Pulverized coal rotational flow stable combustion burner based on focus-adjustable laser igniter and stable combustion method

Abstract

The pulverized coal rotational flow stable combustion burner comprises a shell, a primary air pipe, a first swirler, a backflow cap and a laser generator assembly, a secondary air duct is defined between the primary air pipe and an air guide section, the first swirler is arranged in the secondary air duct, the backflow cap is arranged in the secondary air duct, and the laser generator assembly is arranged in the secondary air duct. The backflow cap is arranged in the combustion chamber and located at the outlet end of the primary air pipe. The laser generator assembly is used for emitting sheet-shaped laser beams into the combustion chamber so as to ignite pulverized coal in the combustion chamber. According to the invention, the size and the shape of the laser beam spot are adjusted, and the ignition efficiency and the stability in the pulverized coal combustion process are obviously improved by the aid of a cooling and combustion control strategy in which tertiary air and secondary air are matched; meanwhile, the laser power and mode can be flexibly switched, different coal quality and load working conditions can be adapted, the adaptability and combustion efficiency of the combustor are greatly improved, the service life of a hearth and related parts is prolonged, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal burners, and particularly relates to a pulverized coal swirl-stabilized combustion burner and a combustion stabilization method based on an adjustable-focus laser igniter. Background Art

[0002] In existing double-cone reverse injection burners, the pulverized coal flow passes through the primary air duct and the reflux cap and is reverse injected into the ignition zone for ignition. Depending on the entrainment effect of the swirling secondary air, the pulverized coal flow moves towards the burner outlet and forms a high-temperature zone at the junction of the front cone and the rear cone. The reflux generated inside the burner brings the heat of the high-temperature zone back to the ignition zone, which is crucial for the ignition of pulverized coal.

[0003] However, when dealing with inferior coal, especially pulverized coal with low volatile content, in order to achieve self-sustaining combustion, the ignition zone requires more heat, but the heat brought by traditional reflux is often insufficient. Currently, two measures are usually taken in engineering: one is to increase heat reflux by optimizing air distribution and extending the residence time of pulverized coal, but this is prone to coking problems; the other is to introduce additional heat sources, such as fuel oil guns, but the long-term use of diesel for combustion assistance has high costs and may cause equipment damage. Summary of the Invention

[0004] The inventors found in their research that one idea is to introduce a laser beam as an ignition heat source, that is, a laser igniter. The essence of a laser igniter is to transfer the heat converted from electrical energy to pulverized coal through a small-range and highly directional light beam.

[0005] However, based on the characteristics of lasers, when a laser igniter is used for pulverized coal ignition, the following problems exist:

[0006] 1. The power is sufficient but the heating area is too small, and only a very small range of pulverized coal can be ignited. Therefore, the requirement for the volatile content of pulverized coal is relatively high, because only pulverized coal with a sufficiently high volatile content can form a secondary flame with sufficient intensity after being ignited by the laser beam, so as to ignite the adjacent pulverized coal;

[0007] 2. The energy of the laser beam is too concentrated. When the pulverized coal concentration on the laser beam path is insufficient, the proportion of the effective heat absorbed by the pulverized coal is relatively low, and a considerable part of the heat will be directly transferred to the boiler wall surface pointed at the end of the laser beam. On the one hand, this will cause waste of heat, and on the other hand, the waste heat absorbed by the wall surface will cause the problem of wall surface burnout.

[0008] In view of the above problems, the present invention proposes a pulverized coal swirl-stabilized combustion burner and a combustion stabilization method based on an adjustable-focus laser igniter, aiming to provide a burner technology that can effectively solve the problem of ignition of low-volatile pulverized coal, reduce coking and equipment damage, and at the same time reduce the operating cost.

[0009] The pulverized coal swirl-stabilized combustor based on an adjustable-focus laser igniter according to an embodiment of the present invention includes a housing, a primary air duct, a first swirler, a return cap, and a laser generator assembly. The housing includes an air guiding section, a front cone section, and a rear cone section that are sequentially communicated. The front cone section and the rear cone section define a combustion chamber. An ignition zone is formed at the inlet end of the front cone section, and a high-temperature zone is formed in the combustion chamber at the intersection area between the front cone section and the rear cone section.

