Airflow mill and coal pulverizing system using it in coal-fired boilers

Abstract

This application relates to the field of coal-fired boiler technology, and more particularly to an airflow coal mill and a coal-fired boiler pulverizing system using the same. The airflow coal mill includes: a frame; and a horizontal cylindrical chamber structure fixedly mounted on the frame. The chamber structure has a hollow interior forming a pulverizing chamber. Multiple airflow nozzles are inserted and installed on the circumferential outer wall of the chamber structure. The nozzles of each airflow nozzle extend into the pulverizing chamber, and each nozzle is arranged to spray in the same tangential direction. Each airflow nozzle is connected to a high-pressure gas delivery pipeline of an air compressor. The chamber structure also includes a raw coal inlet and a discharge outlet connected to the pulverizing chamber. This solves the technical problems of existing coal mills, such as high wear on parts, high maintenance costs, high energy consumption per unit product, susceptibility to adhesion and clogging, and significant noise and vibration.

Description

Technical Field

[0001] This application relates to the field of coal-fired boiler technology, and in particular to an airflow coal mill and a coal-fired boiler pulverizing system using the same. Background Technology

[0002] Currently, coal-fired boiler pulverizing systems typically use fan mills for grinding coal. These fan mills rely on high-speed rotating hammers, blades, and other components to directly impact and grind coal lumps. This results in high-speed mechanical collisions between the core components of the mill, such as the hammers, blades, and liners, and the coal lumps, leading to very rapid wear. This is especially true when processing hard coal or coal with a high gangue content, where wear is even more rapid. The high wear on these components necessitates frequent shutdowns to replace them, resulting in short component replacement cycles, high spare parts consumption, and a heavy maintenance workload. Furthermore, this reduces the continuous operating time and effective utilization rate of the boiler system, significantly increasing maintenance and operating costs.

[0003] Furthermore, since this type of fan-driven coal mill uses an electric motor to drive the rotor to rotate at high speed, the energy consumed during the crushing process is mainly used to drive the rotor to rotate at high speed and to deal with the mechanical impact between the components and the coal. When finer coal powder is required, the rotation speed needs to be increased or the grinding time needs to be extended, which leads to a significant increase in the energy consumption per unit of coal powder. Over-crushing may also be exacerbated, resulting in a decrease in crushing efficiency.

[0004] Furthermore, this type of fan mill is not very adaptable to different coal types and moisture content. When the raw coal is hard or has a high moisture content, the output of the fan mill will decrease significantly, wear will intensify, and adhesion and blockage may even occur, affecting the stable operation of the pulverizing system. In addition, due to the high-speed rotating heavy components and intense material impact, this type of fan mill usually generates considerable noise and vibration, placing certain requirements on the plant environment and equipment foundation.

[0005] Furthermore, this type of fan-type coal mill has limited ability to adjust the fineness of pulverized coal, making it difficult to accurately control the upper limit particle size and particle size distribution of pulverized coal. The fineness and uniformity of the finished pulverized coal are difficult to control, and the content of coarse particles in the finished pulverized coal is often too high, with uneven fineness. This makes it difficult to meet the strict requirements of modern efficient and clean combustion technology for high-quality pulverized coal (such as the proportion of R90 sieve residue being less than a specific value), affecting boiler combustion efficiency and the control of pollutants such as NOx. Utility Model Content

[0006] The purpose of this application is to provide an airflow coal mill and a coal-fired boiler pulverizing system using the same, in order to solve the technical problems of existing coal mills, such as high wear of wear parts, high maintenance costs, high energy consumption per unit product, easy adhesion and blockage, and large noise and vibration.

[0007] In a first aspect, this application provides an airflow coal mill, comprising:

[0008] The machine includes a frame and a horizontal cylindrical silo structure fixedly mounted on the frame. The silo structure has a hollow interior forming a crushing chamber. Multiple airflow spray guns are inserted into the circumferential outer wall of the silo structure. The nozzles of each airflow spray gun are inserted into the crushing chamber and are arranged to spray in the same tangential direction. Each airflow spray gun is connected to a high-pressure gas delivery pipe of an air compressor. The silo structure also includes a raw coal inlet and a discharge outlet connected to the crushing chamber.

