A spontaneous combustion prevention system and method for a hydrogen station venting system

Abstract

This invention discloses a spontaneous combustion prevention system and method for a hydrogen station venting system. The system includes: a venting pipeline isolation system; specifically, a main venting pipeline, one end of which connects to a gas source branch for the hydrogen station, and is equipped with an injection shut-off valve; a displacement branch is located at the end of the main venting pipeline connecting to a venting riser, and is equipped with a displacement outlet shut-off valve; the gas in the main venting pipeline is displaced by opening or closing the injection shut-off valve and the displacement outlet shut-off valve; the downstream venting pipeline includes at least two parallel venting branches, one of which is equipped with a bypass shut-off valve, and the other venting branches are equipped with rupture discs; the bypass shut-off valve is used to open under planned venting conditions and normal operation of the hydrogen station, and the rupture discs are used to rupture under unplanned venting conditions. This system can solve the spontaneous combustion problem during unplanned venting of hydrogen stations.

Description

Technical Field

[0001] This invention relates to the field of hydrogen spontaneous combustion prevention technology, and particularly to a spontaneous combustion prevention system and method for a hydrogen station venting system. Background Technology

[0002] Hydrogen energy is a recognized clean and efficient energy source. Due to geographical differences in hydrogen production and utilization, medium- and long-distance hydrogen transportation is gradually becoming a key link in the efficient utilization of hydrogen energy. Among these, pipeline transportation is a popular choice and a development direction for hydrogen energy transportation. Currently, suitable medium- and long-distance pipeline transportation modes for hydrogen energy include pure hydrogen pipeline transportation, high-hydrogen-natural gas blended pipeline transportation, and low-hydrogen-natural gas transportation. The specific mode can be selected based on the transportation distance, the available hydrogen and natural gas resources, and the user market. All of these transportation modes can provide sufficient support for the development of hydrogen energy utilization.

[0003] Pipeline transportation systems include several typical stations, such as the initial transmission station, intermediate distribution stations, booster stations, and terminal transmission stations. These stations each have their own functions, including metering, pigging, pressurization, distribution, and pressure regulation. Although these stations have different characteristics, they generally involve planned and unplanned venting operations. Planned venting mainly involves releasing flammable media from sealed pipelines and equipment before maintenance of the station and its connected pipelines. Unplanned venting mainly targets stations to quickly release accumulated flammable media from pipelines and equipment in cases of overpressure, fire, or other emergencies.

[0004] Because hydrogen has a low ignition energy and a unique reverse coke effect, in the early stages of high-pressure venting, the high-speed venting fluid will cause instantaneous compression of the local gas downstream of the vent valve in the venting system, forming a high shock wave. This can lead to a temperature rise (reaching the gas's auto-ignition temperature) and may cause the hydrogen to spontaneously combust downstream of the vent valve (a phenomenon known as "diffusion auto-ignition"), resulting in deflagration within the venting pipe of the venting system. For venting systems originally designed for a venting mode (i.e., no ignition, direct venting to the atmosphere), this may deviate from the design intent, causing the vent riser to become a "flare." Especially for unplanned venting systems, it is crucial to pay attention to issues such as untimely or uneconomical pre-venting replacement. Summary of the Invention

[0005] The inventors of this application have discovered that there is currently little research on the prevention of spontaneous combustion in hydrogen venting systems. Existing technologies mainly rely on continuous injection of non-flammable gas to perform long-term, real-time air replacement in the venting system to achieve the function of preventing spontaneous combustion in hydrogen venting systems. However, this air isolation method is resource-intensive and economically inefficient.

[0006] In view of the above problems, the present invention is proposed to provide a spontaneous combustion prevention system and method for a hydrogen station venting system that overcomes or at least partially solves the above problems.

[0007] This invention provides a spontaneous combustion prevention system for a hydrogen station venting system, comprising: a venting pipeline isolation system;

[0008] The venting pipeline isolation system includes: a venting main pipeline for connecting the hydrogen station and the venting riser, wherein one end of the venting main pipeline is connected to a gas source branch for connecting the hydrogen station, and the gas source branch is connected to a gas source device.

[0009] An injection shut-off valve is provided on the gas source branch; a replacement branch is provided at one end of the vent main line for connecting to the vent riser, and a replacement outlet shut-off valve is provided on the replacement branch; so that the non-flammable gas of the gas source device can be injected into the vent main line through the injection shut-off valve and the replacement outlet shut-off valve to replace the gas in the vent main line.

[0010] The downstream venting main pipeline of the replacement branch includes at least two parallel venting branches, one of which is equipped with a bypass shut-off valve, and the other venting branches are equipped with rupture discs. The bypass shut-off valve is used to allow gas in the venting main pipeline to be discharged from the venting riser through the bypass shut-off valve under planned venting conditions and normal operation of the hydrogen station. The rupture disc is used to rupture under unplanned venting conditions, so that the gas released from the hydrogen station mixes with non-flammable gas in the venting main pipeline and then flows through the rupture disc to be discharged from the venting riser.