[0010] The outlet end of the primary air duct extends into the rear cone section through the air guiding section. The inlet end of the primary air duct is arranged outside the housing. A secondary air duct is defined between the primary air duct and the air guiding section. The first swirler is arranged in the secondary air duct and is used to introduce secondary air into the ignition zone. The return cap is arranged in the combustion chamber and is located at the outlet end of the primary air duct.

[0011] At least part of the laser generator assembly is arranged in the secondary air duct and is used to emit a sheet-shaped laser beam into the combustion chamber to ignite the pulverized coal in the combustion chamber.

[0012] In some embodiments, the laser generator assembly includes a laser and a lens assembly. The laser beam emitted by the laser is shaped into a sheet-shaped laser beam by the lens assembly, and the width dimension of the sheet-shaped laser beam is adjustable.

[0013] In some embodiments, the power output mode of the laser can be switched between two types: pulsed laser and continuous laser.

[0014] In some embodiments, a tertiary air inlet is formed on the front cone section and is located upstream of the high-temperature zone. The tertiary air inlet is used to introduce tertiary air into the combustion chamber.

[0015] In some embodiments, a visual TV and a temperature sensor are arranged on the housing. The visual TV is used to monitor the combustion state of the flame in the combustion chamber, and the temperature sensor is used to monitor the temperature of the housing wall surface of the high-temperature zone.

[0016] In some embodiments, an annular channel is defined between the inner side wall of the return cap and the outer side wall of the primary air duct, and a second swirler is arranged in the annular channel.

[0017] In some embodiments, the pulverized coal swirl-stabilized combustor based on an adjustable-focus laser igniter according to an embodiment of the present invention includes a bluff body. The bluff body is sleeved on the primary air duct and is located between the primary air duct and the first swirler in the inner and outer directions. The bluff body has an installation cavity and a light passing hole facing the combustion chamber. The emitting end of the laser is arranged in the installation cavity, and the lens assembly is arranged in the light passing hole.

[0018] In some embodiments, the bluff body includes a conical section and a cylindrical section. The conical section is arranged on the side of the cylindrical section away from the combustion chamber in the axial direction of the primary air duct. The outer diameter of the conical section gradually increases in the direction from the front conical section towards the rear conical section. The outer wall surface of the cylindrical section is connected to the first swirler.

[0019] In some embodiments, the pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to the embodiment of the present invention includes a deflector plate. The deflector plate is arranged inside the front conical section. One end of the deflector plate is connected to the first swirler, and the other end of the deflector plate bends from the outside towards the direction of the light passing hole to deflect a part of the secondary air introduced by the first swirler to the lens assembly.

[0020] The pulverized coal swirl-stabilized combustion method based on an adjustable-focus laser igniter according to the embodiment of the present invention includes:

[0021] Emit a sheet-shaped laser beam into the combustion chamber, and simultaneously monitor the combustion state of the flame in the combustion chamber and the wall temperature of the high-temperature zone in the combustion chamber.

[0022] When the combustion intensity of the flame in the combustion chamber is lower than the first preset value, increase the emission power and width size of the sheet-shaped laser beam. If the shape of the flame in the combustion chamber is unstable, switch the power output mode of the sheet-shaped laser beam to pulsed laser.

[0023] When the combustion intensity of the flame in the combustion chamber is higher than the second preset value, if the distance between the flame in the ignition zone and the secondary air inlet exceeds the third preset value, increase the primary air velocity. If the flame temperature in the ignition zone is too high and the flame volume is too large, increase the secondary air velocity.

[0024] When the wall temperature of the high-temperature zone in the combustion chamber reaches the pulverized coal melting temperature, introduce tertiary air into the front cone of the burner and simultaneously reduce the flow rate of the secondary air.

[0025] The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to the embodiment of the present invention realizes the adjustment of the size and shape of the laser beam spot by setting a bluff body and a laser generator assembly, and is supplemented with a cooling and combustion control strategy of the cooperation between the tertiary air and the secondary air, significantly improving the ignition efficiency and stability of the pulverized coal combustion process. At the same time, the laser power and mode can be flexibly switched, which can adapt to different coal qualities and load conditions, greatly improving the adaptability and combustion efficiency of the burner, prolonging the service life of the furnace and related components, and reducing the operating cost. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to the embodiment of the present invention meets the high-efficiency combustion requirements of industrial pulverized coal furnaces while taking into account the safety and service life of key parts, and has obvious innovation and practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1It is a schematic diagram of the high temperature zone and the ignition zone in the pulverized coal swirl stable combustion burner according to an embodiment of the present invention.

