High-efficiency radiation heat exchange tube and radiation tube heat exchanger

Abstract

This application relates to the field of heat exchange equipment, and in particular to a high-efficiency radiant heat exchange tube and a radiant tube heat exchanger. The radiant heat exchange tube includes a tube body and fins. The tube body is a circular tube with a closed end and an open end, respectively, and the closed end is machined into a hemispherical structure. The fins include multiple sets of inner fins integrally formed on the inner wall of the tube body and multiple sets of first outer fins integrally formed on the outer wall of the tube body. The inner fins and first outer fins are arranged in a spiral pattern along the axial direction of the tube body, thereby improving the heat exchange efficiency and increasing the utilization rate of waste heat from flue gas.

Description

Technical Field

[0001] This application relates to the field of heat exchange equipment, and in particular to a high-efficiency radiant heat exchange tube and radiant tube heat exchanger. Background Technology

[0002] Currently, in processes such as metal heat treatment and industrial drying, with the continuous improvement of product quality and performance requirements, indirect heating technology using radiant tubes is being increasingly widely applied in practical fields such as industrial furnaces. The use of gas-fired radiant tubes for heat treatment is quite common in the market. For energy conservation and emission reduction considerations, most radiant tube heat exchangers utilize the flue gas generated after combustion to preheat the combustion air.

[0003] Existing radiant tubes consist of a tube body and several fins mounted on the outer wall of the tube body. The fins are integrally formed in a plate shape on the tube wall, with the plate surface of the fin perpendicular to the tangent at the point where the fin is located on the tube wall. After the flue gas passes through the tube body, the heat of the flue gas is radiated to the combustion air through the tube body and fins.

[0004] The existing technical solutions mentioned above have the following drawbacks: the heat exchange area of ​​the heat exchange structure is limited, which leads to limited heat exchange efficiency and reduces the utilization rate of waste heat from flue gas. Summary of the Invention

[0005] In order to improve heat exchange efficiency and increase the utilization rate of waste heat from flue gas, this application provides a high-efficiency radiant heat exchange tube and a radiant tube heat exchanger.

[0006] The above-mentioned technical objective of this application is achieved through the following technical solution:

[0007] A high-efficiency radiative heat exchange tube includes a radiative heat exchange tube comprising a tube body and fins. The tube body is a circular tube with a closed end and an open end at each end, and the closed end is processed into a hemispherical structure.

[0008] The fins include multiple sets of inner fins integrally formed on the inner wall of the tube and multiple sets of first outer fins integrally formed on the outer wall of the tube, wherein the inner fins and the first outer fins are arranged in a spiral pattern at intervals along the axial direction of the tube.

[0009] By adopting the above technical solution, the closed end of the tube is designed as a hemispherical structure, and spirally spaced inner fins and a first outer fin are arranged on the inner and outer walls of the tube, significantly increasing the heat exchange area between the flue gas and the combustion air. The spiral fins extend the airflow path, enhance the turbulence effect, and make heat transfer more complete, thereby overcoming the defect of limited heat exchange area and improving heat exchange efficiency.

[0010] Optionally, the number of sets of inner fins and first outer fins is equal, and the end faces of adjacent sets of inner fins or first outer fins are arranged opposite each other or staggered.

[0011] By adopting the above technical solution, the path of gas flowing through the fins is further extended, and the probability of collision between gas and the end face of the fins is increased, avoiding the phenomenon of airflow short circuit, making heat exchange more uniform and comprehensive, and further improving the utilization rate of flue gas waste heat.

[0012] Optionally, the outer wall of the closed end of the tube is machined into a spherical convex surface, and multiple second outer fins are radially distributed on the spherical convex surface.

[0013] By adopting the above technical solution, the radial second outer fins expand the heat exchange area at the end of the tube body, and in particular optimize the heat radiation effect of the flue gas when it is diverted at the closed end of the tube body, so that the heat of the high-temperature flue gas is more fully absorbed by the combustion air and the waste heat loss is reduced.

