Quantitative assessment method and system for explosion risk of hydrogen-blended natural gas

Abstract

The embodiment of the present application provides a method and system for quantitatively assessing the explosion risk of hydrogen-blended natural gas, which relates to the field of new energy safety technology. The assessment method is based on the event tree concept, and calculates the immediate ignition probability, delayed ignition probability and explosion probability when a hydrogen-blended natural gas pipeline leaks according to the lower explosion limit of the leaked material and the material leakage rate; determines the final event probability of a hydrogen-blended natural gas pipeline leak according to the immediate ignition probability, delayed ignition probability and explosion probability; calculates the evaluation index of the explosion consequences of a hydrogen-blended natural gas pipeline leak according to the material leakage rate; calculates the explosion risk evaluation index of a hydrogen-blended natural gas pipeline leak according to the immediate ignition probability, delayed ignition probability, explosion probability and pipeline leakage probability. In this way, the entire process of the hydrogen-blended natural gas pipeline from leakage to fire and explosion is evaluated, and the entire event chain of the hydrogen-blended natural gas explosion is fully monitored.

Description

Technical Field

[0001] This application relates to the field of new energy safety technology, and in particular to a method and system for quantitatively assessing the risk of combustion and explosion of hydrogen-blended natural gas. Background Technology

[0002] With the transformation of the global energy structure and increasingly stringent environmental standards, hydrogen energy, as a clean energy source, has become a key pathway for new energy consumption, storage, and integration, playing a crucial role in promoting global energy transformation. Among its various applications, utilizing existing natural gas pipelines for hydrogen blending and transportation is currently an effective strategy for balancing the safety and economy of hydrogen energy storage and transportation. Hydrogen-blended natural gas not only reduces dependence on fossil fuels but also significantly reduces greenhouse gas emissions. However, hydrogen's wide explosion limits, low minimum ignition energy, and rapid combustion rate significantly increase the safety risks during storage and use.

[0003] Currently, the risk assessment of combustion and explosion of hydrogen-blended natural gas mostly relies on qualitative or semi-quantitative methods, such as HAZOP analysis. These methods rely on expert judgment to provide preliminary risk assessments, but they have limitations in accurately predicting and quantifying risks, and cannot achieve continuous monitoring or provide real-time risk assessments.

[0004] Therefore, there is an urgent need to provide a technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of this application is to provide a method and system for quantitatively assessing the risk of combustion and explosion of hydrogen-blended natural gas, so as to solve or alleviate the problems existing in the prior art.

[0006] To achieve the above objectives, this application provides the following technical solution:

[0007] In a first aspect, embodiments of this application provide a method for quantitatively assessing the risk of combustion and explosion of hydrogen-blended natural gas, used to assess the risk of combustion and explosion caused by leakage in a hydrogen-blended natural gas pipeline. The assessment method includes:

[0008] Step S101: Determine the lower explosive limit L of the leaked substance and the substance leakage rate W corresponding to the j-th leakage scenario when a hydrogen-blended natural gas pipeline leaks. j And the probability of pipeline leakage P leak Where j is a positive integer;

[0009] Step S102: Based on the event tree concept, according to the lower explosive limit L of the leaked substance, and according to the substance leakage rate W... j Calculate the immediate ignition probability P corresponding to a leak in a hydrogen-blended natural gas pipeline. imm , ign Delayed ignition probability P del ,ign And the probability of explosion P exp / ign Among them, the probability of immediate ignition represents the possibility of frictional ignition; the probability of delayed ignition represents the possibility of ignition by external energy excitation; and the probability of explosion represents the possibility of explosion caused by external energy excitation ignition.

[0010] Step S103: Based on the immediate ignition probability P imm , ign Delayed ignition probability P del , ign And the probability of explosion P exp / ign To determine the probability of a final event of leakage in a hydrogen-blended natural gas pipeline;

[0011] Step S104: Based on the substance leakage rate W corresponding to the j-th leakage scenario j Calculate the evaluation index C for the combustion and explosion consequences of a leak in a hydrogen-blended natural gas pipeline;

[0012] And, according to the immediate ignition probability P imm , ign Delayed ignition probability P del , ign Explosion probability P exp / ign And the probability of pipeline leakage P leak Calculate the explosion risk assessment index R for leaks in hydrogen-blended natural gas pipelines.

[0013] Preferably, in step S101, according to the formula:

[0014]

[0015] Determine the lower explosive limit (L) of the leaked substance;

[0016] In the formula, c is the standard heat of combustion of 1 mol of the leaked substance at 298 K. i = {c1, c2, c3, c4}; c1 represents methane contained in the components of the leaked substance; c2 represents ethane contained in the components of the leaked substance; c3 represents propane contained in the components of the leaked substance; c4 represents hydrogen contained in the components of the leaked substance.

[0017] a, b, c, and x are the component coefficients corresponding to c1, c2, c3, and c4 respectively when the leaked substance reaches the critical condition of the lower explosive limit.

[0018] n i c is the mole fraction of the i-th component in the leaked substance; p , i is the constant-pressure specific heat of the i-th component in the leaked substance; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks.

[0019] This represents the mole fraction of each component in the reactants before the leaked substance is burned.

[0020] This represents the mole fraction of each component in the products after the leaked substance is burned.

[0021] Q r The heat radiation loss per mole of leaked material is calculated using the formula:

[0022]

[0023] Determine the thermal radiation loss;

[0024] In the formula, α is the surface radiation heat transfer coefficient; e is the irradiance determined by the surface properties of the object; σ is the Stefan-Boltzmann constant; A s Δt represents the heat transfer surface area per mole of leaked material; Δt represents the flame; T represents the heat transfer surface area per mole of leaked material. i The initial temperature of the i-th component in the leaked substance is represented; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks.

[0025] According to the formula:

[0026]

[0027] Determine the rate of material leakage;

[0028] In the formula, W j Let C be the material leakage rate corresponding to the j-th leakage scenario; j is a positive integer, C d P1 is the gas flow coefficient at the leak point; P2 is the critical pressure inside the pipe at the same cross-section as the leak hole; P2 is the external atmospheric pressure of the hydrogen-blended natural gas pipeline; M is the gas molar mass; Z is the average compressibility factor; R is the standard gas mass constant; and k is the gas adiabatic index.

