JP2011098252A - Vertical mill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical mill that prevents wear of a labyrinth seal and suppressed rotation of a pressure roller due to pulverized coal clogged between the labyrinth seals. <P>SOLUTION: The vertical mill includes: a housing in which a classifying chamber is formed; a crushing table 1 which is housed in the lower part of the housing and rotatably driven by a table driving device; a shaft holder 17 for freely rotatably holding a pressure roller 4; a labyrinth seal 30 provided between the pressure roller and the shaft holder; a roller pressurizing means 29 which pressurizes the pressure roller to the crushing table and crushes lumpy objects on the crushing table; and a controller 57 for controlling the pressing force of the roller pressurizing means. The labyrinth seal is composed of a rotary labyrinth ring 16 provided on the pressure roller and a fixed labyrinth ring 21 provided on the shaft holder. The controller pulsates a tangential force working between the rotary labyrinth ring and the fixed labyrinth ring by varying the pressing force of the roller pressurizing means. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a vertical mill that pulverizes lumps such as coal and limestone into fine powder.

  In a coal-fired boiler using coal as fuel, massive coal is pulverized by a vertical mill into pulverized coal, and the pulverized coal is supplied together with primary air to a burner that is a combustion apparatus.

  First, an outline of a conventional vertical mill will be described with reference to FIGS.

  In the conventional vertical mill, a pulverizing table 1 for pulverizing coal is rotatably provided. The pulverizing table 1 is connected to a table driving motor 3 via a speed reducer 2, and the pulverizing table 1 is driven by the table driving motor 3. Is rotated.

  Above the crushing table 1, a plurality of pressure roller units 5 (described later) having a pressure roller 4 are provided, for example, three at intervals of 120 °, and the pressure roller unit 5 is not shown. It is pressed onto the crushing table 1 by a roller pressing device.

  During the coal pulverization process, lump coal is dropped from the coal supply device (not shown) onto the center of the pulverization table 1, and the pulverization table 1 is parallel to the table drive motor 3 via the speed reducer 2. Is rotated by.

  The pressure roller 4 is rotatable and is driven to rotate by the crushing table 1. The coal dropped on the crushing table 1 is moved by the rotation of the crushing table 1, and the pressure roller 4 is crushed by being bitten.

  Next, the conventional pressure roller unit 5 will be described with reference to FIG.

  The pressure roller unit 5 holds a roller shaft 8, the pressure roller 4 rotatably supported by the roller shaft 8, and the roller shaft 8. The pressure roller unit 5 is pressed by a roller pressure device (not shown). The holding unit 7 presses the pressure roller 4 against the crushing table 1.

  The pressure roller 4 includes a roller wheel portion 11 provided via a bearing 9 provided on the roller shaft 8, and a space formed by the roller wheel portion 11, the bearing 9, and the roller shaft 8. An oil bath 12 filled with oil and a roller tire 13 fitted or attached to the roller wheel portion 11 are provided, and the roller tire 13 is pressed onto the crushing table 1 by a roller pressurizing device (not shown). It has become.

  A closing cap 14 is provided at the tip of the roller wheel 11 to seal the opening of the tip. The base of the pressure roller 4 closes the space between the roller shaft 8 and the bearing 9 in a liquid-tight manner. A shaft seal 15 is provided to seal the oil bath 12 in a liquid-tight manner.

  The holding unit 7 includes a shaft holding unit 17 that supports the roller shaft 8, a pressure receiver 18 that is pressed by a roller pressing device (not shown), and a pivot shaft that becomes a center of rotation when the pressure receiver 18 is pressed. 19.

  A ring-shaped rotating labyrinth ring 16 made of metal protrudes concentrically with the roller shaft 8 at the rear periphery of the roller wheel portion 11, and is made of metal at the periphery of the tip portion 20 of the shaft holding portion 17. A ring-shaped fixed labyrinth ring 21 protrudes concentrically with the roller shaft 8, and the diameter of the rotating labyrinth ring 16 is larger than the diameter of the fixed labyrinth ring 21.

