Method for evaluating adaptability of nonmetal sealing material of hydrogen-doped conveying natural gas pipeline

Abstract

The invention relates to the field of performance test and evaluation of non-metallic materials, and discloses an adaptability evaluation method for a non-metallic sealing material of a hydrogen-doped conveying natural gas pipeline, which comprises the following steps of: simulating hydrogen-free and hydrogen-containing environments by adopting a high-temperature and high-pressure reaction kettle to obtain a corresponding aging performance adaptability score S aging; fixing a second non-metal sealing material test piece group subjected to an anti-explosion performance test in a high-temperature and high-pressure reaction kettle, repeatedly pressurizing, maintaining and releasing the pressure to a specified period number, and then observing the second non-metal sealing material test pieces to obtain a corresponding anti-explosion performance adaptability score S anti-explosion; and arranging the third non-metal sealing material test piece group subjected to the permeability test in a closed space to obtain a corresponding permeability adaptability score S permeability. According to the invention, a systematicness and integrity evaluation method, the safety level and the critical safety working condition are established, and the adaptability of the nonmetal sealing material under the natural gas pipeline hydrogen-doped conveying condition is determined.

Description

Technical Field

[0001] The present invention relates to the field of performance testing and evaluation of non-metallic materials, and particularly relates to a method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen-doped transportation. Background Art

[0002] Hydrogen energy is one of the development directions of new energy and an important way to reduce carbon emissions. Hydrogen energy storage and transportation is a key technology for the large-scale application of hydrogen energy. Among them, the transportation of hydrogen-doped natural gas pipelines shows good economy in long-distance hydrogen transportation. Existing research shows that when the transportation distance exceeds 1000 km, the cost of transporting hydrogen-doped natural gas pipelines is lower than the cost of power transmission. The transportation of hydrogen-doped natural gas pipelines has broad application prospects. At present, the Netherlands has successfully added 20% hydrogen by volume to natural gas. However, during the hydrogen-doped transportation process, hydrogen will enter the internal parts of materials such as pipelines, valves, flanges, instruments, and seals, causing varying degrees of damage to the performance of pipeline materials. Non-metallic sealing materials are an important part of natural gas pipelines. The performance of non-metallic sealing materials mainly includes aging performance, explosion resistance performance, and gas permeability performance. At present, the evaluation of the adaptability of non-metallic sealing materials in hydrogen-doped transportation pipelines is still in its infancy, and there is still a lack of systematic and comprehensive research on the influence law of hydrogen-doped transportation on the performance of non-metallic sealing materials in pipelines; evaluating the hydrogen-doped adaptability of non-metallic sealing materials in pipelines through a single performance test method, the results are not representative and cannot ensure the safe operation of hydrogen-doped transportation pipelines; the safety level division of the evaluation results of the adaptability of non-metallic sealing materials in hydrogen-doped transportation pipelines is not clear. Therefore, it is urgent to develop a reasonable and effective evaluation method for the adaptability of non-metallic sealing materials in hydrogen-doped transportation pipelines, systematically and comprehensively evaluate the influence law of hydrogen-doped transportation on the performance of non-metallic sealing materials in pipelines, so as to obtain the adaptability level evaluation results of non-metallic sealing materials in hydrogen-doped transportation pipelines, and obtain the critical safety operating conditions of hydrogen-doped transportation, providing an important reference for the hydrogen-doped transportation project of pipelines.. Summary of the Invention

[0003] The present invention provides a method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen-doped transportation, establishes a systematic and comprehensive evaluation method, safety level, and critical safety operating conditions, determines the adaptability of non-metallic sealing materials under the conditions of hydrogen-doped transportation of natural gas pipelines, and promotes the implementation of the hydrogen-doped project of natural gas pipelines.

[0004] The present invention is realized through the following technical solutions:

[0005] A method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen-doped transportation includes:

[0006] The high-temperature and high-pressure reactor is used to simulate the on-site conditions of the pipeline, including temperature, pressure and gas components. The first non-metallic sealing material specimen group for aging performance testing is pressurized for a certain period of time in two environments: without hydrogen and with hydrogen, and then the mechanical properties are tested under the designed temperature and pressure conditions to obtain the corresponding aging performance adaptability score S 老化 ;

[0007] The second non-metallic sealing material specimen group for explosion-proof performance testing is fixed in the high-temperature and high-pressure reactor, and the high-temperature and high-pressure reactor is purged with a natural gas mixture containing hydrogen. The processes of pressurization, pressure holding and pressure relief are repeated to the specified number of cycles, and then the second non-metallic sealing material specimen is observed to obtain the corresponding explosion-proof performance adaptability score S 抗爆 , where the pressurization process is: pressurize and heat up to the preset temperature and pressure according to the specified temperature and pressure; the pressure holding process is: keep the preset temperature and pressure for a certain period of time to make the gas inside the second non-metallic sealing material specimen group reach saturation; the pressure relief process is: release the gas in the high-temperature and high-pressure reactor to the atmospheric pressure at a constant pressure relief rate, and the temperature reduction range in the pressure relief stage is less than the set temperature threshold;

[0008] The third non-metallic sealing material specimen group for permeability performance testing is set in a closed space, and each specimen forming the third non-metallic sealing material specimen group divides the closed space into two independent closed chambers of the same size, namely a high-pressure chamber and a low-pressure chamber. A natural gas mixture containing hydrogen is provided in the high-pressure chamber to increase the pressure of the chamber to the specified pressure and temperature. The pressure in the high-pressure chamber is greater than the atmospheric pressure, and the pressure in the low-pressure chamber is lower than the atmospheric pressure. A certain pressure difference is maintained on both sides of the third non-metallic sealing material specimen group and stabilized for a certain period of time. The gas pressure and temperature changes in the chambers on both sides of the third non-metallic sealing material specimen group before and after stabilization are recorded to obtain the corresponding permeability performance adaptability score S 渗透 ;

[0009] When conducting aging performance testing, explosion-proof performance testing and permeability performance testing, the hydrogen doping ratio in the natural gas mixture containing hydrogen is the same. Finally, the comprehensive performance score is calculated and denoted as S, S = S 老化 +S 抗爆 +S 渗透 .

