Low-nitrogen combustor suitable for multiple working conditions

Abstract

The utility model discloses a low-nitrogen burner suitable for multiple working conditions, which mainly comprises a brazier brick, an outer-layer gas gun, a barrel, an air adjusting door, a gas-liquid shunting combined spray gun and the like, the barrel is of a hollow cup-shaped structure and is internally provided with a heat preservation layer, and the brazier brick is a fire-resistant prefabricated part, is provided with a U-shaped notch, is arranged at the top end of the barrel and is used for guiding flame and combustion-supporting air; the outer-layer gas guns are uniformly distributed along a brazier brick and are connected with the gas-liquid split-flow combined spray gun through metal hoses, staged fuel gas is sprayed out to eject flue gas in the furnace, NOx generation is reduced, the gas-liquid split-flow combined spray gun integrates the central liquid guide spray gun and the inner-layer gas guns, gas-liquid fuel is separated and sprayed respectively, and the gas-liquid fuel is mixed with rotational flow combustion-supporting air for combustion, so that the combustion efficiency is improved. The center rotational flow sleeve forms high-speed rotational flow air through the rotational flow pieces, fuel mixing is enhanced, and the incandescent light provides a continuous fire source to guarantee safety. According to the combustor, efficient low-nitrogen emission is achieved through staged combustion, flue gas recirculation and rotational flow combustion-supporting air technologies.

Description

Technical Field

[0001] This utility model relates to the field of petrochemical heating furnace burner technology, specifically a low-NOx burner suitable for multiple operating conditions. Background Technology

[0002] In recent years, in the process of energy conservation and efficiency improvement of heating furnaces, tail gas and waste gas from some refinery units have been sent to petrochemical heating furnaces as fuel gas. The fuel gas contains some non-condensable gases, water or oil, which accumulate in the gas pipeline under low temperature conditions and are carried into the burner, resulting in the problem of fuel gas entrainment. The fuel gas with entrainment is injected into the inside of the fire basin brick and the flame area above it through the nozzle for combustion. Due to poor mixing, the fuel gas entrainment adheres to the inner wall of the fire basin brick and the surface of the nozzle. Under the high temperature radiation of the flame, it will cause coking, black smoke, and reduced combustion efficiency. As the coking becomes more severe, the coke will gradually block the throat of the burner fire basin brick, which will have an adverse effect on flame formation, affect the air supply, and cause the combustion air to deviate, resulting in flame drift. At the same time, the surface temperature of the coke adhering to the fire basin brick is high and the heat dissipation is poor, which will raise the temperature inside the fire basin and affect the flame temperature. This will cause the production of nitrogen oxides to deviate from the low-NOx design conditions.

[0003] Liquid entrainment in fuel gas can also cause fluctuations in the calorific value of fuel gas. At the same pressure, with the nozzle unchanged, the combustion load will increase. In order to meet the load requirements of the heating furnace, when liquid entrainment occurs in fuel gas, it is necessary to reduce the pressure of fuel gas entering the burner, which will cause the fuel gas injection speed to decrease. The liquid droplets are ejected at a low injection speed and fall into the burner cylinder due to gravity before reaching the designated position, causing backfire in the burner and burning out the burner.

[0004] To address the issue of liquid entrainment in fuel gas, factories currently mainly strengthen gas-liquid separators and improve fuel gas pipeline heat tracing. However, for some manufacturers located in northern regions where ambient temperatures are low, handling the liquid entrainment problem is more complicated and the results are not ideal. Utility Model Content

[0005] In view of the above-mentioned shortcomings in the existing technology, the purpose of this utility model is to provide a burner that realizes staged and segmented combustion to control the flame temperature and suppress the large-scale generation of nitrogen oxides.

[0006] The technical solution adopted by this utility model to achieve the above objectives is: a low-NOx burner suitable for multiple working conditions, including a fire pit brick, an outer gas gun, a cylinder, a gas-liquid splitting combined spray gun, and a central swirl sleeve. The cylinder is fixedly connected to the bottom plate of the heating furnace, the top of the cylinder extends into the bottom plate of the heating furnace, and the fire pit brick is fixedly connected to the top of the cylinder.

