An overpressure injury assessment method for hydrogen refueling station leakage and explosion accidents

Abstract

The present invention discloses a method for assessing overpressure damage caused by a hydrogen station leakage and explosion accident. The method comprises the following steps: obtaining leakage and explosion experimental data similar to the scenario of a numerical research model; establishing a physical model of a hydrogen station leakage and explosion accident scenario using computational fluid dynamics simulation software, and performing numerical simulation calculations using the physical model of the hydrogen station leakage scenario established based on the specific hydrogen station situation to obtain experimental data on the diffusion evolution process of the hydrogen cloud and the concentration distribution of the hydrogen cloud after the leakage accident occurs; carrying out numerical simulation calculations of the explosion accident to obtain relevant explosion overpressure experimental data; comparing the experimental data results to determine that the error range is within the range allowed by engineering applications; and rapidly assessing and predicting the overpressure intensity caused by the explosion after hydrogen leakage in the hydrogen station based on the simulation data results. The present invention can accurately provide the overpressure intensity and overpressure distribution of hydrogen station leakage and explosion accidents, and accurately predict the impact and damage caused by the explosion overpressure.

Description

Technical Field

[0001] The present invention relates to the technical field of leakage and explosion accident hazard analysis, and in particular to an overpressure damage assessment method and system for leakage and explosion accidents at hydrogen refueling stations. Background Art

[0002] Hydrogen is the most promising sustainable energy carrier in the future. As an important infrastructure for the development of the hydrogen energy industry, hydrogen refueling stations will find it difficult to support the popularization and application of hydrogen fuel cell vehicles in the future if they cannot reach a certain scale. However, with the current insufficient number of hydrogen fuel cell vehicles, a single hydrogen refueling station faces problems such as difficult site selection and approval, high land and operating costs, and difficulty in operating profitably. Adding hydrogen refueling facilities to existing gas stations to make them gas-hydrogen combined stations, using gas to feed hydrogen, is a type of hydrogen refueling station that is more suitable for the current stage of hydrogen energy development. However, hydrogen refueling stations and gas-hydrogen combined stations store large amounts of hydrogen, natural gas, and a variety of high-pressure equipment. Once leaked, serious fires and explosions can easily occur, bringing catastrophic consequences. In order to further assist the construction and development of hydrogen refueling stations in my country, improve the construction of hydrogen energy industry infrastructure, and combine the actual operating conditions of various types of hydrogen refueling stations, it is urgent to study the leakage and explosion risks of hydrogen refueling stations in my country. At present, there are still many deficiencies in the research on the consequences of leakage and explosion accidents at various types of hydrogen refueling stations:

[0003] (1) The consequence assessment of leakage and explosion accidents at co-built hydrogen refueling stations has not yet been carried out

[0004] Combined gas and hydrogen stations add hydrogen equipment such as hydrogen tube trailers, hydrogen compressors, hydrogen storage tanks, and hydrogen refueling machines to the existing high-pressure LNG and CNG facilities, making the accident risks of combined stations more complex. Furthermore, there are no domestic design specifications specifically for combined gas and hydrogen refueling stations. The construction of existing combined gas and hydrogen stations mainly refers to relevant specifications in the hydrogenation and gas refueling industries. Currently, when adding hydrogenation facilities to gas stations, [CN 112989717A] only considers fire accidents that may be caused by hydrogen leaks. However, the more serious consequences of explosion accidents and whether the risks of leakage and explosion accidents in combined stations will be compounded require further research, demonstration, and clarification.

[0005] (2) Research on hydrogen station explosion damage often ignores the leakage-diffusion process

[0006] According to the existing investigation results of hydrogen refueling station accidents, such as the explosion at a Norwegian hydrogen refueling station in June 2019, the explosion was often caused by a leak in the station equipment. The accumulated hydrogen cloud encountered an ignition source and triggered the explosion. Therefore, the study of explosion accidents in hydrogen refueling stations needs to take into account the entire process of leakage-diffusion-explosion. [Zhou Jingxuan, Zhang Xiaoxi, Guo Hucheng, Diao Xiumeng, Tang Xiuye, Wang Rongyan, Song Wenhua. Research on the consequences of physical explosions and steam cloud explosions of hydrogen storage facilities in hydrogen refueling stations [J]. Journal of Nankai University (Natural Science Edition), 2021, 54(04): 20-25.] The process of hydrogen cylinder leakage accidents was ignored, and the consequences of the explosion were directly considered, which is far from the actual situation.

[0007] (3) The existing overpressure damage assessment methods for hydrogen station leakage and explosion accidents have many shortcomings

[0008] In the study of gas explosions, the main available methods are the TNT (trinitrotoluene) equivalent method, the TNO (Netherlands Institute for Scientific Research) multi-energy method, and the CFD (computational fluid dynamics) method. The energy-based equivalent TNT method and the TNO multi-energy method are widely used in far-field problems, but near-field problems are much more complicated. The TNT model tends to overestimate the risk in the near field and underestimate the risk in the far field. This error is more obvious for hydrogen, which has a lower density and a larger diffusion coefficient. [Yan Yongjiang. Analysis of the consequences of hydrogen tank explosion accidents and countermeasures [J]. Hebei Chemical Industry, 2010, 33(02): 74-75.] These errors were not taken into account when the TNT equivalent method was used to study hydrogen tank explosions. The TNO multi-energy method is more perfect in theory, but it still has shortcomings in specific applications. In particular, the model believes that the total intensity of the gas cloud explosion is the superposition of the explosion intensities of each sub-region, but there is no consensus on the superposition method of the total intensity; the size of the confined area of the flammable gas cloud is difficult to determine, and there is no simple and effective method for selecting the explosion intensity level. Moreover, the TNO multi-energy method introduces restricted dimensions and divides multiple explosion intensity levels, but lacks objective division standards. The subjectivity in determining the restricted area dimensions and explosion intensity is high, resulting in significant differences in the calculation results for the same accident. At the same time, the model assumes that the flammable gas cloud is not uniformly mixed, and will significantly underestimate the accident risk when calculating relatively uniform gas cloud explosion accidents with a long formation time. In addition to the above methods, for example, [Quantitative Risk Assessment Study of Hydrogen Station Accidents [J]. Zhang Jie, Chen Xingguang, Zhao Ming. Chemical Engineering Management. 2021(13)] is a risk-based assessment of the consequences of explosion overpressure. Like the TNT equivalent method and the TNO multi-energy method, it cannot take into account the interaction between equipment and the obstruction and retention effects of obstacles. Its consequence analysis cannot show the overpressure distribution at a specific location, so it has great limitations.

