Swirling flue gas recirculation gas burner

Abstract

The present invention discloses a swirling flue gas recirculation gas burner, which includes a nozzle, a gas gun central tube, a gas spray gun, an external flue gas entrainment unit, an internal flue gas entrainment unit, a spark plug assembly, and a swirling vane. The external flue gas entrainment unit includes an external flue gas inlet and a baffle wall. An external flue gas circulation chamber is formed between the external flue gas inlet, the baffle wall, the outer wall of the gas spray gun, and the inner wall of the nozzle. The internal flue gas entrainment unit includes an annular baffle wall and an annular plate. An internal flue gas circulation chamber is formed between the annular baffle wall, the annular plate, the inner wall of the gas spray gun, and the outer wall of the gas gun central tube. On the premise of ensuring stable combustion, the present invention achieves an NOx emission of less than 30 mg / Nm<supgt;3< / supgt;, thus meeting the increasingly stringent environmental protection standards.

Description

Technical Field

[0001] The present invention relates to the field of combustion technology. Specifically, the present invention relates to a swirl flue gas recirculation gas burner. Background Art

[0002] A gas fuel burner is a device that burns gas fuel to provide heat or hot flue gas, and is widely used in combustion equipment such as gas boilers and hot blast stoves. The main pollutants after burning of gas fuels such as natural gas, coal gas, cracked gas, pyrolysis gas, etc. are nitrogen oxides and sulfur dioxide. The formation of sulfur dioxide mainly depends on the sulfur content in the fuel, while the formation of nitrogen oxides is closely related to the design of the burner. In recent years, China's environmental protection requirements for combustion equipment have become increasingly strict. Taking gas boilers as an example, Beijing has promulgated the "Emission Standard of Air Pollutants for Boilers" (DB11 / 139 - 2015), requiring that the emission concentration of air pollutants from newly built boilers shall not be higher than 30 mg / Nm 3 (converted to a flue gas O2 concentration of 3.5%). This poses new challenges to the burner technology of gas fuels.

[0003] At present, for the mainstream non-premixed low-nitrogen burner technology without the flue gas recirculation technology, the original emission of nitrogen oxides is generally 70 - 120 mg / Nm 3 , and after using the flue gas recirculation technology, the original emissions of a few burners can reach less than 30 mg / Nm 3 of the nitrogen oxide emission standard. However, when a relatively high proportion of flue gas recirculation is used, due to the reduction of the combustion flame temperature, many burners have problems such as unstable flame, oscillation, and flameout, which bring great risks to the operation of combustion equipment. In addition, some premixed combustion technologies, such as surface combustion, porous media combustion, etc., can achieve nitrogen oxide emissions of less than 30 mg / Nm on the premise of ensuring stable combustion 3 . However, the premixed combustion technology requires that the fuel and air are completely mixed before combustion, and explosion may occur if the operation is improper, bringing great potential safety hazards. On the other hand, in industrial production, it is often necessary to select low calorific value gas, such as coal gas, industrial synthesis gas, cracked gas, etc. as fuel according to local conditions. Due to the low calorific value and low flame temperature of these low calorific value gases, greater problems of stability occur during low-nitrogen combustion. Therefore, there is an urgent need in the market to develop a low-nitrogen burner that can effectively control the formation of nitrogen oxides through swirl combustion and flue gas recirculation combustion technology while ensuring stable combustion. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems in the related art to some extent. For this purpose, the object of the present invention is to provide a swirl flue gas recirculation gas burner, which realizes that the emission of nitrogen oxides is less than 30 mg / Nm 3 , thus meeting the increasingly stringent environmental protection standards.

