Natural gas pipeline leakage diffusion risk evaluation method and system

Abstract

The invention discloses a natural gas pipeline leakage diffusion risk evaluation method and system, relates to the technical field of natural gas leakage, and aims at an urban underground gas pipeline system and establishes a natural gas pipeline leakage diffusion risk evaluation index system based on natural gas pipeline leakage diffusion accident reason analysis and related literatures. Using a fuzzy analytic hierarchy process and an entropy weight method to calculate the risk index weight of the leakage diffusion of the natural gas pipeline to obtain a subjective weight and an objective weight; calculating the subjective weight and the objective weight based on a least square method to obtain a combined weight; a natural gas pipeline leakage diffusion model is constructed, so that the natural gas pipeline structure and the natural gas leakage diffusion influence are clearer, the natural gas pipeline leakage diffusion risk level can be simulated, the safety of an urban gas pipeline system is better evaluated, targeted measures are formulated, and the safety of the urban gas pipeline system is improved. The reliability level of urban gas pipelines is improved, and the disaster prevention and reduction capacity of an urban lifeline system is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas leakage, and more particularly to a method and system for evaluating the risk of natural gas pipeline leakage and diffusion. Background Art

[0002] At present, natural gas is a clean and low-carbon fossil energy. When burned, it produces less carbon dioxide than other fossil fuels, which helps to slow down the greenhouse effect of the earth, fundamentally improve environmental quality, reduce carbon emissions, and promote low-carbon production and life. Natural gas is currently the cleanest fossil energy and a bridge for the transition from high-carbon to zero-carbon energy. It plays a positive role in achieving carbon neutrality. Anchoring the goals of carbon peak and carbon neutrality, promoting the safe and efficient use of clean, low-carbon energy will help to orderly guide non-fossil energy consumption and replace coal with electricity and gas, and develop distributed energy such as rooftop photovoltaics.

[0003] Natural gas is mainly transported through two methods: gas pipelines and liquefied natural gas. Gas pipelines are the main means of transportation, and their safe operation is closely related to the sustainable development of modern social economy. Common pipeline laying methods include underground laying and overhead laying. As the most commonly used and in most areas, underground laying is the most common laying method. Due to the wide range of areas where pipelines pass through, complex geological environments, and frequent human activities, natural gas pipeline leakage accidents often occur, and it is very easy to cause natural gas pipeline explosions, and even cause serious casualties, property losses, and accidents that endanger public safety.

[0004] In the relevant methods, in order to evaluate the danger of natural gas pipeline leakage and diffusion, subjective or objective evaluation methods are used to evaluate the danger of natural gas pipeline leakage and diffusion. However, in certain specific situations, the accuracy of this evaluation method may be affected to a certain extent, resulting in an inaccurate determination of the danger of natural gas leakage and diffusion.

[0005] Therefore, how to improve the accuracy of determining the risk of natural gas leakage and diffusion is an urgent problem that needs to be solved by those skilled in the art. Summary of the invention

[0006] In view of this, the present invention provides a method and system for evaluating the risk of leakage and diffusion of a natural gas pipeline to solve the problems existing in the background technology.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A method for evaluating the risk of leakage and diffusion of a natural gas pipeline, comprising:

[0009] Consult the data and establish a natural gas pipeline leakage and diffusion hazard assessment index system;

[0010] The fuzzy analytic hierarchy process and entropy weight method are used to calculate the weight of the natural gas pipeline leakage and diffusion hazard index, and the subjective weight and objective weight are obtained;

[0011] The subjective weight and the objective weight are calculated based on the least square method to obtain the combined weight;

[0012] Construct a natural gas pipeline leakage diffusion model;

[0013] Input the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model, and obtain the model simulation results;

[0014] The danger of natural gas pipeline leakage and diffusion is evaluated based on the model simulation results.