[0014] A radiant tube heat exchanger includes a connecting pipe connected to the open end of the tube body, an air guide pipe passing through the tube body and the connecting pipe, an installation pipe sleeved outside the connecting pipe, a flue pipe connected to the installation pipe, and a secondary heat exchanger disposed in the flue pipe. The secondary heat exchanger is used for secondary recovery of waste heat from the flue gas. The outer wall of the air guide pipe and the inner wall of the tube body form an air flow passage.

[0015] By adopting the above technical solution, a multi-stage heat exchange system is formed. The flue gas first releases heat through a primary heat exchanger (radiant heat exchange tube), and then recovers waste heat through a secondary heat exchanger, realizing the cascade utilization of flue gas heat energy and significantly improving the overall heat exchange efficiency.

[0016] Optionally, the pipe body is provided with a flue gas return hole that connects the inside and outside of it;

[0017] An exhaust pipe head is provided on the air guide pipe, and the end of the exhaust pipe head away from the air guide pipe is machined into a constricted shape.

[0018] By adopting the above technical solution, the flue gas can enter the air guide pipe through the flue gas return hole and mix with the air. This allows for direct heat exchange with the air. At the same time, the mixed gas can increase its flow rate when passing through the exhaust pipe head with a smaller port diameter, thereby ensuring that the flue gas can be returned to the industrial furnace for combustion. This allows for the reuse of the flue gas, improves heat exchange efficiency, and reduces the generation of nitrogen oxides.

[0019] Optionally, the flue gas return hole is opened at an angle from the closed end of the pipe body to the open end of the pipe body;

[0020] The flue gas return hole is located between the closed end of the pipe body and the end of the air guide pipe near the closed end of the pipe body, and the opening direction of the flue gas return hole is towards the end of the air guide pipe.

[0021] By adopting the above technical solution, it is further ensured that the recirculated flue gas can quickly enter the industrial furnace to complete the recirculation and combustion.

[0022] Optionally, a transition tube is fixedly connected to the end of the air guide tube away from the exhaust pipe head, and an extension tube is fixedly connected to the end of the transition tube away from the air guide tube. The diameter of the extension tube is smaller than that of the extension tube and the air guide tube.

[0023] The transition pipe is equipped with a return pipe that connects the interior of the transition pipe with the flue gas return hole.

[0024] By adopting the above technical solution, when air enters the transition pipe located between the extension pipe and the air guide pipe from the extension pipe, the continuously entering air can be compressed, thereby increasing the flow rate in the transition pipe, further improving the smoothness of flue gas recirculation into the air guide pipe, and improving the efficiency of flue gas entering the air guide pipe to mix with air for heat exchange.

[0025] Optionally, the secondary heat exchanger includes a first secondary heat exchanger, which includes an inner tube, a secondary radiative heat exchanger sleeved outside the inner tube and spaced apart from the outer wall of the inner tube, and a first fixed tube and a second fixed tube connecting the two. An indirect heat exchange channel between the inner tube and the secondary radiative heat exchanger is formed between the combustion air and the flue gas.

[0026] By adopting the above technical solution, the first and second stage heat exchangers adopt a nested structure of inner tube and second stage radiant heat exchanger to form a compact indirect heat exchange channel, which enables the flue gas and combustion air to fully exchange heat in countercurrent flow during the second stage of heat exchange, further reducing the exhaust gas temperature and improving the waste heat recovery rate. At the same time, the compact structure facilitates installation and maintenance.

[0027] Optionally, the secondary heat exchanger includes a second secondary heat exchanger, which includes a spiral fixed plate, multiple air inlet pipes passing through and fixed to the fixed plate, heat exchange fins fixed to the outer wall of the air inlet pipes, a third fixed pipe and a fourth fixed pipe fixed to both ends of the multiple air inlet pipes, and a first connecting flange and a second connecting flange fixed to the third fixed pipe and the fourth fixed pipe.

