Method and system for predicting explosion intensity of steam cloud based on flame velocity

Abstract

The invention discloses a method for predicting the explosion intensity of a steam cloud based on a flame velocity. The method comprises the following steps: constructing a flame propagation prediction formula by integrating factors such as a gas cloud limitation degree, obstacle blockage, steam cloud activity and a flame propagation distance; collecting data in different scenes for fitting analysis, and determining values of undetermined parameters in the flame propagation prediction formula in different scenes; solving a flame propagation prediction formula to obtain a dimensionless flame velocity based on the value of the undetermined parameter in the target scene, and determining an actual flame velocity in combination with the sound velocity; based on the determined actual flame speed, predicting the explosion overpressure through a relational expression between the actual flame speed and the explosion overpressure established in the target scene; based on the predicted explosion overpressure, the explosion impulse is predicted through a relational expression between the explosion overpressure and the explosion impulse established in the target scene; and representing the explosion intensity of the steam cloud based on the predicted explosion overpressure and explosion impulse. The method is simple in process, high in reliability and wide in application range.

Description

Technical Field

[0001] The present application relates to the technical field of chemical production safety, and is related to, but not limited to, a method and system for predicting vapor cloud explosion intensity based on flame speed. Background Art

[0002] With the rapid development of my country's chemical industry, the frequency and severity of chemical disasters are increasing year by year. Fires and explosions are the most common and consequently the most damaging types of accidents in chemical plants. Large amounts of liquid combustible materials in containers and pipelines rapidly vaporize after a leak, forming a vast vapor cloud. Upon encountering an ignition source, a fire or explosion can occur, damaging equipment and causing casualties. Therefore, to analyze the severity of vapor cloud explosions, it is necessary to predict their explosion intensity.

[0003] Existing explosion overpressure prediction methods can be divided into two categories: one is the empirical method represented by the TNT equivalent method, the TNO (The Netherlands Organization) multi-energy method and the Baker-Strehlow method. These methods are simple, efficient and easy for on-site engineers to master, but the prediction results have large errors and are particularly poorly applicable in complex scenarios; the other is the computational fluid dynamics (CFD) method. This method has good accuracy in various scenarios, but is time-consuming and not easy for on-site engineers to master. Summary of the Invention

[0004] In view of this, the embodiments of the present invention provide a method and system for predicting vapor cloud explosion intensity based on flame speed, aiming to solve the problems of existing technical methods being efficient but with large prediction errors or methods being accurate but time-consuming.

[0005] The technical solution of the embodiment of the present application is implemented as follows: In a first aspect, embodiments of the present application provide a method for predicting vapor cloud explosion intensity based on flame speed, the method comprising: The flame propagation prediction formula is constructed by integrating the degree of gas cloud restriction, volume blockage ratio within the gas cloud, flame propagation length, characteristic length of vapor cloud explosion, average diameter of the obstacle, density of explosion gas and air, and laminar combustion velocity of explosion gas. Collecting data from different scenarios for fitting analysis to determine the values ​​of undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud confinement, the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion; Based on the values ​​of the undetermined parameters in the target scenario, the flame propagation prediction formula is solved to obtain a dimensionless flame speed, and the actual flame speed is determined in combination with the speed of sound; Based on the determined actual flame speed, the explosion overpressure is predicted by using the relationship between the actual flame speed and explosion overpressure established in the target scenario; Based on the predicted explosion overpressure, the explosion impulse is predicted by using the relationship between explosion overpressure and explosion impulse established under the target scenario; Characterize the vapor cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

[0006] In a specific embodiment, the flame propagation prediction formula is in the form of: Where C is the degree of confinement of the gas cloud; VBR is the volume blocking ratio within the gas cloud; is the flame propagation length; L is the characteristic length of the vapor cloud explosion; n is the flame propagation length The power of the ratio of the characteristic length L of the vapor cloud explosion; d is the average diameter of the obstacle; ρ gas is the density of the explosion gas; ρ air is the air density; S L is the laminar combustion velocity of the explosion gas; C0 is the speed of sound; is the dimensionless flame speed, which is the ratio of the actual flame speed to the speed of sound.

