CN114486543A - A test system and method for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials - Google Patents

Abstract

The invention relates to a material mechanical property testing technology, and aims to provide a system and a method for testing the influence of trace gas impurities on high-pressure hydrogen embrittlement of a material. The system comprises a gas mixing system, a test system, a gas circuit system and a computer; the gas mixing system comprises a hydrogen cylinder, a hydrogen impurity mixing gas cylinder, an argon cylinder and a mixing tank; the gas path system comprises a compressor, a recovery tank, an emptying pipeline and a vacuum pump; the test system comprises a test machine and a test environment box; the test environment box is internally provided with a heat exchange tube, and the inner surface of the box body is provided with a compact and smooth coating; the computer is connected with the systems through signal lines and is used for acquiring measurement data and sending control signals. The invention utilizes the flow meter and the flow control valve in the gas mixing system to achieve low-flow gas inlet, and then utilizes the hydrogen concentration detector and the impurity gas concentration detector to analyze the measurement of the content of each component in the mixed gas of hydrogen and impurities, thereby adjusting the content of each component in the mixed gas and realizing the accurate proportion of the mixed gas of hydrogen and impurities.

Description

A test system and method for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials

technical field

The invention belongs to the testing technology of material mechanical properties, in particular to a testing system and testing method for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials.

Background technique

"Carbon peaking, carbon neutrality" puts forward a major demand for the reform of energy consumption structure. As a clean energy source with diverse sources, convenient storage and transportation, and efficient utilization, hydrogen energy is one of the important ways to achieve the dual-carbon goal. Safe and economical transportation is one of the key links in the development of hydrogen energy. Incorporating hydrogen into the in-service natural gas pipeline network for hydrogen energy transportation is considered to be one of the potential means to realize large-scale hydrogen transportation and utilization. However, the physical and chemical properties of hydrogen-doped natural gas are special, and the hydrogen-doped natural gas has a deteriorating effect on the material properties, which may lead to premature failure of the pipeline and cause major safety accidents. Applications face serious challenges.

The above problems have attracted attention at home and abroad in recent years. The consensus is that in order to ensure the safety of hydrogen pipelines in service, it is necessary to simulate the actual high-pressure hydrogen environment or in the real hydrogen-doped natural gas environment to carry out research on the high-pressure hydrogen embrittlement mechanism of pipeline materials. Due to the limitation of test difficulty and test cost, the evolution law of material mechanical properties is mostly studied in pure hydrogen environment and nitrogen + hydrogen simulated hydrogen-doped natural gas environment at home and abroad. However, the composition of natural gas is complex. In addition to methane, it also contains a variety of trace gas impurities, such as oxygen, carbon dioxide, carbon monoxide, water, etc. Although it has been confirmed that methane has little effect on the hydrogen embrittlement of the material, the trace gas impurities contained may be harmful to the material. High pressure hydrogen embrittlement of materials has adverse effects (for example, it has been found that water vapor and hydrogen sulfide will aggravate the degree of hydrogen embrittlement of materials). Therefore, it is necessary to carry out experimental research on the influence of different gas impurities in hydrogen-doped natural gas on the high-pressure hydrogen embrittlement of the material.

In order to study the influence of different gas impurities in hydrogen-doped natural gas on the high-pressure hydrogen embrittlement of the material, the mechanical properties of the material should be tested in a test environment composed of hydrogen and single or multiple gas impurities. According to China's national standard GB/T37124-2018 "Quality Requirements for Gases Entering Long-distance Natural Gas Pipelines", the content of carbon dioxide in natural gas must not exceed 3 mol%, the content of carbon monoxide and oxygen must not exceed 0.1 mol%, and the content of hydrogen sulfide must not exceed 3 mol%. 6mg/m ³ , the total sulfur content must not exceed 20mg/m ³ , and the water dew point (corresponding to the water vapor content) should be 5°C lower than the lowest ambient temperature under delivery conditions. It can be seen that the content of impurities in the natural gas gas specified in the above standards are all low, and some even reach the ppm level, which puts forward higher requirements for the corresponding test equipment.

For impurities such as carbon monoxide, oxygen, hydrogen sulfide, etc., the traditional test device adopts partial pressure charging for the test environment box, that is, according to the partial pressure or ratio of hydrogen and impurity gas in the target test gas, the required filling rate of each gas is calculated separately. Load pressure. However, since the factory pressure of bottled impurity gas is often greater than 4MPa, in order to make the impurity gas content in the target environment reach the ppm level, it needs to be filled and diluted several times. . In addition, the test gas in the test environment box is a static gas, which is prone to gas stratification and gas leakage, which will eventually lead to the impurity gas content cannot be accurately controlled. In addition, there is currently a lack of corresponding test equipment for water vapor impurities, so the current research on the effect of water vapor on hydrogen embrittlement of materials in the industry is still blank.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and to propose a test system and method for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials.

