Backflow ejector assembly and ejection combustion head structure

Abstract

The utility model discloses a backflow ejector assembly which comprises an ejector pipe, an ejector pipe expanding pipe and an ejector inclined pipe, an inlet of the ejector pipe expands outwards and extends to form a backflow cover, an outlet of a fuel gas spraying pipe extends into the backflow cover with a gap, and the gap between the fuel gas spraying pipe and the backflow cover forms a backflow inlet for flue gas to flow back into the ejector pipe; the injection pipe is in butt joint communication with the injection pipe expanding pipe, and an outlet of the injection pipe expanding pipe exceeds an outlet of the air inlet barrel; and the inclined injection pipe obliquely penetrates out of the expanded injection pipe. On one hand, air is jetted out through the air inlet barrel, fuel gas is jetted out through the injection pipe expanding pipe and the injection inclined pipe, and therefore multi-stage flames are formed in a combustion area; on the other hand, the flue gas in the combustion area enters the injection pipe through the backflow inlet and is finally injected to the combustion area for combustion from the injection pipe expansion pipe, and a flue gas backflow internal circulation system is effectively achieved; and the generation and emission of nitrogen oxides are greatly reduced. In addition, the utility model further discloses an ejection combustion head structure with the backflow ejector set.

Description

Technical Field

[0001] This utility model relates to gas burner technology, and more particularly to an ejector structure for a burner capable of flue gas recirculation. Background Technology

[0002] Thermal NOx refers to nitrogen oxides formed by the oxidation of N2 (nitrogen) in the combustion air at high temperatures. The amount of thermal NOx generated is related to flame temperature, oxygen concentration, and residence time in the high-temperature zone, and is not affected by fuel composition. The higher the combustion temperature, the more NOx is generated. In actual combustion, the temperature distribution inside the furnace is not uniform. Even if the average flame temperature is not high, large amounts of NOx are still generated in localized high-temperature areas, playing a decisive role. Most existing burners use diffusion combustion. To ensure complete combustion, burners generally employ a design with good fuel-air mixing. This type of combustion has a high flame temperature and a large high-temperature zone area, which easily generates large amounts of NOx. To address the technical problem of excessively high temperatures in the combustion high-temperature zone leading to large amounts of NOx... Existing technologies have proposed various solutions. For example, Chinese patent publication number "CN101089467A" discloses a low-NOx gas burner. Fuel is injected through multiple inclined branch pipes, and air flows through the inclined groove of the swirl plate. The two mix to form an outward rotating airflow for combustion. Simultaneously, the large-angle combustion chamber front creates a flue gas recirculation, thereby reducing the flame temperature. This approach is beneficial for reducing NOx formation. However, this technology has a very limited NOx reduction effect due to the relatively small amount of flue gas recirculated internally.

[0003] Therefore, there is an urgent need for a structure with a large flue gas recirculation capacity to significantly reduce the generation of nitrogen oxides. Utility Model Content

[0004] The purpose of this invention is to provide a recirculation ejector assembly that can increase the amount of flue gas recirculation within the burner, thereby significantly reducing the generation of nitrogen oxides during combustion.

[0005] Another objective of this invention is to provide an ejector burner structure that has a recirculation ejector assembly that can increase the amount of flue gas recirculation within the burner, thereby significantly reducing the generation of nitrogen oxides during combustion.

[0006] To achieve the above objectives, this utility model provides a recirculation ejector assembly for guiding gas flow to the outlet of the air inlet duct for mixing with air via a gas nozzle. The recirculation ejector assembly includes:

[0007] An ejector tube for connecting gas flow to a gas nozzle has an inlet that expands outward and extends to form a return shroud, which has a trumpet-shaped structure. The outlet of the gas nozzle extends into the return shroud with a gap, and the gap between the two forms a return inlet for flue gas to flow back into the ejector tube.

