A method for screening maximum credible accident scenarios of an integrated energy supply station

Abstract

The present application belongs to the technical field of safety risk assessment method, and particularly relates to a kind of integrated energy supply station maximum credible accident scene screening method.The method divides integrated energy supply station into at least two leakage units;First round screening is carried out for each leakage unit;Second screening is carried out, credible leakage scene is simulated after accident, and based on damage radius, accident probability, population density and asset density in preset range, credible factor C of each accident scene is calculated;By comparing the value of the credible factor C, the maximum credible accident scene corresponding to each leakage unit is determined.The method covers the integrated leakage unit division principle of equipment and pipeline, ensures the coverage of risk identification, eliminates the "blind area" of risk analysis, truly reflects the complex risk distribution of integrated energy station, two-stage screening significantly improves the analysis efficiency, makes the screening decision more scientific and accurate, has strong engineering practicability and guidance, and has broad prospects.

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 maximum 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 flow upper limit of different pipeline types under the expansion scheme 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:

[0005] (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.

[0006] (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.

[0007] (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.

[0008] (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.

[0009] 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

[0010] 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 measures.

[0011] The technical solution adopted is:

[0012] A method for screening the maximum credible accident scenarios of a comprehensive energy supply station, comprising the following steps:

[0013] S1. Dividing the leakage unit: determining a comprehensive energy supply station, dividing the comprehensive energy supply station into at least two leakage units, each of which includes core process equipment and its connected piping, valves, and flanges;

[0014] S2. First screening: for each leakage unit, calculate the accident occurrence probability under different leakage diameters to determine the acceptable leakage probability, and perform the first round of screening based on a preset probability threshold; for the scenarios that pass the leakage probability screening, perform the second round of screening based on the maximum leakage principle to further determine the credible leakage scenarios of each leakage unit;

[0015] S3. Second screening: perform 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 physical effect influence range, 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;

[0016] For a single accident scenario, a model of a single accident scenario credibility factor C is established, and quantitative evaluation is performed through the following formula:

[0017] ;

[0018] ;

[0019] wherein, S is a physical effect influence range of the accident scenario, P is an accident probability corresponding to the accident scenario, is an asset density corresponding to the accident scenario, is a population density corresponding to the accident scenario; A is an asset impact index, B is a personnel impact index;

[0020] ;

[0021] wherein, k is a personnel risk weight coefficient;

[0022] The accident probability range is a value interval of the accident probability of each accident scenario in a predetermined evaluation period, and when evaluating different candidate sites, according to an accident occurrence probability calculation formula, the environmental factor joint frequency, the leakage direction frequency and the ignition probability corresponding to each candidate site are selected, and the parameters related to the site are substituted into the accident occurrence probability calculation formula, thereby obtaining the accident probability range corresponding to each candidate site.

[0023] The asset density is a ratio of the total asset value of buildings, structures and related equipment and infrastructure in a unit area range to the area, which is expressed in the form of monetary amount per square meter;

[0024] The population density is a ratio of the number of resident population and floating population in a specific period in a unit area range to the area, which is expressed in the form of number of people per square meter.

[0025] Preferably, the fuel involved in the comprehensive energy supply station at least includes two of hydrogen, compressed natural gas, methanol, gasoline and diesel.

[0026] Preferably, in the step S2, the calculation method of the accident occurrence probability is:

[0027] For an instant ignition accident, ;

[0028] For a delayed ignition accident, ;

[0029] wherein, is a leakage probability, is an environmental factor combined frequency, is a leakage direction frequency, is an immediate ignition probability, is a delayed ignition probability.

[0030] Preferably, the leakage probability is determined based on failure statistics of a target leakage unit and working condition; the environmental factor combined frequency is determined according to meteorological statistics of a region where the target site is located; and the immediate ignition probability and the delayed ignition probability are determined through ignition source event tree analysis.