For solving the technical problem, the solution of the present invention is:

A test system for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials is provided, including a gas mixing system, a test system, a gas circuit system, a dew point control system and a computer; wherein, the gas mixing system includes a hydrogen cylinder, a hydrogen-hybrid gas cylinder , argon cylinder and mixing tank; the gas circuit system includes a compressor, a recovery tank, a venting pipeline and a vacuum pump; the test system includes a test machine and a test environment box; a heat exchange tube is arranged inside the test environment box, and the box body The inner surface of the mixing tank has a dense and smooth resin coating; the dew point control system includes a water storage tank and a retention tank, and temperature-controlled heating equipment is provided on the periphery of the two; the outlet of the mixing tank is connected to the water storage tank through a pipeline, and the outlet of the water storage tank is connected through a pipeline. Connect the retention tank and the compressor in sequence, a pressure reducing valve is arranged on the pipeline connected to the water storage tank, the end of the access pipeline extends below the liquid level of the water storage tank, and a discharge pipeline is set above the liquid level of the water storage tank It is used to connect the retention tank; a dew point meter is set above the retention tank; the computer is connected to the aforementioned systems through signal lines to obtain measurement data and send control signals; the hydrogen cylinder, hydrogen-mixed gas cylinder, and argon cylinder The mixing tanks are respectively connected through pipelines, and the outlet of the mixing tank is also directly connected to the compressor through pipelines; the outlet of the compressor is connected to the test environment box through pipelines, and the test environment box is connected to the recovery tank through pipelines; the mixing tank, compressor, The recovery tank and the test environment box are respectively connected to the venting pipeline and the vacuum pump through pipelines; valves are respectively set on the pipelines connecting each equipment, and the interior of the mixing tank and all subsequent pipelines has a dense and smooth resin coating.

As a preferred solution, a flow meter and a flow control valve are arranged on the pipelines connected to the mixing tank, and a hydrogen concentration detector and an impurity gas concentration detector are arranged on the mixing tank.

As a preferred solution, the adjustable temperature range of the heat exchange tube inside the test environment box is -35 to 120°C.

As a preferred solution, the inflation pressure in the mixing tank and the test environment box is in the range of 0-40 MPa; the inflation pressure in the recovery tank is in the range of 0-60 MPa.

As a preferred solution, the adjustable temperature range of the temperature-controlled heating equipment of the water storage tank and the retention tank is -30 to 40°C; the inflation pressure in the water storage tank and the retention tank is in the range of 0 to 40 MPa.

The present invention further improves the test method for realizing the influence of trace gas impurities on the high-pressure hydrogen embrittlement of materials by utilizing the aforementioned test system, comprising the following steps:

(1) Start the vacuum pump, draw out the gas in the test environment box and other equipment and the connecting pipeline, and then use argon for purging and gas replacement; repeat the vacuum pumping and gas replacement operations at least twice to ensure that there are no impurities in the test system;

(2) Test for gas impurities such as oxygen and carbon monoxide: according to the ratio parameters of hydrogen and impurity gas and test requirements, calculate the respective pressure values of hydrogen and hydrogen-mixed gas; open the hydrogen bottle valve and flow control valve, and adjust the flow rate. The counting number is controlled within the range required by the test, and the hydrogen is input into the mixing tank until the pressure reaches the calculated pressure value; in the same way, the gas in the hydrogen-mixed gas cylinder is input into the mixing tank; the hydrogen concentration detector and the impurity gas concentration The detector analyzes the content of each component of the mixed gas in the mixing tank and adjusts it until the mixture ratio of hydrogen and impurity gas meets the test requirements;

Test for water vapor impurities: use temperature-controlled heating equipment to control the temperature of the water storage tank and the retention tank to meet the test requirements, and then input the mixed gas from the mixing tank to the water storage tank; control the charging and discharging rate of the mixed gas through the pressure reducing valve to make the storage tank The saturated vapor pressure at the test temperature is maintained in the water tank. After the mixed gas and water vapor are mixed evenly, they are sent to the retention tank; It is transported to the compressor, and after being pressurized by the compressor, it is transported to the test environment box for testing;

