Variable-wall-thickness fused salt storage tank wall plate optimization design method and storage tank

Abstract

The invention belongs to the field of storage tanks, and discloses a variable-wall-thickness fused salt storage tank wallboard optimization design method and a storage tank, and the method comprises the steps: firstly, optimizing the thickness of a vault based on a finite element calculation method, and obtaining the optimal wall thickness of the vault meeting the stability requirement under the action of axial pressure; then the minimum wall thickness meeting the stability requirement is obtained through a stress-strain curve of the single-layer wall plate under the combined action of the axial pressure and the hydrostatic pressure and serves as the optimal thickness of the bottom-layer wall plate; and finally, the optimal thickness and the optimal height of each layer of wall plate are iteratively calculated layer by layer from bottom to top based on the optimal thickness of the bottom layer wall plate and the thickness change range of the two adjacent layers of wall plates, and the optimal thickness of the top layer wall plate and the number of layers of the wall plates are obtained by taking the condition that the current wall plate thickness is smaller than the optimal thickness of the vault as an iteration termination condition. Therefore, the wall thickness-variable fused salt storage tank wall plate optimization design is completed; according to the method, the stress-strain curve is used as a stability criterion, so that the structural stability requirement is met, the use of materials is saved, and both the stability and the cost are considered.

Description

Technical Field

[0001] The present invention belongs to the field of heat storage technology, specifically to the field of storage tank technology, and in particular relates to a variable wall thickness molten salt storage tank wall plate optimization design method and a storage tank. Background Art

[0002] In a solar thermal power generation system, the concentrator concentrates sunlight onto the receiver, generating high temperatures. The molten salt in the receiver is heated to a high-temperature liquid state and then transported through a pipeline to a molten salt storage tank for storage. The high temperature of the molten salt can reach several hundred degrees Celsius, so a large amount of thermal energy can be stored to ensure continuous power generation even when there is no sunlight. Storage tanks are usually divided into high-temperature tanks and low-temperature tanks, and the molten salt is stored in a cycle at different temperatures. When power generation is required, the high-temperature molten salt is extracted from the storage tank, and the heat energy is transferred to the working fluid (water or other fluids) through a heat exchanger to generate high-temperature and high-pressure steam. The steam drives the steam turbine to generate electricity, and the cooled molten salt is sent back to the low-temperature storage tank to wait for reheating.

[0003] The molten salt storage tank is the core part of the heat storage system in a solar thermal power station. At the same time, the operating environment of the storage tank is also extremely harsh. High temperature, variable liquid level and thermal stress generated may cause damage to the tank structure, leakage, and serious safety hazards. Due to the huge size of the storage tank, in order to meet the strength requirements and economic requirements, the wall panels of the storage tank are usually designed as variable wall thickness panels. In the prior art, the common variable wall thickness design methods are the fixed point method or the variable point method. The fixed point method or the variable point method are both ideal theoretical design methods. However, the actual tank structure is relatively complex, and the use of theoretical design methods has large errors and cannot guarantee uniform stress distribution; and in actual situations, if the strength performance meets the requirements, the use of the above method will result in large material consumption and a large amount of material waste due to the large errors; therefore, there are many difficulties in the structural design process of the storage tank.

[0004] It can be seen that the existing variable wall thickness molten salt storage tank wall panel design method cannot simultaneously meet the strength performance requirements and save materials due to the actual tank structure and the large error between the design method and the actual situation. Summary of the invention

[0005] The present invention provides a variable wall thickness molten salt storage tank wall plate optimization design method and storage tank, so as to solve the technical problem that the existing variable wall thickness molten salt storage tank wall plate design method cannot simultaneously meet the strength performance requirements and save materials due to the actual tank structure and the large error between the design method and the actual situation.

[0006] In order to achieve the above object, the present invention adopts the following technical contents: A variable thickness molten salt storage tank wall plate optimization design method comprises the following steps: The optimal thickness of the vault of the physical model of the variable wall thickness molten salt storage tank is obtained based on the finite element calculation method; wherein the physical model of the variable wall thickness molten salt storage tank is constructed by the actual tank size; Based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure of the physical model of the variable wall thickness molten salt storage tank, the optimal thickness of the single-layer wall panel is obtained, and the optimal thickness of the single-layer wall panel is used as the optimal thickness of the bottom wall panel. Based on the optimal thickness of the bottom wall panel and the thickness variation range of the two adjacent wall panels, the optimal thickness and optimal height of each wall panel are iteratively calculated layer by layer from bottom to top until the calculated current wall panel thickness is less than the optimal thickness of the vault; the wall panel thickness before the iterative calculation is terminated is used as the optimal thickness of the top wall panel of the physical model of the variable wall thickness molten salt storage tank, and the number of wall panel layers of the physical model of the variable wall thickness molten salt storage tank is obtained at the same time.

