Central fuel gas injection type low-nitrogen burner based on fuel gas classification

Abstract

A central fuel gas injection type low-nitrogen burner based on fuel gas classification relates to the technical field of combustion and comprises a central fuel gas gun, a burner block, peripheral fuel gas guns and a burner flame holder, the burner block is cylindrical, penetrates through furnace bottom castable and extends into the inner side of the furnace bottom castable, and a hearth is arranged on the inner side of the furnace bottom castable; one end of the central gas gun penetrates into the furnace bottom castable from the outside of the furnace bottom castable and penetrates into the inner side of the burner block from the outer side of the burner block; one end of the peripheral gas gun penetrates into the furnace bottom castable from the outside of the furnace bottom castable and is positioned on the outer side of the burner block; the ends, located outside the furnace bottom castable, of the center gas gun and the peripheral gas guns are used for introducing gas, the end, close to the outside of the furnace bottom castable, of the cylindrical burner block communicates with an air inlet air bellow, and the air inlet air bellow is used for introducing combustion air into the burner block. And the combustor flame holder is arranged in the combustor burner block. And through the injection type structural design, the problem that nitric oxide is generated by combustion of the central gas fuel is further controlled.

Description

Technical Field

[0001] The present application belongs to the field of combustion technology, and in particular relates to a central gas injection low-nitrogen burner based on gas grading. Background Art

[0002] When fuel burns, nitrogen-containing substances are oxidized under high temperature conditions to form nitrogen oxides, which are one of the main culprits of acid rain.

[0003] Existing typical technical solutions for controlling nitrogen oxide emissions include gas staging, air staging, and air injection technology based on gas staging.

[0004] Gas staging technology is to divide the gas into two or more levels. The main structural feature is that the central gas is arranged in the combustion-supporting air channel in a diffusion combustion mode, which stabilizes the combustion and ignites the peripheral gas. The peripheral gas is arranged outside the combustion-supporting air channel, and the reaction intensity is reduced by weakening the mixing with the air, and the emission is reduced by reducing the flame temperature. Chinese invention patent CN117387068A discloses a staged combustion gas-injected chemical low-nitrogen burner and a gas staged combustion ultra-low nitrogen oxide burner. Gas staging technology can effectively reduce nitrogen oxide emissions, but the central gas is mixed with air in a diffusion combustion mode for full combustion, and the chemical equivalent combustion of the flame front will make the central flame produce nitrogen oxides that cannot be controlled. And excessively reducing the flow rate of the central gas will not play the role of igniting the peripheral gas to stabilize the flame.

[0005] Air staging technology is to divide the air into two channels or multiple channels. The main structural feature is that the gas is arranged in one of the air channels, or multiple channels form an air staging and gas staging coupling. The air excess coefficient of the channel is less than 1, resulting in incomplete combustion, thereby reducing the flame temperature. Chinese invention patent CN108151017A discloses an air-gas staging combustion ultra-low nitrogen oxide burner, in which the combustible gas that is not fully burned continues to burn fully with the air in other channels. Diffusion combustion belongs to chemical equivalent combustion, that is, the gas and air at the flame front react fully, so although there is excess air, the flame front temperature is still high. Practice has shown that air staging and air-gas staging schemes are not as good as gas staging schemes in controlling nitrogen oxides.

[0006] Air injection technology based on gas staging is one of the most advanced low-nitrogen combustion technology solutions. The Chinese invention patent CN110779014A discloses an ultra-low nitrogen burner and boiler with internal circulation of flue gas, which is characterized by increasing the pressure drop of the combustion-supporting air, that is, increasing the wind speed, by lengthening the throat channel length, and opening a hole on the side of the furnace plate near the installation of the burner, forming an ejector principle, so as to achieve the effect of the combustion-supporting air extracting the flue gas. The oxygen concentration of the combustion-supporting air will be reduced to a certain extent, so that the flame temperature of the central fuel gas will be reduced to a certain extent. In addition, because the combustion-supporting air extracts the flue gas, a layer of air and flue gas is formed, which delays the combustion of the peripheral fuel gas and reduces the flame temperature. The air injection technology based on gas staging greatly reduces the temperature of the central fuel gas flame, but due to its structural principle, the throat air duct exposed in the furnace needs to be lengthened, otherwise the serious air and induced flue gas layer will cause serious pressure fluctuations in the furnace. At the same time, in order to reduce the induced resistance, the throat air duct exposed to the furnace is made of metal and has a large diameter. Long-term use may cause the risk of burning the throat air duct, especially in high-temperature furnace conditions with hydrogen fuel. Summary of the invention

[0007] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and provide a central gas injection low-nitrogen burner based on gas grading, to further control the problem of nitrogen oxides produced by the combustion of the central gas fuel, and at the same time solve the problem of burning of the metal wind duct exposed in the furnace.

