Method and system for calculating stress of outer tank system of full-capacity liquid ammonia storage tank and readable medium

Abstract

The invention relates to a stress calculation method and system for an outer tank system of a full-capacity liquid ammonia storage tank and a readable medium. The stress calculation method comprises the following steps: acquiring structure information and material information of the outer tank system of the full-capacity liquid ammonia storage tank; the method comprises the steps of determining unit types of all structures of an outer tank system, conducting geometric modeling according to structure information, completing a solid model, correcting the unit types of all the structures, obtaining real constants, setting the section size of a beam unit, setting material properties according to material information, distributing unit attributes according to the unit types, conducting grid division on all the unit types, and conducting grid division on all the unit types. Generating a finite element model; applying a load effect to the finite element model, setting boundary conditions, and calculating the finite element model to which the load is applied to obtain a stress and deformation distribution result of the outer tank system; and analyzing the stress and deformation distribution result to obtain an outer tank system stress distribution result. The stress distribution condition of the outer tank system of the full-capacity liquid ammonia storage tank under the normal use working condition can be accurately, truly and intuitively reflected.

Description

Technical Field

[0001] The invention relates to a method, system and readable medium for calculating stress of an outer tank system of a full-capacity liquid ammonia storage tank, and belongs to the technical field of low-temperature energy storage. Background Art

[0002] At present, the global pressure to reduce carbon emissions is increasing day by day. The research and application of ammonia as a zero-carbon fuel with convenient transportation, low cost and sufficient supply has received more and more attention. The efficient storage of ammonia has become a key issue of international concern. The largest volume of liquid ammonia storage tank built in China is 50,000 cubic meters, which uses a bimetallic full-containment tank. Due to factors such as the performance of the liquid ammonia storage tank material itself, the structural stress performance, and geological conditions, the feasibility of continuing to increase the tank capacity under the traditional structural type is relatively small and has reached its limit.

[0003] There are three storage processes for liquid ammonia: pressurized normal temperature, pressurized low temperature, and normal pressure and low temperature. The low-temperature and low-pressure process stores liquid ammonia in a properly frozen state, which reduces the design pressure of the storage equipment to thin its walls, thereby reducing the investment in storage tanks. The normal pressure and low temperature process freezes liquid ammonia to a temperature not higher than its boiling point (below -33°C, depending on the local atmospheric pressure), so that the corresponding gas phase pressure of the liquid ammonia is the same or close to the atmospheric pressure, so that it can be stored in normal pressure containers to minimize the investment in storage tanks.

[0004] Full-containment liquid ammonia storage tanks are indispensable in the storage and transportation of liquid ammonia. The bimetallic full-containment liquid ammonia storage tank is composed of an inner and outer tank to form the entire tank storage system. The inner and outer tank walls are filled with thermal insulation materials perlite and elastic felt, and the ceiling deck is laid with insulating glass wool. The outer tank system mainly includes the outer tank arch plate, connecting pipe, main beam, ring beam, inclined beam, hanger, ceiling deck, outer tank wall plate and reinforcement ring and outer tank bottom plate. The inner and outer tank materials are carbon steel or alloy steel. In view of the design temperature of the liquid ammonia storage tank of -33℃ to -40℃, the tank structure needs to be evaluated for rationality and reliability, and a relatively intuitive and accurate model is obtained. The existing technology lacks the tank structure, especially the stress evaluation of the outer tank system, and cannot guarantee the rationality and reliability of the tank structure. Summary of the invention

[0005] In view of the above problems, the purpose of the present invention is to provide a stress calculation method, system and readable medium for the outer tank system of a full-containment liquid ammonia storage tank, which can accurately, truly and intuitively reflect the stress distribution of the outer tank system of the full-containment liquid ammonia storage tank under normal operating conditions of its own gravity, design pressure and side wall pressure of the cold insulation structure, thereby providing an important reference for calculating and optimizing the structural design of the outer tank system of the full-containment liquid ammonia storage tank and ensuring the safety of the liquid ammonia storage tank. A stress analysis calculation method based on finite element software.

