Pulverized coal combustion device for coal-fired power units

Abstract

The present invention provides a pulverized coal combustion device for a coal-fired power plant. The pulverized coal combustion device includes a cavity and a cleaning assembly. The cavity includes an accelerator cylinder. The accelerator cylinder has a first end and a second end that are arranged opposite to each other. The diameter of the first end is smaller than the diameter of the second end, and the first end is provided with a jet nozzle. The cleaning assembly includes a cleaning air duct. The cleaning air duct has an air outlet. The air outlet is arranged at the second end. The opening of the air outlet is arranged toward the inner wall of the accelerator cylinder so that the airflow in the cleaning air duct is directed toward the inner wall of the accelerator cylinder. The pulverized coal combustion device for a coal-fired power plant disclosed in the present invention can effectively remove foreign matter such as pulverized coal adhering to the inner wall of the cavity and accelerate the pulverized coal mixed fluid, thereby not only improving the stability and efficiency of combustion, but also extending the service life of the pulverized coal combustion device for the coal-fired power plant.

Description

Technical Field

[0001] The present invention relates to the technical field of pulverized coal combustion, and in particular to a pulverized coal combustion device for a coal-fired power plant. Background Art

[0002] Pulverized coal combustion equipment is a key component of thermal power plants and other industrial furnaces, and its operational performance directly impacts the energy efficiency and safety of the entire system. However, during operation, pulverized coal combustion equipment often suffers from insufficient flame jet rigidity, resulting in large amounts of unburned carbon particles and ash adhering to the inner walls of the combustion chamber, forming coke. This not only reduces the heat transfer efficiency of the combustion device and increases energy consumption, but can also cause localized overheating of the combustion chamber walls, leading to burnout, shortening the equipment's service life, and even posing safety hazards. Summary of the Invention

[0003] The present invention is based on the inventor's discovery and understanding of the following facts and problems:

[0004] The primary function of pulverized coal combustion equipment is to efficiently convert pulverized coal into heat energy. Its operating conditions directly impact energy efficiency and the overall safety of the system. However, in actual use, flame jet rigidity becomes a key factor limiting the performance of pulverized coal combustion equipment.

[0005] Flame jet rigidity refers to the ability of a flame to maintain a stable shape and direction within the combustion chamber of a combustion device. When the flame jet rigidity within the combustion device is insufficient, the flame cannot effectively resist interference from external airflow. This prevents the pulverized coal from fully mixing with oxygen and burning completely. Consequently, some of the pulverized coal fails to burn completely, leaving a large amount of unburned carbon particles and ash residue. These residues, due to high temperatures, become sticky and tend to deposit and accumulate on the inner walls of the combustion chamber, forming a "coking" phenomenon.

[0006] However, the coking of residues in the combustion chamber not only hinders the effective conduction of heat, reduces the thermal efficiency of the combustion device, and increases energy loss, but also causes the temperature of the combustion device wall to rise abnormally because the heat in the coked area cannot be dissipated in time, accelerating the aging of the metal material and the degradation of its physical properties, which may cause the combustion device to malfunction, bring unforeseen safety hazards to production, and shorten the life of the combustion equipment.

[0007] To this end, an embodiment of the present invention provides a pulverized coal combustion device for a coal-fired power plant. The pulverized coal combustion device comprises a chamber and a cleaning assembly. The chamber includes an accelerator cylinder having a first end and a second end disposed opposite each other, the first end having a smaller diameter than the second end, and the first end being provided with a jet nozzle. The cleaning assembly includes a cleaning air duct having an air outlet disposed at the second end. The outlet opening is disposed toward the inner wall of the accelerator cylinder, so that airflow within the cleaning air duct is directed toward the inner wall of the accelerator cylinder.

[0008] In summary, the pulverized coal combustion device for a coal-fired power plant provided by the present invention, through the conical design of the accelerator cylinder, gradually accelerates the pulverized coal mixture and ejects it through the nozzle at a higher velocity. Furthermore, the airflow flushing action of the cleaning assembly effectively removes foreign matter, such as pulverized coal, adhering to the inner wall of the cavity, while simultaneously accelerating the pulverized coal mixture again. This not only improves combustion stability and efficiency, but also extends the service life of the pulverized coal combustion device for coal-fired power plants, bringing a brand-new solution to the field of industrial combustion.

[0009] In some embodiments, the cleaning air duct has a reduced diameter section, which is connected to the second end of the acceleration cylinder; the cavity also includes a return cylinder, which is connected to the acceleration cylinder, and the cleaning air duct is sleeved on the outside of the return cylinder, and a rectifying channel is provided between the reduced diameter section and the return cylinder, and multiple openings are provided between the return cylinder and the acceleration cylinder to form the air outlet.

