Natural gas burner and natural gas boiler capable of reducing nitrogen oxides
By introducing circulating flue gas into the natural gas burner and mixing it with air, and by using a regulating mechanism to adjust the flue gas ratio, the problem of high nitrogen oxide emissions in natural gas burners has been solved, resulting in a reduction in combustion temperature and nitrogen oxide emissions.
Patent Information
- Application Number
- CN202511308478.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-12
- Publication Date
- 2025-12-16
AI Technical Summary
Existing natural gas burners generate large amounts of nitrogen oxides during combustion, especially in the core area of the flame, leading to environmental pollution and the greenhouse effect, and existing technologies are unable to effectively reduce their emissions.
By introducing recirculated flue gas into the natural gas burner and mixing it with air and natural gas, and by using a regulating mechanism to adjust the ratio of recirculated flue gas in the intermediate delivery channel and the outer annular delivery channel, the combustion temperature in the flame core area is reduced, the oxygen content is reduced, and thus the generation of nitrogen oxides is reduced.
It effectively reduces the combustion temperature in the core flame zone, reduces nitrogen oxide emissions, optimizes the temperature field of the natural gas boiler, and enables flexible combustion control.
Smart Images
Figure CN121139964A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of burners, in particular to a natural gas burner capable of reducing nitrogen oxides and a natural gas boiler. BACKGROUND
[0002] The natural gas burner is an important combustion component in the natural gas boiler. When the natural gas burner is combusted, a large amount of nitrogen oxides, mainly NO and NO2, are generated, which are collectively referred to as NO x The highest proportion of nitrogen oxides is generated by the thermal type nitrogen oxides generated by the reaction of nitrogen in the air with oxygen under high temperature conditions. The thermal type nitrogen oxides are strongly dependent on temperature and are exponentially accelerated at high temperatures.
[0003] The flame area of the natural gas burner is generally divided into an ignition zone, a flame core zone, a flame transition zone and a flame tail zone; among them, the flame core zone has the highest temperature, about 1400-1800℃, which is the main generation zone of thermal type nitrogen oxides, and the flame in each zone generally has the highest temperature at the middle position, which is easy to produce nitrogen oxides. Nitrogen oxides are toxic to animals and plants, and are one of the main causes of acid rain, acid fog and photochemical smog. Therefore, there is an urgent need for a natural gas burner capable of reducing nitrogen oxides to solve the above problems. SUMMARY
[0004] The present application aims to overcome the above-mentioned problems, and provides a natural gas burner capable of reducing nitrogen oxides, which can effectively reduce the combustion temperature of the flame core zone, is beneficial to optimizing the temperature field in the natural gas boiler, and reduces the emission of nitrogen oxides.
[0005] The purpose of the present application is achieved by the following technical solutions:
[0006] A natural gas burner capable of reducing nitrogen oxides, comprising a pipe body, a fuel nozzle for injecting natural gas, and a combustion head for injecting mixed gas for combustion; the front end of the pipe body is provided with an air inlet, the middle part of the pipe body is provided with a circulating flue gas inlet, and the combustion head is arranged at the rear end of the pipe body; the fuel nozzle is arranged at the front end of the pipe body and inside the pipe body; wherein,
[0007] The distribution mechanism is used for distributing different proportions of circulating flue gas; the distribution mechanism comprises a distribution pipe arranged inside and coaxially with the pipe body and an adjusting mechanism connected with the distribution pipe; an intermediate conveying channel is arranged inside the distribution pipe, and a peripheral annular conveying channel is formed between the outer side wall of the distribution pipe and the inner side wall of the pipe body; the distribution pipe comprises a partition pipe and a distributor slidingly arranged at the front end of the partition pipe; the rear end of the partition pipe is connected with the combustion head; the adjusting mechanism is used for driving the distributor to move back and forth along the axis of the partition pipe; the intermediate region of the combustion head is provided with a plurality of intermediate gas injection holes in communication with the intermediate conveying channel; and the peripheral region of the combustion head is provided with a plurality of peripheral gas injection holes in communication with the peripheral annular conveying channel.
