Device and method for improving air inlet uniformity of mill inlet air ring and cooperatively scraping pebble coal

Abstract

The invention discloses a device and a method for improving the air inlet uniformity of an air ring at a mill inlet and cooperatively scraping pebble coal. The device comprises a special-shaped rotating shaft, a movable scraping plate, a shaft sealing piece and an angle driving execution mechanism, the two ends of the special-shaped rotating shaft are cylindrical; one end of the movable scraping plate is provided with a sliding groove, and the other end of the movable scraping plate is a free end; the special-shaped rotating shaft penetrates through the sliding groove, the two ends of the special-shaped rotating shaft penetrate out of the two sides of the horizontal section connector air duct correspondingly, and shaft sealing pieces are arranged at the intersections of the special-shaped rotating shaft and the two sides of the horizontal section connector air duct correspondingly. The special-shaped rotating shaft cannot rotate in the sliding chute, but can slide in the sliding chute; one end of the special-shaped rotating shaft is connected with an angle driving executing mechanism, the angle driving executing mechanism drives the special-shaped rotating shaft to rotate and drives the movable scraper to rotate, and when the free end of the movable scraper rotates to the bottom of the horizontal section connector air duct, the free end of the movable scraper makes contact with the bottom of the horizontal section connector air duct. The air inlet uniformity of the mill inlet air ring is improved, pebble coal scraping is promoted synergistically, and the effect is remarkable.

Description

Technical Field

[0001] The invention relates to a device and a method for improving the uniformity of air inlet to a mill inlet air ring and coordinating the scraping of pebble coal, belonging to the field of coal mills in coal-fired power plants. Background Art

[0002] The coal mill is one of the most critical auxiliary equipment in a coal-fired power plant. Its operating condition directly impacts the safe and economical operation of the boiler. It is also one of the largest power consumers in a power plant. Based on the operating speed, coal mills in power plants can be roughly divided into three types: high-speed mills, such as fan mills; medium-speed mills, such as pan mills, ball mills, and bowl mills; and low-speed mills, such as drum-type ball mills. Generally, drum-type ball mills are used in intermediate storage silo-type coal pulverizing systems, while other types of mills are used in direct-fired pulverizing systems.

[0003] Most modern large-scale power station boilers use direct-blowing 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 domestic thermal power plants currently use 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 consists of a rotating grinding ring driven by the drive unit and three fixed, rotatable grinding rollers that roll along the 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 through a coal drop pipe onto the rotating grinding ring. The centrifugal force of the rotating grinding ring throws the raw coal onto the grinding raceway, where it is ground by the grinding rollers. The raw coal is ground and dried simultaneously. High-temperature primary air enters the rotating grinding ring through the mill inlet air ring, drying the coal powder mixture tangentially ejected from the grinding ring and conveying it to the coarse powder separator above it. Pebble coal passes through the mill inlet air ring and falls into the mill inlet air chamber. The pebble coal scraper then moves it through the pebble coal discharge port into the pebble coal bin. The pulverized coal mixture is separated into fine powder and coarse powder under the action of the coarse powder separation baffle. The qualified fine powder is carried into the furnace by the primary air for combustion, and the coarse powder returns from the bottom of the cone shell to the rotating grinding ring for re-grinding under the action of its own gravity.

[0005] The above-mentioned mill inlet air chamber has a single-sided air intake and limited space. The air intake of the mill inlet air ring is extremely uneven. The pebble coal cannot be discharged normally in the area with large air intake, resulting in more serious wear of components such as the grinding roller and grinding raceway, and a significant increase in the power consumption of the coal mill. In the area with small air intake, some coal blocks may also fall into the mill inlet air chamber through the mill inlet air ring and be mistakenly discharged into the pebble coal box as pebble coal.