(3) Use the heat exchange tube to maintain the temperature of the test environment box to meet the test requirements, and continuously input the pressurized mixed gas into the test environment box through the compressor to keep the gas flow in the box; the excess gas is recycled to the recovery tank to achieve After the discharge requirements, it is released through the venting pipeline; under the condition of flowing gas, the mechanical properties of the material are tested by the testing machine to evaluate the influence of water vapor and impurity gas on the high-pressure hydrogen embrittlement of the material;

(4) After the material mechanical properties test, open the valve between each equipment and the venting pipeline, and empty the equipment through the venting valve; The impurity gas adsorbed on the inner surface of the box is all desorbed; finally, the vacuum pump is started to evacuate the equipment until the vacuum degree reaches the test requirements; at this point, the entire test process is over.

As a preferred solution, in the step (2), according to 10-10,000 times the content of the trace impurity gas required by the test, hydrogen and impurity gas are pre-filled into the hydrogen-mixed gas cylinder; The calculation method of the pressure value is as follows: Assume that the gas environment required for the test is hydrogen with a total gas pressure of P MPa and n ppm X gas impurities, and the pre-prepared hydrogen-mixed gas is hydrogen with a total gas pressure of Q MPa and a ppm X gas. Impurities, the pre-prepared hydrogen-mixed gas cylinder should output the pressure value of n/a × Q MPa, and the hydrogen cylinder should output the pressure value of p-n/a × QMPa.

Compared with the prior art, the beneficial effects of the present invention are:

1. In the traditional impurity gas test method, it is necessary to directly charge hydrogen and impurity gas into the environmental box according to the partial pressure and multiple dilution methods at the test site, and the environmental box is static gas, which is easy to cause gas stratification , The error of impurity gas content is large, and it is impossible to carry out material test research in a gas environment where a very small amount of impurity gas is mixed with hydrogen.

Different from the prior art, the present invention integrates a variety of technical means, including the proportion of hydrogen gas and the trace impurity gas to be studied before the test according to the test requirements, the flow of the mixed gas into the test environment box, the test environment box and the pipeline. The inner surface is made of resin coating, and the inside of the test environment box is equipped with a heat exchange tube to desorb the impurity gas by heating and baking, so as to ensure that the impurity content in the mixed gas of the test environment box is accurately controlled within the test requirements, and the test results are guaranteed. accuracy. Based on the method of the present invention, the impurity content in the final test mixed gas can be as low as 1 ppm.

2. The dew point control system in the present invention can realize the research of water vapor impurities, filling the gap of related devices and research in the industry. In addition, the gas mixing system and the dew point control system in the present invention are independent of each other, and the gas mixing system can mix a variety of impurity gases at the same time. It is necessary to study the influence of a certain impurity gas on the high-pressure hydrogen embrittlement of the material separately, or a certain impurity gas can be studied separately. The coupling effect of various impurity gases and water on high-pressure hydrogen embrittlement of materials can also be studied.

Description of drawings

FIG. 1 is a schematic diagram of the overall system of the present invention.

In the figure: hydrogen cylinder 1, hydrogen-mixed gas cylinder 2, flow meter 3, argon cylinder 4, flow control valve 5, hydrogen concentration detector 6, impurity gas concentration detector 7, mixing tank 8, compressor 9, A vent valve 10, vent line 11, vacuum pump 12, testing machine 13, test environment box 14, second vent valve 15, recovery tank 16, computer 17, dew point meter 18, retention tank 19, temperature control heating equipment 20, Water storage tank 21 , pressure reducing valve 22 , heat exchange tube 23 .

Fig. 2 is the comparison result of the content error of impurity gas of the present invention and the traditional partial pressure method.

FIG. 3 is a comparison of the fatigue life test results of materials in a hydrogen environment with water vapor using the present invention and the results in a traditional anhydrous environment.