[0028] By adopting the above technical solution, the spiral-shaped fixed plate can delay and guide the flue gas, thereby improving the heat exchange efficiency. The third and fourth fixed tubes have the same structure, and the end of the fourth fixed tube away from the inlet pipe can be inserted into the second connecting pipe head.

[0029] Optionally, an aluminum silicate insulation layer is provided between the installation pipe and the connecting pipe, as well as on the inner wall of the exhaust pipe.

[0030] By adopting the above technical solutions, the aluminum silicate insulation layer can effectively reduce heat loss during the heat exchange process, ensure that the waste heat of the flue gas is used to preheat the combustion air to the maximum extent, and improve the energy efficiency and stability of the system.

[0031] In summary, this application has the following technical effects:

[0032] 1. By arranging the inner fins and the first outer fins in a spiral pattern along the tube axis, the heat exchange area between the flue gas and the combustion air is significantly increased. The spiral fins extend the airflow path, enhance the turbulence effect, and make heat transfer more efficient, thereby overcoming the limitation of limited heat exchange area in the prior art and improving heat exchange efficiency;

[0033] 2. By setting radial second outer fins, the heat exchange area at the end of the tube is expanded, and the heat radiation effect of the flue gas when it is diverted at the closed end of the tube is optimized, so that the heat of the high temperature flue gas is more fully absorbed by the combustion air and the waste heat loss is reduced.

[0034] 3. A multi-stage heat exchange system is formed by setting up radiant heat exchange tubes, connecting pipes, air guide pipes, installation pipes, flue gas exhaust pipes, and first and second stage heat exchangers. The flue gas first releases heat through the radiant heat exchange tubes, and then recovers waste heat deeply through the first and second stage heat exchangers, realizing the cascade utilization of flue gas heat energy and significantly improving the overall heat exchange efficiency. Attached Figure Description

[0035] Figure 1 This is a structural diagram of the radiant heat exchange tube in Example 1;

[0036] Figure 2 This is a structural diagram of the fins;

[0037] Figure 3 This is a structural diagram of the radiant tube heat exchanger in Example 3;

[0038] Figure 4 This is a cross-sectional structural diagram of a radiant tube heat exchanger;

[0039] Figure 5 This is a cross-sectional structural diagram of a radiant tube heat exchanger;

[0040] Figure 6 This is a cross-sectional view of the first and second stage heat exchangers;

[0041] Figure 7 This is a cross-sectional view of the air guide tube in Example 5;

[0042] Figure 8 This is a cross-sectional view of the second and second stage heat exchangers.

[0043] Explanation of reference numerals in the attached drawings: 1. Radiant heat exchange tube; 11. Tube body; 12. Fin; 121. Inner fin; 122. First outer fin; 123. Second outer fin; 13. Connecting assembly; 2. Connecting pipe; 21. First connecting pipe head; 22. Second connecting pipe head; 23. Sealing plate; 24. Connecting rod; 3. Air guide pipe; 31. Exhaust pipe head; 32. First retaining ring; 33. Transition pipe; 34. Second retaining ring; 35. Extension pipe; 36. Return pipe; 4. Mounting pipe; 41. Cover 42. First mounting pipe head; 43. Second mounting pipe head; 5. Exhaust pipe; 51. Exhaust pipe head; 6. First and second stage heat exchangers; 61. Inner pipe; 62. Connecting rod; 63. Second stage radiant heat exchanger; 64. First fixed pipe; 65. Second fixed pipe; 7. Second and second stage heat exchangers; 71. First connecting flange; 72. Third fixed pipe; 73. Connecting plate; 74. Inlet pipe; 75. Fixed plate; 76. Heat exchange fins; 77. Second connecting flange; 78. Fourth fixed pipe. Detailed Implementation

[0044] The present application will be further described in detail below with reference to the accompanying drawings.