[0015] Optionally, the calculation process of the subjective weight is:

[0016] Invite experts in related fields to compare the evaluation indicators at the same level in the natural gas pipeline leakage and diffusion hazard evaluation index system, and give scores based on their relative importance;

[0017] According to the expert scoring results, construct the fuzzy judgment matrix at each level;

[0018] A fuzzy consistent judgment matrix is ​​established, and the subjective weight of each evaluation index is calculated based on the fuzzy consistent judgment matrix.

[0019] Optionally, the objective weight is calculated as follows:

[0020] Collect statistical data on natural gas pipeline leakage accidents and construct an original evaluation matrix based on evaluation indicators and samples;

[0021] The original evaluation matrix is ​​normalized, and the information entropy value and information utility value of each evaluation index are calculated, and then the objective weight is calculated.

[0022] Optionally, constructing a natural gas pipeline leakage diffusion model specifically includes:

[0023] According to the geometric shape of natural gas pipeline, GAMBIT software is used to establish the leakage diffusion model of natural gas pipeline;

[0024] Set the grid type of the natural gas pipeline leakage diffusion model and divide the grid;

[0025] Define the boundary conditions and initial conditions of the natural gas pipeline leakage diffusion model;

[0026] Set the solution parameters of GAMBIT software or CFD solver;

[0027] The model construction is completed and the natural gas pipeline leakage diffusion model is derived.

[0028] Optionally, the fuzzy judgment matrix is ​​specifically:

[0029]

[0030] In the formula, the matrix A=(a ij ) n×n And a ij +a ji =1, n represents the order of the matrix.

[0031] Optionally, the specific process of establishing the fuzzy consistent judgment matrix is:

[0032] For the fuzzy judgment matrix A=(a ij ) n×n Sum by row Then make the following mathematical transformation:

[0033]

[0034] Thus, we can get the fuzzy consistent judgment matrix R = (r ij ) n×n .

[0035] Optionally, construct the original evaluation matrix with m time nodes and n indicators:

[0036] X=[x ij ] m×n

[0037] Normalization processing includes: For positive indicators, the leakage and diffusion risk processing formula is as follows:

[0038]

[0039] For negative indicators, the formula for handling leakage and diffusion risk is as follows:

[0040]

[0041] Optionally, the process of calculating the objective weight includes:

[0042] Calculate the information entropy value e of the indicator j and information utility value d j :

[0043]

[0044] P ij is the weight of the i-th sample under the j-th indicator.

[0045] d j =1-e j

[0046] Determine the weight of evaluation indicators:

[0047]

[0048] Wherein, i, k = 1, 2, ..., n, n is the time node, and m is the number of time nodes.

[0049] Optionally, the subjective weight and the objective weight are combined and calculated by a combined weighting method based on the least squares method to obtain a combined weight:

[0050]

[0051] Among them, β 1 , β 2 are the parameters to be solved, which respectively represent the contribution of subjective weight and objective weight in the combined weight.

[0052] A natural gas pipeline leakage and diffusion hazard assessment system, comprising:

[0053] Index system establishment module, consult data, and establish a natural gas pipeline leakage and diffusion hazard evaluation index system;

[0054] The subjective and objective weight calculation module uses the fuzzy analytic hierarchy process and entropy weight method to calculate the weight of the natural gas pipeline leakage and diffusion hazard index to obtain the subjective weight and objective weight;

[0055] The weight combination module calculates the subjective weight and the objective weight based on the least squares method to obtain the combined weight;

[0056] Model building module, building a natural gas pipeline leakage diffusion model;

[0057] The simulation result output module inputs the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model and obtains the model simulation results;

[0058] The evaluation module evaluates the risk of leakage and diffusion of natural gas pipelines based on the model simulation results.