[0005] The present invention provides a swirl flue gas recirculation gas burner. According to an embodiment of the present invention, the swirl flue gas recirculation gas burner includes:

[0006] a nozzle, the cross-section of the nozzle being annular;

[0007] a gas gun central tube, the gas gun central tube being arranged in the nozzle. The gas gun central tube is an annular chamber. The region between the outer wall of the gas gun central tube and the inner wall of the nozzle forms an outer air flow passage. The region between the inner walls of the gas gun central tube forms a central air flow passage. A first gas spray head is provided on the wall of the gas gun central tube near the combustion end;

[0008] a gas spray gun, the gas spray gun being connected to the gas gun central tube through a branch pipe. The gas spray gun is an annular chamber, and the gas spray gun is arranged between the gas gun central tube and the inner wall of the nozzle. A second gas spray head is provided on the wall of the gas spray gun near the combustion end;

[0009] an outer flue gas injection unit, the outer flue gas injection unit including an outer flue gas inlet and a baffle wall. The outer flue gas inlet is provided on the wall of the nozzle near the combustion end. One end of the baffle wall is connected to the inner wall of the nozzle, and the baffle wall extends along the direction towards the combustion end. An outer flue gas circulation chamber is formed among the outer flue gas inlet, the baffle wall, the outer wall of the gas spray gun, and the inner wall of the nozzle;

[0010] an inner flue gas injection unit, the inner flue gas injection unit including an annular baffle wall and an annular plate. One end of the annular baffle wall is connected to the inner wall of the gas spray gun, and the annular baffle wall extends along the direction towards the combustion end. The annular plate is connected to the inner wall of the gas spray gun through a rib plate, and the annular plate extends along the direction towards the combustion end. An inner flue gas circulation chamber is formed among the annular baffle wall, the annular plate, the inner wall of the gas spray gun, and the outer wall of the gas gun central tube;

[0011] an ignition gun assembly, the ignition gun assembly being arranged in the central air flow passage near the combustion end;

[0012] a swirl vane, the swirl vane being arranged in the central air flow passage near the combustion end, and the swirl vane being connected to the inner wall surface of the gas gun central tube.

[0013] For the swirl flue gas recirculation gas burner according to the above embodiments of the present invention, first, an internal flue gas circulation chamber is formed between the annular baffle wall, the annular plate, the inner wall of the gas spray gun, and the outer wall of the gas gun central tube. Among them, an air flow channel with a throat is formed between the annular baffle wall and the outer wall of the gas gun central tube, and a baffle gap is formed between the annular plate and the inner wall surface of the gas spray gun; when the combustion-supporting air flows through the air flow channel with a throat and the baffle gap, it will accelerate and form a low-pressure area, thereby ejecting the high-temperature flue gas near the nozzle of the gas spray gun to flow through the baffle gap and the air flow channel with a throat in sequence to the outlet end of the gas gun central tube (i.e., the fuel nozzle position of the gas gun central tube), so that the high-temperature flue gas flows through the internal flue gas circulation chamber, mixes with the combustion-supporting air in the internal flue gas circulation chamber, heats the combustion-supporting air, and at the same time reduces the oxygen concentration of the combustion-supporting air, thereby effectively inhibiting the generation of nitrogen oxides and improving the flame stability. Second, an external flue gas circulation chamber is formed between the external flue gas inlet, the baffle wall, the outer wall of the gas spray gun, and the inner wall of the nozzle. Among them, the external flue gas inlet connects the external air flow channel with the furnace outside the nozzle wall surface to suck the external flue gas, and the air flow channel between the baffle wall, the inner wall of the nozzle, and the outer wall surface of the gas spray gun forms a throat; when the combustion-supporting air flows through the throat, the air flow velocity at the throat will increase, and a low-pressure area is also formed, thereby sucking the flue gas in the furnace through the external flue gas inlet to mix with the combustion-supporting air in the external flue gas circulation chamber, diluting the oxygen concentration of the combustion-supporting air, reducing the temperature of the main combustion zone, and reducing the emission of nitrogen oxides. Third, the swirl vanes strengthen the mixing of the central gas and the central combustion-supporting air. Due to the swirling action of the swirl vanes near the gas outlet of the gas gun central tube, the combustion-supporting air and the gas are evenly mixed, enhancing the combustion stability and achieving the effect of stable combustion. Fourth, gas nozzles are respectively arranged on the gas gun central tube and the gas spray gun, which can effectively enhance the connection of the flame between the central flame and the main combustion torch and effectively ensure the combustion stability. Thus, when using natural gas as fuel, while ensuring the boiler output, the mass ratio of the flue gas that can be sucked by the internal flue gas circulation chamber and the external flue gas circulation chamber to the combustion-supporting air is as high as about 0.2:1, which can effectively increase the temperature of the combustion-supporting air and reduce the oxygen concentration of the combustion-supporting air; within the range of 30% - 100% of the boiler load, the combustion is stable without flameout or combustion oscillation; when the external flue gas recirculation (FGR) is not input, the emission of nitrogen oxides is 50 - 60mg / Nm 3 ; when combined with the external flue gas recirculation technology (FGR), when the proportion of flue gas recirculation is higher than 18%, the emission of nitrogen oxides can be controlled within 30mg / Nm 3 or less, and the combustion is stable without flameout.

