Powder selecting device for coal mill
Through the multi-stage screening powder selection device, the problem of uneven particle size of coal powder in existing coal mills is solved, the powder selection ability of coal mills and the combustion efficiency of boilers is improved, and energy consumption and fly ash carbon content is reduced.
Patent Information
- Application Number
- CN202421496213.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-06-27
AI Technical Summary
The existing coal mill powder selection device can only perform first-stage or second-stage separation, resulting in the selected coal powder particle size not being delicate enough, affecting the combustion effect.
A multi-stage screening powder selection device is designed, including a coal powder separator, powder selection chamber, buffer bin and coal drop pipe. Multi-stage screening is carried out through gradually narrowing gaps and rotating centrifugal force, and combined with the design of buffer bin and coal drop pipe, multi-stage screening of coal powder is realized.
It improves the powder selection ability of the coal mill, improves the fineness and uniformity of the coal powder, reduces the energy consumption of powder making, improves the combustion efficiency of the boiler and reduces the emission of carbon content of fly ash.
Smart Images
Figure CN223128253U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of coal mills, in particular to a powder selecting device for a coal mill. Background Technique
[0002] The coal mill is the most important auxiliary machine in the boiler coal pulverizing system, which is responsible for grinding raw coal into pulverized coal with qualified fineness and blowing it into the boiler for combustion. The operation status of the coal mill affects the safe and economic operation of the boiler, and the output and fineness of the pulverized coal of the coal mill affect the combustion state and efficiency of the boiler. The separator is a powder selecting and separating device supporting the coal mill, which is used to separate pulverized coal and large particles.
[0003] The existing powder selecting device in the coal mill has only one-stage or two-stage separation. After each piece is ground into powder, it will flow into the separator together with the upward high-speed air flow. The separator uses centrifugal force to separate the large-particle pulverized coal from the small-particle pulverized coal in the air flow. Finally, the small-particle pulverized coal continues to move upward with the high-speed air flow and is discharged from the coal mill through the pipeline together with the high-speed air flow, while the large-particle pulverized coal will fall into the coal mill under the action of its own weight. Since the powder selecting device has only one-stage or two-stage separation structure, the particle size of the selected pulverized coal is not fine enough, and there are often large-particle pulverized coals mixed in it, and the particle size is not uniform enough, which affects the combustion effect of the pulverized coal. Content of the Utility Model
[0004] The purpose of the utility model is to solve the above problems, and a powder selecting device for a coal mill is designed to solve the problem that the particle size of the pulverized coal selected by the existing powder selecting device is not uniform enough.
[0005] To achieve the above object, the technical solution of the utility model is as follows: A powder selecting device for a coal mill, which is used to be installed in a coal mill, includes:
[0006] A pulverized coal separator, and a blanking hopper is arranged at the bottom of the pulverized coal separator;
[0007] A powder selecting bin, the pulverized coal separator and the blanking hopper are both arranged in the powder selecting bin, and the gaps between the blanking hopper and the pulverized coal separator and the powder selecting bin gradually decrease from bottom to top;
[0008] A buffer bin, the buffer bin is arranged at the top of the pulverized coal separator and is communicated with the pulverized coal separator, and the buffer bin has a discharge port;
[0009] A coal dropping pipe, the coal dropping pipe sequentially passes through the buffer bin and the pulverized coal separator from top to bottom and extends into the blanking hopper, and the gap between the buffer bin and the coal dropping pipe gradually increases from bottom to top.
[0010] Preferably, the side or the top of the pulverized coal separator has an inlet and is communicated with the powder selecting bin.
[0011] Preferably, a protection bin is provided at the top of the powder selection bin, the buffer bin is arranged inside the protection bin, and a driving mechanism for driving the coal powder separator to rotate is provided at the top of the protection bin.
[0012] Preferably, the lower end of the coal dropping pipeline extends to a position close to the outlet of the feeding hopper, and a discharging pipeline is arranged at the outlet of the feeding hopper.
[0013] Preferably, a baffle is arranged along the circumferential direction at the lower end of the coal dropping pipeline, and the baffle extends obliquely downward and has a gap with the inner wall of the feeding hopper.
[0014] Preferably, the powder selection bin successively includes a first bin body, a second bin body and a third bin body from top to bottom. The coal powder separator is located in the first bin body, the feeding hopper is located in the second bin body and the third bin body. The gap between the first bin body and the coal powder separator gradually decreases from bottom to top, and the gap between the feeding hopper and the second bin body gradually decreases from bottom to top.
[0015] Preferably, a sealing ring is arranged at the connection between the buffer bin and the coal powder separator.
