Pulverized coal combustion device of coal power unit

Abstract

The invention provides a coal power unit pulverized coal combustion device, the coal power unit pulverized coal combustion device comprises a cavity and a cleaning assembly, the cavity comprises an acceleration cylinder, the acceleration cylinder is provided with a first end and a second end which are oppositely arranged, the diameter of the first end is smaller than that of the second end, and the first end is provided with a jet orifice. The sweeping assembly comprises a sweeping air pipe, the sweeping air pipe is provided with an air outlet, the air outlet is formed in the second end, and an opening of the air outlet faces the inner wall of the acceleration barrel so that airflow in the sweeping air pipe can be jetted to the inner wall of the acceleration barrel. According to the pulverized coal combustion device of the coal power unit, foreign matter such as pulverized coal bonded to the inner wall of the cavity can be effectively removed, the speed of pulverized coal mixed fluid is increased, the combustion stability and efficiency are improved, and the service life of the pulverized coal combustion device of the coal power unit is prolonged.

Description

Technical Field

[0001] The 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] As one of the key equipment in thermal power plants and other industrial furnaces, the operating performance of pulverized coal combustion equipment directly affects the energy efficiency and safety of the entire system. However, during the use of pulverized coal combustion equipment, the flame jet rigidity is often insufficient, resulting in a large amount of unburned carbon particles and ash adhering to the inner wall of the combustion chamber to form coking, which not only reduces the heat transfer efficiency of the combustion device and increases energy consumption, but also may cause local overheating of the wall of the combustion chamber, causing burning, shortening the service life of the equipment, and even causing 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 main function of pulverized coal combustion equipment is to efficiently convert pulverized coal into heat energy, and its working state will directly affect the energy utilization efficiency and the overall safety of the system. However, in actual use, the rigidity of the flame jet has become one of the key factors restricting the performance of pulverized coal combustion equipment.

[0005] Among them, flame jet rigidity refers to the ability of the flame to maintain a stable shape and direction in the combustion chamber of the combustion equipment. When the flame jet rigidity inside the combustion device is insufficient, the flame cannot effectively resist the interference of external airflow, which will cause the coal powder to be unable to fully mix with oxygen and burn completely, and then part of the coal powder fails to burn completely, forming a large amount of unburned carbon particles and ash residues. And these residues have a certain viscosity under high temperature, and are easy to deposit on the inner wall of the combustion chamber and gradually accumulate, forming a "coking" phenomenon.

[0006] However, the coking of residues in the combustion chamber will not only hinder the effective conduction of heat, reduce the thermal efficiency of the combustion device, and increase energy loss; at the same time, since the heat in the coking area is difficult to dissipate in time, it will cause the temperature of the combustion device wall to rise abnormally, accelerate the aging of metal materials and the degradation of physical properties, and may cause the combustion device to malfunction, bringing unforeseen safety hazards to production, affecting 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 for a coal-fired power plant comprising a cavity and a cleaning assembly, the cavity comprising an acceleration cylinder, the acceleration cylinder having a first end and a second end arranged 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 a jet port. The cleaning assembly comprises 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.

[0008] In summary, the coal powder combustion device of the coal-fired power unit provided by the embodiment of the present invention can gradually accelerate the coal powder mixed fluid through the conical design of the acceleration cylinder, and spray it out at a higher speed through the injection port. And by utilizing the airflow flushing effect of the cleaning component, foreign matter such as coal powder adhering to the inner wall of the cavity can be effectively removed, and the coal powder mixed fluid can be accelerated again, which not only improves the stability and efficiency of combustion, but also prolongs the service life of the coal powder combustion device of the coal-fired power unit, bringing a 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, 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 reflow channel and a second reflow channel, the first reflow channel has a first reflow port, the second reflow channel has a second reflow port, the first reflow port and the second reflow port are connected, the opening of the first reflow port and the opening of the second reflow port are both set toward the inner wall of the reflow cylinder, and the straight line where the opening direction of the first reflow port is located and the straight line where the opening direction of the second reflow 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, 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 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, the second channel is connected to the second return channel, and 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 one by one on the air duct, 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 component further includes a plurality of rotors, which are disposed one by 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 on the outside of the pulverized coal pipe assembly, an annular blunt body is arranged 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 in 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 unit provided in an embodiment of the present invention.

[0020] Figure 3 yes Figure 2 The cross-sectional schematic diagram of the pulverized coal combustion device of the coal-fired power unit along AA is shown.

