Underexpansion jet fire radiation fraction evaluation processing method and application

Abstract

The invention relates to an under-expansion jet fire radiation fraction evaluation processing method and application. The radiation fraction evaluation processing method comprises the steps that the proportion of all gas components, the absolute pressure of mixed gas and the temperature of the mixed gas are obtained; determining the molar mass, the gas adiabatic index and the air-fuel ratio of the mixed gas; determining the constant-pressure adiabatic combustion temperature of the mixed gas; the gas speed at the leakage opening is determined; determining the gas density at the leakage port; determining the flame Froude number of the under-expansion jet flame; the radiation fraction of the under-expansion jet flame is determined according to the flame Froude number of the under-expansion jet flame, and the radiation fraction of the under-expansion jet flame is determined according to the following calculation formula: xR = 0.28 Frf-0.66, in the formula, xR is the radiation fraction, and Frf is the flame Froude number. The radiation fractions of the mixed gas under-expansion jet fire determined by the method are good in consistency, and the method can be suitable for evaluating under-expansion jet fire flames of gas pipelines and storage equipment doped with hydrogen and methane in different doping proportions.

Description

Technical Field

[0001] The present application relates to the technical field of safety maintenance of gas pipelines and storage equipment, and particularly relates to a method for evaluating and processing the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane, and its application. Background Technique

[0002] Directly transporting hydrogen through pipelines or mixing it into existing natural gas pipelines for transportation is a key direction to solve the bottleneck of the hydrogen energy industry supply chain. During the transportation of existing natural gas, pure hydrogen, and hydrogen-doped natural gas pipelines, breakages may be caused due to manufacturing defects, self-corrosion, or third-party damage, resulting in the leakage of flammable and explosive gases being transported. If the leaked and ejected gas is ignited, it will trigger a jet fire. Accurately calculating the thermal radiation of the jet fire is of great guiding significance for determining the thermal radiation protection safety distance of the pipeline and carrying out quantitative risk analysis of pipeline fires during operation.

[0003] The radiation fraction is an important parameter for calculating the thermal radiation of a flame, representing the ratio of the radiative heat transfer rate of the flame to the surrounding environment to the total heat release of the flame. This parameter is mainly affected by soot in the flame, flame size, and heat release rate, and is difficult to accurately calculate and determine. Currently, the calculation of the radiation fraction is mainly achieved by means of semi-empirical formulas. There are mainly three types of formulas recognized in the industry: First, the radiation fraction calculation formula based on jet velocity, which is proposed only based on experimental and engineering data of natural gas and cannot be applied to other gases; Second, the radiation fraction calculation formula based on flame residence time; Third, the radiation fraction calculation formula based on the Froude number of the flame; The second and third types of formulas are both proposed based on the research results of single gases, and their applicability to mixed gases has not been verified.

[0004] Therefore, for accurately determining the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane, and being able to determine the radiation fraction of under-expanded jet fires of the above gases with any mixing ratio, the accuracy and consistency of the determination results are of great guiding significance for determining the thermal radiation protection safety distance of the pipeline and carrying out quantitative risk analysis of pipeline fires during operation. Summary of the Invention

[0005] Based on this, it is necessary to provide a method for evaluating and processing the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane that can be applicable to any gas mixing ratio, with good accuracy and consistency, and its application.

[0006] In the first aspect, the present application provides a method for evaluating and processing the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane, including the following steps:

[0007] Obtain the proportions of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas; wherein the mixed gas is methane, hydrogen, or methane gas doped with hydrogen;

[0008] Determine the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas according to the proportion of each gas component;

[0009] Determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics;

[0010] Determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature;

[0011] Determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportion of each gas component;

[0012] Determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio, constant-pressure adiabatic combustion temperature, gas density at the leakage port, and gas velocity at the leakage port of the mixed gas;

[0013] Determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, where the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula:

[0014] χ R = 0.28Fr f -0.66

[0015] In the formula, χ R is the radiation fraction, and Fr f is the flame Froude number.

[0016] In one embodiment, after determining the radiation fraction of the under-expanded jet flame, the processing method further includes the following steps:

[0017] Determine the heat radiation value and the heat radiation protection safety distance according to the radiation fraction of the under-expanded jet flame.

[0018] In one embodiment, after determining the radiation fraction of the under-expanded jet flame, the processing method further includes the following steps:

[0019] Conduct a quantitative fire risk analysis according to the radiation fraction of the under-expanded jet flame.

