Method for evaluating effectiveness and reliability of fireproof coating of atmospheric storage tank area

Abstract

The application relates to a method for evaluating the effectiveness and reliability of a fireproof coating of an atmospheric storage tank area, and relates to the technical field of storage tank coating evaluation.The application constructs two working conditions, i.e., a working condition with a fireproof coating and a working condition without the fireproof coating, through thermal and force coupling simulation, and comprehensively analyzes numerical coupling under wind and non-wind conditions.A curve of tank wall temperature changing with time is obtained through simulation, a failure time is determined, and a corresponding failure time calculation formula is fitted, so that the protection effect of the fireproof coating is further quantitatively analyzed, an effective time formula of an atmospheric storage tank with the fireproof coating under the action of a wind speed and single pool fire thermal radiation is obtained, the effectiveness time gain can be accurately calculated by directly inputting specific wind speed, spacing and volume parameters, the effectiveness time gain of the coating under different working conditions under the wind and non-wind states can be accurately quantified without repeatedly modeling and simulating, the application scope is wide, and the output result is accurate.

Description

Technical Field

[0001] This invention relates to the field of tank coating evaluation technology, specifically a method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank areas. Background Technology

[0002] When a tank fire occurs, the temperature field of adjacent tanks will rise unevenly due to wind speed and heat radiation. This will cause dynamic evolution of the stress and strain of the tank wall. Since the yield strength of the tank material decreases with increasing temperature, when the stress on the tank wall exceeds the yield threshold of the material under high temperature conditions, the tank will fail. In large-scale chemical tank clusters, the installation of fireproof coatings is a key means of preventing and controlling domino accidents. Its core functions include reducing the risk of chain reaction of accidents, mitigating the damage caused by the disaster, and delaying the failure process of the tank structure.

[0003] Chinese invention patent CN112580180A discloses a method for evaluating the performance of safety barriers in tank farm fires. Using numerical simulation, it assesses whether the arrangement of safety barriers such as fire-resistant coatings and cooling water sprays at different safety distances within the tank farm, considering the significant heat radiation generated by a full-surface tank fire in any tank within the farm, can provide sufficient and effective protection to adjacent tanks. This invention innovatively uses numerical simulation to consider the safety of various targets at the scene of a tank farm fire, quantifying the performance of adjacent tank safety barriers. This makes the evaluation results more specific and intuitive, serving as a practical technical means for evaluating the performance of safety barriers in tank farms, with tangible application value. A single failure time point is determined through heat conduction calculations and stress analysis, and then compared with the fire rescue time for assessment. Its calculations are primarily based on the Mudan model and its derivative formulas. This model typically assumes a windless or weak wind environment, simplifies the flame as a vertical cylinder, and focuses on calculating the net heat flux of the target surface. Although the flame tilt angle is mentioned, its specific heat radiation calculation formula does not explicitly introduce wind speed variables or flame tilt angle corrections, but relies on geometric distance and flame height. It is a relatively static calculation method that cannot accurately reflect the changes in flame shape and heat radiation transfer path caused by strong winds. Furthermore, it is based on deterministic simulation, and in reality, environmental parameters fluctuate randomly. Deterministic models cannot quantify the risks brought about by such fluctuations. Each assessment requires remodeling, meshing, and iterative calculation simulation, which has a delay. When facing large-scale tank areas and multiple operating conditions, the calculation cost is extremely high and the efficiency is low. Moreover, it can only analyze whether it can hold out until rescue arrives, without accurately analyzing the effectiveness improvement data of fireproof coatings.

[0004] The information disclosed in the background section is only intended to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to provide a method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank areas, in order to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank farms, comprising the following steps:

[0008] S1. Construct a pool fire model and generate flame heights under windless and windy conditions, respectively.

[0009] S2. Based on the flame height parameter, the flame field distribution in the tank area is simulated and analyzed using twin simulation;

[0010] S3. Numerical simulation analysis of the thermal response process of the atmospheric pressure storage tank with fireproof coating under different wind speeds, and stress simulation analysis to obtain the total deformation, equivalent stress and thermal strain characteristics of the atmospheric pressure storage tank.

[0011] S4. Based on the equivalent stress comparison of the yield strength of the atmospheric pressure storage tank at the corresponding temperature, the failure time of the atmospheric pressure storage tank is determined by the intersection point of the stress change curve of the atmospheric pressure storage tank under thermal response and the material yield strength curve. The failure time of the atmospheric pressure storage tank is the moment of structural failure.

[0012] S5. Based on the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank, a correlation analysis is performed to generate a failure time assessment formula. Based on the principles of computational fluid dynamics, the fire process of the atmospheric pressure storage tank without fireproof coating is simulated through a simulation platform.

[0013] S6. Based on the heat radiation flux received by atmospheric pressure storage tanks with and without fireproof coatings, conduct correlation analysis to quantitatively analyze the protective effect of fireproof coatings.

