WO2013175952A1

WO2013175952A1 - Vertical mill

Info

Publication number: WO2013175952A1
Application number: PCT/JP2013/062738
Authority: WO
Inventors: 田村　雅人; 千草照屋
Original assignee: 株式会社Ihi
Priority date: 2012-05-23
Filing date: 2013-04-24
Publication date: 2013-11-28
Also published as: JP5929506B2; JP2013244417A

Abstract

The present invention is provided with: a pulverizing table that is accommodated in a housing and is rotatably driven by a table drive device; a plurality of pressure rollers that apply pressing pressure on to the pulverizing table and pulverize aggregated material; and a plurality of roller pressure units that apply the pressing pressure to the pressure rollers. The roller pressure units have: a pressure cylinder that applies pressure to the pressure roller; a hydraulic circuit connected to the pressure cylinder; and a damping device (28) provided in the hydraulic circuit. The damping device has a first orifice (34), which has a first orifice hole (36) and a plurality of relief holes (37), and a second orifice (35) that is provided so as to overlap the first orifice and which closes the relief holes. The second orifice is a deformable plate, and the plate deforms during an increase in hydraulic pressure, pulling away from the first orifice and opening the relief holes.

Description

Vertical mill

The present invention relates to a vertical mill that pulverizes lumps such as coal and limestone into fine powder, and more particularly to a vertical mill that presses a pressure roller against a pulverizing table by hydraulic pressure.

In a coal-fired boiler using coal as fuel, massive coal is pulverized by a vertical roller mill into pulverized coal, and the pulverized coal is supplied to a burner which is a combustion device together with primary air.
The vertical mill includes a housing, a crushing table housed in the housing, a pressure roller pressed against the crushing table, a pressure cylinder provided in the housing and pressing the pressure roller against the crushing table, The coal is supplied to the pulverizing table, and the coal is pulverized by the pressure roller.
In a vertical mill, when the rolling resistance of the pressure roller is large, or when the rolling resistance fluctuates, slip occurs between the crushing table and the pressure roller, and the pressure roller is caused by the slip. May generate excitation vibration.
Conventionally, there is a roller mill disclosed in Patent Document 1 that suppresses self-excited vibration of a grinding roller. In the roller mill, a damper device including a throttle valve and an accumulator is connected to the rod side of a hydraulic cylinder to which pressurized oil is supplied, and the vibration energy of the pressurized oil is absorbed by the damper device to Vibration is suppressed.
However, when foreign matter is mixed into the material to be crushed and the pressure roller bites into the foreign matter, the hydraulic pressure may increase so much that it does not compare with the fluctuation of the hydraulic pressure generated by self-excited vibration. When the foreign matter to be bitten is an iron lump of about 58 mm, for example, when a bolt having a size of 57.6 mm is bitten, for example, a hydraulic pressure of about 270 MPa is applied to a hydraulic cylinder having a pressure resistance of 27.5 MPa. appear. Therefore, when a damping device that absorbs the vibration of the pressure roller by restricting the oil flow like the conventional vertical mill is used, the excessive hydraulic pressure generated cannot be absorbed, and the hydraulic cylinder There is a risk of causing damage to the hydraulic system.

JP-A-11-285649

In view of such circumstances, the present invention provides a vertical mill that prevents breakage of a hydraulic system due to a rapid increase in hydraulic pressure.

The present invention includes a crushing table housed in a housing and driven to rotate by a table driving device, a plurality of pressure rollers that are pressed onto the crushing table and crush the lump, and a plurality of pressure rollers that press the pressure roller. A pressure unit for applying pressure to the pressure roller, a hydraulic circuit connected to the pressure cylinder, and a damping provided in the hydraulic circuit. A first orifice having a first orifice hole and a plurality of escape holes, and a second orifice that overlaps with the first orifice and closes the escape hole. And the second orifice is a deformable plate, and the plate is deformed when the hydraulic pressure is increased and is separated from the first orifice to open the escape hole. Than is.
Further, the present invention relates to a vertical mill in which the escape hole is provided on a circumference concentric with the first orifice hole, and the second orifice is a circular plate that closes the escape hole. .
Further, according to the present invention, the escape hole is provided on a straight line parallel to and symmetric with respect to the diameter of the first orifice hole, and the second orifice is a rectangular plate that closes the escape hole. It relates to a mold mill.
Furthermore, according to the present invention, a plurality of slits are formed at equal intervals in the peripheral portion of the second orifice, and a deformed portion is formed between the adjacent slits. The deformed portion is a pressure that flows through the plurality of escape holes. The present invention relates to a vertical mill that is independently deformed by the oil pressure of the oil.

