A pulverized coal self-sustaining internal combustion burner and a self-sustaining combustion control method

Abstract

This invention relates to the field of burner technology, specifically to a pulverized coal self-sustaining internal combustion burner and a self-sustaining combustion control method. The burner includes an igniter, a central air duct, and a combustion unit cylinder. At least one swirl ring is provided at the inlet end of the combustion unit cylinder, and the ignition end of the igniter faces the inlet end of the combustion unit cylinder. A swirl guiding structure is provided on the outer surface of the swirl ring. Central air from the central air duct enters the combustion unit cylinder through the inner ring of the swirl ring, and some pulverized coal enters the combustion unit cylinder through the inner ring of the swirl ring, while some pulverized coal enters the combustion unit cylinder through the swirl guiding structure of the swirl ring. This burner can achieve uniform dispersion of pulverized coal, has low ignition power, and allows for flexible control of the ignition point. The burner can achieve low-load self-sustaining stable combustion operation, reducing both operating and equipment costs.

Description

Technical Field

[0001] This invention relates to a pulverized coal self-sustaining internal combustion burner and a self-sustaining combustion control method, belonging to the field of burner technology. Background Technology

[0002] A thermal power plant, or coal-fired power plant for short, is a factory that uses coal, oil, or natural gas as fuel to produce electricity. Currently, the most commonly used fuel is pulverized coal. The basic production process of power generation is as follows: fuel is burned in a boiler to heat water to produce steam, which converts the chemical energy of the fuel into thermal energy. The steam pressure drives the turbine to rotate, converting the thermal energy into mechanical energy. Then, the turbine drives the generator to rotate, converting the mechanical energy into electrical energy.

[0003] Currently, new energy sources (photovoltaics, wind power, and others) are developing rapidly. From the perspective of energy conservation and environmental protection, thermal power plants often need to carry out deep peak shaving. Improving the flexibility of thermal power units is an effective way to transform the current power supply side. However, deep peak shaving of thermal power plants has high requirements for the self-sustaining combustion and safety of the burners.

[0004] In thermal power plants, burners are devices used in conjunction with boilers. A burner is a general term for a system that sprays fuel and air in a specific manner for combustion. Currently, conventional burners typically use plasma igniters for ignition. During operation, the plasma igniter needs to operate continuously to ensure stable burner operation. However, plasma igniters have a limited lifespan; prolonged continuous operation can easily damage them, increasing equipment and maintenance costs. Furthermore, frequent interruptions and restarts of the burner also increase operating costs.

[0005] Chinese patent application CN101206035A discloses an electrically ignited pulverized coal burner, which consists of a heater and a sleeve. The heater is cylindrical, and the sleeve is fitted over it, forming an annular cavity between the heater and the sleeve. One end of the annular cavity is closed, and the other end is open. A tangential air inlet is located on the sleeve at the closed end of the annular cavity. After the pulverized coal mixes with air, it enters the annular cavity between the heater and the sleeve through the tangential air inlet and spirals forward. Combustion begins near the outlet of the annular cavity, forming a rotating flame that is ejected outwards. However, the spiral movement of the pulverized coal within the annular cavity makes it prone to clogging, and it also limits the ability to flexibly control the ignition point, thus restricting its self-sustaining combustion.

[0006] Chinese patent CN105042585B discloses a pulverized coal burner, including a feed mixer, a central air duct, an air inlet shell, a flame stabilizer, and an igniter. The flame stabilizer is fixedly installed at the front end of the central air duct, and the igniter is inserted from the rear end of the central air duct and extends into the interior of the flame stabilizer. During use, it can fully mix pulverized coal and air, making the combustion of pulverized coal more stable and complete. However, the structure of the flame stabilizer is relatively complex and the manufacturing cost is high. In addition, the igniter extending into the interior of the flame stabilizer can easily cause the flame stabilizer to burn out. Summary of the Invention

[0007] This invention addresses the shortcomings of existing technologies by providing a pulverized coal self-sustaining internal combustion burner and a self-sustaining combustion control method. The burner can achieve uniform dispersion of pulverized coal, has low ignition power, and allows for flexible control of the ignition point. This avoids flameout within the burner and ensures that the components are not damaged. The burner has low overall operating energy and can achieve stable combustion operation under low load. The burner can reduce both operating costs and equipment costs.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a pulverized coal self-sustaining internal combustion burner, the burner including an igniter, a central air duct and a combustion unit cylinder, wherein at least one swirl ring is provided at the inlet end of the combustion unit cylinder, and the ignition end of the igniter faces the inlet end of the combustion unit cylinder;

