JP5488323B2 - Method and apparatus for reducing wear of mill roller bearing - Google Patents

Description

  The present invention relates to a method and an apparatus for reducing wear of a mill roller bearing.

  Conventionally, in a coal fired boiler using pulverized coal as a fuel, a pulverizer called a vertical mill that pulverizes coal to produce pulverized coal has been used.

  The vertical mill has a configuration in which coal is supplied onto the rotation center of a rotary table that is driven to rotate horizontally, and the mill roller provided in the pivot bracket is pressed into the crushing groove provided on the outer peripheral upper surface of the rotary table. In addition, the coal is pulverized between a mill roller that is rotated (rotated) by rotation of the rotary table and a pulverizing groove, and the pulverized pulverized coal is floated and transported by primary air.

  Coal supplied to the rotation center of the rotary table receives centrifugal force due to rotation of the rotary table and is fed into the crushing groove. The coal fed in this way is smoothly bitten and effectively crushed. The roller shaft of the mill roller is inclined so that the center side of the rotary table is low and the outside is high for the purpose of performing vibration reduction and the like. Is rotatably supported by a mill roller bearing provided inside the mill roller.

  The mill roller bearing receives a thrust load in the axial direction of the roller shaft by combining a cylindrical roller bearing that receives a load in a direction perpendicular to the axis of the roller shaft with a cylindrical roller and an inclined roller that is inclined in the opposite direction to the C shape. The thrust roller bearing has a configuration in which the thrust roller bearing is disposed at an interval in the axial direction.

  Since the mill roller bearing is provided inside the rotating mill roller as described above, the mill roller bearing cannot be lubricated from the outside. For this reason, the mill roller bearing is enclosed in a bearing chamber inside the mill roller. It is lubricated with the lubricant.

  As prior art document information showing a general configuration of the vertical mill, there is Patent Document 1.

JP 2002-102730 A

  However, as described above, in the configuration in which the mill roller is rotatably supported on the inclined roller shaft via the mill roller bearing, and the lubricant is sealed in the bearing chamber inside the mill roller, the mill roller bearing is lubricated. Since the roller shaft and the mill roller are inclined, the amount of lubricant contained in the bearing chamber increases on the tip side where the height of the roller shaft becomes low, and the height increases away from the tip of the roller shaft. The amount of storage is decreasing on the higher proximal end side.

  Therefore, the depth at which the mill roller bearing is immersed in the lubricant is not uniform in the axial direction, and the immersion depth is deep at the distal end side of the roller shaft, and the immersion depth is shallow at the proximal end side away from the distal end. .

  During normal operation of the conventional vertical mill, the rotational speed of the rotary table is adjusted based on the required pulverized coal supply amount regardless of the environmental temperature or the like.

  During normal operation of the vertical mill, the lubricant usually has a temperature of 80 ° C. or higher, which is the temperature of the primary air, so that the lubricant can reach the mill roller bearing and perform sufficient lubrication. However, when the temperature of the lubricant is low, such as when starting a vertical mill, it becomes difficult for the lubricant to go around the mill roller bearing on the base end side where the immersion depth is shallow. This is considered to be one factor that wears and damages the roller of the mill roller bearing on the side where the agent is difficult to go around and shortens the life of the bearing.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a method and an apparatus for reducing the wear of a mill roller bearing that can extend the life of the mill roller bearing by always stably lubricating the mill roller bearing. To do.

  In the present invention, the mill roller bearing of the pulverizing apparatus that pulverizes the granular material by pressing the mill roller rotatably supported on the inclined roller shaft via the mill roller bearing into the pulverizing groove of the rotary table is enclosed in a bearing chamber inside the mill roller. A method for reducing wear of a mill roller bearing lubricated by a lubricant, wherein the temperature of the lubricant is detected by a lubricant temperature detecting means, and the temperature detected by the lubricant temperature detecting means and the previously determined lubricant temperature -Based on the bearing rotation speed correlation curve, the rotation of the rotary table is set so that the bearing rotation speed when the lubricant temperature is lower than the threshold is set lower than the bearing rotation speed of the mill roller bearing at the lubricant temperature during steady operation. The present invention relates to a method for reducing wear of a mill roller bearing, characterized in that control is performed.

