JP4953067B2 - Control method of vertical crusher - Google Patents

Description

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

  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, regardless of whether the pulverizer is of the pressure type (method of blowing gas into the pulverizer with a fan) or negative pressure type (method of sucking the gas in the pulverizer with a fan), the vertical pulverizer is usually It is preferable to stop the operation after all the raw materials on the table have been paid out, but in practice, even if some of the raw materials remain on the table, the operation is stopped by stopping the motor after a certain time has elapsed. In most cases.

  For example, when an attempt is made to stop the vertical crusher, a stop command is first issued for the raw material supply device that feeds the raw material into the vertical crusher, and then a stop command is transmitted to the vertical crusher after a certain time has elapsed. Is done.

However, in the case of the conventional stopping method described above, the table rotation of the vertical grinder stops after a certain time, and until the stop, the table rotation speed, the air volume by the fan, In addition, the rotation speed of the separator continues to move under a certain condition.
Therefore, the rotary table continues to move at the rated speed until the vertical crusher stops after a certain time has elapsed, during which the rotary table in the vertical grinder rotates at the rated speed. In spite of this, the raw material put on the table is cut off, and the thickness of the raw material layer on the table is extremely thin.

  Therefore, the phenomenon that the crushing roller hits the table surface occurs from when the raw material supply device stop command is transmitted until the vertical crusher stops, and noise is generated. There are many cases where this noise becomes a problem because the noise is large depending on whether the grinding roller is provided with a mechanical stopper or not.

  In addition, when the inside of the vertical crusher is inspected, even if the supply of new raw materials is stopped when the vertical crusher is stopped, a large amount of the circulating material remains in the vertical crusher. It is accumulating. Since this deposited material is a fine powder, it may spontaneously ignite, and there is a risk of an ignition and an explosion at the time of restart. Therefore, when stopping, a considerable amount of water is put into the vertical crusher. Measures such as were carried out.

  However, during operation, the vertical pulverizer is often heated, and by injecting cold water into the heated vertical pulverizer, the equipment material of the vertical pulverizer breaks into metal due to thermal shock, etc. There was also a problem that occurred. Therefore, when the vertical crusher is stopped, how to suppress the generation of noise and mill vibration and how to leave no fine powder in the vertical crusher has become a major issue.

  The present invention has been made in view of the above requirements, and suppresses the noise of the vertical crusher that is likely to occur during the operation of the vertical crushing operation, thereby reducing the amount of raw material remaining in the crusher. It is related with the control method of a vertical crusher suitable for stopping in a safe state.

In order to achieve the above object, a method for controlling a vertical crusher according to the present invention includes:
(1) A raw material provided on a rotary table having a plurality of rotatable grinding rollers is ground between the rotary table and the grinding roller, and the ground raw material is provided below the rotary table. A vertical crusher control method for blowing up gas from a gas introduction port and taking it out together with gas from a product outlet provided above the rotary table. When stopping the vertical crusher, the vertical crusher The supply of new raw materials to the machine is stopped, the electric motor that drives the rotary table is gradually reduced from the rated rotation speed, and gas is introduced into the machine from the gas introduction port provided at the lower part of the pulverizer. Then, the air volume of the fan discharged from the outlet provided above the pulverizer and the rotational speed of the separator are gradually decreased in accordance with the decrease in the rotational speed of the electric motor .

(2) In the method for controlling a vertical crusher according to (1), the electric motor that drives the rotary table is gradually decreased from the rated rotational speed in a stepwise manner.

According to the present invention, the pulverization roller hits the table surface by gradually reducing the number of rotations of the rotary table from when the raw material supply device stop command is transmitted until the vertical crusher stops. Generation can be suppressed and noise can be reduced.
Moreover, by reducing the rotational speed of the table at the same time as reducing the rotational speed of the separator, the circulating raw material held in the vertical crusher is purged (or blown out) by the suction force of the fan, and the raw material remaining on the table Therefore, the problem that fine powder is ignited in the stopped pulverizer can be suppressed.

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. 3 is a graph showing the relationship between the air volume and the friction coefficient, FIG. 4 is a graph showing the relationship between the speed of the rotary table and the dynamic friction coefficient, and FIG. 5 is a graph showing the relationship between the frequency ratio and the vibration amplification coefficient.
FIG. 6 is a graph showing the noise level when the table rotation speed is gradually reduced by inverter control, FIG. 7 is a graph showing the relationship between the table rotation speed, fan power, and separator rotation speed, and FIG. It is a graph which shows the noise level at the time of reducing a table rotation speed by a prior art.

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.

  In the embodiment shown in FIG. 1, the electric motor 2M is a system that can be variable-speed by an inverter power supply (not shown), and the electric motor 2M 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 embodiment will be described with a focus on differences from the prior art.
The vertical crusher 1 used in the first embodiment has three crushing rollers, a table rotation speed of 73 RPM, a crushing roller center diameter D of 0.4 m, and a table diameter T. Is 0.64 m.

