Liquefied petroleum gas storage tank explosion tank fragmentation characteristic research method

Abstract

The invention discloses a liquefied petroleum gas storage tank explosion tank fragmentation characteristic research method, which comprises the following steps of S1, constructing a physical model of a storage tank, and dividing the constructed physical model to form a grid model; s2, simulating an explosion process in the storage tank under ideal conditions; s3, constructing a new in-tank steam cloud explosion CFD model according to the simulated explosion process, and performing numerical simulation on explosion characteristics in the storage tank; and S4, acquiring explosion characteristics under different height-diameter ratios, filling amounts and top cover forms at pressure observation points at representative positions of the storage tank. According to the invention, a common liquefied petroleum gas storage tank is used as a typical research object and has a universal rule; the explosion process is simulated through simulation modeling, an overpressure time history diagram and the like are obtained, and the explosion condition can be quantitatively displayed; and the model is mainly composed of three parts, and each part conforms to the real working condition, so that the obtained explosion characteristics are ensured to conform to the actual condition.

Description

Technical Field

[0001] The invention relates to the technical field of detection methods, and in particular to a method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion. Background Art

[0002] Liquefied petroleum gas has become a very important production resource, thus placing higher requirements on the safety of its production, transportation, storage and other processes.

[0003] In industrial parks, liquefied petroleum gas tanks are generally stored in a fixed tank area, where a large number of tanks are usually stored in accordance with specifications. When the temperature inside one of the tanks rises due to thunderstorms, collisions, friction, high temperatures, etc., a large amount of liquid vaporizes and mixes with air to form a vapor cloud within the explosion limit and the internal pressure increases, the tank will explode. If the explosion energy is large and exceeds the tank's tolerance limit, the tank body will shatter, and the resulting fragments will be carried away by the shock wave at a very fast speed and collide with other tanks around the tank area. Once the fragments penetrate the tank, the flammable and explosive liquid in the tank will leak out, which will cause a secondary explosion and further form a domino effect, and the consequences of the accident will be disastrous.

[0004] In view of this, it is necessary to design a research method for the fragmentation characteristics of the liquefied petroleum gas storage tank explosion, so as to study the explosion process of the liquefied petroleum gas storage tank, analyze the influencing factors affecting the fragmentation characteristics of the tank body, provide a theoretical basis for the safety protection of the tank explosion, and also have important significance for effectively controlling and reducing the occurrence of tank explosion accidents. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0006] To this end, the present invention provides a method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion, which can use numerical simulation methods to study the mechanism of the tank explosion process, the change of the flow field in the tank, the propagation of the shock wave, and the explosion shock pressure of the inner wall of the tank and other tank explosion fragmentation characteristics.

[0007] According to a first aspect of the present invention, a method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion is provided, comprising the following steps:

[0008] S1. construct a physical model of the storage tank, and divide the constructed physical model to form a grid model;

[0009] S2, simulate the explosion process inside the tank under ideal conditions;

[0010] S3. Construct a new CFD model of steam cloud explosion in the tank based on the simulated explosion process, and perform numerical simulation on the explosion characteristics in the tank;

[0011] S4. Obtain explosion characteristics under different height-to-diameter ratios, filling volumes and top cover forms at pressure observation points at representative locations of the storage tank.

[0012] Preferably, when dividing the constructed physical model, by inputting the x_t file, the x_t file is imported into the meshing software HyperMesh to divide the constructed physical model of the storage tank into a plurality of meshes of equal size to establish a mesh model, and output the k file.

[0013] Further preferably, in the established grid model, the gas and air structures use hexagonal grids with a side size of 0.15m, and the tank structure uses a hexagonal grid with a side size of 0.05m. The generated finite element grid includes 10680 gas, 41173 air and 2556 tank structure grids.

[0014] Preferably, the physical model of the storage tank is divided into three parts, the first part is the combustible gas in the central area, the second part is the air in the large area, and the third part is the storage tank structure, and the outside of the storage tank structure has an air layer with a thickness of 2m.

[0015] Further preferably, when simulating the internal explosion process of the storage tank under ideal conditions, six observation points A to F are set on the storage tank, wherein three observation points A to C are set on the top of the storage tank, two observation points E and F are set on the bottom, and an observation point D is set in the middle of the tank wall.

[0016] Preferably, when obtaining the explosion characteristics of a storage tank under different height-to-diameter ratios, filling volumes and top cover forms, it is necessary to control one or more of the height-to-diameter ratio, filling volume and top cover form for adjustment to obtain the explosion characteristics of the storage tank under different states.