[0006] To achieve the above-mentioned purpose, the present invention proposes the following technical scheme: a method for calculating the stress of an outer tank system of a full-containment liquid ammonia storage tank, comprising the following steps: obtaining structural information and material information of an outer tank system of a full-containment liquid ammonia storage tank; determining the unit type of each structure of the outer tank system according to the structural information, performing geometric modeling according to the structural information, completing a solid model, correcting the unit type of each structure according to the solid model, obtaining real constants, and setting the cross-sectional size of the beam unit, setting material properties according to the material information, assigning unit attributes according to the unit type, meshing each unit type, and generating a finite element model; applying a load to the finite element model, setting boundary conditions, and calculating the finite element model with applied load to obtain stress and deformation distribution results of the outer tank system; analyzing the stress and deformation distribution results to obtain stress distribution results of the outer tank system.

[0007] Furthermore, the components of the outer tank system include the outer tank arch plate, connecting pipe, main beam, ring beam, inclined beam, center ring, hanger, ceiling deck, outer tank wall plate and reinforcement ring and outer tank bottom plate, and also include perlite, a heat-insulating and cold-preserving material filled between the inner and outer tank walls, and insulating glass wool laid on the ceiling deck. The outer tank arch plate, connecting pipe, ceiling deck, outer tank wall plate and reinforcement ring are represented by surface elements, and the main beam, ring beam, inclined beam, center ring and hanger are represented by line elements; the outer tank bottom plate is represented by volume elements.

[0008] Furthermore, the method for establishing the finite element model is as follows: the finite element model is created from the bottom up, the lowest unit key points of the model are established, lines are defined by the key points, surfaces are established by the lines, and a body is defined by the surfaces, a coordinate system is selected, the storage tank uses the x-axis and y-axis as axes of symmetry, and the z-axis as the height direction; the line segmentation on the vault plate surface element obtains the position of the beam; the line segmentation on the ceiling deck surface element obtains the position of the hanger; the line segmentation on the outer tank wall panel surface element obtains the various circles of the outer tank wall panel.

[0009] Furthermore, the unit types include shell units Shell, beam units Beam and solid units Solid. In the finite element model, the structural parts of the outer tank system adopt the shell units Shell in the finite element software; the supporting structural parts of the outer tank system adopt the beam units Beam in the finite element software; and the outer tank bottom plate of the outer tank system adopts the solid unit Solid in the finite element software.

[0010] Furthermore, the method for setting material properties is as follows: the density, elastic modulus and Poisson's ratio of the steel are respectively input according to the actual working conditions of the storage tank, the weight of the insulating glass wool laid on the ceiling deck is taken into account when the steel density attribute of the ceiling deck is assigned, and the unit attributes are assigned according to the unit type to assign material numbers to each component, number the unit type, number the real constants, and set the beam unit number.

[0011] Furthermore, the meshing method for each unit type is as follows: setting the unit size, specifying the shape of the mesh unit, specifying the meshing type, and continuously iterating and adjusting the meshing according to the calculation results. The meshing method and size adopted are comprehensively compared: the maximum stress value of the outer tank system of the full-capacity liquid ammonia storage tank is used as the evaluation index, and the calculation results are compared with the calculation results of different mesh sizes. The relative change value of the calculation results before and after is within the threshold value as the final mesh size of the model. If the relative change value of the calculation result exceeds the threshold value, the size will be halved and the mesh will be encrypted until the relative change value of the calculation results before and after is within the threshold range.

[0012] Furthermore, the load action includes: applying its own gravity, applying design pressure and applying pressure on the side wall of the cold insulation structure; the method of applying load action to the finite element model is: applying design pressure to the outer tank arch plate and the inner wall surface of the outer tank wall plate; applying uniform pressure of the cold insulation structure on the inner wall surface of the outer tank wall plate to the outer tank side wall; applying equivalent force and gravity acceleration to the connecting pipe port; and applying fixed constraints to the outer tank bottom plate.

[0013] Furthermore, the method for obtaining the stress and deformation distribution results of the outer tank system is: solving the finite element model until the deformation value and stress value of the outer tank system are extracted after the calculation is completed, calculating the stress distribution and deformation of the structure after bearing the load, finding the maximum stress point, and making the stress of the maximum stress point lower than the stress threshold of the outer tank system.