[0045] Example 1

[0046] This application discloses a high-efficiency radiative heat exchange tube, combined with... Figure 1 and Figure 2 The radiant heat exchange tube 1 includes a tube body 11 with a closed end and an open end, and fins 12 integrally formed on the tube wall of the tube body 11. The radiant heat exchange tube 1 is cast from high-strength steel. The casting is treated with stainless steel shot blasting, which makes it less prone to rust and rust spots during long-term storage. The end faces of the casting are chamfered to facilitate gas flow.

[0047] The pipe body 11 is a circular pipe. The closed end of the pipe body 11 is machined into a hemispherical shape, and the inner wall of the closed end is machined into a spherical concave surface. The spherical concave surface is conducive to redirecting the flue gas during the emission process, thereby facilitating the smooth discharge of the flue gas.

[0048] The fins 12 include inner fins 121 and first outer fins 122 integrally formed on the inner and outer walls of the tube body 11, respectively. Multiple sets of inner fins 121 and first outer fins 122 are formed. In this embodiment, each set of inner fins 121 and each set of first outer fins 122 is equally spaced with 42 pieces. Adjacent sets of inner fins 121 and adjacent sets of first outer fins 122 are arranged at intervals. The spacing between adjacent sets of inner fins 121 is the same as the spacing between adjacent sets of first outer fins 122. Both the inner fins 121 and the first outer fins 122 are spirally arranged around the axis of the tube body 11. The end faces of adjacent sets of inner fins 121 or first outer fins 122 are arranged opposite each other. This significantly increases the surface area of ​​gas contacting the fins 12 during gas flow within a limited space, thereby significantly improving heat exchange efficiency and effectively increasing the utilization rate of waste heat from flue gas.

[0049] The outer wall of the closed end of the tube body 11 is processed into a spherical convex surface. Multiple second outer fins 123 are integrally formed on the spherical convex surface. The multiple second outer fins 123 are arranged radially from the center point of the spherical convex surface to the edge of the spherical convex surface.

[0050] Example 2

[0051] The difference between this embodiment and Embodiment 1 is that:

[0052] The end faces of two adjacent sets of inner fins 121 are staggered, and the end faces of two adjacent sets of first outer fins 122 are also staggered. This not only enhances the turbulence performance during air or flue gas flow, but also extends the flow path and increases the probability of gas contact with the end faces of fins 12, thereby further improving heat exchange efficiency.

[0053] Example 3

[0054] This application discloses a radiant tube heat exchanger equipped with high-efficiency radiant heat exchange tubes, combined with... Figures 3-5 The radiant tube heat exchanger includes a radiant heat exchange tube 1, a connecting pipe 2 integrally formed with the open end of the tube body 11 and arranged coaxially, an air guide pipe 3 passing through the radiant heat exchange tube 1 and the connecting pipe 2 and coaxially arranged, an installation pipe 4 coaxially sleeved on the outside of the end of the connecting pipe 2 away from the radiant heat exchange tube 1, a flue pipe 5 with one end fixed to and connected to the outer wall of the installation pipe 4, and a secondary heat exchanger coaxially arranged in the flue pipe 5 and with one end fixed to and connected to the connecting pipe 2. In this embodiment, the secondary heat exchanger is a first secondary heat exchanger 6.

[0055] Combination Figure 4 and Figure 5The inner and outer diameters of the connecting pipe 2 are the same as those of the pipe body 11. A first connecting pipe head 21 is integrally formed on the outer wall of the connecting pipe 2 near the opening end of the pipe body 11, and a second connecting pipe head 22 is integrally formed on the outer wall of the connecting pipe 2 away from the pipe body 11. The second connecting pipe head 22 and the first connecting pipe head 21 are arranged at intervals, and the openings of the first connecting pipe head 21 and the second connecting pipe head 22 are both perpendicular to the axis of the connecting pipe 2. A sealing plate 23 is fixedly installed inside the connecting pipe 2 at the end away from the pipe body 11. The sealing plate 23 is located on the side of the second connecting pipe head 22 away from the first connecting pipe head 21, and the sealing plate 23 is arranged at intervals with the second connecting pipe head 22. The sealing plate 23 is a circular plate and seals the inner wall of the connecting pipe 2. In this embodiment, the radiant heat exchange tube 1 is a primary radiant heat exchanger, and the radiant heat exchange tube 1 and the connecting pipe 2 form a primary heat exchanger.

