High-temperature radiation furnace tube for enhancing heat transfer as well as preparation method and application thereof

Abstract

The invention discloses a high-temperature radiation furnace tube for enhancing heat transfer as well as a preparation method and application of the high-temperature radiation furnace tube. The heat-transfer-enhanced high-temperature radiation furnace tube comprises a high-temperature radiation furnace tube, namely a thick tube, of which the inner surface is subjected to roughness treatment and / or a high-temperature radiation furnace tube, namely a streaming terminal, of which the inner surface is sequentially subjected to roughness treatment and streaming structure surfacing treatment, and the roughness parameter Ra of the inner surface of the thick tube is 3.2-40.5 m; and the streaming structure is in one or more forms of a sphere, a raindrop shape and a strip shape. According to the invention, the heat conduction effect and the temperature and airflow uniformity of the furnace tube can be obviously improved through combination of slight increase of the inner surface area and a micron-scale inner surface streaming structure within a certain range, meanwhile, the filling volume of a catalyst in the furnace tube is not influenced, and obvious pressure drop at the outlet end of the furnace tube is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of high-temperature alloy heat radiation furnace tubes, in particular to hydrogen production strengthening furnace tubes, ethylene cracking furnace tubes and iron ore reduction furnace tubes. Background Art

[0002] High temperature radiation furnace tubes play a key role in the preparation of many chemical products, such as hydrogen conversion, petroleum cracking, iron ore reduction, etc.

[0003] Among them, the core component of hydrogen production conversion is the hydrogen production conversion radiation furnace tube. The conversion reaction occurring in the furnace tube includes methane steam reforming reaction. The former is a highly endothermic reaction and requires a continuous heat supply. It adopts a high-temperature radiation furnace tube. The furnace tube is filled with relevant catalysts and reaction media to complete the relevant chemical reactions. The outside of the furnace tube is a furnace. Through the combustion of natural gas in the furnace, the heat is transferred to the outer surface of the furnace tube in the form of thermal radiation. The heat is transferred to the internal reaction medium and catalyst bed through the wall thickness and inner surface to provide the required heat for the reaction. In the existing hydrogen production conversion furnace tube, due to the viscosity of the medium gas and the tube wall, it will appear a significant speed drop near the tube wall. Even if the catalyst inside the furnace tube will produce a circumferential flow effect of the gas medium, there is still a relatively obvious boundary layer on the inner wall of the furnace tube, so that the gas velocity and temperature in the furnace tube form a significant gradient distribution in the radial direction, resulting in a decrease in its heat conduction efficiency and stability.

[0004] In the high-temperature radiation furnace tube of the ethylene cracking furnace, heat energy is transferred to the gas medium through the furnace tube wall, so that the reaction temperature rises rapidly to promote the cracking reaction. The temperature inside the furnace tube is the key control factor of the cracking process. The uniformity of the airflow distribution inside the furnace tube is also important to avoid local overheating or uneven temperature. Uniform temperature and airflow distribution can improve thermal efficiency and selectivity of cracking reaction. However, in the existing ethylene cracking furnace tube, there is an obvious boundary layer effect in the radial direction inside the furnace tube, and the unevenness of temperature distribution and airflow velocity is more significant.

[0005] Compared with traditional blast furnace ironmaking, the direct reduction technology of iron ore has lower carbon emissions and energy consumption. Its high-temperature radiation furnace usually reacts natural gas or by-product gas at high temperature to produce reducing gases such as hydrogen and carbon monoxide, which are used to remove oxygen from iron ore to produce metallic pure iron. The operating temperature of this furnace tube is higher than that of traditional hydrogen production converters, and the energy efficiency and temperature uniformity of the furnace tube are required to be higher. The existing high-temperature radiation furnace tube needs to be improved to meet the requirements of higher temperature and higher production capacity. Summary of the invention

[0006] In view of the defects of the prior art, the purpose of the present invention is to propose a high-temperature radiation furnace tube with enhanced heat transfer and a preparation method and application thereof. The high-temperature radiation furnace tube with enhanced heat transfer can significantly improve the heat conduction effect and temperature and air flow uniformity of the furnace tube by combining a slight increase in the inner surface area and an inner surface flow structure of the micron order within a certain range. At the same time, it does not affect the filling volume of the catalyst in the furnace tube and the original flow capacity.

