Double-layer radiant tube heating system suitable for corrosive environment

Abstract

The utility model discloses a double-layer radiant tube heating system suitable for a corrosive environment, which belongs to the technical field of heat treatment equipment and comprises a heating furnace, a gas burner, an inner radiant tube and an outer radiant tube, the gas burner is arranged on one side of the heating furnace and comprises an air guide pipe, a combustion chamber is arranged at the end of the air guide pipe, and the outer radiant tube is arranged in the combustion chamber. The air conduit is sleeved with a heat exchanger, a heat exchange channel is formed between the heat exchanger and the heat exchanger, the heat exchanger is sleeved with an air shell, a smoke channel is formed between the heat exchanger and the air shell, and the air shell is provided with a smoke outlet and an air inlet; the inner radiant tube extends into the heating furnace, a flame inner tube is arranged in the inner radiant tube, and a radiation space is formed between the inner radiant tube and the flame inner tube; the inner radiant tube is sleeved with the outer radiant tube, a closed isolation interlayer is formed between the outer radiant tube and the inner radiant tube, and an atmosphere detector is arranged in the isolation interlayer; according to the utility model, heat treatment can be carried out on workpieces in a corrosive environment, and the safety and reliability of a combustion system are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of heat treatment equipment, and particularly relates to a double-layer radiant tube heating system suitable for a corrosive environment. Background Art

[0002] In industrial heat treatment furnaces and heating furnaces, a large proportion of special workpieces or high-standard workpieces have relatively high requirements for the heat treatment environment. It is required that the workpieces are not affected by the atmosphere of combustion products during the heating process. Usually, radiant tube burners are used to radiate heat into the furnace chamber, and at the same time, a specific heating environment is set in the furnace chamber to realize the heat treatment of the workpieces. For example, a non-oxidizing furnace fills the heating space by introducing a protective gas, and a salt bath furnace immerses the workpieces in a molten liquid. Both the non-oxidizing furnace and the salt bath furnace can cooperate with the radiant tube burner to perform heat treatment on the workpieces. However, in the above heat treatment process of the radiant tube burner, the radiant tube is corroded and damaged under the corrosive action of factors such as high temperature and heating environment. As a result, the combustion products generated by the burner leak into the heating environment in the furnace chamber. In particular, a salt bath furnace filled with molten liquid is more likely to corrode the radiant tube. After the radiant tube is corroded, it may even cause the molten liquid to penetrate into the burner, damaging the components inside the burner. At present, most radiant tube burners are difficult to cope with a heating environment with strong corrosion, which affects the service life of the radiant tube burner.

[0003] Chinese Patent with Publication No. CN112696675A discloses a radiant tube combustion device, including a radiant tube, a gas burner, a gas pipe, a radiant tube heat exchange device, an ejector, an expansion joint connector, a swirler, a double-electrode ignition electrode, and a staged air sleeve. A radiant tube heat exchange device is installed at one end of the radiant tube, and a gas burner is installed at the other end of the radiant tube. A gas pipe is installed on the gas burner body, and a swirler is installed at the outlet of the gas pipe. A staged air sleeve is installed on the outer wall of the swirler. One end of the double-electrode ignition electrode is installed on the flange at one end of the gas burner body, and the other end of the double-electrode ignition electrode passes through the gas pipe and is installed on the swirler. After the gas burner of the above combustion device burns to generate heat, the heat is radiated externally through the radiant tube to realize the heat treatment of the workpieces, which can avoid the direct contact between the combustion products generated by the gas burner and the workpieces. However, if it is necessary to perform heat treatment on the workpieces in a heating environment with strong corrosion, the radiant tube will be gradually corroded, resulting in a gradual reduction in its thickness. Eventually, the radiant tube may be corroded until it is damaged, causing the combustion products to leak into the heating environment or the corrosive substances to penetrate into the radiant tube, resulting in the corrosion and damage of components such as the gas burner. There is no structure in the above combustion device to cope with a heating environment with strong corrosion, so there is still room for improvement. Summary of the Utility Model

