pressure threshold, the backup shut-off valve 15 is interlocked and opened, allowing nitrogen to be supplied to the instrument air supply main line via the pressure regulating valve 16. The above settings can automatically trigger the backup nitrogen supply circuit when the pressure of the instrument air system drops to the critical value, quickly replenishing the system air volume without manual intervention. It fills the air supply gap caused by air compressor failure by relying on the pre-configured backup air supply path, solving the problem of pressure instability in traditional instrument air systems when there is no backup air source or when a failure occurs.

[0090] In the preferred embodiment, the nitrogen instrument air supply control method for the integrated hydrogen production and refueling station further includes: acquiring the compressor outlet dew point detection signal, which comes from the compressor outlet dew point detector 8 located on the outlet side of the air compressor skid 7; when the compressor outlet dew point detection signal exceeds the set range, the instrument air-side shut-off valve 10 located between the air compressor skid 7 and the instrument air buffer tank 9 is interlocked closed, and the backup shut-off valve 15 is interlocked open; the above settings can detect the problem of excessive moisture in the air compressor outlet gas in the first instance, quickly cut off the delivery path of the abnormal gas source, and simultaneously and automatically switch to a qualified nitrogen gas source for gas supply, blocking the flow of high-humidity gas into the subsequent pipeline from the source, avoiding corrosion damage to various gas valves and instrument components in the system by liquid gas, and extending the overall service life of the equipment.

[0091] In the preferred embodiment, the nitrogen instrument air supply control method for the integrated hydrogen production and refueling station further includes: acquiring a nitrogen-side pressure detection signal, which comes from a nitrogen-side pressure detector 6 located on the nitrogen supply trunk line downstream of the first pressure reducing valve 3; when the nitrogen-side pressure detection signal is lower than the second pressure threshold of 8 bar, an output prompt is given to confirm the valve position status of the first pressure reducing valve 3; when the nitrogen-side pressure detection signal is lower than the first pressure threshold of 6 bar, the nitrogen-side shut-off valve 5 located on the nitrogen supply trunk line is interlocked and closed; the above settings can establish a tiered nitrogen pressure early warning and protection mechanism, guiding maintenance personnel to intervene and check the working status of the first pressure reducing valve 3 in the early stage of pressure abnormality, eliminating potential fault hazards in advance, and cutting off the gas supply circuit in time when the pressure drops to the dangerous range to avoid low-pressure abnormal gas entering the downstream system and causing gas supply disorder.

[0092] In the preferred embodiment, the nitrogen instrument air supply control method for the integrated hydrogen production and refueling station further includes: acquiring a purging pressure detection signal, which comes from a purging pressure detector 26 located on the nitrogen supply trunk line; when the purging pressure detection signal is lower than the second pressure threshold of 8 bar and the integrated hydrogen production and refueling station is performing nitrogen purging operations, interlocking and adjusting the opening of the pressure regulating valve 16 to reduce the supply of nitrogen to the instrument air supply trunk line; the above settings can dynamically adjust the distribution ratio of nitrogen gas source, prioritize ensuring the gas demand of the purging operation when performing nitrogen purging operations on site, avoid insufficient pressure and incomplete purging due to gas source diversion during purging operations, adapt to the gas demand differences of two different gas demand scenarios in the hydrogen production and refueling station, and can take into account the gas demand of both types without additional expansion of the nitrogen gas source.

[0093] In the preferred embodiment, when the merged pressure detection signal is lower than the preset merged pressure value, the opening of the pressure regulating valve 16 is interlocked to increase, so that the gas supply pressure after merging is maintained above the preset merged pressure value; the preset merged pressure value is the first pressure threshold of 6 bar; the above settings can ensure that the gas supply pressure after the instrument air and nitrogen merge is always stable above 6 bar, fully meeting the driving pressure requirements of all pneumatic valves in the station, avoiding insufficient pressure at the end gas consumption points, stabilizing the gas supply pressure of the entire system, ensuring that both the hydrogen production and hydrogen refueling systems can obtain a stable gas supply that meets the operating conditions, and improving the operational stability of the entire station area.