[0011] In an optional embodiment, the spontaneous combustion prevention system of the hydrogen station venting system provided in this embodiment of the invention further includes: multiple buffer branches;

[0012] The buffer branch is used to connect to the bottom of the vent riser, and multiple buffer branches are arranged sequentially along the radial direction of the vent riser to buffer the gas entering the vent riser from the main vent line.

[0013] In an optional embodiment, the spontaneous combustion prevention system of the hydrogen station venting system provided by the present invention further includes: an anti-backflow system; the anti-backflow system is used to connect with the drain port of the venting riser so as to discharge the accumulated liquid in the venting riser through the anti-backflow system.

[0014] In an optional embodiment, the anti-backflow system includes: a first drain shut-off valve, a relay pipeline, and a second drain shut-off valve connected in sequence;

[0015] The first drain shut-off valve is connected to the drain port of the venting riser.

[0016] In an optional embodiment, the spontaneous combustion prevention system of the hydrogen station venting system provided by the present invention further includes a sampling device, which is connected to the replacement outlet shut-off valve to sample the gas in the venting main pipeline.

[0017] In an optional embodiment, a venting element is provided between the hydrogen station and the venting main pipeline;

[0018] The venting components include: an overpressure safety valve, an emergency relief valve, and a regulating relief valve, which are connected in parallel and connected to the hydrogen station and the venting main pipeline.

[0019] In an optional embodiment, a pressure transmitter is also provided on the vent pipe to detect the sealing performance of the vent pipe.

[0020] In an optional embodiment, the vent pipe is made of carbon steel.

[0021] In an optional embodiment, the preset burst pressure of the rupture disc is 0.1 to 0.2 barg.

[0022] Based on the same inventive concept, embodiments of the present invention provide a method for preventing spontaneous combustion of a hydrogen station venting system using the aforementioned spontaneous combustion prevention system; comprising:

[0023] Before the hydrogen station supplies gas normally, open the injection shut-off valve and the displacement outlet shut-off valve to inject non-flammable gas into the venting main pipeline until the oxygen content of the gas discharged at the displacement outlet shut-off valve is lower than the preset oxygen content threshold, and then close the injection shut-off valve and the displacement outlet shut-off valve.

[0024] Under normal gas supply conditions, the injection shut-off valve and bypass shut-off valve are opened at preset intervals to replace the gas in the venting main pipeline with non-combustible gas.

[0025] In unplanned venting conditions, the vented gas enters the venting main pipeline through the overpressure safety valve or emergency relief valve of the venting element, mixes with the non-combustible gas in the venting main pipeline, and flows into the venting riser from the venting main pipeline after reaching the preset burst pressure of the rupture disc.

[0026] When venting is planned, open the bypass shut-off valve, and then open the venting element's relief valve to allow the vented gas to enter the venting main line and mix with the non-flammable gas in the venting main line. The gas will then flow from the bypass shut-off valve into the venting riser and be discharged.

[0027] In an optional embodiment, the spontaneous combustion prevention method provided by the present invention further includes: gas flowing into the vent riser from the vent main pipeline is buffered by a buffer branch and then discharged from the vent riser.

[0028] In an optional embodiment, the spontaneous combustion prevention method provided by this invention involves opening a first drain shut-off valve after the amount of liquid accumulated at the bottom of the vent riser exceeds a preset upper limit for liquid accumulation, so that the liquid in the vent riser flows into the relay pipeline until the amount of liquid collected at the bottom of the vent main pipeline is lower than a preset lower limit for liquid accumulation, then closing the first drain shut-off valve, and subsequently opening a second drain shut-off valve to discharge the liquid in the relay pipeline, and then closing the second drain shut-off valve.

[0029] In an optional embodiment, the spontaneous combustion prevention method provided by the present invention further includes: using a pressure transmitter to detect the sealing performance of the venting main pipeline.

[0030] The beneficial effects of the above-described technical solutions provided in the embodiments of the present invention include at least the following:

[0031] The spontaneous combustion prevention system provided in this invention is designed specifically for the operational characteristics of hydrogen stations and the tendency for spontaneous combustion after hydrogen release. It meets the needs of both planned and unplanned venting in hydrogen station venting systems. Before normal operation of the hydrogen station, a non-flammable gas is injected into the main venting pipeline to replace the existing gas. After the gas in the main venting pipeline is replaced with a non-flammable gas, the injection shut-off valve, bypass shut-off valve, and replacement outlet shut-off valve are closed. Combined with the rupture disc, this provides a long-term sealing effect for the non-flammable gas in the main venting pipeline. During normal operation of the hydrogen station, spontaneous combustion can be prevented only after a preset time. The gas in the venting main pipeline can be replaced. Compared with the existing air isolation measures that use continuous injection of non-flammable gas to replace the air in the venting system for long-term and real-time replacement, the venting pipeline isolation system proposed in this embodiment optimizes continuous replacement into an intermittent replacement + long-term static mode, which greatly reduces the loss of non-flammable gas and the energy consumption when introducing non-flammable gas, and increases economic benefits. Moreover, in the venting state, after the gas in the hydrogen station is released, it will mix with the non-flammable gas sealed in the venting main pipeline, thereby achieving the effect of isolating the air after the gas is discharged from the venting point, which essentially reduces the possibility of hydrogen spontaneous combustion. Meanwhile, by utilizing the non-flammable gas injection function provided by the venting pipeline isolation system of this invention, when the venting system selects the venting flare, non-flammable gas can be injected into the venting main pipeline by opening the injection shut-off valve and the bypass shut-off valve in the middle and later stages of venting. This provides a positive pressure seal for the venting main pipeline in the middle and later stages of venting, eliminating the need for a flame arrestor and simplifying the structure of the entire venting system. It can also prevent backfire problems that may be caused by a decrease in the flow rate of the discharged medium.

[0032] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 This is a schematic diagram of the spontaneous combustion prevention system of the hydrogen station venting system in an embodiment of the present invention.

[0036] Explanation of reference numerals in the attached figures

[0037] 1-Vent main line, 2-Gas source branch line, 3-Replacement branch line, 4-Vent branch line, 5-Buffer branch line, 6-Anti-backflow system, 7-Vent element, 8-Vent riser, 9-Pressure transmitter;

[0038] 21-Injection shut-off valve, 31-Replacement outlet shut-off valve, 41-Rupture disc, 42-Spare rupture disc, 43-Bypass shut-off valve; 61-First drain shut-off valve, 62-Relay pipeline, 63-Second drain shut-off valve; 71-Overpressure safety valve, 72-Emergency relief valve, 73-Regulating relief valve. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0040] In order to overcome the shortcomings of existing technologies and further improve the spontaneous combustion prevention technology of hydrogen station venting systems, this invention provides a spontaneous combustion prevention system for hydrogen station venting systems from the perspectives of spontaneous combustion principle and efficient response.

[0041] Reference Figure 1 As shown, the spontaneous combustion prevention system of the hydrogen station venting system provided in this embodiment of the invention includes: a venting pipeline isolation system;

[0042] The venting isolation system includes: a venting main pipeline 1 for connecting the hydrogen station and the venting riser; one end of the venting main pipeline 1 for connecting to the hydrogen station is connected to a gas source branch pipeline 2; and the gas source branch pipeline 2 is for connecting to a gas source device.

[0043] An injection shut-off valve 21 is provided on the gas source branch line 2; a replacement branch line 3 is provided at one end of the vent main line 1 for connecting to the vent riser 8, and a replacement outlet shut-off valve 31 is provided on the replacement branch line 3; so that the non-flammable gas of the gas source device can be injected into the vent main line 1 by controlling the injection shut-off valve 21 and the replacement outlet shut-off valve 31 to replace the gas in the vent main line 1.

[0044] The downstream venting main pipeline 1 of the replacement branch includes at least two parallel venting branches 4, one of which is equipped with a bypass shut-off valve 43, and the other venting branches are equipped with rupture discs 41. The bypass shut-off valve 43 is used to allow the gas in the venting main pipeline 1 to be discharged from the venting riser 8 through the bypass shut-off valve 43 under planned venting conditions and normal operation of the hydrogen station. The rupture disc 41 is used to rupture under unplanned venting conditions so that the gas released from the hydrogen station is mixed with non-flammable gas in the venting main pipeline 1 and then flows through the rupture disc 41 and is discharged from the venting riser.

[0045] The spontaneous combustion prevention system provided in this invention is designed specifically for the operational characteristics of hydrogen stations and the tendency for spontaneous combustion after hydrogen release. It meets the needs of both planned and unplanned venting in hydrogen station venting systems. Before normal operation of the hydrogen station, a non-flammable gas is injected into the main venting pipeline to replace the existing air. After the gas in the main venting pipeline is replaced with a non-flammable gas, the injection shut-off valve, bypass shut-off valve, and replacement outlet shut-off valve are closed. Combined with a rupture disc, this provides a long-term sealing effect for the non-flammable gas in the main venting pipeline. During normal operation of the hydrogen station, the gas in the main venting pipeline only needs to be replaced at preset times to prevent spontaneous combustion. To prevent internal leakage in valves such as the outlet shut-off valve and bypass relief valve, which could allow other gases to enter the venting main pipeline, this invention proposes a venting pipeline isolation system that optimizes continuous replacement into an intermittent replacement + long-term static mode. This significantly reduces the loss of non-flammable gases and the energy consumption when introducing them, thus increasing economic benefits. Furthermore, during venting, the gas released from the hydrogen station mixes with the non-flammable gas enclosed in the venting main pipeline, effectively isolating the gas from the venting point and fundamentally reducing the possibility of hydrogen spontaneous combustion. Meanwhile, by utilizing the non-flammable gas injection function provided by the venting pipeline isolation system of this invention, when the venting system selects the venting flare, non-flammable gas can be injected into the venting main pipeline by opening the injection shut-off valve and the bypass shut-off valve in the middle and later stages of venting. This provides a positive pressure seal for the venting main pipeline in the middle and later stages of venting, eliminating the need for a flame arrestor and simplifying the structure of the entire venting system. It can also prevent backfire problems that may be caused by a decrease in the flow rate of the discharged medium.