[0056] Gaps exist between the outer surface of the air guide tube 3 and the inner wall of the tube body 11, and between the outer wall of the air guide tube 3 and the inner wall of the connecting tube 2, thus forming an airflow passage between the outer wall of the air guide tube 3 and the inner walls of the tube body 11 and the connecting tube 2. The two ends of the air guide tube 3 are an open end and a closed end, respectively. The open end of the air guide tube 3 is located inside the tube body 11 and has a gap between it and the closed end of the tube body 11. The closed end of the air guide tube 3 is located between the first connecting tube head 21 and the second connecting tube head 22. An exhaust pipe head 31 is fixedly connected to the outer wall of the air guide tube 3 near the closed end. The exhaust pipe head 31 passes through the first connecting tube head 21 and is sealed to the first connecting tube head 21.

[0057] Combination Figure 4 and Figure 5 The inner diameter of the mounting pipe 4 is larger than the outer diameter of the connecting pipe 2, and there is a gap between the inner wall of the mounting pipe 4 and the outer wall of the connecting pipe 2. A cover plate 41 is fixedly connected to the end of the mounting pipe 4 away from the radiant heat exchanger tube 1 via a flange. A sealing gasket is provided on the end face of the cover plate 41 and the mounting pipe 4. In this embodiment, the sealing gasket is made of rubber fiber cotton. A first mounting pipe head 42 and a second mounting pipe head 43 are integrally formed on the outer wall of the mounting pipe 4. The pipe head orientations of both the first mounting pipe head 42 and the second mounting pipe head 43 are perpendicular to the axial direction of the mounting pipe 4. The first mounting pipe head 42 is coaxially arranged with the exhaust pipe head 31, and the outer wall of the first mounting pipe head 42 is sealed and fixedly connected to the exhaust pipe head 31. The pipe head orientation of the second mounting pipe head 43 is perpendicular to the pipe opening orientation of the first mounting pipe head 42.

[0058] Combination Figure 4 and Figure 5One end of the exhaust pipe 5 is connected to the second mounting pipe head 43 via a flange, with a sealing gasket between them. The exhaust pipe 5 and the mounting pipe 4 form a flue gas flow path. An exhaust pipe head 51 is integrally formed on the side wall of the end of the exhaust pipe 5 away from the second mounting pipe head 43. The exhaust pipe head 51 is equipped with a flange for connecting to an external exhaust pipe, thereby discharging the flue gas that has completed heat exchange and is at a lower temperature to the outside of the radiant heat exchanger.

[0059] Combination Figure 5 and Figure 6 The first and second stage heat exchangers 6 include an inner tube 61 with closed ends at both ends, two sets of connecting rods 62 fixed to the outer wall of the inner tube 61 near both ends, a second stage radiative heat exchanger 63 coaxially sleeved outside the inner tube 61 and spaced apart from the outer wall of the inner tube 61, and a first fixed tube 64 and a second fixed tube 65 coaxially fixed to both ends of the second stage radiative heat exchanger 63.