[0029] Preferably, in step S102, according to the formula:

[0030] P imm.ign =[1-5000e -9.5(T / AIT) ]+[0.0024×(P) 1 / 3 / (L) 2 / 3 ]

[0031] Calculate the immediate ignition probability P imm , ign ;

[0032] In the formula, T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; AIT is the auto-ignition point of the leaked substance; P is the pressure of the leaked substance; and L is the lower explosive limit of the leaked substance.

[0033] According to the formula:

[0034]

[0035] Determine the auto-ignition point (AIT) of the leaked substance;

[0036] In the formula, n i The mole fraction of the i-th component in the leaked substance; AIT i Let be the auto-ignition point of the i-th component in the leaked substance.

[0037] Preferably, in step S102, according to the formula:

[0038]

[0039] Calculate the delayed ignition probability P del , ign In the formula, K con M is a factor that characterizes the effectiveness of ignition source control measures; mat is the contribution factor of the combustion characteristics of the leaked substance to the delayed ignition probability; L is the lower explosive limit of the leaked substance; M mag W is the contribution factor of the leakage amount of the leaked substance to the delayed ignition probability. j M represents the material leakage rate corresponding to the j-th leakage scenario; j is a positive integer; M dur The duration of the substance leak and the contribution factors of the number, density, and intensity of ignition sources to the delayed ignition probability are: G is the intensity of the ignition source, and t is the duration of the substance leak.

[0040] Preferably, in step S102, according to the formula:

[0041] P exp / ign =0.024×W j 0.435

[0042] Calculate the explosion probability P exp / ign In the formula, W j Let be the leakage rate of the substance corresponding to the j-th leakage scenario; j is a positive integer.

[0043] Preferably, in step S103, according to the formula:

[0044]

[0045] Determine the probability P of the final event of combustion and explosion of hydrogen-blended natural gas. f Among them, P leak P represents the probability of pipeline leakage. imm , ign P represents the probability of immediate ignition. del , ign P represents the probability of delayed ignition. exp / ignThe probability of an explosion; when f = 1, the probability of the final event occurring is P. f =P1, representing the probability of a fire caused by the combustion and explosion of hydrogen-blended natural gas; when f=2, the probability of the final event P f =P2, representing the probability of an explosion occurring in hydrogen-blended natural gas; when f=3, the final event probability P f =P3, representing the environmental emission probability that the combustion of hydrogen-blended natural gas will not lead to a fire or explosion.

[0046] Preferably, in step S104, according to the formula:

[0047] R = P f ·S

[0048] Calculate the explosion risk assessment index R;

[0049] In the formula, P f S is the probability of the final event of a hydrogen-blended natural gas explosion; S is the severity index; when f = 1, the probability of the final event is P. f =P1, representing the probability of a fire caused by the combustion and explosion of hydrogen-blended natural gas; when f=2, the probability of the final event P f =P2, representing the probability of an explosion occurring in hydrogen-blended natural gas;

[0050] According to the formula:

[0051]

[0052] Determine the severity index S;

[0053] In the formula, N represents the expected number of people appearing annually in the area affected by the hydrogen-blended natural gas pipeline leak; P dea The average probability of death in the entire leak area; u is the integral variable;

[0054] According to the formula:

[0055]

[0056] Determine the intermediate variable Y f ;

[0057] In the formula, Q represents the probability P of the final event of combustion and explosion of hydrogen-blended natural gas. f The corresponding thermal radiation intensity; The peak value of static overpressure; t s Exposure time.

[0058] Preferably, in step S104, according to the formula:

[0059] C:

[0060] Calculate the evaluation index C for the consequences of combustion and explosion;

[0061] In the formula, P0 is standard atmospheric pressure; P′ is the overpressure coefficient when a hydrogen-blended natural gas pipeline explodes; I′ is the impulse coefficient; E is the explosion energy when a hydrogen-blended natural gas pipeline explodes; c0 is the speed of sound; A is a comprehensive evaluation index for the final event of a leak in a hydrogen-blended natural gas pipeline being a fire, and the fire manifesting as a fireball; P s P1 is the overpressure of the leaked substance; q is the thermal radiation of the fireball; I is the explosive impulse when the hydrogen-blended natural gas pipeline explodes; P1 is the potentially lethal overpressure; q1 is the potentially lethal thermal radiation value; I1 is the potentially lethal explosive impulse.

[0062] q v The final event of a leak in a hydrogen-blended natural gas pipeline is a fire, and the fire manifests as the heat radiation value during vertical flame propagation; P w η is the partial pressure of water vapor in the atmosphere; r0 is the distance from the monitoring location to the flame surface when the final event is a fire; η is the thermal radiation coefficient; W j Let ΔH be the leakage rate corresponding to the j-th leakage scenario; c denoted as , where is the heat of combustion of the leaked substance; r is the distance from the monitoring location to the center of the flame when the final event is a fire; j is a positive integer.

[0063] q h The final event of a leak in a hydrogen-blended natural gas pipeline is a fire, and the fire is characterized by the thermal radiation value of a horizontally ejected flame; τ is the atmospheric transport rate.

[0064] According to the formula:

[0065]

[0066] Determine the overpressure coefficient P′; where R′ is the proportional distance, characterizing the proportionality coefficient between the explosion energy and the distance to the explosion center under standard atmospheric pressure; z is the distance from the monitoring location to the explosion center when the final event is an explosion;

[0067] According to the formula:

[0068]

[0069] Determine the explosion energy E; where qmix is the calorific value of the leaked substance, V is the volume of the leaked substance; r i q represents the volume fraction of component i in the leaked substance; i The calorific value of component i in the leaked substance;

[0070] According to the formula:

[0071]

[0072] Determine the impulse coefficient I′;

[0073] According to the formula:

[0074]

[0075] Determine the thermal radiation q of the fireball; where q0 is the thermal radiation flux on the surface of the fireball; R is the diameter of the fireball; r is the average distance from the target to the center of the fireball; and M is the mass of the leaked material consumed during the final event of a fire in a hydrogen-blended natural gas pipeline.