[0007] In a specific embodiment, the values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios are determined as follows: For the case where the vapor cloud is in an open space but there are continuous obstacles, there are two scenarios: In the first scenario where only the lower boundary of the vapor cloud is restricted by the ground and the other surfaces are open, C is taken as 0.5 and n is taken as 4.2; In the second scenario where one or two sides except the lower boundary surface are greatly restricted by the walls of equipment or facilities, C is taken as 0.58 or 0.67, and n is taken as 4.2.

[0008] In a specific embodiment, the values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios are determined as follows: There are two scenarios for vapor clouds in confined spaces and those extending to open areas near the outside of such spaces: In the third scenario where the aspect ratio of the confined space is 1, n is 2.2. When the degree of confinement is the first level, the C values ​​inside and outside the confined space are 0.8 and 0.7 respectively. When the degree of confinement is the second level, the C values ​​inside and outside the confined space are 0.85 and 0.75 respectively. When the degree of confinement is the third level, the C values ​​inside and outside the confined space are 0.9 and 0.8 respectively. In the fourth scenario, where the aspect ratio of the confined space is greater than a preset threshold, n is set to 1.8. When the confinement level is level 1, the C values ​​inside and outside the confined space are 0.8 and 0.7, respectively. When the confinement level is level 2, the C values ​​inside and outside the confined space are 0.85 and 0.75, respectively. When the confinement level is level 3, the C values ​​inside and outside the confined space are 0.9 and 0.8, respectively. The aspect ratio is the ratio of length to diameter; in the confined space, the longest length in the X, Y, and Z directions is the length, and the square root of the area in the other two directions is the diameter. Level 1 means the vapor cloud is confined in two directions within the confined space, or the flame front can be considered to propagate in two dimensions during the explosion. Level 3 means the vapor cloud is confined in three directions within the confined space. Level 2 is between the first and third levels. The preset threshold is determined based on historical experience and can generally be set to 5.

[0009] In a specific embodiment, the relationship between the actual flame speed and the explosion overpressure established in different scenarios is as follows: For the first scenario, ; For the second scenario, ; in, is the explosion overpressure; is the actual flame speed.

[0010] In a specific embodiment, the relationship between the actual flame speed and the explosion overpressure established in different scenarios is as follows: For the third scenario, When the restriction level is the first level, ; When the restriction level is the second level, ; When the restriction level is the third level, ; For the fourth scenario, When the restriction level is the first level, ; When the restriction level is the second level, ; When the restriction level is the third level, ; in, is the explosion overpressure; is the actual flame speed.

[0011] In a specific embodiment, the relationship between explosion overpressure and explosion impulse established in different scenarios is as follows: For the first scenario, ; For the second scenario, ; in, is the explosion impulse; Explosion overpressure.

[0012] In a specific embodiment, the relationship between explosion overpressure and explosion impulse established in different scenarios is as follows: For the third scenario, When the restriction level is the first level, ; When the restriction level is the second level, When the restriction level is the third level, For the fourth scenario, When the restriction level is the first level, When the restriction level is the second level, When the restriction level is the third level, in, is the explosion impulse; Explosion overpressure.

