A scraper structure for preventing stone coal from splashing
By designing a V-shaped scraper structure in the coal mill, the problem of increased resistance caused by flying stones and coal was solved, and the uniformity of air intake was improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIANGSU GUOHUACHENJIAGANG POWER GENERATION CO LTD
- Filing Date
- 2025-07-17
- Publication Date
- 2026-06-26
Smart Images
Figure CN224405254U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a scraper structure for preventing stones and coal from splashing, belonging to the technical field of coal mills in coal-fired power plants. Background Technology
[0002] Coal mills are one of the most important auxiliary machines in coal-fired power plants, and their operating status directly affects the safe and economical operation of the boiler. They are also one of the power plant's largest power-consuming auxiliary machines. Based on their operating speed, coal mills in power plants can be broadly classified into three types: high-speed coal mills, such as fan mills; medium-speed coal mills, such as disc mills, ball mills, and bowl mills; and low-speed coal mills, such as cylindrical ball mills. Generally, cylindrical ball mills are mostly used in intermediate storage pulverizing systems, while other types of coal mills are mostly used in direct-fired pulverizing systems.
[0003] Most modern large power plant boilers adopt direct-fired pulverizing systems. Due to the advantages of medium-speed coal mills, such as light weight, small footprint, low investment, low power consumption, low metal wear and low noise, most large thermal power plants in China currently choose medium-speed coal mills.
[0004] A medium-speed coal mill consists of at least three parts: a drive unit, a grinding unit, and a coarse powder separator. The grinding unit typically comprises a rotating grinding ring driven by the drive unit and three fixed, self-rotating grinding rollers that roll along the grinding ring. The coarse powder separator, consisting of a coarse powder separation baffle and a conical shell, is located above the rotating grinding ring. Raw coal falls onto the rotating grinding ring through a chute, and the centrifugal force of the rotating grinding ring propels the raw coal onto the grinding track, where it is ground by the grinding rollers. Grinding and drying of the raw coal occur simultaneously. High-temperature primary air enters the area around the rotating grinding ring through the mill inlet air ring, drying the coal powder mixture tangentially ejected from the rotating grinding ring after grinding and conveying it to the coarse powder separator above it. Stone coal falls into the mill inlet air chamber through the mill inlet air ring, and then, under the action of the stone coal scraper, enters the stone coal box from the stone coal discharge outlet. The coal powder mixture is separated into fine and coarse powder by the coarse powder separation baffle. The qualified fine powder is carried into the furnace by the primary air for combustion, while the coarse powder returns from the bottom of the cone shell to the rotating grinding ring for re-grinding under its own gravity.
[0005] The aforementioned stone and coal scraper is generally a straight plate structure. It automatically rotates circumferentially at the bottom of the mill inlet air chamber, scraping away stones and coal to fall into the stone and coal discharge port and then into the stone and coal box. The mill inlet is generally equipped with a horizontal section of the interface air duct. During rotation, the stone and coal scraper can easily blow stones and coal into this horizontal section, increasing the mill inlet resistance and affecting the uniformity of airflow into the mill inlet air ring. Utility Model Content
[0006] To prevent stones and coal from splashing into the horizontal section of the coal mill inlet air duct, this utility model provides a scraper structure to prevent stones and coal from splashing.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows:
[0008] A scraper structure for preventing stone and coal splashing includes a mill inlet air chamber, a rotating grinding ring, and a scraper body. A rotating shaft is located in the center of the mill inlet air chamber, and the rotating grinding ring is mounted on the rotating shaft. A stone and coal discharge port is located at the bottom of the mill inlet air chamber. The scraper body is located at the bottom of the mill inlet air chamber and below the rotating grinding ring. The scraper body is mounted on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring. The cross-section of the scraper body is V-shaped, with the inner surface of the V-shaped structure facing the rotation direction of the rotating shaft. The maximum distance from the center of the rotating shaft to the stone and coal discharge port is Rmax, and the minimum distance is Rmin. The distance from the center of the rotating shaft to the apex of the V-shaped structure of the scraper body is R, where Rmin < R < Rmax.
[0009] The maximum distance Rmax and minimum distance Rmin from the center of the rotating shaft to the stone and coal discharge outlet refer to the maximum and minimum radial distances from the center of the rotating shaft to the edge of the stone and coal discharge outlet on the same horizontal plane. The radial direction is consistent with the radial direction of the rotating shaft. Rmax - Rmin = the radial width (square) or diameter (circular) of the stone and coal discharge outlet. In this application, Rmin < R < Rmax is set so that when the scraper body passes through the stone and coal discharge outlet, the vertex projection of the V-shaped structure of the scraper body can fall within the stone and coal discharge outlet.
[0010] The inner surface of the aforementioned V-shaped structure faces the direction of rotation of the axis of rotation, and the direction of rotation is consistent with the direction extending outward from the apex of the inner side of the "V".
[0011] During operation, the rotating grinding ring and scraper body rotate under the drive of the rotating shaft.