[0008] The ejector tube expander has a lockable rotatable connection between its outlet and its inlet; the ejector tube expander extends toward the outlet of the air inlet duct, and its outlet exceeds the outlet of the air inlet duct.

[0009] An ejector oblique tube, the diameter of which is smaller than the diameter of the ejector tube expander, the ejector oblique tube includes an inner tube section, the inner tube section being suspended and built into the ejector tube expander, the inner tube section extending towards the outlet direction of the ejector tube expander and bending to form an inclined outer tube section extending out of the ejector tube expander, the outer tube section being inclined towards the outlet direction of the air inlet, the included angle α between the outer tube section and the ejector tube expander being an acute angle;

[0010] A first gas injection channel is formed by a gas nozzle, an ejector, and an ejector expander connected in sequence; a second gas injection channel is formed by a gas nozzle, an ejector, an ejector expander, and an ejector angled pipe connected in sequence.

[0011] Preferably, the central axes of the gas nozzle, ejector pipe, ejector pipe expander and the built-in pipe of the present invention are located on the same straight line.

[0012] Preferably, the present invention further includes a gas nozzle, which is installed at the outlet of the gas nozzle pipe, the end of the gas nozzle extending into the return shroud, and the diameter of the gas nozzle being smaller than the diameter of the gas nozzle pipe.

[0013] Preferably, the end of the gas nozzle of this invention has a frustum-shaped structure.

[0014] Preferably, the present invention also includes a locking bolt, which is engaged with the ejector tube expander. Rotating the locking bolt can lock the ejector tube by pressing against it or release the pressure to release the lock.

[0015] Preferably, the reflux shroud of this invention has a circular cutout for fitting and connecting with the air inlet duct.

[0016] The ejector combustion head structure provided by this utility model includes a gas nozzle for conveying gas and an air inlet for conveying air. The gas nozzle is disposed outside the air inlet. It also includes the aforementioned return ejector assembly. The ejector tubes are evenly distributed around the air inlet. The gas nozzles and the ejector tubes are arranged in a one-to-one correspondence.

[0017] Preferably, the present invention also includes a flame-gathering shroud, which is sleeved on the air inlet duct and adjacent to the outlet of the air inlet duct. A hollow structure is formed between the flame-gathering shroud and the outer wall of the air inlet duct, and the hollow structure forms a flame-stabilizing buffer cavity. The ejector tube expander passes horizontally through the flame-gathering shroud.

[0018] Preferably, the present invention further includes a swirl flame stabilizer disc, which is embedded and fixed inside the outlet of the air inlet duct. The swirl flame stabilizer disc is provided with a plurality of swirl blades, which are arranged at equal intervals and inclined in a counterclockwise or clockwise direction with the center of the swirl flame stabilizer disc as the center. The spacing between adjacent swirl blades forms an air channel for the air in the air inlet duct to be ejected at an angle.

[0019] Preferably, the inclination direction of the external tube section of this invention is consistent with the inclination direction of the swirl blade.

