Return powder secondary separation device for medium-speed coal mill of thermal power plant

Abstract

The utility model relates to the technical field of coal mills, in particular to a returned powder secondary separation device of a medium-speed coal mill in a thermal power plant, which is characterized in that a fine powder separator for separating coarse coal from fine coal is arranged on the left side of a coarse powder separator, and a powder return hole for discharging the fine coal is formed in the top end of the fine powder separator; a filter screen used for isolating coarse coal is arranged in a hole cavity of the powder return hole, and a sweeping plate used for sweeping the filter screen is fixedly installed at the top end of the connecting rod. Hot air is introduced into the coal mill body through the ventilation pipe, coarse powder and fine powder in the coal milling device can fly away to the fine powder separator and the coarse powder separator, under the action of gravity, the coarse powder can slide downwards, 50-60% of return powder is discharged out of the powder outlet pipe along the filter screen and the powder return hole, and meanwhile, the connecting rod rotates under the rotation of the grinding disc, so that the coal milling device is driven to rotate. Therefore, the cleaning plate can be used for cleaning along the bottom of the filter screen, so that the situation that fine pulverized coal cannot be quickly discharged to the pulverized coal outlet pipe along the pulverized coal return hole due to the fact that coarse pulverized coal is adsorbed on the filter screen is prevented.

Description

Technical Field

[0001] The utility model relates to the technical field of coal mills, in particular to a secondary separation device for reclaimed powder of a medium-speed coal mill in a thermal power plant. Background Art

[0002] When coal is burned in a thermal power plant, in order to maintain the efficient combustion of coal, a coal mill is needed to grind the coal. At present, medium-speed coal mills are generally configured in coal-fired units. The powder output capacity of the medium-speed coal mill directly affects the load-carrying capacity of the unit. The ability of the medium-speed coal mill to grind qualified pulverized coal is jointly determined by the grinding output of the coal mill itself and the efficiency of the coarse powder separator. For example, as shown in a medium-speed roller coal mill with the Chinese patent application number CN202122641490.1, two crushing rollers are symmetrically and horizontally rotatably connected in the shell through a rotating shaft. The two crushing rollers are driven by an external motor to rotate synchronously and reversely. The characteristics are that a rotating seat is rotatably sleeved on the rotating shaft, a transition section is arranged on the rotating seat, a collecting section is arranged at one end of the transition section facing the outside of the shell, an arc section extending upward is arranged on the collecting section, a storage space is formed among the arc section, the collecting section and the transition section, and the arc section is driven by a driving device to rotate along the axial direction of the rotating shaft so that the two arc sections swing upward.

[0003] However, the existing medium-speed coal mills are all equipped with coarse powder separators, whose function is to sort the pulverized coal ground by the coal mill according to the particle size. The qualified pulverized coal is sent to the furnace for combustion, and the unqualified pulverized coal is sent back to the coal mill for continuous grinding. However, due to structural reasons, the coarse powder separator inevitably returns a part of the pulverized coal with qualified particle size as reclaimed powder to the medium-speed coal mill through the reclaimed powder collecting hopper for re-grinding, resulting in problems such as low separation efficiency of the coarse powder separator, high circulating ratio of the coal mill, and high coal grinding power consumption. Summary of the Utility Model

[0004] In order to solve the problem that inevitably a part of the pulverized coal with qualified particle size is returned as reclaimed powder to the medium-speed coal mill through the reclaimed powder collecting hopper for re-grinding, resulting in low separation efficiency of the coarse powder separator, high circulating ratio of the coal mill, and high coal grinding power consumption as mentioned in the above background art, the utility model provides the following technical solutions:

[0005] A secondary separation device for reclaimed powder of a medium-speed coal mill in a thermal power plant includes a coal mill body. A coal grinding device for grinding coal is arranged in the coal mill body. An adjusting device for adjusting the up-and-down movement of the coal grinding device is arranged in the coal mill body. A cleaning device for cleaning the coarse coal in the coal mill body is arranged in the coal mill body.