[0010] In some embodiments, a pulverized coal pipe assembly is also included, and the pulverized coal pipe assembly includes a first return channel and a second return channel, the first return channel has a first return port, the second return channel has a second return port, the first return port and the second return port are connected, the opening of the first return port and the opening of the second return port are both set toward the inner wall of the return cylinder, and the straight line where the opening direction of the first return port is located and the straight line where the opening direction of the second return port is located intersect, so as to spray the pulverized coal fluid into the cavity.

[0011] In some embodiments, the pulverized coal pipe assembly also includes a reflux cap and a guide plate, the first reflux channel and the second reflux channel are coaxially arranged in the reflux cap, the first reflux channel is located on the outside of the second reflux channel, and the guide plate is arranged at the connection point between the first reflux port and the second reflux port, and the guide plate is provided with an inclined surface on the side facing the second reflux channel.

[0012] In some embodiments, the pulverized coal pipe assembly further includes a supply pipe, in which a first channel and a second channel are provided. The first channel and the second channel are independent of each other. The first channel is connected to the first return channel, and the second channel is connected to the second return channel. The first channel and the second channel are used to transport different types of pulverized coal fluids into the cavity.

[0013] In some embodiments, a secondary air component is also included, and the secondary air component includes a plurality of independent air ducts, and the air ducts have air supply ports, and the air supply ports are arranged at one end of the return tube, and the first return port and the second return port are arranged at the other end of the return tube, and the air supply ports are staggered relative to the first return port and the second return port in the radial direction of the cavity.

[0014] In some embodiments, the secondary air component further includes a plurality of regulating valves, and the plurality of regulating valves are disposed on the air duct in a one-to-one correspondence, and the regulating valves are used to adjust the flow rate of the air flow in the air duct.

[0015] In some embodiments, the secondary air assembly further includes a plurality of rotors, which are disposed one-to-one at the air outlet of the air duct, and the rotors are used to guide the airflow transported by the air duct to form a rotating airflow in the cavity.

[0016] In some embodiments, the air duct and the pulverized coal pipe assembly are coaxially arranged, the air duct is arranged outside the pulverized coal pipe assembly, an annular blunt body is provided between the air duct and the pulverized coal pipe assembly, and the annular blunt body is located at the first end of the reflux tube.

[0017] In some embodiments, the cleaning air duct is provided with a wear-resistant coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic front view of a pulverized coal combustion device for a coal-fired power plant provided by an embodiment of the present invention.

[0019] Figure 2 It is a side view schematic diagram of a pulverized coal combustion device of a coal-fired power plant provided by an embodiment of the present invention.

[0020] Figure 3 yes Figure 2 The sectional view of the pulverized coal combustion device of the coal-fired power plant along AA is shown.

[0021] Figure 4 It is a structural schematic diagram of the pulverized coal combustion device of a coal-fired power plant provided by an embodiment of the present invention at the reflux cap.

[0022] Figure 5 It is a flow diagram of the pulverized coal fluid at the reflux cap of the pulverized coal combustion device of the coal-fired power unit provided by an embodiment of the present invention.

[0023] Figure 6 The present invention provides a schematic diagram of the fluid flow in the pulverized coal pipe assembly, the cleaning assembly and the secondary air assembly in the pulverized coal combustion device of the coal-fired power unit.

[0024] Reference numerals: 100, pulverized coal combustion device of coal-fired power unit;

[0025] 10. Cavity; 11. Acceleration tube; 111. First end; 112. Second end; 113. Injection port; 114. High-temperature acceleration zone; 12. Recirculation tube; 121. Third end; 122. Fourth end; 123. High-temperature recirculation zone; 13. Reinforcement layer;

[0026] 30. Cleaning assembly; 31. Cleaning air duct; 311. Air outlet; 312. Reduced diameter section; 313. Rectification channel; 314. Straight pipe section; 315. Wear-resistant coating;

[0027] 50. Pulverized coal pipe assembly; 51. Powder feeding port; 511. First return port; 512. Second return port; 52. Return cap; 521. First return channel; 522. Second return channel; 523. Guide plate; 53. Supply pipe; 531. First channel; 532. Second channel; 533. Inner pipe; 534. Outer pipe; 535. Side branch pipe;

[0028] 70. Secondary air assembly; 71. Air duct; 711. Air outlet; 721. Inner tube; 722. Middle tube; 723. Outer tube; 724. Air supply main; 725. Axial tube; 726. Radial tube; 73. Control valve; 74. Rotary vane; 75. Annular blunt body; 76. End plate. DETAILED DESCRIPTION

[0029] The 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.