[0020] Compared with the prior art, the present invention’s return ejector assembly and ejector combustion head structure having the assembly have the following beneficial effects when implemented: (1) When implemented, air is ejected through the outlet of the air inlet duct, and gas is ejected through the outlet of the ejector tube expansion tube and the outlet of the ejector inclined tube. The ejected air and gas mix in the area in front of the outlet of the air inlet duct and are ignited to form a combustion zone. It can be seen that the air and gas entering the combustion zone are transported in stages through independent channels, thereby forming a multi-stage flame in the combustion zone. This not only constitutes a stable combustion flame, but also expands the combustion zone, greatly reducing the area of ​​the high-temperature zone in the combustion zone, reducing the flame temperature of the high-temperature zone flame, reducing the generation of nitrogen oxides, and increasing the heating efficiency. (2) Because the outlet of the gas nozzle of this utility model extends into the return shroud with a gap, this gap forms a return inlet for the flue gas to flow back into the injector; therefore, during implementation, due to the high temperature in the combustion zone, the gas pressure will increase, and combined with the injection of gas and air, the flue gas generated in the combustion zone will move towards the return shroud (i.e., against the direction of gas and air injection). When the flue gas moves to the return inlet, the return shroud formed by the inlet of the injector is inserted into the gas nozzle that delivers gas under positive pressure. According to Bernoulli's principle, The open-type recirculation inlet creates a negative pressure; the funnel-shaped recirculation hood further facilitates the formation of a higher negative pressure at the recirculation inlet; therefore, the flue gas moving to the recirculation inlet will be drawn into the injector tube in a recirculation manner and ejected from the outlet of the injector tube expansion tube along with the combustion gas; thus, this invention forms a flue gas recirculation internal circulation system, significantly reducing the generation and emission of nitrogen oxides, enabling the injector burner head structure of this invention to adapt to different working conditions, with a wide range of applications, and a significant effect in reducing the generation and emission of nitrogen oxides. (3) By extending an inclined ejector tube through each ejector tube expander tube and setting the outer tube of the inclined ejector tube inclined towards the outlet of the air inlet tube, the present invention forms an inclined gas injection between the gas directly injected from the outlet of the ejector tube expander tube and the air directly injected from the outlet of the air inlet tube, which further enhances the uniformity of gas and air mixing in the combustion zone, enhances the continuity of the multi-stage flame formed in the combustion zone, effectively avoids the occurrence of flameout, and also reduces the flame temperature in the high-temperature zone, reduces the generation of nitrogen oxides, and increases the heating efficiency. Attached Figure Description

[0021] Figure 1 This is a partial cross-sectional three-dimensional structural schematic diagram of the ejector combustion head structure of this utility model.

[0022] Figure 2 This is a cross-sectional schematic diagram of the ejector combustion head structure of this utility model.

[0023] Figure 3 The structure of the ejector combustion head of this utility model is in Figure 2 A schematic diagram of the left-side view structure from a given perspective.

[0024] Figure 4 This is a schematic diagram of the assembly of the reflux ejector assembly and the gas nozzle of this utility model.

[0025] Figure 5 yes Figure 4 A sectional view along the A-A direction.

[0026] Figure 6 yes Figure 5 A bottom view. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to specific implementation examples and accompanying drawings, and the technical solutions of this utility model will be explained. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below. Embodiments of this utility model will now be described with reference to the accompanying drawings, in which similar element reference numerals represent similar elements.

[0028] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0029] like Figure 1 - Figure 6As shown, the ejector combustion head structure 100 of this utility model includes a recirculation ejector assembly 1 for forming a flue gas recirculation system, a gas nozzle 1a for conveying fuel gas, and an air inlet duct 1b for conveying air. The gas nozzle 1a is disposed outside the air inlet duct 1b. The recirculation ejector assembly 1 is connected to the gas nozzle 1a to guide the fuel gas conveyed by the gas nozzle 1a to the outlet 11b of the air inlet duct 1b for mixing with air. This allows the mixed fuel gas and air to ignite and burn in the area in front of the outlet 11b of the air inlet duct 1b, forming a combustion zone. The following is combined with... Figure 1 - Figure 6 The following is a more detailed description of the reflux ejector assembly 1 and the ejector combustion head structure 100 having the assembly of this utility model:

[0030] like Figure 1 - Figure 6 As shown, the reflux ejector assembly 1 of this utility model includes an ejector tube 2, an ejector tube expander 3, and an ejector tube angled tube 4.