[0012] Using the above-mentioned device, the gravel and coal falling into the mill inlet air chamber can be collected at the apex of the V-shaped structure of the scraper body, and fall into the gravel and coal box from the gravel and coal discharge port when passing through it. This effectively reduces or avoids the increase in inlet resistance caused by gravel and coal being blown into the horizontal section interface air duct, and improves the uniformity of air intake in the inlet air ring.
[0013] The included angle of the V-shaped structure of the scraper body is preferably 95° to 120°.
[0014] The aforementioned inlet air chamber, rotating grinding ring, etc., are all components of the coal mill. Since they do not involve improvements to other structures of the coal mill, they will not be described in detail.
[0015] To improve the discharge efficiency of gravel and coal, further optimization is performed, with R equal to (Rmax - Rmin) / 2.
[0016] As one specific implementation scheme, the scraper body is composed of a first scraper and a second scraper. One end of the first scraper is installed on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring, and the other end is connected to the second scraper. The joint of the first scraper and the second scraper forms the apex of a V-shaped structure, and the included angle between the first scraper and the second scraper is 95 to 120°.
[0017] For ease of fabrication and to ensure structural strength, the first and second scrapers are welded together.
[0018] As another specific implementation scheme, the scraper body is an integral structure, with one end of the scraper body installed on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring, and the other end bent at 95 to 120 degrees to form a V-shaped structure.
[0019] To balance strength and service life, the scraper body is made of 65 manganese.
[0020] The bottom of the scraper body is in contact with the bottom of the grinding inlet air chamber.
[0021] To balance service life and cost, the thickness of the scraper body is 10-20mm, and the height of the scraper body is 30-60mm.
[0022] To further improve the coal scraping effect, a top plate is provided on the top of the scraper body. One end of the top plate is connected to the top of the scraper body, and the other end is inclined upward at an angle of 10 to 30 degrees with the horizontal plane. The projection of the top plate falls on the inner side of the V-shaped structure. This can block the thrown stones and coal, and at the same time facilitate the stones that fall on the top plate to fall back down.
[0023] The scraper structure mentioned above for preventing stone and coal splashing also includes a stone and coal discharge pipe and a stone and coal box. The stone and coal box is located on the side of the coal mill, and the stone and coal discharge pipe is set at an angle. The top of the stone and coal discharge pipe is connected to the stone and coal discharge port, and the bottom of the stone and coal discharge pipe extends into the stone and coal box.
[0024] Any technologies not mentioned in this utility model are based on existing technologies.
[0025] This utility model relates to a scraper structure for preventing the splashing of stones and coal. Through improved design of the scraper body structure, stones and coal can be effectively collected and discharged when passing through the stone and coal discharge port. This effectively reduces or avoids the increase in inlet resistance caused by stones and coal being blown into the horizontal section interface air duct, and improves the uniformity of air intake of the inlet air ring. The structure is simple, easy to modify, and low in cost. Attached Figure Description
[0026] Figure 1 This is a schematic diagram (top view) of the scraper structure in traditional technology;
[0027] Figure 2 This is a schematic diagram (top view) of the scraper structure for preventing stones and coal from splashing according to this utility model;
[0028] Figure 3 This is a side view of the scraper structure for preventing stones and coal from splashing according to this utility model;
[0029] Figure 4 This is a schematic diagram of the longitudinal section of the scraper body in Example 5.
[0030] In the figure, 1 is the mill inlet air chamber, 2 is the rotating mill ring, 3 is the scraper body, 4 is the rotating shaft, 5 is the stone and coal discharge port, 6 is the roof plate, 7 is the stone and coal discharge pipe, 8 is the stone and coal box, 9 is the stone and coal, and 10 is the horizontal section interface air duct. Detailed Implementation
[0031] To better understand this utility model, the following embodiments further illustrate the content of this utility model, but the content of this utility model is not limited to the following embodiments.
[0032] Example 1
[0033] like Figure 2 As shown, a scraper structure for preventing stone and coal splashing includes a mill inlet air chamber, a rotating grinding ring, and a scraper body. A rotating shaft is located in the center of the mill inlet air chamber, and the rotating grinding ring is mounted on the rotating shaft. A stone and coal discharge port is located at the bottom of the mill inlet air chamber. The scraper body is located at the bottom of the mill inlet air chamber and below the rotating grinding ring. The scraper body is mounted on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring. The cross-section of the scraper body is a V-shaped structure, with the inner surface of the V-shaped structure facing the rotation direction of the rotating shaft. The maximum distance from the center of the rotating shaft to the stone and coal discharge port is Rmax, and the minimum distance is Rmin. The distance from the center of the rotating shaft to the vertex of the V-shaped structure of the scraper body is R, where Rmin < R < Rmax. In this example, R equals (Rmax - Rmin) / 2, and the included angle of the vertex of the V-shaped structure is 100°.
[0034] During operation, the rotating grinding ring and scraper body rotate under the drive of the rotating shaft. Using this device, the stones and coal falling into the mill inlet air chamber are collected at the apex of the V-shaped structure of the scraper body, and then fall into the stone and coal box from the stone and coal discharge port. This effectively reduces or avoids the increase in inlet resistance caused by stones and coal being blown into the horizontal section interface air duct, and improves the uniformity of airflow into the inlet air ring.
