A double-layer isobaric hydrogen storage device and pressure control method for eliminating hydrogen molecule permeation

Abstract

The application relates to a double-layer isobaric closed hydrogen storage device eliminating hydrogen molecule penetration and a pressure control method. The hydrogen storage device comprises an inner tank body and an outer tank body, the outer tank body is sealed and arranged outside the inner tank body, a closed interlayer cavity is formed between the outer wall of the inner tank body and the inner wall of the outer tank body, and the interlayer cavity is filled with a gas medium; the device further comprises a pressure detection module, a controller and a pressure adjusting assembly, the pressure detection module is used for collecting the absolute pressure of hydrogen in the tank and the absolute pressure of the interlayer gas medium in real time; the controller dynamically controls the action of the pressure adjusting assembly according to the detection signal of the detection module, so that the pressure of the gas medium in the interlayer cavity is dynamically equal to the hydrogen pressure in the inner tank body in real time, and the partial pressure difference of hydrogen molecules diffusing across the tank wall is eliminated. The application cancels a special barrier layer, realizes zero penetration and low-cost hydrogen storage.

Description

Technical Field

[0001] This invention belongs to the technical field of high-pressure hydrogen storage and hydrogen energy storage and transportation containers, specifically relating to a double-layer isobaric sealed hydrogen storage device and pressure control method for eliminating hydrogen molecule permeation. Background Technology

[0002] Hydrogen molecules have an extremely small molecular diameter (0.289 nm), making them highly susceptible to molecular permeation through metal and carbon fiber composite material walls, a core pain point in the hydrogen energy storage and transportation industry. In existing technologies, the annual permeation rate of Type IV carbon fiber hydrogen storage cylinders under normal operating conditions can reach 3%-5%, and they rely on EVOH and nylon polymer barrier layers, which are prone to aging and failure with long-term use, resulting in high costs. Existing vacuum jackets are only used for thermal insulation, and inert gas jackets are only used for post-operation leak detection; neither can eliminate partial pressure differences at the thermodynamic source. Summary of the Invention

[0003] This invention aims to provide a double-layer isobaric sealed hydrogen storage device and pressure control method to eliminate hydrogen molecule permeation, overcoming the shortcomings of existing hydrogen storage containers with high leakage rates and high barrier layer costs. It provides a double-layer isobaric gas medium barrier hydrogen storage device that eliminates the need for a dedicated barrier layer, achieving zero permeation and low-cost hydrogen storage.

[0004] To achieve the above objectives, the present invention provides a double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation, comprising an inner tank and an outer tank, wherein the outer tank is sealed outside the inner tank, and a sealed interlayer cavity is formed between the outer wall of the inner tank and the inner wall of the outer tank, the interlayer cavity being filled with a gaseous medium, wherein the gaseous medium is at least one of dry compressed air, nitrogen, or an inert gas; the device further comprises a pressure detection module, a controller, and a pressure regulating component, wherein the pressure detection module is used to collect the hydrogen pressure inside the tank and the pressure of the interlayer gaseous medium in real time; The controller is electrically connected to each component and dynamically controls the pressure regulating component to operate according to the detection signal from the detection module, so that the pressure in the interlayer cavity is dynamically equal to the hydrogen pressure inside the inner tank in real time, thereby eliminating the partial pressure difference caused by hydrogen molecules diffusing across the tank wall.

[0005] Furthermore, the pressure detection module includes a first pressure sensor and a second pressure sensor. The first pressure sensor is located at a pressure sampling point communicating with the interlayer cavity and is used to detect the pressure of the gas medium in the interlayer cavity. The second pressure sensor is located at a pressure sampling point communicating with the inner tank and hydrogen and is used to detect the hydrogen pressure in the inner tank.

[0006] Furthermore, the differential pressure of the controller is within ±0.01MPa, and the entire hydrogen storage process maintains the interlayer gas pressure and hydrogen pressure at the same value, without setting negative pressure or slightly positive pressure leak detection conditions.

