Device for sealing base of medium-speed coal mill

Abstract

According to the device for sealing the base of the medium-speed coal mill, the medium-speed coal mill comprises a lower frame body, a sealing shell is arranged on the upper portion of the lower frame body, and a transmission disc and a transmission shaft are arranged in the lower frame body and the sealing shell; comprising a lower sealing structure and an upper sealing structure which are sequentially arranged on a transmission shaft in a sleeving mode from bottom to top on the medium-speed coal mill, and a sealing cavity is formed among a sealing shell, the lower sealing structure, the upper sealing structure and the transmission shaft; the negative pressure of the driving disc sealing system is maintained through the negative pressure suction device, the collected mixture is discharged into the coal mill shell, and therefore air powder is prevented from overflowing, it is guaranteed that a machine base is sealed and free of leakage, 14-17 kPa sealing air is adopted as a power steam source to eject the driving disc sealing system, the driving disc sealing system is ejected to be a negative pressure system, and leakage of hot air and ash powder is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of coal mills, and more specifically to a solution for the base sealing device of a medium-speed coal mill. Background Art

[0002] During the operation of a medium-speed coal mill, the sealing ring part of the carbon graphite base of the mill's drive disc is prone to wear, damage, air leakage, and powder leakage. Moreover, with the passage of time, the wear becomes increasingly severe, and a large amount of pebble coal spurts out from the joint between the bottom of the drive disc and the base, with sparks flying everywhere, resulting in deep grooves being worn out at the joint between the output flange and the mechanical seal, which are not easy to repair. At the same time, high-temperature hot air and ash powder leak from the drive disc part, easily causing the aging of oil pipe components and threatening the safe operation of the coal mill's oil system.

[0003] The sealing system of the coal mill's drive disc consists of two parts: the seal between the base seal ring and the drive disc and the seal between the drive disc and the carbon graphite base seal ring, forming a relatively enclosed space. The sealed air boosted by the sealed air blower is used to flush the drive disc sealing system to prevent the primary hot air from leaking into the drive disc sealing system. The labyrinth carbon graphite base seal ring is installed in the sealed chamber. When the wear of the carbon graphite ring is not serious, it ensures that the surface of the drive disc and the inner side of the labyrinth carbon graphite base seal ring are always in close contact during the operation of the coal mill. Since the pressure difference ΔP between the sealed air and the primary air is ≥ 2 kPa, this can prevent the primary hot air and pulverized coal in the primary air chamber from leaking through the gap between the drive disc and the base. However, when the carbon graphite ring wears, hot air and a mixture of ash powder will leak. Summary of the Invention

[0004] One advantage of the utility model is to provide a solution for the base sealing device of a medium-speed coal mill. By means of a negative pressure suction device, the drive disc sealing system is maintained at a negative pressure, and the collected mixture is discharged into the coal mill housing, thereby preventing the overflow of air and powder and ensuring that the base seal does not leak.

[0005] One advantage of the utility model is to provide a solution for the base sealing device of a medium-speed coal mill. Using 14 - 17 kPa sealed air as the power steam source to eject the drive disc sealing system, the drive disc sealing system is ejected into a negative pressure system to avoid the leakage of hot air and ash powder.

[0006] One advantage of the utility model is to provide a solution for the base sealing device of a medium-speed coal mill. The pressure of the mixture in the return air pipe needs to be higher than the pressure of the coal mill body to ensure that the mixture completely enters the coal mill without overflowing, thus preventing the leakage of the primary air and dust in the primary air chamber to the outside and improving the environment around the coal mill.

[0007] One advantage of the utility model is to provide a solution for the base sealing device of a medium-speed coal mill, which can prevent the leakage of the primary air and dust in the primary air chamber to the outside and improve the environment around the coal mill.

