High temperature radiant furnace tube with turbulence structure and its design, preparation and application method

Abstract

The application discloses a high-temperature radiation furnace tube containing a turbulent flow structure and a design, preparation and application method thereof, and belongs to the technical field of high-temperature radiation furnace tubes. The design method comprises the following steps: constructing a calculation model E1 for predicting the influence of the geometric parameters of a turbulent flow structure on the pressure drop of a high-temperature radiation furnace tube containing the turbulent flow structure, i.e., the predicted pressure drop sensitivity of the high-temperature radiation furnace tube containing the turbulent flow structure; and limiting the calculation results of the calculation model E1 according to the actual requirements of the pressure drop sensitivity of the application scene of the high-temperature radiation furnace tube containing the turbulent flow structure, so as to obtain the geometric parameters of the turbulent flow structure meeting the pressure drop sensitivity. The application can be customized and optimized according to different requirements of the furnace tube under different working conditions, such as pressure drop, heat exchange performance and outlet temperature, and can obtain the parameters of the turbulent flow structure for maximizing the heat exchange efficiency of the furnace tube under the premise of meeting the pressure drop control.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-temperature radiant furnace tubes, in particular to a high-temperature radiant furnace tube containing a turbulence structure and a design, preparation and application method thereof. BACKGROUND

[0002] In an ethylene cracking furnace, the cracking reaction is a high-temperature gas-phase reaction, and the ethylene reaction yield is mainly affected by the gas residence time and temperature. Since the cracking reaction is an endothermic reaction, continuous heating of the gas in the tube is required through the tube wall. To avoid the occurrence of side reactions and ensure a short residence time, the gas flow rate in the cracking furnace tube is usually maintained at 100-300 m / s, corresponding to a Reynolds number (Re) greater than 10,000, in a state of strong turbulence. The inner diameter of such a furnace tube is usually 40-200 mm, the operating temperature of the furnace tube ranges from 800 to 1100 ℃, and the gas medium temperature is generally between 600 and 900 ℃.

[0003] Most existing furnace tubes use machined surfaces with smooth inner walls. When the gas passes at high speed, although the main flow appears to be turbulent, the speed in the boundary layer region close to the furnace wall is low, and the heat transfer effect is limited, resulting in insufficient convective heat transfer efficiency between the inner wall of the furnace tube and the gas. To improve this problem, it is common to install turbulence structures such as spiral fins, ribbed fins or protrusions inside the furnace tube to strengthen the fluid flow and improve the heat transfer efficiency of the tube wall.

[0004] However, such internal turbulence structures, while improving heat transfer efficiency, also significantly increase flow resistance, resulting in an increase in pressure drop in the tube. In pressure-sensitive conditions such as an ethylene cracking furnace, excessive pressure drop will cause a decrease in gas flow, leading to an increase in residence time or uneven distribution, which may result in excessive cracking or uneven reaction, thus requiring precise design of the internal structure of the furnace tube to achieve an improvement in heat transfer efficiency under controllable pressure drop conditions. In relatively pressure-insensitive conditions such as a hydrogen production reformer, although some increase in pressure drop is allowed, the relationship between the increase in pressure drop and the improvement in heat transfer efficiency still needs to be clarified.

[0005] In addition, although CN119425537A improves the heat transfer efficiency to some extent and controls the pressure drop by combining the roughening of the inner surface with micron-scale flow structures, the design of the flow structures still lacks systematic differentiation and quantitative guidance for pressure drop sensitivity under different conditions, especially lacking precise prediction means for the flow and heat transfer coupling behavior under extreme high-speed and high-temperature conditions, making it difficult to achieve a dynamic balance between pressure drop and heat transfer and customized design in different application scenarios such as ethylene cracking, hydrogen production reforming and iron ore reduction.

[0006] Therefore, how to accurately predict the influence of the internal disturbance structure of the furnace tube on the pressure drop and heat exchange performance, and accordingly obtain an optimized design structure with a reasonable balance between heat transfer enhancement and pressure drop control, is a key problem that the prior art urgently needs to solve. SUMMARY

[0007] In view of the defects of the prior art, the purpose of the present application is to provide a high-temperature radiation furnace tube containing a disturbance structure and a design, preparation and application method thereof, so as to solve the problems that the internal disturbance structure of the furnace tube in the prior art leads to a significant increase in pressure drop while improving heat transfer efficiency, and lacks quantitative and accurate control of different pressure drop sensitivity working conditions.

[0008] The technical solutions of the present application are as follows:

[0009] A design method of a high-temperature radiation furnace tube containing a disturbance structure, comprising:

[0010] constructing a calculation model E1 for predicting the influence of the geometric parameters of the disturbance structure on the pressure drop of the high-temperature radiation furnace tube containing the disturbance structure, i.e. the predicted pressure drop sensitivity of the high-temperature radiation furnace tube containing the disturbance structure;

[0011] limiting the calculation results of the calculation model E1 according to the actual requirements of the application scene of the high-temperature radiation furnace tube containing the disturbance structure on the pressure drop sensitivity, to obtain the geometric parameters of the disturbance structure that meet the pressure drop sensitivity;

[0012] wherein the calculation model E1 is constructed as follows:

[0013]

[0014] wherein ΔP rough represents the pressure drop of the furnace tube provided with the disturbance structure, ΔP smooth represents the pressure drop of the smooth furnace tube, H represents the distance from the top of the disturbance structure to the center of the bottom, i.e. the radius of the hemispherical disturbance structure, D represents the inner diameter of the furnace tube, P represents the axial spacing of adjacent disturbance structures on the same axis, N represents the total number of disturbance structures covered by the furnace tube on the same axis within the axial spacing of adjacent disturbance structures, and π represents the circular constant; k1, m1, n1, p1 represent fitting parameters, and their values are respectively: k1=178.227, m1=1.117, n1=-1.019, p1=1.209;

[0015] wherein the disturbance structure is hemispherical, uniformly or staggeredly distributed on the inner wall of the high-temperature radiation furnace tube, and the geometric parameters of the disturbance structure satisfy D=40-300mm, H / D=0.02-0.15, P / D=0.03-5, and N=3-48.

