A hydrogen leakage explosion safety analysis method and system based on finite element analysis

Abstract

This invention discloses a method and system for hydrogen leak explosion safety analysis based on finite element analysis. The method includes the following steps: acquiring structural, operational, and environmental parameters of a methanol-to-hydrogen crane vessel and constructing a three-dimensional geometric model; establishing a system simulation model to determine the time-varying relationships of hydrogen production rate, hydrogen flow rate, and hydrogen consumption rate; coupling these time-varying relationships to the finite element analysis model and performing transient leak and diffusion coupling analysis to obtain the concentration distribution field; identifying hazardous areas and constructing a set of trigger points; performing explosion shock wave propagation analysis to obtain the explosion pressure field distribution and structural response; assessing the safety level and generating a report. The system includes modules for model construction, system simulation, leak diffusion analysis, hazardous area identification, explosion analysis, and assessment report generation. This invention integrates the dynamic response of hydrogen production and power generation with the transient process of hydrogen leak explosion, achieving a refined assessment of the hydrogen leak explosion risk of a shipborne methanol-to-hydrogen power generation system under all operating conditions.

Description

Technical Field

[0001] This invention belongs to the field of hydrogen energy safety technology, and relates to a method and system for analyzing the safety of hydrogen leakage and explosion based on finite element analysis. Background Technology

[0002] The methanol-to-hydrogen crane vessel is a new type of offshore operation equipment. It uses an onboard methanol reforming hydrogen production unit to produce hydrogen in real time and supplies the hydrogen to fuel cells to generate electricity, providing power for the ship's crane operations, dynamic positioning and auxiliary systems. This on-demand power generation mode avoids the problem of high-pressure hydrogen storage and transportation, and has unique advantages in the field of offshore hydrogen energy applications.

[0003] However, in the actual operation of such ships, core modules such as hydrogen production units, buffer tanks, hydrogen pipelines, and fuel cell compartments are highly integrated within the limited hull space. During operation, changes in lifting load, ship swaying, and fluctuations in power demand cause a dynamic non-equilibrium state between the hydrogen production rate and the hydrogen consumption rate. Once a hydrogen leak occurs, the leakage source strength changes in real time with the system's dynamic response, and the diffusion behavior of hydrogen in the confined compartment is extremely complex. Existing safety analysis methods are mostly aimed at land-based fixed hydrogen production stations or vehicle-mounted hydrogen storage systems, using steady-state leakage models or independent diffusion explosion simulations. These methods cannot effectively reflect the interaction between the dynamic coupling characteristics of hydrogen production and power generation and the transient process of hydrogen leakage and explosion in the shipboard environment, making it difficult to accurately predict the evolution of the leakage and explosion accident chain. This restricts the safety design and protection optimization of shipboard methanol-to-hydrogen power generation systems. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a hydrogen leakage explosion safety analysis method based on finite element analysis that can achieve a refined assessment of the hydrogen leakage explosion risk under all operating conditions of a shipborne methanol-to-hydrogen power generation system.

[0005] Another object of the present invention is to provide a finite element analysis-based hydrogen leak explosion safety analysis system for performing the method.

[0006] The technical solution of this invention is: a hydrogen leak explosion safety analysis method based on finite element analysis, comprising the following steps: Step (1) Obtain the structural parameters of the methanol-to-hydrogen crane ship, the operating parameters of the methanol-to-hydrogen power generation system, and the operating environment parameters, and construct a three-dimensional geometric model including the hydrogen production module, hydrogen transmission pipeline, fuel cell module, and ship cabin structure. Step (2) Based on the three-dimensional geometric model, establish a system simulation model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system, and determine the time-varying relationship of hydrogen production rate, hydrogen flow rate and hydrogen consumption rate according to the operating conditions of the crane ship. Step (3) uses the time-varying relationship as a dynamic boundary condition and couples it to the pre-constructed finite element analysis model. In the finite element analysis model, the location of the leakage point and the leakage aperture parameters are configured. Transient leakage and diffusion coupling analysis is performed to obtain the first analysis result of the change of hydrogen concentration distribution field in the ship's cabin and surrounding space over time. Step (4) Based on the results of the first analysis, identify the dangerous area where the hydrogen concentration reaches the explosion limit, and construct a set of trigger points within the dangerous area to characterize the location of the ignition source; Step (5) Take each trigger point in the trigger point set as the ignition start position in sequence, and perform the explosion shock wave propagation analysis in the finite element analysis model to obtain the second analysis results of the explosion pressure field distribution and structural response characteristics; Step (6) Based on the second analysis results, extract the peak pressure and structural deformation data of the ship's compartment structure under different explosion conditions, evaluate the safety level based on the peak pressure and structural deformation data, and generate a safety analysis report.