[0014] The present invention also discloses a stress calculation system for an outer tank system of a full-containment liquid ammonia storage tank, comprising: an information acquisition module, used for acquiring structural information and material information of the outer tank system of the full-containment liquid ammonia storage tank; a finite element model generation module, used for determining the unit type of each structure of the outer tank system according to the structural information, performing geometric modeling according to the structural information, completing a solid model, correcting the unit type of each structure according to the solid model, obtaining real constants, and setting the cross-sectional size of the beam unit, setting material properties according to the material information, assigning unit attributes according to the unit type, meshing each unit type, and generating a finite element model; a load application module, used for applying a load to the finite element model, setting boundary conditions, and calculating the finite element model with the applied load to obtain stress and deformation distribution results of the outer tank system; and analyzing the stress and deformation distribution results to obtain the stress distribution results of the outer tank system.

[0015] The present invention also discloses a computer-readable storage medium, on which a computer program is stored. The computer program is executed by a processor to implement the method for calculating the stress of the outer tank system of a full-capacity liquid ammonia storage tank as described in any one of the above.

[0016] The technical solution of the present invention has at least the following technical effects or advantages: the present invention can accurately, truly and intuitively reflect the stress distribution of the outer tank system of the full-capacity liquid ammonia storage tank under normal use conditions of its own gravity, design pressure and the side wall pressure of the cold insulation structure, and maximize the actual stress state, and find out the stress distribution and deformation of the structure after bearing the load, and find out the maximum stress point, so as to provide an important reference for calculating and optimizing the structural design of the outer tank system of the full-capacity liquid ammonia storage tank and ensuring the safety of the liquid ammonia storage tank. At the same time, the obtained solid model and finite element model can be used in subsequent live load, snow load, wind load, and earthquake response analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a flow chart of a method for calculating stress of an outer tank system of a full-capacity liquid ammonia storage tank in one embodiment of the present invention;

[0018] Figure 2 This is a structural diagram of an outer tank system of a full-capacity liquid ammonia storage tank in one embodiment of the present invention;

[0019] Figure 3 is a schematic diagram of an overall geometric model in ANSYS APDL finite element software in one embodiment of the present invention;

[0020] Figure 4 is a schematic diagram of surface primitives and volume primitives in finite element software in one embodiment of the present invention;

[0021] Figure 5 It is a structural schematic diagram of line elements of a main beam, a ring beam, an inclined beam and a center ring in a finite element software in one embodiment of the present invention;

[0022] Figure 6 It is a structural schematic diagram of line elements of a main beam, a ring beam, an inclined beam, a center ring and a suspension ring in a finite element software in one embodiment of the present invention;

[0023] Figure 7 It is a schematic diagram of the structure of a grid unit diagram of an outer tank system in a finite element software in one embodiment of the present invention;

[0024] Figure 8 yes Figure 7 A partial enlarged view of the grid unit at A in the middle;

[0025] Fig. 9 is a grid unit diagram of a main beam, a ring beam, an inclined beam, a center ring and a suspension rod in a finite element software in one embodiment of the present invention;

[0026] Fig.10 yes Fig. 9 A partial enlarged view of the grid unit at B in the middle;

[0027] Fig.11is a schematic diagram of the outer tank deadweight, design pressure and side wall pressure loading in the finite element software in one embodiment of the present invention;

[0028] Fig.12 It is a displacement cloud diagram of the deadweight design pressure and the side wall pressure of the outer tank loaded in the finite element software in one embodiment of the present invention;

[0029] Fig.13 It is a stress cloud diagram of the deadweight design pressure and the side wall pressure of the outer tank loaded in the finite element software in one embodiment of the present invention.

[0030] Reference numerals:

[0031] 1-external tank arch plate; 2-pipe connection; 3-main beam; 4-ring beam; 5-inclined beam; 6-center ring; 7-suspender rod; 8-ceiling deck; 9-external tank wall plate and reinforcement ring; 10-external tank bottom plate. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the provision of specific embodiments is only for a better understanding of the present invention, and they should not be understood as limitations of the present invention. In the description of the present invention, it should be understood that the terms used are only for the purpose of description and cannot be understood as indicating or implying relative importance.