[0007] Furthermore, the pressure regulating component includes an inlet valve and a pressure relief valve. The inlet valve is located on the pressure replenishment pipeline of the interlayer cavity and is used to replenish the interlayer cavity with gas medium when the pressure in the interlayer cavity is lower than the pressure in the inner tank. The pressure relief valve is located on the pressure relief pipeline of the interlayer cavity and is used to release the gas medium when the pressure in the interlayer cavity is higher than the pressure in the inner tank.

[0008] Furthermore, the inner tank is made of thin-walled metal shell or carbon fiber composite material shell, and the tank interior is not equipped with EVOH, nylon or metal-plated hydrogen barrier lining, but only relies on the interlayer isobaric gas medium barrier to block hydrogen molecule permeation.

[0009] Furthermore, the thickness of the interlayer cavity is 2mm-20mm, and the interlayer is a completely sealed, leak-free cavity, connected to an external air source only through an air supply line and a pressure relief line.

[0010] Furthermore, the inner tank is also equipped with a refrigerant coil, which is connected to an external refrigeration cycle system through a refrigerant inlet and a refrigerant outlet, and is used to regulate the temperature of hydrogen inside the inner tank.

[0011] The second technical solution of the present invention is a method for controlling hydrogen storage pressure based on the aforementioned device, comprising the following steps: S1: High-pressure hydrogen is filled into the inner tank through the hydrogen filling interface, and the second pressure sensor collects and uploads the absolute pressure data of hydrogen to the controller in real time. S2: In the initial stage, the gas medium is pre-filled into the interlayer cavity through the gas medium source. The first pressure sensor collects the absolute pressure data of the gas medium in real time and sends it to the controller. The controller adjusts the pressure of the interlayer gas medium so that the initial value of the interlayer gas medium pressure is close to the hydrogen pressure of the inner tank. S3: The controller compares the pressure data collected by the first pressure sensor and the second pressure sensor in real time. When the absolute pressure of the interlayer gas medium is lower than the absolute pressure of hydrogen and the pressure difference exceeds the threshold of 0.01MPa, the solenoid valve is opened to replenish the gas medium into the interlayer cavity. When the pressure of the interlayer gas medium is too high and the pressure difference exceeds the threshold of 0.01MPa, the interlayer pressure relief valve is opened to finely adjust the pressure relief. S4: Continuous dynamic adjustment throughout the entire process of hydrogen storage, settling, and hydrogen release, permanently maintaining the absolute pressure of the interlayer gas medium equal to the absolute pressure of the hydrogen in the inner tank, eliminating the driving force for hydrogen molecule diffusion, and achieving zero-permeability hydrogen storage.

[0012] Compared with the prior art, the present invention has the following advantages: This invention adopts a double-layer split tank structure, with a sealed interlayer filled with a gas medium. The interlayer gas medium can be dry compressed air, nitrogen, or inert gas, which users can flexibly choose according to cost, safety requirements, and operating conditions, without the need for special gas supply facilities; dual high-precision absolute pressure sensors collect pressure signals in real time; and a PLC closed-loop control system dynamically replenishes / depressurizes the interlayer, maintaining equal internal and external pressures between the interlayer and the inner tank throughout the process.

[0013] The device of this invention eliminates the expensive EVOH / nylon liner, reducing manufacturing costs by 15%-30%; the hydrogen molecule permeability approaches 0, completely solving the long-term leakage problem; it is compatible with all pressure levels of 35MPa and 70MPa, making it highly applicable. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the tank structure of the present invention.

[0015] Figure 2 This is a flowchart of the pressure control method of the present invention.