[0007] Furthermore, the physical model of the variable-wall-thickness molten salt storage tank includes a dome, multiple layers of variable-wall-thickness wall panels and a bottom plate; the material of the physical model of the variable-wall-thickness molten salt storage tank is stainless steel 347H; in the modeling process of the physical model of the variable-wall-thickness molten salt storage tank, the effects of changes in dome thickness, wall panel thickness and wall panel height on the overall mechanical properties of the tank are considered, and the gravity of the tank, the axial pressure on the tank dome and the hydrostatic pressure on the working fluid in the tank are used as boundary conditions of the physical model of the variable-wall-thickness molten salt storage tank.

[0008] Furthermore, the specific steps of obtaining the optimal thickness of the vault of the physical model of the variable wall thickness molten salt storage tank based on the finite element calculation method are as follows: The dome of the physical model of the variable wall thickness molten salt storage tank is calculated based on the finite element calculation method, and the stress-strain curve corresponding to the dome is obtained; According to the stress-strain curve corresponding to the vault, the optimal thickness of the vault under axial compression is obtained through structural stability judgment; Among them, the basis for judging the structural stability is: when the stress-strain curve changes linearly, it means that the structure is in elastic deformation and has high stability; when the stress-strain curve changes nonlinearly, it means that the structure is in the plastic damage stage and has poor stability; the arch thickness is the minimum thickness of the structure within the elastic deformation range as the optimal thickness of the arch.

[0009] Furthermore, the specific steps of obtaining the optimal thickness of the single-layer wall panel based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure of the physical model of the variable wall thickness molten salt storage tank are as follows: The variable wall thickness molten salt storage tank in the physical model of variable wall thickness molten salt storage tank is regarded as a molten salt storage tank with equal wall thickness; Combined with the finite element calculation method, the stress-strain curve of the single-layer wall of the molten salt storage tank with equal wall thickness under the combined action of axial pressure and hydrostatic pressure is obtained; According to the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure, the minimum wall thickness that meets the stability when the wall thickness is single is obtained, and the minimum wall thickness that meets the stability when the wall thickness is single is taken as the optimal thickness of the single-layer wall panel.

[0010] Furthermore, the specific steps of iteratively calculating the optimal thickness and optimal height of each layer of wallboard from bottom to top based on the optimal thickness of the bottom wallboard and the thickness variation range of the two adjacent wallboards are as follows: S1: According to the optimal thickness of the bottom wall panel and the thickness variation range of the two adjacent wall panels, the preliminary wall thickness of the second wall panel is obtained; S2: According to the preliminary wall thickness of the second layer wall panel and the optimal thickness of the bottom layer wall panel, the stress-strain curves of the bottom layer wall panel at different heights are obtained, and the minimum height that meets the stability is taken as the optimal height of the bottom layer wall panel; S3: According to the stress-strain curve of the thickness of the second wall panel, the minimum thickness that meets the stability is taken as the optimal thickness of the second wall panel; S4: Iteratively calculate the optimal thickness and optimal height of each layer of wall panels layer by layer until the calculated current wall panel thickness is less than the optimal thickness of the vault, and use the wall panel thickness before the iterative calculation is terminated as the optimal thickness of the top wall panel of the variable wall thickness molten salt storage tank physical model and obtain the number of wall panel layers of the variable wall thickness molten salt storage tank physical model.

[0011] Furthermore, the optimal height of the top wall panel is calculated based on the preset total height of the wall panels and the optimal height of each layer of wall panels. The specific formula is as follows: The optimal height of the top wall panel = the total height of the preset wall panels - the sum of the optimal heights of the wall panels on each layer.

[0012] Furthermore, the thickness of two adjacent wall panels varies in the range of 5% to 25%.

[0013] A variable wall thickness molten salt storage tank comprises multiple layers of wall panels with variable wall thickness and is designed by using the above-mentioned variable wall thickness molten salt storage tank wall panel optimization design method.

[0014] Furthermore, it comprises a tank body surrounded by multiple layers of wall panels with variable wall thickness; a bottom plate is arranged at the bottom of the tank body, and a dome is covered on the top; and a windproof ring is sleeved axially on the tank body.

[0015] Furthermore, the arch includes radial beams, annular beams and oblique supports; wherein the radial beams and the annular beams are made of HN350×170 H-shaped steel; and the oblique supports are made of HN250×125 H-shaped steel.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a variable wall thickness molten salt storage tank wall panel optimization design method. The method first optimizes the vault thickness based on the finite element calculation method to obtain the optimal vault wall thickness that meets the stability requirements under axial pressure; then the minimum wall thickness that meets the stability requirements is obtained based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure and is used as the optimal thickness of the bottom wall panel; finally, based on the optimal thickness of the bottom wall panel and the thickness variation range of the adjacent two layers of wall panels, the optimal thickness and optimal height of each layer of wall panel are iteratively calculated layer by layer from bottom to top, and the current wall panel thickness is less than the optimal vault thickness as The iterative termination condition is used to obtain the optimal thickness of the top wall panel and the number of wall panels, thereby completing the optimal design of the variable wall thickness molten salt storage tank wall panel; this method uses the stress-strain curve as the stability criterion, which not only meets the structural stability requirements, but also saves the use of materials under the premise of stability, taking into account both stability and cost; this method combines the finite element calculation method and the layer-by-layer iteration strategy to accurately determine the optimal thickness and height of each layer of the tank wall panel, and maximizes the use of materials, reduces material waste, and reduces costs while ensuring the stability of the tank structure. It has good promotion and application value.