[0009] Furthermore, large-scale leak explosion experiments are difficult, unsafe, and costly. However, with the continuous advancement of computational fluid dynamics (CFD) technology, the accuracy of numerical simulations continues to improve. Consequently, many researchers have adopted computational fluid dynamics (CFD) technology to simulate leak explosion accidents. FLACS offers three distinct advantages over other CFD software for calculating gas explosions: a unique (β-flame) flame development model to simulate the gas explosion process, a porosity structure to represent geometric shapes, and a subgrid model to reflect flame acceleration effects. Currently, many researchers have used FLACS to recreate several large-scale explosions, helping to overcome difficulties encountered during accident investigations. The European Commission's "NaturalHy" project and GexCon AS have conducted numerous hydrogen jet diffusion and explosion tests, confirming that the errors in the simulated gas cloud concentration and peak overpressure are within acceptable limits. Summary of the Invention

[0010] In order to overcome the defects and shortcomings of the prior art, the purpose of the present invention is to provide a method for assessing overpressure damage in hydrogen station leakage and explosion accidents.

[0011] The present invention is achieved through at least one of the following technical solutions.

[0012] A method for assessing overpressure damage in a hydrogen refueling station leakage and explosion accident comprises the following steps:

[0013] Step 1: Obtain leakage explosion experimental data similar to the scenario of the numerical research model;

[0014] Step 2: Based on the type and scale of the hydrogen refueling station, use computational fluid dynamics simulation software to establish a physical model of the hydrogen refueling station leakage and explosion accident scenario. Combined with the local environment, determine the leakage accident scenario, divide the grid, and determine the corresponding parameter settings;

[0015] Step 3: Using a physical model of a hydrogen refueling station leakage and explosion accident scenario established based on the specific hydrogen refueling station situation, numerical simulation calculations are performed to obtain the diffusion evolution process of the hydrogen cloud after the leakage accident occurs, and experimental data on the concentration distribution of the hydrogen cloud is obtained;

[0016] Step 4: Determine the ignition source, ignition source size, ignition source location, and ignition source occurrence time based on the actual layout and environmental conditions of the hydrogen refueling station, and perform numerical simulation calculations of the explosion accident based on the state of the hydrogen cloud in step 3 to obtain relevant explosion overpressure experimental data;

[0017] Step 5: Compare the data obtained in steps 3 and 4 with the experimental data in step 1. If the error range is within the allowable range for engineering applications, use the simulation result data. Otherwise, return to step 2 to readjust the simulation mesh division and parameter settings until the error remains within the allowable range.

[0018] Step 6: Based on the simulation data results determined in step 5, quickly evaluate and predict the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station.

[0019] Preferably, the post-leakage diffusion test data include: equivalent combustible gas cloud volume, hydrogen cloud concentration distribution, and equivalence ratio; the explosion overpressure test data include: indoor peak overpressure, maximum oscillation amplitude on the overpressure curve, overpressure curves at different positions, indoor peak overpressure curve, and flame speed.

[0020] Preferably, in step 2, the physical model of the hydrogen station leakage and explosion accident scenario includes determining the leakage hole size, leakage hole shape, leakage source location, leakage pressure, and leakage direction;

[0021] Environmental factors include ambient temperature, local atmospheric pressure, local gravitational acceleration, atmospheric stability, and ground roughness;

[0022] Grid division and parameter setting include determining the grid size, grid core area, grid stretching range, stretching coefficient, number and location of monitoring points, output variables, and boundary conditions.

[0023] Preferably, in step 3, the specific hydrogenation station conditions include single hydrogenation stations and combined hydrogenation and gasification stations. The levels of single hydrogenation stations include primary stations, secondary stations and tertiary stations, and the levels of combined hydrogenation and gasification stations include primary stations, secondary stations and tertiary stations.

[0024] Preferably, the ignition sources in step 4 include smoking, illegal use of fire, illegal carrying of flammable and explosive items, illegal use of non-explosion-proof electrical appliances, engine sparks, engine exhaust heat, electrical sparks, mechanical sparks, impact sparks, static sparks, electrical appliances and lightning strikes.

[0025] Preferably, the leakage sources of a single hydrogenation station include hydrogenators, hydrogenator hoses, fixed high-pressure hydrogen storage containers, long tube trailers, transport vehicles, hydrogen transmission pipelines between equipment, and connecting pipelines between equipment; the leakage sources of a combined hydrogenation and gasification station include hydrogenators, hydrogenator hoses, gas dispensers, gas dispenser hoses, fixed high-pressure hydrogen storage containers, gas storage tanks, long tube trailers, transport vehicles, hydrogen transmission pipelines, and gas transmission pipelines.

[0026] Preferably, in step 5, the data result obtained in step 3 is compared with the data result in step 1 to determine whether the error range is within the range allowed by the engineering application. The specific process is:

[0027] Obtain the hydrogen time history curve at each monitoring point based on the numerical simulation results in step 3, and compare it with the experimental data obtained in step 1. If the maximum relative error is less than 20%, use the simulation calculation data result;

[0028] According to the numerical simulation results in step 4, the overpressure time history curve of each monitoring point is obtained and compared with the experimental data obtained in step 1. If the maximum relative error is less than 20%, the simulation calculation data result is adopted.

[0029] Preferably, in step 6, the process of quickly evaluating and predicting the overpressure intensity caused by the explosion after the leakage of hydrogen / HCNG in the hydrogen refueling station is specifically as follows: the explosion overpressure and pressure wave propagation process at different locations can be obtained by calculation through numerical simulation software, and the different levels of hazard areas of the explosion accident are determined according to the corresponding overpressure damage criterion table to complete the explosion overpressure damage assessment.

[0030] The expansion process of hydrogen / HCNG after leakage is considered an isentropic process. The release conditions after gas expansion will be used as the initial conditions for CFD simulation of gas diffusion, and the following equations are used for calculation:

[0031]

[0032] Where: T1 is the temperature of the gas after expansion, °C; P a is the ambient atmospheric pressure; u1 is the gas velocity before expansion; u2 is the gas velocity after expansion, m / s; C p is the specific heat of hydrogen at constant pressure; is the mass flow rate of the gas after expansion, kg / s; A2 is the area of the vented gas after expansion; P2 is the pressure at the leak port; T2 is the temperature at the leak port; A1 is the area of the vented gas at the leak port; R is the gas constant; is the mass flow rate of gas at the leak point.

