Heat exchanger and high-efficiency low-emission self-preheating burner and working method

Abstract

The present application relates to a kind of heat exchanger and high efficiency low emission self-preheating burner and working method, it is applicable to the industrial furnace of steel, nonferrous, machinery, ceramic etc.Industry.The present application includes inner cylinder and outer boss, the outer boss is set in the outside of inner cylinder, the inner cylinder is provided with cylindrical inner cavity, the both ends of the cylindrical inner cavity are cylindrical inner cavity entrance and cylindrical inner cavity exit respectively, the outer boss is provided with boss cavity, the both ends of the boss cavity are boss cavity entrance and boss cavity exit respectively, the cylindrical inner cavity exit is communicated with boss cavity exit, the sidewall of the inner cylinder is provided with notch, the notch is used to communicate cylindrical inner cavity with boss cavity, the outer boss is composed of boss entrance section, boss middle section and boss exit section, the boss entrance section is set in fan ring structure, the boss middle section is set in spiral structure, the boss exit section is set in shrinkage structure.

Description

Technical Field

[0001] This invention relates to a heat exchanger and a high-efficiency, low-emission self-preheating burner and its working method, applicable to industrial furnaces in industries such as steel, non-ferrous metals, machinery, and ceramics. Background Technology

[0002] As a component of the burner, the heat exchanger plays a role in heat exchange during flue gas flow. Currently, finned heat exchangers are commonly used in the market. The heat exchange path between flue gas and air is short, and the effective area of ​​the heat exchanger is small. For example, the finned heat exchanger disclosed in application number 201721270987.4 "Finned tube heat exchanger for self-preheating low-NOx gas burner", the finned heat exchanger in application number 201720055903.9 "Self-preheating low-NOx gas burner", and the finned heat exchanger in application number 202011161982.4 "Self-preheating burner with graded function" have disadvantages such as low heat exchange efficiency and the use of segmented welded structure, which makes it easy to crack at the weld. Summary of the Invention

[0003] The purpose of this invention is to overcome the above-mentioned deficiencies in the prior art and to provide a heat exchanger, a high-efficiency, low-emission self-preheating burner, and a working method.

[0004] The technical solution adopted by the present invention to solve the above problems is as follows: The heat exchanger is characterized by the following structure: it includes an inner cylinder and an outer boss. The outer boss is located on the outside of the inner cylinder. The inner cylinder has a cylindrical inner cavity, with the two ends of the cylindrical inner cavity being the cylindrical inner cavity inlet and the cylindrical inner cavity outlet, respectively. The outer boss has a boss cavity, with the two ends of the boss cavity being the boss cavity inlet and the boss cavity outlet, respectively. The cylindrical inner cavity outlet is connected to the boss cavity outlet. A notch is provided on the side wall of the inner cylinder to connect the cylindrical inner cavity and the boss cavity. The outer boss is composed of a boss inlet section, a boss middle section, and a boss outlet section. A groove is formed between two adjacent outer bosses, and the number of grooves is equal to the number of outer bosses.

[0005] Furthermore, the entrance section of the boss is arranged in a fan-shaped annular structure, the middle section of the boss is arranged in a spiral structure, and the exit section of the boss is arranged in a contracting structure.

[0006] Furthermore, the number of the outer bosses is n, where n≥3 (preferably n=4, 6, 8), the distance between two adjacent outer bosses located in the middle section of the boss is a, the pitch of the outer boss is c, where c=na, and the helix angle of the outer boss is ψ, where 75°≥ψ≥15°.

[0007] Furthermore, the heat exchanger is a one-piece structure, and the heat exchanger is made of high-temperature alloy or silicon carbide and is 3D printed.

[0008] Furthermore, another technical objective of the present invention is to provide a high-efficiency, low-emission self-preheating burner.

[0009] The above-mentioned technical objective of the present invention is achieved through the following technical solution.