[0004] In view of the technical deficiencies in the background art, the present utility model proposes a double-layer radiant tube heating system applicable to corrosive environments, which solves the above technical problems and meets the actual requirements. The specific technical solutions are as follows:

[0005] A double-layer radiant tube heating system applicable to corrosive environments includes a heating furnace, a gas burner, an inner radiant tube, and an outer radiant tube. The gas burner is provided on one side of the heating furnace. The gas burner includes the following structure: an air duct. A combustion chamber is provided at one end of the air duct close to the interior of the heating furnace. An ignition electrode and a gas pipe that both extend into the combustion chamber are provided in the air duct. A heat exchanger is sleeved outside the air duct. A heat exchange channel is formed between the heat exchanger and the air duct. An air housing is sleeved outside the heat exchanger. A flue gas channel is formed between the air housing and the heat exchanger. The air housing is provided with a flue gas outlet communicating with the flue gas channel and an air inlet communicating with the heat exchange channel;

[0006] The inner radiant tube is fixedly connected to the air housing and extends into the heating furnace. The end of the inner radiant tube that extends forms a closed end. A flame inner tube matching the combustion chamber is provided in the inner radiant tube. A radiation space matching the flue gas channel is formed between the inner radiant tube and the flame inner tube; The outer radiant tube is sleeved outside the inner radiant tube. A sealed isolation layer is formed between the outer radiant tube and the inner radiant tube. An atmosphere detector is provided in the isolation layer.

[0007] As a further technical solution of the present utility model, a plurality of primary air holes are provided at one end of the air duct away from the combustion chamber. The interior of the air duct communicates with the air inlet through the primary air holes.

[0008] As a further technical solution of the present utility model, a gas head is provided at one end of the gas pipe close to the combustion chamber. The gas head is provided with a plurality of gas holes facing the inner wall of the combustion chamber. A gas groove surrounding a circle along the plurality of gas holes is provided on the surface of the gas head.

[0009] As a further technical solution of the present utility model, a wind disk support is provided in the air duct. The wind disk support includes a turbulence disk wound along the inner wall of the air duct and a fixed support fixedly connected to both the gas pipe and the combustion chamber. The wind disk support is located on the side of the combustion chamber away from the flame inner tube.

[0010] As a further technical solution of the present utility model, the heat exchanger is provided with a plurality of first heat exchange fins extending from the heat exchange channel to the flue gas channel.

[0011] As a further technical solution of the present utility model, the interior of the air housing is hollow to form an air channel. Both ends of the air channel communicate with the air inlet and the heat exchange channel respectively.

[0012] As a further technical solution of the present utility model, at least one spoiler plate that truncates the air passage is provided in the air passage, and a plurality of jet holes penetrate through the surface of the spoiler plate.

[0013] As a further technical solution of the present utility model, a plurality of second heat exchange fins are provided in the air passage.

[0014] As a further technical solution of the present utility model, a smoke pipe that is respectively communicated with the smoke outlet and the smoke passage is provided in the air housing, and the air inlet faces one side of the radial surface of the smoke pipe.

[0015] The beneficial effects of the present utility model are as follows:

[0016] After the present utility model generates heat through the combustion of the gas burner, the heat is radiated into the furnace of the heating furnace through the inner radiation tube and the outer radiation tube in sequence. The filling medium in the isolation interlayer can ensure that the heat is normally radiated into the heating medium, and the workpiece is indirectly heat-treated through the heating medium. During the heat treatment process, the outer radiation tube can prevent the inner radiation tube from directly contacting the heating medium. The atmosphere detector is used to detect whether the outer radiation tube is corroded and damaged due to corrosive factors such as the heating medium and high temperature. When the inner radiation tube faces the risk of being corroded, the heat treatment of the workpiece is suspended in time to avoid the direct contact between the combustion reaction products and the workpiece and the penetration of the heating medium into the gas burner, improving the safety and reliability of the combustion system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a double-layer radiation tube heating system applicable to a corrosive environment.