[0016] In the diagram: 1-Outer tank; 2-Inner tank; 3-Cavity; 4-Refrigerant coil; 5-Hydrogen filling port; 6-Hydrogen output port; 7-Solenoid valve; 8-First pressure sensor; 9-Air medium inlet; 10-Air medium outlet; 11-Second pressure sensor; 12-Refrigerant inlet; 13-Refrigerant outlet; 14-Temperature sensor. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 like Figure 1As shown, this embodiment is a 70MPa vehicle-mounted double-layer hydrogen storage device, which is a horizontal cylindrical double-layer tank structure. It includes an inner tank 1 and an outer tank 2. The inner layer, the hydrogen storage tank 2, is used to store high-pressure hydrogen; the outer layer, the pressure-bearing outer tank 1, provides pressure protection. A closed annular interlayer cavity 3 is formed between the inner and outer tanks. In this embodiment, dry compressed air is used as the gas medium. The area filled with diagonal lines inside the interlayer indicates the dry compressed air. A hydrogen filling port 5 and a hydrogen output port 6 are provided at the right end cap of the tank, and a pressure relief safety component is provided at the left end cap. An air medium inlet 9 and its pipeline, along with a solenoid valve 7, are provided at the top of the outer tank, and an air medium outlet 10 and its pipeline, along with a pressure relief valve, are provided at the bottom of the outer tank. The controller is located outside the tank and is connected to various sensors and actuators via electrical wiring. A refrigerant coil 4 can be optionally installed inside the inner tank, connecting to the external circulation system through a refrigerant inlet 12 and a refrigerant outlet 13. This embodiment also includes a temperature sensor 14 for monitoring the temperature inside the tank. Solid arrows indicate gas flow direction, and thin dashed lines represent electrical control signal lines.

[0019] The inner tank is equipped with a hydrogen filling interface 5, a hydrogen output interface 6, and a pressure relief safety component. The interlayer cavity is connected to an external dry compressed air source. In this embodiment, the interlayer cavity is filled with dry compressed air as a pressure barrier medium, and the interlayer medium has no explosion-proof leak detection or hydrogen enrichment and collection function. The device also includes multiple sensors for pressure monitoring, a controller, and a pressure regulating component. The pressure regulating component includes electric valve components installed on the air supply line and the pressure relief line. In this embodiment, solenoid valves 7 are used. The sensors, solenoid valves, and controller are electrically connected. The electric valves are connected in series in the pipeline to realize the isolation of the detection path.

[0020] In this embodiment, the inner tank 2 is a thin-walled shell wound with carbon fiber. The interior of the inner tank 2 is used to store high-pressure hydrogen and does not have an EVOH liner. The outer tank 1 is an aluminum alloy pressure-bearing shell, which is sealed and fitted over the outside of the inner tank 2. The outer wall of the inner tank 2 and the inner wall of the outer tank 1 together form a closed annular interlayer cavity 3 with a thickness of 5 mm.

[0021] The interlayer cavity 3 is connected to an external dry compressed air source through the air medium inlet 9, and the interlayer cavity 3 is filled only with dry compressed air as a pressure barrier medium.

[0022] Hydrogen filling port 5 and hydrogen output port 6 are located at the right end cap of the tank body, and are used for hydrogen filling and external hydrogen supply, respectively. In this embodiment, the pressure relief safety component is located on the pipeline at the left end cap of the tank body.

[0023] In this embodiment, the pressure sensors include a first pressure sensor 8 and a second pressure sensor 11. The first pressure sensor is installed at the top of the outer tank to collect the absolute pressure of the air in the interlayer in real time. The second pressure sensor is installed at the right end cap of the inner tank to collect the absolute pressure of the hydrogen gas inside the tank in real time. In this embodiment, to improve reliability, a redundant pressure sensor is installed at each end of the inner tank.

[0024] The controller in this embodiment uses a Siemens S7-1200 series programmable logic controller (PLC), which is fixedly installed in the electrical control cabinet on the outside of the outer tank (not shown in the figure). The PLC's analog input module (4-20mA signal) collects real-time data from the hydrogen absolute pressure sensor and the interlayer air absolute pressure sensor, respectively. After built-in PID calculation, the data is used to drive the opening and closing of solenoid valve 7 or the action of the interlayer pressure relief valve through the digital output module. The PLC's cyclic scanning cycle is not less than the pressure change rate, ensuring that the differential pressure control accuracy reaches ±0.01MPa. Those skilled in the art can also use a microcontroller (such as the STM32 series), DSP, or embedded industrial control computer to replace the PLC, all of which can achieve the same closed-loop control function. Such equivalent substitutions fall within the protection scope of this invention.

