Low nitrogen flame burner and direct-fired heating device for denitration system

Abstract

The present invention is a low-nitrogen flame burner and a direct-fired heating device for a denitration system. The low-nitrogen flame burner includes a burner body structure, a horizontal drive structure, and a vertical drive structure. The burner body structure includes a fixed flue portion and a swinging flue portion. The swinging flue portion can swing horizontally and vertically around the center line of the fixed flue portion. The horizontal drive structure is used to drive the swinging flue portion to swing in a horizontal plane; the vertical drive structure is used to drive the swinging flue portion to swing in a vertical plane. The present invention can realize the function of dynamically adjusting the flame combustion flue gas jet in the horizontal and vertical directions, promote the process requirements of rapid heat exchange between the high-temperature combustion flue gas and the gas in the denitration flue, accurately control the temperature of the mixed flue gas, realize efficient flue gas denitration reaction, and realize ultra-low flue gas emissions.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas denitration, and in particular to a low-nitrogen flame burner for a denitration system and a direct-fired heating device for a denitration system. Background Art

[0002] The control of air pollution is an important part of environmental governance. With the development of industry and the improvement of living standards, people are paying more and more attention to environmental issues and atmospheric environmental protection issues.

[0003] Nitrogen oxides (NOx) are a major type of atmospheric pollutant and one of the main factors in the formation of acid rain, photochemical smog and PM2.5 pollution. At present, industrial sources of NOx emissions in my country account for more than 70% of the total NOx emissions. The control emission technologies of NOx in industrial flue gas mainly include combustion control technology and post-combustion control technology. Combustion control technology includes low-nitrogen combustion technology, reburning technology and flue gas recirculation technology. Among the post-combustion control technologies, selective catalytic reduction (SCR), selective non-catalytic reduction (SNCR) and SCR-SNCR hybrid technology are the main technologies. Considering economic and technical benefits, selective catalytic reduction is the most effective NOx post-control technology.

[0004] The coal combustion process produces a large amount of SO 2 , NOx and other atmospheric pollutants, causing serious air pollution and economic losses. There are various pollutants in the flue gas emitted by thermal power, steel and other industries, which put forward strict requirements on the emission of NOx. The purpose of denitrification is mainly to remove nitric oxide (NO) and nitrogen dioxide (NO 2 ).

[0005] The proportion of nitric oxide (NO) in flue gas to nitrogen oxide (NOx) is very high, often above 90%. Nitric oxide is a polluting gas. When it is directly discharged into the atmosphere, it is easy to pollute the atmosphere, soil and water sources. Therefore, when factories discharge flue gas, especially when the flue gas contains nitric oxide, they need to denitrify the flue gas. Among them, the existing flue gas denitrification technologies are mainly dry and wet. Compared with the wet flue gas denitrification technology, the main advantages of dry flue gas denitrification technology are: low basic investment, simple equipment and process, high efficiency of removing NOx, no wastewater and waste treatment, and not easy to cause secondary pollution.

[0006] The SCR reaction requires the use of a catalyst. Currently, the most widely used is a medium-temperature catalyst with an operating temperature of 320-450°C. Therefore, the reaction temperature of catalytic reduction denitrification should be controlled at 320-450°C. When the reaction temperature is lower than 300°C, a side reaction will occur on the catalyst surface, and ammonia will react with sulfur trioxide and water to generate (NH 4 ) 2SO 4 or NH 4 SO 4 Reduce the reaction with NOx, the product adheres to the catalyst surface, blocks the catalyst channels and micropores, and reduces the catalyst activity. In addition, if the reaction temperature is higher than the applicable temperature of the catalyst, the catalyst channels and micropores will be deformed, thereby deactivating the catalyst. Therefore, ensuring the appropriate reaction temperature is the key to the normal operation of the selective catalyst reduction method. Low boiler load or low atmospheric temperature will cause the SCR inlet temperature to be lower than the catalyst operating temperature. Among them, SCR denitrification requires a temperature window of 300-400℃. NOx is in the catalyst and NH 3 is reduced to N 2 , the denitrification efficiency can reach more than 90%.

[0007] In the denitrification process, the flue gas needs to be heated to a preset temperature before the denitrification process can be carried out efficiently and stably. In the prior art, the flue gas heating is often achieved by setting a heating source below the denitrification flue and allowing the high-temperature gas to rise and mix evenly with the flue gas to achieve the heating purpose. However, since the denitrification system pipelines are generally long in size, heat loss is inevitably caused during the rising process of the high-temperature gas below the mixing layer. At the same time, during the rising process of the high-temperature gas, the axial mixing length with the flue gas is long enough, but the radial mixing surface cannot be guaranteed to be large enough, so the complete and uniform mixing of the high-temperature gas and the flue gas cannot be guaranteed.

[0008] In the steel, metallurgy and coal chemical industries, the exhaust gas temperature of sintering machines and other equipment is relatively low. In order to meet the subsequent denitrification treatment or other process requirements in the SCR equipment, the exhaust gas needs to be heated. There are many ways to heat the flue gas, such as directly adding a heat exchanger, setting up electric heating, etc., which use high-temperature heat sources for heating. These methods require additional heat sources, resulting in high operating costs.

[0009] In addition, since a large amount of blast furnace gas, converter gas, coke oven gas and other fuel gases are usually generated in industrial equipment in the steel, metallurgy and coal chemical industries. Therefore, in the prior art, many companies will use these fuel gases to set up a separate heating furnace outside the flue, and set up one or more blast furnace gas or coke oven gas burners according to the power of the heating furnace. The fuel gas in the burner is burned to produce high-temperature flue gas, and the high-temperature flue gas is sent into the flue through a branch and mixed with the original flue gas in the flue to achieve heating of the original flue gas. Since the above method needs to set up a separate heating furnace outside the flue, on the one hand, the investment cost is relatively high, and on the other hand, after the high-temperature flue gas after the combustion of the fuel gas is mixed with the original flue gas in the flue, the total amount of flue gas in the flue will increase sharply, thereby causing a greater impact on the flue system, and also causing the problem of insufficient output of the existing induced draft fan.

