Gas pipeline leakage heat radiation prediction method based on terrain and temperature correction

Abstract

The present application relates to gas pipeline safety protection problems, specifically relates to a kind of gas pipeline leakage heat radiation prediction method based on topography and temperature correction.Method includes: obtaining pipeline design parameters and surrounding environment data, according to pipeline design parameters and surrounding environment data, calculate gas leakage flow rate Q, according to gas leakage flow rate Q, calculate heat release rate Q';According to the absorption, heat conduction and reflection characteristics of the ground surface material around the pipeline, a topographic correction factor calculation model is constructed;The topographic correction factor calculation model is introduced into the basic multi-point source model for iteration until convergence, and the total radiation intensity obtained by convergence is obtained;Based on the difference between actual temperature and standard ambient temperature, the total radiation intensity obtained by convergence is corrected to obtain the final total radiation intensity.The present application can accurately predict the distribution of gas pipeline heat radiation intensity under complex terrain and different environmental temperature conditions, and then accurately evaluate the hazard range and influence area of heat radiation in explosion accident.

Description

TECHNICAL FIELD

[0001] The present application relates to the safety protection of gas pipelines, in particular to a gas pipeline leakage heat radiation prediction method based on terrain and temperature correction. BACKGROUND

[0002] Gas (hydrogen, natural gas, etc.) has high flammability and rapid diffusion, and gas pipeline leakage or rupture events can cause serious fire and explosion accidents. After leakage, explosive mixed gas is easily formed, causing extensive thermal radiation hazards. Therefore, establishing an accurate gas pipeline heat radiation intensity prediction model is of great guiding significance for assessing the flammable and explosive hazard range and developing safety distances.

[0003] Terrain and environmental temperature are key environmental factors affecting the flammable and explosive heat radiation hazards of gas pipelines. Terrain (such as mountains, valleys, etc.) can change the propagation path of heat radiation, and the reflection, absorption and heat conduction characteristics of different topographies significantly affect the heat radiation distribution, making the attenuation characteristics under complex terrain conditions more uncertain. Changes in environmental temperature also affect the combustion intensity and radiation heat value. High temperature conditions can intensify radiation intensity and expand the hazard range.

[0004] However, current research on the effects of terrain and temperature on heat radiation is still insufficient. Traditional models are based on the idealization and homogenization of topography, only considering the temperature changes of the flame itself and ignoring the effects of environmental temperature. They are difficult to accurately describe the heat radiation characteristics under complex terrain and variable environments, resulting in deviations in the prediction results in actual applications.

[0005] Therefore, there is an urgent need for a gas pipeline heat radiation prediction method based on terrain and temperature correction to improve the accuracy and applicability of the prediction and provide a scientific basis for gas pipeline safety protection. SUMMARY

[0006] The technical problem to be solved by the present application is to overcome the defects of the prior art and provide a gas pipeline leakage heat radiation prediction method based on terrain and temperature correction, which can accurately predict the heat radiation intensity distribution of gas pipelines under complex terrain and different environmental temperature conditions, and further accurately assess the hazard range and impact area of heat radiation in flammable and explosive accidents.

[0007] To solve the above technical problems, the technical scheme of the present application is: a gas pipeline leakage heat radiation prediction method based on terrain and temperature correction, comprising:

[0008] Obtain pipeline design parameters and surrounding environment data, calculate the gas leakage flow rate Q according to the pipeline design parameters and surrounding environment data, and calculate the heat release rate ;

[0009] According to the absorption, heat conduction and reflection characteristics of the surface material around the pipeline, a topographic correction factor calculation model is constructed.

[0010] The topographic correction factor calculation model is introduced into the basic multi-point source model for iteration until convergence, and the total radiation intensity obtained by convergence is obtained.

[0011] The total radiation intensity obtained by convergence is corrected based on the difference between the actual temperature and the standard ambient temperature, and the final total radiation intensity is obtained.