[0014] In addition, the swirl flue gas recirculation gas burner according to the above embodiments of the present invention may further have the following additional technical features:

[0015] In some embodiments of the present invention, the baffle wall is a trapezoidal baffle wall, and the trapezoidal baffle wall includes an inclined wall surface and a horizontal wall surface.

[0016] In some embodiments of the present invention, the angle α between the inclined wall surface and the wall surface line of the nozzle is 20 to 45°.

[0017] In some embodiments of the present invention, the angle β between the leeward side of the annular baffle wall and the inner wall surface line of the gas burner is 15 to 45°.

[0018] In some embodiments of the present invention, the first gas nozzle includes an outer nozzle and an inner nozzle. The outer nozzle is provided on the outer wall of the central tube of the gas gun, and the inner nozzle is provided on the inner wall of the central tube of the gas gun.

[0019] In some embodiments of the present invention, the outer nozzle and the inner nozzle are provided at relative positions on the central tube of the gas gun, and the outer nozzle and the inner nozzle are evenly distributed along the circumference.

[0020] In some embodiments of the present invention, the second gas nozzle includes side spray holes and inclined spray holes. The side spray holes are provided on the side wall of the gas burner, and the inclined spray holes are provided on the front wall of the gas burner.

[0021] In some embodiments of the present invention, the spraying angle θ of the inclined spray holes is 25 to 45°.

[0022] In some embodiments of the present invention, the angle between the swirl vane and the inner wall surface of the central tube of the gas gun is 30 to 60°.

[0023] In some embodiments of the present invention, the central tube of the gas gun and the gas burner form a concentric annular cavity.

[0024] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a schematic structural diagram of a swirl flue gas recirculation gas burner according to an embodiment of the present invention.

[0027] Figure 2 is a schematic diagram of an external flue gas circulation chamber according to an embodiment of the present invention.

[0028] Figure 3It is a three-dimensional schematic diagram of the baffle wall according to an embodiment of the present invention.

[0029] Figure 4 It is a schematic diagram of the internal flue gas circulation chamber according to an embodiment of the present invention.

[0030] Figure 5 It is a schematic diagram of the gas nozzle of the gas spray gun according to an embodiment of the present invention.

[0031] Figure 6 It is a schematic diagram of the gas nozzle of the central pipe of the gas gun according to an embodiment of the present invention.

[0032] In the figure: 1 - furnace wall; 2 - nozzle; 3 - gas spray gun; 4 - central pipe of gas gun; 5 - ignition gun assembly; 6 - swirl vane; 7 - external flue gas inlet; 8 - baffle wall; 9 - annular baffle wall; 10 - annular plate; 11 - side spray hole; 12 - inclined spray hole; 13 - external nozzle; 14 - internal nozzle; A - external air flow channel; B - central air flow channel; C - external flue gas circulation chamber; D - internal flue gas circulation chamber. Detailed Description of the Invention

[0033] The embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0034] In the description of the present invention, 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", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

[0035] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0036] In the present invention, unless otherwise clearly specified or limited, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the present invention, unless otherwise clearly specified or limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may mean that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0038] The present invention provides a swirl flue gas recirculation gas burner. Referring to the attached Figure 1 , the burner includes: a nozzle 2, a gas gun central pipe 4, a gas spray gun 3, an external flue gas entrainment unit, an internal flue gas entrainment unit, a spark plug assembly 5, and a swirl vane 6. The swirl flue gas recirculation gas burner according to an embodiment of the present invention will be described in detail below.