  The rotating labyrinth ring 16 and the fixed labyrinth ring 21 are overlapped with a slight gap therebetween, and the rotating labyrinth ring 16 and the fixed labyrinth ring 21 constitute a labyrinth seal 30. The labyrinth seal 30 reduces the opening area between the pressure roller 4 and the holding portion 7 by the rotating labyrinth ring 16 and the fixed labyrinth ring 21, and further ejects seal air, which will be described later, into the vertical mill. Thus, it has a function of preventing the entry of pulverized coal from the vertical mill.

  Further, a seal air flow path 22 is formed across the pivot shaft 19 and the shaft holding portion 17, and a space 23 formed inside the labyrinth seal 30 via the seal air flow path 22 is provided outside the saddle type mill. The seal air flow path 22 is connected to a seal air supply means (not shown) on the opposite side of the space 23.

  In the conventional vertical mill, during coal pulverization processing, seal air is supplied from a seal air supply means (not shown) to the space 23 via the seal air flow path 22, and between the rotating labyrinth ring 16 and the fixed labyrinth ring 21. By blowing seal air into the vertical mill, pulverized coal is prevented from entering the space 23 from between the rotating labyrinth ring 16 and the fixed labyrinth ring 21.

  However, when the particle size of the pulverized coal is large, or when a large amount of pulverized coal is poured, the entry cannot be prevented only by the seal air blown between the rotating labyrinth ring 16 and the fixed labyrinth ring 21. For this reason, pulverized coal may clog between the rotating labyrinth ring 16 and the fixed labyrinth ring 21 at a rate of about once every several months.

  When pulverized coal is clogged between the rotating labyrinth ring 16 and the fixed labyrinth ring 21, rotation of the pressure roller 4 is suppressed due to friction, and clogging occurs due to accumulation of pulverized coal on the clogged pulverized coal. When the operation is further performed in a clogged state, the rotating labyrinth ring 16 and the fixed labyrinth ring 21 are worn. Alternatively, the rotation of the pressure roller 4 is stopped. For this reason, it is necessary to replace the rotating labyrinth ring 16 and the fixed labyrinth ring 21, and there is a problem that the maintenance cost increases. Further, since the rotating labyrinth ring 16 and the fixed labyrinth ring 21 need to be periodically cleaned in order to prevent wear, there is a problem that the maintenance cost also increases.

JP 2002-59016 A Japanese Patent Laid-Open No. 10-146536 Special Table 2002-519175

  In view of such circumstances, the present invention provides a vertical mill that prevents wear of the labyrinth seal and suppression of rotation of the pressure roller due to clogging of pulverized coal between the labyrinth seals.

  The present invention includes a housing that forms a classification chamber, a pulverizing table that is housed in a lower portion of the housing and is driven to rotate by a table driving device, a shaft holding portion that rotatably holds a pressure roller, and the pressure roller. And a labyrinth seal provided between the shaft holding part, a roller pressing means for pressing a pressure roller against the pulverizing table and pulverizing a lump on the pulverizing table, and a pressing force of the roller pressing means The labyrinth seal is composed of a rotating labyrinth ring provided on the pressure roller and a fixed labyrinth ring provided on the shaft holding portion. The present invention relates to a vertical mill that pulsates a tangential force acting between the rotating labyrinth ring and the fixed labyrinth ring by changing the pressing force of the pressure means.

  The present invention may further include a detector that detects a seal pressure of the labyrinth seal, and the control unit may be a vertical mill that varies the pressing force of the roller pressing unit based on a detection result from the detector. It is concerned.

  According to the present invention, the housing that forms the classification chamber, the pulverization table that is housed in the lower part of the housing and is driven to rotate by the table driving device, the shaft holding portion that rotatably holds the pressure roller, and the additional unit are provided. A labyrinth seal provided between the pressure roller and the shaft holder, a roller pressure unit that presses the pressure roller against the crushing table and crushes the lump on the crushing table, and The labyrinth seal is composed of a rotating labyrinth ring provided on the pressure roller and a fixed labyrinth ring provided on the shaft holding portion, and the control unit includes the control unit that controls the pressing force. Since the tangential force acting between the rotating labyrinth ring and the fixed labyrinth ring is pulsated by changing the pressing force of the roller pressing means, the rotating labyrinth The sling and coal packed between the fixed labyrinth rings can be crushed by applying repeated load and variable load, and there is no need to rework the conventional pressure roller and shaft holder. Is easy, and the cost for implementation can be reduced.

