An improved structure for overheating problem in the upper temperature zone of the heating section of an industrial furnace

Abstract

The present invention relates to the technical field of industrial kilns, and specifically to an improved structure for solving the problem of over-temperature in the upper temperature zone of a heating section of an industrial kiln, comprising: a furnace body, and a plurality of temperature zones are arranged along the length direction of the furnace body; an exhaust system connected to the top of the furnace body, the exhaust system comprising an exhaust fan, an exhaust pipe, a first chimney and a second chimney, the exhaust pipe is arranged along the length direction of the furnace body and is connected to the exhaust fan, a plurality of temperature zones in the front section of the furnace body are connected to the exhaust pipe through the first chimney, a plurality of temperature zones in the rear section of the furnace body are connected to the exhaust pipe through the second chimney, the second chimney is closed to block the gas flow and heat transfer between adjacent temperature zones along the length direction of the furnace body; a conveyor belt is arranged along the length direction of the furnace body and transports products; an air curtain tube is arranged between adjacent temperature zones, the gas discharged from the air curtain tube forms an air curtain to cut off the airflow between adjacent temperature zones.

Description

Technical Field

[0001] The invention relates to the technical field of industrial kilns, and in particular to an improved structure for solving the problem of over-temperature in an upper temperature zone of a heating section of an industrial kiln. Background Art

[0002] In the industrial heat treatment process, the temperature control of the furnace is one of the key factors to ensure product quality and production efficiency. Especially in the process that requires precise control of temperature gradient and constant temperature range, such as carbon fiber heat treatment, material drying and metal heat treatment, the design and performance of the furnace are particularly critical.

[0003] At present, although the furnace design on the market has made some progress, there are still many challenges. For example, during high-temperature heat treatment, the upper temperature zone of the heating section is prone to overheating, which will not only lead to a decline in product quality, such as incomplete graphitization of carbon fiber or deformation of metal workpieces, but also accelerate the damage of the furnace structure and reduce the service life of the equipment.

[0004] Industrial kilns usually need to be equipped with several partitions (called "partition beams") along the length of the furnace to divide the furnace into different temperature areas (called "temperature zones") according to the requirements of the product temperature curve. This makes it easier to control the furnace temperature and prevents different temperature zones from affecting each other. In the furnace body, heaters are usually installed at the upper and lower parts of the furnace. In the furnace heating section, the product temperature is low, and the heater power usually needs to run at full power. Since the heat always flows from the bottom to the upper area in the furnace, the temperature in the upper part is always the highest inside the furnace. It often happens that the temperature of the upper part of the furnace exceeds the set temperature (called "overtemperature"). Even if the output power of the upper heater is adjusted to 0, the upper temperature zone may still be overheated. In order to reduce the temperature of the upper temperature zone, the output power of the lower heater is reduced, which will affect the lower temperature zone, making the temperature of the lower temperature zone low, and fall into a dilemma.

[0005] Traditional furnace design usually relies on a single heating system and temperature control system. Although the design can adopt a method of separately controlling the upper and lower temperature zones of each temperature zone, it is still difficult to achieve precise temperature control between the temperature zones, especially it is impossible to completely avoid overheating of the upper temperature zone of the furnace body. The prior art adopts a circulating airflow method to maintain the temperature in the furnace. This method will cause different temperature zones in the furnace to affect each other. In addition, the circulation of the airflow will not only cause adjacent temperature zones to interfere with each other, but also cause temperature fluctuations in the furnace, making it impossible to maintain the temperature stability in each temperature zone.

[0006] Therefore, the present application has developed an improved structure for overheating problem in the upper temperature zone of the heating section of an industrial furnace to solve the problems existing in the prior art. Summary of the invention

[0007] The purpose of the present invention is to provide an improved structure for the over-temperature problem of the upper temperature zone of the heating section of an industrial kiln, so as to solve the problem in the prior art that a large amount of gas flow occurs between the temperature zones distributed in the length direction of the furnace body, causing the heat to affect each other, thereby causing the temperature in each temperature zone to be unable to remain stable.