[0013] In a second aspect, an embodiment of the present application provides a system for predicting vapor cloud explosion intensity based on flame speed, the system comprising: The flame propagation prediction formula construction module is used to construct the flame propagation prediction formula by integrating the degree of gas cloud restriction, the volume blockage ratio within the gas cloud, the flame propagation length, the characteristic length of the vapor cloud explosion, the average diameter of the obstacle, the density of the explosion gas and air, and the laminar combustion velocity of the explosion gas; a module for determining undetermined parameters, configured to collect data from different scenarios for fitting analysis and determine the values ​​of undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud confinement, the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion; an actual flame speed determination module, configured to solve the flame propagation prediction formula based on the values ​​of the undetermined parameters in the target scenario to obtain a dimensionless flame speed, and determine the actual flame speed in combination with the speed of sound; An explosion overpressure prediction module is used to predict the explosion overpressure based on the determined actual flame speed and the relationship between the actual flame speed and explosion overpressure established in the target scenario; An explosion impulse prediction module is used to predict the explosion impulse based on the predicted explosion overpressure and the relationship between the explosion overpressure and the explosion impulse established in the target scenario; The steam cloud explosion intensity characterization module is used to characterize the steam cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

[0014] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least: In the embodiments of the present application, the flame propagation speed is quantified by constructing a formula and the influence of factors such as the degree of restriction, obstacle blockage, vapor cloud activity and flame propagation distance are comprehensively considered; relationship formulas are established for the correlation between flame speed, explosion overpressure and explosion impulse in different scenarios, so as to predict explosion overpressure and explosion impulse, and then characterize the intensity of vapor cloud explosion; this method is simple and efficient, and the results are reliable, with a wide range of applications, friendly to on-site engineering personnel, and convenient for application by safety management personnel in actual production. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive work, among which: Figure 1 A schematic flow chart of a method for predicting vapor cloud explosion intensity based on flame speed provided by an embodiment of the present invention; Figure 2 A structural block diagram of a system for predicting vapor cloud explosion intensity based on flame speed provided by an embodiment of the present invention; Figure 3 This is a schematic diagram corresponding to the first scenario where only the lower boundary of the vapor cloud is restricted by the ground while the other surfaces are open; Figure 4 This is a schematic diagram corresponding to the second scenario in which one side, except for the lower boundary surface, is significantly restricted by the wall of the equipment or facility; Figure 5 This is a schematic diagram corresponding to the second scenario in which the two sides except the lower boundary surface are greatly restricted by the walls of equipment or facilities; Figure 6 This is a schematic diagram of the first level of restriction; Figure 7 This is a schematic diagram of the second level of restriction; Figure 8 This is a schematic diagram of the third level of restriction; Reference numerals: 1 - vapor cloud; 2 - ground; 3 - side wall restriction; 4 - confined space. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. The following examples are used to illustrate the present application, but are not intended to limit the scope of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0017] In the following description, reference is made to “some embodiments”, which describes a subset of all possible embodiments, but it will be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0018] It should be pointed out that the terms "first\second\third" involved in the embodiments of the present application are only used to distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first\second\third" can be interchanged with a specific order or sequence where permitted, so that the embodiments of the present application described here can be implemented in an order other than that illustrated or described here.

[0019] Those skilled in the art will understand that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art in the art to which the embodiments of the present application belong. It should also be understood that terms such as those defined in common dictionaries should be understood to have meanings consistent with their meanings in the context of the prior art, and will not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0020] Example 1 Figure 1 A flow chart of a method for predicting vapor cloud explosion intensity based on flame speed provided in an embodiment of the present application is shown as follows: Figure 1 As shown, the method comprises at least the following steps: Step S1, constructing a flame propagation prediction formula by comprehensively considering the degree of gas cloud restriction, the volume blockage ratio within the gas cloud, the flame propagation length, the characteristic length of the vapor cloud explosion, the average diameter of the obstacle, the density of the explosion gas and air, and the laminar combustion velocity of the explosion gas.

[0021] Specifically, the flame propagation prediction formula is in the form of: Formula (1); Where C is the degree of confinement of the gas cloud; VBR is the volume blocking ratio within the gas cloud; is the flame propagation length; L is the characteristic length of the vapor cloud explosion; n is the flame propagation length The power of the ratio of the characteristic length L of the vapor cloud explosion; d is the average diameter of the obstacle; ρ gas is the density of the explosion gas; ρ air is the air density; S L is the laminar combustion velocity of the explosion gas; C0 is the speed of sound; is the dimensionless flame speed, which is the ratio of the actual flame speed to the speed of sound.

