A safety protection device for hydrogen liquefaction systems

Abstract

A safety protection device for a hydrogen liquefaction system, belonging to the field of hydrogen liquefaction technology, includes components such as a liquid hydrogen storage tank (1), a liquid hydrogen discharge outlet pipe (2), a special quick connector (3), a non-conforming liquid hydrogen shut-off valve (4), a non-conforming liquid hydrogen pipeline (5), a first emergency vaporizer front-end shut-off valve (6), a second emergency vaporizer front-end shut-off valve (7), a first emergency vaporizer (8), a second emergency vaporizer (9), a first emergency vaporizer rear-end shut-off valve (10), a second emergency vaporizer rear-end shut-off valve (11), an emergency vaporizer outlet pipe (12), an emergency heater (13), an emergency heater outlet pipe (14), and a flare system (15). Its advantages are that it can ensure the safe and stable operation of the hydrogen liquefaction system, collecting and vaporizing the non-conforming liquid hydrogen components and the gas-liquid mixture released from the overpressure of the liquid hydrogen storage tank for combustion; and ensuring that in the event of an accident, a large amount of liquid hydrogen can be rapidly vaporized and sent to the flare system for safe combustion and discharge.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen liquefaction technology, and specifically relates to a safety protection device for hydrogen liquefaction systems, which is applicable to the safe discharge of liquid hydrogen components with substandard purity, gas-liquid mixtures from the vent of liquid hydrogen storage tanks, and in the event of an accident in the hydrogen liquefaction system. Background Technology

[0002] Driven by the dual goals of "peak carbon emissions and carbon neutrality," the hydrogen energy industry has become a hot topic in my country's industrial development, and hydrogen energy is currently in a critical period of vigorous development. Hydrogen energy is considered the most promising secondary energy source of the 21st century, and its development and utilization have become an important direction for a new round of global energy transformation. Since the beginning of this century, developed Western countries, led by the United States, have successively formulated hydrogen energy development plans. my country's understanding of the entire lifecycle of hydrogen energy commercial applications, including production, storage, transportation, and application, is still immature, with hydrogen liquefaction storage and transportation being a bottleneck. According to incomplete statistics, since the beginning of this year, various central ministries and commissions, as well as nearly 30 provinces across the country, have issued more than 100 hydrogen energy development plans and related support and supporting policies, concentrating scientific research efforts on hydrogen energy development. In particular, breakthroughs in large-scale hydrogen liquefaction devices and technological challenges are urgently needed to narrow the gap with developed Western countries, which is of great significance.

[0003] The hydrogen produced by the hydrogen compressor is liquefied through a helium cycle and a hydrogen cycle. The helium cycle primarily uses closed-loop helium refrigeration to provide the cooling capacity for the liquefied hydrogen. In the hydrogen cycle, hydrogen enters a cold box, where it exchanges heat with the returning cold nitrogen and cold helium to cool to 80K. It then undergoes throttling expansion liquefaction, and the subcooled liquid hydrogen is transported from the cold box to the liquid hydrogen storage tank. During operation of the hydrogen liquefaction unit, the purity of the liquid hydrogen may not meet standards, requiring safe discharge of this portion. When the liquid hydrogen storage tank experiences overpressure, a large amount of accumulated gas-liquid mixture must be discharged. In case of an accident, the liquid hydrogen system also requires the safe discharge of a large amount of liquid hydrogen to ensure the safety of the system and personnel and property. Cryogenic liquid hydrogen has an absolute temperature of approximately -253℃ and a hydrogen content of approximately 99.9999%. Due to its extremely low temperature and flammable and explosive properties, improper handling of cryogenic liquid hydrogen will inevitably cause significant harm to equipment near the emission source, civil engineering foundations, the surrounding environment, and personnel.

