JP2002186868A - Method and apparatus for controlling operation of vertical roller mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable continuous operation. SOLUTION: A vertical roller mill 1 is constituted by providing a raw material charging port 3 having a quantitative supply device 4 connected to the upper part thereof and providing a grinding table 7 and the grinding rollers 9, which is brought into contact with the grinding table 7 under pressure to be rotated so as to follow the grinding table 7, to the lower part of a casing 2 having a gas inlet 10 provided to the lower end part thereof and providing a discharge port 15 equipped with a rotary separator 14 to the top part of the casing 2. An upper limit sensor 25 is provided to the lower end level position of the rotary separator 14 of the casing 2 and a lower limit sensor 26 is provided to the upper end level position of the grinding roller 9 and the respective sensors can detect the interface 30 of the upper bed low in raw material density and the lower bed high in raw material density formed in the casing 2 by a raw material 18a relatively low in bulk specific gravity. A controller 29 issuing a command to the drive motor 23 of the quantitative supply device 4 corresponding to the detection signals from the respective sensors 25 and 26 is provided. When the interface 30 is detected by the upper limit sensor 25, the supply of the raw material is stopped and, thereafter, when the interface 30 is detected by the lower limit sensor 26, the supply of the raw material is started.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling the operation of a vertical roller mill for controlling the operation according to the amount of raw material stored in the casing of the vertical roller mill. The present invention relates to a method and an apparatus for controlling the operation of a vertical roller mill for performing a pulverizing process.

[0002]

2. Description of the Related Art Conventionally, among the pulverizers used for pulverizing various raw materials such as cement raw materials and calcium carbonate into granules or powder, a vertical roller mill has been used as a type having relatively high pulverization efficiency. Are known.

As shown in FIG. 2, an example of the vertical roller mill 1 is such that a raw material is supplied to one side of an upper end portion of a cylindrical casing 2 so that the raw material can be supplied toward a central portion of the casing 2. The opening 3 is provided obliquely downward, and a fixed amount supply device 4 is connected to the raw material input port 3. On the other hand, a grinding table 7 and a grinding roller 9 are provided at a lower position in the casing 1 for grinding. The table 7 is driven to rotate at a low speed by a drive motor 5 via a speed reducer 6, and the crushing roller 9 can be moved up and down by operating a fluid pressure cylinder 8. A gas inlet 10 is provided on a lower side wall of the casing 2 below the upper surface of the gasket 7, and a gas supply line 12 for leading a gas (cool air) 11 from a gas supply unit (not shown) is connected. ,casing In the center of the top, a discharge port 15 for discharging gas and fine powder is provided, and a rotary separator 14 driven by a drive motor 13 is provided below the discharge port 15. The raw material pulverized by the gas 9 and blown up by the gas 11 is separated by the separator 14, and the fine powder is guided to the discharge port 15. For example, a raw material 18 such as a cement raw material or an ore having a bulk specific gravity of 1.3 or more such as calcium carbonate is supplied to a quantitative supply device 4.
When the raw material is put on the pulverizing table 7 through the raw material charging port 3 and pulverized between the pulverizing table 7 and the pulverizing roller 9, the pulverized raw material pulverized into the casing 2 has a gas inlet 10. Is blown up to the upper part of the casing 2 by the flow of the gas 11 which is introduced and rises toward the discharge port 15. Only the particles 19 are discharged together with the gas 11 from the discharge port 15, sent to the bag filter 16 through the discharge line 17, and separated and recovered from the gas 11 by the bag filter 16. The crushed raw material larger than the desired particle size separated by the rotary separator 14 falls again on the crushing table 7 as the raw material 18 to be further crushed. Thereby, it is to perform the grinding process to continue. Reference numeral 20 denotes a raw material supply port 3 and a fixed amount supply device 4
A rotary valve for preventing backflow of the gas 11 into the crusher; Is shown.

