Gas burner
Through the gas burner designed with dual air ducts, the problem of flameless burner needs to be preheated and has weak adaptability for working conditions is solved, and stable low NOx combustion in multiple operating conditions is achieved, which improves the flexibility and adaptability of the burner.
Patent Information
- Application Number
- CN202421829188.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-07-31
- Publication Date
- 2025-08-01
- Estimated Expiration
- 2034-07-31
AI Technical Summary
Existing flameless burners need to be equipped with special preheating burners, and are weak in adaptability to operating conditions, and cannot achieve flameless combustion in the furnace preheating stage, and can easily turn into unstable flameless combustion under low-power conditions.
The dual air duct design adopts a flameless combustion without additional preheating burners by adjusting the air flow in the first and second air ducts, and is flexible in different operating conditions, including ignition, preheating and low power and high power operating conditions.
It realizes stable low NOx clean combustion under various operating conditions, enhances the regulation ratio and operating conditions of the burner, reduces NOx emissions, and simplifies structural and maintenance costs.
Smart Images
Figure CN223178829U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to a combustion device, in particular to a gas burner, belonging to the technical field of combustion devices. Background Technique
[0002] Gas fuels represented by natural gas, coke oven gas, etc. are important industrial energy sources. While these gas fuels are burning for heating, they will also generate a large amount of polluting gases such as NO x etc., thus causing serious environmental pollution. Therefore, how to reduce the generation amount of pollutants such as NO x etc. during the combustion process and achieve clean combustion has become an important problem that people in this field urgently want to solve.
[0003] Existing research shows that the NO generated by the combustion of gas fuels x is mainly thermal NO x , accounting for more than 90%. Thermal NO x is formed by the combination of nitrogen atoms in the system with oxygen atoms under the action of high temperature and is rapidly oxidized to generate NO, NO2, etc. Thermal NO x is very sensitive to temperature. As the temperature rises, thermal NO x increases exponentially. The typical temperature threshold of thermal NO x is 1500°C. When the temperature is less than 1500°C, the generation amount of NO x is very small. When the temperature is greater than 1500°C, the generation amount of NO x increases rapidly. Therefore, reducing the peak temperature of the combustion system is the key to controlling the NO x emission during the combustion process.
[0004] MILD combustion (Moderate and Lean Oxygen Combustion), also known as flameless combustion, is an advanced low-NO x combustion technology. It injects fuel and oxidant into the furnace space at an extremely high flow rate (exceeding 100 m / s), uses the large momentum of the reactants to "blow out" the local flame, and makes the combustion reaction proceed in a mild low-oxygen concentration manner throughout the furnace space, thereby greatly reducing the peak flame temperature and achieving low-NO x combustion. Because the reaction takes place throughout the furnace space and the traditional flame shape cannot be seen intuitively, it is also called flameless combustion.
[0005] Existing flameless burners mainly adopt a straight injection pipe design, combined with a large injection flow rate and a suitable fuel-oxidant gap to achieve flameless combustion. Although this design can obtain a relatively low NO xEmission concentration, but it is necessary to raise the overall furnace temperature to the fuel auto-ignition temperature (generally above 700 °C). Therefore, flameless combustion cannot be achieved during the ignition stage and the furnace preheating stage. Therefore, current flameless burners are generally equipped with special preheating burners. During the preheating stage, the overall furnace is heated above the fuel auto-ignition point using a conventional preheating burner, and then the flameless combustion burner is switched. In addition, due to strict requirements for the injection speed of the reactants (usually combustion-supporting air), when the combustion power is less than the designed power, it is very easy for the injection speed to be too low, and the combustion changes from flameless to unstable flame combustion. Therefore, the low NO x flameless burner has a very small turndown ratio and weak adaptability to changes in operating conditions. Summary of the Invention
[0006] In view of the problems of existing flameless burners that require special preheating burners and weak adaptability to changes in operating conditions, the present invention provides a gas burner. This gas burner adopts a design with a double air pipeline, enabling flameless combustion without the need for additional preheating burners; and by adjusting the air intake through the double air pipeline, it can achieve the adjustment and conversion of various operating conditions (such as electric ignition conditions, preheating and low-power conditions, and high-power conditions), with a large turndown ratio and strong adaptability to changes in operating conditions.