[0033] For full-capacity liquid ammonia storage tanks, domestic and foreign research is relatively comprehensive and in-depth. Although the structural form of full-capacity liquid ammonia storage tanks is also divided into two layers of inner and outer tanks, the inner tank is open and in direct contact with LNG, but the material of the outer tank is usually prestressed reinforced concrete, and the outer tank is composed of a reinforced concrete outer tank bottom plate 10, a prestressed reinforced concrete tank wall and a reinforced concrete dome. At present, the research on full-capacity liquid ammonia storage tanks at home and abroad is not comprehensive enough. Full-capacity liquid ammonia storage tanks are also composed of a main container (inner tank) and a secondary container (outer tank). The inner tank is an open-top steel storage tank that directly contains liquid ammonia. It is composed of an inner tank wall plate and a reinforcement ring, an inner tank bottom plate, etc. An open ceiling deck 8 is suspended on the upper part of the inner tank, and the ceiling deck 8 is supported by a hanger suspended from the dome of the outer tank. Because the inner tank is the main container, the inner tank is currently the main research object, and finite element software is used to carry out static stress analysis and safety assessment, fatigue analysis, modal analysis, seismic response analysis, temperature field analysis and inner tank weld analysis on the inner tank. Although the outer tank is a secondary container, it should be able to withstand the gas pressure inside the tank under normal operating conditions, withstand deadweight, live load, snow load, wind load, and maintain the necessary bearing capacity of the structure. Withstand earthquake effects and maintain the functional integrity of the structure. The outer tank system of a full-capacity liquid ammonia storage tank has many components, including the outer tank arch plate 1, pipe 2, main beam 3, ring beam 4, inclined beam 5, hanger 7, ceiling deck 8, outer tank wall plate and reinforcement ring 9 and outer tank bottom plate 10, etc., and also includes the insulation material perlite filled between the inner and outer tank walls and the insulation glass wool laid on the ceiling deck 8. The unit types involve beam units, shell units, solid units, etc. When using finite element software to analyze the outer tank system, the pipe 2, hanger 7, ceiling deck 8 or inclined beam 5 cannot be ignored and a full model needs to be established, so as to maximize the reflection of the actual stress condition, find out the stress distribution and deformation of the structure after bearing the load, and find the maximum stress point.

[0034] In order to solve the problems existing in the prior art, such as the lack of tank structure, especially the stress evaluation of the outer tank system, and the inability to ensure the reasonable reliability of the tank structure, the present invention proposes a stress calculation method, system and readable medium for the outer tank system of a full-capacity liquid ammonia storage tank, including: obtaining structural information and material information of the outer tank system of the full-capacity liquid ammonia storage tank; pre-determining the unit type of each structure according to the tank drawing; and calculating the stress of the outer tank system in ANSYS according to the tank drawing and size. Geometric modeling is performed in APDL finite element software to complete the solid model. The solid model of the outer tank system mainly includes the outer tank arch plate 1, the connecting pipe 2, the main beam 3, the ring beam 4, the inclined beam 5, the center ring 6, the hanger 7, the ceiling deck 8, the outer tank wall plate and the reinforcement ring 9 and the outer tank bottom plate 10, etc.; according to the structural information and material information of each part of the outer tank system, the unit type and real constant are set, and the cross-sectional size of the beam unit is set; the material properties are established according to the design data, and the material properties are set; the unit attributes are allocated; the mesh division is controlled and the mesh division is performed to obtain the finite element model; various loads and boundary conditions such as self-gravity, design pressure and side wall pressure of the cold insulation structure are applied to the finite element model of the outer tank system, and the results are calculated and solved to obtain the results. After the calculation is completed, the stress and deformation distribution results of the outer tank system are extracted; according to the stress and deformation distribution results of the outer tank system, the analysis is performed to obtain the analysis results. The present invention can accurately, truly and intuitively reflect the stress distribution of the outer tank system of a full-capacity liquid ammonia storage tank under normal operating conditions of its own gravity, design pressure and the side wall pressure of the cold insulation structure, thereby providing an important reference for calculating and optimizing the structural design of the outer tank system of the full-capacity liquid ammonia storage tank and ensuring the safety of the liquid ammonia storage tank. At the same time, the obtained solid model and finite element model can be used in subsequent live load, snow load, wind load, and earthquake response analysis. The scheme of the present invention is described in detail below through examples.