[0030] like Figures 1 to 6As shown, an embodiment of the present invention provides a pulverized coal combustion device 100 for a coal-fired power plant. The pulverized coal combustion device 100 includes a cavity 10 and a cleaning assembly 30. The cavity 10 includes an accelerator cylinder 11. The accelerator cylinder 11 has a first end 111 and a second end 112 that are arranged opposite to each other. The diameter of the first end 111 is smaller than the diameter of the second end 112. The first end 111 is provided with a jet nozzle 113. The cleaning assembly 30 includes a cleaning air duct 31. The cleaning air duct 31 has an air outlet 311. The air outlet 311 is provided at the second end 112 of the accelerator cylinder 11. The opening of the air outlet 311 is provided toward the inner wall of the accelerator cylinder 11 so that the air flow in the cleaning air duct 31 is directed toward the inner wall of the accelerator cylinder 11. Thus, the gas in the cleaning air duct 31 can clean the inner wall of the cavity 10 and avoid coking.

[0031] Specifically, the cavity 10 is the main structure of the pulverized coal combustion device 100 of the coal-fired power plant. The diameter of the second end 112 of the accelerator cylinder 11 is larger than the diameter of the first end 111, forming a cone-like structure. This allows the mixture of pulverized coal and gas to be gradually compressed and accelerated when passing through the accelerator cylinder 11, and then ejected at a higher speed at the injection port 113, providing sufficient kinetic energy for the subsequent combustion process. The cleaning component 30 sprays the airflow toward the inner wall of the accelerator cylinder 11 through the air outlet 311 facing the inner wall of the accelerator cylinder 11, so that this airflow impacts the inner wall of the accelerator cylinder 11, effectively removing foreign matter such as pulverized coal particles adhering to the inner wall of the accelerator cylinder 11. This not only avoids the impact of pulverized coal adhesion on the performance of the accelerator cylinder 11, but also further accelerates the mixed fluid through the flushing effect of the airflow, further improving the flow rate of the mixed fluid at the injection port 113.

[0032] In summary, the pulverized coal combustion device 100 for a coal-fired power plant provided by the present embodiment of the present invention gradually accelerates the pulverized coal mixed fluid through the conical design of the accelerator cylinder 11, and ejects it at a higher velocity through the injection port 113. Furthermore, the airflow flushing action of the cleaning assembly 30 effectively removes foreign matter, such as pulverized coal, adhering to the inner wall of the cavity 10, while simultaneously accelerating the pulverized coal mixed fluid again. This not only improves combustion stability and efficiency, but also extends the service life of the pulverized coal combustion device 100 for coal-fired power plants, bringing a brand-new solution to the field of industrial combustion.

[0033] like Figure 3 As shown, in some embodiments, the cleaning air duct 31 has a reduced diameter section 312, which is connected to the second end 112 of the acceleration cylinder 11; the cavity 10 also includes a return cylinder 12, which is connected to the acceleration cylinder 11, and the cleaning air duct 31 is sleeved on the outside of the return cylinder 12, and a rectifying channel 313 is provided between the reduced diameter section 312 and the return cylinder 12, and a plurality of openings are provided between the return cylinder 12 and the acceleration cylinder 11 to form an air outlet 311 for the air flow in the cleaning air duct 31 to flow into the cavity 10.

[0034] Specifically, the purge air duct 31 is sleeved onto the outside of the return tube 12. Multiple openings are provided at the connection between the return tube 12 and the acceleration tube 11 to form air outlets 311. This allows gas to flow through the gap between the purge air duct 31 and the return tube 12 and then be delivered into the cavity 10 through the air outlets 311. Simultaneously, when the pulverized coal mixed fluid enters the acceleration tube 11 from the return tube 12, the airflow within the purge air duct 31 also contacts the mixed fluid through the air outlets 311, forming an air film between the mixed fluid and the inner wall of the acceleration tube 11, thereby isolating the inner wall of the acceleration tube 11 and reducing the possibility of pulverized coal adhering to the inner wall of the acceleration tube 11. In this embodiment, the cross-section of the reduced diameter section 312 is configured to be L-shaped.