[0016] Compared with the prior art, the beneficial effects are as follows:
[0017] In the utility model, coal lumps enter the coal mill through the coal dropping pipe. Coal powder enters the coal powder separator through the gaps between the powder selection bin, the feeding hopper and the coal powder separator along with the gas flowing upward at high speed. Since the gaps between the powder selection bin, the feeding hopper and the coal powder separator gradually decrease from bottom to top, coal powder can be screened. Large-particle coal powder cannot pass through and drops into the coal mill. The coal powder separator rotates to further screen the coal powder. The screened coal powder enters the buffer bin along with the gas flowing at high speed. The gap between the buffer bin and the coal dropping pipe also gradually increases from bottom to top. After the gas enters the buffer bin, the flow rate becomes smaller, and the kinetic energy obtained by the coal powder also becomes smaller. Large-particle coal powder will drop downward under the influence of its own weight, and small-particle coal powder meeting the requirements will be discharged from the buffer bin through the pipeline. In this way, coal powder can be screened at multiple levels to select coal powder meeting the requirements, which can comprehensively improve the powder selection ability of the coal mill, improve the fineness and uniformity of coal powder, reduce the coal powder grinding energy consumption of the coal mill, improve the boiler combustion efficiency, reduce the emission of fly ash carbon content, reduce the coal consumption of the unit, and finally achieve the effect of increasing production and improving efficiency. Description of the Drawings
[0018] Figure 1 is a sectional structural schematic diagram of the powder selection device in the utility model;
[0019] Figure 2 is a schematic diagram of the flow of coal powder in the powder selection device.
[0020] In the figure, 1 is the powder selection bin; 11 is the first bin body; 12 is the second bin body; 13 is the third bin body; 2 is the pulverized coal separator; 3 is the protection bin; 4 is the buffer bin; 5 is the blanking hopper; 6 is the coal dropping pipe; 7 is the baffle; 8 is the blanking pipeline; 9 is the driving mechanism. Specific embodiments
[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0022] As Figure 1 - Figure 2 shown, a preferred embodiment of the present invention proposes a powder selection device for a coal mill, which is generally installed on the top of the coal mill. After the coal mill grinds coal blocks into powder, the pulverized coal will flow into the powder selection device along with the high-speed air flow, and the pulverized coal will be screened at multiple levels. The large coal blocks will fall back onto the grinding table of the coal mill for re-grinding, and the pulverized coal that meets the requirements will be discharged through the pipeline under the drive of the high-speed air flow.
[0023] Referring to Figure 1 , the powder selection device mainly includes components such as the pulverized coal separator 2, the protection bin 3, the powder selection bin 1, the buffer bin 4, and the coal dropping pipe 6. Among them, the protection bin 3 is installed on the top of the powder selection bin 1, the buffer bin 4 is installed in the protection bin 3, the pulverized coal separator 2 is installed in the powder selection bin 1 and is connected to the bottom of the buffer bin 4. The coal dropping pipe 6 passes through the buffer bin 4 and the pulverized coal separator 2 in sequence from top to bottom. The coal dropping pipe 6 is used for feeding coal blocks, and the coal blocks will fall into the coal mill through the coal dropping pipe 6.
[0024] As Figure 1 shown, the powder selection bin 1 is mainly composed of three bin bodies, including the first bin body 11, the second bin body 12, and the third bin body 13 in sequence from top to bottom. The shape of the first bin body 11 is frustum-shaped, the pulverized coal separator 2 is located in the first bin body 11, and the gap between the first bin body 11 and the pulverized coal separator 2 gradually decreases from bottom to top to screen the pulverized coal.
[0025] A blanking hopper 5 is provided at the bottom of the pulverized coal separator 2. The blanking hopper 5 is conical to facilitate the falling of the large coal blocks after screening. The blanking hopper 5 is located in the second bin body 12 and the third bin body 13. A blanking pipeline 8 is provided at the bottom of the blanking hopper 5, and the lower end of the blanking pipeline 8 extends downward above the grinding table in the coal mill.
[0026] The shape of the second bin body 12 is inverted frustum-shaped, and the gap between the second bin body 12 and the blanking hopper 5 gradually decreases from bottom to top. The shape of the third bin body 13 is cylindrical, and the gap between the third bin body 13 and the blanking hopper 5 also gradually decreases from bottom to top. The bottom of the third bin body 13 is the inlet.
[0027] The gaps between the entire powder selection bin 1, the pulverized coal separator 2, and the blanking hopper 5 all gradually decrease from bottom to top. The pulverized coal enters the third bin body 13 with the upward high-speed air flow for primary screening. Due to the gradually decreasing gap, large coal particles will lose kinetic energy and fall downward onto the grinding table of the coal mill. The pulverized coal enters the second bin body 12 with the high-speed air flow for secondary screening; then it enters the first bin body 11 for tertiary screening.
[0028] The circumferential direction of the pulverized coal separator 2 has several holes so that the pulverized coal can enter the pulverized coal separator 2 laterally with the high-speed air flow. The pulverized coal separator 2 rotates, and uses centrifugal force to screen out large particles in the pulverized coal for quaternary screening of the pulverized coal. The screened large particles will directly fall downward into the blanking hopper 5 and finally enter the grinding table of the coal mill through the blanking pipeline 8.
[0029] In other technical solutions, the inlet position can also be set at the top of the pulverized coal separator 2, so that the pulverized coal will enter the pulverized coal separator 2 through the gap between the top wall of the first bin body 11 and the top surface of the pulverized coal separator 2 with the high-speed air flow.