[0007] The technical solution of the present invention is as follows: A high-temperature radiation furnace tube for enhanced heat transfer comprises: a high-temperature radiation furnace tube whose inner surface has been roughened, i.e., a thick tube, and / or a high-temperature radiation furnace tube whose inner surface has been roughened and subjected to flow-around structure surfacing treatment in sequence, i.e., a flow-around terminal, wherein the inner surface roughness parameter Ra of the thick tube is 3.2-40.5 µm, and the shape of the flow-around structure is one or more of spherical, raindrop-shaped, and strip-shaped.

[0008] The above technical solution of the present invention only expands the surface of the furnace tube at the level of roughness treatment, and the bypass terminal can be locally set as needed. The two work together to significantly improve the heat conduction efficiency of the space close to the inner wall of the furnace tube (0-2mm); at the same time, the roughness treatment of the present invention and the setting of the micron-level bypass terminal do not affect the catalyst loading and the original furnace tube gas flow at all; in addition, the roughness treatment and terminal manufacturing process are relatively simple and fast, avoiding the manufacturing method with greater machining difficulty and higher cost.

[0009] In the above technical solution of the present invention, the roughness of the original furnace tube is increased from the smooth surface of Ra1.6µm to the non-smooth surface of Ra3.2-40.5µm, thereby increasing the contact area of ​​heat conduction, generating a flow around the near field of the inner wall of the furnace tube, and reducing the influence of the boundary layer. On this basis, the heat conduction efficiency is improved by further strengthening the flow terminal. The different forms of flow terminals have different functions. The spherical terminal is relatively simple to make, has strong symmetry, and has obvious use effect; the strip flow terminal increases the thermal contact area on the basis of the spherical shape, and its wake area is close to the spherical shape; the raindrop-shaped flow terminal reduces the separation phenomenon through the rounded transition of the front and the gradual contraction of the rear, making the wake area smaller and reducing the resistance when the medium flows through.

[0010] According to some preferred embodiments of the present invention, the flow-around structure is spherical, and the height f of the spherical flow-around structure protruding on the inner surface of the furnace tube is 100-2000µm, and the diameter e projected onto the inner surface of the furnace tube is 1000µm-10mm.

[0011] More preferably, f is 800 µm and e is 1000 µm.

[0012] According to some preferred embodiments of the present invention, the flow-around structure is in a raindrop shape, and the height d of the raindrop-shaped flow-around structure protruding on the inner surface of the furnace tube is 100-2000 µm, and the width a projected onto the inner surface of the furnace tube is 1000µm-10mm. It has a front spherical head and a rear conical tail, and the radius b of the head and the length c of the tail are both 500µm-50mm.

[0013] More preferably, a is 3000µm.

[0014] According to some preferred embodiments of the present invention, the flow-around structure is in the shape of a strip, the total length i of the strip-shaped flow-around structure is 1-500 mm, it contains a spherical head and tail and a cylindrical middle part, the width h projected onto the inner surface of the furnace tube is 1000µm - 30 mm, the height j of the head and tail protruding from the inner surface of the furnace tube and the height k of the middle part protruding from the inner surface of the furnace tube are both 100-2000 µm.

[0015] According to some preferred embodiments of the present invention, the flow-by-flow terminal includes one or more flow-by-flow structure layers, each flow-by-flow structure layer includes a plurality of evenly distributed flow-by-flow structures, and a circumferential angle α between a center position of each flow-by-flow structure and a cross-section of a high-temperature radiation furnace tube is 0-120°.

[0016] For example, when the angle α is 120°, each flow-around structure layer contains 3 evenly distributed flow-around structures. For example, when the angle α is 10°, each flow-around structure layer contains 36 evenly distributed flow-around structures.

[0017] Or, any of the flow-around structure layers contains a plurality of non-uniformly distributed flow-around structures.

