Hydrogen gas leak detection device and hydrogen gas leak detection method

Abstract

To provide a hydrogen gas leakage detection device and a leakage detection method that can easily detect hydrogen gas leakage from flanges of piping in an orifice assembly by using an orifice as a flowmeter capable of measuring a hydrogen gas flow rate under a high-pressure environment.SOLUTION: A hydrogen gas leakage detection device includes a first flange 302 in upstream-side piping of hydrogen gas piping with a predetermined diameter and a second flange 303 in downstream-side piping. An orifice plate 304 is clamped between the opposing first flange 302 and second flange 303. The device includes an orifice flowmeter unit 30 that measures a gas flow rate by measuring gas pressure on the upstream side and downstream side of the orifice plate 304. The device includes a leak port 307 that guides hydrogen gas leaking from between the first flange 302 and the second flange 303 to the outside. The device includes a hydrogen gas sensor 310 that detects the hydrogen gas guided from the leak port 307.SELECTED DRAWING: Figure 3

Description

Technical Field

[0005] ,

[0001] The present invention relates to a method for detecting leakage from a flow meter, and more particularly to a hydrogen gas leakage detection device and a leakage detection method for detecting leakage of hydrogen gas in the process of supplying hydrogen fuel to a marine engine (diesel engine).

Background Art

[0002] In Patent Document 1, hydrogen gas stored in a gas tank is compressed and stored at 100 MPa. However, when supplied to a hydrogen supply pipeline, for safety reasons, the hydrogen gas is decompressed to less than 1 MPa before being supplied. Even when the supply pipe of hydrogen gas uses a pipe with an internal pressure set to a low pressure of 0.2 MPa and thinner than a general hydrogen supply pipe, it is possible to transfer a sufficient amount of hydrogen gas required for consumption by a hydrogen-consuming device, and the flow rate at each location is measured, and leakage of hydrogen gas is detected from the inconsistency of the total sum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the technique of Patent Document 1 does not disclose a device capable of measuring the flow rate of hydrogen gas in a high-pressure environment, that is, there is a problem that there is no flow meter approved by the High-Pressure Gas Safety Act. Furthermore, when measuring the flow rate using an orifice, there is a problem that there is no method for grasping the leakage even if leakage of hydrogen gas occurs inside the flow meter.

[0005] Therefore, the object of the present invention is to provide a hydrogen gas leak detection device and a leak detection method that can easily detect hydrogen gas leakage from the flange of a pipe in an orifice assembly using an orifice as a flow meter capable of measuring the flow rate of hydrogen gas in a high-pressure environment. Furthermore, other problems of the present invention will become clear from the following description. [Means for solving the problem]

[0006] The above problems are solved by the following inventions.

[0007] 1. A hydrogen gas pipe of a predetermined diameter is provided with a first flange on the upstream pipe and a second flange on the downstream pipe. An orifice flow meter unit is provided that sandwiches an orifice plate between the opposing first flange and the second flange, and measures the gas flow rate by measuring the gas pressure on the upstream and downstream sides of the orifice plate. A leak port is provided to guide hydrogen gas leaking from between the first flange and the second flange to the outside. The system includes a hydrogen gas sensor that detects hydrogen gas induced from the aforementioned leak port, Upstream of the orifice flow meter unit, a first reducer unit is provided to expand a pipe with a smaller diameter than the hydrogen gas pipe to a pipe with the same diameter as the hydrogen gas pipe. Furthermore, downstream of the orifice flow meter unit, a second reducer unit is provided that reduces a pipe with the same diameter as the hydrogen gas pipe to a pipe with a smaller diameter than the hydrogen gas pipe. The orifice flow meter unit, the first reducer unit, and the second reducer unit constitute the orifice assembly. The first and second reducer units are flange-connected and have leak ports to guide hydrogen gas leaking from opposing flanges to the outside, and are equipped with hydrogen gas sensors to detect the hydrogen gas guided from the leak ports. A hydrogen gas leak detection device characterized by the following features. 2. Equipped with a hydrogen gas buffer tank for storing hydrogen gas, From the hydrogen gas buffer tank to the orifice assembly, a gas compressor is provided to compress the hydrogen gas and increase its pressure. The hydrogen gas is supplied to the hydrogen gas piping, characterized in that the above 1 The hydrogen gas leak detection device described. 3. The invention is characterized by comprising a tank for storing liquid hydrogen, a liquid hydrogen pump for compressing and pressurizing the liquid hydrogen, a vaporizer for gasifying the liquid hydrogen pressurized by the liquid hydrogen pump, and the high-pressure hydrogen gas gasified by the vaporizer being supplied to the hydrogen gas piping. 1 The hydrogen gas leak detection device described. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a hydrogen gas leak detection device and a leak detection method that can easily detect hydrogen gas leakage from the flange of a pipe in an orifice assembly by using an orifice as a flow meter capable of measuring the flow rate of hydrogen gas in a high-pressure environment. [Brief explanation of the drawing]

