Burner and premixed air intake reflow annular combustion chamber

Abstract

The present invention discloses a burner, which includes a cylinder, a support seat, a fuel nozzle and an oil delivery pipe; the support seat is arranged in the middle of the cylinder to divide the cylinder into an upper gas collecting chamber and a lower premixing chamber; a vertical flow guide hole is formed in the middle of the support seat; a circle of oblique flow holes is evenly arranged around the flow guide hole on the support seat; the axis of the oblique flow hole gradually approaches the axis of the vertical flow guide hole from top to bottom; the fuel nozzle is detachably connected to the support seat; the fuel nozzle is inserted into the flow guide hole; an annular atomizing air channel is formed between the outer wall of the fuel nozzle and the wall of the flow guide hole; the annular atomizing air channel connects the upper gas collecting chamber and the lower premixing chamber of the cylinder; the oil delivery pipe is used to connect high-pressure fuel to the fuel nozzle. The present invention also discloses a premixed air intake type reflow annular combustion chamber. The burner of the present invention can eliminate the problem of excessive oil enrichment at the oil outlet of the fuel nozzle, and has a simple structure, and the fuel nozzle is easy to disassemble and maintain.

Description

Technical Field

[0001] The invention relates to a gas turbine, in particular to a burner and a premixed air intake type reflow annular combustion chamber. Background Art

[0002] Modern gas turbines have increasingly stringent requirements for low pollution emissions. In recent years, various advanced low-NOx combustion technologies have been developed in the combustion field. Among them, dry lean premixed combustion is the mainstream low-NOx combustion technology. Its characteristic is that the fuel and air are evenly mixed before the combustion reaction to achieve low flame temperature and eliminate local high temperature areas. The main disadvantage of this technology is that the liquid fuel evaporation and mixing time is long at low power. Although this technology faces unstable combustion problems such as acoustic oscillation and flashback in application, its design concept is also applicable to micro gas turbines.

[0003] For micro gas turbines using centrifugal compressors and radial turbines, the representative combustion chamber structure is the recirculation annular combustion chamber. The main combustion zone of this type of recirculation annular combustion chamber belongs to the single vortex recirculation mode. The burners are usually installed on the outer wall of the flame tube, with 4 to 6 burners, and the fuel is sprayed tangentially. No swirler is set, and the oblique main combustion hole jet is used to assist the swirl. For liquid fuels, due to the presence of a large number of droplet diffusion combustion modes in the main combustion zone, it is not conducive to reducing the flame temperature in the main combustion zone.

[0004] Chinese patent application CN201710661065.4 discloses an oblique jet annular combustion chamber, including a valve chamber, an oblique jet swirl nozzle and annular combustion chamber. During operation, air and fuel enter a plurality of (6 to 24) oblique jet swirl nozzles symmetrically distributed in the circumference through the valve chamber, generating a swirl jet into the annular combustion chamber; the axis of the oblique jet swirl nozzle is at a certain angle to the bottom plane of the annular combustion chamber, so that the airflow entering the combustion chamber has a certain circumferential velocity component, generates circumferential motion in the annular combustion chamber, and enhances the mixing of the circumferential airflow. The oblique jet annular combustion chamber can reduce the uneven distribution of the combustion chamber outlet temperature, increase the residence time in the reaction zone, and improve the ignition reliability, but the structure is not compact. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a burner which can eliminate the problem of excessive oil enrichment at the oil outlet of the fuel nozzle and has a simple structure and the fuel nozzle is easy to disassemble and maintain.

[0006] In order to solve the above technical problems, the present invention provides a burner, which includes a cylinder 30, a support seat 31, a fuel nozzle 32, and an oil pipeline 33;

[0007] The support seat 31 is disposed in the middle of the cylinder 30, dividing the cylinder 30 into an upper gas collecting chamber 303 and a lower premixing chamber 307;

[0008] A vertical flow guide hole is formed in the middle of the support seat 31;

[0009] The support seat 31 is evenly provided with a circle of centripetally distributed oblique flow holes 305 around the flow guide hole; the axis of the oblique flow hole 305 gradually approaches the axis of the vertical flow guide hole from top to bottom;

[0010] The fuel nozzle 32 is detachably connected to the support seat 31;

[0011] The fuel nozzle 32 is inserted into the guide hole; an annular atomizing air channel 311 is formed between the outer wall of the fuel nozzle 32 and the wall of the guide hole;

[0012] The annular atomizing air channel 311 is connected to the upper air collecting chamber 303 and the lower premixing chamber 307 of the cylinder 30;

[0013] The fuel delivery pipe 33 is used to connect the high-pressure fuel to the fuel nozzle 32 .