  Further, according to the present invention, further comprising a detector for detecting the seal pressure of the labyrinth seal, the control unit varies the pressing force of the roller pressing means based on the detection result from the detector, Coal clogged in the labyrinth seal can be immediately pulverized, and wear of the labyrinth seal caused by rotating the pressure roller while the labyrinth seal is clogged, and prevention of rotation of the pressure roller are prevented. Demonstrate the excellent effect of being able to.

It is a general | schematic elevational sectional view of the vertical mill in this invention. It is an expanded sectional view of the pressure roller unit in the present invention. It is a side view explaining the effect | action in the conventional vertical mill. It is a top view explaining the effect | action in the conventional vertical mill. It is an expanded vertical sectional view of a conventional pressure roller unit.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, an outline of a vertical mill 10 in which the present invention is implemented will be described with reference to FIG. In FIG. 1, the same components as those in FIGS.

  A cylindrical housing 25 is erected on a base 24 having a hollow structure or a leg structure, and a sealed space is formed by the housing 25. A crushing table 1 is provided in the lower part of the space via a speed reducer 2, the speed reducer 2 is driven by a table drive motor 3, and the table drive motor 3 is rotated at a constant speed or a variable speed by the speed reducer 2. Is done.

  On the upper surface of the pulverizing table 1, a table segment 27 having a concave groove 26 having an arcuate cross section is provided.

  A required number of sets, for example, three sets of pressure roller units 5 are provided radially from the rotation center of the crushing table 1 at intervals of 120 °. The pressure roller unit 5 has a pressure roller 4 and is tiltable about a pivot shaft 19. In addition, three sets of roller pressing devices 28 that penetrate radially are provided in the lower portion of the housing 25. The roller pressure device 28 includes an actuator, for example, a hydraulic cylinder 29 that is a roller pressure unit, and presses the pressure roller 4 against the concave groove 26 by the hydraulic cylinder 29.

  A primary air chamber 31 is formed below the pulverization table 1, and a classification chamber 32 is provided above the pulverization table 1 inside the housing 25.

  A primary air supply port 33 is attached to the lower portion of the housing 25, and the primary air supply port 33 is connected to a blower (not shown) and communicates with the primary air chamber 31. A primary air outlet 34 is provided around the pulverization table 1 on the entire circumference.

  A coal supply / discharge portion 35 is provided on the upper side of the housing 25, and a pipe-shaped coal supply pipe 36 is provided so as to penetrate the central portion of the coal supply / discharge portion 35. It extends into the housing 25 and its lower end is located above the center of the grinding table 1. Coal is supplied to the coal supply pipe 36, and the supplied coal falls to the central portion of the crushing table 1.

  In the coal supply pipe 36, a rotary pipe 37 is rotatably provided on a rotary pipe support portion 38 via a bearing 39. The rotary pipe 37 is rotated by a classifier motor 45 via a belt 43 stretched between a pulley 41 and a pulley 42 and a speed reducer 44 provided with the pulley 42.

  A classifier 47 is constituted by the rotary pipe 37, the pulley 41, the pulley 42, the belt 43, the speed reducer 44, the classifier motor 45, and the blade 46.

  The blade 46 has a strip shape and is arranged on the inverted conical curved surface in the circumferential direction at a required angular pitch. The blade 46 is inclined from the lower end toward the upper end so as to be separated from the rotary tube 37, and is attached to the rotary tube 37 via a blade support portion 48.

  Below the classifier 47, an inverted conical reject chute 49 is disposed so as to divide the classifying chamber 32 up and down, and the reject chute 49 contains powdered coal at a required angular pitch in the circumferential direction. A slit 51 through which the next air passes is formed.