[0022] Here, an empirical formula quantifies flame speed and comprehensively considers the influence of factors such as gas cloud confinement, obstruction, vapor cloud activity, and flame propagation distance. This makes the flame speed-based method for predicting vapor cloud explosion intensity applicable to different environments, thereby expanding the method's applicability. Quantifying flame speed through an empirical formula can improve the reliability of the method's results.

[0023] Step S2, collecting data under different scenarios for fitting analysis, and determining the values ​​of undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud restriction, and the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion.

[0024] Specifically, the values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios are determined as follows: For the case where the vapor cloud is in an open space but there are continuous obstacles, there are two scenarios: In the first scenario, only the lower boundary of the vapor cloud is restricted by the ground, while the other sides are open. Figure 3 As shown, C is 0.5 and n is 4.2.

[0025] In the second scenario, in addition to the lower boundary surface, one or two sides are greatly restricted by the walls of equipment or facilities. Figure 4 and Figure 5 As shown, C takes the value of 0.58 or 0.67, and n takes the value of 4.2.

[0026] There are two scenarios for vapor clouds in confined spaces and those extending to open areas near the outside of such spaces: In the third scenario where the aspect ratio of the confined space is 1, n is 2.2; when the degree of confinement is the first level, Figure 6 As shown, the C values ​​inside and outside the confined space are 0.8 and 0.7 respectively; when the degree of confinement is the second level, as shown in Figure 7 As shown, the C values ​​inside and outside the confined space are 0.85 and 0.75 respectively; when the degree of confinement is the third level, as shown in Figure 8 As shown, the C values ​​inside and outside the confined space are 0.9 and 0.8 respectively.

[0027] In the fourth scenario where the aspect ratio of the confined space is greater than the preset threshold, n is set to 1.8; when the degree of confinement is the first level, Figure 6 As shown, the C values ​​inside and outside the confined space are 0.8 and 0.7 respectively; when the degree of confinement is the second level, as shown in Figure 7 As shown, the C values ​​inside and outside the confined space are 0.85 and 0.75 respectively; when the degree of confinement is the third level, as shown in Figure 8 As shown, the C values ​​inside and outside the confined space are 0.9 and 0.8 respectively; the aspect ratio is the ratio of length to diameter, and the longest length in the confined space in the X, Y, and Z directions is the length, and the square root of the area in the other two directions is the diameter; the first level is that the steam cloud is confined in two directions within the confined space or the flame front can be regarded as two-dimensional propagation in the explosion; the third level is that the steam cloud is confined in three directions within the confined space; the second level is between the first and third levels.

[0028] Here, corresponding values ​​of C and n are determined in combination with different scenarios, so that the results of the scheme in predicting the steam cloud explosion intensity in different scenarios are more accurate and the scope of application of the scheme is wider.

[0029] Step S3: Based on the values ​​of the undetermined parameters in the target scenario, the flame propagation prediction formula is solved to obtain a dimensionless flame speed, and the actual flame speed is determined in combination with the speed of sound.

[0030] Specifically, the actual flame speed It is expressed by the following formula: Formula (2); Where C0 is the speed of sound; is the dimensionless flame speed; is the actual flame speed.

[0031] Step S4 : Based on the determined actual flame speed, the explosion overpressure is predicted by using a relationship between the actual flame speed and the explosion overpressure established in the target scenario.

[0032] Specifically, the relationship between the actual flame speed and explosion overpressure established in different scenarios is as follows: For the first scenario, Formula (3); For the second scenario, Formula (4); For the third scenario, When the restriction level is the first level, Formula (5); When the restriction level is the second level, Formula (6); When the restriction level is the third level, Formula (7); For the fourth scenario, When the restriction level is the first level, Formula (8); When the restriction level is the second level, Formula (9); When the restriction level is the third level, Formula (10); in, is the explosion overpressure; is the actual flame speed.