[0018] Figure 2 is a schematic structural diagram of a double-layer radiation tube burner of a double-layer radiation tube heating system applicable to a corrosive environment.

[0019] Figure 3 is a schematic structural diagram of a gas burner of a double-layer radiation tube heating system applicable to a corrosive environment.

[0020] Figure 4 is Figure 3 a partial schematic diagram at A in

[0021] Figure 5 is a schematic structural diagram of a double-layer radiation tube burner of a double-layer radiation tube heating system applicable to a corrosive environment when it is vertically arranged.

[0022] Figure 6 is Figure 3 a partial schematic diagram at B in

[0023] Figure 7It is a schematic structural diagram of a gas head of a double-layer radiant tube heating system applicable to a corrosive environment.

[0024] Figure 8 It is Figure 3 A partial schematic diagram at position C in

[0025] Figure 9 It is a schematic structural diagram of a second embodiment of an air housing of a double-layer radiant tube heating system applicable to a corrosive environment.

[0026] Wherein: heating furnace 1, gas burner 2, air duct 21, primary air holes 211, combustion chamber 22, ignition electrode 23, gas pipe 24, gas head 241, gas holes 242, gas grooves 243, heat exchanger 25, heat exchange channels 251, flue gas channels 252, first heat exchange fins 253, air housing 26, flue gas outlet 261, air inlet 262, air channels 263, spoiler plates 264, jet holes 265, second heat exchange fins 266, wind disk brackets 27, spoiler disks 271, fixed brackets 272, flue gas pipes 28, inner radiant tubes 3, closed ends 31, flame inner tubes 32, radiation spaces 33, outer radiant tubes 4, isolation interlayers 41, atmosphere detectors 42. Specific embodiments

[0027] The following will describe the embodiments of the present invention in conjunction with the accompanying drawings and related embodiments. The embodiments of the present invention are not limited to the following embodiments, and the related necessary components of the present invention in the technical field should be regarded as well-known technologies in the technical field and can be known and mastered by those skilled in the technical field.

[0028] As Figure 1-4 shown, a double-layer radiant tube heating system applicable to a corrosive environment includes a heating furnace 1, a gas burner 2, inner radiant tubes 3, and outer radiant tubes 4. The gas burner 2 is arranged on one side of the heating furnace 1. The gas burner 2 includes the following structures: an air duct 21, a combustion chamber 22 is provided at one end of the air duct 21 close to the inside of the heating furnace 1, an ignition electrode 23 and a gas pipe 24 that both extend into the combustion chamber 22 are provided in the air duct 21, a heat exchanger 25 is sleeved outside the air duct 21, a heat exchange channel 251 is formed between the heat exchanger 25 and the air duct 21, an air housing 26 is sleeved outside the heat exchanger 25, a flue gas channel 252 is formed between the air housing 26 and the heat exchanger 25, the air housing 26 is provided with a flue gas outlet 261 communicating with the flue gas channel 252 and an air inlet 262 communicating with the heat exchange channel 251; several primary air holes 211 are provided at one end of the air duct 21 away from the combustion chamber 22, and the inside of the air duct 21 is communicated with the air inlet 262 through the primary air holes 211;

[0029] The inner radiation tube 3 is fixedly connected to the air housing 26 and extends into the heating furnace 1. The end of the inner radiation tube 3 where it extends forms a closed end 31. Inside the inner radiation tube 3, there is a flame inner tube 32 that matches the combustion chamber 22. A radiation space 33 that matches the flue gas passage 252 is formed between the inner radiation tube 3 and the flame inner tube 32. The outer radiation tube 4 is sleeved outside the inner radiation tube 3. A sealed isolation layer 41 is formed between the outer radiation tube 4 and the inner radiation tube 3. An atmosphere detector 42 is provided inside the isolation layer 41.