[0017] Preferably, in the present invention, the physical model of the variable wall thickness molten salt storage tank adopts stainless steel 347H, which ensures the corrosion resistance and structural strength of the storage tank in a high temperature molten salt environment; at the same time, the influence of various factors on the mechanical properties of the storage tank is considered in the modeling process, and reasonable boundary conditions are set, so that the model is closer to the actual working conditions, thereby improving the accuracy and reliability of the optimization design.

[0018] Preferably, in the present invention, the safety performance of the arch under axial compression is ensured through finite element calculation and structural stability judgment, avoiding the risk of structural failure due to insufficient thickness, thus providing important basic data support for the optimization design of the entire wall panel.

[0019] Preferably, in the present invention, the optimal thickness of the single-layer wall panel is obtained through finite element calculation. This step fully considers the stress conditions in the actual operation of the tank, ensures the stability and safety of the single-layer wall panel in a complex stress environment, and provides an important basis for the subsequent optimization design of the multi-layer wall panel.

[0020] Preferably, in the present invention, by gradually optimizing the thickness and height of each layer of wall panel, a refined design of the entire tank wall panel structure is achieved; this method not only improves the mechanical properties of the tank, but also reduces the manufacturing cost and weight.

[0021] Preferably, in the present invention, the optimal height of the top wall panel is determined by the difference between the preset total height of the wall panel and the optimal height of each layer of wall panels, ensuring that the height of the top wall panel meets the structural requirements without being too redundant. This further improves the optimization design process of the tank wall panel and improves the scientificity and rationality of the design.

[0022] Preferably, in the present invention, the thickness variation range of two adjacent layers of wall panels is 5% to 25%, which helps to maintain a reasonable variation gradient of the wall panel thickness in the optimized design and avoid stress concentration or structural mutation problems caused by excessive thickness variation; it also provides a guiding basis for the processing accuracy in the actual manufacturing process.

[0023] The present invention also provides a variable-wall-thickness molten salt storage tank, which is designed based on the above-mentioned variable-wall-thickness molten salt storage tank wall panel optimization design method. The tank can significantly improve the mechanical properties of the tank, reduce manufacturing costs and extend the service life through the optimized designed wall panel structure, while taking into account the advantages of good structural performance and material saving; the tank has broad application prospects and important economic value in the molten salt energy storage system.

[0024] Preferably, in the present invention, the storage tank includes a tank body surrounded by multiple layers of variable wall thickness panels, a bottom plate, a dome, a windproof ring and other components; the synergistic effect of these components enables the storage tank to maintain stable operation in harsh natural environments, thereby improving the safety and reliability of the storage tank.

[0025] Preferably, in the present invention, the arch adopts radial beams, annular beams and oblique supports of HN steel, which not only improves the strength and rigidity of the arch, but also ensures the stability and durability of the arch, which is of great significance for improving the mechanical properties and safety performance of the entire storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 A schematic diagram of the overall structure of a storage tank provided in an embodiment of the present invention; Figure 2 A schematic diagram of a vault structure provided by an embodiment of the present invention; Figure 3 A schematic diagram of a curve showing the relationship between the maximum deformation and the maximum stress under different vault thicknesses provided by an embodiment of the present invention; wherein (a) is a schematic diagram showing the maximum deformation and the maximum stress under different vault thicknesses; (b) is a cloud diagram showing the deformation of the vault; and (c) is a cloud diagram showing the stress of the vault; Figure 4 A schematic diagram of the maximum deformation and maximum stress curve of a tank wall of equal wall thickness under the combined action of axial pressure and hydrostatic pressure provided in an embodiment of the present invention; Figure 5 A schematic diagram of a maximum deformation and stress change curve of adjacent wall thickness changes provided by an embodiment of the present invention; Figure 6 A schematic diagram of maximum deformation and stress variation curves of different wall panel heights of the first layer provided by an embodiment of the present invention; Figure 7 A schematic diagram of maximum deformation and stress variation curves of the second layer with different wall panel thicknesses provided by an embodiment of the present invention; Figure 8A schematic diagram of maximum deformation and stress variation curves of the second layer with different wall panel heights provided by an embodiment of the present invention; Fig. 9 A schematic diagram of maximum deformation and stress variation curves of the third layer with different wall panel thicknesses provided by an embodiment of the present invention; Fig.10 A schematic diagram of maximum deformation and stress variation curves of different wall panel heights of the third layer provided by an embodiment of the present invention; Fig.11 A schematic diagram of maximum deformation and stress variation curves of the fourth layer with different wall panel thicknesses provided by an embodiment of the present invention; Fig.12 A schematic diagram of maximum deformation and stress variation curves of different wall panel heights of the fourth layer provided by an embodiment of the present invention; Fig.13 A schematic diagram of maximum deformation and stress variation curves of the fifth layer with different wall panel thicknesses provided by an embodiment of the present invention; Fig.14 A schematic diagram of maximum deformation and stress variation curves of different wall panel heights of the fifth layer provided by an embodiment of the present invention; Fig.15 A schematic diagram of maximum deformation and stress variation curves of the sixth layer with different wall panel thicknesses provided by an embodiment of the present invention; Fig.16 A schematic diagram of maximum deformation and stress variation curves of different wall panel heights of the sixth layer provided by an embodiment of the present invention; Fig.17 A schematic diagram of maximum deformation and stress variation curves of the seventh layer with different wall panel thicknesses provided by an embodiment of the present invention; Fig.18 A flow chart of a method for optimizing the design of variable-thickness molten salt storage tank wall panels provided in an embodiment of the present invention.

