JPH0647302A - Operation of vertical type roller mill - Google Patents

Abstract

PURPOSE:To safely operate a vertical type roller mill by previously predicting the vibration generation and preparing vibration preventing countermeasure. CONSTITUTION:An acceleration pick-up meter 10 is installed in the end face of a fulcrum shaft which swings and supports an arm having a crushing roller at the tip part and the sliding of the crushing roller in the rotation direction, wherein the sliding as a prediction of vibration generation is indirectly detected by the acceleration pick-up meter 10. When the acceleration degree signal is put in a comparator 12 from the acceleration pick-up meter 10 and, at the same time, the acceleration degree signal is compared with the set value found exceeding the set value, either the pressing force or the supply amount of the material to be crushed, which are both factors to suppress the vibration generation, or both are adjusted by a controlling apparatus 13 and thus vibration generation in the vertical type roller mill is prevented before vibration, is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of operating a vertical roller mill, and more particularly, to a vertical roller mill capable of easily maintaining a stable operating state by preventing vibration. The present invention relates to a method of operating a roller mill.

[0002]

2. Description of the Related Art In a vertical roller mill, operation is performed by constant mill power control, but in many vertical roller mills, operation by constant mill differential pressure control is adopted. This certainly stabilizes the operation of the vertical roller mill,
If the pulverization status in the mill is represented by a mil differential pressure and the pulverized material amount is controlled to a constant value of the mil differential pressure, the controlled variable mil differential pressure has a poor responsiveness to the pulverized material amount, which is an operating variable. Even if the crushing condition inside the mill changes, the change is transmitted to the mill differential pressure through changes in the amount of stone discharged and the amount of stagnation in the mill, so the constant differential pressure value control becomes a deadly delayed control. There is a problem that the mill differential pressure is not so preferable as a controlled variable from the viewpoint of sensitivity, because the fluctuation of the differential pressure due to the magnitude of the disturbance is small. Therefore, in order to solve such a problem, for example, JP-A-64-3444
A mill control such as that disclosed in Japanese Patent Laid-Open No. 8 and Japanese Patent Laid-Open No. 3-232544 has been proposed.

First, the technique disclosed in Japanese Patent Laid-Open No. 64-34448 is superior in responsiveness and controllability, and it is considered that a variable representative of product grain size may be used as a controlled variable. It was found that vibration, which is one of the controlled variables, represents the crushed state of the object to be crushed by the crushing roller and the crushing table, and the other one, the layer thickness, represents the new feed amount, These three variables, the new feed amount, the mill air amount, and the compressing force of the crushing roller, which have a strong relationship with the two controlled variables of vibration and layer thickness, are used as the operating variables.

More specifically, FIG. 3 of the schematic control system diagram thereof.
As shown in FIG. 2, the vibrometer 11 is provided in the housing of the vertical roller mill M, and the layer thickness gauge 1 is provided on the arm 12 of the crushing roller and the mill body.
3, the new feed supply device 14 has a weighing device 15
To the crushing roller tension pressure adjusting unit 16
7 in the bag filter outlet duct 18
And a damper opening adjustment device 20. Therefore, the signal detected by the vibrometer 11 passes through the filter 21,
Unwanted frequency components are removed and sent to the controller 26. Similarly, the signal from the layer thickness gauge 13 and the weighing device 15
From the tension pressure gauge 17, the signal from the mill air flow measuring device 19, and the signals from the filters 22 and 23, respectively.
It is sent to the controller 26 through 24 and 25. Based on these five signals, the operation amount of the new feed amount, the crushing roller tension pressure, and the mill air amount are calculated in the controller 26 by a predetermined calculation formula, and the tensions of the new feed supply device 14 and the tension are calculated according to the calculated values. The pressure adjusting unit 16 and the damper opening adjusting device 20 for adjusting the mill air flow are automatically controlled.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. 3-232544 is controlled by vibration, which is one of the controlled variables representing the crushed state of the crushed object caught by the crushing roller and the crushing table. As shown in FIG. 4 which is a plan view of a main part of the crushing roller, an auxiliary roller 33 actuated by pressing means is provided on the outer peripheral surface of the crushing table 31 between the crushing rollers 32. However, when the support value of the vibrometer (not shown) mounted on the housing (not shown) of the vertical roller mill exceeds a preset value, the auxiliary roller 33 is pressed by the pressing means (not shown).
The pressing force applied to the crushing table 31 is changed. Therefore, by crushing the raw material with the crushing roller 32 while compressing the raw material particles by the auxiliary roller 33 and deaerating the air present between the particles, the vibration of the vertical roller mill can be suppressed, so that the vertical roller mill Stable operation can be continued.

