Method for assessing long heat supply pipeline failure consequences and risk acceptability

Abstract

A method for assessing the consequences and risk acceptability of failures in long-distance heating pipelines, belonging to the field of heating pipeline safety management technology, addresses the problems of insufficient quantification of consequences, poor adaptability of physical effect models, and static acceptability assessment methods in traditional long-distance heating pipeline failure risk assessments. The method includes the following steps: S1, identifying and analyzing accident types; S2, performing hydraulic calculations; S3, establishing physical effect models for different types of pipelines; S4, quantifying personnel casualties, environmental losses, and economic losses through multiple factors; S5, determining the acceptability of risks in terms of personnel, environment, and economy based on the ALARP criterion, dividing risk areas, and then classifying risk levels according to the risk areas. This invention improves the accuracy of methods for quantifying the consequences and risk acceptability of failures in long-distance heating pipelines, contributing to the safety of long-distance heating pipeline operation.

Description

Technical Field

[0001] This invention belongs to the field of heating pipeline safety management technology, specifically relating to a method for assessing the acceptability of the consequences and risks of failure in long-distance heating pipelines. Background Technology

[0002] Long-distance heating pipelines are the core infrastructure of centralized heating systems, undertaking the task of transporting heat across cities or regions. Their operational safety directly affects the stable supply of heat to residents in the region. Compared to urban municipal heating pipelines, long-distance heating pipelines have the following characteristics:

[0003] 1. Special operating parameters of the medium: It often uses hot water or steam at temperatures above 100℃ as the transport medium, and the operating pressure is usually 1.6~2.5MPa. Moreover, flash evaporation is likely to occur after the medium leaks, and the diffusion law is complex.

[0004] 2. Diverse laying methods: When directly buried, the pipeline is greatly affected by soil constraints and geological conditions, while when laid overhead, the pipeline is directly exposed to the atmospheric environment, and the diffusion range of the medium after leakage is significantly affected by environmental factors such as wind speed.

[0005] 3. The service environment is complex, the pipeline spans a large area, and passes through different regions such as urban areas, suburbs, and farmland, with significant differences in population density, soil type, and ecological environment;

[0006] 4. The consequences of failure are highly correlated. The losses from failure accidents are not caused by a single factor, but are caused by the coupling of factors such as casualties, environmental damage, and economic losses. They are also very likely to trigger secondary social impacts such as heating outages and traffic disruptions.

[0007] Currently, there are existing standards and specifications for oil and gas pipelines and failure consequence assessment. However, due to the different applicable objects, their evaluation methods cannot be directly applied to the quantitative assessment of failure consequences of long-distance heating pipelines. Therefore, the standard system for long-distance heating pipelines still lacks a complete risk assessment system and failure consequence quantification method applicable to long-distance heating pipelines.

[0008] As the arteries for transporting heat energy in cities or regions, the consequences of failures in long-distance heating pipelines are far more severe than those in urban heating networks. These consequences are mainly reflected in the following three aspects:

[0009] 1. Personnel: At the moment of failure, the high-temperature steam or hot water in the pipeline will violently erupt under high pressure, which will not only cause deep burns and shock to the surrounding personnel, but also the shock wave or fragments generated by the pipeline rupture can easily cause secondary injuries such as impact injuries and puncture injuries.

[0010] 2. Environmental aspects: The continuous leakage of high-temperature steam or hot water will cause complex and long-term damage to the soil, surface water, vegetation and other environmental factors along the route.

[0011] 3. Economic aspects: These include both direct and indirect losses. Direct losses include repairs to the pipeline itself, loss of the leaked medium, and emergency response costs. Indirect losses are multifaceted: heating outages lead to industrial shutdowns and declining commercial revenue; traffic congestion and logistics delays; and pollution from the leaked medium results in unsold and reduced crop yields.

[0012] Therefore, it is urgent to construct a reasonable method for quantifying failure consequences and a risk acceptability assessment system, which is a core requirement for the safe operation and maintenance of long-distance heating pipelines.