[0027] Reference numerals: Base plate-1; wall plate-2; wind-resistant ring-3; arch-4; radial beam-5; annular beam-6; inclined support-7. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Example 1 As mentioned in the background technology, the operating environment of the storage tank is extremely harsh. High temperature, variable liquid level and thermal stress generated may cause damage to the storage tank structure, leakage, and serious safety hazards. Due to the huge size of the storage tank, in order to meet the strength requirements and economic requirements, the wall plate of the storage tank is designed as a variable wall thickness wall plate. At present, the design of the storage tank mainly refers to the variable point method design, especially the height design of the storage tank wall plate, most of which use 1.8m-2.8m as a fixed value. Therefore, optimizing the design of the storage tank can effectively improve the operation stability and reduce the material cost. In the prior art, the common design method is the fixed point method or the variable point method, but the actual storage tank structure is relatively complex, and there is a large error in the theoretical design method, and there are many difficulties in the structural design process of the storage tank. In addition, more importantly, the existing variable wall thickness molten salt storage tank wall plate design method is difficult to take into account the problem of structural performance and material saving.

[0036] In order to solve the above problems, the present invention provides a variable wall thickness molten salt storage tank wall plate optimization design method. The method is based on the finite element calculation method and is a variable wall thickness molten salt storage tank design optimization method that performs stability judgment through stress-strain curves. The storage tank designed using this method can improve structural stability, save manufacturing materials, and reduce manufacturing costs.

[0037] The present invention is further described in detail below with reference to the accompanying drawings and embodiments: like Fig.18 As shown, this embodiment provides a method for optimizing the design of variable wall thickness molten salt storage tank wall panels, and the specific steps include: The optimal thickness of the vault 4 of the physical model of the variable wall thickness molten salt storage tank is obtained based on the finite element calculation method; wherein the physical model of the variable wall thickness molten salt storage tank is constructed by the actual tank size; Based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure of the physical model of the variable wall thickness molten salt storage tank, the optimal thickness of the single-layer wall panel is obtained, and the optimal thickness of the single-layer wall panel is used as the optimal thickness of the bottom wall panel. Based on the optimal thickness of the bottom wall panel and the thickness variation range of the two adjacent wall panels, the optimal thickness and optimal height of each wall panel are iteratively calculated layer by layer from bottom to top until the calculated current wall panel thickness is less than the optimal thickness of the vault 4; the wall panel thickness before the iterative calculation is terminated is used as the optimal thickness of the top wall panel of the variable wall thickness molten salt storage tank physical model, and the number of wall panel layers of the variable wall thickness molten salt storage tank physical model is obtained at the same time.

[0038] In this embodiment, a physical model of a molten salt storage tank with variable wall thickness corresponding to the actual tank size is established. This model takes into account structures such as the tank vault, variable wall thickness wall plate and bottom plate. The material selected is stainless steel 347H, which is a common material for actual solar thermal power station tanks. Considering the nonlinearity of the material, the interior of the tank is a uniform medium, and it is assumed that the density and elastic modulus do not change with temperature. For the boundary conditions, the gravity of the tank, the axial pressure on the tank vault, and the hydrostatic pressure of the working fluid in the tank are considered, and a fixed constraint is imposed on the bottom surface of the tank bottom plate. In addition, in the modeling process, the effects of changes in the vault thickness, the wall plate thickness, and the wall plate height on the overall mechanical properties of the tank are considered.