[0008] The technical solution of the present invention is: an improved structure for solving the over-temperature problem of the upper temperature zone of the heating section of an industrial furnace, comprising:

[0009] A furnace body, with a plurality of temperature zones arranged along the length direction of the furnace body;

[0010] an exhaust system connected to the top of the furnace body, the exhaust system comprising an exhaust fan, an exhaust pipe, a first chimney and a second chimney, the exhaust pipe being arranged along the length direction of the furnace body and connected to the exhaust fan, a plurality of temperature zones in the front section of the furnace body being connected to the exhaust pipe through the first chimney, a plurality of temperature zones in the rear section of the furnace body being connected to the exhaust pipe through the second chimney, and the second chimney being closed to block gas flow and heat transfer between adjacent temperature zones along the length direction of the furnace body;

[0011] A conveyor belt is arranged along the length direction of the furnace body and transports the product;

[0012] The air curtain tube is arranged between the adjacent temperature zones, and the gas discharged from the air curtain tube forms an air curtain to block the air flow between the adjacent temperature zones.

[0013] Preferably, both ends of the first chimney and the second chimney are respectively connected to the exhaust pipe and multiple temperature zones corresponding to the furnace body, and the exhaust fan is located in the middle of the front section of the furnace body, so that the multiple first chimneys are symmetrical relative to the exhaust fan.

[0014] Preferably, the multiple temperature zones in the front section of the furnace body are evenly distributed in the furnace body, and at least one second temperature zone is provided in the rear section of the furnace body, and the length of the second temperature zone is greater than the length of the temperature zone.

[0015] Preferably, the first chimney is connected to the first smoke exhaust pipe, and an adjusting part is provided on the top of the first chimney. The bottom of the adjusting part is located at the connecting position of the first chimney and the first smoke exhaust pipe, so that the outlet end of the first chimney is completely sealed. When the adjusting part rotates, the bottom of the adjusting part is away from the outlet end of the first chimney, allowing the gas to flow out.

[0016] Preferably, the second chimney is communicated with a second smoke exhaust pipe, and a sealing plate is detachably provided on the second smoke exhaust pipe, and the sealing plate seals the second smoke exhaust pipe.

[0017] Preferably, the air curtain tube includes a first air curtain tube and a pair of second air curtain tubes, the first air curtain tube is located above the conveyor belt and perpendicular to the length direction of the furnace body, and the pair of second air curtain tubes are respectively located on the left and right sides of the length direction of the furnace body and are connected with both ends of the first air curtain tube, so that the first air curtain tube and the pair of second air curtain tubes form a semi-enclosed structure surrounding the outside of the conveyor belt.

[0018] Preferably, air outlet holes are evenly distributed on the first air curtain tube and the second air curtain tube, the air outlet holes are vertical and face the conveyor belt, and the diameters of the plurality of air outlet holes are the same.

[0019] Preferably, sleeves are provided at both ends of the first air curtain tube, and an insertion portion matching the sleeve is provided at one end of the second air curtain tube. The sleeve is connected to the first air curtain tube, and when the sleeve is plugged into the insertion portion, the gas flows into the second air curtain tube through the first air curtain tube.

[0020] Preferably, a temperature-resistant cotton plate is further provided above the air curtain tube.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) Since the furnace body has different temperature zones distributed in the length direction, the present application closes the second chimney corresponding to the temperature zone of the rear section of the furnace body to prevent the heat of the front high temperature zone from flowing backward to the rear section temperature zone, affecting the temperature of the rear section temperature zone and avoiding the temperature of the rear section temperature zone from being too high; and prevents temperature fluctuations caused by excessive heat loss or the entry of external cold air, and also prevents the rear section of the furnace body from being connected to the outside world, so that the furnace body is in the airflow circulation, resulting in additional airflow between adjacent temperature zones, affecting the effect of the air curtain;