[0033] 10. The method for overpressure damage assessment in a hydrogen refueling station leakage and explosion accident according to claim 9, wherein the mathematical model governing equations of compressible fluid flow used in computational fluid dynamics software are as follows:

[0034] The governing equation for conservation of mass is:

[0035]

[0036] Among them, β v is the volume porosity; u j is the average velocity in the jth direction; is the mass rate; V is the volume; ρ is the initial density; x j is the distance in the j direction;

[0037] Momentum equation governing equations:

[0038]

[0039] Among them, F o,i is the wall friction; g i is the acceleration of gravity in the i direction; β v is the volume porosity; β j is the area porosity in the jth direction; u i is the average velocity in the jth direction; σ ij is the stress tensor; F w,i is the wall friction in the i direction; ρ0 is the initial density; g is the acceleration due to gravity;

[0040] μ eff is the effective viscosity, which is governed by the following equation:

[0041]

[0042] μ is the dynamic viscosity, Pa·s; ε is the dissipation coefficient of turbulent kinetic energy; C is the turbulent kinetic energy coefficient; μ is the constant in the k-ε equation.

[0043] Preferably, step 4 specifically includes the following steps:

[0044] (1) Establish a three-dimensional numerical simulation geometric model for explosion accidents and perform mesh division;

[0045] (2) Determine the ignition source. In the explosion calculation, for the combustion model, the premixed cloud of fuel and oxidizer ignites and escalates to an explosion. Before the escalation, the stable non-turbulent premixed cloud of fuel and oxidizer burns at a laminar combustion velocity:

[0046]

[0047] is the initial laminar combustion velocity; Φ is the equivalence ratio; fuel is the fuel.

[0048] Preferably, the transmission equation of fuel mass fraction is:

[0049]

[0050] in, is the mass fraction of fuel, is turbulent diffusion, is the source term; is the average density, kg·m -3 ; D is the diffusion coefficient.

[0051] Compared with the prior art, the present invention has the following beneficial technical effects:

[0052] The present invention provides a method for assessing overpressure damage in hydrogen station leakage and explosion accidents, which can accurately determine the hazard area of the explosion accident and complete the explosion overpressure damage assessment. It can quickly conduct numerical analysis and research on the external flow field area, and the system efficiently obtains the distribution of the explosion overpressure intensity of the explosion external flow field, which can more realistically restore the actual leakage and explosion scene, and is more in line with the actual leakage and explosion working conditions, with higher calculation accuracy. By analyzing the dangers of hydrogen station leakage and explosion accidents and simulating hydrogen station leakage and explosion accidents through a leakage and explosion accident network model, data support can be provided for reducing the risk of leakage and explosion accidents, and the overpressure intensity and overpressure distribution of hydrogen station leakage and explosion accidents can be accurately provided, and the impact and damage caused by the explosion overpressure can be accurately predicted, thereby effectively preventing and controlling such accidents, and ultimately achieving the purpose of reducing casualties and property losses, with significant economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A schematic diagram of a method and system flow chart for overpressure damage assessment in a hydrogen refueling station leakage and explosion accident according to an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the process flow of a hydrogen refueling station according to an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of the plan layout of a hydrogen refueling station according to an embodiment of the present invention;

[0056] Figure 4 This is a schematic diagram of a curve showing the change in volume of flammable gas cloud over time after a hydrogenation machine leaks according to an embodiment of the invention;

[0057] Figure 5 Schematic diagram of hydrogen cloud concentration distribution and ignition point position at Z=0.5m and XY plane within the flammable range 1.8s after the hydrogen refueling machine leaks in Example 1 of the present invention;

[0058] Figure 6 Schematic diagram of explosion overpressure distribution at different positions on the XY plane at a height of Z=1m after an explosion in Example 1 of the present invention;

[0059] Figure 7 Schematic diagram of the overpressure variation curve over time at two monitoring points near the hydrogenation machine according to the first embodiment of the present invention;

[0060] Figure 8 Schematic diagram of hydrogen cloud concentration distribution and ignition point position at 4.8 seconds after the hydrogen refueling machine leaks in Example 2 of the present invention, Z = 0.8m, and the XY plane is within the flammable range;

[0061] Figure 9Schematic diagram of explosion overpressure distribution at different positions on the XY plane at a height of Z=0.8m after the explosion in Example 2 of the present invention;

[0062] Figure 10 This is a schematic diagram of a curve showing overpressure variation over time at two monitoring points near a hydrogen storage cylinder group according to a second embodiment of the present invention;

[0063] Figure 11 Schematic diagram of hydrogen cloud concentration distribution and ignition point position at 1.2 seconds after the hydrogen refueling machine leaks in Example 3 of the present invention, Z=1m, and the XY plane is within the flammable range;

[0064] Figure 12 This is a schematic diagram of the explosion overpressure distribution at different positions on the XY plane at a height of Z=1m after the explosion in Example 3 of the present invention;

[0065] Figure 13 Schematic diagram of the overpressure variation curve over time at two monitoring points near the hydrogenation machine in Example 3 of the present invention. DETAILED DESCRIPTION

[0066] The following is a clear and complete description of the technical solutions in the embodiments of the present invention, in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0067] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0068] Example 1

[0069] like Figure 1 A method for assessing overpressure damage caused by a hydrogen refueling station leakage and explosion accident is shown, which specifically includes the following steps:

[0070] Step 1: Obtain leakage explosion experimental data similar to the scenario of the numerical research model through experiments or literature research;

[0071] In this step, the post-leakage diffusion experimental data include: equivalent combustible gas cloud volume, hydrogen cloud concentration distribution, equivalence ratio (ratio of actual air-fuel ratio to theoretical air-fuel ratio in combustible gas cloud); the explosion overpressure experimental data include: indoor peak overpressure, maximum oscillation amplitude on the overpressure curve, overpressure curves at different positions, indoor peak overpressure curve and flame speed.

[0072] Step 2: Based on the type and scale of the hydrogen refueling station, use computational fluid dynamics simulation software (such as FLACS) to establish a physical model of the hydrogen refueling station leakage and explosion accident scenario. Combined with the local environment, determine the leakage accident scenario, divide the grid, and determine the corresponding parameter settings;

[0073] Step 2-1: Determine the type and level of hydrogen refueling station:

[0074] Before conducting an overpressure damage assessment for a hydrogen refueling station leak and explosion, the type and scale of the station must be determined. Currently, existing hydrogen refueling stations are primarily standalone hydrogen refueling stations. As hydrogen refueling stations become increasingly widespread, the construction of combined hydrogen and gas refueling stations based on existing gas refueling stations will become the mainstream in the future. Hydrogen refueling station construction models are primarily categorized as single hydrogen refueling stations and combined hydrogen refueling stations. Combined gas and hydrogen refueling models primarily include CNG-hydrogen and LNG-hydrogen combined stations. According to GB50516-2010, "Technical Specifications for Hydrogen Refueling Stations," and the updated national standard GB 50156-2021, "Technical Standards for Automobile Gasoline, Gasoline, and Hydrogen Refueling Stations," the grading standards for hydrogen refueling stations and combined gas and hydrogen refueling stations are shown in Tables 1 and 2.