[0039] In this embodiment, the physical model of the variable wall thickness molten salt storage tank is based on the finite element calculation method. First, the optimal thickness of the vault is determined under axial pressure. The optimal thickness is obtained by stability judgment through the stress-strain curve obtained by finite element analysis. The judgment basis of structural stability is: when the stress-strain curve changes linearly, it means that the structure is in elastic deformation and has high stability. When the stress-strain curve changes nonlinearly, it means that the structure is in the plastic damage stage and the structure is likely to become unstable, which should be avoided. After the minimum thickness of the vault is determined, this thickness is used as the critical thickness of the wall panel thickness change, that is, the thickness of the top wall panel should be greater than or equal to the vault thickness.

[0040] Then, considering the mechanical stability of the variable wall thickness under the action of axial pressure + hydrostatic pressure, the optimal wall thickness that satisfies the stability when the overall wall thickness is single layer is determined first, and this optimal wall thickness is used as the thickness of the bottom layer of the variable wall thickness tank. Secondly, the optimal thickness and height of the second layer of wall panels are determined by the layer-by-layer iteration method, and then the iterative calculation is performed upwards in sequence to obtain the optimal thickness and height of each layer of wall panels. The number of layers is determined based on: when the thickness of the wall panel is less than or equal to the thickness of the vault, the iteration is terminated, and the height of the topmost wall panel is the design height minus the optimal height of each wall panel. Finally, the optimal wall panel combination that satisfies the stability of the tank is obtained. Idea of ​​layer-by-layer iteration method: First, the different thicknesses of the entire tank under axial pressure + hydrostatic pressure loads are studied to determine the thickness range of the wall panel. The minimum wall panel thickness should be greater than the arch thickness under axial pressure. The different wall thicknesses under axial pressure + hydrostatic pressure, the minimum wall thickness that meets the stability conditions is used as the first layer of wall panel thickness (bottom layer wall panel thickness) of the tank. At the same time, the stress-strain curve of the thickness change of adjacent wall panels is obtained through finite element calculation, and the thickness change of two adjacent wall panels is obtained through stability criterion. The thickness change of two adjacent wall panels should be 5%-25%. Assume that the thickness change of the second layer of wall panel is 5% of the thickness change of the first layer of wall panel, and then change the height of the first layer of wall panel, determine the height of the first layer of wall panel through the stress-strain curve, and then determine the thickness of the second layer of wall panel. The maximum wall thickness change of the second layer is 25% of the thickness of the first layer of wall panel. Similarly, the number of wall panel layers can be determined; that is, the calculated current wall panel thickness is less than the optimal thickness of the arch 4, and the wall panel thickness before the iterative calculation is terminated is used as the optimal thickness of the top wall panel of the variable wall thickness molten salt storage tank physical model, and the number of wall panel layers of the variable wall thickness molten salt storage tank physical model is obtained.

[0041] Example 2 This embodiment provides a specific implementation process of a variable wall thickness molten salt storage tank wall plate optimization design method and a variable wall thickness molten salt storage tank. The technical solution mentioned in this embodiment is specifically described below in conjunction with the accompanying drawings: like Figure 1 and Figure 2 As shown, this embodiment provides a variable wall thickness molten salt storage tank, including a tank bottom plate 1, which is a thin-walled circular structure; the wall plate 2 of the tank body adopts a stepped wall plate, each layer adopts a variable wall thickness design, the bottom wall plate is the thickest, and the top wall is covered with a vault structure 3; the wall plate 2 is axially sleeved with a wind-resistant ring 4; the wind-resistant ring 4 is composed of two annular wall plates to reinforce the wall plate 2, and the vault structure 3 includes radial beams 5, annular beams 6 and oblique supports 7; the radial beams 5 are composed of 60 H-shaped steels of HN350×170, which are equidistant along the circumference of the sphere; the annular beams 6 are also composed of 11 H-shaped steels of HN350×170; the oblique supports 7 are composed of 4 groups of H-shaped steels of HN250×125.

[0042] This variable wall thickness molten salt storage tank is designed by adopting the following variable wall thickness molten salt storage tank variable wall thickness molten salt storage tank wall plate optimization design method.

[0043] This embodiment also provides a variable wall thickness molten salt storage tank wall plate optimization design method, which is as follows: Firstly, a physical model of a molten salt storage tank with variable wall thickness is constructed according to the actual tank size. In the physical model of the molten salt storage tank with variable wall thickness, the thickness and height of each layer are optimized and the number of final wall panels is determined.

[0044] like Figure 3 As shown, specifically Figure 3 As shown in Figures (a), (b) and (c), the relationship curves between the maximum deformation and the maximum stress under different arch thicknesses. It can be seen from Figure (a) that when the arch thickness is less than 14 mm, the stress-strain curve shows a nonlinear change, that is, the stress change is very small, and the deformation change is large. When the arch thickness is greater than 14 mm, the maximum deformation and maximum stress curves are straight lines, which are within the elastic range and have good structural stability. Therefore, it can be seen from Figure (a) that the thickness of the arch should be greater than 14 mm. The arch thickness of this embodiment is designed to be 14 mm. From the displacement and stress cloud diagrams of Figures (b) and (c), it can be seen that the maximum deformation occurs in the center of the arch and the maximum stress occurs at the edge.

