Combustor low-nitrogen center gun and low-nitrogen combustor
By designing a low-nitrogen central gun for gas-grade low-nitrogen burners, changing the combustion method and controlling the excess mixture coefficient of gas and air, the problem of difficult reduction of nitrogen oxide emissions in existing gas-grade low-nitrogen burners is solved, and lower nitrogen oxide emissions and flame stability are achieved.
Patent Information
- Application Number
- CN202411905354.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-03-21
AI Technical Summary
Existing gas-grade low-nitrogen burners are difficult to meet stricter nitrogen oxide emission standards, especially in gas-grade low-nitrogen burners, where nitrogen oxide emissions are still high.
A low-nitrogen central gun is designed, by changing the combustion method, it changes from diffusion combustion to over-premix combustion, and a gas dispersion nozzle and a fire stabilizing plate are provided in the combustion air channel to control the excess mixing coefficient of gas and air to be within the range of 80% to 150% to reduce the amount of nitrogen oxide generation in the central gun.
It effectively reduces the nitrogen oxide emissions of the burner, achieves a lower nitrogen oxide emission level, and improves the stability of the flame and reduces the renovation costs.
Smart Images
Figure CN119665231A_ABST
Abstract
Description
Technical Field
[0001] The invention designs a burner low-nitrogen central gun, which is suitable for a gas-staged low-nitrogen burner and can reduce the nitrogen oxide emission of the burner. Background Art
[0002] As my country's environmental protection emission standards become more and more stringent, the nitrogen oxide emission limit is 200mg / m 3 Gradually reduce to 100 mg / m 3 , 80mg / m 3 , even strict to 50mg / m 3 Even 30 mg / m 3 Many low-nitrogen burners can no longer meet the requirements, and now we need low-nitrogen oxygen burners with lower emissions. There are two types of low-nitrogen burners: air-staged and gas-staged. There are many factors that affect nitrogen oxide emissions, including fuel composition, hot air temperature, furnace temperature, air oxygen content, etc. Usually, air-staged low-nitrogen burners emit 100mg / m 3 Horizontal, gas-staged low nitrogen burner emission at 50mg / m 3 Normally, nitrogen oxide emissions can be further halved by increasing the external recirculation of flue gas, but this method requires sacrificing 5% to 10% of the thermal efficiency. Summary of the invention
[0003] The technical problem solved by the present application is: to overcome the deficiencies of the prior art and provide a low-nitrogen center gun for a gas-staged low-nitrogen burner, to quickly and evenly distribute the gas from the center gun into the combustion-supporting air, and in the combustion-supporting air channel of the burner brick, the highest gas concentration is in the range of gas concentration corresponding to the excess air coefficient of 80% to 150% after the gas and air are mixed (this range takes into account both good flame stability and lower nitrogen oxide production), and the fire stabilizing plates are designed and arranged to form a low-speed zone and a reflow zone of the gas-air mixture to control the ignition point of the center gun gas, reduce the nitrogen oxide production of the center gun of the gas-staged low-nitrogen burner, and the burner can obtain lower nitrogen oxide emissions.
[0004] At present, most of the low-nitrogen burners in use are gas-staged low-nitrogen burners. This patent is also optimized for gas-staged low-nitrogen burners. A burner low-nitrogen center gun in this patent is optimized for the center gun of gas-staged low-nitrogen burners. By changing the combustion mode of the center gun of the standard gas-staged low-nitrogen burner and taking advantage of the characteristics of more wind and less fuel in the center flame area, the diffusion combustion of the center gun gas is changed to premixed combustion, which can significantly reduce the maximum temperature of the center flame, thereby reducing the generation of nitrogen oxides in the center gun and reducing the nitrogen oxide emissions of the burner.
[0005] Explanation 1: The theoretical air-fuel ratio of the gas is defined as A (i.e. A = the volume of air required for complete combustion of the gas / the volume of fuel). When the volume of the gas is 1, the volume of air is 1*(A+A*80%). At this time, the concentration of the gas is 1 / [1+1*(A+A*80%)], i.e. the gas concentration with an excess air coefficient of 80% is 1 / (1+A+A*80%); similarly, the gas concentration with an excess air coefficient of 150% is 1 / (1+A+A*150%).