[0014] Preferably, the fuel nozzle 32 is a pneumatic atomizing fuel nozzle.

[0015] Preferably, the fuel outlet of the fuel nozzle 32 is flush with the bottom surface of the support seat 31 .

[0016] Preferably, the support seat 31 is evenly provided with a circle of vertical straight flow holes 306 surrounding the circle of oblique flow holes 305 .

[0017] Preferably, a circle of premixing holes 308 is evenly arranged on the upper wall of the premixing chamber 307 along the circumferential direction;

[0018] High-pressure air can be sprayed into the premixing chamber 307 of the cylinder 30 through the premixing hole 308 .

[0019] Preferably, the premixing hole 308 is a tangential hole.

[0020] Preferably, the premixing hole 308 is a centripetal inclined hole, and the axis of the premixing hole 308 gradually approaches the axis of the cylinder from top to bottom.

[0021] Preferably, the inner diameter of the premixing chamber 307 of the burner 3 barrel 30 gradually increases from top to bottom.

[0022] Preferably, the inner diameter of the premixing chamber 307 of the burner 3 barrel 30 is the same from top to bottom.

[0023] Preferably, a circle of air inlet holes 304 is evenly arranged on the wall of the air collecting cavity 303 along the circumferential direction;

[0024] High-pressure air can be sprayed into the air collecting cavity 303 of the cylinder 30 through the air inlet hole 304 .

[0025] Preferably, the outer wall of the fuel nozzle 32 is provided with swirl blades;

[0026] The outer wall of the fuel nozzle 32 and the swirl blade cooperate with the guide hole wall of the support seat 31 to form the annular atomizing air channel 311;

[0027] The swirl blades are used to assist the high-pressure air in generating swirl.

[0028] Preferably, a circle of premixing holes 308 is evenly arranged on the upper wall of the premixing chamber 307 along the circumferential direction;

[0029] High-pressure air can be sprayed into the premixing chamber 307 of the cylinder 30 through the premixing hole 308;

[0030] The rotation direction of the swirl vanes on the outer wall of the fuel nozzle 32 is the same as the rotation direction of the airflow generated when the premixing hole 308 is a tangential hole.

[0031] The present invention also provides a premixed air intake type reflow annular combustion chamber including the burner, which also includes an annular flame tube 2;

[0032] A plurality of burners 3 are evenly arranged at the head of the annular flame tube 2 along the circumferential direction to form a burner 3 array;

[0033] The burner 3 passes through the head of the annular flame tube 2, and the outlet at the lower end of the tube body 30 is placed inside the cavity of the annular flame tube 2;

[0034] The inclination angle of each burner center line relative to the center axis of the annular flame tube 2 is greater than 18° and less than 80°.

[0035] Preferably, 3 to 8 burners 3 are evenly arranged at the head of the annular flame tube 2 along the circumferential direction.

[0036] Preferably, a machining gap is left between the lower end of the burner 3 cylinder body 30 and the inner and outer walls of the annular flame tube 2.

[0037] Preferably, the annular flame tube 2 has a divergent cooling hole 203 in the middle of its outer wall, an outer impingement cooling hole 204 in the upper part of its outer wall, and an inner impingement cooling hole 205 in the upper part of its inner wall.

[0038] Preferably, the annular flame tube 2 has an inner mixing hole 206 at the lower portion of the inner wall, and an outer mixing hole 202 at the lower portion of the outer wall.

[0039] Preferably, the premixed air intake type reflow annular combustion chamber further includes an annular casing 1;

[0040] The annular casing 1 is sleeved outside the annular flame tube 2;

[0041] The burner 3 flange is fixed on the inclined step of the head of the annular casing 1 and is fixed by a sealing flange 300 .