[0004] Regarding the aforementioned issues, if direct on-site air discharge is adopted, cryogenic liquid hydrogen and hydrogen gas will accumulate. Due to its greater density than air, the equipment requires a huge amount of space to ensure safety. Currently, there are no mandatory or recommended national regulations allowing the direct discharge of liquid hydrogen. In the event of a fire or other accident in the liquid hydrogen system, the cryogenic liquid hydrogen will rapidly vaporize at ambient temperature, and the hydrogen concentration will agglomerate within the accident area. If this agglomerates upon contact with an open flame, it is highly likely to cause an explosion, posing an extremely serious hazard. Therefore, a safe and economical liquid hydrogen discharge treatment device and measure is urgently needed for hydrogen liquefaction systems. Summary of the Invention

[0005] The purpose of this invention is to provide a safety protection device for a hydrogen liquefaction system. This device can collect and vaporize substandard liquid hydrogen components and gas-liquid mixtures released from the liquid hydrogen storage tank under overpressure during operation. Furthermore, it ensures that in the event of an accident, a large amount of liquid hydrogen can be rapidly vaporized and safely incinerated and discharged via a flare. This ensures that the liquid hydrogen system area and the external environment are unaffected, resolves safety hazards during the hydrogen liquefaction process, and thus guarantees the overall system's operational safety and meets production requirements.

[0006] This invention mainly includes components such as a liquid hydrogen storage tank 1, a liquid hydrogen discharge outlet pipe 2, a special quick connector 3, a non-conforming liquid hydrogen shut-off valve 4, a non-conforming liquid hydrogen pipe 5, a first emergency vaporizer front-end shut-off valve 6, a second emergency vaporizer front-end shut-off valve 7, a first emergency vaporizer 8, a second emergency vaporizer 9, a first emergency vaporizer rear-end shut-off valve 10, a second emergency vaporizer rear-end shut-off valve 11, an emergency vaporizer outlet pipe 12, an emergency heater 13, an emergency heater outlet pipe 14, and a flare system 15.

[0007] The discharge port c of liquid hydrogen storage tank 1 is connected to liquid hydrogen discharge outlet pipe 2; the product purity non-compliance outlet b of liquid hydrogen storage tank 1 is sequentially connected to special quick connector 3, non-compliance liquid hydrogen shut-off valve 4, and non-compliance liquid hydrogen pipe 5; after the liquid hydrogen discharge outlet pipe 2 and non-compliance liquid hydrogen pipe 5 are combined, they are split into two paths and connected to the front shut-off valve 6 of the first emergency vaporizer and the front shut-off valve 7 of the second emergency vaporizer respectively; the front shut-off valve 6 of the first emergency vaporizer and the front shut-off valve 7 of the second emergency vaporizer are connected to the first emergency vaporizer 8 and the second emergency vaporizer 9 respectively, and then connected to the rear shut-off valve 10 of the first emergency vaporizer and the rear shut-off valve 11 of the second emergency vaporizer respectively; the rear shut-off valve 10 of the first emergency vaporizer and the rear shut-off valve 11 of the second emergency vaporizer are combined through the emergency vaporizer outlet pipe 12 and connected to the emergency heater 13; finally, the emergency heater 13 is connected to the flare system 15 through the emergency heater outlet pipe 14.

[0008] The liquid hydrogen storage tank 1 of this invention is equipped with a liquid hydrogen filling inlet (a), a product purity defect outlet (b), and a discharge outlet (c). During normal production, the dedicated quick connector 3 is disconnected from the discharge outlet (c) of the liquid hydrogen storage tank 1. When the purity of the filled liquid hydrogen is unqualified, a dedicated liquid hydrogen connection pipe is used to connect the discharge outlet (c) of the liquid hydrogen storage tank 1 to the dedicated quick connector 3. The liquid hydrogen discharge outlet pipe 2, the unqualified liquid hydrogen pipe 5, and the emergency vaporizer outlet pipe 12 are all made of vacuum pipes made of stainless steel resistant to low temperatures (-253℃). The first emergency vaporizer 8 and the second emergency vaporizer 9 can be used simultaneously when the liquid hydrogen discharge volume is large, or they can serve as backups for each other when the liquid hydrogen discharge volume is small, thereby ensuring the redundancy, safety, and stability of the entire system.