[0035] Embodiment 1

[0036] This embodiment discloses a method for calculating the stress of the outer tank system of a full-capacity liquid ammonia storage tank. The finite element software in this embodiment is ANSYS APDL software. ANSYS software is a numerical simulation software that provides a wide range of engineering simulation solutions and can perform virtual simulations on all design requirements. The software mainly includes a pre-processing module, an analysis and calculation module, and a post-processing module. Figure 1 As shown, the stress calculation method includes the following steps:

[0037] S1 obtains the structural information and material information of the outer tank system of the full-capacity liquid ammonia storage tank.

[0038] The outer tank system of the full-containment liquid ammonia storage tank has many components, including the outer tank arch plate 1, the pipe 2, the main beam 3, the ring beam 4, the inclined beam 5, the center ring 6, the suspension rod 7, the ceiling deck 8, the outer tank wall plate and the reinforcement ring 9 and the outer tank bottom plate 10, and also includes the perlite insulation material filled between the inner and outer tank walls and the insulation glass wool laid on the ceiling deck 8, such as Figure 2 shown.

[0039] S2 determines the unit type of each structure of the outer tank system according to the structural information, performs geometric modeling according to the structural information, completes the solid model, modifies the unit type of each structure according to the solid model, obtains real constants, and sets the cross-sectional size of the beam unit. It sets the material properties according to the material information, assigns unit attributes according to the unit type, meshes each unit type, and generates a finite element model.

[0040] In this embodiment, the unit types include shell unit Shell, beam unit Beam and solid unit Solid. In the finite element model, the structural parts of the outer tank system adopt the shell unit Shell in the finite element software; the supporting structural parts of the outer tank system adopt the beam unit Beam in the finite element software; the outer tank bottom plate 10 of the outer tank system adopts the solid unit Solid in the finite element software. The structural parts of the outer tank system include but are not limited to the outer tank arch plate 1, the pipe 2, the ceiling deck 8, the outer tank wall plate and the reinforcement ring 9; the supporting structural parts of the outer tank system include the main beam 3, the ring beam 4, the inclined beam 5 and the suspension rod 7.

[0041] In the ANSYS APDL finite element software, the outer tank arch plate 1, the connecting pipe 2, the ceiling deck 8, the outer tank wall plate and the reinforcement ring 9 and other structural parts adopt surface elements, the main beam 3, the ring beam 4, the inclined beam 5, the center ring 6 and the hanger 7 adopt line elements or beam elements; the outer tank bottom plate 10 adopts volume elements.

[0042] According to the structural information, such as the tank drawings and the size structure information, geometric modeling is performed in the ANSYS APDL finite element software to complete the solid model. According to the structural information and material information of each part of the outer tank system, the unit type and real constant are set, and the cross-sectional size of the beam unit is set. The method of establishing the finite element model is as follows: the solid model modeling elements mainly include key points, lines, surfaces, and bodies. The finite element model is created from the bottom up, the lowest unit key points of the model are established, the higher-level lines are defined by the key points, the surfaces are established by the lines, and the bodies are defined by the surfaces. The coordinate system is selected, and the storage tank takes the x-axis and y-axis as the symmetry axes and the z-axis as the height direction; the main software operation commands are in the Main Menu\Preprocessor\Modeling module in the ANSYS APDL finite element software. The line segmentation on the vault plate surface element obtains the position of the beam; the line segmentation on the ceiling deck 8 surface element obtains the position of the hanger 7; the line segmentation on the outer tank wall plate surface element obtains the various circles of the outer tank wall plate. In this embodiment, the coordinate system includes but is not limited to the earth coordinate system, the local coordinate system, the working plane, the Cartesian coordinate system, and the cylindrical coordinate system. The line segmentation on the vault plate element is the position of the beam. The line segmentation on the 8-surface element of the ceiling deck is the position of the hanger 7. The overall geometric model of the outer tank system of the full-capacity liquid ammonia storage tank is as follows: Figure 3 As shown, the surface elements of the outer tank vault plate 1, the pipe 2, the ceiling deck 8, the outer tank wall plate and the reinforcement ring 9 and the volume element of the outer tank bottom plate 10 are as shown in FIG. Figure 4 As shown, the line elements of the main beam 3, the ring beam 4, the inclined beam 5 and the center ring 6 are as follows Figure 5 As shown, the line elements of the main beam 3, ring beam 4, inclined beam 5, center ring 6 and hanging ring are as shown in Figure 6 shown.