  Also, the present invention provides the mill roller bearing of the pulverizer for pulverizing the granular material by pressing the mill roller rotatably supported on the inclined roller shaft via the mill roller bearing against the pulverization groove of the rotary table. An apparatus for reducing the wear of a mill roller bearing that is lubricated by a lubricant encapsulated in a lubricant, wherein a lubricant temperature detecting means for detecting the temperature of the lubricant and a lubricant temperature-bearing rotational speed correlation curve obtained in advance are input. Based on the lubricant temperature-bearing rotational speed correlation curve based on the detected temperature of the lubricant temperature detecting means, the lubricant temperature is relative to the bearing rotational speed of the mill roller bearing at the lubricant temperature during steady operation. And a controller for controlling the rotation of the rotary table so as to set the bearing rotational speed when the bearing rotational speed is lower than a threshold value. It relates to.

  According to the mill roller bearing wear reduction method and apparatus of the present invention, based on the temperature detected by the lubricant temperature detecting means and the previously obtained lubricant temperature-bearing rotational speed correlation curve, the mill roller at the lubricant temperature during steady operation is obtained. Since the rotation of the rotary table is controlled so that the bearing rotation speed when the lubricant temperature is lower than the threshold value is set lower than the bearing rotation speed of the bearing, a problem that causes poor lubrication particularly when the lubricant temperature is low. Therefore, it is possible to achieve an excellent effect that the mill roller bearing can always be well lubricated to extend the life of the mill roller bearing.

It is a longitudinal cross-sectional view of the vertical mill which is an example of the grinding | pulverization apparatus to which the abrasion reduction method and apparatus of the mill roller bearing which is an Example of this invention are applied. It is sectional drawing which shows the structure of the mill roller bearing with which the vertical mill of FIG. 1 is equipped. It is a lubricant temperature-bearing rotational speed correlation curve figure which calculated | required the limit bearing rotational speed of the mill roller bearing which a lubricant does not become difficult with respect to lubricant temperature.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a longitudinal sectional view of a vertical mill as an example of a grinding apparatus to which a method and apparatus for reducing wear of a mill roller bearing according to an embodiment of the present invention is applied. FIG. 2 is a diagram of a mill roller bearing provided in the vertical mill of FIG. It is sectional drawing which shows a structure.

  A rotary table 5 that is rotationally driven by a motor 3 via a speed reducer 4 is disposed in the lower part of the casing 2 of the vertical mill 1 shown in FIG. 1. 1. As shown in FIG. 2, a pivot bracket 6 is disposed so as to be tiltable with a horizontal shaft 7 supported on the casing 2 as a fulcrum, and is provided on the pivot bracket 6 so as to be substantially orthogonal to the horizontal shaft 7. A mill roller 8 that is rotatable about the roller shaft 9 is attached to the tip of the shaft 9. For example, three mill rollers 8 are arranged in the circumferential direction. Further, a fluid pressure cylinder 10 using a fluid such as oil is attached to the casing 2, and the pressing portion 6 a of the pivot bracket 6 is pushed by the rod of the fluid pressure cylinder 10 via the plunger 11. Then, the mill roller 8 is rotated downward and pressed against the annular crushing groove 12 on the upper surface of the rotary table 5 that is rotating horizontally, and between the mill roller 8 and the crushing groove 12 of the rotary table 5, The pulverization of coal, which is a granular material supplied to the plant, is performed. At this time, the roller shaft 9 of the mill roller 8 when the coal is crushed and crushed has a required inclination angle α at which the height on the tip side is low and the height on the base end side supported by the horizontal shaft 7 is high. Has been placed.

  A primary air chamber 13 is formed below the turntable 5 in the casing 2, and an air port 14 is disposed so as to surround the turntable 5. The primary air 16 is supplied by the supply duct 15.

  A coal chute 17 for supplying coal, which is a granular material, is supported on the casing 2 at the upper part of the rotation center of the turntable 5, and pulverized coal is boiler on the outer periphery of the coal chute 17. A fine powder feed pipe 18 for feeding to a burner (not shown) is connected. Then, the pulverized coal that is crushed by the mill roller 8 and rides on the air blown out from the air port 14 and rises in the casing 2 passes through the slit 20 provided on the inclined surface of the truncated reverse conical reject chute 19, and passes through the motor. After the coarse particles are separated by being guided to the rotary classifier 22 rotated by 21, only the pulverized coal is guided to the pulverized feed pipe 18.

  As shown in FIG. 2, the mill roller bearing 23 that rotatably supports the mill roller 8 on the roller shaft 9 includes a cylindrical roller bearing 23 a on the base end side that receives a load perpendicular to the axis of the roller shaft 9 by a cylindrical roller 24. The thrust roller bearings 23b that receive the thrust load in the axial direction of the roller shaft 9 are provided at intervals in the axial direction by providing a combination of the inclined rollers 25 that are inclined in opposite directions in the shape of a letter C.