[0023] (2) Since inert gas needs to be introduced into the furnace body to provide a favorable environment for the reaction of the product, the inert gas introduced into the furnace is formed into an air curtain in the present application. The air curtain forms an effective airflow partition between two adjacent temperature zones, blocking the gas flow between the temperature zones in the length direction, preventing the heat from the high-temperature zone from being directly transferred to the low-temperature zone, thereby ensuring that the temperature of each temperature zone can be accurately controlled; at the same time, a heat-resistant cotton board for insulation is also provided above the air curtain. The air curtain tube forming the air curtain can be used to support the heat-resistant cotton board, and since the heat-resistant cotton board itself is a lightweight material, it will not cause deformation of the air inlet pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0025] Figure 1 It is a plan view of an improved structure for solving the over-temperature problem in the upper temperature zone of the heating section of an industrial furnace according to the present invention;

[0026] Figure 2 It is a plan view of the front section of the furnace body of the present invention;

[0027] Figure 3 It is a plan view of the rear section of the furnace body of the present invention;

[0028] Figure 4 It is a side view of an improved structure for solving the over-temperature problem in the upper temperature zone of the heating section of an industrial furnace according to the present invention;

[0029] Figure 5 A structural plan view of the first chimney of the present invention;

[0030] Figure 6 is a structural plan view of the second chimney of the present invention;

[0031] Figure 7 is a bottom view of the first air curtain tube of the present invention;

[0032] Figure 8 is a plan view of the first air curtain tube of the present invention;

[0033] Fig. 9 It is a plan view of the second air curtain tube of the present invention.

[0034] Among them: 1. furnace body; 11. temperature zone; 12; second temperature zone; 2. exhaust system; 21. exhaust fan; 22. exhaust duct; 23. first chimney; 231. adjustment part; 24. second chimney; 3. conveyor belt; 4. air curtain tube; 41. first air curtain tube; 411. sleeve; 42. second air curtain tube; 421. insertion part; 43. air outlet; 5. first smoke exhaust pipe; 6. second smoke exhaust pipe; 61. sealing plate; 7. heat-resistant cotton board. DETAILED DESCRIPTION

[0035] The present invention is further described in detail below in conjunction with specific embodiments:

[0036] like Figure 1-Figure 3As shown, an improved structure for overheating of the upper temperature zone of the heating section of an industrial kiln comprises a furnace body 1, an exhaust system 2, a conveyor belt 3 and an air curtain tube 4. A plurality of temperature zones 11 are arranged along the length direction of the furnace body 1. The temperature zone 11 at the front section of the furnace body 1 is connected to the exhaust duct 22 through a first chimney 23. The conveyor belt 3 is arranged along the length direction of the furnace body 1 so that the product passes through the plurality of temperature zones 11 in sequence. The second temperature zone 12 at the rear section of the furnace body 1 is connected to the exhaust duct 22 through a second chimney 24. The exhaust duct 22 is located at the top of the furnace body 1 and is arranged along the length direction of the furnace body 1. When the exhaust fan 21 is started, the exhaust duct 22 is located at the top of the furnace body 1 and is arranged along the length direction of the furnace body 1. When the furnace 1 is in operation, the smoke in the furnace body 1 is exhausted through the exhaust pipe 22 and the first chimney 23, and an air curtain tube 4 is provided between two adjacent temperature zones 11. The air discharged from the air curtain tube 4 forms an air curtain to cut off the airflow between adjacent temperature zones, so that an effective temperature isolation layer is formed between the adjacent temperature zones to prevent the heat from the high-temperature zone from being directly transferred to the low-temperature zone, thereby ensuring that the temperature of each temperature zone can be accurately controlled, and by adjusting the airflow speed and direction of the air curtain tube 4, the airflow distribution in the furnace body 1 can be further controlled to avoid unnecessary heat exchange and temperature fluctuations.

[0037] Among them, the second chimney 24 is located at the rear section of the furnace body 1 and is closed to block the gas flow and heat transfer between adjacent temperature zones along the length direction of the furnace body 1, which can effectively control the temperature of the area, prevent temperature fluctuations caused by excessive heat loss or the entry of external cold air, and reduce heat loss, ensuring the temperature stability of the rear temperature zone, which is conducive to more precise temperature control, more uniform temperature distribution, and reducing temperature gradients. At the same time, it also avoids the furnace body 1 and the external environment from forming a circulating airflow, causing the heat in the front section of the furnace body 1 to move toward the rear of the furnace, resulting in the temperature of the upper temperature zone of the furnace body 1 being too high and overheating. In addition, closing the rear temperature zone can reduce heat loss and temperature fluctuations inside the furnace body 1, and prevent additional airflow between adjacent temperature zones from affecting the gas flow of the air curtain tube 4, thereby affecting the temperature zone isolation effect of the air curtain tube 4.