[0033] Here, for different scenarios, the explosion overpressure is predicted based on the result of step S3, so that the results of the scheme for predicting the explosion overpressure in different scenarios are more accurate and the scope of application of the scheme is wider.

[0034] Step S5: Based on the predicted explosion overpressure, the explosion impulse is predicted by using a relationship between the explosion overpressure and the explosion impulse established in the target scenario.

[0035] Specifically, the relationship between explosion overpressure and explosion impulse established in different scenarios is as follows: For the first scenario, Formula (11); For the second scenario, Formula (12); For the third scenario, When the restriction level is the first level, Formula (13); When the restriction level is the second level, Formula (14); When the restriction level is the third level, Formula (15); For the fourth scenario, When the restriction level is the first level, Formula (16); When the restriction level is the second level, Formula (17); When the restriction level is the third level, Formula (18); in, is the explosion impulse; Explosion overpressure.

[0036] Here, for different scenarios, the explosion impulse is predicted based on the result of step S4, so that the results of the scheme for predicting the explosion impulse in different scenarios are more accurate and the scope of application of the scheme is wider.

[0037] The above method establishes relationship equations for the correlation between flame speed, explosion overpressure and explosion impulse in different scenarios, thereby predicting explosion overpressure and explosion impulse, and then characterizing the intensity of vapor cloud explosion. This method is simple and efficient, and the results are reliable. It has a wide range of applications, is friendly to on-site engineering personnel, and is easy to use for safety management personnel in actual production.

[0038] Step S6: characterizing the steam cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

[0039] In this embodiment, a formula is constructed to quantify the flame propagation speed and comprehensively consider the influence of factors such as the degree of restriction, obstacle blocking, vapor cloud activity, and flame propagation distance; relationship equations are established for the correlation between flame speed, explosion overpressure, and explosion impulse in different scenarios, so as to predict explosion overpressure and explosion impulse, and then characterize the vapor cloud explosion intensity; this method is simple and efficient, and the results are reliable. It has a wide range of applications, is friendly to on-site engineering personnel, and is convenient for application by safety management personnel in actual production.

[0040] Example 2 The vapor cloud size is m, the combustible gas is methane with a concentration of 9.5%, and the obstacle array size is m, placed in the front half of the gas cloud, by The diameter of the pipe is about 168 mm. The ignition position is upstream of the obstacle. The volume blockage ratio VBR in the gas cloud is 0.08. The flame propagation length is The characteristic length of the vapor cloud explosion is 20 m, the characteristic length of the vapor cloud explosion is L3 m, the average diameter of the obstacle is d0.17 m, and the laminar combustion velocity of the explosion gas is S Lis 0.37 m / s, and the speed of sound C0 is 340 m / s.

[0041] According to the above situation, this scenario belongs to the first scenario, so the gas cloud restriction degree C is determined to be 0.5, and the flame propagation length is The power n of the ratio term to the characteristic length L of the vapor cloud explosion is taken as 4.2.

[0042] The actual flame speed is calculated according to the above formulas (1), (2), (3) and (11): 250m / s, predicted explosion overpressure is 35.4 kPa, and the predicted explosion impulse is 1.06 kPa·s.

[0043] An experiment was conducted on this scenario, and the experimental results showed that the explosion overpressure 49.2kPa, explosion impulse The error between the predicted explosion overpressure and the experimental explosion overpressure is within the allowable range, and the error between the predicted explosion impulse and the experimental explosion impulse is also within the allowable range, which proves the reliability of the prediction results of this method.