[0017] Further preferably, to simulate the explosion process inside the storage tank under ideal conditions, the linear polynomial state equation of the combustible gas used is:

[0018] p=C 0 +C 1 u+C 2 u 2 +C 3 u 3 +(C 4 +C 5 u+C 6 u 2 );

[0019] Among them, P is the detonation pressure; E is the internal energy per unit volume; V is the relative volume; C0~C6 are the coefficients of the state equation.

[0020] Preferably, combustible gas is stored in the storage tank, and the combustible gas is set to fill a space set in the center of the storage tank, and the outside of the space is surrounded by air.

[0021] Preferably, the storage tank is suitable for adopting a vertical cylindrical dome steel storage tank with geometric dimensions of 1600 mm in diameter, 4400 mm in length and 10 mm in wall thickness.

[0022] Further preferably, the explosion process inside the storage tank under ideal conditions is simulated by a multi-material ALE algorithm, the model adopts Euler solid units, and the connection between the fluid and solid units is defined by the *CONSTRAINED_LAGRANGE_IN_SOLID keyword for fluid-solid coupling; the gas uses high-energy explosives to detonate the combustion material, the keyword is *MAT_HIGH_EXPLOSIVE_BURN, and the LINEAR_POLYNOMIAL state equation is used to describe the bombardment process; the air uses the *MAT_NULL material model and is also explained by the LINEAR_POLYNOMIAL state equation; the storage tank adopts the plastic body model *MAT_PLASTIC_KINEMATIC, with a density of 7800kg / m3, an elastic modulus E=200Gpa, and a Poisson's ratio of 0.3.

[0023] The beneficial effects of the present invention are as follows: by adopting a numerical simulation method, the problem of practical operational difficulties of large storage tanks is solved, and the numerical simulation can simulate the fragmentation characteristics of the rupture of the storage tank, providing a reference for the safety protection of the storage tank and the design of the safety distance between the storage tanks; using common liquefied petroleum gas storage tanks as typical research objects, it has universal laws; and by simulating the explosion process through simulation modeling, it is possible to more accurately calculate the explosion of a limited flammable gas cloud in a limited space, so as to obtain an overpressure time history diagram, etc., which can quantitatively display the explosion situation; and the various influencing parameters of the model are different, and by controlling different influencing parameters, it is ensured that the obtained accessories are consistent with the actual working conditions.

[0024] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0027] Figure 1A diagram of an explosion model inside a storage tank for a method of studying the fragmentation characteristics of an explosion tank body of a liquefied petroleum gas storage tank according to the present invention;

[0028] Figure 2 It is a top view pressure cloud diagram of the method for studying the fragmentation characteristics of the explosion tank of the liquefied petroleum gas storage tank of the present invention (a) 0.8ms top view;

[0029] Figure 3 It is a top view pressure cloud diagram of the method for studying the fragmentation characteristics of the liquefied petroleum gas storage tank explosion of the present invention (b) 1.1ms top view;

[0030] Figure 4 It is a top view pressure cloud diagram (c) 1.3ms top view of the method for studying the fragmentation characteristics of the liquefied petroleum gas storage tank explosion of the present invention;

[0031] Figure 5 It is a top view of the pressure cloud map (d) 1.4ms top view of the method for studying the fragmentation characteristics of the liquefied petroleum gas storage tank explosion of the present invention;

[0032] Figure 6a-6d It is the explosion overpressure time history curve at each observation point of the method for studying the fragmentation characteristics of the explosion tank body of the liquefied petroleum gas storage tank of the present invention;

[0033] Figure 7 A top view of a tank body rupture process of a method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to the present invention;

[0034] Figures 8a-8f The method for studying the fragmentation characteristics of the liquefied petroleum gas storage tank explosion of the present invention is to analyze the overpressure time history curves of the storage tank explosion at six typical observation points with a height-to-diameter ratio H / D=1.2, 1.5, 1.75, and 2;

[0035] Figures 9a-9f The explosion overpressure time history curves at six typical observation points are analyzed by selecting three cases of filling volume 25%, 50% and 75% for the research method of the fragmentation characteristics of the liquefied petroleum gas storage tank of the present invention;

[0036] Figure 10a-10c For the research method of the explosion and fragmentation characteristics of the liquefied petroleum gas storage tank of the present invention, three different forms of flat top, arch top and cone top are selected to analyze the explosion overpressure time history curves at six typical observation points;

[0037] Fig.11 A flow chart of a method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to the present invention;

[0038] Fig.12 The present invention is a schematic diagram of the operation flow of the method for studying the fragmentation characteristics of the liquefied petroleum gas storage tank explosion.

[0039] Reference numerals:

[0040] 1. Storage tank; 2. Combustible gas; 3. Air. DETAILED DESCRIPTION

[0041] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the components related to the present invention. In the description of the present invention, it should be understood that, unless otherwise specified, the meaning of "multiple" is two or more.