[0076] According to the formula:

[0077]

[0078] Determine the partial pressure P of water vapor in the atmosphere. w In the formula, RH represents the relative humidity of the environment; T a Ambient temperature;

[0079] According to the formula:

[0080] ΔH c =∑(r i ×ΔH i )

[0081] Determine the heat of combustion of the medium ΔH c In the formula, r i ΔH represents the volume fraction of the i-th component in the leaked substance; i Let be the heat of combustion of the i-th component in the leaked substance;

[0082] According to the formula:

[0083] τ=1-0.0565lnr

[0084] Determine the atmospheric transport rate τ; where r is the average distance from the monitoring location to the center of the fireball when the final event is a fire.

[0085] Secondly, embodiments of this application also provide a quantitative assessment system for the risk of combustion and explosion of hydrogen-blended natural gas, used to assess the risk of combustion and explosion caused by leakage in a hydrogen-blended natural gas pipeline. The assessment system includes:

[0086] The pipeline leakage parameter unit is configured to determine the lower explosive limit L of the leaked substance and the substance leakage rate W corresponding to the j-th leakage scenario when a hydrogen-blended natural gas pipeline leaks. j And the probability of pipeline leakage P leak Where j is a positive integer;

[0087] The event tree unit is configured based on the event tree concept, according to the lower explosive limit L of the leaked substance and the substance leakage rate W. jCalculate the immediate ignition probability P when a hydrogen-blended natural gas pipeline leaks. imm，ign Delayed ignition probability P del，ign And the probability of explosion P exp / ign Among them, the probability of immediate ignition represents the possibility of frictional ignition; the probability of delayed ignition represents the possibility of ignition by external energy excitation; and the probability of explosion represents the possibility of explosion caused by external energy excitation ignition.

[0088] The final event unit is configured to be based on the immediate ignition probability P. imm，ign Delayed ignition probability P del，ign And the probability of explosion P exp / ign To determine the probability of a final event of leakage in a hydrogen-blended natural gas pipeline;

[0089] The risk assessment unit is configured to assess the substance leakage rate W corresponding to the j-th leakage scenario. j Calculate the combustion and explosion consequences C of a leak in a hydrogen-blended natural gas pipeline; and, based on the immediate ignition probability P... imm，ign Delayed ignition probability P del，ign Explosion probability P exp / ign And the probability of pipeline leakage P leak Calculate the explosion risk assessment index R for leaks in hydrogen-blended natural gas pipelines.

[0090] Beneficial effects:

[0091] The quantitative assessment method and system for the combustion and explosion risk of hydrogen-blended natural gas provided in this application are used to assess the risk of combustion and explosion caused by leakage in hydrogen-blended natural gas pipelines. In this assessment method, firstly, the lower explosive limit L of the leaked substance and the substance leakage rate W corresponding to the j-th leakage scenario are determined when a hydrogen-blended natural gas pipeline leaks. j And the probability of pipeline leakage P leak Then, based on the event tree concept, according to the lower explosive limit L of the leaked substance and the substance leakage rate W corresponding to the j-th leakage scenario... j Calculate the immediate ignition probability P when a hydrogen-blended natural gas pipeline leaks. imm，ign Delayed ignition probability P del，ign Explosion probability P exp / ign Next, based on the immediate ignition probability P... imm，ign Delayed ignition probability P del，ign Explosion probability P exp / ign The probability of a final event occurring in a hydrogen-blended natural gas pipeline is determined; finally, based on the material leakage rate W corresponding to the j-th leakage scenario... j Calculate the combustion and explosion consequences C of a leak in a hydrogen-blended natural gas pipeline; and, based on the immediate ignition probability P... imm，ign Delayed ignition probability P del，ign Explosion probability Pexp / ign And the probability of pipeline leakage P leak This study calculates the explosion risk assessment index R for leaks in hydrogen-blended natural gas pipelines. By assessing the entire process from leak to fire and explosion in hydrogen-blended natural gas pipelines, and comprehensively monitoring the entire event chain of explosions, it helps to accurately grasp the risks throughout the entire process, enabling the implementation of effective prevention and control measures to minimize potential damage and economic losses, and ensuring the safety of public life and property. Attached Figure Description

[0092] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0093] Figure 1 This is a flowchart illustrating a method for quantitatively assessing the combustion and explosion risk of hydrogen-blended natural gas according to some embodiments of this application;

[0094] Figure 2 This is a schematic diagram illustrating the principle of determining the final event based on the event tree concept according to some embodiments of this application;

[0095] Figure 3 This is a pressure diagram illustrating a hydrogen-blended natural gas pipeline leak according to some embodiments of this application;

[0096] Figure 4 This is a schematic diagram of a quantitative assessment system for the combustion and explosion risk of hydrogen-blended natural gas provided according to some embodiments of this application. Detailed Implementation

[0097] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will understand that modifications and variations can be made to the present application without departing from the scope or spirit of the present application. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention should fall within the scope of protection of the embodiments of the present invention.

[0098] When a gas leak occurs, the accumulated hydrogen-blended natural gas mixes with the surrounding air, forming a large-scale flammable gas mixture. Once this gas mixture comes into contact with an ignition source, it will explode and cause serious damage. Therefore, the prevention and control of hydrogen explosion risks are crucial. However, current assessments of the explosion risks of hydrogen-blended natural gas rely primarily on qualitative or semi-quantitative methods, which have limitations in accurate prediction and risk assessment, and cannot achieve continuous monitoring and real-time evaluation.

[0099] Based on this, this application proposes a quantitative assessment method for the risk of combustion and explosion of hydrogen-blended natural gas, which addresses the shortcomings of existing technologies in risk assessment of combustion and explosion caused by leaks in hydrogen-blended natural gas pipelines. This method improves the accuracy and practicality of risk assessment for combustion and explosion caused by leaks in hydrogen-blended natural gas pipelines, enabling the control and management of potential risks at each stage of hydrogen-blended natural gas combustion and explosion accidents.