[0007] Furthermore, step (2) specifically includes establishing a system simulation model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system, which specifically includes: Based on the working principle of the methanol reforming hydrogen production unit, a hydrogen production sub-model is constructed. The hydrogen production sub-model is used to characterize the dynamic relationship between the hydrogen production rate and the methanol supply and reaction temperature. Based on the power generation characteristics of fuel cell stacks, a hydrogen consumption sub-model is constructed. The hydrogen consumption sub-model is used to characterize the dynamic relationship between hydrogen consumption rate and output power and stack efficiency. By coupling the hydrogen production sub-model and the hydrogen consumption sub-model through the buffer tank pressure balance equation, the time-varying relationships of hydrogen production rate, hydrogen flow rate, and hydrogen consumption rate are obtained.

[0008] Furthermore, the transient leakage and diffusion coupling analysis described in step (3) specifically includes: In the finite element analysis model, the time-varying relationship is configured as the dynamic boundary condition of the mass flow rate of the leakage source; Discretized grid cells are generated around the leak source and inside the ship's cabins, and the properties of the hydrogen-air mixture are set within each grid cell. Based on the mass flow rate of the leakage source at each time step, the diffusion distribution of hydrogen in space is updated grid by grid, while the velocity distribution and pressure distribution of the internal flow field of the cabin are also updated. The process is iterated until convergence, and the first analysis result of the concentration distribution field changing with time is output.

[0009] Furthermore, the identification of dangerous areas where the hydrogen concentration reaches the explosion limit in step (4) specifically includes: setting a lower explosion limit threshold and an upper explosion limit threshold for hydrogen; Traverse the hydrogen concentration values ​​of each spatial node in the concentration distribution field, and mark the area covered by the spatial node whose hydrogen concentration value is between the lower explosion limit threshold and the upper explosion limit threshold as the danger zone; Within the hazardous area, multiple candidate points are selected to form a set of trigger points based on the location of the equipment and the distribution of electrical equipment.

[0010] Furthermore, the execution of the explosion shock wave propagation analysis described in step (5) specifically includes: In the finite element analysis model, the initial state of the hydrogen cloud at the trigger point is taken as the initial condition of the explosion, and the combustion reaction parameters of the hydrogen-air mixture are set. Construct a simulated environment for the propagation of the explosion shock wave between the compartment structures, and configure the propagation path of the flame front and the interaction between the shock wave and the walls of the compartment structure in the simulated environment; Pressure time history data of each unit of the ship's cabin structural wall are extracted to generate a second analysis result of the explosion pressure field distribution and structural response characteristics.

[0011] Furthermore, the assessment of security level in step (6) specifically includes: The peak pressure is compared with the preset structural ultimate bearing pressure, and the structural deformation data is compared with the preset ultimate deformation. Based on the comparison results, the security levels are divided into no-damage level, minor damage level, moderate damage level, and severe damage level. For different security levels, corresponding protection optimization suggestions are generated and embedded into the security analysis report.

[0012] Furthermore, a hydrogen leak explosion safety analysis system based on finite element analysis is provided for performing the method, the system comprising: The model building module is used to obtain the structural parameters of the methanol-to-hydrogen crane ship, the operating parameters of the methanol-to-hydrogen power generation system, and the operating environment parameters, and to build a three-dimensional geometric model that includes the hydrogen production module, hydrogen transmission pipeline, fuel cell module, and ship cabin structure. The system simulation module is used to establish a system simulation model based on a three-dimensional geometric model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system, and to determine the time-varying relationship of hydrogen production rate, hydrogen flow rate and hydrogen consumption rate according to the operating conditions of the crane ship. The leakage and diffusion analysis module is used to couple the time-varying relationship as a dynamic boundary condition to the pre-built finite element analysis model. The leakage point location and leakage aperture parameters are configured in the finite element analysis model, and transient leakage and diffusion coupling analysis is performed to obtain the first analysis result of the change of hydrogen concentration distribution field in the ship's cabin and surrounding space over time. The hazardous area identification module is used to identify hazardous areas where the hydrogen concentration has reached the explosion limit based on the first analysis results, and to construct a set of trigger points within the hazardous area to characterize the location of the ignition source; The explosion analysis module is used to sequentially take each trigger point in the trigger point set as the ignition start position, perform explosion shock wave propagation analysis in the finite element analysis model, and obtain the second analysis results of the explosion pressure field distribution and structural response characteristics. The assessment report generation module is used to extract peak pressure and structural deformation data of the ship's compartment structure under different explosion conditions based on the second analysis results, assess the safety level based on the peak pressure and structural deformation data, and generate a safety analysis report.