[0059] It can be seen from the above technical solution that, compared with the prior art, the present invention discloses a method and system for evaluating the hazard of natural gas pipeline leakage and diffusion. For urban underground gas pipeline systems, based on the analysis of the causes of natural gas pipeline leakage and diffusion accidents and related literature, a natural gas pipeline leakage and diffusion hazard evaluation index system is established, and a natural gas pipeline leakage and diffusion model is constructed, so that the natural gas pipeline structure and the impact of natural gas leakage and diffusion are clearer, and the natural gas pipeline leakage and diffusion hazard level can be simulated, so as to better evaluate the safety of urban gas pipeline systems, and formulate targeted measures to improve the reliability level of urban gas pipelines and ensure the disaster prevention and mitigation capabilities of urban lifeline systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0061] Figure 1 The present invention provides a schematic diagram of the method flow structure. DETAILED DESCRIPTION

[0062] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] The embodiment of the present invention discloses a method for evaluating the risk of leakage and diffusion of a natural gas pipeline. Figure 1 As shown, including:

[0064] Consult the data and establish a natural gas pipeline leakage and diffusion hazard assessment index system;

[0065] This includes consulting relevant literature and summarizing the causes of natural gas leakage accidents; combining expert opinions to build a natural gas pipeline leakage and diffusion hazard evaluation index system.

[0066] The fuzzy analytic hierarchy process and entropy weight method are used to calculate the weight of the natural gas pipeline leakage and diffusion hazard index, and the subjective weight and objective weight are obtained;

[0067] The subjective weight and the objective weight are calculated based on the least square method to obtain the combined weight;

[0068] Construct a natural gas pipeline leakage diffusion model;

[0069] Input the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model, and obtain the model simulation results;

[0070] The danger of natural gas pipeline leakage and diffusion is evaluated based on the model simulation results.

[0071] The calculation process of subjective weight is:

[0072] Invite experts in related fields to compare the evaluation indicators at the same level in the natural gas pipeline leakage and diffusion hazard evaluation index system, and give scores based on their relative importance;

[0073] According to the expert scoring results, construct the fuzzy judgment matrix at each level;

[0074] A fuzzy consistent judgment matrix is ​​established, and the subjective weight of each evaluation index is calculated based on the fuzzy consistent judgment matrix.

[0075] Specifically: Based on the expert scoring results, construct the judgment matrix of each level. The judgment matrix is ​​a square matrix whose elements represent the relative importance of each indicator at the same level and calculate the subjective weight;

[0076] Construct a fuzzy judgment matrix based on the expert scoring results;

[0077]

[0078] Matrix A=(a ij ) n×n And a ij +a ji =1, n represents the order of the matrix.

[0079] Establish a fuzzy consistent judgment matrix. For the fuzzy complementary matrix A=(a ij ) n×n Sum the rows to get the fuzzy complementary matrix A = (a ij ) n×n Sum by row Then make the following mathematical transformation, as shown in formula (2).

[0080]

[0081] Thus, we can get the fuzzy consistent judgment matrix R = (r ij ) n×n . According to formula (2), after mathematical transformation, r can be satisfied. ij =r ik -r jk +0.5, i,j,k=1,2,…,n.

[0082] Based on the fuzzy consistent judgment matrix R = (r ij ) n×n Calculate the weight of each indicator ω=(ω 1 ,ω 2 ,…,ω n ), as shown in formula (3).

[0083]

[0084] The calculation process of objective weight is:

[0085] Collect statistical data on natural gas pipeline leakage accidents and construct an original evaluation matrix based on evaluation indicators and samples;

[0086] The original evaluation matrix is ​​normalized, and the information entropy value and information utility value of each evaluation index are calculated, and then the objective weight is calculated.

[0087] Specifically: construct the initial evaluation matrix. Construct the original matrix with m time nodes and t indicators:

[0088] X=[x ij ] m×t (4)

[0089] For positive indicators, the leakage and diffusion risk treatment formula is as follows:

[0090]

[0091] For negative indicators, the formula for handling leakage and diffusion risk is as follows:

[0092]

[0093] In the formula, x ij is the original value of the jth index of the ith unit, x′ ij is the jth index of the ith unit after the safety level assessment, max(x ij ) is the maximum value, min(x ij ) is the minimum value.

[0094] Calculate the information entropy value e of the indicator j and information utility value d j :

[0095]

[0096] P ij is the weight of the i-th sample under the j-th indicator.

