JP4919158B2 - Vertical crusher control method and vertical crusher - Google Patents

Description

  The present invention relates to a control method and a control apparatus for a vertical crusher that mainly pulverizes coal, oil coke, limestone, slag, clinker, cement raw materials, chemicals, etc. as raw materials. TECHNICAL FIELD The present invention relates to a vertical crusher control method suitable for preventing or suppressing abnormal vibrations that are likely to occur when finely pulverizing and a vertical crusher suitable for carrying out the control method.

  Conventionally, a crusher called a vertical crusher (sometimes referred to as a vertical mill or a vertical roller mill) has been widely used as a crusher for crushing coal, oil coke and the like.

  In recent years, in particular, the number of cases in which raw materials are finely pulverized by a vertical pulverizer is increasing, and the number of vertical pulverizers having a classification mechanism in the vertical pulverizer is increasing. As a vertical crusher equipped with a classification mechanism, a conventional technique as disclosed in Patent Document 1 is known.

Japanese Patent Laid-Open No. 5-104012

  The vertical pulverizer shown in Patent Document 1 conveys and raises the pulverized raw material by an airflow blown from the lower part of the pulverizer, and is also conveyed by the airflow by a classification mechanism arranged at the upper part in the vertical pulverizer. This is a vertical pulverizer of a type that selects only fine powder from raw materials and takes it out of the apparatus, and is a type of vertical pulverizer generally called an air sweep type.

  Hereinafter, the structure of the air swept type vertical crusher disclosed in Patent Document 1 will be briefly described. The vertical crusher disclosed in Patent Document 1 includes a rotary separator having a plurality of rotary blades as a classification mechanism above a rotary table, and vertically penetrates the central axis of the rotary separator. The material input chute is arranged. And it is comprised so that a raw material can be injected | thrown-in on a turntable from a raw material inlet through a raw material injection chute (it may be called supply).

  The raw material supplied to the center of the rotary table from above the rotary table by the raw material charging chute moves toward the outer periphery of the rotary table while drawing a spiral trajectory on the rotary table. A dam ring is provided on the outer peripheral edge of the rotary table and is configured to maintain a required raw material thickness on the rotary table, so that the raw material moved to the outer peripheral part of the rotary table is dammed by the dam ring, It is bitten by the rotary table and grinding roller and crushed.

  In addition, a part of the raw material that is pulverized by the rotary table and the crushing roller gets over the dam ring that is provided around the outer edge of the rotary table, and is a ring that is a gap between the outer peripheral portion of the upper surface of the rotary table and the casing. Head to the passage (sometimes called an annular space).

During the operation of the vertical pulverizer, gas is introduced into the vertical pulverizer from the gas inlet port provided at the lower part of the pulverizer by a blower such as an exhaust fan. It is discharged out of the machine from the upper outlet. As a result, in the casing of the vertical crusher, a gas flow is generated from the lower side of the rotary table toward the upper side of the rotary separator.
Accordingly, a part of the raw material that has reached the annular passage over the dam ring is blown up by the gas flow and rises in the casing.

  The airflow rising in the casing is an airflow rising while turning due to the influence of the rotating separator. Therefore, among the raw materials blown up by the airflow, the raw material having a large diameter and a large weight falls below the casing due to the weight, or deviates from the airflow by the centrifugal force generated in the raw material itself by swirling by the airflow. For example, it falls below the casing and cannot pass through the rotating separator. The material that has failed to pass through the rotating separator and has fallen is again caught in the grinding roller and crushed. In addition, a raw material with a small diameter passes through between the blades, passes through the rotary separator, and is taken out from the upper outlet.

  A raw material having a particularly large particle diameter among the raw materials that have reached the annular passage falls below the rotary table from the annular passage and is taken out of the vertical crusher 1 from the lower outlet, and then a conveyor such as a bucket elevator. Then, the material is again introduced from the raw material inlet of the mold grinder and pulverized.

  By the way, the above-described conventional technique is a technique for avoiding vibration by adjusting the thickness of the raw material layer on the turntable, but abnormal vibration occurs even though the raw material layer thickness on the turntable does not change. There is.

In particular, in order to reduce the driving time of a hydraulic pump or the like and save labor, when the tension hydraulic pressure of a hydraulic cylinder that presses a grinding roller against a rotary table is generated by a pressure accumulator such as an accumulator, vibration tends to occur. was there.
Conventionally, the tension oil pressure of the hydraulic cylinder is always monitored with a pressure sensor, and when the oil pressure drops below a specified value, the hydraulic pump is moved to supply the pressure accumulator to the original pressure value. However, if the pressure of the accumulator falls below a certain value from the set value, abnormal vibration is likely to occur.