[0013] Furthermore, the system simulation module includes: The hydrogen production sub-model unit is used to construct a hydrogen production sub-model based on the working principle of the methanol reforming hydrogen production unit. The hydrogen production sub-model is used to characterize the dynamic correspondence between the hydrogen production rate and the methanol supply and reaction temperature. The hydrogen consumption sub-model unit is used to construct a hydrogen consumption sub-model based on the power generation characteristics of the fuel cell stack. The hydrogen consumption sub-model is used to characterize the dynamic correspondence between hydrogen consumption rate and output power and stack efficiency. The coupling unit is used to couple the hydrogen production sub-model and the hydrogen consumption sub-model through the buffer tank pressure balance equation to obtain the time-varying relationship of hydrogen production rate, hydrogen flow rate and hydrogen consumption rate.

[0014] Furthermore, the leakage diffusion analysis module includes: Boundary configuration elements are used to configure time-varying relationships as dynamic boundary conditions for the mass flow rate of a leakage source in a finite element analysis model. Mesh generation unit, used to generate discretized mesh cells around the leak source and inside the ship's cabin space, setting the properties of the hydrogen-air mixture medium in each mesh cell; The transient update unit is used to update the hydrogen diffusion distribution in space grid by grid according to the mass flow rate of the leakage source at each time step, and at the same time update the velocity distribution and pressure distribution of the internal flow field of the cabin. Iterates until the convergence state and outputs the first analysis result of the concentration distribution field changing with time.

[0015] Furthermore, the explosion analysis module includes: The initial condition configuration unit is used in the finite element analysis model to set the initial state of the hydrogen cloud at the trigger point as the initial condition for the explosion and to set the combustion reaction parameters of the hydrogen-air mixture. The propagation simulation unit is used to construct a simulated environment for the propagation of the explosion shock wave between the compartment structures. The propagation path of the flame front and the interaction between the shock wave and the walls of the compartment structure are configured in the simulation environment. The data extraction unit is used to extract the pressure time history data of each unit of the ship's cabin structural wall and generate a second analysis result of the explosion pressure field distribution and structural response characteristics.

[0016] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: 1. The present invention establishes a system simulation model to describe the dynamic response characteristics of a methanol-to-hydrogen power generation system, obtains the time-varying relationship between hydrogen production rate, hydrogen flow rate, and hydrogen consumption rate as operating conditions, and couples this time-varying relationship as a dynamic boundary condition into the finite element analysis model, realizing the integrated analysis of the dynamic response of hydrogen production and power generation and the transient process of hydrogen leakage and diffusion. This overcomes the defect in the prior art where static boundary conditions cannot reflect the real-time changes in ship operating conditions, making the leakage and diffusion analysis results more consistent with the actual operating state; 2. Based on the leakage and diffusion analysis, the present invention identifies dangerous areas that have reached the explosion limit according to the hydrogen concentration distribution field, and constructs a set of trigger points within the dangerous areas, transforming the continuously distributed concentration field into discrete ignition source candidate positions. Then, the explosion shock wave propagation analysis is performed on each trigger point in sequence, which can comprehensively evaluate the intensity and distribution law of the explosion shock wave on the ship structure under different ignition positions, avoiding the blind spots in safety assessment that may be caused by single ignition position analysis; 3. The present invention extracts the structure of the ship's compartments... The invention utilizes peak pressure and structural deformation data under different explosion conditions, compares them with preset structural limit bearing pressure and limit deformation, classifies safety levels into multiple levels, and generates corresponding protection optimization suggestions. This provides a quantitative basis for the safety design of methanol-to-hydrogen crane ships, guides the optimization of explosion-proof structures and the arrangement of pressure relief devices, and improves the overall safety of ship hydrogen energy systems. 4. This invention organically integrates system simulation modules, leakage diffusion analysis modules, hazardous area identification modules, explosion analysis modules, and assessment report generation modules. The data transmission and interaction logic between modules is clear, realizing fully automated analysis from parameter input to safety report output, improving the efficiency and accuracy of hydrogen leakage explosion safety analysis. 5. Addressing the complex multi-compartment structure of methanol-to-hydrogen crane ships, this invention accurately models the interconnected structures between compartments in leakage diffusion analysis and uses a local mesh densification strategy to capture the initial mixing area of ​​the leakage jet. This accurately simulates the migration and diffusion process of hydrogen between multiple compartments, providing a complete data foundation for identifying expanding hazardous areas and enhancing the reliability of the analysis results. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall process of the method of the present invention; Figure 2 This is a structural framework diagram of the system of the present invention. Detailed Implementation

[0018] The specific technical solution of the present invention will be further described in detail below with reference to specific examples.