[0012] Further, according to the absorption, heat conduction and reflection characteristics of the surface material around the pipeline, a topographic correction factor calculation model is constructed; specifically:

[0013] According to the region where the pipeline is located, the surface material with a surrounding proportion exceeding a threshold value is determined through a geographic information system or field survey.

[0014] The comprehensive characteristic parameters of the surface material with a proportion exceeding the threshold value are determined; wherein the comprehensive characteristic parameters include the absorption coefficient , the heat conduction coefficient and the reflection coefficient .

[0015] The topographic correction factor calculation model is constructed by combining the obtained comprehensive characteristic parameters and the view factor in the basic multi-point source model.

[0016] Further, the calculation model of the topographic correction factor is:

[0017]

[0018] In the formula, is the topographic correction factor of the th point source, is the absorption coefficient of the material; is the view factor; is the heat conduction coefficient of the surface material; represents the thermal radiation intensity of the th point source, with the unit of KW / m 2 . is the reflection coefficient of the material.

[0019] Further, the topographic correction factor calculation model is introduced into the basic multi-point source model for iteration, and the iteration formula is:

[0020]

[0021] ·

[0022] In the formula, is the topographic correction factor of the The calculation result of the landform correction factor of the i th point source, 、 The thermal radiation intensity of the i th point source calculated in the i th time and the i-1 th time respectively.

[0023] Further, the basic multi-point source model is:

[0024]

[0025] ；

[0026]

[0027] Wherein, is the total thermal radiation intensity of the basic multi-point source model; is the weight of the i th point source, is the total number of point sources; N is the atmospheric transmittance; is the radiation fraction; is the heat release rate; is the distance from the j th point to the target point, is the cosine value of the angle between each two-point line and the outer normal of the target, that is, the view factor; N is the number of point sources; n is the total number of point sources of the multi-point source, and the initial radiation intensity of the i th point source is calculated according to the formula

[0028] Further, the total radiation intensity obtained by convergence is corrected based on the difference between the actual temperature and the standard ambient temperature; the specific formula is:

[0029]

[0030] Wherein, is the final total radiation intensity, is the total radiation intensity obtained by convergence, is the standard ambient temperature; is the difference between the actual ambient temperature and the standard ambient temperature.

[0031] The application also provides a damage range prediction method for gas pipeline leakage based on terrain and temperature correction, which adopts the terrain and temperature correction based gas pipeline leakage thermal radiation prediction method to predict the final total radiation intensity of each target point;

[0032] Based on the final total radiation intensity, the damage range and the safety distance are predicted; specifically:

[0033] ​​​​​

[0034]

[0035] total radiation amount of the improved radiation source per unit time; area of the radiation source (pipe leakage jet fire); final total radiation intensity; distance from the center point of the radiation source to the target point, i.e., safety distance radius; atmospheric transmissivity, thermal radiation intensity at a certain space point, i.e., thermal radiation value threshold.

[0036] After the above technical scheme is adopted, the terrain correction factor and the temperature correction are introduced when the thermal radiation intensity is calculated, the attenuation effect of the terrain on the thermal radiation propagation path and intensity, and the amplification effect of the ambient temperature on the combustion intensity and the radiation intensity are comprehensively considered, so that the accuracy of the thermal radiation intensity prediction is significantly improved. This method improves the prediction accuracy and helps to more effectively evaluate the thermal radiation hazard range in the gas pipeline explosion accident, and provides a scientific basis for formulating safety distance and protection measures. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 a flowchart of the gas pipeline leakage thermal radiation prediction method based on terrain and temperature correction of the present application;

[0038] Figure 2 a radiation intensity calculation result error comparison chart of the embodiment and the comparative example of the present application and the actual accident report data;

[0039] Figure 3 a comparison chart of the basic model, the improved model and the actual accident thermal radiation intensity data;

[0040] Figure 4 an error comparison chart of the improved model and the actual data. DETAILED DESCRIPTION

[0041] In order to make the content of the present application more easily understood, the present application will be further described in detail below according to specific embodiments and in combination with the drawings.