[0046] Specifically, the venting pipeline isolation system is used to isolate the venting pipeline from non-flammable gases for a long period of time. It provides a non-flammable gas mixture at the front end of the hydrogen release during unplanned venting and isolates it from air, so as to prevent the high-pressure venting gas from spontaneously combusting or igniting due to medium compression and temperature rise or friction between the medium and the pipeline in the initial stage of unplanned venting.

[0047] In the venting pipeline isolation system provided in this embodiment of the invention, the injection shut-off valve 21 and the displacement outlet shut-off valve 31 can be carbon steel ball valves and can be manually controlled valves. During use, the injection shut-off valve 21 and the displacement outlet shut-off valve 31 are normally closed. The injection shut-off valve is only opened when non-flammable gas is injected into the venting main pipeline to control the gas source device to inject non-flammable gas into the venting main pipeline. The displacement outlet shut-off valve 31 is generally opened during the initial displacement of gas in the venting main pipeline under normal operating conditions of the hydrogen station.

[0048] Furthermore, the venting main pipeline 1 connects the hydrogen station and the venting riser, providing a flow channel for the vented gas. The venting main pipeline 1 can be made of carbon steel. Since non-flammable gases are permanently sealed inside the venting main pipeline 1, the gas released from the hydrogen station will mix with the non-flammable gases inside the venting main pipeline after entering it. Therefore, during the gas flow, the spontaneous combustion phenomenon caused by friction between the released gas and the pipe wall of the venting main pipeline can be reduced. Thus, the material requirements for the venting main pipeline are reduced, and the venting main pipeline can be made of carbon steel instead of the stainless steel material in the existing technology, further improving economic efficiency and reducing investment.

[0049] Optionally, the spontaneous combustion prevention system of this embodiment may further include a sampling device (not shown in the figure). The sampling device is connected to the displacement outlet shut-off valve 31 to sample the gas in the venting main pipeline. Before the hydrogen station is in normal operation, when the injection shut-off valve 21 and the displacement outlet shut-off valve 31 are opened to replace the gas in the venting main pipeline, after a preset replacement time, the sampling device is used to sample the gas in the venting main pipeline from the displacement outlet shut-off valve 31, and the sampled gas is subjected to component detection. When the oxygen content in the gas discharged from the displacement outlet shut-off valve 31 is lower than the preset oxygen content value, it indicates that the gas replacement in the venting main pipeline is completed. At this time, the injection shut-off valve 21 and the displacement outlet shut-off valve 31 are closed. Preferably, the preset replacement time is not less than 5 minutes, and the preset oxygen content is that the volume fraction of oxygen content is less than 1% of the total gas content. Specifically, the specific values ​​of the preset replacement time and the preset oxygen content are not specifically limited in this embodiment and can be set according to actual needs. The sampling device may specifically be a sampling tube.

[0050] The gas source device can be a non-flammable gas storage cylinder. Furthermore, the spontaneous combustion prevention system of this embodiment only requires gas replacement in the venting main pipeline at preset times, thus reducing the number of times the non-flammable gas storage cylinder needs to be replaced. This further reduces the risk of hydrogen spontaneous combustion during non-flammable gas storage cylinder replacement, improving the reliability of the spontaneous combustion prevention system. Preferably, the injected non-flammable gas is carbon dioxide or nitrogen.

[0051] Meanwhile, the spontaneous combustion prevention system provided in this embodiment of the invention can be equipped with multiple rupture discs 41. The rupture discs 41 are used to rupture after the hydrogen station releases gas, guiding the released gas into the vent riser. Furthermore, before the hydrogen station releases gas, the system can prevent gas in the main vent pipeline 1 from entering the vent riser 8, thus preventing air from flowing back into the main vent pipeline via the vent riser. The structure with multiple rupture discs can provide backup rupture discs, preventing unplanned venting failure due to the failure of a single rupture disc, thereby improving the reliability of rupture disc venting. Regarding the number of parallel vent branches, this embodiment of the invention does not specifically limit this number; preferably, at least three are allowed, as detailed in the following reference. Figure 1 As shown, a bypass shut-off valve 43 is installed on one of the vent branches, and a rupture disc 41 and a spare rupture disc 42 are installed on the other two vent branches; furthermore, the rupture disc can be a micro-positive pressure rupture disc, and the preset rupture pressure of each rupture disc can be 0.1 to 0.2 barg.