[0016] It should be noted that the geometric parameters of the spoiler structure satisfying the pressure drop sensitivity in the above scheme can be a single parameter combination such as a unique H, D, P and N value, or a plurality of parameter combinations such as a plurality of H, D, P and N values that meet the calculation requirements.

[0017] In the above calculation model, The approximate expression of the coverage of the spoiler structure in the circumferential direction can be used, and calculation shows that when H / D is 0.05-0.2, the error rate of the approximate processing is not more than 1%, which can significantly simplify the calculation model and quickly obtain the calculation result.

[0018] The above calculation model of the present application fully considers that due to the friction resistance existing in the inner wall of the furnace tube, the gas will generate a pressure drop between the inlet and the outlet when passing through the furnace tube, and the greater the friction resistance, the higher the corresponding pressure drop. In order to accurately quantitatively evaluate the influence of the spoiler structure on the pressure drop, the above calculation model takes the pressure drop ΔP smooth obtained by the smooth furnace tube as the baseline, and the pressure drop ratio obtained by the furnace tube provided with the spoiler structure and the smooth furnace tube is used to measure the increase degree of the flow resistance of different spoiler structures.

[0019] The above calculation model of the present application fully considers the influence of the geometric parameters of the spoiler structure on the flow characteristics, wherein H / D (the ratio of the height of the spoiler structure to the inner diameter of the furnace tube) can reflect the relative protrusion size of the spoiler structure, P / D (the ratio of the axial spacing of the spoiler structure to the inner diameter of the tube) can reflect the arrangement sparseness of the spoiler structure in the axial direction, and can reflect the comprehensive effect of the number of circumferential spoiler structures and the protrusion height. Through the combination of these dimensionless parameters, the coupling relationship between the spoiler structure and the flow friction can be accurately and systematically described.

[0020] In addition, from the physical meaning, the increase of H and N values in the model E1 can significantly strengthen the boundary layer disturbance and increase the friction factor, thereby causing the pressure drop to rise; on the contrary, the increase of P and D values can help to weaken the interference effect and reduce the flow resistance. Therefore, the model can not only accurately depict the influence law of different spoiler structure geometric parameters on the pressure drop, but also provide a reliable prediction tool in engineering design, helping designers to reasonably select the spoiler structure under the pressure drop sensitive working condition, and realize the optimal balance of the energy efficiency improvement and the pressure drop control of the furnace tube.

[0021] According to some preferred embodiments of the present application, when the application scene of the high-temperature radiant furnace tube with the spoiler structure is extremely sensitive to the requirement of the pressure drop sensitivity, the value DP obtained according to the calculation model E1 is limited to DP<2.

[0022] When the application scene of the high-temperature radiant furnace tube with the spoiler structure is relatively sensitive to the requirement of the pressure drop sensitivity, 2≤DP<5 is limited. ​

[0023] When the application scenario of the high-temperature radiant furnace tube with the turbulence structure is not sensitive to the requirement of pressure drop sensitivity, the DP is limited to be greater than or equal to 5.

[0024] According to some preferred embodiments of the present application, the design method further comprises:

[0025] constructing a calculation model E2 for predicting the heat exchange performance of the high-temperature radiant furnace tube with the turbulence structure according to the geometric parameters of the turbulence structure;

[0026] limiting the calculation results of the calculation model E2 according to the actual requirement of the heat exchange performance of the application scenario of the high-temperature radiant furnace tube with the turbulence structure, and obtaining the geometric parameters of the turbulence structure satisfying the heat exchange performance;

[0027] wherein the calculation model E2 is constructed as follows:

[0028]

[0029] wherein Nu rough represents the Nusselt number of the inner wall of the furnace tube with the turbulence structure, Nu smooth represents the Nusselt number of the inner wall of the smooth furnace tube, and k2, m2, n2, p2 represent fitting parameters, and the values thereof are respectively k2=15.375, m2=0.859, n2=-0.895, and p2=0.773.

[0030] Similarly, the geometric parameters of the turbulence structure satisfying the heat exchange performance in the above scheme can be a single parameter combination or multiple parameter combinations.

[0031] The above calculation model E2 of the present application uses the Nusselt number (Nu) as a key index for quantitatively evaluating the convective heat exchange capacity of the inner wall of the furnace tube, and the ratio between the Nusselt number Nu rough of the inner wall of the furnace tube with the turbulence structure and the Nusselt number Nu smoot of the inner wall of the smooth furnace tube directly reflects the contribution of the turbulence structure to the heat transfer enhancement. The greater the ratio, the more significant the enhancement of the turbulence structure to the convective heat exchange capacity, and the more helpful to improve the heat exchange efficiency of the furnace tube and improve the gas heating effect.

[0032] The above calculation model E2 and the calculation model E1 related to the pressure drop sensitivity can be mutually echoed, such as using the dimensionless parameters of H / D, P / D, and and the like, which can comprehensively describe the influence of the geometric parameters of the turbulence structure on the heat transfer characteristics.

