System and method for testing air tightness of hydrogen-doped natural gas pipeline

Abstract

The invention discloses a hydrogen-doped natural gas pipeline airtightness test system, and the system comprises a gas supply pipeline, the gas inlet end of which is communicated with a gas cylinder for storing a mixture of hydrogen and natural gas with different concentrations; the plurality of test pipelines are uniformly distributed in the constant-temperature space, the plurality of test pipelines are connected in parallel, and the air inlet ends of the plurality of test pipelines are communicated with the air supply pipeline in parallel; the gas inlet end of the bleeder is communicated with the plurality of test pipelines in parallel, and the gas outlet end of the bleeder extends to the outside of the constant-temperature space; the data acquisition and analysis system comprises a processor, and a gas concentration sensor, a pressure sensor and a temperature sensor which are in signal connection with the processor, and pressure, temperature, methane and hydrogen sensor data in a pipeline system and pressure data at the outlet of each experiment branch can be recorded in real time. Therefore, the experimental testing process can be monitored and recorded in real time, and scientific and accurate data support is provided for air tightness testing.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and in particular to a system and method for testing the air tightness of a hydrogen-blended natural gas pipeline. Background Art

[0002] With the adjustment of energy structure and the promotion of renewable energy, hydrogen, as a clean energy, has attracted more and more attention for its use in combination with natural gas. However, hydrogen molecules are small and have strong permeability, which can easily cause pipeline leakage. Therefore, in the use of hydrogen-blended natural gas, the air tightness of the pipeline must be strictly tested and controlled. However, there is currently a lack of devices on the market specifically used to test the air tightness of hydrogen-blended natural gas pipelines in different connection methods. Therefore, it is particularly important to provide a test device and method that can accurately measure the air tightness of natural gas pipelines in different connection methods under different hydrogen blending ratios. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a test system and a test method for the air tightness of a hydrogen-blended natural gas pipeline to solve the detection problem existing in the prior art.

[0004] The present invention provides a hydrogen-blended natural gas pipeline air tightness testing system, the air tightness testing system comprising:

[0005] A gas supply pipeline, the gas inlet end of which is connected to a gas cylinder storing a mixture of hydrogen and natural gas of different concentrations;

[0006] A test pipeline, wherein the test pipeline is provided in plurality and is arranged in the constant temperature space, the plurality of test pipelines are connected in parallel, and the air inlet ends of the plurality of test pipelines are connected in parallel to the air supply pipeline;

[0007] A vent pipe, the air inlet end of which is connected in parallel to a plurality of test pipelines, and the exhaust end of which extends to the outside of the constant temperature space;

[0008] The data acquisition and analysis system includes a processor, and a gas concentration sensor, a pressure sensor and a temperature sensor whose signals are connected to the processor, wherein:

[0009] Gas concentration sensors are arranged on multiple test pipelines to detect gas leakage information; pressure sensors are arranged on the exhaust end of the gas supply pipeline; and temperature sensors are arranged on the air inlet end of each test pipeline.

[0010] Preferably, the test pipeline includes: a flange test pipeline with multiple flange test positions, a threaded test pipeline with multiple threaded test positions, a ring pressure test pipeline with multiple ring pressure test positions, and a ferrule test pipeline with multiple ferrule test positions.

[0011] A method for testing a hydrogen-doped natural gas pipeline air tightness testing system comprises the following steps:

[0012] S1. Initial debugging: Connect the gas cylinder to the test pipeline, keep the gas cylinder pressure reducing valve closed, and ensure that the experimental pipeline is unobstructed;

[0013] S2. Gas replacement: Open the valves of each test pipeline and the valve of the vent pipe, then open the pressure reducing valve of the gas cylinder, control the pressure output to 3kPa, and detect the oxygen concentration at the vent port after two minutes. If the oxygen concentration is lower than 0.1%, the venting is completed and the valve at the vent pipe is closed;

[0014] S3. Pressure regulation: Control the pressure output of the pressure reducing valve at the gas cylinder to 0.2MPa, 0.01MPa, 5kPa, and 2kPa respectively, and test the air tightness of various connectors under different pressures in turn;

[0015] S4. Data recording and analysis: Use the data acquisition and analysis system to record the experimental data under each pressure setting

[0016] S5. Pressure release: Slowly release the pressure in the pipeline through the valve at the vent pipe after the experiment.