[0025] In this embodiment, solenoid valve 7 is installed on the air medium inlet 9 pipeline to control the supply of dry compressed air to the interlayer cavity 3. The interlayer pressure relief valve is installed on the air medium outlet 10 pipeline to fine-tune pressure relief when the interlayer pressure is too high.

[0026] In this embodiment, the differential pressure control threshold of the controller is set to 0.01 MPa. Throughout the entire process of vehicle filling, driving, and stationary operation, the controller dynamically replenishes gas to maintain the interlayer gas pressure at the same level as the 70 MPa hydrogen pressure. The annual hydrogen permeability of the tank is tested to be <0.01%.

[0027] As an optional additional structure, a refrigerant coil 4 can also be installed inside the inner tank 2 in this embodiment. It is connected to an external refrigeration cycle system through the refrigerant inlet 12 and the refrigerant outlet 13 to regulate the temperature of the hydrogen in the tank under special operating conditions, thereby further improving the safety of hydrogen storage.

[0028] Example 2 Example 2, a fixed 45MPa hydrogen storage tank for a hydrogen refueling station, has a structure largely the same as Example 1, except that it uses a double-layered steel tank: an inner stainless steel layer for hydrogen storage and an outer carbon steel layer for pressure bearing; the interlayer cavity thickness is 8mm; and an external small dry air compressor is used as the make-up air source. When the tank is stored statically for a long period, the system automatically compensates for the slight pressure loss in the interlayer air, maintaining constant pressure throughout, preventing hydrogen from seeping out, and eliminating the need for a hydrogen recovery device.

[0029] The controller uses a Mitsubishi FX series PLC, which also achieves a differential pressure control accuracy of ±0.01MPa.

[0030] Example 3 The structure is largely the same as in Example 1, except that the gas medium filled in the interlayer cavity 3 is high-purity nitrogen (purity ≥99.99%), supplied by an external nitrogen cylinder group. Nitrogen has stable chemical properties and moderate cost, making it suitable for hydrogen storage scenarios with special requirements for the oxidizing properties of the interlayer medium.

[0031] Example 4 The structure is largely the same as in Example 1, except that the gas medium filled in the interlayer cavity 3 is high-purity argon. Argon is an inert gas with a larger molecular diameter and lower diffusion coefficient than nitrogen and oxygen, and it does not react with hydrogen or the tank material at all, making it suitable for high-end hydrogen storage scenarios with the highest requirements for safety and medium stability. Argon is relatively expensive, but it can be a preferred solution under special operating conditions.

[0032] Example 5 See Figure 2 This embodiment provides a hydrogen storage pressure control method based on the aforementioned device, including the following steps: S1: High-pressure hydrogen is filled into the inner tank 2 through the hydrogen filling interface 5. The second pressure sensor collects and uploads the absolute pressure data of hydrogen to the controller in real time. S2: In the initial stage, dry air is pre-filled into the interlayer cavity 3 through a compressed air source, so that the initial value of the interlayer air pressure is close to the hydrogen pressure of the inner tank. S3: The controller compares the two pressure data collected by the first pressure sensor and the second pressure sensor in real time. When the absolute pressure of the interlayer air is lower than the absolute pressure of hydrogen and the pressure difference exceeds the threshold of 0.01MPa, the solenoid valve 7 is opened to replenish dry air into the interlayer cavity 3; when the interlayer air pressure is too high, the interlayer pressure relief valve is opened to finely adjust the pressure relief. S4: The entire process of hydrogen storage, settling, and hydrogen release is continuously and dynamically adjusted to permanently maintain the absolute pressure of the air in the interlayer equal to the absolute pressure of the hydrogen in the inner tank, eliminating the driving force for hydrogen molecule diffusion and achieving zero-permeability hydrogen storage.