[0094] In summary, the nitrogen instrument air system and its gas supply control method for integrated hydrogen production and refueling stations proposed in this invention rely on the existing nitrogen cylinder group 1 in the station to construct a backup gas supply path for the instrument air. With the cooperation of multi-point pressure detection, dew point monitoring and multi-dimensional interlocking control logic, it overcomes the engineering problems of traditional integrated hydrogen production and refueling stations, such as the lack of a reliable backup gas source for the instrument air, competition between purging and backup gas supply for the instrument air, lack of gas quality control for the instrument air, and poor adaptability of gas supply distribution to different process units. It achieves automatic emergency nitrogen replenishment in the event of an instrument air failure, and takes into account the comprehensive operational effect of gas quality control, gas source conflict protection, and stable end-point gas supply.

[0095] This invention reuses the existing nitrogen cylinder group 1 at the station as a backup gas source, eliminating the need for additional large backup air compressors and high-pressure air storage tanks. While meeting the emergency gas supply safety requirements, it controls the construction investment of the public works system and is adapted to the project construction characteristics of integrated hydrogen production and refueling stations.

[0096] This invention sets up multiple pressure detection points, including a nitrogen-side pressure detector 6, an instrument air pressure detector 28, a purging pressure detector 26, and a convergence pressure detector 27, and is equipped with a graded pressure interlocking mechanism. This can not only complete the low-pressure early warning and cut-off protection of nitrogen source, but also identify the nitrogen purging operation conditions. When the nitrogen source is tight, it automatically reduces the amount of gas supplied to the instrument air, prioritizes the process requirements of equipment pipeline purging and replacement, and avoids the problem of gas source competition between two gas usage scenarios.

[0097] This invention employs a two-stage dew point detection system: a compressor outlet dew point detector 8 at the air compressor skid 7 outlet and a buffer tank outlet dew point detector 14 at the instrument air buffer tank 9 outlet. This system enables full-process monitoring of the instrument air moisture content. In case of abnormal dew point, it can automatically disconnect the instrument air-side shut-off valve 10 and switch to nitrogen to complete the gas supply. Simultaneously, the second safety valve 11, drain valve 12, and condensate drain valve group 13 complete the drainage of the instrument air buffer tank 9. The hydrogen production gas supply branch 23 and the hydrogen refueling gas supply branch 24 adopt a top-outlet, sloped condensate drainage pipeline structure design, reducing condensate accumulation from both equipment and pipeline levels. This reduces the risk of moisture corrosion and jamming of pneumatic valves, ensuring the gas quality of the instrument air supply.

[0098] This invention addresses the different operating conditions of integrated hydrogen production skid-mounted equipment and dispersed hydrogen refueling equipment. It sets up hydrogen production gas supply branch 23 and hydrogen refueling gas supply branch 24 respectively, and configures a gas source distributor 19 on the hydrogen refueling side. Each gas consumption point is equipped with a shut-off valve 20, a ball valve 21, and a second pressure reducing valve 22 to achieve pressure regulation and filtration. This invention is suitable for actual operating conditions where the two sets of equipment are not put into operation at the same time and the gas consumption fluctuates greatly, ensuring stable gas supply pressure at each gas consumption terminal.

[0099] This invention simultaneously configures a backup shut-off valve 15, an automatic valve group of a pressure regulating valve 16, and a manual bypass 18 with a self-regulating pressure regulating valve 30 on the backup connecting pipeline, and sets up a check valve 17 to prevent cross-contamination of gas sources; the control unit integrates pressure interlock, dew point interlock, and gas source conflict interlock, and supports local and remote monitoring, event logging and archiving, taking into account both automatic interlock operation and manual emergency response capabilities, improving the system's fault tolerance capability, and meeting the actual use requirements of continuous and safe production operation of integrated hydrogen production and refueling stations.