[0013] For example, the "GB 32167-2015 Oil and Gas Transmission Pipeline Integrity Management Standard" applies to the integrity management of long-distance onshore oil and gas pipelines, focusing on the structural integrity of the pipeline and establishing detailed evaluation procedures and testing technical requirements. Furthermore, it emphasizes assessing the risk characteristics of oil and gas media. The "GB 46767-2025 Identification and Management of High-Consequence Areas with Dense Population in Long-Distance Onshore Oil and Gas Pipelines" focuses on the identification, assessment, and control of high-consequence areas with dense populations, aiming to reduce the risk of mass casualties. The identification of high-consequence areas is based on the risk of explosion and poisoning after oil and gas leaks. The "CJJ / T 302-2023 Urban Gas Transmission and Distribution Pipeline Integrity Management Standard" emphasizes gas pipeline leak detection and high-consequence area control because the natural gas it transports is flammable and explosive; even a small leak can form an explosive mixture. The "GB / T The "Method for Safety Risk Assessment of Urban Heating Pipelines" (44548-2024) is only applicable to heating pipe networks within urban areas and does not cover major risk assessment scenarios faced by long-distance heating pipelines during cross-regional and long-distance transmission.

[0014] In summary, existing research on the failure consequences and risk acceptability of long-distance heating pipelines still has the following shortcomings:

[0015] 1. Insufficient quantification of consequences. Common methods for urban heating pipelines typically only make rough estimates of personnel, environmental, and economic losses, without conducting refined and parameterized breakdown calculations, making it difficult to carry out accurate risk prevention and control;

[0016] 2. Poor adaptability of physical effect models. For vapor diffusion after leakage, the traditional Gaussian diffusion model is only applicable to continuous, steady-state ground source release. However, for buried pipelines, the Gaussian model cannot describe the physical phenomenon of vapor accumulating in the soil and then bursting, which leads to the inability to accurately assess the risk of vapor diffusion.

[0017] 3. Staticization of acceptability assessment methods. For risk curves commonly used in risk acceptability assessment, the PI curve only reflects the instantaneous impact of an accident in evaluating environmental acceptability, ignoring the dynamic recovery process of the ecosystem; at the same time, in evaluating economic acceptability, the PL curve only assesses the static losses suffered by the system, without considering the system's resilience.

[0018] Therefore, there is an urgent need in this field to propose a failure consequence analysis method that has strong adaptability to physical effect models, can quantify failure consequences from multiple factors, and has dynamic acceptability assessment capabilities, so as to improve the accuracy of failure consequence quantification for long-distance heating pipelines. Summary of the Invention

[0019] Traditional failure risk assessments for long-distance heating pipelines suffer from problems such as insufficient quantification of consequences, poor adaptability of physical effect models, and static acceptability assessment methods. To overcome these shortcomings, this invention aims to propose a failure consequence quantification and risk acceptability assessment method that can quantify accident consequences and physical effect models for both overhead and buried pipelines, and possesses dynamic acceptability assessment capabilities.

[0020] This invention is achieved through the following technical solution: a method for assessing the acceptability of failure consequences and risks of long-distance heating pipelines, comprising the following steps:

[0021] S1. Identify the accident type and analyze and statistically analyze the scope and consequences of the accident.

[0022] S2. Determine the rupture size, perform hydraulic calculations, and determine the leakage rate, system downtime, and total leakage for different types of pipes;

[0023] S3. Based on the type of long-distance heating pipeline, physical effect modeling is performed. The types of long-distance heating pipeline include overhead long-distance heating pipeline and direct-buried long-distance heating pipeline. The flash steam diffusion model of overhead long-distance heating pipeline and the three-stage model of pore accumulation-pressure breakthrough-ground diffusion of direct-buried pipeline are determined respectively to solve the delayed steam explosion risk that cannot be explained by the traditional Gaussian model.

[0024] S4. Quantification of failure consequences and losses: Based on multiple factors, the losses of personnel casualties, environmental losses, and economic losses are quantified respectively; the losses of personnel casualties include economic compensation for death, serious injury, and minor injury; the environmental losses include the restoration costs of soil pollution, water pollution, and vegetation damage; and the economic losses include direct losses and indirect losses.

[0025] S5. The risk acceptability analysis of personnel casualties is determined based on the FN curve, and the risk acceptability analysis of environmental losses is determined based on the TI curve. The TI curve is introduced into the environmental loss acceptability analysis. While the PI curve is often used to assess environmental loss risk, it fails to reflect the dynamic recovery process of the ecosystem. The TI curve, with the ecological recovery period T on the horizontal axis and the environmental impact index I on the vertical axis, can intuitively reflect the duration and severity of environmental impact under different accident scenarios. The risk acceptability analysis of economic losses is determined based on the PLR ​​curve. Traditional economic loss assessment uses the PL curve, but it does not consider system recovery capacity and fails to reflect the dynamic process in actual emergency management. Therefore, the resilience index R is introduced to construct the PLR ​​curve, providing a more comprehensive assessment of the acceptability of economic losses. The risk areas are divided into three categories: "unacceptable," "ALARP," and "widely acceptable," and then three risk levels are determined based on these risk areas to complete the quantitative assessment of the consequences and risk acceptability of long-distance heating pipeline failure.

