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

Abstract

The invention discloses a pulverized coal stable combustion burner based on a focus-adjustable laser igniter and a stable combustion method.The pulverized coal stable combustion burner comprises a shell, a primary air pipe, a reflection bowl, a swirler and a laser generator assembly, and the outlet end of the primary air pipe extends into a combustion chamber and is bent in the direction facing an ignition area; an outlet of the primary air pipe is gradually shrunk in the flowing direction of pulverized coal, the reflection bowl is arranged at the outlet end of the primary air pipe, the bowl opening of the reflection bowl faces the ignition area, and the bowl bottom of the reflection bowl is provided with a through hole used for passing of pulverized coal flow sprayed out of the outlet of the primary air pipe. The laser generator assembly is used for emitting laser beams towards the reflection bowl so as to ignite pulverized coal in the combustion chamber. Compared with a traditional ignition technology, the method has the advantages that the rapid and stable ignition efficiency and effect are achieved, and the adaptability to inferior coal is remarkably expanded. In addition, damage of laser to the wall face of the boiler is avoided, device consumables used for absorbing redundant laser can be saved, and 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 stable combustion burner and a stable combustion method based on an adjustable-focus laser igniter. Background Art

[0002] In existing double-cone reverse injection burners, pulverized coal flows through a primary air duct and a reflux cap and is reverse injected into the ignition zone for ignition. Relying on the entrainment effect of swirling secondary air, the pulverized coal flows 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 low-volatile pulverized coal, more heat is required in the ignition zone to achieve self-sustained combustion, 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 likely to cause coking problems; the other is to introduce additional heat sources, such as fuel oil guns, but the long-term use of diesel for combustion is costly 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 adjacent pulverized coal.

[0007] 2. The energy of the laser beam is too concentrated. When the pulverized coal concentration in 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 lead to waste of heat, and on the other hand, the heat absorbed by the wall surface will cause the problem of wall surface burning damage.

[0008] In view of the above problems, the present invention provides a pulverized coal stable combustion burner and a stable combustion 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 operating costs.

[0009] The present invention aims to solve at least one of the technical problems in the related art to some extent.

[0010] To this end, an embodiment of the present invention provides a pulverized coal combustion stabilization burner and a combustion stabilization method based on a focusable laser igniter.

[0011] The coal powder stable combustion burner based on the adjustable focus laser igniter of the embodiment of the present invention comprises a shell, a primary air duct, a reflective bowl, a swirler and a laser generator assembly, wherein the shell comprises 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 define a combustion chamber, wherein the inlet end of the front cone section forms an ignition zone, and the intersection area of ​​the front cone section and the rear cone section forms a high temperature zone in the combustion chamber; the outlet end of the primary air duct extends into the combustion chamber and is bent in the direction toward the ignition zone, the outlet of the primary air duct gradually shrinks in the flow direction of the coal powder, the reflective bowl is arranged at the outlet end of the primary air duct and the bowl mouth is arranged toward the ignition zone, the bottom of the reflective bowl has a through hole, and the through hole is used for the coal powder flow ejected from the outlet of the primary air duct to pass through; the swirler is arranged in the air guide section for introducing secondary air into the ignition zone; at least part of the laser generator assembly is arranged in the air guide section for emitting a laser beam toward the reflective bowl to ignite the coal powder in the combustion chamber.

[0012] In some embodiments, the center of the laser beam, the central axis of the reflection bowl and the central axis of the primary air duct outlet coincide with each other.

[0013] In some embodiments, the inner surface of the reflective bowl is coated with a reflective coating.

[0014] In some embodiments, the laser generator assembly includes a laser and a lens assembly. The laser beam emitted by the laser is diverged through the lens assembly. The power output mode of the laser can be switched between pulsed laser and continuous laser. The focal length of the lens assembly can be adjusted to adjust the divergence angle of the laser beam.

[0015] In some embodiments, a tertiary air inlet is provided 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.

[0016] In some embodiments, a video television and a temperature sensor are provided on the shell, the video television 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.

[0017] In some embodiments, the pulverized coal stable combustion burner based on an adjustable focus laser igniter according to the embodiments 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 swirler in the inner and outer directions, the bluff body has an installation cavity and a light passing hole facing the combustion chamber, the emission 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 dimension of the conical section gradually increases along the direction from the front conical section to the rear conical section, and the outer wall surface of the cylindrical section is connected to the swirler.

