A method and device for predicting the range of natural gas leakage fireball

Abstract

The present invention discloses a method and device for predicting the range of a natural gas leak fireball. The method corrects the existing observation factor and transmission coefficient, establishes an observation factor function and an atmospheric transmission coefficient function about the observation elevation angle of the irradiated target, and establishes an improved fireball prediction model on this basis; then, the fireball range corresponding to the preset damage degree is solved at the optimal irradiated target observation elevation angle. The present invention reduces the error caused by ignoring the observation factor and transmission coefficient when performing hazard analysis in the classical prediction model, improves the accuracy of hazard radius calculation, and enhances the rationality of safety assessment.

Description

Technical Field

[0001] The invention relates to a method and a device for predicting the action range of a natural gas leakage fireball, belonging to the technical field of natural gas storage and transportation safety prevention and control. Background Art

[0002] With the continuous development of modern society and science and technology, the demand for energy is also gradually increasing. As one of the main energy sources, natural gas has become the main fuel for industrial development and people's daily life. Accidents caused by natural gas leaks are difficult to detect and control, and often cause large casualties and property losses. Natural gas leaks generally occur in four situations: safe discharge, jet flame, fireball fire, and steam cloud explosion. The probability of a fireball accident is low, but the destructive power is extremely strong.

[0003] At present, many experts and scholars have begun to study the hazards of fireballs caused by natural gas leaks. There are few studies on the injury range model of fireball accidents, and the exploration of fireball damage assessment is very limited. The current fireball model damage model is limited to the assessment of the fireball in a static state, and the rising height of the fireball is substituted as a fixed value. In fact, it is difficult for a fireball to remain stationary at a certain height, which causes the fireball damage range to change dynamically. Simulations have found that the existing model predicts a significantly smaller fireball death range, and cannot provide an accurate reference for safety prevention and control work in complex situations. Summary of the invention

[0004] In view of the deficiencies of the prior art, the object of the present invention is to provide a method and device for predicting the range of a natural gas leak fireball, so as to solve the problem in the prior art that the predicted range of a fireball is smaller than the actual range.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] The present invention provides a method for predicting the range of a natural gas leak fireball, comprising:

[0007] Determine the nature of the natural gas leak and calculate the natural gas leak mass flow rate corresponding to the leak nature;

[0008] According to the mass flow rate of natural gas leakage, the amount of natural gas used for fireball combustion, the maximum radius of the fireball and the burning time of the fireball are calculated;

[0009] The heat radiation flux on the surface of the fireball is calculated based on the amount of natural gas used in the fireball combustion, the maximum radius of the fireball, and the burning time of the fireball;

[0010] Establishing an observation factor function and an atmospheric transmission coefficient function regarding an observation elevation angle θ of an irradiated target, and establishing an improved fireball prediction model based on the established observation factor function and atmospheric transmission coefficient function, and the fireball surface thermal radiation flux;

[0011] The improved fireball prediction model is solved at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree.

[0012] Further, the determining of the nature of the natural gas leakage includes:

[0013] If the following equation is satisfied, the leaked natural gas flows at the speed of sound:

[0014]

[0015] If the following equation is satisfied, the leaked natural gas flows at subsonic speed:

[0016]

[0017] Among them, P 0 is the atmospheric pressure, P is the natural gas pressure, and k is the gas adiabatic index;

[0018] The calculation of the natural gas leakage mass flow rate of the corresponding leakage property includes:

[0019] If the leaked natural gas flows at the speed of sound, the mass flow rate is calculated as follows:

[0020]

[0021] If the leaking natural gas flows at subsonic speed, the mass flow rate is calculated as follows:

[0022]

[0023] Where Q is the mass flow rate, C d is the gas leakage coefficient, M is the gas molar mass, T is the natural gas temperature, A is the crack area, and R is the gas constant.