  The upper end of the reject chute 49 is fixed to the housing 25 and is supported by a reject chute support 53 via a bracket 52 fixed to the rotary tube 37. The lower end of the reject chute 49 has a cylindrical shape, and the lower end is opened to form an opening 54 between the coal supply pipe 36.

  A pulverized coal feed pipe 55 for feeding pulverized pulverized coal is connected to the coal feed / discharge section 35, and the pulverized coal feed pipe 55 is connected to a burner (not shown) of a boiler. Yes.

  Next, coal pulverization in the vertical mill 10 will be described.

  In FIG. 1, the solid line indicates the flow of primary air, and the dotted line indicates the flow of coal.

  The pulverization table 1 is rotated by the table drive motor 3 via the speed reducer 2, and primary air at around 200 ° C. is introduced into the primary air chamber 31 from the primary air supply port 33. The lump coal is supplied from the coal supply pipe 36. Lumped coal flows from the lower end of the coal supply pipe 36 to the center of the crushing table 1 and is supplied onto the crushing table 1.

  The coal on the pulverizing table 1 is moved in the outer peripheral direction by centrifugal force generated by the rotation of the pulverizing table 1, and is pulverized into pulverized coal composed of coarse and pulverized coal by the pressure roller 4. To move to the outer circumference.

  The primary air introduced into the primary air chamber 31 from the primary air supply port 33 is blown up from the blow-out port 34 of the pulverizing table 1, and the pulverized coal that has crossed the table segment 27 by centrifugal force is It rides on the primary air blown up from the outlet 34 and moves up the outer peripheral portion of the classification chamber 32 along the wall surface of the housing 25.

  The pulverized coal rising on the primary air around the outer periphery of the classifying chamber 32 falls on the crushing table 1 due to its own weight while a part of the coarse pulverized coal having a large particle diameter is rising, and a part of the pulverized coal Collides with the lower surface and is bounced to the lower outer periphery. Coarse coal that has been bounced by the reject chute 49 falls onto the crushing table 1. The remaining pulverized coal and pulverized coal ride on the primary air, pass through the slit 51, and further rise in the classification chamber 32.

  Coarse and pulverized coal that has passed through the slit 51 flows into the classifier 47 together with primary air. When the blade 46 rotated by the classifier motor 45 is crossed, coarse coal having a predetermined particle size or more collides with the blade 46 and is repelled. Further, since the blade 46 is provided on the inverted conical curved surface, the coarse coal is blown off to the outer peripheral side of the classification chamber 32. Further, the pulverized coal having a predetermined particle size or less rides on the primary air, crosses the blade 46, is sent out from the pulverized coal feed pipe 55, and is supplied to a boiler burner (not shown).

  Coarse coal that has been blown off by the blade 46 falls on the outer periphery of the classification chamber 32, slides along the slope of the reject chute 49, and falls onto the center of the pulverizing table 1 from the opening 54. . The fallen coarse pulverized coal moves to the concave groove 26 by the rotational centrifugal force of the crushing table 1 and is pulverized again by the pressure roller 4. A part of the pulverized coal that slides down also falls from the slit 51.

  Next, the pressure roller unit 5 in this embodiment will be described with reference to FIG. 2 that are the same as those in FIGS. 3 to 5 are denoted by the same reference numerals, and description thereof is omitted.

  The pressure roller unit 5 includes a pressure roller 4, a holding portion 7, and a roller shaft 8, and the pressure roller 4 is rotatably supported by a roller shaft 8, and the holding portion 7 is supported by the roller shaft 8. And a shaft holding portion 17 that presses the pressure roller 4 onto the crushing table 1 through the pivot shaft 19 by being pressed from the hydraulic cylinder 29.

  The front end of the pressure roller 4 is covered with a closing cap 14, and the base of the pressure roller 4 is closed with a shaft seal 15, and the pressure roller 4 and the roller are sealed with the closing cap 14 and the shaft seal 15. The gap with the shaft 8 is sealed in a liquid-tight manner.