[0045] like Figure 4 As shown in the figure, it is the stress-strain curve of the equal wall thickness tank when the axial pressure and hydrostatic pressure act together. It can be obtained from the stress-strain curve that when the wall thickness is less than 48mm, the stress-strain curve shows a nonlinear change. When the tank wall thickness is greater than or equal to 48mm, the stress-strain curve has good linearity, the tank is within the elastic deformation range, and the structure is stable. Therefore, the maximum wall thickness of the variable wall thickness tank designed in this paper is selected as 48mm.

[0046] Figure 5 As shown, it is a stress-strain curve diagram of the change of adjacent wall thickness. When the adjacent wall thickness changes by 25%, the stress-strain curve shows a nonlinear change and does not meet the stability requirement. Therefore, this embodiment stipulates that the thickness change of two adjacent wall panels is 5%-25%.

[0047] like Figure 6 As shown in the figure, the stress-strain curves of the first layer of wall panels (i.e., the bottom layer of wall panels) at different heights. When the height of the first layer of wall panels varies between 0.05 and 2 m, when the height of the wall panels is greater than 0.5 m, the stress-strain curves show a linear relationship, which meets the stability requirements. Therefore, the height of the first layer is determined to be 0.5 m. Figure 4 The thickness of the first layer is 48 mm. Figure 5 It can be obtained that the second layer wall thickness variation range is 5%-25%, and the second layer wall thickness variation range is 38mm-46mm. At this time, it is assumed that the thickness of the second layer wall panel is 46mm.

[0048] like Figure 7 The stress-strain curves of the second wall panel with different wall thicknesses are shown in Figure 2. The thickness of the second wall panel varies from 38mm to 46mm. Figure 7 From the stress-strain curve, it can be obtained that when the thickness of the second layer of wall panel is 46mm, the stress-strain curve is basically linear. Through the stability criterion, it can be obtained that the thickness of the second layer of wall panel is 46mm; at this time, the thickness of the third layer of wall panel varies from 35mm to 44mm, assuming that the thickness of the third layer of wall panel is 44mm.

[0049] Figure 8 As shown in the figure, it is the stress-strain curve of the second layer wall panel at different heights. When the height of the second layer wall panel varies between 0.05 and 2m, it can be obtained from the stress-strain curve that when the height of the second layer wall panel is greater than or equal to 0.1m, the stress-strain curve basically satisfies the linear change, so the height of the second layer wall panel is selected as 0.1m.

[0050] Fig. 9 As shown, it is the stress-strain curve of the third layer wall panel under different wall thicknesses. When the thickness of the third layer wall panel is greater than 41mm, the stress-strain curve basically satisfies the linear relationship, so the optimal thickness of the third layer wall panel is selected as 41mm. At this time, the thickness of the fourth layer wall panel varies from 31mm to 39mm. It is assumed that the thickness of the fourth layer wall panel is 39mm.

[0051] Fig.10 As shown, it is the stress-strain curve of the third layer wall panel at different heights. Through the stability criterion, it can be obtained that when the height of the third layer wall panel is greater than or equal to 0.5m, the stress-strain curve basically satisfies the linear relationship, so the height of the third layer wall panel is determined to be 0.5m.

[0052] Fig.11 As shown in the figure, the stress-strain curves of the fourth wall panel at different thicknesses are basically linear, that is, the minimum wall panel thickness can still meet the stability requirements, so the thickness of the fourth wall panel is determined to be 31mm. At this time, the thickness of the fifth wall panel varies from 24mm to 30mm, assuming that the thickness of the fifth wall panel is 30mm.

[0053] Fig.12 As shown, it is the stress-strain curve under the change of the height of the fourth wall panel. At different wall panel heights, the stress-strain curve is linearly related, so the optimal wall panel height of the fourth wall panel is selected as 0.05m.

[0054] Fig.13As shown in the figure, the stress-strain curves of the fifth wall panel at different thicknesses are obtained. It can be seen that the stress-strain curves at different thicknesses basically satisfy the linear relationship, so the minimum wall thickness is the optimal wall thickness, which is 24mm. At this time, the thickness of the sixth wall panel varies from 18mm to 23mm, assuming that the thickness of the sixth wall panel is 23mm.

[0055] Fig.14 As shown, these are the stress-strain curves of the fifth wall panel at different heights. It can be seen that the stress-strain curves at different heights basically satisfy a linear relationship, so the height of the fifth wall panel is selected to be 0.05m.