[0014] S7. Using the Monte Carlo simulation method, random samples are generated based on the normal distribution to evaluate the reliability of the fireproof coating.

[0015] Furthermore, a pool fire model was constructed, and the flame height was calculated based on the Thomas formula. Twin simulation was used to simulate and analyze the flame thermal field distribution under the pool fire condition in the tank area. The simulation analysis included: geometric model construction and mesh generation, parameter calibration and fire source condition settings, flame tilt angle analysis, detector spatial arrangement, and thermal response process analysis.

[0016] Furthermore, the formula used for flame tilt angle analysis is as follows: ,in, For dimensionless wind speed, To determine the flame tilt angle, the thermal response process analysis was conducted using a numerical simulation based on an empty tank model to analyze and obtain the thermal radiation released during the fire.

[0017] Furthermore, the atmospheric pressure storage tank uses Q345 steel as the main material for the tank body. The radius of curvature of the dome structure is taken as 1.2 times the tank diameter. Four tank spacing conditions are set: 0.4DL, 0.6DL, 0.8DL and 1.0DL, where DL is the tank diameter. The fireproof coating is a lightweight silicate-based coating with a thickness of 50mm. Based on the cavity radiation theory, a thermodynamic response model of the atmospheric pressure storage tank is established through software to obtain the temperature field change diagram of the target storage tank ST2 affected by the accident storage tank ST1. The temperature field change diagram is used to reflect the relationship between the highest temperature of the target storage tank ST2 and the change over time.

[0018] Furthermore, a correlation analysis was conducted based on the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank to generate a failure time assessment formula. The formula used is as follows:

[0019]

[0020] Where a, b, and c are coefficients; I is the thermal radiation intensity; V is the volume of the atmospheric pressure storage tank; and ttf is the failure time of the atmospheric pressure storage tank. A value of 1000m³ is selected. 3 3000m 3 5000m 3 These three atmospheric pressure storage tanks of different volumes were used as the analysis objects. The target storage tank ST2 under the fireproof coating was simulated under different spacing and wind speed conditions. The failure time curves of the target storage tank ST2 with fireproof coating under different spacing and wind speed were plotted. The values ​​of a, b, and c were obtained through numerical simulation.

[0021] Furthermore, based on the principles of computational fluid dynamics, a fire process simulation of an atmospheric pressure storage tank without fire-retardant coating was conducted using a simulation platform. The target atmospheric pressure storage tank's thermal radiation value without fire-retardant coating was generated by fitting wind speed, thermal radiation flux, and tank spacing. The formula used is as follows:

[0022]

[0023] in, The value represents the thermal radiation received by the target storage tank without a fire-retardant coating. This refers to wind speed under natural conditions. Given the distance between the accident tank ST1 and the target tank ST2, the failure time of the unfire-retardant atmospheric pressure tank is obtained based on the formula for the failure time of an unfire-retardant atmospheric pressure tank under different wind speeds. The formula used is:

[0024]

[0025] V is the volume of the target storage tank. It is the failure time of the target storage tank without fireproof coating.

[0026] Furthermore, by comparing the heat radiation flux received by atmospheric pressure storage tanks with and without fire-retardant coatings, the protective effect of the fire-retardant coating is quantitatively analyzed. The formula used is:

[0027]

[0028] in, The effective time for an atmospheric pressure storage tank with a fire-retardant coating to be subjected to wind speed and thermal radiation from a single pool is defined as the time it takes for the tank to be heated. The intensity of heat radiation from a pool fire experienced by the target storage tank under the fire-retardant coating. V represents the intensity of heat radiation from a pool fire experienced by the target storage tank without a fire-retardant coating, and V is the volume of the storage tank at atmospheric pressure. ttf2 represents the time probability of effectiveness; ttf2 represents the failure time of an atmospheric pressure storage tank without fire-retardant coating.

[0029] Compared with the prior art, the beneficial effects of the present invention are:

[0030] Two operating conditions—with and without fire-retardant coating—were constructed through thermal and mechanical coupling simulations. Numerical coupling under windy and windless conditions was comprehensively analyzed. The tank wall temperature change curve over time was obtained through simulation to determine the failure time. The failure times under the coated and uncoated conditions were recorded, and corresponding failure time calculation formulas were fitted to quantify the protective effect of the fire-retardant coating. The effective time formula for an atmospheric pressure storage tank with a fire-retardant coating under wind speed and single-pool thermal radiation was obtained. By directly substituting specific wind speed, spacing, and volume parameters, the effective time gain can be accurately calculated without repeated modeling and simulation. This method achieves accurate quantification of the coating's effective time gain under different operating conditions with and without wind, with a wide range of applications and accurate output results. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the overall method flow of the present invention;

[0032] Figure 2 This is a schematic diagram of the geometric modeling of the tank area of ​​the present invention;