[0008] Through the structural design of the burner head, the central gas gun on the inner side of the burner brick is ensured to have a stable flame and low nitrogen oxide generation, and the peripheral gas gun on the outer side of the burner brick is used as the main flame to achieve ultra-low nitrogen oxide emissions. The burner can be applied to various gas furnaces in the petrochemical, coal chemical, steel and heating industries, and the power range is not limited.

[0009] The technical solutions provided by this application are as follows:

[0010] A central gas injection low-nitrogen burner based on gas grading comprises a central gas gun, a burner brick, a peripheral gas gun and a burner flame stabilizer, wherein the burner brick is cylindrical, the cylindrical burner brick passes through a furnace bottom castable and extends into the inner side of the furnace bottom castable, the inner side of the furnace bottom castable is a furnace; one end of the central gas gun penetrates into the furnace bottom castable from outside the furnace bottom castable and penetrates into the inner space of the burner brick from the outer side of the burner brick; one end of the peripheral gas gun penetrates into the furnace bottom castable from outside the furnace bottom castable and is located outside the burner brick; the ends of the central gas gun and the peripheral gas gun located outside the furnace bottom castable are both used for introducing gas, the end of the cylindrical burner brick located outside the furnace bottom castable is connected to an air inlet wind box, and the air inlet wind box is used for introducing combustion-supporting air into the burner brick; the burner flame stabilizer is arranged in the burner brick of the burner.

[0011] Along the air inlet direction from the air inlet wind box to the inside of the burner brick, the burner brick has a first cavity and a second cavity in sequence, the diameter of the first cavity is smaller than the diameter of the second cavity, and the first cavity and the second cavity form a sudden expansion structure; the central gas gun extends into the second cavity.

[0012] The central gas gun comprises a central gas gun riser, a central nozzle, a central flue gas ejector and a plurality of central nozzle positioning plates, wherein one end of the central gas gun riser is located outside the furnace bottom castable, and the other end extends into the inner side of the furnace bottom castable, and the end is bent and connected to the central nozzle; one end of the central flue gas ejector is exposed in the furnace chamber outside the burner brick and is coaxial with the axis of the central nozzle, and the other end of the central flue gas ejector passes through the burner brick and extends into the combustion-supporting air channel and is parallel to the flow direction of the combustion-supporting air; a plurality of central nozzle positioning plates are connected between the central nozzle and the end of the central flue gas ejector exposed in the furnace chamber outside the burner brick, so that a gap is formed between the central nozzle and the central flue gas ejector, and the flue gas is ejected into the central flue gas ejector from the gap.

[0013] The angle c between the central smoke ejector pipe located at the outer side of the burner brick and the flow direction of the combustion air is 40°-60°.

[0014] The distance from the outlet of the central flue gas ejector to the end face of the burner flame stabilizer is L3. The size of L3 is related to the aerodynamic parameters and physicochemical properties of the fuel and ranges from 20 mm to 50 mm.

[0015] The distance from the outlet of the central flue gas ejector pipe to the end of the burner nozzle brick inside the furnace bottom castable is L4. The size of L4 is related to the aerodynamic parameters and physicochemical properties of the fuel and ranges from 100 mm to 200 mm.

[0016] The spray hole of the central nozzle is coaxial with the inlet end of the central smoke ejector tube, and the end face distance between the end face of the central nozzle and the inlet end of the central smoke ejector tube is -20mm to +30mm; wherein, - indicates that the central nozzle is inserted into the central smoke ejector tube, and + indicates that there is a gap between the end of the central nozzle and the central smoke ejector tube in the axial direction of the central nozzle.

[0017] The minimum distance between the axis of the peripheral gas gun and the inner wall of the burner brick is not less than L5. The size of L5 is related to the power of the burner. In a low-power burner, the value of L5 should be not less than 30mm to ensure that the combustion-supporting air (gas) and the peripheral gas have a certain spacing distance.

[0018] The peripheral gas gun comprises a peripheral gas gun riser, a peripheral nozzle, a peripheral smoke ejector pipe and a plurality of peripheral nozzle positioning plates. One end of the peripheral gas gun riser is located outside the furnace, and the other end extends into the furnace and is connected to the peripheral nozzle. The spray hole of the peripheral nozzle is coaxial with the inlet end of the peripheral smoke ejector pipe. The peripheral nozzle and the peripheral smoke ejector pipe are connected by a plurality of peripheral nozzle positioning plates so that there is a gap between the peripheral nozzle and the peripheral smoke ejector pipe, and the smoke in the furnace is ejected into the peripheral smoke ejector pipe from the gap.