[0042] In the burner 3 of the present invention, a part of the high-pressure air entering the upper air collecting chamber 303 is sprayed into the lower premixing chamber 307 through the annular atomizing air channel 311 as auxiliary atomizing air, and another part of the high-pressure air entering the upper air collecting chamber 303 is sprayed into the lower premixing chamber 307 through the oblique flow holes 305, respectively, to strengthen the fuel sprayed from the oil outlet of the atomizing fuel nozzle 32 and to blow off the wall area oil. In the burner 3 of the first embodiment, the high-pressure air sprayed from the oblique flow holes 305 will impact the fuel spray (atomizing cone) near the oil outlet of the fuel nozzle 32, thereby effectively overcoming the disadvantage of excessive oil enrichment at the oil outlet of the fuel nozzle 32. At the same time, the burner also has the advantages of simple structure and easy disassembly and maintenance of the fuel nozzle 32. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0044] Figure 1 is a cross-sectional view of an embodiment of a burner of the present invention;

[0045] Figure 2 is a cross-sectional view of another embodiment of a burner of the present invention;

[0046] Figure 3 is a cross-sectional view of another embodiment of a burner of the present invention;

[0047] Figure 4 This is a schematic diagram of a burner installed in a flame tube in an embodiment of a premixed air intake type reflow annular combustion chamber of the present invention;

[0048] Figure 5 It is a schematic diagram of an annular casing arranged outside an annular flame tube in one embodiment of a premixed air intake reflow annular combustion chamber of the present invention.

[0049] Description of reference numerals in the figures:

[0050] 3 burner; 30 cylinder; 31 support seat; 32 fuel nozzle; 33 oil pipeline; 303 air collecting chamber; 307 premixing chamber; 305 oblique flow hole; 32 fuel nozzle; 31 support seat; 311 annular atomizing air channel; 306 direct current hole; 308 premixing hole; 304 air inlet hole; 2 annular flame tube; 203 divergent cooling hole; 204 external impact cooling hole; 205 internal impact cooling hole; 206 internal mixing hole; 202 external mixing hole; 1 annular casing; 300 sealing flange. DETAILED DESCRIPTION

[0051] The following will be combined with the accompanying drawings to clearly and completely describe the technical solutions in the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0052] Embodiment 1

[0053] like Figure 1 , Figure 2 and Figure 3 As shown, the burner 3 includes a cylinder 30, a support seat 31, a fuel nozzle 32, and an oil delivery pipe 33;

[0054] The support seat 31 is disposed in the middle of the cylinder 30, dividing the cylinder 30 into an upper gas collecting chamber 303 and a lower premixing chamber 307;

[0055] A vertical flow guide hole is formed in the middle of the support seat 31;

[0056] The support seat 31 is evenly provided with a circle of centripetally distributed oblique flow holes 305 around the flow guide hole; the axis of the oblique flow hole 305 gradually approaches the axis of the vertical flow guide hole from top to bottom;

[0057] The fuel nozzle 32 is detachably connected to the support seat 31;

[0058] The fuel nozzle 32 is inserted into the guide hole; an annular atomizing air channel 311 is formed between the outer wall of the fuel nozzle 32 and the wall of the guide hole;

[0059] The annular atomizing air channel 311 is connected to the upper air collecting chamber 303 and the lower premixing chamber 307 of the cylinder 30;

[0060] The fuel delivery pipe 33 is used to connect the high-pressure fuel to the fuel nozzle 32 .

[0061] Preferably, the fuel nozzle 32 is a pneumatic atomizing fuel nozzle.

[0062] Preferably, the fuel outlet of the fuel nozzle 32 is flush with the bottom surface of the support seat 31 .

[0063] In the burner 3 of the first embodiment, a part of the high-pressure air entering the upper air collecting chamber 303 is sprayed into the lower premixing chamber 307 through the annular atomizing air channel 311 as auxiliary atomizing air, and another part of the high-pressure air entering the upper air collecting chamber 303 is sprayed into the lower premixing chamber 307 through the oblique flow holes 305, respectively, to strengthen the fuel sprayed from the oil outlet of the atomizing fuel nozzle 32 and to blow off the oil on the wall. In the burner 3 of the first embodiment, the high-pressure air sprayed from the oblique flow holes 305 will impact the fuel spray (atomizing cone) near the oil outlet of the fuel nozzle 32, thereby effectively overcoming the disadvantage of excessive oil enrichment at the oil outlet of the fuel nozzle 32. At the same time, the burner also has the advantages of simple structure and easy disassembly and maintenance of the fuel nozzle 32.