In the vertical roller mill 1 described above, the raw material 18 charged into the casing 2 from the fixed quantity supply device 4 is continuously pulverized. However, the pulverization efficiency depends on the properties of the raw material and other factors. If it drops,
A large amount of the raw material 18 may accumulate inside the casing 2 and the level of the raw material 18 in the casing 2 may increase. In this case, when the level of the raised raw material 18 reaches the lower end of the rotary separator 14, the rotation of the separator 14 is hindered and a load is applied, and the drive motor 13
However, there is a possibility that the roller mill 1 may trip and the continuous operation of the roller mill 1 becomes impossible. For this reason, in order to allow the roller mill 1 to be stably operated continuously, the amount of the raw material supplied from the quantitative supply device 4 is adjusted in accordance with a change in the level of the raw material 18 stored in the casing 2, and the raw material is collected in the casing 2. Raw material 1
It is desired that the level 8 be controlled so as to be within a predetermined level range.

Conventionally, a differential pressure gauge 22 is provided between the gas supply line 12 immediately before the gas inlet 10 and the discharge line 17 immediately after the discharge port 15.
The pressure of the gas 11 at the gas inlet 10 and the outlet 15
A controller 24 for detecting a pressure difference from the pressure of the gas 11 in the section and for giving a control command to a drive motor 23 of the quantitative supply device 4 based on a detection signal from the differential pressure gauge 22
So that a predetermined differential pressure is set in advance in the controller 24, and when the level of the raw material 18 stored in the casing 2 rises, the raw material 18 flows from the gas inlet 10 to the outlet 15 in the raw material 18. The resistance of the gas 11 flow increases. At this time, when the differential pressure detected by the differential pressure gauge 22 becomes larger than the differential pressure preset in the controller 24, the controller 2
4, a command is issued to the drive motor 23 to reduce the number of revolutions, the supply speed of the fixed-quantity supply device 4 is reduced, the amount of raw material charged is reduced, and the raw material level inside the casing 2 is reduced. The decrease is determined by the decrease in the differential pressure detected by the differential pressure gauge 22. On the other hand, when the level of the raw material 18 stored in the casing 2 decreases, the flow of the gas 11 easily blows through the casing 2 and Since the differential pressure detected by the pressure gauge 22 is smaller than the differential pressure preset in the controller 24, in this case, the controller 2
4, a command is issued to the drive motor 23 to increase the number of rotations, the supply speed of the fixed amount supply device 4 is increased to increase the amount of raw material input, and the level of the raw material inside the casing 2 is increased. In order to increase the differential pressure, the amount of the raw material charged is adjusted so that the differential pressure detected by the differential pressure gauge 22 matches the set value.

[0006]

However, the differential pressure gauge 22
The above-described conventional operation control method of a vertical roller mill in which the amount of raw material charged is adjusted so that the differential pressure detected by the above-mentioned method matches a preset value is performed when the raw material level inside the casing 2 rises. Since it is assumed that the resistance of the gas flow from the gas inlet 10 to the outlet 15 becomes large in the inside, in the roller mill 1, for example, an ore having a bulk specific gravity of about 1.3, such as a cement raw material or calcium carbonate. When the raw material 18 is pulverized as a raw material 18, good operation control can be performed. However, when a raw material having a low bulk specific gravity, for example, a raw material having a bulk specific gravity of 0.3 or less is ground by the roller mill 1, The raw material is a gas 11 flowing from the gas inlet 10 to the outlet 15 even if it is not pulverized.
Can flow more easily in the casing 2, so that even if the raw material level rises, the flow of the gas 11 hardly becomes a resistance. Therefore, the differential pressure detected by the differential pressure gauge 22 with respect to the change in the raw material level inside the casing 2. For example, even if the raw material level in the casing 2 rises, a time lag occurs before the differential pressure gauge 22 detects the increase in the differential pressure. There is a problem that the raw material level further rises and easily reaches the lower end of the rotary separator 14.

In view of the above, the present invention provides a method of controlling the operation of a vertical roller mill capable of controlling the input amount of raw material in accordance with the amount of raw material stored in a casing, with respect to a vertical roller mill used for pulverizing raw material having a low bulk specific gravity. It is intended to provide a device.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention crushes a raw material supplied from a fixed-quantity supply device between a crushing table and a crushing roller at a lower portion in a casing, and crushes the raw material. The operation of a vertical roller mill in which pulverized material is blown up by a gas introduced from the lower end and raised, and only a powder having a desired particle size is classified and discharged by a rotary separator at an upper end. In the control method, when the interface between the low-concentration upper layer and the low-concentration lower layer of the raw material having a low bulk specific gravity formed in the casing rises to the lower end level of the rotary separator, the raw material is supplied by the quantitative supply device. An operation control method and apparatus for a vertical roller mill that stops or reduces the amount of raw material supplied.

