A method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline

Abstract

The present invention discloses a method for calculating the potential impact radius of a mixed hydrogen natural gas pipeline, comprising the following steps: Step 1: Collect key parameters for calculating the impact radius; Step 2: Calculate the relevant parameters of the mixed gas after the components of the mixed hydrogen natural gas are mixed, including the molar mass of the mixed gas, the sound velocity of the mixed gas, the specific heat ratio of the mixed gas, the combustion heat of the mixed gas, and the radiation coefficient of the mixed gas; Step 3: Calculate the potential impact radius of the mixed gas pipeline. The present invention proposes a simplified calculation method for the potential impact radius of a mixed hydrogen natural gas pipeline based on the design pressure, the inner diameter of the pipeline and the concentration correction factor, which more clearly determines the potential impact radius of natural gas pipelines with different hydrogen contents. Compared with the existing technical specifications, at the same pressure and the same outer diameter, the potential impact radius of the mixed hydrogen natural gas pipeline is greater than that of the pure hydrogen pipeline, which reflects the role of the present invention in promoting and facilitating the safety of the mixed hydrogen natural gas pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of natural gas pipeline structure design, and in particular relates to a method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline. Background Art

[0002] As one of the important development directions of new energy, hydrogen has significant advantages over traditional fossil fuels, such as high calorific value, no pollution to the environment from combustion products, wide sources and renewable nature. It is known as the clean energy of the future and will become a new way for mankind to solve the increasingly severe energy and environmental problems in the future. At present, adding hydrogen to the existing natural gas pipeline transportation system is recognized as an effective way to utilize hydrogen energy on a large scale. It can not only effectively reduce the investment in the construction of new hydrogen pipeline systems, but also make full use of the advantages of the existing natural gas pipeline network to achieve flexible allocation and efficient utilization of resources.

[0003] For conventional natural gas pipelines, the current specification GB 32167-2015 "Oil and Gas Pipeline Integrity Management Specification" stipulates the method for determining its potential impact radius. By calculating the potential impact radius range, high-consequence areas are effectively identified, and detailed operation and management measures are formulated to ensure the safety of personnel and property around the pipeline. For hydrogen pipelines, the foreign specification ASME B31.12 "Hydrogen Pipelines and Pipelines" also recommends a method for calculating its potential impact radius. Quantitatively speaking, compared with hydrogen pipelines of the same diameter and design pressure, the potential impact radius of natural gas pipelines is about 1.5 times that of hydrogen pipelines, which reflects the medium combustion characteristics of natural gas and hydrogen.

[0004] Furthermore, for hydrogen-mixed natural gas pipelines, the method for determining the potential impact radius is still in an unreported state. The ASME B31.12 "Hydrogen Pipelines and Pipelines" specification applies to pipelines with a hydrogen content higher than 10%, that is, for hydrogen pipelines with a natural gas blending concentration lower than 90%, this specification is theoretically applicable. However, in this specification, the potential impact radius calculation formula proposed is only related to the pipe diameter and design pressure, and does not mention the specific component composition, and its calculation result is much smaller than that of natural gas pipelines. If the potential impact radius analysis is conducted on natural gas pipelines with a hydrogen content of more than 10% in accordance with the guidance of this specification, it is very likely to mislead users in calculating the potential impact radius of hydrogen pipelines with different natural gas contents, causing the actual calculated value to be less than the theoretical value, bringing risks. For example, for a natural gas pipeline with a hydrogen content of 10%, since the specification does not specify the components, under the same pressure and design pressure, its potential impact radius is only about 70% of that of a natural gas pipeline, which obviously has large errors and disputes.

[0005] Therefore, it is necessary to analyze the calculation method of the potential impact radius of the hydrogen-mixed natural gas pipeline and propose a correction method for the potential impact radius of the hydrogen-mixed natural gas pipeline to provide support and reference for the development of hydrogen-mixed natural gas transmission technology and help the development of the carbon-neutral industry. Summary of the invention

[0006] The purpose of the present invention is to provide a method for calculating the potential impact radius of a hydrogen-blended natural gas pipeline that can effectively ensure the safe operation of the hydrogen-blended natural gas pipeline in response to the above-mentioned problems.