[0009] The outer surface of the swirl ring is provided with a swirl guiding structure. The central air in the central air duct enters the combustion unit cylinder through the inner ring of the swirl ring. Some pulverized coal enters the combustion unit cylinder through the inner ring of the swirl ring, and some pulverized coal enters the combustion unit cylinder through the swirl guiding structure of the swirl ring.

[0010] The beneficial effects of this invention are as follows: The swirl ring structure allows the pulverized coal to be evenly dispersed within the combustion unit cylinder, making it easier for the pulverized coal to ignite and burn completely, resulting in low ignition power. Simultaneously, the swirl ring causes the pulverized coal to move in a spiral path within the combustion unit cylinder, meaning the pulverized coal surrounds the outer periphery of the flame core, creating a state where the pulverized coal is enveloped in flame. This achieves uniform combustion of the pulverized coal and protects the cylinder wall, preventing it from being easily burned due to prolonged contact with the high-temperature flame. The central airflow design makes the position of the flame core easier to control. By adjusting the pressure of the central airflow, the position of the flame core within the combustion unit cylinder can be adjusted, ensuring that the flame core remains within a safe range. If the flame core is too far from the igniter, the pulverized coal may not ignite in time, and the flame core may easily extinguish. If the flame core is too close to the igniter, the igniter may be easily burned out. These problems would prevent the burner from achieving self-sustaining combustion.

[0011] In the burner described in this invention, the synergistic effect of the swirl ring and the central air duct ensures complete combustion of pulverized coal and a dynamically stable and balanced flame core position, ultimately guaranteeing self-sustaining and stable combustion within the burner. The igniter only needs to be used at the initial ignition stage and does not require prolonged operation, thus extending the igniter's service life. Furthermore, the synergistic effect of the swirl ring and the central air duct effectively protects various components within the burner, thereby reducing equipment investment and maintenance costs. Therefore, the burner described in this invention can reduce both operating costs and equipment costs.

[0012] Based on the above technical solution, the present invention can be further improved as follows:

[0013] Furthermore, the burner is provided with an air supply ring, which is located on the air inlet side of the swirl ring. The surface of the air supply ring is provided with several inclined through holes, and the air outlet of the central air duct is directly opposite the inclined through holes on the air supply ring.

[0014] The beneficial effect of adopting the above-mentioned further scheme is that the structure of the air supply ring can enable the central air to rotate within the air supply ring, thus avoiding the central air from blowing directly onto the ignition point inside the combustion unit cylinder, which would lead to unstable combustion.

[0015] Furthermore, the outer surface of the swirl ring is provided with a plurality of swirl vanes or swirl grooves, and the angle between the swirl vanes or swirl grooves and the axial direction of the swirl ring is 30-60°.

[0016] The inner ring of the swirl ring has a Laval tube structure, and the material of the swirl ring is 310 stainless steel, 304 stainless steel or silicon carbide.

[0017] The beneficial effects of adopting the above-mentioned further solutions are: the material of the swirl ring can give the swirl ring a longer service life; the Laval tube structure can accelerate the central air and facilitate the passage of the central air; the angle limitation of the swirl vanes or swirl channels can not only make the pulverized coal evenly dispersed in the combustion unit cylinder, but also prevent the pulverized coal from clogging the swirl vanes or swirl channels.

[0018] Preferably, the outer surface of the swirl ring is provided with a plurality of swirl grooves.

[0019] The advantages of adopting the above-mentioned preferred solution are: the swirl grooves on the swirl ring can be milled by machining, the machining process can be mechanized, the machining is simpler, and it can ensure the uniform distribution of the swirl grooves on the swirl ring. The swirl ring machined by milling the swirl grooves can be made into an integral part. Compared with the swirl ring machined by welding swirl plates, the swirl ring with the swirl groove structure is less prone to damage.

[0020] Furthermore, the combustion unit cylinder wall surface is provided with balance holes.

