Maximum credible accident scene screening method for comprehensive energy supply station

Abstract

The invention belongs to the technical field of safety risk assessment methods, and particularly relates to a maximum credible accident scene screening method for a comprehensive energy supply station. According to the method, the comprehensive energy supply station is divided into at least two leakage units; performing a first round of screening on each leakage unit; carrying out secondary screening, carrying out accident consequence simulation on a credible leakage scene, and calculating a credible factor C of each accident scene based on a damage radius, an accident probability, and population density and asset density in a preset range; and determining the maximum credible accident scene corresponding to each leakage unit by comparing the numerical value of the credible factor C. According to the method, the equipment and pipeline integrated leakage unit division principle is covered, the risk identification coverage is ensured, the risk analysis blind area is eliminated, the complex risk distribution condition of the comprehensive energy station is truly reflected, the analysis efficiency is remarkably improved through two-stage screening, the screening decision is more scientific and accurate, the engineering practicability and guidance are high, and the method is suitable for popularization and application. The prospect is wide.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of safety risk assessment methods, and particularly relates to a maximum credible accident scenario screening method for a comprehensive energy supply station. BACKGROUND

[0002] With the diversification of energy structure, comprehensive energy supply stations integrating multiple fuel refueling functions are increasingly popular. Such stations have complex processes, dense equipment and pipelines, and significant differences in the physicochemical properties and risk characteristics of different fuels, resulting in a large number of potential accident scenarios and complex risk coupling effects.

[0003] The screening of maximum credible accident scenarios (MAS) is a core link of industrial safety risk assessment, emergency management and environmental impact assessment, and is a key prerequisite for quantitative risk assessment and the development of effective safety measures. Existing MAS screening methods mainly include two-level screening method, quantitative screening of HyRAM+ and LHS, risk assessment based on credibility theory, and dynamic risk assessment based on monitoring data and OOBN.

[0004] Some studies combine the hydrogen risk assessment model (HyRAM+) with Latin hypercube sampling (LHS), quantify uncertainty, and introduce the potential loss of life (PLL) index to screen the highest-risk scenarios. The study found that the complete rupture of the hydrogen compressor unit pipeline leading to jet fire and explosion is the most credible accident, and the explosion has a more significant impact on property loss. Some studies propose a dynamic identification of potential risks and pre-accidents at natural gas transmission and distribution stations based on object-oriented Bayesian networks (OOBN) and real-time monitoring data. Chinese patent CN111815111A discloses a regional comprehensive energy expansion planning method for pipeline risk level, which is based on a multi-energy flow model and its solution results, cooperates with the upper limit of the flow under the expansion scheme of different pipeline types as a constraint condition, establishes an energy pipeline risk level evaluation index based on complex network theory, and processes wind power uncertainty through fuzzy chance constraints. The existing screening methods have the following limitations: (1) Unreasonable analysis unit: Traditional methods often take a single device as the analysis object, ignoring the higher leakage risk of pipelines, flanges, valves and other connecting parts, which are the areas where accidents frequently occur.

[0005] (2) Subjective screening criteria: The scene screening process relies heavily on expert experience, lacks uniform and objective quantitative screening criteria, and the results vary from person to person, with poor repeatability.

[0006] (3) Lack of adaptability to multi-fuel systems: For hydrogen refueling stations, a complete rupture of the piping of the hydrogen compressor unit can lead to jet fire and explosion. Existing methods are mostly designed for single fuel stations and are difficult to handle the complex situation of different fuels (such as jet fire of hydrogen and pool fire of methanol) in a comprehensive energy supply station.

[0007] (4) Weak guidance on resource allocation: Some methods (such as WMAS) pay too much attention to extremely small probability events, and the "worst case" selected has limited practical guiding significance for daily risk management and optimization of emergency resources.

[0008] Therefore, there is an urgent need in the art for a method that can systematically and quantitatively screen out "reasonably possible and serious" accident scenarios to support precise risk management and emergency preparation for comprehensive energy supply stations. SUMMARY

[0009] The problem to be solved by the present application is to provide a method for screening the maximum credible accident scenarios of a comprehensive energy supply station, which constructs an analysis framework based on the integration of "equipment-piping" units, more realistically reflects the distribution of leakage risks, and can effectively identify the most representative risk scenarios of each process unit, providing reliable target scenarios for subsequent consequence simulation, risk quantification, and safety measure development.