[0007] The main technical idea of ​​the present invention is to make component-based corrections to the radiant heat, density, molar mass, emissivity, specific heat ratio, etc. of the mixed medium for hydrogen-mixed natural gas pipelines, propose a corresponding potential influence radius correction method, optimize the calculation formula for the potential influence radius of the natural gas pipeline recommended by the current specifications, improve the calculation accuracy of the potential influence radius of the corresponding hydrogen-mixed natural gas pipeline, and provide reference and support for safe operation.

[0008] The technical solution adopted by the present invention is: a method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline, characterized in that it includes the following steps:

[0009] Step 1: Collect key parameters that affect radius calculation, including pipeline design pressure P, pipeline inner diameter D, and related parameters of hydrogen-mixed natural gas components;

[0010] Step 2: Calculate the relevant parameters of the mixed gas after the hydrogen-natural gas components are mixed, including the molar mass of the mixed gas, the sound velocity of the mixed gas, the specific heat ratio of the mixed gas, the combustion heat of the mixed gas, and the radiation coefficient of the mixed gas;

[0011] Step 3: Calculate the potential impact radius of the mixed gas pipeline, use the commonly specified death radius thermal radiation threshold as the radiation heat impact boundary value, and calculate the potential impact radius r of the spherical model.

[0012]

[0013] Where r is the theoretical potential impact radius, in meters; X mixture is the radiation coefficient of the mixed gas; Q is the average flow rate of pipeline leakage, in kg / s; H mixture is the heat of combustion of the mixed gas.

[0014] In the method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline of the present invention, the component composition-related parameters collected in step 1 specifically include:

[0015] Hydrogen gas volume fraction V H2 , methane volume fraction V C1 ;

[0016] Heat value of hydrogen combustion H H2 , heat of combustion of methane H C1 ;

[0017] Hydrogen specific heat ratio γ H2 , methane specific heat ratio γ C1 ;

[0018] Molar mass of hydrogen M H2 , Methane molar mass M C1 ;

[0019] Hydrogen radiation coefficient X H2 , methane radiation coefficient X C1 .

[0020] The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline of the present invention includes the following specific calculation methods for the relevant parameters in step 2:

[0021] Calculate the molar mass of the mixed gas: M mixture =M H2 V H2 +M C1 V C1

[0022] Where M H2 is the molar mass of hydrogen, in g / mol; M C1 is the molar mass of methane, in g / mol; V H2 is the mole fraction of hydrogen; V C2 is the mole fraction of methane;

[0023] Calculate the heat of combustion of the gas mixture:

[0024] In the formula, H H2 is the calorific value of hydrogen combustion, in kJ / kg; H C1 methane combustion calorific value, in kJ / kg; H2 is the density of hydrogen under standard conditions, in kg / m 3 ρ C1 is the methane density under standard conditions, in kg / m 3 ;

[0025] Calculate the specific heat ratio of the mixed gas: γ mixture =γ H2 V H2 +γ C1 V C1

[0026] In the formula, γ H2 is the specific heat ratio of hydrogen under operating conditions; γ C1 is the specific heat ratio of methane under operating conditions;

[0027] Calculate the radiation coefficient of the mixed gas: X mixture =X H2 V H2 +X C1 V C1

[0028] In the formula, X H2 is the hydrogen radiation coefficient; X C1 is the methane radiation coefficient;

[0029] Calculate the mixed gas sound velocity, which is used to provide input for the mixed gas sound velocity:

[0030]

[0031] Where R is the ideal gas constant, in J / kg·mol / K; T is the gas temperature, in K.

[0032] The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline of the present invention includes the following specific calculation methods for the relevant parameters in step 2:

[0033] After the pipeline is completely broken, the actual discharge flow at the break point is the sum of the discharge flows of the pipelines on both sides; for high-pressure gas pipelines, the discharge flow gradually decreases as the pressure decreases. Considering the average discharge flow during the discharge process as the equivalent discharge value, the calculation formula for the average flow of pipeline leakage is:

[0034]

[0035] Where, Q is the average flow rate of pipeline leakage, in kg / s; D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; C d is the leakage coefficient; C mixture is the working sound velocity of the mixed medium, in m / s; β is the flow factor of the mixed gas;

[0036] Calculate the flow factor of a mixed medium:

[0037]

[0038] The method for calculating the potential impact radius of the mixed hydrogen natural gas pipeline of the present invention is that since it is impossible to have an absolutely static environment, that is, when there is a crosswind in a leakage environment, the combustion center point will be offset, so the theoretical potential impact radius r is corrected, and the correction coefficient a is determined based on a comprehensive evaluation of the deviation degree of the venting flare flame, and the correction coefficient a does not exceed 10%.