[0030] The heating system of the present utility model is applicable to heat-treat workpieces in a heating environment with relatively high corrosiveness. A closed furnace chamber is formed inside the heating furnace 1. A furnace door is provided at the top of the heating furnace 1 so that the furnace chamber can be opened or closed, facilitating the loading of workpieces to be processed and the removal of processed workpieces. Heating medium is injected into the furnace chamber through an external pipeline on one side or at the top of the heating furnace 1, submerging the workpieces to be processed in the heating medium. The surface of the outer radiation tube 4 is in direct contact with the heating medium, which is used to isolate the inner radiation tube 3 from the heating medium, preventing the heating medium from directly contacting the inner radiation tube 3. The gas burner 2 guides the gas into the combustion chamber 22 through the gas pipe 24. At the same time, the combustion-supporting air enters the air duct 21 along the primary air holes 211 through the air inlet 262 as the primary air and is mixed with the gas in the combustion chamber 22 to form a mixed gas. Then, the mixed gas is ignited by the ignition electrode 23 to generate a flame. The flame sprays from the opening on the side of the combustion chamber 22 close to the flame inner tube 32 into the flame inner tube 32. The heat generated by the flame is radiated to the isolation layer 41 through the inner radiation tube 3, and then the heat is radiated to the heating medium through the outer radiation tube 4 to achieve the heat treatment of the workpiece.

[0031] After adopting the above structure, it should be noted that the flame generated by the combustion of the mixed gas extends along the inside of the flame inner tube 32 towards the closed end 31 and generates a large amount of hot air currents containing heat. After the hot air currents collide with the closed end 31, they disperse towards the inner wall of the inner radiation tube 3, and then the hot air currents enter the radiation space 33 along the inner wall of the inner radiation tube 3. During the flow of the hot air currents in the radiation space 33, heat is radiated from the inner wall of the inner radiation tube 3 to the isolation layer 41, thereby gradually reducing the heat in the hot air currents. When the hot air currents flow to the end close to the combustion chamber 22, they form flue gas and enter the flue gas channel 252. In addition, the isolation layer 41 can be filled with polyatomic gases such as water vapor and carbon dioxide as filling media. When the inner radiation tube 3 radiates heat externally, the filling media can transfer heat through the thermal motion of molecules, thereby transferring the heat on the surface of the inner radiation tube 3 to the outer radiation tube 4, and the outer radiation tube 4 transfers heat by contacting the heating medium, thereby realizing another heat transfer method in addition to thermal radiation. When the outer radiation tube 4 is corroded by the heating medium until it is damaged, the filling media inside the isolation layer 41 will change due to leakage. The atmosphere detector 42 preferably uses a humidity sensor. Since the leakage of water vapor into the furnace or the penetration of the molten liquid into the isolation layer 41 will cause humidity changes, the integrity of the outer radiation tube 4 can be judged by detecting the humidity change inside the isolation layer 41 by the atmosphere detector 42. After the outer radiation tube 4 is damaged, the gas burner 2 needs to be suspended and a new outer radiation tube 4 needs to be replaced before continuing the heat treatment of the workpiece.

[0032] Furthermore, the isolation layer 41 can be filled with a liquid with a relatively high thermal conductivity as the filling medium, and then structures such as a propeller can be set to promote the flow of the filling medium, which can improve the efficiency of heat transfer of the filling medium. However, when the outer radiation tube 4 is corroded by the heating medium until it is damaged, the filling medium may be mixed into the heating medium, resulting in contamination of the heating medium and the workpiece. Therefore, using a liquid as the filling medium is not commonly used in practical applications. Preferably, the inside of the isolation layer 41 is in a vacuum state. Since the inner radiation tube 3 transfers heat through thermal radiation and does not require a medium, and there is no medium in the vacuum isolation layer 41 to absorb or scatter the radiation energy, the efficiency of heat radiation of the inner radiation tube 3 can be improved. At the same time, the atmosphere detector 42 can use a pressure sensor to sense the change in the internal pressure of the isolation layer 41 to judge whether the outer radiation tube 4 is damaged due to corrosion.