[0010] At present, the environmental protection situation in the steel industry is becoming increasingly severe, and steel companies need to carry out ultra-low emission transformation in steps. The most commonly used technology in steel plants that have implemented low-emission transformation is to build a set of SCR denitrification equipment, and then use the steel plant's own blast furnace gas to heat the flue gas, so as to meet the denitrification inlet flue gas temperature requirements.

[0011] Blast furnace gas is not easy to ignite due to its low calorific value. Generally, an insulated ignition duct with a separate castable is used. Natural gas or light oil gun is used for ignition first. After the temperature in the ignition duct is raised, blast furnace gas is introduced for combustion. Finally, the high-temperature flue gas after combustion is mixed into the denitrification flue to heat the denitrification flue gas. Although blast furnace gas has a low calorific value, it burns in an insulated flue, and the high-temperature flue gas it produces can reach a temperature of 1200-1400°C. During the ignition process, if natural gas or an oil gun is used for ignition, the combustion temperature will be even higher, reaching 1500-1700°C, while the operating temperature of ordinary refractory castables is around 1300°C, which can easily cause the ignition air duct castable to fall off, and then the air duct steel plate will be deformed by high temperature and its life will be shortened; if refractory castables with better performance, such as alumina hollow ball castables, are used, the manufacturing cost will be greatly increased due to their high price; in addition, there is also the prior art that uses a large excess air coefficient to reduce the combustion flue gas temperature, but this method will greatly increase the additional air required for heating, thereby requiring more gas, resulting in poor economic efficiency.

[0012] The flue gas from the sintering machine of the steel plant needs to be denitrated. Traditional denitrification projects heat the flue gas through a heating furnace. The latest technology is to heat the flue gas directly in the flue, which not only saves the amount of flue gas, but also greatly saves engineering costs and plant land. Flue direct-fired burners also have certain technical difficulties:

[0013] 1. The negative pressure in the flue is large, and the burner is not easy to burn stably;

[0014] 2. The flue gas directly in contact with the flame has a higher temperature rise, while the flue gas far from the flame has a lower temperature rise, so the flue gas temperature is uneven;

[0015] 3. The scouring of the flame by the smoke can easily cause the flame to go out;

[0016] 4. The ignition point of combustible gas is high, the inert gas content is high, and it is not easy to burn stably;

[0017] 5. Loud noise is generated when air is taken in.

[0018] Therefore, the inventor, relying on many years of experience and practice in related industries, proposes a low-nitrogen flame burner and a direct-fired heating device for a denitrification system to overcome the defects of the prior art. Summary of the invention

[0019] The purpose of the present invention is to provide a low-nitrogen flame burner and a direct-fired heating device for a denitrification system. The present invention can realize the function of dynamically adjusting the flame combustion flue gas jet in the horizontal and vertical directions, promote the process requirements of rapid heat exchange between the high-temperature combustion flue gas and the gas in the denitrification flue, accurately control the temperature of the mixed flue gas, realize efficient flue gas denitrification reaction, and achieve ultra-low flue gas emissions.

[0020] The objective of the present invention is achieved in this way. A low-nitrogen flame burner comprises a burner body structure, a horizontal drive structure and a vertical drive structure. The burner body structure comprises a fixed flue portion and a swinging flue portion. The swinging flue portion can swing horizontally and vertically around the center line of the fixed flue portion. The horizontal drive structure is used to drive the swinging flue portion to swing in a horizontal plane; the vertical drive structure is used to drive the swinging flue portion to swing in a vertical plane.

[0021] In a preferred embodiment of the present invention, an outer spherical surface is arranged at the first end of the fixed flue portion, the center of the outer spherical surface is located on the center line of the fixed flue portion, and an inner spherical surface is arranged at the first end of the swinging flue portion, and the inner spherical surface can be rotatably mounted on the outer spherical surface.

[0022] In a preferred embodiment of the present invention, the horizontal driving structure includes a first fixed support and a second fixed support which are horizontally arranged, the first end of the first fixed support is fixedly connected to the fixed flue part, the first end of the second fixed support is fixedly connected to the swinging flue part, and a first telescopic cylinder that can rotate around a horizontal axis is hinged between the second end of the first fixed support and the second end of the second fixed support.

[0023] In a preferred embodiment of the present invention, the first telescopic cylinder includes a first cylinder body and a first cylinder rod, the first end of the first cylinder rod is sealed and slidably penetrated into the first cylinder body from the first end of the first cylinder body; a first rotating shaft is rotatably penetrated through the second end of the first fixed support, a first pin is hinged on the first rotating shaft, the center line of the first pin is vertically arranged, and the first pin is hinged to the second end of the first cylinder body; a second rotating shaft is rotatably penetrated through the second end of the second fixed support, a second pin is hinged on the second rotating shaft, the center line of the second pin is vertically arranged, and the second pin is hinged to the second end of the first cylinder rod.

[0024] In a preferred embodiment of the present invention, the vertical drive structure includes a third fixed support and a fourth fixed support which are vertically arranged, the first end of the third fixed support is fixedly connected to the fixed flue portion, the first end of the fourth fixed support is fixedly connected to the swinging flue portion, and a second telescopic cylinder that can rotate around a vertical axis is hinged between the second end of the third fixed support and the second end of the fourth fixed support.

[0025] In a preferred embodiment of the present invention, the second telescopic cylinder includes a second cylinder body and a second cylinder rod, and the first end of the second cylinder rod is sealed and slidably penetrated into the second cylinder body from the first end of the second cylinder body; the second end of the third fixed support is rotatably penetrated by a third rotating shaft, a third pin is hinged on the third rotating shaft, the center line of the third pin is horizontally arranged, and the third pin is hinged to the second end of the second cylinder body; the second end of the fourth fixed support is rotatably penetrated by a fourth rotating shaft, a fourth pin is hinged on the fourth rotating shaft, the center line of the fourth pin is horizontally arranged, and the fourth pin is hinged to the second end of the second cylinder rod.

[0026] In a preferred embodiment of the present invention, the swinging flue section includes a stable combustion flue pipe, and an outlet pipe with a reduced diameter is arranged at one end of the stable combustion flue pipe away from the fixed flue section; the second fixed support and the fourth fixed support are fixedly connected to the outer wall of the stable combustion flue pipe.