[0039] r real =a×r

[0040] In the formula, r real is the equivalent potential impact radius, in meters.

[0041] The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline of the present invention proposes a potential impact radius correction coefficient of a typical component based on step three, and forms a method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline based on design pressure, pipeline inner diameter and component correction coefficient, specifically:

[0042] The potential impact radius correction factor of pipelines with different hydrogen to natural gas ratios under the same design pressure and the same pipe diameter is proposed;

[0043] The calculation formula for the potential impact radius of the pipeline under different hydrogen concentrations can be written as:

[0044]

[0045] Where D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; m is the correction factor based on hydrogen concentration; the correction factor m is based on the different concentration values ​​of hydrogen in the mixed gas, and its value ranges from 0.075 to 0.107.

[0046] The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline of the present invention is based on the different concentration combinations of hydrogen and natural gas, and the correction coefficient m can be estimated by interpolation.

[0047] Compared with the prior art, the positive effects of the present invention are: based on the physical properties of natural gas and hydrogen, the present technical specifications fully consider the technical and scope deficiencies of the method for determining the potential impact radius of the pipeline, and start from the equivalent discharge flow, mixed gas characteristic characterization, spherical radiation impact range, etc., to correct the calculation method of the potential impact radius of natural gas pipelines with different hydrogen concentrations, and further propose a simplified calculation method for the potential impact radius of mixed hydrogen natural gas pipelines based on design pressure, pipeline inner diameter and concentration correction coefficient, which has an important supporting role in the design, operation and maintenance of mixed hydrogen natural gas pipelines. Furthermore, the calculation method of the present invention more clearly determines the potential impact radius of natural gas pipelines with different hydrogen contents. Compared with the requirements of the existing technical specifications, under the same pressure and the same outer diameter, the potential impact radius of the mixed hydrogen natural gas pipeline is greater than that of the pure hydrogen pipeline, which reflects the role of the present invention in promoting and facilitating the safety of mixed hydrogen natural gas pipelines. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0049] Therefore, the following detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0051] Embodiment: A method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline comprises the following steps:

[0052] Step 1: Collect key parameters affecting radius calculation, including pipeline design pressure P, pipeline inner diameter D and related parameters of hydrogen-mixed natural gas components, to provide basic pipeline characteristics and component characteristics, so as to facilitate quantitative analysis of combustion sources and release volumes required for potential impact radius calculation. Specifically:

[0053] (1) Pipeline design pressure P, used to determine the initial pressure source after pipeline rupture.

[0054] (2) Pipeline inner diameter D, which is used to determine the maximum leakage area after the pipeline breaks.

[0055] (3) Hydrogen gas volume fraction V H2 , methane volume fraction V C1 , used to calculate the composition of mixed gas components and characterize the volume fraction (molar fraction) of mixed hydrogen.

[0056] (4) Hydrogen combustion calorific value H H2 , heat of combustion of methane H C1 , which is used to provide the basis for calculating the calorific value of combustion of mixed components.

[0057] (5) Hydrogen specific heat ratio γ H2 , methane specific heat ratio γ C1 , used to provide the basis for the calculation of the specific heat ratio of the mixed components;

[0058] (6) Hydrogen molar mass M H2 , Methane molar mass M C1 .

[0059] (7) Hydrogen radiation coefficient X H2 , methane radiation coefficient X C1 , which is used to provide the basis for the calculation of the radiation coefficient of the mixed components.

[0060] Step 2: Calculate the relevant parameters of the mixed gas after the hydrogen-natural gas components are mixed, including the molar mass of the mixed gas, the sound velocity of the mixed gas, the specific heat ratio of the mixed gas, the combustion heat of the mixed gas, and the radiation coefficient of the mixed gas. The specific calculation method is as follows:

[0061] (1) Calculate the molar mass of the mixed gas to provide input for the sound velocity of the mixed gas:

[0062] M mixture =M H2 V H2 +M C1 V C1

[0063] Where M H2 is the molar mass of hydrogen, in g / mol; M C1 is the molar mass of methane, in g / mol; V H2 is the mole fraction of hydrogen; V C2 is the mole fraction of methane.