[0007] To achieve the above technical objectives, the technical solutions adopted by the present invention are described as follows:
[0008] A gas burner, which includes a gas pipeline, a first air pipeline, a second air pipeline, a burner brick, and a flue. The intake end of the gas pipeline is provided with a gas inlet, and its outlet end is connected to the flue arranged inside the burner brick. The first air pipeline is sleeved outside the gas pipeline, the second air pipeline is sleeved outside the first air pipeline, and the outlet ends of the first air pipeline and the second air pipeline are both connected to the flue.
[0009] Preferably, the gas burner further includes a tube core and a bluff body. One end of the tube core extends into the gas pipeline and extends along the central axis of the gas pipeline to the outlet of the gas pipeline and is connected to the bluff body arranged inside the flue. By axially moving the tube core in the gas pipeline, the axial distance between the bluff body and the outlet of the gas pipeline can be adjusted.
[0010] Preferably, the tube core is a circular rod-shaped structure, and its diameter does not exceed one-half of the inner diameter of the gas pipeline, preferably does not exceed one-third of the inner diameter of the gas pipeline, and more preferably does not exceed one-fourth of the inner diameter of the gas pipeline.
[0011] Preferably, the bluff body is a conical structure, with its narrow end connected to the core tube, and the diameter of its wide end being not less than the diameter of the gas pipeline outlet. The axial depth of the narrow end of the bluff body extending into the gas pipeline outlet end is controlled by the core tube, thereby adjusting the opening degree of the gas pipeline outlet.
[0012] Preferably, the flue is a divergent structure with a gradually increasing diameter along the gas flow direction. The diameter of the narrow end of the flue is not lower than the diameter of the outlet end of the second air pipeline. Preferably, the diameter of the wide end of the flue is 1.1 to 2 times the diameter of its narrow end.
[0013] Preferably, a first annular air passage is formed between the inner wall of the first air pipeline and the outer wall of the gas pipeline, and swirl vanes are provided inside the outlet end of the first annular air passage. Preferably, the diameter of the first air pipeline is 1.2 to 5 times the diameter of the gas pipeline, preferably 1.5 to 3 times.
[0014] Preferably, a second annular air passage is formed between the inner wall of the second air pipeline and the outer wall of the first air pipeline, and an annular baffle is provided at the outlet of the second annular air passage. A plurality of air injection holes communicating with the second annular air passage are opened on the annular baffle. Preferably, the diameter of the second air pipeline is 1.1 to 4 times the diameter of the first air pipeline, preferably 1.5 to 2 times.
[0015] Preferably, the air injection hole is a convergent hole passage with a gradually decreasing diameter along the gas flow direction.
[0016] Preferably, the outlet sections of the first air pipeline and the second air pipeline are both designed with a reduced diameter along the gas flow direction. Preferably, the reduced diameter amplitudes of the outlet sections of the first air pipeline and the second air pipeline are the same or different.
[0017] Preferably, the gas burner further includes a total air inlet pipeline. The outlet of the total air inlet pipeline is simultaneously connected to the inlets of the first air pipeline and the second air pipeline. Preferably, an air regulating movable valve plate is provided at the outlet of the total air inlet pipeline, and the connecting area size between the outlet of the total air inlet pipeline and the inlets of the first air pipeline and the second air pipeline is adjusted through the air regulating movable valve plate.