[0033] Practical verification shows that the hydrogen storage device using the control method of this embodiment reduces manufacturing costs by 15%-30% after eliminating the expensive EVOH / nylon liner, and the hydrogen molecule permeability approaches 0, completely solving the long-term leakage problem and making it suitable for hydrogen storage scenarios with pressure levels of 35MPa and 70MPa.

[0034] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A double-layer isobaric sealed hydrogen storage device to eliminate hydrogen molecule permeation, characterized in that, The device includes an inner tank and an outer tank, with the outer tank sealed outside the inner tank. A sealed interlayer cavity is formed between the outer wall of the inner tank and the inner wall of the outer tank. The interlayer cavity is filled with a gaseous medium, which is at least one of dry compressed air, nitrogen, or an inert gas. The device also includes a pressure detection module, a controller, and a pressure regulating component. The pressure detection module is used to collect the hydrogen pressure inside the inner tank and the pressure of the interlayer gaseous medium in real time. The controller is located outside the outer tank and electrically connected to each component. Based on the detection signal from the detection module, it dynamically controls the pressure regulating component to make the pressure of the gas medium in the interlayer cavity equal to the hydrogen pressure inside the inner tank in real time, so as to eliminate the partial pressure difference of hydrogen molecules diffusing across the tank wall.

2. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The pressure detection module includes a first pressure sensor and a second pressure sensor. The first pressure sensor is located at a pressure sampling point connected to the outer tank and is used to detect the absolute pressure of the gas medium in the interlayer cavity. The second pressure sensor is located at a pressure sampling point connected to the hydrogen in the inner tank and is used to detect the absolute pressure of the hydrogen in the inner tank.

3. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The differential pressure of the controller is controlled within ±0.01MPa.

4. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The pressure regulating assembly includes an inlet valve and a pressure relief valve. The inlet valve is located on the pressure replenishment pipeline of the interlayer cavity and is used to replenish the interlayer cavity with gas medium when the gas pressure in the interlayer cavity is lower than the hydrogen pressure in the inner tank. The pressure relief valve is located on the pressure relief pipeline of the interlayer cavity and is used to release the gas medium when the gas pressure in the interlayer cavity is higher than the hydrogen pressure in the inner tank.

5. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The inner tank is made of thin-walled metal shell or carbon fiber composite material shell.

6. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The thickness of the interlayer cavity is 2mm-20mm.

7. The double-layer isobaric sealed hydrogen storage device for eliminating hydrogen molecule permeation according to claim 1, characterized in that, The inner tank is also equipped with a refrigerant coil, which is connected to an external refrigeration cycle system through a refrigerant inlet and a refrigerant outlet, and is used to regulate the temperature of the gas medium in the interlayer cavity and the hydrogen inside the inner tank.

8. A method for controlling hydrogen storage pressure using the apparatus described in any one of claims 1-7, characterized in that, Includes the following steps: S1, hydrogen is filled into the inner tank through the hydrogen filling inlet, and the second pressure sensor collects and uploads the absolute hydrogen pressure data to the controller in real time. S2, in the initial stage, the interlayer cavity is pre-filled with gas medium through a gas medium source, so that the initial value of the interlayer gas medium pressure is close to the hydrogen pressure of the inner tank. S3, the controller compares the pressure data of the first pressure sensor and the second pressure sensor in real time. When the absolute pressure of the gas medium in the interlayer cavity is lower than the absolute pressure of hydrogen and the pressure difference exceeds the threshold of 0.01MPa, the gas inlet valve is opened to replenish the gas medium in the interlayer cavity. When the pressure of the gas medium in the interlayer cavity is too high and the pressure difference exceeds the threshold of 0.01MPa, the interlayer pressure relief valve is opened to finely adjust the pressure relief. S4 continuously and dynamically adjusts the hydrogen storage, settling, and hydrogen release processes to maintain the absolute pressure of the gas medium in the interlayer cavity equal to the absolute pressure of the hydrogen in the inner tank.

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