[0064] (2) Calculate the combustion heat of the mixed gas to provide input for the calculation of the combustion heat flux of the mixed gas:

[0065]

[0066] In the formula, H H2 is the calorific value of hydrogen combustion, in kJ / kg; H C1 methane combustion calorific value, in kJ / kg; H2 is the density of hydrogen under standard conditions, in kg / m 3 ρ C1 is the methane density under standard conditions, in kg / m 3 .

[0067] (3) Calculate the specific heat ratio of the mixed gas to provide input for the calculation of the leakage rate of the mixed gas:

[0068] γ mixture =γ H2 V H2 +γ C1 V C1

[0069] In the formula, γ H2 is the specific heat ratio of hydrogen under operating conditions; γ C1 is the specific heat ratio of methane under operating conditions.

[0070] (4) Calculate the radiation coefficient of the mixed gas to provide input for the calculation of the radiation heat flux of the mixed gas. The thermal radiation capacity of hydrogen is smaller than that of natural gas. The radiation coefficients of hydrogen and methane are specified differently:

[0071] X mixture =X H2 V H2 +X C1 V C1

[0072] In the formula, X H2 is the radiation coefficient of hydrogen, which is taken as 0.15; X C1 is the methane radiation coefficient, which is taken as 0.2.

[0073] (5) Calculate the mixed gas sound velocity, which is used to provide input for the mixed gas sound velocity:

[0074]

[0075] Where R is the ideal gas constant, in J / kg·mol / K; T is the gas temperature, in K.

[0076] Step 3: Calculate the potential impact radius of the mixed gas pipeline. The specific calculation method is:

[0077] (1) After the pipeline is completely broken, the actual discharge flow rate at the break point is the sum of the discharge flow rates of the pipelines on both sides, that is, the pipeline on the left and the pipeline on the right of the break point are discharged at the same time, and the flow rate is considered to be twice the discharge flow rate of the pipeline on one side; for high-pressure gas pipelines, the discharge flow rate gradually decreases as the pressure decreases. Considering the average discharge flow rate of the discharge process as the equivalent discharge value, the calculation formula for the average discharge flow rate of the pipeline leakage is:

[0078]

[0079] Where, Q is the average flow rate of pipeline leakage, in kg / s; D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; C d is the leakage coefficient, hydrogen is 0.72, methane is 0.61, and the leakage coefficient of hydrogen-methane mixture is converted according to the volume ratio; C mixture is the working sound velocity of the mixed medium, in m / s; β is the flow factor of the mixed gas.

[0080] (2) Calculate the flow factor of the mixed medium:

[0081]

[0082] (3) Using the commonly specified 1% probability death radius thermal radiation threshold (15.8kW / m 2 ) as the radiation heat impact boundary value, calculate the potential impact radius r of the spherical model,

[0083]

[0084] Where r is the theoretical potential impact radius, in meters; X mixture is the radiation coefficient of the mixed gas; Q is the average flow rate of pipeline leakage, in kg / s; H mixture is the heat of combustion of the mixed gas.

[0085] Furthermore, since it is impossible to have an absolutely static environment, that is, when there is a crosswind in a leakage environment, the combustion center point will be offset, so the theoretical potential impact radius r is corrected, and the correction coefficient a is determined based on a comprehensive evaluation of the deviation degree of the flare flame. The correction coefficient a does not exceed 10%, and a 5% correction coefficient is preferably considered, that is:

[0086] r real =1.05×r

[0087] In the formula, r real is the equivalent potential impact radius, in meters.

[0088] Furthermore, in order to improve the calculation efficiency of steps one to three, a potential influence radius correction coefficient of typical components is proposed to form a calculation method for the potential influence radius of a hydrogen-mixed natural gas pipeline based on design pressure, pipeline inner diameter and component correction coefficient, specifically:

[0089] Through the superposition and combination of calculation formulas, it can be seen that the calculation of the potential impact radius of different mixed media is related to the design pressure and the inner diameter of the pipeline, and the rules are consistent. Therefore, the potential impact radius correction coefficient of pipelines with different hydrogen and natural gas ratios under the same design pressure and the same pipe diameter is proposed (the reference value is a pure natural gas pipeline). According to different gas concentrations, the corresponding component correction coefficient can be selected to quickly and accurately calculate the potential impact radius;

[0090] Specifically, the calculation formula for the potential impact radius of the pipeline under different hydrogen concentrations can be written as:

[0091]

[0092] Where D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; m is the correction factor based on hydrogen concentration; the correction factor m is based on the different concentration values ​​of hydrogen in the mixed gas, and the value is 0.075~0.107. The specific values ​​are as follows:

[0093] Natural gas concentration, % Hydrogen concentration, % m value 0 100 0.075 10 90 0.077 20 80 0.080 30 70 0.083 40 60 0.087 50 50 0.090 60 40 0.094 70 30 0.097 80 20 0.101 90 10 0.104 100 0 0.107

[0094] Furthermore, based on the different concentration combinations of hydrogen and natural gas, the correction coefficient m can be estimated by interpolation.