[0031] As a further preference, the determination methods of the leakage probability, the environmental factor combined frequency, the leakage direction frequency, and the immediate ignition probability and the delayed ignition probability are as follows:

[0032] (1) Determination of the leakage probability:

[0033] For potential leakage positions of equipment, pipelines, valves and flanges in a leakage unit, for a failure rate expression mode of “counting by element”, let the failure rate of the i-th element category be , unit: times / (year·element), representing the expected number of leakages of a single i-th element in a year, the number of the i-th element category in the target leakage unit be , unit: pieces, then the total leakage frequency of the leakage unit is , representing the expected number of leakages of any aperture in a year, unit: times / year; expressed by a formula as:

[0034] ;

[0035] wherein, is the total number of element categories in the leakage unit;

[0036] For a failure rate expression mode of “counting by length”, let the failure rate of the i-th pipeline category be , unit: times / (year·m), representing the expected number of leakages of a single i-th pipeline in a year, the length of the i-th pipeline category in the target leakage unit be , unit: m, then the total leakage frequency is expressed by a formula as:

[0037] ;

[0038] After obtaining the total leakage frequency , the total leakage frequency is distributed according to different leakage aperture types, let the leakage aperture type be ​​​​(e.g. small, medium, large, etc.), the type of pore size under the condition of leakage The occurrence condition ratio is (dimensionless), satisfying , and The type of pore size Corresponding to the leakage frequency is:

[0039] ;

[0040] When the evaluation period is one year, the frequency can be further converted into the annual leakage probability, assuming that the evaluation period is , the unit is year, then the type of pore size The annual leakage probability of the pore size can be approximately expressed as a Poisson process:

[0041] ;

[0042] where, is an exponential function, when , the approximate relationship can be further used.

[0043] (2) Determination of the combined frequency of environmental factors:

[0044] 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;

[0045] Assuming that the wind direction is divided into the first wind direction interval (e.g. 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 occurs in the statistical period is , the unit is hour, and the total number of hours in the statistical period is , the unit is hour, then the combined occurrence frequency of the working condition unit , the probability of being in working condition at a random time is:

[0046] ;

[0047] The is taken as the combined frequency of environmental factors under the working condition .

[0048] (3) Determination of the leakage direction frequency:

[0049] Centering on the leak point, several typical leak directions are preset, and the leak directions are divided into several directions (such as "up", "down", "horizontal to a side", etc.), and a weight (dimensionless, reflecting the degree to which the leak jet is more inclined to the direction) is assigned to each direction.

[0050] By summing up the weights of the directions and normalizing, the leak direction frequency of each direction can be obtained.

[0051]

[0052] Wherein, n is the total number of preset leak directions, and when the weights of the directions are all taken as 1, the leak direction frequency of each direction is obtained as follows:

[0053] .

[0054] (4) Determination of ignition probability:

[0055] Taking "leakage event occurrence" as the top event, considering the combustible cloud formation condition, the type 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 recommended values in related safety specifications;

[0056] Let the probability of forming a combustible cloud after the leakage event occurs be (dimensionless, indicating the probability of forming a combustible cloud in a certain time and space range), the conditional probability of immediate ignition under the condition of forming a combustible cloud be (dimensionless, indicating 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 in a given time window under the condition of not immediate ignition but a combustible cloud has been formed be (dimensionless, indicating the probability of being ignited by a distant ignition source under the premise of "a combustible cloud exists and no immediate ignition"), then the immediate ignition probability (dimensionless, indicating the overall probability of the path from leakage to immediate ignition) and the delayed ignition probability (dimensionless, indicating the overall probability of the path from leakage to delayed ignition) are respectively represented as:

[0057] ;

[0058] ;

[0059] Wherein,​​​​​​​ , The sum of the joint probabilities of other paths in the event tree corresponds to the probability of "no ignition".

[0060] The conditional probabilities described above can be determined in combination with historical statistical data, similar device experience, or recommended values in relevant safety specifications.

[0061] Preferably, in step S2, the calculation formula of the maximum possible leakage amount is:

[0062] The maximum possible leakage amount = min (leakage rate x leakage time, unit capacity + replenishment amount).

[0063] 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, shutdown measures or the termination of material leakage in an uncontrolled state; the unit capacity is the mass of the leakable medium contained in the target leakage unit at the start of leakage; the replenishment amount is the mass of the medium 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;

[0064] For the same leakage unit, the scenario with the maximum leakage amount is selected as the credible leakage scenario of the unit.