[0019] like Figure 1 As shown, the present invention provides a hydrogen leakage explosion safety analysis method based on finite element analysis, which analyzes the hydrogen leakage explosion risk of a methanol-to-hydrogen crane ship under typical operating conditions. The specific steps are as follows: In step (1), the structural parameters of the methanol-to-hydrogen crane vessel, the operating parameters of the methanol-to-hydrogen power generation system, and the operating environment parameters are first obtained. The structural parameters include the geometric dimensions of the hull compartments, the thickness of the bulkheads, the layout of the passageways between compartments, the installation location of the hydrogen production module, the routing and diameter of the hydrogen transmission pipeline, and the installation location of the fuel cell module. Operating parameters include the rated hydrogen production rate of the methanol reforming hydrogen production unit, the buffer tank volume, the rated power and power response characteristics of the fuel cell stack, the operating temperature range of each device, and the start-stop control logic. The operating environment parameters include the ambient temperature, ambient pressure, wind speed and wind direction of the sea area where the ship is operating. Based on the above parameters, a three-dimensional geometric model including the hydrogen production module, hydrogen transmission pipeline, fuel cell module and ship cabin structure is constructed using three-dimensional modeling software. This three-dimensional geometric model provides accurate spatial topological relationships for subsequent finite element analysis, ensuring the geometric authenticity of the location of the leakage source, diffusion path and explosion shock wave propagation channel. In step (2), based on the three-dimensional geometric model constructed in step (1), a system simulation model is established to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system; Specifically, based on the working principle of the methanol reforming hydrogen production unit, a hydrogen production sub-model was constructed. This model established a dynamic correspondence between the rotational speed of the methanol supply pump, the reactor temperature, and the hydrogen production rate. That is, when the lifting load of the crane vessel increases, leading to an increase in power demand, the methanol supply increases, and the hydrogen production rate increases accordingly. Based on the power generation characteristics of the fuel cell stack, a hydrogen consumption sub-model was constructed. This model established a dynamic correspondence between the output power and the hydrogen consumption rate. That is, when the lifting load fluctuates, the fuel cell output power changes, and the hydrogen consumption rate changes synchronously. The hydrogen production sub-model and the hydrogen consumption sub-model were coupled through the buffer tank pressure balance equation. When the pressure in the buffer tank increases, the feedback regulation decreases the hydrogen production rate; when the pressure in the buffer tank decreases, the feedback regulation increases the hydrogen production rate. Thus, the time-varying relationship of the hydrogen production rate, hydrogen flow rate, and hydrogen consumption rate with the crane vessel's operating conditions was obtained. Through this step, the originally static hydrogen production and power generation system was transformed into a time-varying system that can reflect the dynamic fluctuations of the actual operating conditions, providing dynamic boundary conditions that truly reflect the system's operating status for subsequent leakage analysis. In step (3), the time-varying relationship obtained in step (2) is used as a dynamic boundary condition and coupled to the pre-constructed finite element analysis model. The location of the leak point and the leakage orifice diameter parameters are configured in the finite element analysis model. The location of the leak point is set according to the weak links in the hydrogen pipeline, such as flange connections, valve seals, or pipeline bends. The leakage orifice diameter is set to different levels such as micro-orifice leakage, small-hole leakage, or rupture leakage according to historical accident statistics or preset accident scenarios. When performing transient leakage and diffusion coupling analysis, the time-varying relationship is first configured as the dynamic boundary condition of the mass flow rate of the leak source in the finite element analysis model, that is, the mass flow rate of the leak source changes with the hydrogen production rate and the pressure of the buffer tank. The system dynamically adjusts according to time changes, and then generates discretized grid cells around the leak source and inside the ship's cabin. Within each grid cell, the properties of the hydrogen-air mixture are set, including physical parameters such as density, viscosity, and diffusion coefficient. Based on the mass flow rate of the leak source at each time step, the diffusion distribution of hydrogen in space is updated grid by grid, while the velocity distribution and pressure distribution of the flow field inside the cabin are also updated. The process is iterated until convergence, and the first analysis result of the concentration distribution field changing over time is output. This first analysis result can accurately present the dynamic evolution law of the entire process of hydrogen cloud formation, diffusion, accumulation and until stable distribution in the cabin space from the moment of leak onset. In step (4), the dangerous area where the hydrogen concentration reaches the explosion limit is identified based on the first analysis results. Specifically, the lower explosion limit threshold of hydrogen is set to 4% by volume and the upper explosion limit threshold is set to 75% by volume. The hydrogen concentration values ​​of each spatial node in the concentration distribution field are traversed, and the area covered by the spatial node whose hydrogen concentration value is between the lower explosion limit threshold and the upper explosion limit threshold is marked as the dangerous area. In the dangerous area, multiple candidate points are selected to form a set of trigger points based on the equipment layout and electrical equipment distribution. These candidate points include the location of non-explosion-proof electrical equipment, the tip of metal structural parts that may generate static electricity, the surface of high-temperature equipment, and other potential ignition source locations. Through this step, the continuously distributed concentration field is transformed into a discrete dangerous area identifier and further focused into a set of trigger points with actual ignition risk, providing clear candidate locations of ignition sources for subsequent explosion analysis. In step (5), each trigger point in the trigger point set is taken as the ignition start position in turn, and the explosion shock wave propagation analysis is performed in the finite element analysis model. First, in the finite element analysis model, the initial state of the hydrogen cloud at the trigger point is taken as the initial condition of the explosion. The combustion reaction parameters of the hydrogen-air mixture are set, including flame propagation speed, combustion heat release rate, and combustion product expansion coefficient. Then, a simulation environment for the propagation of the explosion shock wave between the compartment structures is constructed. In the simulation environment, the flame front propagation path and the interaction between the shock wave and the compartment structure wall are configured, including the reflection coefficient of the shock wave on the compartment wall, the diffraction effect at the corner of the compartment, and the propagation attenuation characteristics between different compartments. By simulating the propagation trajectory of the flame front and the pressure amplitude distribution of the shock wave after detonation at different trigger point positions, the pressure time history data of each unit of the ship compartment structure wall are extracted, and the second analysis result of the explosion pressure field distribution and structural response characteristics is generated. This second analysis result can comprehensively reflect the intensity and distribution law of the explosion shock wave on the ship structure under different ignition positions. In step (6), the peak pressure and structural deformation data of the ship's compartment structure under different explosion conditions are extracted based on the second analysis results. The safety level is evaluated based on the peak pressure and structural deformation data. Specifically, the peak pressure of each bulkhead unit is compared with the preset structural ultimate bearing pressure, and the structural deformation data is compared with the preset ultimate deformation. Based on the comparison results, the safety level is divided into no damage level, slight damage level, moderate damage level, and severe damage level. Corresponding protection optimization suggestions are generated for different safety levels. For example, for areas with moderate damage level, it is recommended to add explosion-proof walls or strengthen the bulkhead structure; for areas with severe damage level, it is recommended to re-plan the equipment layout or add pressure relief devices. The protection optimization suggestions are embedded in the safety analysis report to provide a quantitative basis for the safety design of the methanol-to-hydrogen crane ship.