[0042] As shown in Figure 1 , a gas pipeline leakage thermal radiation prediction method based on terrain and temperature correction comprises:

[0043] Step S1, obtaining pipeline design parameters and surrounding environment data, calculating a gas leakage flow rate Q according to the pipeline design parameters and the surrounding environment data, and calculating a heat release rate according to the gas leakage flow rate Q.

[0044] In this step, the gas leakage flow rate Q is calculated according to the pipeline design parameters and the surrounding environment data, which is a prior art and is described in detail in the Chinese patent with the patent name of "A gas pipeline jet fire action range prediction method" and the patent number of 201910830368.3; the heat release rate is calculated according to the gas leakage flow rate Q which is also a prior art and is described in detail in the book "A consideration of methods of determining the radiative characteristics of jet fires" by HANKINSON G.

[0045] Step S2, a topographic correction factor calculation model is constructed according to the absorption, heat conduction and reflection characteristics of the surrounding surface material of the pipeline; specifically:

[0046] Step S21, according to the region where the pipeline is located, the surrounding surface material whose proportion exceeds the threshold value is determined through the geographic information system (GIS) or field survey, that is, the main material type of the surrounding surface, such as rock, soil, vegetation, water, etc.

[0047] Step S22, the comprehensive characteristic parameters of the main material of the surrounding surface are determined, and in the case where the proportion of the surrounding surface material exceeds one kind, the comprehensive characteristic parameters are calculated based on the area proportion (weighted average method) of each material to determine the final topographic correction factor. For reference, the reports on the thermal properties of soil and natural materials published by the United States Geological Survey (USGS), NASA, European Space Agency (ESA), etc., as well as the Chinese Soil Society, the Civil Engineering Manual, etc. Among them, the comprehensive characteristic parameters include the absorption coefficient , the heat conduction coefficient and the reflection coefficient ;

[0048] In the case where the surrounding surface material exceeds one kind, the method of proportional weighting is adopted to calculate the comprehensive characteristic parameters. The specific calculation formula is as follows:

[0049]

[0050] Among them:

[0051] , the comprehensive characteristic parameters, such as the absorption coefficient, the heat conduction coefficient or the reflection coefficient;

[0052] , the characteristic parameters of the first material;

[0053] , the area proportion of the first material, which satisfies .

[0054] In practical applications, the area ratio data of each material can be obtained through a geographic information system (GIS) or field survey, and the comprehensive characteristic parameters can be calculated according to the thermal characteristics (such as absorption, thermal conductivity and reflection coefficient) of the materials. This method can better reflect the overall response of the multi-material mixed area to thermal radiation.

[0055] In step S23, the acquired comprehensive characteristic parameters are combined with the view factor in the basic multi-point source model to construct a topographic correction factor calculation model.

[0056] In this step, according to the physical principles of absorption, reflection and thermal conductivity, the constructed topographic correction factor calculation model includes absorption, thermal conductivity and reflection terms, which correspond to the thermal response characteristics of the material in different aspects, respectively.

[0057] The absorption term describes the absorption ability of the material to the incident thermal radiation, which is related to the absorption coefficient and the view factor The absorption coefficient represents the absorption ability of the material, and different materials (such as soil and rock) have different absorption coefficients. The view factor reflects the geometric relationship between the heat source and the material surface, and determines the effective visibility of the material surface to the heat source.

[0058] The thermal conductivity term describes the ability of the material to conduct heat to the interior after absorbing heat. Materials with high thermal conductivity will conduct the absorbed heat to the interior more quickly, resulting in lower surface temperature rise and reducing the efficiency of absorbing radiation energy. The higher the thermal conductivity, the slower the surface temperature rise of the material after absorbing heat, which shows the so-called "thermal inertia". In order to describe the relationship that the efficiency of material absorbing heat decreases with the increase of thermal conductivity , the ln function is used to represent this decreasing trend, and the thermal conductivity response term is:

[0059]

[0060] wherein, is the thermal conductivity coefficient of the material on the ground surface, ; is the incident radiation intensity, KW / m2; is the view factor. When is small, the material absorbs more heat and responds faster. When is large, the thermal response of the material tends to be saturated, and the surface temperature rise slows down, thereby reducing the actual absorption of radiation.