[0026] Furthermore, in step S2, the type of pipeline is a direct-buried long-distance heating pipeline. When calculating the leakage rate of the direct-buried long-distance heating pipeline, since the leakage is blocked by the soil medium, a soil constraint coefficient K is introduced. s Quantifying the compressive effect of the soil on the leakage pore, i.e., the leakage rate of directly buried long-distance heating pipelines:

[0027] ; (1)

[0028] In equation (1), K s K is the soil constraint coefficient. s The value of K ranges from 0.4 to 0.7. s The value of C depends on soil compaction, burial depth, and backfill material; d ρ is the flow coefficient; A is the rupture area; ρ is the hot water density; P1 is the pressure inside the pipe; P2 is the ambient pressure.

[0029] System downtime and total leakage:

[0030] ; (2)

[0031] In the formula, t s This refers to the system downtime. This represents the leakage rate per unit time.

[0032] Furthermore, in step S3, constructing the three-stage model of pore accumulation-pressure breakthrough-surface diffusion of the directly buried pipeline includes the following steps:

[0033] S3-1, Pore accumulation stage;

[0034] Leakage affects volume Vinfluence for:

[0035] ; (3)

[0036] In equation (3), R influence The radius of the leakage impact is h; the burial depth is h.

[0037] Pore ​​volume V pore for:

[0038] ; (4)

[0039] In equation (4), ϕ is the soil porosity;

[0040] Critical breakthrough pressure P critical for:

[0041] ; (5)

[0042] In equation (5), P0 is the environmental pressure;

[0043] The pore vapor mass m0 under ambient pressure is:

[0044] ; (6)

[0045] In equation (6), M is the molar mass of water, R is the universal gas constant, and T is the steam temperature;

[0046] Required steam mass m at critical pressure critical for:

[0047] ; (7)

[0048] The additional steam mass Δm that needs to be accumulated is:

[0049] ; (8)

[0050] Steam generation rate steam for:

[0051] ; (9)

[0052] In equation (9), f is the flash evaporation ratio. leak,buried This refers to the leakage rate of a directly buried pipeline.

[0053] Accumulation time t accumulation for:

[0054] ; (10)

[0055] Actual pore pressure P pore for:

[0056] ; (11)

[0057] S3-2, Pressure Breakout Phase: Determine if a breakout has occurred. The conditions for determining if a breakout has occurred are: ;

[0058] I. If a breakthrough occurs;

[0059] Nozzle area A vent for:

[0060] ;(12)

[0061] In equation (12), f crack is the crack opening ratio, representing the ratio of the actual crack opening area to the equivalent circular area; h is the equivalent circular nozzle diameter.

[0062] Jet mass flow rate burst for: (13)

[0064] In equation (13), ρ v The density of the vapor;

[0065] Spray duration t burst for:

[0066] ;(14)

[0067] Effective source high v jet for: (15)

[0069] ; (16)

[0070] In equation (16), g is the acceleration due to gravity, g = 9.81 m / s²;

[0071] S3-3, Ground diffusion stage;

[0072] The ground point source concentration is: (17)

[0074] In equation (17), u is the wind speed, and σ is the wind speed. y σ is the lateral diffusion parameter. z For vertical diffusion parameters;

[0075] Let the damage threshold concentration C be... threshold Assuming it's a constant, the radius of influence R is obtained by iteratively solving the following equation:

[0076] ; (18)

[0077] The diffusion duration t for the concentration to drop to the safe threshold was calculated based on the Gaussian model. diffusion for: (19)

[0079] In equation (19), x max η is the distance at which the concentration drops to the safe threshold. diffusion The diffusion efficiency coefficient;

[0080] II. If no breakthrough occurs, the vapor diffuses slowly through the soil pores: (20)

[0082] The radius of influence R is as follows, assuming no breakthrough occurs:

[0083] ; (twenty one)

[0084] The area affected is:

[0085] ; (twenty two)

[0086] In equation (22), A fatal R represents the area of ​​the lethal influence zone. fatal Radius of lethal effect;

[0087] ; (twenty three)

[0088] In equation (23), A serious For the area of ​​the severely affected zone, R serious This significantly affects the radius;

[0089] ; (twenty four)

[0090] In equation (24), A minor R represents the area of ​​the area with slight impact. minor It has a slight impact on the radius.