[0009] Even when the amount of the raw material accumulated in the casing increases during the pulverizing process of the raw material having the small specific gravity by the vertical roller mill, even if the amount of the raw material stored in the casing is increased, the interface between the lower layer and the upper layer having a low raw material concentration remains at the lower level of the rotary separator. At that point,
Since the supply of the raw material is stopped or the supply amount of the raw material is reduced, and the rise of the interface is suppressed, the rotary separator is prevented from sinking in the lower layer where the raw material concentration is high.

Further, the interface between the upper layer having a low concentration of the raw material having a low bulk specific gravity and the lower layer having a high density formed in the casing is as follows:
By using a method and an apparatus for starting the feeding of the raw material by the fixed amount supply device when the raw material is lowered to near the upper end level of the grinding roller, the amount of the raw material between the grinding table and the grinding roller is reduced. In addition, it is possible to prevent the crushing table and the crushing roller from approaching each other, thereby preventing the possibility of mill vibration from occurring.

[0011]

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

FIG. 1 shows an embodiment of a method and an apparatus for controlling the operation of a vertical roller mill according to the present invention. Similar to the vertical roller mill 1 shown in FIG. The lower part of the cylindrical casing 2 provided with the provided raw material inlet 3 and the gas inlet 10 connected to the gas supply line 12 at the lower end side wall is driven by the drive motor 5 through the speed reducer 6 at a low speed. A disk-shaped crushing table 7, and a crushing roller 9 which rotates while following the rotation of the crushing table 7 while being pressed against the upper surface of the crushing table 7. In a vertical roller mill having a structure in which a separator 14 and a raw material and gas discharge port 15 are provided, a raw material having a low bulk specific gravity, for example, a raw material 18a having a bulk specific gravity of 0.3 or less is suitable for pulverizing treatment. An upper limit sensor 25 is installed on the side wall of the casing 2 at the lower end level position of the rotary separator 14, and a lower limit sensor 26 is installed on the side wall of the casing 2 at the upper end level position of the crushing roller 9. Each of the upper limit sensor 25 and the lower limit sensor 26 is configured to include, for example, swinging detection blades 27 and 28 so that a change in resistance acting on the swinging detection blades 27 and 28 can be detected. And a controller 29 for giving a control command to the drive motor 23 of the quantitative supply device 4 based on the detection signals from the upper limit sensor 25 and the lower limit sensor 26.

Here, the raw material 18a to be pulverized by the vertical roller mill 1 has a low bulk specific gravity, so that it goes from the gas inlet 10 to the discharge port 15 in the casing 2 even when it is not pulverized. The raw material 18a, which is easily blown up by the gas flow but is not sufficiently pulverized to a desired particle size, falls immediately after being blown up by the gas flow and immediately suspended even if it is suspended. An upper layer having a low raw material concentration (raw material filling rate with respect to space) in which the raw material 18a blown up in
A lower layer having a high raw material concentration in which 8a is accumulated and accumulated is formed.

Therefore, when the interface 30 between the upper layer and the lower layer having different concentrations of the raw material 18a rises and reaches the installation level of the upper limit sensor 25 as shown by the dashed line in FIG. 1, the swing of the detection blade 27 is hindered. Then, the resistance is increased and the upper limit sensor 25 detects the resistance. Therefore, a stop command is given from the controller 29 to the drive motor 23 to stop the supply of the raw material by the quantitative supply device 4. On the other hand, when the interface 30 is lowered to the position where the lower limit sensor 26 is installed, as shown by the two-dot chain line in FIG. 1, the lowering of the interface 30 is detected by the lower limit sensor 26 due to a decrease in resistance acting on the detection blade 28. Therefore, a command to start driving is given from the controller 29 to the driving motor 23 to start feeding the raw material by the quantitative supply device 4.