[0021] The beneficial effects of adopting the above-mentioned further solution are: when there is insufficiently burned coal powder in the combustion unit cylinder, the insufficiently burned coal powder will stick to the inner wall of the combustion unit cylinder, causing the combustion unit cylinder to be blocked or damaged. The setting of the balance hole can make the insufficiently burned coal powder in the combustion unit cylinder fall out and be blown to the next stage of combustion, thus avoiding the accumulation of ash and carbon in the combustion unit cylinder.

[0022] Furthermore, the swirl rings at each stage are installed in a nested manner, with the innermost swirl ring having a Laval tube structure.

[0023] The beneficial effects of adopting the above-mentioned further scheme are: the connection of multi-stage swirl rings can divide the pulverized coal into spiral paths of different diameters to enter the combustion unit cylinder, thereby making the pulverized coal dispersion in the combustion unit cylinder more uniform and more conducive to the self-sustaining and stable combustion of the burner.

[0024] Furthermore, the burner includes at least two or more combustion unit cylinders, with the outlet end of the previous combustion unit cylinder sequentially connected to the inlet end of the next combustion unit cylinder.

[0025] The beneficial effects of adopting the above-mentioned further scheme are: the setting of multi-stage combustion unit cylinders can realize multi-stage amplification of combustion and effectively reduce ignition energy consumption.

[0026] Furthermore, at least one swirl ring is provided between each of the combustion unit cylinders, and pulverized coal enters each stage of the combustion unit cylinder through the swirl guiding structure of the swirl ring.

[0027] The beneficial effect of adopting the above-mentioned further scheme is that swirl rings are provided between each stage of the combustion unit cylinder, which can enable the pulverized coal to be evenly dispersed in each stage of the combustion unit cylinder, thereby achieving uniform and stable combustion.

[0028] Furthermore, the burner includes a housing, and the igniter, combustion unit cylinder and swirl ring are all installed inside the housing. A pulverized coal inlet is provided on the side of the housing.

[0029] The beneficial effect of adopting the above-mentioned further solution is that the outer casing makes the installation and use of the entire burner easier.

[0030] Furthermore, a reflux jacket is provided on the inner wall of the outer shell, and a reflux air inlet is provided at the end of the reflux jacket near the igniter. The reflux jacket is connected to the last stage combustion unit cylinder at the outlet end of the burner through a reverse jet stabilizing nozzle, and the outlet of the reverse jet stabilizing nozzle faces the ignition position of the igniter.

[0031] The beneficial effects of adopting the above-mentioned further scheme are: the recirculation air is introduced into the recirculation jacket, which can cool the outer shell and the combustion unit cylinder to prevent them from being burned. In addition, the heat collected by the recirculation air is blown back into the combustion unit cylinder to heat the pulverized coal, thereby achieving full utilization of energy. While improving the ignition characteristics of the burner, it can also ensure the safety of the equipment itself.

[0032] This invention also discloses a control method for stable combustion using the aforementioned pulverized coal self-sustaining internal combustion burner. The control method is as follows: pulverized coal enters the combustion unit cylinder through the swirl ring; the igniter ignites the pulverized coal in the combustion unit cylinder to form a flame core; the pulverized coal moves in a spiral path within the combustion unit cylinder, ensuring uniform dispersion; the igniter is then turned off, and the uniformly dispersed pulverized coal in the combustion unit cylinder is ignited by the burning coal; the position of the flame core and the combustion status within the combustion unit cylinder are adjusted by regulating the central airflow in the central air duct, thereby achieving stable combustion within the burner.

[0033] The beneficial effects of the control method described in this invention are as follows: the pulverized coal moves in a spiral path within the combustion unit cylinder, which allows the pulverized coal to be evenly dispersed within the combustion unit cylinder, thereby facilitating the ignition and complete combustion of the pulverized coal. At the same time, the pulverized coal surrounds the outer periphery of the flame core, forming a state where the pulverized coal is wrapped in flame, which not only achieves uniform combustion of the pulverized coal but also protects the cylinder wall of the combustion unit cylinder. The setting of the central airflow makes the position of the flame core easier to control. By adjusting the pressure of the central airflow, the position of the flame core within the combustion unit cylinder can be adjusted, ensuring that the position of the flame core is always within a safe range. This not only ensures that the fire within the combustion unit cylinder is not easily extinguished but also guarantees the long-term safety of all components.