[0010] As an optimization, when conducting the aging performance test, natural gas without hydrogen and a natural gas mixture containing hydrogen are respectively injected into the high-temperature and high-pressure autoclave to simulate a hydrogen-free environment and a hydrogen-containing environment. Among them, there are at least two groups of the first non-metallic sealing material specimens. One group of the first non-metallic sealing material specimens is used in the hydrogen-free environment, and the other group of the first non-metallic sealing material specimens is used in the hydrogen-containing environment. Each group of the first non-metallic sealing material specimens contains the first non-metallic sealing material specimens with the same quantity, the same material, and the same shape conditions. Several groups of the first non-metallic sealing material specimens are respectively kept at a constant temperature and pressure in the high-temperature and high-pressure autoclave in the hydrogen-free environment and the hydrogen-containing environment for a certain period of time, and then a tensile performance experiment is carried out on each group of the first non-metallic sealing material specimens, and the elongation rates δ 空气 and δ 氢气 of the first non-metallic sealing material specimens in the hydrogen-free environment and the hydrogen-containing environment are respectively measured. Among them, δ 空气 represents the elongation rate in the hydrogen-free environment, and δ 氢气 represents the elongation rate in the hydrogen-containing environment. The aging performance adaptability score S 老化 of the first non-metallic sealing material specimens is obtained through the aging performance adaptability scoring formula.

[0011] As an optimization, the aging performance adaptability scoring formula is specifically:

[0012]

[0013] Among them, A is the ratio of the tensile performance of the first non-metallic sealing material specimens in the hydrogen-containing environment to that in the hydrogen-free environment, represents the average value of the elongation rates of the first non-metallic sealing material specimens in the hydrogen-containing environment, and m represents the quantity of one group of the first non-metallic sealing material specimens.

[0014] As an optimization, when the range of the tensile performance ratio A is 0.8 < A ≤ 1.0, A takes 1.0; when the range of the tensile performance ratio A is 0.6 < A ≤ 0.8, A takes 0.8; when the range of the tensile performance ratio A is 0.4 < A ≤ 0.6, A takes 0.6; when the range of the tensile performance ratio A is 0.2 < A ≤ 0.4, A takes 0.4; when the range of the tensile performance ratio A is 0.0 < A ≤ 0.2, A takes 0.2.

[0015] As an optimization, when conducting the anti-explosion performance test, a natural gas mixture containing hydrogen is injected into the high-temperature and high-pressure autoclave to conduct a purging and gas-washing treatment on the high-temperature and high-pressure autoclave. Among them, the second non-metallic sealing material specimen group includes several second non-metallic sealing material specimens with the same material and the same external conditions. The several second non-metallic sealing material specimens are respectively fixed in the high-temperature and high-pressure autoclave in a hydrogen-containing environment, and the pressure is repeatedly increased, maintained, and released to a specified number of cycles, and then the second non-metallic sealing material specimens are observed to obtain the corresponding anti-explosion performance adaptability score S 抗爆 。

[0016] As an optimization, the corresponding anti-explosion performance adaptability score S is obtained 抗爆 The specific process is as follows:

[0017] If there is no visible damage on the surface of the second non-metallic sealing material specimen, the second non-metallic sealing material specimen is cut into K equal parts along the axial direction of the second non-metallic sealing material specimen, and K is a positive integer not less than 4;

[0018] If there are several visible damage areas on the surface of the second non-metallic sealing material specimen, the first cut is made at a specified position in the largest visible relevant damage area, the second cut is made at a specified position in the most obvious but non-relevant damage area, and the third cut is made at a specified position in the longest section among the three sections of the second non-metallic sealing material specimen that has been cut;

[0019] The cross-section of the second non-metallic sealing material specimen after cutting is observed one by one with a microscope for the size and quantity of cracks, bubbles, and holes, and the anti-explosion performance adaptability score of the second non-metallic sealing material specimen is obtained according to the anti-explosion performance scoring formula and the grade division.

[0020] As an optimization, the anti-explosion performance adaptability scoring formula is specifically:

[0021] S 抗爆 = min(B, C);

[0022] Among them, B is a parameter related to the total number n of cracks, air bubbles, and holes in a second non-metallic sealing material specimen; when the range of the total number of cracks, air bubbles, and holes is 0 < n ≤ 2, B takes 10; when the range of the total number of cracks, air bubbles, and holes is 2 < n ≤ 4, B takes 8; when the range of the total number of cracks, air bubbles, and holes is 4 < n ≤ 6, B takes 6; when the range of the total number of cracks, air bubbles, and holes is 6 < n ≤ 8, B takes 4; when the range of the total number of cracks, air bubbles, and holes is 8 < n ≤ 10, B takes 2; C is a parameter related to the crack length L and the cross-sectional dimension D of the specimen; when the range of the crack length is 0 < L ≤ 20% D, C takes 10; when the range of the crack length is 20% D < L ≤ 40% D, C takes 8; when the range of the crack length is 40% D < L ≤ 60% D, C takes 6; when the range of the crack length is 80% D < L ≤ 100% D, C takes 4; when the range of the crack length is 100% D < L, C takes 2.

