Secondary heat exchanger of self-preheating burner and heat exchange system

Abstract

The utility model discloses a secondary heat exchanger and a heat exchange system of a self-preheating type burner, on one hand, the secondary heat exchanger of the self-preheating type burner comprises an outer shell, a heat exchange pipe and an inner pipe which are sequentially arranged from outside to inside, a smoke outlet is formed in the heat exchange pipe, the heat exchange pipe comprises an air inlet section, a smoke inlet and a cold air inlet pipe are arranged on the air inlet section, and the inner pipe is arranged in the outer shell; the cold air inlet pipe is communicated with the inner pipe, the inner pipe and the heat exchange pipe are connected with an air conveying pipe in a sealed mode, and the outer shell is communicated with a preheated air outlet. Secondly, the heat exchange system of the self-preheating type burner comprises a radiant tube provided with the self-preheating type burner and a ceramic flame tube and a secondary heat exchanger of the self-preheating type burner, the self-preheating type burner is provided with a smoke exhaust port and a preheated air inlet, the smoke inlet is communicated with the smoke exhaust port, and the preheated air inlet is communicated with the ceramic flame tube. And the preheated air inlet is communicated with the preheated air outlet. Heat of high-temperature smoke generated after combustion can be further recycled, and therefore the heat efficiency of the system is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to heat exchanger technical field, concretely relates to two -stage heat exchanger and heat exchange system of self preheating type burner. BACKGROUND

[0002] Self preheating type burner combines radiation pipe and is mainly applied to the scene needing to isolate and heat smoke gas or needing to heat under the protection gas atmosphere environment. When self preheating type burner is used for indirect heating with radiation pipe, commonly used radiation pipe forms have P type, double P type and I type radiation pipe. In actual application, self preheating type burner is usually installed at the entrance of radiation pipe, and high-temperature smoke gas produced by burning gas at the burner spout heats the radiation pipe, and the radiation pipe radiates heat to the workpiece. For P type or double P type high-temperature smoke gas, after one round trip in the radiation pipe, the high-temperature smoke gas is discharged through the outer wall of the fin of self preheating type burner. Figure 1 As shown in FIG. 1, for I type radiation pipe 3, a segmented ceramic flame pipe 2 needs to be installed in the radiation pipe 3, and high-temperature smoke gas flows from the inside of the ceramic flame pipe 2 into the channel between the outer wall of the ceramic flame pipe 2 and the inner wall of the radiation pipe 3 and is then discharged through the outer wall of the fin of the burner. When combustion-supporting air flows into the inner wall of the fin of the burner, the combustion-supporting air exchanges heat with the high-temperature smoke gas, thereby heating the combustion-supporting air and improving the thermal efficiency.

[0003] Due to the size limitation of the radiation pipe, the fin length of self preheating type burner is limited, and the heat exchange area is insufficient. In some high-temperature heat treatment furnaces, the final exhaust gas temperature is still relatively high. For example, in a conventional plain carbon steel strip continuous annealing furnace or a wide and thick plate quenching furnace, the final exhaust gas temperature is basically above 600℃. Because the exhaust gas temperature is very high, the smoke gas carries away most of the heat, resulting in low thermal efficiency of the system. UTILITY MODEL CONTENTS

[0004] The utility model discloses a two-stage heat exchanger and heat exchange system of self preheating type burner, which can further recover the heat of high-temperature smoke gas produced after combustion to preheat combustion-supporting air entering the burner, thereby improving the thermal efficiency of the system. According to actual theoretical calculation and actual application, the energy-saving efficiency can reach more than 20%, greatly saving fuel operation cost and reducing carbon emission of products.