[0027] In a preferred embodiment of the present invention, the flame-stabilizing flue pipe includes a flame-stabilizing inner tube and a flame-stabilizing outer tube that are coaxially and radially spaced apart, the cross-section of the flame-stabilizing inner tube is a closed contour formed by splicing multiple circular arcs, the cross-section of the flame-stabilizing outer tube is a circle, and a flame-stabilizing annular space is formed between the flame-stabilizing inner tube and the flame-stabilizing outer tube, and the flame-stabilizing annular space is filled with a refractory castable material unit.

[0028] In a preferred embodiment of the present invention, an annular groove structure is provided on the outer spherical surface, and a first elastic sealing ring is provided in the annular groove structure.

[0029] In a preferred embodiment of the present invention, the horizontal driving structure drives the swinging flue portion to swing in the horizontal plane at an angle range of -30° to 30°; the vertical driving structure drives the swinging flue portion to swing in the vertical plane at an angle range of -30° to 30°.

[0030] In a preferred embodiment of the present invention, the inner cavity of the fixed flue portion and the inner cavity of the swinging flue portion are connected to form a combustion mixing chamber, and an auxiliary combustion chamber and a gas chamber are connected at one end of the fixed flue portion away from the swinging flue portion. An ejector is inserted through the gas chamber and the auxiliary combustion chamber. The ejector is coaxially arranged with the fixed flue portion. The ejector is used to accelerate the combustible gas in the gas chamber and inject it into the combustion mixing chamber. A necked ejection channel is formed between the auxiliary combustion chamber and the combustion mixing chamber, and the auxiliary combustion gas in the auxiliary combustion chamber is ejected into the combustion mixing chamber through the ejection channel; an igniter, a flame detector and a temperature detector are arranged in the combustion mixing chamber.

[0031] In a preferred embodiment of the present invention, the ejector includes a straight pipe section, a contraction section, a throat section, an expansion section and a straightening section, the straight pipe section is located in the fuel gas chamber, and the contraction section, the throat section, the expansion section and the straightening section are located in the combustion-supporting gas chamber; an air inlet is provided at the first end of the straight pipe section, the second end of the straight pipe section is connected to the first end of the contraction section, the diameter of the contraction section is gradually contracted from the first end to the second end, the second end of the contraction section is connected to the first end of the throat section, the second end of the throat section is connected to the first end of the expansion section, the diameter of the expansion section is gradually expanded from the first end to the second end, the second end of the expansion section is connected to the first end of the straightening section, and the second end of the straightening section is provided with an air outlet.

[0032] In a preferred embodiment of the present invention, a first flange is sleeved on the side wall of the swinging flue portion, one end of the bellows is connected to the first flange, the other end of the bellows is connected to the second flange, the second flange is used for sealing connection with the side wall of the denitrification flue, and the first flange, the bellows and the second flange constitute an elastic connection sealing cover of the burner.

[0033] The object of the present invention can also be achieved in this way. A direct-fired heating device for a denitrification system includes a plurality of the aforementioned low-nitrogen flame burners, and the plurality of low-nitrogen flame burners constitute a burner group. The center line of the flame flow of each low-nitrogen flame burner in the burner group is tangent to an imaginary tangent circle, and the swinging flue part of each of the low-nitrogen flame burners can swing in the horizontal plane and the vertical plane to achieve spatial adjustment of the flame injection angle.

[0034] As described above, the low nitrogen flame burner and the direct-fired heating device for the denitration system provided by the present invention have the following beneficial effects:

[0035] The low-nitrogen flame burner provided by the present invention adopts a combination of a fixed flue portion and a swinging flue portion, and a driving structure adopts a combination of a horizontal driving structure and a vertical driving structure. The driving structure is used to realize the function of dynamically adjusting the outlet angle of the swinging flue portion in real time and online in both the horizontal and vertical directions, and realize the function of dynamically adjusting the flame combustion flue gas jet in the horizontal and vertical directions, so as to meet the requirements of dynamic heating in different areas, realize the dynamic adjustment of the size and intensity of the flame combustion area, meet the function of dynamically adjusting the size and position of the flame combustion area in the denitrification flue, promote the process requirements of rapid heat exchange between the high-temperature combustion flue gas and the gas in the denitrification flue, accurately control the temperature of the mixed flue gas, realize efficient flue gas denitrification reaction, and realize ultra-low emission of flue gas; the horizontal driving structure and the vertical driving structure meet the accurate setting and control of the swing angle of the low-nitrogen flame burner, and can realize the resetting of the initial position of the swinging flue portion; the low-nitrogen flame burner adopts the ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of equipment operation;

[0036] In the direct-fired heating device for the denitrification system of the present invention, a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the flame combustion heat of the low-nitrogen flame burners is used to directly heat the flue gas, thereby improving the heat utilization efficiency and reducing heat loss; a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the kinetic energy of the flame injection of the low-nitrogen flame burners is used to cause the flue gas to form a swirl zone, thereby achieving a dynamic swirl effect of the flue gas, promoting the turbulent flow of the flue gas, promoting the heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange area in the flue, and achieving temperature uniformity; the flame injection direction of the low-nitrogen flame burner is arranged opposite to the direction of the flue gas flow, thereby promoting the turbulent flow of the flue gas and the high-temperature flame ... The fast and efficient heat exchange of the warm flame shortens the time required for heat exchange, reduces the flue length required for uniform flue gas temperature, and promotes uniform temperature in the flue; the angles between the central axis of each low-nitrogen flame burner and the horizontal and vertical directions can be adjusted to realize the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and realize dynamic adjustment of the size and intensity of the swirl area; the direct-fired heating device for the denitrification system of the present invention directly heats the flue gas, prompts the flue gas temperature to reach the temperature range of the ideal denitrification reaction of the catalyst, realizes the expected denitrification reaction, meets the ultra-low emission requirements, and improves the economic benefits of equipment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0038] in:

[0039] Figure 1 : is the appearance diagram of the low nitrogen flame burner of the present invention.