[0034] During operation, the optimal position of the flame core is determined based on the structure and usage requirements of each component. Adjustments to the central airflow and pulverized coal intake speed allow for adjustments to the flame core position, ultimately improving combustion efficiency and extending the lifespan of each component. Furthermore, the control method maintains the flame core in a stable and balanced position, ensuring smooth and continuous combustion. The combustion at the flame core creates negative pressure; under this pressure difference, the central airflow carries some pulverized coal through the inner ring of the swirl ring to replenish the flame core, preventing it from extinguishing and maintaining pressure balance to ensure self-sustaining combustion within the burner.

[0035] Conventional burners often require continuous operation of the igniter for stable combustion, resulting in high energy consumption and easy damage to the igniter, increasing equipment and maintenance costs. However, the stable combustion control method described in this application can achieve continuous stable combustion by adjusting the central airflow. The central airflow can be achieved using conventional compressed air. Compared with the high power consumption of igniters, the use of compressed air greatly reduces energy consumption. Under the same size, the energy consumption of the burner described in this invention is only 1% of that of conventional burners. Attached Figure Description

[0036] Figure 1 This is a three-dimensional structural diagram of the burner described in the embodiment;

[0037] Figure 2 This is a left view of the burner described in the embodiment;

[0038] Figure 3 This is a bottom view of the burner described in the embodiment;

[0039] Figure 4 for Figure 3 AA section view in the middle;

[0040] Figure 5 for Figure 4 A magnified view of section B;

[0041] Figure 6 A schematic diagram of the combustion unit cylinder, air supply ring, and central air duct.

[0042] Figure 7 A schematic diagram of the combustion unit cylinder and the reverse jet flame-stabilizing nozzle;

[0043] Figure 8 This is a schematic diagram of the combustion unit cylinder.

[0044] Figure 9 This is a schematic diagram of a two-stage swirl ring structure;

[0045] Figure 10 This is a schematic diagram of the swirl ring structure;

[0046] Figure 11 This is a schematic diagram of the air supply ring structure;

[0047] Figure 12 This is a schematic diagram of a lever switch.

[0048] In the diagram, 1. Igniter; 2. Central air duct; 3. Combustion unit cylinder; 4. Swirl ring; 5. Air supply ring; 6. Inclined through hole; 7. Swirl groove; 8. Balance hole; 9. Outer shell; 10. Return jacket; 11. Return air inlet; 12. Reverse jet flame stabilizer nozzle; 13. Pull-rod switch; 14. Pulverized coal inlet. Detailed Implementation

[0049] The specific embodiments of the present invention will be described in detail below. The present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used is for describing particular embodiments only and is not intended to limit the invention.

[0051] like Figures 1-5 As shown, a pulverized coal self-sustaining internal combustion burner is disclosed. The burner includes an igniter 1, a central air duct 2, and a combustion unit cylinder 3. At least one swirl ring 4 is provided at the inlet end of the combustion unit cylinder 3. The ignition end of the igniter 1 faces the inlet end of the combustion unit cylinder 3. The igniter 1 can be a conventionally known product. In this embodiment, a plasma igniter 1 is used.

[0052] The outer surface of the swirl ring 4 is provided with a swirl guiding structure. The central air (compressed air) in the central air duct 2 enters the combustion unit cylinder 3 through the inner ring of the swirl ring 4. Some coal powder enters the combustion unit cylinder 3 through the inner ring of the swirl ring 4, and some coal powder enters the combustion unit cylinder 3 through the swirl guiding structure of the swirl ring 4.

[0053] Specifically, such as Figure 6 and Figure 11 As shown, the burner is provided with an air supply ring 5, which is located on the air inlet side of the swirl ring 4. The surface of the air supply ring 5 is provided with several inclined through holes 6, and the air outlet of the central air duct 2 is directly opposite the inclined through holes 6 on the air supply ring 5.

[0054] Specifically, the outer surface of the swirl ring 4 is provided with a plurality of swirl vanes or swirl grooves 7, and the angle between the swirl vanes or swirl grooves 7 and the axial direction of the swirl ring 4 is 30-60°; the inner ring of the swirl ring 4 has a Laval tube structure, and the material of the swirl ring 4 is 310 stainless steel, 304 stainless steel or silicon carbide.