[0033] Figure 3 This is a schematic diagram of the flame temperature slice when the wind speed is 0 m / s according to the present invention;

[0034] Figure 4 This is a schematic diagram of the flame temperature slice at a wind speed of 2 m / s according to the present invention;

[0035] Figure 5 This is a schematic diagram of the flame temperature slice at a wind speed of 4 m / s according to the present invention;

[0036] Figure 6 This is a schematic diagram of the flame temperature slice at a wind speed of 6 m / s according to the present invention;

[0037] Figure 7 This is a schematic diagram of the flame temperature slice at a wind speed of 8 m / s according to the present invention;

[0038] Figure 8 This is a thermal response characteristic diagram of the storage tank of the present invention;

[0039] Figure 9 This is a temperature distribution diagram of storage tank ST2 when the wind speed is 0 m / s according to the present invention;

[0040] Figure 10 This is a temperature distribution diagram of storage tank ST2 when the wind speed is 2m / s according to the present invention;

[0041] Figure 11 This is a temperature distribution diagram of storage tank ST2 at a wind speed of 4 m / s according to the present invention;

[0042] Figure 12 This is a temperature distribution diagram of storage tank ST2 at a wind speed of 6 m / s according to the present invention;

[0043] Figure 13 This is a temperature distribution diagram of storage tank ST2 at a wind speed of 8 m / s according to the present invention;

[0044] Figure 14 This is a graph showing the relationship between the highest temperature and time of storage tank ST2 in this invention.

[0045] Figure 15 This is a diagram showing the total deformation distribution of storage tank ST2 at 8 m / s according to the present invention;

[0046] Figure 16 This is the equivalent stress distribution diagram of storage tank ST2 at 8 m / s according to the present invention;

[0047] Figure 17 This is a thermal strain distribution diagram of storage tank ST2 at 8 m / s according to the present invention;

[0048] Figure 18 This is a graph showing the changes in maximum temperature, stress, and yield strength of storage tank ST2 at 8 m / s according to the present invention.

[0049] Figure 19 This is a failure probability diagram of an atmospheric pressure storage tank under the fire-retardant coating of the present invention;

[0050] Figure 20 This is a failure probability diagram of an atmospheric pressure storage tank without a fireproof coating according to the present invention. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0052] It should be noted that, unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0053] Example:

[0054] Please see Figure 1 The present invention provides a technical solution:

[0055] A method for evaluating the effectiveness and reliability of fire-retardant coatings in atmospheric pressure storage tank areas is disclosed. Effectiveness is selected as the evaluation index for analyzing the fire-retardant coatings. Lightweight silicate-based fire-retardant coatings are chosen as the research object. This invention is not limited to lightweight silicate-based fire-retardant coatings but can also be applied to other fire-retardant coatings. Specific steps include:

[0056] Step 1: Construct a pool fire model and generate flame heights under windless and windy conditions respectively;

[0057] Numerical simulations of pool fires commonly employ solid flame models, simplifying the flame into a cylindrical luminous body whose height is determined by the distribution of carbon soot particles produced during combustion. In the theoretical calculation of the height of this cylindrical flame, commonly used empirical models include the Brötz formula, the Heaskestad relation, the Thomas theoretical model, and the Moorhouse empirical equation. Data analysis shows that the prediction results of the Thomas formula have a high degree of agreement with the measured flame height. Therefore, this invention calculates the flame height based on the Thomas formula, using the following formula:

[0058] In windless conditions:

[0059]

[0060] In windy conditions:

[0061]

[0062] H is the flame height, and D is the diameter of the fire pit. The mass combustion rate of the flammable liquid. For ambient air density, Let g be the dimensionless wind speed and g be the acceleration due to gravity, where:

[0063] For wind speed, This refers to the ambient air density.

[0064] The mass loss rate during pool fire combustion depends on multiple factors, including fuel characteristics, combustion area, and environmental conditions. The ratio of the maximum combustion rate to the steady-state combustion rate directly affects the flame's thermal radiation characteristics. Based on Babrauskas theory, a predictive model for the combustion rate of combustible liquids is established for analysis.

[0065] For mass combustion rate, The maximum mass combustion rate is given by k, where k is the flame decay coefficient. The average ray length correction factor is given, D is the pool fire diameter, and gasoline is the primary analytical object, with the maximum mass combustion rate as the maximum mass combustion rate. It is 0.055 kg / (m 2 .s), It is 2.1m -1 .

[0066] Step 2: Based on the flame height parameter, simulate and analyze the flame field distribution in the tank area using twin simulation;

[0067] The Pyrosim platform was used to conduct twin simulation analysis of the flame thermal field distribution under the condition of a tank area fire. The simulation analysis included: geometric model construction and mesh generation, parameter calibration and fire source condition setting, flame tilt angle analysis, detector spatial arrangement, and thermal response process analysis.