[0035] Example 2
[0036] Based on Example 1, the following improvements were made: the plate body is welded together from a first scraper and a second scraper. One end of the first scraper is installed on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring, and the other end is connected to the second scraper. The splice of the first scraper and the second scraper forms the apex of a V-shaped structure, and the included angle between the first scraper and the second scraper is 100°.
[0037] Example 3
[0038] Based on Example 1, the following improvements were made: the plate body is an integral structure, one end of the scraper body is installed on the side wall of the rotating shaft and / or the bottom of the rotating grinding ring, and the other end is bent at 100° to form a V-shaped structure.
[0039] Example 4
[0040] Based on Example 2 or 3, the following improvements were made: the scraper body is made of 65 manganese steel. The bottom of the scraper body contacts the bottom of the grinding mill inlet air chamber. The thickness of the scraper body is 15 mm, and the height of the scraper body is 40 mm.
[0041] Example 5
[0042] Based on Example 4, the following improvements were made: Figure 4 As shown, to further improve the coal scraping effect, a top plate is provided on the top of the scraper body. One end of the top plate is connected to the top of the scraper body, and the other end is inclined upward at an angle of 28° with the horizontal plane. The projection of the top plate falls on the inner side of the V-shaped structure. This can block the thrown coal and stones, and at the same time facilitate the falling of stones that fall on the top plate.
[0043] Example 6
[0044] Based on Example 4 or 5, the following improvements were further made: Figure 3 As shown, the scraper structure to prevent stone and coal from splashing also includes a stone and coal discharge pipe and a stone and coal box. The stone and coal box is located on the side of the coal mill. The stone and coal discharge pipe is set at an angle, with the top of the stone and coal discharge pipe connected to the stone and coal discharge port and the bottom of the stone and coal box.
[0045] The scraper structures described above for preventing the splashing of stones and coal, through improvements in the scraper body structure, can effectively gather stones and coal and discharge them when passing through the stone and coal discharge port. This effectively reduces or avoids the increase in inlet resistance caused by stones and coal being blown into the horizontal section interface air duct, and improves the uniformity of air intake in the inlet air ring. The structure is simple, easy to modify, and inexpensive.
Claims
1. A scraper structure for preventing stone and coal splashing, comprising a mill inlet air chamber (1), a rotating grinding ring (2), and a scraper body (3); a rotating shaft (4) is provided in the center of the mill inlet air chamber (1), and the rotating grinding ring (2) is mounted on the rotating shaft (4); a stone and coal discharge port (5) is provided at the bottom of the mill inlet air chamber (1), and the scraper body (3) is located at the bottom of the mill inlet air chamber (1) and below the rotating grinding ring (2), and the scraper body (3) is mounted on the side wall of the rotating shaft (4) and / or the bottom of the rotating grinding ring (2), characterized in that: The cross-section of the scraper body (3) is V-shaped. The inner side of the V-shaped structure faces the rotation direction of the rotating shaft (4). The maximum distance from the center of the rotating shaft (4) to the stone and coal discharge port (5) is Rmax, and the minimum distance is Rmin. The distance from the center of the rotating shaft (4) to the vertex of the V-shaped structure of the scraper body (3) is R, where Rmin < R < Rmax.
2. The scraper structure for preventing stone and coal splashing as described in claim 1, characterized in that: R equals (Rmax - Rmin) / 2.
3. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The scraper body (3) is formed by splicing the first scraper and the second scraper. One end of the first scraper is installed on the side wall of the rotating shaft (4) and / or the bottom of the rotating grinding ring (2), and the other end is connected to the second scraper. The splice of the first scraper and the second scraper forms the apex of a V-shaped structure. The included angle between the first scraper and the second scraper is 95 to 120°.
4. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The first scraper and the second scraper are welded together.
5. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The scraper body (3) is an integral structure. One end of the scraper body (3) is installed on the side wall of the rotating shaft (4) and / or the bottom of the rotating grinding ring (2), and the other end is bent at 95 to 120 degrees to form a V-shaped structure.
6. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The scraper body (3) is made of 65 manganese.
7. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The bottom of the scraper body (3) contacts the bottom of the grinding inlet air chamber (1).
8. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The thickness of the scraper body (3) is 10-20 mm, and the height of the scraper body (3) is 30-60 mm.
9. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: The scraper body (3) is provided with a top plate (6) at the top. One end of the top plate (6) is connected to the top of the scraper body (3), and the other end is inclined upward at an angle of 10 to 30° with the horizontal plane. The projection of the top plate (6) falls on the inner side of the V-shaped structure.
10. The scraper structure for preventing stone and coal splashing as described in claim 1 or 2, characterized in that: It also includes a stone coal discharge pipe (7) and a stone coal box (8). The stone coal box (8) is located on the side of the coal mill. The stone coal discharge pipe (7) is set at an angle. The top of the stone coal discharge pipe (7) is connected to the stone coal discharge port (5), and the bottom is connected to the stone coal box (8).