[0017] Preferably, the experimental data in S4 includes:

[0018] Pressure and temperature data at the inlet of each test pipeline;

[0019] Check the gas concentration sensor data of methane and hydrogen in a constant temperature space;

[0020] Pressure data at the outlet of each test pipeline.

[0021] The advantages of the present invention compared with the prior art are:

[0022] The present invention can accurately measure the air tightness of pipelines with different hydrogen blending ratios, different pressures and different connection methods (such as flanges, threads, ring pressures, and ferrules).

[0023] The device of the present invention is equipped with a data acquisition system, which can record the pressure, temperature, methane and hydrogen sensor data in the pipeline system and the pressure data at the outlet of each experimental branch in real time. This allows the experimental test process to be monitored and recorded in real time, providing scientific and accurate data support for airtightness testing.

[0024] The present invention adopts two different leakage calculation methods: the wrapping method and the pressure difference method:

[0025] Wrapping method: By wrapping the connector with a special sealing bag, the gas is extracted and the methane and hydrogen concentrations are tested by a gas analyzer, and the leakage amount is calculated based on the concentration changes.

[0026] Pressure difference method: The leakage is estimated by the pressure difference and flow change of the pipeline. This method indirectly calculates the leakage by testing the pressure change and is highly practical and flexible.

[0027] The test method in the present invention includes gas replacement and oxygen concentration detection steps. By controlling the gas replacement in the experiment, the oxygen concentration in the pipeline is ensured to be less than 0.1% at the beginning of the test. This ensures the accuracy of the experiment and avoids the interference of oxygen concentration on the airtightness test results.

[0028] From gas cylinder connection, gas replacement, pressure regulation to emptying after the experiment, the present invention provides a set of simplified operation procedures, making the entire test process both scientific and easy to operate, and reducing the operating difficulty of the experimenter. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 is a schematic diagram of system connection of the present invention;

[0031] Figure 2 It is a system connection schematic diagram of the flange test pipeline in the present invention;

[0032] Figure 3 It is a system connection schematic diagram of the threaded test pipeline in the present invention;

[0033] Figure 4 It is a system connection schematic diagram of the ring pressure test pipeline in the present invention;

[0034] Figure 5 It is a schematic diagram of the system connection of the ferrule test pipeline in the present invention;

[0035] As shown in the figure: 1a-flange test position; 1b-thread test position; 1c-ring pressure test position; 1d-ferrule test position; 2-sealing bag with reserved sensor interface; 3-gas concentration sensor; 4-data acquisition and analysis system; 5-vent pipe. DETAILED DESCRIPTION

[0036] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0037] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] The present invention is further described in detail below in conjunction with the accompanying drawings.

[0039] Combination Figure 1 to Figure 5 The present invention provides a hydrogen-blended natural gas pipeline air tightness testing system, the air tightness testing system comprising:

[0040] A gas supply pipeline, the gas inlet end of which is connected to a gas cylinder storing a mixture of hydrogen and natural gas of different concentrations;

[0041] A test pipeline, wherein the test pipeline is provided in plurality and is arranged in the constant temperature space, the plurality of test pipelines are connected in parallel, and the air inlet ends of the plurality of test pipelines are connected in parallel to the air supply pipeline;

[0042] A vent pipe 5, the air inlet end of which is connected in parallel to a plurality of test pipelines, and the exhaust end of which extends to the outside of the constant temperature space;

[0043] The data acquisition and analysis system 4 includes a processor, and a gas concentration sensor 3, a pressure sensor and a temperature sensor whose signals are connected to the processor, wherein:

[0044] Gas concentration sensors are arranged on multiple test pipelines to detect gas leakage information; pressure sensors are arranged on the exhaust end of the gas supply pipeline; and temperature sensors are arranged on the air inlet end of each test pipeline.