[0018] In the prior art, the existing flameless burner structure (Adelaide burner, such as Figure 1As shown in the figure, although a flameless combustion with low NOx emissions can be achieved with a relatively simple structure and process under the existing structure, there are at least the following two obvious defects, which prevent it from being widely promoted and applied on a large scale. First, flameless combustion cannot be achieved during the furnace preheating stage, and a dedicated preheating burner needs to be equipped: Since there is no flame structure in flameless combustion like traditional flaming combustion, the fuel and oxidant mixture entering the furnace needs to be ignited by the local temperature. Therefore, the temperature at each part of the furnace must be above the fuel auto-ignition point. However, during the preheating stage, the temperature at each part of the furnace is below the auto-ignition point, so flameless combustion cannot be achieved. Therefore, at present, general flameless burners are usually equipped with dedicated preheating burners. During the preheating stage, the conventional preheating burner is used to heat the entire furnace above the fuel auto-ignition point, and then the flameless combustion burner is switched. Second, the adjustment ratio for the stable combustion of the burner is small, and its adaptability to operating condition fluctuations is poor: Since flameless combustion requires a relatively large injection speed to entrain a sufficient amount of furnace flue gas to achieve the effects of diluting reactants and enhancing heat transfer, so as to realize the transformation of combustion from flaming to flameless mode. When the actual power of the burner is less than the designed power, the flow rate and injection speed of the fuel and oxidant decrease. When it is lower than the lower limit of the flameless combustion speed, the furnace will change from flameless combustion to an unstable flaming combustion state. The utility model realizes flameless combustion without additionally installing a preheating burner by successively sleeving two air pipes outside the gas pipe, and by adjusting the changes in the air flow in the two air pipes; in addition, it also has a large adjustment ratio, and can meet the adjustment and conversion of various operating conditions such as electric ignition operating conditions, preheating and low-power operating conditions, and high-power operating conditions, with strong practicability.
[0019] In the utility model, the gas pipe, the first air pipe, and the second air pipe are concentrically arranged in the order from the inside to the outside, and the diameters of the gas pipe, the first air pipe, and the second air pipe increase in sequence; the air outlets of the gas pipe, the first air pipe, and the second air pipe are flush and are all connected to the flue. That is to say, when the air flow ejected from the first air pipe enters the flue, it is close to the outer periphery of the gas flow, and when the air flow ejected from the second air pipe enters the flue, it is slightly away from the outer periphery of the gas flow. Then, by adjusting the changes in the air flow rate and flow velocity and other states of the first air pipe and the second air pipe, the flameless combustion under different operating condition requirements can be realized. In a preferred embodiment, the air flow ejected from the first air pipe is a rotating air flow (realized by setting swirl vanes), and the air flow ejected from the second air pipe is a high-speed straight jet flow (realized by setting variable-diameter spray holes).
[0020] In the present utility model, the air inlets of the first air duct and the second air duct are both connected to the same main air inlet duct, and an air regulating movable valve plate is arranged at the air outlet of the main air inlet duct to adjust the size of the communication area between the air outlet of the main air inlet duct and the air inlets of the first air duct and the second air duct respectively. That is to say, when the total air volume is constant, the air volume entering the first air duct and the second air duct can be adjusted through the air regulating movable valve plate, and thus the rapid switching of flameless combustion under various working conditions can be realized.
[0021] In the present utility model, when the system is in the ignition working condition (as Figure 4 shown): the air regulating movable valve plate closes the air inlet of the second air duct, so that all the air enters the first air duct. That is, the gas and the air enter the flue from the gas duct and the first annular air passage respectively. The gas flows through the bluff body and a recirculation is formed behind the bluff body. At the same time, after the air passes through the swirl vanes in the first annular air passage, it obtains a rotating forward speed. The swirling air and the fuel are fully mixed in the flue and then burn. At this time, the combustion is still in the ignition process, the surrounding environment temperature is very low, and most of the heat generated by the combustion is transferred to the surrounding environment (flue, furnace, etc.), so the flame temperature is relatively low, and the temperature of the core area is generally only 800 - 1000 °C. However, due to the dual effects of the bluff body flow disturbance and the air swirl, stable recirculation zones will be formed at the edge and the center of the flue. In the recirculation zones, the fuel, the air and the high-temperature flue gas are violently mixed, and a stable combustion flame is formed in the flue, and the flame root closely adheres to the end of the burner. These characteristics make the flame stability of the ignition process of the burner of this patent very strong.
[0022] In the present utility model, when the system is in the preheating and low-power working conditions (as Figure 5As shown in the figure: The air-conditioning movable valve plate is located between the first air duct inlet and the second air duct inlet, and air will enter the first air duct and the second air duct simultaneously. That is, part of the air enters the flue through the second annular air channel, and part of the air enters the flue through the first annular air channel. The strong swirling air ejected from the first annular air channel entrains a large amount of high-temperature flue gas. On the one hand, it preheats the unreacted low-temperature gas and air, and on the other hand, it dilutes the high-temperature reaction gas, making the flame temperature lower than the conventional combustion temperature. By controlling the swirling intensity, the peak temperature of the flame in the combustion zone can be controlled within 1300 °C, thereby significantly reducing the generation of NOx during the combustion process. At the same time, since part of the combustion-supporting air is ejected from the periphery of the swirling air at a certain speed (ejected from the second annular air channel) to form peripheral direct-injection air, a forward flow field is generated at the edge of the flue, lifting the swirling flame downstream to form a lifted flame at a certain distance from the end of the gas channel, so that the high-temperature flame is far from the burner, improving the working environment of the burner. At the same time, the peripheral direct-injection air can elongate the swirling flame, making the temperature distribution in the combustion area more uniform, further reducing the peak flame temperature and reducing the generation of NOx during the combustion process.