Detailed ways

The test system for the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials described in the present invention includes a gas mixing system, a test system, a gas circuit system, a dew point control system and a computer; wherein, the gas mixing system includes a hydrogen bottle 1, a hydrogen-hybrid gas mixture Bottle 2 (abbreviation for hydrogen and impurity gas mixed gas bottle), argon gas bottle 4 and mixing tank 8; the gas circuit system includes a compressor 9, a recovery tank 16, a venting pipeline 11 and a vacuum pump 12; the test system includes a test machine 13 and the test environment box 14; the heat exchange tube 23 is arranged inside the test environment box 14, and the inner surface of the box body has a dense and smooth resin coating; the dew point control system includes a water storage tank 21 and a retention tank 19, and a temperature The outlet of the mixing tank 8 is connected to the water storage tank 21 through a pipeline, and the outlet of the water storage tank 21 is connected to the retention tank 19 and the compressor 9 in turn through a pipeline, and a pressure reducing valve 22 is provided on the pipeline connected to the water storage tank 21. , the end of the access pipeline extends below the liquid level of the water storage tank 21, and a discharge pipeline is arranged above the liquid level of the water storage tank 21 for connecting the retention tank 19; the dew point meter 18 is set above the retention tank 19; the computer 17 Connect the aforementioned systems through signal lines for acquiring measurement data and sending control signals. The hydrogen cylinder 1, the hydrogen-mixed gas cylinder 2, and the argon cylinder 4 are respectively connected to the mixing tank 8 through pipelines, and the outlet of the mixing tank 8 is also directly connected to the compressor 9 through pipelines. The outlet of the compressor 9 is connected to the test environment box 14 through pipelines, and the test environment box 14 is connected to the recovery tank 16 through pipelines; the mixing tank 8, the compressor 9, the recovery tank 16 and the test environment box 14 are respectively connected to the vent pipes through pipelines circuit 11 and vacuum pump 12. Valves are respectively provided on the pipelines connecting each equipment, flow meters 3 and flow control valves 5 are provided on the pipelines connected to the mixing tank 8 , and hydrogen concentration detectors 6 and impurity gas concentration detectors are arranged on the mixing tank 8 7. The inside of the mixing tank 8 and all the pipelines following it has a dense and smooth resin coating.

The test method for realizing the influence of trace gas impurities on high-pressure hydrogen embrittlement of materials by using the test system includes the following steps:

(1) Start the vacuum pump 12, draw out the gas in the test environment box 14 and other equipment and the connecting pipeline, and then use argon for purging and gas replacement; repeat the vacuum pumping and gas replacement operations at least twice to ensure that there is no gas in the test system. impurities;

(2) Test for gas impurities such as oxygen and carbon monoxide: According to the ratio parameters of hydrogen and impurity gas and the test needs, calculate the respective pressure values of hydrogen and hydrogen-mixed gas; 10,000 times, and fill hydrogen and impurity gas into hydrogen-mixed gas cylinder 2 in advance. The calculation method of the pressure value of each component in the mixed gas is as follows: Assuming that the gas environment required for the test is hydrogen with a total gas pressure of P MPa and n ppmX gas impurities, and the pre-prepared mixed gas of hydrogen and impurity gas is a gas with a total gas pressure of QMPa If the hydrogen and a ppm X gas impurities are present, the pre-prepared hydrogen-mixed gas cylinder 2 should output a pressure value of n/a×Q MPa, and the hydrogen cylinder should output a pressure value of p-n/a×Q MPa. Open the valve of the hydrogen bottle 1 and the flow control valve 5, control the indication of the flow meter 3 within the range required by the test, and input the hydrogen into the mixing tank 8 until the pressure reaches the calculated pressure value; The gas in the bottle is input into the mixing tank 8; the content of each component of the mixed gas in the mixing tank 8 is analyzed by the hydrogen concentration detector 6 and the impurity gas concentration detector 7 and adjusted until the ratio of the hydrogen and the impurity gas mixed gas meets the test Require;

After completing the above steps, proceed as follows to test for water vapor impurities:

Use the temperature control heating device 20 to control the temperature of the water storage tank 21 and the retention tank 19 to meet the test requirements, and then input the mixed gas from the mixing tank 8 into the water storage tank 21; Maintain the saturated vapor pressure at the test temperature in 21, and transfer the mixed gas to the retention tank 19 after the mixed gas and water vapor are evenly mixed; measure the water dew point of the mixed gas mixed with water vapor by the dew point meter on the retention tank 19, which meets the test requirements Then, it is transported to the compressor 9, and after being pressurized by the compressor 9, it is transported to the test environment box 14 for testing;

(3) The heat exchange tube 23 is used to maintain the temperature of the test environment box 14 to meet the test requirements, and the pressurized mixed gas is continuously input into the test environment box 14 through the compressor 9 to keep the gas flow in the box; excess gas is recovered To the recovery tank 16, after meeting the discharge requirements, it is released through the venting pipeline 11; under the condition of flowing gas, the mechanical properties of the material are tested by the testing machine 13 to evaluate the influence of water vapor and impurity gas on the high-pressure hydrogen embrittlement of the material;

(4) After the material mechanical properties test, open the valve between each device and the venting pipeline 11, and empty the device through the venting valve; then use the heat exchange tube to maintain the temperature of the test environment box 14 at 120°C and keep it for 30 minutes , so that all the impurity gases adsorbed on the inner surface of the environmental box are desorbed; finally, the vacuum pump 12 is started to evacuate each equipment until the vacuum degree reaches the test requirements; at this point, the entire test process is over.