[0061] The reflection term describes the reflection ability of the material to thermal radiation, which is related to the reflection coefficient and the view factor Reflectance The reflectance of a material is the ratio of the reflected radiation to the incident radiation. View factor correction term The reflectance of a material is the ratio of the reflected radiation to the incident radiation.

[0062]

[0063] Where, is the reflectance of the material, is the view factor.

[0064] In practical applications, the absorption behavior and thermal behavior of a material are interdependent, so multiplying the absorption term by the thermal response term can more accurately describe the absorption effect of the material under different thermal conductivity conditions. If the thermal conductivity is low, the heat absorbed by the material will accumulate on the surface, and the absorption effect will be strong; if the thermal conductivity is high, the heat will be conducted to the interior more quickly, resulting in a weakening of the surface absorption effect. At the same time, to represent the complementary relationship between physically absorbed and reflected, subtracting the reflection term can ensure that the structure of the entire formula complies with the principle of energy conservation, i.e., the total amount of thermal radiation received by the material is either absorbed or reflected, ensuring the accuracy of the material's response to thermal radiation.

[0065] Therefore, the calculation model of the topographic correction factor of a single point source (the first point source) is: j

[0066]

[0067] Where, is the topographic correction factor of the single point source, is the absorption coefficient of the material; is the view factor; is the thermal conductivity of the surface material, ; is the thermal radiation intensity of the first point source, j ; is the reflectance of the material; Step S3: Introduce the topographic correction factor calculation model into the basic multi-point source model for iteration until convergence, obtaining the total radiation intensity obtained by convergence;

[0068] Where, the basic multi-point source model is:

[0069]

[0070]

[0071] ； ​​

[0072]

[0073] wherein, is the total thermal radiation intensity of the base multi-point source model, ; is the weight of the jth point source, is the total number of point sources; N is the atmospheric transmissivity, generally taken as 1; is the radiation fraction, which is taken according to the fuel type, generally taken as 0.2 for natural gas and 0.05 for hydrogen; is the heat release rate, ; is the distance from the jth point source to the target point, m, is the cosine value of the angle between each two-point line and the outer normal of the target, i.e., the view factor; N is the number of point sources; n is the total number of point sources of the multi-point source.

[0074] take the initial iteration value of the thermal radiation as introduce the topographic correction factor into the multi-point source model, and iteratively calculate the total thermal radiation intensity until convergence: the calculation formula of the initial radiation intensity of the jth point source is .

[0075] The following is the iteration process. In the first iteration, the initial thermal radiation intensity of each point source is calculated

[0076]

[0077] is the thermal radiation intensity calculated in the first iteration, representing the initial total thermal radiation intensity; is the weight of the jth point source; is the atmospheric transmissivity, generally taken as 1; is the heat release rate, representing the heat release rate of each point source; is the view factor between the jth point source and the target point, representing the angle between the line from the target point to the jth point source and the outer normal of the target point; is the distance from the jth point source to the target point; is the total number of point sources; The total thermal radiation intensity is obtained by superposition:

[0078]

[0079]

[0080] ​​​​​​​Then the topographic correction factor of each point source is calculated:

[0081]

[0082] is the topographic correction factor of the first iteration of the th point source; is the absorption coefficient; is the view factor; is the initial radiation intensity of the th point source, calculated by ; is the reflection coefficient; is the thermal conductivity of the ground material;

[0083] Then the radiation intensity of each point source is corrected by the topographic correction factor of each point source:

[0084]

[0085] Finally, all the corrected point source radiation intensities are added up to obtain the total radiation intensity:

[0086]

[0087] Second iteration, first calculate the topographic correction factor of each point source : for each point source , according to the radiation intensity obtained in the first iteration

[0088]

[0089] The initial radiation intensity of the th point source is multiplied by its corresponding topographic correction factor to obtain the updated radiation intensity:

[0090]

[0091] All the point source radiation intensities are added up to obtain the total radiation intensity of the second iteration:

[0092] ...