[0006]

In the technique disclosed in Japanese Patent Laid-Open No. 64-34448 related to the first conventional example,
It is assumed that the vertical roller mill is controlled by using the two variables of layer thickness and vibration as controlled variables. However, since the layer thickness and the vibration have a close inverse correlation, as a result, it is the same as using only the vibration or the layer thickness as the controlled variable, which is wasteful. Considering that it becomes impossible to measure an accurate value gradually, the content to obtain the new feed amount, the pressing force, and the set value change amount of the air flow condition that are the factors that determine the layer thickness by using the vibration as the controlled variable become.

Therefore, there is a time delay in control, and it is very difficult to formulate the relationship between vibration and these control variables, and in addition, such control itself is very difficult.
There is a problem to be solved that grain size control is also difficult. That is, it is preferable that the controlled variables and control variables be easy to control and the number of them be small.

[0008] Also, Japanese Patent Publication No. 3-232 according to the second conventional example.
In the technique disclosed in Japanese Patent No. 544, since the vibration of the vertical roller mill is detected and the pressing force of the auxiliary roller for pressing the powder layer is controlled, the time delay cannot be avoided and the vertical The operating state of the die roller mill cannot be returned to a stable state. That is, there is a problem to be solved in that control is often not in time, which is not always practical.

Therefore, an object of the present invention is to prevent the vertical roller mill from vibrating quickly and easily.
It is an object of the present invention to provide a practical method for operating a vertical roller mill that enables stable operation of the vertical roller mill to be continued.

[0010]

Means for Solving the Problems As a result of intensive studies, the inventors have found that there is a predictive phenomenon that a vertical roller mill starts to vibrate during operation, and predict this predictive phenomenon to prevent proper vibration. It is believed that if measures are taken, the vibration of the vertical roller mill can be surely prevented and the stable operation of the vertical roller mill can be continued.

Therefore, the main feature of the method of operating the vertical roller mill according to the present invention is that the crushing table that is horizontally rotated and the tension cylinder that is swingably supported by the horizontal fulcrum shaft are used. Is supplied by a crushed object supply device between the crushing table and the crushing roller of a vertical roller mill in which a crushing roller is rotatably supported at the crushing table side end of an arm that is swung by the operation of In an operating method of a vertical roller mill for crushing an object to be crushed, an accelerometer for detecting axial movement of the shaft is provided on the fulcrum shaft, and an acceleration signal value from the accelerometer is preset. Compared with the set value, when the acceleration signal value exceeds the set value, the hydraulic pressure of the hydraulic oil for operating the tension cylinder is increased, or Select one of the means or reducing the supply amount of the object to be crushed by the grinding object feeder, or where to operate by them both means.

[0012]

[Operation] In many cases, it is not possible to control the speed of vibration simply by detecting the vibration of the vertical roller mill, and in many cases, the unstable phenomenon itself does not appear in the vibration. The instability phenomenon of the vertical roller mill in which the driving force of the roller mill suddenly changes greatly is caused by the change of the frictional force generated during the material crushing of the crushing roller to the compression crushing, and the vibration occurs. The crushing roller slides in the direction of rotation before the operation, and the vibration is generated by the repetition of such slipping thereafter. In other words, this suggests that it is possible to predict that vibration will occur in the vertical roller mill by detecting the initial lateral slip of the crushing roller.