[0091] Furthermore, in step S4, personal injury losses are quantified by combining statutory compensation, funeral expenses, or lost wages; the direct losses include repair, media, and emergency losses, while the indirect losses include heating outages, transportation, and agricultural losses.

[0092] This invention closely reflects the actual loss composition of heating pipeline accidents, and provides a more comprehensive quantification of loss factors compared to traditional models.

[0093] Furthermore, in step S5, in the TI curve, "T" represents the ecological restoration period, and "I" represents the environmental impact index, where:

[0094] Environmental Impact Index I (dimensionless) is:

[0095] ; (25)

[0096] In equation (25), w i Let be the weight of the i-th type of environmental element, and ;I i The impact index of the i-th type of environmental element is determined based on pollution concentration and ecological sensitivity.

[0097] The ecological restoration period T is:

[0098] ; (26)

[0099] In equation (26), T soil For soil restoration years, T water For the water body recovery period, T veg The number of years required for vegetation to recover.

[0100] Furthermore, in step S5, the expression for the PLR ​​curve is: (27)

[0102] In equation (27), L(t) represents the cumulative economic loss at time t, L0 represents the initial economic loss of the accident; R is the resilience index, which represents the recovery capacity of the economic system per unit time; t is time.

[0103] The toughness index R is: (28)

[0105] In equation (28), T r Indicates the time required for the system to recover to an acceptable level; L c This indicates the acceptable threshold for economic loss.

[0106] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows: by constructing models of physical effects of different types of pipelines, quantifying accident consequences through multiple factors, and constructing a dynamic risk acceptability assessment method, the problems of insufficient consequence quantification factors, poor adaptability of physical effect models, and static acceptability assessment methods in the traditional risk assessment of failure consequences of long-distance heating pipelines are solved, thereby improving the accuracy of consequence quantification and contributing to the safe operation and maintenance of long-distance heating pipelines. Attached Figure Description

[0107] Figure 1 This is a schematic diagram of the process of the present invention;

[0108] Figure 2 Diagram showing the composition of losses from accidents involving long-distance heating pipelines;

[0109] Figure 3A bar chart detailing economic losses;

[0110] Figure 4 This is a plot of the acceptability of economic loss risk (PLR curve). Detailed Implementation

[0111] To better understand the above-described objects, features, and advantages of the present invention, embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0112] like Figures 1 to 4 The method shown for assessing the acceptability of the consequences and risks of failure in long-distance heating pipelines includes the following steps.

[0113] S1. Identify the accident type and analyze and statistically analyze the scope and consequences of the accident.

[0114] As an infrastructure responsible for the cross-regional, large-capacity transmission of heat energy, long-distance heating pipelines operate in complex environments and are subjected to high-temperature and high-pressure conditions for extended periods. Their accident types are primarily media leakage failures. Based on the pipeline structure and actual engineering failure cases, they can be mainly classified into the following four categories:

[0115] Small hole leakage: refers to tiny leaks with a diameter of less than 10mm appearing in the pipe wall. These leaks are often caused by localized corrosion, minor defects in weld joints, long-term erosion by the medium, or the propagation of micro-cracks in the material.

[0116] Medium-sized hole leakage: The leakage hole diameter is between 10 and 50 mm. It belongs to the progressive failure. The main causes include corrosion pits exceeding the critical thickness of the pipe wall, minor impact from a third party, and crack propagation caused by stress concentration in the pipeline.

[0117] Large hole leakage / fracture: Leakage hole diameter > 50mm or the entire pipe is fractured. This is a sudden and serious failure, which is often caused by geological disasters, impact from heavy machinery from third parties, material fatigue failure, or overpressure operation.

[0118] Flange, valve or connector failure: The failure of the seal or the structural damage of the pipeline connection due to aging of the seal, installation deviation, loosening due to temperature stress or long-term lack of maintenance.

[0119] S2. Determine the rupture size, perform hydraulic calculations, and determine the leakage rate, system downtime, and total leakage for different types of pipes;

[0120] S2-1, Overhead Pipeline Leakage Model:

[0121] ;

[0122] In the formula, C dρ is the flow coefficient; A is the rupture area; ρ is the hot water density; P1 is the pressure inside the pipe; P2 is the ambient pressure.