[0031] Continue to combine Figure 1 - Figure 6 As shown, the ejector tube 2 of this invention is used for airflow connection to the gas nozzle 1a. The inlet of the ejector tube 2 expands outward and extends to form a return shroud 21, which has a trumpet-shaped structure. The outlet of the gas nozzle 1a extends into the return shroud 21 with a gap, and the gap between the outlet of the gas nozzle 1a and the return shroud 21 forms a return inlet 22 for flue gas to flow back into the ejector tube 2. By utilizing the characteristic of a large opening and a small inlet in the trumpet-shaped structure, this invention enhances the velocity of flue gas entering the return inlet 22 and also guides the flue gas into the return inlet 22.

[0032] Continue to combine Figure 1 - Figure 6As shown, the outlet of the ejector tube 2 and the inlet of the ejector tube expander 3 are rotatably connected in a lockable manner. Specifically, the inlet of the ejector tube expander 3 is rotatably connected to the outlet of the ejector tube 2. The ejector tube 2 and the ejector tube expander 3 are locked together by a locking bolt 5, which is engaged at the inlet end of the ejector tube expander 3. By rotating the locking bolt 5, the ejector tube 2 can be pressed against it, thereby achieving the docking and locking of the ejector tube 2 and the ejector tube expander 3. When the ejector tube 2 and the ejector tube expander 3 are locked by the locking bolt 5, the pressing force of the locking bolt 5 on the ejector tube 2 can be released by rotating the locking bolt 5 in the opposite direction, thereby achieving relative rotation adjustment of the ejector tube 2 and the ejector tube expander 3 or disassembly of the two. Furthermore, the outlet of ejector tube 2 and the inlet of ejector tube expander tube 3 are rotatably connected by threaded engagement. When the two are rotated to the desired position, the ejector tube 2 and ejector tube expander tube 3 can be locked to the adjusted position by rotating the locking bolt 5. In this invention, the ejector tube expander tube 3 extends towards the outlet 11b of the air inlet duct 1b, and the outlet 31 of the ejector tube expander tube 3 exceeds the outlet 11b of the air inlet duct 1b.

[0033] Continue to combine Figure 1 - Figure 6 As shown, the diameter of the ejector oblique tube 4 of this invention is smaller than the diameter of the ejector tube expander 3. The ejector oblique tube 4 includes an internal tube portion 41, which is suspended and built into the ejector tube expander 3. The internal tube portion 41 extends towards the outlet 31 of the ejector tube expander 3 and is bent to form an inclined external tube portion 42 that extends out of the ejector tube expander 3. The external tube portion 42 of the ejector oblique tube 4 of this invention is inclined towards the outlet 11b of the air inlet duct 1b, and the angle α between the external tube portion 42 and the ejector tube expander 3 is an acute angle.

[0034] Combination Figure 1 - Figure 6 As described above, the gas injector 1a, ejector 2, and ejector tube expander 3, which are connected in sequence by airflow, form a first gas injection channel; the gas injector 1a, ejector 2, ejector tube expander 3, and ejector oblique tube 4, which are connected in sequence by airflow, form a second gas injection channel; the gas delivered from the gas injector 1a to the return ejector assembly 1 is injected into the combustion area through the two-stage channels of the first and second gas injection channels. Specifically, in the ejector burner head structure 100 of this invention, the ejector tubes 2 are evenly distributed around the air inlet duct 1b, and the gas injector 1a and the ejector tubes 2 are arranged in a one-to-one correspondence. Figure 1 - Figure 3In the embodiments described, only an implementation with eight ejector tubes 2 evenly arranged is given. Of course, the number of ejector tubes 2 can also be three, four, five, six, seven, nine, ten, etc. Those skilled in the art can choose the number of ejector tubes 2 according to the actual needs without any creative labor, and will not be elaborated here.