According to the present invention, a crushing table housed in a housing and rotated by a table driving device, a plurality of pressure rollers pressed on the crushing table and crushing a lump, and the pressure rollers are pressed. A plurality of roller pressing units, the roller pressing unit being provided in the hydraulic circuit, a pressure cylinder that applies pressure to the pressure roller, a hydraulic circuit connected to the pressure cylinder, and A damping device, a first orifice having a first orifice hole and a plurality of escape holes, and a second orifice that overlaps with the first orifice and closes the escape hole. An orifice, and the second orifice is a deformable plate, and the plate is deformed when the hydraulic pressure is increased and is separated from the first orifice to open the escape hole. Even when the pressure suddenly increases, the passage of the pressure oil is expanded by opening the relief hole, and the hydraulic pressure acting on the pressurizing cylinder and the hydraulic circuit can be reduced. Damage to the hydraulic system such as the pressure cylinder and the hydraulic circuit can be prevented.

FIG. 1 is a schematic view showing an example of a vertical mill according to an embodiment of the present invention.
FIG. 2 is a hydraulic circuit diagram showing the main part of the embodiment of the present invention.
3 (A) and 3 (B) are schematic front sectional views of the damping device according to the embodiment of the present invention. FIG. 3 (A) shows the damping device in a normal state, and FIG. ) Shows a damping device when the hydraulic pressure is increased.
FIG. 4 is a view taken in the direction of arrows AA in FIG.
FIG. 5 is a schematic sectional side view showing a first modification of the damping device.
FIG. 6 is a schematic sectional side view showing a second modification of the damping device.