[0035] Furthermore, the purge air duct 31 is provided with a reduced diameter section 312 near the second end 112 of the accelerator cylinder 11. This reduces the gap between the reduced diameter section 312 and the return cylinder 12, thereby reducing the flow cross-section of the rectifying channel 313. This guides the airflow within the purge air duct 31 so that it flows smoothly and orderly toward the inner wall of the accelerator cylinder 11, avoiding turbulence and eddies that may occur during the flow. Simultaneously, the reduced gap between the reduced diameter section 312 and the return cylinder 12 increases the resistance to the flow of the airflow, making the airflow ejected through the air outlet 311 more uniform. It also increases the jet velocity of the airflow, allowing it to maintain a high momentum and flow forward along the inner wall of the accelerator cylinder 11.

[0036] Furthermore, the cleaning air duct 31, the return cylinder 12 and the acceleration cylinder 11 are all configured to be cylindrical, and multiple openings are evenly arranged along the wall of the acceleration cylinder 11, so that the airflow ejected from the cleaning air duct 31 through the air outlet 311 is more evenly distributed on the wall of the acceleration cylinder 11, avoiding the problem of local excessive flushing or insufficient cleaning caused by uneven airflow distribution, and ensuring that every area of ​​the inner wall of the acceleration cylinder 11 can be fully cleaned and covered by airflow.

[0037] Furthermore, the purge air duct 31 includes a straight pipe section 314, which is connected to the reduced diameter section 312, and the straight pipe section 314 is sleeved on the outside of the return tube 12. On the one hand, it provides a stable and smooth channel for the airflow in the purge air duct 31, avoiding the problems of increased airflow resistance and reduced flow rate caused by pipe bending or deformation, and ensuring that the airflow in the purge air duct 31 can flow smoothly to the acceleration tube 11 at a higher speed, thereby improving the cleaning effect and gas acceleration performance. On the other hand, the straight pipe section 314 is sleeved on the outside of the return tube 12, making the structure of the entire coal-fired power unit pulverized coal combustion device 100 more compact and efficient, not only improving space utilization, but also reducing the overall size and weight of the equipment, making the coal-fired power unit pulverized coal combustion device 100 more convenient and flexible during installation and operation.

[0038] Optionally, a wear-resistant coating 315 is provided on the cleaning air duct 31, thereby improving the wear resistance of the cleaning air duct 31, extending the service life of the equipment, and reducing the cost and inconvenience caused by frequent replacement or maintenance.

[0039] like Figure 3 As shown, in some embodiments, the reflux cylinder 12 has a third end 121 and a fourth end 122 disposed opposite each other. The diameter of the third end 121 is larger than the diameter of the fourth end 122, thereby forming a conical structure. Furthermore, the third end 121 of the reflux cylinder 12 is connected to the second end 112 of the accelerator cylinder 11, forming a structure with a larger diameter in the middle and smaller diameters at both ends. This allows the pulverized coal fluid to swirl within the reflux cylinder 12 and be smoothly ejected through the injection port 113 of the accelerator cylinder 11.

[0040] Furthermore, a reinforcement layer 13 is provided between the clean air duct 31 and the return tube 12. Specifically, the reinforcement layer 13 wraps around the outer side of the return tube 12, thereby enhancing the structural strength of the return tube 12. In this embodiment, the reinforcement layer 13 is an annular body with a right-angled triangular cross-section. The inclined surface of the triangular cross-section of the reinforcement layer 13 conforms to the return tube 12, forming a narrow, straight ventilation duct between the reinforcement layer 13 and the clean air duct 31. This optimizes the airflow path and reduces resistance and energy consumption during airflow transmission.

[0041] Furthermore, the reinforcement layer 13 is made of thermal insulation. This prevents excessive heat from escaping from the recirculation drum 12 to the purge air duct 31, causing it to overheat. It also maintains a relatively high temperature within the recirculation drum 12, promoting rapid ignition and stable combustion of the pulverized coal. This also enhances the structural strength of the recirculation drum 12.

[0042] like Figure 3 、 Figure 4 and Figure 5 As shown, in some embodiments, the pulverized coal combustion device 100 of the coal-fired power plant further includes a pulverized coal pipe assembly 50, which has a powder delivery port 51. The powder delivery port 51 is located in the cavity 10. The pulverized coal pipe assembly 50 can deliver the pulverized coal fluid into the cavity 10 through the powder delivery port 51, which not only ensures that the pulverized coal fluid can enter the cavity 10 accurately, but also provides a strong guarantee for the uniform distribution and efficient combustion of the pulverized coal.

[0043] In this embodiment, the cavity 10 can be divided into a high-temperature recirculation zone 123 located in the recirculation cylinder 12 and a high-temperature acceleration zone 114 located in the acceleration cylinder 11. The powder feeding port 51 is located at the connection between the recirculation cylinder 12 and the acceleration cylinder 11, and the opening of the powder feeding port 51 is set toward the high-temperature recirculation zone 123, so that the pulverized coal fluid moves toward the high-temperature recirculation zone 123, and after rotating in the high-temperature recirculation zone 123, it flows toward the high-temperature acceleration zone 114 and then flows out through the injection port 113.