[0097] d j =1-e j (8)

[0098] Determine the weight of evaluation indicators

[0099]

[0100] The subjective weight and the objective weight are combined to calculate the combined weight through the combined weighting method based on the least squares method;

[0101]

[0102] In the formula, β 1 , β 2 are the parameters to be solved, which respectively represent the contribution of subjective weight and objective weight in the combined weight.

[0103] Construct a model of natural gas pipeline leakage and diffusion and perform model simulation.

[0104] Exemplarily, the present invention provides a schematic diagram of factors affecting safety resilience, classifies the factors affecting the risk of natural gas pipeline leakage and diffusion into four aspects: leakage source characteristics, leakage material characteristics, environmental factors, and diffusion consequences, and establishes a natural gas pipeline leakage and diffusion risk evaluation index system, which is divided into 5 primary indicators and 19 secondary indicators, as shown in Table 1.

[0105] Table 1 Evaluation index system for the risk of leakage and diffusion of natural gas pipelines

[0106]

[0107]

[0108] Exemplarily, the present invention provides a schematic flow chart of establishing a geometric model of a pipeline using GAMBIT software, which mainly includes the following steps:

[0109] Set the grid type and divide the grid;

[0110] Choose the appropriate mesh type based on the complexity of the model and the computational requirements;

[0111] Divide the mesh and check the mesh quality to ensure there are no negative volumes, highly distorted meshes, etc.

[0112] Define the boundary conditions and initial conditions of the model;

[0113] Define the inlet boundary conditions including leakage rate, properties of the leaking material, etc.;

[0114] Define the outlet boundary conditions of the diffusion region, such as pressure, temperature, etc.;

[0115] Set boundary conditions for pipe walls and other solid surfaces, such as no-slip, adiabatic, etc.

[0116] Define the initial conditions for the start of the simulation, such as pressure, temperature, velocity distribution in the flow field, etc.

[0117] Set solution parameters in GAMBIT or the CFD solver (such as FLUENT) that is subsequently called, such as the number of iterations, convergence criteria, solution algorithm, etc.

[0118] Export the model and mesh constructed in GAMBIT, load the model in the CFD solver, set the solution parameters, and run the solution process;

[0119] Use the post-processing tools of the CFD solver (such as the post-processing module provided by FLUENT) to analyze the simulation results;

[0120] The danger of natural gas pipeline leakage and diffusion is assessed based on the simulation results.

[0121] A natural gas pipeline leakage and diffusion hazard assessment system, comprising:

[0122] Index system establishment module, consult data, and establish a natural gas pipeline leakage and diffusion hazard evaluation index system;

[0123] The subjective and objective weight calculation module uses the fuzzy analytic hierarchy process and entropy weight method to calculate the weight of the natural gas pipeline leakage and diffusion hazard index to obtain the subjective weight and objective weight;

[0124] The weight combination module calculates the subjective weight and the objective weight based on the least squares method to obtain the combined weight;

[0125] Model building module, building a natural gas pipeline leakage diffusion model;

[0126] The simulation result output module inputs the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model and obtains the model simulation results;

[0127] The evaluation module evaluates the risk of leakage and diffusion of natural gas pipelines based on the model simulation results.

[0128] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0129] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for assessing the risk of leakage and diffusion of a natural gas pipeline, characterized in that: include: Consult the data and establish a natural gas pipeline leakage and diffusion hazard assessment index system; The fuzzy analytic hierarchy process and entropy weight method are used to calculate the weight of the natural gas pipeline leakage and diffusion hazard index, and the subjective weight and objective weight are obtained; The subjective weight and the objective weight are calculated based on the least square method to obtain the combined weight; Construct a natural gas pipeline leakage diffusion model; Input the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model, and obtain the model simulation results; The danger of natural gas pipeline leakage and diffusion is evaluated based on the model simulation results.