[0040] Figure 2 : It is a schematic diagram of the swinging flue part of the low nitrogen flame burner of the present invention after swinging.

[0041] Figure 3 :for Figure 2 Enlarged view of point I in the middle.

[0042] Figure 4 : is the internal structure diagram of the low nitrogen flame burner of the present invention.

[0043] Figure 5 :for Figure 4 Center A view.

[0044] Figure 6 : It is a connection diagram of the low nitrogen flame burner of the present invention and the side wall of the denitrification flue.

[0045] Figure 7 : is a schematic diagram of a direct-fired heating device for a denitration system according to the present invention.

[0046] In the figure:

[0047] 100. Low nitrogen flame burner;

[0048] 200. Direct-fired heating device for denitration system; 201. Imaginary tangential circle;

[0049] 1. Burner body structure;

[0050] 11. Fixed flue section; 111. External spherical surface;

[0051] 12. Swinging flue part; 121. Inner spherical surface; 122. Stable combustion flue pipe; 1221. Stable combustion inner pipe; 1222. Stable combustion outer pipe; 1223. Refractory casting material unit; 123. Exit pipe;

[0052] 13. Gas chamber;

[0053] 14. Combustion-supporting chamber;

[0054] 15, ejector; 151, straight pipe section; 152, contraction section; 153, throat section; 154, expansion section; 155, rectification section;

[0055] 16. Ejection channel;

[0056] 2. Horizontal drive structure;

[0057] 3. Vertical drive structure;

[0058] 31. third fixed support; 32. fourth fixed support; 33. second telescopic cylinder; 331. second cylinder body; 332. second cylinder rod; 34. third rotating shaft; 35. third pin shaft; 36. fourth rotating shaft; 37. fourth pin shaft;

[0059] 41. Ignition device; 42. Flame detector; 43. Temperature detector;

[0060] 51. first flange; 52. second flange; 53. bellows;

[0061] 9. Denitrification flue; 91. Front side wall; 92. Rear side wall. DETAILED DESCRIPTION

[0062] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0063] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0065] like Figures 1 to 7As shown, the present invention provides a low-nitrogen flame burner 100, including a burner body structure 1, a horizontal drive structure 2 and a vertical drive structure 3. The burner body structure 1 includes a fixed flue portion 11 and a swinging flue portion 12. The swinging flue portion 12 can swing horizontally and vertically around the center line of the fixed flue portion 11. The horizontal drive structure 2 is used to drive the swinging flue portion 12 to swing in a horizontal plane; the vertical drive structure 3 is used to drive the swinging flue portion 12 to swing in a vertical plane.

[0066] The low-nitrogen flame burner provided by the present invention adopts a combination of a fixed flue portion and a swinging flue portion, and a driving structure adopts a combination of a horizontal driving structure and a vertical driving structure. The driving structure is used to realize the function of dynamically adjusting the outlet angle of the swinging flue portion in both the horizontal and vertical directions online in real time, and realize the function of dynamically adjusting the flame combustion flue gas jet in the horizontal and vertical directions, so as to meet the requirements of dynamic heating in different areas, realize the dynamic adjustment of the size and intensity of the flame combustion area, meet the function of dynamically adjusting the size and position of the flame combustion area in the denitrification flue, promote the process requirements of rapid heat exchange between the high-temperature combustion flue gas and the gas in the denitrification flue, accurately control the temperature of the mixed flue gas, realize efficient flue gas denitrification reaction, and realize ultra-low emission of flue gas; the horizontal driving structure and the vertical driving structure meet the accurate setting and control of the swing angle of the low-nitrogen flame burner, and can realize the resetting of the initial position of the swinging flue portion;

[0067] Burners of natural gas, blast furnace gas or other combustible gases are installed in the flue to directly heat the flue gas, which can cause the flue gas temperature to reach the ideal temperature range of the catalyst's denitrification reaction, meet ultra-low emission requirements, and improve the economic benefits of equipment operation.

[0068] Further, if Figure 2 As shown, the first end of the fixed flue part 11 is provided with an outer spherical surface 111, the center of the outer spherical surface 111 is located on the center line of the fixed flue part 11, and the first end of the swinging flue part 12 is provided with an inner spherical surface 121, and the inner spherical surface 121 can be rotatably sleeved on the outer spherical surface 111. The swinging flue part 12 and the fixed flue part 11 are hinged by a spherical surface, so that the swinging flue part 12 can swing in a single or simultaneous manner in a horizontal plane and a vertical plane. The width d of the outer spherical surface 111 and the inner spherical surface 121 is not less than 150 mm, preferably 200 to 300 mm.

[0069] Furthermore, in order to ensure the connection sealing performance between the swing flue part 12 and the fixed flue part 11 , an annular groove structure is provided on the outer spherical surface 111 , and a first elastic sealing ring is provided in the annular groove structure.

[0070] Furthermore, the horizontal driving structure 2 includes a first fixed support and a second fixed support which are horizontally arranged, the first end of the first fixed support is fixedly connected (welded) to the fixed flue portion 11, the first end of the second fixed support is fixedly connected (welded) to the swinging flue portion 12, and a first telescopic cylinder that can rotate around a horizontal axis is hinged between the second end of the first fixed support and the second end of the second fixed support.

[0071] Further, the first telescopic cylinder includes a first cylinder body and a first cylinder rod. The first end of the first cylinder rod is sealed and slidably penetrated into the first cylinder body from the first end of the first cylinder body. The first telescopic cylinder is a pneumatic cylinder or a hydraulic cylinder. The second end of the first fixed support is rotatably penetrated by a first rotating shaft, and a first pin is hinged on the first rotating shaft. The center line of the first pin is vertically arranged, and the first pin is hinged to the second end of the first cylinder body. The second end of the second fixed support is rotatably penetrated by a second rotating shaft, and a second pin is hinged on the second rotating shaft. The center line of the second pin is vertically arranged, and the second pin is hinged to the second end of the first cylinder rod.