[0005] To solve the above technical problems, the utility model adopts the following scheme:

[0006] In a first aspect, a two-stage heat exchanger of a self-preheating burner includes, from the outside to the inside, an outer shell, a heat exchange pipe, and an inner pipe. The heat exchange pipe is provided with a flue gas outlet. The heat exchange pipe includes an air inlet section at the end of the outer shell away from the flue gas outlet. The air inlet section is provided with a flue gas inlet and a cold air inlet pipe. The cold air inlet pipe penetrates the air inlet section and is connected to the inner pipe. The outer wall of the section of the inner pipe away from the air inlet section is sealingly connected to the inner wall of the corresponding position of the heat exchange pipe by a gas conveying pipe for connecting the inner pipe to the outer shell. The outer shell is provided with a preheated air outlet near the air inlet section. The cold air inlet pipe is sealingly connected to the air inlet section. The gas conveying pipe is provided with at least two around the inner pipe. The greater the number of gas conveying pipes, the greater the heat exchange area of the high-temperature flue gas passing through the section of the heat exchange pipe provided with the gas conveying pipe, and the better the heat exchange effect. The outer shell, the heat exchange pipe, and the inner pipe are all circular tubes and are coaxially arranged. The function is that, through the arrangement of the outer shell, the heat exchange pipe, and the inner pipe and the design of the spatial relationship among them, the cold air passes through the cold air inlet pipe, the inner pipe, the gas conveying pipe, the gap between the outer shell and the heat exchange pipe, and then reaches the preheated air outlet. The cold air in the inner pipe exchanges heat with the high-temperature flue gas in the heat exchange pipe through the side wall of the inner pipe, preliminarily reduces the temperature of the high-temperature flue gas, and preheats the cold air. The cold air in the gap between the outer shell and the heat exchange pipe exchanges heat with the high-temperature flue gas in the heat exchange pipe through the side wall of the heat exchange pipe, further reduces the temperature of the high-temperature flue gas, and further preheats the cold air. The heat of the high-temperature flue gas generated after combustion can be further recovered to preheat the combustion-supporting air entering the burner, thereby improving the thermal efficiency of the system. According to actual theoretical calculation and actual application, the energy-saving efficiency can reach more than 20%, greatly saving the operating fuel cost, and reducing the carbon emissions of the product.

[0007] Further, the heat exchange pipe includes, from the flue gas outlet to the air inlet section, an air outlet section, a heat exchange section, and an air inlet section, which are sealingly connected. The heat exchange section is composed of a plurality of finned pipes sealingly connected in sequence. The function is that, through the design of the heat exchange section composed of finned pipes, the heat exchange efficiency of the heat exchange pipe can be effectively improved.

[0008] Further, at least two layers of heat exchange fins are arranged on the inner and outer sides of the finned pipe along the axial direction. The heat exchange fins are uniformly distributed in a ring shape around the axis of the finned pipe and extend along the axial direction of the finned pipe. The heat exchange fins of adjacent layers are arranged in a staggered manner. The function is that, through the design of heat exchange fins on the inner and outer sides of the finned pipe, the heat exchange area can be effectively increased, thereby improving the heat exchange efficiency of the inner and outer sides of the heat exchange pipe. Through the staggered arrangement of the heat exchange fins of different layers, the disturbance of the convective heat exchange gas can be strengthened, and the temperature uniformity of the heat exchange gas can be improved.

[0009] Further, the outer shell is provided with an outer shell expansion joint at a position corresponding to the gas conveying pipe. The expansion joint is a prior art and will not be described here. Its function is to absorb the thermal expansion of the outer shell due to temperature rise, prevent the outer shell from deforming, and increase the service life of the outer shell.

[0010] Further, the inner pipe is provided with an inner pipe expansion joint at the junction of the heat exchange section and the air inlet section. Its function is to absorb the thermal expansion of the inner pipe due to temperature rise, prevent the inner pipe from deforming, and increase the service life of the inner pipe.

[0011] Further, the outer shell is provided with an outer shell expansion joint at a position corresponding to the gas conveying pipe. The expansion joint is a prior art and will not be described here. Its function is to absorb the thermal expansion of the outer shell due to temperature rise, prevent the outer shell from deforming, and increase the service life of the outer shell.

[0012] Further, the outer shell is provided with an outer shell expansion joint at a position corresponding to the gas conveying pipe. The expansion joint is a prior art and will not be described here. Its function is to absorb the thermal expansion of the outer shell due to temperature rise, prevent the outer shell from deforming, and increase the service life of the outer shell.

[0013] Further, the outer shell is provided with a lifting lug on the outer wall. Its function is to facilitate the lifting of the outer shell and the connection of the self-preheating burner.

[0014] The inner pipe is provided with an inner pipe sealing plate at the end away from the flue gas outlet. Its function is to allow the cold air entering the inner pipe from the cold air inlet pipe to be discharged only from the gas conveying pipe.