[0010] The technical scheme adopted is: A method for screening the maximum credible accident scenarios of a comprehensive energy supply station, comprising the following steps: S1. Dividing leakage units: determining a comprehensive energy supply station, dividing the comprehensive energy supply station into at least two leakage units, each of the leakage units comprising core process equipment and its connected piping, valves, and flanges; S2. First screening: for each leakage unit, calculating the accident occurrence probability under different leakage diameters to determine the acceptable leakage probability, and performing the first round of screening based on a preset probability threshold; for the scenarios that pass the leakage probability screening, performing the second round of screening based on the maximum leakage principle to further determine the credible leakage scenarios of each leakage unit; S3. Second screening: performing accident consequence simulation on the credible leakage scenarios obtained in step S2 to calculate the damage radius of thermal radiation and overpressure; based on the damage radius, accident probability, population density and asset density within a preset range, calculating the credibility factor C of each accident scenario; by comparing the values of the credibility factor C, determining the maximum credible accident scenario corresponding to each leakage unit.

[0011] Preferably, the fuels involved in the comprehensive energy supply station include at least two of hydrogen, compressed natural gas, methanol, gasoline, and diesel.

[0012] Preferably, the step S2, the accident occurrence probability is calculated in the following way: For immediate ignition accident, ; For delayed ignition accident, ; Wherein, is the leakage probability, is the environmental factor joint frequency, is the leakage direction frequency, is the immediate ignition probability, is the delayed ignition probability.

[0013] Preferably, the leakage probability is determined based on the failure statistics of the target leakage unit and the working condition; the environmental factor joint frequency is determined according to the meteorological statistics of the region where the target site is located; the immediate ignition probability and the delayed ignition probability are determined by ignition source event tree analysis.

[0014] As a further preferred, the determination method of the leakage probability, the environmental factor joint frequency, the leakage direction frequency, and the immediate ignition probability and the delayed ignition probability is as follows: (1) Determination of the leakage probability: For the potential leakage sites of the equipment, pipelines, valves and flanges in the leakage unit, for the failure rate expression mode of "counting by element", let the failure rate of the first class element be , unit: times / (year·piece), indicating the expected number of leaks of a single first class element in a year, the number of this class of elements in the target leakage unit is , then the total leakage frequency of the leakage unit is , indicating the expected number of leaks of any aperture in the leakage unit in a year, unit: times / year; expressed by formula as: ; Wherein, is the total number of element categories in the leakage unit;

[0015] For the failure rate expression mode of "counting by length", let the failure rate of the first class pipeline be , unit: times / (year·m), indicating the expected number of leaks of a single first class pipeline in a year, the length of this class of pipelines in the target leakage unit is , unit: m, then the total leakage frequency is expressed by formula as: ; In the formula, the total leakage frequency Afterwards, the total leakage frequency is allocated to different leakage aperture types, which are denoted as (for example, small aperture, medium aperture, large aperture, etc.), under the condition of leakage, the aperture type appears with a proportion of (dimensionless), satisfying , and , then the aperture type corresponds to a leakage frequency , which is: ; When the evaluation period is one year, the frequency can be further converted into the annual leakage probability, assuming that the evaluation period is , in years, then the annual leakage probability of the aperture type can be approximately expressed as a Poisson process: ; where is an exponential function, when , the approximate relationship can be further used.

[0016] (2) Determination of environmental factor joint frequency: Based on at least one year of hourly meteorological observation data, the wind direction, wind speed and atmospheric stability are classified, and the combination of different wind direction intervals, wind speed intervals and stability levels is taken as an environmental working condition unit; Assuming that the wind direction is divided into the first wind direction interval (for example, corresponding to a certain azimuth sector), the wind speed is divided into the first wind speed interval, and the atmospheric stability level is the first level, then the number of hours of the environmental working condition unit defined by appears in the statistical period is , in hours, and the total number of hours in the statistical period is , in hours, then the joint occurrence frequency of the working condition unit , which represents the probability of being in working condition at a random time, is: ; The , that is, the environmental factor joint frequency under the working condition .

[0017] (3) Determination of leakage direction frequency: Taking the leakage point as the center, a plurality of typical leakage directions are preset, the leakage direction is divided into the first direction (such as “up”, “down”, “horizontal to a side”, etc.), and each direction is​ weighting factor (dimensionless, reflects the degree to which the leak jet is more prone to this direction); By summing up the weighting factors of each direction and normalizing, the leak direction frequency of each direction can be obtained i.e. ; wherein, is the preset total number of leak directions, when the weighting factor of each direction is uniformly taken as 1, thus obtaining: .