[0033] In addition, from the physical meaning of model E2, it can be seen that the increase of H and N values will strengthen the fluid disturbance and turbulence effect, thereby increasing the heat transfer coefficient, resulting in the increase of Nusselt number; and the increase of P and D values will weaken the disturbance effect, thereby reducing the heat transfer strengthening effect. Through the formula, engineering personnel can quickly predict the promotion range of the heat transfer of the spoiler structure under different operating conditions, so as to realize the quantitative balance between energy efficiency improvement and structure optimization.

[0034] According to some preferred embodiments of the present application, the obtaining of the geometric parameters of the spoiler structure satisfying the heat transfer performance comprises: obtaining the geometric parameters of the spoiler structure satisfying the heat transfer performance under the condition that the geometric parameters of the spoiler structure satisfy the pressure drop sensitivity, and taking the maximum value of the calculation model E2 as the requirement of the application scenario of the high-temperature radiation furnace tube with the spoiler structure on the heat transfer performance.

[0035] In order to verify the accuracy of the above calculation model E2, the present application also provides a calculation model E3 for predicting the outlet gas temperature of the high-temperature radiation furnace tube with the spoiler structure according to the geometric parameters of the spoiler structure, which is rough The comparison between the predicted temperature obtained by model E3 and the actual temperature or the software simulation temperature determines the accuracy of the Nusselt number Nu rough calculated by model E2.

[0036] The calculation model E3 is as follows;

[0037]

[0038] Where, ΔT represents the difference between the outlet gas temperature and the inlet gas temperature of the unit length furnace tube, i.e. ΔT = T out -T in , wherein T out represents the outlet gas temperature of the furnace tube; T wall represents the furnace tube wall temperature, T in represents the inlet gas temperature of the furnace tube, Nu rough represents the Nusselt number of the inner wall of the furnace tube provided with the spoiler structure, and L represents an empirical constant for characterizing the enhancement degree of the heat transfer performance enhancement between the furnace wall and the gas, and the value of L is L = 0.00004.

[0039] The above calculation model E3 of the present application is established based on the heat transfer mechanism of convective heat transfer, comprehensively considers the influences of the furnace tube wall temperature, the inlet gas temperature and the heat transfer capacity along the way (introduced through the Nu rough parameter), and can intuitively reflect the temperature evolution law of the gas in the process of flowing in the tube.

[0040] The above calculation model E3 of the present application fully considers that the change of the gas outlet temperature is not only affected by the inlet temperature and the wall temperature of the furnace tube, but also obviously affected by the convective heat exchange capacity along the furnace tube, and therefore the calculation model E3 reliably characterizes the capacity by Nusselt number (Nu). Meanwhile, considering that the effect of the turbulence structure on the gas outlet temperature is indirect, mainly by changing the local convective heat exchange coefficient in the furnace tube, thereby affecting the overall temperature change of the gas, therefore, the present application does not directly establish a gas outlet temperature calculation model by the geometric parameters of the turbulence structure.

[0041] The above calculation model E3 of the present application simultaneously reveals the exponential decay characteristics of the gas heat transfer process in the furnace tube: when the heat exchange capacity is strong, the temperature difference between the gas and the wall surface rapidly decays, and the outlet temperature tends to the wall temperature; when Nu is low, the temperature difference decays slowly, and the outlet temperature is limitedly increased.

[0042] Based on the above unexpected findings, it can be seen that the combination of the models E1, E2 and E3 of the present application can obtain a complete prediction chain of the furnace tube pressure drop performance prediction, the furnace tube heat exchange performance prediction and the furnace tube outlet gas temperature prediction from the geometric parameters of the turbulence structure, ensuring the rationality of the physical mechanism, significantly improving the reliability and engineering applicability of the prediction results, and providing a systematic engineering design method for furnace tube design optimization, energy efficiency evaluation and operation condition regulation.

[0043] According to some preferred embodiments of the present application, the design method comprises:

[0044] predicting the influence of the geometric parameters of the turbulence structure on the pressure drop of the high-temperature radiation furnace tube with the turbulence structure, i.e. the pressure drop sensitivity of the high-temperature radiation furnace tube with the turbulence structure, by the calculation model E1;

[0045] obtaining the first constraint condition that the geometric parameters of the turbulence structure need to satisfy based on the calculation model E1 according to the actual requirements of the application scene of the high-temperature radiation furnace tube with the turbulence structure on the pressure drop sensitivity;

[0046] predicting the heat exchange performance of the high-temperature radiation furnace tube with the turbulence structure by the calculation model E2;

[0047] obtaining the second constraint condition that the geometric parameters of the turbulence structure need to satisfy based on the calculation model E2 according to the actual requirements of the application scene of the high-temperature radiation furnace tube with the turbulence structure on the heat exchange performance;

[0048] obtaining the optimization function that the geometric parameters of the turbulence structure need to satisfy by combining the first constraint condition, the second constraint condition and other constraint conditions about the actual production requirements;

[0049] obtaining the optimal geometric parameters of the turbulence structure by solving the optimal solution of the optimization function;

[0050] designing the spoiler structure according to the optimal geometric parameter of the spoiler structure.

[0051] According to some preferred embodiments of the present application, the other constraints include one or more of the following: minimum H value, maximum H value, minimum H / D value, maximum H / D value, minimum P / D value, maximum P / D value, minimum N value, maximum N value of the spoiler structure limited by the preparation process capability, minimum D value, maximum D value limited by the production requirement, minimum H value, maximum H value, minimum H / D value, maximum H / D value, minimum P / D value, maximum P / D value, minimum N value, maximum N value limited by the corrosion resistance and / or thermal shock resistance requirement of the spoiler structure material.

[0052] The present application further provides a high-temperature radiant furnace tube containing a spoiler structure, which is obtained according to the above design method.