[0072] Further, if Figure 1 , Figure 2 , Figure 3 As shown, the vertical drive structure 3 includes a third fixed support 31 and a fourth fixed support 32 which are vertically arranged, the first end of the third fixed support 31 is fixedly connected (welded) to the fixed flue portion 11, the first end of the fourth fixed support 32 is fixedly connected (welded) to the swinging flue portion 12, and a second telescopic cylinder 33 which can rotate around a vertical axis is hinged between the second end of the third fixed support 31 and the second end of the fourth fixed support 32.

[0073] Further, if Figure 3 As shown, the second telescopic cylinder 33 includes a second cylinder body 331 and a second cylinder rod 332. The first end of the second cylinder rod 332 is sealed and slidably penetrated into the second cylinder body 331 from the first end of the second cylinder body 331. The second telescopic cylinder 33 is a pneumatic cylinder or a hydraulic cylinder; the second end of the third fixed support 31 is rotatably penetrated by a third rotating shaft 34, and a third pin 35 is hinged on the third rotating shaft 34. The center line of the third pin 35 is horizontally arranged, and the third pin 35 is hinged to the second end of the second cylinder body 331; the second end of the fourth fixed support 32 is rotatably penetrated by a fourth rotating shaft 36, and a fourth pin 37 is hinged on the fourth rotating shaft 36. The center line of the fourth pin 37 is horizontally arranged, and the fourth pin 37 is hinged to the second end of the second cylinder rod 332.

[0074] Furthermore, the horizontal driving structure 2 drives the swinging flue part 12 to swing in the horizontal plane within an angle range of -30° to 30°; the vertical driving structure 3 drives the swinging flue part 12 to swing in the vertical plane within an angle range of -30° to 30°.

[0075] The first cylinder rod is telescopically extended along the first cylinder body, pushing the swinging flue portion 12 to swing in the horizontal plane, and at the same time, the swinging flue portion 12 drives the second telescopic cylinder 33 to rotate relative to the third rotation axis 34; the second cylinder rod 332 is telescopically extended along the second cylinder body 331, pushing the swinging flue portion 12 to swing in the vertical plane, and at the same time, the swinging flue portion 12 drives the first telescopic cylinder to rotate relative to the first rotation axis; the horizontal driving structure 2 and the vertical driving structure 3 can act simultaneously, so that the swinging flue portion 12 can swing at a certain angle in both the horizontal and vertical directions, thereby realizing the spatial adjustment of the flame injection angle.

[0076] Further, if Figure 4 As shown, the swing flue portion 12 includes a stable combustion flue pipe 122, and an outlet pipe 123 with a reduced diameter is arranged at one end of the stable combustion flue pipe 122 away from the fixed flue portion 11; the second fixed support and the fourth fixed support 32 are fixedly connected to the outer wall of the stable combustion flue pipe 122. The length of the outlet pipe 123 is not less than 200 mm.

[0077] Further, if Figure 5 As shown, the stable combustion flue pipe 122 includes a stable combustion inner pipe 1221 and a stable combustion outer pipe 1222 which are coaxially and radially spaced. The cross section of the stable combustion inner pipe 1221 is a closed contour formed by splicing multiple arcs, and the number of spliced ​​arcs is preferably an even number; the cross section of the stable combustion outer pipe 1222 is circular, and a stable combustion annular space is formed between the stable combustion inner pipe 1221 and the stable combustion outer pipe 1222, and the stable combustion annular space is filled with a refractory casting material unit 1223. The cross section of the stable combustion inner pipe 1221 is spliced ​​by multiple arcs, which increases the contact area between the high-temperature flame and the flue gas, promotes the heat exchange of the flue gas, and is conducive to maintaining a good gathering effect of the combustion flame, increasing the flame length, and avoiding premature divergence and attenuation of the flame.

[0078] Further, if Figure 4 As shown, the inner cavity of the fixed flue portion 11 and the inner cavity of the swinging flue portion 12 are connected to form a combustion mixing chamber. The end of the fixed flue portion 11 away from the swinging flue portion 12 is connected to set a gas chamber 13 and a combustion-supporting chamber 14. An ejector 15 is passed through the gas chamber 13 and the combustion-supporting chamber 14. The ejector 15 is coaxially arranged with the fixed flue portion 11. The combustible gas is evenly pressure-distributed in the gas chamber 13. The ejector 15 is used to accelerate the combustible gas in the gas chamber 13 to be sprayed into the combustion mixing chamber. A necked ejection channel 16 is formed between the combustion-supporting chamber 14 and the combustion mixing chamber. The combustion-supporting gas in the combustion-supporting chamber 14 is ejected into the combustion mixing chamber through the ejection channel. An igniter 41, a flame detector 42 and a temperature detector 43 are arranged in the combustion mixing chamber. The combustible gas and the combustion-supporting gas are mixed and burned in the combustion mixing chamber to form high-temperature flue gas. The high-temperature flue gas enters the denitrification flue through the rectifier injection of the outlet pipe. The high-temperature flue gas is quickly mixed with the gas in the denitrification flue to increase the flue gas temperature to meet the subsequent denitrification reaction.

[0079] The flame detector 42 and the temperature detector 43 are both electrically connected to the control system; the flame detector 42 is used to detect the combustion conditions of the flame in the combustion mixing chamber. If the flame is extinguished, the igniter is re-ignited through the control system to achieve stable combustion of the flame burner; the temperature detector 43 is used to detect the temperature in the combustion mixing chamber.

[0080] The combustible gas entering the low-nitrogen flame burner may be blast furnace gas, converter gas, coke oven gas, natural gas, etc., or a mixture of blast furnace gas, converter gas, coke oven gas or natural gas.

[0081] The combustion-supporting gas entering the low-nitrogen flame burner can be air, pure oxygen, or the original flue gas in the flue containing a certain amount of oxygen, or a mixture of air, oxygen and the original flue gas. The combustion-supporting gas can use the original flue gas in the denitrification flue as the combustion-supporting gas to carry out the combustion reaction of the low-nitrogen flame burner, so as to realize the combustion of the combustible gas under the condition of low oxygen concentration, avoid the generation of NOx, and realize the low-nitrogen combustion of the gas.