[0044] Example 3 The two sizes are m cubic container, both of which are composed of The opening of m is connected, and the area of ​​the front wall is 2.48 m 2 Ventilation port, ignition is at the rear wall of the left container, the combustible gas is methane with a concentration of 9.5%, the volume blockage ratio VBR in the gas cloud is 0.05, and the flame propagation length The characteristic length of the vapor cloud explosion is 3.6 m, the characteristic length of the vapor cloud explosion is L, the average diameter of the obstacle is 0.01 m, and the laminar combustion velocity of the explosion gas is S. L is 0.37 m / s, and the speed of sound C0 is 340 m / s.

[0045] According to the above situation, this scene is determined to be the third scene, so the flame propagation length The power n of the ratio term to the characteristic length L of the vapor cloud explosion is taken as 2.2; the degree of restriction of this scenario is the second level, so the value of the gas cloud restriction degree C is determined to be 0.85, but due to the existence of the front surface vents, the value is appropriately lowered, so the gas cloud restriction degree C is taken as 0.8.

[0046] The actual flame speed is calculated according to the above formulas (1), (2), (6) and (14): 125m / s, predicted explosion overpressure is 17.8 kPa, and the predicted explosion impulse is 1.41 kPa·s.

[0047] An experiment was conducted on this scenario, and the experimental results showed that the explosion overpressure 13.5 kPa, explosion impulse The error between the predicted explosion overpressure and the experimental explosion overpressure is within the allowable range, and the error between the predicted explosion impulse and the experimental explosion impulse is also within the allowable range, which proves the reliability of the prediction results of this method.

[0048] Example 4 Based on the foregoing embodiments, an embodiment of the present application further provides a system for predicting vapor cloud explosion intensity based on flame speed. The system includes various modules included therein, which can be implemented by a processor in an electronic device; of course, it can also be implemented by a specific logic circuit; during implementation, the processor can be a central processing unit (CPU), a microprocessor (MPU), a digital signal processor (DSP), or a field programmable gate array (FPGA), etc.

[0049] See Figure 2 , Figure 2 2 is a block diagram of a system for predicting vapor cloud explosion intensity based on flame speed. The system 200 for predicting vapor cloud explosion intensity based on flame speed provided in this embodiment includes: The flame propagation prediction formula construction module 201 is used to construct a flame propagation prediction formula based on the degree of gas cloud restriction, the volume blockage ratio within the gas cloud, the flame propagation length, the characteristic length of the vapor cloud explosion, the average diameter of the obstacle, the density of the explosion gas and air, and the laminar combustion speed of the explosion gas.

[0050] This step quantifies the flame speed using an empirical formula and comprehensively considers the influence of factors such as the degree of gas cloud confinement, obstruction, vapor cloud activity, and flame propagation distance. This makes the flame speed-based method for predicting vapor cloud explosion intensity applicable to different environments, thereby increasing the method's applicability. Quantifying the flame speed using an empirical formula can improve the reliability of the method's results.

[0051] The undetermined parameter determination module 202 is used to collect data under different scenarios for fitting analysis and determine the values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud restriction, and the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion.

[0052] Here, corresponding values ​​of C and n are determined in combination with different scenarios, so that the results of the scheme in predicting the steam cloud explosion intensity in different scenarios are more accurate and the scope of application of the scheme is wider.

[0053] The actual flame speed determination module 203 is configured to solve the flame propagation prediction formula based on the values ​​of the undetermined parameters in the target scenario to obtain a dimensionless flame speed, and determine the actual flame speed in combination with the speed of sound.

[0054] The explosion overpressure prediction module 204 is configured to predict the explosion overpressure based on the determined actual flame speed and by using a relationship between the actual flame speed and the explosion overpressure established in a target scenario.

[0055] Here, for different scenarios, the explosion overpressure is predicted based on the result of the actual flame speed determination module 203, so that the results of the scheme in predicting the explosion overpressure in different scenarios are more accurate and the application range of the scheme is wider.

[0056] The explosion impulse prediction module 205 is used to predict the explosion impulse based on the predicted explosion overpressure and the relationship between the explosion overpressure and the explosion impulse established in the target scenario.