[0055] In this embodiment, as Figure 10 As shown, the outer surface of the swirl ring 4 is provided with a plurality of evenly distributed swirl grooves 7, and the angle between the swirl grooves 7 and the axial direction of the swirl ring 4 is 45°.

[0056] Specifically, such as Figure 8 As shown, the combustion unit cylinder 3 has a balance hole 8 on its wall surface. The balance hole 8 can be a circular hole or an elongated hole, etc., to allow unburned coal powder to be discharged and to prevent carbon buildup on the inner wall of the combustion unit cylinder 3.

[0057] Specifically, the swirl rings 4 at each level are installed in a nested manner, and the innermost swirl ring 4 has a Laval tube structure.

[0058] In this embodiment, as Figure 9 As shown, the burner includes two stages of swirl rings 4 connected together. The more stages of swirl rings 4 there are, the more conducive it is to the uniform dispersion of pulverized coal in the combustion unit cylinder 3. However, in actual use, the optimal number of swirl rings 4 will be determined based on the balance between equipment cost and operating cost, as well as the size of the equipment.

[0059] Specifically, the burner includes at least two or more combustion unit cylinders 3, with the outlet end of the previous combustion unit cylinder 3 sequentially connected to the inlet end of the next combustion unit cylinder 3.

[0060] In this embodiment, as Figure 4 As shown, the burner includes a three-stage combustion unit cylinder 3. The combustion unit cylinders 3, which are connected sequentially from the igniter 1 from near to far, are the first-stage combustion unit cylinder 3, the second-stage combustion unit cylinder 3, and the third-stage combustion unit cylinder 3. The diameter of the combustion unit cylinders 3 connected sequentially from the igniter 1 from near to far increases at each stage. The space inside the first-stage combustion unit cylinder 3 at the igniter 1 is relatively small, which is more conducive to ignition and reduces the ignition power.

[0061] Specifically, each of the combustion unit cylinders 3 is provided with at least one swirl ring 4, and the pulverized coal enters each stage of the combustion unit cylinder 3 through the swirl guiding structure of the swirl ring 4.

[0062] In this embodiment, two swirling rings 4 are provided between each stage of the combustion unit cylinder 3 (the installation structure of the swirling ring 4 at the inlet end of the first stage combustion unit cylinder 3 is the same, so it is not shown in detail in the figure), so that the pulverized coal in each stage of the combustion unit cylinder 3 can achieve spiral path movement and the pulverized coal can be evenly dispersed in each stage of the combustion unit cylinder 3, so that the pulverized coal can achieve full and stable combustion.

[0063] Specifically, the burner includes a housing 9, and the igniter 1, combustion unit cylinder 3 and swirl ring 4 are all installed inside the housing 9. A pulverized coal inlet 14 is provided on the side of the housing 9.

[0064] In this embodiment, as Figure 4 and Figure 12 As shown, the igniter 1 is installed inside the housing 9 via a flange. The housing 9 is equipped with a lever switch 13 for adjusting the pulverized coal inlet 14, thereby controlling the amount of pulverized coal entering.

[0065] Specifically, such as Figure 4 and Figure 7As shown, a reflux jacket 10 is provided on the inner wall of the outer shell 9. A reflux air inlet 11 is provided at the end of the reflux jacket 10 near the igniter 1. The reflux jacket 10 is connected to the last stage combustion unit cylinder 3 at the outlet end of the burner through a reverse jet flame stabilizing nozzle 12. The outlet of the reverse jet flame stabilizing nozzle 12 faces the ignition position of the igniter 1.

[0066] In this embodiment, as Figure 1 and Figure 4 As shown, the recirculation air inlet 11 is located on the flange connecting the igniter 1 and the housing 9. The recirculation air uses conventional compressed air. The recirculation air can cool the housing 9 and the combustion unit cylinder 3, preventing them from burning out. In addition, the heat collected by the recirculation air is blown back into the combustion unit cylinder 3 to heat the pulverized coal, thereby achieving full utilization of energy. This improves the ignition characteristics of the burner while ensuring the safety of the equipment itself.