[0039] In an embodiment of the present invention, referring to the attached Figure 1 , the nozzle 2, the cross-section of the nozzle 2 is annular, the nozzle 2 penetrates through the furnace wall 1 and extends into the furnace, and the rear end of the nozzle 2 is connected to a wind box (not shown in the figure) to supply the air required for combustion.

[0040] In an embodiment of the present invention, referring to the attached Figure 1 , the gas gun central pipe 4, the gas gun central pipe 4 is arranged in the nozzle 2, the gas gun central pipe 4 is an annular chamber, the area between the outer wall of the gas gun central pipe 4 and the inner wall of the nozzle forms an outer air flow channel A, and the area between the inner walls of the gas gun central pipe 4 forms a central air flow channel B. A first gas spray head is provided on the wall of the gas gun central pipe 4 near the combustion end. In an embodiment of the present invention, the specific number of the above first gas spray heads is not particularly limited, and those skilled in the art can set it arbitrarily according to actual needs.

[0041] According to a specific embodiment of the present invention, referring to the attached Figure 6, the first gas spray head includes an outer spray orifice 13 and an inner spray orifice 14. The outer spray orifice 13 is provided on the outer wall of the central pipe 4 of the gas gun, and the inner spray orifice 14 is provided on the inner wall of the central pipe 4 of the gas gun. Thus, the connection between the central flame and the flame of the main combustion torch is further effectively enhanced, and the combustion stability is effectively ensured.

[0042] According to another specific embodiment of the present invention, the outer spray orifice 13 and the inner spray orifice 14 are provided at opposite positions on the central pipe 4 of the gas gun, and the outer spray orifice 13 and the inner spray orifice 14 are evenly distributed along the circumference. Thus, the connection between the central flame and the flame of the main combustion torch is further effectively enhanced, and the combustion stability is effectively ensured.

[0043] In an embodiment of the present invention, refer to the appendix Figure 1 , a gas spray gun 3. The gas spray gun 3 is connected to the central pipe 4 of the gas gun through a branch pipe. The gas spray gun 3 is an annular chamber, and the gas spray gun 3 is provided between the inner wall of the central pipe 4 of the gas gun and the spray orifice. The central pipe 4 of the gas gun and the gas spray gun 3 are concentric annular cavities and penetrate out of the outlet end of the spray orifice into the furnace. A second gas spray head is provided on the wall of the gas spray gun 3 near the combustion end. In an embodiment of the present invention, the specific number of the above-mentioned second gas spray heads is not particularly limited, and those skilled in the art can set it arbitrarily according to actual needs.

[0044] According to another specific embodiment of the present invention, refer to the appendix Figure 5 , the second gas spray head includes a side spray hole 11 and an inclined spray hole 12. The side spray hole 11 is provided on the side wall of the gas spray gun 3, and the inclined spray hole 12 is provided on the front wall of the gas spray gun 3. Thus, the connection between the central flame and the flame of the main combustion torch is further effectively enhanced, and the combustion stability is effectively ensured.

[0045] According to another specific embodiment of the present invention, the spraying angle θ of the inclined spray hole 12 is 25 to 45°. Thus, the connection between the central flame and the flame of the main combustion torch is further effectively enhanced, and the combustion stability is effectively ensured.

[0046] In an embodiment of the present invention, refer to the appendix Figure 1 and 2, an external flue gas entrainment unit, the external flue gas entrainment unit includes an external flue gas inlet 7 and a baffle wall 8, the external flue gas inlet 7 is provided on the wall of the nozzle near the combustion end, one end of the baffle wall 8 is connected to the inner wall of the nozzle, the baffle wall 8 extends along the direction towards the combustion end, and an external flue gas circulation chamber C is formed between the external flue gas inlet 7, the baffle wall 8, the outer wall of the gas burner 3 and the inner wall of the nozzle. Thus, the external flue gas inlet 7 connects the external air flow channel with the furnace outside the nozzle wall surface, sucking in external flue gas, and the air flow channel between the baffle wall 8, the inner wall of the nozzle and the outer wall of the gas burner 3 forms a throat; when the combustion-supporting air flow passes through this throat, the air flow velocity at this throat will increase, also forming a low-pressure area, so as to suck the flue gas in the furnace through the external flue gas inlet 7 and mix it with the combustion-supporting air in the external flue gas circulation chamber C, diluting the oxygen concentration of this combustion-supporting air, reducing the temperature in the main combustion area, and reducing the emission of nitrogen oxides.

