JP2908399B1 - Closed circuit grinding system control method and powder manufacturing apparatus - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To always find an optimum crushing condition when a change in crushing easiness and a particle size of a crushed raw material and a particle size specification of a product occur, and to control a closed-circuit crushing system in accordance therewith, thereby always achieving a high crushing efficiency. It is an object of the present invention to provide a method for controlling a closed-circuit pulverization system and a powder production apparatus that maintain the above-mentioned conditions and eliminate the loss due to mill clogging. SOLUTION: The raw material supply amount P to the crusher, the transport amount Q of the crushed product from the crusher to the classifier or the return amount R of the coarse powder returned from the classifier to the crusher; Based on the fineness S of the product, the crushing characteristics of the raw materials in the crusher are determined, and based on the crushing characteristics, the raw material supply amount P is adjusted so as to optimize the crushed powder passing amount T in the crusher. It is constituted so that.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a closed-circuit pulverizing system in powder production for producing fine powder by pulverizing raw materials, and a powder production apparatus.

[0002]

2. Description of the Related Art FIG. 5 shows a general powder producing apparatus having a closed-circuit pulverizing system comprising a conventional pulverizer, a classifier, and several conveyors. The powder manufacturing apparatus includes a crusher 2 for crushing the raw material supplied from the raw material supply device 1,
Conveyor 3 for transferring the crushed product discharged from the crusher 2
A classifier 4 for classifying the crushed product into coarse powder having a predetermined particle size and fine powder having a predetermined particle size or less, a bag filter 5 for collecting the classified fine powder, and a bag filter 5
A fan 6 is provided for sucking the air inside through a motor-operated on-off valve (not shown) for adjusting the flow rate and exhausting the air to the outside.

As a driving unit of the powder manufacturing apparatus, a raw material feeder 1 has a motor 1a for controlling a raw material supply amount for adjusting a raw material supply amount to a crusher 2, and a classifier 4 has a fineness. Motor for classifier rotation control for adjustment (not shown)
It has.

In this powder manufacturing apparatus, a PID controller 7 for manually inputting a set value calculates the amount of crushed material transported during powder production from a power load of a motor 3a provided in the transporter 3, and preliminarily calculates the amount. Power constant value control has been performed on the motor 3a that operates the number of rotations of the motor 1a provided in the raw material feeder 1 so that the set crushed product transport amount is maintained.

The set value input to the PID controller 7 is, for example, to change the power load on the motor 3a under the condition of a constant fineness, and to determine the optimum value of the power load on the motor 3a based on the change in the amount of raw material supplied at that time. It was determined by the desired field experiment.

[Problems] In such a conventional technique, there are the following problems. The optimum value of the power load on the electric motor of the crusher outlet side transfer machine obtained by such a method is not absolute, and is greatly increased depending on the easiness of crushing of the crushed raw material or the particle size of the crushed raw material, that is, the crushing characteristics of the crushed raw material. Variable, and generally the power load optimum is high for raw materials with poor crushing properties (ie, difficult to crush or coarse),
Conversely, when the raw material has good grinding characteristics, the optimum power load value tends to be low.

[0007] The optimum value of the electric power load on the motor of the conveying machine on the outlet side of the pulverizer also varies depending on the product particle size. In some cases the power load optimum is low. Furthermore, when the mill tends to be clogged, the mill discharge decreases, so the supply of the crushed material is controlled to increase, and the operation for the transport amount of the crushed material is reversed,
On the contrary, it causes the clogging of the mill.

[0008] As a result, when the set value of the conveying amount at the outlet of the crusher is too low, the crushing efficiency is low, the crushing ability is at a low level, and conversely, the set value of the conveying amount at the crusher outlet is too high, and the mill is clogged. If this occurs, an operation loss due to the mill idling occurs, so that the operation efficiency of the powder production decreases.

In addition, even when the set value of the conveyance amount at the outlet of the pulverizer is set in an appropriate range, high pulverization efficiency is required in the pulverization classification step in which the characteristics of the material to be pulverized change with time. Cannot be maintained and a high level of grinding capacity cannot be obtained.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the problems in the prior art, and the technical problems specifically set to solve the problems are as follows. In a closed-circuit grinding system, when the ease of crushing and the particle size of the crushed raw material and the particle size specification of the product change, it is easy to find the optimal grinding conditions, and by controlling the closed-circuit grinding system accordingly, a high grinding performance is always achieved. An object of the present invention is to provide a method of controlling a closed-circuit pulverization system and a powder production apparatus that maintain efficiency and eliminate loss due to mill clogging.

[0011]

Means for Solving the Problems Claim 1 of the present invention
The method of controlling the closed-circuit pulverizing system according to the present invention is to supply a raw material to a pulverizer and pulverize, transfer a pulverized product pulverized by the pulverizer to a classifier by a transporter, and set powder by the classifier. The crushed product is classified into fine powder and coarse powder according to the degree, and the fine powder is discharged as a product, and the coarse powder is returned from the classifier to the crusher and subjected to re-grinding. In the circuit crushing system, the raw material supply amount P to the crusher, the transport amount Q of the crushed product from the crusher to the classifier or the return amount R of the coarse powder returned from the classifier to the crusher. The characteristic curve of the fineness with respect to the circulation rate CL of the raw material in the crusher is estimated based on the circulation rate CL obtained by the above and the fineness S of the crushed product, and the power for the conveyance amount corresponding to this characteristic curve is estimated. Estimate the characteristic curve of the basic unit, and use this characteristic curve to Optimum transport amount Q _opt the unit is minimum
And the amount P of raw material supplied to the pulverizer is adjusted in accordance with the deviation between the optimum transport amount Q _opt and the actually measured transport amount Q of the crushed product.