[0100] like Figures 1 to 3 As shown, the quantitative assessment method for the risk of combustion and explosion of hydrogen-blended natural gas, used for risk assessment of combustion and explosion caused by leakage in hydrogen-blended natural gas pipelines, includes:

[0101] Step S101: Determine the lower explosive limit of the leaked substance when a hydrogen-blended natural gas pipeline leaks, the substance leakage rate corresponding to the j-th leakage scenario, and the pipeline leakage probability.

[0102] In this application, the critical pressure P at the same cross-section of the pipeline as the leak hole inside the pipeline is used when a hydrogen-blended natural gas pipeline leaks. 1 The external atmospheric pressure P of the hydrogen-blended natural gas pipeline 2 To determine the leakage scenario when a hydrogen-blended natural gas pipeline leaks. Specifically, when... At that time, the leakage in the hydrogen-blended natural gas pipeline was a sonic leak; when At that time, the leakage in the hydrogen-blended natural gas pipeline was a subsonic leakage. Here, k is the gas adiabatic index.

[0103] Here, we define leakage in a hydrogen-blended natural gas pipeline as sonic leakage when j=1, and subsonic leakage when j=2. Furthermore, according to the formula:

[0104]

[0105] Determine the leakage rate of substances when a hydrogen-blended natural gas pipeline leaks. Where W... j Let C be the material leakage rate corresponding to the j-th leakage scenario; j is a positive integer, C d P is the gas flow coefficient at the leak point; 1 The critical pressure at a point inside the pipe with the same cross-section as the leak hole; P 2denoted as: ρ = external atmospheric pressure of the hydrogen-blended natural gas pipeline; M = molar mass of the gas; Z = average compressibility factor; R = standard gas mass constant; T = temperature of the leaked substance; k = gas adiabatic index.

[0106] In this application, the pipeline leakage probability P when a hydrogen-blended natural gas pipeline leaks is defined. leak The lower explosive limit (L) of the leaked substance in a hydrogen-blended natural gas pipeline leak is determined by statistical analysis of historical data on such leaks. Specifically, the formula is as follows:

[0107]

[0108] Determine the lower explosive limit L of the leaked substance in the event of a leak in a hydrogen-blended natural gas pipeline. Where, c is the standard heat of combustion of 1 mol of the leaked substance at 298 K. i = {c1, c2, c3, c4}; c1 represents methane (CH4) in the leaked substance; c2 represents ethane (C2H6) in the leaked substance; c3 represents propane (C3H8) in the leaked substance; c4 represents hydrogen (H2) in the leaked substance. The standard heat of combustion of each component in the hydrogen-blended natural gas is shown in Table 1, as follows:

[0109] Table 1 Standard heat of combustion of each component in hydrogen-blended natural gas

[0110] Components Standard heat of combustion (joules / J) <![CDATA[CH4]]> 890300 <![CDATA[C2H6]]> 1558300 <![CDATA[C3H8]]> 2217800 <![CDATA[H2]]> 285800

[0111] a, b, c, and x are the component coefficients of different components of the leaked substance—methane, ethane, propane, and hydrogen—when the leaked substance reaches the critical condition of the lower explosive limit.

[0112] n i c is the mole fraction of the i-th component in the leaked substance; p , i represents the constant-pressure specific heat of the i-th component in the leaked substance; T represents the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks. reactants represents the leaked substance; products represent the products generated after the leaked substance is burned.

[0113] Q r The heat radiation loss per mole of leaked material is calculated using the formula:

[0114]

[0115] Determine the thermal radiation loss;

[0116] In the formula, α is the surface radiation heat transfer coefficient; e is the irradiance determined by the surface properties of the object; σ is the Stefan-Boltzmann constant; A s Δt represents the heat transfer surface area per mole of leaked material; Δt represents the flame; T represents the heat transfer surface area per mole of leaked material. i The initial temperature of the i-th component in the leaked substance is represented by ; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks. The irradiance e, determined by the surface properties of the object, is determined through experiments in a constant-volume incendiary bomb by the amount of energy irradiated onto the surface of the reactor per unit time.

[0117] Step S102: Based on the event tree concept, calculate the immediate ignition probability, delayed ignition probability, and explosion probability when a hydrogen-blended natural gas pipeline leaks, according to the lower explosive limit of the leaked substance and the leakage rate of the substance corresponding to the j-th leakage scenario.

[0118] In this application, the probability of frictional ignition is represented by the immediate ignition probability; the probability of ignition by external energy excitation is represented by the delayed ignition probability; and the probability of explosion caused by external energy excitation is represented by the explosion probability. After a leak occurs in a hydrogen-blended natural gas pipeline, based on the event tree approach, the system first determines whether ignition will occur immediately, then whether ignition will occur with a delay, and finally whether an explosion will occur.

[0119] Specifically, according to the formula:

[0120] P imm.ign =[1-5000e -9.5(T / AIT) ]+[0.0024×(P) 1 / 3 / (L) 2 / 3 ]

[0121] Calculate the immediate ignition probability P after a leak in a hydrogen-blended natural gas pipeline. imm.ign In the formula, AIT is the auto-ignition point of the leaked substance; P is the pressure of the leaked substance. Here, according to the formula:

[0122]

[0123] Determine the auto-ignition point (AIT) of the leaked substance. Where, n i The mole fraction of the i-th component in the leaked substance; AIT i Let be the auto-ignition point of the i-th component in the leaked substance. The auto-ignition points of each component in the hydrogen-blended natural gas are shown in Table 2 below:

[0124] Table 2 Standard heat of combustion of each component in hydrogen-blended natural gas

[0125] Components Autoignition point (Fahrenheit) <![CDATA[CH4]]> 999 <![CDATA[C2H6]]> 881 <![CDATA[C3H8]]> 842 <![CDATA[H2]]> 752

[0126] In this application, according to the formula:

[0127]

[0128] Calculate the delayed ignition probability P after a leak occurs in a hydrogen-blended natural gas pipeline. del，ign In the formula, K con The value factor K represents the effectiveness of ignition source control measures. It is typically assigned a value based on the safety control measures implemented for the ignition source. con =0.2.