[0006] Explanation 2: For common natural gas fuels, the flame temperature of an excess air coefficient of 80% is ~1400°C, and the design of low-nitrogen burners generally recognizes that the nitrogen oxide generation rate is sufficiently low at a temperature below 1400°C; the flame temperature of an excess air coefficient of 150% is ~900°C, and the gas can be reliably ignited at a temperature of ~600°C. A flame temperature exceeding 900°C can maintain reliable ignition of the gas.
[0007] The technical solutions provided by this application are as follows:
[0008] A low-nitrogen center gun of a burner comprises a gas vertical pipe, a gas horizontal pipe, a gas dispersion nozzle and a gas fire stabilizing plate. A plurality of gas dispersion nozzles are arranged on the gas horizontal pipe, and each gas dispersion nozzle has a plurality of spray holes. The gas fire stabilizing plate is located in the gas spraying direction of the gas dispersion nozzle. The gas vertical pipe is connected with the gas horizontal pipe for inputting gas.
[0009] The angle between the axis of each nozzle of the gas dispersion nozzle and the direction of the combustion-supporting air does not exceed 30°; to avoid the formation of a reflow zone due to a large angle between the gas and the combustion-supporting air, premature ignition when the gas concentration is too high, resulting in excessive nitrogen oxide emissions.
[0010] The gas fire stabilizing plate is connected to the gas cross pipe through a gas fire stabilizing plate fixing rod, and the spacing between the gas fire stabilizing plate and the gas dispersion nozzle is obtained through numerical simulation calculation to ensure that the maximum concentration of the gas after the gas and the combustion-supporting air are mixed within the range of the gas concentration corresponding to the excess air coefficient of 80% to 150% after the gas and air are mixed.
[0011] In order to ensure that the gas of the center gun can ignite near the gas fire stabilizing plate and form a stable flame in the low-speed zone and recirculation zone formed downstream of the gas fire stabilizing plate, a permanent lamp is designed and arranged at a position roughly flush with the gas fire stabilizing plate (within the range of -20 to +20 mm) and horizontally staggered with the gas fire stabilizing plate (within the range of 30 to 50 mm). The specific position of the permanent lamp is to ignite the center gun with the center gun flame close to and higher than the gas fire stabilizing plate. If the position of the permanent lamp is too low, the center gun gas will be ignited too early, resulting in a high amount of nitrogen oxides produced. If the position of the permanent lamp is too high, the center gun gas flame will be away from the low-speed zone and recirculation zone formed by the gas fire stabilizing plate, which will cause the center gun flame to jump or even flame out.
[0012] A conventional gas-fired staged low-nitrogen burner comprises a burner brick, a bellows assembly, a peripheral gun, a pilot light and a common center gun. The burner brick is embedded in the refractory layer of the furnace bottom. The burner brick is provided with a square hole connecting the inside and outside of the furnace wall. The bellows assembly is connected to the outside of the furnace wall and connected to one end of the burner brick. The pilot light and the common center gun both pass through the bellows assembly and extend into the square hole of the burner brick. The peripheral gun passes through the burner brick and extends into the furnace wall. The ignition end of the pilot light is located on the side of the common center gun nozzle facing the inside of the furnace wall.
[0013] The low-nitrogen burner using this patented low-nitrogen center gun replaces the ordinary center gun of the conventional gas-fired graded low-nitrogen burner with this patented low-nitrogen center gun, the gas cross pipe is in the square hole of the burner brick close to the bellows side, the gas fire stabilizing plate is in the square hole of the burner brick close to the furnace side, and the ignition end of the pilot lamp is adjusted to the side of the gas fire stabilizing plate of the low-nitrogen center gun, the vertical distance between the ignition end of the pilot lamp outlet and the gas fire stabilizing plate of the low-nitrogen center gun is in the range of -20mm-+20mm, and the pilot lamp outlet and the gas fire stabilizing plate of the low-nitrogen center gun are horizontally staggered by 30-50mm.
[0014] The gas horizontal pipe and the gas fire stabilizing plate are both perpendicular to the air supply direction of the combustion-supporting air in the burner brick.
[0015] Along the flow direction of the combustion-supporting air in the burner brick, the gas fire stabilizing plate is located just downstream of the gas dispersion nozzle. The gas fire stabilizing plate is located at a position where the maximum gas concentration is in the gas concentration range corresponding to the air excess coefficient of 80% to 150%.
