A method and structure for hierarchical arrangement of heating coils in a large storage tank

Abstract

The present invention relates to the technical field of large storage tank heating, and particularly to a hierarchical layout method and structure for heating coils of a large storage tank; it includes the following steps: S1. Determine the structural parameters of the storage tank and the material process parameters, and extract them; S2. According to the structural parameters of the storage tank and the material process parameters extracted in step S1, construct a physical simulation calculation model, and then use CFD software to perform simulation calculations on the physical simulation calculation model to obtain the boundary layer drift position, the velocity boundary thickness, and the average temperature of the liquid raw material in the storage tank; S3. Determine the setting position range of the heating coils according to the boundary layer drift position; according to the velocity boundary thickness and the average temperature of the liquid raw material in the storage tank, perform iteration to successively determine the layout positions of n layers of heating coils. When the iteration termination condition is met, stop the iteration and complete the layout of the heating coils; the present invention has a high design accuracy for the heating coils, and enables a strong temperature uniformity in the large storage tank.

Description

Technical Field

[0001] The present invention relates to the technical field of large storage tank heating, and particularly to a layered layout method and structure of a heating coil in a large storage tank. Background Art

[0002] As an auxiliary heating and heat preservation measure, it is a part that needs to be considered in the design of chemical raw material storage tanks. During the chemical production process, a large amount of chemical raw materials or chemical products need to be stored in storage tanks. Traditional storage tanks are placed outdoors and are greatly affected by the ambient temperature. Especially in cold winters, they dissipate heat to the outside world faster. The fluctuating temperature conditions are difficult to meet the storage requirements of chemical raw materials. Usually, when storing high-melting-point chemical raw material liquids in large storage tanks, a corresponding heating and heat preservation system needs to be configured to maintain a stable temperature and prevent raw material crystallization due to the low-temperature environment. Therefore, it is of great significance to reasonably design the corresponding heating system to improve the utilization rate of chemical raw materials and the thermal energy utilization efficiency, save costs for enterprises, reduce energy consumption and emissions, and improve the production efficiency of chemical raw materials. There are many heating and heat preservation methods for large storage tanks. Coils can be used for in-tank heating, and electric tracing, external coils, and external circulation of materials and media can be used for out-of-tank heating. Currently, the single tank capacity of the stored materials is large, and the cost of the external coil heating method for storage tanks is very high; the energy consumption of electric tracing is relatively high compared to steam and hot water heating and heat preservation, and electric tracing is prone to breakpoints, and the maintenance cost is also high; while the in-tank coil heating or external heat exchanger circulation heating effect is good, effectively utilizing the heat source, and is widely used in the heating and heat preservation system.

[0003] The existing designs of large storage tank heating layouts often focus on different heating coil structures and layout forms. The built-in heating coils are often arranged at the bottom of the storage tank for heating and heat preservation considering the simplicity of construction. There are also often design schemes with stratified arrangement of heating coils applied to the heating of storage tanks for high-viscosity fluids, such as crude oil, asphalt, etc. Currently, the design of coil layout mainly relies on energy constant calculation and empirical formulas to calculate the relationship between the heat consumption required by the storage tank and the heat transfer area of the heating coil. However, there is no relatively clear guiding direction for how to specifically design the stratification.

[0004] Currently, empirical formulas are commonly used in engineering to calculate the heat dissipation and temperature drop of storage tanks. Currently, the design of coil layout mainly starts from the chemical perspective. According to experiments or experience, the heat loss per unit area under a fixed temperature difference is calculated and converted into a convective heat transfer coefficient, so as to obtain the lost heat. Then, based on the lost heat, empirical estimation is carried out for heat preservation design. The design of heating coils mainly depends on the empirical value of the convective heat transfer coefficient, and most empirical formula calculations will ignore the influence of heat convection and heat radiation, resulting in large errors. And the temperature drop of the materials in the storage tank is a non-steady heat transfer process. The results predicted by empirical formulas are quite different from the actual situation, and the empirical formulas cannot give the temperature drop law of the materials in the tank and cannot guide actual production.