[0129] M mat M is the contribution factor of the combustion characteristics of the leaked substance to the delayed ignition probability. mag M is the contribution factor of the leakage amount of the leaked substance to the delayed ignition probability. dur The duration of the substance leakage and the contribution factors of the ignition source intensity to the delayed ignition probability are: G = ignition source intensity, t = duration of substance leakage. In this application, the ignition source intensity G is determined based on data collected by BakerRisk, as shown in Table 3. Table 3 is as follows:

[0130] Table 3 Intensities of Different Types of Ignition Sources

[0131]

[0132]

[0133] In Table 3, L represents the average number of motor vehicles in the cloud-covered area; V represents the average number of motor vehicles in the cloud-covered area; F represents the ratio of the process unit to the combustible cloud-covered area; and N represents the population in the cloud-covered area.

[0134] In this application, according to the formula:

[0135] P exp / ign =0.024×W j 0.435

[0136] Calculate the explosion probability P exp / ign .

[0137] Step S103: Determine the final event probability of a leak in the hydrogen-blended natural gas pipeline based on the immediate ignition probability, delayed ignition probability, and explosion probability.

[0138] like Figure 2 As shown, in this application, according to the formula:

[0139]

[0140] Determine the probability P of the final event of combustion and explosion of hydrogen-blended natural gas. f Among them, P leak P represents the probability of pipeline leakage. imm ,ign P represents the probability of immediate ignition. del , ign P represents the probability of delayed ignition. exp / ign The probability of an explosion; when f = 1, the probability of the final event occurring is P. f =P1, representing the probability of a fire caused by the combustion and explosion of hydrogen-blended natural gas; when f=2, the probability of the final event P f =P2, representing the probability of an explosion occurring in hydrogen-blended natural gas; when f=3, the final event probability P f =P3, representing the environmental emission probability that the combustion of hydrogen-blended natural gas will not lead to a fire or explosion.

[0141] Step S104: Calculate the combustion and explosion consequence evaluation index C for a leak in a hydrogen-blended natural gas pipeline based on the substance leakage rate corresponding to the j-th leakage scenario; and calculate the combustion and explosion risk evaluation index R for a leak in a hydrogen-blended natural gas pipeline based on the probability of immediate ignition, the probability of delayed ignition, the probability of explosion, and the probability of pipeline leakage.

[0142] In this application, according to the formula:

[0143] R = P f ·S

[0144] Calculate the explosion risk assessment index R. Where S is the severity index, specifically, according to the formula:

[0145]

[0146] Determine the severity index S. Where N is the expected number of people per year in the area affected by the hydrogen-blended natural gas pipeline leak; P... dea The average probability of death in the entire leak area (following a standard normal distribution); u is the integral variable (the integral variable of the standard normal distribution function);

[0147] According to the formula:

[0148]

[0149] Determine the intermediate variable Y f In the formula, Q represents the probability P of the final event of combustion and explosion of hydrogen-blended natural gas. f The corresponding thermal radiation intensity; This is the peak value of the static overpressure, i.e., the explosion overpressure P of the leaked substance. s peak value; t s Exposure time.

[0150] In this application, the potential final event following a leak in a hydrogen-blended natural gas pipeline is an explosion or fire. Fires primarily manifest in two forms: fireballs and jet fires. Both are related to the leakage, release, and ignition of substances, but their physical characteristics and hazards differ. Fireballs typically form from the rapid evaporation and ignition of volatile liquids or gases. The mixture formed within the fuel undergoes large-scale, enveloping combustion within a short period, producing a huge, spherical flame. Fireballs are characterized by high temperatures, intense radiant heat, and the ability to rapidly transfer heat to the surrounding environment. This type of fire poses a significant threat to personal injury and property damage, often causing widespread damage in a short time.

[0151] Jet fire, on the other hand, is formed by the ejection and ignition of high-pressure gas or liquid fuel from damaged pipes, containers, or equipment. It is a directional flame that can burn for a relatively long time, forming a high-temperature, high-speed flame stream in a specific direction. Compared to a fireball, according to the formula:

[0152] C:

[0153] Calculate the explosion consequence evaluation index C. Where P0 is standard atmospheric pressure; P′ is the overpressure coefficient when a hydrogen-blended natural gas pipeline explodes; I′ is the impulse coefficient; E is the explosion energy when a hydrogen-blended natural gas pipeline explodes; c0 is the speed of sound; A is the comprehensive evaluation index for a hydrogen-blended natural gas pipeline leak where the final event is a fire, and the fire manifests as a fireball.

[0154] P s Let be the explosion overpressure of the leaked material at the time of the final event, q be the thermal radiation of the fireball, I be the explosion impulse, P1 be the potentially lethal explosion overpressure (a constant, P1 = 0.05 MPa), and q1 be the potentially lethal thermal radiation (a constant, q1 = 12.5 kW / m²). 2 I1 is the potentially lethal explosive impulse, a constant, I1 = 72000 Pa·s; q v P represents the thermal radiation value when the final event is a fire and the fire manifests as vertical flames. w η is the partial pressure of water vapor in the atmosphere; r0 is the distance from the monitoring location to the flame surface when the final event is a fire; η is the thermal radiation coefficient; W n Let ΔH be the leakage rate corresponding to the nth leakage scenario; c q represents the heat of combustion of the leaked substance; r represents the distance from the monitoring location to the center of the flame when the final event is a fire; h τ represents the thermal radiation value when the final event is a fire and the fire manifests as horizontal flames; τ is the atmospheric transmissivity.