[0045] Preferably, the test pipeline includes: a flange test pipeline with multiple flange test positions 1a, a threaded test pipeline with multiple threaded test positions 1b, a ring pressure test pipeline with multiple ring pressure test positions 1c, and a ferrule test pipeline with multiple ferrule test positions 1d.

[0046] A method for testing a hydrogen-doped natural gas pipeline air tightness testing system comprises the following steps:

[0047] S1. Initial debugging: Connect the gas cylinder to the test pipeline, keep the gas cylinder pressure reducing valve closed, and ensure that the experimental pipeline is unobstructed;

[0048] S2. Gas replacement: Open the valves of each test pipeline and the valve of the vent pipe, then open the pressure reducing valve of the gas cylinder, control the pressure output to 3kPa, and detect the oxygen concentration at the vent port after two minutes. If the oxygen concentration is lower than 0.1%, the venting is completed and the valve at the vent pipe is closed;

[0049] S3. Pressure regulation: Control the pressure output of the pressure reducing valve at the gas cylinder to 0.2MPa, 0.01MPa, 5kPa, and 2kPa respectively, and test the air tightness of various connectors under different pressures in turn;

[0050] S4. Data recording and analysis: Use the data acquisition and analysis system to record the experimental data under each pressure setting

[0051] S5. Pressure release: Slowly release the pressure in the pipeline through the valve at the vent pipe after the experiment.

[0052] Preferably, the experimental data in S4 includes:

[0053] Pressure and temperature data at the inlet of each test pipeline;

[0054] Check the gas concentration sensor data of methane and hydrogen in a constant temperature space;

[0055] Pressure data at the outlet of each test pipeline.

[0056] In addition, the present invention is preferably, Figure 2-Figure 5 As shown, the flange test position, threaded test position, ring pressure test position and ferrule test position are all provided with a sealing bag 2 with a reserved sensor interface, and the sealing bag with a reserved sensor interface seals and connects the gas concentration sensor and the flange, threaded connector, ring pressure connector and ferrule connector in the corresponding test pipeline respectively.

[0057] The working principle of the present invention is:

[0058] 1. Create a constant temperature space

[0059] 1. Turn on the air conditioning device and adjust the space where the experimental test pipeline is located to a constant temperature of 25°C.

[0060] 2. Install the gas cylinder

[0061] 1. According to experimental needs, connect gas cylinders with different hydrogen blending ratios to the test pipeline.

[0062] 2. The gas cylinder valve and the pressure reducing valve connected to it remain closed and will be opened when the experiment officially begins.

[0063] 3. Test Data Acquisition System

[0064] 1. Connect the pressure gauge and thermometer of the test line and the methane and hydrogen sensor in the acrylic housing to the data acquisition system.

[0065] 2. Open the computer data acquisition software to collect pressure, temperature, methane and hydrogen concentration data.

[0066] 4. Start the experiment

[0067] 1. Open the pipeline valve, keep the test pipeline unobstructed, and keep the drain valve closed.

[0068] 2. Open the gas cylinder valve, pass the gas into the test pipeline, and start the test.

[0069] 5. Empty

[0070] 1. At the end of the experiment, close the gas cylinder valve, open the exhaust valve, and exhaust the gas in the pipeline.

[0071] 6. Data Analysis

[0072] 1. Calculate leakage using the wrapping method

[0073] Acrylic shells are used to wrap each connection to create a closed space, and a gas pump is used to extract gas from it and send it to the gas analyzer to detect the concentration of methane and hydrogen.