[0068] Geometric model construction and mesh generation were performed, establishing numerical models of three different volumes: 1000 m³, 3000 m³, and 5000 m³ for vertical fixed-roof gasoline storage tanks. Pyrosim software has limitations in curved surface geometry modeling; therefore, multi-cubic-pole modules were used for geometric equivalent modeling of the vertical cylindrical atmospheric pressure storage tank. In the numerical simulation, smaller mesh sizes can improve simulation accuracy but significantly increase computational memory consumption and may even lead to convergence issues during iteration. Therefore, cubic elements with a side length of 0.5 m were used as the computational mesh, referencing... Figure 2 Finally, a three-dimensional geometric model of the storage tank was established.

[0069] Parameter calibration and ignition source condition settings: the ground boundary condition is defined as INERT, and the boundary conditions of the remaining computational domain are set to OPEN. The environmental parameters are set as follows: the ambient temperature is kept constant at 20℃, the atmospheric pressure follows the standard value, five wind speed conditions in the range of 0-8m / s are investigated, with an interval of 2m / s, the numerical simulation time span is set to 100 seconds, and the ignition source is located on the upper surface area of ​​the liquid surface inside the storage tank.

[0070] The flame height of a fire in an atmospheric pressure storage tank varies depending on the wind speed. Table 1 shows the flame height of a tank fire under wind speeds of 0 m / s, 2 m / s, 4 m / s, 6 m / s, and 8 m / s, calculated using Thomas's formula.

[0071] Table 1: Flame Height of Atmospheric Pressure Tank Fires under Different Wind Speeds

[0072] Referring to Table 2, under windy conditions, the flame may not remain vertical. The formula used for flame tilt angle analysis is as follows: ,in, For dimensionless wind speed, The angle of the flame.

[0073] Table 2: Flame Inclination Angle and Related Parameters of Atmospheric Pressure Storage Tank Fires under Different Wind Speeds

[0074] To monitor the spatial distribution characteristics of flame temperature, a layered temperature measurement scheme is adopted for the detector spatial arrangement: multiple temperature sensor arrays are vertically arranged along the top of the tank to acquire flame thermodynamic parameters at different elevations. Five measurement planes are set in the liquid surface area, with the vertical distance between each plane and the flame front increasing in increments of 4 meters. The horizontal spacing between detectors within the same plane is 3 meters. This high-density detector array layout enables detailed and comprehensive recording of flame temperature and its dynamic changes. Based on temperature measurement data from the stable combustion phase... Figure 3-7 Table 3 shows the flame slice temperature distribution of the storage tank at wind speeds of 0, 2, 4, 6, and 8 m / s, respectively. The table also shows the flame characteristic temperature values ​​of atmospheric pressure storage tank fires under different wind speed conditions.

[0075] Table 3: Flame Temperature of Atmospheric Pressure Storage Tanks at Different Wind Velocities

[0076] Thermal response process analysis reveals that heat conduction, heat convection, and heat radiation are the three basic heat transfer mechanisms. In the scenario of a fire in an atmospheric pressure storage tank, the energy released by the fire is mainly transferred through heat radiation. As the temperature of the adjacent tank gradually increases, the tank wall will radiate heat to the surrounding environment in the form of heat radiation. At the same time, due to the temperature gradient between the tank and the environment, heat will be transferred from the high-temperature area to the low-temperature area through heat conduction. In addition, the heat flux absorbed by the adjacent tank will also exchange energy with the surrounding environment through convection heat transfer.

[0077] The formula for calculating the heat radiation from the fire source received by the adjacent storage tank is as follows:

[0078] In windless conditions:

[0079]

[0080] in: .

[0081] In windy conditions:

[0082]

[0083] I represents the intensity of thermal radiation received by the storage tank; E represents the intensity of thermal radiation received by the burning tank. For view factors; The absorptivity is the surface absorption rate of the tank wall, with a value of 0.6 for the tank wall. Indicates atmospheric projection rate; Surface emissivity; when the object is considered a blackbody =1; The flame temperature of a pool fire; The ambient reference temperature is 0℃. , These are the horizontal and vertical view factors, respectively; d represents the horizontal distance; S is the ratio of the horizontal spacing to the pool fire radius; A, B, and C are calculation coefficients; h is the ratio of the tank height to the pool fire radius; H is the pool fire flame height; L is the distance between the pool fire flame center and the target; and D is the pool fire diameter. The tilt angle.

[0084] Reference Figure 8 During the thermal response process analysis, numerical simulation was performed based on an empty tank model. When the target storage tank is subjected to thermal radiation, the fireproof coating effectively delays the failure process of the storage tank by reducing the thermal radiation energy absorbed by the tank wall, thereby determining its effectiveness time.