[0060] One end of the connecting rod 62 is fixed to the outer wall of the inner tube 61. Multiple connecting rods 62 are provided in each group and are evenly distributed around the axis of the inner tube 61. The other ends of the two groups of connecting rods 62 are respectively fixed to the inner walls of the first fixed tube 64 and the second fixed tube 65. The difference between the secondary radiative heat exchanger 63 and the radiative heat exchange tube 1 (the primary radiative heat exchanger) is that both ends of the secondary radiative heat exchanger 63 are open. The secondary radiative heat exchanger 63 also includes a tube body 11, inner fins 121, and a first outer fin 122. There is a gap between the first outer fin 122 of the secondary radiative heat exchanger 63 and the inner wall of the exhaust pipe 5. The first fixed tube 64 and the second fixed tube 65 are integrally formed on both ends of the tube body 11 of the secondary radiative heat exchanger 63, so that the inner tube 61 is suspended inside the secondary radiative heat exchanger 63, thereby forming an air intake passage between the inner tube 61 and the secondary radiative heat exchanger 63. The end of the first fixed pipe 64 furthest from the secondary radiant heat exchanger 63 is sealed to the second connecting pipe head 22. The diameter of the pipe body 11 of the first fixed pipe 64 furthest from the secondary radiant heat exchanger 63 is smaller than that of the pipe body 11 of the secondary radiant heat exchanger 63, thereby accelerating the airflow and allowing air to be quickly discharged into the installation pipe 4. A flange is provided on the end of the second fixed pipe 65 furthest from the secondary radiant heat exchanger 63, thereby allowing for a sealed connection with the end of the exhaust pipe 5.

[0061] High-temperature flue gas enters through the gap between the first outer fin 122 and the mounting pipe 4, where it undergoes primary heat exchange with the already preheated air. Then, the flue gas passes sequentially through the outside of the connecting pipe 2 and the gap between the exhaust pipe 5 and the secondary radiant heat exchanger 63, where it undergoes secondary heat exchange with the air newly entering the secondary radiant heat exchanger 63 in the exhaust pipe 5. This allows for a significant recovery of heat from the flue gas and reduces heat loss.

[0062] It should be noted that, since the flue gas and air are in a state of flux within the overall device, the heat exchange efficiency is limited. Even if the newly introduced air comes into contact with the high-temperature flue gas, the air cannot completely absorb the heat from the flue gas in a short period of time. Therefore, in this embodiment, the newly introduced air comes into contact with the flue gas that has already undergone one heat exchange, which can initially raise the temperature of the air. The air that has already undergone one heat exchange will come into contact with the newly generated high-temperature flue gas in the primary heat exchanger, further raising the temperature of the air. After this process, the air will absorb a significant amount of heat from the flue gas.

[0063] In this embodiment, insulation layers (not shown in the figure) are provided in the cavity between the sealing plate 23 and the cover plate 41, on the inner wall of the mounting pipe 4, and on the inner wall of the flue gas pipe 5. The insulation layers are made of aluminum silicate. The insulation layers can effectively reduce heat loss inside the radiant tube heat exchanger, thereby facilitating the preheating of flue gas.

[0064] Example 4

[0065] The difference between this embodiment and Embodiment 3 is as follows:

[0066] Several flue gas return holes (not shown in the figure) are formed on the pipe body 11 around its axis. These return holes are inclined from the closed end of the pipe body 11 towards the open end, connecting the inner and outer walls of the pipe body 11. The return holes are located between the closed end of the pipe body 11 and the open end of the air guide pipe 3, with the opening direction of the return holes facing the opening of the air guide pipe 3, allowing the returned flue gas to smoothly enter the air guide pipe 3. During flue gas emission, the flue gas enters the air guide pipe 3 through the inclined return holes and mixes with the air. This allows for direct heat exchange with the air, while the flue gas can also return to the industrial furnace for combustion, achieving reuse of the flue gas, improving heat exchange efficiency, and achieving energy conservation and environmental protection.

[0067] Reference Figure 5 The end of the exhaust pipe head 31 that is away from the air guide pipe 3 and extends out of the first mounting pipe head 42 is processed into a constricted tube shape, that is, the diameter of the exhaust pipe head 31 opening is smaller than the diameter of the end of the exhaust pipe head 31 connected to the exhaust duct 3. When the flue gas that flows back to the air guide pipe 3 through the return hole and the gas mixed with air is discharged through the end of the exhaust pipe head 31 with the smaller diameter, the gas flow speed can be increased, thereby quickly discharging the mixed gas of the return flue gas and the combustion air into the industrial furnace, and achieving the purpose of reducing the generation of nitrogen oxides.