[0042] See also Figures 1 to 12 A method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to a specific embodiment of the present invention comprises the following steps:

[0043] S1, constructing a physical model of the storage tank 1, and dividing the constructed physical model to form a grid model;

[0044] S2, simulating the explosion process inside the storage tank 1 under ideal conditions;

[0045] S3. Construct a new CFD model of vapor cloud explosion in the tank according to the simulated explosion process, and perform numerical simulation on the explosion characteristics in the storage tank 1;

[0046] S4. Obtain explosion characteristics under different height-to-diameter ratios, filling volumes and top cover forms at pressure observation points at representative locations of the storage tank 1.

[0047] Specifically, the physical model of the storage tank 1 is constructed by using the drawing software SolidWorks. After the construction is completed, the x_t file is input; the x_t file is imported into the meshing software HyperMesh, and then the meshing software HyperMesh is used to divide the physical model into meshes of appropriate sizes and establish a mesh model.

[0048] More specifically, the finite element simulation software LS-Dyna is used to simulate the explosion process inside the tank 1 under ideal conditions. The models are all simulated using Euler solid elements (SOLID164) and the multi-material ALE algorithm; the connection between the fluid and solid elements is defined by the *CONSTRAINED_LAGRANGE_IN_SOLID keyword for fluid-solid coupling; the gas uses high-energy explosives to detonate the combustion material, the keyword is *MAT_HIGH_EXPLOSIVE_BURN, and the LINEAR_POLYNOMIAL state equation is used to describe the explosion process; the air uses the *MAT_NULL material model and the LINEAR_POLYNOMIAL state equation is also used to explain; the tank structure uses the plastic body model *MAT_PLASTIC_KINEMATIC, with a density of 7800kg / m3, an elastic modulus E=200Gpa, and a Poisson's ratio of 0.3.

[0049] In addition, during the simulation, six typical observation points A to F are set on the top cover, wall and connection of the storage tank 1, wherein three observation points A to C are set on the top of the storage tank, two observation points E and F are set on the bottom, and an observation point D is set in the middle of the tank wall. Under different observation points, the explosion characteristics of the storage tank under different height-to-diameter ratios, filling amounts and top cover forms can be obtained, and it is also necessary to control one or more of the height-to-diameter ratio, filling amount and top cover form for adjustment to obtain the explosion characteristics of the storage tank under different states. The present invention uses the DFT method to simulate the explosion process of the storage tank. Unlike other methods, the CFD method can more accurately calculate the explosion of a limited combustible gas cloud in a limited space in solving problems such as turbulence models, hourglass models, and combustion models.

[0050] In this embodiment, a common domestic liquefied petroleum gas storage tank 1WG1.77-1600-10 is selected. The storage tank 1 is a vertical cylindrical vault steel storage tank 1, and its main material is Q345R, and its dimensions are 1600mm in diameter, 4400mm in length, and 10mm in wall thickness. The geometric dimensions of the storage tank 1 are shown in Table 1. Geometric dimensions of the WG1.77-1600-10 storage tank 1:

[0051]

[0052] Table 1.

[0053] The storage tank 1 stores a combustible gas 2 , and the combustible gas 2 is set to fill a space set at the center of the storage tank 1 , and the outside of the space is surrounded by air 3 .

[0054] During the simulation, the three parts of the results, namely, the combustible gas 2, the air 3 and the shell of the cylindrical tank 1, were simulated using Euler solid elements, and the multi-material ALE algorithm was used.

[0055] Combustible gas 2 uses high-energy explosives to detonate combustion materials. The combustible gas parameters set the density to 1.23 and the detonation speed to 800. The linear polynomial state equation of combustible gas 2 is:

[0056] p=C 0 +C 1 u+C 2 u 2 +C 3 u 3 +(C 4 +C 5 u+C 6 u 2 );

[0057] Among them, P is the detonation pressure; E is the internal energy per unit volume; V is the relative volume; C0~C6 are the coefficients of the state equation. The parameters of the air model are set to density 1.32, polynomial parameters C0~C6 are 374, 3.23, 4.15, 0, 0.3, 7.0, 27, and E0 is 2.5e5. The tank structure uses a density of 7800kg / m3, an elastic modulus E=200Gpa, and a Poisson's ratio of 0.3.

[0058] In the model, the gas and air structures use hexagonal grids with a side size of 0.15m, and the tank structure uses a hexagonal grid with a side size of 0.05m. The generated finite element grid includes 10680 gas, 41173 air and 2556 tank structure grids.

[0059] In step 4, when numerical simulation is used to analyze the explosion pressure and shock wave in the tank, the explosion characteristics of the storage tank 1 under different height-to-diameter ratios, filling volumes and top cover forms need to be controlled respectively. The specific parameters are shown in Table 2. Structural geometric dimensions of different H / D storage tanks 1 and Table 3. Geometric dimensions of different types of top cover storage tanks 1 (flat-top tanks, conical-top tanks, and dome-top tanks).