[0009] [Figure 1] A diagram illustrating a method for supplying hydrogen fuel to marine engines (diesel engines). [Figure 2] Cross-sectional view showing an example of a hydrogen gas leak detection device according to the present invention. [Figure 3] Cross-sectional view of a key part showing an example of an orifice flow meter unit according to the present invention. [Modes for carrying out the invention]

[0010] Preferred embodiments of the present invention will be described below.

[0011] Figure 1 shows a method for supplying hydrogen fuel to a marine engine (e.g., a diesel engine), Figure 2 is a cross-sectional view showing an example of a hydrogen gas leak detection device according to the present invention, and Figure 3 is a cross-sectional view of a key part showing an example of an orifice flow meter unit according to the present invention.

[0012] In this invention, for example, the hydrogen fuel supplied to a marine engine such as a diesel engine is supplied as high-pressure hydrogen gas. High-pressure hydrogen gas can be obtained from liquid hydrogen, and the process can be carried out using the following three methods. In the first method, the liquefied hydrogen stored in the liquefied hydrogen tank is evaporated by an evaporator without increasing the pressure to raise the temperature to obtain hydrogen gas. The hydrogen gas is stored in a hydrogen gas buffer tank and compressed using a gas compressor to obtain high-pressure hydrogen gas. The process of compressing the hydrogen gas by the gas compressor to increase the pressure may be performed from the hydrogen gas buffer tank to the orifice assembly. In the second method, high-pressure liquid hydrogen is obtained by using a liquid hydrogen pump that compresses the liquid hydrogen stored in the liquid hydrogen tank to increase the pressure. Next, a method of obtaining high-pressure hydrogen gas by vaporizing it in a vaporizer regardless of the temperature is mentioned. In the third method, a method is mentioned in which boil-off gas generated from the liquefied hydrogen in the liquefied hydrogen tank without passing through an evaporator is obtained, stored in a hydrogen gas buffer tank, compressed using a gas compressor, and high-pressure hydrogen gas is obtained.

[0013] The first method is shown in Fig. 1. In Fig. 1, 1 is a hydrogen gas buffer tank for storing hydrogen gas. In this form, it is sent to the hydrogen gas buffer tank 1 through an evaporator (not shown) that evaporates the liquefied hydrogen sent from a liquefied hydrogen tank (not shown) to obtain hydrogen gas. The hydrogen gas is sent from the hydrogen gas buffer tank 1 to the gas compressor 2 through the hydrogen gas pipe 10. The gas compressor 2 is preferably of a multi-stage compression type. In this embodiment, it is composed of a front-stage compressor 20 and a rear-stage compressor 21.

[0014] The front-stage compressor 20 is not particularly limited, and a configuration that compresses in any number of stages, for example, 1 to 3 stages, can be adopted. The number of compression stages is not limited to a maximum of 3 stages. In the front-stage compressor 20, for example, it is compressed in the range of 0.6 to 19 MPa.

[0015] The rear-stage compressor 21 is not particularly limited as long as it can compress to meet the required pressure of a marine engine or an internal combustion engine. It may be further compressed in 1 or 2 stages in the rear-stage compressor 21. In the rear-stage compressor 21, for example, it may be compressed to exceed 30 MPa.

[0016] The high-pressure hydrogen gas compressed by the gas compressor 2 is sent to the orifice assembly 3.

[0017] As shown in Figures 2 and 3, the orifice assembly 3 consists of an orifice flow meter unit 30, a first reducer unit 31, and a second reducer unit 32.

[0018] The first reducer unit 31 includes a reducer that expands a pipe with a smaller diameter than a predetermined diameter hydrogen gas pipe upstream of the orifice flow meter unit 30 to a pipe with the same diameter as the hydrogen gas pipe. The second reducer unit 32 also includes a reducer that reduces a pipe with the same diameter as a hydrogen gas pipe of a predetermined diameter to a pipe with a smaller diameter than the hydrogen gas pipe.

[0019] In the present invention, the orifice assembly 3 includes the orifice flow meter unit 30, the first reducer unit 31, and the second reducer unit 32 because they are flange connections, and there is a possibility of hydrogen leakage from these flanges. Therefore, it is preferable that these flanges be provided with leak ports for detecting hydrogen leaking from the flanges.