[0052] The bypass shut-off valve 43 can be a manual ball valve, installed in parallel with the rupture disc 41 and the spare rupture disc 42. It is normally closed and is opened when the gas in the venting main pipeline 1 is periodically replaced. That is, when the gas is replaced, the replacement outlet shut-off valve 31 is closed and the bypass shut-off valve 43 is used for replacement. The purpose is to ensure that if unplanned venting occurs during the gas replacement process, the unplanned vented gas can flow through the venting main pipeline 1 and be discharged from the venting riser, avoiding the vented gas from being discharged from the replacement outlet shut-off valve and causing danger; this further improves the reliability of the entire system.

[0053] Optionally, a pressure transmitter 9 can also be installed on the vent main line 1 to detect the sealing performance of the vent main line 1. This is used to characterize the sealing performance of the rupture disc 41, the spare rupture disc 42, and the bypass shut-off valve 43, preventing the vent main line 1 from losing its sealing function against non-flammable gases due to accidental rupture of the rupture disc 41 or loosening of the bypass shut-off valve 43, thus preventing the venting system from losing its self-ignition prevention function. Specifically, the pressure transmitter is installed before the replacement branch line 3, and the monitoring pressure value of the pressure transmitter 9 can be set to 0.1 barg. That is, when the pressure detected by the pressure transmitter is less than 0.1 barg, it indicates that the gas pressure in the vent main line 1 is at atmospheric pressure, further indicating that the vent main line may be connected to the outside. In this case, the vent pipeline isolation system needs to be inspected to ensure the sealing function of the vent main line 1 against non-flammable gases, further improving the reliability of the vent pipeline isolation system.

[0054] In an optional embodiment, the spontaneous combustion prevention system provided by the present invention may further include: multiple buffer branches 5;

[0055] The buffer branch 5 is used to connect to the bottom of the vent riser 8, and multiple buffer branches 5 are arranged in sequence along the radial direction of the vent riser 8 to buffer the gas entering the vent riser 8 from the main vent line 1.

[0056] Multiple buffer branches 5 constitute a venting pipeline buffer system. This system is used to buffer the gas flowing from the main venting pipeline 1 into the venting riser 8 during the initial stages of planned and unplanned venting, as well as during the venting process. Specifically, the gas entering the venting riser 8 from the main venting pipeline 1 flows through the buffer branches 5, where it is buffered and its flow path is altered before exiting the venting riser. Compared to the method where the gas directly collides with the venting riser wall and changes its flow path upon entering the riser, the buffer branches 5 absorb the kinetic energy of the high-speed venting gas as it transitions from the horizontal main venting pipeline to the vertical venting riser, mitigating vibration and friction under high-speed impact and reducing the probability of sparks during high-speed flow changes. Specifically, the buffer branches 5 may include buffer pipes and blind flanges installed at the ends of the buffer pipes.

[0057] Optionally, the spontaneous combustion prevention system of this embodiment of the invention further includes: an anti-backflow system 6; the anti-backflow system 6 is used to communicate with the drain port of the venting riser so as to discharge the accumulated liquid in the venting riser through the anti-backflow system.

[0058] Specifically, the anti-backflow system includes: a first drain shut-off valve 61, a relay pipeline 62, and a second drain shut-off valve 63 connected in sequence;

[0059] The first drain shut-off valve is connected to the drain port of the vent riser.

[0060] The first drain shut-off valve 61 and the second drain shut-off valve 63 can be manual ball valves, which are normally closed and only open when draining the vent riser. In application, the first drain shut-off valve 61 and the second drain shut-off valve 63 are not opened at the same time.

[0061] Under normal operating conditions of the hydrogen station, the liquid accumulated at the bottom of the vent riser (or vent flare) is discharged manually. When the amount of liquid accumulated at the bottom of the vent riser reaches the preset upper limit (after reaching the upper limit of the level gauge), the first drain shut-off valve 61 is opened first, and part of the liquid is discharged into the relay pipeline 62. After the amount of liquid collected at the bottom of the vent riser 8 is lower than the preset lower limit of the liquid accumulation (lower limit of the level gauge), the first drain shut-off valve 61 is closed. The second drain shut-off valve 63 is opened to discharge the liquid in the relay pipeline 62, and then the second drain shut-off valve 63 is closed. This ensures that the upstream of the first drain shut-off valve 61 remains liquid-sealed, and that the two shut-off valves in the relay pipeline (the first drain shut-off valve 61 and the second drain shut-off valve 63) do not open simultaneously. This prevents outside air from entering the venting riser through the opened first drain shut-off valve 61 and the second drain shut-off valve 63 during high-speed venting, which could cause hydrogen and air to mix in the riser. This also helps prevent backflow in the venting system.