Therefore, according to the method for operating the vertical roller mill of the present invention, the lateral slip of the roller is indirectly detected as the axial movement of the full-crum shaft by the accelerometer, so that the vibration is generated before the vibration occurs. The occurrence of instability can be predicted. And when the acceleration signal value exceeds the set value,
Either one of increasing the pressure of the hydraulic oil for operating the tension cylinder or increasing the supply amount of the material to be ground by the material to be ground supply device is selected, or operated by both of these means. Therefore, it is possible to prevent the occurrence of vibrations by one operated variable and one operated variable.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for operating a vertical roller mill according to the present invention will be described below with reference to FIG. 1 which is an explanatory view of a mounting state of an accelerometer on a vertical roller mill and FIG. 2 which is an operation control block diagram of the vertical roller mill. To explain, reference numeral 1 shown in FIG. 1 denotes a housing of a vertical roller mill M. A crushing table 2 is rotatably supported inside a lower portion of the housing 1 about a vertical axis, and an upper surface of the crushing table 2 is provided. The crushing roller 3 is rolling on the crushing roller 3, and the crushing object supplied from the crushing object supply device (not shown) to the upper surface of the crushing table 2 is caught between the crushing table 2 and the crushing roller 3. Smash.

The crushing roller 3 is swingably supported on the outside of the housing 1 by a horizontal fulcrum shaft 5 via a bracket, and is swung by a tension cylinder 6 whose bottom side is pivotally attached to the mounting surface side. Arm 4
The vertical roller mill M has a well-known configuration, as is well understood from the above description.

In this embodiment, an accelerometer 10 is attached to the end face of the fulcrum shaft 5 of the vertical roller mill M having the above structure. Therefore, when the crushing roller 3 is slipped in the rotational direction, the slip is transmitted to the fulcrum shaft 5 via the arm 4, so that the accelerometer 10 detects the axial movement of the crushing roller 3 to rotate the crushing roller 3. The slip in the direction can be indirectly detected, and it becomes possible to know in advance that vibration will occur in the vertical roller mill M. The accelerometer 10 is a commercially available product that is easily available, and in this embodiment, for example, the main specifications are that the natural frequency is 14 Hz and the sensitivity is 100 mV / c.
A drip-proof type with m / s, maximum allowable acceleration of 100 m / s ² , and maximum measurement displacement of 1000 μm ^pp was used.

Next, in the operation control system of the vertical roller mill M, as shown in FIG. 2, the acceleration signal from the accelerometer 10 is inputted to the comparator via the amplifier 11, and the set value is inputted from the data table 12a to the comparator. 12 is input. The comparator 12 compares the acceleration signal value with the set value and does not operate when the acceleration signal value is smaller than the set value, but when the acceleration signal value exceeds the set value, an alarm is issued and a controller to be described later. An operation command signal to the vertical roller mill M is output to the No. 13. The set value input to the data table 12a is set based on many years of experience.

The controller 13 is a tension hydraulic pressure controller 13a which issues a command signal to a hydraulic unit (not shown) for supplying hydraulic oil to the tension cylinder 6 so as to increase the hydraulic pressure of the hydraulic oil, and the crushed material. A feed amount adjuster 13b for issuing a command signal to reduce the moving speed of the conveyor to an object supply device (not shown). Further, one of the tension hydraulic pressure adjuster 13a and the feed amount adjuster 13b is used for the above. The operation command signal to the vertical roller mill M is input.