[0023] As an optimization, n is the average value of the total number of cracks, air bubbles, and holes in several second non-metallic sealing material specimens, and L is the average value of the length L of several second non-metallic sealing material specimens.

[0024] As an optimization, the specified position is in the range of 45% - 65% of the damaged part along the axial direction of the second non-metallic sealing material specimen; or the specified position is in the range of 45% - 65% of the total length of this section of the second non-metallic sealing material specimen along the axial direction of the second non-metallic sealing material specimen.

[0025] As an optimization, the third non-metallic sealing material specimen group includes several third non-metallic sealing material specimens with the same material and the same external shape conditions. The several third non-metallic sealing material specimens are arranged in parallel so that the closed space is separated into a high-pressure chamber and a low-pressure chamber, and temperature sensors and pressure sensors are respectively arranged in the high-pressure chamber and the low-pressure chamber. A certain pressure difference is respectively maintained on both sides of the third non-metallic sealing material specimen group, and the pressure is stabilized for a certain time. Record the gas pressure and temperature changes in the high-pressure chamber before and after the pressure stabilization, and obtain the permeability adaptability score S of the third non-metallic sealing material specimen through the permeability adaptability scoring formula. 渗透 。

[0026] As an optimization, the permeability adaptability scoring formula is specifically:

[0027]

[0028] Among them, m represents the number of the third non-metallic sealing material specimens, and Δp represents the pressure drop rate of the third non-metallic sealing material specimens, The unit is %; Ts is the absolute temperature of the gas in the high-pressure chamber at the start of pressure stabilization, in K; T z is the absolute temperature of the gas in the high-pressure chamber at the end of pressure stabilization, with the unit of K; P s is the absolute pressure of the gas in the high-pressure chamber at the start of pressure stabilization, P s = P s1 + P s2 , P z is the absolute pressure of the gas in the high-pressure chamber at the end of pressure stabilization, P z = P z1 + P z2 , with the unit of MPa; P s1 、P z1 are the readings of the high-pressure side pressure gauges at the start and end of pressure stabilization respectively, in MPa; P s2 、P z2 are the readings of the low-pressure side pressure gauges at the start and end of pressure stabilization, with the unit of MPa;

[0029] When the range of the pressure drop rate is , take 0.5; when the range of the pressure drop rate is , take 1.0; when the range of the pressure drop rate is , take 1.5; when the range of the pressure drop rate is , take 2.0; when the range of the pressure drop rate is , take 2.5.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] The present invention has established a systematic and complete evaluation method, safety level, and critical safety operating conditions, determined the adaptability of non-metallic sealing materials under the condition of hydrogen-doped transportation in natural gas pipelines, and promoted the implementation of hydrogen-doped projects in natural gas pipelines. Detailed implementation manners

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. The illustrative implementation manners and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0033] By comparing the differences in the performance test results of non-metallic sealing materials in hydrogen-free and hydrogen-containing environments, the influence law of hydrogen-doped transportation on the performance of non-metallic sealing materials in pipelines can be clarified; the present invention also includes the aging performance, explosion resistance performance, and permeability performance tests of non-metallic sealing materials, and can systematically and completely evaluate the influence law of hydrogen-doped transportation on the performance of non-metallic sealing materials.

[0034] In Example 1, the hydrogen doping ratio in the hydrogen-containing environment is 5%, and the hydrogen doping ratio in the hydrogen-free environment is 0%. V 氢气 and V 天然气 are the volumes of hydrogen and natural gas respectively.

[0035] Next, the method of the present invention will be specifically introduced.

[0036] Example 1 provides a method for evaluating the adaptability of non-metallic sealing materials for hydrogen-doped natural gas pipelines, including:

[0037] Using a high-temperature and high-pressure autoclave to simulate the pipeline field conditions, including temperature, pressure and gas components, keeping the first non-metallic sealing material specimen group for aging performance test under hydrogen-free and hydrogen-containing environments for a certain period of time respectively, and then testing the mechanical properties under the designed temperature and pressure conditions to obtain the corresponding aging performance adaptability score S 老化 ; According to the percentage range of the change in tensile properties between the hydrogen-containing environment and the hydrogen-free environment, the hydrogen doping adaptability of the non-metallic sealing material is scored and graded to evaluate its applicability under different hydrogen-containing environments.

[0038] Aging performance test:

[0039] Specifically, when conducting the aging performance test, natural gas without hydrogen and a natural gas mixture containing hydrogen are respectively injected into the high-temperature and high-pressure autoclave to simulate a hydrogen-free environment and a hydrogen-containing environment. Among them, there are at least two groups of the first non-metallic sealing material specimens. One group of the first non-metallic sealing material specimens is used in the hydrogen-free environment, and the other group of the first non-metallic sealing material specimens is used in the hydrogen-containing environment. Each group of the first non-metallic sealing material specimens contains the first non-metallic sealing material specimens with the same quantity, material and shape conditions. Several groups of the first non-metallic sealing material specimens are respectively kept warm and pressurized in the high-temperature and high-pressure autoclave in the hydrogen-free environment and the hydrogen-containing environment for a certain period of time, and then a tensile performance experiment is carried out on each group of the first non-metallic sealing material specimens to respectively measure the elongation rates δ 空气 and δ 氢气 of the first non-metallic sealing material specimens in the hydrogen-free environment and the hydrogen-containing environment. Among them, δ 空气 represents the elongation rate in the hydrogen-free environment, and δ 氢气 represents the elongation rate in the hydrogen-containing environment. The aging performance adaptability score S 老化 of the first non-metallic sealing material specimens is obtained through the aging performance adaptability scoring formula.