[0019] In some embodiments, the pulverized coal stable combustion burner based on an adjustable focus laser igniter according to the embodiments of the present invention includes a deflector plate, the deflector plate is arranged in the front conical section, one end of the deflector plate is connected to the swirler, and the other end of the deflector plate is bent from the outside to the inside towards the direction of the light passing hole to divert part of the secondary air introduced by the swirler into the ignition area to the lens assembly.

[0020] In some embodiments, the method for stabilizing the combustion of pulverized coal based on an adjustable focus laser igniter according to the embodiments of the present invention is applied to the pulverized coal stable combustion burner described in any of the above embodiments, and includes:

[0021] Emitting a laser beam into the reflecting bowl, and simultaneously monitoring the combustion state of the flame in the combustion chamber and the wall temperature of the high-temperature area in the combustion chamber;

[0022] When the combustion intensity of the flame in the combustion chamber is lower than a first preset value, increase the emission power of the laser beam to the divergence angle. If the shape of the flame in the combustion chamber is unstable, switch the power output mode of the laser beam to pulsed laser;

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

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

[0025] Due to the high directivity of the laser beam, the heat placement position can be controlled more accurately. Compared with the traditional ignition technology, the present invention can use the laser generator assembly for efficient ignition, achieve the efficiency and effect of rapid and stable ignition, and significantly expand the adaptability to inferior coal. In addition, at the same time, the tapered outlet of the primary air duct and the setting of the reflection bowl enable the coal powder flow to efficiently absorb the energy of the laser beam for combustion. Compared with the traditional laser, the energy of the laser beam of the present invention is basically absorbed by the coal powder for combustion, thus avoiding the damage of the laser to the boiler wall, saving the consumables of the device used to absorb the excess laser, and reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 4 It is a schematic diagram of the flow of pulverized coal in a pulverized coal stable combustion burner according to the second embodiment of the present invention.

[0030] 100. Pulverized coal stable 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. Reflection bowl; 4. Swirl; 6. Laser generator assembly; 601. Laser; 602. Lens assembly; 7. Video TV; 8. Temperature sensor; 9. Blunt body; 901. Mounting cavity; 902. Light hole; 903. Conical section; 904. Cylindrical section; 10. Guide plate. DETAILED DESCRIPTION

[0031] 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.

[0032] like Figures 1 to 3 As shown, the pulverized coal stable 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 reflector bowl 3, a swirler 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.

[0033] The outlet end of the primary air duct 2 extends into the combustion chamber 104 and is bent in the direction towards the ignition zone. The outlet of the primary air duct 2 tapers along the flow direction. The reflecting bowl 3 is arranged at the outlet end of the primary air duct 2 with the bowl mouth facing the ignition zone. The bottom of the reflecting bowl 3 has a through hole for the pulverized coal flow ejected from the outlet of the primary air duct 2 to pass through. The swirler 4 is arranged in the air guiding section 101 for introducing secondary air into the ignition zone. At least part of the laser generator assembly 6 is arranged in the air guiding section 101 for emitting a laser beam towards the reflecting bowl 3 to ignite the pulverized coal in the combustion chamber 104.

[0034] When the pulverized coal stable combustion burner 100 based on the adjustable focus laser igniter of the embodiment of the present invention is in use, the pulverized coal is sent into the combustion chamber 104 through the primary air duct 2, and the pulverized coal flow ejects the pulverized coal flow towards the ignition zone after passing through the bent section of the primary air duct 2. Since the outlet of the primary air duct 2 tapers along the flow direction of the pulverized coal flow, after the pulverized coal flows out through the outlet of the primary air duct 2, under the action of inertia force, it concentrates towards the central axis direction of the outlet of the primary air duct 2, forming a local high concentration point of pulverized coal (as shown in Figure 2 and Figure 3 .

[0035] When the laser generator assembly 6 emits a laser beam towards the reflecting bowl 3, it can quickly ignite the high-concentration pulverized coal. At the same time, the laser beam irradiated on the reflecting bowl 3 can be reflected by the inner surface of the reflecting bowl 3 and then irradiate the pulverized coal flow a second time, so that the pulverized coal flow can fully absorb the energy of the laser beam and burn quickly. 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 beneficial to the stable progress of combustion. The backflow generated in the combustion chamber 104 brings the heat of the high-temperature zone back to the ignition zone, and the secondary air is introduced into the ignition zone through the swirler 4, increasing the residence time and mixing effect of the pulverized coal, and contributing to the further ignition and combustion of the pulverized coal in the ignition zone.