[0015] In the second aspect, the heat exchange system of the self-preheating burner comprises a radiation tube provided with the self-preheating burner and a ceramic flame tube and the secondary heat exchanger of the self-preheating burner, the self-preheating burner is provided with a flue gas outlet for discharging high-temperature flue gas and a preheated air inlet for inputting preheated cold air, the flue gas inlet is communicated with the flue gas outlet, and the preheated air inlet is communicated with the preheated air outlet. The preheated air inlet and the preheated air outlet are connected through flanges. Through the design that the preheated air inlet on the self-preheating burner is communicated with the preheated air outlet on the secondary heat exchanger, the high-temperature flue gas discharged from the self-preheating burner can be cooled, and the cold air entering the self-preheating burner can be preheated, so that the heat of the high-temperature flue gas is effectively recycled. If the flue gas temperature of the burner is about 600 DEG C, the flue gas temperature can be reduced to about 350 DEG C after passing through the secondary heat exchanger, and the cold air can be preheated to about 220 DEG C.

[0016] The utility model has the beneficial effect that:

[0017] 1. Through the setting of the outer shell, the heat exchange pipe and the inner pipe and the design of the space relationship among them, the cold air successively passes through the cold air inlet pipe, the inner pipe, the gas conveying pipe, the gap between the outer shell and the heat exchange pipe and then reaches the preheated air outlet. The cold air in the inner pipe exchanges heat with the high-temperature flue gas in the heat exchange pipe through the side wall of the inner pipe, thereby preliminarily reducing the temperature of the high-temperature flue gas and preheating the cold air. The cold air in the gap between the outer shell and the heat exchange pipe exchanges heat with the high-temperature flue gas in the heat exchange pipe through the side wall of the heat exchange pipe, thereby further reducing the temperature of the high-temperature flue gas and further preheating the cold air. The heat of the high-temperature flue gas generated after combustion can be further recycled to preheat the combustion-supporting air entering the burner, thereby improving the thermal efficiency of the system. According to actual theoretical calculation and actual application, the energy-saving efficiency can reach more than 20%, thereby greatly saving the operating fuel cost and reducing the carbon emission of the product.

[0018] 2. Through the design that the heat exchange fins are arranged on the inner and outer sides of the finned tube, the heat exchange area can be effectively increased, thereby improving the heat exchange efficiency of the inner and outer sides of the heat exchange pipe. Through the staggered arrangement of the heat exchange fins of different layers, the disturbance to the convection heat exchange gas can be strengthened, thereby improving the temperature uniformity of the heat exchange gas. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 FIG. 1 is a structural schematic diagram of the self-preheating burner in the working state in the prior art;

[0020] Figure 2 FIG. 6 is a structural schematic diagram of the secondary heat exchanger in Embodiment 1 (the arrow indicates the gas flow direction);

[0021] Figure 3 for Figure 2 Enlarged structural diagram at point A (arrows indicate gas flow direction);

[0022] Figure 4 for Figure 2 Enlarged structural diagram at point B (arrows indicate gas flow direction);

[0023] Figure 5 This is a three-dimensional structural diagram of the finned tube in Example 1;

[0024] Figure 6 This is a three-dimensional structural diagram of the heat exchange system in Example 1 (arrows indicate the direction of gas flow).

[0025] Reference numerals: 1. Self-preheating burner; 2. Ceramic flame tube; 3. Radiant tube; 4. Outer shell; 5. Heat exchange tube; 501. Inlet section; 502. Heat exchange section; 503. Outlet section; 6. Inner tube; 7. Flue gas outlet; 8. Flue gas inlet; 9. Cold air inlet pipe; 10. Gas delivery pipe; 11. Preheated air outlet; 12. Finned tube; 13. Heat exchange fin; 14. Outer shell expansion joint; 15. Inner tube expansion joint; 16. Inlet section sealing plate; 17. Outlet section sealing plate; 18. Lifting lug; 19. Flue gas outlet; 20. Preheated air inlet; 21. Inner tube sealing plate; a. Combustion gas; b. Cold air; c. Flue gas; d. Combustion air. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0027] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0028] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0029] Example 1