[0075] Table 1 Classification of hydrogen refueling stations

[0076]

[0077] Table 2 Classification principles for combined hydrogenation and gasification stations

[0078]

[0079]

[0080] Note: G is the capacity of hydrogen storage tank (bottle, well) (kg), V LNG is the total volume of LNG storage tank (m 3 ),V CNG is the total volume of CNG storage facilities (m 3 ), S3 and S4 are identification indicators derived from the major hazard source identification indicators.

[0081] Step 2-2: Determine the spill scenario

[0082] In this step, the specific steps for determining the leakage accident scenario are as follows:

[0083] (1) Determine the location of the leak:

[0084] The main process flow of hydrogen refueling station is as follows: Figure 2 As shown, the layout diagrams of hydrogenation single station and hydrogenation and gasification combined station are as follows: Figure 3As shown; a single hydrogen refueling station is mainly divided into three areas, namely the filling area, the equipment area and the station control system area. The main equipment in the filling area is the hydrogen refueling machine; the main equipment in the equipment area is the compressor, the high-pressure hydrogen storage container, and the long tube trailer. Among them, the high-pressure hydrogen storage container can be divided into vertical steel belt wrapped high-pressure hydrogen storage container, horizontal steel belt wrapped high-pressure hydrogen storage container, and gas cylinder group high-pressure hydrogen storage container. The station control system area mainly includes the monitoring room and the distribution room, etc. In addition to the above equipment, the combined gas refueling station also has gas refueling machines and gas storage tanks. According to the process flow and floor plan of the above hydrogen refueling station, the possible leakage sources of different types of hydrogen refueling stations are determined as shown in Table 3. The leakage sources of hydrogen refueling stations include but are not limited to those listed in the table.

[0085] Table 3 Possible leakage sources of single hydrogenation and hydrogenation and gasification combined stations

[0086]

[0087] The above determination method is described in detail below with a specific example, assuming that leakage is caused by a rupture of a hydrogenation hose of a 35MPa hydrogenation machine.

[0088] (2) Determine the leakage conditions

[0089] According to the leakage source determined in step 2-1(1), the leakage conditions mainly include leakage location, leakage speed, leakage hole shape and size, leakage time, leakage form, ambient wind speed, and ambient temperature.

[0090] Assume that a rupture occurs at the hydrogenation hose of a 35MPa hydrogenation machine, causing a leakage accident. Taking a small hole leakage with a relatively high leakage probability as an example, the leakage hole is circular with a diameter of 10mm, the leakage hole coordinates are (24.7, 6.4, 1), the leakage direction is +X, the ambient temperature is 15℃, the local atmospheric pressure is 101kPa, and the local gravity acceleration is 9.8m / s 2 ,Since this paper mainly studies the leakage and diffusion situation in ,hydrogen refueling stations, the influence of complex terrain is not ,considered. The ground roughness is set to “RURAL”, the ,ambient wind speed is 0m / s, and the atmospheric stability is F.

[0091] A geometric model was established using FLACS. The calculation domain was 85 × 85 × 20 m, the calculation core area was 45 × 30 × 10 m, and the grid size was 0.5 m. When meshing the gas leak diffusion, FLACS used a uniform grid along the jet orifice and a gradient grid perpendicular to the jet orifice, with a stretch factor of 1.1. Furthermore, the grid on the left and right sides perpendicular to the jet orifice was further refined. Therefore, the grid near the leak hole was refined to 0.175 m, resulting in a total of 440,000 grid cells. 1,638 monitoring points were evenly distributed within the calculation domain, extending from (10, -7, 0) to (60, 22, 6).

[0092] Based on the leakage explosion scenario predicted in step 2 and the determined leakage explosion type, the boundary conditions of the three-dimensional numerical simulation model are determined. The boundary conditions on the six outer boundaries of the FLACS calculation domain can be selected from the following boundary conditions: Euler boundary, Nozzle boundary, Plane wave boundary, Symmetry boundary, Wind boundary, and Bernoulli boundary. In subsonic flow, local disturbances in the flow field are ubiquitous. It is necessary to obtain a good convergence speed while ensuring that the physical model is close to reality. The best choice for the boundary position is determined, and a balance is made between memory and computational efficiency, computational accuracy, and cost. When mainly performing fluid flow simulation, that is, simulating the leakage diffusion process, wind boundary control is often selected. The wind boundary provides the properties of the atmospheric environment and the atmospheric boundary layer near the ground. Here, the atmospheric boundary layer theory is mainly described and applied. First, the characteristic length is defined:

[0093]

[0094] Among them, ρ a is the atmospheric density, T a is the initial atmospheric temperature, H s is the explosion overpressure flux from the ground, μ * is the friction velocity, C p is the constant pressure specific heat of hydrogen, J / (kg·k); k is the turbulent kinetic energy, m 2 s -2 ; g is the acceleration due to gravity, ms -2 The characteristic length corresponding to the atmospheric stability degree is shown in Table 4.

[0095] Table 4 Correspondence between characteristic length and atmospheric stability

[0096]

[0097] When performing explosion simulation, the boundary of the calculation area is generally selected as "Euler". In order to minimize the impact of the boundary on the propagation of flames and pressure waves, it is necessary to extend the boundaries in all directions. Here, the inviscid flow equation (Euler) is discretized into boundary elements, that is, the momentum equation and continuity equation are used on the boundary, and only in the case of outflow.

[0098] For the simulation of leakage and diffusion processes, the diffusion flux adopts the second-order format, the convection flux adopts the hybrid format of the second-order upwind format and the second-order difference format, the time step format adopts the first-order backward Euler format, and the CFL number (CFLC sound velocity and CFLV fluid velocity) is used to control the time step. The pressure correction term adopts the SIMPLE algorithm, and the iterative method is used to calculate the mass residual to be less than 1×10 -4, and obtain the discrete solution.

[0099] The boundary conditions are set according to the leakage direction, atmospheric environment and the properties of the near-ground atmospheric boundary: the X-axis direction boundary is defined as XLO, and the lower boundary is defined as the upper and lower boundaries of the Y and Z axes in turn; the boundary conditions of this simulation set the XLO, XHI, YHI, and ZHI boundaries as "wind" and the ZLO and YLO boundaries as "Nozzle".