[0057] Here, for different scenarios, the explosion impulse is predicted based on the results of the explosion overpressure prediction module 204, so that the results of the scheme in predicting the explosion impulse in different scenarios are more accurate and the scope of application of the scheme is wider.

[0058] The steam cloud explosion intensity characterization module 206 is configured to characterize the steam cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

[0059] The system quantifies the flame propagation speed by constructing a formula and comprehensively considers the influence of factors such as the degree of restriction, obstacle blockage, vapor cloud activity and flame propagation distance; it establishes relationship equations for the correlation between flame speed, explosion overpressure and explosion impulse in different scenarios, so as to predict explosion overpressure and explosion impulse, and then characterize the intensity of vapor cloud explosion; the system process is simple and efficient, the results are reliable, the scope of application is wide, it is friendly to on-site engineering personnel, and it is convenient for safety management personnel to use in actual production.

[0060] It should be noted that the description of the above system embodiment is similar to the description of the above method embodiment and has similar beneficial effects as the method embodiment. For technical details not disclosed in the system embodiment of this application, please refer to the description of the method embodiment of this application for understanding.

[0061] It should be understood that "one embodiment" or "an embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments.

[0062] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0063] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple units or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0064] The units described above as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units; they may be located in one place or distributed across multiple network units; some or all of the units may be selected according to actual needs to achieve the purpose of the embodiment of the present application.

[0065] In addition, all functional units in the embodiments of the present application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the above-mentioned integrated units can be implemented in the form of hardware or in the form of hardware plus software functional units.

[0066] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling the automatic test line of the device to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0067] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0068] The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0069] The above is merely an embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for predicting vapor cloud explosion intensity based on flame speed, characterized in that: The method comprises: The flame propagation prediction formula is constructed by integrating the degree of gas cloud restriction, volume blockage ratio within the gas cloud, flame propagation length, characteristic length of vapor cloud explosion, average diameter of the obstacle, density of explosion gas and air, and laminar combustion velocity of explosion gas. Collecting data from different scenarios for fitting analysis to determine the values ​​of undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud confinement, the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion; Based on the values ​​of the undetermined parameters in the target scenario, the flame propagation prediction formula is solved to obtain a dimensionless flame speed, and the actual flame speed is determined in combination with the speed of sound; Based on the determined actual flame speed, the explosion overpressure is predicted by using the relationship between the actual flame speed and explosion overpressure established in the target scenario; Based on the predicted explosion overpressure, the explosion impulse is predicted by using the relationship between explosion overpressure and explosion impulse established under the target scenario; Characterize the vapor cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

2. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 1, characterized in that: The specific form of the flame propagation prediction formula is: Where C is the degree of confinement of the gas cloud; VBR is the volume blocking ratio within the gas cloud; is the flame propagation length; L is the characteristic length of the vapor cloud explosion; n is the flame propagation length The power of the ratio of the characteristic length L of the vapor cloud explosion; d is the average diameter of the obstacle; ρ gas is the density of the explosion gas; ρ air is the air density; S L is the laminar combustion velocity of the explosion gas; C0 is the speed of sound; is the dimensionless flame speed, which is the ratio of the actual flame speed to the speed of sound.

3. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 2, characterized in that: The values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios are determined as follows: For the case where the vapor cloud is in an open space but there are continuous obstacles, there are two scenarios: In the first scenario where only the lower boundary of the vapor cloud is restricted by the ground and the other surfaces are open, C is taken as 0.5 and n is taken as 4.2; In the second scenario where one or two sides except the lower boundary surface are greatly restricted by the walls of equipment or facilities, C is taken as 0.58 or 0.67, and n is taken as 4.

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4. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 2, characterized in that: The values ​​of the undetermined parameters in the flame propagation prediction formula under different scenarios are as follows: There are two scenarios for vapor clouds in confined spaces and those extending to open areas near the outside of such spaces: In the third scenario where the aspect ratio of the confined space is 1, n is 2.