[0006] In addition, during the operation of the above-mentioned coal mill, the stones falling from the mill inlet air ring may not fall completely into the stone coal box, and some of them may fall or be ejected onto the horizontal section interface air duct at the mill inlet, resulting in increased resistance at the mill inlet and uncertainty in the uniformity of the mill inlet air ring air intake, which may cause the uniformity of the mill inlet air ring air intake to deteriorate. Summary of the Invention

[0007] In order to improve the uniformity of the air inlet of the mill air ring, the present invention provides a device and method for improving the uniformity of the air inlet of the mill air ring and coordinating the scraping of stone coal.

[0008] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0009] A device for improving the uniformity of air inlet to the mill inlet air ring and scraping off pebble coal is installed on the horizontal section interface air duct of the mill inlet. The device for improving the uniformity of air inlet to the mill inlet air ring and scraping off pebble coal comprises a special-shaped rotating shaft, a movable scraper, a shaft seal and an angle drive actuator.

[0010] Both ends of the special-shaped rotating shaft are cylindrical, and there is a special-shaped structure between the two ends of the special-shaped rotating shaft;

[0011] The movable scraper is located inside the horizontal section interface air duct, with a slide groove at one end and a free end at the other end;

[0012] The special-shaped rotating shaft passes through the chute, and the ends of the special-shaped rotating shaft respectively pass through the side walls on both sides of the horizontal section interface air duct. Shaft seals are respectively provided at the intersections of the special-shaped rotating shaft and the two sides of the horizontal section interface air duct; the special-shaped rotating shaft cannot rotate in the chute, but the movable scraper can slide freely on the special-shaped rotating shaft within the length of the chute;

[0013] One end of the special-shaped rotating shaft outside the horizontal section interface air duct is connected to the angle drive actuator, and the angle drive actuator drives the special-shaped rotating shaft to rotate. The rotation of the special-shaped rotating shaft will drive the movable scraper to rotate. When the free end of the movable scraper rotates to the bottom of the horizontal section interface air duct, the free end of the movable scraper contacts the bottom of the horizontal section interface air duct.

[0014] The above-mentioned special-shaped rotating shaft has a special-shaped structure except for the two ends which are cylindrical.

[0015] The above-mentioned special-shaped rotating shaft cannot rotate in the chute (that is, the special-shaped rotating shaft cannot rotate relative to the chute), but can slide freely along the length direction of the chute, so as to ensure that the rotation of the special-shaped rotating shaft will drive the movable scraper to rotate, and under the action of gravity and resistance, the movable scraper can slide freely on the special-shaped rotating shaft (in the length direction and length range of the chute), which can not only sweep the stone coal at the bottom of the horizontal section interface air duct back to the mill inlet air chamber, but also prevent jamming.

[0016] The movable scraper of the above device guides and equalizes the air entering the mill inlet air ring, and at the same time helps to scrape off the stones and coal in the horizontal section interface air duct.

[0017] As one of the specific implementation solutions, two parallel sliding surfaces are provided between the two end portions of the special-shaped rotating shaft. The two sliding surfaces are in contact with the two sides of the sliding groove respectively and slide freely along the length direction of the sliding groove.

[0018] In order to facilitate manufacturing, the ends of the special-shaped rotating shaft are in a regular quadrangular prism or regular hexagonal prism structure.

[0019] In order to facilitate assembly and ensure sealing, the intersections between the two ends of the special-shaped shaft and the horizontal section interface air duct and the exit parts are all cylindrical.

[0020] In order to facilitate maintenance and extend service life, the shaft seal is located on the outside of the horizontal section interface air duct.

[0021] The direction from the chute to the free end of the movable scraper is considered the length direction of the movable scraper. In order to meet general use requirements, the length of the chute is 1 / 3 to 1 / 2 of the length of the movable scraper. The length direction of the chute is consistent with the length direction of the movable scraper.