[0065] Preferably, in 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 ;

[0066] The evaluation domain Ω is divided into several grid cells, and the area of the kth grid cell is Δ S k A representative point is selected as a calculation point within the kth grid cell; 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 The thermal radiation flux threshold value, the explosion peak overpressure threshold value, and the area S of the physical effect range are respectively I k ≥ Ith or P k ≥ P th area ； S is then obtained by statistical analysis using the following formula:

[0067] When operating under thermal radiation conditions ;

[0068] When in an explosive condition ;

[0069] Where K is the total number of grid cells, ranging from 100 to 1000; 1 (*) is an indicator function that takes the value 1 when the condition in parentheses is true, and 0 otherwise.

[0070] Based on this, the formula for calculating the damage radius R is: ;

[0071] Where R is the radius of the circular region centered on the accident source, which is equivalent to the range of influence of the physical effect under the thermal radiation flux threshold or the explosion peak overpressure threshold; S is the area of ​​the range of physical effect; and π is pi.

[0072] The I th 、P th The consequences impact thresholds are determined according to Appendix G1 and G2 of GB / T 37243-2019 "Risk Baseline for Production and Storage Facilities of Hazardous Chemicals", or can be determined according to the internationally recognized engineering guidelines (Methods for the Calculation of Physical Effects, also known as the Dutch TNO Purple Book).

[0073] Preferably, 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.

[0074] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0075] (1) Comprehensiveness and systematicness: The method of this invention covers the principle of dividing equipment and pipeline into integrated leakage units, and treats the core process equipment and its connected pipelines, valves and flanges as a whole analysis unit, which ensures the coverage of risk identification, eliminates the "blind spots" of risk analysis, and truly reflects the complex risk distribution of the integrated energy station.

[0076] (2) Objectivity and efficiency: The invention establishes a "two-stage quantitative screening" mechanism, which quickly eliminates scenarios with extremely low probability and no engineering significance through the first stage (probability screening), and selects the most representative scenario with the most serious consequences within the same unit based on the maximum leakage principle in the second stage (leakage screening). Two-stage screening greatly reduces subjective randomness and significantly improves analysis efficiency.

[0077] (3) Scientificity and accuracy: The invention innovatively proposes a "credible factor C" comprehensive evaluation model, which considers multiple sources of risk simultaneously. For the first time, population density and asset density are included as core variables in the screening model, making the screening results more accurately reflect the real impact of accidents on the specific surrounding environment. The fusion of personnel casualties and asset losses, two different dimensional indicators, into a unified and comparable comprehensive risk indicator (C value), makes the screening decision more scientific and accurate, breaking the limitations of traditional single dimension.

[0078] (4) Strong engineering practicability and guidance: The "maximum credible accident scenario" screened by the invention is no longer simply "maximum probability" or "most serious consequences", but a scenario with the highest risk value, i.e. the best balance point after weighting the environmental sensitivity of the occurrence probability and the severity of the consequences. The screening results can directly serve safety decisions, emergency plan preparation, and emergency resource allocation, etc.

[0079] (5) Universality and scalability: The invention provides a methodology framework, which can be seamlessly applied to comprehensive energy supply stations containing any two or more fuels such as hydrogen, compressed natural gas, methanol, gasoline, diesel, etc., with good promotion prospects and industry adaptability. BRIEF DESCRIPTION OF DRAWINGS

[0080] Figure 1 The overall flowchart of the method described in the invention.

[0081] Figure 2 The hydrogen leakage event tree analysis diagram in Example 1 of the invention. DETAILED DESCRIPTION

[0082] The accompanying drawings are for illustrative purposes only; 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, and can be obtained by the above-mentioned criteria or purple book.

[0083] Embodiment 1.

[0084] 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:

[0085] S1, leak unit division.

[0086] The process flow of its hydrogen energy supply station is divided into multiple leak units, including: unit 0101: pipeline system from hydrogen gas 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.

[0087] The division principle is to ensure that each unit is relatively independent in function and space, and contains equipment and its key connecting components.

[0088] S2, primary screening.

[0089] This step aims to screen out “credible leakage scenarios” with representative leakage quantities and non-extremely low occurrence probabilities from all possible leakage scenarios.

[0090] Probability screening. The leakage probability is determined based on the failure statistics of the target leakage unit and the working condition.

[0091] The calculation method of the accident occurrence probability is:

[0092] For immediate ignition accidents, ;

[0093] For delayed ignition accidents, ;

[0094] Wherein, is the leakage probability, is the environmental factor joint frequency, is the leakage direction frequency, For instantaneous ignition probability, This is the probability of delayed ignition.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] S3, Secondary screening.