[0008] The working principle of the natural gas burner capable of reducing nitrogen oxides is as follows:
[0009] When the natural gas burner is burning, air enters the pipe body from the air inlet, and natural gas is injected into the pipe body from the fuel injection pipe; part of the flue gas generated by the natural gas burner burning enters the pipe body from the circulating flue gas inlet, and the flue gas entering the pipe body is the circulating flue gas; the air, the natural gas and the circulating flue gas are mixed to form a mixed gas in the pipe body; part of the mixed gas enters the intermediate conveying channel, is conveyed through the intermediate conveying channel, and is then injected from the intermediate gas injection holes; another part of the mixed gas enters the peripheral annular conveying channel, is conveyed through the peripheral annular conveying channel, and is then injected from the peripheral gas injection holes; the mixed gas injected from the intermediate gas injection holes and the peripheral gas injection holes burns outside the combustion head, and part of the flue gas generated by the burning enters the pipe body from the circulating flue gas inlet; by mixing the circulating flue gas with the air and the natural gas, the proportion of oxygen in the air can be reduced, so that the burning efficiency is reduced. Since the flame region is located in the intermediate region with the highest temperature and the surrounding region with a lower temperature, nitrogen oxides are easily generated in the intermediate region; by driving the distributor to move through the adjusting mechanism, when the distributor is closer to the circulating flue gas inlet, more circulating flue gas guided by the distributor enters the intermediate conveying channel, and less circulating flue gas enters the peripheral annular conveying channel, so that the proportion of circulating flue gas in the mixed gas in the intermediate conveying channel is large, and the proportion of oxygen is small, and thus the burning efficiency of the mixed gas injected from the intermediate gas injection holes is low, the burning efficiency of the intermediate region is reduced, and the generation of nitrogen oxides is further reduced. By driving the distributor to move away from the circulating flue gas inlet through the adjusting mechanism, the content of circulating flue gas entering the intermediate conveying channel can be changed, so that less circulating flue gas enters the intermediate conveying channel, and more circulating flue gas enters the peripheral annular conveying channel, so that the movement of the distributor driven by the adjusting mechanism can flexibly adjust the distribution proportion of circulating flue gas in the intermediate conveying channel and the peripheral annular conveying channel, and the distribution proportion can be flexibly adjusted according to actual needs.
[0010] In one preferred embodiment of the present application, the pipe body comprises a gas inlet pipe, a Venturi pipe and a gas outlet pipe connected in sequence; the fuel nozzle is located inside the gas inlet pipe, the circulating flue gas inlet is located on the Venturi pipe, and the combustion head is located at the end of the gas outlet pipe. By arranging the Venturi pipe, the gas flow rate can be changed, thereby facilitating the mixing of air, natural gas and circulating flue gas.
[0011] Further, the Venturi pipe comprises a converging section, a throat section and a diverging section connected in sequence, the gas inlet pipe is connected with the converging section, and the diverging section is connected with the gas outlet pipe; the circulating flue gas inlet is provided in plurality, and the plurality of circulating flue gas inlets are distributed along the circumferential direction on the throat section. In the above structure, the plurality of circulating flue gas inlets can increase the intake amount of circulating flue gas and make the mixing of air, natural gas and circulating flue gas more uniform. When the gas enters the converging section from the gas inlet pipe, the gas flow rate increases, thereby increasing the gas flow rate of the throat section, and the circulating flue gas also accelerates into the throat section, thereby improving the self-circulation ability of the circulating flue gas.
[0012] Preferably, the adjusting mechanism comprises a gas supply device, a driving gas cavity arranged between the distributor and the partition pipe, and a driving spring sleeved on the partition pipe; the gas supply device is in communication with the driving gas cavity; one end of the driving spring acts on the distributor, and the other end acts on the partition pipe. In the above structure, when it is necessary to drive the distributor to move, the gas supply device supplies gas to the driving gas cavity, and under the action of the gas pressure, the distributor is pushed to move, and the volume of the driving gas cavity also increases, and the driving spring is compressed when the distributor moves; when the gas supply device stops supplying gas, the distributor moves reversely under the elastic force of the driving spring, and the volume of the driving gas cavity decreases. Through the cooperation of the gas supply device and the driving spring, the back-and-forth movement of the distributor can be realized, thereby flexibly adjusting the distribution ratio of the circulating flue gas.