[0006] At the top of the coal mill body, there is a coarse powder separator for absorbing coarse coal and fine coal. On the left side of the coarse powder separator, there is a fine powder separator for separating coarse coal and fine coal. At the top of the fine powder separator, there is a return powder hole for discharging fine coal, and a filter screen for isolating coarse coal is arranged in the cavity of the return powder hole.

[0007] The coal grinding device includes a coal grinding component arranged in the coal mill body for grinding coal. Below the coal grinding component, there is a rotating component for grinding coal together with the coal grinding component. On the left side of the rotating component, there is a driving component for driving the rotating component to rotate. At the bottom end of the coal mill body, a protective cylinder for protecting the rotating component is fixedly installed.

[0008] Furthermore, the driving component includes a rotating shaft movably connected to the cylinder body of the protective cylinder. At the left end of the rotating shaft, a motor for driving the rotating shaft to rotate is fixedly installed. At the right end of the rotating shaft, a first bevel gear for meshing with the rotating component is fixedly installed.

[0009] Furthermore, the rotating component includes a rotating shaft movably connected to the protective cylinder. On the shaft body of the rotating shaft, a second bevel gear for meshing with the first bevel gear is arranged. At the top end of the rotating shaft, a grinding disc for cooperating with the coal grinding component to grind coal is fixedly installed. At the bottom end of the grinding disc, a scraper for discharging impurities in the coal is fixedly installed.

[0010] Furthermore, the coal grinding component includes grinding rollers for cooperating with the grinding disc to grind coal. On the outer side of the grinding rollers, there are support frames for supporting the grinding rollers. At the top end of the support frames, a connecting plate for supporting the support frames is fixedly installed, and the connecting plate is connected to the adjusting device.

[0011] Furthermore, the adjusting device includes an adjusting plate fixedly connected to the connecting plate. At the bottom end of the adjusting plate, a hydraulic rod for driving the adjusting plate to move up and down is arranged.

[0012] Furthermore, the cleaning device includes a connecting rod fixedly installed at the top end of the grinding disc. At the top end of the connecting rod, a cleaning plate for cleaning the filter screen is fixedly installed.

[0013] Furthermore, a slag discharge port for discharging impurities in the coal is arranged at the bottom of the coal mill body.

[0014] Furthermore, a ventilation pipe for introducing hot air into the coal mill body is arranged on the outer side of the coal mill body. Below the ventilation pipe, there is a slag storage tank for collecting impurities in the slag discharge port. An outlet pipe for adding coal to the grinding disc is arranged at the top end of the coal mill body. A coal dropping pipe for connecting with the return powder hole is arranged at the top end of the coal mill body.

[0015] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0016] By providing a coarse powder separator, a fine powder separator, a filter screen and a cleaning device, when hot air needs to be introduced into the coal mill body through the ventilation pipe, the coarse powder and fine powder in the coal grinding device will fly towards the fine powder separator and the coarse powder separator. Under the action of gravity, the coarse powder will slide downwards, and 50-60% of the returned powder is led out along the filter screen and the powder return hole, and then introduced into the upward main air flow boundary of the coal mill through the powder outlet pipe, and slides down into the main air flow by its own weight. The qualified coal powder does not need to be mixed with the raw coal falling from the coal dropping pipe and falls back into the coal grinding device for rolling; a powder return hole for discharging fine coal is provided at the top of the fine powder separator, and the powder return hole is connected to the coal dropping pipe; a filter screen for isolating coarse coal is provided in the cavity of the powder return hole to prevent larger coarse coal powder from being discharged into the powder outlet pipe through the powder return hole. At the same time, when the connecting rod rotates with the grinding disc, the cleaning plate can clean along the bottom of the filter screen to prevent the coarse coal powder from adsorbing on the filter screen, resulting in the slow discharge of fine coal powder along the powder return hole into the powder outlet pipe. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the overall structure of the present utility model;

[0018] Figure 2 is a sectional view of the coal mill body of the present utility model;

[0019] Figure 3 is a front sectional view of the coal mill body of the present utility model;

[0020] Figure 4 is a schematic diagram of the structure of the coal grinding device of the present utility model;

[0021] Figure 5 is a schematic diagram of the structure of the adjusting device of the present utility model;

[0022] Figure 6 is a schematic diagram of the structure of the cleaning device of the present utility model.