[0099] This step aims to conduct a deeper evaluation of the initially selected credible leakage scenarios to determine the "maximum credible incident scenario".

[0100] 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 ;

[0101] The evaluation domain Ω is divided into several grid units, and the area of the kth grid unit is Δ S k A representative point is selected as a calculation point in the kth grid unit; 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 , and the physical effect intensity in the explosion working condition is denoted as P k , I th 、P th are the thermal radiation flux threshold value and the explosion peak overpressure threshold value respectively, 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: ；

[0102] When it is the thermal radiation working condition, ;

[0103] When it is the explosion working condition, ;

[0104] Wherein, K is the total number of grid units, and 1(*) is an indicator function, which takes 1 when the condition in the parentheses is true, and 0 otherwise.

[0105] On this basis, the calculation formula of the damage radius R is: ;

[0106] Wherein, R is the radius of a circular region with the accident source as the center and equivalent to the range of the physical effect 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.

[0107] 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).

[0108] ​The physical meaning of the statistics: The sum of the areas of all grid cells whose physical effect intensity reaches or exceeds the threshold is the area S of the physical effect range; this process is equivalent to obtaining the distribution of physical effect intensity and statistically analyzing the area of ​​the region that meets the threshold. The grid resolution can be set according to the evaluation accuracy requirements; the finer the grid division, the more accurate the area statistics result. I k or P k The results are calculated and output by accident consequence simulation software under corresponding scenarios and threshold conditions. HyRAM is preferred for hydrogen scenarios, while PHAST software is used for other fuels.

[0109] Comprehensive assessment of credibility factors: Population and asset distribution data are collected for each unit's surrounding area. The established credibility factor C model is applied to calculate the credibility factor C for each accident scenario. This model quantifies the comprehensive risk intensity of the accident on the surrounding environment by separately solving for the asset impact index A and the personnel impact index B, and uses a dimensional comparability coefficient k to ensure the dimensionless comparability of the assessment results.

[0110] Scenario determination: Compare the confidence factor C values ​​of all accident scenarios within the same leakage 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 confidence accident scenario" for that unit.

[0111] The method of this invention was applied to evaluate a comprehensive energy supply station, identifying all leaking units in the hybrid energy supply station. The results are shown using unit 0102 as an example:

[0112] First, based on the aforementioned accident scenario identification and screening method, credible accident scenarios for unit 0102 under different leakage orifice diameters (0.01%, 0.1%, 1%) and different accident types (jet fire, explosion) are determined, and the accident probability of each scenario is calculated using equipment failure data and operating conditions. Subsequently, according to the risk quantification formula proposed in this invention, the asset risk factor A and personnel risk factor B for each credible accident scenario are calculated. Specifically, the asset impact index of a single accident scenario... and personnel impact index Defined as:

[0113] ; ;

[0114] in, This refers to the range of physical effects affecting the accident scenario. For the probability of an accident, For asset density, Population density. By substituting the physical effect range and density parameters of each scenario in unit 0102 into the above formula, we can obtain asset risk factor A and personnel risk factor B.

[0115] Taking the 0.01% leakage and jet fire accident scenario in unit 0102 as an example, the accident probability in this scenario is P = 2.52 × 10⁻⁶. -4 Let the range of its physical effects be... Asset density is The asset risk factor is:

[0116] ;

[0117] After substituting the actual parameters, we can obtain

[0118] .

[0119] Similarly, let the population density be... The personnel risk factor is:

[0120] ;

[0121] The calculation yielded the following results:

[0122] .

[0123] 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:

[0124] ;

[0125] in, For personnel risk weighting coefficients, in this embodiment, we take... .

[0126] Taking the 0.01% leakage and jet fire scenario in unit 0102 as an example, substituting A and B above, we get:

[0127] ; ; ;

[0128] ;

[0129] Obtain the credibility factor corresponding to this scenario. .

[0130] 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:

[0131] ;

[0132] Personnel risk factor:

[0133] ;

[0134] Substitute the credible factor formula and take :

[0135] ; ; ;

[0136] ;

[0137] Get the credible factor of the explosion scene of 0102 unit 0.1 % leakage .

[0138] Using the same method, respectively get the value of 0102 unit 0.1 % leakage jet fire scene, wherein A=1.43×10 -5 , B=4.08×10 -7 , C=4.32×10 -5 , and 1 % leakage jet fire and explosion scene, A=8.38×10 -6 , B=2.39×10 -7 , C=2.54×10 -5 .