[0020] In one embodiment, in determining the molar mass of the mixed gas according to the proportion of each gas component, the molar mass of the mixed gas is determined using the following calculation formula:

[0021]

[0022] Among them, are the molar masses of the mixed gas, methane, and hydrogen, respectively, with the unit of kg / mol; is the volume fraction of hydrogen in the mixed gas;

[0023] And / or, in determining the gas adiabatic index of the mixed gas according to the proportion of each gas component, the following calculation formula is used to determine the gas adiabatic index of the mixed gas:

[0024]

[0025] where k fuel 、 are the adiabatic indexes of the mixed gas, methane, and hydrogen respectively;

[0026] And / or, in determining the air-fuel ratio of the mixed gas according to the proportion of each gas component, the following calculation formula is used to determine:

[0027]

[0028] where S is the stoichiometric air-fuel ratio of the mixed gas; M air is the molar mass of air, M fuel is the molar mass of the mixed gas, x and y are the values in C x H y C x H y is obtained after equalizing the doping ratios of methane and hydrogen; The values of x and y in C x H y are determined using the following calculation formula:

[0029]

[0030] where is the volume fraction of hydrogen in the mixed gas, is the volume fraction of methane in the mixed gas, and the mixed gas includes at least one of hydrogen and methane.

[0031] In one embodiment, in determining the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics, it includes:

[0032] According to the general formula C x H y of the equalized mixed gas, determine the number of moles of carbon dioxide, water, and nitrogen in the combustion products;

[0033] According to the number of moles of carbon dioxide, water, and nitrogen and the standard enthalpies of formation of carbon dioxide, water, and nitrogen, determine the product enthalpy of the combustion products;

[0034] According to the product enthalpy of the combustion products, determine the constant-pressure adiabatic combustion temperature of the mixed gas.

[0035] In one embodiment, in determining the gas velocity at the leakage port based on the molar mass of the mixed gas and the temperature of the mixed gas, the following calculation formula is used to determine the gas velocity at the leakage port:

[0036]

[0037] where v e is the gas velocity at the leakage port, with the unit of m / s; R is the gas constant, 8.314 J / (mol·K); T0 is the temperature of the mixed gas, with the unit of K;

[0038] and / or, in determining the gas density at the leakage port based on the absolute pressure of the mixed gas, the adiabatic index of the gas of the mixed gas, and the proportion of each gas component, the following calculation formula is used to determine the gas density at the leakage port:

[0039]

[0040] ρ e is the gas density at the leakage port, with the unit of kg / m 3 ; P0 is the absolute pressure of the mixed gas, with the unit of Pa.

[0041] In one embodiment, in determining the flame Froude number of the underexpanded jet flame based on the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port, the following calculation formula is used to determine the flame Froude number of the underexpanded jet flame:

[0042]

[0043] where Fr f is the flame Froude number; T f is the constant-pressure adiabatic combustion temperature of the mixed gas, with the unit of K; T ∞ is the ambient atmospheric temperature, with the unit of K; ρ ∞ is the ambient atmospheric density, with the unit of kg / m 3 ; d e is the diameter of the leakage port, with the unit of m.

[0044] In a second aspect, the present application provides an evaluation and processing device for the radiation fraction of methane, hydrogen, and hydrogen-doped methane underexpanded jet flames, including:

[0045] an acquisition module, configured to acquire the proportion of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas;

[0046] a physical property parameter determination module, configured to determine the molar mass, adiabatic index, and air-fuel ratio of the mixed gas according to the proportion of each gas component; the physical property parameter determination module is further configured to determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics;

[0047] A gas velocity determination module, configured to determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature;

[0048] A gas density determination module, configured to determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportion of each gas component;

[0049] A Froude number determination module, configured to determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port;

[0050] A radiation fraction determination module, configured to determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, wherein the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula:

[0051] χ R = 0.28Fr f -0.66

[0052] In the formula, χ R is the radiation fraction, and Fr f is the flame Froude number.

[0053] In a third aspect, the present application provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method described in any one of the above embodiments are implemented.

[0054] In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in any one of the above embodiments are implemented.