[0024] Furthermore, the amount of natural gas used for fireball combustion is calculated based on the mass flow rate of natural gas leakage as follows:

[0025] M f =βM;

[0026] M = 30·Q;

[0027] Where M is the mass of natural gas leaked when the leakage time is 30s, β is the mass coefficient of natural gas participating in the fireball combustion, and M f The amount of natural gas used to burn the fireball;

[0028] The maximum radius of the fireball is calculated as follows:

[0029]

[0030] The fireball burning time is calculated as follows:

[0031]

[0032] Among them, R f is the maximum radius of the fireball, t is the burning time of the fireball, and a, b, c, and d are the combustion coefficients respectively.

[0033] Furthermore, the calculation of the heat radiation flux on the surface of the fireball according to the amount of natural gas used for the fireball combustion, the maximum radius of the fireball, and the burning time of the fireball includes:

[0034]

[0035] Among them, SEP 2 is the heat radiation flux on the fireball surface, η is the heat radiation factor on the fireball surface, H c The heat of combustion of the fuel.

[0036] Furthermore, the observation factor function and the atmospheric transmission coefficient function for the observation elevation angle θ of the irradiated target are established as follows:

[0037]

[0038]

[0039]

[0040] Among them, F v is the observation factor function, τ a is the atmospheric transmission coefficient function, r is the horizontal distance from the irradiated target to the center of the fireball, P w is the ambient temperature T 0 The lower horizontal partial pressure, RH is the relative humidity, T 0 is the ambient temperature;

[0041] The observation elevation angle θ of the irradiated target is the angle between the horizontal line and the line connecting the irradiated target to the center of the fireball, which is an acute angle.

[0042] Furthermore, the improved fireball prediction model is established as follows:

[0043] I 2 (r) = τ a ·SEP 2 ·F v ;

[0044] Among them, I 2 (r) is the heat flux corresponding to the preset damage level.

[0045] Furthermore, the improved fireball prediction model is solved at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree, including:

[0046] Obtain the heat flux value corresponding to the preset damage level, and calculate the r value corresponding to the heat flux value when the optimal irradiated target observation elevation angle θ is the fireball action range corresponding to the preset damage level;

[0047] The optimal irradiated target observation elevation angle θ is: θ=arctan(R f / r).

[0048] Furthermore, the heat flux values ​​corresponding to the preset damage levels include:

[0049] When the preset damage level is safe, the corresponding heat flux value is 1.6kw / m 2 ;

[0050] When the preset injury level is severe, the corresponding heat flux value is 6.4kw / m 2 ;

[0051] When the preset injury level is lethal, the corresponding heat flux value is 25.0kw / m 2 .

[0052] Another aspect of the present invention provides a natural gas leak fireball range prediction device, comprising:

[0053] A first calculation module, used to determine the leakage property of natural gas and calculate the leakage mass flow rate of natural gas corresponding to the leakage property;

[0054] The second calculation module is used to calculate the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball according to the mass flow rate of the natural gas leakage;

[0055] The third calculation module is used to calculate the heat radiation flux on the surface of the fireball according to the amount of natural gas used for the fireball combustion, the maximum radius of the fireball and the burning time of the fireball;

[0056] A model building module is used to establish an observation factor function and an atmospheric transmission coefficient function regarding an observation elevation angle θ of an irradiated target, and to establish an improved fireball prediction model based on the established observation factor function and atmospheric transmission coefficient function, and the fireball surface thermal radiation flux;

[0057] as well as,

[0058] The prediction output module is used to solve the improved fireball prediction model at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree.