A more detailed description of the content of the embodiment is as follows:

As shown in FIG. 1 , the test system in this embodiment includes a hydrogen cylinder 1 for providing the test, a hydrogen and impurity gas mixture cylinder 2 for providing the impurity gas for the test, an argon cylinder 4 for purging, and a hydrogen cylinder 1 , hydrogen and impurity gas mixed gas cylinder 2, the exhaust port of argon gas cylinder 4 is connected to the mixing tank 8, a flow meter 3 and a flow control valve 5 are set on the above pipelines. The discharge port of the mixing tank 8 is divided into two paths: one is connected to the compressor 9, and then is the test environment box 14. The exhaust port of the test environment box 14 is connected to the recovery tank 16, and the above-mentioned test environment box 14 is provided with a heat exchange tube 23 inside. , and the inner surface has a dense and smooth resin coating; all the way is connected to the water storage tank 21, and then is the retention tank 19, the outlet of the retention tank 19 is connected to the compressor 9, and is incorporated into the pipeline connected to the compressor 9, the above-mentioned water storage tank 21 and the retention tank 19 are equipped with temperature-controlled heating equipment 20, and a pressure reducing valve 22 is provided on the pipeline connecting the mixing tank 8 and the water storage tank 21. A hydrogen concentration detector 6 and an impurity gas concentration detector 7 are arranged on the mixing tank, and a dew point instrument 18 is arranged on the retention tank. The hydrogen concentration detector 6, the impurity gas concentration detector 7 and the dew point instrument 18 can be used to measure hydrogen, impurity gas and water. The content of each component in the steam mixed gas is adjusted, and the content ratio of each component in the mixed gas is adjusted to realize the precise proportioning of hydrogen, impurity gas and water vapor mixed gas. The top of the recovery tank 16 is connected to the second vent valve 15 and the vent line 11 through pipelines, and the gas in the recovery tank can be directly vented; the vent line 11 is also connected to the first vent valve 10, vacuum pump 12, mixing tank 8 , retention tank 19 and test environment box 14, can directly carry out argon purging mixing tank 8, retention tank 19 and test environment box 14, so as to achieve the purpose of gas replacement; start vacuum pump 12, can mix tank 8, retention tank 19 Vacuuming with the test environment box 14, repeated vacuuming and argon purging can ensure that there are no other impurities in the test system that may affect the accuracy of the test results. The test machine 13 equipped with the test environment box 14 can test the mechanical properties of the material in the test gas environment. The mixing tank 8, the water storage tank 21, the retention tank 19, the testing machine 13, the compressor 9, the recovery tank 16 and the vacuum pump 12 are respectively connected to the computer 17 through signal lines. The inside of the mixing tank 8 and all the pipelines following it has a dense and smooth resin coating.

The method for testing the influence of gas impurities in hydrogen-doped natural gas on high-pressure hydrogen embrittlement of materials using the aforementioned test system includes the following steps:

(1) Start the vacuum pump 12, after the gas in the test environment box 14, the mixing tank 8, the water storage tank 21, and the retention tank 19 is drawn out, the test environment box 14, the mixing tank 8, The water storage tank 21, the retention tank 19 and their connecting pipelines are purged and replaced with gas; the above-mentioned vacuuming and gas replacement processes are repeated at least twice to ensure that there is no other excess gas in the test system;