  Further, the mill roller 8 is provided with a cover member 27 surrounding the tip of the roller shaft 9 to form a bearing chamber 26. The cover member 27 has a required amount of lubricant 28 (in the bearing chamber 26). Lubricating oil) is supplied and sealed, and a supply port 29 is provided. At this time, since the roller shaft 9 and the mill roller 8 are inclined, the lubricant 28 enclosed in the bearing chamber 26 is stored on the tip side (thrust roller bearing 23b side) where the height of the roller shaft 9 is lowered. The amount increases, and the storage amount decreases on the base end side (cylindrical roller bearing 23a side) where the height increases with increasing distance from the tip end of the roller shaft 9. In FIG. 2, the cylindrical roller bearing 23a on the inner peripheral surface of the mill roller 8 projects between the cylindrical roller bearing 23a and the thrust roller bearing 23b on the inner peripheral side (roller shaft 9 side) and has a small amount of lubricant. The case where the protrusion-like member 30 conventionally provided for keeping the lubricant is provided is shown.

  The vertical mill 1 is provided with a lubricant temperature detecting means 31 for detecting the temperature of the lubricant 28 in the bearing chamber 26 of the mill roller 8 shown in FIG. 2, and the temperature detected by the lubricant temperature detecting means 31 is indicated by a signal line 32. To the controller 33 shown in FIG. 2 is provided with a temperature sensor 31a for directly detecting the temperature of the lubricant 28 in the bearing chamber 26, and a signal obtained by passing the temperature detected by the temperature sensor 31a through the inside of the roller shaft 9 is provided. The case where it guide | induces to the said controller 33 with the line 32 is shown. The lubricant temperature detecting means 31 detects the temperature of the roller shaft 9 or the ambient temperature in the casing 2 in addition to the method of directly detecting the temperature of the lubricant 28 by the temperature sensor 31a as described above. Then, the temperature of the lubricant 28 may be empirically estimated from these detected temperatures.

  Since a very large load acts on the mill roller bearing 23 of the mill roller 8, a mineral oil or a synthetic oil has been conventionally used as a lubricant so that lubrication is possible even when such a large load is applied.

  The inventors set the limit bearing rotational speed with respect to the lubricant temperature at which the mill roller bearing 23 does not cause poor lubrication when the coal is pulverized by the mill roller 8 while the mill roller bearing 23 is lubricated with the synthetic oil. The required test was performed to obtain a lubricant temperature-bearing rotational speed correlation curve A shown in FIG.

  The lubricant temperature-bearing rotational speed correlation curve A shown in FIG. 3 obtained by the above test is input to the controller 33. In FIG. 3, B is a threshold value.

  The rotational speed of the turntable 5 and the amount of coal input during the steady operation of the vertical mill 1 of FIG. 1 are independently controlled based on the required amount of pulverized coal supplied. The drive of the motor 3 is switched and controlled so that the bearing rotational speed is changed depending on whether the detected temperature of the agent 28 is higher or lower than the threshold value B of the lubricant temperature-bearing rotational speed correlation curve A in FIG. Yes. When the detected temperature of the lubricant 28 is lower than the threshold value B, the rotational speed of the rotary table 5 is controlled to be low according to the detected temperature, and the bearing rotational speed is controlled to be low. For this reason, an inverter motor can be used for the electric motor 3.

  The rotational speed of the mill roller bearing 23 at the rotational speed of the turntable 5 during steady operation was approximately 30 rpm in the test shown in FIG. In the lubricant temperature-bearing rotational speed correlation curve A shown in FIG. 3, if the temperature of the lubricant is approximately 50 ° C. or higher, good lubrication can be performed even at the steady rotational speed of the mill roller bearing 23, 30 rpm. I understood. For this reason, the lubricant temperature of 50 ° C. is set as the threshold value B in FIG. Here, at the time of steady operation of the vertical mill 1, since the coal is dried by high-temperature primary air blown from the air port 14 so that the temperature at the outlet of the mill is maintained at 80 ° C., lubrication The agent 28 is maintained at a temperature of about 80 ° C. or higher in the vertical mill 1, and the mill roller bearing 23 is lubricated satisfactorily.

  On the other hand, when the temperature of the lubricant 28 is 50 ° C. or lower and the mill roller bearing 23 rotates at a steady rotational speed, the lubrication of the mill roller bearing 23 becomes poor. In order to perform satisfactory lubrication even when the temperature of the lubricant 28 is 50 ° C. or less, it is necessary to reduce the bearing rotational speed of the mill roller bearing 23 according to the lubricant temperature. For example, when the temperature of the lubricant 28 is 20 ° C., it is understood that the bearing rotational speed needs to be suppressed to about 10 rpm or less in order to make the lubricant easy to go around.