[0005] Since a smaller selected pipe diameter is more beneficial to heat transfer, but an overly small pipe diameter will increase the flow resistance inside the pipe and the number of parallel pipes required will increase. Therefore, the commonly used pipe diameters are generally in the range of DN25 - 65, which can prevent excessive pressure drop inside the coil and limit the flow velocity inside the pipe to 0.3 - 0.8 m / s. For gases, the mass flow rate is controlled at 3 - 10 kg / m 2. s. Generally, the height between the upper and lower heating coils is set at 1.5 - 2do (do is the outer diameter of the coil). The heating area of the coil, the selection of coil size, the height from the ground, and the distance from the wall surface are designed based on empirical values, without corresponding theoretical basis to support, and cannot be fully applied to heating storage tanks of different sizes and designs.

[0006] Currently, the design research of heating coils mainly focuses on the heating of asphalt, crude oil, and LNG natural gas. However, the storage and transportation of chemical raw materials also require good heat preservation and heating designs to maintain the temperature of chemical materials. Generally, the heating coils of large storage tanks are spirally laid flat at the bottom. After the liquid is heated, a density difference is generated for convection, and the heat transfer efficiency is relatively low. It takes a long time to operate at low temperatures to maintain the temperature stability inside the tank. Currently, to solve the problem that the bottom liquid is heated quickly while the upper part is not easily heated, the main method is to set heating pipes in layers and set temperature sensors at different heights for heating control. However, this method often estimates the layer height based on experience, resulting in waste of heat energy and high costs.

[0007] Therefore, there is an urgent need to provide a method and structure for layered arrangement of heating coils in large storage tanks, which can reduce the design error and make the heating temperature uniform compared with the existing technology. Summary of the Invention

[0008] The present invention solves the technical problems existing in the prior art and provides a method and structure for layered arrangement of heating coils in large storage tanks.

[0009] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0010] A method for layered arrangement of heating coils in large storage tanks includes the following steps:

[0011] S1. Determine the structural parameters of the storage tank and the process parameters of the material, and extract them;

[0012] S2. According to the structural parameters of the storage tank and the process parameters of the material extracted in step S1, construct a physical simulation calculation model, and then use CFD software to perform simulation calculations on the physical simulation calculation model to obtain the boundary layer deflection position, velocity boundary thickness, and average temperature of the liquid raw material inside the storage tank;

[0013] S3. Determine the installation position range of the heating coils according to the position of the boundary layer drift; perform iteration based on the velocity boundary thickness and the average temperature of the liquid raw material in the storage tank to successively determine the layout positions of the n layers of heating coils. When the iteration termination condition is met, stop the iteration to complete the layout of the heating coils.

[0014] Further, S2 specifically includes the following steps:

[0015] S21. According to the storage tank structure parameters and material process parameters extracted in step S1, perform model simplification and three-dimensional modeling of the storage tank to obtain a three-dimensional model of the storage tank;

[0016] S22. Make physical assumptions, and perform simulation on the three-dimensional model of the storage tank according to the physical assumptions to obtain a physical simulation calculation model;

[0017] S23. Use CFD software to perform simulation calculation on the operation data of the physical simulation calculation model to obtain the position of the boundary layer drift, the velocity boundary thickness, and the average temperature of the liquid raw material in the storage tank without installing the heating coils.

[0018] Furthermore, the physical assumptions in step S22 include satisfying the mass conservation equation, the momentum conservation equation, the energy conservation equation, and natural convection in the tank.

[0019] Furthermore, the model simplification method in step S21 is: remove the internal components of the storage tank and only perform three-dimensional modeling on the storage tank without internal components.

[0020] Furthermore, S3 specifically includes the following steps:

[0021] S31. Set the position of the boundary layer drift obtained in step S2 as the installation position range of the heating coils;

[0022] S32. Calculate the position of the first layer of heating coils according to the velocity boundary layer thickness obtained in step S2;

[0023] S33. Add the structure of the first layer of heating coils to the physical simulation calculation model in step S2, and use the method in step S23 to obtain the updated velocity boundary thickness and the average temperature of the liquid raw material in the storage tank; judge whether the updated average temperature of the liquid raw material in the storage tank meets the iteration termination condition. If it meets, terminate the iteration to complete the layout of the heating coils. If it does not meet, perform step S34;

[0024] S34. Calculate the position of the second layer of heating coils according to the updated velocity boundary thickness in step S33;

[0025] S35. Repeat steps S33 - S34 to determine the positions of the next layers of heating coils, thereby completing the layout of all heating coils.