[0044] Furthermore, the pulverized coal pipe assembly 50 includes a first return channel 521 and a second return channel 522, and the powder delivery port 51 includes a first return port 511 located in the first return channel 521 and a second return port 512 located in the second return channel 522. The first return port 511 and the second return port 512 are connected, and the opening of the first return port 511 and the opening of the second return port 512 are both arranged toward the inner wall of the return tube 12. The straight line where the opening direction of the first return port 511 is located and the straight line where the opening direction of the second return port 512 is located intersect, so as to spray the pulverized coal fluid into the cavity 10.

[0045] In this embodiment, the opening direction of the first reflow opening 511 is parallel to the axis of the reflow tube 12, and the opening direction of the second reflow opening 512 is inclined from the center to the edge along the radial direction of the reflow tube 12. It is conceivable that the flow rate of the pulverized coal fluid in the first reflow channel 521 and the second reflow channel 522 can be adjusted as needed to change the injection angle of the pulverized coal fluid to meet different usage requirements.

[0046] Furthermore, the pulverized coal pipe assembly 50 also includes a return cap 52 and a guide plate 523. The first return channel 521 and the second return channel 522 are coaxially arranged in the return cap 52. The first return channel 521 is located on the outside of the second return channel 522. The guide plate 523 is arranged at the connection point of the first return port 511 and the second return port 512. The guide plate 523 is provided with an inclined surface on the side facing the second return channel 522, so that the pulverized coal fluid in the second return channel 522 is adhered to the inclined surface of the guide plate 523 and drained to the connection point of the first return port 511 and the second return port 512, and then the pulverized coal fluid in the first return channel 521 and the pulverized coal fluid in the second return channel 522 merge to form a stream of pulverized coal fluid, which is sprayed into the cavity 10.

[0047] In this embodiment, if Figure 4 and Figure 5As shown, the angle between the straight line where the opening direction of the first return port 511 is located and the straight line where the opening direction of the second return port 512 is located can be set to β°, that is, the angle between the coal powder fluid ejected from the first return port 511 and the coal powder fluid ejected from the second return port is β°. The coal powder fluid in the first return channel 521 can be the first fluid, and the coal powder fluid in the second return channel 522 can be the second fluid. The first fluid and the second fluid can converge at the connection point of the first return port 511 and the second return port 512, and then converge into a coal powder mixed fluid for jet ejection. In the above process, by adjusting the flow rate of the first fluid and the second fluid, the jet momentum ratio of the first fluid and the second fluid can be changed, and the mutual injection effect between the first fluid and the second fluid can be changed, so that the ejection angle of the coal powder mixed fluid formed after the first fluid and the second fluid converge is finally made between 0° and β°. Among them, Figure 5 The arrow D indicates the flow direction of the first fluid, and the arrow E indicates the flow direction of the second fluid.

[0048] Among them, when the total amount of coal powder in the first return channel 521 and the second return channel 522 remains unchanged, if the flow rate of the first fluid is increased and the flow rate of the second fluid is reduced, the injection angle of the coal powder mixed fluid formed by the convergence will gradually approach β°; if the flow rate of the first fluid is reduced and the flow rate of the second fluid is increased, the injection angle of the coal powder mixed fluid formed by the convergence will gradually approach 0°.

[0049] It should be noted that when the injection angle of the pulverized coal mixed fluid increases, the radial velocity component of the pulverized coal mixed fluid flowing in all directions increases, while the axial velocity component decreases. This accelerates the decay of the overall flow velocity of the pulverized coal mixed fluid from right to left, causing it to turn earlier and flow from left to right, thereby reducing the axial length of the high-temperature recirculation zone 123. Similarly, when the injection angle of the pulverized coal mixed fluid decreases, the radial velocity component of the pulverized coal mixed fluid flowing in all directions decreases, while the axial velocity component increases. This slows the decay of the overall flow velocity of the pulverized coal mixed fluid from right to left, delaying its turn and causing it to flow from left to right, thereby increasing the axial length of the high-temperature recirculation zone 123.