[0027] Figure 2 It is a schematic diagram of the flow field in the pulverized coal swirl stable combustion burner according to an embodiment of the present invention.

[0028] Figure 3 It is a schematic diagram of the flow of pulverized coal in a pulverized coal swirl stable combustion burner according to an embodiment of the present invention.

[0029] 100. Pulverized coal swirl steady combustion burner; 1. Shell; 101. Air guide section; 102. Front cone section; 103. Rear cone section; 104. Combustion chamber; 105. Tertiary air inlet; 2. Primary air duct; 3. First swirler; 4. Backflow cap; 5. Secondary air duct; 6. Laser generator assembly; 601. Laser; 602. Lens assembly; 7. Video TV; 8. Temperature sensor; 9. Second swirler; 10. Blunt body; 1001. Mounting cavity; 1002. Light hole; 1003. Conical section; 1004. Cylindrical section; 11. Guide plate. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0031] like Figures 1 to 3 As shown, the pulverized coal swirl steady combustion burner 100 based on the adjustable focus laser igniter of the embodiment of the present invention comprises a housing 1, a primary air duct 2, a first swirler 3, a reflow cap 4 and a laser generator assembly 6. The housing 1 comprises an air guide section 101, a front cone section 102 and a rear cone section 103 which are connected in sequence, and the front cone section 102 and the rear cone section 103 define a combustion chamber 104, wherein the inlet end of the front cone section 102 forms an ignition zone, and the junction area of ​​the front cone section 102 and the rear cone section 103 forms a high temperature zone in the combustion chamber 104.

[0032] The outlet end of the primary air duct 2 extends into the rear cone section 103 through the air guide section 101, and the inlet end of the primary air duct 2 is arranged outside the shell 1, and a secondary air duct 5 is defined between the primary air duct 2 and the air guide section 101. The first cyclone 3 is arranged in the secondary air duct 5, and is used to introduce the secondary air into the ignition zone. The reflux cap 4 is arranged in the combustion chamber 104 and is located at the outlet end of the primary air duct 2.

[0033] At least a portion of the laser generator assembly 6 is disposed in the secondary air duct 5 , and is used to emit a sheet-shaped laser beam into the combustion chamber 104 to ignite the coal powder in the combustion chamber 104 .

[0034] When the pulverized coal swirl-stabilized combustor 100 based on an adjustable-focus laser igniter according to an embodiment of the present invention is in use, pulverized coal is sent into the combustion chamber 104 through the primary air duct 2. The pulverized coal flow passes through the reflux cap 4 and is reversely sprayed near the high-temperature zone. The swirling secondary air is introduced into the ignition zone through the first swirler 3, increasing the residence time and mixing effect of the pulverized coal. The laser generator assembly 6 emits a sheet-shaped laser beam, which acts on the pulverized coal in the ignition zone to provide the heat required for ignition. After the pulverized coal ignites, the formed high-temperature zone is at the junction of the rear cone section 103 and the front cone section 102, which is conducive to the stable progress of combustion. The reflux generated in the combustion chamber 104 brings the heat of the high-temperature zone back to the ignition zone, contributing to the further ignition and combustion of the pulverized coal in the ignition zone.

[0035] Due to the high directivity of the laser beam, the position of heat release can be controlled more precisely. Compared with traditional ignition technologies, the present invention can use the laser generator assembly 6 to efficiently ignite at an appropriate power and mode, achieving the efficiency and effect of rapid and stable ignition, and significantly expanding the adaptability to inferior coal.

[0036] In addition, at the same time, the sheet-shaped laser beam only expands in one direction (forming a flat sheet), and remains narrow in the other direction to maintain the energy density. A large amount of pulverized coal after the reverse spraying of the reflux cap 4 will pass through the sheet-shaped laser beam. Compared with traditional lasers, the contact probability between the sheet-shaped laser beam of the present invention and the pulverized coal increases by at least one order of magnitude, so that the energy of the sheet-shaped laser beam is basically absorbed by the pulverized coal for combustion. Therefore, it also avoids damage to the boiler wall by the laser, can save the device consumables for absorbing the excess laser, and reduces the cost.