[0009] The outlet of the liquid hydrogen storage tank 1 is connected to the inlet and outlet of the first emergency vaporizer 8 and the second emergency vaporizer 9, as well as the inlet and outlet of the emergency heater 13, using stainless steel welded flanges to meet the requirements for low-temperature impact resistance.

[0010] The beneficial effects of this invention are as follows: it ensures the safe and stable operation of the hydrogen liquefaction system, collecting, vaporizing, and incinerating liquid hydrogen components with substandard purity and gas-liquid mixtures released from the liquid hydrogen storage tank under overpressure; and it ensures that in the event of an accident, large quantities of liquid hydrogen can be rapidly vaporized and sent to the flare system for safe incineration and discharge. This guarantees the needs of process production, eliminates safety hazards in production, and protects the safety of equipment, operators, and related property in the liquid hydrogen system area. Attached Figure Description

[0011] Figure 1 A diagram of a safety protection device for a hydrogen liquefaction system. The device includes: 1. Liquid hydrogen storage tank; 2. Liquid hydrogen discharge outlet pipe; 3. Dedicated quick connector; 4. Defective liquid hydrogen shut-off valve; 5. Defective liquid hydrogen pipeline; 6. Front shut-off valve of the first emergency vaporizer; 7. Front shut-off valve of the second emergency vaporizer; 8. First emergency vaporizer; 9. Second emergency vaporizer; 10. Rear shut-off valve of the first emergency vaporizer; 11. Rear shut-off valve of the second emergency vaporizer; 12. Emergency vaporizer outlet pipe; 13. Emergency heater; 14. Emergency heater outlet pipe; 15. Flare system. Detailed Implementation

[0012] The present invention will be further described below with reference to the accompanying drawings and specific embodiments; it should be emphasized that the following description is not intended to limit the scope and application of the present invention.

[0013] This invention provides a safety protection device for a hydrogen liquefaction system, which is applied in the safety discharge system of a 1000L / h hydrogen liquefaction unit of a large gas technology company in China. The safety device of this invention is installed in the liquid hydrogen storage tank area, which solves the safety hazards in the operation of the unit and ensures the safe production of the liquid hydrogen system area.

[0014] according to Figure 1 As shown, the present invention mainly includes a liquid hydrogen storage tank 1, a liquid hydrogen discharge outlet pipe 2, a special quick connector 3, a non-conforming liquid hydrogen shut-off valve 4, a non-conforming liquid hydrogen pipe 5, a first emergency vaporizer front-end shut-off valve 6, a second emergency vaporizer front-end shut-off valve 7, a first emergency vaporizer 8, a second emergency vaporizer 9, a first emergency vaporizer rear-end shut-off valve 10, a second emergency vaporizer rear-end shut-off valve 11, an emergency vaporizer outlet pipe 12, an emergency heater 13, an emergency heater outlet pipe 14, and a flare system 15.

[0015] The liquid hydrogen storage tank 1 is equipped with a liquid hydrogen filling inlet a, a product purity failure outlet b, and a discharge outlet c. During normal production, the dedicated quick connector 3 is disconnected from the discharge outlet c of the liquid hydrogen storage tank 1; and liquid hydrogen with a purity of 99.9999% enters through the filling inlet a of the liquid hydrogen storage tank 1 for storage. If the purity fails the test, the discharge outlet c of the liquid hydrogen storage tank 1 needs to be connected to the dedicated quick connector 3 via a dedicated liquid hydrogen connection pipeline; the unqualified liquid hydrogen in the liquid hydrogen storage tank 1 then passes through the dedicated quick connector 3, the unqualified liquid hydrogen shut-off valve 4, the unqualified liquid hydrogen pipeline 5, the first emergency vaporizer front-end shut-off valve 6, the second emergency vaporizer front-end shut-off valve 7, the first emergency vaporizer 8, the second emergency vaporizer 9, the first emergency vaporizer rear-end shut-off valve 10, the second emergency vaporizer rear-end shut-off valve 11, the emergency vaporizer outlet pipeline 12, the emergency heater 13, the emergency heater outlet pipeline 14, and the flare system 15 for processing. The substandard liquid hydrogen components are vaporized, heated, and then incinerated in flare system 15 to ensure the process production requirements are met.