[0050] like Figure 3 As shown, in this embodiment, the pulverized coal pipe assembly 50 further includes a supply pipe 53, which is provided with a first channel 531 and a second channel 532. The first channel 531 and the second channel 532 are independent of each other. The first channel 531 communicates with the first return channel 521, while the second channel 532 communicates with the second return channel 522. The first channel 531 and the second channel 532 are used to convey different types of pulverized coal fluids into the cavity 10. It should be noted that the different types of pulverized coal fluids can have different flow rates or different concentrations. In this embodiment, the pulverized coal fluids have different flow rates.

[0051] Furthermore, the supply pipe 53 includes an inner pipe 533 and an outer pipe 534. The inner pipe 533 is hollow to form a first channel 531. The outer pipe 534 is sleeved on the outside of the inner pipe 533. A second channel 532 is formed between the outer pipe 534 and the inner pipe 533, thereby ensuring that the two channels are independent of each other and do not interfere with each other, and providing a strong guarantee for the stable transportation of the coal powder fluid.

[0052] Furthermore, the supply pipe 53 further includes a side branch pipe 535 connected to the second channel 532. The side branch pipe 535 is cylindrical, and its axis is perpendicular to the axis of the outer pipe 534. The side branch pipe 535 is used to transport the pulverized coal fluid to the second channel 532.

[0053] like Figure 3 and Figure 6 As shown, in some embodiments, the coal-fired power plant pulverized coal combustion device 100 also includes a secondary air component 70, and the secondary air component 70 includes a plurality of independent air ducts 71. The air duct 71 has an air supply port 711, and the air supply port 711 is arranged at one end of the return tube 12, and the first return port 511 and the second return port 512 are arranged at the other end of the return tube 12. The air supply port 711 is relative to the first return port 511 and the second return port 512, and the air supply port 711 is staggered relative to the first return port 511 and the second return port 512 in the radial direction of the cavity 10, which can not only adjust the radial width of the coal powder fluid in the high-temperature recirculation zone 123, but also provide assistance to the coal powder fluid in the high-temperature recirculation zone 123, thereby accelerating the flow speed of the coal powder fluid toward the injection port 113.

[0054] Specifically, the powder feeding port 51 is provided at the fourth end of the recirculation tube 12, and the first recirculation port 511 and the second recirculation port 512 are provided at the third end of the recirculation tube. The multiple air ducts 71 are not simply arranged side by side or randomly distributed, but are coaxially arranged and nested with each other. Due to the mutual nesting between the air ducts 71, the corresponding air supply ports 711 also present the characteristics of annular arrangement and mutual nesting. This means that when the airflow passes through these air supply ports 711, they will be evenly blown into the high-temperature recirculation zone 123 in the form of an annular wind. This annular wind design not only improves the coverage of the airflow, but also makes the distribution of the airflow in the recirculation tube 12 more uniform, thereby further improving the combustion efficiency and stability of the coal powder.

[0055] Furthermore, the central axis of the air outlet 711 completely coincides with the axis of the return tube 12, ensuring uniform airflow distribution along the axis of the return tube 12 while also preventing airflow deviation or turbulence during delivery. This layout not only improves airflow delivery efficiency but also makes the combustion process more stable and controllable.

[0056] In this embodiment, three air ducts 71 are provided. The pulverized coal pipe assembly 50 includes an inner pipe 721, a middle pipe 722, and an outer pipe 723. The inner pipe 721, middle pipe 722, and outer pipe 723 are arranged in sequence along the radial direction of the cavity 10. Three air ducts 71 are provided between the inner pipe 721, middle pipe 722, and outer pipe 723. The inner pipe 721 is sleeved on the outer side of the pulverized coal pipe outer pipe 534, while the outer pipe 723 is inserted into the purge air duct 31, making the overall structure more compact.

[0057] Furthermore, the secondary air assembly 70 also includes an air supply main duct 724, which is connected to the air duct 71, thereby providing a stable airflow for the air duct 71. The inner tube 721, the middle tube 722, and the outer tube 723 each include an axial tube 725 and a radial tube 726. The axial tube 725 extends in the axial direction of the return tube 12, and the radial tube 726 extends in the radial direction of the return tube 12. The radial tube 726 is connected between the axial tube 725 and the air supply main duct 724, making the air duct 71 Z-shaped, making the overall structure more compact.

[0058] Furthermore, the secondary air assembly 70 also includes a plurality of regulating valves 73, each correspondingly disposed on the air duct 71. The regulating valves 73 are used to adjust the flow rate of the airflow within the air duct 71. Furthermore, the airflow within the air duct 71 can be opened and closed by opening and closing the regulating valves 73, thereby varying the radial width of the pulverized coal mixed fluid within the high-temperature recirculation zone 123. In other words, the secondary air assembly 70 can provide a multi-layer airflow that wraps sequentially from the inside out. By closing or reducing the regulating valves 73 on the inner tube 721, the middle tube 722, and the outer tube 723, the radial width of the multi-layer airflow in the recirculation tube 12 can be varied, thereby adjusting the radial width of the high-temperature recirculation zone 123. The regulating valves 73 are disposed on the radial tube 726.