[0059] Furthermore, the model building module is specifically used to:

[0060] The observation factor function and atmospheric transmission coefficient function about the observation elevation angle θ of the irradiated target are established as follows:

[0061]

[0062]

[0063]

[0064] Among them, F v is the observation factor function, τ a is the atmospheric transmission coefficient function, r is the horizontal distance from the irradiated target to the center of the fireball, R f is the maximum radius of the fireball, P w is the ambient temperature T 0 The lower horizontal partial pressure, RH is the relative humidity, T 0 is the ambient temperature, P 0 is the atmospheric pressure;

[0065] The observation elevation angle θ of the irradiated target is the angle between the horizontal line and the line connecting the irradiated target to the center of the fireball, which is an acute angle;

[0066] The improved fireball prediction model is established as follows:

[0067] I 2 (r) = τ a ·SEP 2 ·F v ;

[0068] Among them, I 2 (r) is the heat flux corresponding to the preset damage level, SEP 2 is the heat radiation flux on the fireball surface.

[0069] Furthermore, the prediction output module is specifically used to:

[0070] Obtain the heat flux value corresponding to the preset damage level, and calculate the r value corresponding to the heat flux value when the optimal irradiated target observation elevation angle θ is the fireball action range corresponding to the preset damage level;

[0071] The optimal irradiated target observation elevation angle θ is: θ=arctan(R f / r).

[0072] Compared with the prior art, the present invention has the following beneficial effects:

[0073] The present invention substitutes the corrected observation factor and transmission coefficient into the calculation of the fireball's range, reducing the error caused by the classical prediction model ignoring the observation factor and transmission coefficient when performing hazard analysis, improving the accuracy of hazard radius calculation, and enhancing the rationality of safety assessment. It can provide more accurate decision-making basis for safety area division, evacuation plan formulation, and rescue work implementation. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] Figure 1 This is a flow chart of a method for predicting the range of a natural gas leak fireball provided by an embodiment of the present invention;

[0075] Figure 2 is a schematic diagram of an improved fireball prediction model provided by an embodiment of the present invention;

[0076] Figure 3 is a comparison chart of prediction results using a classic fireball prediction model and an improved fireball prediction model in an embodiment of the present invention;

[0077] Figure 4 It is a comparison chart of the prediction results of the improved fireball prediction model used in the embodiment of the present invention and the simulation values ​​of the actual working conditions. DETAILED DESCRIPTION

[0078] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0079] The present invention provides a method for predicting the range of a natural gas leak fireball, comprising:

[0080] Determine the nature of the natural gas leak and calculate the natural gas leak mass flow rate corresponding to the leak nature;

[0081] According to the mass flow rate of natural gas leakage, the amount of natural gas used for fireball combustion, the maximum radius of the fireball and the burning time of the fireball are calculated;

[0082] The heat radiation flux on the surface of the fireball is calculated based on the amount of natural gas used in the fireball combustion, the maximum radius of the fireball, and the burning time of the fireball;

[0083] Establishing an observation factor function and an atmospheric transmission coefficient function regarding an observation elevation angle θ of an irradiated target, and establishing an improved fireball prediction model based on the established observation factor function and atmospheric transmission coefficient function, and the fireball surface thermal radiation flux;

[0084] The improved fireball prediction model is solved at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree.

[0085] An embodiment of the present invention provides a method for predicting the range of a natural gas leak fireball. Figure 1 As shown, the specific implementation process is as follows:

[0086] S1: Collect leakage source parameters and surrounding environment data;

[0087] In this embodiment, the leakage source parameters include natural gas pressure P, natural gas temperature T, leakage port conditions (shape and area A); the surrounding environment data include atmospheric pressure P 0 、Ambient temperature T 0 And humidity RH.

[0088] S2: Determine the nature of the natural gas leak and calculate the mass flow rate;

[0089] In this embodiment, if the following formula (1) is satisfied, the leaked natural gas flows at the speed of sound:

[0090]

[0091] If the following formula (2) is satisfied, the leaked natural gas will flow at a subsonic speed:

[0092]

[0093] If the leaked natural gas flows at the speed of sound, the mass flow rate is calculated as follows:

[0094]

[0095] If the leaking natural gas flows at subsonic speed, the mass flow rate is calculated as follows:

[0096]

[0097] Where, Q is the leakage rate, kg / s; P 0 is atmospheric pressure, Pa; P is natural gas pressure, Pa; k is the gas adiabatic index, which is generally 1.306 for natural gas; C d is the gas leakage coefficient, the circular leakage hole is taken as 1.00; M is the gas molar mass, kg / mol; T is the natural gas temperature, K; A is the crack area, m 2 ; R is the gas constant, J / (mol·K), which is 8.314.