[0068] Example 5

[0069] The difference between this embodiment and embodiment four is that:

[0070] Reference Figure 7A first retaining ring 32 is fixedly connected to the end of the air guide pipe 3 away from the exhaust pipe head 31. The outer diameter of the first retaining ring 32 is the same as the outer diameter of the air guide pipe 3, and the inner diameter of the first retaining ring 32 is smaller than the inner diameter of the air guide pipe 3. A transition pipe 33 is fixedly connected to the inner ring of the first retaining ring 32. A second retaining ring 34 is fixedly connected to the end of the transition pipe 33 away from the air guide pipe 3. The second retaining ring 34 has the same structure as the first retaining ring 32. An extension pipe 35 is fixedly connected to the side of the second retaining ring 34 away from the transition pipe 33. The extension pipe 35 has the same diameter as the air guide pipe 3, and the axes of the air guide pipe 3, the transition pipe 33, and the extension pipe 35 coincide.

[0071] A return pipe 36 is provided on the transition pipe 33. One end of the return pipe 36 is fixed to the transition pipe 33 and is connected to the interior of the transition pipe 33. The end of the return pipe 36 away from the transition pipe 33 passes through the flue gas return hole, and the end of the return pipe 36 is lower than the height of the second outer fin 123.

[0072] Since the diameter of the transition tube 33 is smaller than that of the extension tube 35 and the air guide tube 3, when air enters the interior of the transition tube 33 located between the extension tube 35 and the air guide tube 3 from the extension tube 35, it can compress the continuously entering air, thereby increasing the flow rate in the transition tube 33, further improving the smoothness of flue gas recirculation into the air guide tube 3, and improving the efficiency of flue gas entering the air guide tube 3 to mix with air for heat exchange.

[0073] Example 6

[0074] The difference between this embodiment and Embodiment 3 is as follows:

[0075] Combination Figure 5 and Figure 8 The secondary heat exchanger installed inside the flue pipe 5 is a second secondary heat exchanger 7. The second secondary heat exchanger 7 includes a first connecting flange 71 for connecting to the upper end of the flue pipe 5, a third fixed pipe 72 with one end fixed to the first connecting flange 71 and coaxially arranged in the inner hole of the first connecting flange 71, a connecting plate 73 fixed to the end of the third fixed pipe 72 away from the first connecting flange 71, multiple air inlet pipes 74 with one end passing through and fixed to the connecting plate 73 and connected to the third fixed pipe 72, a fixed plate 75 with the plate surface for the multiple air inlet pipes 74 to pass through and fixed to the outer wall of the air inlet pipes 74, multiple heat exchange plates 76 fixedly fixed at intervals along the length of the outer wall of the air inlet pipes 74, another connecting plate 73 (not shown in the figure) fixed to the other end of the multiple air inlet pipes 74, a fourth fixed pipe 78 with one end fixed to the other connecting plate 73, and a second connecting flange 77 with the inner hole sleeved and fixed to the outside of the other connecting plate 73.

[0076] In this embodiment, multiple air inlet pipes 74 are evenly distributed on two connecting plates 73, and the length direction of the multiple air inlet pipes 74 is perpendicular to the plate surface of the first connecting flange 71. The fixing plate 75 is spiral-shaped, which can delay and guide the flue gas, thereby improving the heat exchange efficiency. The third fixing pipe 72 and the fourth fixing pipe 78 have the same structure, and the end of the fourth fixing pipe 78 away from the air inlet pipe 74 can be inserted into the second connecting pipe head 22.

