Layered arrangement method and structure of large storage tank heating coils

Abstract

The invention relates to the technical field of large storage tank heating, in particular to a layered arrangement method and structure of large storage tank heating coils. Comprising the following steps that S1, storage tank structure parameters and material process parameters are determined and extracted; s2, according to the storage tank structure parameters and the material process parameters extracted in the step S1, a physical simulation calculation model is constructed, then CFD software is used for conducting simulation calculation on the physical simulation calculation model, and the boundary layer bias flow position, the speed boundary thickness and the average temperature of liquid raw materials in the storage tank are obtained; s3, the setting position range of the heating coil is determined according to the boundary layer bias flow position; iteration is carried out according to the speed boundary thickness and the average temperature of the liquid raw materials in the storage tank, the arrangement positions of the n layers of heating coils are sequentially determined, and when iteration termination conditions are met, iteration is stopped, and arrangement of the heating coils is completed; the design accuracy of the heating coil is high, and the temperature uniformity in the large storage tank is high.

Description

Technical Field

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

[0002] As an auxiliary heating and insulation measure, it is necessary to consider the design of chemical raw material storage tanks. In the chemical production process, a large number 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 winter when the heat dissipation to the outside world is faster. Fluctuating temperature conditions are difficult to meet the storage requirements of chemical raw materials. Usually, when chemical raw material liquids with high melting points are stored in large storage tanks, corresponding heating and insulation systems need to be configured to maintain a stable temperature and prevent raw material crystallization due to low temperature environments. Therefore, it is of great significance to reasonably design the corresponding heating system, improve the utilization rate of chemical raw materials and the efficiency of thermal energy utilization, save costs for enterprises, save energy and reduce emissions, and improve the production efficiency of chemical raw materials. There are many ways to heat and insulate large storage tanks. Coils can be used for heating inside the tank, and electric heating, external coils, and external circulation of materials and media can be used for heating outside the tank. Currently, the single tank capacity of stored materials is large, and the cost of heating with coils outside the tank is very high. The energy consumption of electric heating is higher than that of steam and hot water heating and insulation, and electric heating is prone to breakage, and the maintenance cost is also high. The use of coil heating inside the tank or external heat exchanger circulation heating can effectively utilize heat sources and has good heat exchange effects, and is widely used in heating and insulation systems.

[0003] The existing large-scale storage tank heating layout design is often designed around different heating coil structures and layout forms. The built-in heating coil is often set at the bottom of the tank for heating and insulation considering the ease of construction. There are also often layered heating coil design schemes used in the heating of high-viscosity fluid storage tanks, such as crude oil, asphalt, etc. At present, the design of coil layout mainly relies on energy constant calculation and empirical formula to calculate the relationship between the required heat consumption of the storage tank and the heat exchange area of ​​the heating coil, but there is no clear guidance on how to design the specific layers.

[0004] At present, empirical formulas are often used in engineering to calculate the heat dissipation and temperature drop of storage tanks. The current design of coil layout is mainly based on the chemical industry perspective. The heat loss per unit area under a fixed temperature difference is calculated based on experiments or experience, and then converted into the convective heat transfer coefficient to obtain the lost heat. Then, based on the lost heat, empirical estimates are made for insulation design. The design of the heating coil mainly depends on the empirical value of the convective heat transfer coefficient, and most empirical formula calculations ignore the effects of heat convection and thermal radiation, resulting in large errors. The temperature drop of materials in the storage tank is a non-steady-state heat transfer process. The results predicted by the empirical formula are quite different from the actual situation, and the empirical formula cannot give the temperature drop law of the materials in the tank, and cannot guide actual production.

[0005] The smaller the selected pipe diameter, the more favorable it is for heat transfer. However, too small a pipe diameter will increase the flow resistance in the pipe and increase the number of parallel pipes required. Therefore, the commonly used pipe diameter is in the range of DN25-65, which can prevent excessive pressure drop in the coil and limit the flow rate in the pipe to 0.3-0.8m / s. For gas, the mass flow rate is controlled at 3-10kg / m 2. s. Generally, the height of the upper and lower heating coils is set at 1.5-2do (do is the outer diameter of the coil). The design of the coil heating area and the coil size selection, ground height, and distance from the wall are based on empirical values. There is no corresponding theoretical basis to support this, and it cannot be fully applicable to heating tanks of different sizes and designs.