[0040] The specific formula for the aging performance adaptability score is as follows:

[0041]

[0042] Among them, A is the ratio of the tensile properties of the first non-metallic sealing material specimen in a hydrogen-containing environment to that in a hydrogen-free environment. represents the average value of the elongation rate of the first non-metallic sealing material specimen in a hydrogen-containing environment, and m represents the number of the first non-metallic sealing material specimens in a group.

[0043] If the range of the tensile property ratio A is 0.8 < A ≤ 1.0, A takes 1.0; if the range of the tensile property ratio A is 0.6 < A ≤ 0.8, A takes 0.8; if the range of the tensile property ratio A is 0.4 < A ≤ 0.6, A takes 0.6; if the range of the tensile property ratio A is 0.2 < A ≤ 0.4, A takes 0.4; if the range of the tensile property ratio A is 0.0 < A ≤ 0.2, A takes 0.2.

[0044] That is, the test uses a high-temperature and high-pressure hydrogen reaction kettle to simulate the on-site working conditions of the pipeline, including temperature, pressure and gas components, that is, to simulate high-pressure hydrogen-free and hydrogen-containing environments, control the pressure at 6.3 MPa, the temperature at 30 °C, the gas is a mixture of methane and hydrogen, and the hydrogen doping ratios are 0 and 5% respectively; secondly, the test object is the first non-metallic sealing material specimen group, and the first non-metallic sealing material specimen is a standard tensile specimen, and the specimen processing refers to the standard GB / T 34903.2, with a nominal thickness of 2 mm, and 5 parallel first non-metallic sealing material specimens are tested in each group; then, the test first maintains the pressure for 30 days under the specified pressure, temperature and gas composition conditions, and then conducts tensile property tests; finally, compare the elongation rates of the non-metallic sealing materials in hydrogen-free and hydrogen-containing environments, and according to the ratio range of the elongation rates in hydrogen-containing and hydrogen-free environments, score and grade the hydrogen doping adaptability of the non-metallic sealing materials. The ratio of the tensile properties in hydrogen-containing and hydrogen-free environments is denoted as A, as shown in formula 1 for details, and the score of the hydrogen doping aging performance adaptability of the non-metallic sealing material is denoted as S 老化 .

[0045] Explosion resistance performance test:

[0046] Fix the second non-metallic sealing material specimen group for explosion resistance performance test in a high-temperature and high-pressure reaction kettle, and conduct purging treatment on the high-temperature and high-pressure reaction kettle with a natural gas mixed gas containing hydrogen, repeat the pressure boosting, pressure maintaining and pressure relieving to the specified number of cycles, and then observe the second non-metallic sealing material specimen to obtain the corresponding explosion resistance performance adaptability score S 抗爆, wherein the pressure application process is as follows: pressurize and heat up to the preset temperature and pressure according to the specified temperature and pressure; the pressure holding process is as follows: maintain the preset temperature and pressure for a certain period of time to make the gas inside the second non-metallic sealing material specimen group reach saturation; the pressure relief process is as follows: release the gas in the high-temperature and high-pressure autoclave to atmospheric pressure at a constant pressure relief rate, and the temperature reduction range during the pressure relief stage is less than the set temperature threshold. Page 22 of GBT34903.2 states that the temperature should be kept as constant as possible during the test pressure reduction stage. Although the temperature will inevitably decrease slightly during the pressure relief process, therefore, the temperature should be kept as constant as possible during the pressure relief stage. Even if there is a slight decrease, the decrease range should be less than the set temperature threshold. Here, the temperature threshold can be set according to the actual situation;

[0047] Wherein, the second non-metallic sealing material specimen group includes several second non-metallic sealing material specimens with the same material and the same external shape conditions. Fix several of the second non-metallic sealing material specimens in the high-temperature and high-pressure autoclave in a hydrogen-containing environment, repeat the pressure application, pressure holding, and pressure relief to the specified number of cycles, and then observe the second non-metallic sealing material specimens to obtain the corresponding anti-explosion performance adaptability score S 抗爆 。

[0048] Obtain the corresponding anti-explosion performance adaptability score S 抗爆 The specific process is as follows:

[0049] If there is no visible damage on the surface of the second non-metallic sealing material specimen, then cut the second non-metallic sealing material specimen into K equal parts along the axial direction of the second non-metallic sealing material specimen, where K is a positive integer not less than 4;

[0050] If there are several visible damage areas on the surface of the second non-metallic sealing material specimen, then the first cut is made at the specified position of the largest visible relevant damage area, the second cut is made at the specified position of the most obvious but non-relevant damage area, and the third cut is made at the specified position of the longest section among the three sections of the second non-metallic sealing material specimen that has been cut; if the first two cuts divide the second non-metallic sealing material specimen into almost equal three parts, then the third cut can be made arbitrarily in the middle of one of the sections. The two terms, the largest visible relevant damage area and the most obvious but non-relevant damage area, are the exact words in Clause B.4 of Standard GB / T34903.2-2017, and will not be elaborated here. Use a microscope to observe the size and quantity of cracks, air bubbles, and holes on the cross-section of the second non-metallic sealing material specimen that has been cut one by one, and obtain the anti-explosion performance adaptability score of the second non-metallic sealing material specimen according to the anti-explosion performance scoring formula and grade division.