2. A method for assessing the risk of leakage and diffusion of a natural gas pipeline according to claim 1, characterized in that: The calculation process of the subjective weight is: Invite experts in related fields to compare the evaluation indicators at the same level in the natural gas pipeline leakage and diffusion hazard evaluation index system, and give scores based on their relative importance; According to the expert scoring results, construct the fuzzy judgment matrix at each level; A fuzzy consistent judgment matrix is ​​established, and the subjective weight of each evaluation index is calculated based on the fuzzy consistent judgment matrix.

3. A method for evaluating the risk of leakage and diffusion of a natural gas pipeline according to claim 1, characterized in that: The calculation process of the objective weight is: Collect statistical data on natural gas pipeline leakage accidents and construct an original evaluation matrix based on evaluation indicators and samples; The original evaluation matrix is ​​normalized, and the information entropy value and information utility value of each evaluation index are calculated, and then the objective weight is calculated.

4. A method for evaluating the risk of leakage and diffusion of a natural gas pipeline according to claim 1, characterized in that: The construction of natural gas pipeline leakage diffusion model specifically includes: According to the geometric shape of natural gas pipeline, GAMBIT software is used to establish the leakage diffusion model of natural gas pipeline; Set the grid type of the natural gas pipeline leakage diffusion model and divide the grid; Define the boundary conditions and initial conditions of the natural gas pipeline leakage diffusion model; Set the solution parameters of GAMBIT software or CFD solver; The model construction is completed and the natural gas pipeline leakage diffusion model is derived.

5. A method for evaluating the risk of leakage and diffusion of a natural gas pipeline according to claim 2, characterized in that: The fuzzy judgment matrix is ​​specifically: In the formula, the matrix A=(a ij ) n×n And a ij +a ji =1, n represents the order of the matrix.

6. A method for assessing the risk of leakage and diffusion of a natural gas pipeline according to claim 2, characterized in that: The specific process of establishing the fuzzy consistent judgment matrix is ​​as follows: For the fuzzy judgment matrix A=(a ij ) n×n Sum by row Then make the following mathematical transformation: Thus, we can get the fuzzy consistent judgment matrix R = (r ij ) n×n .

7. A method for assessing the risk of leakage and diffusion of a natural gas pipeline according to claim 3, characterized in that: Construct the original evaluation matrix with m time nodes and n indicators: X=[x ij ] m×n Normalization processing includes: For positive indicators, the leakage and diffusion risk processing formula is as follows: For negative indicators, the formula for handling leakage and diffusion risk is as follows:

8. A method for assessing the risk of leakage and diffusion of a natural gas pipeline according to claim 3, characterized in that: The process of calculating objective weights includes: Calculate the information entropy value e of the indicator j and information utility value d j : P ij is the weight of the i-th sample under the j-th indicator; d j =1-e j Determine the weight of evaluation indicators: Wherein, i, k = 1, 2, ..., n, n is the time node, and m is the number of time nodes.

9. A method for evaluating the risk of leakage and diffusion of a natural gas pipeline according to claim 1, characterized in that: Through the combined weighting method based on the least squares method, the subjective weight and the objective weight are combined to calculate the combined weight: Among them, β1 and β2 are parameters to be solved, which respectively represent the contribution of subjective weight and objective weight in the combined weight.

10. A natural gas pipeline leakage and diffusion risk assessment system, using a natural gas pipeline leakage and diffusion risk assessment method according to any one of claims 1 to 9, characterized in that: include: Index system establishment module, consult data, and establish a natural gas pipeline leakage and diffusion hazard evaluation index system; The subjective and objective weight calculation module uses the fuzzy analytic hierarchy process and entropy weight method to calculate the weight of the natural gas pipeline leakage and diffusion hazard index to obtain the subjective weight and objective weight; The weight combination module calculates the subjective weight and the objective weight based on the least squares method to obtain the combined weight; Model building module, building a natural gas pipeline leakage diffusion model; The simulation result output module inputs the actual data and combined weights of the natural gas pipeline into the natural gas pipeline leakage diffusion model and obtains the model simulation results; The evaluation module evaluates the risk of leakage and diffusion of natural gas pipelines based on the model simulation results.

Images