[0006] At present, the design and research of heating coils are basically concentrated in the heating of asphalt, crude oil and LNG natural gas, and the storage and transportation of chemical raw materials also require better insulation and heating design to maintain the temperature of chemical materials. Generally, the heating coils of large storage tanks are laid flat at the bottom. The heated liquid produces density difference for convection, and the heat transfer efficiency is low. It takes a long time to run in a low temperature environment to maintain the temperature in the tank stable. At present, the problem that the bottom liquid heats quickly but the upper part is not easy to be heated is mainly solved by arranging heating pipes in layers and setting 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 cost.

[0007] Therefore, there is an urgent need to provide a layered arrangement method and structure for large storage tank heating coils, which can reduce design errors and make the heating temperature uniform compared to the prior art. Summary of the invention

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

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A layered arrangement method for large storage tank heating coils comprises the following steps: S1. Determine the tank structure parameters and material process parameters and extract them; S2. According to the storage tank structural 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 flow position, velocity boundary thickness and average temperature of the liquid raw material in the storage tank; S3. Determine the setting position range of the heating coil according to the boundary layer deviation position; iterate according to the velocity boundary thickness and the average temperature of the liquid raw material in the storage tank, and determine the layout positions of the n layers of heating coils in turn. When the iteration termination condition is met, stop the iteration and complete the layout of the heating coils.

[0010] Furthermore, 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. Use CFD software to perform running data simulation calculation on 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 storage tank when the heating coil is not set.

[0011] Furthermore, the physical assumptions in step S22 include satisfying the mass conservation equation, momentum conservation equation, energy conservation equation, and natural convection in the tank.

[0012] Furthermore, the model simplification method in step S21 is: removing the internal components of the storage tank and only performing three-dimensional modeling on the storage tank without the internal components.

[0013] Furthermore, S3 specifically includes the following steps: S31, setting the boundary layer bias 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. Repeat steps S33-S34 to determine the position of the next layer of heating coils, thereby completing the arrangement of all heating coils.

[0014] Furthermore, the position of the heating coil on the i-th layer It is calculated by the dimensionless dimensional correlation formula, specifically: ; ; ; 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, A is 0.00783, B is 1.207, and C is 0.0121. 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.

[0015] Furthermore, the iteration termination condition is: setting a temperature setting value, and when the average temperature of the liquid raw material in the storage tank reaches the temperature setting value, the iteration is terminated.

[0016] Furthermore, 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.

[0017] A layered arrangement structure of a large storage tank heating coil comprises a tank body and a multi-layer heating coil. The multi-layer heating coil is arranged on the tank body using a layered arrangement method of a large storage tank heating coil.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) After the heating coil is added to the present invention, the number of flow field vortices in the storage tank increases significantly, which is beneficial to enhancing the thermal convection movement of the material in the tank and making the material temperature evenly distributed. Compared with the existing heating coil design method, the method proposed in the present invention relies on velocity deviation to arrange the heating coil, which can effectively improve the flow stagnation problem on the wall of the storage tank, improve the temperature heating uniformity inside the storage tank, thereby improving the heat utilization efficiency, and at the same time can avoid design errors.

[0019] (2) The present invention combines CFD fluid calculation to obtain a relatively accurate convective heat transfer coefficient, which can provide the flow field movement and temperature field distribution in the storage tank. At the same time, arranging heating coils at the boundary layer deviation 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 provide a relatively accurate basis for the design of the heating coil structure.

[0020] (3) The present invention combines the concepts of heat transfer and fluid mechanics, proposes dimensionless dimensional correlations for physical parameters such as tank diameter, tank height, heating coil spacing, and flow boundary layer thickness, and points out the general law of boundary layer deviation direction. This solves the problems of large errors in traditional empirical design, the inability to intuitively study the flow field and temperature field changes in the tank, and the waste of heat energy, and can provide a design solution quickly and intuitively. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a flow chart of the method of the present invention.

[0022] Figure 2 It is a schematic diagram of a storage tank structure without internal components of the present invention.

[0023] Figure 3 It is a velocity distribution cloud diagram when the heating coil is not arranged in the present invention.

[0024] Figure 4 It is a schematic diagram of temperature distribution near the wall surface when no heating coil is arranged in the present invention.