19a is the raw material 1 by the roller mill 1.
8a is obtained by pulverizing 8a, classifying it by a rotary separator 14, and selecting the powder having a desired particle size or less. Other configurations are the same as those shown in FIG. 2, and the same components are denoted by the same reference numerals.

During normal operation of the vertical roller mill 1, a raw material 18a having a small bulk specific gravity is charged into the casing 2 through the raw material charging port 3 by the constant-quantity feeding device 4, and the raw material 18a
a is pulverized between a pulverizing table 7 and a pulverizing roller 9 which are pressed into contact with each other in the same manner as in the pulverizing process of the raw material 18 by the vertical roller mill 1 shown in FIG. The powder 1 which is blown up to the upper part of the casing 2 by the flow of the gas 11 toward the discharge port 15 from the 10 and has a desired particle size or smaller among the blown-up raw material pulverized materials.
Only 9a is classified and classified by the rotary separator 14,
The raw material pulverized material, which is discharged from the outlet 15 and separated from the gas 11 by the bag filter 16 and is larger than a desired particle size, is dropped on the pulverizing table 7 and
The pulverization process is continuously performed.

During operation of the vertical roller mill 1, the casing 2
When the level of the interface 30 rises due to an increase in the amount of the raw material 18a stored inside, the level is detected when the interface 30 reaches the installation level of the upper limit sensor 25, that is, the lower limit level position of the rotary separator 14. Further, since the supply of the raw material by the constant-quantity supply device 4 is stopped, the interface 30 is prevented from further rising, so that the rotary separator 14 is disposed under the interface 30 where the raw material 18a has a high concentration. Is prevented from occurring, so that the motor 13 of the rotary separator 14 can be prevented from tripping, and the vertical roller mill 1 can be stably operated continuously.

Thereafter, by operating the roller mill 1 in a state where the charging of the raw material is stopped, the raw material 18a is pulverized, and the granular material 19a having a desired particle size or less is discharged. The amount of the accumulated raw material 18a gradually decreases, and the level of the interface 30 decreases. On this occasion,
The interface 30 is at the installation level of the lower limit sensor 26, that is,
When the lowering of the crushing roller 9 to the upper end level position is detected by the lower limit sensor 26, the supply of the raw material by the fixed quantity supply device 4 is started, so that the further lowering of the interface 30 level is prevented. This can prevent the amount of the raw material 18a between the crushing table 7 and the crushing roller 9, that is, the thickness of the layer of the raw material 18a, from being reduced. Therefore, it is possible to prevent the occurrence of mill vibration beforehand.

It should be noted that the present invention is not limited to only the above embodiment, and the upper limit sensor 25 and the lower limit sensor 2
6 is a type in which the interface 30 is detected based on a change in resistance acting on the detection blades 27 and 28 oscillated in the casing 2. Position and roller 9 for crushing
If the interface 30 generated based on the difference in the concentration of the raw material 18a can be detected at the upper end level position, an ultrasonic sensor or a wire having a weight at the lower end is suspended from the top of the casing 2 so that the weight is A sensor that detects the level of the interface 30 based on a change in the tension of the wire when it reaches the lower layer where the raw material concentration is high, or a probe rope (surface wave transmission line) is vertically extended in the casing 2 and the probe Any type of sensor such as a sensor that transmits a surface wave to the rope from the top side of the casing 2 and, when a part of the surface wave is reflected at the interface 30, can detect the level of the interface 30 from the arrival time of the reflected wave. Can be adopted,
Although the lower limit sensor 26 is shown as being installed at the upper end level position of the crushing roller 9, when the crushing is performed between the crushing table 7 and the crushing roller 9 according to the properties of the raw material 18 a to be crushed. Since the minimum amount of the raw material 18a to be stored in the casing 2 to prevent the occurrence of mill vibration is different, the installation level of the lower limit sensor 26 depends on the properties of the raw material 18a to be ground. It may be moved up and down in the vicinity.
When 0 is detected, the controller 29 controls the drive motor 23 of the fixed-quantity supply device 4 to stop to stop the supply of the raw material. However, the controller 29 issues a deceleration command to the drive motor 23. Giving, control may be performed to reduce the amount of raw material input by the quantitative supply device 4,
In addition, it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0020]