[0019] The angle between the axis of the peripheral flue gas ejector outlet and the direction of combustion air blowing is 0, or the peripheral flue gas ejector outlet is bent toward the center of the burner brick, at which time the angle between the axis of the peripheral flue gas ejector outlet and the direction of combustion air blowing is 0-30°.

[0020] In summary, this application at least includes the following beneficial technical effects:

[0021] As described above, a central gas injection type low nitrogen burner based on gas grading is designed according to the principle of gas injector, and the central gas gun is designed as an injection structure. The gas in the riser forms a high-speed airflow through the nozzle and is injected into the central flue gas injector. Under the action of the high-speed airflow, the flue gas mainly composed of inert gas in the combustion chamber is sucked into the central flue gas injector. Under the action of strong turbulence, the gas and the flue gas are fully mixed in the central flue gas injector. The mixed central mixed gas is mixed with the combustion-supporting air in the burner brick for combustion. Each central nozzle is provided with a spray hole, which is beneficial to increase the amount of smoke entrainment. If each nozzle is provided with multiple spray holes, the distance between adjacent spray holes is too close, which will cause the entrained smoke to interfere with each other, increase the friction of the air mass, reduce the injection amount, and fail to achieve the purpose of diluting the gas. Because the mixed central mixed gas contains a certain amount of inert gas, the flame temperature can be effectively reduced. Here, the mixed gas of 100% concentration natural gas and 60% concentration natural gas mixed with 40% concentration nitrogen is compared with the combustion air of 25℃, and the flame temperature of the latter is 100℃ lower than that of the former. According to numerical simulation and experiment, the temperature of the latter mixed gas is lower than that of the former, because the mixed gas is mixed with combustible gas and non-combustible gas, which is equivalent to the flame being fragmented. The flame behavior is manifested as the flame length becoming longer and the temperature decreasing. This feature is easily not considered in analytical calculation. Because the other part of the central gas ejector pipe passes through the burner brick and extends into the combustion air channel, the mixed gas will be cooled by the combustion air, so the problem of the temperature increase of the mixed gas caused by the gas ejection furnace flue gas can be ignored. Thereby ensuring that the nitrogen oxides generated by the central gas gun flame are effectively controlled. By controlling the load proportion of the above-mentioned central gas gun, adjusting the air excess coefficient of the throat combustion air, and then finely controlling the oxygen concentration of the combustion gas at the burner brick outlet, the oxygen concentration at the burner brick outlet is generally controlled at 15%-18%. The central gas gun is made of 310S material. Because there is always high-speed flammable gas flowing in the central gas riser and the central nozzle, the temperature can be effectively reduced to ensure the safety of the riser and the nozzle. In the central flue gas ejector, the ejected flue gas is partially heat-exchanged flue gas rather than flame, so the temperature is generally lower than 1200°C. At the same time, it is mixed with low-temperature fuel gas. The overall temperature meets the use conditions of 310S material, ensuring the safety of the central gas gun assembly.

[0022] As described above, in a central gas-injection low-nitrogen burner based on gas grading, the burner bricks described therein ensure that the central flame and the peripheral flame are separated, delay the mixing of the combustion-supporting gas at the burner brick outlet with the gas in the peripheral gas spray gun, form a graded combustion structure, disperse the heat release volume, weaken the heat release intensity, and reduce thermal nitrogen oxide emissions. The high temperature resistance of the burner bricks can ensure that the combustion-supporting air throat structure is not burned. The burner bricks described therein are designed as a sudden expansion structure from the air inlet to the outlet below the central flue gas injection pipe hole or slot, which can prevent the combustion-supporting air from flowing out of the burner bricks at the hole or slot position.

[0023] As described above, a central gas injection type low nitrogen burner based on gas grading is designed as an injection structure according to the gas injection principle. The gas in the riser of the peripheral gas gun forms a high-speed airflow through the nozzle and is injected into the peripheral flue gas injection tube. Under the action of the high-speed airflow, the flue gas mainly composed of inert gas in the combustion chamber is sucked into the peripheral flue gas injection tube. Under the action of strong turbulence, the gas and the flue gas are fully mixed in the central flue gas injection tube, and the mixed peripheral mixed gas is mixed and burned with the low oxygen concentration combustion-supporting gas at the burner brick outlet. Each peripheral nozzle is provided with a spray hole, which is beneficial to increase the amount of smoke entrainment. If each nozzle is provided with multiple spray holes, the distance between adjacent spray holes is too close, which will cause the entrained smoke to interfere with each other, increase the friction of the air mass, reduce the injection amount, and fail to achieve the purpose of dilution. Because the mixed peripheral mixed gas contains a certain amount of inert gas, and the oxygen concentration of the combustion-supporting gas at the burner brick outlet is lower than the normal air oxygen concentration, under the heat release of the central flame, a stable flame is formed downstream of the peripheral gas outlet, and the flame temperature is low, which can effectively control the amount of nitrogen oxides generated. The peripheral gas gun is made of 310S material. Because there is always high-speed flammable gas in the peripheral gas riser and the peripheral nozzle, the temperature can be effectively reduced to ensure the safety of the riser and the nozzle. In the peripheral flue gas ejector, the ejected flue gas is partially heat-exchanged flue gas rather than flame, so the temperature is generally lower than 1200°C. At the same time, it is mixed with low-temperature fuel gas. The overall temperature meets the use conditions of 310S material, ensuring the safety of the peripheral gas gun components.