[0094] Iteration until convergence, first take the radiation intensity obtained in the th iteration as the basis to calculate the topographic correction factor of the th iteration:

[0095]

[0096] The first A point source in The radiation intensity in the iteration The corresponding terrain correction factor Multiply them together to get the updated radiation intensity:

[0097]

[0098] The radiation intensity of all point sources Add up and get The total radiation intensity of the iteration:

[0099]

[0100] in, For the The total thermal radiation intensity obtained by the iteration is =1,2,3......, ; For the The landform factor obtained by the iteration is =1,2,3......K, K is the number of iterations until convergence; For the The weight of each point source; is the atmospheric transmittance, generally taken as 1, is the radiation fraction, which is determined by the fuel type. Natural gas is generally set to 0.2, and hydrogen is generally set to 0.05. Heat release rate ; is the distance between the jth point and the target point, m, is the cosine value of the angle between the line connecting each two points and the external normal of the target object, that is, the viewing factor; N is the number of point sources; n is the total number of point sources in multiple point sources; is the absorption coefficient of the material; The cosine value of the angle between the line connecting each two points and the external normal of the target object, that is, the viewing angle factor; is the reflection coefficient of the material.

[0101] Step S4: Correcting the converged total radiation intensity based on the difference between the actual temperature and the standard ambient temperature to obtain a final total radiation intensity.

[0102] The actual ambient temperature is , standard ambient temperature = , then the temperature difference = According to the Stefan-Boltzmann law, the radiation intensity and temperature Proportional to the fourth power of:

[0103]

[0104] At standard ambient temperature The radiation intensity is In actual applications, the ambient temperature will change, especially high temperature will increase the intensity of thermal radiation. , the radiation intensity becomes accordingly:

[0105]

[0106] Will Perform Taylor expansion and retain the first-order term to approximate:

[0107]

[0108] The final ambient temperature correction formula is:

[0109]

[0110] in, is the final total thermal radiation intensity, For the The total thermal radiation intensity obtained by iteration until convergence is the standard ambient temperature, take ; The actual ambient temperature and the standard ambient temperature (298K) difference, .

[0111] A method for predicting the damage range of a gas pipeline leak based on terrain and temperature correction includes:

[0112] The final total radiation intensity received by each target point is predicted using the gas pipeline leakage thermal radiation prediction method based on terrain and temperature correction in the above embodiment;

[0113] Based on the final total radiation intensity, the damage range and safety distance are predicted; specifically:

[0114] Among them, the basic calorific value distance formula is:

[0115]

[0116]

[0117] Where: is the total radiation amount per unit time of the radiation source, ; is the gas leakage rate, ; is the heat of combustion of the fuel, ; R is the distance from the leakage point to the target point, m; is the thermal radiation intensity of a certain space point KW / m2; is the atmospheric transmittance, generally taken as 1;

[0118] The improved distance formula is:

[0119]

[0120]

[0121] is the total radiation of the improved radiation source per unit time, ; is the final total radiation intensity, kW / m2; ; is the area of the radiation source (pipeline leakage jet fire), m2; is the distance from the center point of the improved radiation source to the target point, m; is the thermal radiation intensity of a certain space point, i.e. the threshold value of thermal radiation, kW / m2. .

[0122] It should be noted that the calculation method of parameter A, and the calculation method of the geometric center point of the radiation source in (the distance from the center point of the improved radiation source, i.e. the center of the jet fire, to the target point) is the prior art, which can be found in "Research on Natural Gas Pipeline Failure Jet Fire Hazard Model", and will not be described in detail here. The reason for not writing the pipeline leakage point but writing the center point of the radiation source is that when calculating the safety distance in international standards, the geometric center point of the pipeline leakage jet fire is usually considered as the standard due to the influence of the volume of the jet fire, rather than directly using the pipeline leakage point.