[0051] The specified position is in the axial direction of the second non-metallic sealing material specimen, at the position of 45%-65% of the damaged part.

[0052] That is, along the axial direction of the second non-metallic sealing material specimen, a damaged part is divided into 100 equal parts. Taking one end of the damaged part as the starting point, the position of the 45th - 65th equal part is the specified position.

[0053] The specific formula for the anti-explosion performance adaptability score is as follows:

[0054] S 抗爆 = min(B, C);

[0055] Wherein, B is a parameter related to the total number n of cracks, air bubbles, and holes in a second non-metallic sealing material specimen; when the range of the total number of cracks, air bubbles, and holes is 0 < n ≤ 2, B takes 10; when the range of the total number of cracks, air bubbles, and holes is 2 < n ≤ 4, B takes 8; when the range of the total number of cracks, air bubbles, and holes is 4 < n ≤ 6, B takes 6; when the range of the total number of cracks, air bubbles, and holes is 6 < n ≤ 8, B takes 4; when the range of the total number of cracks, air bubbles, and holes is 8 < n ≤ 10, B takes 2; C is a parameter related to the crack length L and the cross-sectional size D of the specimen; when the range of the crack length is 0 < L ≤ 20% D, C takes 10; when the range of the crack length is 20% D < L ≤ 40% D, C takes 8; when the range of the crack length is 40% D < L ≤ 60% D, C takes 6; when the range of the crack length is 80% D < L ≤ 100% D, C takes 4; when the range of the crack length is 100% D < L, C takes 2. Since there are multiple second non-metallic sealing material specimens, here n is the average value of the total number of cracks, air bubbles, and holes in several second non-metallic sealing material specimens, and L is the average value of the lengths L of several second non-metallic sealing material specimens.

[0056] In specific implementation, first, fix the second non-metallic sealing material specimen on a special fixture, apply a certain tightening force through bolts, and install the fixture in a high-temperature and high-pressure autoclave. Secondly, the gas is a mixture of methane and hydrogen, and the hydrogen doping ratio is 5%. Purge and wash the high-temperature and high-pressure autoclave, and then pressurize and heat it up. Control the pressure to be 6.3 MPa and the temperature to be 30 °C. Thirdly, keep the pressure for 72 h under the specified temperature and pressure conditions to saturate the gas inside the second non-metallic sealing material specimen, and then release the gas to the atmospheric pressure of 0.1 MPa at a constant pressure relief rate of 2 Mpa / min. Then, after maintaining for 1 hour at atmospheric pressure, repressurize the high-temperature and high-pressure autoclave to the test pressure of 6.3 MPa, and keep it at this pressure for 24 hours, and then relieve the pressure to the atmospheric pressure of 0.1 MPa at the same pressure relief rate. Repeat the pressure application, pressure holding, and pressure relief cycles 10 times. Finally, cut the second non-metallic sealing material specimen into 4 equal parts along the cross-section. The first cut should start from the center of the largest visible damage (such as bubbles or cracks); the second cut should start from the next most obvious but unrelated damage; the remaining parts should be cut in the middle area at approximately equal intervals. If there is no obvious damage on the non-metallic seal, the first cut can be made at any position of the second non-metallic sealing material specimen, and the other parts should be cut symmetrically around the seal. Observe the crack conditions on each cross-section one by one with a microscope at a magnification of 10 - 50 times, and based on the observation results such as the crack, bubble, hole size and quantity, score and classify the hydrogen doping adaptability of the non-metallic sealing material.

[0057] Permeability performance test:

[0058] Set the third non-metallic sealing material specimen group for the permeability performance test in a closed space respectively, and each specimen constituting the third non-metallic sealing material specimen group divides the closed space into two independent closed chambers of the same size, namely a high-pressure chamber and a low-pressure chamber. Provide a natural gas mixed gas containing hydrogen in the high-pressure chamber to increase the pressure of the chamber to the specified pressure and temperature. The pressure in the high-pressure chamber is greater than the atmospheric pressure, and the pressure in the low-pressure chamber is lower than the atmospheric pressure. Keep a certain pressure difference on both sides of the third non-metallic sealing material specimen group and stabilize the pressure for a certain time, record the gas pressure and temperature changes in the chambers on both sides of the third non-metallic sealing material specimen group before and after the pressure stabilization, and obtain the corresponding permeability performance adaptability score S 渗透 ;

[0059] The third non-metallic sealing material specimen group includes several third non-metallic sealing material specimens with the same material and the same external conditions. The several third non-metallic sealing material specimens are arranged in parallel to isolate the enclosed space into a high-pressure chamber and a low-pressure chamber. Temperature sensors and pressure sensors are respectively arranged in the high-pressure chamber and the low-pressure chamber. A certain pressure difference is maintained on both sides of the third non-metallic sealing material specimen group, and the pressure is stabilized for a certain period of time. The gas pressure and temperature changes in the high-pressure chamber before and after pressure stabilization are recorded, and the permeability adaptability score S of the third non-metallic sealing material specimen is obtained through the permeability adaptability scoring formula. 渗透 。