[0123] S2-2, Leakage Model of Direct-Buried Pipelines:

[0124] When calculating the leakage rate of buried long-distance heating pipelines, a soil constraint coefficient K is introduced because the leakage is hindered by the soil medium. s Quantifying the compressive effect of the soil on the leakage pore, i.e., the leakage rate of directly buried long-distance heating pipelines:

[0125] ; (1)

[0126] In equation (1), K s K is the soil constraint coefficient. s The value of C ranges from 0.4 to 0.7. d ρ is the flow coefficient; A is the rupture area; ρ is the hot water density; P1 is the pressure inside the pipe; P2 is the ambient pressure.

[0127] S2-3, System downtime and total leakage:

[0128] ; (2)

[0129] In equation (2), t s This refers to the system downtime. This represents the leakage rate per unit time.

[0130] S3. Perform physical effect modeling based on the type of long-distance heating pipeline, which includes overhead long-distance heating pipeline and direct-buried long-distance heating pipeline. Determine the flash steam diffusion model for overhead long-distance heating pipeline and the three-stage model of pore accumulation-pressure breakthrough-ground diffusion for direct-buried pipeline.

[0131] S3-1, Flash steam diffusion model for overhead long-distance heating pipelines;

[0132] S3-1-1, the flash evaporation ratio f is:

[0133] ;

[0134] In the formula, h1 is the enthalpy of hot water under pipe pressure, h2 is the enthalpy of saturated water under ambient pressure, and h fg The latent heat of vaporization under environmental pressure;

[0135] S3-1-2, Steam Cloud Diffusion Model:

[0136] ;

[0137] In the formula, Q is the source strength of the pollutant; u is the average ambient wind speed; σ y σ is the crosswind diffusion coefficient; z y is the vertical diffusion coefficient; x is the downwind distance; y is the crosswind distance; z is the prediction point height; H e For effective source high.

[0138] S3-2. Constructing the three-stage model of pore accumulation-pressure breakthrough-ground diffusion for the directly buried pipeline includes the following steps:

[0139] S3-2-1, Pore Accumulation Stage;

[0140] ① Leakage affects volume V influence for:

[0141] ; (3)

[0142] In equation (3), R influence The radius of the leakage impact is h; the burial depth is h.

[0143] ② Pore volume V pore for:

[0144] ; (4)

[0145] In equation (4), ϕ is the soil porosity;

[0146] ③ Critical breakthrough pressure P critical for:

[0147] ; (5)

[0148] In equation (5), P0 is the environmental pressure;

[0149] ④ The pore vapor mass m0 under ambient pressure is:

[0150] ; (6)

[0151] In equation (6), M is the molar mass of water, R is the universal gas constant, and T is the steam temperature;

[0152] ⑤ Required steam mass m at critical pressure critical for:

[0153] ; (7)

[0154] ⑥ The additional steam mass Δm that needs to be accumulated is:

[0155] ; (8)

[0156] ⑦ Steam generation rate steam for:

[0157] ; (9)

[0158] In equation (9), f is the flash evaporation ratio. leak,buried This refers to the leakage rate of a directly buried pipeline.

[0159] ⑧ Accumulation time t accumulation for:

[0160] ; (10)

[0161] ⑨ Actual pore pressure P pore for:

[0162] ; (11)

[0163] S3-2-2, Pressure Breakout Phase: Determine if a breakout has occurred. The conditions for determining if a breakout has occurred are: ;

[0164] I. If a breakthrough occurs:

[0165] ① Nozzle area A vent for:

[0166] ;(12)

[0167] In equation (12), f crack is the crack opening ratio, representing the ratio of the actual crack opening area to the equivalent circular area; h is the equivalent circular nozzle diameter.