[0055] The above-mentioned method for evaluating the radiation fraction of methane, hydrogen, and hydrogen-doped methane under-expanded jet flames can accurately and reliably determine the radiation fraction of the under-expanded jet flame of the hydrogen-doped methane mixed gas, providing a basis for determining the heat radiation value, the heat radiation protection safety distance, and carrying out the quantitative fire risk analysis during operation. The radiation fraction of the mixed gas under-expanded jet flame determined by the present application has good consistency and can be applied to the evaluation of the under-expanded jet flame of the gas transmission pipeline and storage equipment of hydrogen-doped methane with different doping ratios. Compared with the existing calculation methods, the new formula proposed by the present invention can calculate the radiation fraction of the under-expanded jet flame of the hydrogen-doped methane mixed gas, and the calculation range covers any mixing ratio, realizing the calculation of the radiation fraction of the under-expanded jet flames of methane, hydrogen, and hydrogen-doped methane with any ratio using the same formula, ensuring the accuracy and consistency of the calculation results. Description of the Drawings

[0056] Figure 1 Schematic flow chart of a method for evaluating the radiation fraction of underexpanded jet fires of methane, hydrogen, and hydrogen-doped methane in one embodiment;

[0057] Figure 2 Graph comparing the radiation fraction obtained by the method for evaluating the radiation fraction of underexpanded jet fires of methane, hydrogen, and hydrogen-doped methane in one embodiment with the experimentally measured data;

[0058] Figure 3 Schematic module structure diagram of a device for evaluating the radiation fraction of underexpanded jet fires of methane, hydrogen, and hydrogen-doped methane in one embodiment;

[0059] Figure 4 Schematic structure diagram of a computer device in one embodiment. Detailed implementation manners

[0060] To facilitate the understanding of this application, in order to make the above-mentioned objects, features, and advantages of this application more obvious and understandable, the following will describe the detailed implementation manners of this application in conjunction with the accompanying drawings. Many specific details are set forth in the following description to fully understand this application, and the preferred embodiments of this application are given in the accompanying drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosure content of this application more thorough and comprehensive. This application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of this application. Therefore, this application is not limited by the specific embodiments disclosed below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used herein are only for the purpose of describing specific implementation manners and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0061] In a first aspect, please refer to Figure 1 , this application provides a method for evaluating the radiation fraction of underexpanded jet fires of methane, hydrogen, and hydrogen-doped methane, including the following steps:

[0062] S110: Obtain the proportions of the gas components in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas; wherein the mixed gas is methane, hydrogen, or methane gas doped with hydrogen;

[0063] In this application, the mixed gas is the mixed gas in a gas transmission pipeline, a storage tank of a transport vehicle, or other gas storage containers. For example, the gas transmission pipeline is a natural gas pipeline after hydrogen doping. Of course, the pipeline to which the methane, hydrogen, and hydrogen-doped methane under-expanded jet fire flame evaluation and treatment method of this application applies is also suitable for pipelines of hydrogen, methane, and mixed gas of methane and hydrogen, or storage tanks of transport vehicles, or other gas storage containers.

[0064] The jet fire mentioned in this application refers to the flame formed when a gas is injected horizontally into the atmospheric environment. The jet fire of this application is the under-expanded jet fire of a gas transmission pipeline. The under-expansion mentioned in this invention refers to the condition where the static pressure of the jet itself is higher than the ambient back pressure when the gas flows out of the outlet. The under-expanded jet fire of this application is the case when the ratio of the atmospheric pressure to the absolute pressure of the mixed gas is lower than the critical pressure ratio, where the critical pressure ratio CPR satisfies the following formula:

[0065]

[0066] If P ∞ P0 < CPR, then it is in an under-expanded jet, where P0 is the absolute pressure of the mixed gas (the absolute pressure inside the pipeline or container), and P ∞ is the atmospheric pressure. k fuel is the adiabatic index of the mixed gas.

[0067] In this step S110, the proportion of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas can be obtained according to the gas transmission pipeline or other gas storage containers for use in determining the jet fire radiation fraction subsequently. Among them, the proportion of each gas component refers to the composition and volume ratio of each gas component in the gas transmission pipeline or other gas storage containers. The absolute pressure of the mixed gas refers to the absolute pressure in the gas transmission pipeline or other gas storage containers. The temperature of the mixed gas refers to the temperature of the gas in the gas transmission pipeline or other gas storage containers.

[0068] In one embodiment, the mixed gas includes methane and hydrogen; for example, the proportion of each gas component includes the volume fraction of hydrogen. Thus, the volume fraction of methane can be obtained through the volume fraction of hydrogen. For example, the mixed gas is hydrogen-doped natural gas, for example, the mixed gas is hydrogen-doped methane.

[0069] S120: Determine the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas according to the proportion of each gas component;

[0070] Based on the determined proportion of each gas component in this application, the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas are determined.

[0071] In one of the embodiments, in determining the molar mass of the mixed gas according to the proportion of each gas component, the following calculation formula is used to determine the molar mass of the mixed gas:

[0072]

[0073] Wherein, are the molar masses of the mixed gas, methane, and hydrogen, respectively, with the unit of kg / mol; is the volume fraction of hydrogen in the mixed gas; thus, it is convenient to determine the molar mass of the mixed gas.