[0047] According to another specific embodiment of the present invention, referring to the attached Figure 2 and 3 , the baffle wall 8 is a trapezoidal baffle wall, the trapezoidal baffle wall includes an inclined wall surface and a horizontal wall surface; further, the included angle α between the inclined wall surface and the wall surface line of the nozzle is 20 to 45°. Thus, limiting the included angle α between the inclined wall surface and the wall surface line of the nozzle within the above range is further beneficial to forming an air flow channel with a throat between the baffle wall 8, the inner wall of the nozzle and the outer wall of the gas burner 3, so as to increase the air flow velocity at this throat to form a low-pressure area.

[0048] In the embodiment of the present invention, referring to the attached Figure 1 and 4, an internal flue gas entrainment unit, the internal flue gas entrainment unit includes an annular baffle wall 9 and an annular plate 10. One end of the annular baffle wall 9 is connected to the inner wall of the gas gun 3. The annular baffle wall 9 (with a shape of a frustum thin wall connected to a cylindrical thin wall) extends along the direction towards the combustion end. The annular plate 10 is supported by rib plates and connected to the inner wall of the gas gun 3. The annular plate 10 extends along the direction towards the combustion end. An internal flue gas circulation chamber D is formed between the annular baffle wall 9, the annular plate 10, the inner wall of the gas gun 3, and the outer wall of the gas gun central tube 4. Thus, an air flow passage with a throat is formed between the annular baffle wall 9 and the outer wall of the gas gun central tube 4, and a baffle gap is formed between the annular plate 10 and the inner wall surface of the gas gun 3. When the combustion-supporting air flows through the air flow passage with a throat and the baffle gap, it will accelerate, forming a low-pressure area, thereby entraining the high-temperature flue gas near the nozzle of the gas gun 3 to flow through the baffle gap and the air flow passage with a throat in sequence to the outlet end of the gas gun central tube 4 (i.e., the fuel nozzle position of the gas gun central tube 4). Thus, the high-temperature flue gas flows through the internal flue gas circulation chamber D and mixes with the combustion-supporting air in the internal flue gas circulation chamber D, heating the combustion-supporting air while also reducing the oxygen concentration of the combustion-supporting air, thereby effectively inhibiting the generation of nitrogen oxides and at the same time improving the flame stability.

[0049] According to another specific embodiment of the present invention, the included angle β between the leeward side of the annular baffle wall 9 and the inner wall surface line of the gas gun 3 is 15 - 45°. Thus, by limiting the included angle β between the leeward side of the annular baffle wall 9 and the inner wall surface line of the gas gun 3 within the above range, it is further beneficial to form an air flow passage with a throat between the annular baffle wall 9 and the outer wall of the gas gun central tube 4, thereby increasing the air flow velocity at the throat to form a low-pressure area.

[0050] In an embodiment of the present invention, referring to the attached Figure 1 , an ignition gun assembly 5, the ignition gun assembly 5 is arranged in the central air flow passage near the combustion end. The ignition gun assembly 5 includes an ignition electrode and an ignition gas pipe (not shown in the figure), and the flame monitor functions to detect the flame. At the same time, in the central air flow passage, a corresponding flame detector (not shown in the figure) is also arranged.

[0051] In an embodiment of the present invention, referring to the attached Figure 1 , a swirl vane 6, the swirl vane 6 is arranged in the central air flow passage near the combustion end, and the swirl vane 6 is connected to the inner wall surface of the gas gun central tube 4. Thus, the swirl vane 6 strengthens the mixing of the central gas and the central combustion-supporting air. Due to the swirling action of the swirl vane 6 near the gas outlet of the gas gun central tube 4, the combustion-supporting air and the gas are mixed evenly, enhancing the combustion stability and achieving the effect of stable combustion.