[0074] The product of the difference between the methane and hydrogen concentrations after the detection data reaches stability and the background methane and hydrogen concentrations and the gas flow rate is the leakage amount of hydrogen-blended natural gas.

[0075] Q g =(c-c0)·Q air

[0076] Q g —Gas leakage rate (L / min);

[0077] Q air ——Gas flow rate (L / min);

[0078] c——sample methane and hydrogen concentration (ppm);

[0079] c0——Background methane and hydrogen concentration (ppm).

[0080] 2. Calculate leakage using differential pressure method

[0081] The leakage is calculated based on the change rate of pipeline pressure difference and flow rate. Usually we can estimate the leakage by the following formula:

[0082]

[0083] in:

[0084] Q L ——m 3 / s or L / s);

[0085] Q0——Flow rate of the pipeline during leakage (m 3 / s or L / s);

[0086] ΔP——pressure difference in case of leakage (Pa);

[0087] P0——initial pressure (Pa).

[0088] The present invention and its embodiments are described above, and such description is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it, without departing from the purpose of the invention, they can design a structure and embodiment similar to the technical solution without creativity, which should belong to the protection scope of the present invention.

Claims

1. A hydrogen-blended natural gas pipeline air tightness test system, characterized by: The airtightness testing system comprises: A gas supply pipeline, the gas inlet end of which is connected to a gas cylinder storing a mixture of hydrogen and natural gas of different concentrations; A test pipeline, wherein the test pipeline is provided in plurality and is arranged in the constant temperature space, the plurality of test pipelines are connected in parallel, and the air inlet ends of the plurality of test pipelines are connected in parallel to the air supply pipeline; A vent pipe, the air inlet end of which is connected in parallel to a plurality of test pipelines, and the exhaust end of which extends to the outside of the constant temperature space; The data acquisition and analysis system includes a processor, and a gas concentration sensor, a pressure sensor and a temperature sensor whose signals are connected to the processor, wherein: The gas concentration sensor is arranged on a plurality of test pipelines to detect gas leakage information; the pressure sensor is arranged on the exhaust end of the gas supply pipeline; and the temperature sensor is arranged on the air inlet end of each test pipeline.

2. The hydrogen-blended natural gas pipeline air tightness testing system according to claim 1, characterized in that: The test pipeline includes: a flange test pipeline with multiple flange test positions, a threaded test pipeline with multiple threaded test positions, a ring pressure test pipeline with multiple ring pressure test positions, and a ferrule test pipeline with multiple ferrule test positions.

3. A method for testing the air tightness testing system for a hydrogen-blended natural gas pipeline according to claim 1, characterized in that: The following steps are involved: S1. Initial debugging: Connect the gas cylinder to the test pipeline, keep the gas cylinder pressure reducing valve closed, and ensure that the experimental pipeline is unobstructed; S2. Gas replacement: Open the valves of each test pipeline and the valve of the vent pipe, then open the pressure reducing valve of the gas cylinder, control the pressure output to 3kPa, and detect the oxygen concentration at the vent port after two minutes. If the oxygen concentration is lower than 0.1%, the venting is completed and the valve at the vent pipe is closed; S3. Pressure regulation: Control the pressure output of the pressure reducing valve at the gas cylinder to 0.2MPa, 0.01MPa, 5kPa, and 2kPa respectively, and test the air tightness of various connectors under different pressures in turn; S4. Data recording and analysis: Use the data acquisition and analysis system to record the experimental data under each pressure setting S5. Pressure release: Slowly release the pressure in the pipeline through the valve at the vent pipe after the experiment.

4. The method for testing the air tightness test system of a hydrogen-blended natural gas pipeline according to claim 3 is characterized in that: The experimental data in S4 include: Pressure and temperature data at the inlet of each test pipeline; Check the gas concentration sensor data of methane and hydrogen in a constant temperature space; Pressure data at the outlet of each test pipeline.

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