[0053] The present application further provides a high-temperature radiant furnace tube containing a spoiler structure, which is provided with uniformly or staggered distributed hemispherical spoiler structures on the inner wall of the high-temperature radiant furnace tube, and the geometric parameter of the spoiler structure is the optimal geometric parameter of the spoiler structure; the optimal geometric parameter of the spoiler structure is obtained by the following process:

[0054] predicting the influence of the geometric parameter of the spoiler structure on the pressure drop of the high-temperature radiant furnace tube containing the spoiler structure, i.e. the pressure drop sensitivity of the high-temperature radiant furnace tube containing the spoiler structure, by the calculation model E1;

[0055] obtaining the first constraint condition that the geometric parameter of the spoiler structure based on the calculation model E1 needs to meet according to the actual requirement of the pressure drop sensitivity of the application scenario of the high-temperature radiant furnace tube containing the spoiler structure;

[0056] predicting the heat exchange performance of the high-temperature radiant furnace tube containing the spoiler structure by the calculation model E2;

[0057] obtaining the second constraint condition that the geometric parameter of the spoiler structure based on the calculation model E2 needs to meet according to the actual requirement of the heat exchange performance of the application scenario of the high-temperature radiant furnace tube containing the spoiler structure;

[0058] obtaining the optimization function that the geometric parameter of the spoiler structure needs to meet by combining the first constraint condition, the second constraint condition and other constraint conditions about the actual production requirement;

[0059] obtaining the optimal geometric parameter of the spoiler structure by solving the optimal solution of the optimization function;

[0060] and the geometric parameter of the spoiler structure meets D = 40-300mm, H / D = 0.02-0.15, P / D = 0.03-5, N = 3-48.

[0061] The application further provides a preparation method of the high-temperature radiant furnace tube with the turbulence structure, and the turbulence structure is formed by surfacing with anti-carburizing metal powder material selected from one or more of HP alloy, 35 / 45 alloy and anti-coking heat-resistant corrosion-resistant alloy.

[0062] The anti-carburizing metal powder material can be selected according to different application scenarios, for example, the anti-coking heat-resistant corrosion-resistant alloy for ethylene cracking, the HP alloy, 35 / 45 alloy or other heat-resistant corrosion-resistant alloy similar to the base material of the furnace tube for hydrogen production reformer.

[0063] The application further provides an application method of the high-temperature radiant furnace tube, which is applied in an ethylene cracking furnace and / or a hydrogen production reformer.

[0064] The application has the following beneficial effects:

[0065] Compared with the actual measurement method or the numerical simulation method, the design method of the application can obtain the optimized design scheme of the furnace tube with the turbulence structure more quickly.

[0066] The design method of the application can be customized and optimized according to different requirements of the furnace tube under different working conditions, such as pressure drop, heat exchange performance and outlet temperature, and can obtain a design structure that maximizes the heat exchange efficiency of the furnace tube under the premise of meeting the pressure drop control.

[0067] The design method of the application can realize complete correlation from the geometric parameters of the turbulence structure to the engineering performance, can accurately predict the pressure drop, Nusselt number and outlet temperature of the furnace tube under a specific working condition, and thus obtain the optimized design scheme of different turbulence structures.

[0068] The application can solve the problem that the existing furnace tube with the turbulence structure has a significant increase in pressure drop while strengthening heat transfer, and can balance heat transfer strengthening and pressure drop control to improve the reaction performance.

[0069] The design method of the application or the obtained furnace tube can be applied under various working conditions and can be flexibly adjusted according to the pressure drop sensitivity. BRIEF DESCRIPTION OF DRAWINGS

[0070] Figure 1 The structure schematic diagram of the sample obtained by the embodiment of the application, wherein (a) is a perspective view of the inner surface of the sample with uniformly distributed turbulence structures, (b) is a cross-sectional schematic diagram of the sample with uniformly distributed turbulence structures, (c) is an inner surface development diagram of the sample with uniformly distributed turbulence structures, (d) is an inner surface development diagram of the sample with staggered turbulence structures, and (e) is a schematic diagram of the shape of a single turbulence structure.

[0071] Figure 2The sample obtained for the embodiment of the present application is a physical map;

[0072] Figure 3 The comparison chart of the CFD simulated pressure drop ratio of sample 1-17 obtained in embodiment 2 and the pressure drop ratio calculated by model E1;

[0073] Figure 4 The comparison chart of the CFD simulated Nusselt number ratio of sample 1-17 obtained in embodiment 2 and the Nusselt number ratio calculated by model E2;

[0074] Figure 5 The comparison chart of the CFD simulated outlet-inlet gas temperature difference of sample 1-17 obtained in embodiment 2 and the outlet-inlet gas temperature difference calculated by model E3;

[0075] Figure 6 The schematic diagram of the test device of embodiment 3. DETAILED DESCRIPTION

[0076] The technical solutions in the present application will be further described below in combination with the embodiments of the present application and the accompanying drawings. The embodiments described below are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should fall within the protection scope of the present application.

[0077] The turbulence structure in the following embodiments is shown in the accompanying drawings as follows: Figure 1 、 2 .

[0078] The meanings of the parameters in the following embodiments are as follows:

[0079] D represents the inner diameter of the furnace tube, H represents the distance from the top point of the turbulence structure to the center of the bottom, i.e. the radius of the hemispherical turbulence structure, P represents the axial spacing of the adjacent turbulence structures located on the same axis (when the turbulence structures are uniformly distributed, it is the axial spacing between the two closest turbulence structures in the axial direction, as shown in the accompanying drawings as follows: Figure 1 (c); When the turbulence structures are staggered, it is obviously greater than the axial spacing between the two closest turbulence structures in the axial direction Q, as shown in the accompanying drawings as follows: Figure 1 (d); N represents the total number of turbulence structures covered by the furnace tube circumference within the axial spacing of the adjacent turbulence structures located on the same axis, and Coverage represents the total circumferential coverage rate of the turbulence structures of the furnace tube circumference within a unit axial length. .