[0062] Furthermore, the spontaneous combustion prevention system of this embodiment of the invention refers to... Figure 1 As shown, an venting element 7 is installed between the hydrogen station and the main venting pipeline 1;

[0063] The venting element 7 includes: an overpressure safety valve 71, an emergency relief valve 72, and a regulating relief valve 73, which are connected in parallel and connected to the hydrogen station and the venting main pipeline.

[0064] Specifically, the gas source branch 2 is located downstream of the venting element 7; wherein, the overpressure safety valve 71 and the emergency relief valve 72 are in the open state during unplanned venting. At this time, the gas vented from the hydrogen station flows through the overpressure safety valve 71 or the emergency relief valve 72 and then flows into the venting main pipeline to mix with the gas in the venting main pipeline, thereby suppressing its diffusion and spontaneous combustion; when the pressure of the mixed gas is slightly higher than the preset rupture pressure of the rupture disc, the mixed gas enters the venting riser to achieve safe discharge and treatment. Furthermore, a flow-limiting orifice plate can be installed after the emergency relief valve 72 so that the pressure of the gas vented from the hydrogen station can be released after flowing through the flow-limiting orifice plate.

[0065] The regulating vent valve 73 is opened during planned venting, and the flow rate of the gas during planned venting can be controlled by controlling the opening degree of the regulating vent valve 73. At this time, the bypass shut-off valve 43 is also in the open state. The gas vented from the hydrogen station flows through the regulating vent valve 73 and enters the venting main pipeline. The vented gas at the front end mixes with the non-combustible gas accumulated in the venting main pipeline 1 and flows through the opened bypass shut-off valve before being discharged from the venting riser, so as to achieve safe gas discharge and treatment.

[0066] To overcome the shortcomings of existing technologies and further improve the spontaneous combustion prevention technology of hydrogen station venting systems, this paper proposes a spontaneous combustion prevention system and method for hydrogen station venting systems. Based on the characteristics of unplanned venting in hydrogen stations and the potential for spontaneous combustion under low-pressure venting of hydrogen, this paper addresses the issues of long-term air isolation in the venting system, efficient use of replacement gas, and prevention of air entry during the venting process. It includes a venting pipeline isolation system, a venting buffer system, and an anti-backflow system. This system can prevent spontaneous combustion caused by medium compression and heating, or friction between the medium and the pipeline, from occurring in the main venting pipeline during unplanned venting of hydrogen stations. Furthermore, it includes the necessary station facilities to constitute the complete function of this system, such as the hydrogen station, venting riser, and venting elements. It should be noted that the above elements are existing technologies and are not the innovative points of this invention.

[0067] The spontaneous combustion prevention system provided in this invention features a venting pipeline isolation system that isolates the main venting pipeline using rupture discs and valves. This ensures that the gas within the venting pipeline is isolated from air (mostly non-flammable gases), and includes a periodic replacement function. This prevents air from entering the venting pipeline during normal operation of the hydrogen station due to valve leakage, ensuring that hydrogen released from the high-pressure end cannot come into contact with air after entering the venting pipeline, thus preventing spontaneous combustion. This method is more energy-efficient than continuously supplying sealing gas. When the pressure in the venting pipeline exceeds the preset rupture pressure of the rupture disc, the disc ruptures. However, the gas leading to the rupture disc is non-flammable, acting as a barrier to disperse the air downstream of the rupture disc, effectively preventing spontaneous combustion. To ensure the reliability of the rupture disc, a backup rupture disc is provided. Furthermore, a temporarily open bypass shut-off valve is included to ensure emergency venting during venting pipeline replacement.

[0068] Furthermore, due to the extremely low density of hydrogen and its rapid venting speed, negative pressure can easily form inside the venting riser. Therefore, the drainage system of the venting riser is set to a dual-stop mode (first drainage shut-off valve and second drainage shut-off valve), and the two cannot be opened at the same time to avoid the bottom of the venting riser being directly connected to the atmosphere during the drainage process, which could cause the risk of atmospheric backflow.

[0069] Based on the same inventive concept, embodiments of the present invention also provide a method for natural fire prevention using the aforementioned spontaneous combustion prevention system of the hydrogen station venting system, comprising the following steps:

[0070] Before the hydrogen station is in normal operation, open the injection shut-off valve and the displacement outlet shut-off valve to inject non-flammable gas into the venting main pipeline until the oxygen content of the gas discharged at the displacement outlet shut-off valve is lower than the preset oxygen content threshold, and then close the injection shut-off valve and the displacement outlet shut-off valve.

[0071] Under normal operating conditions, the injection shut-off valve and bypass shut-off valve are opened at preset intervals to replace the gas in the venting main pipeline with non-combustible gas.

[0072] In unplanned venting conditions, the vented gas enters the main venting pipeline through the overpressure safety valve or emergency relief valve of the venting element, mixes with the non-combustible gas in the main venting pipeline, and flows into the venting riser from the main venting pipeline after reaching the preset burst pressure of the rupture disc.