Embodiments of the present invention will be described below with reference to the drawings.
First, an example of a vertical mill 1 will be briefly described with reference to FIG.
A crushing table 3 is provided at the lower part of the housing 2, and the crushing table 3 is rotationally driven by a table driving device 10. Further, a pressure roller 4 rolls on the crushing table 3, and the pressure roller 4 is radially provided at a position equally divided into three in the circumferential direction, and is pressed against the crushing table 3 by a roller pressure unit 5. Is done.
A coal supply / exhaust portion 6 is provided on the upper side of the housing 2, and a pipe-like chute 7 is provided on the rotational axis of the crushing table 3, and lump coal from the chute 7 is the center of the crushing table 3. To be supplied. A classifier 8 that rotates about the chute 7 is provided at the top of the housing 2.
Coal supplied from the chute 7 onto the pulverizing table 3 is moved in the outer peripheral direction by centrifugal force, pulverized by the pressure roller 4 to become powder, and the pulverized coal is sprayed from the outer periphery of the pulverizing table 3. It rises as a pulverized coal stream 9 on the rising primary air for conveyance.
The pulverized coal stream 9 is classified into pulverized coal having a predetermined particle size or less by the classifier 8, and the classified pulverized coal is pulverized coal burner (see FIG. Not shown). Coarse coal particles having a predetermined particle size or more fall on the crushing table 3 and are pulverized again by the pressure roller 4.
The roller pressure unit 5 is provided through a journal cover 12 that constitutes a part of the housing 2, and a roller arm 13 is tiltably provided on the journal cover 12. The roller pressing unit 5 is provided on the roller arm 13. The roller pressure unit 5 includes a pressure cylinder 14 and a push rod 15, and the push rod 15 is provided to be slidable in the axial direction.
The rod 16 of the pressure cylinder 14 is in contact with the proximal end of the push rod 15, and the distal end (center side end) of the push rod 15 is in contact with the roller arm 13. The pressing force is transmitted to the pressure roller 4 through the push rod 15 and the roller arm 13.
Further, the vertical mill 1 has a control device 17, and the control device 17 supplies pressure oil to the pressure cylinder 14 so that the pressure transmitted to the pressure roller 4 becomes a predetermined pressure. The hydraulic circuit 21 (see FIG. 2) is controlled.
The hydraulic circuit 21 will be described with reference to FIG.
One end of the pressure oil supply path 22 communicates with the cylinder head side of the pressure cylinder 14, and the other end communicates with the oil tank 23. A hydraulic pump 24, a first on-off valve 25, and a pressure detector 26 are provided from the upstream side of the pressure oil supply path 22. A bypass path 27 is provided to bypass the first on-off valve 25 and connect the upstream side and the downstream side of the first on-off valve 25, and the bypass path 27 is provided with a damping device 28.
An accumulator 29 communicates with the pressure oil supply path 22 upstream of the first on-off valve 25 or upstream of the damping device 28.
One end of the oil drain passage 31 is in communication with the rod 16 side of the pressure cylinder 14, and the other end is in communication with the oil tank 23. A second on-off valve 32 is provided in the oil drain passage 31.
Here, the hydraulic circuit 21 functions as pressure oil supply means to the pressure cylinder 14 and also functions as self-excited vibration suppression means.
3 (A), 3 (B), and 4, the details of the damping device 28 will be described.
The damping device 28 includes a cylindrical orifice case 33 through which pressure oil flows, and a first orifice 34 and a second orifice 35 provided in the orifice case 33.
The first orifice 34 is a disk-like member provided so as to close the pressure oil flow path of the orifice case 33, and a circular first orifice hole 36 is formed in the center thereof. The pressure oil flow path is reduced by one orifice hole 36 so that the flow of the pressure oil is restricted. Further, as shown in FIG. 4, a plurality of escape holes 37 are formed around the first orifice hole 36 at a predetermined angular pitch on the concentric circumference of the first orifice hole 36.
The second orifice 35 is an elastically deformable plate, for example, a plate made of steel, a plate made of stainless steel, or the like, and is attached upstream of the first orifice 34. The second orifice 35 is smaller in diameter than the first orifice 34 and has a diameter that completely closes all the escape holes 37. The plate thickness of the second orifice 35 is set so as to be deformable with an increase in hydraulic pressure, and a second orifice having the same diameter as or slightly larger than the first orifice hole 36 at the center. A hole 38 is formed.
Further, as shown in FIG. 4, the first orifice 34 and the second orifice 35 are superposed such that the first orifice hole 36 and the second orifice hole 38 are concentric, The first orifice hole 36 is fixed around a plurality of fixing tools 39 such as bolts.
At this time, as shown in FIG. 3 (A), the peripheral portion of the second orifice 35 closes the upstream end of the escape hole 37, and also shown in FIG. 3 (B). Similarly, when the pressure applied to the second orifice 35 exceeds a predetermined pressure, it is bent and deformed with the fixing tool 39 as a fulcrum, and all the escape holes 37 are opened at once.
Next, the operation of the hydraulic circuit 21 will be described.
The control device 17 opens the first on-off valve 25 and the second on-off valve 32, and the pressure oil increased in pressure by the hydraulic pump 24 passes through the pressure oil supply path 22 to the pressure cylinder 14. By being supplied to the cylinder head side, the pressure roller 14 is pressed onto the crushing table 3 by the pressure cylinder 14, and the coal is crushed.
At this time, the oil pressure in the pressure oil supply passage 22 is detected by the pressure detector 26. When the oil pressure in the pressure oil supply passage 22 reaches a predetermined pressure, the control device 17 The first on-off valve 25 is closed. In this state, as shown in FIG. 3A, the second orifice 35 is in close contact with the first orifice 34 and closes the upstream end of the escape hole 37.
If self-excited vibration occurs while the first on-off valve 25 is closed during the coal pulverization process, the pressure roller 4 vibrates up and down, and the vibration of the pressure roller 4 is further affected by the roller arm 13. , Transmitted to the push rod 15 and the rod 16.
The vibration of the rod 16 appears as the vibration of the piston 14a of the pressurizing cylinder 14. The vibration of the piston 14a fluctuates the volume on the cylinder head side, and the pressure oil on the cylinder head side enters and exits. Pressure oil corresponding to the change in volume flows into and out of the accumulator 29 through the bypass passage 27 and the damping device 28, but flows through the first orifice hole 36 and the second orifice hole 38. Thus, the vibration is attenuated by the viscous resistance of the pressure oil.
Therefore, the self-excited vibration can be suppressed by forcibly circulating the pressure oil supplied to the pressure cylinder 14 to the damping device 28.
Thus, even when self-excited vibration occurs or when self-excited vibration occurs, the self-excited vibration is suppressed and the operation is continued without stopping the vertical mill 1. Can be made.
Further, when the pressure roller 4 bites foreign matter during the coal pulverization process, the pressure roller 4 rides on the foreign matter and is rapidly displaced upward. The displacement of the pressure roller 4 is transmitted to the roller arm 13, the push rod 15, and the rod 16, and the hydraulic pressure in the cylinder head side of the pressure cylinder 14, the pressure oil supply path 22, and the bypass path 27 is rapidly increased. However, as shown in FIG. 3B, the rising pressure acts on the second orifice 35 through the escape hole 37 to bend and deform the second orifice 35. As the second orifice 35 is deformed, a gap is formed between the first orifice 34 and the second orifice 35, the upstream end of the escape hole 37 is opened, and the damping device 28 The flow path is enlarged.
Therefore, even if the pressure roller 4 bites foreign matter and the hydraulic pressure rises suddenly in a state where the circulation of the pressure oil is restricted by the damping device 28, the flow of the pressure oil is caused by the relief hole 37. By expanding the path, the hydraulic pressure can be reduced, and damage to the hydraulic system such as the pressurizing cylinder 14 and the pressure oil supply path 22 due to a sudden increase in hydraulic pressure can be prevented.
The second orifice 35 is preferably manufactured so as to be bent and deformed within the range of elastic deformation. By bending and deforming the second orifice 35 within the range of elastic deformation, the second orifice 35 can be used repeatedly without being damaged, and the durability of the damping device 28 can be improved. . Alternatively, the damping device 28 may be replaced, and when the hydraulic pressure higher than a predetermined pressure is generated, the second orifice 35 may be damaged and the relief hole 37 may be opened.
The second orifice 35 preferably has such a rigidity and shape (strength) that it does not deform when self-excited vibration occurs but deforms only when the hydraulic pressure suddenly increases when foreign matter is caught. For example, the second orifice 35 is curved so as to be convex toward the upstream side, and is attached so as to correct the curvature with the fixing tool 39, so that the second orifice 35 is initially bent. By setting the strength so that the second orifice 35 is not deformed when the self-excited vibration is generated, it is possible to prevent the pressure oil flow path from expanding when the self-excited vibration is generated and the efficiency of vibration damping to be deteriorated.
FIG. 5 shows a first modification of the damping device 28.
In the first modification, a plurality of slits 41 are formed at a predetermined angular pitch toward the center at the peripheral edge of the second orifice 35, and the hydraulic pressure increases between the