[0100] Step 3: Using a physical model of a hydrogen refueling station leakage scenario established based on the specific hydrogen refueling station situation, numerical simulation calculations are performed to obtain the diffusion evolution process of the hydrogen cloud after the leakage accident occurs, and experimental data on the concentration distribution of the hydrogen cloud is obtained;

[0101] The leakage process was solved using FLACS v10.6. The expansion of hydrogen / HCNG after a leak can be considered an adiabatic expansion process. Due to the small aperture, it can also be considered a flat-walled circular orifice. Therefore, the expansion of hydrogen / HCNG after a leak is an adiabatic expansion process at a flat-walled circular orifice. This adiabatic expansion process can be considered an isentropic process. The release conditions after gas expansion serve as the initial conditions for the CFD simulation of gas diffusion, which can be calculated using the following set of equations:

[0102]

[0103] Where: T1 is the temperature of the gas after expansion, °C; P a is the ambient atmospheric pressure, Pa; u1 is the gas velocity before expansion, m / s; u2 is the gas velocity after expansion, m / s; C p is the specific heat of hydrogen at constant pressure, J / (kg·k); is the mass flow rate of the gas after expansion, kg / s; A2 is the area of the vented gas after expansion, m 2 ; P2 is the pressure at the leak port, Pa; T2 is the temperature at the leak port, ℃; A1 is the area of the gas released at the leak port, m 2 ; R is the gas constant; is the mass flow rate of gas at the leak, kg / s.

[0104] The governing equations of the mathematical model for compressible fluid flow used in FLACS are as follows:

[0105] The governing equation for conservation of mass is:

[0106]

[0107] Among them, β v is the volume porosity; u j is the average speed in the jth direction, m / s; is the mass rate, kg·s-1 ; V is volume, m 3 ; ρ is the initial density, kg·m -3 ;x j is the distance in the j direction, m.

[0108] Momentum equation governing equations:

[0109]

[0110] Among them, F o,i is the wall friction, N; g i is the acceleration due to gravity in the i direction, m·s -2 β v is the volume porosity; β j is the area porosity in the jth direction; u i is the average velocity in the jth direction, m / s; σ ij is the stress tensor, N·m -2 ; F w,i is the wall friction in direction i, N; ρ0 is the initial density, kg·m -3 ; g is the acceleration due to gravity, m·s -2 .

[0111]

[0112] δ ij is the Cronk trigonometric function. If i=j, δ ij =1, if i≠j, δ ij =0=0. u k is the average velocity (kth component, vector); is; x k is the length coordinate at k.

[0113] μ eff is the effective viscosity, which is governed by the following equation:

[0114]

[0115] μ is the dynamic viscosity, Pa·s; ε is the dissipation coefficient of turbulent kinetic energy, m 2 ·s -3 ; is the turbulent kinetic energy coefficient, m 2 ·s -2 ; C μ is the constant in the k-ε equation, usually C μ =0.09.

[0116] Flow shear stress (G s ), wall shear stress (G W ), buoyancy (G b ) and sub-meshes (G o) for turbulent kinetic energy P k The contribution to the generation of is as follows:

[0117] P k =G s +G W +G b +G o (7)

[0118] like Figure 4 The figure shows the time-varying curve of the flammable gas cloud volume after a hydrogen refueling leak in an embodiment of the present invention. The figure shows that despite the leak aperture being only 10 mm, the high-pressure hydrogen leak and the flammable gas cloud diffused extremely rapidly. The flammable gas cloud reached its maximum volume within 2 seconds of the leak initiation, leaving no time for personnel to take measures to control the leak.

[0119] like Figure 5 The figure shows the hydrogen cloud concentration distribution in the flammable range (4% to 76%) at Z = 0.5 m 1.8 seconds after the hydrogen refueling machine leaks in an embodiment of the present invention. It can be seen from the figure that the flammable hydrogen cloud diffuses to the chiller 1.8 seconds after the hydrogen refueling machine leaks. At this time, the affected range of the flammable hydrogen cloud reaches 33×8×5 m.

[0120] Step 4: Determine the ignition source size, location, and time of ignition occurrence based on the actual layout and environmental conditions of the hydrogen refueling station, and perform numerical simulation calculations of the explosion accident based on the state of the hydrogen cloud in step 3 to obtain relevant explosion overpressure experimental data;

[0121] (1) Establish a three-dimensional numerical simulation geometric model for explosion accidents and perform mesh division.

[0122] The rdfile.exe program provided in the FLACS software toolkit uses the mesh information file cg.dat3 from the leak-diffusion simulation to read the temporary result file rd.n001 (containing the cloud map information at that moment) recorded during the calculation process and map it to a new mesh information file as the initial state for subsequent analysis. Because the time scale of the explosion analysis is much smaller than that of the leak-diffusion analysis, the gas leak source is interrupted to speed up the calculation. The mesh is re-divided into cubes, and all boundary conditions are changed to EULER (Eulerian boundaries). The initial conditions are reset, and the Courant number is set to CFLC = 5 and CFLV = 0.5. The cloud map is output using NPLOT mode to adapt to the explosion analysis process.

[0123] (2) Determine the ignition source

[0124] Identifying the ignition source includes determining the size, location, and time of occurrence of the ignition source. Fire sources at hydrogen refueling stations include smoking, illegal use of fire, illegal carrying of flammable and explosive items, illegal use of non-explosion-proof electrical appliances, engine sparks, engine exhaust heat, electrical sparks, mechanical sparks, impact sparks, static sparks, electrical appliances, and lightning strikes. Based on the actual situation of the hydrogen refueling station model, determine the location that meets the actual situation for ignition. In this example, the engine spark is used as the ignition source, and the specific coordinates of the ignition point are (33.6, 6.5, 0.5). Figure 5 shown.

[0125] In the explosion calculation, for the combustion model, the ignition of the premixed cloud of fuel and oxidizer may escalate to an explosion. Before escalation, the stable non-turbulent premixed cloud of fuel and oxidizer will burn at a laminar burning velocity:

[0126]

[0127] is the initial laminar combustion velocity, m / s; Φ is the equivalence ratio; fuel is the fuel.

[0128] The laminar burning velocity depends on the fuel and the equivalence ratio Φ. For mixtures with a fuel content below the lower flammable limit (LFL) or above the upper flammable limit (UFL), the laminar burning velocity is zero, meaning no combustion occurs. During an explosion, the flame accelerates and becomes turbulent. Turbulent burning velocities are much greater than laminar burning velocities because reactants and products are better mixed. Most leak explosion scenarios involve non-premixed or diffusion flames. For most leak explosions, the burning rate is controlled by the mixing of fuel and air, and the simple mixed combustion (Mixed Is Burnt) combustion model can be applied.

[0129] The transport equation for fuel mass fraction is shown below:

[0130]

[0131] in, is the mass fraction of fuel, is turbulent diffusion, is the source term; is the average density, kg·m -3 ; D is the diffusion coefficient, m 2 ·s -1 ; is the average velocity of the ith component of turbulence.