[0036] Due to the high directivity of the laser beam, the position of heat release can be controlled more precisely. Compared with the traditional ignition technology, the present invention can use the laser generator assembly 6 for efficient ignition, achieving the efficiency and effect of rapid and stable ignition, and significantly expanding the adaptability to inferior coal. In addition, at the same time, the tapered outlet of the primary air duct 2 and the setting of the reflecting bowl 3 enable the pulverized coal flow to efficiently absorb the energy of the laser beam for combustion. Compared with traditional lasers, the energy of the laser beam of the present invention is basically absorbed by the pulverized coal for combustion, so 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 center of the laser beam, the central axis of the reflecting bowl 3 and the central axis of the outlet of the primary air duct 2 coincide.

[0038] Such asFigure 2 and Figure 3 As shown, when the center of the laser beam coincides with the central axis of the reflecting bowl 3, the focusing or reflecting effect of the reflecting bowl 3 can be maximally utilized, thereby improving the utilization efficiency of the laser. Through precise alignment, the energy loss of the laser beam during transmission can be reduced, because incorrect alignment may cause some energy of the laser beam not to be effectively utilized. When the pulverized coal flow is precisely located at the center of the laser beam, the pulverized coal particles can maximally absorb the energy of the laser beam, which can improve the heating and combustion efficiency of the pulverized coal and is particularly important for the laser-induced pulverized coal combustion or gasification process. The coincidence of the central axis of the reflecting bowl 3 and the central axis of the air duct outlet helps the uniform distribution of the pulverized coal flow within the laser irradiation area, thereby enhancing the reaction efficiency between the pulverized coal and the laser.

[0039] In some embodiments, the inner surface of the reflecting bowl 3 is coated with a reflective coating.

[0040] For example, the reflective coating is a wear-resistant coating with high reflectivity and low pulverized coal adhesion. The reflective coating is usually made of a material with high reflectivity, which can effectively reflect the laser beam, reduce energy loss, and thus improve the energy utilization efficiency of the entire system. The reflective coating can focus the laser beam to a smaller focal point, which helps to increase the energy density of the laser beam in the pulverized coal flow, enabling the pulverized coal to absorb laser energy more quickly and fully. The focused laser beam can ignite the pulverized coal faster, especially in situations where rapid ignition is required, such as during the startup process of a coal-fired boiler.

[0041] 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 diverged by the lens assembly 602. The power output mode of the laser 601 can be switched between two types: pulsed laser and continuous laser. The focal length of the lens assembly 602 is adjustable to adjust the divergence angle of the laser beam.

[0042] Specifically, during use, the lens assembly 602 is arranged outside the laser emission port, so that the laser beam can be diverged into, for example, a conical shape (the light spot is circular) after passing through the lens assembly 602. By adjusting the focal length of the lens assembly 602, the divergence angle of the laser can be adjusted to change the diameter size of the laser beam. For example, when the divergence angle of the laser beam reaches the maximum, the diverged laser beam can cover the entire reflecting bowl 3 (as Figure 3 shown). When the divergence angle of the laser beam reaches the minimum, the laser beam only passes through the high-concentration point position of the pulverized coal flow (as Figure 2 shown). By adjusting the divergence angle of the laser beam, different combustion conditions can be adapted, making the burner of the present invention highly applicable.

[0043] Meanwhile, in the case where 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 quick ignition of the pulverized coal.

[0044] 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.

[0045] The ability to freely switch between pulsed laser and continuous laser enables the burner to adjust according to the type of pulverized coal and 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 methods can be adopted to achieve the best ignition effect. In the pulsed laser mode, high-power pulses 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.

[0046] Optionally, the maximum input power of the laser generator assembly 6 should reach at least 5% of the burner power.

[0047] In some embodiments, a tertiary air inlet 105 is provided on the front cone section 102 upstream of the high-temperature zone, and the tertiary air inlet 105 is used to introduce tertiary air into the combustion chamber 104.

[0048] As Figures 1 to 3 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 (the melting temperature of pulverized coal) and avoid wall damage caused by excessive temperature, by increasing the proportion of tertiary air flow, the high-temperature zone can be moved upstream, which can quickly reduce the wall temperature near the high-temperature zone, thus avoiding damage caused by local overheating. When the wall temperature of the high-temperature zone is too low, the proportion of tertiary air is appropriately reduced while the secondary air is increased to fully ensure the high-temperature combustion process and improve the heating effect of the recirculated heat on the pulverized coal ignition zone, thereby ensuring the continuous and stable combustion reaction. This adjustment method takes into account the ignition safety while also extending the service life of the housing 1 and related components.