[0080] The calculation models E1, E2 and E3 used are as follows:

[0081] E1:

[0082]

[0083] wherein ΔP rough represents the pressure drop of the furnace tube provided with the turbulence structure, ΔP smooth represents the pressure drop of the smooth furnace tube, represents the pressure drop ratio, H represents the distance from the top of the turbulence structure to the center of the bottom, D represents the inner diameter of the furnace tube, P represents the axial spacing of the turbulence structure, N represents the number of the turbulence structures in the furnace tube in the circumferential direction within the axial spacing of the adjacent turbulence structures located in the same axis, and π represents the circular constant; k1, m1, n1, p1 represent the fitting parameters, and the values thereof are respectively k1 = 178.227, m1 = 1.117, n1 = -1.019, and p1 = 1.209;

[0084] E2:

[0085]

[0086] wherein Nu rough represents the Nusselt number of the inner wall of the furnace tube provided with the turbulence structure, Nu smooth represents the Nusselt number of the inner wall of the smooth furnace tube, represents the Nusselt number ratio, and k2, m2, n2, p2 represent the fitting parameters, and the values thereof are respectively k2 = 15.375, m2 = 0.859, n2 = -0.895, and p2 = 0.773;

[0087] E3:

[0088]

[0089] wherein ΔT represents the difference between the outlet gas temperature and the inlet gas temperature of the furnace tube per unit length, i.e. the outlet temperature difference, T wall represents the furnace tube wall temperature, T in represents the furnace tube inlet gas temperature, Nu rough represents the Nusselt number of the inner wall of the furnace tube provided with the turbulence structure, and L represents an empirical constant used to represent the enhancement degree of the temperature difference between the furnace wall and the gas due to the enhancement of the heat exchange performance, and the value thereof is L = 0.00004.

[0090] Example 1

[0091] The furnace tube samples 1-17 shown in Table 1 were obtained (wherein Q greater than 0 represents that the turbulence structures are staggered):

[0092] Table 1 Turbulence structure geometric parameters of samples

[0093]

[0094] Example 2

[0095] Numerical simulations of the smooth tube and the sample from Example 1 were performed using Fluent software based on fluid dynamics (CFD) methods. This allowed for a systematic analysis of the influence of the geometric parameters of different turbulence structures on flow resistance and heat transfer performance in Example 1 without relying on a large number of experimental prototypes.

[0096] The simulation parameters are as follows: total furnace tube length 1000 mm, inner diameter 50 mm, gas inlet velocity 160 m / s, inlet temperature 600 ℃; tube wall material is stainless steel, surface micro-roughness height is approximately 1×10⁻⁶. −6 m can be approximated as a smooth tube; the tube wall temperature is constant at 900℃, and the SST k-ω model is selected as the turbulence model, which combines... k-ε and k-ω The model's advantage lies in its performance near the wall. k-ω The model transitions to a free-flow region. k-ε This model is suitable for complex flows with boundary layer separation, strong pressure gradients, and vortex structures. It can calculate turbulent kinetic energy, specific dissipation rate, and the distribution of flow field parameters such as velocity, pressure, and temperature. It offers high accuracy in near-wall flow prediction, simultaneously and accurately capturing the turbulent characteristics of both the viscous sublayer and the free flow region at the wall. In engineering, it is commonly used to predict frictional drag, heat transfer coefficient, and wall heat transfer characteristics.

[0097] The simulation setup also includes: in mesh generation and near-wall treatment, a boundary layer expansion layer is used to generate a progressively finer mesh on the wall. The expansion layer is set to 15 layers, with the initial layer thickness allowing y⁺ to be controlled around 1, and the growth rate controlled at 1.1. The expansion layer is sufficient to cover the velocity and thermal boundary layer thickness to ensure the accuracy of the friction factor and Nusselt number (Nu) calculations. The mesh is further refined in local turbulence protrusions to avoid numerical errors caused by geometric abrupt changes.

[0098] In the simulation, calculations were first performed on a smooth tube without any turbulence structures to obtain baseline values ​​for pressure drop and heat transfer performance, and to verify the rationality of the numerical model and boundary conditions selected in this embodiment. The simulation results show that the pressure drop of the smooth tube is approximately 2930 Pa, and the outlet gas temperature rise is approximately 30 °C, which is consistent with the calculation results of the model in this invention.

[0099] Furthermore, under the same numerical model and boundary conditions, CFD simulations were performed on samples 1-17 of Example 1 to obtain the CFD simulated Nusselt number (CFD-Nusser number), CFD simulated pressure drop (CFD-pressure drop), CFD simulated Nusselt number ratio (CFD-Nusser number ratio), CFD simulated pressure drop ratio (CFD-pressure drop ratio), and CFD simulated outlet temperature difference (CFD-outlet temperature difference). These results were compared with the pressure drop ratio (E1-pressure drop ratio), Nusselt number ratio (E2-Nusser number ratio), and outlet temperature difference (E3-outlet temperature difference) calculated by models E1, E2, and E3 according to the present invention. The results are shown in Table 2 and Appendix. Figure 3 , 4 As shown in Figure 5 ( Figure 5 The temperature difference between the outlet and the outlet is expressed as the temperature rise at the outlet by ΔT.