[0037] In some embodiments, the laser generator assembly 6 includes a laser 601 and a lens assembly 602. The laser beam emitted by the laser 601 is shaped into a sheet-shaped laser beam by the lens assembly 602, and the width dimension of the sheet-shaped laser beam is adjustable.

[0038] The laser 601 generates a high-energy laser beam, which is usually dot-shaped or cylindrical. The laser beam passes through the lens assembly 602, which is responsible for shaping the laser beam into a sheet shape to more effectively cover a larger area. The width dimension of the sheet-shaped laser beam can be adjusted by adjusting the lens assembly 602 or the laser 601 itself to adapt to different pulverized coal characteristics and combustion conditions.

[0039] By adjusting the width dimension of the sheet-shaped laser beam, the interaction between the laser beam and the pulverized coal can be optimized, and the ignition reliability can be improved. The sheet-shaped laser beam can cover a wider pulverized coal area, thus accelerating the ignition process of the pulverized coal and improving the combustion efficiency. The adjustable width dimension means that the laser igniter can adapt to pulverized coal with different volatile matter contents, increasing the applicable range of the burner. Compared with the dot-shaped laser beam, the sheet-shaped laser beam reduces the local concentration of heat and reduces the energy waste caused by insufficient pulverized coal concentration. Due to the more uniform heat distribution, the risk of damage caused by local overheating is reduced.

[0040] Optionally, the lens assembly 602 is composed of cylindrical lenses. The working principle of the cylindrical lens is similar to that of an ordinary spherical lens. However, due to its unique geometric shape, the cylindrical lens focuses or disperses light along one direction (usually the horizontal or vertical direction), and does not produce focusing or dispersing effects on the axis perpendicular to this direction. This characteristic makes the cylindrical lens particularly useful in the laser igniter because they can shape the laser beam into a sheet-shaped beam, thus generating a wider ignition area in the combustion chamber. By adjusting the focal length of the cylindrical lens, the adjustment of the width dimension of the sheet-shaped laser beam can be achieved. This technology belongs to the prior art and will not be elaborated here in the present invention.

[0041] In some embodiments, the power output mode of the laser 601 can be switched between two types: pulsed laser and continuous laser.

[0042] In the case where the pulverized coal is difficult to ignite or high power output is required to quickly ignite the pulverized coal, the laser 601 can be switched to the pulsed laser mode. The pulsed laser is characterized by high peak power and can provide a large amount of heat in a short time, which helps the rapid ignition of the pulverized coal.

[0043] When the pulverized coal is relatively easy to ignite, or stable and continuous heating is required to ensure combustion stability, the laser 601 can be switched to the continuous laser mode. The continuous laser provides a stable power output, which helps to maintain the stability of the combustion process.

[0044] The free switching between the pulsed laser and the continuous laser enables the burner to be adjusted according to the type of pulverized coal and the changes in combustion conditions, improving the applicability and reliability of the burner. For different types of pulverized coal, such as high-volatile pulverized coal and low-volatile pulverized coal, different power output modes can be adopted to achieve the best ignition effect. In the pulsed laser mode, the high-power pulse can quickly ignite the pulverized coal, reducing the ignition time and improving the combustion efficiency; in the continuous laser mode, the stable power output helps the continuous progress of combustion.

[0045] Optionally, the maximum input power of the laser generator assembly 6 should reach at least 5% of the burner power.

[0046] In some embodiments, a tertiary air inlet 105 located upstream of the high temperature zone is opened on the front cone section 102 , and the tertiary air inlet 105 is used to introduce tertiary air into the combustion chamber 104 .

[0047] like Figure 1 and Figure 2 As shown, when the wall temperature of the high-temperature zone is too high, in order to prevent the wall temperature of the high-temperature zone from reaching the coking temperature (melting temperature of coal powder) and prevent the wall from burning due to excessive temperature, the tertiary air flow ratio is increased to move the high-temperature zone upstream, which can quickly reduce the wall temperature near the high-temperature zone, thereby avoiding burning due to local overheating. When the wall temperature of the high-temperature zone is too low, the tertiary air flow is appropriately reduced while the secondary air is increased to fully ensure the high-temperature combustion process and improve the heating effect of the reflux heat on the coal powder ignition zone, thereby ensuring the continuous stability of the combustion reaction. This adjustment method not only takes into account the ignition safety, but also prolongs the service life of the shell 1 and related components.