In the operation of the tension oil pressure adjuster 13a and the feed amount adjuster 13b, when an acceleration larger than the set value is detected, first, the tension oil pressure is increased to bring the acceleration detection value to the set value or less. Adjust so that
If this cannot be achieved, the feed amount is further reduced. That is, even if the operation to raise the tension hydraulic pressure is prioritized and the maximum hydraulic pressure determined from the mechanical strength is raised, only the feed amount is adjusted when the acceleration detection value exceeds the set value. As is well understood from the above description, the control system according to this embodiment is extremely simplified as compared with the control system according to the first conventional example.

The operation mode of the above operation control will be described below. The initial lateral slip of the crushing roller 3 is transmitted to the fulcrum shaft 5 via the arm 4, and this is transmitted as an axial motion of the fulcrum shaft 5 to the accelerometer. Detected by 10. Then, the acceleration signal value is input from the accelerometer 10 as an acceleration signal value to the comparator 12 via the amplifier 11, and the input acceleration signal value is compared with a preset value input in advance from the data table 12A, and the acceleration signal When the value exceeds the set value, the comparator 12 sends an operation command signal to the vertical roller mill M to the controller 13.

The controller 13 to which the operation command signal is input is
Tension oil pressure controller 13a and feed amount controller 1 can be selected.
Since the operation command to the vertical roller mill M is transmitted to either one of 3b and 3b, the tension cylinder 6 is generated based on the operation command.
Is increased to lower the pressing force of the crushing roller 3 against the crushing table 2, or the moving speed of the conveyor of the crushed material supply device is decreased to reduce the supply amount of the crushed material.

As described above, it is predicted that vibration will occur before the vertical roller mill M vibrates, and at least one of the pressing force for suppressing the vibration and the supply amount of the crushed object is adjusted. Therefore, it is possible to reliably prevent the occurrence of vibration with one manipulated variable and one manipulated variable without delaying the time and performing difficult control as in the past. It becomes possible to obtain such a powder product having excellent product quality.

[0023]

As described above in detail, according to the operating method of the vertical roller mill according to the present invention, vibration is generated by detecting the lateral slip of the roller by the accelerometer attached to the sieve crumb shaft. The occurrence of instability can be predicted, and either the hydraulic pressure of the working oil of the tension cylinder or the supply amount of the pulverized material, or both are adjusted to suppress vibration. Therefore, unlike the conventional example, there is no time delay in control, and it is possible to prevent vibration from occurring in advance by one manipulated variable and one manipulated variable, so that the occurrence of vibration is prevented quickly and easily,
There is an effect that the stable operation of the vertical roller mill can be continued.

[Brief description of drawings]

FIG. 1 is an explanatory view of a mounting state of an accelerometer on a vertical roller mill according to an embodiment of the present invention.

FIG. 2 is an operation control block diagram of the vertical roller mill according to the embodiment of the present invention.

FIG. 3 is a control system diagram of a vertical roller mill according to a first conventional example.

FIG. 4 is a plan view of a main part of a vertical roller mill according to a second conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Grinding table 3 ... Grinding roller 4 ... Arm 5 ... Fulcrum shaft 6 ... Tension cylinder 10 ... Accelerometer 11 ... Amplifier 12 ... Comparator, 12a ... Data table 13 ... Controller, 13a ... Tension hydraulic regulator, 13b ... Feed amount controller M ... Vertical roller mill

Claims (1)

[Claims] 1. A crushing roller is rotatably supported at the tip of the arm that is oscillated by a horizontally rotating crushing table and a horizontal fulcrum shaft and that is oscillated by the operation of a tension cylinder on the crushing table side. In the method for operating a vertical roller mill of the vertical roller mill configured to crush the material to be crushed supplied by the object to be crushed between the crushing table and the crushing roller, in the full crumb shaft, An accelerometer for detecting movement in the axial direction is provided, and an acceleration signal value from the accelerometer is compared with a preset set value, and when the acceleration signal value exceeds the set value, the tension cylinder Either increase the hydraulic pressure of the hydraulic oil that activates the, or reduce the supply amount of the crushed material by the crushed material supply device, or Or, a method of operating a vertical roller mill characterized by operating by both of these means.