[0016] During production, the liquid hydrogen storage tank 1 may experience abnormal operating conditions such as overpressure. The liquid hydrogen gas-liquid components released due to overpressure are discharged externally through the discharge port c of the liquid hydrogen storage tank 1. These liquid hydrogen gas-liquid components are processed sequentially through the liquid hydrogen discharge outlet pipe 2, the front shut-off valve 6 of the first emergency vaporizer, the front shut-off valve 7 of the second emergency vaporizer, the first emergency vaporizer 8, the second emergency vaporizer 9, the rear shut-off valve 10 of the first emergency vaporizer, the rear shut-off valve 11 of the second emergency vaporizer, the emergency vaporizer outlet pipe 12, the emergency heater 13, the emergency heater outlet pipe 14, and the flare system 15. The overpressure-released liquid hydrogen gas-liquid components are vaporized, heated, and then incinerated in the flare system 15 to ensure stable and safe production.

[0017] The hydrogen liquefaction system is also susceptible to dangerous accidents such as fires during production. In addition to quickly shutting off the upstream liquid hydrogen quick-cut valve of liquid hydrogen storage tank 1 and implementing emergency spray measures, it is also necessary to rapidly depressurize, vaporize, and incinerate the liquid hydrogen components stored in liquid hydrogen storage tank 1. This process is carried out sequentially through components such as liquid hydrogen discharge outlet pipe 2, front-end shut-off valve 6 of the first emergency vaporizer, front-end shut-off valve 7 of the second emergency vaporizer, first emergency vaporizer 8, second emergency vaporizer 9, rear-end shut-off valve 10 of the first emergency vaporizer, rear-end shut-off valve 11 of the second emergency vaporizer, emergency vaporizer outlet pipe 12, emergency heater 13, emergency heater outlet pipe 14, and flare system 15, thereby ensuring the stability and safety of the hydrogen liquefaction system under accident conditions.

[0018] The liquid hydrogen storage tank 1 is a horizontal storage tank with an effective volume of 100 m³. 3The operating pressure is 0.6 MPa, and it adopts a high-vacuum multi-layer insulation method. The container material is low-temperature resistant stainless steel. Liquid hydrogen is a low-temperature medium with a temperature of approximately -253℃. Therefore, the liquid hydrogen discharge outlet pipe 2, the unqualified liquid hydrogen pipe 5, and the emergency vaporizer outlet pipe 12 all need to be insulated. The insulated pipes are vacuum pipes made of low-temperature resistant (-253℃) stainless steel. The first emergency vaporizer front-end shut-off valve 6, the second emergency vaporizer front-end shut-off valve 7, the first emergency vaporizer rear-end shut-off valve 10, and the second emergency vaporizer rear-end shut-off valve 11 are all low-temperature impact resistant stainless steel manual shut-off valves. The first emergency vaporizer 8 and the second emergency vaporizer 9 are vertical, with a maximum vaporization capacity of 1000 Nm³. 3 The operating pressure is 0.5 MPa, and the outlet gas temperature is >-10℃ (and must not be lower than 10℃ below the ambient temperature). If this is not possible in winter, the emergency heater 13 will start and automatically start / stop according to the ambient temperature. When two devices are used as backups for each other, the inlet / outlet valves must remain open and closed. The maximum vaporization capacity of the emergency heater 13 is 15000 Nm³. 3 The operating pressure is 0.2 MPa, the medium operating temperature is 60-70℃, and an emergency power supply must be provided to ensure that the outlet temperature is not lower than the minimum withstand temperature of the emergency heater outlet pipe 14. The flare system 15 is a plant-wide utility facility responsible for the combustion of all combustible media recovered in the plant, and the connecting pipes must slope towards the flare inlet.