[0022] To improve the uniformity of the mill inlet air ring and the effectiveness of scraping away pebble coal, the width of the movable scraper is aligned with the width of the horizontal section interface air duct, and the width of the movable scraper extends throughout the width of the horizontal section interface air duct. In other words, the width of the movable scraper is essentially the same as the width of the horizontal section interface air duct, with 5 to 10 mm of rotational space reserved at both ends.

[0023] A method for improving the uniformity of air inlet to the mill inlet air ring and cooperating in scraping off pebbles and coal is realized by using the above-mentioned device for improving the uniformity of air inlet to the mill inlet air ring and cooperating in scraping off pebbles and coal. The angle drive actuator drives the special-shaped rotating shaft to rotate, and then drives the movable scraper to rotate. When the free end of the movable scraper rotates downward, the movable scraper slides downward within the length of the slide groove relative to the special-shaped rotating shaft. When the free end of the movable scraper contacts the bottom of the horizontal section interface air duct, the movable scraper slides upward within the length of the slide groove relative to the special-shaped rotating shaft under the action of resistance, so that the free end of the movable scraper just contacts the bottom of the horizontal section interface air duct, and under the action of rotation, the pebbles and coal at the bottom of the horizontal section interface air duct are swept back to the mill inlet air chamber; the movable scraper also plays the role of diversion, and improves the uniformity of air inlet to the mill inlet air ring while the movable scraper rotates.

[0024] Generally, the flow velocity is higher on the side away from the air inlet, and the air uniformity can be effectively improved after being guided by the movable scraper.

[0025] The technologies not mentioned in this invention are all referred to the prior art.

[0026] The present invention provides a device and method for improving the uniformity of the air inlet to the mill air ring and collaboratively scraping off pebble coal. Through the rotation of a movable scraper, the device and method guide and homogenize the air inlet to the mill air ring and remove pebble coal in the horizontal section interface air duct, thereby avoiding the increase in resistance caused by the accumulation of pebble coal in the horizontal section interface air duct. The device and method improve the uniformity of the air inlet to the mill air ring and collaboratively scrape off pebble coal, with significant effects, extending the service life of the equipment and improving the utilization rate of coal. The device and method also have a simple and reasonable structure and are easy to modify and maintain. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the device for improving the uniformity of the air inlet ring of the mill inlet and coordinating the removal of stone coal;

[0028] Figure 2 This is a schematic diagram of the operation of the device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to the present invention;

[0029] Figure 3 For the present invention Figure 2 Schematic diagram of the AA section;

[0030] Figure 4 Schematic diagram of the flow field before and after the transformation of the present invention (a is the flow field before the transformation, b is the schematic diagram after the transformation, and c is the flow field after the transformation);

[0031] In the figure, 1 is the horizontal section interface air duct, 2 is the angle drive actuator, 3 is the special-shaped rotating shaft, 4 is the shaft seal, 5 is the movable scraper, 6 is the chute, 7 is the mill inlet air ring, 8 is the mill inlet air chamber, 9 is the pebble coal scraper, 10 is the pebble coal, 11 is the pebble coal discharge port, and 12 is the pebble coal box. m is the width direction. DETAILED DESCRIPTION

[0032] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0033] Example 1

[0034] like Figure 1-3 As shown, a device for improving the uniformity of air inlet to the mill inlet air ring and scraping off pebble coal is installed on the horizontal interface air duct of the mill inlet. The device for improving the uniformity of air inlet to the mill inlet air ring and scraping off pebble coal comprises a special-shaped rotating shaft, a movable scraper, a shaft seal and an angle drive actuator.