[0100] Table 2 Comparison of simulated and calculated values ​​for the samples

[0101]

[0102] As shown in Figure 3, when the pressure drop ratio is in the range of 1-2.5, the calculation results of model E1 are in good agreement with the CFD simulation values. The trends of the pressure drop ratio obtained by both models with the structural parameters (H / D, P / D, N·2H / πD) are basically consistent, and the numerical deviation is small. When the pressure drop ratio is in the range of 2.5-5.5, the numerical deviation between the two models increases, but the overall trend remains consistent. In addition, comparing Implementations 9 and 10, the only difference between them is whether the arrangement of the flow structure is staggered. The CFD simulation results show that the pressure drop data are very close, and model E1 can also accurately predict the results of the two different arrangements. Therefore, model E1 can effectively predict the influence of different geometric parameters of the flow structure and different arrangements on the pressure drop ratio.

[0103] As shown in Figure 4, when the pressure drop ratio is in the range of 1-1.6, the calculation results of model E2 show good consistency with the CFD simulation values. The Nusselt number ratios obtained by both models show basically the same trend with the structural parameters (H / D, P / D, N·2H / πD), with small numerical deviations. However, when the pressure drop ratio is in the range of 1.6-3, the difference between the two models increases. This indicates that as the flow intensity increases, the flow structure becomes more complex, and both CFD simulations and empirical models may have some deviations in their predictions of the actual situation, but these deviations are still within a reasonable range. Comparing Implementations 9 and 10, the only difference is whether the arrangement of the flow structure is staggered. The CFD simulation results show that the Nusselt number ratios are basically the same, and model E2 can also accurately predict the results of the two different arrangements. In summary, model E2 can effectively predict the influence of different geometric parameters of the turbulent structure on the Nusselt number ratio.

[0104] As shown in Figure 5, under the same gas inlet temperature (600 ℃), the gas outlet temperature increases by approximately 30–80 ℃ depending on the geometric parameters of the turbulence structure. This temperature increase is mainly determined by the Nusselt number ratio, which is influenced by the combined effects of the geometric parameters H / D, P / D, and N·2H / πD of the turbulence structure. The comparison between the CFD and E3 results shows good consistency, further validating the accuracy of model E2 in predicting the Nusselt number ratio and model E3 in predicting the outlet temperature difference.

[0105] Example 3

[0106] Laboratory tests were conducted on samples 1, 3, and 4 of Example 1, which have typical turbulence structure parameters. The testing apparatus is shown in the attached figure. Figure 6 As shown, it includes: a sample furnace tube 1 installed in a high-temperature furnace 3, a preheating furnace tube 2 connected to the inlet end of the sample furnace tube 1, and a cooling furnace tube 4 connected to its outlet end. The preheating furnace tube 2 and the cooling furnace tube 4 have the same inner diameter and wall thickness as the sample furnace tube 1, the only difference being that the preheating furnace tube 2 and the cooling furnace tube 4 are smooth tubes without a turbulence structure. The preheating furnace tube 2 is connected to a blower 11 through an inlet elbow 7, and the cooling furnace tube 4 is connected to the outside through an outlet elbow 8. An inlet temperature and pressure measuring device 5 and an inlet furnace tube surface thermocouple 10 are installed between the preheating furnace tube 2 and the sample furnace tube 1, and an outlet temperature and pressure measuring device 6 and an outlet furnace tube surface thermocouple 9 are installed between the cooling furnace tube 4 and the sample furnace tube 1. The sample furnace tube 1 has a length of 1000 mm, an outer diameter of 64 mm, an inner diameter of 50 mm, and the turbulence structure is formed by HP high-temperature alloy powder overlay welding.

[0107] In the above device, the preheating furnace tube 2 and the cooling furnace tube 4 can be used to heat and cool the gas respectively, which can ensure the temperature uniformity of the sample furnace tube 1. During the test, the length of the preheating furnace tube 2 in the high temperature furnace 3 is adjusted by moving the position of the high temperature furnace 3 up and down, thereby adjusting the inlet temperature of the gas at the sample inlet.

[0108] The testing process was as follows: The inlet gas velocity was maintained at 160 m / s using blower 11. The furnace tubes were heated by high-temperature furnace 3 until the temperatures measured by thermocouples 9 and 10 on the inlet and outlet tube surfaces reached 900±5℃. The inlet gas temperature measured by inlet temperature and pressure measuring device 5 was 600±5℃. The pressure and temperature data of the outlet gas of different sample furnace tubes were recorded by outlet temperature and pressure measuring device 6. Based on the recorded data, the pressure drop, pressure drop ratio, and temperature difference between the outlet gas temperature and the inlet gas temperature of sample furnace tube 1 were calculated, i.e., the measured pressure drop, measured pressure drop ratio, and measured outlet temperature difference. The results are shown in Table 3 below.

[0109] Table 3. Measured results of samples 3 and 4

[0110]

[0111] The comparison of the measured pressure drop ratio, measured outlet temperature, etc. with the pressure drop ratio and outlet temperature difference calculated according to the model E1, E2 and E3 of the application and the simulated pressure drop ratio and simulated outlet temperature difference obtained according to the CFD simulation method of Example 2 (as shown in Table 2) shows that the measured values are in the same order of magnitude as the prediction results of the model of the application and the CFD numerical simulation results, and the change trends are highly consistent, and the obtained results are basically consistent, verifying the correctness and engineering feasibility of the model established in the application.