[0018] For example, between 0-90°, the circumferential angle α between the center position of the flow structure and the cross section of the high-temperature radiation furnace tube is 10°, between 90-180°, the circumferential angle α is 5°, between 180-270°, the circumferential angle α is 10°, and between 270-360°, the circumferential angle α is 5°.

[0019] According to some preferred embodiments of the present invention, the distance DH between adjacent flow-around structure layers is 1-2000mm, which can be a fixed value, that is, the distance between every two adjacent flow-around structure layers is equal, or it can be a variable value, that is, the distances between different adjacent flow-around structure layers are not equal, such as 5mm between the first and second layers, 5mm between the second and third layers, 10mm between the third and fourth layers, and 15mm between the fourth and fifth layers.

[0020] According to some preferred embodiments of the present invention, the flow-around structures between adjacent flow-around structure layers have a misalignment with a rotation angle β of 0-120°.

[0021] For example, the first flow-around structure of the first layer is set at 0°, and the first flow-around structure of the second layer is set at 5°, and the first flow-around structure of each subsequent layer is rotated 5° clockwise relative to the previous layer.

[0022] According to some preferred embodiments of the present invention, the high-temperature radiation furnace tube for enhanced heat transfer comprises the thick tube and the flow-around terminal, wherein the flow-around terminal may be one or more, and the flow-around structures in the flow-around terminal may be the same or different.

[0023] For example, in the application of iron ore reduction furnace tubes, the high-temperature radiation furnace tube is 12m long. From bottom to top, 0-1.5m is a thick tube with Ra of 12.5µm, 1.5-6m is a spherical flow terminal, 6-10m is a raindrop-shaped flow terminal, and 10-12m is a thick tube with Ra12.5µm.

[0024] More preferably, the Ra of the thick tube is 12.5µm, and the flow-around structure of the flow-around terminal is in a strip shape.

[0025] According to some preferred embodiments of the present invention, the material of the furnace tube is one or more of HP40NbMa (ZG45Ni5Cr25NbM) alloy, 35Cr45NiMa (ZG50Ni45Cr35NbM), 28Cr48Ni5W (ZG50Ni48Cr28W5) alloy and aluminum-added high-temperature alloy; wherein the HP40NbMa alloy includes 0.38-0.45wt% of C element, 0.5-1.5wt% of Mn element , 0.5-1.5wt% Si element, 34-37wt% Ni element, 24-27wt% Cr element, 0.5-1.5wt% Nb element, 0-0.5wt% Ti element, 0-0.5wt% Zr element and the balance Fe element; the 35Cr45NiMa alloy includes 0.4-0.6wt% C element, 1-2wt% Mn element, 1-2wt% Si element, 43-47wt% Ni element, 33 -37wt% Cr element, 0.7-1.5wt% Nb element, 0-0.5wt% Ti element, 0-0.5wt% Zr element and the balance Fe element; the 28Cr48Ni5W alloy includes 0.4-0.6wt% C element, 0-1.5wt% Mn element, 0-1.5wt% Si element, 47-50wt% Ni element, 27-30wt% Cr element, 0-2wt% Nb element, 4-6wt% t% of W element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; the aluminum-added high-temperature alloy includes 0.05-0.6wt% of C element, 0.5-2wt% of Mn element, 0.5-2wt% of Si element, 20-55wt% of Ni element, 15-40wt% of Cr element, 0-2wt% of Nb element, 4-5wt% of W element, 2-8wt% of Al element and the balance of Fe element.

[0026] According to some preferred embodiments of the present invention, the high-temperature radiation furnace tube comprises a plurality of tube sections, each tube section has a length of 3-7 m, an outer diameter of less than 400 mm, and a wall thickness of 5-35 mm.

[0027] According to the above preferred embodiments of the present invention, the high-temperature radiation furnace tube can achieve different application requirements through the combination of tube sections with different numbers and / or inner surface structures.

[0028] More preferably, the pipe sections are securely connected by welding.