  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 1 is again caught 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 when stopping the vertical crusher 1 will be described.
First, in the embodiment of the vertical pulverizer 1 according to the present invention, when the vertical pulverizer 1 is stopped, the supply of a new raw material sent from the raw material hopper 20 into the vertical pulverizer 1 is stopped. By controlling an inverter power source (not shown), the electric motor 2M that drives the rotary table 2 is gradually reduced from the rated rotational speed.

  In the present embodiment, the circulating raw material held in the vertical crusher 1 is further exhausted by further reducing the rotational speed of the separator 14 at the same time as reducing the rotational speed 2 of the table. Since the amount of the raw material remaining on the rotary table 2 can be reduced by purging with the suction force of the fan 89, problems such as ignition of fine powder in the stopped vertical crusher 1 can be suppressed. In addition, if the suction amount of the exhaust fan 89 is reduced in accordance with the reduction in the rotational speed of the separator 14, the particle size of the raw material discharged out of the vertical crusher greatly changes compared with that during normal operation. This is the preferred form.

6 and 8 show noise levels when the rotation speed of the turntable 2 is gradually lowered and stopped, and when the conventional stop method is used.
When the inverter power supply is used to gradually reduce the rotational speed of the turntable 2, the noise level is clearly lower and the effect is recognized.

Here, in the case of the conventional stopping method, as described above, the phenomenon that the crushing roller 3 hits the table surface after the stop command of the raw material supply device is transmitted until the vertical crusher 1 stops. Occurs, and noise is generated.
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). According to the present embodiment, the rotational speed of the rotary table 2 is gradually reduced during a certain time required for discharging the raw material in the vertical crusher 1 to the outside of the machine. Since the friction coefficient of the raw material is increased and, as a result, slipping is less likely to occur in the pulverizing part, it is considered that there is an effect of suppressing noise of the vertical pulverizer 1.

  For this reason, when the vertical crusher 1 is stopped, the supply of new raw material sent from the raw material hopper 20 into the vertical crusher 1 is stopped and the rotation speed of the turntable 2 is rated. By gradually reducing the rotational speed from the rotational speed, and reducing the rotational speed of the separator 14 accordingly, the circulating raw material held in the vertical crusher 1 is purged by the suction force of the exhaust fan 89, Reducing the amount of raw material remaining on the turntable 2 is effective in preventing noise and preventing dangers such as explosions.

  In the present embodiment, the inverter power supply is used to gradually reduce the rotation speed of the turntable 2 at a constant rate from the rated rotation speed and stop the rotation table 2, but the rotation speed of the turntable 2 is gradually reduced from the rated rotation speed. The method of reducing is not limited to this, and for example, a method in which the number of rotations of the turntable 2 is decreased in steps from the rated number of rotations and stopped may be used.

  By the way, the relationship between the friction coefficient and the vibration of the vertical crusher 1 tends to be the starting point of vibration and noise when the friction coefficient is lowered. In addition to the friction coefficient, the vibration that is the source of noise generated in the vertical crusher 1 can also be considered as follows.

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

Moreover, as shown in FIG. 5, it turns out that it changes with the ratio of the vibration amplification coefficient M, the vibration frequency ((omega)), and the frequency ((omega) 0) of a grinding | pulverization layer.
Normally, in FIG. 5, 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 inner molecule of the denominator numerator ω / ω0 is lowered, the vibration amplification coefficient is reduced, so that vibration of the vertical crusher 1 can be suppressed.

  As described above, as a method for suppressing or suppressing vibration and noise, 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 ability of the vertical crusher 1 can be maximized by setting the rotational speed to an appropriate speed according to the raw material properties.

  That is, when the noise of the vertical crusher 1 increases, if the rotational frequency of the rotary table 2 is arbitrarily reduced, the excitation frequency is reduced, and the vibration amplification coefficient is reduced, the cause of vibration and noise Can be eliminated.

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 an air volume and a friction coefficient. 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. It is a graph showing the noise level by this embodiment. It is a graph which shows the relationship between table rotation speed, fan motive power, and separator rotation speed. It is a graph showing the noise level by a prior art.

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 controller

Claims (2)

The raw material supplied to the rotary table with a plurality of freely pulverizing rollers is pulverized between the rotary table and the pulverizing roller, and
A control method for a vertical crusher that blows up the pulverized raw material with a gas introduced from a gas inlet provided below the rotary table and takes out the gas together with a gas from a product outlet provided above the rotary table,
When stopping the vertical pulverizer, the supply of new raw materials to the vertical pulverizer is stopped, and the electric motor that drives the rotary table is gradually reduced from the rated rotational speed, and provided at the lower part of the pulverizer. The air volume of the fan introduced into the machine through the gas inlet and discharged from the outlet provided above the pulverizer through the separator unit , and the rotational speed of the separator are adjusted in accordance with the decrease in the rotational speed of the electric motor. A control method for a vertical crusher characterized by gradually lowering.   The method for controlling a vertical crusher according to claim 1, wherein the electric motor for driving the rotary table is decreased stepwise from the rated rotational speed and gradually decreased.

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