slits

41, 41 of the second orifice 35. It becomes the deformation part 42 at the time.
The deforming portion 42 is positioned on the escape hole 37 when the second orifice 35 is fixed to the first orifice 34, and the deformable portions 42 block the escape holes 37, respectively. Yes.
In the first modified example, when the oil pressure of the pressure cylinder 14 and the pressure oil supply passage 22 rises rapidly due to the foreign matter biting of the pressure roller 4, the pressure holes 4 circulate through the relief holes 37. Since the deforming portions 42 are independently deformed by the pressure oil, the strength of the second orifice 35 can be easily set.
FIG. 6 shows a second modification of the damping device 28.
In the second modification, the second orifice 35 is a rectangular plate, and the escape hole 37 is positioned on a straight line parallel to and symmetric with respect to the diameter of the first orifice hole 36. It is drilled to do. When the second orifice 35 is fixed to the first orifice 34, the escape hole 37 is closed by the end of the short side of the second orifice 35, and the escape hole 37 is The two orifices 35 are fixed so as to be parallel to the short side.
In the second modification, the second orifice 35 can be easily manufactured. Further, since the escape hole 37 is formed so as to be parallel to and symmetric with respect to the diameter of the first orifice hole 36, the bending direction of the second orifice 35 becomes constant, The strength of the second orifice 35 can be easily set.
The second orifice 35 in the second modification may be a rectangular plate other than a rectangle, for example, a square plate.
Needless to say, the slit 41 may be formed in the second orifice 35 of the second modification as in the first modification.

By superposing the second orifice on the first orifice and closing the escape hole with the deformable plate-like second orifice, the second orifice is separated from the escape hole when the hydraulic pressure suddenly increases. Thus, the flow path of the pressure oil can be expanded to reduce the hydraulic pressure, and can be applied to prevent damage to the hydraulic system.

DESCRIPTION OF SYMBOLS 1 Vertical mill 2 Housing 3 Crushing table 4 Pressure roller 5 Roller pressure unit 14 Pressure cylinder 17 Control device 21 Hydraulic circuit 28 Damping device 33 Orifice case 34 First orifice 35 Second orifice 36 First orifice hole 37 Escape hole 38 Second orifice hole 41 Slit 42 Deformed portion

Claims

A crushing table housed in a housing and driven to rotate by a table driving device, a plurality of pressure rollers that are pressed onto the crushing table and crush the lump, and a plurality of roller pressure units that press the pressure roller The roller pressure unit includes a pressure cylinder that applies pressure to the pressure roller, a hydraulic circuit connected to the pressure cylinder, and a damping device provided in the hydraulic circuit. The damping device has a first orifice having a first orifice hole and a plurality of escape holes, and a second orifice that is overlapped with the first orifice and closes the escape hole, The second orifice is a deformable plate, and the plate is deformed when the hydraulic pressure is increased and is separated from the first orifice to open the relief hole. .
The vertical mill according to claim 1, wherein the escape hole is provided on a circumference concentric with the first orifice hole, and the second orifice is a circular plate closing the escape hole.
2. The saddle type according to claim 1, wherein the escape hole is provided on a straight line parallel to and symmetric with respect to the diameter of the first orifice hole, and the second orifice is a rectangular plate for closing the escape hole. mill.
A plurality of slits are formed at equal intervals in the peripheral portion of the second orifice, and a deformed portion is formed between the adjacent slits, and the deformed portions are independent of each other by the hydraulic pressure of the pressure oil flowing through the plurality of escape holes. The vertical mill according to claim 2 or 3, wherein the vertical mill is deformed.