[0112] Example 4

[0113] Under the working condition of a furnace tube inner diameter D = 50 mm and an inlet gas flow rate of 160 m, based on the actual production capacity (the minimum thickness of the surfacing process is about 1 mm, corresponding to the minimum H / D value of 0.02) and material requirements (the turbulence structure will be subjected to scouring and corrosion during use, in order to avoid the influence of scouring and corrosion as much as possible, the maximum H / D value is set to 0.14, the P / D value is 0.3-6, and the N value is 3-12), the turbulence structure geometric parameters are designed according to different pressure drop sensitivities, including:

[0114] The value range of H / D, P / D and N is uniformly divided, for example, each is divided into 20 parts, thereby obtaining 20x20x20=8000 parameter combinations;

[0115] The model E1 is used to screen the 8000 parameter combinations to obtain a parameter set meeting the pressure drop sensitivity requirement;

[0116] The model E2 is used to select a parameter set close to the optimal solution from the parameter set meeting the pressure drop sensitivity requirement, to obtain a plurality of optimal turbulence structure geometric parameters.

[0117] Among them, under the condition of extremely sensitive pressure drop (DP<2) such as some ethylene cracking furnace tubes, the optimal turbulence structure geometric parameters obtained by the above process are shown in Table 4 combinations a and b:

[0118] Table 4 Optimal turbulence structure parameters under the condition of extremely sensitive pressure drop

[0119]

[0120] The above optimal structure parameters can obtain low pressure drop while significantly improving the Nusselt number, achieving the balance between heat transfer intensification and pressure drop control.

[0121] Some other optimal (i.e. closer to the maximum Nusselt number ratio) spoiler structure parameters are as follows: H / D = 0.08, P / D = 3.4, N = 9 (Nusselt number ratio is 1.36); H / D = 0.1, P / D = 4.1, N = 11 (Nusselt number ratio is 1.45); H / D = 0.08, P / D = 2.8, N = 9 (Nusselt number ratio is 1.43).

[0122] When the pressure drop sensitivity is relatively sensitive (2≤DP<5), the optimal spoiler structure geometric parameters obtained by the above process are shown in Table 5 combinations c and d as follows:

[0123] Table 5 Optimal spoiler structure parameters under the condition of relatively sensitive pressure drop

[0124]

[0125] The above optimal structure parameters can obtain higher Nusselt number and higher heat exchange efficiency with moderate increase in pressure drop, and are suitable for conditions with higher pressure drop tolerance.

[0126] Some other optimal spoiler structure parameters are as follows: H / D = 0.14, P / D = 3.4, N = 10 (Nusselt number ratio is 1.8); H / D = 0.11, P / D = 2.8, N = 11 (Nusselt number ratio is 1.8); H / D = 0.06, P / D = 1.6, N = 21 (Nusselt number ratio is 1.7).

[0127] When the pressure drop sensitivity is not sensitive (DP≥5), the optimal spoiler structure geometric parameters obtained by the above process are shown in Table 6 combination e as follows:

[0128] Table 6 Optimal spoiler structure parameters under the condition of not sensitive pressure drop

[0129]

[0130] The above optimal structure parameters can maximize the Nusselt number and obtain the efficiency of enhanced convective heat transfer without strict constraints on the pressure drop.

[0131] Some other optimal spoiler structure parameters are as follows: H / D = 0.13, P / D = 0.3, N = 10 (Nusselt number ratio is 7.4); H / D = 0.11, P / D = 0.3, N = 11 (Nusselt number ratio is 6.8).

[0132] It should be noted that the above only describes the preferred embodiments of the present application, which should not limit the protection scope of the technical solutions of the present application. Any modifications made by those skilled in the art to the technical solutions described in the foregoing embodiments, equivalent replacements of technical features, etc. shall be included in the protection scope of the present application.

Claims

1. A method of designing a high temperature radiant furnace tube with a turbulence inducing structure, characterized by, It comprises: constructing a calculation model E1 for predicting the influence of the geometric parameters of the spoiler structure on the pressure drop of the high-temperature radiant furnace tube with the spoiler structure, i.e., the predicted pressure drop sensitivity of the high-temperature radiant furnace tube with the spoiler structure; limiting the calculation results of the calculation model E1 according to the actual requirements of the pressure drop sensitivity of the application scene of the high-temperature radiant furnace tube with the spoiler structure, and obtaining the geometric parameters of the spoiler structure that meet the pressure drop sensitivity; constructing a calculation model E2 for predicting the heat exchange performance of the high-temperature radiant furnace tube with the spoiler structure according to the geometric parameters of the spoiler structure; limiting the calculation results of the calculation model E2 according to the actual requirements of the heat exchange performance of the application scene of the high-temperature radiant furnace tube with the spoiler structure, and obtaining the geometric parameters of the spoiler structure that meet the heat exchange performance; wherein the calculation model E1 is constructed as follows: ； wherein ΔP rough represents the pressure drop of the furnace tube provided with the spoiler structure, ΔP smooth represents the pressure drop of the smooth furnace tube, H represents the distance from the top of the spoiler structure to the center of the bottom, D represents the inner diameter of the furnace tube, P represents the axial distance between adjacent spoiler structures on the same axis, N represents the total number of spoiler structures covered by the furnace tube on the same axis within the axial distance between adjacent spoiler structures, and π represents the circular constant; k1, m1, n1, and p1 represent fitting parameters, and their values are respectively k1=178.227, m1=1.117, n1=-1.019, and p1=1.

209. wherein the spoiler structure is hemispherical, uniformly or staggered distributed on the inner wall of the high-temperature radiant furnace tube, and the geometric parameters of the spoiler structure meet D = 40-300mm, H / D = 0.02-0.15, P / D = 0.03-5, N = 3-48; The calculation model E2 is constructed as follows: ； where Nu rough represents the Nusselt number of the inner wall of the furnace tube provided with the spoiler structure, Nu smooth represents the Nusselt number of the inner wall of the smooth furnace tube, k2, m2, n2, p2 represent fitting parameters, and their values are respectively: k2 = 15.375, m2 = 0.859, n2 = -0.895, p2 = 0.