[0049] In some embodiments, a visual TV 7 and a temperature sensor 8 are provided on the housing 1. The visual 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 housing 1 in the high-temperature zone.

[0050] The visual 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 combustion stability and efficiency. By observing the changes in the flame, abnormal conditions during the combustion process, such as unstable flame, flameout or incomplete combustion, can be detected in time, so as to take measures for adjustment in time. Temperature sensors such as the temperature sensor 8 can monitor the wall temperature of the housing 1 in the high-temperature area in the combustion chamber 104 in real time, ensuring that the temperature in the combustion chamber 104 is controlled within a safe range. By monitoring the wall temperature, damage to the housing 1 material caused by excessive temperature can be prevented, thus ensuring the safety of the equipment.

[0051] Through the real-time data of the visual TV 7 and the temperature sensor 8, the operator can understand the combustion state more quickly and accurately, improving the monitoring efficiency. Real-time monitoring can detect and handle potential risks during the combustion process in time, reducing the probability of accidents and ensuring the safety of the equipment and the operator. By analyzing the flame and temperature data, combustion parameters such as air volume, pulverized coal flow rate and laser power can be optimized to achieve the best combustion effect.

[0052] In some embodiments, the pulverized coal stable combustion burner 100 based on an adjustable-focus laser igniter of the embodiment of the present invention includes a bluff body 9. The bluff body 9 is sleeved on the primary air duct 2 and is located between the primary air duct 2 and the swirler 4 in the inner and outer directions. The bluff body 9 has an installation cavity 901 and a light passing hole 902 facing the combustion chamber 104. The emitting end of the laser 601 is arranged in the installation cavity 901, and the lens assembly 602 is arranged in the light passing hole 902.

[0053] By adding the bluff body 9 between the swirler 4 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 901 and the lens assembly 602 is arranged in the light passing hole 902, the laser beam can work continuously near the flame side more focused, reducing the adverse impact of air flow turbulence on laser transmission and improving the reliability of ignition.

[0054] In some embodiments, the bluff body 9 includes a conical section 903 and a cylindrical section 904. The conical section 903 is arranged on the side of the cylindrical section 904 away from the combustion chamber 104 in the axial direction of the primary air duct 2. The outer diameter dimension of the conical section 903 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 904 is connected to the swirler 4.

[0055] The outer diameter dimension of the conical section 903 gradually increases in the direction from the front conical section 102 towards the rear conical section 103. The outer wall surface of the cylindrical section 904 is connected to the cyclone 4. The gradually increasing outer diameter dimension of the conical section 903 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 swirling effect of the secondary air to improve the combustion stability and reduce the risk of flameout.

[0056] In some embodiments, the pulverized coal stable combustion burner 100 based on the adjustable focus laser igniter according to the embodiment of the present invention includes a deflector 10. The deflector 10 is arranged in the front conical section 102. One end of the deflector 10 is connected to the cyclone 4, and the other end of the deflector 10 bends from the outside to the inside towards the direction of the light passing hole 902 to divert a part of the secondary air introduced by the cyclone 4 into the ignition zone to the lens assembly 602.

[0057] The secondary air entering the ignition zone at the outlet of the cyclone 4 will be diverted and guided to the lens assembly 602 through the deflector 10. On the one hand, it can provide a moderate cooling air flow for the lens assembly 602 to reduce the component loss under the action of laser high temperature. On the other hand, it also helps to purge dust accumulation and avoid the deposition of pulverized coal or fly ash on the lens surface, resulting in 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 surface cleaning.

[0058] In summary, the pulverized coal stable combustion burner 100 based on the 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 the bluff body 9 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 burner, extending the service life of the furnace and related components, and reducing the operation cost. The pulverized coal stable combustion burner 100 based on the 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.

[0059] In some embodiments, the present invention also discloses a pulverized coal stable combustion method based on an adjustable focus laser igniter. This method is applied to the pulverized coal stable combustion burner 100 in any of the above embodiments and includes:

[0060] Emit a laser beam into the reflection bowl 3, and at the same time monitor 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 of the laser beam and its divergence angle to expand the spot coverage range and 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 laser beam to pulsed laser to increase the local energy density and 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 swirler 4 exceeds the third preset value, increase the primary air velocity; if the temperature of the flame in the ignition zone is relatively high and the flame volume is relatively large, increase the secondary air velocity.