[0025] Figure 5 This is a velocity distribution cloud diagram after the first layer of heating coils is arranged in the present invention.

[0026] Figure 6 This is a velocity distribution cloud diagram after the second layer of heating coils is arranged in the present invention.

[0027] Figure 7 This is a velocity distribution cloud diagram after the third layer of heating coils is arranged in the present invention.

[0028] Figure 8 This is a velocity distribution cloud diagram after the fourth layer of heating coils is arranged in the present invention.

[0029] Fig. 9 This is a velocity distribution cloud diagram after the fifth layer of heating coils is arranged in the present invention.

[0030] Fig.10 It is a schematic diagram of the relationship between the number of heating coils and the dimensionless height of the axial arrangement of the present invention.

[0031] Fig.11 It is a schematic diagram of the structure of the present invention.

[0032] Description of reference numerals: 1. Tank top; 2. Tank wall; 3. Tank bottom; 4. Gas phase area; 5. Liquid phase area; 6. Tank body; 7. Heating coil. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present invention, and all other embodiments obtained by ordinary technicians in the field without making creative work are within the protection scope of the present invention.

[0034] Example 1 like Figure 1 As shown, this embodiment provides a layered arrangement method for large storage tank heating coils, comprising the following steps: S1. Determine the tank structure parameters and material process parameters, and extract them; the tank structure parameters include tank radius, tank height, tank wall thickness, insulation layer thickness, ambient temperature, heating coil 7 inlet temperature, heating coil 7 outlet temperature, material temperature, air layer gap, filling coefficient; material process parameters include initial / final temperature, qualitative temperature, specific heat, viscosity, density, thermal conductivity.

[0035] In this embodiment, a 1000 cubic storage tank is taken as an example to arrange the heating coil 7 in layers; the structural parameters of the storage tank are shown in Table 1 below, and the relevant parameters of the fluid inside and outside the heating coil 7 are shown in Table 2 below.

[0036] Table 1 Tank structural parameters

[0037] The filling factor in the structural parameters of the tank is only extracted in extreme cases.

[0038] Table 2 Related parameters of the fluid inside and outside the heating coil 7

[0039] 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, specifically including the following steps: S21. Simplify and model the 1000 cubic storage tank. Since the storage tank is an axisymmetric structure and some accessories on the storage tank, such as manholes, material inlets and outlets, have little effect on the overall heat dissipation of the storage tank, the manholes, material inlets and outlets, ladders and other external components on the storage tank can be ignored. Only the storage tank without internal components is three-dimensionally modeled to obtain a three-dimensional model of the storage tank, which can save consumed resources and reduce processing time.

[0040] like Figure 2 As shown, the storage tank structure 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 area 4 is arranged inside the tank top 1, and a liquid phase area 5 is arranged inside the tank wall 2.

[0041] In the three-dimensional model of the storage tank, the thickness of the steel plate of the tank wall 2 is set to 5mm, an insulation layer is provided on the outside of the tank wall 2, and a 1mm air gap layer is provided between the tank wall 2 and the insulation layer. The insulation material of the insulation layer is a 70mm rock wool insulation board; according to the heat transfer manual, the convective heat transfer coefficient of the rock wool insulation board surface is obtained 11.6 ; Calculate the thermal conductivity of rock wool by the following formula: ; when hour, ; In the above formula, Indicates the thermal conductivity of rock wool, Indicates the qualitative temperature of the fluid in the heating coil 7.

[0042] When constructing the three-dimensional model of the tank, since the main heat dissipation area of ​​the tank heating is near the wall, the grid near the wall is encrypted 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 part below the air is the mixed material with a filling coefficient of 0.9. Referring to the concept of the thermal influence zone, the bottom boundary condition of the tank bottom 3 is set as a 3m virtual thickness soil layer with a temperature of 5 ; Set the external ambient temperature to 0 , used to simulate the heat dissipation of storage tanks under low temperature conditions in winter.

[0043] S22, make physical assumptions and set up a physical simulation calculation model; simulate the three-dimensional model of the storage tank constructed in step S21, and set physical assumptions during the simulation process. The physical assumptions include satisfying the mass conservation equation, momentum conservation equation, energy conservation equation, natural convection in the tank, and setting the gravity acceleration during the simulation process; during the simulation process, the VOF multiphase flow model, Realizable k-epsilon turbulence model, energy equation and radiation equation are also turned on to obtain a physical simulation calculation model. The VOF multiphase flow model can clearly track the interface phase separation of the gas phase and the liquid phase in the storage tank, and the calculation cost is small; because the Realizable k-epsilon model is suitable for designing complex shear flows with rapid strain, slight rotation, vortex and local transition flow, such as boundary layer separation, and the calculation cost is reasonable.