[0023] In the present utility model, when the system is in a high-power working condition (such as Figure 6 As shown in the figure: The air-conditioning movable valve plate closes the air inlet of the first air duct, so that all the air enters the second air duct. That is, all the air forms a direct-injection air channel through the second annular air channel and enters the flue. The speed of the air ejected from the end annular baffle is as high as 80-120 m / s (acceleration injection holes are provided on the annular baffle. The acceleration injection holes are set such that the holes at the incoming flow end are larger than the holes at the outlet end, so that the flow rate of the air is secondarily accelerated after passing through the end annular baffle), and strong flue gas entrainment is formed around the jet, thereby forming uniform flameless combustion in the entire furnace. Since the combustion occurs throughout the furnace and there is no obvious visible flame shape to the naked eye, the furnace temperature is very uniform. The peak temperature of the furnace is very low, generally not exceeding 1350 °C. Therefore, the NOx emission is very small.
[0024] Compared with the prior art, the beneficial technical effects of the present utility model are as follows:
[0025] 1: Through the design of the double air ducts sleeved in sequence, the gas burner of the present utility model can flexibly adjust various working conditions such as ignition, preheating, low power, and high power, meet different combustion requirements, and achieve stable and low-NOx clean combustion under all working conditions. The burner has a large adjustment ratio and strong working condition adaptability.
[0026] 2: The gas burner of the present utility model also has the characteristics of simple structure, low manufacturing and maintenance costs, stable working conditions, convenient flexible adjustment, strong applicability and practicability, and is convenient for popularization and practical application. Description of the Drawings
[0027] Figure 1 is a burner of the prior art.
[0028] Figure 2 is a schematic structural view of the burner of the present utility model.
[0029] Figure 3 is a schematic structural view of the annular baffle of the present utility model.
[0030] Figure 4 is a schematic view of the air flow regulation under the ignition condition of the present utility model.
[0031] Figure 5 is a schematic view of the air flow regulation under the preheating and low-power conditions of the present utility model.
[0032] Figure 6 is a schematic view of the air flow regulation under the high-power condition of the present utility model.
[0033] Reference numerals: 1: gas pipeline; 2: first air pipeline; 3: second air pipeline; 4: burner brick; 5: flue; 6: tube core; 7: bluff body; 8: swirl vane; 9: annular baffle; 901: air injection hole; 10: total air intake pipeline; 11: air regulation movable valve plate. Detailed implementation manners
[0034] The technical solutions of the present utility model will be illustrated by way of example below. The scope of protection claimed by the present utility model includes but is not limited to the following embodiments.
[0035] A gas burner, which includes a gas pipeline 1, a first air pipeline 2, a second air pipeline 3, a burner brick 4 and a flue 5. The intake end of the gas pipeline 1 is provided with a gas inlet, and its outlet end is communicated with the flue 5 arranged in the burner brick 4. The first air pipeline 2 is sleeved outside the gas pipeline 1, the second air pipeline 3 is sleeved outside the first air pipeline 2, and the outlet ends of the first air pipeline 2 and the second air pipeline 3 are both communicated with the flue 5.
[0036] Preferably, the gas burner further includes a tube core 6 and a bluff body 7. One end of the tube core 6 extends into the gas pipeline 1 and extends along the central axis of the gas pipeline 1 to the outlet of the gas pipeline 1 and is connected to the bluff body 7 arranged in the flue 5. By axially moving the tube core 6 in the gas pipeline 1, the axial distance between the bluff body 7 and the outlet of the gas pipeline 1 is adjusted.