[0067] The control method for stable combustion using the pulverized coal self-sustaining internal combustion burner described in this embodiment is as follows: Pulverized coal enters the combustion unit cylinder 3 through the swirl ring 4. The igniter 1 ignites the pulverized coal in the combustion unit cylinder 3 to form a flame core. The pulverized coal moves in a spiral path within the combustion unit cylinder 3, so that the pulverized coal is evenly dispersed within the combustion unit cylinder 3. The igniter 1 is turned off, and the evenly dispersed pulverized coal in the combustion unit cylinder 3 is ignited by the burning pulverized coal. The position of the flame core and the combustion status within the combustion unit cylinder 3 are adjusted by regulating the central airflow in the central air duct 2, thereby achieving stable combustion within the burner.

[0068] In this embodiment, a three-stage combustion unit cylinder 3 is used, which can realize the step-by-step amplification of combustion. The ignition process is completed in a relatively small space, and only a very low ignition power is needed to achieve ignition, thus reducing ignition energy consumption.

[0069] During operation, the optimal position of the flame core is determined based on the structure and usage requirements of each component. The overall pulverized coal velocity is adjusted according to the central airflow and the pulverized coal inlet velocity, thereby adjusting the flame core position and ultimately improving combustion efficiency and the service life of each burner component. The functional relationship between the flame core position and the pulverized coal velocity is as follows:

[0070]

[0071] Where: L is the location of the ignition core, that is, the distance between the ignition point of the pulverized coal and the igniter, in meters;

[0072] c is the specific heat capacity of the mixed gas, 1.3 kJ / (kg·K);

[0073] Q hThe calorific value is the heat of volatile matter per unit mass, expressed in kJ / kg; the range is 19000-26000 kJ / kg.

[0074] C m The value represents the coal powder concentration, in kg / kg; the range is 0.25-0.6.

[0075] υ ’ Let τ be the percentage of all volatiles released as τ approaches ∞; τ is time, in seconds.

[0076] T h T c These are the temperatures of the thermal vortex region and the pulverized coal gas flow, respectively, in K;

[0077] T h The value range is 1273-1473K, T c The value is 348K;

[0078] β is the drag coefficient of the self-sustaining internal combustion burner, which is dimensionless and related to the structure of the device, and its value is ≤1;

[0079] u1 is the pulverized coal wind speed, in m / s; its value ranges from 18 to 26 m / s.

[0080] d0 is the equivalent diameter of the entrance to the fire core area, the size of which depends on the specific structure, in meters (m).

[0081] d1 is the inner diameter of the self-sustaining internal combustion burner, the size of which depends on the specific structure, in meters (m).

[0082] X is the volume correction factor for the thermal vortex region. Once the structure is determined, this value is related to the regenerating air flow rate and the ejection method. Experiments have verified that X is approximately 0.2-0.6.

[0083] k0 is the frequency factor, 1 / s, with a value of 2.5 × 10⁻⁶. 4 E is the activation energy, kJ / kg·mol, with a value of 8 × 10⁻⁶. 4 kJ / kg·mol; R is the gas constant kJ / (kg·mol·K), with a value of 8.314 kJ / (kg·mol·K); T p Let K and T represent the temperature of the pulverized coal. p =T c .

[0084] The above formula shows that the ignition distance of pulverized coal is closely related to the temperature of the thermal vortex zone, the flow velocity of the pulverized coal airflow, the burner resistance coefficient, and the initial temperature of the pulverized coal airflow. It is also related to the characteristics of the pulverized coal, the pulverized coal concentration, and the heat dissipation intensity between the thermal vortex and the wall. Once the structure of the self-sustaining internal combustion burner and the characteristics of the pulverized coal are determined, the ignition distance of the pulverized coal airflow under different thermal vortex zone temperatures, different pulverized coal concentrations, and different flow velocities can be calculated, thus facilitating control during operation.

[0085] In addition, the control method described above can keep the flame core position in a stable and balanced position, so that the combustion process can proceed smoothly and continuously. Combustion at the flame core will cause negative pressure. Under the action of pressure difference, the central air will carry some coal powder through the inner ring of the swirl ring 4 to replenish the flame core in time, so as to prevent the flame core from going out, thereby maintaining gas pressure balance and ensuring self-sustaining stable combustion in the burner.