[0038] In the present embodiment, both ends of the first chimney 23 and the second chimney 24 are respectively connected to the exhaust pipe 22 and the multiple temperature zones 11 of the corresponding furnace body 1. When the product in the furnace body 1 moves along the length direction of the furnace body 1, it passes through each temperature zone in turn. After the reaction, the smoke is discharged to the exhaust pipe 22 through the first chimney 23 and the second chimney 24. The exhaust pipe 22 is connected to the exhaust fan 21. The exhaust fan 21 is operated to discharge the smoke from the furnace body 1. The exhaust fan 21 is located in the middle of the front section of the furnace body 1, so that the multiple first chimneys 23 are symmetrical with respect to the exhaust fan 21. The symmetrical distribution of the first chimneys 23 can ensure that the distribution of smoke in the furnace body 1 is more uniform, and the smoke will not be concentrated in a certain area and cannot be discharged in a short time due to excessive pressure in some areas of the furnace body 1. The residence time and accumulation of smoke in the furnace body 1 are reduced, thereby improving the smoke exhaust efficiency, helping to balance the airflow in each chimney, and preventing the airflow in some chimneys from being too large or too small, resulting in uneven smoke emission or local overheating.

[0039] Furthermore, the multiple temperature zones 11 at the front section of the furnace body 1 are evenly distributed inside the furnace body 1, which helps to provide a stable and gradually changing temperature environment for the product during the heating stage, and reduce the thermal stress of the product caused by sudden temperature changes during the heating process. The rear section of the furnace body 1 is provided with at least one second temperature zone 12, and the length of the second temperature zone 12 is greater than the length of the temperature zone 11, which can more effectively utilize heat, improve heating efficiency, and can further fine-tune the temperature distribution to ensure that the product can obtain a uniform and stable heat treatment effect at a higher temperature.

[0040] like Figure 5 As shown, in order to more accurately control the temperature in the furnace body 1 and prevent the occurrence of overheating in the furnace body 1, the first chimney 23 is connected to the first smoke exhaust pipe 5, and the smoke enters the exhaust pipe 22 through the first chimney 23 and the first smoke exhaust pipe 5, and the top of the first chimney 23 is provided with an adjusting portion 231, and the bottom of the adjusting portion 231 is located at the connection position of the first chimney 23 and the first smoke exhaust pipe 5, so that the outlet end of the first chimney 23 is completely sealed. When the adjusting portion 231 rotates, the bottom of the adjusting portion 231 is away from the outlet end of the first chimney 23, so that the gas flows out, and the adjusting portion 231 is rotated. 1. Accurately control the gas flow rate at the outlet end of the first chimney 23. When the regulating part 231 rotates to the bottom to completely seal the outlet end of the first chimney 23, the gas is completely blocked and cannot flow out. When the regulating part 231 rotates to make its bottom away from the outlet end, the gas can flow out smoothly. The size of the flow rate depends on the rotation angle of the regulating part 231, which helps to reduce the flow resistance of the smoke in the chimney, so that the smoke can be discharged more smoothly, and at the same time, it can also avoid accumulation or backflow in the chimney. The emission of smoke is controlled by rotating the regulating part 231 to prevent the generation of overheating.

[0041] like Figure 6As shown, the second chimney 24 is connected to the second smoke exhaust pipe 6, and a detachable sealing plate 61 is provided on the second smoke exhaust pipe 6 to seal the second smoke exhaust pipe. The sealing plate 61 can be opened or closed at any time according to actual needs, and the number of opening and closing of the sealing plate 61 can be selected to meet different emission requirements.

[0042] In this embodiment, Figure 7-Figure 9 As shown, the air curtain tube 4 includes a first air curtain tube 41 and a pair of second air curtain tubes 42 , and the first air curtain tube 41 and the second air curtain tube 42 are made of heat-resistant stainless steel or silicon carbide material.