[0019] The outlet of the liquid hydrogen storage tank 1 and the inlet pipes of the first emergency vaporizer 8 and the second emergency vaporizer 9 are both DN80, and the connection is made using stainless steel welding flanges; the outlet pipe diameter of the first emergency vaporizer 8 and the second emergency vaporizer 9 is DN200, and the outlet and inlet pipe diameters of the emergency heater 13 are DN250, and the connection is made using stainless steel welding flanges, which must meet the requirements for low temperature impact resistance.

[0020] The application of the safety protection device for hydrogen liquefaction systems provided by this invention solves the process requirements of low-temperature hydrogen liquefaction systems and the safety hazards under conditions such as overpressure and accidents, thus ensuring the safety of production in the station area.

[0021] Final note: The above content is only a specific implementation example of the present invention, but is not limited thereto; any similar technical solutions formed by equivalent changes or transformations based on the present invention are all protected content of the present invention and are within the protection scope of the present invention.

Claims

1. A safety protection device for a hydrogen liquefaction system, characterized in that, Includes liquid hydrogen storage tank (1), liquid hydrogen discharge outlet pipeline (2), special quick connector (3), unqualified liquid hydrogen shut-off valve (4), unqualified liquid hydrogen pipeline (5), first emergency vaporizer front shut-off valve (6), second emergency vaporizer front shut-off valve (7), first emergency vaporizer (8), second emergency vaporizer (9), first emergency vaporizer rear shut-off valve (10), second emergency vaporizer rear shut-off valve (11), emergency vaporizer outlet pipeline (12), emergency heater (13), emergency heater outlet pipeline (14), and flare system (15); The discharge port c of the liquid hydrogen storage tank (1) is connected to the liquid hydrogen discharge outlet pipe (2); the product purity non-compliance outlet b of the liquid hydrogen storage tank (1) is connected in sequence to the special quick connector (3), the non-compliance liquid hydrogen shut-off valve (4), and the non-compliance liquid hydrogen pipe (5); after the liquid hydrogen discharge outlet pipe (2) and the non-compliance liquid hydrogen pipe (5) are combined, they are split into two paths and connected to the first emergency vaporizer front-end shut-off valve (6) and the second emergency vaporizer front-end shut-off valve (7) respectively; the first emergency vaporizer front-end shut-off valve (6) and the second emergency vaporizer front-end shut-off valve (7) are connected to the first emergency vaporizer front-end shut-off valve (6) and the second emergency vaporizer front-end shut-off valve (7) respectively. The shut-off valve (7) is connected to the first emergency vaporizer (8) and the second emergency vaporizer (9) respectively, and then connected to the shut-off valve (10) at the end of the first emergency vaporizer and the shut-off valve (11) at the end of the second emergency vaporizer respectively; the shut-off valve (10) at the end of the first emergency vaporizer and the shut-off valve (11) at the end of the second emergency vaporizer are combined through the outlet pipe (12) of the emergency vaporizer and then connected to the emergency heater (13); the emergency heater (13) is connected to the flare system (15) through the outlet pipe (14) of the emergency heater. The liquid hydrogen storage tank (1) is equipped with a liquid hydrogen filling inlet a, a product purity non-compliance outlet b and a discharge outlet c; during normal production, the special quick connector (3) is disconnected from the product purity non-compliance outlet b of the liquid hydrogen storage tank (1); When the purity of the liquid hydrogen being filled is not up to standard, the liquid hydrogen storage tank (1)’s outlet b with the product purity not up to standard must be connected to the special quick connector (3) using a special liquid hydrogen connection pipe; the liquid hydrogen discharge outlet pipe (2), the unqualified liquid hydrogen pipe (5) and the emergency vaporizer outlet pipe (12) are all made of stainless steel vacuum pipes that can withstand low temperatures of -253℃; the first emergency vaporizer (8) and the second emergency vaporizer (9) are used simultaneously or as backups for each other; The connection between the outlet of the liquid hydrogen storage tank (1) and the inlet of the first emergency vaporizer (8) and the second emergency vaporizer (9) is made of stainless steel welded flange. The connection between the outlet of the first emergency vaporizer (8) and the second emergency vaporizer (9) and the inlet of the emergency heater (13) is made of stainless steel welded flange, which meets the requirements for low temperature impact resistance.

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