[0029] The present invention further provides a method for preparing the above-mentioned high-temperature radiation furnace tube with enhanced heat transfer, which comprises: (1) roughening the inner surface of the high-temperature radiation furnace tube by shot peening, rolling or machining so that the surface roughness parameter Ra is 3.2-40.5 µm, thereby obtaining the rough tube; (2) Laser cladding and plasma cladding are performed on the thick tube to form the flow-around structure and obtain the flow-around terminal.

[0030] According to some preferred embodiments of the present invention, when the material of the furnace tube is HP40NbMa alloy, the surfacing powder contains: 0.38-0.45wt% of C element, 0.5-3wt% of Mn element, 0.5-3wt% of Si element, 34-37wt% of Ni element, 24-27wt% of Cr element, 0.5-1.5wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; when the material of the furnace tube is 35Cr45NiMa alloy, the surfacing powder contains: 0.4-0.6wt% of C element, 1-3wt% of Mn element, 1-3wt% of Si element, 43-47wt% of Ni element, 33-37wt% of Cr element, 0.7-1.5wt% of Nb element, 0-0.5wt% of Ti element , 0-0.5wt% of Zr element and the balance of Fe element; when the material of the furnace tube is 28Cr48Ni5W alloy, the surfacing powder contains 0.4-0.6wt% of C element, 0-3wt% of Mn element, 0-3wt% of Si element, 47-50wt% of Ni element, 27-30wt% of Cr element, 0-2wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; when the material of the furnace tube is aluminum-added high-temperature alloy, the surfacing powder contains 0.05-0.6wt% of C element, 0.5-3wt% of Mn element, 0.5-3wt% of Si element, 30-60wt% of Ni element, 20-40wt% of Cr element, 0-2wt% of Nb element, 2-8wt% of Al element and the balance of Fe element.

[0031] In a preferred embodiment of the present invention, aluminum is added to the material composition of the high-temperature radiation furnace tube, which can change the formation mechanism of the oxide film under high-temperature thermal fatigue of the material, from an oxide scale with chromium oxide as the main component to an oxide scale with aluminum oxide as the main component, thereby improving the thermal erosion resistance of the flow-around structure.

[0032] The high-temperature radiation furnace tube with enhanced heat transfer obtained by the invention can be applied to a hydrogen production conversion furnace, an ethylene cracking furnace or an iron ore reduction furnace.

[0033] The present invention has the following beneficial effects: (1) The present invention can increase the contact area between the furnace tube and the medium and enhance the flow effect by combining the roughness grooves on the inner surface and the protrusions of the flow-around structure, thereby obtaining a more uniform temperature field in the furnace tube, effectively controlling the pressure drop at the furnace tube mouth, and improving the heat conduction efficiency of the furnace tube; (2) The roughness of the grooves and the protrusions of the flow structure in the present invention are both in micron size, and the flow effect is positively correlated with the speed of the gas medium passing through; in the application of hydrogen production converters and iron ore reduction furnace tubes, the flow effect can significantly change the temperature field change in the 0-2mm space near the inner wall of the furnace tube.

[0034] (3) The present invention does not need to change the minimum dense layer thickness of the existing furnace tube, the external dimensions of the furnace tube, does not need to process the internal shape of the furnace tube, does not affect the catalyst loading, has a wider range of applications, is more flexible and convenient to process and use, and has lower furnace tube maintenance costs; (4) The thick tube and the flow-through terminal in the present invention can be flexibly matched in different types and distributions according to production needs, with a wider range of applications and greater practicality; (5) The present invention can achieve the same or higher production efficiency at a relatively low temperature, reduce production energy consumption, significantly extend the furnace tube decoking cycle, and increase annual output value; (6) The present invention can increase the effective reaction area of ​​the furnace tube, convert the traditional low-temperature zone into a medium-high temperature zone, and improve the production capacity of the furnace tube; (7) Under the same production efficiency, the temperature of the furnace tube of the present invention is more than 20°C lower than that of the traditional high-temperature alloy radiation furnace tube, which can significantly extend the life of the furnace tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of the test device used in the embodiment.

[0036] Figure 2 Schematic diagram of the catalyst loading method in the embodiment.

[0037] Figure 3 Schematic diagram of the spherical flow structure in the embodiment, wherein (a) is a top view and (b) is a side view.