[0043] The first air curtain tube 41 is located above the conveyor belt 3 and is perpendicular to the length direction of the furnace body 1. A pair of second air curtain tubes 42 are respectively located on the left and right sides of the length direction of the furnace body 1 and are connected to the two ends of the first air curtain tube 41, so that the first air curtain tube 41 and the pair of second air curtain tubes 42 form a semi-enclosed structure surrounding the outside of the conveyor belt 3, and the first air curtain tube 41 and the second air curtain tube 42 are evenly distributed with air outlet holes 43. When inert gas is introduced into the first air curtain tube 41, the inert gas fills the first air curtain tube 41 and the second air curtain tube 42 and is discharged through the air outlet holes 43, and the inert gas is evenly blown to the conveyor belt 3 and the space around it, forming an effective temperature isolation barrier to enhance the temperature isolation effect. The diameters of the multiple air outlet holes 43 are the same. When the diameters of the air outlet holes 43 are the same, the gas can maintain a relatively uniform flow rate and flow direction when passing through the air outlet holes 43, thereby reducing the generation of eddies and turbulence, helping to reduce energy loss, improve the efficiency and stability of gas flow, and ensure the stability of the air curtain tube 4 barrier.

[0044] Furthermore, if Figure 4 As shown, the air outlet holes 43 are all perpendicular to and toward the conveyor belt 3, and are evenly distributed on the first air curtain tube 41 and the second air curtain tube 42, so that the inert gas is evenly blown out from multiple positions to form a stable and uniform air curtain tube 4 barrier, and the air outlet holes 43 are perpendicular to and toward the conveyor belt 3, which can ensure that the gas is directly blown to the conveyor belt 3 and the space around it, forming an effective temperature isolation barrier. By precisely controlling the flow rate and pressure of the gas, the airflow inside the furnace body 1 can be ensured to be stable, reducing the mutual influence of adjacent temperature zones caused by temperature fluctuations or uneven airflow.

[0045] The first air curtain tube 41 and the second air curtain tube 42 are arranged around the conveyor belt 3 by integral molding or plug-in. Preferably, sleeves 411 are provided at both ends of the first air curtain tube 41, and an insertion portion 421 matching the sleeve 411 is provided at one end of the second air curtain tube 42. The sleeve 411 is connected to the first air curtain tube 41. When the sleeve 411 is plugged with the insertion portion 421, the gas flows into the second air curtain tube 42 through the first air curtain tube 41. The plug-in design of the sleeve 411 and the insertion portion 421 can not only make the connection between the first air curtain tube 41 and the second air curtain tube 42 more stable and not easy to loosen due to gas pressure, but also can be flexibly configured and adjusted according to different application requirements.

[0046] In order to block the heat transfer between adjacent temperature zones, a temperature-resistant cotton board 7 is also provided above the air curtain tube 4. The temperature-resistant cotton board 7 has good fire resistance and can maintain structural stability in a high temperature environment. It can effectively prevent high-temperature heat from being transferred through the pipeline, reduce energy loss, and improve thermal efficiency.

[0047] The implementation principle of this embodiment:

[0048] When processing the product, the product moves along the length direction of the furnace body 1 driven by the conveyor belt 3, and passes through different temperature zones in turn. An air curtain tube 4 is provided between adjacent temperature zones 11 and between adjacent temperature zones 11 and the second temperature zone 12. By flushing inert gas into the first air curtain tube 41, the first air curtain tube 41 and the second air curtain tube 42 are filled with inert gas and flow out from the air outlet 43, so that an air curtain barrier is formed around the conveyor belt 3 to isolate the two adjacent temperature zones to prevent the adjacent temperature zones from affecting each other. An exhaust pipe is provided on the top of the furnace body 1, and the smoke in the furnace body 1 is discharged through the first chimney 23 and the second chimney 24. The second chimney 24 is closed so that the temperature zone in the rear section of the furnace body 1 will not be discharged, thereby avoiding the formation of airflow circulation in the furnace body 1, which causes the airflow to move backward, causing the temperature of the upper temperature zone to be too high and produce overheating, and also avoiding the influence of the airflow on the air curtain tube 4 barrier, so that the effect of the air curtain tube 4 is not ideal and the temperature zone isolation effect is not good.