[0018] (4) Determination of ignition probability: Taking “leakage event occurrence” as the top event, comprehensively considering the combustible cloud formation condition, the types and spatial distribution of ignition sources in the leakage area, and the personnel activity frequency factor, an event tree of leakage-diffusion-ignition is constructed, and the conditional probability of each branch of the event tree is given based on historical statistical data or the recommended value in the relevant safety specification; Let the probability of forming a combustible cloud after the occurrence of a leakage event be (dimensionless, represents the probability of forming a combustible cloud of the leaked substance within a certain time and space range), the conditional probability of immediate ignition under the condition of forming a combustible cloud be (dimensionless, represents the probability of being ignited by a nearby ignition source in a very short time under the premise of “a combustible cloud has been formed”), the conditional probability of delayed ignition within a given time window under the condition of not occurring immediate ignition but having formed a combustible cloud be (dimensionless, represents the probability of being ignited by a distant ignition source under the premise of “a combustible cloud exists and immediate ignition has not occurred”), then the immediate ignition probability (dimensionless, represents the overall probability of the path from leakage to immediate ignition) and the delayed ignition probability (dimensionless, represents the overall probability of the path from leakage to delayed ignition) are respectively represented as: ; ; wherein, , respectively correspond to the joint probability of the “immediate ignition path” and the “delayed ignition path” in the event tree, and the sum of the joint probabilities of other paths in the event tree is the probability of “no ignition”.

[0019] The above conditional probabilities can be determined in combination with historical statistical data, experience of similar devices, or recommended values in relevant safety specifications.

[0020] Preferably, in the step S2, the calculation formula of the maximum possible leakage amount is: Maximum possible leakage amount = min (leakage rate x leakage time, unit capacity + replenishment amount); Wherein, the leakage rate is the medium outflow rate of the target leakage unit under the corresponding leakage aperture and operating conditions, expressed in the form of mass flow or volume flow; the leakage time is the upper limit of the duration from the start of leakage to the adoption of isolation, cutting-off measures or the termination of material leakage; the unit capacity is the leakable medium mass contained in the target leakage unit at the start of leakage; the replenishment amount is the medium mass replenished to the target leakage unit from the upstream equipment or pipeline within the leakage time and possibly further leaked, which can be zero in the absence of upstream replenishment sources; For the same leakage unit, the scenario with the maximum leakage amount is selected as the credible leakage scenario of the unit.

[0021] Preferably, in the step S3, when considering thermal radiation, the physical effect intensity is the thermal radiation flux I When considering explosion, the physical effect intensity is the explosion peak overpressure P ; The evaluation domain Ω is divided into a plurality of grid units, and the area of the kth grid unit is △ S k A representative point is selected as a calculation point within the kth grid unit; the physical effect intensity at the representative point is output or calculated by the accident consequence simulation software, wherein the physical effect intensity under thermal radiation conditions is denoted as I k , and the physical effect intensity under explosion conditions is denoted as P k , I th 、P th thermal radiation flux threshold value, explosion peak overpressure threshold value, and the area S of the physical effect range is the area that satisfies I k ≥ I th or P k ≥ P th the area of the region ； S is obtained according to the following formula: When it is a thermal radiation condition, ; When it is an explosion condition, ; Wherein, K is the total number of grid units, and the value range is 100 to 1000; 1(*) is an indicator function, which takes 1 when the condition in the parentheses is true, and 0 otherwise. On this basis, the calculation formula of damage radius R is: ; Wherein, R is the radius of the circular area with the accident source as the center, which is equivalent to the range of physical effect under the threshold of heat radiation flux or the threshold of explosion peak overpressure, S is the area of the physical effect range, and π is the circular constant; The I th 、P th According to the consequence impact threshold determined in Appendix G1 and G2 of GB / T 37243-2019 “Risk Criteria for Hazardous Chemical Production Devices and Storage Facilities”, or according to the internationally recognized engineering guide (Methods for the Calculation of Physical Effects, also known as the Dutch TNO Purple Book).

[0022] Preferably, a model of the credibility factor C is established, and the credibility factor C is quantitatively evaluated by the following formula: ; wherein, , ; ; wherein, , ; ; Wherein, is the asset impact index, is the personnel impact index.