[0073] When venting is planned, open the bypass shut-off valve, and then open the venting element's relief valve to allow the vented gas to enter the venting main line and mix with the non-flammable gas in the venting main line. The gas will then flow from the bypass shut-off valve into the venting riser and be discharged.

[0074] Specifically, when replacing the gas in the venting main pipeline before the hydrogen station is in normal operation, the duration should be no less than 5 minutes. A sample should be taken at the outlet of the replacement outlet shut-off valve to detect the composition of the gas in the venting main pipeline. Preferably, the volume fraction of oxygen in the discharged medium is less than 1% of the total gas content, which is considered a qualified gas replacement.

[0075] Under normal operating conditions, the preset time for replacing the gas in the venting main pipeline at preset intervals can be once a week.

[0076] The spontaneous combustion prevention method provided in this embodiment of the invention further includes: the venting gas flowing from the venting main pipeline into the venting riser is buffered by the buffer branch and then discharged from the venting riser.

[0077] The spontaneous combustion prevention method provided in this embodiment of the invention further includes: after the amount of liquid accumulated at the bottom of the vent riser exceeds a preset upper limit for liquid accumulation, opening a first drain shut-off valve to allow the liquid in the vent riser to flow into the relay pipeline until the amount of liquid accumulated at the bottom of the main vent pipeline falls below a preset lower limit for liquid accumulation, closing the first drain shut-off valve, then opening a second drain shut-off valve to allow the liquid in the relay pipeline to drain, and finally closing the second drain shut-off valve to achieve the discharge of liquid collected at the bottom of the vent riser. Specifically, the amount of liquid accumulated in the vent riser can be measured by a level gauge installed at the bottom of the vent riser.

[0078] The spontaneous combustion prevention method provided in this embodiment of the invention further includes: using a pressure transmitter to detect the sealing performance of the venting main pipeline.

[0079] Regarding the spontaneous combustion prevention system of the hydrogen station venting system in the above embodiments, the specific operation methods of each module have been described in detail in the embodiments related to the spontaneous combustion prevention system, and will not be elaborated here.

[0080] The spontaneous combustion prevention system and method provided in this invention provide safety guarantees from aspects such as isolating air in the initial stage of venting, mitigating the turning impact during venting, and preventing backflow of air during venting, forming a more economical and reliable spontaneous combustion prevention system for medium- and high-pressure hydrogen station venting systems. Specifically, it is manifested in:

[0081] (1) Scientific setup

[0082] This invention addresses the operational characteristics of hydrogen stations and the inherent susceptibility to spontaneous combustion after hydrogen venting. It modifies existing venting methods by addressing issues such as air isolation, mitigating static electricity caused by turning collisions, premixing vented hydrogen with non-flammable gases, and preventing air from being introduced through the drain outlet. This significantly reduces the probability of spontaneous combustion in the venting system caused by hydrogen venting. For example, the venting pipeline isolation system provides a long-term seal for non-flammable gases, ensuring that hydrogen is isolated from air and fully mixed with non-flammable gases after being discharged from the venting point, thus substantially reducing the possibility of spontaneous combustion. The venting pipeline anti-backflow system is specifically designed for hydrogen with high flow rates (hydrogen has an extremely high sound velocity, reaching 1300 m / s), employing enhanced protection strategies to prevent external air from being drawn into the venting system due to excessively high hydrogen flow rates.

[0083] (2) Excellent economic efficiency

[0084] Compared to traditional self-ignition control modes, the venting pipeline isolation system proposed in this invention optimizes continuous purging into an intermittent purging + long-term static mode, significantly reducing the consumption of non-combustible gases and the energy consumption of introducing non-combustible gases. Furthermore, due to the inherent isolation provided by this invention, the venting system can be made of carbon steel, reducing investment. At the same time, with the non-combustible gas injection function provided by the venting pipeline isolation system of this invention, in venting ignition scenarios, it can be used to provide gas sealing function for the venting pipeline in the mid-to-late stages of venting, eliminating the need for a flame arrester.

[0085] (3) Promote technological development

[0086] This invention focuses on the prevention of spontaneous combustion in the venting system of hydrogen stations, which is in line with the development plan for the efficient utilization of hydrogen energy. Given the limited amount of publicly available information, it can serve as a support for the technological advancement of safe operation of such stations, and has good social benefits while ensuring safety.

[0087] Regarding the device in the above embodiments, the specific manner in which the operation is performed has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0088] The foregoing description includes examples of one or more embodiments. It is certainly impossible to describe all possible combinations of components or methods in order to describe the above embodiments, but those skilled in the art will recognize that further combinations and arrangements of the various embodiments are possible. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. Furthermore, the term "comprising" as used in the specification or claims is interpreted in a manner similar to the term "including," as interpreted when used as a conjunction in the claims. Additionally, the use of any term "or" in the specification of the claims is intended to mean "non-exclusive or."