[0026] Furthermore, the position of the i-th layer of heating coils is calculated by a dimensionless size correlation, specifically:

[0027] ;

[0028] ;

[0029] ;

[0030] In the above formula, represents the abscissa of the i-th layer of heating coils, represents the velocity boundary thickness corresponding to the i-th layer of heating coils, represents the radius of the storage tank, represents the ordinate of the i-th layer of heating coils, represents the total number of heating coils when the i-th layer of heating coils is installed, A, B, and C are all constants. A is taken as 0.00783, B is taken as 1.207, and C is taken as 0.0121. represents the viscosity of the liquid outside the heating coils, represents the liquid level height in the storage tank, represents the density of the liquid outside the heating coils, represents the overall flow rate of the chemical raw materials in the storage tank under natural convection.

[0031] Furthermore, the iteration termination condition is: set the temperature set value, and when the average temperature of the liquid raw materials in the storage tank reaches the temperature set value, the iteration terminates.

[0032] Further, in step S1, the storage tank structure parameters include the storage tank radius, storage tank height, storage tank wall thickness, insulation layer thickness, ambient temperature, heating coil inlet temperature, heating coil outlet temperature, material temperature, air layer gap, filling coefficient; the material process parameters include initial / final temperature, qualitative temperature, specific heat, viscosity, density, thermal conductivity.

[0033] A hierarchical layout structure of heating coils for a large storage tank, including a tank body and multiple layers of heating coils, and the multiple layers of heating coils are arranged on the tank body by using a hierarchical layout method of heating coils for a large storage tank.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] (1) After adding the heating coil in the present invention, the number of vortices in the flow field inside the storage tank increases significantly, which is beneficial to enhancing the thermal convection movement of the materials inside the tank, making the temperature distribution of the materials uniform. Compared with the existing heating coil design methods, the method proposed in the present invention arranges the heating coils by relying on the velocity drift, which can effectively improve the problem of stagnant flow on the storage tank wall surface, improve the uniformity of the internal temperature heating of the storage tank, thereby improving the thermal utilization efficiency, and at the same time can also avoid design errors.

[0036] (2) By combining CFD fluid calculation in the present invention, the obtained convective heat transfer coefficient is relatively accurate, and it can give the movement situation of the flow field and the temperature field distribution inside the storage tank. At the same time, arranging the heating coils at the boundary layer drift can efficiently compensate for the heat loss, effectively improve the problem of flow dead zones in local areas, maintain a stable temperature inside the tank, and can give a relatively accurate design basis for the heating coil structure.

[0037] (3) By combining the ideas of heat transfer and fluid mechanics in the present invention, dimensionless size correlation formulas for physical parameters such as the storage tank diameter, storage tank height, heating coil spacing, and flow boundary layer thickness are proposed, and the general law of the boundary layer drift direction is pointed out, solving the problems of large design errors in traditional empirical designs, inability to intuitively study the changes in the flow field and temperature field inside the storage tank, and waste of thermal energy, and can quickly and intuitively provide a design scheme. Description of the Drawings

[0038] Figure 1 is the flow chart of the method of the present invention.

[0039] Figure 2 is the schematic diagram of the storage tank structure without internal components of the present invention.

[0040] Figure 3 is the velocity distribution nephogram when no heating coil is arranged in the present invention.

[0041] Figure 4 is the schematic diagram of the temperature distribution at the near-wall surface when no heating coil is arranged in the present invention.

[0042] Figure 5 is the velocity distribution nephogram after arranging the first layer of heating coils in the present invention.

[0043] Figure 6 is the velocity distribution nephogram after arranging the second layer of heating coils in the present invention.

[0044] Figure 7 is the velocity distribution nephogram after arranging the third layer of heating coils in the present invention.

[0045] Figure 8 is the velocity distribution nephogram after arranging the fourth layer of heating coils in the present invention.

[0046] Figure 9It is the velocity distribution contour map after arranging the fifth layer of heating coils in the present invention.