[0082] Further, if Figure 4 As shown, the ejector 15 includes a straight pipe section 151, a contraction section 152, a throat section 153, an expansion section 154 and a rectification section 155. The straight pipe section 151 is located in the combustion chamber 13, and the contraction section 152, the throat section 153, the expansion section 154 and the rectification section 155 are located in the combustion-supporting chamber 14; an air inlet is arranged at the first end of the straight pipe section 151, and the second end of the straight pipe section 151 is connected to the first end of the contraction section 152, and the diameter of the contraction section 152 is gradually reduced from the first end to the second end, and the second end of the contraction section 152 is connected to the first end of the throat section 153, and the second end of the throat section 153 is connected to the first end of the expansion section 154, and the diameter of the expansion section 154 is gradually increased from the first end to the second end, and the second end of the expansion section 154 is connected to the first end of the rectification section 155, and the second end of the rectification section 155 is provided with an air outlet. In a specific embodiment of the present invention, the distance between the air outlet of the ejector and the bottom of the combustion mixing chamber is between 100 and 300 mm, and the preferred range is 150 to 250 mm.

[0083] The rectifying section 155 includes a rectifying inner tube and a rectifying outer tube which are coaxially and radially spaced apart. The cross section of the rectifying inner tube is a closed contour formed by splicing multiple arc segments, and the cross section of the rectifying outer tube is a circle. A rectifying annular space is formed between the rectifying inner tube and the rectifying outer tube, and the rectifying annular space is filled with refractory castable material units.

[0084] The multi-arc circular cross section of the rectifying section 155 can make the combustible gas still maintain the multi-arc circular cross section to spray forward after leaving the outlet pipe. The multi-arc circular cross section shape increases the contact area between the combustible gas and the combustion-supporting gas, while maintaining the stability of combustion, and achieving a good gathering effect of the jet flame, avoiding premature divergence and attenuation of the flame, ensuring that the flames sprayed by multiple low-nitrogen flame burners have high kinetic energy, and efficiently stirring the flue gas in the flue to promote heat exchange. At the same time, the multi-arc circular cross section structure can reduce the local oxygen content of the combustible gas combustion, reduce the local high temperature of the low-nitrogen flame burner, avoid the generation of NOx, and achieve low-nitrogen combustion.

[0085] The low nitrogen flame burner 100 adopts the ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of the equipment operation. The combustion chamber and the gas chamber are connected to the corresponding pipelines through flanges, and flow meters and flow regulating valves are arranged on the corresponding pipelines. The flow meters and flow regulating valves are electrically connected to the control system. The required combustible gas and combustion-supporting gas demand are calculated according to the control model using the detection data of the temperature detection device in the denitration system, and the flow is adjusted through the flow regulating valve (electric regulating valve) until the flow reaches the predetermined demand.

[0086] Further, if Figure 6 As shown, a first flange 51 is sleeved (welded) on the side wall of the swinging flue portion 12, one end of a bellows 53 is connected to the first flange 51, and the other end of the bellows 53 is connected to a second flange 52. The second flange 52 is used for sealing connection with the side wall of the denitrification flue, and the first flange 51, the bellows 53 and the second flange 52 constitute an elastically connected sealing cover of the burner.

[0087] A burner through hole is arranged on the side wall of the denitrification flue, and the swinging flue portion 12 passes through the burner through hole. The diameter of the burner through hole is larger than the diameter of the swinging flue portion 12. In a specific embodiment of the present invention, the distance between the inner wall of the burner through hole and the outer wall of the swinging flue portion 12 is not less than 300 mm (that is, the difference between the radii of the two is not less than 300 mm). The space between the inner wall of the burner through hole and the outer wall of the swinging flue portion 12 can realize the swinging of the swinging flue portion 12 in the horizontal and vertical directions, thereby realizing the spatial dynamic adjustment of the injection angle of the high-temperature flame jet of the flame burner; the length of the bellows 53 is not less than 600 mm, and the distance that the outlet end of the swinging flue portion 12 penetrates into the side wall of the denitrification flue does not exceed 100 mm.

[0088] like Figure 7As shown, the present invention also provides a direct-fired heating device 200 for a denitrification system, comprising a plurality of the aforementioned low-nitrogen flame burners 100, wherein the plurality of low-nitrogen flame burners 100 constitute a burner group, wherein the center line of the flame stream of each low-nitrogen flame burner 100 of the burner group is tangent to an imaginary tangent circle, and the swinging flue portion 12 of each low-nitrogen flame burner 100 can swing in the horizontal plane and the vertical plane to achieve spatial adjustment of the flame injection angle.

[0089] In this embodiment, the direct-fired heating device 200 for the denitrification system includes at least two burner groups, and the number of burner groups is an even number; the center line of the flame flow of each low-nitrogen flame burner 100 of each burner group is tangent to an imaginary tangent circle, and the center line of each flame flow of two adjacent burner groups is opposite to the cutting direction of the imaginary tangent circle 201; the flame injection direction of each low-nitrogen flame burner 100 is opposite to the flue gas flow direction, and the flame injection length L of each low-nitrogen flame burner 100 is adjustable. By adjusting the flow rate and ratio of the combustible gas and the combustion-supporting gas of the low-nitrogen flame burner 100, the flame length of the low-nitrogen flame burner 100 can be adjusted.

[0090] The center line of each flame stream of two adjacent burner groups is set opposite to the cutting direction of the imaginary tangent circle, that is, the center line of each flame stream of two adjacent burner groups and the cutting direction of the imaginary tangent circle adopt the opposite swirl mode, eliminating the impact of the two groups of swirl flame burners and realizing the stable operation of the swirl. The number of burner groups is an even number to ensure the stable operation of the heating device.

[0091] The flame injection length of each low-nitrogen flame burner 100 can be adjusted, the diameter of the imaginary tangent circle tangent to the center line of the flame flow of each low-nitrogen flame burner 100 of each burner group is different, and the height position of the imaginary tangent circle is different. Different swirl mixing area controls can be achieved under different flue gas flow conditions. The position of the high-temperature zone of the flame in the flue is adjustable to achieve dynamic adjustment of the flue gas mixing.