[0009] Furthermore, the inner wall of the pulverizing chamber is provided with a wear-resistant liner, and the nozzles of each of the airflow spray guns are inserted into the pulverizing chamber through the wear-resistant liner.

[0010] Furthermore, the chamber structure is a horizontal annular cylindrical structure, and the crushing chamber is an annular cylindrical cavity structure.

[0011] Furthermore, a classifying wheel is coaxially mounted on the inner annular ring of the crushing chamber. The classifying wheel has multiple inclined classifying blades evenly distributed around the inner annular ring, and the center of the classifying wheel is set as the discharge port.

[0012] Furthermore, the grading wheel includes a front wheel body and a rear wheel body, with an internal cavity formed between the front wheel body and the rear wheel body. Each of the grading blades is spaced apart between the front wheel body and the rear wheel body, and the discharge port is located at the center of the front wheel body.

[0013] Furthermore, the grading wheel also includes a conical surface located on the outer side of the rear wheel body, and a dynamic airflow channel is formed axially inside the conical surface, which is connected to the internal cavity.

[0014] Furthermore, each of the graded blades is rotatably connected to the front wheel body and the rear wheel body;

[0015] The grading wheel is also equipped with a motor control terminal for controlling the rotation of the grading blades to adjust their tilt angle.

[0016] Furthermore, the spacing between each of the graded blades is uniform, with the spacing being between 100 and 300 mm;

[0017] The tilt angle of each of the graded blades is between 15° and 45°.

[0018] Furthermore, the airflow spray guns are spaced apart and staggered from each other.

[0019] Secondly, the coal-fired boiler pulverizing system provided in this application includes the airflow pulverizer described in any one of the preceding descriptions.

[0020] Compared with the prior art, this application provides an airflow coal mill and a coal-fired boiler pulverizing system using the same. The airflow coal mill includes a frame and a horizontal cylindrical chamber structure fixedly installed on the frame. The chamber structure is hollow and forms a pulverizing chamber. Multiple airflow nozzles are inserted and installed on the circumferential outer wall of the chamber structure. Each airflow nozzle is connected to a delivery pipe of an air compressor for generating high-pressure gas. The delivery pipe is used to deliver high-pressure gas to each airflow nozzle. The nozzles of each airflow nozzle are inserted into the pulverizing chamber. The high-pressure gas passes through each nozzle, and thermal expansion accelerates to form a supersonic airflow that is injected into the pulverizing chamber. The nozzles are arranged clockwise or counterclockwise along the same tangential direction, forming a high-speed rotating vortex airflow field in the pulverizing chamber.

[0021] Raw coal particles entering from the raw coal inlet are immediately captured and entrained by the high-speed rotating airflow field after entering the crushing chamber. Crushing mainly relies on the interaction between airflow energy and coal particles, rather than the direct impact and grinding of coal blocks by high-speed rotating hammers, blades and other components, as is the case with existing fan mills. This significantly reduces the wear rate of the main crushing components, extends the maintenance cycle, reduces maintenance costs, and also reduces noise and vibration compared to existing fan mills with the same output.

[0022] Furthermore, the energy of the airflow mill provided in this application is mainly used to generate high-speed airflow from compressed air. Compared with existing fan mills, although compressed air itself also consumes energy, the energy utilization efficiency of supersonic airflow is higher in terms of impact and interparticle grinding. When preparing finer coal powder, it can achieve lower unit energy consumption and higher pulverization efficiency. Moreover, when processing materials, the high-speed airflow itself has a certain drying effect, and the material is in a fluidized or suspended state in the chamber, making it more adaptable to high-moisture coal and less prone to clogging and adhesion. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 This is a process flow diagram of the airflow coal mill provided in the embodiments of this application;

[0025] Figure 2 This is a cross-sectional view of the airflow coal mill provided in an embodiment of this application;

[0026] Figure 3This is a cross-sectional view of the grading wheel provided in an embodiment of this application.