[0047] Figure 10 It is a schematic diagram of the relationship between the number of heating coils and the dimensionless height of the axial arrangement in the present invention.

[0048] Figure 11 It is a schematic diagram of the structure of the present invention.

[0049] Explanation of reference numerals:

[0050] 1. Tank top; 2. Tank wall; 3. Tank bottom; 4. Gas phase region; 5. Liquid phase region; 6. Tank body; 7. Heating coil. Detailed implementation manners

[0051] Next, the technical solutions of the present invention will be clearly described in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0052] Embodiment 1

[0053] As Figure 1 shown, this embodiment provides a method for hierarchical arrangement of heating coils in a large storage tank, including the following steps:

[0054] S1. Determine and extract the storage tank structure parameters and material process parameters; the storage tank structure parameters include storage tank radius, storage tank height, storage tank wall thickness, insulation layer thickness, ambient temperature, inlet temperature of heating coil 7, outlet temperature of heating coil 7, material temperature, air layer gap, filling coefficient; the material process parameters include initial / final temperature, qualitative temperature, specific heat, viscosity, density, thermal conductivity.

[0055] In this embodiment, a 1000-cubic storage tank is taken as an example to perform the hierarchical arrangement of heating coil 7; the structure parameters of the storage tank are shown in Table 1 below, and the relevant parameters of the inner and outer fluids of heating coil 7 are shown in Table 2 below.

[0056] Table 1 Storage tank structure parameters

[0057]

[0058] The filling coefficient in the storage tank structure parameters is only extracted in extreme cases.

[0059] Table 2 Relevant parameters of the inner and outer fluids of heating coil 7

[0060]

[0061] S2. Apply CFD simulation to calculate the material flow field distribution, temperature field distribution, and fluid boundary layer near the wall in the storage tank without internal components under natural convection conditions, and obtain the boundary layer deviation position, velocity boundary thickness, and average temperature of the liquid raw material in the storage tank. The specific steps are as follows:

[0062] S21. Simplify and model the 1000-cubic storage tank. Since the storage tank is axisymmetric and some accessories on the storage tank, such as manholes, material inlets and outlets, etc., have little impact on the overall heat dissipation of the storage tank, the external components such as manholes, material inlets and outlets, and ladders on the storage tank can be ignored, and only the storage tank without internal components is modeled three-dimensionally to obtain the three-dimensional model of the storage tank, which can save the consumed resources and reduce the processing time.

[0063] As Figure 2 shown, the structure of the storage tank without internal components includes a tank top 1, a tank wall 2, and a tank bottom 3. The tank top 1 is arranged at the upper end of the tank wall 2, the tank bottom 3 is arranged at the lower end of the tank wall 2, a gas phase region 4 is arranged inside the tank top 1, and a liquid phase region 5 is arranged inside the tank wall 2.

[0064] In the three-dimensional model of the storage tank, the steel plate thickness of the tank wall 2 is set to 5 mm, there is a thermal insulation layer outside the tank wall 2, and there is a 1-mm air gap layer between the tank wall 2 and the thermal insulation layer. The thermal insulation material of the thermal insulation layer is a 70-mm rock wool thermal insulation board; according to the heat transfer manual, the convective heat transfer coefficient on the surface of the rock wool thermal insulation board is 11.6 ; Calculate the thermal conductivity of rock wool through the following formula:

[0065] ;

[0066] When the time is ;

[0067] In the above formula, represents the thermal conductivity of rock wool, represents the qualitative temperature of the fluid in the heating coil 7.

[0068] When constructing the three-dimensional model of the storage tank, since the main heat dissipation area of the storage tank heating is near the wall surface, the near-wall surface is encrypted with grids and the fluid boundary layer is set; and in the numerical simulation, the part near the tank top 1 is set as air, and the mixture material with a filling coefficient of 0.9 is below the air. Referring to the concept of the thermal influence area of the tank bottom 3, the bottom boundary condition is set as a soil layer with a virtual thickness of 3 m and a temperature of 5 ; Set the external ambient temperature to 0 , to simulate the heat dissipation of the storage tank under low-temperature conditions in winter.