[0085] Step 3: For atmospheric pressure storage tanks with fireproof coatings, numerical simulation analysis of the thermal response process is performed under different wind speeds, and stress simulation analysis is performed to obtain the total deformation, equivalent stress and thermal strain characteristics of the atmospheric pressure storage tank.

[0086] The atmospheric pressure storage tank uses Q345 steel as the main material for the tank body. The radius of curvature of the dome structure is taken as 1.2 times the tank diameter. Four tank spacing conditions are set: 0.4DL, 0.6DL, 0.8DL, and 1.0DL, where DL is the tank diameter. The fireproof coating is a lightweight silicate-based coating with a thickness of 50mm. When constructing the numerical model of the thermal protection performance of the fireproof coating, the analysis is based on the following assumptions: the tank failure simulation condition is set as a full liquid surface pool fire state; the fireproof coating maintains stable performance and does not undergo parameter degradation in variable wind speed and thermal radiation environments; the influence of contact thermal resistance between the coating and the tank substrate is ignored.

[0087] Based on cavity radiation theory, a thermodynamic response model of an atmospheric pressure storage tank was established using Ansys Fluent software. The temperature dependence of the steel's thermal properties was ignored. A solid flame model was adopted, and the maximum combustion temperature was given. It was assumed that the burning tank had a uniform temperature field distribution, and that the temperature field of adjacent tanks changed dynamically under the coupling effect of wind and thermal radiation. Simultaneously, thermal convection and radiative heat transfer with the surrounding medium were considered. The calculation parameters were set as follows: atmospheric temperature 293 K, radiation absorptivity 0.28, convective heat transfer coefficient of 5, and gravitational acceleration of the standard value of 9.8 m / s². Environmental temperature boundary conditions were applied in the spatial domain, and adiabatic and zero-displacement constraints were applied to the bottom surface of the tank. The stress field was solved using a transient dynamics method. The total simulation time was 1200 seconds, and a time step of 5 seconds was set to maintain calculation accuracy and synchronize with the thermal analysis.

[0088] During a fire, the energy released is mainly transferred to adjacent storage tanks via radiation. Its heat transfer efficiency is regulated by factors such as the geometric characteristics of the fire source, including flame height, radiation direction angle, and relative position between tanks. Due to the uneven spatial distribution of radiation flux, the heat flux density absorbed at different locations on the surface of the heated storage tank varies significantly, resulting in a clear gradient distribution of the tank wall temperature field. As the heat load continues, the tank structure generates thermal stress due to the temperature rise. At the same time, the mechanical properties of the steel deteriorate due to the high temperature, eventually leading to structural deformation. The application of fire-retardant coatings can significantly improve the fire resistance of the storage tank and effectively delay the damage process of the tank structure caused by high temperature. Under different wind speeds, the flame temperature increases with the increase of wind speed, thereby forcing the target storage tank to shorten its failure time.

[0089] This invention uses Ansys Fluent software to numerically simulate and analyze the thermal response process of an atmospheric pressure storage tank with a fire-retardant coating under different wind speeds. Taking a 5000 cubic meter atmospheric pressure storage tank as the combustion medium, with gasoline as the combustion medium, the distance between the accident storage tank ST1 and the target storage tank ST2 is set to 0.4DL. For different wind speed conditions, reference is made... Figure 9-13 The temperature distribution characteristics of the target storage tank after being subjected to thermal radiation under the action of physical safety barriers were analyzed, with reference to Figure 14A temperature field change diagram of the target storage tank ST2 affected by the accident storage tank ST1 is obtained. This temperature field change diagram is used to reflect the relationship between the highest temperature of the target storage tank ST2 and time. (Refer to...) Figure 15-17 The figures represent the total deformation distribution, equivalent stress distribution, and thermal strain distribution of the storage tank at a wind speed of 8 m / s. As the wind speed increases, the temperature received by the target storage tank ST2 also increases. The highest temperature of the tank is at the top, and the temperature spreads downwards from the top, gradually decreasing from the front to the sides. Due to the continuous influence of the wind speed and thermal radiation from the accident storage tank ST1, the temperature rise rate of the target storage tank ST2 continuously accelerates, eventually reaching its peak temperature. The temperature rise rate of the target storage tank with the fire-retardant coating at the same wind speed is significantly lower than that of the target storage tank without the fire-retardant coating. When the wind speed is 0 m / s, the target storage tank ST2 with the fire-retardant coating reaches its highest temperature in approximately 558 s, while the target storage tank ST2 without the fire-retardant coating reaches its highest temperature in approximately 454 s. When the wind speed reaches 8 m / s, the target storage tank ST2 with the fire-retardant coating reaches its highest temperature in approximately 347 s, while the target storage tank ST2 without the fire-retardant coating reaches its highest temperature in 284 s.