[0155] The explosion overpressure P of the leaked material was obtained.s Explosion impulse I, comprehensive evaluation index A, fireball thermal radiation q, and thermal radiation value q when ejected vertically. v The thermal radiation value q when the fire is emitted horizontally. h Subsequently, based on the overpressure criterion for personnel injury (as shown in Table 4), the impulse criterion for personnel injury (as shown in Table 5), the criterion for damage to buildings caused by shock wave overpressure (as shown in Table 6), the comprehensive evaluation criteria for fireballs (as shown in Table 7), and the criterion for thermal radiation hazards (as shown in Table 8), the damage caused to personnel and buildings by hydrogen-blended natural gas leaks can be effectively determined. Tables 4, 5, 6, 7, and 8 are as follows:

[0156] Table 4 Overpressure Criteria for Personal Injury

[0157]

[0158] Table 5. Criteria for Personnel Injury Impulse

[0159]

[0160] Table 6. Criteria for the Damage of Buildings by Shock Wave Overpressure

[0161]

[0162] Table 7 Comprehensive Evaluation Criteria for Fireballs

[0163]

[0164] Table 8 Guidelines for Thermal Radiation Hazards

[0165]

[0166] In this application, according to the formula:

[0167]

[0168] Determine the overpressure coefficient P′. In the formula, R′ is the proportional distance, representing the ratio of explosion energy to the distance from the explosion center under standard atmospheric pressure; z is the distance from the monitoring location to the explosion center when the final event is a fire.

[0169] According to the formula:

[0170]

[0171] Determine the explosion energy E. In the formula, qmix is the calorific value of the leaked substance, V is the volume of the leaked substance, and rm is the volume of the leaked substance. i q represents the volume fraction of component i in the leaked substance; i Let i be the calorific value of component i in the leaked substance.

[0172] According to the formula:

[0173]

[0174] Determine the impulse coefficient I′.

[0175] According to the formula:

[0176]

[0177] Determine the thermal radiation q of the fireball; where q0 is the thermal radiation flux of the fireball surface; R is the diameter of the fireball; r is the average distance from the target to the center of the fireball; and M is the mass of the leaked material consumed during the final event of a fire in a hydrogen-blended natural gas pipeline.

[0178] According to the formula:

[0179]

[0180] Determine the partial pressure P of water vapor in the atmosphere. w In the formula, RH represents the relative humidity of the environment, which is the percentage of water vapor pressure in the air to the saturated water vapor pressure at the same temperature; T a The ambient temperature.

[0181] According to the formula:

[0182] ΔH c =∑(r i ×ΔH i )

[0183] Determine the heat of combustion of the medium ΔH c In the formula, r i ΔH represents the volume fraction of the i-th component in the leaked substance; i Let be the heat of combustion of the i-th component in the leaked substance.

[0184] According to the formula:

[0185] τ=1-0.0565lnr

[0186] Determine the atmospheric transport rate τ; where r is the average distance from the monitoring location to the center of the fireball when the final event is a fire.

[0187] This application determines the immediate ignition probability, delayed ignition probability, and explosion probability of a hydrogen-blended natural gas pipeline leak based on fundamental parameters. Using an event tree approach, it first determines whether ignition is immediate, then whether ignition is delayed, and finally whether an explosion occurs. Furthermore, by combining the aforementioned evaluation indicators for the combustion and explosion consequences of a hydrogen-blended natural gas pipeline leak with these risk assessment indicators, the entire process from leak to fire and explosion is evaluated. This comprehensive monitoring of the entire event chain of hydrogen-blended natural gas combustion and explosion helps to accurately grasp the risks throughout the entire process, from leak to fire and explosion, thereby enabling the implementation of effective prevention and control measures to minimize potential damage and economic losses, and ensure the safety of public life and property.

[0188] like Figure 4 As shown in the embodiments of this application, a quantitative assessment system for the risk of combustion and explosion of hydrogen-blended natural gas is also provided. This system is used to assess the risk of combustion and explosion caused by leakage in a hydrogen-blended natural gas pipeline. The assessment system includes:

[0189] Pipeline leakage parameter unit 401 is configured to determine the lower explosive limit L of the leaked substance and the substance leakage rate W corresponding to the j-th leakage scenario when a hydrogen-blended natural gas pipeline leaks. j And the probability of pipeline leakage P leak Where j is a positive integer;

[0190] Event tree unit 402 is configured based on the event tree concept, according to the lower explosive limit L of the leaked substance and the substance leakage rate W. j Calculate the immediate ignition probability P corresponding to a leak in a hydrogen-blended natural gas pipeline. imm , ign Delayed ignition probability P del , ign And the probability of explosion P exp / ign Among them, the probability of immediate ignition represents the possibility of frictional ignition; the probability of delayed ignition represents the possibility of ignition by external energy excitation; and the probability of explosion represents the possibility of explosion caused by external energy excitation ignition.

[0191] Final event unit 403 is configured to determine the immediate ignition probability P. imm , ign Delayed ignition probability P del , ign And the probability of explosion P exp / ign To determine the probability of a final event of leakage in a hydrogen-blended natural gas pipeline;

[0192] Risk assessment unit 404 is configured to assess the substance leakage rate W corresponding to the j-th leakage scenario. j Calculate the combustion and explosion consequences C of a leak in a hydrogen-blended natural gas pipeline; and, based on the immediate ignition probability P... imm, ign Delayed ignition probability P del , ign Explosion probability P exp / ign And the probability of pipeline leakage P leak Calculate the explosion risk assessment index R for leaks in hydrogen-blended natural gas pipelines.

[0193] The hydrogen-blended natural gas explosion risk quantitative assessment system provided in this application embodiment can realize the steps and processes of the hydrogen-blended natural gas explosion risk quantitative assessment method in any of the above embodiments, and achieve the same technical effect, which will not be repeated here.