[0168] ② Jet mass flow rate burst for:

[0169] ; (13)

[0170] In equation (13), ρ v The density of the vapor;

[0171] ③ Spray duration t burst for: (14)

[0173]

[0174] ⑤ Effective source high v jet for:

[0175] ; (15)

[0176] ; (16)

[0177] In equation (16), g is the acceleration due to gravity, g = 9.81 m / s²;

[0178] S3-2-3, Ground diffusion stage;

[0179] ① The ground point source concentration is: (17)

[0181] In equation (17), u is the wind speed, and σ is the wind speed. y σ is the lateral diffusion parameter. z For vertical diffusion parameters;

[0182] ② Let the damage threshold concentration C be... threshold Assuming it's a constant, the radius of influence R is obtained by iteratively solving the following equation:

[0183] ; (18)

[0184] ④ Calculate the diffusion duration t for the concentration to drop to the safe threshold based on the Gaussian model. diffusion for: (19)

[0186] In equation (19), x max η is the distance at which the concentration drops to the safe threshold. diffusion The diffusion efficiency coefficient;

[0187] II. If no breakthrough occurs, the vapor diffuses slowly through the soil pores: (20)

[0189] ① The radius of influence R under the condition that no breakthrough occurs is:

[0190] ; (twenty one)

[0191] ② The area affected is:

[0192] ; (twenty two)

[0193] In equation (22), A fatal R represents the area of ​​the lethal influence zone. fatal Radius of lethal effect; (twenty three)

[0195] In equation (23), A serious For the area of ​​the severely affected zone, R serious This significantly affects the radius; (twenty four)

[0197] In equation (24), Aminor R represents the area of ​​the area with slight impact. minor It has a slight impact on the radius.

[0198] S4. Quantification of Failure Consequences and Losses: Based on multiple factors, personnel casualty losses, environmental losses, and economic losses are quantified separately. Personnel casualty losses include economic compensation for death, serious injury, and minor injury, combined with statutory compensation, funeral expenses, or lost wages. Environmental losses include the cost of remediation for soil pollution, water pollution, and vegetation damage. Economic losses include direct and indirect losses. Direct losses include remediation, media, and emergency losses, while indirect losses include heating outages, transportation, and agricultural losses.

[0199] S5. Based on the FN curve, determine the risk acceptability analysis of personnel casualties and losses; based on the TI curve, determine the risk acceptability analysis of environmental losses; based on the PLR ​​curve, determine the risk acceptability analysis of economic losses. Divide the risk areas into three categories: "unacceptable," "ALARP," and "widely acceptable." Then, based on the risk areas, define three levels of risk to complete the quantitative assessment of the consequences and risk acceptability of long-distance heating pipeline failure.

[0200] FN curve: It quantifies casualties of different severity into equivalent deaths, making the FN curve adaptable to risk assessment of multiple types of casualties.

[0201]

[0202] In the formula, N fatal N represents the actual number of deaths. serious For the number of seriously injured, N minor The number of people with minor injuries.

[0203] Where: N: equivalent number of deaths; k: social risk baseline parameter; β: social sensitivity parameter to the accident.

[0204] Furthermore, in the TI curve, "T" represents the ecological restoration period, and "I" represents the environmental impact index, where:

[0205] The environmental impact index I is:

[0206] ; (25)

[0207] In equation (25), w i Let be the weight of the i-th type of environmental element, and ;I i The impact index of the i-th type of environmental element is determined based on pollution concentration and ecological sensitivity.

[0208] The ecological restoration period T is: (26)

[0210] In equation (26), T soil For soil restoration years, T water For the water body recovery period, T veg The number of years required for vegetation to recover.

[0211] Furthermore, the expression for the PLR ​​curve is:

[0212] ;(27)

[0213] In equation (27), L(t) represents the cumulative economic loss at time t, L0 represents the initial economic loss of the accident; R is the resilience index, which represents the recovery capacity of the economic system per unit time; t is time.

[0214] The toughness index R is:

[0215] ; (28)

[0216] In equation (28), T r Indicates the time required for the system to recover to an acceptable level; L c This indicates the acceptable threshold for economic loss.

[0217] The following example of an accident in a certain enterprise's long-distance heating pipeline will be used to further illustrate the present invention. The main body data of the pipeline is shown in Table 1.

[0218] Table 1. Pipeline Body Data

[0219]

[0220] This paper takes overhead pipeline A and buried pipeline B as examples. The overhead pipeline A experiences leakage through its large bore due to third-party damage, while the buried pipeline B experiences leakage through its central bore due to corrosion. Hydraulic calculations were performed on both the overhead pipeline A and the buried pipeline B to obtain the leakage rate, system downtime, and total leakage, as shown in Table 2 below.

[0221] Table 2. Hydraulic Calculation Results

[0222]

[0223] Next, a flash steam diffusion model for overhead pipeline A and a three-stage model for pore accumulation-pressure breakthrough-ground diffusion for buried pipeline B were established.