[0008] To achieve at least one of the above advantages of the present utility model, the present utility model provides a solution for the base sealing device of a medium-speed coal mill. The medium-speed coal mill includes a lower frame body, and a sealing housing is arranged on the upper part of the lower frame body. A driving disc and a transmission shaft are arranged inside the lower frame body and the sealing housing; it includes a lower sealing structure and an upper sealing structure that are sequentially sleeved on the transmission shaft from bottom to top on the medium-speed coal mill. A sealed chamber is formed among the sealing housing, the lower sealing structure, the upper sealing structure and the transmission shaft;

[0009] A sealed air pipeline is connected to the lower frame body of the coal mill. The sealed air pipeline is communicated with the sealed chamber. A butterfly valve is arranged in the middle of the sealed air pipeline and divides the sealed air pipeline into a front section of the pipeline and a rear section of the pipeline. A negative pressure pipe is connected to the front section of the pipeline, and a gas source pipe is connected to the rear section of the pipeline. The upper end of the gas source pipe is connected to a negative pressure chamber and a nozzle. The nozzle is located inside the negative pressure chamber. The upper end of the negative pressure chamber is connected to a pressure stabilizing pipe. The upper end of the pressure stabilizing pipe is connected to a diffuser pipe. The upper end of the diffuser pipe is connected to a return air pipe. The other end of the return air pipe is communicated with the rotary separator of the coal mill; the negative pressure pipe is communicated with the side of the negative pressure chamber.

[0010] According to an embodiment of the present utility model, the lower sealing structure includes a floating seal assembly arranged between the lower frame body and the transmission shaft. The floating seal assembly includes a machine seat seal ring groove and a graphite packing, a support connecting ring and a support spring arranged in the machine seat seal ring groove. The support spring is located below the support connecting ring, and the graphite packing is located above the support connecting ring.

[0011] According to an embodiment of the present utility model, two groups of floating seal assemblies are arranged from top to bottom in total.

[0012] According to an embodiment of the present utility model, the graphite packing is a nickel wire-containing graphite packing with a tightening spring.

[0013] According to an embodiment of the present utility model, the upper sealing structure includes a machine seat seal ring arranged between the lower frame body and the transmission shaft.

[0014] According to an embodiment of the present utility model, a sealed air blower is connected to the rear section of the pipeline. The sealed air blower outputs sealed air of 14 - 17 kPa. The sealed air enters the coal mill after passing through the rear section of the pipeline, the gas source pipe, the air nozzle, the pressure stabilizing pipe, the diffuser pipe and the return air pipe.

[0015] According to an embodiment of the present utility model, the pressure of the sealed air in the return air pipe is greater than the pressure inside the coal mill.

[0016] According to an embodiment of the present utility model, the height of the nozzle is not lower than the height of the connection port between the negative pressure pipe and the negative pressure chamber.

[0017] According to an embodiment of the present utility model, the diffuser pipe is arranged in a horn-shaped structure, and the relatively narrow end of the diffuser pipe is communicated with the pressure stabilizing section.

[0018] According to an embodiment of the present utility model, the diameter of the voltage stabilizing tube is the same as the diameter of the relatively narrow end of the diffuser tube. Description of the Drawings

[0019] Figure 1 It is a structural diagram of the present utility model;

[0020] Figure 2 It is an enlarged view of the lower sealing structure of the present utility model;

[0021] Figure 3 It is a partial enlarged view of the present utility model;

[0022] Among them, the reference numerals are as follows:

[0023] 1, coal mill; 2, drive disk; 3, sealing chamber; 4, negative pressure pipe; 5, gas source pipe; 6, diffuser tube; 7, drive shaft; 8, lower sealing structure, 81, graphite packing; 82, support connection ring; 83, support spring; 9, voltage stabilizing tube; 10, nozzle; 11, butterfly valve; 12, sealing air pipeline; 13, machine base top plate; 14, upper sealing structure; 15, return air duct. Detailed Embodiment

[0024] To make the purpose, technical solution and advantages of the implementation of the present utility model clearer, the following will combine the attached drawings of the present utility model Figure 1 ~Attached Figure 3 , and describe the present utility model in more detail.

[0025] The following description is used to disclose the present utility model so that those skilled in the art can implement the present utility model. The preferred embodiments described below are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description can be applied to other implementation schemes, variant schemes, improvement schemes, equivalent schemes, and other technical schemes that do not deviate from the spirit and scope of the present utility model.