[0037] Preferably, the tube core 6 is a circular rod-shaped structure, and its diameter does not exceed one-half of the inner diameter of the gas pipeline 1, preferably does not exceed one-third of the inner diameter of the gas pipeline 1, and more preferably does not exceed one-fourth of the inner diameter of the gas pipeline 1.
[0038] Preferably, the bluff body 7 is a conical structure, with its narrow end connected to the core 6, and the diameter of its wide end being not less than the diameter of the air outlet of the gas pipeline 1. The axial depth of the narrow end of the bluff body 7 extending into the air outlet end of the gas pipeline 1 is controlled by the core 6, thereby adjusting the opening degree of the air outlet of the gas pipeline 1.
[0039] Preferably, the flue 5 is a divergent structure with a gradually increasing diameter along the gas flow direction. The diameter of the narrow end of the flue 5 is not less than the diameter of the air outlet end of the second air pipeline 3. Preferably, the diameter of the wide end of the flue 5 is 1.1 - 2 times the diameter of its narrow end.
[0040] Preferably, a first annular air passage is formed between the inner wall of the first air pipeline 2 and the outer wall of the gas pipeline 1, and a swirl vane 8 is arranged inside the air outlet end of the first annular air passage. Preferably, the diameter of the first air pipeline 2 is 1.2 - 5 times the diameter of the gas pipeline 1, preferably 1.5 - 3 times.
[0041] Preferably, a second annular air passage is formed between the inner wall of the second air pipeline 3 and the outer wall of the first air pipeline 2, and an annular baffle 9 is arranged at the outlet of the second annular air passage. A plurality of air injection holes 901 communicating with the second annular air passage are formed on the annular baffle 9. Preferably, the diameter of the second air pipeline 3 is 1.1 - 4 times the diameter of the first air pipeline 2, preferably 1.5 - 2 times.
[0042] Preferably, the air injection hole 901 is a convergent hole passage with a gradually decreasing diameter along the gas flow direction.
[0043] Preferably, the air outlet sections of the first air pipeline 2 and the second air pipeline 3 are both designed with a reduced diameter along the gas flow direction. Preferably, the reduced diameter amplitudes of the air outlet sections of the first air pipeline 2 and the second air pipeline 3 are the same or different.
[0044] Preferably, the gas burner further includes a total air inlet pipeline 10. The air outlet of the total air inlet pipeline 10 is simultaneously communicated with the air inlets of the first air pipeline 2 and the second air pipeline 3. Preferably, an air regulating movable valve plate 11 is arranged at the air outlet of the total air inlet pipeline 10, and the communication area between the air outlet of the total air inlet pipeline 10 and the air inlets of the first air pipeline 2 and the second air pipeline 3 is adjusted through the air regulating movable valve plate 11. Example 1
[0045] As Figure 2-6As shown, a gas burner includes a gas pipeline 1, a first air pipeline 2, a second air pipeline 3, a burner block 4, and a flue 5. The intake end of the gas pipeline 1 is provided with a gas inlet, and its outlet end is connected to the flue 5 arranged inside the burner block 4. The first air pipeline 2 is sleeved outside the gas pipeline 1, and the second air pipeline 3 is sleeved outside the first air pipeline 2. The outlet ends of both the first air pipeline 2 and the second air pipeline 3 are connected to the flue 5. Example 2
[0046] Repeat Example 1, except that the gas burner further includes a tube core 6 and a bluff body 7. One end of the tube core 6 extends into the gas pipeline 1 and extends along the central axis of the gas pipeline 1 to the outlet of the gas pipeline 1 and is connected to the bluff body 7 arranged in the flue 5. By axially moving the tube core 6 in the gas pipeline 1, the axial distance between the bluff body 7 and the outlet of the gas pipeline 1 is adjusted. Example 3
[0047] Repeat Example 2, except that the tube core 6 is a circular rod-shaped structure, and its diameter does not exceed one-half of the inner diameter of the gas pipeline 1. Example 4
[0048] Repeat Example 3, except that the diameter of the tube core does not exceed one-fourth of the inner diameter of the gas pipeline 1. Example 5
[0049] Repeat Example 4, except that the bluff body 7 is a conical structure, its narrow end is connected to the tube core 6, and the diameter of its wide end is not less than the diameter of the outlet of the gas pipeline 1. By controlling the axial depth of the narrow end of the bluff body 7 extending into the outlet end of the gas pipeline 1 through the tube core 6, the opening degree of the outlet of the gas pipeline 1 is adjusted. Example 6