[0038] Figure 4 Schematic diagram of the raindrop flow structure in the embodiment, wherein (a) is a top view and (b) is a side view.

[0039] Figure 5 Schematic diagram of the spherical strip flow structure in the embodiment, wherein (a) is a top view and (b) is a side view.

[0040] Figure 6 It is a perspective schematic diagram of the three-dimensional structure of the spherical flow terminal in the embodiment.

[0041] Figure 7It is a statistical chart of the test results of Examples 1-15.

[0042] Figure 8 Statistical graph of test results of Examples 14-20. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be further described below in conjunction with the embodiments and drawings of the present invention. The embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0044] The furnace tubes used in the following embodiments are obtained by centrifugal casting. The materials are HP40NbMa alloy (i.e. ZG45Ni5Cr25NbM alloy, hereinafter referred to as alloy 1), 35Cr45NiMa alloy (i.e. ZG50Ni45Cr35NbM alloy, hereinafter referred to as alloy 2), 28Cr48Ni5W alloy (i.e. ZG50Ni48Cr28W5 alloy, hereinafter referred to as alloy 3) and aluminum-added high-temperature alloy (hereinafter referred to as alloy 4). The main element compositions are shown in Table 1 below. The element compositions of the corresponding surfacing powders used are shown in Table 2 below. Figure 1 The test device shown was used for comparative testing.

[0045] Table 1 Furnace tube material type and composition

[0046] Table 2 Composition of cladding powder

[0047] In the test device, the furnace tubes 1 and 2 correspond to two pipe sections of the high-temperature radiation furnace tube. The inlet of the furnace tube 1 is connected to the blower 4 through the inlet flange 3, the outlet of the furnace tube 1 is connected to the inlet of the furnace tube 2 through the elbow 5, and the outlet of the furnace tube 2 is connected to the outside of the furnace through the outlet flange 6. The furnace tubes 1, 2 and the elbow 5 are placed in a box-type heating furnace 7 as a whole. The internal temperature of the box-type heating furnace 7 is stably controlled to 800°C ± 3°C, and uniform heating and consistent temperature are ensured; during the test, the blower 4 continuously delivers a constant flow of air to the inside of the furnace tubes 1 and 2, the air flow rate is set to 2-12m / s, and the air flow is ensured to be stable. The temperature of the inlet air is controlled to 20°C ± 2°C, and the air temperature output by the blower is ensured to be stable; Comparative testing included: (1) Temperature monitoring: In the length direction of the furnace tube, 5 thermocouples were welded at 0m, 1m, 2m, 3m and 4m respectively to monitor the temperature change on the surface of the furnace tube in real time. The test records show that the temperature measured by all thermocouples in the test was 800°C ±3°C, indicating that the surface temperature of the furnace tube was stable; (2) Stress test: Pressure sensors are installed at the inlet and outlet of the furnace tube, and the pressure drop of the gas when it flows through the furnace tube is calculated by the pressure sensors; (3) Outlet temperature measurement: A temperature sensor is installed at the furnace tube outlet to measure the air temperature after flowing through the furnace tube. After the furnace tube surface temperature and the outlet gas temperature reach a stable state, the air outlet temperature is recorded.

[0048] The calculation formula of heat exchange power Q (kW) used in the embodiment is:

[0049] in, Indicates the mass flow rate of air (kg / s), that is, the mass of air passing through the furnace tube per second. The calculation formula is:

[0050] Where ρ represents the air density (kg / m 3 ), under test conditions, 1.2 kg / m 3 ; v represents the air velocity (m / s), which is 2-12 m / s under test conditions, and A represents the inner cross-sectional area of ​​the furnace tube (m 2 ); Indicates the specific heat capacity of air at constant pressure (kJ / (kg\K)). Under test conditions, the value is 1.005 kJ / (kg\K) represents the outlet temperature (K); represents the inlet temperature (K), which is 293K (corresponding to 20℃) under test conditions.