[0123] The above-mentioned scheme related to the embodiments will be described in detail in combination with specific embodiments.

[0124] Embodiment:

[0125] As shown in the drawings, a gas pipeline leakage thermal radiation prediction method based on terrain and temperature correction comprises: Figure 1 Step S1, collecting pipeline design parameters and surrounding environment data, calculating the gas leakage flow rate Q according to the pipeline design parameters and surrounding environment data, and calculating the heat release rate

[0126] according to the gas leakage flow rate Q;

[0127] The embodiment is: January January​ morning An explosion occurred in a high-pressure gas pipeline (carrying hydrogen) in an industrial area south of Brussels, Belgium The pipeline diameter, material, wall thickness, daily delivery pressure, and pipeline pressure at the time of the accident were 1 , 1 , 1 , 1 , and 1 , respectively. The range of light injuries after the explosion was 1 .

[0128] According to the heat flux criterion for personnel injury and equipment damage under thermal radiation, the thermal radiation threshold for light injury in the accident was determined to be 2 .

[0129] Table 1 Heat value injury threshold table

[0130]

[0131] The calculated jet velocity was the speed of sound, the local speed of sound was 340 m / s, the leakage flow rate Q was 1 , and the heat release rate was 1 . kw.

[0132] S2, the specific parameters of different ground materials are shown in Table 2:

[0133] Table 2 Specific parameters of different ground materials

[0134]

[0135] In the accident analysis, since the accident occurred in an industrial area, the ground material is mostly hard material (concrete or asphalt). These materials usually have medium to high thermal conductivity and absorption coefficients, and low reflectivity. Based on this, the material parameters of concrete and asphalt are comprehensively selected, the reflectivity is 0.175, the thermal conductivity is 1.125 W / (m·K), the absorption coefficient is 0.825, and the point source topographic correction factor calculation model is:

[0136]

[0137] S3, the topographic correction factor calculation model is introduced into the multi-point source model for iteration until convergence to obtain the corrected total radiation intensity:

[0138] The multi-point source model based on topographic factors is discretized and calculated by data processing software, and the total number of point sources is taken as 260, resulting in is 1 , 0.9335, the fourth iteration converges,

[0139] S4, At 10:00 on the morning of 10 / 10 / 2018, the temperature query in the area south of the capital of Belgium, Brussels, is ,

[0140] S5, according to the final total thermal radiation intensity, the injury range and safety distance are predicted.

[0141] The thermal radiation value threshold is 2 , that is, 2 , the light injury range is calculated to be 952.5 m by substituting into the distance formula, and the error compared with the actual injury range is 4.75%.

[0142] Comparative example:

[0143] The basic model before correction is used to calculate, , and the light injury range is 898.114 m, with an error of 10.19%.

[0144] Comparing the data of the example and the comparative example, the error of the calculation result of the model of the example (after correction) decreases by 5.44%, as shown in Figure 2 .

[0145] In addition, the accident data under various combined conditions including typical slope angles (15°, 30°, 45°), height differences (5 m, 10 m, 20 m), and wind speeds (2 m / s, 5 m / s, 10 m / s) are summarized. Through data comparison and analysis, the error of the improved model (comparative example) under various complex conditions increases with the complexity of the conditions, and compared with the basic model, the improved model (example) of the present application has higher accuracy in predicting radiation intensity, and the improved model is more consistent with the accident data, which can significantly reduce the error of radiation evaluation under complex terrain. The radiation intensity of the basic model, the improved model and the actual accident data is shown in Figure 3 , and the error comparison of the improved model and the actual data is shown in Figure 4 .

[0146] ​​​​​​​​​The model formula constructed by the method of the present application further considers the landform features and temperature and various complex conditions on the basis of preliminarily considering factors such as terrain and wind speed. The model fully reflects the more actual complex situation through a simple formula form, and good coupling is realized between various correction factors, thereby promoting the accuracy of the gas pipeline safety protection distance setting.