[0060] The specific permeability adaptability scoring formula is as follows:

[0061]

[0062] Among them, m represents the number of the third non-metallic sealing material specimens, and Δp represents the pressure drop rate of the third non-metallic sealing material specimens. The unit is %; T s is the absolute temperature of the gas in the high-pressure chamber at the start of pressure stabilization, in K; T z is the absolute temperature of the gas in the high-pressure chamber at the end of pressure stabilization, with the unit of K; P s is the absolute pressure of the gas in the high-pressure chamber at the start of pressure stabilization, P s =P s1 +P s2 ,P z is the absolute pressure of the gas in the high-pressure chamber at the end of pressure stabilization, P z =P z1 +P z2 ,the unit is MPa; P s1 、P z1 、are the readings of the high-pressure side pressure gauges at the start and end of pressure stabilization respectively, in MPa; P s2 、P z2 、are the readings of the low-pressure side pressure gauges at the start and end of pressure stabilization, with the unit of MPa;

[0063] When the range of the pressure drop rate is , take 0.5; when the range of the pressure drop rate is , take 1.0; when the range of the pressure drop rate is , Δp takes 1.5; when the range of the pressure drop rate is , take 2.0; when the range of the pressure drop rate is , take 2.5.

[0064] First, the permeability test unit of the third non-metallic sealing material is designed based on the differential pressure method. Its structure is to set two closed spaces inside and outside the non-metallic sealing material specimen. One is the gas supply side with a higher pressure, and the other is the permeation side with a lower pressure. Pressure and temperature sensors are equipped on both sides respectively. Secondly, keep the gas on the high-pressure side as a mixture of methane and hydrogen, with a hydrogen doping ratio of 5%, control the pressure at 6.3 MPa, and the temperature at 30 °C, with 3 parallel samples in each group. Keep the low-pressure side at atmospheric pressure of 0.1 MPa, stabilize the pressure for 24 h, and record the gas pressure and temperature changes in both chambers. Then, calculate the pressure drop rate on the high-pressure side through the pressure and temperature data in the two chambers before and after pressure stabilization. Finally, according to the pressure drop rate value of the hydrogen-containing gas, score and grade the hydrogen doping adaptability of the non-metallic sealing material.

[0065] Finally, calculate the comprehensive performance score, denoted as S, S = S 老化 + S 抗爆 + S 渗透 .

[0066] The sum of the scores for the aging performance, explosion resistance performance, and gas permeability performance of the non-metallic sealing material is denoted as S, S = S 老化 + S 抗爆 + S 渗透 , where S 老化 is the material aging performance score, S 抗爆 is the material explosion resistance performance score, and S 渗透 is the material gas permeability performance score. The single-item scores are 10, 8, 6, 4, and 2 points, and the comprehensive scores are 24 < S ≤ 30, 18 < S ≤ 24, 12 < S ≤ 18, 6 < S ≤ 12, and 0 < S ≤ 6 points, all in 5 grades. The corresponding adaptability levels are all 5, 4, 3, 2, and 1, the corresponding safety evaluations are all high safety area, relatively high safety area, potential risk area, relatively high risk area, and extremely high risk area, and the corresponding suggestions are all recommended for use, recommended for use, suggest optimizing the working conditions, not recommended for use, and not recommended for use, as shown in Table 1.

[0067] Table 1

[0068] Comprehensive Score Adaptability Level Safety Evaluation Suggestion 24＜S≤30 5 High Safety Area Recommended for Use 18＜S≤24 4 Higher Safety Area Recommended for Use 12＜S≤18 3 Potential Risk Area Suggested to Optimize Operating Conditions 6＜S≤12 2 Higher Risk Area Not Recommended for Use 0＜S≤6 1 Extremely High Risk Area Not Recommended for Use

[0069] The higher the score and grade, the better the hydrogen doping adaptability of the non-metallic sealing material, the smaller the influence of hydrogen doping on the performance of the non-metallic sealing material, the higher the pipeline safety during operation under this hydrogen doping condition, and it is recommended to use this non-metallic sealing material under the corresponding working conditions of the test conditions. On the contrary, the lower the score and grade, the worse the hydrogen doping adaptability of the non-metallic sealing material, the greater the influence of hydrogen doping on the performance of the non-metallic sealing material, the higher the pipeline safety risk during operation under this hydrogen doping condition, and it is recommended to optimize the working conditions or not recommend using this non-metallic sealing material under the corresponding working conditions of the test conditions.

[0070] When the single-item score is specified as 6 points, the corresponding operating conditions are the critical safety operating conditions for the corresponding single-item performance. To ensure the safe operation of the hydrogen-doped pipeline, the single-item performance score of the non-metallic sealing material should be greater than 6 points, and the comprehensive score should be greater than 18 points. Otherwise, it is recommended to optimize the operating conditions or not recommend using this non-metallic sealing material. Based on this, a series of evaluation tests for adaptability to different pressures, temperatures, and gas components are designed to obtain the critical safety operating conditions for hydrogen doping in the target pipeline.

[0071] The difference between Example 2 and Example 1 is that in the experiments of aging test, explosion resistance test, and permeation test, a hydrogen doping ratio of 10% is selected for detection.

[0072] The difference between Example 3 and Example 1 is that in the experiments of aging test, explosion resistance test, and permeation test, a hydrogen doping ratio of 15% is selected for detection.