[0043] According to the entity model, the unit type of each structure is modified to obtain the real constants, and the cross-sectional dimensions of the beam unit and the thickness of the shell unit are set to achieve different thicknesses of the outer tank vault plate 1, the pipe 2, the ceiling deck 8 and the outer tank wall plate. The size setting Sections sets the cross-sectional dimensions and section numbers of the beam unit to achieve different cross-sectional shapes and cross-sectional dimensions of the main beam 3, the ring beam 4, the inclined beam 5, the center ring 6 and the suspension rod 7.

[0044] The method for setting the material properties is: input the physical property values ​​such as density, elastic modulus and Poisson's ratio of the steel according to the actual working conditions of the storage tank, and take into account the weight of the insulating glass wool laid on the ceiling deck 8 when assigning the steel density attribute of the ceiling deck 8.

[0045] Because the outer tank system of the full-containment liquid ammonia storage tank has many components, including the outer tank arch plate 1, connecting pipe 2, main beam 3, ring beam 4, inclined beam 5, center ring 6, hanger 7, ceiling deck 8, outer tank wall plate and reinforcement ring 9 and outer tank bottom plate 10, etc., the unit attributes are assigned according to the unit type, including assigning material numbers to each component, numbering the unit type, numbering the real constants, setting the beam unit number, etc.

[0046] Meshing will directly affect the final calculation accuracy and efficiency. The finite element model in this embodiment has a complex structure and large size, so the requirements for meshing directly determine the amount of calculation. The meshing method for each unit type is: set the unit size, specify the shape of the mesh unit, specify the meshing type, such as free meshing or mapped meshing. Selecting the appropriate meshing type also has a significant impact on the calculation results. The mesh division is continuously iterated and adjusted according to the calculation results, and the adopted meshing method and size are comprehensively compared: the maximum stress value of the outer tank system of the full-capacity liquid ammonia storage tank is used as the evaluation index, and the calculation results are compared with the calculation results of different mesh sizes. The relative change value of the calculation results before and after is within the threshold value as the final mesh size of the model. If the relative change value of the calculation result exceeds the threshold, the size will be halved and the mesh will be encrypted until the relative change value of the calculation results before and after is within the threshold range. The threshold in this embodiment is 5%. The mesh unit diagram of the outer tank system in the finite element software is as follows: Figure 7 As shown; the partial enlarged view of the mesh unit of the main beam 3, the ring beam 4, the inclined beam 5 and the center ring 6 in the finite element software is as follows Figure 8 The mesh unit diagram of the main beam 3, ring beam 4, inclined beam 5, center ring 6 and suspension rod 7 in the finite element software is shown in FIG. Fig. 9 The enlarged partial view of the mesh unit of the main beam 3, ring beam 4, inclined beam 5, center ring 6 and suspension rod 7 in the finite element software is shown in FIG. Fig.10 shown.

[0047] S3 applies load to the finite element model, sets boundary conditions, and calculates the finite element model with applied load to obtain stress and deformation distribution results of the outer tank system; and analyzes the stress and deformation distribution results to obtain stress distribution results of the outer tank system.