The cause of this is not clear, but the point at which the tension oil pressure of the crushing roller once decreased is the starting point of self-excited vibration, and vibration exceeding normal has occurred. It was thought that when it was raised, the vibration was encouraged and increased.
For this reason, conventionally, once the tension hydraulic pressure of the crushing roller is reduced, the tension hydraulic pressure is not increased suddenly from that state, and the tension hydraulic pressure is gradually increased so that vibration does not increase. It was.

  However, a relatively large self-excited vibration continues while the tension hydraulic pressure recovers to the set value, and a control method and apparatus for a vertical crusher that eliminates the self-excited vibration as soon as possible has been demanded.

  The present invention has been made in view of the above demands, and is an abnormal vibration of a vertical crusher that is likely to occur when a tension hydraulic pressure that deviates from a set value by more than a specified value to the original set value. The present invention relates to a method for controlling a vertical crusher suitable for effectively preventing the occurrence of a vertical crusher, and a vertical crusher suitable for implementing the control method.

In order to achieve the above object, a method for controlling a vertical crusher according to the present invention includes:
(1) In a control method of a vertical crusher that includes a plurality of freely rotatable crushing rollers and crushes the raw material supplied on the rotating table between the rotating table and the crushing roller, the crushing roller is pressed against the rotating table. When the tension oil pressure of the hydraulic cylinder is detected and the tension oil pressure becomes smaller than a preset value by a predetermined value or more, the tension oil pressure is increased to a set value after decelerating the rotation speed of the rotary table, After the tension hydraulic pressure rises to the set value, the rotational speed of the rotary table is increased until the speed before deceleration is reached.

The vertical crusher according to the present invention is
(2) In a vertical crusher that includes a plurality of rotatable crushing rollers and crushes the raw material supplied on the rotary table between the rotary table and the crushing roller, a hydraulic cylinder that presses the crushing roller against the rotary table; A pressure accumulator that generates tension oil pressure in the hydraulic cylinder, a hydraulic pump that supplies pressure oil to the pressure accumulator, and a pressure sensor that measures the tension oil pressure, and detects the tension oil pressure of the hydraulic cylinder by the pressure sensor; When the tension hydraulic pressure becomes smaller than a preset value by a predetermined value or more, the rotational speed of the rotary table is decelerated, and then the pressure oil in the accumulator is increased by the hydraulic pump to increase the tension hydraulic pressure of the hydraulic cylinder. After increasing to the set value, the rotational speed of the rotary table is increased to the speed before deceleration.

  According to the present invention, in the vertical crusher, the abnormal vibration of the vertical crusher that is likely to occur when the tension hydraulic pressure of the crushing roller once deviated from the set value by more than the specified value is restored to the original set value is effective. Can be prevented.

Hereinafter, an example of a preferred embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram for explaining a schematic structure of a vertical crusher according to the present embodiment. FIG. 2 is a diagram conceptually illustrating a pulverization system using a vertical pulverizer according to this embodiment. FIG. 3 is a graph showing the relationship between the speed of the rotary table and the dynamic friction coefficient, and FIG. 4 is a graph showing the relationship between the frequency ratio and the vibration amplification coefficient.

Hereinafter, the preferable structure of the vertical crusher 1 which concerns on embodiment of this invention is demonstrated.
The vertical crusher 1 used in the present embodiment, as shown in FIG. 1, is a casing 1B that forms the outline of the vertical crusher 1, a rotary table 2, and an upper surface of the rotary table 2 (also referred to as a rotary table upper surface 2A). There are a plurality of conical crushing rollers 3 disposed at positions where the outer peripheral portion is equally divided in the circumferential direction, a speed reducer 2B installed under the vertical crusher 1, and a rotary table via the speed reducer 2B. 2, a variable speed electric motor 2 </ b> M that drives 2, and a control panel 50 that controls the rotational speed of the electric motor 2 </ b> M.

  The crushing roller 3 is connected to the piston rod 9 of the hydraulic cylinder 8 via an upper arm 6 pivotally attached to the lower casing by a shaft 7 and a lower arm 6A formed integrally with the upper arm 6. The hydraulic cylinder 8 is pressed in the direction of the rotary table upper surface 2A by the operation of the hydraulic cylinder 8, and is rotated by being driven by the raw material through the rotary table upper surface 2A.