[0013] Preferably, the distributor comprises a horn pipe at the front end and a sliding pipe at the rear end; an inwardly protruding sliding ring is arranged on the inner wall of the sliding pipe; a first annular protrusion and a second annular protrusion are sequentially arranged on the outer wall of the front end of the partition pipe, and the second annular protrusion is located behind the first annular protrusion; the sliding ring is located between the first annular protrusion and the second annular protrusion and is in sliding connection with the outer wall of the partition pipe; the first annular protrusion and the second annular protrusion are both in sliding connection with the inner wall of the sliding pipe; a space surrounded by the first annular protrusion, the outer wall of the partition pipe, the sliding ring and the inner wall of the sliding pipe constitutes the driving air cavity; a space surrounded by the sliding ring, the outer wall of the partition pipe, the second annular protrusion and the inner wall of the sliding pipe constitutes the spring mounting cavity, and the driving spring is located in the spring mounting cavity. With the above structure, it is very compact, and the horn-shaped horn pipe can better guide the circulating flue gas delivered by the circulating flue gas inlet into the horn pipe, and then into the intermediate conveying channel. The sliding ring is in sliding connection with the outer wall of the partition pipe, and the first annular protrusion and the second annular protrusion are both in sliding connection with the inner wall of the sliding pipe, so that the movement of the sliding pipe is very stable, and the stability of the adjustment is improved. One end of the driving spring acts on the sliding ring, and the other end acts on the second annular protrusion.
[0014] Preferably, a limiting ring is arranged at the rear end of the sliding pipe, and when the gas supply device is not working, the limiting ring abuts against the second annular protrusion under the elastic force of the driving spring. By arranging the limiting ring, a good limiting effect can be achieved, and when the limiting ring abuts against the second annular protrusion, the horn pipe is located at the position closest to the circulating flue gas inlet.
[0015] Preferably, a sealing groove is arranged on the sliding ring, and a sealing ring is arranged in the sealing groove. The purpose is to improve the sealing between the sliding ring and the outer wall of the partition pipe.
[0016] Preferably, the fuel injection pipe is in communication with the fuel conveying pipe, and a plurality of fuel injection holes are arranged on the fuel injection pipe. The arrangement of a plurality of fuel injection holes facilitates the injection of natural gas into the pipe body and enables the natural gas and air to be fully mixed.
[0017] Preferably, the axis of the circulating flue gas inlet is arranged to be inclined towards the direction close to the inlet pipe. The purpose is to make the gas outlet direction of the circulating flue gas inlet closer to the flow direction of the mixed gas, thereby improving the conveying efficiency of the circulating flue gas.
[0018] The natural gas boiler comprises a boiler drum, a furnace, a back-draft chamber, a front flue, a rear flue and a natural gas burner; the furnace and the back-draft chamber are arranged in the boiler drum, the front flue is arranged at the front end of the boiler drum, and the rear flue is arranged at the rear end of the boiler drum; the back-draft chamber is arranged at the rear end of the furnace and communicates with the furnace, the front flue and the back-draft chamber communicate through a first return flue, the front flue and the rear flue communicate through a second return flue, and the combustion head of the natural gas burner is arranged at the front end of the furnace; the rear flue communicates with the circulating flue gas inlet through a circulating flue gas pipeline.
[0019] The mixed gas sprayed from the combustion head is combusted in the furnace, the furnace heats the water in the boiler drum to generate steam, and the high-temperature flue gas generated by the furnace passes through the back-draft chamber, the first return flue, the front flue, the second return flue and the rear flue in sequence, the first return flue and the second return flue can further heat the water in the boiler drum, the temperature of the flue gas entering the rear flue is reduced, part of the flue gas is discharged from the flue gas outlet of the rear flue, and part of the flue gas (circulating flue gas) enters the circulating flue gas inlet through the circulating flue gas pipeline, and then enters the pipe body of the natural gas burner from the circulating flue gas inlet, so that the emission of nitrogen oxides is reduced.
[0020] The upper end of the rear flue is provided with a flue gas outlet, and a fan is arranged at the flue gas outlet. By arranging the fan, the exhaust size of the flue gas outlet can be controlled.