[0010] A high-efficiency, low-emission self-preheating burner includes a shell, an end cap, a gas conduit, and an electrode. The shell is divided into an air chamber and a flue gas chamber by a partition, and has an air inlet and a flue gas outlet. The air inlet and the flue gas outlet are respectively connected to the air chamber and the flue gas chamber. The flue gas chamber is connected to a groove located at the inlet section of the boss. An insulation layer is provided inside the flue gas chamber. A transition flange is provided on the shell. The electrode is disposed on the end cap. The burner is characterized by further including a combustion chamber, a burner core, and a heat exchanger. The transition flange is provided with… A transition conduit is provided, which is connected to the inlet of the cylindrical inner cavity. The air cavity is connected to the inlet of the boss cavity. The heat exchanger is mounted on the shell through a heat exchanger flange. The gas conduit and the combustion chamber are both located inside the inner cylinder, with the combustion chamber located at the outlet of the cylindrical inner cavity. The electrode and the burner core penetrate each other, with one end of both the burner core and the electrode located inside the combustion chamber. The two ends of the gas conduit are the gas conduit inlet end and the gas conduit outlet end, respectively. The gas conduit inlet end is connected to the gas inlet on the end cap, and the gas conduit outlet end is connected to the burner core.

[0011] Furthermore, a triangular support is provided on the gas conduit, and the triangular support is installed on the combustion chamber. The two ends of the combustion chamber are the combustion chamber inlet end and the combustion chamber outlet end, respectively. The burner core is installed at the combustion chamber inlet end, and the combustion chamber outlet end is matched with the outlet of the cylindrical inner cavity.

[0012] Furthermore, the combustion chamber includes a first chamber and a second chamber, with a contraction section between the first chamber and the second chamber; the outer wall of the first chamber is provided with a plurality of spherical protrusions, which cooperate with the inner cylinder; the outer wall of the combustion chamber outlet end is provided with a plurality of strip-shaped protrusions, which cooperate with the cylindrical inner cavity outlet; and the side wall of the second chamber is provided with secondary air holes.

[0013] Furthermore, the burner core is provided with an outer ring air hole, an inner ring air hole, and an air cap.

[0014] Furthermore, the gas cap is provided with an inner cavity, and radial and axial nozzles communicating with the inner cavity, the inner cavity being connected to the outlet end of the gas conduit.

[0015] Furthermore, another technical objective of the present invention is to provide a working method for a high-efficiency, low-emission self-preheating burner.

[0016] The above-mentioned technical objective of the present invention is achieved through the following technical solution.

[0017] A method for operating a high-efficiency, low-emission self-preheating burner, characterized in that: the method is as follows:

[0018] A) When the temperature of the heating space is lower than the fuel ignition point, combustion air enters the air cavity through the air inlet, then enters the boss cavity through the boss cavity inlet. Part of the combustion air passes through the notch, outer ring air hole, and inner ring air hole into the first chamber; the other part of the combustion air is divided into two paths through the boss cavity outlet: one path enters the second chamber through the secondary air hole, and the other path enters the heating space between the strip-shaped protrusion and the cylindrical inner cavity outlet. Gas enters the gas duct inlet through the gas inlet, then enters the inner cavity through the gas duct outlet. Part of the gas enters the first chamber through the radial nozzle. A portion of the combustion air entering the first chamber mixes with a portion of the gas, and then... The electrode is ignited, and the combustion products and another part of the gas ejected from the axial nozzle enter the second chamber. They continue to mix and burn with the air that enters through the secondary air hole. The gas is then injected into the heating space through the combustion chamber outlet and mixes and burns again with the combustion air injected into the heating space between the strip-shaped protrusion and the cylindrical inner cavity outlet, forming a stable flame. At the same time, the high-speed ejected intense flame entrains and mixes with the flue gas in the heating space, further reducing the flame temperature. Meanwhile, the flue gas enters the flue gas cavity through the groove. When the flue gas flows in the groove, it transfers heat to the combustion air flowing in the cavity of the protrusion through the outer protrusion. Finally, the flue gas enters the flue gas cavity and is discharged from the burner through the flue gas outlet.