[0023] Preferably, the accident probability range is the value interval of the accident probability of each accident scene within a predetermined evaluation period, and when evaluating different candidate sites, according to the accident probability calculation formula, the environmental factor joint frequency, the leakage direction frequency and the ignition probability corresponding to each candidate site are selected by comprehensively calculating the leakage probability, the environmental factor joint frequency, the leakage direction frequency and the ignition probability, and the parameters related to the site are substituted into the accident probability calculation formula, thereby obtaining the accident probability range corresponding to each candidate site; The asset density is the ratio of the total asset value of buildings, structures and related equipment, infrastructure within a unit area range to the area, which is expressed in the form of monetary amount per square meter; The population density is the ratio of the number of resident population and floating population within a specific period within a unit area range to the area, which is expressed in the form of the number of people per square meter.

[0024] Preferably, the preset probability threshold is 1x10 -6The preset probability threshold is determined based on a safety level of the comprehensive energy supply station, an industry standard, and risk acceptable criteria.

[0025] Compared with the prior art, the present application has the following advantages: (1) comprehensiveness and systematicness: the method of the present application covers the principle of dividing the integrated leakage unit of equipment and pipelines, analyzes the core process equipment, the pipelines connected thereto, the valves, and the flanges as a whole analysis unit, ensures the coverage of risk identification, eliminates the "blind area" of risk analysis, and truly reflects the complex risk distribution condition of the comprehensive energy station.

[0026] (2) objectivity and high efficiency: the present application establishes a "two-stage quantitative screening" mechanism, quickly eliminates scenes with extremely low occurrence probability and no engineering significance through the first stage (probability screening), and screens out the most serious representative scene in the same unit based on the maximum leakage principle through the second stage (leakage amount screening). The two-stage screening greatly reduces subjective randomness and significantly improves analysis efficiency.

[0027] (3) scientificity and precision: the present application innovatively proposes a "credible factor C" comprehensive evaluation model, simultaneously considers multiple sources of risk, and for the first time, incorporates population density and asset density as core variables into the screening model, so that the screening result can better reflect the real impact of the accident on the specific surrounding environment, and the two different dimension indicators of personnel casualty and asset loss are fused into a unified and comparable comprehensive risk indicator (C value), so that the screening decision is more scientific and precise, and the limitation of traditional single dimension is broken.

[0028] (4) strong engineering practicability and guidance: the "maximum credible accident scene" screened by the present application is no longer simply "maximum probability" or "most serious consequence", but a scene with the highest risk value, i.e. the best balance point after the environmental sensitivity weighting of the occurrence possibility and the consequence severity, and the screening result can directly serve the safety decision, the preparation of emergency plan, and the allocation of emergency resources, etc.

[0029] (5) universality and scalability: the present application provides a methodology framework, and the unit division, two-stage screening, and credible factor model thereof can be seamlessly applied to the comprehensive energy supply station containing any two or more fuels such as hydrogen, compressed natural gas, methanol, gasoline, and diesel, and has good popularization prospect and industry adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the overall flowchart of the method of the present application.

[0031] Figure 2 is the hydrogen leakage event tree analysis diagram in Example 1 of the present application. DETAILED DESCRIPTION

[0032] The drawings are only for illustrative purposes; the present application will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that for well-known common sense or prior art, it can be omitted. GB / T 37243-2019 “Risk Criteria for Hazardous Chemical Production Devices and Storage Facilities” or internationally recognized engineering guidelines (Methods for the Calculation of Physical Effects, also known as the Dutch TNO Purple Book) can be obtained through conventional commercial channels. The area of the physical effect range is calculated under the preset threshold of thermal radiation flux or explosion overpressure, which can be obtained by the above-mentioned criteria or purple book.

[0033] Embodiment 1.

[0034] As Figure 1 shown, a comprehensive energy supply station maximum credible accident scenario screening method takes a hydrogen energy supply system of a certain comprehensive energy supply station as an example, and includes the following steps:

[0035] S1, leak unit division.

[0036] The process flow of its hydrogen energy supply station is divided into multiple leak units, including: unit 0101: pipeline system from hydrogen pipe bundle container to valve A; unit 0102: pipeline system from valve A to valve B, including compressor equipment; unit 0103: pipeline system from valve B to hydrogen storage tank; unit 0201: pipeline system from hydrogen storage tank to hydrogen refueling machine.

[0037] The division principle is to ensure that each unit is relatively independent in function and space, and contains equipment and its key connecting components.

[0038] S2, primary screening.

[0039] This step aims to screen out “credible leakage scenarios” with representative leakage quantities and non-extremely low occurrence probabilities from all possible leakage scenarios.