[0035] Continue to combine Figure 1 - Figure 6As shown, the reflux ejector assembly 1 and the ejector combustion head structure 100 with the assembly of this utility model have the following beneficial effects when implemented: (1) When implemented, air is ejected through the outlet 11b of the air inlet duct 1b, and gas is ejected through the outlet 31 of the ejector tube expansion pipe 3 and the outlet 43 of the ejector inclined pipe 4. The ejected air and gas are mixed in the area in front of the outlet 11b of the air inlet duct 1b and ignited to form a combustion area. It can be seen that the air and gas entering the combustion area are transported in stages through independent channels, thereby forming a multi-stage flame in the combustion area. This not only constitutes a stable combustion flame, but also expands the combustion area, which greatly reduces the area of ​​the high-temperature area in the combustion area, reduces the flame temperature of the high-temperature area flame, reduces the generation of nitrogen oxides, and increases the heating efficiency. (2) Since the outlet of the gas nozzle 1a of this invention extends into the return shroud 21 with a gap, the gap forms a return inlet 22 for flue gas to flow back into the injector; therefore, during implementation, due to the high temperature in the combustion zone, the gas pressure will increase, and combined with the injection of gas and air, the flue gas generated in the combustion zone will move towards the return shroud 21 (i.e., against the direction of gas and air injection). When the flue gas moves to the return inlet 22, the return shroud 21 formed by the inlet of the injector 2 is inserted into the gas nozzle 1a which delivers gas under positive pressure. According to Bernoulli's principle... It is known that a negative pressure will be formed outside the open-type return inlet 22; the funnel-shaped return hood 21 is more conducive to forming a higher negative pressure at the return inlet 22; therefore, the flue gas that moves to the return inlet 22 will be drawn into the ejector tube 2 in a return manner and ejected from the outlet 31 of the ejector tube expansion tube 3 along with the combustion gas; thus, this utility model forms a flue gas return internal circulation system, which greatly reduces the generation and emission of nitrogen oxides, and makes the ejector burner head structure of this utility model adaptable to different working conditions, with a wide range of applications, and the effect of reducing the generation and emission of nitrogen oxides is significant. (3) By extending an inclined ejector pipe 4 through each ejector tube expander 3, and the external pipe part 42 of the inclined ejector pipe 4 is inclined toward the outlet 11b of the air inlet duct 1b, the present invention forms an inclined gas injection between the gas directly injected from the outlet 31 of the ejector tube expander 3 and the air directly injected from the outlet 11b of the air inlet duct 1b. This further enhances the uniformity of the gas and air mixing in the combustion zone, strengthens the continuity of the multi-stage flame formed in the combustion zone, effectively avoids the occurrence of flameout, and also reduces the flame temperature in the high-temperature zone, reduces the generation of nitrogen oxides, and increases the heating efficiency.

[0036] like Figure 1 - Figure 3As shown, specifically, the ejector burner head structure 100 of this utility model also includes a flame-gathering hood 6, which is sleeved on the air inlet duct 1b and adjacent to the outlet 11b of the air inlet duct 1b. A hollow structure is formed between the flame-gathering hood 6 and the outer wall of the air inlet duct 1b, forming a flame-stabilizing buffer chamber 61. The ejector tube expander 3 of this utility model passes horizontally through the flame-gathering hood 6. During combustion, when the ejector burner head structure 100 operates in the furnace cavity, due to the limited space of the combustion area, the flame may experience backfire towards the gas nozzle 1a. When the flame in the combustion area backfires towards the gas nozzle 1a, the backfire will enter the flame-stabilizing buffer chamber 61 and be blocked, continuing to radiate heat towards the central area of ​​the combustion zone through thermal radiation. Therefore, this utility model effectively solves the backfire problem through the setting of the flame-gathering hood 6 and the flame-stabilizing buffer chamber 61, while also enhancing the flame stability of the entire flow field in the central area. More specifically, continuing to combine... Figure 1 - Figure 3 As shown, the flame-gathering cover 6 of this utility model has a contraction portion 62 that bends and extends into the flame-stabilizing buffer cavity 61. The contraction portion 62 is provided with a cutout 63 for the ejector tube expander 3. The contraction portion 62 and the cutout 63 can effectively position and limit the ejector tube expander 3, ensuring that it does not tilt in position or angle under high temperature environment, thereby causing flame stability of the entire flow field in the combustion area.