[0092] like Figure 7 As shown, the denitrification flue 9 is a rectangular flue and is arranged vertically. The center line of the two opposite side walls (front side wall 91 and rear side wall 92) of the denitrification flue 9 is the hedging center line. The flame burners are divided into two groups, and each burner group includes four low-nitrogen flame burners 100. The low-nitrogen flame burners 100 are in the form of tangential combustion. The gas streams of the low-nitrogen flame burners 100 are fed in a tangential manner, and each low-nitrogen flame burner 100 forms an octagonal double tangential combustion structure. The center line of the flame streams sprayed by each group of low-nitrogen flame burners 100 is tangent to the same imaginary tangential circle (ellipse or circle), and the rotation directions of the two groups of imaginary tangential circles (ellipse or circle) are opposite, one is clockwise and the other is counterclockwise.

[0093] In actual engineering applications, low-nitrogen flame burners 100 can be appropriately added to the front side wall 91 and the rear side wall 92 according to the cross-sectional size of the denitrification flue 9; low-nitrogen flame burners 100 can also be appropriately added to the other two side walls of the denitrification flue 9.

[0094] like Figure 7 As shown, in a specific embodiment of the present invention, the angles between the eight low-nitrogen flame burners 100 and the side walls of the vertical denitrification flue 9 are β 1 , β 2 , β 3 , β 4 , β 5 , β 6 , β 7 , β 8 , which ranges from 15° to 85°, and preferably ranges from 30° to 65°.

[0095] The present invention adopts the swirl effect of Laval nozzle injection and a double tangential circle arrangement. The two groups of imaginary tangential circles adopt opposite swirl modes, eliminating the impact of the two groups of swirl low-nitrogen flame burners 100 and achieving stable swirl operation.

[0096] In the direct-fired heating device for the denitrification system of the present invention, a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the flame combustion heat of the low-nitrogen flame burners is used to directly heat the flue gas, thereby improving the heat utilization efficiency and reducing heat loss; a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the kinetic energy of the flame injection of the low-nitrogen flame burners is used to cause the flue gas to form a swirl zone, thereby achieving a dynamic swirl effect of the flue gas, promoting the turbulent flow of the flue gas, promoting the heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange area in the flue, and achieving temperature uniformity; the flame injection direction of the low-nitrogen flame burner is arranged opposite to the direction of the flue gas flow, thereby promoting the turbulent flow of the flue gas and the high-temperature flame ... The fast and efficient heat exchange of the warm flame shortens the time required for heat exchange, reduces the flue length required for uniform flue gas temperature, and promotes uniform temperature in the flue; the angles between the central axis of each low-nitrogen flame burner and the horizontal and vertical directions can be adjusted to realize the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and realize dynamic adjustment of the size and intensity of the swirl area; the direct-fired heating device for the denitrification system of the present invention directly heats the flue gas, prompts the flue gas temperature to reach the temperature range of the ideal denitrification reaction of the catalyst, realizes the expected denitrification reaction, meets the ultra-low emission requirements, and improves the economic benefits of equipment operation.

[0097] As described above, the low nitrogen flame burner and the direct-fired heating device for the denitration system provided by the present invention have the following beneficial effects:

[0098] The low-nitrogen flame burner provided by the present invention adopts a combination of a fixed flue portion and a swinging flue portion, and a driving structure adopts a combination of a horizontal driving structure and a vertical driving structure. The driving structure is used to realize the function of dynamically adjusting the outlet angle of the swinging flue portion in real time and online in both the horizontal and vertical directions, and realize the function of dynamically adjusting the flame combustion flue gas jet in the horizontal and vertical directions, so as to meet the requirements of dynamic heating in different areas, realize the dynamic adjustment of the size and intensity of the flame combustion area, meet the function of dynamically adjusting the size and position of the flame combustion area in the denitrification flue, promote the process requirements of rapid heat exchange between the high-temperature combustion flue gas and the gas in the denitrification flue, accurately control the temperature of the mixed flue gas, realize efficient flue gas denitrification reaction, and realize ultra-low emission of flue gas; the horizontal driving structure and the vertical driving structure meet the accurate setting and control of the swing angle of the low-nitrogen flame burner, and can realize the resetting of the initial position of the swinging flue portion; the low-nitrogen flame burner adopts the ejector jet technology, which reduces the load of the system fan, reduces the resistance loss of the flue, and improves the stability of equipment operation;

[0099] In the direct-fired heating device for the denitrification system of the present invention, a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the flame combustion heat of the low-nitrogen flame burners is used to directly heat the flue gas, thereby improving the heat utilization efficiency and reducing heat loss; a plurality of low-nitrogen flame burners are grouped in the denitrification flue, and the kinetic energy of the flame injection of the low-nitrogen flame burners is used to cause the flue gas to form a swirl zone, thereby achieving a dynamic swirl effect of the flue gas, promoting the turbulent flow of the flue gas, promoting the heat exchange between the flue gas and the high-temperature flame, shortening the length of the heat exchange area in the flue, and achieving temperature uniformity; the flame injection direction of the low-nitrogen flame burner is arranged opposite to the direction of the flue gas flow, thereby promoting the turbulent flow of the flue gas and the high-temperature flame ... The fast and efficient heat exchange of the warm flame shortens the time required for heat exchange, reduces the flue length required for uniform flue gas temperature, and promotes uniform temperature in the flue; the angles between the central axis of each low-nitrogen flame burner and the horizontal and vertical directions can be adjusted to realize the function of dynamic adjustment of the flame jet in the horizontal and vertical directions, meet the requirements of dynamic heating in different areas, and realize dynamic adjustment of the size and intensity of the swirl area; the direct-fired heating device for the denitrification system of the present invention directly heats the flue gas, prompts the flue gas temperature to reach the temperature range of the ideal denitrification reaction of the catalyst, realizes the expected denitrification reaction, meets the ultra-low emission requirements, and improves the economic benefits of equipment operation.