A separator 14 and a raw material charging port 35 are provided at the center upper portion of the upper surface 2A of the rotary table of the casing 1B, and a raw material charging chute 13 is arranged so as to penetrate the central axis of the separator 14 up and down. Thus, the raw material can be charged (also referred to as supply) from the raw material charging port 35 to the rotary table upper surface 2A via the raw material charging chute 13.
In addition, the separator 14 includes a plurality of blades 14A arranged in a reverse truncated cone shape having a diameter increased upward with the rotation axis of the separator 14 as a center, with a predetermined interval between them, and can be freely operated by a driving device (not shown). It can be rotated.

  The raw material charged from the raw material charging chute 13 is moved to the outer peripheral portion of the rotary table upper surface 2A while drawing a spiral trajectory on the rotary table upper surface 2A, and is bitten by the rotary table upper surface 2A and the pulverizing roller 3 to be pulverized. Then, a part of the raw material caught by the rotary table upper surface 2A and the pulverizing roller 3 passes over the dam ring 15 provided around the outer edge of the rotary table upper surface 2A, and the outer peripheral portion of the rotary table upper surface 2A. It goes to the annular passage 30 (which may be referred to as the annular space 30), which is a gap with the casing. Here, a gas inlet 33 for introducing gas is provided below the rotary table 2 of the casing 1B, and an upper outlet 39 for taking out the raw material pulverized together with the gas is further provided above the rotary table. Provided.

  During operation of the vertical crusher 1, gas (air in the present embodiment) is introduced from the gas inlet 33 to pass through the separator 14 from the lower side of the rotary table in the casing 1B, and the upper outlet. A gas stream flowing to 39 is generated.

The raw material charged into the vertical crusher 1 and a part of the raw material crushed by the rotary table 2 and the crushing roller 3 and over the dam ring 15 are blown up by the gas to rise in the casing, and the rotary separator 14 To reach.
Here, the raw material having a large diameter and a large weight cannot pass through the blades 14A of the separator 14 and falls below the separator 14, is re-engaged by the grinding roller 3, and is pulverized. Then, it passes through the separator 14 through the blades 14 A arranged with a gap, and is taken out from the upper outlet 39.

  Further, a part of the raw material having a maximum particle size that does not get caught in the crushing roller 3 and reaches the annular passage as it is falls from the annular passage 30 to the lower side of the rotary table and passes through the lower take-out port 34 of the vertical crusher 1. It is taken out.

  Of course, the model of the vertical crusher 1 that can be used in the present embodiment is not limited to that described above. For example, the vertical crusher is a tire-type vertical crusher in which the shape of the crushing roller 3 is a spherical shape. 1 may be sufficient. Further, the separator 14 may be a fixed type according to the required particle size of the product. Alternatively, a type without a separator may be used.

  In the present embodiment, the hydraulic cylinder 8 that presses the crushing roller 3 against the rotary table 2, and the accumulator 61 that supplies the hydraulic cylinder 8 as the tension hydraulic pressure that generates the tension hydraulic pressure that presses the crushing roller 3 against the rotary table 2 is supplied with pressure oil to the accumulator 61. And a pressure sensor S1 that measures the tension oil pressure.

Next, the control panel 50 provided in the vertical crusher 1 will be briefly described.
In the embodiment shown in FIG. 1, the control panel 50 receives a signal from the pressure sensor S <b> 1, and when the pressure value is smaller than a set value by a predetermined value, the control panel 50 is a signal for reducing the rotational speed to the motor 2 </ b> M. And then a control device 50A for transmitting an operation signal to the hydraulic pump 36. In the embodiment shown in FIG. 1, the electric motor 2M is a variable speed type, and is connected to the rotary table 2 via a speed reducer 2B. Therefore, the electric motor 2M can freely change the rotation speed of the turntable 2 by freely changing the rotation speed according to a signal transmitted from the control device 50A of the control panel 50.

Next, a preferred example of the grinding system according to the present embodiment will be described with reference to FIG.
The pulverization system shown in FIG. 2 includes a vertical pulverizer 1, a raw material hopper 20, a bucket elevator 25, a raw material hopper 21, an exhaust fan 89, and the like.
The raw material stored in the raw material hopper 20 is put into the vertical crusher 1 through the bucket elevator 25 and the raw material hopper 21 and pulverized. The raw material pulverized in the vertical pulverizer 1 is moved upward in the vertical pulverizer 1 by the gas flow from the exhaust fan 89 and taken out from the product outlet 39 to the outside. Among the raw materials charged into the vertical crusher 1, some raw materials that have not been taken out from the product take-out port 39 are taken out from the lower take-out port 34 to the bucket. It is again put into the vertical crusher 1 through the elevator 25 and the raw material hopper 21 and pulverized.