[0044] S23, perform running data simulation calculation on the physical simulation calculation model, use CFD software to simulate the material flow field distribution, temperature field distribution and wall fluid boundary layer of the physical simulation calculation model after the heat dissipation physical time is 0.5h, Figure 3 , Figure 4They are respectively the velocity distribution cloud map and the temperature distribution diagram near the wall after calculation by CFD software; according to the material flow field distribution, temperature field distribution and wall fluid boundary layer conditions, the boundary layer deviation position, velocity boundary thickness and the average temperature of the liquid raw material in the tank are obtained.

[0045] S3, according to the boundary layer deviation position, velocity boundary thickness and average temperature of the liquid raw material in the storage tank obtained in step S2, iterate to determine the diameter and layout position of the n-layer heating coil 7 in turn, and stop the iteration when the iteration termination condition is met. Specifically, it includes the following steps: S31. Determine the boundary layer bias flow position obtained in step S2 as the setting position range of the heating coil 7. Setting the heating coil 7 at the boundary layer bias flow position can efficiently compensate for heat loss.

[0046] S32. According to the velocity boundary thickness obtained in step S2, the position of the first layer of heating coils 7 is set.

[0047] 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 cloud map and the temperature distribution diagram near the wall, so as to obtain the updated velocity boundary thickness and the average temperature of the liquid raw material in the storage tank; determine whether the updated average temperature of the liquid raw material in the storage tank meets the iteration termination condition, if so, terminate the iteration, if not, proceed to step S34.

[0048] S34. Calculate the position of the second layer of heating coil 7 according to the velocity boundary thickness updated in step S33.

[0049] S35. Repeat steps S33-S34 to determine the position of the next layer of heating coils 7, thereby completing the arrangement of all heating coils 7; the diameter of each layer of heating coils 7 is preferably 0.05m, and the hot water flow rate of each layer of heating coils 7 is set to 0.5m / s.

[0050] 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.

[0051] The position of the heating coil 7 on the i-th layer It is calculated by the dimensionless dimensional correlation formula, specifically: ; ; ; In the above formula, represents the horizontal coordinate of the i-th layer heating coil 7, represents the velocity boundary thickness corresponding to the i-th layer of heating coil 7, represents the radius of the tank, represents the ordinate of the i-th layer heating coil 7, represents the total number of heating coils 7 existing when the i-th layer of heating coils 7 is installed, , B, and C are all constants, A is 0.00783, B is 1.207, and C is 0.0121. represents the viscosity of the liquid outside the heating coil 7, It represents the liquid level height in the tank, that is, the characteristic length of natural convection in the tank. represents the density of the liquid outside the heating coil 7, It represents the overall flow rate of chemical raw materials in the storage tank under natural convection, and i is 1-n.

[0052] In this embodiment, the position of the first layer of heating coils 7 is based on Figure 3 , Figure 4 The velocity boundary thickness shown in is obtained, and the position of the first layer of heating coil 7 is calculated according to , the first layer of heating coil 7 is added to the physical simulation calculation model, and the velocity distribution cloud diagram after the CFD software is updated is as follows Figure 5 As shown, the position of the second layer heating coil 7 is calculated as In this embodiment, after the fifth layer of heating coils 7 is set, the average temperature of the liquid raw material in the storage tank meets the iteration termination condition, and the third layer of heating coils 7 is calculated according to the position The fourth layer heating coil 7 is located according to the calculation The fifth layer heating coil 7 is located according to the calculation The velocity distribution cloud diagram after adding the first layer of heating coil 7 and the second layer of heating coil 7 in the physical simulation calculation model is as follows: Figure 6 As shown, the velocity distribution cloud diagram after adding the first layer of heating coils 7, the second layer of heating coils 7 and the third layer of heating coils 7 to the physical simulation calculation model is as follows: Figure 7 As shown, the velocity distribution cloud diagram after adding the first layer of heating coil 7, the second layer of heating coil 7, the third layer of heating coil 7 and the fourth layer of heating coil 7 in the physical simulation calculation model is as follows Figure 8 As shown, the velocity distribution cloud diagram after adding the first layer of heating coil 7, the second layer of heating coil 7, the third layer of heating coil 7, the fourth layer of heating coil 7 and the fifth layer of heating coil 7 in the physical simulation calculation model is as follows Fig. 9 shown.