[0027] Figure label:

[0028] 100-Airflow coal mill;

[0029] 10-Rack;

[0030] 20- Warehouse structure;

[0031] 21 - Raw coal inlet;

[0032] 30 - Grinding chamber;

[0033] 31-Abrasion-resistant lining;

[0034] 40-Airflow spray gun;

[0035] 50-Grading wheel;

[0036] 51-Graded blades;

[0037] 52 - Discharge port;

[0038] 53-Front wheel body;

[0039] 54 - Rear wheel assembly;

[0040] 55 - Internal cavity;

[0041] 56 - Conical surface;

[0042] 57 - Dynamic airflow channel;

[0043] 201-Coal Bunker;

[0044] 202-Coal feeder;

[0045] 203 - Boiler Combustion Chamber;

[0046] 204 - Pulverized coal discharge pipe. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0048] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0049] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0050] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this application is in use. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. In addition, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0052] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0053] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0054] like Figures 1 to 3 As shown, this application provides an airflow mill 100 and a coal-fired boiler pulverizing system using the airflow mill 100.

[0055] like Figure 1 and Figure 2As shown, the airflow pulverizer 100 may include a frame 10 and a horizontal cylindrical silo structure 20 fixedly installed on the frame 10. The silo structure 20 is hollow, forming a pulverizing chamber 30. Multiple airflow spray guns 40 are inserted and installed on the circumferential outer wall of the silo structure 20. The nozzles of each airflow spray gun 40 are inserted into the pulverizing chamber 30 and are arranged to spray in the same tangential direction. Each airflow spray gun 40 is connected to the conveying pipeline of the air compressor of the coal-fired boiler pulverizing system for conveying high-pressure gas. The silo structure 20 also includes a raw coal inlet 21 and a discharge port 52 connected to the pulverizing chamber 30. The raw coal inlet 21 may be connected to a coal feeder 202, which may be connected to a coal bunker 201. The discharge port 52 may be connected to a pulverized coal discharge pipe 204, which may be connected to a boiler combustion chamber 203.

[0056] Compared with the prior art, the embodiments of this application provide an airflow coal mill 100 and a coal-fired boiler pulverizing system using the same. The airflow coal mill 100 includes a frame 10 and a horizontal cylindrical chamber structure 20 fixedly installed on the frame 10. The chamber structure 20 is hollow to form a pulverizing chamber 30, and a plurality of airflow nozzles 40 are inserted and installed on the circumferential outer wall of the chamber structure 20. Each airflow nozzle 40 is connected to a conveying pipe of an air compressor for generating high-pressure gas. The conveying pipe is used to convey high-pressure gas to each airflow nozzle 40, and the nozzles of each airflow nozzle 40 are inserted into the pulverizing chamber 30. The high-pressure gas passes through each nozzle, and thermal expansion accelerates to form a supersonic airflow that is injected into the pulverizing chamber 30. The nozzles are arranged to spray clockwise or counterclockwise along the same tangential direction, forming a high-speed rotating vortex airflow field in the pulverizing chamber 30.

[0057] The raw coal particles entering through the raw coal inlet 21 are immediately captured and entrained by the high-speed rotating airflow field after entering the crushing chamber 30. Crushing mainly relies on the interaction between the airflow energy and the coal particles, rather than on the direct impact of high-speed rotating hammers, blades and other components to grind coal lumps, as is the case with existing fan mills. This significantly reduces the wear rate of the main crushing components, i.e., the wear parts, extends the maintenance cycle, reduces maintenance costs, and also reduces noise and vibration compared to existing fan mills with the same output. This solves the technical problems of high wear parts wear, high maintenance costs, low availability and high noise and vibration in existing coal mills.

[0058] Furthermore, the energy of the airflow mill 100 provided in this application embodiment is mainly used to compress air to generate high-speed airflow. Compared with the existing fan mill, although the compressed air itself also consumes energy, the energy utilization efficiency of the supersonic airflow is higher in terms of impact and interparticle grinding. When preparing finer coal powder, it can achieve lower unit energy consumption and higher crushing efficiency, thus solving the technical problem of high unit product energy consumption of existing coal mills.