[0074] In one of the embodiments, in determining the gas adiabatic index of the mixed gas according to the proportion of each gas component, the following calculation formula is used to determine the gas adiabatic index of the mixed gas:

[0075]

[0076] Wherein, k fuel 、 are the adiabatic indices of the mixed gas, methane, and hydrogen, respectively; thus, the gas adiabatic index of the mixed gas in the gas transmission pipeline or other gas storage containers can be determined more accurately.

[0077] And / or, in determining the air-fuel ratio of the mixed gas according to the proportion of each gas component, the following calculation formula is used to determine:

[0078]

[0079] Wherein, S is the stoichiometric air-fuel ratio of the mixed gas; M air is the molar mass of air, M fuel is the molar mass of the mixed gas, x and y are the values in C x H y ; C x H y is obtained after equalizing the doping ratios of methane and hydrogen; the determination of x and y in C x H y is determined by the following calculation formula:

[0080]

[0081] Wherein is the volume fraction of hydrogen in the mixed gas, is the volume fraction of methane in the mixed gas, and the mixed gas includes at least one of hydrogen and methane. Thus, the air-fuel ratio of the mixed gas can be determined preferably.

[0082] Of course, it should be noted that C x H yThe general formula of the mixed gas obtained after equalizing the doping ratios of methane and hydrogen can be prepared by conversion based on the volume fractions of hydrogen and methane. For example, if the volume fraction of hydrogen is then the volume fraction of methane is The molar ratio of hydrogen to methane is Then, according to the molecular formulas of hydrogen (H2) and methane (CH4), combined with the molar ratio, the equivalent general formula of the mixed gas C x H y The values of x and y in can be determined.

[0083] In this embodiment, x and y can be determined based on the following formula:

[0084]

[0085] where N is the subscript x number of the C element or the subscript y number of the H element. In the formula: n i is the number of C atoms or H atoms of the i-th component; Y i is the volume fraction of the i-th component.

[0086] In this application, during the determination of the air-fuel ratio, it is determined based on the reaction equation of the following general formula of the mixed gas:

[0087] C x H y +(x + y / 4)(O2 + 3.76N2) → xCO2 + (y / 2)H2O + 3.76(x + y / 4)N2

[0088] Through the above reaction process, the calculation formula for the air-fuel ratio is determined as:

[0089]

[0090] In this way, the air-fuel ratio can be determined more accurately according to the above calculation formula.

[0091] S130: Determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportions of each gas component and in combination with the first law of thermodynamics;

[0092] It should be noted that the adiabatic combustion temperature is a relatively well-recognized definition. For a single gas, it can be obtained by methods such as looking up tables, but for a mixed gas, it can be determined by software calculation.

[0093] In one of the embodiments, in the determination of the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportions of each gas component and in combination with the first law of thermodynamics, it is determined based on heat balance calculations using the CHEMKIN software according to the proportions of each gas component in the mixed gas and the combustion process.

[0094] In one embodiment, in the step of determining the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics, it includes:

[0095] According to the general formula C x H y of the equivalent mixed gas, determine the number of moles of carbon dioxide, water, and nitrogen in the combustion products;

[0096] According to the number of moles of carbon dioxide, water, and nitrogen, and the standard enthalpy of formation of carbon dioxide, water, and nitrogen, determine the enthalpy of the combustion products;

[0097] According to the enthalpy of the combustion products, determine the constant-pressure adiabatic combustion temperature of the mixed gas.

[0098] It should be further noted that the combustion flame temperature is an important parameter in the combustion process. For a given reaction mixture and initial temperature, if the composition of the combustion products is known, the temperature of the products can be calculated according to the first law of thermodynamics. When the air-fuel ratio and fuel temperature are constant, the temperature that can be reached by adiabatic combustion is called the adiabatic combustion (flame) temperature (T f ). For the two cases of constant-volume combustion and constant-pressure combustion, their adiabatic combustion temperatures are called the constant-pressure adiabatic combustion temperature and the constant-volume adiabatic combustion temperature respectively. In this application, since the combustion is carried out in the atmospheric environment, the adiabatic combustion temperature determined in this application is the constant-pressure adiabatic combustion temperature.

[0099] For the constant-pressure combustion process, the first law of thermodynamics can be expressed as:

[0100] The absolute enthalpy of the combustion products = the absolute enthalpy of the reactants in the initial state

[0101] That is: H prod (T2) = H reac (T1)

[0102] In the formula, T1 and T2 are the temperatures of the reactants (reac) and products (prod) respectively. H represents enthalpy.