[0095] The principle of the present invention is:

[0096] (1) The potential impact radius of oil and gas pipelines is an important indicator and support for guiding the division of high consequence areas and the scope of risk assessment. A reasonable method for calculating the potential impact radius is crucial. The potential impact radius is determined according to the range of jet fire heat radiation that personnel can accept after the pipeline breaks. At present, the relevant specifications for gas transmission pipelines stipulate the calculation formula for the potential impact radius of natural gas pipelines; foreign hydrogen pipeline specifications stipulate the calculation formula for the potential impact radius of hydrogen pipelines, and the scope of application of the hydrogen pipeline specification is gas pipelines with a hydrogen content of more than 10%. Using the above specifications, the calculation results of the potential impact radius of hydrogen pipelines (hydrogen content greater than 10%, which can be considered as a hydrogen / natural gas mixture with a hydrogen content of 10% to 99%) are consistent under the same design pressure and pipeline inner diameter. At the same time, the potential impact radius of pure hydrogen pipelines is much smaller than that of pure natural gas pipelines; obviously, this does not take into account the impact of hydrogen concentration on the potential impact radius of hydrogen pipelines, and the potential impact radius of hydrogen pipelines is smaller than that of natural gas pipelines, which will undoubtedly mislead the calculation of the potential impact radius of mixed hydrogen natural gas pipelines, and this misleading will underestimate the potential impact radius of hydrogen-containing natural gas pipelines.

[0097] (2) To this end, the present invention proposes a method for calculating the potential impact radius area of ​​a gas pipeline with a specific hydrogen-natural gas content; by means of component combination, molar mass combination, specific heat ratio combination, combustion heat combination, etc., while taking into account the flame deviation caused by wind direction, the difference in the radiation coefficient of hydrogen and natural gas, etc., with the help of a spherical distribution model of the thermal radiation value of the jet fire after leakage, a method for calculating the potential impact radius of a mixed hydrogen natural gas pipeline under an acceptable radiation intensity threshold is formed. Using this method, the potential impact radius range of mixed hydrogen natural gas pipelines with different components, different pressures and different pipe diameters can be determined more accurately. Furthermore, using this method, when the hydrogen content is 0% or the natural gas content is 0%, the calculation result is very close to the potential impact radius recommended by the aforementioned natural gas pipeline and hydrogen pipeline specifications; under the same pressure and pipeline inner diameter, the potential impact radius increases with the increase of the natural gas content, which shows that for mixed hydrogen natural gas pipelines, the calculation result of the potential impact radius using the hydrogen pipeline specification is too loose and there is a safety hazard.

[0098] (3) In order to improve the convenience of calculating the potential impact radius of the mixed hydrogen natural gas pipeline in the present invention, a simplified calculation formula based on the component correction factor, design pressure and pipeline inner diameter is proposed, and recommended correction factors are listed for different hydrogen concentration conditions, which can quickly and accurately evaluate the potential impact radius of the mixed hydrogen natural gas pipeline with different hydrogen contents.

[0099] The present invention is not limited to the foregoing specific embodiments, and the present invention extends to any new features or any new combination disclosed in this specification, and any new method or process steps or any new combination disclosed.

Claims

1. A method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline. Features: The following steps are involved: Step 1: Collect key parameters that affect radius calculation, including pipeline design pressure P, pipeline inner diameter D, and related parameters of hydrogen-mixed natural gas components; Step 2: Calculate the relevant parameters of the mixed gas after the hydrogen-natural gas components are mixed, including the molar mass of the mixed gas, the sound velocity of the mixed gas, the specific heat ratio of the mixed gas, the combustion heat of the mixed gas, and the radiation coefficient of the mixed gas; Step 3: Calculate the potential impact radius of the mixed gas pipeline, use the commonly specified death radius thermal radiation threshold as the radiation heat impact boundary value, and calculate the potential impact radius r of the spherical model. Where r is the theoretical potential impact radius, in meters; X mixture is the radiation coefficient of the mixed gas; Q is the average flow rate of pipeline leakage, in kg / s; H mixture is the heat of combustion of the mixed gas.

2. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to claim 1, Features: The component composition related parameters collected in step 1 specifically include: Hydrogen gas volume fraction V H2 , methane volume fraction V C1 ; Heat value of hydrogen combustion H2 , heat of combustion of methane H C1 ; Hydrogen specific heat ratio γ H2 , methane specific heat ratio γ C1 ; Molar mass of hydrogen M H2 , Methane molar mass M C1 ; Hydrogen radiation coefficient X H2 , methane radiation coefficient X C1 .

3. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to claim 2, Features: The specific calculation method of the relevant parameters in step 2 is: Calculate the molar mass of the mixed gas: M mixture =M H2 V H2 +M C1 V C1 Where M H2 is the molar mass of hydrogen, in g / mol; M C1 is the molar mass of methane, in g / mol; V H2 is the mole fraction of hydrogen; V C2 is the mole fraction of methane; Calculate the heat of combustion of the gas mixture: In the formula, H H2 is the calorific value of hydrogen combustion, in kJ / kg; H C1 methane combustion calorific value, in kJ / kg; H2 is the density of hydrogen under standard conditions, in kg / m 3 ρ C1 is the methane density under standard conditions, in kg / m 3 ; Calculate the specific heat ratio of the mixed gas: γ mixture =γ H2 V H2 +γ C1 V C1 In the formula, γ H2 is the specific heat ratio of hydrogen under operating conditions; γ C1 is the specific heat ratio of methane under operating conditions; Calculate the radiation coefficient of the mixed gas: X mixture =X H2 V H2 +X C1 V C1 In the formula, X H2 is the radiation coefficient of hydrogen; X C1 is the methane radiation coefficient; Calculate the mixed gas sound velocity, which is used to provide input for the mixed gas sound velocity: C mixture =(1000γ mixture RT / M mixture ) 0.5 Where R is the ideal gas constant, in J / kg·mol / K; T is the gas temperature, in K.

4. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to claim 3, Features: The specific calculation method of the relevant parameters in step 2 is: After the pipeline is completely broken, the actual discharge flow at the break point is the sum of the discharge flows of the pipelines on both sides; for high-pressure gas pipelines, the discharge flow gradually decreases as the pressure decreases. Considering the average discharge flow during the discharge process as the equivalent discharge value, the calculation formula for the average flow of pipeline leakage is: Where, Q is the average flow rate of pipeline leakage, in kg / s; D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; C d is the leakage coefficient; C mixture is the working sound velocity of the mixed medium, in m / s; β is the flow factor of the mixed gas; Calculate the flow factor of a mixed medium:

5. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to claim 4, Features: Since it is impossible to have an absolutely static environment, that is, when there is a crosswind in a leakage environment, the combustion center point will shift, so the theoretical potential impact radius r is corrected, and the correction coefficient a is determined based on a comprehensive evaluation of the deviation degree of the flare flame. The correction coefficient a does not exceed 10%. r real ＝a×r In the formula, r real is the equivalent potential impact radius, in meters.

6. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to any one of claims 1 to 5, Features: Based on step three, the potential impact radius correction coefficient of typical components is proposed to form a calculation method for the potential impact radius of the mixed hydrogen natural gas pipeline based on the design pressure, pipeline inner diameter and component correction coefficient, specifically: The potential impact radius correction factor of pipelines with different hydrogen to natural gas ratios under the same design pressure and the same pipe diameter is proposed; The calculation formula for the potential impact radius of the pipeline under different hydrogen concentrations can be written as: Where D is the inner diameter of the pipeline, in mm; P is the design pressure of the pipeline, in MPa; m is the correction factor based on hydrogen concentration; the correction factor m is based on the different concentration values ​​of hydrogen in the mixed gas, and its value ranges from 0.075 to 0.

107.

7. The method for calculating the potential impact radius of a hydrogen-mixed natural gas pipeline according to claim 6, Features: Based on the different combinations of hydrogen and natural gas concentrations, the correction factor m can be estimated by interpolation.

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