[0020] The present invention further refines the specific implementation of the transient leakage and diffusion coupling analysis in step (3), especially for the leakage and diffusion process under complex multi-compartment structures.

[0021] In step (3), the methanol-to-hydrogen crane ship typically includes multiple functional compartments, including a hydrogen production compartment, a buffer tank compartment, a fuel cell compartment, and an electrical control compartment. The compartments are interconnected through ventilation ducts, cable penetrations, and personnel passages. When constructing the three-dimensional geometric model, the interconnection structure between the compartments is accurately modeled, including the diameter, length, and bend position of the ventilation ducts, the aperture size of the cable penetrations, and the opening status of the passage doors.

[0022] When configuring the time-varying relationship as the dynamic boundary condition for the mass flow rate of the leakage source, considering that the hydrogen production chamber is equipped with a methanol reforming hydrogen production unit, a hydrogen purification device, and supporting pipelines, according to the time-varying relationship output by the system simulation module, the hydrogen production rate fluctuates periodically with the change of the lifting load. When the crane ship is carrying out heavy lifting operations, the power demand increases sharply, the fuel cell output power increases, the hydrogen consumption rate increases, the buffer tank pressure decreases, and the hydrogen production system responds by increasing the hydrogen production rate, resulting in an increase in the pipeline pressure in the hydrogen production chamber. If a leak occurs at the pipeline flange at this time, the mass flow rate of the leakage source shows a dynamic change law of first rising rapidly and then stabilizing with the change of the buffer tank pressure.

[0023] When generating discretized mesh cells around the leak source and inside the ship's compartments, a local mesh refinement strategy was adopted for the area near the leak source. The mesh size was set to 5mm within a 1m radius of the leak orifice to accurately capture the initial mixing region of the leak jet. In the main compartment space, the mesh size was set to 50mm to control the total mesh size while ensuring computational accuracy. In connecting structures such as inside ventilation ducts, boundary layer meshes were used to accurately simulate the flow characteristics of airflow along the duct walls. When setting the hydrogen-air mixing medium properties within each mesh cell, the hydrogen diffusion coefficient in air was set to 6.1×10⁻⁶ based on ambient temperature and pressure. -5 m 2 / s, the dynamic viscosity of the hydrogen-air mixture is calculated using the following formula: In the formula, The dynamic viscosity of the mixture. Components The mass fraction, Components dynamic viscosity, The number of components; Based on the mass flow rate of the leak source at each time step, the diffusion distribution of hydrogen in space is updated grid-by-grid. In the initial stage of the leak, high-pressure hydrogen is ejected at high speed from the leak orifice, forming an underexpanded jet. The hydrogen concentration in the core region of the jet is close to 100%. As the jet is entrained and mixed with the surrounding air, the hydrogen concentration gradually decreases along the jet axis. When the hydrogen diffuses to the chamber wall, it is blocked by the wall, forming a backflow zone. Some hydrogen accumulates along the wall, forming a high-concentration region near the wall. At the same time, the velocity and pressure distribution of the flow field inside the chamber are updated. Considering the influence of the ventilation system's operating status on the chamber flow field, the air supply and exhaust vents of the ventilation system are applied as velocity boundary conditions in the model. In each time step, the velocity boundary at the leak orifice is first updated according to the mass flow rate of the leak source, then the flow field distribution is solved, and then the hydrogen component transport is solved based on the flow field results. This process is iterated until the residual in each time step is less than 1×10. -4 Then proceed to the next time step; Through the above-mentioned transient leakage and diffusion analysis of multi-compartment coupling, the output of the first analysis result not only includes the spatiotemporal distribution of hydrogen concentration inside each compartment, but also reflects the hydrogen migration process between compartments through the interconnected structure. For example, when hydrogen accumulates to a certain concentration in the hydrogen production compartment, some hydrogen may diffuse to the adjacent buffer tank through the ventilation duct, causing the explosion hazard area to expand from a single compartment to multiple compartments. This analysis result can accurately identify the spatial distribution of the hazard area under the multi-compartment structure, providing a complete data foundation for subsequent hazard area identification and trigger point set construction.