[0033] Furthermore, the gas burner 2, the inner radiation tube 3, and the outer radiation tube 4 together form the structure of a double-layer radiation tube burner. The double-layer radiation tube burner can be arranged horizontally or vertically in the heating furnace 1. When the double-layer radiation tube burner is arranged horizontally, such as Figure 1As shown, when a molten liquid is used as the heating medium, the outer radiation tube 4 can be completely immersed in the heating medium, and the outer radiation tube 4 can be in direct contact with the heating medium to improve the heat transfer efficiency, so as to better heat-treat the workpiece through the liquid heating medium; when the double-layer radiation tube burner is vertically arranged, as Figure 5 shown, since the liquid heating medium usually does not completely fill the furnace chamber of the heating furnace 1, it will cause the outer radiation tube 4 to not be completely immersed in the heating medium, thus affecting the heat transfer efficiency. Therefore, the vertically arranged double-layer radiation tube burner is suitable for the heating furnace 1 filled with a gaseous heating medium.

[0034] Furthermore, when the hot gas completes heat radiation through the inner radiation tube 3 and forms flue gas and enters the flue gas passage 252, the flue gas is discharged from the flue gas outlet 261 after passing through the flue gas passage 252. At the same time, the combustion-supporting air is shunted at the primary air holes 211 and the heat exchange passage 251. A part of the combustion-supporting air flows along the heat exchange passage 251 and serves as secondary air. The secondary air exchanges heat with the flue gas in the flue gas passage 252 through the heat exchanger 25 in the heat exchange passage 251. The heat in the flue gas is transferred to the combustion-supporting air to increase the temperature of the combustion-supporting air, thereby recovering the heat in the flue gas, improving the heat utilization rate and reducing the total consumption of the fuel gas; the heat-exchanged secondary air is mixed with the flame at the opening of the combustion chamber 22 to make the combustion-supporting air burn in stages, achieving the purpose of extending the combustion reaction zone, which can play the role of reducing the combustion reaction rate, and further reducing the temperature of the combustion flame and the generation amount of thermal-type nitrogen oxides.

[0035] In summary, the utility model generates heat through the combustion of the gas burner 2 and then radiates heat into the furnace chamber of the heating furnace 1 through the inner radiation tube 3 and the outer radiation tube 4 in sequence. The filling medium in the isolation interlayer 41 can ensure that the heat is normally radiated into the heating medium, and the workpiece is indirectly heat-treated through the heating medium. During the heat treatment process, the outer radiation tube 4 can prevent the inner radiation tube 3 from being in direct contact with the heating medium. The atmosphere detector 42 is used to detect whether the outer radiation tube 4 is corroded and damaged due to corrosive factors such as the heating medium and high temperature. When the inner radiation tube 3 is at risk of being corroded, the heat treatment of the workpiece is suspended in time to avoid the direct contact between the combustion reaction products and the workpiece and the penetration of the heating medium into the interior of the gas burner 2, improving the safety and reliability of the combustion system.

[0036] As Figure 3 、 6As shown, as one of the preferred embodiments of the present utility model, a gas head 241 is provided at one end of the gas pipe 24 close to the combustion chamber 22. The gas head 241 is provided with a number of gas holes 242 facing the inner wall of the combustion chamber 22, and a gas groove 243 is provided on the surface of the gas head 241 around the number of gas holes 242; the gas participating in the combustion reaction flows through the gas pipe 24 into the combustion chamber 22 to participate in the combustion. The gas head 241 is internally connected to the gas pipe 24 and is used to release the gas into the combustion chamber 22. After the gas is discharged from the gas holes 242, it will first fill into the gas groove 243, and then form an annular gas flow and mix with the combustion-supporting air. The annular gas flow can improve the uniformity and intensity of the mixture with the air, and can make the flame formed by the combustion be distributed in a ring around the gas head 241 and spray towards the flame inner pipe 32, improving the stability of the flame and reducing the local high temperature inside the flame, and avoiding the generation of thermal-type nitrogen oxides.