[0048] The load action includes: applying self-gravity, applying design pressure and applying cold insulation structure side wall pressure; the method of applying load action to the finite element model is: applying design pressure to the outer tank arch plate 1 and the inner wall surface of the outer tank wall plate; applying the cold insulation structure to the inner wall surface of the outer tank wall plate to uniformly distribute the pressure on the outer tank side wall; applying equivalent force and gravity acceleration to the pipe opening of pipe 2; applying fixed constraints to the outer tank bottom plate 10. Apply load action and boundary conditions to the finite element model of the outer tank system, such as Fig.11 shown.

[0049] The method for obtaining the stress and deformation distribution results of the outer tank system is: solve the finite element model until the calculation is completed, extract the deformation value and stress value of the outer tank system, maximize the reflection of the actual stress condition, find out the stress distribution and deformation of the structure after bearing the load, find out the maximum stress point, and make the stress at the maximum stress point lower than the stress threshold of the outer tank system. This provides an important reference for calculating and optimizing the structural design of the outer tank system of the full-capacity liquid ammonia storage tank and ensuring the safety of the liquid ammonia storage tank. At the same time, the obtained solid model and finite element model can be used in subsequent live load, snow load, wind load, and seismic response analysis. The displacement cloud diagram of the self-weight design pressure and side wall pressure loaded on the outer tank in the finite element software is shown below: Fig.12 The stress cloud diagram of the outer tank loaded with deadweight design pressure and side wall pressure in the finite element software is shown in Fig.13 shown.

[0050] Embodiment 2

[0051] Based on the same inventive concept, this embodiment discloses a stress calculation system for an outer tank system of a full-capacity liquid ammonia storage tank, comprising:

[0052] An information acquisition module is used to obtain structural information and material information of the outer tank system of the full-capacity liquid ammonia storage tank;

[0053] The finite element model generation module is used to determine the unit type of each structure of the outer tank system according to the structural information, perform geometric modeling according to the structural information, complete the solid model, modify the unit type of each structure according to the solid model, obtain the real constant, and set the cross-sectional size of the beam unit, set the material properties according to the material information, assign unit attributes according to the unit type, mesh each unit type, and generate a finite element model; the load application module is used to apply loads to the finite element model, set boundary conditions, and calculate the finite element model with applied loads to obtain the stress and deformation distribution results of the outer tank system; the stress and deformation distribution results are analyzed to obtain the stress distribution results of the outer tank system.

[0054] Embodiment 3

[0055] Based on the same inventive concept, this embodiment discloses a computer-readable storage medium, on which a computer program is stored, and the computer program is executed by a processor to implement any of the above-mentioned methods for calculating the stress of the outer tank system of a full-containment liquid ammonia storage tank.

[0056] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0057] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0058] These computer program instructions may also be stored in a computer readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture including an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0059] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0060] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation of the present invention can still be modified or replaced by equivalents, and any modification or equivalent replacement that does not deviate from the spirit and scope of the present invention should be included in the protection scope of the claims of the present invention. The above content is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or replacements within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A method for calculating the stress of the outer tank system of a full-capacity liquid ammonia storage tank, characterized in that: The following steps are involved: Obtain the structural information and material information of the outer tank system of the full-capacity liquid ammonia storage tank; Determine the unit type of each structure of the outer tank system according to the structural information, perform geometric modeling according to the structural information, complete the solid model, modify the unit type of each structure according to the solid model, obtain real constants, and set the cross-sectional size of the beam unit, set the material properties according to the material information, assign unit attributes according to the unit type, mesh each unit type, and generate a finite element model; A load is applied to the finite element model, boundary conditions are set, and the finite element model with the applied load is calculated to obtain stress and deformation distribution results of the outer tank system; and the stress and deformation distribution results are analyzed to obtain stress distribution results of the outer tank system.

2. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 1, characterized in that: The structures of the outer tank system include the outer tank vault plate, connecting pipe, main beam, ring beam, inclined beam, center ring, hanger, suspended ceiling deck, outer tank wall plate and reinforcement ring and outer tank bottom plate, and also include perlite, a heat-insulating and cold-preserving material filled between the inner and outer tank walls, and insulating glass wool laid on the suspended ceiling deck. The outer tank vault plate, connecting pipe, suspended ceiling deck, outer tank wall plate and reinforcement ring adopt surface graphics, the main beam, ring beam, inclined beam, center ring and hanger adopt line graphics; the outer tank bottom plate adopts volume graphics.

3. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 1, characterized in that: The method for establishing the finite element model is as follows: the finite element model is created from the bottom up, the lowest unit key points of the model are established, lines are defined by the key points, surfaces are established by the lines, and a body is defined by the surfaces, a coordinate system is selected, the storage tank uses the x-axis and y-axis as symmetry axes, and the z-axis as the height direction; the line segmentation on the vault plate surface element obtains the position of the beam; the line segmentation on the ceiling deck surface element obtains the position of the hanger; the line segmentation on the outer tank wall panel surface element obtains the various circles of the outer tank wall panel.

4. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 3, characterized in that: The unit type includes a shell unit Shell; Beam unit Beam and solid unit Solid. In the finite element model, the structural parts of the outer tank system adopt the shell unit Shell in the finite element software; the supporting structural parts of the outer tank system adopt the beam unit Beam in the finite element software; the outer tank bottom plate of the outer tank system adopts the solid unit Solid in the finite element software.

5. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 3, characterized in that: The method for setting material properties is: input the density, elastic modulus and Poisson's ratio of the steel respectively according to the actual working conditions of the storage tank, take into account the weight of the insulating glass wool laid on the ceiling deck when assigning the steel density attribute of the ceiling deck, assign unit attributes according to the unit type to assign material numbers to each component, number the unit type, number the real constants, and set the beam unit number.

6. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 3, characterized in that: The meshing method for each unit type is: setting the unit size, specifying the shape of the mesh unit, specifying the meshing type, and continuously iterating and adjusting the meshing according to the calculation results. The meshing method and size adopted are comprehensively compared: the maximum stress value of the outer tank system of the full-capacity liquid ammonia storage tank is used as the evaluation index, and the calculation results are compared with the calculation results of different mesh sizes. The relative change value of the calculation results before and after is within the threshold value as the final mesh size of the model. If the relative change value of the calculation result exceeds the threshold value, the size will be halved and the mesh will be encrypted until the relative change value of the calculation results before and after is within the threshold range.

7. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 1, characterized in that: The load action includes: applying its own gravity, applying design pressure and applying pressure on the side wall of the cold insulation structure; the method of applying load action to the finite element model is: applying design pressure to the outer tank arch plate and the inner wall surface of the outer tank wall plate; applying uniform pressure of the cold insulation structure on the inner wall surface of the outer tank wall plate to the outer tank side wall; applying equivalent force and gravity acceleration to the connecting pipe port; and applying fixed constraints to the outer tank bottom plate.

8. The method for calculating stress of the outer tank system of a full-capacity liquid ammonia storage tank according to claim 1, characterized in that: The method for obtaining the stress and deformation distribution results of the outer tank system is: after solving the finite element model and completing the calculation, the deformation value and stress value of the outer tank system are extracted, the stress distribution and deformation of the structure after bearing the load are obtained, and the maximum stress point is found, so that the stress of the maximum stress point is lower than the stress threshold of the outer tank system.

9. A stress calculation system for the outer tank system of a full-capacity liquid ammonia storage tank, characterized in that: include: An information acquisition module is used to obtain structural information and material information of the outer tank system of the full-capacity liquid ammonia storage tank; a finite element model generation module, for determining the unit type of each structure of the outer tank system according to the structural information, performing geometric modeling according to the structural information, completing a solid model, correcting the unit type of each structure according to the solid model, obtaining real constants, and setting the cross-sectional size of the beam unit, setting the material properties according to the material information, assigning unit attributes according to the unit type, meshing each unit type, and generating a finite element model; The load application module is used to apply load to the finite element model, set boundary conditions, and calculate the finite element model with applied load to obtain stress and deformation distribution results of the outer tank system; and analyze the stress and deformation distribution results to obtain stress distribution results of the outer tank system.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and the computer program is executed by a processor to implement the method for calculating the stress of the outer tank system of a full-capacity liquid ammonia storage tank as described in any one of claims 1-8.

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