[0030] The bottom of the buffer bin 4 is connected to the pulverized coal separator 2. The shape of the buffer bin 4 is an inverted frustum. The gap between the buffer bin 4 and the coal dropping pipe 6 gradually increases from bottom to top, and the minimum gap between the buffer bin 4 and the coal dropping pipe 6 is also smaller than the minimum gap between the powder selection bin 1 and the pulverized coal separator 2. The pulverized coal will enter the buffer bin 4 with the high-speed flowing gas for quinary screening of the pulverized coal.
[0031] Since the gap between the buffer bin 4 and the coal dropping pipe 6 gradually increases from bottom to top, after the high-speed flowing gas enters the buffer bin 4, the gas flow rate will decrease. At this time, the kinetic energy obtained by the pulverized coal will also decrease. The pulverized coal with a larger self-weight will fall under the action of gravity into the pulverized coal separator 2 and finally into the blanking hopper 5.
[0032] The buffer bin 4 does not rotate with the pulverized coal separator 2. A sealing ring is provided at the connection between the buffer bin 4 and the pulverized coal separator 2 for enhanced sealing.
[0033] The side wall or the top of the buffer bin 4 has an outlet, and the screened pulverized coal will be discharged through the pipeline connected to the outlet together with the relatively high-speed gas.
[0034] Such as Figure 1As shown in the figure, a driving mechanism 9 is provided at the top of the protection bin 3. The driving mechanism 9 is composed of components such as a motor and a speed reducer, and can drive the coal powder separator 2 to rotate. In this embodiment, the coal dropping pipe 6 is divided into three sections, and the section of the coal dropping pipe 6 located in the coal powder separator 2 will rotate together with the coal powder separator 2. A sealing structure is provided at the connection between each section of the coal dropping pipe 6 to enhance the sealing performance.
[0035] In order to prevent the coal powder from flowing back into the hopper 5, a ring of baffles 7 is axially provided at the lower end of the coal dropping pipe 6. The baffles 7 are inclined downward and have a certain gap with the hopper 5. The large coal lumps falling from the coal powder separator 2 will fall into the hopper 5 and then fall out from the bottom of the hopper 5 along the gap between the hopper 5 and the baffles 7.
[0036] A buffer cavity is formed between the bottom of the baffle 7 and the coal dropping pipe 6. The coal powder flowing back from the coal mill will enter the buffer cavity and lose its kinetic energy after being blocked by the baffle 7 and then fall back into the coal mill again.
[0037] The above technical solutions only reflect the preferred technical solutions of the technical solutions of the present utility model. Some changes that may be made by those skilled in the art to some parts thereof all reflect the principles of the present utility model and fall within the protection scope of the present utility model.
Claims
1. A powder selection device for a coal mill, which is used to be installed in the coal mill, and is characterized in that, Comprising: A pulverized coal separator (2), at the bottom of which a blanking hopper (5) is provided; A powder selection bin (1), both the pulverized coal separator (2) and the blanking hopper (5) are arranged in the powder selection bin (1), and the gaps between the blanking hopper (5) and the pulverized coal separator (2) and the powder selection bin (1) gradually decrease from bottom to top; A buffer bin (4), which is arranged on the top of the pulverized coal separator (2) and is communicated with the pulverized coal separator (2), and the buffer bin (4) has a discharge port; A coal dropping pipe (6), which sequentially passes through the buffer bin (4) and the pulverized coal separator (2) from top to bottom and extends into the blanking hopper (5), and the gap between the buffer bin (4) and the coal dropping pipe (6) gradually expands from bottom to top.
2. The powder separator for a coal mill according to claim 1, characterized in that The side or top of the pulverized coal separator (2) has an inlet and is communicated with the powder selection bin (1).
3. The powder separator for coal mill according to claim 1, characterized in that, A protection bin (3) is arranged on the top of the powder selection bin (1), the buffer bin (4) is arranged in the protection bin (3), and a driving mechanism (9) for driving the pulverized coal separator (2) to rotate is arranged on the top of the protection bin (3).
4. The powder separator for coal mill according to claim 1, characterized in that, The lower end of the coal dropping pipe (6) extends to a position close to the outlet of the blanking hopper (5), and a blanking pipeline (8) is arranged at the outlet of the blanking hopper (5).
5. The powder separator for coal mills according to claim 4, characterized in that, A baffle is arranged along the circumferential direction at the lower end of the coal dropping pipe (6), and the baffle extends obliquely downward and leaves a gap with the inner wall of the blanking hopper (5).
6. The powder separator for coal mill according to claim 1, characterized in that The powder selection bin (1) sequentially includes a first bin body (11), a second bin body (12) and a third bin body (13) from top to bottom. The pulverized coal separator (2) is located in the first bin body (11), the blanking hopper (5) is located in the second bin body (12) and the third bin body (13), the gap between the first bin body (11) and the pulverized coal separator (2) gradually decreases from bottom to top, and the gap between the blanking hopper (5) and the second bin body (12) gradually decreases from bottom to top.
7. The powder separator for coal mill according to claim 1, wherein, A sealing ring is arranged at the connection between the buffer bin (4) and the pulverized coal separator (2).