[0073] The difference between Example 4 and Example 1 is that in the experiments of aging test, explosion resistance test, and permeation test, a hydrogen doping ratio of 20% is selected for detection.

[0074] The above experimental ratios are not all the experimental ratios. The specific hydrogen doping ratio to be selected can be determined according to the actual hydrogen ratio in the hydrogen-doped transportation of natural gas pipelines, which will not be elaborated here.

[0075] The specific embodiments described above further elaborate the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation, Characterized in that, It includes: The high-temperature and high-pressure autoclave is used to simulate the on-site working conditions of the pipeline, including temperature, pressure and gas components. The first non-metallic sealing material specimen group for aging performance testing is kept under pressure for a certain period of time in two environments: without hydrogen and with hydrogen, and then the mechanical properties are tested under the designed temperature and pressure conditions to obtain the corresponding aging performance adaptability score S 老化 ; Fix the second non-metallic sealing material specimen group to be tested for explosion resistance performance in a high-temperature and high-pressure autoclave, and purge and wash the high-temperature and high-pressure autoclave with a natural gas mixture containing hydrogen. Repeat the processes of pressurization, pressure holding, and pressure relief to the specified number of cycles, and then observe the second non-metallic sealing material specimen to obtain the corresponding explosion resistance performance adaptability score S 抗爆 , where the pressurization process is: pressurize and heat up to the preset temperature and pressure according to the specified temperature and pressure; the pressure holding process is: maintain the preset temperature and pressure for a certain period of time to make the gas inside the second non-metallic sealing material specimen group reach saturation; the pressure relief process is: release the gas in the high-temperature and high-pressure autoclave to atmospheric pressure at a constant pressure relief rate, and the temperature reduction range during the pressure relief stage is less than the set temperature threshold; The third non-metallic sealing material specimen group for the permeability performance test is set in a closed space, and each specimen that makes up the third non-metallic sealing material specimen group separates the closed space into two independent closed chambers of the same size, namely a high-pressure chamber and a low-pressure chamber. A natural gas mixed gas containing hydrogen is provided in the high-pressure chamber to increase the pressure of the chamber to a specified pressure and temperature. The pressure in the high-pressure chamber is greater than the atmospheric pressure, and the pressure in the low-pressure chamber is lower than the atmospheric pressure. A certain pressure difference is maintained on both sides of the third non-metallic sealing material specimen group and stabilized for a certain period of time. The gas pressure and temperature changes in the chambers on both sides of the third non-metallic sealing material specimen group before and after the pressure stabilization are recorded, and the corresponding permeability performance adaptability score S is obtained 渗透 ; During the aging performance test, anti-knock performance test, and permeability performance test, the hydrogen doping ratio in the natural gas mixture containing hydrogen is the same, and finally the comprehensive performance score is calculated, denoted as S, where S = S 老化 + S 抗爆 + S 渗透 .

2. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 1, Characterized in that, When conducting the aging performance test, natural gas without hydrogen and a natural gas mixture containing hydrogen are respectively injected into the high-temperature and high-pressure autoclave to simulate a hydrogen-free environment and a hydrogen-containing environment. Among them, there are at least two groups of the first non-metallic sealing material specimen groups. One group of the first non-metallic sealing material specimen groups is used in the hydrogen-free environment, and the other group of the first non-metallic sealing material specimen groups is used in the hydrogen-containing environment. Each group of the first non-metallic sealing material specimen groups contains first non-metallic sealing material specimens with the same quantity, the same material, and the same shape conditions. Several groups of the first non-metallic sealing material specimen groups are respectively kept at a constant temperature and pressure in the high-temperature and high-pressure autoclave in the hydrogen-free environment and the hydrogen-containing environment for a certain period of time, and then a tensile performance experiment is carried out on each group of the first non-metallic sealing material specimen groups, and the elongation rates δ 空气 and δ 氢气 of the first non-metallic sealing material specimen groups in the hydrogen-free environment and the hydrogen-containing environment are respectively measured. Among them, δ 空气 represents the elongation rate in the hydrogen-free environment, and δ 氢气 represents the elongation rate in the hydrogen-containing environment. The aging performance adaptability score S 老化 of the first non-metallic sealing material specimen is obtained through the aging performance adaptability scoring formula.

3. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 2, Characterized in that, The specific formula for the adaptability score of the aging performance is: Wherein, A is the ratio of the tensile properties of the first non-metallic sealing material specimen in a hydrogen-containing environment to that in a hydrogen-free environment, represents the average value of the elongation rate of the first non-metallic sealing material specimen in a hydrogen-containing environment, and m represents the number of a group of the first non-metallic sealing material specimens.

4. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 3, Characterized in that, If the range of the tensile property ratio A is 0.8 < A ≤ 1.0, A takes 1.0; if the range of the tensile property ratio A is 0.6 < A ≤ 0.8, A takes 0.8; if the range of the tensile property ratio A is 0.4 < A ≤ 0.6, A takes 0.6; if the range of the tensile property ratio A is 0.2 < A ≤ 0.4, A takes 0.4; if the range of the tensile property ratio A is 0.0 < A ≤ 0.2, A takes 0.

2.

5. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 1, Characterized in that, When conducting the anti-explosion performance test, a natural gas mixture containing hydrogen is injected into the high-temperature and high-pressure autoclave to purge and wash the high-temperature and high-pressure autoclave. Among them, the second non-metallic sealing material specimen group includes several second non-metallic sealing material specimens with the same material and the same external conditions. The several second non-metallic sealing material specimens are respectively fixed in the high-temperature and high-pressure autoclave in a hydrogen-containing environment, and the pressure is repeatedly increased, maintained, and released to a specified number of cycles, and then the second non-metallic sealing material specimens are observed to obtain the corresponding anti-explosion performance adaptability score S 抗爆 。 6. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 5, Characterized in that, Obtain the corresponding anti-knock performance adaptability score S 抗爆 The specific process is as follows: If there is no visible damage on the surface of the second non-metallic sealing material specimen, the second non-metallic sealing material specimen is cut into K equal parts along the axial direction of the second non-metallic sealing material specimen, where K is a positive integer not less than 4; If there are several visible damage areas on the surface of the second non-metallic sealing material specimen, the first cut is made at a specified position of the largest visible relevant damage area, the second cut is made at a specified position of the most obvious but non-relevant damage area, and the third cut is made at a specified position of the longest section among the three sections of the second non-metallic sealing material specimen that have been cut; The sizes and quantities of cracks, bubbles, and holes in the cross-section of the second non-metallic sealing material specimen after cutting are observed one by one with a microscope, and the adaptability score of the anti-explosion performance of the second non-metallic sealing material specimen is obtained according to the anti-explosion performance score formula and the grade division.

7. The method for evaluating the adaptability of non-metallic sealing materials for natural gas pipelines with hydrogen doping during transportation according to claim 6, Characterized in that, The specific formula for the adaptability score of the anti-explosion performance is: S 抗爆 = min(B, C); Among them, B is a parameter related to the total number n of cracks, air bubbles, and holes in a second non-metallic sealing material specimen; when the range of the total number of cracks, air bubbles, and holes is 0 < n ≤ 2, B takes 10; when the range of the total number of cracks, air bubbles, and holes is 2 < n ≤ 4, B takes 8; when the range of the total number of cracks, air bubbles, and holes is 4 < n ≤ 6, B takes 6; when the range of the total number of cracks, air bubbles, and holes is 6 < n ≤ 8, B takes 4; when the range of the total number of cracks, air bubbles, and holes is 8 < n ≤ 10, B takes 2; C is a parameter related to the crack length L and the cross-sectional size D of the specimen; when the crack length range is 0 < L ≤ 20% D, C takes 10; when the crack length range is 20% D < L ≤ 40% D, C takes 8; when the crack length range is 40% D < L ≤ 60% D, C takes 6; when the crack length range is 80% D < L ≤ 100% D, C takes 4; when the crack length range is 100% D < L, C takes 2.

8. The method for evaluating the adaptability of a non-metallic sealing material for a hydrogen-doped natural gas pipeline according to claim 7, characterized in that, n is the average value of the total number of cracks, air bubbles, and holes in several of the second non-metallic sealing material specimens, and L is the average value of the lengths L of several of the second non-metallic sealing material specimens.

9. The method for evaluating the adaptability of a non-metallic sealing material for a hydrogen-doped natural gas pipeline according to claim 6, characterized in that, the specified position is in the axial direction of the second non-metallic sealing material specimen, at the position of 45% - 65% of the damaged part; or the specified position is in the axial direction of the second non-metallic sealing material specimen, at the position of 45% - 65% of the total length of this section of the second non-metallic sealing material specimen.

10. The method for evaluating the adaptability of a non-metallic sealing material for a hydrogen-doped natural gas pipeline according to claim 1, characterized in that, The third non-metallic sealing material specimen group includes several third non-metallic sealing material specimens with the same material and the same external conditions. The several third non-metallic sealing material specimens are respectively arranged in the sealed space so as to isolate the sealed space into a high-pressure chamber and a low-pressure chamber, and temperature sensors and pressure sensors are respectively arranged in the high-pressure chamber and the low-pressure chamber. A certain pressure difference is maintained on both sides of the third non-metallic sealing material specimen group respectively, and the pressure is stabilized for a certain period of time. The gas pressure and temperature changes in the high-pressure chamber before and after the pressure stabilization are recorded, and the permeability adaptability score S of the third non-metallic sealing material specimen is obtained through the permeability adaptability scoring formula 渗透 .

11. The method for evaluating the adaptability of a non-metallic sealing material for a hydrogen-doped natural gas pipeline according to claim 9, characterized in that, the specific formula for the adaptability score of the permeation performance is: Among them, m represents the number of the third non-metallic sealing material specimens, and Δp represents the pressure drop rate of the third non-metallic sealing material specimens, in %; T s is the absolute temperature of the gas in the high-pressure chamber at the start of the constant pressure, in K; T z is the absolute temperature of the gas in the high-pressure chamber at the end of the constant pressure, with the unit of K; P s is the absolute pressure of the gas in the high-pressure chamber at the start of the constant pressure, P s = P s1 + P s2 , P z is the absolute pressure of the gas in the high-pressure chamber at the end of the constant pressure, P z = P z1 + P z2 , with the unit of MPa, P s1 and P z1 are the readings of the high-pressure side pressure gauges at the start and end of the constant pressure respectively, in MPa; P s2 and P z2 are the readings of the low-pressure side pressure gauges at the start and end of the constant pressure, with the unit of MPa; when the range of the pressure drop rate is , takes 0.5; when the range of the pressure drop rate is , takes 1.0; when the range of the pressure drop rate is , takes 1.5; when the range of the pressure drop rate is , takes 2.0; when the range of the pressure drop rate is , takes 2.5.

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