[0030] Firstly, the secondary heat exchanger of the self-preheating burner 1, such as Figure 2 As shown, the system includes an outer shell 4, a heat exchange tube 5, and an inner tube 6 arranged sequentially from the outside in. The heat exchange tube 5 has a flue gas outlet 7 and includes an inlet section 501 located outside the end of the outer shell 4 away from the flue gas outlet 7. The inlet section 501 has a flue gas inlet 8 and a cold air inlet pipe 9. The cold air inlet pipe 9 passes through the inlet section 501 and is connected to the inner tube 6. A gas supply pipe 10, connecting the inner tube 6 to the outer shell 4, is sealed between the outer wall of the section of the inner tube 6 away from the inlet section 501 and the inner wall of the corresponding heat exchange tube 5. A preheated air outlet 11 is connected to the outer shell 4 near the inlet section 501. The cold air inlet pipe 9 is sealed to the inlet section 501. At least two gas supply pipes 10 surround the inner tube 6. The greater the number of gas supply pipes 10, the larger the heat exchange area of ​​the high-temperature flue gas c when passing through the section of the heat exchange tube 5 with the gas supply pipes 10, and the better the heat exchange effect. The outer shell 4, heat exchange tube 5, and inner tube 6 are all cylindrical and coaxially arranged. Their function is to, through the arrangement of the outer shell 4, heat exchange tube 5, and inner tube 6, and the design of their spatial relationship, ensure that as the high-temperature flue gas c moves from the flue gas inlet 8 through the gap between the heat dissipation tube and the inner tube 6 to the flue gas outlet 7, the cold air b sequentially passes through the cold air inlet pipe 9, the inner tube 6, the gas delivery pipe 10, and the gap between the outer shell 4 and the heat exchange tube 5 before reaching the preheated air outlet 11. The cold air b located inside the inner tube 6 exchanges heat with the high-temperature flue gas c inside the heat exchange tube 5 through the side wall of the inner tube 6, initially reducing the temperature of the high-temperature flue gas c and reducing its effect on the cold air... The cold air b, located in the gap between the outer shell 4 and the heat exchange tube 5, exchanges heat with the high-temperature flue gas c inside the heat exchange tube 5 through the side wall of the heat exchange tube 5. This further reduces the temperature of the high-temperature flue gas c and further preheats the cold air b, allowing the heat from the high-temperature flue gas c generated after combustion to be recovered and used to preheat the combustion air d entering the burner, thereby improving the thermal efficiency of the system. According to actual theoretical calculations and practical applications, the energy-saving efficiency can reach more than 20%, greatly saving operating fuel costs and reducing the carbon emissions associated with the product.

[0031] Specifically, such as Figure 2As shown, the heat exchange pipe 5 includes, in sequence from the flue gas outlet 7, an air outlet section 503, a heat exchange section 502, and an air inlet section 501, and the air outlet section 503 and the heat exchange section 502 and the heat exchange section 502 and the air inlet section 501 are all sealingly connected. The heat exchange section 502 is composed of a plurality of finned tubes 12 connected end to end. Its role is to effectively improve the heat exchange efficiency of the heat exchange pipe 5 by designing the heat exchange section 502 composed of finned tubes 12.

[0032] Specifically, as shown in the figure, Figure 5 As shown, at least two layers of heat exchange fins 13 are arranged on the inner and outer sides of the finned tube 12 along the axial direction, the heat exchange fins 13 are uniformly distributed around the axis of the finned tube 12, the heat exchange fins 13 extend along the axial direction of the finned tube 12, and the adjacent two layers of heat exchange fins 13 are arranged in a staggered manner. Its role is to effectively increase the heat exchange area and improve the heat exchange efficiency of the inner and outer sides of the heat exchange pipe 5 by designing the heat exchange fins 13 on the inner and outer sides of the finned tube 12, and to strengthen the disturbance of the convective heat exchange gas and improve the temperature uniformity of the heat exchange gas by arranging the different layers of heat exchange fins 13 in a staggered manner.

[0033] Specifically, as shown in the figure, Figure 3 As shown, the outer shell 4 is provided with an outer shell expansion joint 14 at a position corresponding to the air conveying pipe 10. The expansion joint itself is a prior art and will not be described in detail. Its role is to absorb the thermal expansion of the outer shell 4 due to temperature rise, prevent the outer shell 4 from deforming, and increase the service life of the outer shell 4 by providing the outer shell expansion joint 14.