[0056] Fig.15 As shown in the figure, the stress-strain curves of the sixth wall panel at different thicknesses are obtained. It can be seen that the stress-strain curves at different thicknesses basically satisfy the linear relationship, so the minimum wall thickness is the optimal wall thickness, which is 18mm. At this time, the thickness of the seventh wall panel varies from 14mm to 17mm, assuming that the thickness of the seventh wall panel is 17mm.

[0057] Fig.16 As shown in Figure 1, the stress-strain curves of the sixth wall panel at different heights are shown. It can be seen that the stress-strain curves at different heights basically satisfy the linear relationship, so the height of the sixth wall panel is selected to be 0.05m.

[0058] Fig.17 As shown in the figure, it is the stress-strain curve of the seventh layer wall at different thicknesses. It can be obtained that the stress-strain curves at different thicknesses basically satisfy the linear relationship, so the optimal wall thickness of the seventh layer is determined to be 14mm. Since the wall thickness of the arch 4 under axial pressure is determined to be 14mm, the minimum thickness of the tank wall cannot be less than 14mm. When the thickness of the highest layer is less than 14mm, in order to ensure that the design capacity remains unchanged, the height is the design height minus the determined wall height.

[0059] Here, when the thickness of the eighth layer of wall panels is calculated again, since the thickness of the eighth layer of wall panels is less than the thickness of the arch 4 wall panels, it cannot meet the structural stability requirements and the iteration is terminated; therefore, the previous wall panel thickness of 14 mm is iteratively calculated as the optimal thickness of the top wall panel, and it can be confirmed that the number of wall panel layers of this variable wall thickness molten salt storage tank physical model is seven.

[0060] Compared with the variable-thickness molten salt storage tank wall optimization design method and the variable-point method design, the finite element calculation method meets the stability conditions of the storage tank and also reduces the material cost. The tank wall material of a single hot molten salt storage tank is reduced by 165.34 tons, as shown in Table 1.

[0061] Table 1 is a comparison table of storage tank designs

[0062] It can be seen that the variable wall thickness molten salt storage tank wall plate optimization design method provided in this embodiment has the following advantages: (A) For the vault structure under axial compression, the optimal vault thickness that satisfies stability is determined.

[0063] (B) Compared with the thickness of the wall panels with equal wall thickness, this method is used to determine the minimum wall panel thickness that meets stability requirements.

[0064] (C) By comparing the thickness and height of the variable thickness wall panels, the optimal variable thickness wall panel combination that meets stability is determined.

[0065] (D) The variable wall thickness tank wall plate has a reasonable design, simple structure, and is easy to implement, and can be widely used in actual engineering.

[0066] In summary, the present invention provides a variable wall thickness molten salt storage tank wall plate optimization design method, which has the following advantages compared with the existing design methods: First, this method optimizes the thickness of the vault and selects a minimum wall thickness that meets the stability requirements under axial compression.

[0067] Second, this method optimizes the thickness of the wall plate with equal wall thickness, selects the optimal wall thickness that meets the stability requirements under the coupling of axial pressure and hydrostatic pressure, and uses this wall thickness as the maximum thickness of the wall plate with variable wall thickness.

[0068] Third, this method optimizes the thickness and height of the variable wall panel and uses the stress-strain curve to make a stability criterion, thus obtaining a method that meets the stability requirements and saves materials.

[0069] The above embodiment is only one of the implementation methods that can realize the technical solution of the present invention. The scope of protection claimed by the present invention is not limited only to this embodiment, but also includes changes, replacements and other implementation methods that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention.

Claims

1. A variable thickness molten salt storage tank wall optimization design method, characterized in that: The steps include: Obtaining the optimal thickness of the dome (4) of the physical model of the variable wall thickness molten salt storage tank based on the finite element calculation method; wherein the physical model of the variable wall thickness molten salt storage tank is constructed based on the actual tank size; Based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure of the physical model of the variable wall thickness molten salt storage tank, the optimal thickness of the single-layer wall panel is obtained, and the optimal thickness of the single-layer wall panel is used as the optimal thickness of the bottom wall panel. Based on the optimal thickness of the bottom wall panel and the thickness variation range of the two adjacent wall panels, the optimal thickness and optimal height of each wall panel are iteratively calculated layer by layer from bottom to top until the calculated current wall panel thickness is less than the optimal thickness of the vault (4); the wall panel thickness before the iterative calculation is terminated is used as the optimal thickness of the top wall panel of the variable wall thickness molten salt storage tank physical model, and the number of wall panel layers of the variable wall thickness molten salt storage tank physical model is obtained at the same time.