[0224] Next, the consequences and losses are quantified, including multi-factor quantification of personal injury losses (including economic compensation for death, serious injury, and minor injury), environmental losses (soil pollution, water pollution, and vegetation damage restoration costs), and economic losses (direct restoration costs and indirect losses). A diagram illustrating the loss composition of a long-distance heating pipeline accident is shown below. Figure 2 The results of the calculation of economic casualties are shown in Table 3, and the detailed bar chart of economic losses is shown in the figure below. Figure 3 .

[0225] Table 3. Calculation Results of Economic Casualty Losses

[0226]

[0227] The FN curve, TI curve, and PLR curve were used to conduct risk acceptability analysis for personnel, environment, and economy, respectively. Three risk zones were identified: unacceptable, ALARP, and broadly acceptable. Based on these risk zones, three risk levels were then assigned. The acceptability and risk levels of personnel, environmental, and economic losses are shown in Table 4, and the PLR ​​curve is shown in the figure below. Figure 4 .

[0228] Table 4. Risk Zones for Personnel, Environmental, and Economic Losses

[0229]

[0230] Calculations show that the overall risk of this incident is in the ALARP zone (medium risk), and measures need to be developed and improved to ensure that the risk is always kept at the lowest reasonable and feasible level.

[0231] As can be seen from this embodiment, this invention addresses the problems of insufficient quantification factors, poor adaptability of physical effect models, and static acceptability assessment methods in traditional methods for quantifying failure consequences and assessing the acceptability of long-distance heating pipelines. It proposes a failure consequence analysis method with strong adaptability of physical effect models, capable of quantifying failure consequences from multiple factors, and possessing dynamic acceptability assessment capabilities. The core of this method lies in constructing a closed-loop assessment method encompassing physical effect modeling, multi-factor loss quantification, risk acceptability analysis, and risk level determination. A soil constraint coefficient K is introduced when calculating the leakage rate of directly buried long-distance heating pipelines. s This method quantifies the compressive effect of soil on leaking pores; considering the characteristics of leaked vapor accumulation in soil pores and subsequent diffusion through soil penetration, a three-stage model of "pore accumulation - pressure breakthrough - ground diffusion" is established; FN curves, TI curves, and PLR curves are introduced to determine the acceptability of risks in terms of personnel, environment, and economy, respectively. This method can accurately quantify the losses of failure accidents and define the risk level and acceptability boundary, improving the accuracy of quantifying the consequences of failures and assessing the acceptability of risks in long-distance heating pipelines, and contributing to the safety of long-distance heating pipeline operation.

[0232] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for assessing the acceptability of failure consequences and risks of long-distance heating pipelines, characterized in that, Includes the following steps: S1. Identify the accident type and analyze and statistically analyze the scope and consequences of the accident. S2. Determine the rupture size, perform hydraulic calculations, and determine the leakage rate, system downtime, and total leakage for different types of pipes; S3. Perform physical effect modeling based on the type of long-distance heating pipeline. The types of long-distance heating pipelines include overhead long-distance heating pipelines and direct-buried long-distance heating pipelines. Determine the flash steam diffusion model for overhead long-distance heating pipelines and the three-stage model of pore accumulation-pressure breakthrough-ground diffusion for direct-buried pipelines. S4. Quantification of failure consequences and losses: Based on multiple factors, the losses of personnel casualties, environmental losses, and economic losses are quantified respectively; the losses of personnel casualties include economic compensation for death, serious injury, and minor injury; the environmental losses include the restoration costs of soil pollution, water pollution, and vegetation damage; and the economic losses include direct losses and indirect losses. S5. Based on the FN curve, determine the risk acceptability analysis of personnel casualties, based on the TI curve, determine the risk acceptability analysis of environmental losses, and based on the PLR ​​curve, determine the risk acceptability analysis of economic losses. Divide the risk areas into three categories: "unacceptable", "ALARP", and "widely acceptable". Then, based on the risk areas, define three levels of risk to complete the quantitative assessment of the consequences and risk acceptability of long-distance heating pipeline failure.