[0069] S22. Make physical assumptions and set up a physical simulation calculation model; perform simulations on the three-dimensional model of the storage tank constructed in step S21. During the simulation, set physical assumptions, which include satisfying the mass conservation equation, momentum conservation equation, energy conservation equation, natural convection inside the tank, and set the gravitational acceleration during the simulation. Also, enable the VOF multiphase flow model, Realizable k-epsilon turbulence model, energy equation, and radiation equation during the simulation to obtain the physical simulation calculation model. The VOF multiphase flow model can more significantly track the phase separation of the gas-liquid interface inside the storage tank with low computational cost; since the Realizable k-epsilon model is suitable for designing complex shear flows with rapid strain, slight rotation, vortices, and local transitional flows, such as boundary layer separation, etc., and has reasonable computational cost.

[0070] S23. Perform simulation calculations on the operating data of the physical simulation calculation model. Use CFD software to simulate the material flow field distribution, temperature field distribution, and wall fluid boundary layer situation of the physical simulation calculation model after 0.5 h of physical time for heat dissipation. Figure 3 、 Figure 4 They are the velocity distribution contour map and the temperature distribution schematic diagram near the wall surface after being calculated by CFD software respectively; according to the material flow field distribution, temperature field distribution, and wall fluid boundary layer situation, obtain the boundary layer drift position, velocity boundary thickness, and the average temperature of the liquid raw material inside the storage tank.

[0071] S3. According to the boundary layer drift position, velocity boundary thickness, and the average temperature of the liquid raw material inside the storage tank obtained in step S2, perform iterations to sequentially determine the diameter and layout position of the nth layer of heating coils 7. When the iteration termination condition is met, stop the iteration. Specifically, it includes the following steps:

[0072] S31. Determine the setting position range of the heating coils 7 based on the boundary layer drift position obtained in step S2. Setting the heating coils 7 at the boundary layer drift position can efficiently compensate for heat loss.

[0073] S32. Set the position of the first layer of heating coils 7 according to the velocity boundary thickness obtained in step S2.

[0074] S33. Set the first layer of heating coils 7 in the physical simulation calculation model in step S2, and use the method in step S23 to obtain the updated velocity distribution contour map and the temperature distribution schematic diagram near the wall surface, so as to obtain the updated velocity boundary thickness and the average temperature of the liquid raw material inside the storage tank; determine whether the updated average temperature of the liquid raw material inside the storage tank meets the iteration termination condition. If it meets, terminate the iteration; if not, perform step S34.

[0075] S34. Calculate the position of the second layer of heating coils 7 according to the updated velocity boundary thickness in step S33.

[0076] S35. Repeat steps S33 - S34 to determine the position of the next layer of the heating coil 7, thus completing the layout of all the heating coils 7; the diameter of each layer of the heating coil 7 is preferably 0.05 m, and the hot water flow rate of each layer of the heating coil 7 is set to 0.5 m / s.

[0077] The iteration termination condition is: set the temperature set value, and when the average temperature of the liquid raw material in the storage tank reaches the temperature set value, the iteration terminates.

[0078] The position of the i-th layer of the heating coil 7 It is calculated through the dimensionless size correlation formula, specifically:

[0079] ;

[0080] ;

[0081] ;

[0082] In the above formula, represents the abscissa of the i-th layer of the heating coil 7, represents the velocity boundary thickness corresponding to the i-th layer of the heating coil 7, represents the radius of the storage tank, represents the ordinate of the i-th layer of the heating coil 7, represents the total number of heating coils 7 existing when the i-th layer of the heating coil 7 is installed, A, B, and C are all constants. A takes 0.00783, B takes 1.207, and C takes 0.0121. represents the viscosity of the liquid outside the heating coil 7, represents the liquid level height in the storage tank, that is, the characteristic length of natural convection occurring in the storage tank, represents the density of the liquid outside the heating coil 7, represents the overall flow rate of the chemical raw material in the storage tank under natural convection, and i takes 1 - n.