[0007] A bottom end plate is fixedly connected to the bottom end of the cylinder. Multiple sets of outer gas guns are fixedly connected to the bottom end plate in a circular array. A gas-liquid splitting combined spray gun is fixedly connected to the bottom end plate in the middle area of ​​the multiple sets of outer gas guns. Both the outer gas guns and the gas-liquid splitting combined spray gun are located inside the cylinder. The top of the outer gas gun protrudes from the cylinder and is located on the outer periphery of the fire pit brick.

[0008] The gas-liquid splitting combined spray gun includes a central liquid-guiding spray gun, an inner gas-fueling gun, an annular plate, a gun barrel, a jacketed tube, lugs, and a flange. The gun barrel is fixedly connected to the bottom end plate, and the annular plate is fixedly connected to the top of the gun barrel. The central liquid-guiding spray gun is fixedly connected to the annular plate. A fuel gas passage is provided between the central liquid-guiding spray gun and the gun barrel. Multiple sets of the inner gas-fueling guns are fixedly connected to the gun barrel near its top, and the inner gas-fueling guns communicate with the fuel gas passage. Multiple... The assembly includes a connector that communicates with the fuel gas passage. The bottom end of the gun barrel is fixedly connected to the flange. The flange has a groove in the middle of its inner side and multiple small through holes around the groove. The bottom end of the central liquid-guiding nozzle communicates with the groove. The inner gas gun is located around the inner side of the fire pit brick. The central liquid-guiding nozzle is located at the center of the fire pit brick. The connector is connected to the outer gas gun via a metal hose. The gun barrel is fixedly connected to the jacket tube near its bottom via the support lug.

[0009] The fire pit brick is equipped with a central vortex sleeve, which is sleeved on the central liquid guiding spray gun. The central vortex sleeve is equipped with multiple sets of vortex vanes.

[0010] In the above technical solution, a continuous light component is fixedly connected to the bottom end plate, and the continuous light component is located inside the cylinder.

[0011] In the above technical solution, a square tube is fixedly connected to the cylinder, and the square tube is provided with an air regulating damper structure.

[0012] In the above technical solution, the fire pit brick adopts a hollow cylindrical structure, the middle of the fire pit brick is a combustion air channel, the upper and lower openings of the fire pit brick have the same diameter, the outer periphery of the fire pit brick is provided with multiple sets of U-shaped notches in a ring array, the number of outer gas guns is the same as the number of U-shaped notches, and the outer gas guns are located one by one in the U-shaped notches.

[0013] The fire pit brick includes a frustum portion and a conical portion located on the upper part of the frustum portion, and the frustum portion is fixedly connected to the top surface of the cylinder.

[0014] In the above technical solution, the central swirl sleeve further includes a central sleeve, an air guide tube, a tapered tube, and a flat steel. The central sleeve is provided at the top of the air guide tube, and the air guide tube and the central sleeve are fixedly connected by the swirl vane. The tapered tube is fixedly connected to the bottom of the air guide tube, and the bottom of the tapered tube is fixedly connected to the inner gas gun by the flat steel. The top of the central liquid spray gun penetrates into the central sleeve.

[0015] In the above technical solution, a heat insulation layer is fixedly connected to the inner wall of the cylinder, and the outer gas gun extends through the heat insulation layer.

[0016] In the above technical solution, a mounting ring is fixedly connected to the bottom end of the cylinder, and the bottom end plate is fixedly connected to the mounting ring by bolts.

[0017] The beneficial effects of this utility model are as follows: This structure is equipped with a gas-liquid splitting combined spray gun, which can adapt to the working conditions of liquid inclusion or non-liquid inclusion in the fuel gas, maintain stable combustion, protect the burner from coking and black smoke, ensure complete combustion, high efficiency, and flame formation is not affected by liquid inclusion in the fuel gas; it also controls the flame temperature and suppresses the large-scale generation of nitrogen oxides by using technologies such as fuel gas grading, air grading, and induction of flue gas recirculation combustion in the furnace, thus achieving a low-NOx combustion effect. By setting a central swirl sleeve, the wind speed and air volume in the central swirl sleeve are increased to form a swirl, which is conducive to turbulent mixing with the liquid fuel or fuel gas injected by the central nozzle, making the liquid fuel burn more completely, without black smoke, with low CO concentration and low dust concentration in the flue gas, and a more uniform combustion temperature field in the center of the flame, which is also conducive to suppressing the generation of nitrogen oxides. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 This is a schematic diagram of the gas-liquid splitting combined spray gun structure of this utility model;