[0100] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. A low nitrogen flame burner, characterized in that: The burner comprises a burner body structure, a horizontal driving structure and a vertical driving structure. The burner body structure comprises a fixed flue part and a swinging flue part. The swinging flue part can swing horizontally and vertically around the center line of the fixed flue part. The horizontal driving structure is used to drive the swinging flue part to swing in a horizontal plane. The vertical driving structure is used to drive the swinging flue part to swing in a vertical plane. The first end of the fixed flue part is provided with an outer spherical surface, the center of which is located on the center line of the fixed flue part, and the first end of the swing flue part is provided with an inner spherical surface, which can be rotatably sleeved on the outer spherical surface; The horizontal driving structure comprises a first fixed support and a second fixed support which are arranged horizontally, wherein a first end of the first fixed support is fixedly connected to the fixed flue portion, a first end of the second fixed support is fixedly connected to the swing flue portion, and a first telescopic cylinder which can rotate around a horizontal axis is hinged between the second end of the first fixed support and the second end of the second fixed support; The vertical drive structure includes a third fixed support and a fourth fixed support which are vertically arranged. The first end of the third fixed support is fixedly connected to the fixed flue part, the first end of the fourth fixed support is fixedly connected to the swinging flue part, and a second telescopic cylinder that can rotate around a vertical axis is hinged between the second end of the third fixed support and the second end of the fourth fixed support.

2. The low nitrogen flame burner according to claim 1, characterized in that: The first telescopic cylinder includes a first cylinder body and a first cylinder rod, the first end of the first cylinder rod is sealed and slidably penetrated into the first cylinder body from the first end of the first cylinder body; a first rotating shaft is rotatably penetrated through the second end of the first fixed support, a first pin is hinged on the first rotating shaft, the center line of the first pin is vertically arranged, and the first pin is hinged to the second end of the first cylinder body; a second rotating shaft is rotatably penetrated through the second end of the second fixed support, a second pin is hinged on the second rotating shaft, the center line of the second pin is vertically arranged, and the second pin is hinged to the second end of the first cylinder rod.

3. The low nitrogen flame burner according to claim 1, characterized in that: The second telescopic cylinder includes a second cylinder body and a second cylinder rod, and the first end of the second cylinder rod is sealed and slidably penetrated into the second cylinder body from the first end of the second cylinder body; a third rotating shaft is rotatably penetrated through the second end of the third fixed support, a third pin is hinged on the third rotating shaft, the center line of the third pin is horizontally arranged, and the third pin is hinged to the second end of the second cylinder body; a fourth rotating shaft is rotatably penetrated through the second end of the fourth fixed support, a fourth pin is hinged on the fourth rotating shaft, the center line of the fourth pin is horizontally arranged, and the fourth pin is hinged to the second end of the second cylinder rod.

4. The low nitrogen flame burner according to claim 1, characterized in that: The swinging flue portion includes a stable combustion flue pipe, and an outlet pipe with a reduced diameter is arranged at one end of the stable combustion flue pipe away from the fixed flue portion; the second fixed support and the fourth fixed support are fixedly connected to the outer wall of the stable combustion flue pipe.

5. The low nitrogen flame burner according to claim 4, characterized in that: The flame-stabilizing flue pipe comprises a flame-stabilizing inner pipe and a flame-stabilizing outer pipe which are coaxially and radially spaced apart. The cross section of the flame-stabilizing inner pipe is a closed contour formed by splicing multiple arc segments, and the cross section of the flame-stabilizing outer pipe is a circle. A flame-stabilizing annular space is formed between the flame-stabilizing inner pipe and the flame-stabilizing outer pipe, and the flame-stabilizing annular space is filled with a refractory castable material unit.

6. The low nitrogen flame burner according to claim 1, characterized in that: An annular groove structure is arranged on the outer spherical surface, and a first elastic sealing ring is arranged in the annular groove structure.

7. The low nitrogen flame burner according to claim 1, characterized in that: The horizontal driving structure drives the swinging flue part to swing in a horizontal plane within an angle range of -30° to 30°; the vertical driving structure drives the swinging flue part to swing in a vertical plane within an angle range of -30° to 30°.

8. The low nitrogen flame burner according to claim 1, characterized in that: The inner cavity of the fixed flue part and the inner cavity of the swinging flue part are connected to form a combustion mixing chamber. The fixed flue part is connected to a combustion-supporting chamber and a gas chamber at one end away from the swinging flue part. Ejectors are inserted through the gas chamber and the combustion-supporting chamber. The ejector is coaxially arranged with the fixed flue part. The ejector is used to accelerate the combustible gas in the gas chamber and spray it into the combustion mixing chamber. A necked ejection channel is formed between the combustion-supporting chamber and the combustion mixing chamber. The combustion-supporting gas in the combustion-supporting chamber is ejected into the combustion mixing chamber through the ejection channel. An igniter, a flame detector and a temperature detector are arranged in the combustion mixing chamber.

9. The low nitrogen flame burner according to claim 8, characterized in that: The ejector includes a straight pipe section, a contraction section, a throat section, an expansion section and a rectification section, the straight pipe section is located in the fuel gas chamber, the contraction section, the throat section, the expansion section and the rectification section are located in the combustion-supporting gas chamber; an air inlet is arranged at the first end of the straight pipe section, the second end of the straight pipe section is connected to the first end of the contraction section, the diameter of the contraction section is gradually contracted from the first end to the second end, the second end of the contraction section is connected to the first end of the throat section, the second end of the throat section is connected to the first end of the expansion section, the diameter of the expansion section is gradually expanded from the first end to the second end, the second end of the expansion section is connected to the first end of the rectification section, and an air outlet is arranged at the second end of the rectification section.

10. The low nitrogen flame burner according to claim 8, characterized in that: A first flange is sleeved on the side wall of the swinging flue part, one end of the bellows is connected to the first flange, the other end of the bellows is connected to the second flange, the second flange is used for sealing connection with the side wall of the denitrification flue, and the first flange, the bellows and the second flange constitute an elastic connection sealing cover of the burner.

11. A direct-fired heating device for a denitration system, characterized in that: The method comprises a plurality of low-nitrogen flame burners as described in any one of claims 1 to 10, wherein the plurality of low-nitrogen flame burners constitute a burner group, the center line of the flame stream of each low-nitrogen flame burner of the burner group is tangent to an imaginary tangent circle, and the swinging flue part of each low-nitrogen flame burner can swing in the horizontal plane and the vertical plane to realize spatial adjustment of the flame injection angle.

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