[0019] B) When the temperature of the heating space is higher than the fuel ignition point, the combustion air enters the air cavity through the air inlet, then enters the boss cavity through the boss cavity inlet. A portion of the combustion air passes through the notch, outer ring air hole, and inner ring air hole into the first chamber, while the other portion is divided into two paths through the boss cavity outlet. One path enters the second chamber through the secondary air hole. Another route enters the heating space between the strip-shaped protrusion and the cylindrical inner cavity outlet. The gas enters the gas duct inlet end through the gas inlet, and then enters the inner cavity through the gas duct outlet end. A portion of the gas enters the first chamber through the radial nozzle and mixes with a portion of the combustion air entering the first chamber. It then enters the second chamber with the gas ejected from the axial nozzle and mixes again with the air entering the second chamber through the secondary air hole. Finally, it is injected into the heating space through the combustion chamber outlet end and mixes again with the combustion air injected into the heating space between the strip-shaped protrusion and the cylindrical inner cavity outlet. Under the action of high temperature, diffusion combustion without obvious flame is formed. At the same time, the flue gas enters the flue gas cavity through the groove. When the flue gas flows in the flue gas cavity, it transfers heat to the combustion air flowing in the cavity of the protrusion through the outer protrusion. Finally, the flue gas enters the flue gas cavity and is discharged from the burner through the flue gas outlet.

[0020] Compared with the prior art, the present invention has the following advantages: the heat exchanger is made of high-temperature alloy or silicon carbide and is 3D printed. Spiral-shaped external protrusions are set on the outside of the heat exchanger, and grooves are formed between adjacent external protrusions. The grooves are also spiral-shaped, allowing flue gas to enter the flue gas cavity through the grooves. When the flue gas flows in the grooves, it transfers heat to the combustion air flowing in the cavity of the external protrusions. Finally, the flue gas enters the flue gas cavity and is discharged from the burner through the flue gas outlet. The heat exchanger has a large effective heat exchange area and a greatly increased heat exchange path, thereby improving the heat exchange efficiency. Attached Figure Description

[0021] Figure 1 This is a three-dimensional structural diagram of a high-efficiency, low-emission self-preheating burner according to an embodiment of the present invention.

[0022] Figure 2 This is a three-dimensional (cross-sectional) structural schematic diagram of the high-efficiency, low-emission self-preheating burner according to an embodiment of the present invention.

[0023] Figure 3 This is a schematic diagram of the main view (section) structure of the high-efficiency, low-emission self-preheating burner according to an embodiment of the present invention.

[0024] Figure 4 This is a schematic diagram of the main structure of a high-efficiency, low-emission self-preheating burner according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram of the main structure of the heat exchanger according to an embodiment of the present invention.

[0026] Figure 6This is a schematic diagram of the front view (cross-sectional) structure of the heat exchanger according to an embodiment of the present invention.

[0027] Figure 7 This is a three-dimensional (cross-sectional) structural schematic diagram of the heat exchanger according to an embodiment of the present invention.

[0028] Figure 8 This is a schematic diagram of the main view (cross-sectional) structure of the combustion chamber according to an embodiment of the present invention.

[0029] Figure 9 This is a right-side structural schematic diagram of the burner core (when y≥z>1) according to an embodiment of the present invention.

[0030] Figure 10 This is a three-dimensional structural schematic diagram of the burner core (when y≥z>1) according to an embodiment of the present invention.

[0031] Figure 11 This is a three-dimensional structural diagram of the burner core (when z=1) according to an embodiment of the present invention.

[0032] Figure 12 This is a schematic diagram of the main structure of the burner core (when y≥z>1) according to an embodiment of the present invention.

[0033] Figure 13 This is a schematic diagram of the main structure of the burner core (when z=1) according to an embodiment of the present invention.

[0034] In the diagram: 1. Shell; 2. Heat exchanger; 3. End cap; 4. Gas conduit; 5. Combustion chamber; 6. Burner core; 7. Triangular support; 8. Electrode.

[0035] 10. Partition layer 11. Insulation layer 12. Transition flange 13.

[0036] Air chamber 101, flue gas chamber 102

[0037] Air inlet 101a, flue gas outlet 102a

[0038] Transition catheter 120

[0039] Inner cylinder 21, outer boss 22, heat exchanger flange 23

[0040] Cylindrical inner cavity 210, cylindrical inner cavity inlet 211, cylindrical inner cavity outlet 212, gap 213,

[0041] Boss cavity 220, boss cavity inlet 221, boss cavity outlet 222, boss inlet section 223, boss middle section 224, boss outlet section 225, groove 226.