[0060]

[0061] Table 2.

[0062] Flat Top Cone Top dome Hr(m) 0 0.22 0.22 D(m) 2 2 20 Hr / 0.5D 0 0.22 1.2

[0063] Table 3.

[0064] Therefore, the research method is novel, and the selected experimental object is the more common domestic liquefied petroleum gas storage tank 1WG1.77-1600-10. The size of the liquefied petroleum gas storage tank 1 and the materials used are typical, so taking it as the research object has universal laws.

[0065] In addition, the research method is further improved based on the finite element simulation software LS-Dyna in that simulation modeling can be realized to simulate the explosion process, so as to obtain the overpressure time history diagram and other quantitative display of the explosion situation. And the established model is roughly the same as the actual working condition. In order to better establish the model of storage tank 1, the internal steam cloud explosion characteristics of storage tank 1 are extracted, and the range of combustible gas 2 is simplified to fill the cylindrical space (air layer) with a diameter of 1m and a length of 2m in the center of the tank, and the outside is wrapped with air 3, so as to better extract the explosion characteristics in storage tank 1.

[0066] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0067] The above description is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion, characterized in that: The following steps are involved: S1. construct a physical model of the storage tank, and divide the constructed physical model to form a grid model; S2, simulate the explosion process inside the tank under ideal conditions; S3. Construct a new CFD model of steam cloud explosion in the tank based on the simulated explosion process, and perform numerical simulation on the explosion characteristics in the tank; S4. Obtain explosion characteristics under different height-to-diameter ratios, filling volumes and top cover forms at pressure observation points at representative locations of the storage tank.

2. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 1 is characterized in that: When dividing the constructed physical model, the x_t file is input and imported into the meshing software HyperMesh to divide the constructed physical model of the storage tank into a plurality of meshes of equal size to establish a mesh model, and the k file is output.

3. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 2 is characterized in that: In the established grid model, the gas and air structures use hexagonal grids with a side size of 0.15m, and the tank structure uses a hexagonal grid with a side size of 0.05m. The generated finite element grid includes 10680 gas, 41173 air and 2556 tank structure grids.

4. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 1 is characterized in that: The physical model of the storage tank is divided into three parts. The first part is the combustible gas in the central area, the second part is the air in the large area, and the third part is the storage tank structure. The outside of the storage tank structure has an air layer with a thickness of 2m.

5. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 1 is characterized in that: When simulating the internal explosion process of the storage tank under ideal conditions, six observation points A~F are set on the storage tank, among which three observation points A~C are set on the top of the storage tank, two observation points E and F are set on the bottom, and an observation point D is set in the middle of the tank wall.

6. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 1 is characterized in that: When obtaining the explosion characteristics of a storage tank under different height-to-diameter ratios, filling volumes, and top cover forms, it is necessary to control one or more of the height-to-diameter ratio, filling volume, and top cover form for adjustment to obtain the explosion characteristics of the storage tank under different states.

7. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 6 is characterized in that: To simulate the explosion process inside the tank under ideal conditions, the linear polynomial state equation of the combustible gas used is: p=C0+C1u+C2u 2 +C3u 3 +(C4+C5u+C6u 2 ); Among them, P is the detonation pressure; E is the internal energy per unit volume; V is the relative volume; C0~C6 are the coefficients of the state equation.

8. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to claim 3 is characterized in that: The storage tank stores combustible gas, and the combustible gas is set to fill a space set at the center of the storage tank, and the outside of the space is surrounded by air.

9. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to any one of claims 1 to 8, characterized in that: The storage tank is suitable for adopting a vertical cylindrical dome steel storage tank with geometric dimensions of 1600 mm in diameter, 4400 mm in length and 10 mm in wall thickness.

10. The method for studying the fragmentation characteristics of a liquefied petroleum gas storage tank explosion according to any one of claims 1 to 8, characterized in that: The multi-material ALE algorithm is used to simulate the explosion process inside the storage tank under ideal conditions. The model uses Euler solid units, and the connection between the fluid and solid units is defined by fluid-solid coupling through the *CONSTRAINED_LAGRANGE_IN_SOLID keyword; the gas uses high-energy explosives to detonate the combustion material, the keyword is *MAT_HIGH_EXPLOSIVE_BURN, and the LINEAR_POLYNOMIAL state equation is used to describe the bombardment process; the air uses the *MAT_NULL material model and is also explained by the LINEAR_POLYNOMIAL state equation; the storage tank uses the plastic body model *MAT_PLASTIC_KINEMATIC, with a density of 7800kg / m3, an elastic modulus E=200Gpa, and a Poisson's ratio of 0.3.

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