[0020] Figure 3 for Figure 1 Detailed structural diagram of part a;

[0021] Figure 4 for Figure 2 Detailed structural diagram of part b in the middle;

[0022] Figure 5 This is a schematic diagram of the structure of the fire pit brick in this utility model;

[0023] Figure 6 This is a schematic diagram of the flange structure in this utility model;

[0024] Figure 7 This is a schematic diagram of the central vortex sleeve in this utility model.

[0025] In the diagram: 100 Fire pit brick, 101 U-shaped notch, 102 Frustum section, 103 Conical section, 200 Outer gas gun, 300 Cylinder body, 301 Bottom end plate, 302 Insulation layer, 303 Mounting ring, 400 Gas-liquid splitting combined spray gun, 401 Central liquid guiding spray gun, 402 Inner gas gun, 403 Ring plate, 404 Gun barrel, 405 Jacketed tube, 406 Support lug, 407 Flange, 408 Fuel gas passage, 408 Connector, 409 Groove, 410 Small through hole, 411 Metal hose, 500 Central swirl sleeve, 501 Swirl vane, 502 Central sleeve, 503 Air guide tube, 504 Conical tube, 505 Flat steel, 600 Constant light component, 701 Square tube, 702 Air damper structure. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figure 1-7 This embodiment provides a low-NOx burner suitable for multiple operating conditions, which is mainly composed of a fire pit brick 100, an outer gas gun 200, a cylinder 300, an air damper, a metal hose 412, a gas-liquid splitting combined spray gun 400, a continuous lamp, a central swirl sleeve 500 and other components.

[0028] Among them, the cylinder 300 is a hollow cup-shaped structure, which serves as the main carrier for the installation of other components. It is fixed to the furnace bottom plate of the heating furnace through the external steel plate flange 407. Its upper part extends into the furnace bottom plate. The outer wall of the cylinder 300 is made of steel plate. In order to prevent the heat of the flame or preheated air from being conducted to the outer wall during operation, an insulation layer 302 is provided inside. The bottom of the cylinder 300 is fixedly connected to the mounting ring 303, and the mounting ring 303 is fixedly connected to the bottom end plate 301 by bolts.

[0029] The bottom end plate 301 is provided with many round holes, and sleeves are welded inside the corresponding round holes. These round holes are the installation positions of the outer gas gun 200 and the night lamp component 600. The heads of these components pass through the corresponding round holes and sleeves, and are installed and fixed to the bottom end plate 301 through the flange 407.

[0030] In addition, a gas-liquid splitting combined spray gun 400 is welded on the bottom end plate 301, and is provided with a viewing hole, ignition hole, and flame detector installation hole. A square tube 701 for combustion air to enter is opened at the bottom of the side wall of the cylinder 300. The square tube 701 is made of welded steel plate and has an internal insulation layer 302. There is a steel plate flange 407 at the inlet of the square tube 701 for connecting with the external air duct. An air regulating damper structure 702 is set inside the square tube 701. The opening of the valve plate is controlled by rotating the external handle, thereby controlling the combustion air volume.

[0031] Furthermore, the fire pit brick 100 is a hollow cylindrical structure, prefabricated with refractory material, with a combustion air channel in the middle. Its upper and lower openings have the same diameter, and its bottom truncated cone is slightly larger. Its circumferential edge has multiple evenly distributed U-shaped notches 101, with a semi-circular hole near the center end and parallel open notches on the outer circumference. The number and position of these U-shaped notches 101 correspond to the number and position of the outer gas guns, and are generally an even number. In this example, there are 8. The fire pit brick 100 includes a truncated cone portion 102 and a conical portion 103 located on the upper part of the truncated cone portion 102. The conical portion 103 gradually narrows from the upper end surface of the truncated cone portion 102 upwards and retains a certain wall thickness. The fire pit brick 100 is installed on the top surface of the cylinder 300. Its upper end surface of the truncated cone portion 102 is generally flush with the furnace bottom plate lining of the heating furnace, while its conical portion 103 is higher than the lining.