[0194] In the description of this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0195] The above embodiments are merely preferred embodiments of this application and are not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for quantitatively assessing the explosion risk of hydrogen-blended natural gas, characterized in that: Used to conduct risk assessment on explosion caused by leakage of hydrogen-blended natural gas pipeline, the assessment method includes: Step S101: Determine the lower explosion limit L of the leaked substance when the hydrogen-blended natural gas pipeline leaks, and the substance leakage rate W corresponding to the jth leakage scenario. j and pipeline leakage probability P leak ; Where j is a positive integer; according to the formula: Determine the lower explosion limit L of the leaked substance; In the formula, is the standard heat of combustion of 1 mol of the leaked substance at 298 K, c i ={c1, c2, c3, c4}; c1 represents methane contained in the components of the leaked substance; c2 represents ethane contained in the components of the leaked substance; c3 represents propane contained in the components of the leaked substance; c4 represents hydrogen contained in the components of the leaked substance; a, b, c, and x are the component coefficients corresponding to c1, c2, c3, and c4 when the leaked substance reaches the critical condition of the lower explosion limit; n i is the molar fraction of the i-th component in the leaked substance; c p , i is the constant pressure specific heat of the i-th component in the leaked substance; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; Q r For the thermal radiation loss per mole of the leaked substance, according to the formula: determining the thermal radiation loss; Where α is the surface radiation heat transfer coefficient; e is the irradiance determined by the surface properties of the object; σ is the Stefan-Boltzmann constant; A s is the heat exchange surface area per mole of the leaked substance; Δt is the flame; T i represents the initial temperature of the i-th component in the leaked substance; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; Step S102: Based on the event tree concept, according to the lower explosion limit L of the leaked substance and the leakage rate W of the substance j , calculate the immediate ignition probability P corresponding to the leakage of the hydrogen-blended natural gas pipeline imm , ign , delayed ignition probability P del , ign And the explosion probability P exp / ign ; Wherein, the immediate ignition probability represents the possibility of friction ignition, and according to the formula: P imm.ign =[1-5000e -9.5(T / AIT) ]+[0.0024×(P) 1 / 3 / (L) 2 / 3 ] Calculate the immediate ignition probability P imm，ign ; Wherein, T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; AIT is the autoignition point of the leaked substance; P is the pressure of the leaked substance; L is the lower explosion limit of the leaked substance; The delayed ignition probability represents the possibility of ignition due to external energy excitation; the explosion probability represents the possibility of explosion caused by ignition due to external energy excitation; Step S103: according to the immediate ignition probability P imm , ign , the delayed ignition probability P del , ign And the explosion probability P exp / ign , determine the final event probability of leakage of the hydrogen-blended natural gas pipeline; Step S104: calculate the substance leakage rate W corresponding to the jth leakage scenario. j , calculate the explosion consequence evaluation index C of the leakage of the hydrogen-blended natural gas pipeline; as well as, According to the immediate ignition probability P imm , ign , the delayed ignition probability P del , ign , the explosion probability P exp / ign and the pipeline leakage probability P leak , calculate the explosion risk assessment index R of the hydrogen-blended natural gas pipeline leakage.

2. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S101, According to the formula: determining a leakage rate of the substance; Where W j is the material leakage rate corresponding to the jth leakage scenario; j is a positive integer, C d is the gas flow coefficient at the leakage point; P 1 P is the critical pressure of the internal point of the pipeline with the same cross section as the leakage hole; 2 is the external atmospheric pressure of the hydrogen-blended natural gas pipeline; M is the gas molar mass; Z is the average compression factor; R is the standard gas mass constant; and k is the gas adiabatic index.

3. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S102, According to the formula: Determine the autoignition point AIT of the leaked substance; Where n i is the mole fraction of the i-th component in the leaked material; AIT i is the autoignition point of the i-th component in the leaked material.

4. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S102, According to the formula: Calculate the delayed ignition probability P del , ign ; In the formula, K con is a value factor, which represents the quality of the ignition source control measures; M mat is the contribution factor of the combustion characteristics of the leaked substance to the delayed ignition probability; L is the lower explosion limit of the leaked substance; M mag W is the contribution factor of the leakage amount of the leaked substance to the delayed ignition probability; j is the material leakage rate corresponding to the jth leakage scenario; j is a positive integer; M dur is the contribution factor of the duration of material leakage and the ignition source intensity to the delayed ignition probability; G is the ignition source intensity, and t is the duration of material leakage.

5. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S102, According to the formula: P exp / ign =0.024×W j 0.435 Calculate the explosion probability P exp / ign ; Where W j is the material leakage rate corresponding to the jth leakage scenario; j is a positive integer.

6. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S103, According to the formula: Determine the final event probability P of the hydrogen-blended natural gas explosion f ; Among them, P leak is the pipeline leakage probability; P imm , ign is the immediate ignition probability; P del , ign is the delayed ignition probability; P exp / ign is the explosion probability; When f=1, the probability of the final event occurring is P f =P1, representing the probability of fire occurrence of the hydrogen-blended natural gas explosion; When f=2, the probability of the final event occurring is P f = P2, representing the explosion probability of the hydrogen-blended natural gas explosion; When f=3, the final event probability P f =P3, characterizing the probability of environmental emission that the combustion of the hydrogen-blended natural gas does not lead to fire or explosion.

7. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 6, characterized in that: In step S104, According to the formula: R=P f ·S Calculating the explosion risk assessment index R; Where P f is the probability of the final event of the explosion of the hydrogen-blended natural gas; S is the severity index; When f=1, the probability of the final event occurring is P f =P1, representing the probability of fire occurrence of the hydrogen-blended natural gas explosion; When f=2, the probability of the final event occurring is P f = P2, representing the explosion probability of the hydrogen-blended natural gas explosion; According to the formula: Determining the severity index S; Where N is the expected number of people appearing in the hydrogen-blended natural gas pipeline leakage area each year; P dea is the average probability of death in the entire leakage area; u is the integral variable; According to the formula: Determine the intermediate variable Y f ; Where Q is the probability of the final event of the explosion of the hydrogen-blended natural gas. f The corresponding thermal radiation intensity; is the peak value of static overpressure; t s For exposure time.