[0024] As described above, a central gas-injection low-nitrogen burner based on gas grading, wherein the burner flame stabilizer has mounting holes matching the number of central gas spray guns, so as to ensure that the central flue gas injection tube passes through the flame stabilizer to form a low-speed zone, thereby ensuring the stability of the central flame; the burner flame stabilizer can be of flat type or swirl type, and the setting of the swirl intensity can control the flame length; the burner flame stabilizer has mounting fasteners, and can be installed on a column such as an ignition gun to ensure stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a front view of a central gas injection low-nitrogen burner based on gas grading described in the present invention.

[0026] Figure 2 This is a top view of a central gas injection low-nitrogen burner based on gas grading described in the present invention.

[0027] Figure 3 The invention discloses a core component of a central gas injection type low nitrogen burner based on gas grading - a burner head.

[0028] Description of the accompanying figures: 1. Central gas gun; 1-1. Central nozzle; 1-2. Central gas gun riser; 1-3. Central smoke ejector; 1-4. Central nozzle positioning piece;

[0029] 2. Burner brick;

[0030] 3. Peripheral gas gun; 3-1. Peripheral nozzle; 3-2. Peripheral gas gun riser; 3-3. Peripheral smoke ejector; 3-4. Peripheral nozzle positioning piece;

[0031] 4. Burner flame stabilizer; 4-1. Flame stabilizer body; 4-2. Flame stabilizer mounting fasteners;

[0032] 5. Air inlet bellows; 5-1. Bellows body; 5-2. High temperature resistant insulation layer; 5-3. Combustion air inlet; 5-4. Mounting flange; 5-5. Bellows tube insulation layer;

[0033] 6. Gas collector; 6-1. Collector; 6-2. Fuel gas inlet;

[0034] 7. Ignition gun assembly; 8. Fire detection and ignition device. DETAILED DESCRIPTION

[0035] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] The embodiment of the present application discloses a central gas injection type low nitrogen burner based on gas staging, in order to reduce the generation of nitrogen oxides and the safety of the burner structure, such as Figure 1 As shown, it includes a core structure - a burner head, including a central gas gun 1, a burner brick 2, a peripheral gas gun 3, and a burner flame stabilizer 4. And other components matching the burner head include an air inlet wind box 5, a gas collector 6, an ignition gun (or a pilot lamp) assembly 7, and a fire detection and ignition device 8, wherein the fire detection and ignition device 8 is optional. The air inlet wind box 5 contains a thermal insulation layer.

[0037] The burner brick 2 is annular in shape, and its internal space forms a combustion-supporting air channel. The burner brick 2 passes through the furnace bottom castable and extends into the furnace bottom castable, and the furnace bottom castable is a furnace. One end of the peripheral gas gun 3 extends into the furnace bottom castable and is located outside the burner brick 2, and the other end is located outside the furnace. One end of the central gas gun 1 extends into the furnace bottom castable and extends into the burner brick 2 from the outside of the burner brick 2, and the other end is located outside the furnace. The gas collector 6 includes a collector 6-1 and a fuel gas inlet 6-2. The collector 6-1 is connected to the ends of the peripheral gas gun 3 and the central gas gun 1 located outside the furnace, and the fuel gas inlet 6-2 is connected to the collector 6-1 to pass gas into the peripheral gas gun 3 and the central gas gun 1. The air inlet wind box 5 is arranged outside the furnace bottom castable and connected to the combustion-supporting air channel, and is used to pass combustion-supporting air into the combustion-supporting air channel. The collector 6-1 is located outside the air inlet wind box 5. The burner flame stabilizer 4 is arranged in the burner nozzle brick 2, one end of the ignition gun (or ever-burning lamp) assembly 7 is located outside the air inlet wind box 5, and the ignition part of the other end is connected to the burner flame stabilizer 4. The ignition part of the ignition gun (or ever-burning lamp) assembly 7 extends out of the end surface of the burner flame stabilizer 4, and is used to ignite the central mixed gas sprayed from the central gas gun 1. When the fire detection and ignition device 8 is optionally set, the fire detection and ignition device 8 is installed on the ignition gun, which is used to monitor the ignition of the flame and to ignite the ignition gun (or ever-burning lamp) gas.