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

[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 is a schematic diagram of fluid flow in a pulverized coal pipe assembly, a cleaning assembly and a secondary air assembly in a pulverized coal combustion device of a coal-fired power unit provided in an embodiment of the present invention.

[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. Reflow tube; 121. Third end; 122. Fourth end; 123. High-temperature reflow zone; 13. Strengthening 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 delivery 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 tube; 725. Axial tube; 726. Radial tube; 73. Control valve; 74. Rotary vane; 75. Annular blunt body; 76. End plate. DETAILED DESCRIPTION

[0029] 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 for a coal-fired power plant comprises a cavity 10 and a cleaning assembly 30, the cavity 10 comprises an accelerating cylinder 11, the accelerating cylinder 11 comprises a first end 111 and a second end 112 which are arranged opposite to each other, the diameter of the first end 111 is smaller than the diameter of the second end 112, and the first end 111 is provided with a jet port 113. The cleaning assembly 30 comprises a cleaning air duct 31, the cleaning air duct 31 comprises an air outlet 311, the air outlet 311 is arranged at the second end 112 of the accelerating cylinder 11, the opening of the air outlet 311 is arranged toward the inner wall of the accelerating cylinder 11, so that the air flow in the cleaning air duct 31 is ejected toward the inner wall of the accelerating cylinder 11, so that the gas in the cleaning air duct 31 can clean the inner wall of the cavity 10 to avoid coking.

[0031] Specifically, the cavity 10 is the main structure of the coal-fired power plant pulverized coal combustion device 100. 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, so that the mixture of pulverized coal and gas can 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 toward the inner wall of the accelerator cylinder 11, so that the airflow impacts the inner wall of the accelerator cylinder 11, effectively removing foreign matter such as pulverized coal particles adhered to the inner wall of the accelerator cylinder 11, not only avoiding the influence of pulverized coal adhesion on the performance of the accelerator cylinder 11, but also accelerating the mixed fluid again through the flushing effect of the airflow, so that the flow speed of the mixed fluid at the injection port 113 is further improved.

[0032] In summary, the pulverized coal combustion device 100 of the coal-fired power plant provided by the embodiment of the present invention can gradually accelerate the pulverized coal mixed fluid through the conical design of the acceleration cylinder 11, and eject it at a higher speed through the injection port 113. And by utilizing the airflow flushing effect of the cleaning component 30, foreign matter such as pulverized coal adhering to the inner wall of the cavity 10 can be effectively removed, and the pulverized coal mixed fluid can be accelerated again, which not only improves the stability and efficiency of combustion, but also prolongs the service life of the pulverized coal combustion device 100 of the coal-fired power plant, bringing a 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 outer side 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, so that the airflow in the cleaning air duct 31 can flow into the cavity 10.

[0034] Specifically, the purge air duct 31 is sleeved on the outside of the return cylinder 12, and a plurality of openings are provided at the connection between the return cylinder 12 and the acceleration cylinder 11 to form an air outlet 311, so that the gas flows through the gap between the purge air duct 31 and the return cylinder 12, and is then transported to the cavity 10 through the air outlet 311. At the same time, when the coal powder mixed fluid enters the acceleration cylinder 11 from the return cylinder 12, the air flow in the purge air duct 31 will also contact the mixed fluid through the air outlet 311, and form a layer of air film between the mixed fluid and the inner wall of the acceleration cylinder 11, thereby isolating the inner wall of the acceleration cylinder 11 and reducing the possibility of coal powder adhering to the inner wall of the acceleration cylinder 11. In this embodiment, the cross-section of the reduced diameter section 312 is set to be L-shaped.