  A tip 20 is formed at the tip of the shaft holding portion 17, and a fixed labyrinth ring 21 concentric with the roller shaft 8 is projected from the front peripheral edge of the tip 20, and the rear surface of the roller wheel portion 11. A rotating labyrinth ring 16 concentric with the roller shaft 8 is provided on the periphery. Note that the inner periphery of the rotating labyrinth ring 16 and the outer periphery of the fixed labyrinth ring 21 may be subjected to wear-resistant processing such as wear-resistant coating or build-up of wear members.

  A labyrinth seal 30 is constituted by the rotating labyrinth ring 16 and the fixed labyrinth ring 21, and a space 23 is formed between the labyrinth seal 30 and the roller shaft 8, and a seal air flow path 22 is provided in the space 23. Seal air is introduced from a seal air supply means (not shown).

  The seal air flow path 22 is connected to a pressure sensor 56 that is a detector for detecting the pressure of the seal air flowing through the seal air flow path 22, and the pressure sensor 56 feeds back the detection result to the roller pressurizing device 28. It has become.

  The roller pressure device 28 includes the hydraulic cylinder 29 and a hydraulic pressure control unit 57, and the hydraulic cylinder 29 presses the holding unit 7 via the pressure receiver 18, thereby pulverizing the pressure roller 4. Press down on table 1. The hydraulic control unit 57 controls the pressing force of the hydraulic cylinder 29 based on the detection result from the pressure sensor 56.

  In the figure, R represents the radius of the pressure roller 4, r represents the radius of the tip 20, f represents the reduction force of the pressure roller 4, and μ represents the frictional force of the grinding table 1. Represents.

  The pressure roller unit 5 is maintained at a rate of once every several years. In the maintenance, the oil in the roller tire 13 and the oil bath 12 is replaced.

  In the vertical mill 10 of the present embodiment having the above-described configuration, during the coal pulverization process, the pressure roller 4 causes the hydraulic cylinder 29 to move the pressure receiver 18 with a constant force by the hydraulic control unit 57. Is pressed onto the crushing table 1, and the crushing table 1 is rotated to be driven.

  Further, seal air supplied from a seal air supply means (not shown) is discharged to the classification chamber 32 from between the rotating labyrinth ring 16 and the fixed labyrinth ring 21 via the seal air flow path 22 and the space 23. Bulk coal was dropped from the coal supply pipe 36, and coal (pulverized coal) crushed by the pressure roller 4 or coal bounced on the pulverization table 1 soared in the classification chamber 32 and soared. Part of the coal is poured onto the pressure roller unit 5.

  The pressure sensor 56 constantly detects the pressure of the seal air flowing through the seal air flow path 22 during the pulverization process, that is, the seal pressure between the rotating labyrinth ring 16 and the fixed labyrinth ring 21, and the detection result is the hydraulic pressure. Feedback is given to the control unit 57.

  During the processing, when pulverized coal is clogged between the rotating labyrinth ring 16 and the fixed labyrinth ring 21, the flow path of the seal air discharged from the space 23 to the classification chamber 32 is narrowed. And the pressure of the seal air flow path 22 rises. The pressure sensor 56 detects a pressure change in the seal air flow path 22 and outputs a detection result to the hydraulic pressure control unit 57.

  The hydraulic control unit 57 determines whether or not the labyrinth seal 30 is clogged based on the detection result from the pressure sensor 56. And the rolling torque of the pressure roller 4 represented by μ · f · R is pulsated.

  In conjunction with the rolling torque pulsation of the pressure roller 4, the tangential force of the clogged portion of the labyrinth seal 30 expressed by μ · f · R / r pulsates. When the tangential force pulsates, a repetitive load and a variable load are applied to the pulverized coal between the rotating labyrinth ring 16 and the fixed labyrinth ring 21, and between the rotating labyrinth ring 16 and the fixed labyrinth ring 21. The pulverized coal is sheared by the rotating labyrinth ring 16 and the fixed labyrinth ring 21 or is ground and pulverized.