[0024] like Figure 2 As shown, the present invention also provides a hydrogen leak explosion safety analysis system based on finite element analysis, which is used to perform the above-described method; the system specifically includes: The model building module first obtains the structural parameters of the methanol-to-hydrogen crane vessel, the operating parameters of the methanol-to-hydrogen power generation system, and the operating environment parameters. In specific implementation, the structural parameters are obtained by reading the STEP format model file exported from the ship's 3D design software. This model file contains information on the hull structure, compartment division, equipment installation locations, and pipeline layout. The operating parameters are obtained by exporting the operating parameter table from the PLC control system of the methanol-to-hydrogen power generation system, including a rated hydrogen production rate of 50 Nm³ for the methanol reforming hydrogen production unit. 3 / h, buffer tank volume 2m 3 The rated power of the fuel cell stack is 100kW. The operating environment parameters are set according to the meteorological data of the sea area where the ship is operating, including an ambient temperature of 25℃, an ambient pressure of 101325Pa, a wind speed of 5m / s, and a wind direction along the bow of the ship. Based on the above parameters, the model building module constructs a three-dimensional geometric model including the hydrogen production module, hydrogen transmission pipeline, fuel cell module and ship cabin structure, and outputs the model to the system simulation module and the leakage diffusion analysis module. After receiving the 3D geometric model, the system simulation module establishes a system simulation model based on this model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system. The system simulation module includes a hydrogen production sub-model unit, a hydrogen consumption sub-model unit, and a coupling unit. The hydrogen production sub-model unit constructs a hydrogen production sub-model based on the working principle of the methanol reforming hydrogen production unit. This model correlates the opening of the flow control valve of the methanol supply pump with the hydrogen production rate. The hydrogen production rate increases linearly with the increase of methanol supply. It also considers the influence of reaction temperature on hydrogen production efficiency; when the reaction temperature is below 200℃, the hydrogen production efficiency decreases. The hydrogen consumption sub-model unit constructs a hydrogen consumption sub-model based on the power generation characteristics of the fuel cell stack. This model correlates the fuel cell output power with the hydrogen consumption rate; each kW of output power consumes 0.07 Nm of hydrogen. 3 / h, the coupling unit couples the hydrogen production sub-model and the hydrogen consumption sub-model through the buffer tank pressure balance equation. The buffer tank pressure change rate is equal to the hydrogen inlet rate minus the hydrogen outlet rate divided by the product of the buffer tank volume and the gas constant. According to the operating conditions of the crane ship, when the crane load jumps from 50kW to 100kW, the hydrogen consumption rate output by the hydrogen consumption sub-model increases accordingly, and the buffer tank pressure decreases. The coupling unit feeds back the pressure drop signal to the hydrogen production sub-model, and the hydrogen production sub-model adjusts the methanol supply to increase the hydrogen production rate. Finally, the dynamic change curves of the hydrogen production rate, hydrogen flow rate and hydrogen consumption rate over time are obtained. The leakage and diffusion analysis module receives the time-varying relationship output by the system simulation module and the three-dimensional geometric model output by the model building module. It couples the time-varying relationship as a dynamic boundary condition to the pre-built finite element analysis model. The module includes boundary configuration elements, mesh generation elements, and transient update elements. In the finite element analysis model, the boundary configuration element configures the time-varying relationship as a dynamic boundary condition for the mass flow rate of the leakage source; that is, the mass flow rate of the leakage source dynamically adjusts with the real-time changes in the hydrogen production rate and the buffer tank pressure. The mesh generation element generates discretized data around the leakage source and within the ship's cabin space. The grid cell employs a hexahedral-dominated gridding strategy, generating a triangular prism boundary layer grid around the leak source to accurately capture near-wall flow, and a tetrahedral grid in the main cabin space to ensure grid quality. Within each grid cell, the properties of the hydrogen-air mixture are defined, including density, dynamic viscosity, specific heat capacity, and thermal conductivity. The transient update cell updates the hydrogen diffusion distribution in space grid by grid according to the mass flow rate of the leak source at each time step, while simultaneously updating the velocity and pressure distribution of the flow field inside the cabin. Iterates until convergence and outputs the first analysis result of the concentration distribution field changing over time. The hazardous area identification module receives the first analysis result and identifies hazardous areas where the hydrogen concentration has reached the explosion limit. The hazardous area identification module first sets the lower explosion limit threshold of hydrogen to 4% by volume and the upper explosion limit threshold to 75% by volume. Then, it traverses the hydrogen concentration values ​​of each spatial node in the concentration distribution field and marks the area covered by the spatial node whose hydrogen concentration value is between the lower explosion limit threshold and the upper explosion limit threshold as a hazardous area. The hazardous area identification module further selects multiple candidate points to form a trigger point set within the hazardous area based on the equipment layout location and electrical equipment distribution. The selection rules include priority for non-explosion-proof electrical equipment, priority for high-temperature surfaces, and priority for metal structure tips. The explosion analysis module receives the trigger point set and the first analysis result, and sequentially uses each trigger point in the trigger point set as the ignition start position. It then performs explosion shock wave propagation analysis in the finite element analysis model. The explosion analysis module includes an initial condition configuration unit, a propagation simulation unit, and a data extraction unit. In the finite element analysis model, the initial condition configuration unit uses the initial state of the hydrogen cloud at the trigger point location as the initial explosion condition, and sets the combustion reaction parameters of the hydrogen-air mixture, including a laminar flame velocity of 2.7 m / s and a heat of combustion of 1.2 × 10⁶ J / kg. The thermal expansion coefficient of the combustion products is 7. The propagation simulation unit constructs a simulated environment for the propagation of the explosion shock wave between the compartment structures. In the simulation environment, the propagation path of the flame front and the interaction between the shock wave and the compartment structure wall are configured. When the shock wave propagates to the compartment wall, it is reflected, and the reflected pressure can reach twice the incident pressure. When the shock wave propagates to the corner of the compartment, it is diffracted. The pressure amplitude of the diffracted wave is attenuated, but the range of action is expanded. The data extraction unit extracts the pressure time history data of each unit of the ship's compartment structure wall and generates the second analysis results of the explosion pressure field distribution and structural response characteristics. The assessment report generation module receives the second analysis results, extracts the peak pressure and structural deformation data of the ship's compartment structure under different explosion conditions, and assesses the safety level based on the peak pressure and structural deformation data. The module compares the peak pressure of each bulkhead unit with the preset structural ultimate bearing pressure (set to 0.5 MPa) and the structural deformation data with the preset ultimate deformation (set to 10 mm). Based on the comparison results, the safety level is divided into no-damage, minor-damage, moderate-damage, and severe-damage levels. For areas assessed as moderate-damage or above, the assessment report generation module generates corresponding protection optimization suggestions, such as adding a 10 mm thick explosion-proof partition between the hydrogen production compartment and the fuel cell compartment, or adding a 0.5 m² area partition on the top of the compartment. 2 The explosion vent is assessed, and the assessment report generation module integrates the above assessment results and optimization suggestions to generate a safety analysis report, which is then output to the user terminal for designers to refer to.