[0034] Specifically, as shown in the figure, Figure 4 As shown, the inner tube 6 is provided with an inner tube expansion joint 15 at the junction of the heat exchange section 502 and the air inlet section 501. Its role is to absorb the thermal expansion of the inner tube 6 due to temperature rise, prevent the inner tube 6 from deforming, and increase the service life of the inner tube 6 by providing the inner tube expansion joint 15.

[0035] Specifically, as shown in the figure, Figure 4 As shown, the outer shell 4 is provided with an air inlet section sealing plate 16 between the end face away from the flue gas outlet 7 and the air inlet section 501 for sealing the gap between the outer shell 4 and the air inlet section 501. Its role is to prevent the preheated cold air b from being discharged from the gap between the end face of the outer shell 4 away from the flue gas outlet 7 and the air inlet section 501, so that the preheated cold air b can only be discharged from the preheated air outlet 11 by providing the air inlet section sealing plate 16.

[0036] Specifically, as shown in the figure, Figure 3As shown in the figure, the outer shell 4 is provided with an air outlet section sealing plate 17 between the end face adjacent to the flue gas outlet 7 and the air outlet section 503 for sealing the gap between the outer shell 4 and the air outlet section 503. Its function is to avoid the preheated cold air b from the gap between the end face of the outer shell 4 adjacent to the flue gas outlet 7 and the air inlet section 501, so that the preheated cold air b can only be discharged from the preheated air outlet 11.

[0037] Specifically, as shown in the figure, Figure 1 The outer shell 4 is provided with a lifting lug 18. Its function is to facilitate the connection of the outer shell 4 and the self-preheating burner 1 by the setting of the lifting lug 18.

[0038] Specifically, as shown in the figure, Figure 4 The inner tube 6 is provided with an inner tube sealing plate 21 at the end away from the flue gas outlet 7 for sealing the end face of the inner tube 6. Its function is to make the cold air b entering the inner tube 6 from the cold air inlet pipe 9 only be discharged from the air outlet pipe 10.

[0039] Secondly, the heat exchange system of the self-preheating burner 1, as shown in the figure, Figure 5 The heat exchange system of the self-preheating burner 1, as shown in the figure, includes a radiation pipe 3 provided with the self-preheating burner 1 and the ceramic flame tube 2, and the above-mentioned secondary heat exchanger of the self-preheating burner 1. The self-preheating burner 1 is provided with a flue gas outlet 19 for discharging high-temperature flue gas c and a preheated air inlet 20 for inputting preheated cold air b. The flue gas inlet 8 is in communication with the flue gas outlet 19, and the preheated air inlet 20 is in communication with the preheated air outlet 11 (not shown in the figure). The preheated air inlet 20 and the preheated air outlet 11 are connected by flanges. Its function is to connect the preheated air inlet 20 on the self-preheating burner 1 with the preheated air outlet 11 on the secondary heat exchanger, which can not only cool the high-temperature flue gas c discharged from the self-preheating burner 1, but also preheat the cold air b entering the self-preheating burner 1, effectively recovering the heat of the high-temperature flue gas c. After adding this secondary heat exchanger to the self-preheating burner 1, if the burner flue gas temperature is about 600℃, the flue gas temperature can be reduced to about 350℃ after passing through the secondary heat exchanger, and the cold air b can be preheated to about 220℃.

[0040] The working principle of the embodiment is explained as follows: the fuel gas a is introduced into the self-preheating burner 1, and the fuel gas a is combusted at the burner nozzle to generate high-temperature flue gas c to heat the radiation tube 3; the flue gas c is discharged through the flue gas discharge port 19 into the flue gas inlet 8, and the high-temperature flue gas c entering the secondary heat exchanger flows through the gap between the cylindrical heat exchange tube 5 and the inner tube 6 to the flue gas outlet 7; in the process of flowing in the secondary heat exchanger, the cold air b entering the inner tube 6 from the cold air inlet pipe 9 successively exchanges heat with the high-temperature flue gas c from the inner and outer sides of the high-temperature flue gas c, so as to complete the cooling of the high-temperature flue gas c and the preheating of the cold air b, and the preheated cold air b is introduced into the self-preheating burner 1 as preheated air through the preheated air outlet 11 and the preheated air inlet 20 in sequence to be combusted.