[0063] When the wall temperature of the high-temperature zone of the combustion chamber 104 reaches the pulverized coal melting temperature, introduce tertiary air into the front cone section 102 of the burner and reduce the flow rate of the secondary air at the same time.

[0064] By arranging a lens system with zoom ability outside the laser emission port, the laser beam can not only be directly emitted as it is, but also diverge to form a conical spot when needed and cover the entire reflector bowl 3 area.

[0065] In summary, the pulverized coal stable combustion method based on the adjustable-focus laser igniter in the embodiments of the present invention realizes the adjustment of the size and shape of the laser beam spot, and is supplemented by the cooling and combustion control strategies of the cooperation of 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, extending the service life of the furnace and related components, and reducing the operation cost. The pulverized coal swirl stable combustion method based on the adjustable-focus laser igniter in the embodiments of the present invention meets the high-efficiency combustion requirements of industrial pulverized coal furnaces, takes into account the safety and service life of key parts, and has obvious innovation and practical value.

[0066] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by 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. is the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and is 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 therefore should not be construed as a limitation to the present invention.

[0067] In addition, the terms "first" and "second" are for descriptive purposes only and should not 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.

[0068] In the present invention, unless otherwise clearly defined and limited, terms such as "mounted", "connected", "connected to", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or communicable with each other; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the communication inside 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.

[0069] In the present invention, unless otherwise clearly defined and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below" and "beneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0070] In the present invention, terms such as "an 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 descriptions 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 a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0071] 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 can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A pulverized coal stable 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, the outlet end of which extends into the combustion chamber and is bent in a direction toward the ignition zone, and the outlet of the primary air duct gradually shrinks in the flow direction of the coal powder. A reflective bowl, the reflective bowl is arranged at the outlet end of the primary air duct and the bowl mouth is arranged toward the ignition zone, the bottom of the reflective bowl has a through hole, and the through hole is used for the coal powder flow sprayed from the outlet of the primary air duct to pass through; a swirler, the swirler being arranged in the air guide section and being used for introducing secondary air into the ignition zone; A laser generator assembly, at least a portion of which is disposed in the air guide section, and is used for emitting a laser beam toward the reflective bowl to ignite the coal powder in the combustion chamber.

2. The pulverized coal stable combustion burner based on an adjustable focus laser igniter according to claim 1, wherein The center of the laser beam, the central axis of the reflection bowl and the central axis of the primary air duct outlet coincide with each other.

3. The pulverized coal stable combustion burner based on an adjustable focus laser igniter according to claim 2, wherein The inner surface of the reflective bowl is coated with a reflective coating.

4. The pulverized coal stable combustion burner based on an adjustable focus laser igniter according to claim 3, wherein The laser generator assembly includes a laser and a lens assembly. The laser beam emitted by the laser is diverged through the lens assembly. The power output mode of the laser can be switched between pulsed laser and continuous laser. The focal length of the lens assembly can be adjusted to adjust the divergence angle of the laser beam.

5. The pulverized coal stable combustion burner based on an adjustable focus laser igniter according to claim 4, wherein, 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.

6. The pulverized coal stable 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.

7. The pulverized coal stable combustion burner based on an adjustable-focus laser igniter according to claim 4, 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 cyclone 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 stable 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 swirler.

9. The pulverized coal stable 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 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 swirler to the lens assembly.

10. A method for stabilizing the combustion of pulverized coal based on a focus-adjustable laser igniter, the method being applied to the pulverized coal stabilizing combustion burner based on a focus-adjustable laser igniter as claimed in any one of claims 1 to 9, comprising: The laser beam is emitted into the reflective bowl, 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 simultaneously; When the combustion intensity of the flame in the combustion chamber is lower than the first preset value, increase the emission power of the laser beam and its divergence angle. If the shape of the flame in the combustion chamber is unstable, switch the power output mode of the laser beam to 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 swirler exceeds the third preset value, increase the primary air velocity. If the temperature of the flame in the ignition zone is on the high side and the flame volume is large, increase the secondary air velocity. When the wall temperature of the high-temperature zone in the combustion chamber reaches the pulverized coal melting temperature, introduce the tertiary air into the front cone section of the burner, and at the same time reduce the flow rate of the secondary air.

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