[0098] S3: Calculate the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball according to the mass flow rate;

[0099] The amount of natural gas used for fireball combustion is calculated as follows:

[0100] M f =βM (5)

[0101] M=30·Q

[0102] Wherein, M is the total mass of natural gas (the mass of leaked gas when the leakage time is 30s), kg; β is the mass coefficient of natural gas participating in fireball combustion, β = 90%.

[0103] The maximum radius and burning time of the fireball are:

[0104]

[0105]

[0106] In the formula, R f is the maximum radius of the fireball, m; t is the burning time of the fireball, s; a, b, c, d are the combustion coefficients respectively. The difference between different combustion materials is mainly reflected in the selection of coefficients. The value range of coefficient a is 1.75-3.24, the value range of coefficient b is 0.277-0.333, the value range of coefficient c is 0.23-2.61, and the value range of coefficient d is 0.097-0.333. Combined with the characteristics of natural gas forming fireball, the value of a is determined to be 3.18, the value of b is 0.325, the value of c is 2.57, and the value of d is 0.167.

[0107] S4: Calculate the heat radiation flux SEP on the surface of the fireball based on the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball. 2 as follows:

[0108]

[0109] In the formula, SEP 2 is the heat radiation flux of the fireball surface, kW / m 2 ; η is the thermal radiation factor of the fireball surface, which is taken as 0.4; H c is the heat of combustion of the fuel, which for methane can be taken as 55600 kJ / kg.

[0110] S5: Since the fireball is affected by gravity and buoyancy, the height of the fireball changes at any time, so the variable θ is introduced, which means the observation elevation angle of the irradiated target; two sets of functions about the variable θ, the observation factor and the atmospheric transmission coefficient, are established;

[0111] The classic fireball model defines the fireball's rising height as H. f , which is also the maximum height the fireball can reach, the formula is as follows:

[0112] H f =2.46R f (9)

[0113] Observation factor F v for:

[0114]

[0115] Where r is the horizontal distance from the irradiated target to the center of the fireball, m.

[0116] Atmospheric transmission coefficient τ a for:

[0117]

[0118]

[0119] Where, T 0 is the ambient temperature, K; P w is the ambient temperature T 0 Lower horizontal partial pressure, Pa; P 0 is atmospheric pressure, Pa; RH is relative humidity, which is 1 in dry and sunny weather.

[0120] This embodiment proposes an improvement on the classic prediction model. According to the on-site situation, the fireball is affected by gravity and buoyancy, and the rising height of the fireball changes at any time. Therefore, the variable θ is introduced, such as Figure 2 As shown, it is the observation elevation angle of the irradiated target, which is the angle between the horizontal line and the line connecting the target to the center of the fireball. The acute angle is taken, and the range is:

[0121] The fireball rise height formula is improved to:

[0122] H f = r·tanθ (13)

[0123] Substitute the variable θ into the observation factor F v In , the observation factor function is optimized as follows:

[0124]

[0125] Simplified:

[0126]

[0127] Substituting the variable θ into the transmission coefficient τ a In the formula, the transmission coefficient function is optimized as follows:

[0128]

[0129] Simplified:

[0130]

[0131] S6: By analyzing the influence of variable θ on the damage radius through two sets of functions of observation factor and atmospheric transmission coefficient, the optimal threshold is determined as follows:

[0132] The observation factor function is a monotonically decreasing function of θ; when θ decreases and r remains unchanged, F v Increase; if you want to observe the factor F v remains unchanged, the radiated body needs to be away from the fireball, r increases; when θ=arctan(R f / r), F v The maximum value is also the optimal threshold.