[0132] Step 5: Compare the data obtained in steps 3 and 4 with the experimental data in step 1. If the error range is within the allowable range for engineering applications, use the simulation result data. Otherwise, return to step 2 to adjust the simulation mesh division and parameter settings.

[0133] The present invention uses the high-pressure hydrogen leakage and explosion experiment conducted by Osaka Gas Company of Japan to verify the above model (Tanaka T, Azuma T, Evans JA, et al. Experimental study on hydrogen explosions in a full-scale hydrogen filling station model [J]. International Journal of Hydrogen Energy, 2007, 32 (13): 2162-2170.), and conducts a 40MPa hydrogen storage container leakage and explosion accident reconstruction. The volume of the hydrogen storage container is 0.25m 3 The simulation used a leak hole with an 8mm diameter, leaking along the negative X-axis, with an ambient wind speed of 3m / s and a wind direction in the positive X-axis. The calculation assumed that the gas temperature in the cylinder was equal to the ambient temperature, approximately 15°C. The simulation results were compared with experimental data, confirming that the overpressure distribution at the monitoring point obtained from the simulation was within 20% of the experimental results. This also confirmed that the FLACS simulation of the entire process of hydrogen leakage, diffusion, and explosion can effectively predict explosion overpressure.

[0134] Step 6: Based on the simulation data results determined in step 5, quickly evaluate and predict the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station.

[0135] (1) Determine the overpressure distribution of the explosion accident.

[0136] like Figure 6 The figure shows the distribution of explosion overpressure at different positions in the XY plane at a height of Z = 1m after the explosion in the example of the present invention. It can be seen from the figure that the impact of the explosion overpressure will affect the two vehicle hydrogenation machines, the chiller and the station building in the hydrogenation station. Among them, the areas with larger explosion overpressure values are concentrated near the ignition point and near the hydrogenation machine where the leak occurred.

[0137] (2) Overpressure time curves at different locations in the hydrogen refueling station

[0138] like Figure 7The graph shows the overpressure variation over time at two monitoring points, monitoring point A (24.4, 6.1875, 1.25) at a horizontal distance of -0.3m, a horizontal distance of 0.3m, and a height of 1.25m from the centerline of the hydrogenator, and monitoring point B (25.1, 6.1875, 1.25) at a horizontal distance of +0.4m, a horizontal distance of 0.3m, and a height of 1.25m from the centerline of the hydrogenator, as described in an example of the present invention. It can be seen from the graph that the explosion overpressure at monitoring point B reached over 20kPa 0.00067 seconds after the explosion.

[0139] (3) Analysis of overpressure consequences

[0140] People and buildings will suffer certain injuries and damage under the action of shock waves, the consequences of which are shown in Table 5.

[0141] Table 5 Damage to buildings and personnel caused by explosion overpressure

[0142]

[0143] Combine Figure 6 、 Figure 7 From the analysis of Table 5, it can be seen that if a leakage accident occurs in a 35MPa hydrogen refueling machine, once the hydrogen cloud after the leakage encounters an ignition source and explodes, it will cause serious damage to the leaking hydrogen refueling machine, causing serious injuries or even deaths to many people within a horizontal range of 2m and a height of 2m around the hydrogen refueling machine; people within a range of 4×7m near the ignition point may be injured by debris. Due to the blocking effect of the building's outer walls and fences, people inside the station building and outside the fences are relatively safe.

[0144] Example 2

[0145] Steps 1-3 are the same as steps 1 to 2-1 of the theoretical calculation method for analyzing the risk of a fire accident at a hydrogen refueling station in Example 1;

[0146] Step 2-2: Determine the spill scenario

[0147] (1) Determine the leakage conditions

[0148] Assume that a leakage accident occurs at a 45MPa hydrogen storage cylinder. Take a small hole leakage with a relatively high leakage probability as an example. The leakage hole is circular with a diameter of 10mm. The coordinates of the leakage hole are (63.1, 27.8, 0.8), the leakage direction is +Y, the ambient temperature is 15℃, the local atmospheric pressure is 101kPa, and the local gravity acceleration is 9.8m / s. 2 , the ground roughness is set to "RURAL", the ambient wind speed is 0m / s, and the atmospheric stability is F.

[0149] The calculation area was 80 × 85 × 20 m, with a core area of 40 × 40 × 10 m. The grid size was 0.5 m. When meshing the gas leak diffusion, FLACS used a uniform grid along the jet orifice and a gradient grid perpendicular to the jet orifice, with a stretch factor of 1.1. Furthermore, the grid on the left and right sides perpendicular to the jet orifice was further refined. Therefore, the grid near the leak hole was refined to 0.12 m, resulting in a total of 570,000 grid cells. 3,696 monitoring points were evenly distributed within the cubic area from (36, 9, 0) to (90, 33, 10) in the calculation area.

[0150] Step 3: Using a physical model of a hydrogen refueling station leakage scenario established based on the specific hydrogen refueling station situation, numerical simulation calculations are performed to obtain the diffusion evolution process of the hydrogen cloud after the leakage accident occurs, and experimental data on the concentration distribution of the hydrogen cloud is obtained;

[0151] like Figure 8 The figure shows the hydrogen cloud concentration distribution at Z = 0.8m, 4.8 seconds after the hydrogen storage cylinder leaks in an embodiment of the present invention, and the XY plane is within the flammable range (4% to 76%). It can be seen from the figure that 4.8 seconds after the hydrogen refueling machine leaks, the impact range of the flammable hydrogen cloud will pass through the gap between the explosion-proof wall and the surrounding wall and expand to the compressor. At this time, the impact range of the flammable hydrogen cloud reaches 50×6×3m.

[0152] Step 4: Determine the ignition source size, location, and time of ignition occurrence based on the actual layout and environmental conditions of the hydrogen refueling station, and perform numerical simulation calculations of the explosion accident based on the state of the hydrogen cloud in step 3 to obtain relevant explosion overpressure experimental data;

[0153] According to the actual situation of the hydrogen refueling station model, the location that meets the actual situation is determined for ignition. In this example, the impact spark is used as the ignition source, and the specific coordinates of the ignition point are (64, 33.3, 1). Figure 8 shown.

[0154] Step 5: Compare the data obtained in steps 3 and 4 with the experimental data in step 1. If the error range is within the allowable range for engineering applications, use the simulation result data. Otherwise, return to step 2 to adjust the simulation mesh division and parameter settings.