[0059] In some embodiments, the secondary air assembly 70 further includes a plurality of rotor vanes 74, each of which is disposed in a one-to-one correspondence at the air outlet 711 of the air duct 71. The rotor vanes 74 are used to guide the airflow conveyed by the air duct 71 to form a rotating airflow within the cavity 10. The rotor vanes 74 are disposed on the axial tube 725 and are a plurality of guide vane structures uniformly disposed along the circumference of the air duct 71. Each guide vane is disposed at an angle with the axial direction of the air duct 71, and the angle can be set to 30° to 80°. This allows the airflow passing through the rotor vanes 74 to be converted into a rotating fluid having an axial velocity and a tangential velocity, which is then ejected into the high-temperature recirculation zone 123 of the recirculation cylinder 12.

[0060] In some embodiments, the air duct 71 and the pulverized coal pipe assembly 50 are coaxially arranged. The air duct 71 is located outside the pulverized coal pipe assembly 50. An annular blunt body 75 is provided between the air duct 71 and the pulverized coal pipe assembly 50. The annular blunt body 75 is located at the first end 111 of the return tube 12. The annular blunt body 75 can be provided between the inner tube 721 and the outer tube 534 of the pulverized coal pipe assembly 50.

[0061] Furthermore, the secondary air assembly 70 also includes an end plate 76, which is a circular flat plate structure. The left ends of the outer tube 534, the inner tube 721, the middle tube 722 and the outer tube 723 are connected to the end plate 76 to realize the connection between the pulverized coal pipe assembly 50 and the secondary air assembly 70.

[0062] like Figure 6 As shown, arrow D indicates the flow direction of the pulverized coal fluid in the first channel; arrow E indicates the flow direction of the pulverized coal fluid in the second channel; arrow F indicates the flow direction of the airflow in the secondary air assembly; arrow G indicates the flow direction of the airflow in the cleaning assembly; arrow H indicates the rotation direction of the pulverized coal fluid in the high-temperature recirculation zone; length M is the axial length of the high-temperature recirculation zone; length N is the radial length of the high-temperature recirculation zone. During the use of the above-mentioned pulverized coal combustion device 100 of the coal-fired power plant, one of the two pulverized coal fluids flows toward the first recirculation port 511 through the first channel 531 and the first recirculation channel 521, and the other of the two pulverized coal fluids flows toward the second recirculation port 512 through the second channel 532 and the second recirculation channel 522. The two pulverized coal fluids converge into a pulverized coal mixed fluid at the connection point between the first recirculation port 511 and the second recirculation port 512, and are sprayed from right to left into the high-temperature recirculation zone 123 in the recirculation tube 12 along the axial direction of the recirculation tube 12.

[0063] At the same time, the secondary air assembly 70 divides the secondary air into three streams through the air supply main 724, which are injected into the inner tube 721, the middle tube 722, and the outer tube 723 respectively. Then, under the rotational guidance of the rotor vane 74, the three streams are injected from left to right along the axis of the return tube 12 into the high-temperature recirculation zone 123 of the return tube 12. As a result, three layers of rotating airflow are formed on the left side of the return tube 12, which are wrapped from the inside to the outside. This not only provides oxygen for the combustion of pulverized coal, but also enhances the entrainment effect of the high-temperature airflow by constructing a low-pressure zone inside the rotating airflow, further promoting the formation and maintenance of the high-temperature recirculation zone 123. At the same time, the radial width of the multi-layer airflow in the return tube 12 can be changed by closing or reducing the regulating valves 73 on the inner tube 721, the middle tube 722, and the outer tube 723, thereby adjusting the radial width of the high-temperature recirculation zone 123.

[0064] In addition, the airflow in the cleaning assembly 30 can be injected into the acceleration cylinder 11 from left to right along the axial direction of the return cylinder 12 through the cleaning air duct 31 and the air outlet 311, and flow at high speed along the inner wall of the acceleration cylinder 11, thereby wrapping and carrying the jet flame located in the center to flow out, ensuring the good rigidity of the center flame.

[0065] When the acceleration cylinder 11 and the injection port 113 are cleverly arranged inside the burner, these high-temperature flames can quickly ignite the coal powder airflow around the injection port 113, thereby achieving efficient and stable combustion of the coal powder.