[0133] The atmospheric transmission coefficient is a monotonically decreasing function of θ; when θ decreases and r remains unchanged, τ a Increase; if we want to observe the factor τ a remains unchanged, the radiated body needs to be away from the fireball, r increases; when θ=arctan(R f / r), τ a The maximum value is also the optimal threshold.

[0134] Therefore, when θ=arctan(R f / r), the observation factor F v and the atmospheric transmission coefficient τ a , meeting the optimal threshold requirement. In the classic fireball model, the fireball rise height is fixed at 2.36R f Substituting it in, the calculation result deviates from the actual one, resulting in the predicted fireball range being smaller than the actual range. In addition, as the r value increases, the influence of variable θ gradually decreases, the calculation error of the death radius is the largest, followed by the serious injury radius, and the safety radius is the last.

[0135] S7: Determine the heat flux corresponding to the preset damage level;

[0136] In this embodiment, the heat flux corresponding to the preset injury level is determined with reference to the heat flux injury criterion; wherein the injury level is the degree of impact on people, which is divided into three types: safety, serious injury, and death.

[0137] S8: Calculate the fireball range corresponding to the preset damage level by combining the heat flux, surface thermal radiation flux, the corrected observation factor and the transmission coefficient;

[0138] In this embodiment, the prediction model is defined as follows:

[0139] I 2 (r) = τ a ·SEP 2 ·F v (18)

[0140] In the formula, I 2 (r) is the heat flux corresponding to the preset damage level, W / m 2 .

[0141] When θ=arctan(Rf / r), substitute it into formula (15) to calculate the fireball damage range r corresponding to the preset damage level.

[0142] Another embodiment of the present invention provides a method for predicting the range of a natural gas leak fireball, which is as follows:

[0143] Step 1: Collect leakage source parameters and surrounding environment data.

[0144] In order to facilitate the verification of the experimental results, this embodiment selects the following set working conditions and uses the fire simulation software (FDS) to perform numerical simulation on the leaking pipeline under the same working conditions. The inner diameter of the pipeline is set to 150 mm, the natural gas pressure in the pipeline is 4.0 MPa, the natural gas temperature in the pipeline is 30 ° C, the ambient temperature outside the pipeline is 20 ° C, and the external pressure is standard atmospheric pressure. Since the pipeline leakage mode is generally a small hole leakage, the aperture of the leaking crack is 20 mm.

[0145] Step 2: Calculate the mass flow rate of the leaked natural gas based on the leakage source parameters and surrounding environment data.

[0146] Substituting the working condition data set in step 1 into formulas (1) to (4), it can be found through calculation that in this embodiment, Therefore, the leakage is sonic flow. The mass flow rate Q under this condition is calculated to be 6.69 kg / s using the mass flow rate calculation formula of sonic flow.

[0147] Step three, based on the mass flow rate, calculate the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball.

[0148] Substituting the mass flow rate of 6.69 kg / s calculated in step 2 into formula (5), the natural gas consumption is about 180.63 kg; then substituting the natural gas consumption into formulas (6) to (7), it can be calculated that in this embodiment, the maximum radius of the fireball is about 17.21 m and the burning time is about 6.12 s.

[0149] Step 4: Calculate the surface radiation flux SEP of the fireball based on the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball. 2 .

[0150] Substituting the natural gas consumption 180.63 kg, the maximum radius of the fireball 17.21 m, and the burning time of the fireball 6.12 s calculated in step 3 into formula (8), it can be calculated that in this embodiment, the radiation flux on the surface of the fireball is approximately 176 kW / m 2 .

[0151] In steps five and six, the influence of variable θ on the damage radius is analyzed by observing two sets of functions of the factor and the atmospheric transmission coefficient, and the optimal threshold is determined.