[0035] In addition, the cleaning air duct 31 is provided with a reduced diameter section 312 at the second end 112 near the accelerating cylinder 11, so that the gap between the reduced diameter section 312 and the return cylinder 12 is reduced, that is, the flow cross section of the rectifying channel 313 is reduced, so that the airflow in the cleaning air duct 31 can be guided, so that the airflow can flow to the inner wall of the accelerating cylinder 11 smoothly and orderly, avoiding the turbulence and eddy phenomenon that may occur in the flow of the airflow. At the same time, the gap between the reduced diameter section 312 and the return cylinder 12 becomes smaller, which can also increase the resistance to the flow of the airflow along the way, making the airflow ejected through the air outlet 311 more uniform, and can also increase the jet speed of the airflow, so that the airflow maintains a high momentum and flows forward along the inner wall of the accelerating 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 cylinder 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 cylinder 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 cleaning 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, a stable and smooth channel is provided for the airflow in the cleaning air duct 31, avoiding the problems of increased airflow resistance and reduced flow velocity caused by pipe bending or deformation, and ensuring that the airflow in the cleaning air duct 31 can flow smoothly to the acceleration tube 11 at a higher speed, thereby improving the cleaning effect and the acceleration performance of the gas. 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, which not only improves the space utilization, but also reduces 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, so as to improve the wear resistance of the cleaning air duct 31, extend the service life of the equipment, and reduce 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 that are arranged opposite to each other, and the diameter of the third end 121 is larger than the diameter of the fourth end 122, thereby forming a cone-like structure. In addition, the third end 121 of the reflux cylinder 12 is connected to the second end 112 of the acceleration cylinder 11, so that the reflux cylinder 12 and the acceleration cylinder 11 form a structure with a large diameter in the middle and small diameters at both ends, so that the pulverized coal fluid can be rotated in the reflux cylinder 12 and smoothly ejected through the injection port 113 of the acceleration cylinder 11.

[0040] Furthermore, a reinforcing layer 13 is provided between the cleaning air duct 31 and the return tube 12, that is, the reinforcing layer 13 is wrapped around the extra side of the return tube 12, thereby improving the structural strength of the return tube 12. In this embodiment, the reinforcing layer 13 is an annular body with a right-angled triangular cross section, and the inclined surface in the triangular cross section of the reinforcing layer 13 fits the return tube 12, so that a narrow and straight ventilation duct can be formed between the reinforcing layer 13 and the cleaning air duct 31, thereby optimizing the flow path of the airflow and reducing the resistance and energy consumption of the airflow during transmission.

[0041] Furthermore, the reinforcing layer 13 is made of thermal insulation cotton, which can prevent excessive heat from being lost from the recirculation tube 12 to the cleaning air duct 31 and causing it to be too hot; on the other hand, it can maintain a relatively high temperature in the recirculation tube 12, promote rapid ignition and stable combustion of the pulverized coal, and at the same time improve the structural strength of the recirculation tube 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 also includes a pulverized coal pipe assembly 50, which has a powder delivery port 51, and the powder delivery port 51 is located in the cavity 10. The pulverized coal pipe assembly 50 can deliver the pulverized coal fluid to 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 reflow zone 123 located in the reflow cylinder 12 and a high-temperature acceleration zone 114 located in the acceleration cylinder 11. The powder delivery port 51 is located at the connection between the reflow cylinder 12 and the acceleration cylinder 11, and the opening of the powder delivery port 51 is set toward the high-temperature reflow zone 123, so that the pulverized coal fluid moves toward the high-temperature reflow zone 123, and after rotating in the high-temperature reflow 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 at the first return channel 521 and a second return port 512 located at 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, and the straight line where the opening direction of the first return port 511 and the straight line where the opening direction of the second return port 512 are 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 port 511 is parallel to the axis of the reflow tube 12, and the opening direction of the second reflow port 512 is inclined from the center to the edge along the radial direction of the reflow tube 12. It can be imagined 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 reflux cap 52 and a guide plate 523. The first reflux channel 521 and the second reflux channel 522 are coaxially arranged in the reflux cap 52. The first reflux channel 521 is located on the outside of the second reflux channel 522. The guide plate 523 is arranged at the connection point between the first reflux port 511 and the second reflux port 512. The guide plate 523 is provided with an inclined surface on the side facing the second reflux channel 522, so that the pulverized coal fluid in the second reflux channel 522 fits the inclined surface of the guide plate 523 and is drained to the connection point between the first reflux port 511 and the second reflux port 512, and then the pulverized coal fluid in the first reflux channel 521 and the pulverized coal fluid in the second reflux channel 522 merge to form a stream of pulverized coal fluid, which is sprayed toward 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 between 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, the jet momentum ratio of the first fluid and the second fluid can be changed by adjusting the flow rate of the first fluid and the second fluid, and the mutual induced 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 around will increase, and the axial velocity component will decrease, so that the overall flow velocity of the pulverized coal mixed fluid from right to left will decay faster, and it will turn early and flow from left to right, thereby achieving the purpose of 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 around will decrease, and the axial velocity component will increase, so that the overall flow velocity of the pulverized coal mixed fluid from right to left will decay slower, and it will turn later and flow from left to right, thereby achieving the purpose of 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, in which a first channel 531 and a second channel 532 are provided, the first channel 531 and the second channel 532 are independent of each other, the first channel 531 is connected to the first return channel 521, and the second channel 532 is connected to the second return channel 522, and the first channel 531 and the second channel 532 are used for conveying different types of pulverized coal fluids into the cavity 10. It should be noted that different types of pulverized coal fluids may have different flow rates or different concentrations of pulverized coal fluids. 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 the axis of the side branch pipe 535 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 pulverized coal combustion device 100 of the coal-fired power plant also includes a secondary air component 70, and the secondary air component 70 includes a plurality of independent air ducts 71, and the air duct 71 has an air supply port 711, and the air supply port 711 is arranged at one end of the reflow tube 12, and the first reflow port 511 and the second reflow port 512 are arranged at the other end of the reflow tube 12, and the air supply port 711 is arranged relative to the first reflow port 511 and the second reflow port 512, and the air supply port 711 is arranged relative to the first reflow port 511 and the second reflow port 512 in the radial direction of the cavity 10. It can not only adjust the radial width of the pulverized coal fluid in the high-temperature reflow zone 123, but also provide assistance for the pulverized coal fluid in the high-temperature reflow zone 123, and accelerate the flow speed of the pulverized coal fluid toward the injection port 113.