[0016] In summary, this application at least includes the following beneficial technical effects:
[0017] The advantages of the present invention are: (1) For low-nitrogen burners with gas grading, the purpose of reducing nitrogen oxide emissions from the entire burner can be achieved by replacing the central gun and adding a fire stabilization design at a suitable position in the air passage of the burner brick; other accessories of the original burner can be reused, which can greatly reduce the cost of transformation. (2) For the bottom burner of the cracking furnace, when operating at low load and high oxygen content in the original coking hot standby condition, because the oxygen content in the furnace increases, the peripheral guns of the burner have deviated from low-nitrogen and oxygen combustion, and the central gun itself has no nitrogen reduction effect, and the nitrogen oxide emissions will exceed 200mg / m 3 Therefore, it is necessary to increase the nitrogen reduction steam to reduce the nitrogen oxide emission of the coking hot standby condition to 100mg / m 3 If the central gun solution of this patent is used, when the original charring hot standby condition is running at low load and high oxygen content, the peripheral gun gas is cut off and only the central gun gas is turned on, so that the charring hot standby condition does not need to reduce nitrogen and steam nitrogen oxide emissions to 60mg / m 3(3) Since a flame stabilizing plate is added to the center gun, the ignition point of the center gun flame can be precisely controlled, flame stability can be provided, and flame jitter caused by insufficient negative pressure in the furnace when the low-nitrogen burner is overloaded can be eliminated. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a side view of a conventional gas-fired staged low-nitrogen burner;
[0019] Figure 2 A top view of a conventional gas-staged low-nitrogen burner;
[0020] Figure 3 A side view of a gas-fired staged low-nitrogen burner using a low-nitrogen center gun;
[0021] Figure 4 A top view of a gas-fired staged low-nitrogen burner using a low-nitrogen center gun;
[0022] Figure 5 It is a low nitrogen center gun (including dispersion nozzle and fire stabilizing plate).
[0023] Explanation of the accompanying figures: 1. Burner brick; 2. Bellows assembly; 3. Peripheral gun; 4. Pilot lamp; 5. Ordinary center gun; 6. Low-nitrogen center gun; 11. Pilot lamp flame; 12. Peripheral gun flame; 13. Ordinary center gun flame; 14. Low-nitrogen center gun flame; 21. Gas vertical pipe; 22. Gas horizontal pipe; 23. Gas dispersion nozzle; 24. Gas fire stabilizing plate; 25. Gas fire stabilizing plate fixing rod. DETAILED DESCRIPTION
[0024] 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.
[0025] The embodiment of the present application discloses a burner low-nitrogen center gun, which is suitable for any gas-staged low-nitrogen-oxygen burner. It changes the center gas diffusion combustion mode to a premixed combustion mode, reduces the amount of nitrogen oxides produced by the center gas flame, and further reduces the nitrogen oxide emissions of the low-nitrogen burner.
[0026] like Figure 1 , Figure 2This is a structural diagram (side view and top view) of a conventional gas staged burner. The burner consists of a burner brick 1, a bellows assembly 2, a peripheral gun 3, a pilot lamp 4, and a common center gun 5. The combustion-supporting air enters from the air port of the bellows assembly 2 and exits from the square hole of the burner brick 1. The peripheral gun 3 passes through the burner brick 1 and sprays from the outside of the burner brick 1 to the square hole of the burner brick 1. The common center gun 5 is in the square hole of the burner brick 1. When the burner is working, three flames are produced: a pilot lamp flame 11, a peripheral gun flame 12, and a common center gun flame 13. The pilot lamp flame 11 can ignite the peripheral gun flame 12 and the common center gun flame 13 at the same time.
[0027] like Figure 3 , Figure 4 The side view and top view of the structure diagram of the gas staged burner using the low nitrogen center gun of the patent, the burner consists of a burner brick 1, a bellows assembly 2, a peripheral gun 3, a pilot light 4, and a low nitrogen center gun 6. The combustion-supporting air enters from the air port of the bellows assembly 2 and exits from the square hole of the burner brick 1. The peripheral gun 3 passes through the burner brick 1 and sprays from the outside of the burner brick 1 to the square hole of the burner brick 1. The low nitrogen center gun 6 is in the square hole of the burner brick 1. When the burner is working, three flames are produced: the pilot light flame 11, the peripheral gun flame 12, and the low nitrogen center gun flame 14. The pilot light flame 11 can ignite the peripheral gun flame 12 and the low nitrogen center gun flame 14 at the same time.