[0041] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. According to the technical essence of the present application, any simple modification, equivalent replacement, improvement, etc. of the above embodiment within the spirit and principles of the present application still belongs to the protection scope of the technical scheme of the present application.

Claims

1. A two-stage heat exchanger of a self-preheating burner (1), characterized in that: The heat exchanger comprises an outer shell (4), a heat exchange pipe (5) and an inner pipe (6) arranged from outside to inside in sequence, the heat exchange pipe (5) is provided with a flue gas outlet (7), the heat exchange pipe (5) comprises an air inlet section (501) located outside the outer shell (4) away from the flue gas outlet (7), the air inlet section (501) is provided with a flue gas inlet (8) and a cold air inlet pipe (9), the cold air inlet pipe (9) penetrates through the air inlet section (501) and is connected with the inner pipe (6), the outer wall of a section of the inner pipe (6) away from the air inlet section (501) is sealingly connected with the inner wall of the corresponding position of the heat exchange pipe (5) to form a gas conveying pipe (10) for connecting the inner pipe (6) with the outer shell (4), and the outer shell (4) is provided with a preheated air outlet (11) near the air inlet section (501).

2. The two-stage heat exchanger of a self-preheating burner (1) according to claim 1, characterized in that: The heat exchange pipe (5) comprises an air outlet section (503), a heat exchange section (502) and the air inlet section (501) arranged in sequence and connected in communication along the direction away from the flue gas outlet (7), and the air outlet section (503) and the heat exchange section (502) and the heat exchange section (502) and the air inlet section (501) are sealingly connected, the heat exchange section (502) is composed of a plurality of finned pipes (12) sealingly connected in sequence.

3. The two-stage heat exchanger of a self-preheating burner (1) according to claim 2, characterized in that: The finned pipe (12) is provided with at least two layers of heat exchange fins (13) on the inner and outer sides in the axial direction, the heat exchange fins (13) are uniformly distributed in a ring shape around the axis of the finned pipe (12), the heat exchange fins (13) extend in the axial direction of the finned pipe (12), and the adjacent two layers of heat exchange fins (13) are arranged in a staggered manner.

4. The two-stage heat exchanger of a self-preheating burner (1) according to claim 1, characterized in that: The outer shell (4) is provided with an outer shell expansion joint (14) at a position corresponding to the gas conveying pipe (10).

5. The two-stage heat exchanger of a self-preheating burner (1) according to claim 2, characterized in that: The inner pipe (6) is provided with an inner pipe expansion joint (15) at the junction of the heat exchange section (502) and the air inlet section (501).

6. The two-stage heat exchanger of a self-preheating burner (1) according to claim 2, characterized in that: The outer shell (4) is provided with an air inlet section sealing plate (16) between the end face away from the flue gas outlet (7) and the air inlet section (501) for sealing the gap between the outer shell (4) and the air inlet section (501).

7. The two-stage heat exchanger of a self-preheating burner (1) according to claim 2, characterized in that: The outer shell (4) is provided with an air outlet section sealing plate (17) between the end face near the flue gas outlet (7) and the air outlet section (503) for sealing the gap between the outer shell (4) and the air outlet section (503).

8. The two-stage heat exchanger of a self-preheating burner (1) according to claim 1, characterized in that: The outer shell (4) is provided with a lifting lug (18) on the outer wall.

9. The two-stage heat exchanger of a self-preheating burner (1) according to claim 1, characterized in that: The inner pipe (6) is provided with an inner pipe sealing plate (21) at one end away from the flue gas outlet (7) for sealing the end face of the inner pipe (6).

10. Heat exchange system of a self-preheating burner (1), characterized by the fact that: The heat exchanger comprises a radiant tube (3) provided with a self-preheating burner (1) and a ceramic flame tube (2), and the self-preheating burner (1) of any one of claims 1-9, the self-preheating burner (1) is provided with a flue gas outlet (19) for discharging high-temperature flue gas and a preheated air inlet (20) for inputting preheated cold air, the flue gas inlet (8) is connected with the flue gas outlet (19), and the preheated air inlet (20) is connected with the preheated air outlet (11).

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