[0103] Among them,

[0104] h i (T) is the sum of the sensible enthalpy and the chemical enthalpy. When the composition and temperature of the reactants are constant, H reac and H prod can be calculated, and then according to the composition of the combustion products, the temperature T2 of the combustion products can be obtained. Generally, the composition of the products refers to the composition at chemical equilibrium, which is related to the product temperature. Therefore, solving the energy equation is an iterative process. Specifically, according to the determined enthalpy of the products, the following formula can be used to determine

[0105]

[0106] Among them, is the standard enthalpy of formation; is the specific heat capacity, both of which can be obtained by querying the physical property parameter table, and T f is the adiabatic combustion temperature.

[0107] In this application, the reaction equation combined with the general formula of the mixed gas:

[0108] C x H y +(x + y / 4)(O2 + 3.76N2) → xCO2 + (y / 2)H2O + 3.76(x + y / 4)N2

[0109] From the above, it can be determined that the number of moles of carbon dioxide, water, and nitrogen in the products is N i . Then, look up the enthalpies of carbon dioxide, water, and nitrogen, and through

[0110]

[0111] the product enthalpies of carbon dioxide, water, and nitrogen can be determined. In the above formula corresponds to the standard enthalpies of formation (298K) of carbon dioxide, water, and nitrogen. Then, according to the determined standard production enthalpies of the products, substitute them into the following formula:

[0112]

[0113] the constant-pressure adiabatic combustion temperature can be determined.

[0114] S140: Determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature;

[0115] In this application, the gas velocity at the leakage port is determined by the molar mass of the mixed gas and the mixed gas temperature. The gas velocity at the leakage port of a pipeline or other gas storage container is the velocity of the leaked gas.

[0116] In one of the embodiments, in the determination of the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature, the following calculation formula is used to determine the gas velocity at the leakage port:

[0117]

[0118] Among them, v e is the gas velocity at the leakage port, with the unit of m / s; R is the gas constant, 8.314 J / (mol·K); T0 is the mixed gas temperature, with the unit of K; in this way, the gas velocity at the leakage port can be determined better.

[0119] S150: Determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the adiabatic index of the mixed gas, and the proportion of each gas component;

[0120] In one embodiment, in the step of determining the gas density at the leakage port according to the absolute pressure of the mixed gas, the adiabatic index of the mixed gas, and the proportion of each gas component, the following calculation formula is used to determine the gas density at the leakage port:

[0121]

[0122] ρ e is the gas density at the leakage port, with the unit of kg / m 3 ; P0 is the absolute pressure of the mixed gas, with the unit of Pa.. In this way, the gas density at the leakage port can be better determined.

[0123] S160: Determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port;

[0124] In one of the embodiments, in the step of determining the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port, the following calculation formula is used to determine the flame Froude number of the under-expanded jet flame:

[0125]

[0126] where, Fr f is the flame Froude number; T f is the constant-pressure adiabatic combustion temperature of the mixed gas, with the unit of K; T ∞ is the ambient atmospheric temperature, with the unit of K; ρ ∞ is the ambient atmospheric density, with the unit of kg / m 3 ; d e is the diameter of the leakage port, with the unit of m. In this way, the flame Froude number of the under-expanded jet flame can be better determined.

[0127] S170 Determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, where the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula:

[0128] χ R = 0.28Fr f -0.66

[0129] In the formula, χ R is the radiation fraction, and Fr f is the flame Froude number.

[0130] The above-mentioned method for evaluating and processing the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane can accurately and reliably determine the radiation fraction of under-expanded jet fires of the hydrogen-doped methane mixture gas, providing a basis for determining the heat radiation value and the heat radiation protection safety distance. The consistency of the radiation fraction of the mixture gas under-expanded jet fire determined in this application is good, and it can be applied to the evaluation of under-expanded jet fire flames of gas transmission pipelines and storage equipment of hydrogen-doped methane with different doping ratios. Compared with the existing calculation methods, the new formula proposed in this invention can calculate the radiation fraction of under-expanded jet fires of the hydrogen-doped methane mixture gas, and the calculation range covers any mixing ratio, realizing the calculation of the radiation fraction of under-expanded jet fires of methane, hydrogen, and hydrogen-doped methane with any ratio using the same formula, ensuring the accuracy and consistency of the calculation results.

[0131] In one embodiment, after determining the radiation fraction of the under-expanded jet fire, the processing method further includes the following steps:

[0132] Determine the heat radiation value and the heat radiation protection safety distance according to the radiation fraction of the under-expanded jet fire.