[0090] To analyze the failure mechanism of the target storage tank under the influence of wind speed and single-pool thermal radiation, its stress distribution characteristics need to be analyzed. Under the influence of thermal expansion and contraction, the tank wall of the atmospheric pressure storage tank will experience thermal stress due to temperature changes. The non-uniform distribution of the temperature field of the tank wall will further cause uneven stress distribution, thereby inducing stress deformation and potentially leading to tank failure. Therefore, it is necessary to obtain the total deformation, equivalent stress, and thermal strain characteristics under different wind speeds through software simulation. Under the influence of wind speed and thermal radiation, the target storage tank ST2 with a fireproof coating experiences greater deformation as the wind speed increases. The deformation amplitude decreases as the height of the tank decreases, and the deformation trend spreads to both sides. The maximum deformation of the tank occurs at the top of the wall. Due to the constraint of the bottom of the tank, the elastic deformation capacity of the top due to thermal expansion is suppressed. At the same time, under the combined influence of wind speed and thermal radiation, the top area absorbs a large amount of heat, causing the local temperature to rise rapidly, ultimately resulting in the maximum deformation at the top. When the wind speed reaches 8 m / s, the maximum total deformation of the tank is 0.26691 m. The maximum stress in the target storage tank ST2 is concentrated in the bottom region, and the stress value decreases along the height of the tank wall. Given that the bottom of storage tanks in actual engineering is usually fixed to the ground surface, the displacement boundary condition at the bottom is set to 0 during the simulation. After the target storage tank ST2 undergoes thermal response and deformation, the maximum stress occurs at the bottom of the tank. When the wind speed is 8 m / s, the maximum equivalent stress of the target storage tank ST2 is 2.9749 e. 8Pa. Under thermal response, due to the gradient difference in the internal temperature field of the target storage tank ST2, the resulting thermal stress causes deformation of the tank structure. When the wind speed reaches 8 m / s, the maximum thermal strain of storage tank ST2 reaches 0.015024 m.

[0091] Step 4: Based on the equivalent stress comparison of the yield strength of the atmospheric pressure tank at the corresponding temperature, the failure time of the atmospheric pressure tank is determined by the intersection point of the stress change curve of the atmospheric pressure tank under thermal response and the material yield strength curve. The failure time of the atmospheric pressure tank is the moment of structural failure.

[0092] The thermal radiation from the pool fire causes a temperature rise in the atmospheric pressure storage tank. As the temperature rises, the yield strength of the tank wall material decreases, leading to structural deformation. If the equivalent stress exceeds the material's yield limit at the current temperature, structural failure will occur. Numerical simulations were used to obtain the thermal response curves of the target storage tank ST2 with a fire-retardant coating under the pool fire of the accident storage tank ST1. Figure 18 The curves show the changes in maximum temperature, stress, and yield strength of target storage tank ST2 under the coupled effects of thermal radiation and wind speed at a wind speed of 8 m / s. Under the fire-retardant coating, the highest temperature of the tank wall of target storage tank ST2 is located at the top of the tank. Due to the combined effects of wind speed and thermal radiation, the higher the wind speed, the shorter the failure time of target storage tank ST2. The area at the bottom rear of the tank is the region of maximum stress. If the received thermal radiation intensity is low, the temperature is lower, and the yield strength of the tank material decreases slowly. As the thermal radiation intensity increases, the tank wall temperature will rise significantly, leading to a sharp decrease in the material's yield strength and ultimately structural failure. Therefore, the intersection of the stress change curve and the material yield strength curve of the atmospheric pressure storage tank under thermal radiation is used as the basis for determining the failure time. Thus, when the wind speed is 0 m / s, the failure time of target storage tank ST2 is approximately 515 s, while when the wind speed reaches 8 m / s, the failure time of target storage tank ST2 is approximately 190 s.

[0093] Step 5: Based on the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank, a correlation analysis is performed to generate a failure time assessment formula. Based on the principles of computational fluid dynamics, the fire process of the atmospheric pressure storage tank without fireproof coating is simulated through a simulation platform.

[0094] A correlation analysis was conducted based on the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank to generate a failure time assessment formula. The formula used is as follows:

[0095]

[0096] Where a, b, and c are coefficients; I is the thermal radiation intensity; V is the volume of the atmospheric pressure storage tank; and ttf is the failure time of the atmospheric pressure storage tank. A value of 1000m³ is selected.3 3000m 3 5000m 3 These three atmospheric pressure storage tanks of different volumes were used as the analysis objects. The target storage tank ST2 under the fireproof coating was simulated under different spacing and wind speed conditions. The failure time curves of the target storage tank ST2 with fireproof coating under different spacing and wind speed were plotted. The values ​​of a, b, and c were obtained through numerical simulation.

[0097] The failure time formula for an atmospheric pressure storage tank with a fire-retardant coating, derived from Ansys Fluent numerical simulation, is as follows:

[0098]

[0099] in, This refers to the failure time of target storage tanks with fire-retardant coatings under different wind speeds. V represents the thermal radiation received by the target storage tank under the fireproof coating, and V is the volume of the target storage tank.