[0139] The screening results of 102 units are shown in Table 1.

[0140] Table 1 Screening results of 102 unit accident scene primary and secondary scenes

[0141]

[0142] When secondary screening, the data obtained by calculation are shown in Table 2.

[0143] Table 2 Calculation results of credible factors A, B, C of 102 unit accident scene

[0144]

[0145] Compare the results, and screen out the maximum credible accident scene, which is shown in Table 3. The results show that in the jet fire accident type, the credible factor of 0102 unit 0.01 % leakage scene is the largest; in the explosion accident type, the credible factor of 0102 unit 0.1 % leakage scene is the largest. Therefore, the pipeline system from valve A to valve B, including the compressor equipment, is the largest credible accident scene of the mixed comprehensive energy supply station.

[0146] Table 3 Maximum credible accident scenario screening results

[0147]

[0148] Further, the credible factors C of each unit, each accident type and each leakage aperture scenario of the whole station are compared and sorted to obtain the maximum credible accident scenario of the comprehensive energy supply station.

[0149] Of course, the above description is not a limitation on the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the spirit and scope of the present application should also be within the protection scope of the present application.

Claims

1. A method for screening maximum credible accident scenarios for an integrated energy supply station, characterized in that, The method comprises 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, and each leakage unit comprising core process equipment and pipelines, valves and flanges connected thereto; S2. First screening: for each leakage unit, calculating the accident occurrence probability under different leakage aperture diameters to determine the acceptable leakage probability, and performing the first round of screening based on a preset probability threshold; for the scenarios passing the leakage probability screening, performing the second round of screening based on the maximum leakage amount 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 physical effect influence range, accident probability, population density and asset density within a preset range, calculating the credible factor C of each accident scenario; by comparing the values of the credible factor C, determining the maximum credible accident scenario corresponding to each leakage unit; For a single accident scenario, a model of the single accident scenario credible factor C is established, and quantitative evaluation is performed through the following formula: ； ； wherein, S is a physical effect impact range of the accident scenario, P is an accident probability corresponding to the accident scenario, is an asset density corresponding to the accident scenario, is a population density corresponding to the accident scenario; A is an asset impact index, B is a personnel impact index; ； wherein, k is a personnel risk weight coefficient; The accident probability range is the value interval of the accident occurrence probability of each accident scenario within a predetermined evaluation period, and when evaluating different candidate sites, the environmental factor joint frequency, the leakage direction frequency and the ignition probability related to the site are selected according to the accident occurrence probability calculation formula, and the parameters of the environmental factor joint frequency, the leakage direction frequency and the ignition probability related to the site are substituted into the accident occurrence 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 and infrastructure within a unit area 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 to the area, which is expressed in the form of the number of people per square meter.

2. The method of claim 1, wherein, The fuel involved in the comprehensive energy supply station includes two of hydrogen, compressed natural gas, methanol, gasoline and diesel.

3. The method of claim 2, wherein, In step S2, the calculation method of the accident occurrence probability is as follows: For immediate ignition accidents, ; For delayed ignition accidents, ; wherein, is the leak probability, is the environmental factor joint frequency, is the leak direction frequency, is the immediate ignition probability, is the delayed ignition probability.

4. The method of claim 3, wherein, The leakage probability is determined based on the failure statistical data and working condition of the target leakage unit; the environmental factor joint frequency is determined according to the meteorological statistical data of the region where the target site is located; the instant ignition probability and the delayed ignition probability are determined through ignition source event tree analysis.