[0054] Specifically, the powder delivery port 51 is arranged at the fourth end of the reflow tube 12, and the first reflow port 511 and the second reflow port 512 are arranged at the third end of the reflow tube. The multiple air ducts 71 are not simply arranged side by side or randomly, but are coaxially arranged and mutually nested. Due to the mutual nesting between the air ducts 71, the corresponding air supply ports 711 also show 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 reflow zone 123 in the form of annular wind. This annular wind design not only improves the coverage of the airflow, but also makes the distribution of the airflow in the reflow tube 12 more uniform, thereby further improving the combustion efficiency and stability of the coal powder.

[0055] Moreover, the central axis of the air supply port 711 completely coincides with the axis of the return tube 12, which not only ensures that the airflow can be evenly distributed along the axis of the return tube 12, but also avoids the deviation or turbulence of the airflow during the transportation process. Such a layout not only improves the transportation efficiency of the airflow, 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 may include an inner layer pipe 721, a middle layer pipe 722 and an outer layer pipe 723, which are sequentially arranged along the radial direction of the cavity 10, and three air ducts 71 are correspondingly arranged between the inner layer pipe 721, the middle layer pipe 722 and the outer layer pipe 723. Among them, the inner layer pipe 721 is sleeved on the outer side of the outer pipe 534 of the pulverized coal pipe, and the outer layer pipe 723 is penetrated in the cleaning air pipe 31, so that the overall structure can be made more compact.

[0057] Furthermore, the secondary air assembly 70 further includes an air supply main pipe 724, which is connected to the air duct 71, so as to provide a stable airflow for the air duct 71. The inner layer pipe 721, the middle layer pipe 722 and the outer layer pipe 723 all include an axial pipe 725 and a radial pipe 726, the axial pipe 725 is extended along the axial direction of the return cylinder 12, the radial pipe 726 is extended along the radial direction of the return cylinder 12, and the radial pipe 726 is connected between the axial pipe 725 and the air supply main pipe 724, so that the air duct 71 is arranged in a Z shape, making the overall structure more compact.

[0058] Furthermore, the secondary air assembly 70 also includes a plurality of regulating valves 73, which are arranged one by one on the air duct 71, and the regulating valves 73 are used to adjust the flow rate of the airflow in the air duct 71. And the airflow in the air duct 71 can be opened and closed by opening and closing the regulating valves 73, so that the radial width of the coal powder mixed fluid in the high-temperature recirculation zone 123 can be changed. In other words, the secondary air assembly 70 can provide a multi-layer airflow wrapped from the inside to the outside, and the radial width of the multi-layer airflow in the recirculation 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, so that the radial width of the high-temperature recirculation zone 123 can be adjusted. Among them, the regulating valve 73 is arranged on the radial tube 726.