(2) According to the ratio parameters of hydrogen and impurity gas and the test needs, calculate the required pressure values of hydrogen and hydrogen-mixed gas respectively. The specific calculation method is as follows: Assume that the gas environment required for the test is hydrogen with a total gas pressure of P MPa and n ppm X gas impurities, the pre-prepared mixed gas of hydrogen and impurity gas is hydrogen gas with a total gas pressure of QMPa and appm X gas impurities, then the pre-prepared hydrogen-mixed gas cylinder 2 should output the pressure value n during the test /a×Q MPa, the pressure value that the hydrogen cylinder 1 should output is p-n/a×Q MPa. For example, the gas environment required for the test is a mixed gas environment with a total pressure of 5MPa, hydrogen and 10ppm carbon dioxide, then the hydrogen gas with a total gas pressure of 5MPa and 100ppm impurity gas can be mixed into the hydrogen-mixed gas cylinder 2 before the test. During the test, input 0.5MPa hydrogen mixed gas and 4.5MPa hydrogen into the mixing tank 8. Open the hydrogen bottle 1 and the flow control valve 5 connected to it, control the indication of the flow meter 3 within the test range, and input hydrogen into the mixing tank 8 until the hydrogen pressure in the mixing tank 8 meets the test requirements; The process that the gas in the prepared hydrogen-miscellaneous mixed gas cylinder 2 is input into the mixing tank 8 is the same as hydrogen; the hydrogen concentration detector 6 and the impurity gas concentration detector 7 provided on the mixing tank 8 analyze and measure each of the hydrogen and the impurity gas mixed gas. Component content, and then adjust the content ratio of each component in the mixed gas to achieve an accurate ratio of hydrogen and impurity gas mixed gas;

(3) Use the temperature control heating device 20 to control the temperature of the water storage tank 21 to the temperature required for the test, and the retention tank 19 is operated in the same way, and then the mixed gas of hydrogen and impurity gas is input into the water storage tank 21, so that the gas in the water storage tank 21 is maintained at The saturated vapor pressure at this temperature, the mixed gas of hydrogen and impurity gas and water vapor are evenly mixed and input into the retention tank 19, and the water dew point of the hydrogen, impurity gas and water vapor mixed gas is measured by the dew point meter 18 on the retention tank 19 , and proceed to the next step after reaching the test requirements; a pressure reducing valve 22 is provided in the connecting pipeline of the water storage tank 21 and the mixing tank 8 to control the charging and discharging rate of the mixed gas of hydrogen and impurity gas;

(4) Using the heat exchange tube 23, the temperature of the test environment box 14 is maintained under the test requirements, and then the hydrogen, impurity gas and water vapor mixed gas is input into the test environment box 14, and the pressure is increased by the compressor 9 to the test requirements. , keep (2) (3) step operation, keep the gas in the test environment box 14 flowing, the excess gas is recovered to the recovery tank 16, after the gas in the recovery tank 16 reaches the discharge requirement, open the second vent valve 15 connected to it. , release the gas through the venting pipeline 11; at the same time, use the testing machine 13 to test the mechanical properties of the material to evaluate the effect of water vapor and impurity gas on the high-pressure hydrogen embrittlement of the material;

(5) After the material mechanical properties test is completed, open the test environment box 14 , the mixing tank 8 , the water storage tank 21 , the retention tank 19 and the valve on the connecting pipeline 11 and the first vent valve 10 , and vent the test environment box 14 , the gas in the mixing tank 8, the water storage tank 21, and the retention tank 19; then the target temperature of the heat exchange tube 23 is set to 120 ° C, and kept for 30 minutes, to bake the test environment box 14 to make all the impurity gases adsorbed on the inner surface are removed. Attached, finally start the vacuum pump 12, open the valves on the connecting pipeline of the test environment box 14, the mixing tank 8, the water storage tank 21, the retention tank 19 and the vacuum pump 12. After vacuuming, the vacuum degree can be stopped when the degree of vacuum reaches the test requirements. At this point, the whole test process is over.

As mentioned above, various methods are used to ensure that the impurity content in the mixed gas of the test environment box is accurately controlled within the test requirements, and the accuracy of the test results is ensured, including: ① small flow intake through flowmeter and flow control valve; ② Use the hydrogen concentration detector and the impurity gas concentration detector to analyze the measurement of the content of each component in the hydrogen and impurity mixed gas, and then adjust the content of each component in the mixed gas; The impurity gas and water vapor are mixed with gas, and the excess gas is input into the recovery tank; ④The interior of the mixing tank and all subsequent pipelines has a dense and smooth resin coating, so that the gas is not easy to adhere to the inner surface of the pipeline; ⑤The inner surface of the test environment box It has a dense and smooth resin coating, so that the gas is not easy to adhere to the inner surface of the test environment box, and the test environment box is equipped with a heat exchange tube to heat and desorb the impurity gas adsorbed on the inner surface to achieve double protection; ⑥ Before the test, according to the test needs The ratio of hydrogen and a small amount of impurity gas is carried out, and then mixed with high-pressure hydrogen during the test, which can further dilute the impurity gas, and can build a gas environment in which a very small amount of impurity gas and hydrogen is mixed. Compared with the traditional test method in which hydrogen and impurity gas are directly charged into the environmental box by partial pressure and multiple dilution methods, and the environmental box is static gas, the accuracy of the impurity gas content in the present invention is greatly improved. The specific comparison is shown in Figure 2.