[0040] Probability screening. The leakage probability is determined based on the failure statistics of the target leakage unit and the working condition.

[0041] The calculation method of accident occurrence probability is: for immediate ignition accident, ; for delayed ignition accident, ; wherein, is the leakage probability, is the combined frequency of environmental factors, is the leakage direction frequency, is the immediate ignition probability, is the delayed ignition probability.

[0042] For potential leak locations such as equipment, pipes, valves, and flanges within a leak unit, data sources including national standard GB / T 37243-2019 and HyRAM software are used to obtain the probability of different leak pore sizes (e.g., hydrogen leaks at 0.01%, 0.1%, 1%, 10%, and 100% pore sizes). This is combined with event tree analysis (e.g.,...). Figure 2 (As shown) Determine the ignition probability and calculate the final accident probability. Set the threshold to 1×10-1 -6 Scenarios with a probability lower than this value are excluded. For example, the probability of a 0.01% pore size leakage accident in unit 0102 is 2.52 × 10⁻⁶. -4 Less than 1×10 -5 Retained (based on the ALARP (Minimum Reasonable Feasibility Principle) requirements for process safety and industrial applications, exceeding 1×10 -5 This is an unacceptable area; the risk is generally unacceptable. 1×10 -5 (This indicates that the annual probability of an individual's death due to an accident scenario is higher than one in 100,000, and the risk is considered unacceptable). Conversely, the probability of a 10% orifice leakage accident is less than one in 100,000. -6 If it is, then it will be removed.

[0043] Leakage screening: Based on the principle of maximum leakage, calculate the maximum possible leakage of each scenario within each unit that passes the probability screening.

[0044] The formula is: Maximum possible leakage = min(Leakage rate × Leakage time, Unit capacity + Replenishment amount). For the same unit, only the scenario with the largest maximum possible leakage is retained as the "credible leakage scenario" for that unit. For example, in unit 0102, the maximum possible leakage calculated for 0.01%, 0.1%, and 1% aperture leakage is 0.331 kg, so all of them can be used as representative leakage scenarios for that unit and enter the next round of screening.

[0045] S3, Secondary screening.

[0046] This step aims to conduct a deeper evaluation of the initially selected credible leakage scenarios to determine the "maximum credible incident scenario".

[0047] Consequence simulation: Using specialized consequence simulation software, each credible leak scenario is simulated to calculate the damage radius of the accident consequences (such as jet fire, explosion, pool fire, etc.). When thermal radiation is considered, the physical effect intensity is the thermal radiation flux. I When considering the physical effects intensity during an explosion, the peak overpressure of the explosion is... P ; The evaluation domain Ω is divided into several grid cells, and the area of ​​the k-th grid cell is Δ. S k, the representative point in the kth grid cell is selected as the calculation point; the physical effect intensity at the representative point is output by the accident consequence simulation software or calculated, wherein the physical effect intensity in the thermal radiation working condition is denoted as I k , the physical effect intensity in the explosion working condition is denoted as P k , I th 、P th respectively, the thermal radiation flux threshold value, the explosion peak overpressure threshold value, and the area S of the physical effect range satisfies I k ≥ I th or P k ≥ P th the area of the region ； S is obtained according to the following formula: when it is the thermal radiation working condition, ; when it is the explosion working condition, ; wherein K is the total number of grid cells, 1(*) is an indicator function, which is 1 when the condition in the parentheses is met, and 0 otherwise; On this basis, the calculation formula of the damage radius R is: ; wherein R is the radius of the circular region with the accident source as the center and equivalent to the physical effect influence range under the thermal radiation flux threshold value or the explosion peak overpressure threshold value, S is the area of the physical effect range, and π is the circular constant; the I th 、P th According to the consequence influence threshold values in Appendix G1 and G2 of GB / T 37243-2019 “Risk Criteria for Hazardous Chemicals Production Devices and Storage Facilities”, or according to the internationally recognized engineering guide (Methods for the Calculation of Physical Effects, also known as the Dutch TNO Purple Book).

[0048] Statistical physical meaning: the area of all grid cells with physical effect intensity reaching or exceeding the threshold value is accumulated, and the obtained area is the physical effect range area S; this process is equivalent to the implementation method of “obtaining the physical effect intensity distribution and calculating the area satisfying the threshold value”. The grid resolution can be set according to the evaluation accuracy requirement, and the finer the grid division, the more accurate the area statistical result; I k or Pk The output is calculated by the post-accident consequence simulation software under corresponding scenarios and threshold conditions, hydrogen scenarios are preferably implemented using HyRAM, and PHAST software is used for other fuels.