[0035] Both ends of the special-shaped rotating shaft are cylindrical, and there is a special-shaped structure between the two ends of the special-shaped rotating shaft;

[0036] The movable scraper is located inside the horizontal section interface air duct, with a slide groove at one end and a free end at the other end;

[0037] The special-shaped rotating shaft passes through the chute, and the ends of the special-shaped rotating shaft respectively pass through the side walls on both sides of the horizontal section interface air duct. Shaft seals are respectively provided at the intersections of the special-shaped rotating shaft and the two sides of the horizontal section interface air duct; the special-shaped rotating shaft cannot rotate in the chute, but the movable scraper can slide freely on the special-shaped rotating shaft within the length of the chute;

[0038] One end of the special-shaped rotating shaft outside the horizontal section interface air duct is connected to the angle drive actuator, and the angle drive actuator drives the special-shaped rotating shaft to rotate. The rotation of the special-shaped rotating shaft will drive the movable scraper to rotate. When the free end of the movable scraper rotates to the bottom of the horizontal section interface air duct, the free end of the movable scraper contacts the bottom of the horizontal section interface air duct.

[0039] like Figure 2 As shown, a method for improving the uniformity of the air inlet of the mill inlet air ring and cooperating in scraping off the pebble coal is implemented by using the above-mentioned device for improving the uniformity of the air inlet of the mill inlet air ring and cooperating in scraping off the pebble coal. The angle drive actuator drives the special-shaped rotating shaft to rotate, and then drives the movable scraper to rotate. When the free end of the movable scraper rotates downward, the movable scraper slides downward within the length of the slide groove relative to the special-shaped rotating shaft. When the free end of the movable scraper contacts the bottom of the horizontal section interface air duct, the movable scraper slides upward within the length of the slide groove relative to the special-shaped rotating shaft under the action of resistance, so that the free end of the movable scraper just contacts the bottom of the horizontal section interface air duct, and under the action of rotation, the pebble coal at the bottom of the horizontal section interface air duct is swept back to the mill inlet air chamber; the movable scraper also plays the role of diversion, and improves the uniformity of the air inlet of the mill inlet air ring while the movable scraper rotates.

[0040] The movable scraper of the above device guides and equalizes the air entering the mill inlet air ring, and at the same time helps to scrape off the stones and coal in the horizontal section interface air duct.

[0041] Example 2

[0042] Based on Example 1, the following improvements are further made: two parallel sliding surfaces are provided between the two end portions of the special-shaped rotating shaft, and the two sliding surfaces are in contact with the two sides of the slide groove respectively and slide freely along the length direction of the slide groove. In this example, the two end portions of the special-shaped rotating shaft are formed into a regular quadrangular prism structure, and of course a regular hexagonal prism structure can also be used.

[0043] Example 3

[0044] Based on Example 2, the following improvements were made: To facilitate assembly and ensure sealing, the intersections of both ends of the special-shaped shaft with the horizontal section interface air duct and the exit portion are cylindrical. To facilitate maintenance and extend service life, the shaft seal is located on the outside of the horizontal section interface air duct.

[0045] Example 4

[0046] Based on Example 3, the following improvements were made: the length of the movable scraper from the chute to the free end was considered the length of the movable scraper. To meet general usage requirements, the chute length was set to 0.4 times the length of the movable scraper. To further improve the uniformity of the air inlet ring and the effectiveness of scraping away pebble coal, the width of the movable scraper was aligned with the width of the horizontal section interface air duct, and the width of the movable scraper extended throughout the width of the horizontal section interface air duct. In other words, the width of the movable scraper was essentially the same as the width of the horizontal section interface air duct, with 5mm of rotational space reserved at both ends. Figure 4 The figure is a schematic diagram of the flow field before and after the transformation using this solution. It can be seen from the figure that the uniformity of the air entering the mill inlet air ring is significantly improved after adopting this solution.

[0047] The devices and methods for improving the uniformity of the air inlet to the mill air ring and collaboratively scraping off pebbles and coal in the above-mentioned examples, through the rotation of the movable scraper, guide and homogenize the air inlet to the mill air ring, while removing the pebbles and coal in the horizontal section interface air duct, avoiding the increase in resistance caused by the accumulation of pebbles and coal in the horizontal section interface air duct, improving the uniformity of the air inlet to the mill air ring and scraping off the pebbles and coal, and promoting the synergistic effect, with significant results; and the structure is simple and reasonable, and easy to modify and maintain.