[0026] The utility model provides a base sealing device for a medium-speed coal mill 1. The medium-speed coal mill 1 includes a lower frame body, and a sealing housing is arranged on the upper part of the lower frame body. A driving disc 2 and a transmission shaft 7 are arranged inside the lower frame body and the sealing housing; it includes a lower sealing structure 8 and an upper sealing structure 14 which are sequentially sleeved on the transmission shaft 7 from bottom to top on the medium-speed coal mill 1. A sealing chamber 3 is formed among the sealing housing, the lower sealing structure 8, the upper sealing structure 14 and the transmission shaft 7; a sealing air pipeline 12 is connected to the lower frame body of the coal mill 1, and the sealing air pipeline 12 is communicated with the sealing chamber 3. A butterfly valve 11 is arranged in the middle of the sealing air pipeline 12 and divides the sealing air pipeline 12 into a front pipeline section and a rear pipeline section. A negative pressure pipe 4 is connected to the front pipeline section, and an air source pipe 5 is connected to the rear pipeline section. The upper end of the air source pipe 5 is connected with a negative pressure chamber and a nozzle 10. The nozzle 10 is located inside the negative pressure chamber. The upper end of the negative pressure chamber is connected with a pressure stabilizing pipe 9. The upper end of the pressure stabilizing pipe 9 is connected with a diffuser pipe 6. The upper end of the diffuser pipe 6 is connected with a return air pipe 15. The other end of the return air pipe 15 is communicated with the rotary separator of the coal mill 1; the negative pressure pipe 4 is communicated with the side surface of the negative pressure chamber; the lower sealing structure 8 includes a floating seal assembly arranged between the lower frame body and the transmission shaft 7. The floating seal assembly includes a machine base seal ring groove and a graphite packing 81, a support connecting ring 82 and a support spring 83 arranged in the machine base seal ring groove. The support spring 83 is located below the support connecting ring 82, and the graphite packing 81 is located above the support connecting ring 82; two groups of floating seal assemblies are arranged from top to bottom in total; the graphite packing 81 is a nickel wire-containing graphite packing 81 with a tightening spring; the upper sealing structure 14 includes a machine base seal ring arranged between the lower frame body and the transmission shaft 7; a sealing fan is connected to the rear pipeline section. The sealing fan outputs sealing air of 14 - 17 kPa. The sealing air enters the coal mill 1 after passing through the rear pipeline section, the air source pipe 5, the air nozzle, the pressure stabilizing pipe 9, the diffuser pipe 6 and the return air pipe 15; the pressure of the sealing air in the return air pipe 15 is greater than the pressure inside the coal mill 1; the height of the nozzle 10 is not lower than the height of the connection port of the negative pressure pipe 4 and the negative pressure chamber; the diffuser pipe 6 is arranged in a horn-shaped structure, and the relatively narrow end of the diffuser pipe 6 is communicated with the pressure stabilizing section; the diameter of the pressure stabilizing pipe 9 is the same as the diameter of the relatively narrow end of the diffuser pipe 6.

[0027] Embodiment 1 of the utility model is as follows:

[0028] For a coal mill 1 operating under positive pressure, powder may leak out from the unsealed parts, polluting the surrounding environment; at the same time, powder may also leak through the gaps of the rotating parts, aggravating the wear of the dynamic and static parts and bearings, and deteriorating the lubricating grease. Therefore, sealing measures should be taken for these parts.

[0029] Common coal mills 1 often adopt a positive pressure seal air system for sealing, that is, air with a higher pressure than the pressure inside the coal mill 1 is sent in to prevent the escape of the pulverized coal air flow. However, when the carbon seal ring is worn, leakage of the hot air and ash powder mixture may still occur, and at the same time, this leakage will cause pollution to the air outside the coal mill 1.

[0030] This application provides a base sealing device for a medium-speed coal mill 1, which adopts a negative pressure suction system. While ensuring the sealing effect, it also extracts the ash powder and then sends it back into the coal mill 1 to ensure that it will not pollute the external environment.