[0021] Compared with the prior art, the present application has the following beneficial effects:
[0022] 1. The natural gas burner in the present application can make the flue gas (circulating flue gas) generated during combustion enter the pipe body from the circulating flue gas inlet, and air, natural gas and circulating flue gas are mixed in the pipe body to form mixed gas, which is sprayed from the combustion head for combustion. By mixing the circulating flue gas with air and natural gas, the proportion of oxygen in the air can be reduced, the combustion efficiency is reduced, the combustion temperature of the flame core area is effectively reduced, the temperature field in the natural gas boiler is optimized, and the emission of nitrogen oxides is reduced.
[0023] 2. The natural gas burner in the present application has the following advantages: the flame area is located in the middle area with the highest temperature, the temperature around the middle area is relatively low, and nitrogen oxides are prone to be generated in the middle area. The distributor is driven to move by the adjusting mechanism, when the distributor is closer to the circulating flue gas inlet, more circulating flue gas guided by the distributor enters the middle conveying channel, and less circulating flue gas enters the peripheral annular conveying channel. Therefore, the proportion of circulating flue gas in the mixed gas in the middle conveying channel is large, and the proportion of oxygen is small, so that the combustion efficiency of the mixed gas sprayed from the middle gas injection hole is low, the combustion efficiency of the middle area is reduced, and the generation of nitrogen oxides is further reduced.
[0024] 3. The natural gas burner in this invention can change the content of circulating flue gas entering the intermediate conveying channel by adjusting the back-and-forth movement of the distributor driven by the adjustment mechanism. Therefore, the distribution ratio of circulating flue gas in the intermediate conveying channel and the outer annular conveying channel can be flexibly adjusted by adjusting the movement of the distributor driven by the adjustment mechanism, which can be flexibly adjusted according to actual needs. Attached Figure Description
[0025] Figure 1 This is a three-dimensional structural diagram of a natural gas burner that can reduce nitrogen oxides according to the present invention.
[0026] Figure 2 This is a front view of a natural gas burner that can reduce nitrogen oxides according to the present invention.
[0027] Figure 3 This is a cross-sectional view of a natural gas burner that can reduce nitrogen oxides according to the present invention.
[0028] Figure 4 This is a three-dimensional structural diagram of the distribution mechanism and the combustion head in this invention.
[0029] Figure 5 This is a partial cross-sectional view of the dispensing mechanism in this invention.
[0030] Figure 6 for Figure 5 A magnified view of a portion of point A in the middle.
[0031] Figure 7 This is a three-dimensional structural diagram of the distributor in this invention.
[0032] Figure 8 This is a three-dimensional structural diagram of the separator tube in this invention.
[0033] Figure 9 This is a three-dimensional structural diagram of a natural gas boiler according to the present invention.
[0034] Figure 10 This is a cross-sectional view of a natural gas boiler according to the present invention. Detailed Implementation
[0035] To enable those skilled in the art to fully understand the technical solutions of the present invention, the present invention will be further described below in conjunction with embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.
[0036] See Figures 1-5This embodiment discloses a natural gas burner that can reduce nitrogen oxides, including a pipe body 1, a fuel nozzle 2 for injecting natural gas, and a burner head 3 for injecting a mixed gas for combustion; the front end of the pipe body 1 is provided with an air inlet, the middle part of the pipe body 1 is provided with a circulating flue gas inlet 4, and the burner head 3 is located at the rear end of the pipe body 1; the fuel nozzle 2 is located at the front end of the pipe body 1 and inside the pipe body 1.
[0037] See Figures 1-8 The natural gas burner further includes a distribution mechanism for distributing circulating flue gas in different proportions; the distribution mechanism includes a distribution pipe 5 disposed inside the pipe body 1 and coaxially arranged with the pipe body 1, and an adjustment mechanism 6 connected to the distribution pipe 5; the distribution pipe 5 has an intermediate conveying channel 7 inside, the front end of the intermediate conveying channel 7 being connected to the pipe body 1; an outer annular conveying channel 8 is formed between the outer side wall of the distribution pipe 5 and the inner side wall of the pipe body 1; the front end of the outer annular conveying channel 8 is connected to the pipe body 1; the distribution pipe 5 includes a dividing pipe 5-1 and a distributor 5-2 slidably disposed at the front end of the dividing pipe 5-1; the rear end of the dividing pipe 5-1 is connected to the burner head 3; the adjustment mechanism 6 is used to drive the distributor 5-2 to move back and forth along the axis of the dividing pipe 5-1; the burner head 3 has a plurality of intermediate jet holes 3-1 in the middle area, the intermediate jet holes 3-1 being connected to the intermediate conveying channel 7; the burner head 3 has a plurality of peripheral jet holes 3-2 in the surrounding area, the peripheral jet holes 3-2 being connected to the peripheral annular conveying channel 8.