[0020] The orifice flow meter unit 30 will be described based on Figure 3. A first flange 302 and a second flange 303 are provided at the ends of the upstream pipe 300 and the downstream pipe 301 of the hydrogen gas piping. The flanges are preferably fixed to the ends of the pipes by welding.

[0021] In this embodiment, the hydrogen gas piping may be constructed as a double-walled pipe with a protective tube on its outer circumference to improve its strength. Furthermore, in addition to improving strength, the protective tube can also function to prevent hydrogen gas leaking from the inner pipe from being exposed to the atmosphere.

[0022] The orifice plate 304 is installed between flange 302 and flange 303. The thickness and diameter of the orifice are not particularly specified; it just needs to have sufficient strength to withstand high pressure.

[0023] Pressure sensing tubes 305 and 306 are attached to flanges 302 and 303, respectively. The method of attaching pressure sensing tubes 305 and 306 to flanges 302 and 303 is not particularly limited. It is preferable to select sensing tubes made of a material that can withstand gas pressure, and it is preferable to employ a sealing structure that prevents gas leakage. Pressure gauges 305A and 306A are provided at the tip ends of pressure sensing tubes 305 and 306. Pressure gauges 305A and 306A are connected to a control room (not shown) to which predetermined data is sent.

[0024] A leak port 307 is formed between the orifice plate 304 and the flange 302 to guide hydrogen gas to the outside if it leaks. This allows for immediate detection of hydrogen gas leakage from the orifice flow meter unit 30. The flange on which the leak port 307 is formed is not limited to flange 302, but may also be flange 303.

[0025] In this embodiment, the tip of the leak port 307 is open at the end face of the flange 302, and it is preferable that the flange 303 has an opening 308 for guiding the tip of the leak port 307. The opening 308 is formed in a cylindrical shape, and a part of this cylindrical shape is opened by the tip of the leak port 307, so that hydrogen gas leaking from the flange is easily guided to the leak port 307 regardless of which part of the opening 308 it leaks into. This makes it easy to guide the gas to the leak port 307 and allows for immediate detection of leaks.

[0026] As shown in Figure 3, it is preferable to provide sealing members 309A, 309B, and 309C above and below the radial opening of the tip of the leak port 307 (upper and lower perimeters). Sealing member 309A seals the space between flange 302 and orifice plate 304, and sealing member 309B seals the space between flange 303 and orifice plate 304. Sealing member 309C is provided on the outer circumference of the leak port 307 and seals the space between flanges 302 and 303. This is preferable from the viewpoint of reliably preventing hydrogen gas leakage from between flanges 302 and 303. O-rings and the like can be used as sealing members 309A, 309B, and 309C. The material is appropriately determined considering the gas pressure.

[0027] A hydrogen gas sensor 310 is provided at the tip of the leak port 307, which can detect leaking hydrogen.

[0028] To measure the hydrogen gas flow rate using the orifice plate 304, the hydrogen gas pressure on both sides of the orifice plate 304 is measured using pressure gauges 305A and 306A.

[0029] The hydrogen gas pressure at the inlet side of the orifice plate 304 is high, but the hydrogen gas pressure at the outlet side of the orifice plate 304 decreases due to pressure loss. The flow rate can be measured using a predetermined formula based on this pressure difference.

[0030] The following briefly describes the flow rate measurement method using the orifice flow meter unit 30. As shown in Figure 3, when a flow rate Q of hydrogen gas with density ρ is passed through an orifice plate, if the cross-sectional area A1 (inner diameter D), flow velocity v1, and pressure P1 before throttling are defined as follows, and the cross-sectional area A2 (inner diameter d) (orifice), flow velocity v2, and pressure P2 after throttling, the flow rate Q (cross-sectional area × flow velocity) can be calculated by the following formula (Equation 1). This enables accurate flow rate measurement under high pressure. This flow rate measurement allows for the determination of the supply amount relative to the demand of the internal combustion engine.

number

[0031] Next, we will describe the piping connection and hydrogen leak detection method using the first reducer unit 31 that constitutes the orifice assembly 3.

[0032] The first reducer unit 31 has a smaller diameter upstream pipe 311 than the hydrogen gas piping, and a downstream pipe (upstream pipe of the orifice flow meter unit) 300 with the same diameter, each end of which is provided with flanges 312 and 313. It is preferable that the flanges be fixed to the ends of the pipes by welding.