[0025] Through the collaborative work of the various modules of the above system, this invention realizes fully automated analysis from parameter input to safety report output. The data transmission and interaction logic between the modules is clear, and the system execution actions are coherent, enabling efficient and detailed assessment of the safety of hydrogen leakage and explosion on methanol-to-hydrogen crane ships.

Claims

1. A method for analyzing the safety of hydrogen leak explosions based on finite element analysis, characterized in that, Includes the following steps: Step (1) Obtain the structural parameters of the methanol-to-hydrogen crane ship, the operating parameters of the methanol-to-hydrogen power generation system, and the operating environment parameters, and construct a three-dimensional geometric model including the hydrogen production module, hydrogen transmission pipeline, fuel cell module, and ship cabin structure. Step (2) Based on the three-dimensional geometric model, establish a system simulation model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system, and determine the time-varying relationship between the hydrogen production rate, hydrogen flow rate and hydrogen consumption rate according to the operating conditions of the crane ship. Step (3) uses the time-varying relationship as a dynamic boundary condition and couples it to the pre-constructed finite element analysis model. In the finite element analysis model, the location of the leakage point and the leakage aperture parameters are configured. Transient leakage and diffusion coupling analysis is performed to obtain the first analysis result of the change of hydrogen concentration distribution field in the ship's cabin and surrounding space over time. Step (4) Identify the dangerous area where the hydrogen concentration reaches the explosion limit based on the first analysis results, and construct a set of trigger points within the dangerous area to characterize the location of the ignition source; Step (5) Take each trigger point in the trigger point set as the ignition start position in sequence, and perform the explosion shock wave propagation analysis in the finite element analysis model to obtain the second analysis results of the explosion pressure field distribution and structural response characteristics; Step (6) Extract the peak pressure and structural deformation data of the ship's compartment structure under different explosion conditions based on the second analysis results, evaluate the safety level based on the peak pressure and structural deformation data, and generate a safety analysis report.