  Therefore, when the vertical mill 1 is started when the temperature of the lubricant is 20 ° C., the rotation of the rotary table 5 is adjusted by adjusting the drive of the electric motor 3 so that the bearing rotational speed is set to about 10 rpm or less. It is necessary to control the number (that is, the number of rotations of the mill roller 8).

  Next, the operation of the above embodiment will be described.

  When the vertical mill 1 of FIG. 1 is stopped, the primary air 16 is not supplied, and therefore the temperature of the lubricant 28 in the mill roller 8 is lowered to a temperature close to the ambient temperature (for example, 20 ° C.).

  When starting the vertical mill 1 from this state, the electric motor 3 is driven to rotate the rotary table 5, the coal is supplied onto the rotary table 5 by the coal chute 17, and further, the primary air supply duct 15 is used. The primary air 16 is supplied to the primary air chamber 13 to blow out the primary air 16 from the air port 14. At this time, the detected temperature of the lubricant 28 detected by the lubricant temperature detecting means 31 is input to the controller 33. Further, since the lubricant temperature-bearing rotational speed correlation curve A shown in FIG. 3 is input to the controller 33, the controller 33 detects that the detected temperature of the lubricant 28 is the lubricant temperature-bearing. The drive of the electric motor 3 is switched and controlled so that the bearing rotational speed is changed depending on whether it is higher or lower than the threshold value B of the rotational speed correlation curve A. The rotational speed of the rotary table 5 is controlled to a low rotational reduce the bearing speed. In this way, when the lubricant temperature is lower than the threshold value B, by controlling so that the bearing rotational speed of the mill roller bearing 23 is kept low, the mill roller bearing 23 is lubricated even when the vertical mill 1 in which the lubricant temperature is low is started. Can be performed satisfactorily. As described above, even when the lubricant temperature is low, the mill roller bearing 23 is stably lubricated, whereby the life of the mill roller bearing 23 can be extended. When the lubricant temperature rises above the threshold B, the controller 33 automatically switches to the control during steady operation.

  The method and apparatus for reducing the wear of a mill roller bearing according to the present invention is not limited to the above-described embodiment, and any mill other than a vertical mill can be used as long as it is a crusher having an inclined roller shaft. Needless to say, the present invention can be applied to the pulverization of the granular material, the mill roller bearing can be applied to a configuration other than the illustrated example, and various changes can be made without departing from the scope of the present invention.

1 Vertical mill (pulverizer)
5 Rotary Table 8 Mill Roller 9 Roller Shaft 12 Grinding Groove 23 Mill Roller Bearing 23a Cylindrical Roller Bearing (Mill Roller Bearing)
23b Thrust roller bearing (Mill roller bearing)
26 Bearing chamber 28 Lubricant 31 Lubricant temperature detection means 33 Controller A Lubricant temperature-bearing rotational speed correlation curve B Threshold value α Inclination angle

Claims (2)

  The mill roller bearing of the pulverizer for pulverizing the granular material by pressing the mill roller rotatably supported on the inclined roller shaft via the mill roller bearing against the pulverization groove of the rotary table is made by a lubricant enclosed in a bearing chamber inside the mill roller. A method for reducing the wear of a lubricated mill roller bearing, wherein the temperature of the lubricant is detected by a lubricant temperature detecting means, the temperature detected by the lubricant temperature detecting means, and a lubricant temperature-bearing rotational speed determined in advance. Based on the correlation curve, the rotation of the rotary table is controlled so that the bearing rotational speed when the lubricant temperature is lower than the threshold is set lower than the bearing rotational speed of the mill roller bearing at the lubricant temperature during steady operation. A method for reducing the wear of mill roller bearings.   The mill roller bearing of the pulverizer for pulverizing the granular material by pressing the mill roller rotatably supported on the inclined roller shaft via the mill roller bearing against the pulverization groove of the rotary table is made by a lubricant enclosed in a bearing chamber inside the mill roller. A device for reducing wear of a lubricating mill roller bearing, wherein a lubricant temperature detecting means for detecting the temperature of the lubricant and a lubricant temperature-bearing rotational speed correlation curve obtained in advance are input, and the lubricant Based on the lubricant temperature-bearing rotational speed correlation curve based on the temperature detected by the temperature detecting means, the bearing when the lubricant temperature is lower than the threshold with respect to the bearing rotational speed of the mill roller bearing at the lubricant temperature during steady operation. And a controller for controlling the rotation of the rotary table so as to set the rotational speed to a low value.

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