[0032] In addition, the outer gas gun 200 is provided in multiple sets (eight in this example), evenly distributed along the outer circumference of the fire pit brick 100, that is, corresponding to the position of the U-shaped notch 101 reserved at the bottom of the fire pit brick 100. In this embodiment, the outer gas gun 200 consists of a gun head and a gun barrel 404. The gun head and gun barrel 404 pass through the bottom end plate 301 at the bottom of the cylinder 300 and the insulation layer 302 inside the side wall, and are installed and fixed on the bottom end plate 301 of the cylinder 300 through the flange 407 welded to the gun barrel 404. A hose connector 409 is welded to the lower part of the gun barrel 404, which is connected to the corresponding hose connector 409 of the gas-liquid splitting combination spray gun 400 through a metal hose 412. In this way, the fuel gas that is not mixed with liquid after splitting enters the gas-liquid splitting combination. Inside the spray gun 400, the fuel gas is delivered to each outer gas gun 200 via the hose connector 409 and the metal hose 412. The outer gas gun 200 nozzle then sprays the fuel gas onto the outer conical surface of the fire pit brick 100 and the flame area above the fire pit brick 100. The fuel gas injected from the nozzle is generally divided into 2-3 stages. One part is sprayed along the outer conical surface of the fire pit brick 100 to the brick opening, while the other part is injected with a portion of the furnace return flue gas (d) and sprayed into the combustion area above the fire pit brick 100. During the injection process, the fuel gas mixes with the furnace return flue gas, which dilutes the fuel gas concentration and heats the fuel gas. Finally, the furnace return flue gas (d) participates in combustion, exhibiting a physical heat absorption process in the flame area, which reduces the flame temperature and effectively suppresses NOx production.

[0033] Furthermore, the gas-liquid splitting combined spray gun 400 is welded together by a central liquid guiding spray gun 401, an inner gas gun 402, an annular plate 403, a gun barrel 404, a connector 409, a jacketed tube 405, a support lug 406, and a flange 407 in a corresponding positional relationship. From top to bottom, the central liquid guiding spray gun 401 passes through the annular plate 403 and is welded to it. The annular plate 403 is welded to the upper opening of the gun barrel 404. A fuel gas passage 408 is set between the gun barrel 404 and the central liquid guiding spray gun 401. The inner gas gun 402 is welded to the upper part of the side wall of the gun barrel 404. The inner gas gun 402 is connected to the fuel gas passage 408. A hose connector 409 is welded to the lower part of its side wall.

[0034] A jacketed tube 405 is installed inside the lower part of the barrel 404. The jacketed tube 405 is welded and fixed inside the barrel 404 by three lugs 406. The bottom end of the barrel 404 is welded to the flange 407. Thus, the barrel 404 forms a closed fuel gas delivery channel 408. That is, the fuel gas (b) enters the lower part of the barrel 404 of the gas-liquid splitting combined spray gun 400 from the small through hole 411 on the flange 407, and under the action of inertial force, the fuel gas... The entrained liquid is sprayed into the jacket formed by the jacket tube 405 and the gun barrel 404. After the liquid collides with the wall, it flows down the wall to the groove 410 on the upper surface of the flange 407. The liquid collected in the groove 410 is sent into the central liquid guiding spray gun 401, which is deep in the groove 410, under the action of the pressure inside the tube. The liquid is sprayed from the nozzle at the top of the central liquid guiding spray gun 401 to the air above the central vortex sleeve 500, where it meets and mixes with the second-stage vortex combustion air and is burned.