[0037] like Figure 1 - Figure 3As shown, specifically, the ejector burner head structure 100 of this utility model also includes a swirling flame stabilizer 7, which is embedded and fixed in the outlet 11b of the air inlet duct 1b. The swirling flame stabilizer 7 is provided with a plurality of swirling blades 71, which are arranged at equal intervals and inclined in a counterclockwise or clockwise direction with the center of the swirling flame stabilizer 7 as the center. The spacing between adjacent swirling blades 71 forms an air channel 72 for the air inlet duct 1b to be obliquely ejected. This invention features a swirling flame stabilizer 7 and inclined swirling blades 71. Air injected from the air inlet duct 1b into the swirling flame stabilizer 7 is ejected at an angle from the air channel 71. Several inclined air channels 72 form a circular shape, causing the air ejected from the air channels 72 to rotate clockwise or counterclockwise around the center of the swirling flame stabilizer 7. This allows the invention to achieve flame transition, rotation, and diffusion from the inside out, creating a stable swirling flame field within the combustion zone. This swirling flame field acts as a stoker flame, stabilizing the flame in the entire flow field and providing a stable combustion flame, effectively preventing flameout and backfire. More specifically, the inclined direction of the outer tube 42 of the ejector oblique tube 4 is consistent with the inclined direction of the swirling blades 71, ensuring that the combustion gas ejected from the ejector oblique tube 4 and the air ejected from the air channel 72 rotate and mix synchronously in one direction. On the one hand, it makes the air and fuel mixture in the entire combustion zone more uniform, further enhancing the continuity of the multi-stage flame formed in the combustion zone; on the other hand, it makes the flame rotate in the combustion zone, thereby forming a swirling flame field in the combustion zone. The swirling flame field serves as a standby ignition source, further stabilizing the flame stability of the entire flow field and effectively preventing flameout and backfire.

[0038] like Figure 1 - Figure 5 As shown, in order to better achieve the delivery of gas and air and the uniformity of gas and air mixing in the combustion zone, in the reflux ejector assembly 1 and the ejector combustion head structure 100 having the assembly, the central axes of the built-in pipe section 41 of the gas nozzle 1a, ejector pipe 2, ejector pipe expander 3 and ejector oblique pipe 4 are located on the same straight line.

[0039] like Figure 1 , Figure 2 , Figure 4 and Figure 5As shown, in order to improve the injection pressure of the gas nozzle 1a and its ability to connect with the airflow of the return shroud 21, thereby enhancing the negative pressure return capability of the return inlet 22, the return ejector assembly 1 and the ejector combustion head structure 100 having the assembly further include a gas nozzle 8. The gas nozzle 8 is installed at the outlet of the gas nozzle 1a, and its end extends into the return shroud 21. The diameter of the gas nozzle 8 is smaller than the diameter of the gas nozzle 1a. Specifically, the end of the gas nozzle 8 has a frustoconical structure.

[0040] like Figure 1 , Figure 2 , Figure 4 , Figure 5 and Figure 6 As shown, in the reflux ejector assembly 1 and the ejector combustion head structure 100 having the assembly of this utility model, the reflux shroud 21 has a circular cutout 23 for it to fit snugly against the air inlet duct 1b. Through the circular cutout 23 of the reflux shroud 21, the flared structure of the reflux shroud 21, which protrudes relative to the ejector tube 2, can fit snugly against the wall of the air inlet duct 1b, avoiding the ejector tube 2 from being suspended due to the reflux shroud 21 protruding from the ejector tube 2. This simplifies the installation process of the ejector tube 2 and makes the structure reasonable and compact.