[0089] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A spontaneous combustion prevention system for a hydrogen station venting system, characterized in that, include: Vent pipe isolation system and backflow prevention system; The venting pipeline isolation system includes: a venting main pipeline for connecting the hydrogen station and the venting riser, wherein one end of the venting main pipeline is connected to a gas source branch for connecting the hydrogen station, and the gas source branch is connected to a gas source device. An injection shut-off valve is provided on the gas source branch; a replacement branch is provided at one end of the vent main line for connecting to the vent riser, and a replacement outlet shut-off valve is provided on the replacement branch; so that the non-flammable gas of the gas source device can be injected into the vent main line through the injection shut-off valve and the replacement outlet shut-off valve to replace the gas in the vent main line. The downstream venting main pipeline of the replacement branch includes at least two parallel venting branches, one of which is equipped with a bypass shut-off valve, and the other venting branches are equipped with rupture discs. The bypass shut-off valve is used to allow gas in the venting main pipeline to be discharged from the venting riser through the bypass shut-off valve under planned venting conditions and normal operation of the hydrogen station. The rupture disc is used to rupture under unplanned venting conditions so that the gas released from the hydrogen station mixes with non-flammable gas in the venting main pipeline and then flows through the rupture disc to be discharged from the venting riser. The anti-backflow system includes: a first drain shut-off valve, a relay pipeline, and a second drain shut-off valve connected in sequence; The first drain shut-off valve is connected to the drain port of the vent riser so as to drain the accumulated liquid in the vent riser through the anti-backflow system.

2. The spontaneous combustion prevention system for the hydrogen station venting system as described in claim 1, characterized in that, Also includes: Multiple buffer branches; The buffer branch is used to connect to the bottom of the vent riser, and multiple buffer branches are arranged sequentially along the radial direction of the vent riser to buffer the gas entering the vent riser from the main vent line.

3. The spontaneous combustion prevention system as described in claim 1, characterized in that, It also includes a sampling device, which is connected to the displacement outlet shut-off valve to sample the gas in the venting main pipeline.

4. The spontaneous combustion prevention system for the hydrogen station venting system as described in claim 1, characterized in that, A venting element is installed between the hydrogen station and the main venting pipeline; The venting components include: an overpressure safety valve, an emergency relief valve, and a regulating relief valve that are connected in parallel and connected to the hydrogen station and the main venting pipeline.

5. The spontaneous combustion prevention system as described in claim 1, characterized in that, A pressure transmitter is also installed on the venting main line to detect the sealing performance of the venting main line.

6. The spontaneous combustion prevention system as described in claim 1, characterized in that, The venting main pipeline is made of carbon steel.

7. The spontaneous combustion prevention system according to any one of claims 1-6, characterized in that, The preset burst pressure of the rupture disc is 0.1 to 0.2 barg.

8. A method for preventing spontaneous combustion of a hydrogen station venting system, characterized in that, This is achieved using the spontaneous combustion prevention system of the hydrogen station venting system as described in any one of claims 1-7; comprising: Before the hydrogen station supplies gas normally, open the injection shut-off valve and the displacement outlet shut-off valve to inject non-flammable gas into the venting main pipeline until the oxygen content of the gas discharged at the displacement outlet shut-off valve is lower than the preset oxygen content threshold, and then close the injection shut-off valve and the displacement outlet shut-off valve. Under normal gas supply conditions, the injection shut-off valve and bypass shut-off valve are opened at preset intervals to replace the gas in the venting main pipeline with non-combustible gas. In unplanned venting conditions, the vented gas enters the venting main pipeline through the overpressure safety valve or emergency relief valve of the venting element, mixes with the non-combustible gas in the venting main pipeline, and flows into the venting riser from the venting main pipeline after reaching the preset burst pressure of the rupture disc. When venting is planned, open the bypass shut-off valve, and then open the venting element's relief valve to allow the vented gas to enter the venting main line and mix with the non-flammable gas in the venting main line. The gas will then flow from the bypass shut-off valve into the venting riser and be discharged.

9. The spontaneous combustion prevention method as described in claim 8, characterized in that, Also includes: Gas flowing into the vent riser from the main vent line is buffered by the buffer branch and then discharged from the vent riser.

10. The spontaneous combustion prevention method as described in claim 9, characterized in that, Also includes: After the amount of liquid accumulated at the bottom of the vent riser exceeds the preset upper limit of liquid accumulation, the first drain shut-off valve is opened to allow the liquid in the vent riser to flow into the relay pipeline until the amount of liquid collected at the bottom of the vent main pipeline is lower than the preset lower limit of liquid accumulation. Then the first drain shut-off valve is closed, and the second drain shut-off valve is opened to allow the liquid in the relay pipeline to be discharged. Finally, the second drain shut-off valve is closed.

11. The spontaneous combustion prevention method according to any one of claims 8-10, characterized in that, Also includes: The sealing performance of the vent pipe is tested using a pressure transmitter.

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