[0064] Embodiment 2

[0065] Based on the burner 3 of the first embodiment, Figure 2 , Figure 3 As shown, the support seat 31 is evenly provided with a circle of vertical straight flow holes 306 around the circle of oblique flow holes 305 .

[0066] In the burner 3 of the second embodiment, the high-pressure air entering the upper air collecting chamber 303 can be sprayed into the lower premixing chamber 307 through the oblique flow holes 305 and the straight flow holes 306 respectively, so that the high-pressure air can be sprayed into the premixing chamber 307 more evenly, and the fuel spray in the premixing chamber 307 can be evenly distributed.

[0067] Embodiment 3

[0068] Based on the burner 3 of the first embodiment, a circle of premixing holes 308 is evenly arranged on the upper wall of the premixing chamber 307 along the circumferential direction;

[0069] High-pressure air can be sprayed into the premixing chamber 307 of the cylinder 30 through the premixing hole 308 .

[0070] Better, such as Figure 1 , Figure 2 As shown, the premixing hole 308 is a tangential hole. The premixing hole 308 is a tangential hole that can rotate the high-pressure air flow entering the premixing chamber 307 of the barrel 30 to generate a swirl flow, which is mixed with the fuel spray entering the premixing chamber 307, which can promote the evaporation of the fuel spray and strengthen the mixing, improve the uniformity of the fuel distribution at the outlet of the burner 3, and effectively atomize the fuel under various power conditions.

[0071] Better, such as Figure 3 As shown, the premixing hole 308 is a centripetal inclined hole, and the axis of the premixing hole 308 gradually approaches the axis of the cylinder from top to bottom.

[0072] Better, such as Figure 1 As shown, the inner diameter of the premixing chamber 307 of the burner 3 barrel 30 gradually increases from top to bottom.

[0073] Better, such as Figure 2 , Figure 3 As shown, the inner diameter of the premixing chamber 307 of the burner 3 barrel 30 is the same from top to bottom.

[0074] In the burner 3 of the third embodiment, the high-pressure air entering the premixing chamber 307 of the barrel 30 through the premixing hole 308 is mixed with the fuel spray entering the premixing chamber 307, which can promote the evaporation of the spray and strengthen the mixing, thereby improving the uniformity of the fuel distribution at the outlet of the burner 3.

[0075] Embodiment 4

[0076] Based on the burner 3 of the first embodiment, a circle of air inlet holes 304 is evenly arranged on the wall of the gas collecting cavity 303 along the circumferential direction;

[0077] High-pressure air can be sprayed into the air collecting cavity 303 of the cylinder 30 through the air inlet hole 304 .

[0078] In the burner 3 of the fourth embodiment, high-pressure air enters the gas collecting cavity 303 of the cylinder 30 through a plurality of air inlet holes 304 provided on the cylinder wall of the gas collecting cavity 303 .

[0079] Embodiment 5

[0080] Based on the burner 3 of the first embodiment, the outer wall of the fuel nozzle 32 is provided with swirl blades;

[0081] The outer wall of the fuel nozzle 32 and the swirl blade cooperate with the guide hole wall of the support seat 31 to form the annular atomizing air channel 311;

[0082] The swirl blades are used to assist the high-pressure air in generating swirl.

[0083] Preferably, a circle of premixing holes 308 is evenly arranged on the upper wall of the premixing chamber 307 along the circumferential direction;

[0084] High-pressure air can be sprayed into the premixing chamber 307 of the cylinder 30 through the premixing hole 308;

[0085] The rotation direction of the swirl vanes on the outer wall of the fuel nozzle 32 is the same as the rotation direction of the airflow generated when the premixing hole 308 is a tangential hole.