[0035] More specifically, the inner gas gun 402 is made of multiple sets (eight in this example), consisting of a gun head, a 90° bend, etc. The gun head is made of high-temperature resistant metal material and has many nozzles. One end of the 90° bend is welded to the upper side wall of the gun barrel 404 of the gas-liquid splitting combined spray gun 400. The welding positions of the multiple gun barrels 404 are evenly distributed along the circumference of the side wall. After splitting, the fuel gas without liquid entrainment goes up from the gun barrel 404 of the gas-liquid splitting combined spray gun 400 and is sent into the inner gas gun 402. The nozzle at the top of the gun gun sprays the fuel gas to the inner wall of the fire pit brick 100, near the brick opening, and above the central swirl sleeve 500, where it mixes and burns with the first-stage combustion air and the second-stage swirl combustion air at the outlet of the central swirl sleeve 500, respectively.

[0036] More specifically, flange 407 is machined from a raised-face circular flange 407 cover, which is a circular plate with a certain thickness. The upper surface of flange 407 is welded to the lower end of the gun barrel 404. The lower surface of flange 407 has a raised face for sealing and bolt holes for installation. It is connected to the heating furnace fuel gas pipeline flange 407 through bolts, nuts and sealing gaskets. The upper surface of the center part of flange 407 is machined with a groove 410. The groove 410 has a slightly larger opening and a certain depth for the separation of liquid fuel gas to converge. Several small circular through holes 411 are evenly distributed near the outer circumference of the groove 410, which are channels for liquid-filled or non-liquid-filled fuel gas to enter the gas-liquid diversion combined spray gun 400.

[0037] More specifically, the central swirl sleeve 500 consists of a central sleeve 502, a swirl vane 501, an air guide tube 503, a cone tube 504, and flat steel 505. The central sleeve 502 covers and limits the central liquid-guiding spray gun. The central sleeve 502 is welded to the inner wall of the upper end of the air guide tube 503 through the swirl vane 501. The lower end of the air guide tube 503 is welded to the small end of the cone tube 504. The large end of the lower end of the cone tube 504 is welded to the 90° bend of the inner gas gun 402 of the gas-liquid splitting combined spray gun 400 through four flat steel 505. Thus, two channels are formed between the central swirl sleeve 500 and the fire basin brick 100, dividing the combustion air into two parts, one of which flows in a ring between the two. The annular gap has one part of the combustion air flowing through the central channel of the central swirl sleeve 500. The cone tube 504 of the central swirl sleeve 500 guides a large amount of combustion air into it. After being rectified by the swirl vane 501, it forms a high-speed swirl, which is beneficial to the mixing and combustion of the second-stage fuel (i.e., liquid fuel or fuel gas) injected by the central liquid-guiding nozzle. The other part of the combustion air flowing vertically upward in the annular gap is rectified by the jacket and flows upward in a laminar flow at a reduced wind speed. It mixes and burns with the first-stage fuel gas in the annular gap, forming a relatively stable flame combustion zone. This provides support for the combustion of liquid fuel in the central part and also provides stable combustion support for the mixing and combustion of the third-stage fuel gas injected by the outer gas nozzle 200.

[0038] Furthermore, the air damper includes components such as a handle, limit pawl, blades, and a rotating shaft, which are installed inside the square tube 701 on the side wall of the cylinder 300 to allow combustion air to enter. By rotating the handle and adjusting the blade opening, the amount of combustion air can be adjusted.

[0039] In addition, the continuous light component 600 is a general component of the burner. Its function is to provide a small flame at all times during the operation of the burner, so as to ensure that there is an open flame in the furnace when the burner of the heating furnace is extinguished in an abnormal situation, so as to prevent a flash explosion safety accident. The continuous light passes through the corresponding round hole on the bottom end plate 301, and the head extends into the inside of the cylinder 300, reaching the bottom of the annular gap between the fire basin brick 100 and the central swirl sleeve 500. It is installed and fixed on the bottom end plate 301 of the cylinder 300 through the flange 407 welded to the gun barrel 404. The tail of the continuous light is a threaded connector 409, which can be connected to the heating furnace continuous light gas (a) pipeline through a hose.