[0049] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the scope of protection of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is limited by the attached claims rather than the above description, and it is intended to include all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. An improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace, characterized in that: include: A furnace body (1), wherein a plurality of temperature zones (11) are provided along the length direction of the furnace body (1); an exhaust system (2) connected to the top of the furnace body (1), the exhaust system (2) comprising an exhaust fan (21), an exhaust pipe (22), a first chimney (23) and a second chimney (24); the exhaust pipe (22) is arranged along the length direction of the furnace body (1) and is connected to the exhaust fan (21); the plurality of temperature zones (11) at the front section of the furnace body (1) are connected to the exhaust pipe (22) through the first chimney (23); the plurality of temperature zones (11) at the rear section of the furnace body (1) are connected to the exhaust pipe (22) through the second chimney (24); the second chimney (24) is closed to block gas flow and heat transfer between adjacent temperature zones along the length direction of the furnace body (1); A conveyor belt (3) is arranged along the length direction of the furnace body (1) and transports the product; An air curtain tube (4) is arranged between adjacent temperature zones (11), and gas discharged from the air curtain tube (4) forms an air curtain to block the air flow between adjacent temperature zones (11); The air curtain tube (4) comprises a first air curtain tube (41) and a pair of second air curtain tubes (42), wherein the first air curtain tube (41) is located above the conveyor belt (3) and is perpendicular to the length direction of the furnace body (1), and the pair of second air curtain tubes (42) are respectively located on the left and right sides of the length direction of the furnace body (1) and are connected to both ends of the first air curtain tube (41), so that the first air curtain tube (41) and the pair of second air curtain tubes (42) form a semi-enclosed structure surrounding the outside of the conveyor belt (3).

2. According to claim 1, an improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace is characterized in that: The two ends of the first chimney (23) and the second chimney (24) are respectively connected to the exhaust pipe (22) and the corresponding multiple temperature zones (11) of the furnace body (1); the exhaust fan (21) is located in the middle of the front section of the furnace body (1), so that the multiple first chimneys (23) are symmetrical relative to the exhaust fan (21).

3. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: The plurality of temperature zones (11) at the front section of the furnace body (1) are evenly distributed in the furnace body (1), and the rear section of the furnace body (1) is provided with at least one second temperature zone (12), and the length of the second temperature zone (12) is greater than the length of the temperature zone (11).

4. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: The first chimney (23) is connected to the first smoke exhaust pipe (5); an adjusting portion (231) is provided at the top of the first chimney (23); the bottom of the adjusting portion (231) is located at the connection position between the first chimney (23) and the first smoke exhaust pipe (5), and the outlet end of the first chimney (23) is completely sealed; when the adjusting portion (231) rotates, the bottom of the adjusting portion (231) moves away from the outlet end of the first chimney (23), allowing gas to flow out.

5. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: The second chimney (24) is in communication with the second smoke exhaust pipe (6), and a sealing plate (61) is detachably provided on the second smoke exhaust pipe (6), wherein the sealing plate (61) seals the second smoke exhaust pipe (6).

6. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: The first air curtain tube (41) and the second air curtain tube (42) are evenly distributed with air outlet holes (43), the air outlet holes (43) are all perpendicular and facing the conveyor belt (3), and the diameters of the plurality of air outlet holes (43) are all the same.

7. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: Sleeves (411) are provided at both ends of the first air curtain tube (41), and an insertion portion (421) matching the sleeve (411) is provided at one end of the second air curtain tube (42); the sleeve (411) is in communication with the first air curtain tube (41), and when the sleeve (411) and the insertion portion (421) are plugged into each other, gas flows into the second air curtain tube (42) through the first air curtain tube (41).

8. The improved structure for overheating in the upper temperature zone of the heating section of an industrial furnace according to claim 1 is characterized in that: A heat-resistant cotton plate (7) is also provided above the air curtain tube (4).

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