[0038] It should be noted that in this embodiment, the central gas gun 1 and the peripheral gas guns 3 are arranged outside the air inlet bellows 5 and are connected to the gas collector 6. The central gas gun 1 and the peripheral gas guns 3 can also be arranged in the air box tube insulation layer 5-5; similarly, the gas collector 6 can be arranged below the air inlet bellows 5, directly welded to the central gas gun 1 and the peripheral gas guns 3 or softly connected with a metal hose. The above achieves the same purpose through changes in the structural form and is considered equivalent to the present embodiment. The specific structure of the air inlet bellows 5 is not shown in this embodiment, but it does not mean that the air inlet bellows 5 of the present invention does not have an air distribution and guide device. The description of each component in this embodiment is only a way of expression. When the same function is achieved, it is considered equivalent. For example, the "central nozzle" is only a nozzle whose function is to spray gas. The sprayed gas enters the middle flame area to ignite and stabilize the main flame.

[0039] It should be noted that the key point of the present invention is that the flame that ignites the main flame and stabilizes the flame adopts the gas-injected smoke technology, so it is not limited to two-stage or multi-stage gas classification, or equivalent variations.

[0040] It should be noted that the present invention is applicable to fuel gas with a fuel gas pressure higher than 5 kPa, and is not limited to a specific fuel gas.

[0041] like Figure 2and Figure 3 As shown, according to the principle of gas ejector, the central gas gun 1 is designed as an ejection structure. In this embodiment, the central gas gun 1 is composed of a central gas gun riser 1-2 extending into the furnace, a central nozzle 1-1, a central flue gas ejection pipe 1-3 and a central nozzle positioning piece 1-4. One end of the central gas gun riser 1-2 is connected to the central nozzle 1-1 and exposed in the furnace outside the burner brick; a part of the central flue gas ejection pipe 1-3 is exposed in the furnace outside the burner brick 2 and is coaxial with the axis of the central nozzle 1-1, and the other part of the central flue gas ejection pipe 1-3 passes through the burner brick 2 and extends into the combustion-supporting air channel; the outlet of the central flue gas ejection pipe 1-3 is parallel to the outlet of the burner brick 2; wherein, the central nozzle 1-1 is a single-spray hole type. The end of the central gas gun riser 1-2 exposed in the furnace part forms an angle c toward the axis direction of the burner brick 2, and the angle ranges from 40° to 60°, and 45° is preferred in this embodiment; the central gas gun riser 1-2 is coaxially welded with the central nozzle 1-1; each central nozzle 1-1 has a spray hole, and the spray hole of the central nozzle 1-1 is coaxial with the inlet end of the central flue gas ejection pipe 1-3, and the end face distance is -20mm to 30mm (- indicates that the central nozzle 1-1 is inserted into the central flue gas ejection pipe, and -20mm ... -1 is inserted into the central flue gas ejection tube 1-3 by 20mm); the central nozzle 1-1 and the central flue gas ejection tube 1-3 are positioned and fixed by the central nozzle positioning piece 1-4, and the fixing method is welding. Specifically, three uniformly distributed central nozzle positioning pieces 1-4 are arranged along the circumference of the central nozzle 1-1, one end of the central nozzle positioning piece 1-4 is welded to the central gas gun riser 1-2, and the other end is welded to the central flue gas ejection tube 1-3. The diameter of the central flue gas ejection tube 1-3 is 1-4 times the diameter of the central gas gun riser 1-2. Through the above arrangement, there is a gap between the central nozzle 1-1 and the central flue gas ejection tube 1-3. When the central nozzle 1-1 injects gas, the flue gas is injected into the central flue gas ejection tube 1-3 through the gap. The central flue gas ejector tube 1-3 passes through the burner brick 2 and enters the combustion air channel, passing through an angle b (the sum of which and the angle c is 180°), to form an angle parallel to the combustion air channel, which is 135° in this embodiment; the material of the central gas gun 1 is 310S high-temperature resistant stainless steel; the number of central gas guns 1 is determined by the heat release load of the burner, ranging from 3 to 24, and 4 are preferred in this embodiment.

[0042] The distance from the outlet of the central flue gas ejector tube 1-3 to the end face of the burner flame stabilizer 4 is L3. The size of L3 is related to the aerodynamic parameters and physicochemical properties of the fuel, and its range is 20mm to 50mm to improve the flame stabilization effect. In this embodiment, L3 is 50mm; the distance from the outlet of the central flue gas ejector tube 1-3 to the end of the burner nozzle brick 2 inside the furnace bottom castable is L4. The size of L4 is related to the aerodynamic parameters and physicochemical properties of the fuel, and its range is 100mm to 200mm to improve the flame stabilization effect. In this embodiment, L4 is 150mm.