[0133] It should be noted that for the specific process of how to determine the heat radiation value and the heat radiation protection safety distance through the radiation fraction, please refer to the existing technology, and this application will not elaborate. By ensuring the consistency of the radiation fraction, this application ensures the consistency and reliability of the heat radiation value.

[0134] In one embodiment, after determining the radiation fraction of the under-expanded jet fire, the processing method further includes the following steps:

[0135] Conduct a quantitative fire risk analysis according to the radiation fraction of the under-expanded jet fire.

[0136] In one embodiment, the applicant verified the accuracy of the heat radiation fraction calculation formula through independent experimental data and literature experimental data. Please refer to Figure 2, which is the thermal radiation fraction determined based on the methane, hydrogen, and hydrogen-doped methane underexpanded jet fire radiation fraction evaluation and processing method of the present application. The black solid line in the figure is the curve of the thermal radiation fraction calculation formula calculated by using the underexpanded jet fire radiation fraction evaluation and processing method of the present application. The red scatter points are the self-experimental data, the green scatter points are the experimental data in the literature Lowesmith B J, Hankinson G. Large scale high pressure jet fires involving natural gas and natural gas / hydrogen mixtures. Process Safety and Environmental Protection, 2012, 90(2): 108-120., and the blue scatter points are the experimental data in the literature Studer E, Jamois D, Jallais S, et al. Properties of large-scale methane / hydrogen jet fires. International journal of hydrogen energy, 2009, 34(23): 9611-9619.. It can be seen from the figure that the experimental data are all distributed around the calculation formula curve, indicating that the calculation accuracy of this formula is relatively good. This confirms that the fire radiation fraction determined by the methane, hydrogen, and hydrogen-doped methane underexpanded jet fire radiation fraction evaluation and processing method of the present application has relatively good accuracy and consistency, and can realize the quantitative calculation of the underexpanded jet fire radiation fraction of methane, hydrogen, and methane-hydrogen mixed gas with any mixing ratio. Compared with the existing calculation methods, the new formula proposed by the present invention can calculate the underexpanded jet fire radiation fraction of this kind of mixed gas of hydrogen-doped methane, and the calculation range covers any mixing ratio, realizing the calculation of the underexpanded jet fire radiation fraction of methane, hydrogen, and methane-hydrogen with any ratio using the same formula, ensuring the accuracy and consistency of the calculation results.

[0137] The new formula proposed by the present invention can calculate the underexpanded jet fire radiation fraction of this kind of mixed gas of hydrogen-doped methane, and the calculation range covers any mixing ratio, realizing the calculation of the underexpanded jet fire radiation fraction of methane, hydrogen, and methane-hydrogen with any ratio using the same formula, ensuring the accuracy of the calculation results.

[0138] In a second aspect, please refer to Figure 3 , the present application provides a methane, hydrogen, and hydrogen-doped methane underexpanded jet fire radiation fraction evaluation and processing device, including:

[0139] An acquisition module, configured to acquire the proportion of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas;

[0140] The physical property parameter determination module is used to determine the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas according to the proportions of the gas components; the physical property parameter determination module is further used to determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportions of the gas components and in combination with the first law of thermodynamics;

[0141] The gas velocity determination module is used to determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature;

[0142] The gas density determination module is used to determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportions of the gas components;

[0143] The Froude number determination module is used to determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port;

[0144] The radiation fraction determination module is used to determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, wherein the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula:

[0145] χ R =0.28Fr f -0.66

[0146] In the formula, χ R is the radiation fraction, and Fr f is the flame Froude number.

[0147] In one embodiment, the device further includes a thermal radiation value and safety distance determination module, which is used to determine the thermal radiation value and the thermal radiation protection safety distance according to the jet fire radiation fraction of the under-expanded jet flame;

[0148] In one embodiment, the device further includes a risk analysis module, which is used to perform quantitative risk analysis of fire during operation according to the jet fire radiation fraction of the under-expanded jet flame.

[0149] In one embodiment, in the physical property parameter determination module, the molar mass of the mixed gas is determined according to the following calculation formula:

[0150]

[0151] Wherein, are the molar masses of the mixed gas, methane, and hydrogen, respectively, with the unit of kg / mol; is the volume fraction of hydrogen in the mixed gas.

[0152] In one embodiment, in the physical property parameter determination module, the following calculation formula is used to determine the adiabatic index of the mixed gas:

[0153]

[0154] where k fuel , are the adiabatic indices of the mixed gas, methane, and hydrogen respectively.