Claims

1. A high efficiency radiant heat exchange tube characterized by: It includes a radiant heat exchange tube (1), which includes a tube body (11) and fins (12). The tube body (11) is a circular tube with a closed end and an open end at both ends, and the closed end is processed into a hemispherical structure. The fins (12) include multiple sets of inner fins (121) integrally formed on the inner wall of the tube body (11) and multiple sets of first outer fins (122) integrally formed on the outer wall of the tube body (11). The inner fins (121) and the first outer fins (122) are arranged in a spiral pattern along the axial direction of the tube body (11).

2. A high efficiency radiant heat pipe as claimed in claim 1, wherein: The number of inner fins (121) and the number of first outer fins (122) are equal, and the end faces of two adjacent sets of inner fins (121) or first outer fins (122) are arranged opposite to each other or staggered.

3. A high efficiency radiant heat transfer tube according to claim 2, wherein: The outer wall of the closed end of the tube (11) is processed into a spherical convex surface, and multiple second outer fins (123) are provided on the spherical convex surface in a radial distribution.

4. A radiant tube heat exchanger comprising the high-efficiency radiant heat exchange tube according to any one of claims 1 to 3, characterized by: The radiant tube heat exchanger includes a connecting pipe (2) connected to the open end of the tube body (11), an air guide pipe (3) passing through the tube body (11) and the connecting pipe (2), an installation pipe (4) sleeved outside the connecting pipe (2), a flue pipe (5) connected to the installation pipe (4), and a secondary heat exchanger installed in the flue pipe (5). The secondary heat exchanger is used for secondary recovery of waste heat from the flue gas. The outer wall of the air guide pipe (3) and the inner wall of the tube body (11) form an air flow passage.

5. A radiant tube heat exchanger according to claim 4, wherein: The pipe body (11) is provided with a flue gas return hole that connects the inside and outside of it; An exhaust pipe head (31) is provided on the air guide pipe (3), and the end of the exhaust pipe head (31) away from the air guide pipe (3) is processed into a constricted shape.

6. A radiant tube heat exchanger according to claim 5, characterized in that: The flue gas return hole is opened at an angle from the closed end of the pipe body (11) to the open end of the pipe body (11); The flue gas return hole is located between the closed end of the pipe body (11) and the end of the air guide pipe (3) near the closed end of the pipe body (11), and the opening direction of the flue gas return hole is towards the end of the air guide pipe (3).

7. A radiant tube heat exchanger according to claim 5, characterized in that: A transition tube (33) is fixedly connected to one end of the air guide tube (3) away from the exhaust pipe head (31), and an extension tube (35) is fixedly connected to one end of the transition tube (33) away from the air guide tube (3). The diameter of the extension tube (35) is smaller than that of the air guide tube (3) and the air guide tube (3). The transition pipe (33) is provided with a return pipe that connects the interior of the transition pipe (33) with the flue gas return hole.

8. A radiant tube heat exchanger according to claim 4, characterized in that: The secondary heat exchanger includes a first secondary heat exchanger (6), which includes an inner tube (61), a secondary radiative heat exchanger (63) sleeved outside the inner tube (61) and spaced apart from the outer wall of the inner tube (61), and a first fixed tube (64) and a second fixed tube (65) connecting the two. An indirect heat exchange channel between the inner tube (61) and the secondary radiative heat exchanger (63) is formed between the combustion air and the flue gas.

9. A radiant tube heat exchanger according to claim 4 wherein: The secondary heat exchanger includes a second secondary heat exchanger (7), which includes a spiral fixed plate (75), multiple air inlet pipes (74) passing through and fixed to the fixed plate (75), heat exchange plates (76) fixed to the outer wall of the air inlet pipes (74), a third fixed pipe (72) and a fourth fixed pipe (78) fixed to both ends of the multiple air inlet pipes (74), and a first connecting flange (71) and a second connecting flange (77) fixed to the third fixed pipe (72) and the fourth fixed pipe (78).

10. A radiant tube heat exchanger according to claim 4, wherein: An aluminum silicate insulation layer is provided between the installation pipe (4) and the connecting pipe (2), as well as on the inner wall of the exhaust pipe (5).

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