[0086] Embodiment 6

[0087] like Figure 4 As shown, a premixed air intake type reflow annular combustion chamber including any burner 3 of embodiments 1 to 5, which also includes an annular flame tube 2;

[0088] A plurality of burners 3 are evenly arranged at the head of the annular flame tube 2 along the circumferential direction to form a burner 3 array;

[0089] The burner 3 passes through the head of the annular flame tube 2, and the outlet at the lower end of the tube body 30 is placed inside the cavity of the annular flame tube 2;

[0090] The inclination angle of each burner center line relative to the center axis of the annular flame tube 2 is greater than 18° and less than 80°.

[0091] Preferably, 3 to 8 burners 3 are evenly arranged at the head of the annular flame tube 2 along the circumferential direction.

[0092] Preferably, a machining gap is left between the lower end of the burner 3 cylinder body 30 and the inner and outer walls of the annular flame tube 2 to allow a certain amount of deformation of the annular flame tube 2 due to thermal expansion.

[0093] The premixed air intake reflow annular combustion chamber of embodiment six is ​​provided with a plurality of groups of oblique spray burners 3 at the head of the combustion chamber. The burners 3 and the annular flame tube 2 constitute a combustion area. The center line of the outlet of the premixing chamber 307 (the outlet at the lower end of the cylinder) of the burner 3 with a premixing chamber 307 is at a certain angle to the center axis of the combustion chamber. The premixed gas is injected into the combustion zone along the axially inclined rotation injection, providing a stable aerodynamic flow state for the combustion zone, which is beneficial to lowering the flame temperature of the main combustion zone and reducing the generation of pollutants. This structural design type is suitable for engines with small axial size requirements but strict radial size requirements.

[0094] Embodiment 7

[0095] Based on the premixed air intake reflow annular combustion chamber of Example 6, the annular flame tube 2 has a divergent cooling hole 203 in the middle of its outer wall, an outer impingement cooling hole 204 in the upper part of its outer wall, and an inner impingement cooling hole 205 in the upper part of its inner wall.

[0096] In the premixed air intake reflow annular combustion chamber of embodiment seven, the wall cooling methods of the annular flame tube 2 are respectively impingement film cooling and divergence cooling. The cooling air enters the annular flame tube 2 through the impingement cooling holes and the divergence cooling holes, which plays a role in reducing the wall temperature and exhaust temperature of the annular flame tube 2, so as to extend the service life of the annular flame tube 2.

[0097] Embodiment 8

[0098] Based on the premixed air intake reflow annular combustion chamber of the sixth embodiment, the annular flame tube 2 has an inner mixing hole 206 at the lower part of the inner wall and an outer mixing hole 202 at the lower part of the outer wall.

[0099] In the premixed air intake reflow annular combustion chamber of Example 8, all the combustion air enters the burner 3 through the air intake hole 304 and the premixing hole 308 on the burner 3 cylinder body and then enters the annular flame tube 2, and the mixed air enters the annular flame tube 2 through the inner mixing hole 206 on the inner wall of the annular flame tube 2 and the outer mixing hole 202 on the outer wall.

[0100] Embodiment 9

[0101] Based on Example 6, Figure 5 As shown, the premixed air intake type reflow annular combustion chamber further includes an annular casing 1;

[0102] The annular casing 1 is sleeved outside the annular flame tube 2;

[0103] The burner 3 flange is fixed on the inclined step of the head of the annular casing 1 and is fixed by a sealing flange 300 .