773.

2. The method of designing a high-temperature radiant furnace tube according to claim 1, wherein It comprises: under the geometric parameters of the spoiler structure that meet the pressure drop sensitivity, taking the maximum value of the calculation model E2 as the requirement of the heat exchange performance of the application scene of the high-temperature radiant furnace tube with the spoiler structure, and obtaining the geometric parameters of the spoiler structure that meet the heat exchange performance.

3. The method of designing according to claim 1, wherein, It comprises: predicting the influence of the geometric parameters of the spoiler structure on the pressure drop of the high-temperature radiant furnace tube with the spoiler structure through the calculation model E1, i.e., the pressure drop sensitivity of the high-temperature radiant furnace tube with the spoiler structure; obtaining the first constraint condition that the geometric parameters of the spoiler structure need to meet based on the calculation model E1 according to the actual requirements of the pressure drop sensitivity of the application scene of the high-temperature radiant furnace tube with the spoiler structure; predicting the heat exchange performance of the high-temperature radiant furnace tube with the spoiler structure through the calculation model E2; obtaining the second constraint condition that the geometric parameters of the spoiler structure need to meet based on the calculation model E2 according to the actual requirements of the heat exchange performance of the application scene of the high-temperature radiant furnace tube with the spoiler structure; obtaining the optimization function that the geometric parameters of the spoiler structure need to meet by combining the first constraint condition, the second constraint condition and other constraint conditions related to actual production requirements; obtaining the optimal geometric parameters of the spoiler structure by solving the optimal solution of the optimization function; designing the spoiler structure according to the optimal geometric parameters of the spoiler structure.

4. The method of designing according to claim 3, wherein, The other constraint conditions include: one or more of the minimum H value, the maximum H value, the minimum H / D value, the maximum H / D value, the minimum P / D value, the maximum P / D value, the minimum N value, the maximum N value of the spoiler structure limited by the preparation process capability, the minimum D value, the maximum D value limited by the production demand, and the minimum H value, the maximum H value, the minimum H / D value, the maximum H / D value, the minimum P / D value, the maximum P / D value, the minimum N value, the maximum N value limited by the corrosion resistance and / or thermal shock resistance requirements of the spoiler structure material.

5. The high-temperature radiant furnace tube with the spoiler structure obtained by the design method of any one of claims 1-4.

6. A high-temperature radiant furnace tube containing a spoiler structure according to claim 5, characterized in that, It is provided with evenly or staggered distributed semi-spherical turbulence structure on the inner wall of high temperature radiation furnace tube, the geometric parameters of the turbulence structure are the optimal geometric parameters of the turbulence structure; the optimal geometric parameters of the turbulence structure are obtained through the following process: The influence of the geometric parameters of the turbulence structure on the pressure drop of the high temperature radiation furnace tube containing the turbulence structure is predicted by the calculation model E1, i.e. the pressure drop sensitivity of the high temperature radiation furnace tube containing the turbulence structure; According to the actual requirement of the pressure drop sensitivity of the application scene of the high temperature radiation furnace tube containing the turbulence structure, the first constraint condition that the geometric parameters of the turbulence structure based on the calculation model E1 need to meet is obtained; The heat exchange performance of the high temperature radiation furnace tube containing the turbulence structure is predicted by the calculation model E2; According to the actual requirement of the heat exchange performance of the application scene of the high temperature radiation furnace tube containing the turbulence structure, the second constraint condition that the geometric parameters of the turbulence structure based on the calculation model E2 need to meet is obtained; The first constraint condition, the second constraint condition and other constraint conditions about the actual production requirement are combined to obtain the optimization function that the geometric parameters of the turbulence structure need to meet; The optimal solution of the optimization function is solved to obtain the optimal geometric parameters of the turbulence structure; Wherein, The calculation model E1 is as follows: ； wherein ΔP rough represents the pressure drop of the furnace tube provided with the spoiler structure, ΔP smooth represents the pressure drop of the smooth furnace tube, H represents the distance from the top of the spoiler structure to the center of the bottom, D represents the inner diameter of the furnace tube, P represents the axial distance between adjacent spoiler structures on the same axis, N represents the total number of spoiler structures covered by the furnace tube on the same axis within the axial distance between adjacent spoiler structures, and π represents the circular constant; k1, m1, n1, and p1 represent fitting parameters, and their values are respectively k1=178.227, m1=1.117, n1=-1.019, and p1=1.

209. The calculation model E2 is as follows: ； Nu = k2·Re m2·Pr n2·p2wherein Nu rough represents the Nusselt number of the furnace tube provided with the spoiler structure, Nu smooth represents the Nusselt number of the smooth furnace tube, k2, m2, n2, p2 represent fitting parameters, and their values are respectively: k2 = 15.375, m2 = 0.859, n2 = -0.895, p2 = 0.773; And the geometric parameters of the turbulence structure meet D=40-300mm, H / D=0.02-0.15, P / D=0.03-5, N=3-48.

7. The method of producing a high-temperature radiant furnace tube with a turbulence structure according to claim 5 or 6, characterized in that, It includes: The turbulence structure is formed by surfacing with anti-carburizing metal powder material, and the anti-carburizing metal powder material is selected from one or more of HP alloy, 35 / 45 alloy, anti-coking heat-resistant corrosion-resistant alloy.

8. The application of the high temperature radiation furnace tube containing the turbulence structure according to claim 5 or 6 in ethylene cracking furnace and / or hydrogen production reformer.

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