[0031] The medium-speed coal mill 1 includes a lower frame body. A sealing housing is arranged on the upper part of the lower frame body. A driving disc 2 and a transmission shaft 7 are arranged inside the lower frame body and the sealing housing. A lower sealing structure 8 and an upper sealing structure 14 are sleeved on the transmission shaft 7 of the medium-speed coal mill 1 from bottom to top in sequence. A sealing chamber 3 is formed between the sealing housing, the lower sealing structure 8, the upper sealing structure 14 and the transmission shaft 7;

[0032] A sealing air pipeline 12 is connected to the machine base top plate 13 of the lower frame body of the coal mill 1. The sealing air pipeline 12 is communicated with the sealing chamber 3. A butterfly valve 11 is arranged in the middle of the sealing air pipeline 12 and divides the sealing air pipeline 12 into a front pipeline section and a rear pipeline section. A negative pressure pipe 4 is connected to the front pipeline section, and a gas source pipe 5 is connected to the rear pipeline section. The upper end of the gas source pipe 5 is connected with a negative pressure chamber and a nozzle 10. The nozzle 10 is located inside the negative pressure chamber. The upper end of the negative pressure chamber is connected with a pressure stabilizing pipe 9. The upper end of the pressure stabilizing pipe 9 is connected with a diffuser pipe 6. The upper end of the diffuser pipe 6 is connected with a return air pipe 15. The other end of the return air pipe 15 is communicated with the rotary separator of the coal mill 1. The negative pressure pipe 4 is communicated with the side of the negative pressure chamber.

[0033] A sealing fan is connected to the rear pipeline section. The sealing fan outputs sealing air of 14 - 17 kPa. The sealing air enters the coal mill 1 after passing through the rear pipeline section, the gas source pipe 5, the air nozzle, the pressure stabilizing pipe 9, the diffuser pipe 6 and the return air pipe 15.

[0034] When the high-pressure sealing air sprays out from the nozzle 10 and enters the pressure stabilizing pipe 9, an entrainment effect will be generated, driving the air in the negative pressure chamber to move towards the diffuser pipe 6 along with the high-pressure gas. At the same time, since the end of the diffuser pipe 6 is in a flared structure, the entrainment effect will be significantly improved. Then the pressure in the negative pressure chamber decreases, and the air inside the sealing chamber 3 moves towards the negative pressure chamber through the negative pressure pipe 4. At this time, the air between the coal mill 1 and the outside will flow into the sealing chamber 3 from the upper sealing structure 14 and the lower sealing structure 8. In this way, the hot air with pulverized coal will not overflow from the lower sealing structure 8, ensuring the sealing performance. At the same time, the hot air with pulverized coal will enter the negative pressure chamber through the negative pressure pipe 4, and then enter the coal mill 1 after passing through the pressure stabilizing pipe 9, the diffuser pipe 6 and the return air pipe 15, and re-enter the grinding process.

[0035] The lower sealing structure 8 includes a floating seal assembly disposed between the lower frame and the transmission shaft 7. The floating seal assembly includes a seat seal ring groove and a graphite packing 81, a support connecting ring 82, and a support spring 83 disposed in the seat seal ring groove. The support spring 83 is located below the support connecting ring 82, and the graphite packing 81 is located above the support connecting ring 82. It is applicable to dynamic seals under high-temperature and high-pressure conditions. At the same time, the floating seal of the graphite packing 81 is maintained through the support connecting ring 82 and the support spring 83, improving the service life and sealing efficiency of the graphite packing 81.

[0036] Two sets of floating seal assemblies are provided from top to bottom, improving the sealing effect.

[0037] The graphite packing 81 is a nickel wire-containing graphite packing 81 with a tightening spring, which can form a tight and stable oxide coating on the surface, improving the acid, alkali, and corrosion resistance.

[0038] The upper sealing structure 14 includes a seat seal ring disposed between the lower frame and the transmission shaft 7, ensuring that larger pulverized coal does not enter the sealing chamber 3.

[0039] On the other hand, in this embodiment, 14 - 17 kPa sealing air is used as the power steam source to eject the sealing system of the drive disc 2, and the sealing system of the drive disc 2 is ejected into a negative pressure system, ensuring that the pressure of the sealing air in the return air pipe 15 is greater than the pressure in the coal mill 1. Thus, the primary air and dust in the primary air chamber do not leak to the outside, and the dust sucked through the negative pressure system re-enters the interior of the coal mill 1, reducing losses and improving the environmental protection effect.

[0040] The height of the nozzle 10 is not lower than the height of the connection port between the negative pressure pipe 4 and the negative pressure chamber, ensuring that only an ejection effect is generated between the nozzle 10 and the negative pressure pipe 4, and preventing the high-pressure sealing air from flowing back.