[0050] Repeat Example 5, except that the flue 5 is a gradually expanding structure with a gradually increasing diameter along the gas flow direction. The diameter of the narrow end of the flue 5 is not lower than the diameter of the outlet end of the second air pipeline 3. Example 7
[0051] Repeat Example 6, except that the diameter of the wide end of the flue 5 is 1.4 times the diameter of its narrow end. Example 8
[0052] Repeat Example 7, except that a first annular air channel is formed between the inner wall of the first air pipeline 2 and the outer wall of the gas pipeline 1, and a swirl vane 8 is arranged inside the outlet end of the first annular air channel. Example 9
[0053] Repeat Example 8, except that the diameter of the first air pipeline 2 is 1.3 times the diameter of the gas pipeline 1. Example 10
[0054] Repeat Example 9, except that the diameter of the first air duct 2 is 2.2 times the diameter of the gas duct 1. Example 11
[0055] Repeat Example 10, except that a second annular air passage is formed between the inner wall of the second air duct 3 and the outer wall of the first air duct 2. An annular baffle 9 is provided at the outlet of the second annular air passage, and a plurality of air jet holes 901 communicating with the second annular air passage are formed on the annular baffle 9. Example 12
[0056] Repeat Example 11, except that the diameter of the second air duct 3 is 2 times the diameter of the first air duct 2. Example 13
[0057] Repeat Example 12, except that the diameter of the second air duct 3 is 2.5 times the diameter of the first air duct 2. Example 14
[0058] Repeat Example 13, except that the air jet hole 901 is a tapered hole with a gradually decreasing aperture along the air flow direction. Example 15
[0059] Repeat Example 14, except that the outlet sections of both the first air duct 2 and the second air duct 3 are designed with constrictions along the air flow direction. Example 16
[0060] Repeat Example 15, except that the constriction amplitudes of the outlet sections of the first air duct 2 and the second air duct 3 are the same. Example 17
[0061] Repeat Example 16, except that the gas burner further includes a main air inlet duct 10. The outlet of the main air inlet duct 10 is simultaneously connected to the inlets of the first air duct 2 and the second air duct 3. Example 18
[0062] Repeat Example 17, except that an air regulating movable valve plate 11 is provided at the outlet of the main air inlet duct 10 to adjust the size of the communication area between the outlet of the main air inlet duct 10 and the inlets of the first air duct 2 and the second air duct 3 respectively.
Claims
1. A gas burner, characterized in that: The gas burner includes a gas pipeline (1), a first air pipeline (2), a second air pipeline (3), a burner block (4), and a flue (5); a gas inlet is provided at the inlet end of the gas pipeline (1), and its outlet end is communicated with the flue (5) arranged in the burner block (4); the first air pipeline (2) is sleeved outside the gas pipeline (1), the second air pipeline (3) is sleeved outside the first air pipeline (2), and the outlet ends of the first air pipeline (2) and the second air pipeline (3) are both communicated with the flue (5).
2. The gas burner according to claim 1, characterized in that: The gas burner further includes a core (6) and a bluff body (7); one end of the core (6) extends into the gas pipeline (1) and extends along the central axis of the gas pipeline (1) to the outlet of the gas pipeline (1) and is connected to the bluff body (7) arranged in the flue (5); by axially moving the core (6) in the gas pipeline (1), the axial distance between the bluff body (7) and the outlet of the gas pipeline (1) is adjusted.
3. The gas burner according to claim 2, characterized in that: The core (6) is a circular rod-like structure, and its diameter does not exceed one-half of the inner diameter of the gas pipeline (1).
4. The gas burner according to claim 3, characterized in that: The diameter of the core (6) does not exceed one-third of the inner diameter of the gas pipeline (1).
5. The gas burner according to claim 4, wherein: The diameter of the core (6) does not exceed one-fourth of the inner diameter of the gas pipeline (1).
6. The gas burner according to claim 2, characterized in that: The bluff body (7) is a conical structure, its narrow end is connected to the core (6), and the diameter of its wide end is not less than the diameter of the outlet of the gas pipeline (1); by controlling the axial depth of the narrow end of the bluff body (7) extending into the outlet end of the gas pipeline (1) through the core (6), the opening degree of the outlet of the gas pipeline (1) is adjusted.