2. The variable thickness molten salt storage tank wall panel optimization design method according to claim 1 is characterized in that: The variable wall thickness molten salt storage tank physical model comprises a dome (4), a multi-layer variable wall thickness wall plate (2) and a bottom plate (1); the material of the variable wall thickness molten salt storage tank physical model is stainless steel 347H; in the modeling process of the variable wall thickness molten salt storage tank physical model, the influence of the change of the dome thickness, the wall plate thickness and the wall plate height change on the overall mechanical properties of the storage tank is considered, and the gravity of the storage tank, the axial pressure on the dome of the storage tank and the hydrostatic pressure on the working medium in the storage tank are used as the boundary conditions of the variable wall thickness molten salt storage tank physical model.

3. The variable thickness molten salt storage tank wall plate optimization design method according to claim 1 is characterized in that: The specific steps of obtaining the optimal thickness of the vault (4) of the physical model of the variable wall thickness molten salt storage tank based on the finite element calculation method are as follows: The dome (4) of the physical model of the variable wall thickness molten salt storage tank is calculated based on the finite element calculation method to obtain the stress-strain curve corresponding to the dome (4); According to the stress-strain curve corresponding to the arch (4), the optimal thickness of the arch (4) under axial compression is obtained through structural stability judgment; The judgment basis of the structural stability is as follows: when the stress-strain curve changes linearly, it indicates that the structure is in elastic deformation and has high stability; when the stress-strain curve changes nonlinearly, it indicates that the structure is in the plastic damage stage and has poor stability; the thickness of the arch (4) is the minimum thickness within the elastic deformation range of the structure as the optimal thickness of the arch (4).

4. The variable thickness molten salt storage tank wall panel optimization design method according to claim 1 is characterized in that: The specific steps of obtaining the optimal thickness of the single-layer wall panel based on the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure of the variable wall thickness molten salt storage tank physical model are as follows: The variable wall thickness molten salt storage tank in the physical model of variable wall thickness molten salt storage tank is regarded as a molten salt storage tank with equal wall thickness; Combined with the finite element calculation method, the stress-strain curve of the single-layer wall of the molten salt storage tank with equal wall thickness under the combined action of axial pressure and hydrostatic pressure is obtained; According to the stress-strain curve of the single-layer wall panel under the combined action of axial pressure and hydrostatic pressure, the minimum wall thickness that meets the stability when the wall thickness is single is obtained, and the minimum wall thickness that meets the stability when the wall thickness is single is taken as the optimal thickness of the single-layer wall panel.

5. The variable thickness molten salt storage tank wall plate optimization design method according to claim 1 is characterized in that: The specific steps of iteratively calculating the optimal thickness and optimal height of each layer of wallboard from bottom to top based on the optimal thickness of the bottom wallboard and the thickness variation range of the two adjacent wallboards are as follows: S1: According to the optimal thickness of the bottom wall panel and the thickness variation range of the two adjacent wall panels, the preliminary wall thickness of the second wall panel is obtained; S2: According to the preliminary wall thickness of the second layer wall panel and the optimal thickness of the bottom layer wall panel, the stress-strain curves of the bottom layer wall panel at different heights are obtained, and the minimum height that meets the stability is taken as the optimal height of the bottom layer wall panel; S3: According to the stress-strain curve of the thickness of the second wall panel, the minimum thickness that meets the stability is taken as the optimal thickness of the second wall panel; S4: Iteratively calculate the optimal thickness and optimal height of each wall panel layer by layer until the calculated current wall panel thickness is less than the optimal thickness of the dome (4), and use the wall panel thickness before the iterative calculation is terminated as the optimal thickness of the top wall panel of the variable wall thickness molten salt storage tank physical model and obtain the number of wall panel layers of the variable wall thickness molten salt storage tank physical model.

6. The variable thickness molten salt storage tank wall plate optimization design method according to claim 5 is characterized in that: The optimal height of the top wall panel is calculated based on the preset total height of the wall panels and the optimal height of each layer of wall panels. The specific formula is as follows: The optimal height of the top wall panel = the total height of the preset wall panels - the sum of the optimal heights of the wall panels on each layer.

7. The variable thickness molten salt storage tank wall plate optimization design method according to claim 1 is characterized in that: The thickness variation range of two adjacent wall panels is 5% to 25%.

8. A variable wall thickness molten salt storage tank, characterized in that: The variable wall thickness molten salt storage tank comprises multiple layers of variable wall thickness wall panels (2), and is designed using the variable wall thickness molten salt storage tank wall panel optimization design method as described in claims 1 to 7.

9. The variable wall thickness molten salt storage tank according to claim 8, characterized in that: The invention comprises a tank body surrounded by multiple layers of wall panels (2) with variable wall thickness; a bottom plate (1) is arranged at the bottom of the tank body, and a dome (4) is covered on the top; and a windproof ring (3) is sleeved axially on the tank body.

10. The variable wall thickness molten salt storage tank according to claim 9, characterized in that: The arch (4) comprises radial beams (5), annular beams (6) and oblique supports (7); wherein the radial beams (5) and the annular beams (6) are made of HN350×170 H-shaped steel; and the oblique supports (7) are made of HN250×125 H-shaped steel.

Images