8. The method for quantitatively assessing the explosion risk of hydrogen-blended natural gas according to claim 1, characterized in that: In step S104, According to the formula: Calculating the explosion consequence evaluation index C; Wherein, P0 is the standard atmospheric pressure; P′ is the overpressure coefficient when the hydrogen-blended natural gas pipeline explodes; I' is the impulse coefficient; E is the explosion energy when the hydrogen-blended natural gas pipeline explodes; c0 is the speed of sound; A is the final event of leakage of the hydrogen-blended natural gas pipeline being a fire, and the manifestation of the fire is a comprehensive evaluation index of a fireball; P s is the explosion overpressure of the leaked material when the final event of the hydrogen-blended natural gas pipeline leakage is explosion; q is the fireball heat radiation; I is the explosion impulse when the hydrogen-blended natural gas pipeline explodes; P1 is the potentially lethal explosion overpressure; q1 is the potentially lethal thermal radiation value; I1 is the potentially lethal explosion impulse; q v The final event of leakage of the hydrogen-blended natural gas pipeline is fire, and the manifestation of the fire is the thermal radiation value when the fire is sprayed in the vertical direction; P w is the partial pressure of water vapor in the atmosphere; r0 is the distance from the monitoring position to the flame surface when the final event is a fire; η is the thermal radiation coefficient; W j is the leakage rate corresponding to the jth leakage scenario; ΔH c is the combustion heat of the leaked substance; r is the distance from the monitoring position to the center of the flame when the final event is a fire; j is a positive integer; q h The final event of leakage of the hydrogen-blended natural gas pipeline is fire, and the manifestation of the fire is the thermal radiation value when the fire is sprayed in the horizontal direction; τ is the atmospheric transmission rate; According to the formula: Determining the overpressure coefficient P′; Wherein, R′ is the proportional distance, which represents the proportional coefficient between the explosion energy and the distance from the explosion center under standard atmospheric pressure; z is the distance from the monitoring position to the explosion center when the final event is an explosion; According to the formula: Determining the explosion energy E; Where, q is the calorific value of the leaked substance, V is the volume of the leaked substance; r i is the volume fraction of component i in the leaked material; q i is the calorific value of component i in the leaked substance; According to the formula: Determining the impulse coefficient I′; According to the formula: Determine the fireball heat radiation q; Wherein, q0 is the thermal radiation flux on the surface of the fireball; R is the diameter of the fireball; r is the average distance from the target to the center of the fireball; M is the mass of the leaked substance consumed when the final event of the leakage of the hydrogen-blended natural gas pipeline is a fire; According to the formula: Determine the partial pressure P of water vapor in the atmosphere w ; Where RH is the relative humidity of the environment; T a is the ambient temperature; According to the formula: ΔH c =∑(r i ×ΔH i ) Determine the heat of combustion of the medium ΔH c ; In the formula, r i is the volume fraction of the i-th component in the leaked material; ΔH i is the combustion heat of the i-th component in the leaked substance; According to the formula: τ=1-0.0565lnr Determining the atmospheric transmission rate τ; Where r is the average distance from the monitoring position to the center of the fireball when the final event is a fire.

9. A quantitative assessment system for explosion risk of hydrogen-blended natural gas, characterized in that: Used to conduct risk assessment on explosion caused by leakage of hydrogen-blended natural gas pipeline, the assessment system includes: The pipeline leakage parameter unit is configured to determine the lower explosion limit L of the leaked substance when the hydrogen-blended natural gas pipeline leaks, the substance leakage rate W corresponding to the jth leakage scenario j and pipeline leakage probability P leak ; Where j is a positive integer; according to the formula: Determine the lower explosion limit L of the leaked substance; In the formula, is the standard heat of combustion of 1 mol of the leaked substance at 298 K, c i ={c1, c2, c3, c4}; c1 represents methane contained in the components of the leaked substance; c2 represents ethane contained in the components of the leaked substance; c3 represents propane contained in the components of the leaked substance; c4 represents hydrogen contained in the components of the leaked substance; a, b, c, and x are the component coefficients corresponding to c1, c2, c3, and c4 when the leaked substance reaches the critical condition of the lower explosion limit; n i is the molar fraction of the i-th component in the leaked substance; c p , i is the constant pressure specific heat of the i-th component in the leaked substance; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; Q r For the thermal radiation loss per mole of the leaked substance, according to the formula: determining the thermal radiation loss; Where α is the surface radiation heat transfer coefficient; e is the irradiance determined by the surface properties of the object; σ is the Stefan-Boltzmann constant; A s is the heat exchange surface area per mole of the leaked substance; Δt is the flame; T i represents the initial temperature of the i-th component in the leaked substance; T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; The event tree unit is configured to be based on the event tree concept, according to the lower explosion limit L of the leaked material, according to the leakage rate W of the material j , calculate the immediate ignition probability P corresponding to the leakage of the hydrogen-blended natural gas pipeline imm , ign , delayed ignition probability P del , ign And the explosion probability P exp / ign ; Wherein, the immediate ignition probability represents the possibility of friction ignition, and according to the formula: P imm.ign =[1-5000e -9.5(T / AIT) ]+[0.0024×(P) 1 / 3 / (L) 2 / 3 ] Calculate the immediate ignition probability P imm，ign ; Wherein, T is the temperature of the leaked substance when the hydrogen-blended natural gas pipeline leaks; AIT is the autoignition point of the leaked substance; P is the pressure of the leaked substance; L is the lower explosion limit of the leaked substance; The delayed ignition probability represents the possibility of ignition due to external energy excitation; the explosion probability represents the possibility of explosion caused by ignition due to external energy excitation; The final event unit is configured to be configured according to the immediate ignition probability P imm , ign , the delayed ignition probability P del , ign And the explosion probability P exp / ign , determine the final event probability of leakage of the hydrogen-blended natural gas pipeline; The risk assessment unit is configured to calculate the material leakage rate W corresponding to the jth leakage scenario. j , calculate the explosion consequence evaluation index C of the leakage of the hydrogen-blended natural gas pipeline; as well as, According to the immediate ignition probability P imm , ign , the delayed ignition probability P del , ign , the explosion probability P exp / ign and the pipeline leakage probability P leak , calculate the explosion risk assessment index R of the hydrogen-blended natural gas pipeline leakage.

Images