[0042] Gas inlet 30

[0043] Gas pipe inlet end 41, gas pipe outlet end 42

[0044] First chamber 501, second chamber 502, contraction section 503

[0045] Combustion chamber inlet end 51, combustion chamber outlet end 52, spherical protrusion 53, strip-shaped protrusion 54, secondary air vent 55

[0046] Outer ring air vent 61, inner ring air vent 62, air cap 63

[0047] The inner cavity is 630, the radial spray hole is 631, the axial spray hole is 632, and the tubular nozzle is 633. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are explanations of the present invention, but the present invention is not limited to the following embodiments.

[0049] Example

[0050] See Figures 1 to 13 As shown in the accompanying drawings, the structures, proportions, sizes, etc., depicted are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness or purpose of the invention, should still fall within the scope of the disclosed technical content. Furthermore, the use of terms such as "upper," "lower," "left," "right," "middle," and "one" in this specification is merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0051] The high-efficiency, low-emission self-preheating burner in this embodiment includes a shell 1, a heat exchanger 2, an end cap 3, a gas conduit 4, a combustion chamber 5, a burner core 6, a triangular support 7, and an electrode 8. The heat exchanger 2 is an integral structure, and the material of the heat exchanger 2 is high-temperature alloy or silicon carbide, and it is 3D printed.

[0052] In this embodiment, the housing 1 is divided into an air cavity 101 and a flue gas cavity 102 by a partition 10, and the housing 1 is provided with an air inlet 101a and a flue gas outlet 102a, which are respectively connected to the air cavity 101 and the flue gas cavity 102.

[0053] The heat exchanger 2 in this embodiment includes an inner cylinder 21 and an outer boss 22. The outer boss 22 is located on the outside of the inner cylinder 21. The inner cylinder 21 has a cylindrical inner cavity 210. The two ends of the cylindrical inner cavity 210 are the cylindrical inner cavity inlet 211 and the cylindrical inner cavity outlet 212, respectively. The outer boss 22 has a boss cavity 220. The two ends of the boss cavity 220 are the boss cavity inlet 221 and the boss cavity outlet 222, respectively. The cylindrical inner cavity outlet 212 communicates with the boss cavity outlet 222. The side wall of the inner cylinder 21 has a notch 213 for communicating with the cylindrical inner cavity 210 and the boss cavity 220. The notch 213 is elongated and the number of notches 213 is w, where w ≥ 3, preferably w is 6.

[0054] In this embodiment, the outer boss 22 is composed of a boss inlet section 223, a boss middle section 224, and a boss outlet section 225. The boss inlet section 223 is arranged in a fan-shaped structure, the boss middle section 224 is arranged in a spiral structure, and the boss outlet section 225 is arranged in a contracting structure.

[0055] In this embodiment, a groove 226 is formed between two adjacent outer protrusions 22, and the number of grooves 226 is equal to the number of outer protrusions 22. The groove 226 located in the entrance section 223 of the protrusion is arranged in a trapezoidal structure, the groove 226 located in the middle section 224 of the protrusion is arranged in a spiral structure, and the groove 226 located in the exit section 225 of the protrusion is arranged in a contracting structure.

[0056] In this embodiment, the number of external protrusions 22 is n, where n≥3 (preferably, n=4, 6, 8). The distance between two adjacent external protrusions 22 located in the middle section 224 of the protrusion is a, the pitch of the external protrusion 22 is c, where c=na, and the helix angle of the external protrusion 22 is ψ, where 75°≥ψ≥15° (e.g., ...). Figure 4 As shown, the same pattern filled in the 6 outer protrusions 22 indicates the same outer protrusion 22. The cross-section of the outer protrusion 22 located in the middle section 224 of the protrusion is set in a rectangular structure. The wall thickness of the outer protrusion 22 is b, where 6mm ≥ b ≥ 3mm. The wall thickness of the protrusion cavity 220 is s, where the value of s is generally in the range of 3 to 7mm.