[0066] In summary, under the joint action of the pulverized coal pipe assembly 50, the secondary air assembly 70 and the cleaning assembly 30, a high-temperature recirculation zone 123 can be formed inside the recirculation cylinder 12, and a high-temperature flame can be generated. Then, under the acceleration action of the acceleration cylinder 11, it is ejected at high speed through the injection port 113 to form a high-temperature jet flame, which can ignite the unburned pulverized coal airflow around the injection port 113 in the burner, thereby realizing efficient and continuous combustion of the pulverized coal.

[0067] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying 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 operate in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0068] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0069] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0070] In the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediary. Furthermore, when a first feature is "above," "above," or "above" a second feature, it may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. When a first feature is "below," "below," or "below" a second feature, it may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0071] In the present invention, the terms "one embodiment," "some embodiments," etc., mean that the specific features, structures, materials, or characteristics described in conjunction 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 can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0072] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A pulverized coal combustion device for a coal-fired power plant, characterized in that: include: A cavity, the cavity comprising an accelerating cylinder, the accelerating cylinder having a first end and a second end opposite to each other, the diameter of the first end being smaller than the diameter of the second end, and the first end being provided with an injection port; The cleaning component includes a cleaning air duct, the cleaning air duct having an air outlet, the air outlet being arranged at the second end, the opening of the air outlet being arranged toward the inner wall of the acceleration cylinder, so that the airflow in the cleaning air duct is ejected toward the inner wall of the acceleration cylinder, the cleaning air duct having a reduced diameter section, the reduced diameter section being connected to the second end of the acceleration cylinder; the cavity further includes a return cylinder, the return cylinder and the acceleration cylinder are connected, the cleaning air duct is sleeved on the outer side of the return cylinder, a rectifying channel is provided between the reduced diameter section and the return cylinder, and a plurality of openings are provided between the return cylinder and the acceleration cylinder to form the air outlet; A pulverized coal pipe assembly, the pulverized coal pipe assembly includes a first return channel and a second return channel, the first return channel has a first return port, the second return channel has a second return port, the first return port and the second return port are connected, the opening of the first return port and the opening of the second return port are both set towards the inner wall of the return cylinder, the straight line where the opening direction of the first return port is located and the straight line where the opening direction of the second return port is located intersect, so as to spray the pulverized coal fluid into the cavity.

2. The pulverized coal combustion device of a coal-fired power plant according to claim 1, characterized in that: The pulverized coal pipe assembly also includes a reflux cap and a guide plate. The first reflux channel and the second reflux channel are coaxially arranged in the reflux cap. The first reflux channel is located outside the second reflux channel. The guide plate is arranged at the connection point between the first reflux port and the second reflux port. The guide plate is provided with an inclined surface on the side facing the second reflux channel.

3. The pulverized coal combustion device of a coal-fired power plant according to claim 1, characterized in that: The pulverized coal pipe assembly also includes a supply pipe, in which a first channel and a second channel are provided. The first channel and the second channel are independent of each other. The first channel is connected to the first return channel, and the second channel is connected to the second return channel. The first channel and the second channel are used to transport different types of pulverized coal fluids into the cavity.

4. The pulverized coal combustion device of a coal-fired power plant according to claim 1, characterized in that: It also includes a secondary air component, which includes a plurality of independent air ducts. The air ducts have air supply ports, and the air supply ports are arranged at one end of the return tube. The first return port and the second return port are arranged at the other end of the return tube. The air supply ports are staggered relative to the first return port and the second return port in the radial direction of the cavity.

5. The pulverized coal combustion device of a coal-fired power plant according to claim 4, characterized in that: The secondary air component further includes a plurality of regulating valves, which are arranged on the air duct in a one-to-one correspondence, and the regulating valves are used to adjust the flow rate of the air flow in the air duct.

6. The pulverized coal combustion device of a coal-fired power plant according to claim 4, characterized in that: The secondary air component further includes a plurality of rotor blades, which are arranged in a one-to-one correspondence at the air outlet of the air duct, and the rotor blades are used to guide the airflow transported by the air duct to form a rotating airflow in the cavity.

7. The pulverized coal combustion device of a coal-fired power plant according to claim 4, characterized in that: The air duct and the pulverized coal pipe assembly are coaxially arranged. The air duct is arranged outside the pulverized coal pipe assembly. An annular blunt body is arranged between the air duct and the pulverized coal pipe assembly. The annular blunt body is located at the first end of the reflux cylinder.

8. The pulverized coal combustion device of a coal-fired power plant according to claim 1, characterized in that: The cleaning air duct is provided with a wear-resistant coating.

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