2. When the degree of confinement is the first level, the C values ​​inside and outside the confined space are 0.8 and 0.7 respectively. When the degree of confinement is the second level, the C values ​​inside and outside the confined space are 0.85 and 0.75 respectively. When the degree of confinement is the third level, the C values ​​inside and outside the confined space are 0.9 and 0.8 respectively. In the fourth scenario where the aspect ratio of the confined space is greater than a preset threshold, n is 1.

8. When the degree of confinement is level 1, the C values ​​inside and outside the confined space are 0.8 and 0.7, respectively. When the degree of confinement is level 2, the C values ​​inside and outside the confined space are 0.85 and 0.75, respectively. When the degree of confinement is level 3, the C values ​​inside and outside the confined space are 0.9 and 0.8, respectively. The aspect ratio is the ratio of length to diameter. In the X, Y, and Z directions of the confined space, the longest length is the length, and the square root of the area in the other two directions is the diameter. The first level is that the vapor cloud is confined in two directions within the confined space or the flame front can be regarded as two-dimensional propagation in the explosion; the third level is that the vapor cloud is confined in three directions within the confined space; the second level is between the first and third levels.

5. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 3, characterized in that: The relationship between the actual flame speed and explosion overpressure established in different scenarios is as follows: For the first scenario, ; For the second scenario, ; in, is the explosion overpressure; is the actual flame speed.

6. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 4, characterized in that: The relationship between the actual flame speed and explosion overpressure established in different scenarios is as follows: For the third scenario, When the restriction level is the first level, ; When the restriction level is the second level, ; When the restriction level is the third level, ; For the fourth scenario, When the restriction level is the first level, ; When the restriction level is the second level, ; When the restriction level is the third level, ; in, is the explosion overpressure; is the actual flame speed.

7. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 5, characterized in that: The relationship between explosion overpressure and explosion impulse established in different scenarios is as follows: For the first scenario, ; For the second scenario, ; in, is the explosion impulse; Explosion overpressure.

8. The method for predicting vapor cloud explosion intensity based on flame speed according to claim 6, characterized in that: The relationship between explosion overpressure and explosion impulse established in different scenarios is as follows: For the third scenario, When the restriction level is the first level, ; When the restriction level is the second level, ; When the restriction level is the third level, ; For the fourth scenario, When the restriction level is the first level, ; When the restriction level is the second level, When the restriction level is the third level, in, is the explosion impulse; Explosion overpressure.

9. A system for predicting vapor cloud explosion intensity based on flame speed, characterized in that: include: The flame propagation prediction formula construction module is used to construct the flame propagation prediction formula by integrating the degree of gas cloud restriction, the volume blockage ratio within the gas cloud, the flame propagation length, the characteristic length of the vapor cloud explosion, the average diameter of the obstacle, the density of the explosion gas and air, and the laminar combustion velocity of the explosion gas; a module for determining undetermined parameters, configured to collect data from different scenarios for fitting analysis and determine the values ​​of undetermined parameters in the flame propagation prediction formula under different scenarios; wherein the undetermined parameters include: the degree of gas cloud confinement, the power of the ratio of the flame propagation length to the characteristic length of the vapor cloud explosion; an actual flame speed determination module, configured to solve the flame propagation prediction formula based on the values ​​of the undetermined parameters in the target scenario to obtain a dimensionless flame speed, and determine the actual flame speed in combination with the speed of sound; An explosion overpressure prediction module is used to predict the explosion overpressure based on the determined actual flame speed and the relationship between the actual flame speed and explosion overpressure established in the target scenario; An explosion impulse prediction module is used to predict the explosion impulse based on the predicted explosion overpressure and the relationship between the explosion overpressure and the explosion impulse established in the target scenario; The steam cloud explosion intensity characterization module is used to characterize the steam cloud explosion intensity based on the predicted explosion overpressure and explosion impulse.

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