[0053] Define the axial height of the 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 follows: Fig.10 shown.

[0054] According to the velocity distribution cloud diagram of the above-mentioned setting of different layers of heating coils 7, it can be seen that the number of eddies in the flow field in the storage tank increases significantly after adding the heating coils 7, which is conducive to enhancing the thermal convection movement of the material in the tank and making the material temperature uniformly distributed. The existing design method of the heating coil 7 is calculated and enlarged according to the empirical value. The designed coil heating area is 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 in the entire storage tank relies on the local heating method, and the temperature field will be uneven, especially in the bottom 3 of the storage tank, there will be a dead zone without flow phenomenon; the key design parameters such as the interval height and diameter of the heating coil 7 are often determined according to experience, and there is no corresponding design basis, which cannot be universal in storage tanks of different diameters and heights. Compared with the existing design method of the heating coil 7, the layered arrangement method of the large storage tank heating coil proposed in this embodiment relies on the velocity deviation to arrange the heating coil 7, which can effectively improve the flow stagnation problem on the two sides of the storage tank wall, improve the uniformity of the temperature heating inside the storage tank, thereby improving the heat utilization efficiency, and can also avoid design errors.

[0055] This embodiment combines CFD fluid calculation to obtain a more accurate convective heat transfer coefficient, which can provide the flow field movement and temperature field distribution in the tank. At the same time, arranging the heating coil 7 at the boundary layer deviation can efficiently compensate for heat loss, effectively improve the problem of flow dead zone in local areas, maintain a stable temperature in the tank, and provide a more accurate basis for the structural design of the heating coil 7. This embodiment combines the concepts of heat transfer and fluid mechanics to propose dimensionless dimensional correlations for physical parameters such as tank diameter, tank height, spacing between heating coils 7, and flow boundary layer thickness, and points out the general law of the boundary layer deviation direction, solving the problems of large errors in traditional empirical design, inability to intuitively study the flow field in the tank, temperature field changes, and heat energy waste, and can quickly and intuitively provide a design solution.

[0056] Example 2 like Fig.11 As shown, this embodiment provides a layered arrangement structure of a large storage tank heating coil, including a tank body 6 and a multi-layer heating coil 7, and the multi-layer heating coil 7 is arranged on the tank body 6 using the distribution arrangement method of the large storage tank heating coil 7 in Example 1.

[0057] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate 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 storage tank structural 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 flow position, velocity boundary thickness and average temperature of the liquid raw material in the storage tank; S3. Determine the setting position range of the heating coil according to the boundary layer deviation position; iterate according to the velocity boundary thickness and the average temperature of the liquid raw material in the storage tank, and determine the layout positions of the n layers of heating coils in turn. When the iteration termination condition is met, stop the iteration and complete the layout of the heating coils.

2. A layered arrangement method for large storage tank heating coils according to claim 1, characterized in that: 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. Use CFD software to perform running data simulation calculation on 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 storage tank when the heating coil is not set.

3. The layered arrangement method of a large storage tank heating coil according to claim 2 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.

4. The layered arrangement method of a large storage tank heating coil according to claim 2 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.

5. The layered arrangement method of a large storage tank heating coil according to claim 2 is characterized in that: S3 specifically includes the following steps: S31, setting the boundary layer bias 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. Repeat steps S33-S34 to determine the position of the next layer of heating coils, thereby completing the arrangement of all heating coils.

6. The layered arrangement method of large storage tank heating coils according to claim 5 is characterized in that: The location of the heating coil on the i-th layer It is calculated by the dimensionless dimensional correlation formula, specifically: ； ； ； 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, A is 0.00783, B is 1.207, and C is 0.0121. 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.

7. The layered arrangement method of large tank heating coils according to claim 5, 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.

8. The layered arrangement method of a large storage tank heating coil 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.

9. A layered arrangement structure of large tank heating coils, characterized in that: It 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 large storage tank heating coils according to any one of claims 1-8.

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