[0023] In the drawings, the list of component names represented by each reference numeral is as follows:

[0024] 100 - coal mill body, 101 - slag discharge port, 102 - coarse powder separator, 103 - fine powder separator, 104 - filter screen, 105 - powder return hole;

[0025] 200 - Coal grinding device, 210 - Driving assembly, 211 - Motor, 212 - Rotating shaft, 213 - First bevel gear, 220 - Rotating assembly, 221 - Rotating shaft, 222 - Second bevel gear, 223 - Grinding table, 224 - Scraper, 230 - Coal grinding assembly, 231 - Grinding roller, 232 - Support frame, 233 - Connecting plate, 240 - Protection cylinder;

[0026] 300 - Adjusting device, 310 - Hydraulic rod, 320 - Tripod;

[0027] 400 - Cleaning device, 410 - Connecting rod, 420 - Cleaning plate;

[0028] 001 - Slag storage tank, 002 - Ventilation pipe, 003 - Coal dropping pipe, 004 - Powder outlet pipe. Specific embodiments

[0029] The following describes in detail the preferred specific embodiments for implementing the present utility model, and a clear and complete description is made in combination with the accompanying drawings.

[0030] Please refer to Figures 1-6 , the present utility model provides a secondary separation device for recycled powder of a medium - speed coal mill in a thermal power plant.

[0031] It includes a coal mill body 100. Inside the coal mill body 100, there is a coal grinding device 200 for grinding coal. Inside the coal mill body 100, there is an adjusting device 300 for adjusting the up - and - down movement of the coal grinding device 200. Inside the coal mill body 100, there is a cleaning device 400 for cleaning the coarse coal inside the coal mill body 100.

[0032] On the outside of the coal mill body 100, there is a ventilation pipe 002 for introducing hot air into the coal mill body 100. Hot air can be introduced into the coal mill body 100 through the ventilation pipe 002 to facilitate the upward spiral movement of the fine and coarse coal powder generated in the coal grinding device 200. Below the ventilation pipe 002, there is a slag storage tank 001 for collecting impurities in the slag discharge port 101, so that the impurities generated in the coal grinding device 200 can be discharged from the slag discharge port 101 into the slag storage tank 001 for centralized collection and treatment. At the top of the coal mill body 100, there is a powder outlet pipe 004 for adding coal onto the grinding table 223, so as to discharge the fine coal powder generated in the coal grinding device 200 from the powder outlet pipe 004. At the top of the coal mill body 100, there is a coal dropping pipe 003 for connecting with the powder return hole 105. Coal can be added to the coal grinding device 200 through the coal dropping pipe 003. At the bottom of the coal mill body 100, there is a slag discharge port 101 for discharging impurities in the coal.

[0033] At the top of the coal mill body 100, there is a coarse powder separator 102 for absorbing coarse coal and fine coal. The inner and outer surfaces of the coarse powder separator 102 are lined with anti-wear ceramics to reduce surface wear and extend the service life. The included angle between the coarse powder separator 102 and the coal mill body 100 is less than 40°, so as to ensure that the returned powder entering can flow smoothly to the powder outlet pipe 004.

[0034] On the left side of the coarse powder separator 102, there is a fine powder separator 103 for separating coarse coal and fine coal. Thus, when hot air needs to be introduced into the coal mill body 100 through the ventilation pipe 002, the coarse powder and fine powder in the coal grinding device 200 will fly towards the fine powder separator 103 and the coarse powder separator 102. Under the action of gravity, the coarse powder will slide downwards, and 50 - 60% of the returned powder is led out along the filter screen 104 and the powder return hole 105, and then introduced into the upward main air flow boundary of the coal mill through the powder outlet pipe 004, and slides down into the main air flow by its own weight. The qualified coal powder does not need to be mixed with the raw coal falling from the coal dropping pipe 003 and falls back into the coal grinding device 200 for rolling. At the top of the fine powder separator 103, there is a powder return hole 105 for discharging fine coal, and the powder return hole 105 is connected to the coal dropping pipe 003; inside the cavity of the powder return hole 105, there is a filter screen 104 for isolating coarse coal to prevent larger coarse coal powder from being discharged into the powder outlet pipe 004 through the powder return hole 105.