Hereinafter, the control method of the vertical crusher 1 according to the present invention will be described with reference to the first embodiment, focusing on the differences from the prior art.
The raw material supplied to the central portion of the rotary table is moved toward the outer peripheral portion of the rotary table 2 by the raw material charging chute 13, and is caught by the rotary table 2 and the pulverizing roller 3 and pulverized. A part of the raw material caught by the rotary table 2 and the grinding roller 3 passes over the dam ring 15 provided around the outer edge of the rotary table, and the gap between the outer peripheral portion of the upper surface of the rotary table 2A and the casing 1B. It heads for the annular passage 30 which is.

  During operation of the vertical crusher 1, gas is introduced into the machine by an exhaust fan 89 from a gas inlet 33 provided at the lower part of the crusher, and is provided above the crusher via a rotating separator. It is discharged out of the machine from the outlet. As a result, in the casing 1 </ b> B of the vertical crusher 1, a gas flow is generated from the lower side of the rotary table 2 to the upper side of the rotary separator 14. Therefore, a part of the raw material that has passed over the dam ring 15 and reached the annular passage 30 is blown up by the gas flow and rises in the casing 1B.

  The airflow rising in the casing 1B is influenced by the rotary separator 14 and is an airflow rising while turning. Therefore, among the raw materials blown up by the air current, the raw material having a large diameter and a large weight falls below the casing 1B due to the weight, or deviates from the air current due to centrifugal force generated in the raw material itself due to swirling by the air current. Then, it falls below the casing 1B and cannot pass through the rotary separator 14.

  The material that has failed to pass through the rotary separator 14 and circulates in the vertical crusher is again entrapped in the crushing roller 3 and crushed. Alternatively, after being dropped from the annular passage below the rotary table and taken out of the vertical crusher 1 from the lower outlet, it is charged again from the raw material inlet of the mold crusher via a conveyor such as a bucket elevator. And crushed. In addition, a raw material with a small diameter passes through between the blades, passes through the rotary separator, and is taken out from the upper outlet.

Hereinafter, a control method of the vertical crusher 1 will be described.
First, in the first embodiment of the vertical crusher according to the present invention, the set value and the specified value are set to the control panel 50 for the tension hydraulic pressure applied to the hydraulic cylinder 8 before the control operation.
The specified value in this case is to adjust the lower limit value of the tension oil pressure, and when the measured value of the tension oil pressure falls below the set value by more than the specified value, it is a preparatory action for restoring the tension oil pressure. This is the value that triggers entry.
The process for recovering the tension hydraulic pressure will be described later, but from the viewpoint of preventing vibration, the specified value should be small, and if it decreases even a little, the hydraulic pump 63 is driven to supply the pressure oil, and the hydraulic cylinder It is better to prevent the tension oil pressure of 8 from decreasing.
However, from the viewpoint of energy saving, it is better that the specified value is larger, and driving the hydraulic pump 63 after waiting for the tension hydraulic pressure to drop to a certain level can reduce the number of times and time the hydraulic pump is driven. it can. The specified value may be determined as appropriate in consideration of the aforementioned factors.

Next, during the control operation of the vertical crusher 1, the tension oil pressure of the hydraulic cylinder 8 is always detected by the pressure sensor S1.
The pressure value of the tension oil pressure detected by the pressure sensor S1 is transmitted to the control panel 50 and compared with a preset set value in the control device 50A.
As a result of the comparison, when the measured value is smaller than the set value by a predetermined value or more, the control device 50A transmits a signal for decreasing the rotational speed to the electric motor 2M, and the electric motor 2M receives the signal and sets the rotational speed. Since the speed is lowered, the rotation speed of the turntable 2 is reduced.
Next, the control device 50 </ b> A transmits a drive signal to the hydraulic pump 36, and the hydraulic pump 36 that receives the signal supplies pressure oil to the accumulator 61.
The accumulator 61 that has been supplied with the pressure oil increases the pressure and raises the tension hydraulic pressure of the hydraulic cylinder 8. When the pressure sensor S1 detects that the tension hydraulic pressure has increased to the set value, the control device 50 stops driving the hydraulic pump 36, and then sends a signal for increasing the rotational speed to the electric motor 2M. The rotational speed of the rotary table 2 is increased until the speed before deceleration is reached.