[0028] Figure 5It is a low-nitrogen center gun, including a gas vertical pipe 21, a gas horizontal pipe 22, a gas dispersion nozzle 23, a gas fire-stabilizing sheet 24, and a gas fire-stabilizing sheet fixing rod 25. The center gun gas enters from the gas vertical pipe 21, and is distributed to multiple gas dispersion nozzles 23 in the gas horizontal pipe 22. Each gas dispersion nozzle 23 sprays the gas out at a small angle through multiple small holes, and mixes with the air in the combustion-supporting air channel. When the gas has the highest concentration and the air excess coefficient is 80% to 150% after the gas and air are mixed, the gas is ignited in the range corresponding to the gas concentration (the gas concentration is too low and it is not easy to ignite, and the concentration is too high and the amount of nitrogen oxides produced is large). The low-nitrogen center gun flame is an over-premixed combustion flame. Compared with the diffusion combustion flame of the ordinary center gun, the maximum temperature of the center gun flame is significantly reduced, and the amount of nitrogen oxides generated by the center gun flame is also significantly reduced. In order to ensure that the central gun gas starts to ignite within the appropriate gas concentration range, a gas fire stabilizing plate 24 is designed at this position. The gas fire stabilizing plate 24 can be welded with a gas gun to a gas fire stabilizing plate fixing rod 25 or fixed with a burner brick. If a gas fire stabilizing plate fixing rod 25 is used, a thin rod structure with a circular cross section should be used to avoid the low-speed zone and the recirculation zone before the gas and combustion-supporting air mixture reaches the gas fire stabilizing plate 24, so that the central gas ignites in advance. The gas cross pipe 22 of the low-nitrogen central gun is placed in the combustion-supporting air channel of the burner brick near the wind inlet, and multiple gas dispersion nozzles 23 are designed on the gas cross pipe 22. Multiple nozzles and multiple spray holes can quickly disperse the gas of the central gun. At the same time, the gas dispersion nozzle 23 is designed as a plurality of small holes for small-angle spraying, and the recirculation zone and the low-speed zone are avoided near the gas dispersion nozzle 23 in the combustion-supporting air channel to prevent the gas of the central gun from igniting prematurely. Designing a reasonable position of the fire stabilizing plate is the key to achieving low emissions and flame stability of the low-nitrogen central gun.
[0029] like Figure 3It is a side view of the structural diagram of the gas staged burner using the low-nitrogen center gun of the present patent, in which the relative positions of the ever-burning lamp 4 and the low-nitrogen center gun 6 are relatively important, that is, the ignition end position of the ever-burning lamp 4 outlet is basically flush with the gas fire stabilizing strip 24 of the low-nitrogen center gun 6 in the vertical direction (in the range of -20 to +20 mm), and the ignition end position of the ever-burning lamp 4 outlet is staggered 30 to 50 mm from the gas fire stabilizing strip in the horizontal direction. The ever-burning lamp outlet is located on the side of the gas fire stabilizing strip 24 facing the furnace, and can be used to ignite the low-nitrogen center gun 6 gas and the peripheral gun 3 gas at the same time, so that the ever-burning lamp flame 11 can be at the low-nitrogen center gun 6. The gas of the low-nitrogen center gun 6 is ignited at a position above and close to the gas fire stabilizing plate 24 to form a low-nitrogen center gun flame 14, and does not directly burn the fire stabilizing plate. If this position is too low, the low-nitrogen center gun 6 gas will be ignited in advance, and the high local concentration of the center gas will lead to a large amount of nitrogen oxides produced. When the low-nitrogen center flame 14 burns to the gas fire stabilizing plate 24, it will affect the service life of the gas fire stabilizing plate 24; if this position is too high, the center gun gas will be ignited and the root of the flame will separate from the gas fire stabilizing plate 24 and cannot form a stable low-nitrogen center flame 14, which will cause the center gun to flame out or the entire burner flame to surge.
[0030] Some well-known techniques in the art are used in the process of the present invention, such as Figure 1 , Figure 2 It is a standard structure of a gas-staged low-nitrogen burner. This patent optimizes and partially improves the center gun part thereof. Designing multiple gas nozzles on the center gun is also often used on the burner. Designing a fire-stabilizing plate on the burner to increase flame stability is also often used. Using a long-burning lamp on the burner is also a standard design. The low-nitrogen center gun used in this patent changes the combustion mode of the ordinary center gun, and changes the gas diffusion combustion mode to a premixed combustion mode. The key is to utilize the characteristics of more air and less gas at the center gun position of the gas-staged low-nitrogen burner, control the excess air coefficient after the gas and air are mixed at the ignition point position, make a good structural design to stabilize the ignition point, reduce the amount of nitrogen oxides produced by the center gun gas flame, and achieve reduction in burner nitrogen oxide emissions.