[0086] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are exhaustively listed. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0087] For those skilled in the art, various modifications and improvements can be made without departing from the concept of the present invention, and these modifications and improvements are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the appended claims.

Claims

1. A pulverized coal self-sustaining internal combustion burner, characterized in that, The burner includes an igniter (1), a central air duct (2), and a combustion unit cylinder (3). At least one swirl ring (4) is provided at the inlet end of the combustion unit cylinder (3), and the ignition end of the igniter (1) faces the inlet end of the combustion unit cylinder (3). The outer surface of the swirl ring (4) is provided with a swirl guiding structure. The central air in the central air duct (2) enters the combustion unit cylinder (3) through the inner ring of the swirl ring (4). Some coal powder enters the combustion unit cylinder (3) through the inner ring of the swirl ring (4), and some coal powder enters the combustion unit cylinder (3) through the swirl guiding structure of the swirl ring (4).

2. The pulverized coal self-sustaining internal combustion burner according to claim 1, characterized in that, The burner is provided with an air supply ring (5), which is located on the air inlet side of the swirl ring (4). The surface of the air supply ring (5) is provided with several inclined through holes (6), and the air outlet of the central air duct (2) is directly opposite the inclined through holes (6) on the air supply ring (5).

3. The pulverized coal self-sustaining internal combustion burner according to claim 1, characterized in that, The outer surface of the swirling ring (4) is provided with a plurality of swirling vanes or swirling grooves (7), and the angle between the swirling vanes or swirling grooves (7) and the axial direction of the swirling ring (4) is 30-60°. The inner ring of the swirl ring (4) has a Laval tube structure, and the material of the swirl ring (4) is 310 stainless steel, 304 stainless steel or silicon carbide.

4. The pulverized coal self-sustaining internal combustion burner according to claim 1, characterized in that, The combustion unit cylinder (3) has balance holes (8) on its wall surface.

5. The pulverized coal self-sustaining internal combustion burner according to claim 1, characterized in that, The swirl rings (4) at each level are installed in a sleeve manner, and the innermost swirl ring (4) has a Laval tube structure.

6. The pulverized coal self-sustaining internal combustion burner according to claim 1, characterized in that, The burner includes at least two or more combustion unit cylinders (3), with the outlet end of the upper combustion unit cylinder (3) sequentially connected to the inlet end of the lower combustion unit cylinder (3).

7. The pulverized coal self-sustaining internal combustion burner according to claim 6, characterized in that, Each of the combustion unit cylinders (3) is provided with at least one stage of swirl ring (4), and pulverized coal enters each stage of the combustion unit cylinder (3) through the swirl guiding structure of the swirl ring (4).

8. A pulverized coal self-sustaining internal combustion burner according to any one of claims 1-7, characterized in that, The burner includes a housing (9), and the igniter (1), combustion unit cylinder (3) and swirl ring (4) are all installed inside the housing (9). The side of the housing (9) is provided with a pulverized coal inlet (14).

9. A pulverized coal self-sustaining internal combustion burner according to claim 8, characterized in that, The inner wall of the outer shell (9) is provided with a reflux jacket (10), and the end of the reflux jacket (10) near the igniter (1) is provided with a reflux air inlet (11). The reflux jacket (10) is connected to the last stage combustion unit cylinder (3) at the outlet end of the burner through a reverse jet flame stabilizing nozzle (12). The outlet of the reverse jet flame stabilizing nozzle (12) faces the ignition position of the igniter (1).

10. A control method for stable combustion using a pulverized coal self-sustaining internal combustion burner according to any one of claims 1-9, characterized in that, The control method is as follows: pulverized coal enters the combustion unit cylinder (3) through the swirl ring (4), and the igniter (1) ignites the pulverized coal in the combustion unit cylinder (3) to form a fire core. The pulverized coal moves in a spiral path in the combustion unit cylinder (3) so that the pulverized coal is evenly dispersed in the combustion unit cylinder (3). The igniter (1) is turned off, and the pulverized coal evenly dispersed in the combustion unit cylinder (3) is ignited by the burning pulverized coal. The position of the fire core and the combustion situation in the combustion unit cylinder (3) are adjusted by adjusting the central air in the central air duct (2) to achieve self-sustaining stable combustion in the burner.

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