The main components of natural gas are alkanes, of which methane accounts for the vast majority, and a small amount of ethane, propane and butane, in addition to oxygen, hydrogen sulfide, carbon dioxide, nitrogen and water vapor, and a small amount of carbon monoxide and traces of rare gases such as helium. and Argon etc. The specific gravity is about 0.65, which is lighter than air, and has the characteristics of colorless, odorless and non-toxic. Since alkanes such as methane have been confirmed to have no effect on material properties, this application focuses on the impact of impurities (oxygen, carbon dioxide, carbon monoxide, water, etc.) in natural gas on material properties. gases such as carbon dioxide.

In actual operation, the hydrogen gas and the trace impurity gas to be studied are mixed according to the test requirements before the test, and the content of the mixed impurity gas can be selected in the range of 100% to 100ppm. During the test, after mixing with high-pressure hydrogen, the final test is used. The minimum impurity content in the mixed gas can reach 1ppm, which can realize material test research in a gas environment where a very small amount of impurity gas is mixed with hydrogen; the operating pressure of the pipeline is generally lower than 20MPa, and the temperature range is generally -20~35℃. Covering the service conditions and test safety of the pipeline, the inflation pressure in the mixing tank, the water storage tank, the retention tank and the test environment box is in the range of 0 to 40MPa, and the inflation pressure in the recovery tank is in the range of 0 to 60MPa. The adjustable temperature range of the temperature-controlled heating equipment is -30 to 40 °C, and the adjustable temperature range of the heat exchange tube in the test environment box is -35 to 120 °C.

The dew point control system in the present invention can realize water vapor impurity research. According to the research of the present invention, it is found that water vapor has a great influence on the hydrogen embrittlement of the material, and the specific results are shown in Figure 3. In addition, during the test, the gas mixing system and the dew point control system are independent of each other, and the gas mixing system can mix a variety of impurity gases at the same time. The influence of a certain impurity gas on the high-pressure hydrogen embrittlement of the material can be studied separately according to the needs of the test. The coupling effect of a certain impurity gas and water on the high-pressure hydrogen embrittlement of the material can also be studied.

The above is only an example of the implementation of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with a preferred implementation example, it is not intended to limit the present invention. , without departing from the scope of the technical solution of the present invention, when certain changes or modifications can be made by using the structure and technical content disclosed above, it becomes an equivalent implementation case of equivalent changes.

Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solutions of the present invention still fall within the scope of the technical solutions of the present invention.

Claims (7)

1. A system for testing the influence of trace gas impurities on high-pressure hydrogen embrittlement of a material is characterized by comprising a gas mixing system, a test system, a gas circuit system, a dew point control system and a computer; wherein,

the gas mixing system comprises a hydrogen cylinder, a hydrogen impurity mixing gas cylinder, an argon cylinder and a mixing tank;

the gas path system comprises a compressor, a recovery tank, an emptying pipeline and a vacuum pump;

the test system comprises a tester and a test environment box; the test environment box is internally provided with a heat exchange tube, and the inner surface of the box body is provided with a compact and smooth resin coating;

the dew point control system comprises a water storage tank and a detention tank, and temperature control heating equipment is arranged on the peripheries of the water storage tank and the detention tank; the outlet of the mixing tank is connected with a water storage tank through a pipeline, the outlet of the water storage tank is sequentially connected with a detention tank and a compressor through pipelines, a pressure reducing valve is arranged on a pipeline connected into the water storage tank, the end part of the connected pipeline extends to the position below the liquid level of the water storage tank, and a discharge pipeline is arranged above the liquid level of the water storage tank and is used for connecting the detention tank; a dew point meter is arranged above the detention tank;

the computer is connected with the systems through signal lines and is used for acquiring measurement data and sending control signals;

the hydrogen cylinder, the hydrogen impurity mixed gas cylinder and the argon gas cylinder are respectively connected with the mixing tank through pipelines, and the outlet of the mixing tank is also directly connected with the compressor through a pipeline; the outlet of the compressor is connected with a test environment box through a pipeline, and the test environment box is connected with a recovery tank through a pipeline; the mixing tank, the compressor, the recovery tank and the test environment box are respectively connected with an emptying pipeline and a vacuum pump through pipelines; valves are respectively arranged on pipelines connecting all the devices, and dense and smooth resin coatings are arranged in the mixing tank and all the pipelines behind the mixing tank.