[0155] The embodiments of the present invention are based on the hydrogen leakage experiment in a semi-enclosed corridor conducted by Swain MR, Grilliot ES, Swain MN. Risks incurred by hydrogen escaping from containers and conduits [R]. National Renewable Energy Lab. (NREL), Golden, CO (United States), 1998.] and the 63.7m3 hydrogen leakage experiment conducted by Bauwens CR, Chao J, Dorofeev SB. Effect of hydrogen concentration on vented explosion overpressures from lean hydrogen–air deflagrations [J]. International journal of hydrogen energy, 2012, 37(22): 17599-17605. 3 The model was validated through ventilation explosion tests of hydrogen-air mixtures with hydrogen contents ranging from 12% to 19%. Comparing the simulation results with experimental data confirmed that the overpressure distribution at monitoring points derived from the simulation was within 20% of the experimental results. This confirms that FLACS, which simulates the entire process of hydrogen leakage, diffusion, and explosion, can effectively predict explosion overpressure.

[0156] Step 6: Based on the simulation data results determined in step 5, quickly evaluate and predict the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station.

[0157] (1) Determine the overpressure distribution of the explosion accident.

[0158] like Figure 9 The figure shows the explosion overpressure distribution at different positions in the XY plane at a height of Z = 0.8 m after the explosion in the example of the present invention. It can be seen from the figure that the main impact area of the explosion overpressure is still concentrated at the hydrogen storage cylinder group where the leakage accident occurred, and it will cross the wall to affect the personnel on the other side of the wall.

[0159] (2) Overpressure time curves at different locations in the hydrogen refueling station

[0160] like Figure 10The graph shows the overpressure variation over time at monitoring point A (63.28.2, 1) near the hydrogen storage cylinder and at monitoring point B (63.33, 1) on the wall, according to an example of the present invention. The graph shows that at monitoring point B, the overpressure reached over 7 kPa 0.000843 seconds after the explosion, potentially causing minor injuries to nearby personnel.

[0161] Example 3

[0162] Steps 1-3 are the same as steps 1 to 2-1 of the overpressure damage assessment method for a hydrogen refueling station leakage and explosion accident in Example 1;

[0163] Step 2-2: Determine the spill scenario

[0164] (1) Determine the leakage conditions

[0165] Assume that a rupture occurs at the hydrogenation hose of a 35MPa hydrogenation machine, causing a leakage accident. The leakage hole is circular with a diameter of 10mm. The coordinates of the leakage hole are (24.7, 16.4, 1). The leakage direction is -Y. The ambient temperature is 15℃. The local atmospheric pressure is 101kPa, and the local gravity acceleration is 9.8m / s. 2 , the ground roughness is set to "RURAL", the ambient wind speed is 3m / s, and the atmospheric stability is D.

[0166] The calculation area was 85 × 85 × 20 m, with a core area of 45 × 30 × 10 m and a grid size of 0.5 m. FLACS used a uniform grid along the jet orifice and a gradient grid perpendicular to the jet orifice for gas leakage and diffusion analysis. The stretch factor was 1.1, and the maximum grid size was 3 m. Furthermore, the grid on the left and right sides perpendicular to the jet orifice was required to be further refined. Therefore, the grid near the leak was refined to 0.10 m, resulting in a total of 520,000 grid cells. 1,038 monitoring points were evenly distributed within the cubic area from (-5, 10, 0) to (43, 24, 6) in the calculation area.

[0167] Step 3: Using a physical model of a hydrogen refueling station leakage scenario established based on the specific hydrogen refueling station situation, numerical simulation calculations are performed to obtain the diffusion evolution process of the hydrogen cloud after the leakage accident occurs, and experimental data on the concentration distribution of the hydrogen cloud is obtained;

[0168] like Figure 11 The figure shows the hydrogen cloud concentration distribution in the flammable range (4% to 76%) at Z = 1m and the XY plane 1.2 seconds after the hydrogen refueling machine leaks in an embodiment of the present invention. It can be seen from the figure that 1.2 seconds after the hydrogen refueling machine leaks, the flammable hydrogen cloud will completely surround the other hydrogen refueling / gas refueling machine, causing serious impact on the equipment in the vehicle hydrogen refueling / gas refueling machine area and surrounding personnel.

[0169] Step 4: Determine the ignition source size, location, and time of ignition occurrence based on the actual layout and environmental conditions of the hydrogen refueling station, and perform numerical simulation calculations of the explosion accident based on the state of the hydrogen cloud in step 3 to obtain relevant explosion overpressure experimental data;

[0170] According to the actual situation of the hydrogen refueling station model, the position that meets the actual situation is determined for ignition. In this example, the engine spark is used as the ignition source, and the specific coordinates of the ignition point are (24.6, 10.6, 1). Figure 11 shown.

[0171] Step 5. The embodiment of the present invention uses a numerical simulation to restore a 5.4×6.0×2.5m premixed hydrogen cloud explosion experiment and a 40MPa hydrogen leakage experiment conducted by Shell and the UK Health and Safety Laboratory using a dummy vehicle and a hydrogen refueling unit. [Shirvill LC, Roberts TA, Royle M, et al. Safety studies on high-pressure hydrogen vehicle refueling stations: Releases into a simulated high-pressure dispensing area [J]. International journal of hydrogen energy, 2012, 37(8): 6949-6964.] The obtained simulation results are compared with the experimental data to determine that the overpressure distribution at the monitoring point location obtained by the simulation calculation results is within 20% of the experimental results, and it is determined that the full process simulation of hydrogen leakage, diffusion and explosion using FLACS can relatively well predict the explosion overpressure.

[0172] Step 6: Based on the simulation data results determined in step 5, quickly evaluate and predict the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station.

[0173] (1) Determine the overpressure distribution of the explosion accident.

[0174] like Figure 12 The figure shows the explosion overpressure distribution at different positions in the XY plane at a height of Z = 1m after the explosion in the example of the present invention. As can be seen from the figure, the explosion overpressure will affect all areas of the vehicle hydrogen / gas refueling machine. In the area between the two hydrogen / gas refueling machines, the overpressure generated by the explosion is sufficient to cause minor injuries to personnel.

[0175] (2) Overpressure time curves at different locations in the hydrogen refueling station

[0176] like Figure 13The graph shows the overpressure variation over time at monitoring point A (23.5, 16, 1) near the hydrogenation reactor where the leak occurred, and at monitoring point B (24.5, 7.5, 1) near another hydrogenation reactor, as described in the present invention. The graph shows that at monitoring point B, the overpressure reached over 12 kPa at 0.00037 seconds after the explosion, sufficient to cause minor injuries to nearby personnel.

[0177] It should be noted that the contents not described in detail in the embodiments of the present invention belong to the prior art known to those skilled in the art.