[0057] In this embodiment, the flue gas cavity 102 is connected to the groove 226 located in the boss inlet section 223. The flue gas cavity 102 is provided with a heat insulation layer 11. The shell 1 is provided with a transition flange 12. The electrode 8 is provided on the end cover 3. The transition flange 12 is provided with a transition conduit 120. The transition conduit 120 is connected to the cylindrical inner cavity inlet 211. The air cavity 101 is connected to the boss cavity inlet 221.

[0058] In this embodiment, the heat exchanger 2 is mounted on the shell 1 via the heat exchanger flange 23. The gas conduit 4 and the combustion chamber 5 are both located inside the inner cylinder 21, and the combustion chamber 5 is located at the cylindrical inner cavity outlet 212. The electrode 8 penetrates the burner core 6, and one end of both the burner core 6 and the electrode 8 is located inside the combustion chamber 5.

[0059] In this embodiment, a triangular bracket 7 is provided on the gas conduit 4. The triangular bracket 7 is provided on the combustion chamber 5. The two ends of the combustion chamber 5 are the combustion chamber inlet end 51 and the combustion chamber outlet end 52, respectively. The two ends of the gas conduit 4 are the gas conduit inlet end 41 and the gas conduit outlet end 42, respectively. The gas conduit inlet end 41 is connected to the gas inlet 30 on the end cap 3. The gas conduit outlet end 42 is connected to the burner core 6. The burner core 6 is provided on the combustion chamber inlet end 51. The combustion chamber outlet end 52 is matched with the cylindrical inner cavity outlet 212.

[0060] In this embodiment, the combustion chamber 5 includes a first chamber 501 and a second chamber 502. A contraction section 503 is provided between the first chamber 501 and the second chamber 502. The maximum diameter of the first chamber 501 is D1, the minimum diameter of the contraction section 503 is D2, the maximum diameter of the second chamber 502 is D3, and the diameter of the combustion chamber outlet end 52 is D4, wherein 3D4≥D1≥2D4, 0.8D1≥D2≥D4, and D1≥D3≥1.5D4. The outer wall of the first chamber 501 is provided with a plurality of spherical protrusions 53, which cooperate with the inner cylinder 21; the outer wall of the combustion chamber outlet end 52 is provided with a plurality of strip-shaped protrusions 54, which cooperate with the cylindrical inner cavity outlet 212; the side wall of the second chamber 502 is provided with secondary air holes 55, the number of secondary air holes 55 is e, where e≥3, and the angle formed by the axis of the secondary air holes 55 and the axis of the combustion chamber 5 is θ, where 75°≥θ≥0°.

[0061] In this embodiment, the burner core 6 is provided with an outer ring air hole 61, an inner ring air hole 62, and an air cap 63. The number of outer ring air holes 61 is m, where m≥8. The m outer ring air holes 61 are arranged in a circular array with a diameter of D. The number of inner ring air holes 62 is x, where x=m / 2-1. The inlet center to outlet center of the outer ring air hole 61 is deflected counterclockwise by an angle β along its circle. The deflection angle refers to the angle formed by the projections of the inlet center and outlet center of the outer ring air hole 61 onto the same plane and the lines connecting them to the center of the air cap 63, where 20°≥β≥0°. The angle between the axis of the inner ring air hole 62 and the axis of the burner core 6 is α, where 30°≥α≥0°.

[0062] In this embodiment, the gas cap 63 is provided with an inner cavity 630, and radial nozzles 631 and axial nozzles 632 communicating with the inner cavity 630. The inner cavity 630 is connected to the outlet end 42 of the gas conduit. The number of radial nozzles 631 is y, where y = m / 2. The number of axial nozzles 632 is z, where y ≥ z ≥ 1. When z = 1, the axis of the axial nozzles 632 coincides with the axis of the gas cap 63. The axial nozzles 632 are connected to the tubular nozzles 633. The inner diameter of the tubular nozzles 633 is d, and the length of the gas cap 63 is l, where D ≥ l ≥ 2d.