[0059] Furthermore, the airflow coal mill 100 provided in this application embodiment has a certain drying effect when processing materials, and the materials are in a fluidized or suspended state in the crushing chamber, which makes it more adaptable to high-moisture coal and less prone to clogging and adhesion. This solves the technical problem that existing coal mills have poor adaptability to coal types and moisture content and are prone to adhesion and clogging.

[0060] As the raw coal particles entering through the raw coal inlet 21 are immediately captured and entrained by the high-speed rotating airflow field upon entering the crushing chamber 30, they collide with the inner wall of the crushing chamber 30 at extremely high speeds and are crushed under tremendous impact force. The inner wall of the crushing chamber 30 acts as the target surface impacted by the accelerated airflow, bearing the main impact wear. On the other hand, and also the main crushing method, the raw coal particles undergo intense, high-frequency collisions, friction, and shearing with each other, achieving efficient grinding crushing. This grinding crushing effectively reduces the wear rate of the main crushing components of the equipment (such as the inner wall of the crushing chamber 30) and improves the fineness of the coal powder, resulting in finer coal powder. Under the simultaneous and mutually reinforcing effects of the two crushing methods (impact crushing and grinding crushing), the material does not stop after one impact but continues to be accelerated again by the rotating airflow into the airflow of the next nozzle, continuously colliding and grinding with other particles, forming a continuous and cyclical crushing process.

[0061] In a further embodiment, to improve the wear resistance of the inner wall of the crushing chamber 30, which is one of the main crushing components, such as... Figure 2 As shown, the inner wall of the crushing chamber 30 can be configured as a wear-resistant liner 31, and the nozzles of each airflow spray gun 40 are inserted into the crushing chamber 30 through the wear-resistant liner 31.

[0062] Another further embodiment, such as Figure 2 As shown, in order to prevent mutual interference and influence between adjacent airflow spray guns 40 during spraying, and to ensure the working effect of repeated impact and grinding of coal powder on the inner wall of the crushing chamber 30, it is preferable that each airflow spray gun 40 is spaced apart and staggered.

[0063] In a preferred embodiment, the present application also provides a forced dynamic grading mechanism, which can more accurately control the maximum particle size and particle distribution of pulverized coal, improve the uniformity and fineness of pulverized coal, and has a wider adjustment range.

[0064] Specifically, such as Figure 2 and Figure 3As shown, the chamber structure 20 can be configured as a horizontal annular cylindrical structure, and the crushing chamber 30 can be configured as an annular cylindrical cavity structure. A classifying wheel 50 is coaxially mounted on the inner ring of the annular cylindrical crushing chamber 30. The classifying wheel 50 has multiple inclined classifying blades 51 evenly distributed around the inner ring, and the center of the classifying wheel 50 is set as the discharge port 52.

[0065] Among them, such as Figure 3 As shown, the grading wheel 50 may include a front wheel body 53 and a rear wheel body 54, as well as a conical surface 56 located outside the rear wheel body 54. An internal cavity 55 is formed between the front wheel body 53 and the rear wheel body 54. Each grading blade 51 is spaced apart between the front wheel body 53 and the rear wheel body 54. The discharge port 52 is provided at the center of the front wheel body 53. A dynamic airflow channel 57 is formed axially inside the conical surface 56. The dynamic airflow channel 57 is connected to the internal cavity 55 and provides airflow drag to the internal cavity 55. The conical surface 56 can also guide the airflow to form secondary separation to avoid coarse particles from being mixed in.

[0066] Driven by the high-speed rotating airflow field in the grinding chamber 30, the coal powder forms a rotating fluidized bed. The particles diffuse outward due to centrifugal force. Among them, the particles with large mass and strong centrifugal force are thrown to the outside of the classifying wheel 50. After being blocked by the classifying blades 51, they return to the grinding chamber 30 for further grinding. The particles with small mass and weak centrifugal force are dominated by the airflow drag force provided by the dynamic airflow channel 57. They pass through the gap of the classifying blades 51 with the airflow and enter the interior of the classifying wheel 50, and are discharged from the central outlet.