As described above, according to the method and apparatus for controlling the operation of the vertical roller mill of the present invention, the raw material supplied from the fixed amount supply device is transferred between the pulverizing table and the pulverizing roller in the lower part of the casing. The powder is blown up by a gas introduced from the lower end of the casing and raised, and only the powder having a desired particle size is classified and discharged by the rotary separator at the upper end. In the vertical roller mill operation control method, when the interface between the low-concentration upper layer and the low-concentration lower layer of the raw material having a low bulk specific gravity formed in the casing rises to the lower end level of the rotary separator, a fixed amount is supplied. Since the method and apparatus for stopping the supply of the raw material by the apparatus or reducing the amount of the raw material supplied are used, during the pulverization processing of the raw material having a low specific gravity by the vertical roller mill, Even if the amount of the raw material accumulated in the shing increases, the raw material supply is stopped or the raw material supply amount is reduced when the interface between the lower raw material concentration layer and the deep upper raw material layer reaches the lower end level of the rotary separator. Since the rise of the interface can be suppressed, the rotary separator can be prevented from sinking in the lower layer having a high raw material concentration, and the motor of the rotary separator trips. Fear can be prevented beforehand,
It has an excellent effect of being able to carry out a stable continuous operation of a vertical roller mill, and the interface between the lower layer and the lower layer of the raw material having a low bulk specific gravity formed in the casing is formed by the grinding roller. By reducing the amount of the raw material between the crushing table and the crushing roller by adopting a method and an apparatus for starting the supply of the raw material by the fixed amount supply device when the crushing table is lowered to near the upper end level, the crushing table is reduced. And the crushing roller can be prevented from approaching, whereby the effect of generating mill vibration can be prevented beforehand.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of a method and an apparatus for controlling the operation of a vertical roller mill according to the present invention.

FIG. 2 is a schematic diagram illustrating a conventional vertical roller mill operation control method and apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical roller mill 2 Casing 3 Raw material input port 4 Quantitative feeder 7 Pulverizing table 9 Pulverizing roller 10 Gas inlet 14 Rotary separator 15 Outlet 18, 18a Raw material 19, 19a Powder 19, 19a Granular material 25 Upper limit sensor 26 Lower limit sensor 29 Control Vessel 30 interface

Claims (4)

[Claims] 1. A raw material supplied from a fixed amount supply device is pulverized between a pulverizing table and a pulverizing roller in a lower part of a casing, and a pulverized material is blown up by gas introduced from a lower end of the casing and raised. In a method for controlling the operation of a vertical roller mill in which only a granular material having a desired particle size is classified and discharged by a rotary separator at an upper end portion, a raw material having a small bulk specific gravity formed in a casing. When the interface between the low-concentration upper layer and the high-concentration lower layer rises to the lower end level of the rotary separator, the supply of the raw material by the quantitative supply device is stopped, or the amount of the raw material supplied is reduced. Control method of die roller mill. 2. When the interface between an upper layer having a low concentration and a lower layer having a low concentration of a raw material having a low bulk specific gravity formed in a casing is lowered to a level near an upper end level of a crushing roller, the raw material is supplied by a quantitative supply device. The operation control method for a vertical roller mill according to claim 1, wherein the operation is started. 3. A raw material supplied from a fixed amount supply device is pulverized between a pulverizing table and a pulverizing roller in a lower part of a casing, and a pulverized material is blown up by a gas introduced from a lower end of the casing and raised. In a vertical roller mill operation control device in which only a granular material having a desired particle size is classified and discharged by a rotary separator at an upper end portion, a raw material having a small bulk specific gravity is formed in a casing. An upper limit sensor is provided at a required position in the casing to detect that the interface between the upper layer having a lower concentration and the lower layer having a higher concentration has risen to the lower end level of the rotary separator,
An operation control device for a vertical roller mill, further comprising a controller for giving a stop command to the quantitative supply device based on a detection signal of the upper limit sensor. 4. A lower limit sensor for detecting that an interface between an upper layer having a low density and a lower layer having a high density formed of a material having a low bulk specific gravity is reduced to a level near an upper end level of a crushing roller. At the required position in the
4. The operation control device for a vertical roller mill according to claim 3, further comprising a controller for giving a drive start command to the fixed amount supply device based on a detection signal of the lower limit sensor.