[0035] The coal grinding device 200 includes a coal grinding component 230 arranged inside the coal mill body 100 for grinding coal. Below the coal grinding component 230, there is a rotating component 220 for grinding coal together with the coal grinding component 230. On the left side of the rotating component 220, there is a driving component 210 for driving the rotating component 220 to rotate. At the bottom end of the coal mill body 100, there is a protective cylinder 240 fixedly installed for protecting the rotating component 220.

[0036] The driving component 210 includes a rotating shaft 212 movably connected to the cylinder body of the protective cylinder 240. At the left end of the rotating shaft 212, there is a motor 211 fixedly installed for driving the rotating shaft 212 to rotate. At the right end of the rotating shaft 212, there is a first bevel gear 213 fixedly installed for meshing with the rotating component 220;

[0037] The rotating component 220 includes a rotating shaft 221 movably connected to the protective cylinder 240 to facilitate the rotation of the rotating shaft 221; on the shaft body of the rotating shaft 221, there is a second bevel gear 222 for meshing with the first bevel gear 213. At the top end of the rotating shaft 221, there is a grinding disc 223 fixedly installed for cooperating with the coal grinding component 230 to grind coal. At the bottom end of the grinding disc 223, there is a scraper 224 fixedly installed for discharging impurities in the coal.

[0038] The coal grinding assembly 230 includes a grinding roller 231 that cooperates with a grinding table 223 to grind coal. A support frame 232 for supporting the grinding roller 231 is arranged on the outer side of the grinding roller 231. A connecting plate 233 for supporting the support frame 232 is fixedly installed at the top end of the support frame 232, and the connecting plate 233 is connected to an adjusting device 300. Thus, when it is necessary to grind the coal falling from the coal dropping pipe 003, the motor 211 can drive the rotating shaft 212 to rotate, so that the grinding table 223 can be rotated. The scraper 224 can rotate synchronously with the grinding table 223, and the impurities in the coal can be collected into the slag storage tank 001 along the slag discharge port 101 by the pushing of the scraper 224. By making the sliding between the rotating grinding table 223 and the grinding roller 231, the coal on the grinding table 223 can be ground.

[0039] The adjusting device 300 includes an adjusting plate 320 fixedly connected to the connecting plate 233. A hydraulic rod 310 for driving the adjusting plate 320 to move up and down is arranged at the bottom end of the adjusting plate 320. Thus, by the up and down movement of the hydraulic rod 310, the grinding roller 231 at the bottom end of the adjusting plate 320 can be driven to approach the top end of the grinding table 223, and corresponding adjustment can be made according to the fineness of different pulverized coal.

[0040] The cleaning device 400 includes a connecting rod 410 fixedly installed at the top end of the grinding table 223. A cleaning plate 420 for cleaning the filter screen 104 is fixedly installed at the top end of the connecting rod 410, so as to prevent the coarse pulverized coal from adsorbing on the filter screen 104, resulting in the fine pulverized coal not being able to quickly discharge to the powder outlet pipe 004 along the powder return hole 105.

[0041] Based on the above content and the drawings, those skilled in the art can understand and implement the present utility model. In addition, any non-creative modifications made to the present utility model by those skilled in the art without making creative efforts still fall within the protection scope of the present utility model.