[0051] The total heat exchange efficiency Z is calculated as follows: Z=Z 粗糙度 +Z 绕流端子 ==α·Ra β (1-η ρ )+ η0·η d ·η h ·η ρ Among them, Z 粗糙度 represents the effect of roughness on heat exchange efficiency, Z 绕流端子represents the effect of the flow-around structure terminal on the heat exchange efficiency, α and β are constants obtained through experimental data or numerical simulation, represents the effect of roughness on the heat exchange efficiency, Ra represents the roughness of the inner surface, η0 represents the basic heat exchange efficiency, that is, the heat exchange efficiency without the flow-around structure terminal, η d Indicates the contribution of terminal diameter to heat exchange efficiency, η h Indicates the contribution of terminal height to heat exchange efficiency, η ρ Indicates the contribution of terminal density to heat exchange efficiency.

[0052] Examples 1-15 The following processing was performed on several furnace tubes with a length of 3 m, an outer diameter of 121 mm, an inner diameter of 98 mm, and a material of HP40NbMa: (1) performing inner surface roughness treatment on the furnace tube, including: performing shot peening treatment on the inner surface of the furnace tube to achieve the surface roughness as shown in Table 3; (2) Selecting cladding powder corresponding to the furnace tube material to perform cladding treatment on the furnace tube with different lengths and shapes of flow structures after inner surface roughness treatment (as shown in Table 3) to obtain the processed furnace tube; (3) The two processed furnace tubes are combined as two pipe sections of a high-temperature radiation furnace tube to obtain a high-temperature radiation furnace tube with enhanced heat transfer.

[0053] Fill the high temperature radiation furnace tube with enhanced heat transfer with a columnar catalyst with an outer diameter of 12-15 mm, such as the attached Figure 2 As shown in Table 3 and Appendix, the pressure drop and heat exchange power were measured at a wind speed of 2.4 m / s. Figure 7 The test results are shown in Table 3. The pressure drop of Example 1 is used as a reference value, and the pressure drop of other Examples 2-13 is subtracted from the reference value of the pressure drop of Example 1. The obtained changes are recorded in Table 3. A positive change indicates an increase in pressure drop.

[0054] Table 3 Test results of Examples 1-15

[0055]

[0056] As can be seen from Table 3, under the same other conditions, increasing the surface roughness and the inner surface flow structure does not affect the furnace tube pressure drop, but significantly changes the furnace tube heat exchange efficiency; in the hydrogen production conversion tube, the pressure drop is mainly caused by the filling of the catalyst, and the size of the pressure drop mainly depends on the shape and size of the catalyst; using larger shot peening particles (diameter> 1mm) and higher injection pressure, the roughness gradually increases from Ra3.2μm to Ra20.1μm, and using ultra-large particle shot peening (Example 4), the roughness can reach Ra36.9μm, causing obvious pits and microcracks on the surface, resulting in industrial use risks. Therefore, Ra3.2-12.5μm is the preferred range.

[0057] By comparing the cases without terminals (Examples 1-4) and with terminals (Examples 5-13), it can be found that the optimization effect of the terminals is more obvious than that of the roughness, among which the strip effect is better than the spherical and raindrop terminal effects.

[0058] By comparing Examples 5, 6, and 7, it can be seen that, under the condition of a given roughness, changing the distribution density of the spherical terminals (ie, reducing a) and generating rotation between the terminals (ie, β is not equal to 0) can change the overall heat exchange efficiency.

[0059] By comparing Examples 8, 9, and 10, it can be seen that changing the distribution density of the raindrop terminals (ie, reducing a) and the interlayer distance (ie, DH) can change the overall heat exchange efficiency.

[0060] Compared with Examples 11, 12, and 13, it can be seen that changing the distribution density of the strip terminals (ie, changing a) and generating rotation between the terminals (ie, β is not equal to 0) can change the overall heat exchange efficiency.

[0061] By comparing Examples 13, 14, and 15, it can be seen that when the distribution density of the terminals is increased (a and DH are reduced) in a certain area (Example 13 is the furnace tube 1 area, and Example 14 is the furnace tube 2 area), and the corresponding remaining area adopts thick tubes, the average value of the heat exchange rate obtained is the same as that of Example 13. This shows that the heat input inside the furnace tube can be dynamically adjusted by combining the flow-around terminals and the thick tubes, providing an adjustable mechanism and method for the actual use of furnace tubes on site.