[0155] In one embodiment, in the physical property parameter determination module, the following calculation formula is used to determine the air-fuel ratio:

[0156]

[0157] where S is the stoichiometric air-fuel ratio of the mixed gas; M air is the molar mass of air, M fuel is the molar mass of the mixed gas, x and y are the values in C x H y and C x H y is obtained by equalizing the doping ratios of methane and hydrogen.

[0158] In one embodiment, the physical property parameter determination module determines the constant-pressure adiabatic combustion temperature based on the CHEMKIN software by performing a heat balance calculation according to the proportions of the gas components in the mixed gas and the combustion process.

[0159] In one embodiment, the gas velocity determination module uses the following calculation formula to determine the gas velocity at the leakage port:

[0160]

[0161] where v e is the gas velocity at the leakage port, with the unit of m / s; R is the gas constant, 8.314 J / (mol·K); T0 is the temperature of the mixed gas, with the unit of K.

[0162] In one embodiment, the gas density determination module uses the following calculation formula to determine the gas density at the leakage port:

[0163]

[0164] ρ e is the gas density at the leakage port, with the unit of kg / m 3 ; P0 is the absolute pressure of the mixed gas, with the unit of Pa.

[0165] The Froude number determination module uses the following calculation formula to determine the flame Froude number of the underexpanded jet flame:

[0166]

[0167] Among them, Fr f is the flame Froude number; T f is the constant-pressure adiabatic combustion temperature of the mixed gas, with the unit of K; T ∞ is the ambient atmospheric temperature, with the unit of K; ρ ∞ is the ambient atmospheric density, with the unit of kg / m 3 ; d e is the leakage orifice diameter, with the unit of m.

[0168] In a third aspect, the present application provides a computer device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method described in any of the above embodiments are implemented.

[0169] In one embodiment, a computer device is provided. The computer device may be a terminal, that is, the device to be upgraded, and its internal structural diagram may be as Figure 4 shown. The computer device includes a processor, a memory, a network interface, a display screen, and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with the server through a network connection. When the computer program is executed by the processor, it realizes a method for evaluating the radiation fraction of an under-expanded jet fire of methane, hydrogen, and hydrogen-doped methane. The display screen of the computer device may be a liquid crystal display screen or an electronic ink display screen. The input device of the computer device may be a touch layer covering the display screen, or a button, a trackball, or a touchpad provided on the outer shell of the computer device, or an external keyboard, touchpad, or mouse, etc.

[0170] Those skilled in the art can understand that Figure 4 the structure shown in

[0171] is only a block diagram of some structures related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine some components, or have different component arrangements.

[0172] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided in this application can include non-volatile and / or volatile memories. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0173] The above methane, hydrogen, and hydrogen-doped methane underexpanded jet fire radiation fraction evaluation processing method, device, equipment, and medium can accurately and reliably determine the radiation fraction of the underexpanded jet fire of the hydrogen-doped methane mixed gas, providing a basis for determining the thermal radiation protection safety distance. The radiation fraction of the mixed gas underexpanded jet fire determined in this application has good consistency and can be applied to the evaluation of the underexpanded jet fire of gas pipelines and storage equipment with different doping ratios of hydrogen-doped methane. Compared with the existing calculation methods, the new formula proposed in the present invention can calculate the radiation fraction of the underexpanded jet fire of the hydrogen-doped methane mixed gas. The calculation range covers any mixing ratio, realizing the use of the same formula to calculate the radiation fractions of methane, hydrogen, and hydrogen-doped methane underexpanded jet fire with any ratio, ensuring the accuracy and consistency of the calculation results.

[0174] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification. It should be noted that "in one embodiment of the present application", "for example", "again, for example", etc. are intended to illustrate the present application, rather than to limit the present application. The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for evaluating and processing the radiation fraction of under-expanded jets of methane, hydrogen, and hydrogen-doped methane, characterized in that, It includes the following steps: Obtain the proportion of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas; wherein the mixed gas is methane, hydrogen, or methane gas doped with hydrogen; Determine the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas according to the proportion of each gas component; Determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics; Determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the temperature of the mixed gas; Determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportion of each gas component; Determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port; Determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, wherein the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula: χ R = 0.28Fr f -0.66 where χ R is the radiation fraction, and Fr f is the flame Froude number.

2. The processing method according to claim 1, characterized in that After determining the radiation fraction of the under-expanded jet flame, the processing method further includes the following steps: Determine the heat radiation value and the heat radiation protection safety distance according to the radiation fraction of the under-expanded jet flame.