[0100] When the spacing is the same, with the synergistic enhancement of wind force and thermal radiation intensity, the yield strength of the tank material will be significantly reduced due to the continuously enhanced thermal radiation effect, and the structural failure time will show a decreasing trend.

[0101] Specifically, based on the principles of computational fluid dynamics, a fire process simulation of an atmospheric pressure storage tank without fire-retardant coating was conducted using a simulation platform. The thermal radiation flux of the target storage tank ST2 under different wind speeds and distances was simulated using Pyrosim. Wind speed, thermal radiation flux, and distance were selected as factors to fit a formula:

[0102]

[0103] in, The value represents the thermal radiation received by the target storage tank without a fire-retardant coating. This refers to wind speed under natural conditions. Given the distance between the accident tank ST1 and the target tank ST2, the failure time of the unfire-retardant atmospheric pressure tank is obtained based on the formula for the failure time of an unfire-retardant atmospheric pressure tank under different wind speeds. The formula used is:

[0104]

[0105] V is the volume of the target storage tank. It is the failure time of the target storage tank without fireproof coating.

[0106] Step 6: Conduct correlation analysis based on the heat radiation flux received by atmospheric pressure storage tanks with and without fireproof coatings to quantitatively analyze the protective effect of fireproof coatings.

[0107] The protective effect of fire-retardant coatings is quantitatively analyzed by comparing the heat radiation flux received by atmospheric pressure storage tanks with and without fire-retardant coatings. The formula used is as follows:

[0108]

[0109] in, This refers to the effective time of a fire-retardant coated atmospheric pressure storage tank under the influence of wind speed and single-pool thermal radiation. It reflects the specific number of seconds that a fire-retardant coated tank experiences compared to an uncoated tank under specific, fixed operating conditions, calculated through numerical simulation. This value measures the protective effectiveness of the fire-retardant coating; a higher value indicates better effectiveness. The intensity of heat radiation from a pool fire experienced by the target storage tank under the fire-retardant coating. V represents the intensity of heat radiation from a pool fire experienced by the target storage tank without a fire-retardant coating, and V is the volume of the storage tank at atmospheric pressure. The effectiveness time probability reflects the statistical probability that the fire-retardant coating will successfully provide protection when considering fluctuations in random factors such as wind speed and spacing. This refers to the failure time of an atmospheric pressure storage tank without a fire-retardant coating.

[0110] Step 7: Use the Monte Carlo simulation method to generate random samples based on the normal distribution to evaluate the reliability of the fireproof coating.

[0111] There are uncertainties in the process of tank fire accidents in atmospheric pressure tank areas under the influence of wind speed and single tank fire radiation. The probability of the accident is also uncertain. Monte Carlo simulation method can simulate and analyze uncertainty risk. It has the advantage of evaluating the impact of the uncertainty of different variables on the results by random sampling. Monte Carlo simulation is used to analyze the accident by considering factors such as tank size, spacing, wind speed, and failure time of atmospheric pressure tanks with or without fireproof coating, and obtain a reliability assessment model.

[0112] Based on the Monte Carlo simulation method, a reliability assessment of the fire-resistant coating of atmospheric pressure storage tanks is conducted. First, based on the Probit extended model proposed by Cozzani, a failure criterion model for atmospheric pressure storage tanks is constructed, incorporating the effects of wind speed and the fire-resistant coating. Considering the coupling effect of wind field and thermal radiation, the Monte Carlo simulation method is used, assuming that the ambient wind speed, tank spacing, and thermal radiation intensity follow a normal distribution. A large-scale sample dataset is randomly generated based on the probability distribution, and the generated random samples are input into the accident probability model to calculate the tank failure probability under two conditions: with and without the fire-resistant coating. Finally, by calculating the difference in failure probabilities between the two conditions, a reliability improvement index for the fire-resistant coating is obtained, thereby quantitatively evaluating the protective effectiveness of the fire-resistant coating in uncertain environments. Figure 19 , representing the failure probability of an atmospheric pressure storage tank under fire-retardant coating, referencing Figure 20, representing the failure probability of an atmospheric pressure storage tank without a fire-retardant coating.

[0113] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation.

[0114] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented in software, the above embodiments can be implemented, in whole or in part, as a computer program product. Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution.

[0115] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment, depending on actual needs.