[0031] The scope disclosed by the present invention includes the disclosed technology and obvious replacements, such as the gas dispersion nozzle (23). The patent drawing shows that the number of nozzles is 8, each with 6 nozzle holes, such as the number of nozzles is 4 to 16, each with 3 to 10 nozzle holes, all of which can quickly disperse the gas; the gas flame stabilizing sheet 24 can be designed as a long strip or as multiple short strips, and can also be designed as other flame stabilizing structures, such as designing a small flow gas nozzle near the flame stabilizing sheet to improve the stability of the central gas flame. Their functions are to stabilize the gas flame at a position where the excess air coefficient is in the range of 80% to 150% after the gas and air are mixed. The central gas flame is controlled; the function of the gas fire stabilizing plate fixing rod 25 is to fix the gas fire stabilizing plate 24, and it can also be changed to other forms of fixing the gas fire stabilizing plate 24, such as the gas fire stabilizing plate 24 is connected and fixed to the burner brick 1 or the burner bellows 2. No matter which fixing method is adopted, it is necessary to pay attention to the gas dispersion nozzle 23 and the gas fire stabilizing plate 24. In the space where the gas is dispersed in the air in the burner brick channel, avoid the generation of backflow areas and low-speed areas, which causes the central gas to be ignited in advance; this patent indicates that it is used for a gas-graded low-nitrogen burner with a square cross-section, and the same effect can be achieved if it is used for a gas-graded low-nitrogen burner with a circular cross-section.
[0032] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.
[0033] 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 burner low nitrogen center gun, characterized by: It comprises a gas vertical pipe (21), a gas horizontal pipe (22), a gas dispersion nozzle (23) and a gas fire stabilizing plate (24), wherein a plurality of gas dispersion nozzles (23) are arranged on the gas horizontal pipe (22), and each gas dispersion nozzle (23) has a plurality of spray holes; The gas fire stabilizing plate (24) is located downstream of the gas dispersing nozzle (23) in the gas spraying direction; The gas vertical pipe (21) is communicated with the gas horizontal pipe (22) for inputting gas.
2. A burner low nitrogen center gun according to claim 1, characterized in that: The angle between the axis of each spray hole of the gas dispersion nozzle (23) and the direction of the combustion-supporting air does not exceed 30°.
3. A burner low nitrogen center gun according to claim 1, characterized in that: A gas fire stabilizing sheet (24) is arranged downstream of the gas dispersion nozzle (23).
4. A low nitrogen burner, characterized in that: It comprises a burner brick (1), a bellows assembly (2), a peripheral gun (3), a permanent lamp (4) and a low-nitrogen central gun (6) as described in any one of claims 1 to 3, wherein the burner brick (1) is embedded in the refractory layer of the furnace bottom, the burner brick (1) is provided with a square hole connecting the inside and outside of the furnace wall, the bellows assembly (2) is connected to the outside of the furnace wall and connected to one end of the burner brick (1), the permanent lamp (4) and the low-nitrogen central gun (6) both pass through the bellows assembly (2) and extend into the square hole of the burner brick (1), and the peripheral gun (3) passes through the burner brick (1) and extends into the furnace wall; the ignition end of the permanent lamp (4) is located on the side of the gas fire stabilizing plate (24) of the low-nitrogen central gun (6) facing the inside of the furnace wall.
5. A low nitrogen burner according to claim 4, characterized in that: The height difference between the ignition end of the outlet of the pilot lamp (4) and the gas fire stabilizing plate (24) of the low nitrogen center gun (6) is within the range of -20mm-20mm, and the horizontal offset is 30-50mm.
6. A low nitrogen burner according to claim 4, characterized in that: The gas horizontal pipe (22) and the gas fire stabilizing plate (24) are both perpendicular to the air supply direction of the combustion-supporting air in the burner brick (1).
7. A low nitrogen burner according to claim 4, characterized in that: Along the flow direction of the combustion-supporting air in the burner brick (1), the gas fire stabilizing sheet (24) is located just downstream of the gas dispersion nozzle (23).
8. A low nitrogen burner according to claim 7, characterized in that: The gas fire stabilizing plate (24) is located at a position where the maximum gas concentration is within the gas concentration range corresponding to an excess air coefficient of 80% to 150% after the gas and air are mixed.