2. The method according to claim 1, characterized in that, In step S2, the pipeline type is a direct-buried long-distance heating pipeline. When calculating the leakage rate of the direct-buried long-distance heating pipeline, a soil constraint coefficient K is introduced because the leakage of the direct-buried long-distance heating pipeline is blocked by the soil medium. s The compressive effect of the soil on the leakage pore, i.e., the leakage rate of the directly buried long-distance heating pipeline, is quantified as follows: ； （1） In equation (1), K s K is the soil constraint coefficient. s The value of C ranges from 0.4 to 0.7; d ρ is the flow coefficient; A is the rupture area; ρ is the hot water density; P1 is the pressure inside the pipe; P2 is the ambient pressure. System downtime and total leakage: ； （2） In equation (2), t s This refers to the system downtime. This represents the leakage rate per unit time.

3. The method according to claim 1, characterized in that, In step S3, constructing the three-stage model of pore accumulation-pressure breakthrough-surface diffusion for the directly buried pipeline includes the following steps: S3-1, Pore accumulation stage; Leakage affects volume V influence for: ； （3） In equation (3), R influence The radius of the leakage impact is h; the burial depth is h. Pore ​​volume V pore for: ； （4） In equation (4), ϕ is the soil porosity; Critical breakthrough pressure P critical for: ； （5） In equation (5), P0 is the environmental pressure; The pore vapor mass m0 under ambient pressure is: ； （6） In equation (6), M is the molar mass of water, R is the universal gas constant, and T is the steam temperature; Required steam mass m at critical pressure critical for: ； （7） The additional steam mass Δm that needs to be accumulated is: ； （8） Steam generation rate steam for: ； （9） In equation (9), f is the flash evaporation ratio. leak,buried This refers to the leakage rate of a directly buried pipeline. Accumulation time t accumulation for: ； （10） Actual pore pressure P pore for: ； （11） S3-2, Pressure Breakout Phase: Determine if a breakout has occurred. The conditions for determining if a breakout has occurred are: ; I. If a breakthrough occurs; Nozzle area A vent for: ； （12） In equation (12), f crack is the crack opening ratio, representing the ratio of the actual crack opening area to the equivalent circular area; h is the equivalent circular nozzle diameter. Jet mass flow rate burst for: ； （13） In equation (13), ρ v The density of the vapor; Spray duration t burst for: ； （14） Effective source high v jet for: ； （15） ； （16） In equation (16), g is the acceleration due to gravity, g = 9.81 m / s²; S3-3, Ground diffusion stage; The ground point source concentration is: ； （17） In equation (17), u is the wind speed, and σ is the wind speed. y σ is the lateral diffusion parameter. z For vertical diffusion parameters; Let the damage threshold concentration C be... threshold Assuming it's a constant, the radius of influence R is obtained by iteratively solving the following equation: ； （18） The diffusion duration t for the concentration to drop to the safe threshold was calculated based on the Gaussian model. diffusion for: ； （19） In equation (19), x max η is the distance at which the concentration drops to the safe threshold. diffusion The diffusion efficiency coefficient; II. If no breakthrough occurs, the vapor diffuses slowly through the soil pores: ； （20） The radius of influence R is as follows, assuming no breakthrough occurs: ； （21） The area affected is: ； （22） In equation (22), A fatal R represents the area of ​​the lethal influence zone. fatal Radius of lethal effect; （23） In equation (23), A serious For the area of ​​the severely affected zone, R serious This significantly affects the radius; （24） In equation (24), A minor R represents the area of ​​the area with slight impact. minor It has a slight impact on the radius.

4. The method according to claim 1, characterized in that, In step S4, personal injury losses are quantified by combining statutory compensation, funeral expenses, or lost wages; the direct losses include repair, media, and emergency losses, while the indirect losses include heating outages, transportation, and agricultural losses.

5. The method according to claim 1, characterized in that, In step S5, in the TI curve, "T" represents the ecological restoration period, and "I" represents the environmental impact index, where: The environmental impact index I is: ； （25） In equation (25), w i Let be the weight of the i-th type of environmental element, and ;I i The impact index of the i-th type of environmental element is determined based on pollution concentration and ecological sensitivity. The ecological restoration period T is: ； （26） In equation (26), T soil For soil restoration years, T water For the water body recovery period, T veg The number of years required for vegetation to recover.

6. The method according to claim 1, characterized in that, In step S5, the expression for the PLR ​​curve is: ； （27） In equation (27), L(t) represents the cumulative economic loss at time t, L0 represents the initial economic loss of the accident; R is the resilience index, which represents the recovery capacity of the economic system per unit time; t is time. The toughness index R is: ； （28） In equation (28), T r Indicates the time required for the system to recover to an acceptable level; L c This indicates the acceptable threshold for economic loss.

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