Claims

1. A secondary separation device for coal powder return of a medium-speed coal mill in a thermal power plant, comprising a coal mill body (100), characterized in that: The coal mill body (100) is provided with a coal grinding device (200) for crushing coal, the coal mill body (100) is provided with an adjusting device (300) for adjusting the up and down movement of the coal grinding device (200), and the coal mill body (100) is provided with a cleaning device (400) for cleaning coarse coal in the coal mill body (100); A coarse powder separator (102) for absorbing coarse coal and fine coal is provided at the top of the coal mill body (100); a fine powder separator (103) for separating coarse coal and fine coal is provided on the left side of the coarse powder separator (102); a powder return hole (105) for discharging fine coal is provided at the top of the fine powder separator (103); a filter screen (104) for isolating coarse coal is provided in the cavity of the powder return hole (105); The coal grinding device (200) comprises a coal grinding assembly (230) arranged in a coal grinding machine body (100) for pulverizing coal, a rotating assembly (220) for pulverizing coal with the coal grinding assembly (230) is arranged below the coal grinding assembly (230), a driving assembly (210) for driving the rotating assembly (220) to rotate is arranged on the left side of the rotating assembly (220), and a protective cylinder (240) for protecting the rotating assembly (220) is fixedly installed at the bottom end of the coal grinding machine body (100).

2. The medium-speed coal mill return secondary separation device for a thermal power plant according to claim 1, characterized in that: The driving assembly (210) comprises a rotating shaft (212) movably connected to the body of the protective cylinder (240); a motor (211) for driving the rotating shaft (212) to rotate is fixedly mounted on the left end of the rotating shaft (212); and a bevel gear 1 (213) for meshing with the rotating assembly (220) is fixedly mounted on the right end of the rotating shaft (212).

3. The medium-speed coal mill return powder secondary separation device for a thermal power plant according to claim 2, characterized in that: The rotating assembly (220) comprises a rotating shaft (221) movably connected to the protective tube (240); a second bevel gear (222) for meshing with a first bevel gear (213) is arranged on the shaft body of the rotating shaft (221); a grinding disc (223) for cooperating with a coal grinding assembly (230) to grind coal is fixedly mounted on the top end of the rotating shaft (221); and a scraper (224) for discharging impurities in the coal is fixedly mounted on the bottom end of the grinding disc (223).

4. The medium-speed coal mill return secondary separation device for a thermal power plant according to claim 3, characterized in that: The coal grinding assembly (230) comprises a grinding roller (231) for cooperating with a grinding disc (223) to grind coal; a support frame (232) for supporting the grinding roller (231) is arranged on the outer side of the grinding roller (231); a connecting plate (233) for supporting the supporting frame (232) is fixedly mounted on the top of the supporting frame (232); and the connecting plate (233) is connected to the adjusting device (300).

5. The medium-speed coal mill return secondary separation device for a thermal power plant according to claim 4, characterized in that: The adjusting device (300) comprises an adjusting plate (320) fixedly connected to the connecting plate (233), and a hydraulic rod (310) for driving the adjusting plate (320) to move up and down is arranged at the bottom end of the adjusting plate (320).

6. The device for secondary separation of coal powder from a medium-speed coal mill in a thermal power plant according to claim 3, characterized in that: The cleaning device (400) comprises a connecting rod (410) fixedly mounted on the top end of the grinding disc (223), and a cleaning plate (420) for cleaning the filter screen (104) is fixedly mounted on the top end of the connecting rod (410).

7. The device for secondary separation of coal powder from a medium-speed coal mill in a thermal power plant according to claim 1, characterized in that: The bottom of the coal mill body (100) is provided with a slag discharge port (101) for discharging impurities in the coal.

8. The device for secondary separation of coal powder from a medium-speed coal mill in a thermal power plant according to claim 7, characterized in that: A ventilation pipe (002) for introducing hot air into the coal mill body (100) is arranged on the outside of the coal mill body (100); a slag storage box (001) for collecting impurities in the slag discharge port (101) is arranged below the ventilation pipe (002); a powder discharge pipe (004) for adding coal to the grinding disc (223) is arranged at the top of the coal mill body (100); and a coal drop pipe (003) for communicating with the powder return hole (105) is arranged at the top of the coal mill body (100).

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