[0083] In this embodiment, the position of the first layer of the heating coil 7 is obtained according to the Figure 3 、 Figure 4 The velocity boundary thickness shown in, and the position of the first layer of the heating coil 7 is calculated as , adding the first layer of the heating coil 7 to the physical simulation calculation model, the updated velocity distribution contour map by the CFD software is as shown in Figure 5 , so the position of the second layer of the heating coil 7 is calculated as ; in this embodiment, after setting up to the fifth layer of the heating coil 7, the average temperature of the liquid raw material in the storage tank meets the iteration termination condition, and the calculated position of the third layer of the heating coil 7 is , the fourth-layer heating coil 7 is located according to the calculated position as , the fifth-layer heating coil 7 is located according to the calculated position as ; The velocity distribution contour map after adding the first-layer heating coil 7 and the second-layer heating coil 7 in the physical simulation calculation model is as Figure 6 shown. The velocity distribution contour map after adding the first-layer heating coil 7, the second-layer heating coil 7, and the third-layer heating coil 7 in the physical simulation calculation model is as Figure 7 shown. The velocity distribution contour map after adding the first-layer heating coil 7, the second-layer heating coil 7, the third-layer heating coil 7, and the fourth-layer heating coil 7 in the physical simulation calculation model is as Figure 8 shown. The velocity distribution contour map after adding the first-layer heating coil 7, the second-layer heating coil 7, the third-layer heating coil 7, the fourth-layer heating coil 7, and the fifth-layer heating coil 7 in the physical simulation calculation model is as Figure 9 shown.

[0084] Define the axial height of the storage tank as H, set the dimensionless height of the axial arrangement as y / H, and the dimensionless height of the radial arrangement as x / r; The relationship between the number of heating coils 7 and the dimensionless height of the axial arrangement is as Figure 10 shown.

[0085] It can be seen from the velocity distribution contour maps of the heating coils 7 with different layers set above that after adding the heating coils 7, the number of vortices in the flow field inside the storage tank increases significantly, which is beneficial to enhancing the thermal convection movement of the materials inside the tank and making the temperature distribution of the materials uniform. In the existing design method of the heating coils 7, it is calculated and enlarged according to empirical values. The designed coil heating area is relatively large, the arrangement height interval is small, and the design of the heat exchange area directly depends on the value of the heat transfer coefficient; The solution inside the entire storage tank relies on the local heating method, and the temperature field will be uneven. In particular, there will be a phenomenon of dead zones not flowing at the bottom 3 of the storage tank; The key design parameters such as the interval height and diameter of the heating coils 7 often depend on experience and there is no corresponding design basis, so it cannot be applied universally in storage tanks with different diameters and heights. Compared with the existing design method of the heating coils 7, the method for arranging the heating coils in layers of the large storage tank proposed in this embodiment arranges the heating coils 7 relying on velocity drift, which can effectively improve the problem of stagnant flow on the wall 2 of the storage tank, improve the uniformity of the internal temperature heating of the storage tank, thereby improving the thermal utilization efficiency, and at the same time, it can also avoid design errors.

[0086] In this embodiment, by combining CFD fluid calculations, the obtained convective heat transfer coefficient is relatively accurate, and it can give the flow field movement and temperature field distribution in the storage tank. At the same time, heating coils 7 are arranged at the side flow of the boundary layer, which can efficiently compensate for heat loss, effectively improve the problem of flow dead zones in local areas, maintain a stable temperature in the tank, and can accurately provide a basis for the structural design of the heating coils 7. This embodiment combines the ideas of heat transfer and fluid mechanics, proposes a dimensionless size correlation formula for physical parameters such as the diameter of the storage tank, the height of the storage tank, the spacing of the heating coils 7, and the thickness of the flow boundary layer, and points out the general law of the side flow direction of the boundary layer, solving the problems of large errors in traditional empirical design, inability to intuitively study the changes in the flow field and temperature field in the storage tank, and waste of thermal energy, and can quickly and intuitively provide a design scheme.

[0087] Embodiment 2

[0088] As Figure 11 shown, this embodiment provides a hierarchical layout structure of heating coils for a large storage tank, including a tank body 6 and multiple layers of heating coils 7. The multiple layers of heating coils 7 are arranged on the tank body 6 using the distribution arrangement method of the large storage tank heating coils 7 in Embodiment 1.