[0063] The working method of the high-efficiency, low-emission self-preheating burner in this embodiment is as follows:

[0064] A) When the temperature of the heating space is lower than the fuel ignition point (e.g., natural gas 780℃), combustion air enters the air cavity 101 through the air inlet 101a, and then enters the boss cavity 220 through the boss cavity inlet 221. Part of the combustion air enters the first chamber 501 through the notch 213, the outer ring air hole 61, and the inner ring air hole 62. The other part of the combustion air is divided into two paths through the boss cavity outlet 222. One path enters the second chamber 502 through the secondary air hole 55, and the other path enters the heating space between the strip-shaped protrusion 54 and the cylindrical inner cavity outlet 212. The gas enters the gas duct inlet 41 through the gas inlet 30, and then enters the inner cavity 630 through the gas duct outlet 42. Part of the gas enters the first chamber 501 through the radial nozzle 631. Part of the combustion air entering the first chamber 501 mixes with part of the gas and is ignited by the electrode 8. The combustion products and the other part are ejected through the axial nozzle 632. The combustion gas enters the second chamber 502 and continues to mix and burn with the air entering through the secondary air hole 55. It is then injected into the heating space through the combustion chamber outlet 52 and mixes and burns again with the combustion air injected into the heating space between the strip-shaped protrusion 54 and the cylindrical inner cavity outlet 212, forming a stable flame. At the same time, the high-speed ejected intense flame entrains and mixes with the flue gas in the heating space, further reducing the flame temperature (by providing combustion air and combustion gas in two stages, the oxygen concentration in the combustion chamber 5 is reduced, the combustion time is extended, the combustion intensity in the combustion chamber 5 is reduced, and the combustion products are forced to flow back and dilute, further reducing the flame temperature and achieving low NOx emissions). Meanwhile, the flue gas enters the flue gas cavity 102 through the groove 226. When the flue gas flows in the groove 226, the flue gas transfers heat to the combustion air flowing in the protrusion cavity 220 through the outer protrusion 22. Finally, the flue gas enters the flue gas cavity 102 and is discharged from the burner through the flue gas outlet 102a.

[0065] B) When the temperature of the heating space is higher than the fuel ignition point (e.g., 780°C for natural gas), combustion air enters the air cavity 101 through air inlet 101a, and then enters the boss cavity 220 through boss cavity inlet 221. A portion of the combustion air passes through notch 213, outer annular air hole 61, and inner annular air hole 62 into the first chamber 501. The other portion of the combustion air is divided into two paths through boss cavity outlet 222; one path enters the second chamber 502 through secondary air hole 55. Another route enters the heating space between the strip-shaped protrusion 54 and the cylindrical inner cavity outlet 212; the gas enters the gas duct inlet end 41 through the gas inlet 30, and enters the inner cavity 630 through the gas duct outlet end 42. A portion of the gas enters the first chamber 501 through the radial nozzle 631 and mixes with a portion of the combustion air entering the first chamber 501. It then enters the second chamber 502 with the gas ejected from the axial nozzle 632, and continues to mix with the air entering the second chamber 502 through the secondary air hole 55. Finally, it is ejected through the combustion chamber outlet end 52. The gas enters the heating space and mixes again with the combustion air injected into the heating space between the strip-shaped protrusion 54 and the cylindrical inner cavity outlet 212. Under the action of high temperature, it forms a diffuse combustion without obvious flame (achieving ultra-low NOx emissions through flameless combustion). At the same time, the flue gas enters the flue gas cavity 102 through the groove 226. When the flue gas flows in the flue gas cavity 102, the flue gas transfers heat to the combustion air flowing in the protrusion cavity 220 through the outer protrusion 22. Finally, the flue gas enters the flue gas cavity 102 and is discharged from the burner through the flue gas outlet 102a.

[0066] Furthermore, it should be noted that the specific embodiments described in this specification may differ in the shape and name of their components, etc. The above description is merely illustrative of the structure of the present invention. All equivalent or simple variations made based on the structure, features, and principles described in this patent concept are included within the protection scope of this patent. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to substitute them, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, all of which should fall within the protection scope of this invention.