[0067] Coal powder that meets the particle size requirements passes through the classifying wheel 50, is drawn away by negative pressure, and discharged through the central outlet 52. It is then transported to the boiler combustion chamber 203 via the external coal powder discharge pipe 204. Coal powder that does not meet the particle size requirements remains in the crushing chamber 30 for further crushing. This process achieves dynamic particle sieving through the combined action of centrifugal force and airflow. Furthermore, the higher the rotational speed of the classifying wheel 50, the greater the centrifugal force, allowing only finer particles to pass through, thus enabling precise control of particle size and achieving more refined sieving control.

[0068] Furthermore, the size of the inlet can be adjusted by adjusting the tilt angle of the classifying blades 51, thereby further controlling the dynamic screening of particles and improving the fineness and uniformity of coal powder. It is preferable that the tilt angle of each classifying blade 51 is between 15° and 45° to reduce pressure drop and drive energy consumption, and improve the classification accuracy as needed.

[0069] Specifically, each grading blade 51 is rotatably connected to the front wheel body 53 and the rear wheel body 54, and is rotatably connected along its axial direction. The grading wheel 50 may also be provided with a motor control terminal for controlling the rotation of each grading blade 51 to adjust its tilt angle. Thus, the particle size requirement can be adjusted by controlling the tilt angle of each grading blade 51.

[0070] In one specific embodiment, the staged blades 51 are preferably evenly spaced, with the spacing between 100 and 300 mm, to meet the requirements of high throughput.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An air swept coal mill, characterised in that, include: frame; The machine includes a horizontal cylindrical silo structure fixedly mounted on the frame. The silo structure has a hollow interior forming a crushing chamber. Multiple airflow spray guns are inserted into the circumferential outer wall of the silo structure. The nozzles of each airflow spray gun are inserted into the crushing chamber and are arranged to spray in the same tangential direction. Each airflow spray gun is connected to a high-pressure gas delivery pipe of an air compressor. The silo structure also includes a raw coal inlet and a discharge outlet connected to the crushing chamber.

2. The airflow mill according to claim 1, characterized in that, The inner wall of the pulverizing chamber is provided with a wear-resistant lining, and the nozzles of each of the airflow spray guns are inserted into the pulverizing chamber through the wear-resistant lining.

3. The airflow mill according to claim 1 or 2, characterized in that, The chamber structure is a horizontal annular cylindrical structure, and the crushing chamber is an annular cylindrical cavity structure.

4. The airflow mill according to claim 3, characterized in that, A classifying wheel is coaxially mounted on the inner annular ring of the crushing chamber. The classifying wheel has multiple inclined classifying blades evenly distributed around the inner annular ring, and the center of the classifying wheel is set as the discharge port.

5. The airflow coal mill according to claim 4, characterized in that, The grading wheel includes a front wheel body and a rear wheel body, with an internal cavity formed between the front wheel body and the rear wheel body. Each grading blade is spaced apart between the front wheel body and the rear wheel body, and the discharge port is located at the center of the front wheel body.

6. The airflow mill according to claim 5, characterized in that, The graded wheel also includes a conical surface located on the outer side of the rear wheel body, and a dynamic airflow channel is formed axially inside the conical surface, which is connected to the internal cavity.

7. The airflow mill according to claim 5 or 6, characterized in that, Each of the graded blades is rotatably connected to the front wheel body and the rear wheel body; The grading wheel is also equipped with a motor control terminal for controlling the rotation of the grading blades to adjust their tilt angle.

8. The airflow mill according to claim 7, characterized in that, The graded blades are evenly spaced, with the spacing between 100 and 300 mm. The tilt angle of each of the graded blades is between 15° and 45°.

9. The airflow coal mill according to claim 1, characterized in that, The airflow spray guns are spaced apart and staggered from each other.

10. A coal-fired boiler pulverizing system characterized by comprising: The gas flow mill includes any one of claims 1 to 9.

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