[0037] As Figure 3 , 7 shown, as one of the preferred embodiments of the present utility model, a wind disk bracket 27 is provided inside the air duct 21. The wind disk bracket 27 includes a spoiler disk 271 wound along the inner wall of the air duct 21 and a fixed bracket 272 fixedly connected to both the gas pipe 24 and the combustion chamber 22. The wind disk bracket 27 is located on the side of the combustion chamber 22 away from the flame inner pipe 32; the wind disk bracket 27 is used to fix the air duct 21, the gas pipe 24, and the combustion chamber 22 to each other, and at the same time, the spoiler disk 271 turbulates the combustion-supporting air flowing along the inner wall of the air duct 21, improving the mixing uniformity and mixing intensity of the combustion-supporting air and the gas in the combustion chamber 22. The combustion-supporting air turbulated by the spoiler disk 271 enters the combustion chamber 22 along the space between the fixed brackets 272. Since the gas head 241 is provided with gas holes 242 and a gas groove 243, it is not necessary to provide a wind disk with a number of through holes to disperse the combustion-supporting air and then enter the combustion chamber 22, and the gas and the combustion-supporting air can be evenly mixed.

[0038] As Figure 3 shown, as one of the preferred embodiments of the present utility model, the heat exchanger 25 is provided with a number of first heat exchange fins 253 extending from the heat exchange channel 251 to the flue gas channel 252; the first heat exchange fins 253 can contact the flue gas and the secondary air through a large specific surface area, which can improve the heat exchange efficiency between the flue gas and the secondary air and improve the effective recovery rate of the waste heat in the flue gas.

[0039] As Figure 3 , 8As shown, as one of the preferred embodiments of the present utility model, the interior of the air housing 26 is hollow to form an air passage 263. Both ends of the air passage 263 are respectively communicated with an air inlet 262 and a heat exchange passage 251. The air housing 26 is the structure of the gas burner 2 exposed outside the heating furnace 1 and is fixedly connected to both the inner radiation tube 3 and the outer radiation tube 4. Part of the heat in the inner radiation tube 3 and the outer radiation tube 4 will be transferred to the air housing 26 through the connection structure. When the combustion-supporting air just enters the air passage 263, its temperature is relatively low. When the combustion-supporting air flows in the air passage 263, it can absorb the heat in the air housing 26, reduce the surface temperature of the air housing 26, and can increase the temperature of the combustion-supporting air. In addition, when the combustion-supporting air flows in the air passage 263, it can exchange heat with the flue gas through the side of the air housing 26 close to the flue gas passage 252, further increasing the temperature of the combustion-supporting air and improving the heat utilization rate.

[0040] As Figure 3 , 8 shown, as one of the preferred embodiments of the present utility model, at least one spoiler plate 264 that cuts off the air passage 263 is provided in the air passage 263. A number of jet holes 265 penetrate through the surface of the spoiler plate 264. The combustion-supporting air in the air passage 263 needs to pass through the spoiler plate 264 before it can flow to the heat exchange passage 251. The combustion-supporting air is intercepted by the spoiler plate 264 and can only be ejected through the jet holes 265. The openings of the jet holes 265 face the inner wall of the air housing 26. After the combustion-supporting air is ejected from the jet holes 265, it can strengthen the disturbance of the combustion-supporting air in the air passage 263, enabling the combustion-supporting air to more efficiently absorb the heat in the air housing 26 and improving the heat exchange efficiency between the combustion-supporting air and the flue gas in the air passage 263.

[0041] As Figure 9 shown, as the second preferred embodiment of the air housing 26 of the present utility model, a number of second heat exchange fins 266 are provided in the air passage 263. The spoiler plate 264 in the air passage 263 can be replaced with the second heat exchange fins 266. The second heat exchange fins 266 contact the combustion-supporting air through a larger specific surface area and extend the flow path of the combustion-supporting air in the air passage 263, enabling the combustion-supporting air to more efficiently absorb the heat in the air housing 26 and improving the heat exchange efficiency between the combustion-supporting air and the flue gas in the air passage 263.