Claims

1. A high-efficiency low-emission self-preheating burner, comprising a shell (1), an end cover (3), a gas guide pipe (4) and an electrode (8), the shell (1) is divided into an air cavity (101) and a flue gas cavity (102) by a partition (10), and the shell (1) is provided with an air inlet (101a) and a flue gas outlet (102a), the air inlet (101a) and the flue gas outlet (102a) are communicated with the air cavity (101) and the flue gas cavity (102) respectively, the flue gas cavity (102) is communicated with a groove (226) located at a convex table inlet section (223), the flue gas cavity (102) is provided with a heat preservation layer (11), the shell (1) is provided with a transition flange (12), and the electrode (8) is arranged on the end cover (3), characterized in that: It also includes a combustion chamber (5) and a burner core (6), and a heat exchanger (2), a transition flange (12) is provided with a transition conduit (120), the transition conduit (120) is communicated with the cylindrical inner cavity inlet (211), the air cavity (101) is communicated with the boss cavity inlet (221), the heat exchanger (2) is arranged on the shell (1) through the heat exchanger flange (23), the gas conduit (4) and the combustion chamber (5) are arranged in the inner cylinder (21), and the combustion chamber (5) is located in the cylindrical inner cavity outlet (212), the electrode (8) and the burner core (6) are penetrated, and one end of the burner core (6) and the electrode (8) is located in the combustion chamber (5), the two ends of the gas conduit (4) are respectively the gas conduit inlet end (41) and the gas conduit outlet end (42), the gas conduit inlet end (41) is communicated with the gas inlet (30) on the end cover (3), and the gas conduit outlet end (42) is connected with the burner core (6); The heat exchanger (2) includes an inner cylinder (21) and an outer boss (22), the outer boss (22) is arranged outside the inner cylinder (21), the inner cylinder (21) is provided with a cylindrical inner cavity (210), the two ends of the cylindrical inner cavity (210) are respectively a cylindrical inner cavity inlet (211) and a cylindrical inner cavity outlet (212), the outer boss (22) is provided with a boss cavity (220), the two ends of the boss cavity (220) are respectively a boss cavity inlet (221) and a boss cavity outlet (222), the cylindrical inner cavity outlet (212) is communicated with the boss cavity outlet (222), the side wall of the inner cylinder (21) is provided with a notch (213), the notch (213) is used for communicating the cylindrical inner cavity (210) with the boss cavity (220), the outer boss (22) is composed of a boss inlet section (223), a boss middle section (224) and a boss outlet section (225), adjacent two outer bosses (22) form a groove (226), the number of the groove (226) is equal to the number of the outer boss (22); The combustion chamber (5) includes a first chamber (501) and a second chamber (502), a contraction section (503) is arranged between the first chamber (501) and the second chamber (502); the two ends of the combustion chamber (5) are respectively a combustion chamber inlet end (51) and a combustion chamber outlet end (52), the outer wall of the first chamber (501) is provided with a plurality of spherical protrusions (53), the spherical protrusions (53) are matched with the inner cylinder (21); the outer wall of the combustion chamber outlet end (52) is provided with a plurality of strip-shaped protrusions (54), the strip-shaped protrusions (54) are matched with the cylindrical inner cavity outlet (212); the side wall of the second chamber (502) is provided with a secondary air hole (55).

2. The high efficiency low emission self-preheating burner as claimed in claim 1, wherein: The boss inlet section (223) is arranged in a fan ring structure, the boss middle section (224) is arranged in a spiral structure, and the boss outlet section (225) is arranged in a contraction structure.

3. The high efficiency low emission self-preheating burner as claimed in claim 1 wherein: The number of the outer bosses (22) is n, wherein n≥3, the distance between two adjacent outer bosses (22) in the middle section (224) is a, the pitch of the outer bosses (22) is c, wherein c=na, and the helix angle of the outer bosses (22) is ψ, wherein 75°≥ψ≥15°.

4. The high efficiency low emission self-preheating burner as claimed in claim 1, wherein: The heat exchanger is of an integrated structure, and is made of high-temperature alloy or silicon carbide and formed by 3D printing.