[0178] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for assessing overpressure damage in hydrogen station leakage and explosion accidents, characterized in that: The following steps are involved: Step 1: Obtain leakage explosion experimental data similar to the scenario of the numerical research model. Step 2: Based on the type and scale of the hydrogen refueling station, a physical model of the hydrogen refueling station leakage and explosion accident scenario is established using computational fluid dynamics simulation software. The leakage accident scenario is determined in combination with the local environment, and the grid is divided and the corresponding parameter settings are determined. The physical model of the hydrogen refueling station leakage and explosion accident scenario includes determining the leak hole size, leak hole shape, leak source location, leak pressure, and leak direction. The local environment includes ambient temperature, local atmospheric pressure, local gravitational acceleration, atmospheric stability, and ground roughness; Grid division and parameter setting include determining grid size, grid core area, grid stretching range, stretching coefficient, number and location of monitoring points, output variables, and boundary conditions; Step 3: Using a physical model of a hydrogen refueling station leakage and explosion accident scenario established based on the specific hydrogen refueling station situation, numerical simulation calculations are performed to obtain the diffusion evolution process of the hydrogen cloud after the leakage accident, and experimental data on the concentration distribution of the hydrogen cloud are obtained; the experimental data on the concentration distribution of the hydrogen cloud include: equivalent combustible gas cloud volume, hydrogen cloud concentration distribution, and equivalence ratio; Step 4: Determine the ignition source, ignition source size, ignition source location, and ignition source occurrence time based on the actual layout and environmental conditions of the hydrogen refueling station, and perform numerical simulation calculations of the explosion accident based on the state of the hydrogen cloud in Step 3 to obtain relevant explosion overpressure experimental data; the explosion overpressure experimental data includes: indoor peak overpressure, maximum oscillation amplitude on the overpressure curve, overpressure curves at different locations, indoor peak overpressure curve, and flame speed; Step 5: Compare the simulation results obtained in Steps 3 and 4 with the experimental data in Step 1. If the error range is within the allowable range for engineering applications, use the simulation results. Otherwise, return to Step 2 to readjust the simulation mesh division and parameter settings until the error remains within the allowable range. Step 6: Based on the simulation calculation results determined in step 5, quickly evaluate and predict the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station.

2. The method for assessing overpressure damage caused by a hydrogen refueling station leakage and explosion accident according to claim 1, characterized in that: In step 3, the specific hydrogenation station situations include single hydrogenation stations and combined hydrogenation and gasification stations. The levels of single hydrogenation stations include primary, secondary and tertiary stations, and the levels of combined hydrogenation and gasification stations include primary, secondary and tertiary stations.

3. The method for assessing overpressure damage caused by a hydrogen refueling station leakage and explosion accident according to claim 1, characterized in that: The ignition sources in step 4 include smoking, illegal use of fire, illegal carrying of flammable and explosive items, illegal use of non-explosion-proof electrical appliances, engine sparks, engine exhaust heat, electrical sparks, mechanical sparks, impact sparks, static sparks, electrical appliances and lightning strikes.

4. The method for assessing overpressure damage caused by a hydrogen refueling station leakage and explosion accident according to claim 2, characterized in that: The leakage sources of a single hydrogenation station include hydrogenators, hydrogenator hoses, fixed high-pressure hydrogen storage containers, long tube trailers, transport vehicles, hydrogen transmission pipelines between equipment, and connecting pipelines between equipment; the leakage sources of a combined hydrogenation and gasification station include hydrogenators, hydrogenator hoses, gas dispensers, gas dispenser hoses, fixed high-pressure hydrogen storage containers, gas storage tanks, long tube trailers, transport vehicles, hydrogen transmission pipelines, and gas transmission pipelines.

5. The method for assessing overpressure damage caused by leakage and explosion accidents at hydrogen refueling stations according to claim 1, characterized in that: In step 5, the simulation calculation results obtained in steps 3 and 4 are compared with the experimental data in step 1 to determine whether the error range is within the range allowed by engineering applications. The specific process is as follows: Obtain the hydrogen time history curve at each monitoring point based on the simulation calculation results in step 3, and compare it with the experimental data obtained in step 1. If the maximum relative error is less than 20%, adopt the simulation calculation result; According to the simulation calculation results in step 4, the overpressure time history curve of each monitoring point is obtained and compared with the experimental data obtained in step 1. If the maximum relative error is less than 20%, the simulation calculation result is adopted.

6. The method for assessing overpressure damage caused by leakage and explosion accidents at hydrogen refueling stations according to claim 1, characterized in that: In step 6, the process of quickly evaluating and predicting the overpressure intensity caused by the explosion after the hydrogen leakage in the hydrogen refueling station is specifically as follows: the explosion overpressure and pressure wave propagation process at different locations can be obtained by calculation through numerical simulation software, and the different levels of hazard areas of the explosion accident are determined according to the corresponding overpressure damage criterion table to complete the explosion overpressure damage assessment.

7. A method for assessing overpressure damage caused by leakage and explosion accidents at hydrogen refueling stations according to any one of claims 1 to 6, characterized in that: The expansion process of hydrogen after leakage is considered as an isentropic process. The release conditions after gas expansion will be used as the initial conditions for CFD simulation of gas diffusion, and the following equations are used for calculation: Where: T1 is the temperature of the gas after expansion, °C; P a is the ambient atmospheric pressure; u1 is the gas velocity before expansion; u2 is the gas velocity after expansion, m / s; C p is the specific heat of hydrogen at constant pressure; is the mass flow rate of the gas after expansion, kg / s; A2 is the area of the vented gas after expansion; P2 is the pressure at the leak port; T2 is the temperature at the leak port; A1 is the area of the vented gas at the leak port; R is the gas constant; is the mass flow rate of gas at the leak point.

8. The method for assessing overpressure damage caused by leakage and explosion accidents at hydrogen refueling stations according to claim 7, characterized in that: The mathematical model governing equations for compressible fluid flow used in fluid mechanics simulation software are as follows: The governing equation for conservation of mass is: Among them, β v is the volume porosity; u j is the average velocity in the jth direction; is the mass rate; V is the volume; ρ is the initial density; x j is the distance in the j direction; Momentum governing equation: Among them, F o,i is the wall friction; g i is the acceleration of gravity in the i direction; β v is the volume porosity; β j is the area porosity in the jth direction; u i is the average velocity in the i-th direction; F w,i is the wall friction in the i direction; ρ0 is the initial density; g is the acceleration due to gravity; μ eff is the effective viscosity, which is governed by the following equation: μ is the dynamic viscosity, Pa·s; ε is the dissipation coefficient of turbulent kinetic energy; k is the turbulent kinetic energy coefficient; C μ is the constant in the k-ε equation.

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