[0049] Comprehensive evaluation of the credibility factor: Collect the population distribution and asset distribution data around each unit. Apply the established model of the credibility factor C to calculate the credibility factor C of each accident scenario. This model quantifies the comprehensive risk intensity caused by the accident to the surrounding environment by separately solving the asset impact index A and the personnel impact index B, and uses the dimension coordination coefficient k to ensure the dimensionless comparability of the evaluation results.

[0050] Scenario determination: Compare the credibility factor C values of all accident scenarios within the same leaking unit. Select the scenario with the largest C value (or select the scenario with the largest C value according to different accident types) as the "maximum credible accident scenario" of the unit.

[0051] Apply the method of the present application to evaluate a certain comprehensive energy supply station, determine all the leaking units of the mixed energy supply station, and take the 0102 unit as an example to show the results: First, according to the aforementioned accident scenario identification and screening method, determine the credible accident scenarios of the 0102 unit under different leakage diameters (0.01%, 0.1%, 1%) and different accident types (jet fire, explosion), and calculate the accident probability of each scenario using device failure data and working conditions. Then, according to the risk quantification formula proposed in the present application, calculate the asset risk factor A and the personnel risk factor B of each credible accident scenario. Specifically, the asset impact index A and the personnel impact index B of a single accident scenario are defined as: wherein, is the physical effect impact range of the accident scenario, is the accident probability, is the asset density, is the population density. According to the above formula, substitute the physical effect range and density parameters of each scenario of the 0102 unit to obtain the asset risk factor A and the personnel risk factor B.

[0052] Take the 0102 unit 0.01% leakage, jet fire accident scenario as an example, the accident probability of this scenario is P = 2.52 × 10 -4 , the physical effect impact range is , the asset density is , and the asset risk factor is: ; After substituting the actual parameters, we get​​​​ .

[0053] Similarly, let the population density be... The personnel risk factor is: ; The calculation yielded the following results: .

[0054] After obtaining A and B for a single scenario, the credibility factor calculation formula proposed in this invention is used to comprehensively characterize the scenario risk: ; in, For personnel risk weighting coefficients, in this embodiment, we take... .

[0055] Taking the 0.01% leakage and jet fire scenario in unit 0102 as an example, substituting A and B above, we get: ; ; ; ; Obtain the credibility factor corresponding to this scenario. .

[0056] Taking the 0.1% leakage and explosion accident scenario of unit 0102 as an example, the probability of the accident is: Based on the physical effect range and asset / population density parameters, asset risk factors can be obtained respectively: ; Personnel risk factors: ; Substitute into the confidence factor formula and take :

[0057] ; ; ; .

[0058] The confidence factor for the explosion scenario with 0.1% leakage in cell 0102 was obtained. .

[0059] Using the same method, the values ​​for the 0.1% leakage jet fire scenario in element 0102 were obtained, where A = 1.43 × 10⁻⁶. -5 B = 4.08 × 10 -7 C = 4.32 × 10 -5And a 1% leak, jet fire, and explosion scenario, A = 8.38 × 10 -6 B = 2.39 × 10 -7 C = 2.54 × 10 -5 .

[0060] The screening results for Unit 102 are shown in Table 1.

[0061] Table 1. Results of primary and secondary scenario screening for Unit 102 accident scenarios:

[0062] The data obtained from the secondary screening is shown in Table 2.

[0063] Table 2. Calculation results of credibility factors A, B, and C for the accident scenario in Unit 102:

[0064] The results were compared, and the most credible accident scenarios were selected, as shown in Table 3. The results show that among jet fire accidents, the 0.01% leakage scenario in unit 0102 has the highest credibility factor; among explosion accidents, the 0.1% leakage scenario in unit 0102 has the highest credibility factor. This indicates that the pipeline system from valve A to valve B, including the compressor equipment, represents the most credible accident scenario for this hybrid integrated energy supply station.

[0065] Table 3. Results of the screening of the most credible incident scenarios: Accident type Unit Leak aperture Jet fire 102 0.01% leak Explosion 102 0.1% leak

[0066] Furthermore, the credibility factor C of each unit, accident type, and leakage aperture scenario in the entire station is compared and ranked to obtain the maximum credibility accident scenario of the integrated energy supply station.