[0059] In some embodiments, the secondary air assembly 70 further includes a plurality of rotor blades 74, which are arranged one by one at the air outlet 711 of the air duct 71, and the rotor blades 74 are used to guide the airflow transported by the air duct 71 to form a rotating airflow in the cavity 10. The rotor blades 74 are arranged on the axial tube 725, and the rotor blades 74 are a plurality of guide vane structures uniformly arranged along the circumference of the air duct 71, and each guide vane is arranged at an angle with the axial direction of the air duct 71, and the angle can be set to 30° to 80°, so that the airflow flowing through the rotor blades 74 can be a rotating fluid with an axial velocity and a tangential velocity, and then sprayed into the high-temperature reflow zone 123 of the reflow 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 arranged outside the pulverized coal pipe assembly 50, an annular bluff 75 is arranged between the air duct 71 and the pulverized coal pipe assembly 50, and the annular bluff 75 is located at the first end 111 of the return tube 12. The annular bluff 75 can be arranged between the inner layer 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 reflow port 511 through the first channel 531 and the first reflow channel 521, and the other of the two pulverized coal fluids flows toward the second reflow port 512 through the second channel 532 and the second reflow channel 522. The two pulverized coal fluids converge into a pulverized coal mixed fluid at the connection point between the first reflow port 511 and the second reflow port 512, and are sprayed into the high-temperature reflow zone 123 in the reflow tube 12 from right to left along the axial direction of the reflow tube 12.

[0063] At the same time, the secondary air assembly 70 divides the secondary air into three air streams through the air supply main pipe 724, and injects them into the inner tube 721, the middle tube 722 and the outer tube 723 respectively, and then injects them into the high-temperature recirculation zone 123 of the recirculation tube 12 from left to right under the rotation and guidance of the rotary vane 74 and along the axial direction of the recirculation tube 12, so that three layers of rotating airflow wrapped from inside to outside can be formed on the left side of the recirculation tube 12, which can not only provide oxygen for coal powder combustion, but also enhance the entrainment effect of high-temperature airflow by constructing a low-pressure zone inside the rotating airflow, and further promote 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 recirculation 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, so that the radial width of the high-temperature recirculation zone 123 can be adjusted.

[0064] In addition, the airflow in the cleaning component 30 can be injected into the acceleration cylinder 11 from left to right along the axial direction of the reflux 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 reflux cylinder 12, and a high-temperature flame can be generated. Then, under the acceleration action of the acceleration cylinder 11, a high-temperature jet flame is ejected at high speed through the injection port 113 to form the pulverized coal airflow that has not yet been burned 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 is necessary to understand that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0068] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0069] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0070] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in 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 one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0072] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary 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 arranged 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; A cleaning component, the cleaning component includes a cleaning air duct, the cleaning air duct has an air outlet, the air outlet is arranged at the second end, and the opening of the air outlet is 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.

2. The pulverized coal combustion device of a coal-fired power plant according to claim 1, characterized in that: 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, 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.

3. The pulverized coal combustion device of a coal-fired power plant according to claim 2, characterized in that: It also includes a coal powder pipe assembly, which includes a first reflow channel and a second reflow channel, the first reflow channel has a first reflow port, the second reflow channel has a second reflow port, the first reflow port and the second reflow port are connected, the opening of the first reflow port and the opening of the second reflow port are both arranged toward the inner wall of the reflow cylinder, and the straight line where the opening direction of the first reflow port is located and the straight line where the opening direction of the second reflow port is located intersect, so as to spray the coal powder fluid into the cavity.

4. The pulverized coal combustion device of a coal-fired power plant according to claim 3, 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 on the outside of the second reflux channel. The guide plate is arranged at the connection between the first reflux port and the second reflux port. The guide plate has an inclined surface on the side facing the second reflux channel.

5. The pulverized coal combustion device of a coal-fired power plant according to claim 3, 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, and the first channel and the second channel are used to transport different types of pulverized coal fluids into the cavity.

6. The pulverized coal combustion device of a coal-fired power plant according to claim 3, characterized in that: It also includes a secondary air component, which includes a plurality of independent air ducts, each of which has an air supply port, wherein the air supply port is 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, and the air supply port is staggered relative to the first return port and the second return port in the radial direction of the cavity.

7. The pulverized coal combustion device of a coal-fired power plant according to claim 6, 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.

8. The pulverized coal combustion device of a coal-fired power plant according to claim 6, characterized in that: The secondary air component further includes a plurality of rotor blades, which are arranged one by one 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.

9. The pulverized coal combustion device of a coal-fired power plant according to claim 6, 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.

10. 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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