[0043] The high-speed airflow formed after the central gas passes through the central nozzle 1-1 is ejected into the central flue gas ejector 1-3. Under the action of the high-speed airflow, the high-temperature flue gas in the furnace is sucked into the central flue gas ejector 1-3 together with the central gas to be mixed and move forward to form a central mixed gas. The central mixed gas begins to burn when it is ejected from the outlet of the central flue gas ejector 1-3.

[0044] The height of the peripheral gas gun 3 can be higher or lower than the outlet of the burner brick 2; when the height of the peripheral gas gun 3 is higher than the outlet of the burner brick 2, the height of the peripheral gas gun 3 is higher than the part of the outlet of the burner brick 2, so that the flame generated by the combustion of the central gas gun 1 will not directly burn on the body of the peripheral gas gun 3; when the height of the peripheral gas gun 3 is lower than the outlet of the burner brick 2, the difference should not be too large, otherwise after the mixed gas diffuses, part of the mixed gas is disturbed by the furnace flue gas flow field and deviates from the flame zone, and cannot meet and burn with the combustion-supporting gas, forming unburned gas.

[0045] The burner brick 2 has holes or grooves matching the number of central gas spray guns so as to realize the arrangement of the central flue gas ejection pipe of the central gas spray gun; the burner brick is made of LZ60 to LZ75 inorganic material, which can withstand temperatures up to 1650°C and be used for a long time; the burner brick 2 is designed as a sudden expansion structure from the air inlet to the outlet below the hole or groove of the central flue gas ejection pipe.

[0046] In this embodiment, the burner brick 2 adopts a multi-petal assembly structure. During installation, the central flue gas ejector tube 1-3 is first inserted into the corresponding hole or groove. After positioning, the central nozzle 1-1 and the central flue gas ejector tube 1-3 are positioned and fixed by the central nozzle positioning piece 1-4, and the fixing method is welding.

[0047] like Figure 2 and Figure 3As shown, in this embodiment, the peripheral gas gun 3 is composed of a peripheral gas gun riser 3-2 extending into the furnace, a peripheral nozzle 3-1, a peripheral flue gas ejector 3-3 and a peripheral nozzle positioning sheet 3-4. The end of the peripheral gas gun riser 3-2 exposed in the furnace is coaxially welded with the peripheral nozzle 3-1; the peripheral flue gas ejector 3-3 is exposed in the furnace outside the burner brick 2, and the peripheral flue gas ejector 3-3 can be parallel to the burner brick outlet, or form an angle of 0-30°, facing the burner brick outlet axis; wherein, the peripheral nozzle is a single-spray hole type. Each peripheral nozzle 3-1 has a spray hole, and the spray hole of the peripheral nozzle 3-1 is coaxial with the inlet end of the peripheral smoke ejector tube 3-3, and the end face distance is -20mm to 30mm (-20mm means that the peripheral nozzle 3-1 is inserted into the peripheral smoke ejector tube 3-3); the peripheral nozzle 3-1 and the peripheral smoke ejector tube 3-3 are positioned and fixed by the peripheral nozzle positioning piece 3-4, and the fixing method is welding. The outlet angle a of the peripheral smoke ejector tube is 0 in this embodiment, that is, the outlet is parallel to the air flow at the burner brick outlet; the material of the peripheral gas gun 3 is 310S high temperature resistant stainless steel; the number of peripheral gas guns 3 is determined by the burner load, ranging from 3 to 24, and 4 are preferably selected in this embodiment, and in this embodiment, the central gas gun 1 and the peripheral gas gun 3 are staggered in the circumferential direction.

[0048] In another embodiment, the outlet of the peripheral flue gas ejector can also be bent toward the center of the burner brick 2. At this time, the angle between the axis of the peripheral flue gas ejector outlet and the direction of the combustion air blowing is 0-30°. After the peripheral gas passes through the peripheral nozzle 3-1, a high-speed airflow is formed and ejected into the peripheral flue gas ejector 3-3. Under the action of the high-speed airflow, the high-temperature flue gas in the furnace is sucked into the peripheral flue gas ejector 3-3 together with the peripheral gas to be mixed and advance to form a peripheral mixed gas. Since the peripheral gas gun 3 is arranged outside the burner brick 2, and the burner brick 2 has a certain thickness, the minimum distance between the axis of the peripheral gas gun 3 and the inner wall of the burner brick 2 is not less than 30mm. In this embodiment, L5 is 60mm. After the peripheral mixed gas is ejected, it can contact the combustion gas (low oxygen content) later. The peripheral mixed gas has a certain time to diffuse, the flame will be elongated, and the combustion reaction will be weakened. When the combustion reaction is weakened too much, it is beneficial to maintain its stable combustion by bending the outlet of the peripheral flue gas ejector toward the center of the burner brick 2.