[0152] Classic fireball model, fireball rise height 2.46R f Substitute into formula (10) and formula (11); the improved fireball model, θ = arctan (R f / r) is substituted into formula (15) and formula (17).

[0153] Step seven, referring to the heat flux damage criterion, determine the heat flux corresponding to each damage degree.

[0154] The heat flux criterion is a common criterion that uses the heat flux value as an indicator to measure whether the target is damaged. When the heat flux value received by the target is greater than or equal to the critical value that causes target damage, the target is damaged; therefore, the heat flux corresponding to each degree of damage can be determined according to the heat flux damage criterion. The standard value of fire heat radiation damage of natural gas process equipment facilities determined according to the heat flux damage criterion is detailed in Table 1.

[0155] Table 1: Standard values ​​of fire heat radiation damage in natural gas process equipment

[0156]

[0157] It can be seen from Table 1 that when a person is in a safe state, the corresponding heat flux is 1.6kw / m 2 ; When a person is seriously injured, the corresponding heat flux is 6.4kw / m 2 ; When the injury to a person is fatal, the corresponding heat flux is 25.0kw / m 2 .

[0158] Step eight, calculate the fireball action range corresponding to the preset damage level by combining the heat flux, surface thermal radiation flux, observation factor and transmission coefficient corresponding to the preset damage level.

[0159] In this embodiment, the heat flux when a person is injured and killed is 25.0 kW / m 2 、The heat flux when a person is seriously injured is 6.4kW / m 2 The heat flux is 1.6kW / m when people are in a safe state 2 As the key value, first substitute it into the classic prediction model and calculate the r corresponding to the above three injury levels to be 70m, 139m, and 278m respectively; modify the observation factor and transmission coefficient, and calculate the r corresponding to the above three injury levels to be 78m, 144m, and 281m respectively; that is, in this embodiment, the theoretical death radius is 78m, the serious injury radius is 144m, and the safety radius is 281m. Finally, compare the theoretical calculation values ​​of the classic model with the theoretical calculation values ​​of the improved model. The results are as follows: Figure 3 shown.

[0160] Step nine, perform fireball simulation and collect flame data to verify the calculation results.

[0161] Use FDS software to convert the combustion volume through the natural gas leakage and the fireball volume. Compare the heat flux threshold corresponding to each degree of damage in the heat flux criterion with the temperature, thermal radiation and other data collected by the monitoring device at each point, select the monitoring point closest to the threshold, measure the range of the jet flame under death, serious injury and safety conditions, and compare the theoretical calculation value in step eight with the simulation calculation result in this step. The results are as follows: Figure 4 It can be seen that the hazard range calculated by the improved prediction model is in good agreement with the simulation data, and its rationality has been verified by numerical simulation.

[0162] Another embodiment of the present invention provides a natural gas leak fireball range prediction device, comprising:

[0163] A first calculation module, used to determine the leakage property of natural gas and calculate the leakage mass flow rate of natural gas corresponding to the leakage property;

[0164] The second calculation module is used to calculate the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball according to the mass flow rate of the natural gas leakage;

[0165] The third calculation module is used to calculate the heat radiation flux on the surface of the fireball according to the amount of natural gas used for the fireball combustion, the maximum radius of the fireball and the burning time of the fireball;

[0166] A model building module is used to establish an observation factor function and an atmospheric transmission coefficient function regarding an observation elevation angle θ of an irradiated target, and to establish an improved fireball prediction model based on the established observation factor function and atmospheric transmission coefficient function, and the fireball surface thermal radiation flux;

[0167] as well as,

[0168] The prediction output module is used to solve the improved fireball prediction model at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree.