[0042] As Figure 2As shown, as one of the preferred embodiments of the present utility model, a smoke pipe 28 communicating with a flue gas outlet 261 and a flue gas passage 252 respectively is provided in an air housing 26, and an air inlet 262 faces one side of the radial surface of the smoke pipe 28; after adopting the above structure, combustion-supporting air enters an air passage 263 from the air inlet 262 in an eccentric direction, strengthening the disturbance intensity of the combustion-supporting air in the air passage 263, enabling the combustion-supporting air to more efficiently absorb the heat in the air housing 26, so that the surface temperature of the air housing 26 is lower.

[0043] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present utility model, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present utility model.

Claims

1. A double-layer radiant tube heating system suitable for use in a corrosive environment, comprising a heating furnace (1), a gas burner (2), an inner radiant tube (3), and an outer radiant tube (4), characterized in that: The gas burner (2) is arranged on one side of the heating furnace (1), and the gas burner (2) comprises the following structure: an air duct (21), wherein a combustion chamber (22) is arranged at one end of the air duct (21) close to the interior of the heating furnace (1), an ignition electrode (23) and a gas pipe (24) are arranged in the air duct (21), both of which extend to the combustion chamber (22), a heat exchanger (25) is arranged on the outer jacket of the air duct (21), a heat exchange channel (251) is formed between the heat exchanger (25) and the air duct (21), an air shell (26) is arranged on the outer jacket of the heat exchanger (25), a smoke channel (252) is formed between the air shell (26) and the heat exchanger (25), and the air shell (26) is provided with a smoke outlet (261) connected to the smoke channel (252) and an air inlet (262) connected to the heat exchange channel (251); The inner radiation tube (3) is fixedly connected to the air shell (26) and extends into the interior of the heating furnace (1); the end of the inner radiation tube (3) extending therefrom forms a closed end (31); a flame inner tube (32) matching the combustion chamber (22) is provided inside the inner radiation tube (3); a radiation space (33) matching the flue gas channel (252) is formed between the inner radiation tube (3) and the flame inner tube (32); the outer radiation tube (4) is sleeved outside the inner radiation tube (3); a sealed insulating interlayer (41) is formed between the outer radiation tube (4) and the inner radiation tube (3); an atmosphere detector (42) is provided inside the insulating interlayer (41).

2. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1 is characterized in that: A plurality of primary air holes (211) are provided at one end of the air duct (21) away from the combustion chamber (22), and the interior of the air duct (21) is connected to the air inlet (262) through the primary air holes (211).

3. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1, characterized in that: A gas head (241) is provided at one end of the gas pipe (24) close to the combustion chamber (22); the gas head (241) is provided with a plurality of gas holes (242) facing the inner wall of the combustion chamber (22); and a gas groove (243) is provided on the surface of the gas head (241) surrounding the plurality of gas holes (242).

4. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1, characterized in that: A wind disk support (27) is provided in the air duct (21), the wind disk support (27) comprising a spoiler disk (271) arranged along the inner wall of the air duct (21) and a fixed support (272) fixedly connected to the gas pipe (24) and the combustion chamber (22), the wind disk support (27) being located on a side of the combustion chamber (22) away from the flame inner tube (32).

5. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1, characterized in that: The heat exchanger (25) is provided with a plurality of first heat exchange fins (253) extending from the heat exchange channel (251) to the flue gas channel (252).

6. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1, characterized in that: The air housing (26) is hollow inside to form an air channel (263), and two ends of the air channel (263) are respectively connected to the air inlet (262) and the heat exchange channel (251).

7. The double-layer radiant tube heating system suitable for corrosive environments according to claim 6, characterized in that: At least one spoiler (264) is provided in the air passage (263) for cutting off the air passage (263), and a plurality of jet holes (265) are penetrated through the surface of the spoiler (264).

8. The double-layer radiant tube heating system suitable for corrosive environments according to claim 6, characterized in that: A plurality of second heat exchange fins (266) are provided in the air passage (263).

9. The double-layer radiant tube heating system suitable for corrosive environments according to claim 1, characterized in that: A smoke pipe (28) is provided in the air housing (26) and is connected to the smoke outlet (261) and the smoke channel (252) respectively. The air inlet (262) faces one side of the radial surface of the smoke pipe (28).

Images