[0147] Based on the above ideal embodiments of the present application, the related personnel can make various changes and modifications without deviating from the technical idea of the present application according to the above description. The technical scope of the present application is not limited to the content of the specification, and the technical scope must be determined according to the scope of claims.​

Claims

1. A method for predicting heat radiation of gas pipeline leakage based on terrain and temperature correction, characterized in that, comprising: Obtaining pipeline design parameters and surrounding environment information, calculating a gas leakage flow rate Q according to the pipeline design parameters and the surrounding environment information, and calculating a heat release rate according to the gas leakage flow rate Q ; constructing a topographic correction factor calculation model according to the absorption, thermal conductivity and reflection characteristics of the surrounding surface material of the pipeline; introducing the topographic correction factor calculation model into the basic multi-point source model for iteration until convergence, obtaining the total radiation intensity obtained by convergence; correcting the total radiation intensity obtained by convergence based on the difference between the actual temperature and the standard ambient temperature, obtaining the final total radiation intensity; constructing a topographic correction factor calculation model according to the absorption, thermal conductivity and reflection characteristics of the surrounding surface material of the pipeline; Specifically: According to the region where the pipeline is located, determine the surrounding surface material whose proportion exceeds the threshold value through geographic information system or field survey; Determine a comprehensive characteristic parameter of the ground material whose proportion exceeds the threshold value; wherein the comprehensive characteristic parameter comprises an absorption coefficient , a thermal conductivity coefficient , and a reflection coefficient ; Combined with the obtained comprehensive characteristic parameters and the view factor in the basic multi-point source model, the topographic correction factor calculation model is constructed; The calculation model of the topographic correction factor of the single point source is: wherein is the terrain correction factor for the th point source, is the absorption coefficient of the material; is the view factor; is the thermal conductivity of the surface material; denotes the thermal radiation intensity of the th point source; is the reflection coefficient of the material; introducing the topographic correction factor calculation model into the basic multi-point source model for iteration, and the iteration formula is: · wherein is the result of the i-th calculation of the topographic correction factor for the j-th point source, is the result of the i-th calculation of the topographic correction factor for the j-th point source, , is the result of the i-th calculation of the topographic correction factor for the j-th point source, is the result of the i-th calculation of the topographic correction factor for the j-th point source, correcting the total radiation intensity obtained by convergence based on the difference between the actual temperature and the standard ambient temperature; The specific formula is: wherein, to improve the total intensity of radiation, to converge the total intensity of radiation, is the standard ambient temperature; is the difference between the actual ambient temperature and the standard ambient temperature .

2. The method for predicting heat radiation of gas pipeline leakage based on terrain and temperature correction according to claim 1, characterized in that, the basic multi-point source model is: ； wherein, is the total thermal radiation intensity of the base multi-point source model; is the initial radiation intensity of the jth point source, is the weight of the jth point source, N is the total number of point sources; is the atmospheric transmissivity; is the radiation fraction; is the heat release rate; is the distance from the jth point source to the target point, is the cosine value of the angle between each two-point line and the outer normal of the target, i.e., the view factor; N is the number of point sources; n is the total number of point sources of the multi-point source, and the initial radiation intensity of the jth point source is calculated by the formula .​ 3. A method for predicting the damage range of gas pipeline leakage based on terrain and temperature correction, characterized in that, using the method for predicting heat radiation of gas pipeline leakage based on terrain and temperature correction according to any one of claims 1 or 2 to predict the final total radiation intensity received by each target point; based on the final total radiation intensity, predict the damage range and safety distance.

4. The method for predicting the damage range of gas pipeline leakage based on terrain and temperature correction according to claim 3, characterized in that, based on the final total radiation intensity, predict the damage range and safety distance; Specifically: total radiation amount per unit time of the improved radiation source; area of the radiation source; final total radiation intensity; distance from the center point of the radiation source to the target point, i.e., safety distance radius; atmospheric transmissivity, threshold value of thermal radiation value.

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