[0040] It will be apparent to those skilled in the art that this invention 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 invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-NOx burner suitable for multiple operating conditions, comprising a fire pit brick (100), an outer gas gun (200), a cylinder (300), a gas-liquid splitting combined spray gun (400), and a central swirl sleeve (500), characterized in that: The cylinder (300) is fixedly connected to the bottom plate of the heating furnace, the top of the cylinder (300) extends into the bottom plate of the heating furnace, and the fire pit brick (100) is fixedly connected to the top of the cylinder (300). The bottom end of the cylinder (300) is fixedly connected to a bottom end plate (301). Multiple sets of the outer gas guns (200) are fixedly connected in a ring array on the bottom end plate (301). The gas-liquid splitting combined spray gun (400) is fixedly connected to the bottom end plate (301) in the middle area of ​​the multiple sets of the outer gas guns (200). The outer gas guns (200) and the gas-liquid splitting combined spray gun (400) are both located inside the cylinder (300). The top of the outer gas gun (200) protrudes from the cylinder (300) and is located on the outer periphery of the fire pit brick (100). The gas-liquid splitting combined spray gun (400) includes a central liquid-guiding spray gun (401), an inner gas gun (402), an annular plate (403), a barrel (404), a jacketed tube (405), a support lug (406), and a flange (407). The barrel (404) is fixedly connected to the bottom end plate (301). The top end of the barrel (404) is fixedly connected to the annular plate (403). The central liquid-guiding spray gun (401) is fixedly connected to the annular plate (403). A fuel gas passage (408) is provided between the central liquid-guiding spray gun (401) and the barrel (404). Multiple sets of the inner gas guns (402) are fixedly connected to the barrel (404) near its top. The inner gas guns (402) communicate with the fuel gas passage (408). Multiple sets of the inner gas guns (402) are fixedly connected to the barrel (404) near its bottom. The assembly connector (409) is connected to the fuel gas passage (408). The bottom end of the gun barrel (404) is fixedly connected to the flange (407). The flange (407) has a groove (410) in the middle of its inner side. The flange (407) has multiple small through holes (411) around the groove (410). The bottom end of the central liquid guide spray gun (401) is connected to the groove (410). The inner gas gun (402) is located around the inner side of the fire pit brick (100). The central liquid guide spray gun (401) is located at the center of the fire pit brick (100). The assembly connector (409) is connected to the outer gas gun (200) through a metal hose (412). The gun barrel (404) is fixedly connected to the jacket tube (405) near its bottom through the support lug (406). The fire pit brick (100) is provided with a central vortex sleeve (500) inside, the central vortex sleeve (500) is sleeved on the central liquid guiding spray gun (401), and the central vortex sleeve (500) is provided with multiple sets of vortex vanes (501).

2. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: A continuous light component (600) is fixedly connected to the bottom end plate (301), and the continuous light component (600) is located inside the cylinder (300).

3. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: A square tube (701) is fixedly connected to the cylinder (300), and an air regulating damper structure (702) is provided on the square tube (701).

4. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: The fire pit brick (100) adopts a hollow cylindrical structure. The middle of the fire pit brick (100) is a combustion air channel. The upper and lower openings of the fire pit brick (100) have the same diameter. The outer periphery of the fire pit brick (100) is provided with multiple sets of U-shaped notches (101) arranged in a ring array. The number of outer gas guns (200) is the same as the number of U-shaped notches (101). The outer gas guns (200) are located one by one in the U-shaped notches (101). The fire pit brick (100) includes a frustum portion (102) and a conical portion (103) located on the upper part of the frustum portion (102), the frustum portion (102) being fixedly connected to the top surface of the cylinder (300).

5. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: The central swirl sleeve (500) also includes a central sleeve (502), an air guide tube (503), a cone tube (504), and a flat steel (505). The central sleeve (502) is provided at the top of the air guide tube (503). The air guide tube (503) and the central sleeve (502) are fixedly connected by the swirl vane (501). The cone tube (504) is fixedly connected to the bottom of the air guide tube (503). The bottom of the cone tube (504) is fixedly connected to the inner gas gun (402) by the flat steel (505). The top of the central liquid spray gun (401) is inserted into the central sleeve (502).

6. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: An insulation layer (302) is fixedly connected to the inner wall of the cylinder (300), and the outer gas gun (200) extends through the insulation layer (302).

7. A low-NOx burner suitable for multiple operating conditions according to claim 1, characterized in that: The bottom end of the cylinder (300) is fixedly connected to an installation ring (303), and the bottom end plate (301) is fixedly connected to the installation ring (303) by bolts.

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