5. The high efficiency low emission self-preheating burner as claimed in claim 1 wherein: The gas guide pipe (4) is provided with a triangular support (7), the triangular support (7) is arranged on the combustion chamber (5), the burner core (6) is arranged at the inlet end (51) of the combustion chamber, and the outlet end (52) of the combustion chamber is matched with the cylindrical inner cavity outlet (212).

6. The high efficiency low emission self-preheating burner as claimed in claim 1 wherein: The burner core (6) is provided with an outer ring air hole (61), an inner ring air hole (62) and a gas cap (63).

7. The high efficiency low emission self-preheating burner as claimed in claim 6 wherein: The gas cap (63) is provided with an inner cavity (630), a radial injection hole (631) and an axial injection hole (632) in communication with the inner cavity (630), and the inner cavity (630) is in communication with the outlet end (42) of the gas guide pipe.

8. A method of operating a high efficiency, low emission, self-preheating burner as claimed in any one of claims 1 to 7, characterised by: The working method is as follows: A) when the temperature of the heating space is lower than the ignition point of the fuel, the combustion air enters the air cavity (101) through the air inlet (101a), enters the boss cavity (220) through the boss cavity inlet (221), part of the combustion air enters the first chamber (501) through the gap (213), the outer ring air hole (61) and the inner ring air hole (62), the other part of the combustion air is divided into two paths, one path enters the second chamber (502) through the secondary air hole (55), and the other path enters the heating space between the strip-shaped protrusion (54) and the cylindrical inner cavity outlet (212); the gas enters the gas guide pipe inlet end (41) through the gas inlet (30), enters the inner cavity (630) through the gas guide pipe outlet end (42), part of the gas enters the first chamber (501) through the radial injection hole (631), part of the combustion air entering the first chamber (501) mixes with part of the gas, is ignited by the electrode (8), the combustion products and the other part of the gas sprayed out of the axial injection hole (632) enter the second chamber (502), continue to mix with the air entering through the secondary air hole (55), are sprayed into the heating space through the combustion chamber outlet end (52), are mixed with the combustion air sprayed into the heating space between the strip-shaped protrusion (54) and the cylindrical inner cavity outlet (212) again, form a stable flame, and the high-speed sprayed strong flame mixes with the flue gas in the heating space to further reduce the flame temperature; meanwhile, the flue gas enters the flue gas cavity (102) through the groove (226), and the flue gas flows in the groove (226) and gives heat to the combustion air flowing in the boss cavity (220) through the outer boss (22), and finally the flue gas enters the flue gas cavity (102) and is discharged from the burner through the flue gas outlet (102a). B) When the temperature of the heating space is higher than the ignition point of the fuel, combustion air enters the air cavity (101) through the air inlet (101a), enters the boss cavity (220) through the boss cavity inlet (221), and part of the combustion air enters the first chamber (501) through the gap (213), the outer ring air hole (61), and the inner ring air hole (62). Another part of the combustion air is divided into two routes through the boss cavity outlet (222), one route enters the second chamber (502) through the secondary air hole (55), and the other route enters the heating space between the strip-shaped protrusion (54) and the cylindrical inner cavity outlet (212); fuel gas enters the gas guide inlet end (41) through the gas inlet (30), enters the inner cavity (630) through the gas guide outlet end (42), and part of the fuel gas enters the first chamber (501) through the radial injection hole (631) and mixes with part of the combustion air entering the first chamber (501). The gas ejected from the axial injection hole (632) enters the second chamber (502), and then continues to mix with the air entering the second chamber (502) through the secondary air hole (55), is injected into the heating space through the combustion chamber outlet end (52), and is mixed with the combustion air injected into the heating space between the strip-shaped protrusion (54) and the cylindrical inner cavity outlet (212) and burns again. Under the action of high temperature, diffusion combustion without obvious flame is formed, and at the same time, flue gas enters the flue gas cavity (102) through the groove (226). When the flue gas flows in the flue gas cavity (102), the flue gas gives heat to the combustion air flowing in the boss cavity (220) through the outer boss (22), and finally the flue gas enters the flue gas cavity (102) and is discharged from the burner through the flue gas outlet (102a).

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