Claims

1. A nitrogen instrument ventilation system for an integrated hydrogen production and refueling station, characterized in that, The system includes a nitrogen supply unit, an instrument air supply unit, a backup connecting pipeline, a gas distribution unit, a pressure detection component, and a control unit. The nitrogen supply unit includes a nitrogen source (1), the output of which is connected to the nitrogen supply trunk line via a filter (2) and a first pressure reducing valve (3). A nitrogen-side shut-off valve (5) is installed on the nitrogen supply trunk line. The instrument air supply unit includes an air compressor skid (7), the outlet of which is connected to the inlet of an instrument air buffer tank (9) via an instrument air-side shut-off valve (10). The outlet of the instrument air buffer tank (9) is connected to the instrument air supply trunk line. The backup connecting pipeline and the gas distribution unit are both connected between the nitrogen supply trunk line and the instrument air supply trunk line. A backup shut-off valve (15) and a pressure regulating valve (16) are installed on the backup connecting pipeline. The gas distribution unit includes a hydrogen production gas supply branch (23) and a hydrogen refueling branch. The gas supply branch (24) is used to supply gas to the hydrogen production equipment and the hydrogen refueling equipment respectively; the pressure detection component includes a nitrogen side pressure detector (6), which is located on the nitrogen supply trunk line behind the first pressure reducing valve (3), an instrument air pressure detector (28) is located on the instrument air buffer tank (9), and a merging pressure detector (27) is located on the gas supply pipeline after the nitrogen supply trunk line and the instrument air supply trunk line merge; the control unit is connected to the pressure detection component, the backup shut-off valve (15) and the pressure regulating valve (16) for interlocking to open the backup shut-off valve (15) when the detection pressure of the instrument air pressure detector (28) is lower than the first pressure threshold, so that the nitrogen supply unit can supplement the gas supply to the instrument air supply trunk line through the backup connecting pipeline, and for adjusting the opening of the pressure regulating valve (16) according to the detection pressure of the merging pressure detector (27).

2. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The nitrogen source (1) includes multiple sets of high-pressure nitrogen cylinders. A first safety valve (4) is provided on the nitrogen supply line between the first pressure reducing valve (3) and the nitrogen side shut-off valve (5). A nitrogen side pressure detector (6) is located between the first pressure reducing valve (3) and the first safety valve (4).

3. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The volume of the instrument air buffer tank (9) is set to ensure that the gas consumption of the whole station is not less than 30 minutes; the top of the instrument air buffer tank (9) is equipped with a second safety valve (11), and the bottom is equipped with a drain valve (12) and a condensate drain valve group (13); the outlet side of the instrument air buffer tank (9) is equipped with a buffer tank outlet dew point detector (14) for detecting the gas quality at the outlet of the instrument air buffer tank (9).

4. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The air compressor skid (7) is equipped with a compressor outlet dew point detector (8) on the outlet side. The compressor outlet dew point detector (8) is interlocked with the instrument air-side shut-off valve (10). The control unit is also used to interlock and close the instrument air-side shut-off valve (10) and interlock and open the backup shut-off valve (15) when the dew point value detected by the compressor outlet dew point detector (8) exceeds the set range.

5. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The backup connection pipeline is equipped with a check valve (17), which is used to prevent the airflow from the instrument air supply line to the nitrogen supply line in reverse. The backup connection pipeline is also equipped with a manual bypass (18) connected in parallel with the pressure regulating valve (16). The manual bypass (18) is equipped with a manual shut-off valve (29) and a self-regulating pressure regulating valve (30).

6. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The hydrogen supply branch (24) is equipped with a gas source distributor (19), which is used to collect the gas supply and distribute it to multiple hydrogen gas-using devices. Each hydrogen gas-using device is equipped with a shut-off valve (20), a ball valve (21), and a second pressure reducing valve (22) before the gas inlet. The gas source distributor is equipped with a drain valve (12) on its distribution pipeline.

7. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The hydrogen production and gas supply branch (23) and the hydrogen refueling and gas supply branch (24) are respectively led out from the top of the corresponding gas supply trunk line, and the high point of each gas supply branch slopes towards the corresponding gas supply trunk line, so that the condensate in the gas supply branch line flows back to the gas supply trunk line.

8. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The hydrogen production equipment is a skid-mounted integrated equipment, and the hydrogen production gas supply branch (23) is a single gas supply trunk line that supplies gas to the hydrogen production equipment.

9. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 2, characterized in that, The control unit is also used to: output a prompt to confirm the valve position status of the first pressure reducing valve (3) when the detection pressure of the nitrogen side pressure detector (6) is lower than the second pressure threshold; and interlock to close the nitrogen side shut-off valve (5) when the detection pressure of the nitrogen side pressure detector (6) is lower than the first pressure threshold.

10. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that: The pressure detection assembly also includes a purge pressure detector (26) located on the nitrogen supply line; the control unit is also used to: when the detection pressure of the purge pressure detector (26) is lower than the second pressure threshold and the hydrogen production and hydrogen refueling station is carrying out nitrogen purging operation, interlock and adjust the opening of the pressure regulating valve (16) to reduce the supply of nitrogen to the instrument air supply line.

11. The nitrogen instrument ventilation system for an integrated hydrogen production and refueling station according to claim 1, characterized in that, The control unit is also used to: when the detection pressure of the merging pressure detector (27) is lower than the preset merging pressure value, interlock to increase the opening of the pressure regulating valve (16) to increase the supplementary nitrogen supply, so that the supply pressure after merging is maintained above the preset merging pressure value.

12. A method for controlling the nitrogen instrument air supply in an integrated hydrogen production and refueling station, characterized in that, Based on the nitrogen instrument ventilation system for the integrated hydrogen production and refueling station as described in any one of claims 1 to 11, it includes: Step 1: Obtain the instrument air pressure detection signal and the combined pressure detection signal. The instrument air pressure detection signal comes from the instrument air pressure detector (28) installed on the instrument air buffer tank (9), and the combined pressure detection signal comes from the combined pressure detector (27) installed on the gas supply pipeline after the nitrogen gas supply trunk line and the instrument air supply trunk line merge. Step 2: When the instrument air pressure detection signal is lower than the first pressure threshold, the interlock opens the spare shut-off valve (15) located between the nitrogen supply line and the instrument air supply line, so that nitrogen is supplied to the instrument air supply line through the pressure regulating valve (16); adjust the opening of the pressure regulating valve (16) according to the combined pressure detection signal to maintain the combined air supply pressure.

13. The nitrogen instrument air supply control method for an integrated hydrogen production and refueling station according to claim 12, characterized in that: When the instrument air pressure detection signal is lower than the first pressure threshold, the interlock opens the backup shut-off valve (15) to allow nitrogen to be supplied to the instrument air supply line via the pressure regulating valve (16).

14. The nitrogen instrument air supply control method for an integrated hydrogen production and refueling station according to claim 12, characterized in that, Also includes: Obtain the compressor outlet dew point detection signal, which comes from the compressor outlet dew point detector (8) located on the outlet side of the air compressor skid (7); when the compressor outlet dew point detection signal exceeds the set range, interlock and close the instrument air side shut-off valve (10) located between the air compressor skid (7) and the instrument air buffer tank (9), and interlock and open the standby shut-off valve (15).

15. The nitrogen instrument air supply control method for an integrated hydrogen production and refueling station according to claim 12, characterized in that, Also includes: The nitrogen side pressure detection signal is obtained from the nitrogen side pressure detector (6) located on the nitrogen supply line behind the first pressure reducing valve (3); when the nitrogen side pressure detection signal is lower than the second pressure threshold, an output prompt is given to confirm the valve position status of the first pressure reducing valve (3); when the nitrogen side pressure detection signal is lower than the first pressure threshold, the nitrogen side shut-off valve (5) located on the nitrogen supply line is interlocked and closed.

16. The nitrogen instrument air supply control method for an integrated hydrogen production and refueling station according to claim 12, characterized in that, Also includes: The purging pressure detection signal is obtained from the purging pressure detector (26) located on the nitrogen supply line. When the purging pressure detection signal is lower than the second pressure threshold and the hydrogen production and hydrogen refueling station is carrying out nitrogen purging operation, the opening of the pressure regulating valve (16) is interlocked to reduce the supply of nitrogen to the instrument air supply line.

17. The nitrogen instrument air supply control method for an integrated hydrogen production and refueling station according to claim 12, characterized in that: When the convergence pressure detection signal is lower than the preset convergence pressure value, the opening of the pressure regulating valve (16) is increased by interlock to maintain the gas supply pressure after convergence above the preset convergence pressure value; the preset convergence pressure value is the first pressure threshold.

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