2. The method for hydrogen leak explosion safety analysis based on finite element analysis according to claim 1, characterized in that, Step (2) involves establishing a system simulation model to describe the dynamic response characteristics of the methanol-to-hydrogen power generation system, which specifically includes: Based on the working principle of the methanol reforming hydrogen production unit, a hydrogen production sub-model is constructed. The hydrogen production sub-model is used to characterize the dynamic relationship between the hydrogen production rate and the methanol supply and reaction temperature. Based on the power generation characteristics of fuel cell stacks, a hydrogen consumption sub-model is constructed. The hydrogen consumption sub-model is used to characterize the dynamic relationship between hydrogen consumption rate and output power and stack efficiency. By coupling the hydrogen production sub-model and the hydrogen consumption sub-model through the buffer tank pressure balance equation, the time-varying relationships of hydrogen production rate, hydrogen flow rate, and hydrogen consumption rate are obtained.

3. The method for hydrogen leak explosion safety analysis based on finite element analysis according to claim 1, characterized in that, The transient leakage and diffusion coupling analysis described in step (3) specifically includes: In the finite element analysis model, the time-varying relationship is configured as the dynamic boundary condition of the mass flow rate of the leakage source; Discretized grid cells are generated around the leak source and inside the ship's cabins, and the properties of the hydrogen-air mixture are set within each grid cell. Based on the mass flow rate of the leakage source at each time step, the diffusion distribution of hydrogen in space is updated grid by grid, while the velocity distribution and pressure distribution of the internal flow field of the cabin are also updated. The process is iterated until convergence, and the first analysis result of the concentration distribution field changing with time is output.

4. The method for hydrogen leak explosion safety analysis based on finite element analysis according to claim 1, characterized in that, The identification of hazardous areas where the hydrogen concentration reaches the explosion limit in step (4) specifically includes: Set the lower and upper explosion limits for hydrogen; Traverse the hydrogen concentration values ​​of each spatial node in the concentration distribution field, and mark the area covered by the spatial node whose hydrogen concentration value is between the lower explosion limit threshold and the upper explosion limit threshold as the danger zone; Within the hazardous area, multiple candidate points are selected to form a set of trigger points based on the location of the equipment and the distribution of electrical equipment.

5. The method for analyzing the safety of hydrogen leak explosions based on finite element analysis according to claim 1, characterized in that, The specific steps in step (5) to perform the explosion shock wave propagation analysis include: In the finite element analysis model, the initial state of the hydrogen cloud at the trigger point is taken as the initial condition of the explosion, and the combustion reaction parameters of the hydrogen-air mixture are set. Construct a simulated environment for the propagation of explosion shock waves between compartment structures, and configure the propagation path of the flame front and the interaction between the shock wave and the walls of the compartment structure in the simulated environment; Pressure time history data of each unit of the ship's cabin structural wall are extracted to generate a second analysis result of the explosion pressure field distribution and structural response characteristics.

6. The method for hydrogen leak explosion safety analysis based on finite element analysis according to claim 1, characterized in that, The assessment of security level in step (6) specifically includes: The peak pressure is compared with the preset structural ultimate bearing pressure, and the structural deformation data is compared with the preset ultimate deformation. Based on the comparison results, the security levels are divided into no-damage level, minor damage level, moderate damage level, and severe damage level. For different security levels, corresponding protection optimization suggestions are generated and embedded into the security analysis report.

7. A hydrogen leak explosion safety analysis system based on finite element analysis, characterized in that, The method for performing any one of claims 1-6 includes a model building module, a system simulation module, a leakage and diffusion analysis module, a hazardous area identification module, an explosion analysis module, and an assessment report generation module.

8. The hydrogen leak explosion safety analysis system based on finite element analysis according to claim 7, characterized in that, The system simulation module includes a hydrogen production sub-model unit, a hydrogen consumption sub-model unit, and a coupling unit.

9. The hydrogen leak explosion safety analysis system based on finite element analysis according to claim 7, characterized in that, The leakage and diffusion analysis module includes a boundary configuration unit, a mesh generation unit, and a transient update unit.

10. The hydrogen leak explosion safety analysis system based on finite element analysis according to claim 7, characterized in that, The explosion analysis module includes an initial condition configuration unit, a propagation simulation unit, and a data extraction unit.

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