[0052] According to another specific embodiment of the present invention, the included angle between the swirl vane 6 and the inner wall surface of the gas gun central tube 4 is 30 to 60°. Thus, limiting the included angle between the swirl vane 6 and the inner wall surface of the gas gun central tube 4 within the above range is further beneficial for the swirl vane 6 to promote the mixing of the central gas and the central combustion-supporting air.

[0053] In the embodiment of the present invention, gaseous fuel is introduced into the inlet end of the gas gun central tube 4, and a part of the gaseous fuel enters the gas gun 3 through a plurality of circular tubes between the gas spray gun 3 and the gas gun central tube 4. The ignition assembly ignites the gaseous fuel at the outlet end of the gas gun central tube 4 and further ignites the gaseous fuel at the outlet end of the gas gun 3. The central air flow passage between the inner wall surfaces of the annular cavity of the gas gun central tube 4 provides air for the combustion of the central flame, and the excess air coefficient is 1.2 to 1.3. The swirl vane 6 strengthens the mixing of the air and the gaseous fuel.

[0054] According to the swirling flue gas recirculation gas burner of the above embodiments of the present invention, first, an internal flue gas circulation chamber D is formed between the annular baffle wall 9, the annular plate 10, the inner wall of the gas spray gun 3 and the outer wall of the gas gun central tube 4. Among them, an air flow passage with a throat is formed between the annular baffle wall 9 and the outer wall of the gas gun central tube 4, and a baffle gap is formed between the annular plate 10 and the inner wall surface of the gas spray gun 3; when the combustion-supporting air flows through the air flow passage with a throat and the baffle gap, it will accelerate to form a low-pressure area, thereby ejecting the high-temperature flue gas near the nozzle of the gas spray gun 3 to flow through the baffle gap and the air flow passage with a throat in sequence to the outlet end of the gas gun central tube 4 (i.e., the fuel nozzle position of the gas gun central tube 4), so that the high-temperature flue gas flows through the internal flue gas circulation chamber D, mixes with the combustion-supporting air in the internal flue gas circulation chamber D, heats the combustion-supporting air, and at the same time reduces the oxygen concentration of the combustion-supporting air, thereby effectively inhibiting the generation of nitrogen oxides and improving the flame stability. Second, an external flue gas circulation chamber C is formed between the external flue gas inlet 7, the baffle wall 8, the outer wall of the gas spray gun 3 and the inner wall of the nozzle. Among them, the external flue gas inlet 7 connects the external air flow passage to the furnace outside the nozzle wall surface to suck the external flue gas, and the air flow passage between the baffle wall 8, the inner wall of the nozzle and the outer wall surface of the gas spray gun 3 forms a throat; when the combustion-supporting air flows through the throat, the air flow velocity at the throat will increase, and a low-pressure area is also formed, thereby sucking the flue gas in the furnace through the external flue gas inlet 7 to mix with the combustion-supporting air in the external flue gas circulation chamber C, diluting the oxygen concentration of the combustion-supporting air, effectively reducing the temperature of the main combustion zone, and reducing the emission of nitrogen oxides. Third, the swirling vane 6 strengthens the mixing of the central gas and the central combustion-supporting air. Due to the swirling action of the swirling vane 6 near the gas outlet of the gas gun central tube 4, the combustion-supporting air and the gas are evenly mixed, enhancing the combustion stability and achieving the effect of stable combustion. Fourth, gas nozzles are respectively arranged on the gas gun central tube 4 and the gas spray gun 3, which can effectively strengthen the connection of the flame between the central flame and the main combustion torch and effectively ensure the combustion stability.

[0055] Verified by on-site implementation, the present invention can achieve the following performance indicators:

[0056] (1) The mass ratio of the flue gas and the combustion-supporting air that can be sucked by the internal flue gas circulation chamber and the external flue gas circulation chamber can reach 0.2:1, which can effectively increase the temperature of the combustion-supporting air and reduce the oxygen concentration;

[0057] (2) In the range of 30% - 100% of the boiler load, the combustion is stable without flameout or combustion oscillation;

[0058] (3) When the external flue gas recirculation (FGR) is not input, the emission of nitrogen oxides is 50 - 60mg / Nm 3 ;

[0059] (4) When combined with the external flue gas recirculation technology (FGR), when the proportion of flue gas recirculation is higher than 18%, the emission of nitrogen oxides can be controlled below 30 mg / Nm 3 , and the combustion is stable without flameout.