[0062] Examples 16-22 According to the same processing process as in Example 1-15, a plurality of furnace tubes with a length of 3 m, an outer diameter of 60 mm, and an inner diameter of 50 mm were processed, and two furnace tubes with completely the same structure after processing were combined as two pipe sections of the high-temperature radiation furnace tube to obtain a high-temperature radiation furnace tube with enhanced heat transfer. The furnace tube was not filled with catalyst, and its outlet temperature, outlet pressure drop, and total heat exchange efficiency were measured respectively. The results are shown in Tables 4 and 5 and attached. Figure 8 shown.

[0063] Table 4 Test results of Examples 16-22

[0064] Through Table 4 and Figure 8 It can be seen that without the effect of the flow-around terminal (Examples 16-18), as the inner surface roughness increases, the heat exchange efficiency increases accordingly, and after adding the terminal (Examples 19-22), the outlet temperature increases relative to the thick tube, among which the heat exchange efficiency of the raindrop-shaped flow-around terminal is better than that of the spherical flow-around terminal. In Examples 19 and 20, the outlet temperature can be significantly increased by increasing the density of the spherical flow-around structure (i.e., reducing a and DH). In Examples 21 and 22, the outlet temperature can be significantly increased by increasing the density of the raindrop flow-around structure (i.e., reducing a and DH).

[0065] It should be noted that the above is only a preferred embodiment of the present invention, which should not limit the protection scope of the technical solution of the present invention. Any modification of the technical solution recorded in the above embodiments and equivalent replacement of technical features by ordinary technicians in the field within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A high temperature radiation furnace tube for enhanced heat transfer, characterized in that: It includes: inner surface A high-temperature radiation furnace tube that has been subjected to roughness treatment, i.e., a thick tube, and / or a high-temperature radiation furnace tube whose inner surface has been subjected to roughness treatment and flow-around structure surfacing treatment in sequence, i.e., a flow-around terminal, wherein the inner surface roughness parameter Ra of the thick tube is 3.2–40.5µm, and the shape of the flow-around structure is one or more of a spherical shape, a raindrop shape, and a strip shape.

2. The high temperature radiation furnace tube with enhanced heat transfer according to claim 1, characterized in that: in, The flow-around structure is spherical, the height f of the spherical flow-around structure protruding on the inner surface of the furnace tube is 100-2000µm, and the diameter e projected on the inner surface of the furnace tube is 1000µm-10mm; or, the flow-around structure is raindrop-shaped, the height d of the raindrop-shaped flow-around structure protruding on the inner surface of the furnace tube is 100-2000µm, and the width a projected on the inner surface of the furnace tube is 1000µm-10mm, and it has a front spherical head and a rear conical tail, and the radius b of the head and the length c of the tail are both 500µm-50mm; or, the flow-around structure is strip-shaped, the total length i of the strip-shaped flow-around structure is 1-500 mm, and the width h projected on the inner surface of the furnace tube is 1000µm-30 mm, It comprises a spherical head and tail and a cylindrical middle part, and the height j of the head and tail protruding from the inner surface of the furnace tube and the height k of the middle part protruding from the inner surface of the furnace tube are both 100-2000 μm.

3. The high temperature radiation furnace tube with enhanced heat transfer according to claim 2, characterized in that: in, The flow-around structure is spherical, f is 800 µm, and e is 1000 µm; or, the flow-around structure is raindrop-shaped, and a is 3000 µm.

4. The high temperature radiation furnace tube with enhanced heat transfer according to claim 1, characterized in that: The flow-by-flow terminal includes one or more flow-by-flow structure layers, each flow-by-flow structure layer includes a plurality of evenly distributed flow-by-flow structures, and a circumferential angle α between the center position of each flow-by-flow structure and the cross-section of the high-temperature radiation furnace tube is 0-120°; or, any of the flow-by-flow structure layers contains a plurality of unevenly distributed flow-by-flow structures.