[0038] See Figures 1-8 The pipe body 1 includes an intake pipe 1-1, a venturi pipe 1-2, and an outlet pipe 1-3 connected sequentially from front to back. The fuel injector 2 is located inside the intake pipe 1-1, the circulating flue gas inlet 4 is located on the venturi pipe 1-2, and the burner head 3 is located at the end of the outlet pipe 1-3. The air inlet is located at the front end of the intake pipe 1-1. By setting the venturi pipe 1-2, the gas flow rate can be changed, thereby promoting the mixing of air, natural gas, and circulating flue gas.
[0039] See Figures 1-8The Venturi tube 1-2 includes a tapered section 1-21, a throat 1-22, and a diffusing section 1-23 connected sequentially from front to back. The inlet pipe 1-1 is connected to the tapered section 1-21, and the diffusing section 1-23 is connected to the outlet pipe 1-3. Multiple circulating flue gas inlets 4 are provided, evenly distributed along the circumference of the throat 1-22. In this structure, the multiple circulating flue gas inlets 4 increase the intake volume of circulating flue gas and make the mixing of air, natural gas, and circulating flue gas more uniform. When gas enters the tapered section 1-21 from the inlet pipe 1-1, the gas velocity increases, which in turn increases the gas velocity in the throat 1-22. The circulating flue gas also enters the throat 1-22 more rapidly, improving the self-circulation capability of the circulating flue gas.
[0040] See Figures 1-8 The adjusting mechanism 6 includes a gas supply device, a driving air chamber 6-1 disposed between the distributor 5-2 and the dividing pipe 5-1, and a driving spring 6-2 sleeved on the dividing pipe 5-1. The gas supply device is connected to the driving air chamber 6-1. One end of the driving spring 6-2 acts on the distributor 5-2, and the other end acts on the dividing pipe 5-1. In the above structure, when it is necessary to drive the distributor 5-2 to move, gas is supplied to the driving air chamber 6-1 through the gas supply device. Under the action of gas pressure, the distributor 5-2 is pushed to move, and the volume of the driving air chamber 6-1 will also increase accordingly. When the distributor 5-2 moves, it will compress the driving spring 6-2. When the gas supply device stops supplying gas, under the elastic force of the driving spring 6-2, the distributor 5-2 is driven to move in the opposite direction, and the volume of the driving air chamber 6-1 decreases. Through the coordinated adjustment of the gas supply device and the driving spring 6-2, the back-and-forth movement of the distributor 5-2 can be realized, thereby flexibly adjusting the distribution ratio of the circulating flue gas.
[0041] See Figures 1-8 The gas supply device can be an air compressor or other gas source. The front end of the separator pipe 5-1 is provided with a gas inlet and outlet 6-3, which is connected to the driving air chamber 6-1. The gas inlet and outlet 6-3 is connected to the gas supply device through a gas pipe 6-4.
[0042] See Figures 1-8The distributor 5-2 includes a horn tube 5-21 at the front end and a sliding tube 5-22 at the rear end. The inner wall of the sliding tube 5-22 has an inwardly protruding sliding ring 5-23. The outer wall of the front end of the separator 5-1 has a first annular protrusion 5-11 and a second annular protrusion 5-12 arranged sequentially backwards, with the second annular protrusion 5-12 located behind the first annular protrusion 5-11. The sliding ring 5-23 is located between the first annular protrusion 5-11 and the second annular protrusion 5-12 and is slidably connected to the outer wall of the separator 5-1. The first annular protrusion 5-11 and the second annular protrusion 5-12 are both slidably connected to the inner wall of the sliding tube 5-22; wherein, the space enclosed by the first annular protrusion 5-11, the outer wall of the partition tube 5-1, the sliding ring 5-23 and the inner wall of the sliding tube 5-22 constitutes the driving air chamber 6-1; the space enclosed by the sliding ring 5-23, the outer wall of the partition tube 5-1, the second annular protrusion 5-12 and the inner wall of the sliding tube 5-22 constitutes the spring mounting cavity 5-24, and the driving spring 6-2 is located in the spring mounting cavity 5-24. The above structure is very compact. The trumpet-shaped tube 5-21 can better guide the circulating flue gas delivered by the circulating flue gas inlet 4 into the trumpet tube 5-21, thereby entering the intermediate conveying channel 7. The sliding ring 5-23 is slidably connected to the outer wall of the separator tube 5-1. The first annular protrusion 5-11 and the second annular protrusion 5-12 are both slidably connected to the inner wall of the sliding tube 5-22, making the movement of the sliding tube 5-22 very stable and improving the stability of the adjustment. One end of the driving spring 6-2 acts on the sliding ring 5-23, and the other end acts on the second annular protrusion 5-12.