[0048] In some embodiments, a video TV 7 and a temperature sensor 8 are provided on the shell 1. The video TV 7 is used to monitor the combustion state of the flame in the combustion chamber 104, and the temperature sensor 8 is used to monitor the wall temperature of the shell 1 in the high temperature area.

[0049] The video TV 7 can monitor the flame state in the combustion chamber 104 in real time, including the temperature, shape, size and color of the flame, so as to evaluate the stability and efficiency of the combustion. By observing the changes in the flame, abnormal conditions in the combustion process, such as flame instability, flameout or incomplete combustion, can be discovered in time, so that timely measures can be taken to make adjustments. Temperature sensors such as the temperature sensor 8 can monitor the wall temperature of the shell 1 in the high temperature area of ​​the combustion chamber 104 in real time to ensure that the temperature in the combustion chamber 104 is controlled within a safe range. By monitoring the wall temperature, damage to the shell 1 material caused by excessive temperature can be prevented, thereby ensuring the safety of the equipment.

[0050] Through the real-time data of the visual television 7 and the temperature sensor 8, the operator can understand the combustion status more quickly and accurately, thus improving the monitoring efficiency. Real-time monitoring can timely discover and deal with potential risks in the combustion process, reduce the probability of accidents, and ensure the safety of equipment and operators. By analyzing the flame and temperature data, the combustion parameters such as air volume, coal powder flow rate and laser power can be optimized to achieve the best combustion effect.

[0051] In some embodiments, an annular channel is defined between the inner wall of the return cap 4 and the outer wall of the primary air duct 2 , and a second cyclone 9 is disposed in the annular channel.

[0052] When the pulverized coal is ejected from the reflux cap 4, a tangential velocity is added under the action of the second swirler 9 to form a swirl. Through the swirl of the pulverized coal and in cooperation with the sheet laser beam, while ensuring the energy density, the contact probability between the laser and the pulverized coal is further increased, and the combustion effect of the pulverized coal is further improved.

[0053] In some embodiments, the pulverized coal swirl-stabilized combustor 100 based on an adjustable-focus laser igniter according to an embodiment of the present invention includes a bluff body 10. The bluff body 10 is sleeved on the primary air duct 2 and is located between the primary air duct 2 and the first swirler 3 in the inner and outer directions. The bluff body 10 has an installation cavity 1001 and a light passing hole 1002 facing the combustion chamber 104. The emitting end of the laser 601 is arranged in the installation cavity 1001, and the lens assembly 602 is arranged in the light passing hole 1002.

[0054] By adding the bluff body 10 between the first swirler 3 and the primary air duct 2, the secondary air flow can be more evenly guided into the combustion chamber 104, thereby providing a more stable and less interfering air flow environment for the transmission of the laser beam. At the same time, since the emitting end of the laser 601 is arranged in the installation cavity 1001 and the lens assembly 602 is arranged in the light passing hole 1002, the laser beam can work more focused near the flame side continuously, reducing the adverse effect of air flow turbulence on laser transmission and improving the reliability of ignition.

[0055] In some embodiments, the bluff body 10 includes a conical section 1003 and a cylindrical section 1004. The conical section 1003 is arranged on the side of the cylindrical section 1004 away from the combustion chamber 104 in the axial direction of the primary air duct 2. The outer diameter dimension of the conical section 1003 gradually increases in the direction from the front cone section 102 to the rear cone section 103, and the outer wall surface of the cylindrical section 1004 is connected to the first swirler 3. The gradually increasing outer diameter dimension of the conical section 1003 helps to optimize the flow characteristics of the secondary air, reduce the flow resistance, and improve the flow stability. At the same time, it can also enhance the swirl effect of the secondary air to improve the combustion stability and reduce the risk of flameout.

[0056] In some embodiments, the pulverized coal swirl-stabilized combustor 100 based on an adjustable-focus laser igniter according to an embodiment of the present invention includes a deflector 11. The deflector 11 is arranged in the front cone section 102. One end of the deflector 11 is connected to the first swirler 3, and the other end of the deflector 11 is bent from the outside to the inside towards the light passing hole 1002 to deflect a part of the secondary air introduced into the ignition zone by the first swirler 3 to the lens assembly 602.