5. The high temperature radiation furnace tube with enhanced heat transfer according to claim 4, characterized in that: The distance DH between adjacent flow-around structure layers is 1-2000 mm; and / or the flow-around structures between adjacent flow-around structure layers have a misalignment with a rotation angle β of 0-120°.

6. The high temperature radiation furnace tube with enhanced heat transfer according to claim 1, characterized in that: It includes the thick tube and the flow-around terminal, the Ra of the thick tube is 12.5µm, and the flow-around structure of the flow-around terminal is strip-shaped.

7. The high temperature radiation furnace tube with enhanced heat transfer according to any one of claims 1 to 6, characterized in that: The material of the high temperature radiation furnace tube is one or more of HP40NbMa alloy, 35Cr45NiMa alloy, 28Cr48Ni5W alloy and aluminum high temperature alloy; wherein the HP40NbMa alloy includes 0.38-0.45wt% of C element, 0.5-1.5wt% of Mn element, 0.5-1.5wt% of Si element, 34-37wt% of Ni element, 24-27wt% of Cr element, 0.5-1.5wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; the 35Cr45NiMa alloy includes 0.4-0.6wt% of C element, 1-2wt% of Mn element, 1-2wt% of Si element, 43-47wt% of Ni element, 33-37wt% of Cr element, 0.7-1.5wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; the 28Cr48Ni5W alloy includes 0.4-0.6wt% of C element, 0-1.5wt% of Mn element, 0-1.5wt% of Si element, 47-50wt% of Ni element, 27-30wt% of Cr element, 0-2wt% of Nb element, 4-6wt% of W element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; the aluminum-added high-temperature alloy includes 0.05-0.6wt% of C element, 0.5-2wt% of Mn element, 0.5-2wt% of Si element, 20-55wt% of Ni element, 15-40wt% of Cr element, 0-2wt% of Nb element, 4-5wt% of W element, 2-8wt% of Al element and the balance of Fe element.

8. The method for preparing a high-temperature radiation furnace tube with enhanced heat transfer according to any one of claims 1 to 7, characterized in that: It includes: (1) roughening the inner surface of the high-temperature radiation furnace tube by shot peening, rolling or machining so that the surface roughness parameter Ra is 3.2-40.5 µm, thereby obtaining the rough tube; (2) Laser cladding and plasma cladding are performed on the thick tube to form the flow-around structure and obtain the flow-around terminal.

9. The preparation method according to claim 8, when the material of the high-temperature radiation furnace tube is HP40NbMa alloy, the surfacing welding powder contains: 0.38-0.45wt% of C element, 0.5-3wt% of Mn element, 0.5-3wt% of Si element, 34-37wt% of Ni element, 24-27wt% of Cr element, 0.5-1.5wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; when the material of the high-temperature radiation furnace tube is 35Cr45NiMa alloy, the surfacing welding powder contains: 0.4-0.6wt% of C element, 1-3wt% of Mn element, 1-3wt% of Si element, 43-47wt% of Ni element, 33-37wt% of Cr element, 0.7-1.5wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element. When the material of the high-temperature radiation furnace tube is 28Cr48Ni5W alloy, the surfacing powder contains 0.4-0.6wt% of C element, 0-3wt% of Mn element, 0-3wt% of Si element, 47-50wt% of Ni element, 27-30wt% of Cr element, 0-2wt% of Nb element, 0-0.5wt% of Ti element, 0-0.5wt% of Zr element and the balance of Fe element; when the material of the high-temperature radiation furnace tube is aluminum-added high-temperature alloy, the surfacing powder contains 0.05-0.6wt% of C element, 0.5-3wt% of Mn element, 0.5-3wt% of Si element, 30-60wt% of Ni element, 20-40wt% of Cr element, 0-2wt% of Nb element, 2-8wt% of Al element and the balance of Fe element.

10. Use of the high-temperature radiation furnace tube with enhanced heat transfer according to any one of claims 1 to 7 or the high-temperature radiation furnace tube with enhanced heat transfer prepared by the preparation method according to claim 8 or 9 in a hydrogen production converter, an ethylene cracking furnace or an iron ore reduction furnace.

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