Claims

1. A device for improving the uniformity of air inlet to the mill inlet air ring and scraping off pebble coal, characterized by: The device is installed on the horizontal interface air duct of the coal mill inlet to improve the uniformity of the air inlet of the mill inlet air ring and to scrape away the stone coal. It includes a special-shaped rotating shaft, a movable scraper, a shaft seal and an angle drive actuator. Both ends of the special-shaped rotating shaft are cylindrical, and there is a special-shaped structure between the two ends of the special-shaped rotating shaft; The movable scraper is located inside the horizontal section interface air duct, with a slide groove at one end and a free end at the other end; The special-shaped rotating shaft passes through the chute, and the ends of the special-shaped rotating shaft respectively pass through the side walls on both sides of the horizontal section interface air duct. Shaft seals are respectively provided at the intersections of the special-shaped rotating shaft and the two sides of the horizontal section interface air duct; the special-shaped rotating shaft cannot rotate in the chute, but the movable scraper can slide freely on the special-shaped rotating shaft within the length of the chute; One end of the special-shaped rotating shaft outside the horizontal section interface air duct is connected to the angle drive actuator, and the angle drive actuator drives the special-shaped rotating shaft to rotate. The rotation of the special-shaped rotating shaft will drive the movable scraper to rotate. When the free end of the movable scraper rotates to the bottom of the horizontal section interface air duct, the free end of the movable scraper contacts the bottom of the horizontal section interface air duct.

2. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1, characterized in that: The movable scraper guides the air and evens out the air from the air ring at the mill inlet, while simultaneously scraping away the pebbles and coal in the horizontal section interface air duct.

3. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: Two parallel sliding surfaces are provided between the two end portions of the special-shaped rotating shaft. The two sliding surfaces are in contact with the two sides of the sliding groove respectively and slide freely along the length direction of the sliding groove.

4. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The ends of the special-shaped rotating shaft are separated by a regular quadrangular prism structure.

5. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The ends of the special-shaped rotating shaft are separated by a regular hexagonal prism structure.

6. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The intersections of both ends of the special-shaped rotating shaft and the horizontal section interface air duct and the passing-through parts are all cylindrical.

7. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The shaft seal is arranged on the outside of the horizontal section interface air duct.

8. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The direction from the chute to the free end of the movable scraper is regarded as the length direction of the movable scraper, and the length of the chute is 1 / 3 to 1 / 2 of the length of the movable scraper.

9. The device for improving the uniformity of air inlet to the mill inlet air ring and coordinating the removal of pebble coal according to claim 1 or 2, characterized in that: The width direction of the movable scraper is consistent with the width direction of the horizontal section interface air duct, and the width of the movable scraper runs through the width of the horizontal section interface air duct.

10. A method for improving the uniformity of air inlet to a mill inlet air ring and coordinating the removal of pebble coal, implemented using the device for improving the uniformity of air inlet to a mill inlet air ring and coordinating the removal of pebble coal according to any one of claims 1 to 9, characterized in that: The angle drive actuator drives the special-shaped rotating shaft to rotate, and then drives the movable scraper to rotate. When the free end of the movable scraper rotates downward, the movable scraper slides downward within the length of the slide groove relative to the special-shaped rotating shaft. When the free end of the movable scraper contacts the bottom of the horizontal section interface air duct, the movable scraper slides upward within the length of the slide groove relative to the special-shaped rotating shaft under the action of resistance, so that the free end of the movable scraper just contacts the bottom of the horizontal section interface air duct, and under the action of rotation, the stone coal at the bottom of the horizontal section interface air duct is swept back to the mill inlet air chamber; the movable scraper also plays the role of diversion, and when the movable scraper rotates, the air inlet uniformity of the mill inlet air ring is improved.

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