[0104] In the premixed air intake type reflow annular combustion chamber of the ninth embodiment, the center line of the outlet of the premixing chamber 307 of the oblique injection burner 3 with the premixing chamber 307 is at a certain angle to the center axis of the combustion chamber, and the premixed air is obliquely injected into the combustion zone along the axial direction, providing a stable aerodynamic flow state for the combustion zone, which is conducive to reducing the flame temperature in the main combustion zone and reducing the generation of pollutants. The remaining air enters the flame tube through the impact cooling hole, the divergent cooling hole and the mixing hole, respectively, to reduce the flame tube wall temperature and the exhaust temperature. This structural design type is suitable for engines with small axial size requirements but strict radial size requirements.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A burner, characterized in that: It comprises a cylinder (30), a support seat (31), a fuel nozzle (32), and an oil delivery pipe (33); The support seat (31) is arranged in the middle of the cylinder (30), dividing the cylinder (30) into an upper gas collecting chamber (303) and a lower premixing chamber (307); The upper wall of the premixing chamber (307) is evenly provided with a circle of premixing holes (308) along the circumferential direction; High-pressure air can be sprayed into the premixing chamber (307) of the barrel (30) through the premixing hole (308); The cylinder wall of the gas collecting cavity (303) is evenly provided with a circle of gas inlet holes (304) along the circumferential direction; High-pressure air can be sprayed into the air collecting cavity (303) of the cylinder (30) through the air inlet hole (304); A vertical flow guide hole is formed in the middle of the support seat (31); The support seat (31) is evenly provided with a circle of centripetally distributed oblique flow holes (305) around the flow guide hole; the axis of the oblique flow hole (305) gradually approaches the axis of the vertical flow guide hole from top to bottom; The fuel nozzle (32) is detachably connected to the support seat (31); The fuel nozzle (32) extends into the guide hole; an annular atomizing air channel (311) is formed between the outer wall of the fuel nozzle (32) and the wall of the guide hole; The annular atomizing air channel (311) is in communication with the upper air collecting chamber (303) and the lower premixing chamber (307) of the barrel (30); The oil delivery pipe (33) is used to connect the high-pressure fuel to the fuel nozzle (32); The support seat (31) is evenly provided with a circle of vertical straight flow holes (306) surrounding the circle of oblique flow holes (305).

2. The burner according to claim 1, characterized in that The fuel nozzle (32) is a pneumatic atomizing fuel nozzle.

3. The burner according to claim 1, characterized in that The premixing hole (308) is a tangential hole; or, The premixing hole (308) is a centripetal inclined hole, and the axis of the premixing hole (308) gradually approaches the axis of the cylinder from top to bottom; The inner diameter of the premixing chamber (307) of the burner (3) barrel (30) gradually increases from top to bottom; or, The inner diameter of the premixing chamber (307) of the burner (3) barrel (30) is the same from top to bottom.

4. The burner according to claim 1, characterized in that The oil outlet of the fuel nozzle (32) is flush with the bottom surface of the support seat (31).

5. The burner according to claim 3, characterized in that The outer wall of the fuel nozzle (32) is provided with swirl blades; The outer wall of the fuel nozzle (32) and the swirl blade cooperate with the guide hole wall of the support seat (31) to form the annular atomizing air channel (311); The swirl blades are used to assist the high-pressure air in generating swirl.

6. The burner according to claim 5, characterized in that The rotation direction of the swirl blades on the outer wall of the fuel nozzle (32) is the same as the rotation direction of the airflow generated when the premixing hole (308) is a tangential hole.

7. A premixed air intake type recirculating annular combustion chamber comprising the burner according to any one of claims 1 to 6, characterized in that: It also includes an annular flame tube (2); A plurality of burners (3) are evenly arranged along the circumferential direction at the head of the annular flame tube (2) to form a burner (3) array; The burner (3) passes through the head of the annular flame tube (2), and the outlet at the lower end of the tube body (30) is placed inside the cavity of the annular flame tube (2); The inclination angle of each burner center line relative to the center axis of the annular flame tube (2) is greater than 18 degrees and less than 80 degrees.

8. The premixed air intake type reflow annular combustion chamber according to claim 7, characterized in that: 3 to 8 burners (3) are evenly arranged along the circumferential direction at the head of the annular flame tube (2); A machining gap is left between the lower end of the burner (3) cylinder (30) and the inner wall and outer wall of the annular flame tube (2); The annular flame tube (2) has a divergent cooling hole (203) in the middle of its outer wall, an outer impingement cooling hole (204) in the upper part of its outer wall, and an inner impingement cooling hole (205) in the upper part of its inner wall; The annular flame tube (2) has an inner mixing hole (206) at the lower portion of its inner wall, and an outer mixing hole (202) at the lower portion of its outer wall; The premixed air intake type reflow annular combustion chamber further comprises an annular casing (1); The annular casing (1) is sleeved outside the annular flame tube (2); The burner (3) flange is fixed on the inclined step of the head of the annular casing (1) and is fixedly connected by a sealing flange (300).

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