[0043] See Figures 1-8 The sliding tube 5-22 has a limiting ring 5-25 at its rear end. When the gas supply equipment is not working, the limiting ring 5-25 is pressed against the second annular protrusion 5-12 under the elastic force of the drive spring 6-2. By setting the limiting ring 5-25, a good limiting effect can be achieved. When the limiting ring 5-25 is pressed against the second annular protrusion 5-12, the horn tube 5-21 is in the position closest to the circulating flue gas inlet 4. The front end of the sliding tube 5-22 is also provided with a limiting ring 5-25, the purpose of which is also to play a limiting role and prevent the sliding tube 5-22 from moving too far backward.
[0044] See Figures 1-8 The sliding ring 5-23 is provided with a sealing groove 5-26, and a sealing ring 6-5 is provided in the sealing groove 5-26. The purpose is to improve the sealing performance between the sliding ring 5-23 and the outer wall of the partition tube 5-1.
[0045] See Figures 1-8The separator 5-1 includes a small separator at the front end, a gradually expanding separator in the middle, and a large separator at the rear end. The rear end of the large separator is fixed to the burner head 3. The distributor 5-2 is located at the front end of the small separator. The small separator is fixed to the pipe body 1 by a bracket 20. The separator 5-1 is configured as a small separator, a gradually expanding separator 5-1, and a large separator to accommodate changes in the pipe diameter of the pipe body 1, facilitating the transport of the mixed gas.
[0046] See Figures 1-8 The fuel nozzle 2 has a fuel delivery pipe 9 at its front end; the fuel nozzle 2 is connected to the fuel delivery pipe 9, and the fuel nozzle 2 has multiple fuel injection holes. The multiple fuel injection holes facilitate the injection of natural gas into the pipe body 1, ensuring thorough mixing of natural gas and air. Fuel injection holes are distributed on both the rear end face and the circumferential surface of the fuel nozzle 2, which is located in the middle of the pipe body 1.
[0047] See Figures 1-8 The axis of the circulating flue gas inlet 4 is inclined towards the direction close to the inlet pipe 1-1, that is, the angle between the flow direction of the mixed gas and the flow direction of the circulating flue gas at the circulating flue gas inlet 4 is an acute angle. The purpose is to make the outlet direction of the circulating flue gas inlet 4 closer to the flow direction of the mixed gas, thereby improving the conveying efficiency of the circulating flue gas.
[0048] See Figures 1-8 The number of circulating flue gas inlets 4 is two.
[0049] See Figures 1-8 The burner head 3 is hemispherical. The air inlet of the pipe body 1 is connected to the blower 19.