[0067] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for screening the maximum credible accident scenario of an integrated energy supply station, characterized in that, Includes the following steps: S1. Delineate leakage units: Determine the integrated energy supply station and divide the integrated energy supply station into at least two leakage units. Each leakage unit includes core process equipment and its connected pipes, valves and flanges. S2. First screening: For each leakage unit, calculate the probability of an accident under different leakage apertures to determine the acceptable leakage probability, and conduct the first round of screening based on the preset probability threshold; for the scenarios that pass the leakage probability screening, conduct the second round of screening based on the principle of maximum leakage amount to further determine the credible leakage scenario of each leakage unit; S3. Secondary screening: Simulate the accident consequences of the credible leakage scenarios obtained in step S2, and calculate the damage radius of thermal radiation and overpressure; based on the damage radius, accident probability, population density and asset density within the preset range, calculate the credibility factor C of each accident scenario; by comparing the values ​​of the credibility factor C, determine the maximum credible accident scenario corresponding to each leakage unit.

2. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 1, characterized in that, The integrated energy supply station involves at least two of the following fuels: hydrogen, compressed natural gas, methanol, gasoline, and diesel.

3. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 2, characterized in that, In step S2, the probability of an accident occurring is calculated as follows: For immediate ignition accidents ; For delayed ignition accidents ; in, For the probability of leakage, For the combined frequency of environmental factors, For the leakage direction frequency, For instantaneous ignition probability, This is the probability of delayed ignition.

4. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 3, characterized in that, The leakage probability is determined based on the failure statistics and operating conditions of the target leakage unit; the combined frequency of environmental factors is determined based on the meteorological statistics of the area where the target site is located; the instantaneous ignition probability and the delayed ignition probability are determined through ignition source event tree analysis.

5. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 4, characterized in that, The methods for determining leakage probability, combined frequency of environmental factors, leakage direction frequency, instantaneous ignition probability, and delayed ignition probability are as follows: (1) Determination of leakage probability: For potential leak points in equipment, pipes, valves, and flanges within a leak unit, for failure rate expressed using a "component-based count" method, let the number of leaks be... The failure rate of this type of component is , indicating a single first The expected number of times a type of component will leak within a year, and the number of this type of component in the target leaking unit. If there are 1 leak, then the total leakage frequency of the leaking unit is 1. This represents the expected number of leaks of any orifice diameter occurring in the leaking unit within one year, expressed as times per year; it can be expressed by the formula: ； in, This represents the total number of component categories within the leaking unit. For the failure rate representation method using "counting by length", let the first... The failure rate of pipes is The unit is times / (year·m), indicating the number of times per unit length. The expected number of leaks of this type of pipeline within a year, and the length of this type of pipeline in the target leak unit. The unit is meters (m), then the total leakage frequency is... Expressed as a formula: ； After obtaining the total leakage frequency ƒ leak,total Then, the total leakage frequency is allocated according to different leakage orifice types. Let the leakage orifice type be h, and the proportion of orifice type h occurring under leakage conditions is: ,satisfy ,and Then the leakage frequency corresponding to aperture type h for: ； When the evaluation period is one year, the frequency is converted into the annual leakage probability. Let the evaluation period be... If the unit is years, then the aperture type Annual leakage probability The Poisson process can be approximated as follows: ； Where exp is an exponential function, when When using approximate relationships ; (2) Determination of the combined frequency of environmental factors: Based on at least one year of hourly meteorological observation data, wind direction, wind speed and atmospheric stability are classified, and combinations of different wind direction ranges, wind speed ranges and stability levels are used as environmental condition units. Let the wind direction be divided into the first... The wind direction range is divided into several wind speed zones. The wind speed range has an atmospheric stability level of [number]. Level, then by The number of hours that the commonly defined environmental condition unit occurred during the statistical period is: The unit is hours, and the total number of hours during the statistical period is... If the unit is hours, then the joint occurrence frequency of this operating condition unit is... This indicates the operating condition at a random moment. The probability is: ； The That is, as in working condition The combined frequency of environmental factors; (3) Determination of leakage direction frequency: Centered on the leak point, several typical leak directions are pre-defined, and the leak directions are divided into the following categories: There are several directions, and for each direction Assign weights ; By summing and normalizing the weights for each direction, the leakage direction frequency in each direction can be obtained. ,Right now: ； in, Given a preset total number of leakage directions, and the weights of each direction... We set the value to 1 for all values, and thus we get: ； (4) Determination of ignition probability: Taking "the occurrence of a leak event" as the top event, and comprehensively considering the conditions for the formation of flammable clouds, the types and spatial distribution of ignition sources in the leak area, and the frequency of human activities, an event tree of leak-diffusion-ignition is constructed, and conditional probabilities are assigned to each branch of the event tree based on historical statistical data or recommended values ​​in relevant safety specifications. Assume the probability of a flammable cloud forming after a leak occurs is . The conditional probability of instantaneous ignition under the condition of forming a combustible cloud is: Given that a combustible cloud has formed without immediate ignition, the conditional probability of delayed ignition occurring within a given time window is: Then the instantaneous ignition probability and delayed ignition probability They are represented as follows: ； ； in, , The probability of "no ignition" corresponds to the joint probability of "immediate ignition path" and "delayed ignition path" in the event tree, respectively. The sum of the joint probabilities of other paths in the event tree is the probability of "no ignition".

6. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 5, characterized in that, In step S2, the formula for calculating the maximum possible leakage is: Maximum possible leakage amount = min (leakage rate × leakage time, unit capacity + replenishment amount); Wherein, the leakage rate is the media leakage rate of the target leakage unit under the corresponding leakage orifice diameter and operating conditions, expressed in the form of mass flow rate or volumetric flow rate; the leakage time is the upper limit of the duration from the start of leakage to the implementation of isolation, cut-off measures or termination of material release in an uncontrolled state; the unit capacity is the amount of releasable media contained in the target leakage unit at the start of leakage; the replenishment amount is the amount of media replenished to the target leakage unit by upstream equipment or pipelines during the leakage time and may be further leaked, and the replenishment amount can be zero if there is no upstream replenishment source; For the same leaking unit, the scenario with the largest leakage is selected as the reliable leaking scenario for that unit.

7. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 5, characterized in that, In step S3, when thermal radiation is considered, the intensity of the physical effect is the thermal radiation flux. I When considering the physical effects intensity during an explosion, the peak overpressure of the explosion is... P ; The evaluation domain Ω is divided into several grid cells, and the area of ​​the k-th grid cell is Δ. S k A representative point is selected within the k-th grid cell as the calculation point; the intensity of the physical effect at the representative point is obtained by outputting or calculating from the accident consequence simulation software, wherein the intensity of the physical effect under thermal radiation conditions is denoted as... I k The intensity of the physical effect under explosion conditions is denoted as P k , I th 、 P th These are the thermal radiation flux threshold, the explosion peak overpressure threshold, and the area S of the physical effect range, which satisfies... I k ≥ I th or P k ≥ P th area ； S is obtained by statistical analysis using the following formula: When operating under thermal radiation conditions ; When in an explosive condition ; Where K is the total number of grid cells, and 1 (*) is an indicator function that takes the value 1 when the condition in parentheses is true, and 0 otherwise; Based on this, the formula for calculating the damage radius R is: ; Where R is the radius of the circular region centered on the accident source and equivalent to the range of physical effect influence under the damage threshold, S is the area of ​​the physical effect range, and π is pi. The I th 、P th The consequences impact thresholds were determined in accordance with Appendix G1 and G2 of GB / T 37243-2019 "Risk Baseline for Hazardous Chemical Production and Storage Facilities".

8. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 7, characterized in that, Establish a model for the credibility factor C and quantify it using the following formula: ； in, , ; ； in, , ; ； in, For asset impact index, The personnel impact index.

9. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 8, characterized in that, The accident probability range is the range of values ​​for the probability of occurrence of each accident scenario within a predetermined evaluation period. When evaluating different candidate sites, the accident probability is calculated by comprehensively considering the leakage probability, the combined frequency of environmental factors, the leakage direction frequency, and the ignition probability according to the accident probability calculation formula. The parameters related to the combined frequency of environmental factors, the leakage direction frequency, and the ignition probability of each candidate site are selected and substituted into the accident probability calculation formula to obtain the accident probability range corresponding to each candidate site. Asset density is the ratio of the total asset value of buildings, structures and related equipment and infrastructure within a unit area to that area, expressed in monetary terms per square meter. Population density is the ratio of the number of permanent residents and the number of transient residents within a unit area to that area during a specific period, expressed in terms of people per square meter.

10. The method for screening the maximum credible accident scenario of an integrated energy supply station according to claim 2, characterized in that, The preset probability threshold is 1×10 -6 ; The preset probability threshold is determined based on the safety level of the integrated energy supply station, industry standards, and risk acceptable criteria.

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