[0033] A leak port 314 is provided to detect hydrogen gas leakage from between the two flanges 312 and 313. In this embodiment, the leak port 314 is provided on flange 313, but it is not particularly limited and may also be provided on flange 312. A hydrogen gas sensor (not shown) is provided at the tip of the leak port 314.

[0034] Next, we will describe the piping connection and hydrogen leak detection method using the second reducer unit 32 that constitutes the orifice assembly 3.

[0035] The second reducer unit 32 has a downstream pipe 301 (downstream pipe of the orifice flow meter unit 30) with the same diameter as the hydrogen gas pipe, and a downstream pipe 321 with a smaller diameter, each of which is provided with flanges 322 and 323. It is preferable that the flanges be fixed to the ends of the pipes by welding.

[0036] A leak port 324 is provided to detect hydrogen gas leakage from between the two flanges 322 and 323. In this embodiment, the leak port 324 is provided on flange 322, but it is not limited to flange 323. A hydrogen gas sensor (not shown) is provided at the tip of the leak port 324.

[0037] Although embodiments of the present invention have been described above, the invention is not limited thereto. A clamp 33 may be provided before the first reducer unit 31, and a clamp 34 may be provided after the second reducer unit 32.

[0038] To prevent hydrogen gas leakage by keeping the hydrogen gas piping 10 of the orifice flow meter unit 30, the first reducer unit 31, and the second reducer unit 32 all horizontal, a suspension member 35 that supports from above to maintain a constant height and support members 36 and 37 that support from below are provided, as shown in Figure 2. This prevents rupture at the welded joints between the pipes and maintains a horizontal state. In this embodiment, clamps 33 and 34 are provided on both sides of the first reducer unit 31 and the second reducer unit 32, respectively, in order to reliably maintain a horizontal position and further prevent hydrogen gas leakage. [Explanation of symbols]

[0039] 1. Hydrogen gas buffer tank 10 Hydrogen gas piping 2 Gas compressors 20 Low-pressure side compressor 21. High-pressure side compressor 3. Orifice Assembly 30 Orifice Flow Meter Unit 300 Upstream piping 301 Downstream piping 302 Flange 303 Flange 304 Orifice Plate 305, 306 Pressure sensing tubes 305A, 306A pressure gauge 307 Leakport 308 Opening 309A, 309B, 309C sealing members 310 Hydrogen gas sensor 31. First Reducer Unit 311 Upstream piping 312, 313 Flange 314 Leakport 32. Second Reducer Unit 321 Downstream piping 322, 323 Flange 324 Leakport 33, 34 Clamp 35 Suspension member 36, 37 Support members

Claims

1. A hydrogen gas pipe of a predetermined diameter is provided with a first flange on the upstream pipe and a second flange on the downstream pipe. An orifice flow meter unit is provided that sandwiches an orifice plate between the opposing first flange and the second flange, and measures the gas flow rate by measuring the gas pressure on the upstream and downstream sides of the orifice plate. A leak port is provided to guide hydrogen gas leaking from between the first flange and the second flange to the outside. The system includes a hydrogen gas sensor that detects hydrogen gas induced from the aforementioned leak port, Upstream of the orifice flow meter unit, a first reducer unit is provided to expand a pipe with a smaller diameter than the hydrogen gas pipe to a pipe with the same diameter as the hydrogen gas pipe. Furthermore, downstream of the orifice flow meter unit, a second reducer unit is provided that reduces a pipe with the same diameter as the hydrogen gas pipe to a pipe with a smaller diameter than the hydrogen gas pipe. The orifice flow meter unit, the first reducer unit, and the second reducer unit constitute the orifice assembly. A hydrogen gas leak detection device characterized in that the first reducer unit and the second reducer unit are flange-connected, a leak port is provided to guide hydrogen gas leaking from the opposing flanges to the outside, and a hydrogen gas sensor is provided to detect the hydrogen gas guided from the leak port.

2. Equipped with a hydrogen gas buffer tank for storing hydrogen gas, From the hydrogen gas buffer tank to the orifice assembly, a gas compressor is provided to compress the hydrogen gas and increase its pressure. The hydrogen gas leak detection device according to claim 1, characterized in that high-pressure hydrogen gas is supplied to the hydrogen gas piping.

3. The hydrogen gas leak detection device according to claim 1, comprising a tank for storing liquid hydrogen, a liquid hydrogen pump for compressing liquid hydrogen to a high pressure, a vaporizer for gasifying the liquid hydrogen that has been pressurized by the liquid hydrogen pump, and the high-pressure hydrogen gas gasified by the vaporizer being supplied to the hydrogen gas piping.

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