[0050] See Figures 1-2 The working principle of the above-mentioned natural gas burner that can reduce nitrogen oxides is as follows:
[0051] When the natural gas burner is burning, air enters the pipe body 1 through the air inlet, and natural gas is injected into the pipe body 1 through the fuel injection pipe 2. Part of the flue gas produced during combustion enters the pipe body 1 through the circulating flue gas inlet 4; this flue gas entering the pipe body 1 is called circulating flue gas. Air, natural gas, and circulating flue gas mix within the pipe body 1 to form a mixed gas. Part of this mixed gas enters the intermediate conveying channel 7, is conveyed through it, and then exits from the intermediate jet hole 3-1. Another part of the mixed gas enters the outer annular conveying channel 8, is conveyed through it, and then exits from the outer jet hole 3-2. The mixed gas exiting from the intermediate jet hole 3-1 and the outer jet hole 3-2 burns outside the burner head 3, and part of the flue gas produced (circulating flue gas) enters the pipe body 1 through the circulating flue gas inlet 4. By mixing the circulating flue gas with air and natural gas, the proportion of oxygen in the air can be reduced, thereby lowering the combustion efficiency. Because the flame zone has the highest temperature in the middle and lower temperatures around it, nitrogen oxides are easily generated in the middle. The distributor 5-2 is moved by the adjusting mechanism 6. When the distributor 5-2 is closer to the circulating flue gas inlet 4, more circulating flue gas is guided into the intermediate conveying channel 7, and less circulating flue gas enters the outer annular conveying channel 8. Therefore, the mixed gas in the intermediate conveying channel 7 has a higher proportion of circulating flue gas and a lower proportion of oxygen, resulting in lower combustion efficiency of the mixed gas ejected from the intermediate jet hole 3-1, reducing the combustion efficiency in the middle zone, and further reducing nitrogen oxide generation. Conversely, when the adjusting mechanism 6 moves the distributor 5-2 away from the circulating flue gas inlet 4, the amount of circulating flue gas entering the intermediate conveying channel 7 can be changed, resulting in less circulating flue gas entering the intermediate conveying channel 7 and more circulating flue gas entering the outer annular conveying channel 8. Therefore, by adjusting the mechanism 6 to drive the distributor 5-2, the distribution ratio of circulating flue gas in the intermediate conveying channel 7 and the outer annular conveying channel 8 can be flexibly adjusted according to actual needs.
[0052] See Figures 9-10 and Figures 1-2This embodiment also discloses a natural gas boiler, including a boiler drum 10, a furnace shell 11, a combustion chamber 12, a front smoke box 13, a rear smoke box 14, and a natural gas burner as described in the embodiment; the furnace shell 11 and the combustion chamber 12 are disposed within the boiler drum 10, the front smoke box 13 is disposed at the front end of the boiler drum 10, and the rear smoke box 14 is disposed at the rear end of the boiler drum 10; the combustion chamber 12 is disposed at the rear end of the furnace shell 11 and communicates with the furnace shell 11, the front smoke box 13 and the combustion chamber 12 are connected by a first return smoke pipe 15, the front smoke box 13 and the rear smoke box 14 are connected by a second return smoke pipe 16, and the burner head 3 of the natural gas burner is disposed at the front end of the furnace shell 11; the rear smoke box 14 is connected to the circulating flue gas inlet 4 by a circulating flue gas pipe 17. After exiting the rear smoke box 14, the circulating flue gas pipe 17 splits into two paths, each connected to one of the two circulating flue gas inlets 4.
[0053] See Figures 9-10 and Figures 1-2 The mixed gas ejected from the burner head 3 will burn inside the furnace chamber 11. The furnace chamber 11 will heat the water inside the boiler drum 10, thereby generating steam. The high-temperature flue gas generated by the furnace chamber 11 will pass sequentially through the combustion chamber 12, the first return flue pipe 15, the front smoke box 13, the second return flue pipe 16, and the rear smoke box 14. The first return flue pipe 15 and the second return flue pipe 16 can further heat the water inside the boiler drum 10. The flue gas temperature will decrease when it enters the rear smoke box 14. Part of the flue gas will be discharged from the flue gas outlet 18 of the rear smoke box 14, and part of the flue gas (circulating flue gas) will enter the circulating flue gas inlet 4 through the circulating flue gas pipe 17, and then enter the tube body 1 of the natural gas burner from the circulating flue gas inlet 4, thereby reducing the emission of nitrogen oxides.
[0054] See Figures 9-10 and The upper end of the rear smoke box 14 is provided with a smoke outlet 18, and a fan is provided at the smoke outlet 18. By setting the fan, the exhaust volume of the smoke outlet 18 can be controlled.
[0055] The above are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above content. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.