[0041] The diffuser tube 6 is provided with a horn-shaped structure. The relatively narrow end of the diffuser tube 6 communicates with the stabilizing section, and the diameter of the stabilizing tube 9 is the same as the diameter of the relatively narrow end of the diffuser tube 6.

[0042] Those skilled in the art should understand that in the disclosure of the specification, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0043] It will be understood that the term "a" should be construed as "at least one" or "one or more". That is, in one embodiment, the number of an element may be one, while in other embodiments, the number of the element may be multiple. The term "a" should not be construed as a limitation on the number.

[0044] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention. The advantages of the present invention have been fully and effectively realized. The functions and structural principles of the present invention have been shown and described in the embodiments. Without departing from the principles, the embodiments of the present invention may have any variations or modifications.

Claims

1. A sealing device for a medium-speed coal mill base, the medium-speed coal mill comprising a lower frame, a sealing shell is arranged on the upper part of the lower frame, and a transmission disc and a transmission shaft are arranged inside the lower frame and the sealing shell; characterized in that: It includes a lower sealing structure and an upper sealing structure which are sequentially sleeved on a transmission shaft of a medium-speed coal mill from bottom to top, and a sealing chamber is formed between the sealing housing, the lower sealing structure, the upper sealing structure and the transmission shaft; A sealed air duct is connected to the lower frame of the coal mill, and the sealed air duct is connected to a sealed chamber. A butterfly valve is provided in the middle of the sealed air duct and divides the sealed air duct into a front section and a rear section. The front section is connected to a negative pressure pipe, and the rear section is connected to an air source pipe. The upper end of the air source pipe is connected to a negative pressure chamber and a nozzle, and the nozzle is located inside the negative pressure chamber. The upper end of the negative pressure chamber is connected to a pressure-stabilizing tube, and the upper end of the pressure-stabilizing tube is connected to a pressure diffuser tube, and the upper end of the pressure diffuser tube is connected to a return air duct, and the other end of the return air duct is connected to the rotating separator of the coal mill; the negative pressure pipe is connected to the side of the negative pressure chamber.

2. The sealing device for medium-speed coal mill base according to claim 1 is characterized in that: The lower sealing structure includes a floating seal assembly arranged between the lower frame and the transmission shaft, the floating seal assembly includes a machine base sealing ring groove and a graphite packing, a supporting connecting ring and a supporting spring arranged in the machine base sealing ring groove, the supporting spring is located below the supporting connecting ring, and the graphite packing is located above the supporting connecting ring.

3. The sealing device for medium-speed coal mill base according to claim 2 is characterized in that: The floating seal assembly is provided in two groups from top to bottom.

4. The sealing device for medium-speed coal mill base according to claim 3 is characterized in that: The graphite packing is a nickel-wire graphite packing with a tightening spring.

5. The sealing device for medium-speed coal mill base according to claim 1 is characterized in that: The upper sealing structure comprises a base sealing ring arranged between the lower frame and the transmission shaft.

6. The sealing device for medium-speed coal mill base according to claim 1 is characterized in that: The rear section of the pipeline is connected to a sealed fan, which outputs 14-17kPa sealed air. The sealed air enters the coal mill after passing through the rear section of the pipeline, the air source pipe, the air nozzle, the pressure-stabilizing pipe, the pressure-expanding pipe and the return air pipe.

7. The sealing device for medium-speed coal mill base according to claim 6 is characterized in that: The pressure of the sealing air in the return air duct is greater than the pressure in the coal mill.

8. The sealing device for medium-speed coal mill base according to claim 6 is characterized in that: The height of the nozzle is not lower than the height of the connection port between the negative pressure tube and the negative pressure chamber.

9. The sealing device for medium-speed coal mill base according to claim 6 is characterized in that: The pressure diffuser is configured as a trumpet-shaped structure, and a relatively narrow end of the pressure diffuser is connected to the pressure stabilizing section.

10. The sealing device for medium-speed coal mill base according to claim 9 is characterized in that: The diameter of the voltage regulator tube is the same as the diameter of the relatively narrow end of the pressure diffuser tube.

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