[0060] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0061] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A swirling flue gas recirculation gas burner, characterized in that, Comprising: A nozzle, the cross-section of the nozzle being annular; A central gas gun tube, the central gas gun tube being disposed within the nozzle. The central gas gun tube is an annular chamber. The region between the outer wall of the central gas gun tube and the inner wall of the nozzle forms an outer air flow channel, and the region between the inner walls of the central gas gun tube forms a central air flow channel. A first gas spray head is provided on the wall of the central gas gun tube near the combustion end; the first gas spray head includes an outer spray port and an inner spray port. The outer spray port is disposed on the outer wall of the central gas gun tube, and the inner spray port is disposed on the inner wall of the central gas gun tube; the outer spray port and the inner spray port are disposed at opposite positions on the central gas gun tube, and the outer spray port and the inner spray port are evenly distributed along the circumference; A gas spray gun, the gas spray gun being connected to the central gas gun tube through a branch pipe. The gas spray gun is an annular chamber, and the gas spray gun is disposed between the central gas gun tube and the inner wall of the nozzle. A second gas spray head is provided on the wall of the gas spray gun near the combustion end; the second gas spray head includes a side spray hole and an inclined spray hole. The side spray hole is disposed on the side wall of the gas spray gun, and the inclined spray hole is disposed on the front wall of the gas spray gun; An outer flue gas entrainment unit, the outer flue gas entrainment unit including an outer flue gas inlet and a baffle wall. The outer flue gas inlet is disposed on the wall of the nozzle near the combustion end. One end of the baffle wall is connected to the inner wall of the nozzle, and the baffle wall extends along the direction towards the combustion end. An outer flue gas circulation chamber is formed between the outer flue gas inlet, the baffle wall, the outer wall of the gas spray gun, and the inner wall of the nozzle; An inner flue gas entrainment unit, the inner flue gas entrainment unit including an annular baffle wall and an annular plate. One end of the annular baffle wall is connected to the inner wall of the gas spray gun, and the annular baffle wall extends along the direction towards the combustion end. The annular plate is connected to the inner wall of the gas spray gun through a rib plate, and the annular plate extends along the direction towards the combustion end. An inner flue gas circulation chamber is formed between the annular baffle wall, the annular plate, the inner wall of the gas spray gun, and the outer wall of the central gas gun tube; an air flow channel with a throat is formed between the annular baffle wall and the outer wall of the central gas gun tube, and a baffle gap is formed between the annular plate and the inner wall surface of the gas spray gun. High-temperature flue gas flows through the baffle gap and the air flow channel with a throat in sequence to the outlet end of the central gas gun tube; A spark gun assembly, the spark gun assembly being disposed in the central air flow channel near the combustion end; A swirl vane, the swirl vane being disposed in the central air flow channel near the combustion end, and the swirl vane being connected to the inner wall surface of the central gas gun tube.

2. The swirl flue gas recirculation gas burner according to claim 1, wherein The baffle wall is a trapezoidal baffle wall, and the trapezoidal baffle wall includes an inclined wall surface and a horizontal wall surface.

3. The cyclone flue gas recirculation gas burner according to claim 2, characterized in that, The angle α between the inclined wall surface and the wall line of the nozzle is 20 to 45°.

4. The cyclone flue gas recirculation gas burner according to claim 1, characterized in that, The angle β between the leeward side of the annular baffle wall and the wall line of the inner wall of the gas spray gun is 15 to 45°.

5. The cyclone flue gas recirculation gas burner according to claim 1, characterized in that, The spraying angle θ of the inclined spray hole is 25 to 45°.

6. The cyclone flue gas recirculation gas burner according to claim 1, characterized in that, The included angle between the swirl vane and the inner wall surface of the central pipe of the gas gun is 30 to 60°.

7. The cyclone flue gas recirculation gas burner according to any one of claims 1-6, characterized in that, The central pipe of the gas gun and the gas spray gun form a concentric annular cavity.

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