5. The method of claim 4, wherein, The determination methods of the leakage probability, the environmental factor joint frequency, the leakage direction frequency, the instant ignition probability and the delayed ignition probability are as follows: (1) Determination of leakage probability: For the potential leakage points of the equipment, pipelines, valves and flanges in the leakage unit, for the failure rate expression mode of "counting by element", set the failure rate of the first class element as , unit: times / (year·element), 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: ； wherein, N is the total number of element classes within the leak unit; For the failure rate expressed in "count per length", let the failure rate of the i-th pipe be , unit: times / (year·m), which represents the expected number of leaks per year of the i-th pipe with a length of , unit: m, in the target leak unit, then the total leak frequency is , unit: times / year. The formula is: ； The total leakage frequency ƒ leak,total is then distributed among the different leakage aperture types, assuming that there are N types of leakage apertures, and that the i-th type of aperture has a probability of occurrence of h , and that the i-th type of aperture has a probability of occurrence of h , and that the i-th type of aperture has a probability of occurrence of , and that the i-th type of aperture has a probability of occurrence of , and that the i-th type of aperture has a probability of occurrence of , and that the i-th type of aperture has a probability of occurrence of h , and that the i-th type of aperture has a probability of occurrence of , and that the i-th type of aperture has a probability of occurrence of ； When the evaluation period is one year, the frequency is converted to the annual leakage probability, and the evaluation period is set to , in years, then the annual leakage probability of the aperture type is approximated by a Poisson process as ； where exp is the exponential function, and when the approximation is used. (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; Let the wind direction be divided into the first wind direction intervals, the wind speed be divided into the first wind speed intervals, and the atmospheric stability level be the first level, then the number of hours in which 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 is , and the probability of being in the working condition at a random moment is: ； The i.e. as a joint frequency of the environmental factors under the working conditions . (3) Determination of leakage direction frequency: Centering on the leakage point, a plurality of typical leakage directions are preset, the leakage directions are divided into a plurality of directions, and each direction is assigned a weight. ;​​ By summing up the weights of each direction and normalizing, the leakage direction frequency of each direction is obtained That is: ； wherein, is a preset total number of leakage directions, and when each direction weight is uniformly taken as 1, thus obtaining: ； (4) Determination of ignition probability: With "leakage event occurrence" as the top event, the event tree of leakage-diffusion-ignition is constructed by comprehensively considering the formation condition of flammable cloud, the type and spatial distribution of ignition source in the leakage area, and the frequency of personnel activities, and the conditional probability of each branch of the event tree is given based on historical statistical data or recommended values in relevant safety standards; Let P (cloud) be the probability that a flammable cloud forms after a leak event Let P (flash) be the conditional probability that an immediate ignition occurs given that a flammable cloud has formed Let P (delay) be the conditional probability that a delayed ignition occurs within a given time window given that a flammable cloud has formed but no immediate ignition has occurred Then the immediate ignition probability P (flash | cloud) is given by And the delayed ignition probability P (delay | cloud) is given by P (flash | cloud) = P (flash) P (cloud) / P (cloud | flash) ； ； wherein , correspond to the joint probabilities of the "immediate ignition path" and "delayed ignition path" in the event tree, respectively, and the sum of the joint probabilities of the other paths in the event tree is the probability of "no ignition".

6. The method of claim 5, wherein, In the step S2, the calculation formula of the maximum possible leakage amount is: The maximum possible leakage amount = min (leakage rate × 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 isolation, cutting-off measures or the termination of material leakage in the out-of-control state; the unit capacity is the amount of leachable medium contained in the target leakage unit at the start of leakage; the replenishment amount is the amount of medium replenished from the upstream equipment or pipeline to the target leakage unit and possibly further leaked within the leakage time, which is 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.

7. The method of claim 5, wherein, The intensity of the physical effect when considering thermal radiation is the thermal radiation flux I The intensity of the physical effect when considering an explosion is the peak overpressure of the explosion P ; The evaluation domain Ω is divided into several grid units, and the area of the kth grid unit is △ S k A representative point is selected as a calculation point in the kth grid unit; 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 The thermal radiation flux threshold and the explosion peak overpressure threshold are respectively denoted as and the area S of the physical effect range satisfies I k ≥ I th or P k ≥ P th The area of the region ； is obtained according to the following formula: When for the heat radiation working condition, ​ When for explosion working condition, ; Wherein, K is the total number of grid units, 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 circular area radius with the accident source as the center, which is equivalent to the physical effect influence range under the threshold of heat radiation flux or the threshold of explosion peak overpressure, S is the area of the physical effect influence range, and π is the circular constant; The I th 、P th Determined according to the consequence impact thresholds of Appendix G1 and G2 of GB / T 37243-2019 "Risk Criteria for Hazardous Chemicals Production Devices and Storage Facilities".

8. The method of claim 2, wherein, The preset probability threshold is 1x10 -6 ; The preset probability threshold is determined based on the safety level of the comprehensive energy supply station, industry standards and risk acceptance criteria.

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