  Here, FIG. 3 shows the relationship between the rotational speed of the rotary table and the dynamic friction coefficient (dynamic friction coefficient between the grinding roller and the raw material). When the rotational speed decreases, the friction coefficient between the grinding roller 3 and the raw material increases. In addition, slipping is less likely to occur in the pulverizing part.

  Further, increasing the pulverization force (vibration force) causes the vertical pulverizer vibration, but the vibration generated in the vertical pulverizer can be considered as follows in addition to the friction coefficient.

A displacement amount (A) is obtained by dividing the excitation force by the spring constant.

That is, it can be seen that the vibration amplification coefficient varies depending on the ratio of the vibration frequency (ω) and the frequency (ω0) of the pulverized layer as shown in FIG.
Normally, in FIG. 4, ω / ω0 is operated at 1.0 or less (= resonance point or less), so the frequency of the pulverized layer (ω0) is not changed (the same particle size is changed in proportion to the product particle size). By reducing the excitation frequency (ω), the vibration amplification coefficient can be reduced.

  Since the vibration frequency (ω) is proportional to the rotation speed of the crushing roller, the vibration frequency can be reduced by changing the table rotation speed to be synchronized. As a result, if the denominator, the inner numerator of the numerator ω / ω0 is lowered, the vibration amplification coefficient decreases, so that the vertical crusher vibration can be suppressed.

  As described above, as a method for suppressing or suppressing vibration, there are a friction coefficient securing method and an excitation frequency control method. What is common to these two methods is the rotational speed of the rotary table 2, and the capacity of the vertical crusher can be maximized by setting the rotational speed to an appropriate speed according to the raw material properties.

Therefore, when the tension hydraulic pressure of the vertical crusher deviates from the set value and becomes smaller than the specified value, the tension hydraulic pressure is increased after the table rotation speed is decreased. The vibration factor can be eliminated before the crusher vibration is generated.
In other words, if the rotational speed of the turntable 2 is reduced, abnormal vibration is unlikely to occur even if the tension oil pressure is increased rapidly. Therefore, the tension hydraulic pressure can be quickly recovered from the state in which the tension hydraulic pressure has decreased.

It is a principal part longitudinal cross-sectional view which shows embodiment of the vertical crusher which concerns on this invention. It is a figure which illustrates notionally the crushing system using the vertical crusher concerning this embodiment. It is a graph showing the relationship between the speed of a rotary table, and a dynamic friction coefficient. It is a graph showing the relationship between a frequency ratio and a vibration amplification coefficient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Vertical crusher 2 Rotary table 3 Crushing roller 13 Raw material input chute 14 Rotating separator 15 Dam ring 1B Casing 20 Raw material hopper (for new raw material supply)
21 Raw material hopper 25 Bucket elevator 30 Annular passage 33 Gas inlet 89 Exhaust fan (blower)
34 Lower outlet 35 Raw material inlet 39 Product outlet (upper outlet)
50 control panel 50A control device S1 pressure sensor 61 accumulator (pressure accumulator)
63 Hydraulic pump 65 Oil tank

Claims (2)

In a control method of a vertical crusher that includes a plurality of rotatable crushing rollers and feeds the raw material supplied on the rotary table between the rotary table and the crushing roller,
The tension hydraulic pressure of the hydraulic cylinder that presses the crushing roller against the rotary table is detected, and when the tension hydraulic pressure is smaller than a preset value by a preset value, the rotational speed of the rotary table is reduced before the tension hydraulic pressure is reduced. A control method for a vertical crusher, which is increased to a set value, and after the tension oil pressure has increased to a set value, the rotational speed of the rotary table is increased to a speed before deceleration. In a vertical crusher that includes a plurality of rotatable crushing rollers and feeds the raw material supplied on the rotary table between the rotary table and the crushing roller,
A hydraulic cylinder that presses the crushing roller against the rotary table, a pressure accumulator that generates tension oil pressure in the hydraulic cylinder, a hydraulic pump that supplies pressure oil to the pressure accumulator, and a pressure sensor that measures the tension oil pressure,
When the tension oil pressure of the hydraulic cylinder is detected by the pressure sensor and the tension oil pressure becomes smaller than a preset value by a predetermined value or more, the rotational speed of the rotary table is decelerated and the hydraulic pump A vertical crusher that increases the pressure oil pressure to increase the tension oil pressure of the hydraulic cylinder to a set value, and then increases the rotational speed of the rotary table to the speed before deceleration.

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