[0049] The burner flame stabilizer 4 has mounting holes matching the number of the central gas spray guns to ensure that the central flue gas ejection tube passes through the burner flame stabilizer 4 to form a low-speed zone to ensure the stability of the central flame; the flame stabilizer can be a flat plate type or a swirl type.

[0050] In this embodiment, the burner flame stabilizer 4 is composed of a flame stabilizer body 4-1 and a flame stabilizer mounting fastener 4-2. After the burner brick 2 and the central flue gas ejector tube 1-3 are installed, the burner flame stabilizer 4 is positioned and fixed to the ignition gun through the flame stabilizer mounting fastener 4-2.

[0051] In this embodiment, a technical solution for secondary staged combustion of gas is disclosed, in which a sufficient amount of combustion-supporting air is mixed and burned in the air duct inside the burner brick 2 with the central mixed gas ejected from the central flue gas ejection pipe 1-3, and the high-temperature burned flue gas (formed by the mixed combustion of the central mixed gas and part of the combustion-supporting air in the air duct inside the burner brick 2) and the combustion-supporting air that does not participate in the reaction are mixed to form a combustion-supporting gas (oxygen concentration is less than 21%), which is mixed and burned with the peripheral mixed gas ejected from the peripheral flue gas ejection pipe.

[0052] In this embodiment, the combustion air enters the burner brick 2 from the combustion air inlet 5-3 through the air inlet wind box 5, reduces the wind speed at the sudden expansion position of the burner brick 2, and forms a corner vortex low-speed zone at the sudden expansion position, preventing the combustion air from entering the furnace from the burner brick 2 at the installation hole position of the central flue gas ejector 1-3.

[0053] In this embodiment, the central gas forms a high-speed airflow after passing through the central gas riser 1-2 and the central nozzle 1-1, and is ejected into the central flue gas ejector 1-3. Under the action of the high-speed airflow, the high-temperature flue gas in the furnace is sucked into the central flue gas ejector 1-3 along with the central gas, mixed and moved forward to form a central mixed gas. The combustion-supporting air passes through the flame stabilizer body 4-1 and is mixed with the central mixed gas ejected from the central flue gas ejector 1-3 to burn. Because the central mixed gas ejected from the central flue gas ejector 1-3 contains inert gas, the combustion intensity is greatly weakened, and the flame temperature is reduced to effectively control the generation of nitrogen oxides in the central flame. Under the action of the flame stabilizer body 4-1, the central flame forms a temperature-stationary flame, which ignites the main flame of the peripheral gas.

[0054] In this embodiment, the peripheral gas passes through the peripheral gas riser 3-2 and the peripheral nozzle 3-1 to form a high-speed airflow, which is injected into the peripheral flue gas ejector 3-3. Under the action of the high-speed airflow, the high-temperature flue gas in the furnace is sucked into the peripheral flue gas ejector 3-3 together with the peripheral gas to be mixed and move forward to form a peripheral mixed gas. Under the action of the burner brick 2, the central flame and the peripheral flame are separated at the root, which helps to delay the mixing time of the peripheral flame. In this way, after the peripheral mixed gas is ejected, it has a certain time to diffuse and stretch, thereby weakening the combustion reaction. At the same time, the peripheral mixed gas diluted by the inert gas reduces the intensity of the combustion reaction, forming a lower temperature space, thereby reducing the generation of nitrogen oxides in the peripheral flame.

[0055] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0056] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A central gas injection low nitrogen burner based on gas staging, characterized in that: The invention comprises a central gas gun (1), a burner brick (2), a peripheral gas gun (3) and a burner flame stabilizer (4); the burner brick (2) is cylindrical, the cylindrical burner brick (2) passes through the furnace bottom castable and extends into the inner side of the furnace bottom castable, and the inner side of the furnace bottom castable is a furnace chamber; one end of the central gas gun (1) is located outside the furnace bottom castable, and the other end of the central gas gun (1) penetrates into the furnace bottom castable and penetrates from the outer side of the burner brick (2) into the inner side space of the burner brick (2); One end of the peripheral gas gun (3) is located outside the furnace bottom castable, and the other end of the peripheral gas gun (3) penetrates into the furnace bottom castable and is located outside the burner brick (2); The ends of the central gas gun (1) and the peripheral gas gun (3) located outside the furnace bottom castable are both used to introduce fuel gas, and the end of the cylindrical burner brick (2) located outside the furnace bottom castable is connected to the air inlet box (5), and the air inlet box (5) is used to introduce combustion-supporting air into the burner brick (2); The burner flame stabilizer (4) is arranged in the burner nozzle brick (2).