  By crushing the pulverized coal between the rotating labyrinth ring 16 and the fixed labyrinth ring 21, clogging of the labyrinth seal 30 is eliminated, and the pulverized pulverized coal is sent to the classification chamber 32 by seal air from the space 23. Released. The pressure sensor 56 detects that the pressure in the seal air flow path 22 has returned to normal, and outputs the detection result to the hydraulic pressure control unit 57.

  When the hydraulic control unit 57 receives a detection result from the pressure sensor 56 that the pressure of the seal air flow path 22 is normal, that is, the clogging of the labyrinth seal 30 has been eliminated, the pulsation of the pressing force of the hydraulic cylinder 29 is detected. The control is stopped, the pressure receiver 18 is pressed again with a constant force, and the pulverization process is continued.

  As described above, the pressure sensor 56 constantly detects the pressure of the seal air in the seal air flow path 22 and feeds back the detection result to the hydraulic pressure control unit 57. The hydraulic pressure control unit 57 according to the detection result. Since the pressing force of the labyrinth seal 30 is changed, the pulverized coal packed in the labyrinth seal 30 changes the rotation of the pressure roller 4 due to the fluctuation of the pressing force of the hydraulic cylinder 29, that is, the rotating labyrinth ring 16 and the fixed portion. The pulsation of the tangential force between the labyrinth rings 21 is crushed or ground between the fixed labyrinth ring 21 and the rotating labyrinth ring 16 and discharged into the classification chamber 32 by seal air. Therefore, the processing is not continued for a long time while the labyrinth seal 30 is packed with pulverized coal, and the rotating labyrinth ring 16 and the fixed labyrinth ring 21 are continued by continuing the processing while the labyrinth seal 30 is packed with pulverized coal. Can be prevented from being worn, and the pressure roller 4 from being prevented from rotating.

  In this embodiment, the pressure of the seal air passage 22 is detected, and the pressing force of the hydraulic cylinder 29 is changed based on the detection result. Therefore, it is necessary to change the pressure roller unit 5 itself. In addition, the present invention can be easily applied to the existing pressure roller unit 5.

  Furthermore, clogging of the labyrinth seal 30 occurs only when the operating conditions are significantly changed, and since the occurrence frequency is low, special processing is applied to the rotating labyrinth ring 16 and the fixed labyrinth ring 21. However, it goes without saying that the anti-rotation labyrinth ring 16 and the fixed labyrinth ring 21 can be stably applied for a long period of time by applying an anti-wear process.

  In addition, although the said Example demonstrated the vertical mill which grind | pulverizes massive coal, it cannot be overemphasized that this invention can be implemented also with respect to grinding | pulverization of massive objects, such as limestone.

DESCRIPTION OF SYMBOLS 1 Crushing table 4 Pressure roller 5 Pressure roller unit 7 Holding part 8 Roller shaft 10 Vertical mill 17 Shaft holding part 22 Seal air flow path 28 Roller pressurizing device 29 Hydraulic cylinder 30 Labyrinth seal 56 Pressure sensor 57 Hydraulic control part

Claims (2)

  A housing that forms a classification chamber, a pulverizing table that is housed in a lower portion of the housing and is driven to rotate by a table driving device, a shaft holding portion that rotatably holds the pressure roller, the pressure roller, and the shaft holding A labyrinth seal provided between the sections, a roller pressing means for pressing the pressure roller against the pulverizing table and pulverizing the lump on the pulverizing table, and a control for controlling the pressing force of the roller pressing means The labyrinth seal is composed of a rotating labyrinth ring provided on the pressure roller and a fixed labyrinth ring provided on the shaft holding portion, and the control unit is configured to push the roller pressing means. A vertical mill characterized in that a tangential force acting between the rotating labyrinth ring and the fixed labyrinth ring is pulsated by changing a pressure.   The vertical mill according to claim 1, further comprising a detector that detects a seal pressure of the labyrinth seal, wherein the control unit varies the pressing force of the roller pressing unit based on a detection result from the detector.

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