[0116] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank farms, characterized in that, The specific steps include: S1. Construct a pool fire model and generate flame heights under windless and windy conditions, respectively. S2. Based on the flame height parameter, the flame field distribution in the tank area is simulated and analyzed using twin simulation; S3. Numerical simulation analysis of the thermal response process of the atmospheric pressure storage tank with fireproof coating under different wind speeds, and stress simulation analysis to obtain the total deformation, equivalent stress and thermal strain characteristics of the atmospheric pressure storage tank. S4. Based on the equivalent stress comparison of the yield strength of the atmospheric pressure storage tank at the corresponding temperature, the failure time of the atmospheric pressure storage tank is determined by the intersection point of the stress change curve of the atmospheric pressure storage tank under thermal response and the material yield strength curve. The failure time of the atmospheric pressure storage tank is the moment when the structure of the atmospheric pressure storage tank fails. S5. Based on the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank, a correlation analysis was conducted to evaluate the failure time. Based on the principles of computational fluid dynamics, the fire process of the atmospheric pressure storage tank without fireproof coating was simulated through a simulation platform. Based on a correlation analysis of the failure time of the atmospheric pressure storage tank, the thermal radiation intensity, and the volume of the atmospheric pressure storage tank, a failure time assessment formula is generated. The formula is as follows: ； Where a, b, and c are coefficients; I is the thermal radiation intensity; V is the volume of the atmospheric pressure storage tank; and ttf is the failure time of the atmospheric pressure storage tank. A value of 1000m³ is selected. 3 3000m 3 5000m 3 Three atmospheric pressure storage tanks of different volumes were used as the analysis objects. The target storage tank ST2 under fireproof coating was simulated under different spacing and wind speed conditions. The failure time curves of the target storage tank ST2 with fireproof coating under different spacing and wind speed were plotted. The values ​​of a, b, and c were obtained through numerical simulation. Based on fluid mechanics principles, a fire process simulation of an atmospheric pressure storage tank without fire-retardant coating was conducted using a simulation platform. The target atmospheric pressure storage tank's thermal radiation value without fire-retardant coating was generated by fitting wind speed, heat radiation flux, and tank spacing. The formula used is as follows: ； in, The value represents the thermal radiation received by the target storage tank without a fire-retardant coating. This refers to wind speed under natural conditions. Given the distance between the accident tank ST1 and the target tank ST2, the failure time of the unfire-retardant atmospheric pressure tank is obtained based on the formula for the failure time of an unfire-retardant atmospheric pressure tank under different wind speeds. The formula used is: ； V is the volume of the target storage tank. It is the failure time of the target storage tank without fire-retardant coating; S6. Based on the heat radiation flux received by atmospheric pressure storage tanks with and without fireproof coatings, conduct correlation analysis to quantitatively analyze the protective effect of fireproof coatings. The protective effect of fire-retardant coatings is quantitatively analyzed by comparing the heat radiation flux received by atmospheric pressure storage tanks with and without fire-retardant coatings. The formula used is as follows: ； in, The effective time of exposure of an atmospheric pressure storage tank with a fire-retardant coating to wind speed and single-pool thermal radiation is used to quantify the protective effect of the fire-retardant coating. The intensity of heat radiation from a pool fire experienced by the target storage tank under the fire-retardant coating. V represents the intensity of heat radiation from a pool fire experienced by the target storage tank without a fire-retardant coating, and V is the volume of the storage tank at atmospheric pressure. ttf2 represents the time probability of effectiveness; ttf2 represents the failure time of an atmospheric pressure storage tank without fire-retardant coating. S7. Using the Monte Carlo simulation method, random samples are generated based on the normal distribution to evaluate the reliability of the fireproof coating.

2. The method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank farms according to claim 1, characterized in that: In S1 and S2, a pool fire model is constructed, flame height is calculated based on the Thomas formula, and twin simulation is used to simulate and analyze the flame thermal field distribution under the pool fire condition in the tank area. The simulation analysis includes: geometric model construction and mesh generation, parameter calibration and fire source condition setting, flame tilt angle analysis, detector spatial arrangement, and thermal response process analysis.

3. The method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank farms according to claim 2, characterized in that: The formula used for flame tilt angle analysis is: ,in, For dimensionless wind speed, To determine the flame tilt angle, the thermal response process analysis was conducted using a numerical simulation based on an empty tank model to analyze and obtain the thermal radiation released during the fire.

4. The method for evaluating the effectiveness and reliability of fire-resistant coatings in atmospheric pressure tank farms according to claim 3, characterized in that: In S3, the atmospheric pressure storage tank uses Q345 steel as the main material for the tank body. The radius of curvature of the dome structure is taken as 1.2 times the tank diameter. Four tank spacing conditions are set: 0.4DL, 0.6DL, 0.8DL and 1.0DL, where DL is the tank diameter. The fireproof coating is a lightweight silicate-based coating with a thickness of 50mm. Based on the cavity radiation theory, a thermodynamic response model of the atmospheric pressure storage tank is established to obtain the temperature field change diagram of the target storage tank ST2 affected by the accident storage tank ST1. The temperature field change diagram is used to reflect the relationship between the highest temperature of the target storage tank ST2 and the change over time.

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