3. The processing method according to claim 1, wherein After determining the radiation fraction of the under-expanded jet flame, the processing method further includes the following steps: Conduct a quantitative fire risk analysis according to the radiation fraction of the under-expanded jet flame.

4. The processing method according to claim 1, wherein In the determination of the molar mass of the mixed gas according to the proportion of each gas component, the molar mass of the mixed gas is determined by using the following calculation formula: Among them, are the molar masses of the mixed gas, methane, and hydrogen, with the unit of kg / mol, respectively; is the volume fraction of hydrogen in the mixed gas; And / or, in the determination of the gas adiabatic index of the mixed gas according to the proportion of each gas component, the gas adiabatic index of the mixed gas is determined by using the following calculation formula: where k fuel , are the adiabatic indices of the mixed gas, methane, and hydrogen, respectively; And / or, in the determination of the air-fuel ratio of the mixed gas according to the proportion of each gas component, it is determined by using the following calculation formula: Among them, S is the stoichiometric air-fuel ratio of the mixed gas; M air is the molar mass of air, M fuel is the molar mass of the mixed gas, x, y are the values in C x H y and are obtained after the doping ratios of methane and hydrogen are equal; C x H y is obtained by equalizing the doping ratios of methane and hydrogen; the determination of x and y in C x H y is determined by the following calculation formula: where x H2 is the volume fraction of hydrogen in the mixed gas, is the volume fraction of methane in the mixed gas, and the mixed gas includes at least one of hydrogen and methane.

5. The processing method according to claim 4, characterized in that In the determination of the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportion of each gas component and in combination with the first law of thermodynamics, it includes: According to the general formula C x H y after the equivalence of the mixed gas, determine the number of moles of carbon dioxide, water, and nitrogen in the combustion products; Determine the product enthalpy of the combustion products according to the number of moles of carbon dioxide, water, nitrogen, and the standard enthalpy of formation of carbon dioxide, water, nitrogen; Determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the product enthalpy of the combustion products.

6. The processing method according to claim 4, characterized in that In the determination of the gas velocity at the leakage port according to the molar mass of the mixed gas and the temperature of the mixed gas, the gas velocity at the leakage port is determined by using the following calculation formula: Among them, v e is the gas velocity at the leakage port, with the unit of m / s; R is the gas constant, 8.314 J / (mol·K); T0 is the temperature of the mixed gas, with the unit of K. And / or, in the determination of the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportion of each gas component, the gas density at the leakage port is determined by using the following calculation formula: ρ e is the gas density at the leakage port, with the unit of kg / m 3 ; P0 is the absolute pressure of the mixed gas, with the unit of Pa.

7. The processing method according to claim 1, characterized in that, In the determination of the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port, the flame Froude number of the under-expanded jet flame is determined by using the following calculation formula: where Fr f is the flame Froude number; T f is the constant-pressure adiabatic combustion temperature of the mixed gas, in K; T ∞ is the ambient atmospheric temperature, in K; ρ ∞ is the ambient atmospheric density, in kg / m 3 ; d e is the leakage orifice diameter, in m.

8. A device for evaluating and processing the radiation fraction of an under-expanded jet fire of methane, hydrogen, and hydrogen-doped methane, characterized in that, It includes: An acquisition module for acquiring the proportion of each gas component in the mixed gas, the absolute pressure of the mixed gas, and the temperature of the mixed gas; The physical property parameter determination module is used to determine the molar mass, gas adiabatic index, and air-fuel ratio of the mixed gas according to the proportions of the gas components; the physical property parameter determination module is further used to determine the constant-pressure adiabatic combustion temperature of the mixed gas according to the proportions of the gas components and in combination with the first law of thermodynamics; The gas velocity determination module is used to determine the gas velocity at the leakage port according to the molar mass of the mixed gas and the mixed gas temperature; The gas density determination module is used to determine the gas density at the leakage port according to the absolute pressure of the mixed gas, the gas adiabatic index of the mixed gas, and the proportions of the gas components; The Froude number determination module is used to determine the flame Froude number of the under-expanded jet flame according to the air-fuel ratio of the mixed gas, the constant-pressure adiabatic combustion temperature, the gas density at the leakage port, and the gas velocity at the leakage port; The radiation fraction determination module is used to determine the radiation fraction of the under-expanded jet flame according to the flame Froude number of the under-expanded jet flame, wherein the radiation fraction of the under-expanded jet flame is determined according to the following calculation formula: χ R = 0.28Fr f -0.66 where χ R is the radiation fraction, and Fr f is the flame Froude number.

9. A computer device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the steps of the method described in any one of claims 1-7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, the steps of the method described in any one of claims 1-7 are implemented.

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