[0089] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than a limitation on the protection scope of the present invention. Any simple modification or equivalent replacement of the technical solution of the present invention by those of ordinary skill in the art does not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A layered arrangement method for large tank heating coils, characterized in that: The following steps are involved: S1. Determine the tank structure parameters and material process parameters and extract them; S2. According to the tank structure parameters and material process parameters extracted in step S1, a physical simulation calculation model is constructed, and then CFD software is used to simulate the physical simulation calculation model to obtain the boundary layer deviation position, velocity boundary thickness and average temperature of the liquid raw material in the tank; S2 specifically includes the following steps: S21, according to the storage tank structural parameters and material process parameters extracted in step S1, simplify the model of the storage tank and perform three-dimensional modeling to obtain a three-dimensional model of the storage tank; S22, making physical assumptions, and simulating the three-dimensional model of the storage tank according to the physical assumptions, thereby obtaining a physical simulation calculation model; S23, using CFD software to perform operation data simulation calculation on the physical simulation calculation model to obtain the boundary layer deviation flow position, velocity boundary thickness and average temperature of the liquid raw material in the storage tank when the heating coil is not set; S3, determining the setting position range of the heating coil according to the boundary layer deviation position; iterating according to the velocity boundary thickness and the average temperature of the liquid raw material in the storage tank, and sequentially determining the arrangement positions of the n layers of heating coils. When the iteration termination condition is met, the iteration is stopped, and the arrangement of the heating coils is completed; S3 specifically includes the following steps: S31, setting the boundary layer deviation flow position obtained in step S2 as the setting position range of the heating coil; S32, calculating the position of the first layer of heating coils according to the velocity boundary layer thickness obtained in step S2; S33, adding the structure of the first layer of heating coils to the physical simulation calculation model in step S2, and using the method in step S23 to obtain the updated velocity boundary thickness and the average temperature of the liquid raw material in the storage tank; judging whether the updated average temperature of the liquid raw material in the storage tank meets the iteration termination condition, if so, terminating the iteration and completing the arrangement of the heating coils, if not, proceeding to step S34; S34, calculating the position of the second layer of heating coils according to the velocity boundary thickness updated in step S33; S35, repeating steps S33-S34 to determine the position of the next layer of heating coils, thereby completing the arrangement of all heating coils; The position of the i-th layer heating coil (Xi, Yi) is calculated by the dimensionless size correlation formula, which is: ； ； ； In the above formula, represents the horizontal coordinate of the heating coil at the i-th layer, represents the velocity boundary thickness corresponding to the i-th layer of heating coil, represents the radius of the tank, represents the ordinate of the i-th layer of heating coil, Indicates the total number of heating coils existing when the i-th layer of heating coils is installed. , B, and C are all constants. Indicates the viscosity of the liquid outside the heating coil, Indicates the liquid level in the tank. represents the density of the liquid outside the heating coil, It indicates the overall flow rate of chemical raw materials in the storage tank under natural convection.

2. The layered arrangement method of a large storage tank heating coil according to claim 1 is characterized in that: The physical assumptions in step S22 include satisfying the mass conservation equation, momentum conservation equation, energy conservation equation, and natural convection in the tank.

3. The layered arrangement method of a large storage tank heating coil according to claim 1 is characterized in that: The model simplification method in step S21 is: remove the internal components of the storage tank and perform three-dimensional modeling only on the storage tank without the internal components.

4. The layered arrangement method of a large storage tank heating coil according to claim 1 is characterized in that: A is 0.00783, B is 1.207, and C is 0.0121.

5. The layered arrangement method of large storage tank heating coils according to claim 1 is characterized in that: The iteration termination condition is: set the temperature setting value. When the average temperature of the liquid raw material in the storage tank reaches the temperature setting value, the iteration terminates.

6. The layered arrangement method of large tank heating coils according to claim 1 is characterized in that: In step S1, the tank structural parameters include tank radius, tank height, tank wall thickness, insulation layer thickness, ambient temperature, heating coil inlet temperature, heating coil outlet temperature, material temperature, air layer gap, and filling coefficient; the material process parameters include initial / final temperature, qualitative temperature, specific heat, viscosity, density, and thermal conductivity.

7. A layered arrangement structure of large tank heating coils, characterized in that: The invention comprises a tank body and a multi-layer heating coil, wherein the multi-layer heating coil is arranged on the tank body using a layered arrangement method for a large storage tank heating coil according to any one of claims 1 to 6.

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