[0169] In this embodiment, the model building module is specifically used to:

[0170] The observation factor function and atmospheric transmission coefficient function about the observation elevation angle θ of the irradiated target are established as follows:

[0171]

[0172]

[0173]

[0174] Among them, Fv is the observation factor function, τ a is the atmospheric transmission coefficient function, r is the horizontal distance from the irradiated target to the center of the fireball, P w is the ambient temperature T 0 The lower horizontal partial pressure, RH is the relative humidity, T 0 is the ambient temperature;

[0175] The observation elevation angle θ of the irradiated target is the angle between the horizontal line and the line connecting the irradiated target to the center of the fireball, which is an acute angle;

[0176] The improved fireball prediction model is established as follows:

[0177] I 2 (r) = τ a ·SEP 2 ·F v ;

[0178] Among them, I 2 (r) is the heat flux corresponding to the preset damage level.

[0179] In this embodiment, the prediction output module is specifically used to:

[0180] Obtain the heat flux value corresponding to the preset damage level, and calculate the r value corresponding to the heat flux value when the optimal irradiated target observation elevation angle θ is the fireball action range corresponding to the preset damage level;

[0181] The optimal irradiated target observation elevation angle θ is: θ=arctan(R f / r).

[0182] The present invention substitutes the corrected observation factor and transmission coefficient into the calculation of the fireball's range, reducing the error caused by the classical prediction model ignoring the observation factor and transmission coefficient when performing hazard analysis, improving the accuracy of hazard radius calculation, and enhancing the rationality of safety assessment. It can provide more accurate decision-making basis for safety area division, evacuation plan formulation, and rescue work implementation.

[0183] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0184] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0185] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0186] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0187] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for predicting the range of a natural gas leak fireball. It is characterized in that include: Determine the nature of the natural gas leak and calculate the natural gas leak mass flow rate corresponding to the leak nature; According to the mass flow rate of natural gas leakage, the amount of natural gas used for fireball combustion, the maximum radius of the fireball and the burning time of the fireball are calculated; The heat radiation flux on the surface of the fireball is calculated based on the amount of natural gas used in the fireball combustion, the maximum radius of the fireball, and the burning time of the fireball; The observation factor function and atmospheric transmission coefficient function about the observation elevation angle θ of the irradiated target are established as follows: Among them, F v is the observation factor function, τ a is the atmospheric transmission coefficient function, R f is the maximum radius of the fireball, r is the horizontal distance from the irradiated target to the center of the fireball, P w is the ambient temperature T 0 The lower horizontal partial pressure, RH is the relative humidity, T 0 is the ambient temperature, P 0 is the atmospheric pressure; The observation elevation angle θ of the irradiated target is the angle between the horizontal line and the line connecting the irradiated target to the center of the fireball, which is an acute angle; Based on the established observation factor function and atmospheric transmission coefficient function, as well as the fireball surface thermal radiation flux, an improved fireball prediction model is established as follows: I 2 (r)=τ a ·SEP 2 ·F v ; Among them, I 2 (r) is the heat flux corresponding to the preset damage level, SEP 2 is the thermal radiation flux on the fireball surface; The improved fireball prediction model is solved at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree; the optimal irradiated target observation elevation angle θ is: θ=arctan(R f / r).

2. A natural gas leak fireball range prediction method according to claim 1, It is characterized in that Determining the nature of the natural gas leak includes: If the following equation is satisfied, the leaked natural gas flows at the speed of sound: If the following equation is satisfied, the leaked natural gas flows at subsonic speed: Among them, P 0 is the atmospheric pressure, P is the natural gas pressure, and k is the gas adiabatic index; The calculation of the natural gas leakage mass flow rate of the corresponding leakage property includes: If the leaked natural gas flows at the speed of sound, the mass flow rate is calculated as follows: If the leaking natural gas flows at subsonic speed, the mass flow rate is calculated as follows: Where Q is the mass flow rate, C d is the gas leakage coefficient, M is the gas molar mass, T is the natural gas temperature, A is the crack area, and R is the gas constant.