7. The gas burner according to any one of claims 1-6, characterized in that: The flue (5) is a gradually expanding structure with a gradually increasing diameter along the gas flow direction; the diameter of the narrow end of the flue (5) is not lower than the diameter of the outlet end of the second air pipeline (3).
8. The gas burner according to claim 7, characterized in that: The diameter of the wide end of the flue (5) is 1.1 to 2 times the diameter of its narrow end.
9. The gas burner according to any one of claims 1-6 and 8, characterized in that: A first annular air passage is formed between the inner wall of the first air pipeline (2) and the outer wall of the gas pipeline (1), and a swirl vane (8) is arranged inside the outlet end of the first annular air passage.
10. The gas burner according to claim 7, characterized in that: A first annular air passage is formed between the inner wall of the first air pipeline (2) and the outer wall of the gas pipeline (1), and a swirl vane (8) is arranged inside the outlet end of the first annular air passage.
11. The gas burner according to claim 9, characterized in that: The diameter of the first air pipeline (2) is 1.2 to 5 times the diameter of the gas pipeline (1).
12. The gas burner according to claim 10, characterized in that: The diameter of the first air pipeline (2) is 1.2 to 5 times the diameter of the gas pipeline (1).
13. The gas burner according to claim 11 or 12, characterized in that: The diameter of the first air pipeline (2) is 1.5 to 3 times the diameter of the gas pipeline (1).
14. The gas burner according to any one of claims 1-6, 8, 10-12, characterized in that: A second annular air passage is formed between the inner wall of the second air pipeline (3) and the outer wall of the first air pipeline (2), an annular baffle (9) is arranged at the outlet of the second annular air passage, and a plurality of air injection holes (901) communicated with the second annular air passage are opened on the annular baffle (9).
15. The gas burner according to claim 7, characterized in that: A second annular air passage is formed between the inner wall of the second air pipeline (3) and the outer wall of the first air pipeline (2), an annular baffle (9) is arranged at the outlet of the second annular air passage, and a plurality of air injection holes (901) communicated with the second annular air passage are opened on the annular baffle (9).
16. The gas burner according to claim 9, characterized in that: A second annular air passage is formed between the inner wall of the second air duct (3) and the outer wall of the first air duct (2). An annular baffle (9) is provided at the outlet of the second annular air passage, and a plurality of air injection holes (901) communicating with the second annular air passage are formed in the annular baffle (9).
17. The gas burner according to claim 14, characterized in that: The diameter of the second air duct (3) is 1.1 to 4 times that of the first air duct (2).
18. The gas burner according to claim 15, characterized in that: The diameter of the second air duct (3) is 1.1 to 4 times that of the first air duct (2).
19. The gas burner according to claim 16, characterized in that: The diameter of the second air duct (3) is 1.1 to 4 times that of the first air duct (2).
20. The gas burner according to any one of claims 17 to 19, characterized in that: The diameter of the second air duct (3) is 1.5 to 2 times that of the first air duct (2).
21. The gas burner according to claim 14, characterized in that: The air injection hole (901) is a tapered hole with a gradually decreasing aperture along the air flow direction.
22. The gas burner according to claim 15 or 16, characterized in that: The air injection hole (901) is a tapered hole with a gradually decreasing aperture along the air flow direction.
23. The gas burner according to any one of claims 1-6, 8, 10-12, 15-19, 21, characterized in that: The outlet sections of the first air duct (2) and the second air duct (3) are both designed with a reduced cross-section along the air flow direction.
24. The gas burner according to claim 23, wherein: The reduction amplitudes of the outlet sections of the first air duct (2) and the second air duct (3) are the same or different.
25. The gas burner according to any one of claims 1-6, 8, 10-12, 15-19, 21, 24, characterized in that: The gas burner further includes a total air intake duct (10); the outlet of the total air intake duct (10) is simultaneously communicated with the inlets of the first air duct (2) and the second air duct (3).
26. The gas burner according to claim 25, characterized in that: An air regulating movable valve plate (11) is provided at the outlet of the total air intake duct (10) to adjust the size of the communication area between the outlet of the total air intake duct (10) and the inlets of the first air duct (2) and the second air duct (3) respectively.