[0041] It will be apparent to those skilled in the art that this utility model is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this utility model is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model. No reference numerals in the claims should be construed as limiting the scope of the claims. Furthermore, the embodiments disclosed above are merely preferred embodiments of this utility model and should not be construed as limiting the scope of this utility model. Therefore, equivalent variations made within the scope of the claims of this utility model are still within the scope of this utility model.

Claims

1. A return ejector assembly for guiding gas flow to the outlet of an air intake duct for mixing gas with air by connecting the gas flow to a gas nozzle, characterized in that, The return ejector assembly includes: An ejector tube for connecting gas flow to a gas nozzle has an inlet that expands outward and extends to form a return shroud, which has a trumpet-shaped structure. The outlet of the gas nozzle extends into the return shroud with a gap, and the gap between the two forms a return inlet for flue gas to flow back into the ejector tube. The ejector tube expander has a lockable rotatable connection between its outlet and its inlet; the ejector tube expander extends toward the outlet of the air inlet duct, and its outlet exceeds the outlet of the air inlet duct. An ejector oblique tube, the diameter of which is smaller than the diameter of the ejector tube expander, the ejector oblique tube includes an inner tube section, the inner tube section being suspended and built into the ejector tube expander, the inner tube section extending towards the outlet direction of the ejector tube expander and bending to form an inclined outer tube section extending out of the ejector tube expander, the outer tube section being inclined towards the outlet direction of the air inlet, the included angle α between the outer tube section and the ejector tube expander being an acute angle; A first gas injection channel is formed by a gas nozzle, an ejector, and an ejector expander connected in sequence; a second gas injection channel is formed by a gas nozzle, an ejector, an ejector expander, and an ejector angled pipe connected in sequence.

2. The return ejector assembly as claimed in claim 1, characterized in that, The central axes of the gas nozzle, ejector, ejector expansion tube, and internal tube are located on the same straight line.

3. The return ejector assembly as claimed in claim 1, characterized in that, It also includes a gas nozzle, which is installed at the outlet of the gas nozzle pipe, with the end of the gas nozzle extending into the return shroud, and the diameter of the gas nozzle being smaller than the diameter of the gas nozzle pipe.

4. The reflow ejector assembly as claimed in claim 3, characterized in that, The end of the gas nozzle has a frustum-shaped structure.

5. The return ejector assembly as claimed in claim 1, characterized in that, It also includes a locking bolt, which is engaged with the ejector tube expansion tube. Rotating the locking bolt can lock the ejector tube by pressing against it or release the pressure to release it.

6. The return ejector assembly as claimed in claim 1, characterized in that, The return shroud has a circular cutout for fitting and connecting with the air inlet duct.

7. An ejector combustion head structure, comprising a gas nozzle for conveying fuel gas and an air inlet for conveying air, wherein the gas nozzle is disposed outside the air inlet, characterized in that, It also includes a return ejector assembly as described in any one of claims 1-6, wherein the ejector tubes are evenly distributed around the air inlet duct, and the gas nozzles are arranged in a one-to-one correspondence with the ejector tubes.

8. The ejector combustion head structure as described in claim 7, characterized in that, It also includes a flame-gathering hood, which is fitted onto the air inlet duct and is adjacent to the outlet of the air inlet duct. A hollow structure is formed between the flame-gathering hood and the outer wall of the air inlet duct. The hollow structure forms a flame-stabilizing buffer cavity. The ejector tube expander passes horizontally through the flame-gathering hood.

9. The ejector combustion head structure as described in claim 7, characterized in that, It also includes a swirl flame stabilizer, which is embedded and fixed inside the outlet of the air inlet. The swirl flame stabilizer has a number of swirl blades, which are arranged at equal intervals and inclined in a counterclockwise or clockwise direction with the center of the swirl flame stabilizer as the center. The spacing between adjacent swirl blades forms an air channel for the air in the air inlet to be ejected at an angle.

10. The ejector combustion head structure as described in claim 9, characterized in that, The inclination direction of the external tube is consistent with the inclination direction of the swirl blade.

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