Claims
1. A natural gas burner capable of reducing nitrogen oxides, characterized in that, The system includes a pipe body, a fuel nozzle for injecting natural gas, and a burner head for injecting a gas mixture for combustion. The pipe body has an air inlet at its front end and a circulating flue gas inlet in its middle section. The burner head is located at the rear end of the pipe body. The fuel nozzle is located at the front end of the pipe body and inside the pipe body. It also includes a distribution mechanism for distributing circulating flue gas in different proportions; the distribution mechanism includes a distribution pipe disposed inside the pipe body and coaxially arranged with the pipe body, and an adjustment mechanism connected to the distribution pipe; the distribution pipe has an intermediate conveying channel inside, and an outer annular conveying channel is formed between the outer side wall of the distribution pipe and the inner side wall of the pipe body; the distribution pipe includes a separator and a distributor slidably disposed at the front end of the separator; the rear end of the separator is connected to the burner head; the adjustment mechanism is used to drive the distributor to move back and forth along the axis of the separator; the middle area of the burner head has multiple intermediate jet holes, which are connected to the intermediate conveying channel; the surrounding area of the burner head has multiple peripheral jet holes, which are connected to the peripheral annular conveying channel.
2. The natural gas burner according to claim 1, characterized in that, The pipe body includes an intake pipe, a venturi pipe, and an outlet pipe connected in sequence; the fuel injector is located inside the intake pipe, the circulating flue gas inlet is located on the venturi pipe, and the burner head is located at the end of the outlet pipe.
3. The natural gas burner according to claim 2, characterized in that, The venturi tube includes a converging section, a throat, and a diverging section connected in sequence. The inlet pipe is connected to the converging section, and the diverging section is connected to the outlet pipe. Multiple circulating flue gas inlets are provided, and the multiple circulating flue gas inlets are distributed along the circumferential direction in the throat.
4. The natural gas burner according to claim 1, characterized in that, The regulating mechanism includes an air supply device, a driving air chamber disposed between the distributor and the dividing pipe, and a driving spring sleeved on the dividing pipe; the air supply device is connected to the driving air chamber; one end of the driving spring acts on the distributor, and the other end acts on the dividing pipe.
5. The natural gas burner according to claim 4, characterized in that, The distributor includes a horn tube at the front end and a sliding tube at the rear end; the inner wall of the sliding tube is provided with an inwardly protruding sliding ring, and the outer wall of the front end of the separator tube is provided with a first annular protrusion and a second annular protrusion in sequence, with the second annular protrusion located behind the first annular protrusion; the sliding ring is located between the first annular protrusion and the second annular protrusion and is slidably connected to the outer wall of the separator tube, and both the first annular protrusion and the second annular protrusion are slidably connected to the inner wall of the sliding tube; wherein, the space enclosed by the first annular protrusion, the outer wall of the separator tube, the sliding ring, and the inner wall of the sliding tube constitutes the driving air chamber; the space enclosed by the sliding ring, the outer wall of the separator tube, the second annular protrusion, and the inner wall of the sliding tube constitutes the spring mounting cavity, and the driving spring is located in the spring mounting cavity.
6. The natural gas burner according to claim 5, characterized in that, The sliding tube is provided with a limiting ring at its rear end. When the gas supply equipment is not working, the limiting ring is pressed against the second annular protrusion under the elastic force of the drive spring.
7. The natural gas burner according to claim 5, characterized in that, The sliding ring is provided with a sealing groove, and a sealing ring is provided in the sealing groove.
8. The natural gas burner according to claim 1, characterized in that, The fuel injector is connected to the fuel delivery pipe, and the fuel injector is provided with multiple fuel injection holes.
9. The natural gas burner according to claim 2, characterized in that, The axis of the circulating flue gas inlet is inclined toward the direction of the inlet pipe.
10. A natural gas boiler, characterized in that, The system includes a boiler drum, a furnace shell, a combustion chamber, a front smoke box, a rear smoke box, and a natural gas burner as described in any one of claims 1-9; the furnace shell and the combustion chamber are disposed within the boiler drum, the front smoke box is disposed at the front end of the boiler drum, and the rear smoke box is disposed at the rear end of the boiler drum; the combustion chamber is disposed at the rear end of the furnace shell and communicates with the furnace shell, the front smoke box and the combustion chamber are connected by a first return smoke pipe, the front smoke box and the rear smoke box are connected by a second return smoke pipe, and the burner head of the natural gas burner is disposed at the front end of the furnace shell; the rear smoke box is connected to the circulating flue gas inlet by a circulating flue gas pipe.