[0057] The secondary air entering the ignition zone at the outlet of the first cyclone 3 will be diverted and guided to the lens assembly 602 through the deflector 11. On the one hand, it can provide an appropriate cooling air flow for the lens assembly, reducing the component loss under the action of laser high temperature. On the other hand, it also helps to purge dust accumulation, avoiding the deposition of pulverized coal or fly ash on the lens surface, which causes a decrease in transmittance and local overheating. This can not only extend the working life of the lens assembly 602, but also reduce the failures caused by incomplete mirror cleaning.

[0058] In summary, the pulverized coal swirl-stabilized combustor 100 based on the adjustable-focus laser igniter in the embodiment of the present invention realizes the adjustment of the size and shape of the laser beam spot by setting the bluff body 10 and the laser generator assembly 6, and is supplemented by the cooling and combustion control strategies of the cooperation between the tertiary air and the secondary air, significantly improving the ignition efficiency and stability of the pulverized coal combustion process. At the same time, the laser power and mode can be flexibly switched, which can adapt to different coal qualities and load conditions, greatly improving the adaptability and combustion efficiency of the combustor, extending the service life of the furnace and related components, and reducing the operation cost. The pulverized coal swirl-stabilized combustor 100 based on the adjustable-focus laser igniter in the embodiment of the present invention meets the high-efficiency combustion requirements of industrial pulverized coal furnaces, and at the same time takes into account the safety and service life of key parts, having obvious innovation and practical value.

[0059] The present invention also discloses a pulverized coal swirl-stabilized combustion method based on an adjustable-focus laser igniter, including:

[0060] Emitting a sheet-shaped laser beam into the combustion chamber 104, and simultaneously monitoring the combustion state of the flame in the combustion chamber 104 and the wall temperature of the high-temperature zone in the combustion chamber 104.

[0061] When the combustion intensity of the flame in the combustion chamber 104 is lower than the first preset value, increase the emission power and width size of the sheet-shaped laser beam, and expand the laser beam coverage range to enhance the pulverized coal ignition area. If the shape of the flame in the combustion chamber 104 is unstable, switch the power output mode of the sheet-shaped laser beam to pulsed laser to increase the local energy density to form a stable secondary flame.

[0062] When the combustion intensity of the flame in the combustion chamber 104 is higher than the second preset value, if the distance between the flame in the ignition zone and the secondary air inlet exceeds the third preset value, increase the primary air velocity so that the pulverized coal can reach near the bluff body 6, improving the utilization rate of the combustion space inside the front cone section 102. If the flame temperature in the ignition zone is too high and the flame volume is too large, increase the secondary air velocity to move the combustion zone backward by reducing the residence time of the pulverized coal in the ignition zone. Vice versa.

[0063] When the wall temperature of the high-temperature zone in the combustion chamber 104 reaches the pulverized coal melting temperature, introduce tertiary air into the front cone of the combustor and simultaneously reduce the flow rate of the secondary air to prevent wall damage caused by excessive temperature and move the high-temperature zone upstream. Vice versa.

[0064] In summary, the pulverized coal swirl combustion stabilization method based on an adjustable-focus laser igniter according to the embodiments of the present invention realizes the adjustment of the size and shape of the laser beam spot, and is supplemented by a cooling and combustion control strategy that coordinates the tertiary air and the secondary air, significantly improving the ignition efficiency and stability during the pulverized coal combustion process. At the same time, the laser power and mode can be flexibly switched, which can adapt to different coal qualities and load conditions, greatly improving the adaptability of the burner and the combustion efficiency, extending the service life of the furnace and related components, and reducing the operating cost. The pulverized coal swirl combustion stabilization method based on an adjustable-focus laser igniter according to the embodiments of the present invention meets the high-efficiency combustion requirements of industrial pulverized coal furnaces while taking into account the safety and service life of key parts, and has obvious innovation and practical value.

[0065] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0066] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0067] In the present invention, unless otherwise clearly defined and limited, the terms "mounted", "connected", "coupled", "fixed", etc. should be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral body; it may be a mechanical connection, an electrical connection, or a communication with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0068] In the present invention, unless otherwise expressly specified and defined, a first feature being “on” or “under” a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact via an intermediate medium. Further, a first feature being “above”, “over” and “on top of” a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the horizontal height of the first feature is higher than that of the second feature. A first feature being “under”, “beneath” and “underneath” a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the horizontal height of the first feature is less than that of the second feature.