2. The test system of claim 1, wherein a flow meter and a flow control valve are arranged on each pipeline connected to the mixing tank, and a hydrogen concentration detector and an impurity gas concentration detector are arranged on the mixing tank.

3. The test system as claimed in claim 1, wherein the adjustable temperature range of the heat exchange tube inside the test environment box is-35-120 ℃.

4. The test system of claim 1, wherein the aeration pressure in the mixing tank and test environment chamber is in the range of 0 to 40 MPa; the inflation pressure range in the recovery tank is 0-60 MPa.

5. The test system of claim 5, wherein the adjustable temperature range of the temperature controlled heating equipment of the water storage tank and the detention tank is-30-40 ℃; the inflation pressure range in the water storage tank and the detention tank is 0-40 MPa.

6. The method for testing the influence of trace gas impurities on the high-pressure hydrogen embrittlement of a material by using the test system of any one of claims 1 to 5 is characterized by comprising the following steps:

(1) starting a vacuum pump, pumping out gas in equipment such as a test environment box and the like and a connecting pipeline, and then purging and gas replacement by using argon; the operations of vacuumizing and gas replacement are repeated for at least 2 times, so that no impurities exist in the test system;

(2) the test is carried out on gas impurities such as oxygen, carbon monoxide and the like: respectively calculating the pressure values required by the hydrogen and the hydrogen mixed gas according to the proportioning parameters of the hydrogen and the impurity gas and the test requirements; opening a hydrogen cylinder valve and a flow control valve, controlling the reading of a flow meter within a test requirement range, and inputting hydrogen into a mixing tank until the pressure reaches a calculated pressure value; in the same way, the gas in the hydrogen-mixed gas cylinder is input into the mixing tank; analyzing the content of each component of the mixed gas in the mixing tank through a hydrogen concentration detector and an impurity gas concentration detector, and adjusting until the ratio of the hydrogen to the impurity gas mixed gas meets the test requirements;

tests were carried out for water vapour impurities: controlling the temperature of the water storage tank and the detention tank to meet the test requirements by using temperature control heating equipment, and then inputting mixed gas into the water storage tank from the mixing tank; controlling the charging and discharging rate of the mixed gas through a pressure reducing valve to maintain the saturated vapor pressure in the water storage tank at the test temperature, and conveying the mixed gas and the vapor to a detention tank after the mixed gas and the vapor are uniformly mixed; measuring the water dew point of the mixed gas mixed with water vapor by a dew point meter on the retention tank, conveying the mixed gas to a compressor after meeting the test requirement, and conveying the mixed gas into a test environment box for a test after the mixed gas is pressurized by the compressor;

(3) the temperature of the test environment box is maintained to meet the test requirements by using the heat exchange tube, and the pressurized mixed gas is continuously input into the test environment box through the compressor to keep the gas in the box flowing; the redundant gas is recycled to the recycling tank and released through the emptying pipeline after the discharge requirement is met; under the condition of flowing gas, a testing machine is utilized to test the mechanical properties of the material, and the influence of water vapor and impurity gas on the high-pressure hydrogen embrittlement of the material is evaluated;

(4) after the mechanical property test of the material is finished, opening valves between each device and an emptying pipeline, and emptying the devices through emptying valves; then, maintaining the temperature of the test environment box at 120 ℃ for 30 minutes by using a heat exchange tube, so that all impurity gases adsorbed on the inner surface of the environment box are desorbed; finally, starting a vacuum pump to vacuumize each device until the vacuum degree meets the test requirement; the entire testing process is now complete.

7. The method as claimed in claim 6, wherein in the step (2), the hydrogen gas and the impurity gas are filled into the hydrogen-impurity mixed gas cylinder in advance according to 10-10000 times of the content of the trace impurity gas required by the test; the pressure value calculation method of each component in the mixed gas is as follows: assuming that the gas environment required by the test is hydrogen with total gas pressure of P MPa and n ppm X gas impurities, and the pre-prepared hydrogen mixed gas is hydrogen with total gas pressure of Q MPa and a ppm X gas impurities, the pressure value which should be output by the pre-prepared hydrogen mixed gas cylinder during the test is n/a multiplied by Q MPa, and the pressure value which should be output by the hydrogen cylinder is P-n/a multiplied by Q MPa.

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