2. A central gas injection low nitrogen burner based on gas staging according to claim 1, characterized in that: Along the air inlet direction from the air inlet wind box (5) to the inside of the burner brick (2), the burner brick (2) has a first cavity and a second cavity in sequence, the diameter of the first cavity is smaller than the diameter of the second cavity, and the first cavity and the second cavity form a sudden expansion structure; the central gas gun (1) extends into the second cavity.

3. A central gas injection low nitrogen burner based on gas staging according to claim 1, characterized in that: The central gas gun (1) comprises a central gas gun riser (1-2), a central nozzle (1-1), a central smoke ejector pipe (1-3) and a plurality of central nozzle positioning pieces (1-4); one end of the central gas gun riser (1-2) is located outside the furnace bottom castable, the other end extends into the inside of the furnace bottom castable and the end is bent and connected to the central nozzle (1-1); one end of the central smoke ejector pipe (1-3) is exposed in the furnace chamber outside the burner brick (2) and is connected to the axis of the central nozzle (1-1). The central flue gas ejector pipe (1-3) is coaxial with the burner brick (2), and the other end thereof passes through the burner brick (2) and extends into the combustion-supporting air channel and is parallel to the flow direction of the combustion-supporting air. A plurality of central nozzle positioning pieces (1-4) are connected between the central nozzle (1-1) and the end of the central flue gas ejector pipe (1-3) exposed in the furnace outside the burner brick (2), so that a gap is formed between the central nozzle (1-1) and the central flue gas ejector pipe (1-3), and flue gas is ejected into the central flue gas ejector pipe (1-3) from the gap.

4. A central gas injection low nitrogen burner based on gas staging according to claim 3, characterized in that: The angle c between the central smoke ejector pipe (1-3) located on the outer side of the burner brick (2) and the flow direction of the combustion air is 40°-60°.

5. The central gas injection type low nitrogen burner based on gas staging according to claim 3 is characterized in that: The distance from the outlet of the central smoke ejector tube (1-3) to the end face of the burner flame stabilizer (4) is L3, and the range of L3 is 20 mm to 50 mm.

6. The central gas injection type low nitrogen burner based on gas staging according to claim 3 is characterized in that: The distance from the outlet of the central flue gas ejector pipe (1-3) to the end of the burner nozzle brick (2) inside the furnace bottom castable is L4, and the range of L4 is 100 mm to 200 mm.

7. The central gas injection type low nitrogen burner based on gas staging according to claim 3 is characterized in that: The spray hole of the central nozzle (1-1) is coaxial with the inlet end of the central smoke ejector tube (1-3), and the end surface distance between the end surface of the central nozzle (1-1) and the inlet end of the central smoke ejector tube (1-3) is -20 mm to +30 mm; wherein - indicates that the central nozzle (1-1) is inserted into the central smoke ejector tube (1-3), and + indicates that there is a gap between the end of the central nozzle (1-1) and the central smoke ejector tube (1-3) in the axial direction of the central nozzle (1-1).

8. The central gas injection type low nitrogen burner based on gas staging according to claim 1 is characterized in that: The minimum distance between the axis of the peripheral gas gun (3) and the inner wall of the burner brick (2) is not less than L5, and the value of L5 is not less than 30 mm.

9. The central gas injection type low nitrogen burner based on gas staging according to claim 1 is characterized in that: The peripheral gas gun (3) comprises a peripheral gas gun riser (3-2), a peripheral nozzle (3-1), a peripheral smoke ejector pipe (3-3) and a plurality of peripheral nozzle positioning pieces (3-4); one end of the peripheral gas gun riser (3-2) is located outside the furnace, and the other end extends into the furnace and is connected to the peripheral nozzle (3-1); the spray hole of the peripheral nozzle (3-1) is coaxial with the inlet end of the peripheral smoke ejector pipe (3-3); the peripheral nozzle (3-1) and the peripheral smoke ejector pipe (3-3) are connected via a plurality of peripheral nozzle positioning pieces (3-4) so ​​that there is a gap between the peripheral nozzle (3-1) and the peripheral smoke ejector pipe (3-3); smoke in the furnace is ejected from the gap into the peripheral smoke ejector pipe (3-3).

10. A central gas injection type low nitrogen burner based on gas staging according to claim 9, characterized in that: The angle between the axis of the peripheral smoke ejector pipe outlet and the direction of combustion air blowing is 0, or the peripheral smoke ejector pipe outlet is bent toward the center of the burner brick (2), at which time the angle between the axis of the peripheral smoke ejector pipe outlet and the direction of combustion air blowing is 0-30°.

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