[0069] In the present invention, the terms “one embodiment”, “some embodiments”, “example”, “specific example”, or “some examples” etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0070] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter, characterized in that include: A shell, the shell comprising an air guide section, a front cone section and a rear cone section which are connected in sequence, the front cone section and the rear cone section defining a combustion chamber, wherein an inlet end of the front cone section forms an ignition zone, and a junction area between the front cone section and the rear cone section forms a high temperature zone in the combustion chamber; A primary air duct, a first cyclone and a return cap, wherein the outlet end of the primary air duct extends into the rear cone section through the air guide section, the inlet end of the primary air duct is arranged outside the shell, a secondary air duct is defined between the primary air duct and the air guide section, the first cyclone is arranged in the secondary air duct for introducing secondary air into the ignition zone, and the return cap is arranged in the combustion chamber and located at the outlet end of the primary air duct; A laser generator assembly, at least part of which is disposed in the secondary air duct and is used for emitting a sheet-shaped laser beam into the combustion chamber to ignite the coal powder in the combustion chamber.

2. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 1, characterized in that, The laser generator assembly comprises a laser and a lens assembly. The laser beam emitted by the laser is shaped into a sheet-shaped laser beam by the lens assembly, and the width of the sheet-shaped laser beam is adjustable.

3. The pulverized coal swirling-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 2, wherein The power output mode of the laser can be switched between pulse laser and continuous laser.

4. The pulverized coal swirl-stabilized combustion burner based on the adjustable-focus laser igniter according to claim 3, characterized in that The front cone section is provided with a tertiary air inlet located upstream of the high temperature zone, and the tertiary air inlet is used to introduce tertiary air into the combustion chamber.

5. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 4, characterized in that, The shell is provided with a video TV and a temperature sensor. The video TV is used to monitor the combustion state of the flame in the combustion chamber, and the temperature sensor is used to monitor the shell wall temperature in the high temperature zone.

6. The pulverized coal swirling-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 4, characterized in that An annular channel is defined between the inner side wall of the return cap and the outer side wall of the primary air duct, and a second cyclone is disposed in the annular channel.

7. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 3, characterized in that, It includes a bluff body, which is sleeved on the primary air duct and located between the primary air duct and the first swirler in the inward and outward directions. The bluff body has a mounting cavity and a light-through hole arranged toward the combustion chamber. The emitting end of the laser is arranged in the mounting cavity, and the lens assembly is arranged in the light-through hole.

8. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 7, characterized in that, The blunt body includes a conical section and a cylindrical section, the conical section is arranged on the side of the cylindrical section away from the combustion chamber in the axial direction of the primary air duct, the outer diameter of the conical section gradually increases from the front conical section to the rear conical section, and the outer wall surface of the cylindrical section is connected to the first swirler.

9. The pulverized coal swirl-stabilized combustion burner based on an adjustable-focus laser igniter according to claim 7, characterized in that, It includes a guide plate, which is arranged in the front cone section, one end of the guide plate is connected to the first swirler, and the other end of the guide plate is bent from the outside to the inside toward the light hole to guide part of the secondary air introduced into the ignition zone by the first swirler to the lens assembly.

10. A method for swirl stabilization of coal powder combustion based on a focusable laser igniter, comprising: A sheet laser beam is emitted into the combustion chamber, and the combustion state of the flame in the combustion chamber and the wall temperature of the high-temperature area in the combustion chamber are monitored at the same time; When the combustion intensity of the flame in the combustion chamber is lower than the first preset value, the emission power and width of the sheet laser beam are increased; if the shape of the flame in the combustion chamber is unstable, the power output mode of the sheet laser beam is switched to a pulsed laser; When the combustion intensity of the flame in the combustion chamber is higher than the second preset value, if the distance between the flame in the ignition zone and the secondary air inlet exceeds the third preset value, the primary air velocity is increased; if the flame temperature in the ignition zone is on the high side and the flame volume is large, the secondary air velocity is increased. When the wall temperature of the high-temperature zone in the combustion chamber reaches the pulverized coal melting temperature, tertiary air is introduced into the front cone of the burner, and at the same time, the flow rate of the secondary air is reduced.

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