3. A natural gas leak fireball range prediction method according to claim 2, It is characterized in that According to the mass flow rate of natural gas leakage, the amount of natural gas used for fireball combustion is calculated as follows: M f =βM; M = 30·Q; Where M is the mass of natural gas leaked when the leakage time is 30s, β is the mass coefficient of natural gas participating in the fireball combustion, and M f The amount of natural gas used to burn the fireball; The maximum radius of the fireball is calculated as follows: The fireball burning time is calculated as follows: Among them, R f is the maximum radius of the fireball, t is the burning time of the fireball, and a, b, c, and d are the combustion coefficients respectively.

4. A natural gas leak fireball range prediction method according to claim 3, It is characterized in that The heat radiation flux on the surface of the fireball is calculated according to the amount of natural gas used for the fireball combustion, the maximum radius of the fireball, and the burning time of the fireball, including: Among them, SEP 2 is the heat radiation flux on the fireball surface, η is the heat radiation factor on the fireball surface, H c The heat of combustion of the fuel.

5. A method for predicting the range of a natural gas leak fireball according to claim 4, It is characterized in that The improved fireball prediction model is solved at the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree, including: The heat flux value corresponding to the preset damage level is obtained, and the r value corresponding to the heat flux value when the optimal irradiated target observation elevation angle θ is calculated, which is the fireball action range corresponding to the preset damage level.

6. A method for predicting the range of a natural gas leak fireball according to claim 5, It is characterized in that The heat flux values ​​corresponding to the preset damage levels include: When the preset damage level is safe, the corresponding heat flux value is 1.6kw / m 2 ; When the preset injury level is severe, the corresponding heat flux value is 6.4kw / m 2 ; When the preset injury level is lethal, the corresponding heat flux value is 25.0kw / m 2 .

7. A natural gas leak fireball range prediction device, It is characterized in that The device is used to implement the method for predicting the range of a natural gas leakage fireball as described in any one of claims 1 to 6, and comprises: A first calculation module, used to determine the leakage property of natural gas and calculate the leakage mass flow rate of natural gas corresponding to the leakage property; The second calculation module is used to calculate the amount of natural gas used for fireball combustion, the maximum radius of the fireball, and the burning time of the fireball according to the mass flow rate of the natural gas leakage; The third calculation module is used to calculate the heat radiation flux on the surface of the fireball according to the amount of natural gas used for the fireball combustion, the maximum radius of the fireball and the burning time of the fireball; The model building module is used to establish the observation factor function and the atmospheric transmission coefficient function about the observation elevation angle θ of the irradiated target, which is expressed as: Among them, F v is the observation factor function, τ a is the atmospheric transmission coefficient function, r is the horizontal distance from the irradiated target to the center of the fireball, R f is the maximum radius of the fireball, P w is the ambient temperature T 0 The lower horizontal partial pressure, RH is the relative humidity, T 0 is the ambient temperature, P 0 is the atmospheric pressure; The observation elevation angle θ of the irradiated target is the angle between the horizontal line and the line connecting the irradiated target to the center of the fireball, which is an acute angle; And based on the established observation factor function and atmospheric transmission coefficient function, as well as the fireball surface thermal radiation flux, an improved fireball prediction model is established, which is expressed as: I 2 (r)=τ a ·SEP 2 ·F v ; Among them, I 2 (r) is the heat flux corresponding to the preset damage level, SEP 2 is the thermal radiation flux on the fireball surface; as well as, The prediction output module is used to solve the improved fireball prediction model under the optimal irradiated target observation elevation angle θ to obtain the fireball action range corresponding to the preset damage degree; the optimal irradiated target observation elevation angle θ is: θ = arctan (R f / r).

8. A natural gas leak fireball range prediction device according to claim 7, It is characterized in that The prediction output module is specifically used to: The heat flux value corresponding to the preset damage level is obtained, and the r value corresponding to the heat flux value when the optimal irradiated target observation elevation angle θ is calculated, which is the fireball action range corresponding to the preset damage level.

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