[0012]

[0013]

According to a second aspect of the present invention, there is provided a powder producing apparatus including a closed circuit pulverizing system to which the control method according to the first aspect is applied.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below. However, this embodiment is specifically described for better understanding of the gist of the invention, and does not limit the content of the invention unless otherwise specified. Further, the same parts as those in the prior art are denoted by the same reference numerals and description thereof will be omitted.

[0016] As shown in FIG.
A constant feedware 11 that is a raw material supply device that supplies a raw material such as a cement clinker from a clinker silo 10; a tube mill 12 that is a pulverizer that pulverizes the raw material supplied from the constant feedware 11 in a cylindrical cylinder; , a bucket elevator 13 is a conveyor for conveying the mill Deco a ₁ is a砕製which have been discharged from the tube mill 12 to classifier side, the mill Deco a ₁ which is turned coarser than the predetermined particle size meal A separator 14 which is a classifier for classifying A ₂ and fine powder A ₃ having a predetermined particle size or less;
A bag filter 5 for collecting the classified fine powder and a fan 6 for sucking air in the bag filter 5 through an electric on-off valve (not shown) for adjusting a flow rate and exhausting the air to the outside are provided.

The constant feedware 11 in this apparatus has a control motor 11a having an inverter for adjusting the amount of raw material supplied to the tube mill 12.
The bucket elevator 13 has a driving motor 1
3a.

In this cement closed circuit pulverizing system, a raw material such as a cement clinker is supplied to a tube mill 12 by a constant feedware 11 and pulverized. Then, carry mill Deco A ₁ from the tube mill 12 to the separator 14 by the bucket elevator 13, where it coarser meal than the predetermined particle size A ₂ and a predetermined particle size less fine powder A ₃ binary class. The fine powder A ₃ is sent to the bag filter 5 by suction by the fan 6, collected and discharged out of the closed-circuit pulverizing system, while the coarse powder A ₂ is sent to the tube mill 12 and again with the raw material. Crushed. Similarly, cement is continuously produced by repeating this cycle.

In the closed-circuit pulverizing system in the cement production, in order to control the quality of the produced cement, a fineness measuring device 21 is provided at the outlet chute of the tube mill 12 or at the inlet chute of the separator 14 so that the milled powder A is discharged. Measure the fineness of ₁ . It is preferable that the fineness measuring device 21 can determine the fineness of the powder continuously or at intervals of at least ten minutes at most. For example, Japanese Patent Application Laid-Open No. 9-520
The method and apparatus described in the '57 publication are desirable.

The fineness measuring device 21 includes a probe directly inserted into the powder, a light-emitting portion, and a light-receiving portion, and includes a photoelectric converter for photoelectrically converting and outputting the amount of light reflected from the granular material. A reflected light amount measuring device including an amplifier that amplifies and photoelectrically converts an electric signal, adjusts a gain, and outputs a signal at a predetermined control voltage level; and a specific surface area, which is one of indexes indicating reflected light amount and fineness. And a storage device that holds calibration curve data that defines the relationship.

In the measurement by the fineness measuring device 21, the reflected light amount measuring device instantaneously outputs an electric signal of a predetermined voltage level from the light receiving unit via the photoelectric converter and the amplifier, and stores the calibration curve data stored in the storage device. By obtaining and outputting a specific surface area, which is one of the indices representing the degree of fineness with respect to the amount of reflected light, it is possible to obtain highly responsive and highly accurate data.

Further, a control motor 1 for adjusting the amount of raw material supplied to the tube mill 12 is provided in the closed circuit pulverizing system.
1a, a constant feedware transport amount output signal sc, a bucket elevator load current value output signal sb from the driving motor 13a for adjusting the mill powder transport amount to the separator 14, and an output signal of the fineness measuring device 21. s
and a control device 22 for estimating the crushing characteristics of the clinker in the tube mill from the mill output Q and calculating the optimum load current value of the bucket elevator 13 based on the clinker crushing characteristics; 13 and the output signal from the control device 22, and the control motor 11 of the constant feedware 11.
The control device 23 includes a PID controller or the like that outputs a signal indicating the frequency (rotational speed) to a.

The control device 22 controls the bucket elevator load.
Mill output from the output signal sb of the current value and the calibration curve data
A program that seeks Q and constant feedware
The raw material supply amount P which is the output of 11 and the fineness measuring device 21
Milling specific surface area S, which is the output of
From the milled powder quantity Q obtained from the load current value
The characteristic of the clinker at the time
Any of the specified grinding characteristics level I, II, III
The program that determines whether the closest
Level is the lowest in terms of power consumption.
) Mill output Q _minAnd obtain this value and the calibration curve data.
By milling A₁Elevator 1 that transports
3 and output the obtained load current value as a signal.
Program.

The control device 23 controls the bucket elevator 13
Of the constant feedware 11 and the control motor 11a so as to take in the load current value and the output signal from the control device 22 and set the deviation to 0 (zero).
And a PID controller that outputs a signal to the PID controller.

In the closed-circuit pulverizing system of the cement manufacturing apparatus, a fineness measuring apparatus 21 using a reflected light amount measuring apparatus is applied.
The by laying the separator inlet chute, sure you can continuously accurately measure the specific surface area of the mill Deco A _1, was subjected to the following field experiments.

(1) First, clinkers CLa to CLc having different crushing characteristics (meaning ease of crushing and relating to hardness and particle size) are separately provided for each of the silos 10a to 10c of the clinker silo 10 as follows. Keep in storage. Clinker CLa… Silo 10a… Crushable characteristics (good) Clinker CLb… Silo 10b… Crushable characteristics (medium) Clinker CLc… Silo 10c… Crushable characteristics (bad)

(2) Clinker C stored in silo 10a
The following field experiment is performed using only La. Mill discharge A from the outlet of the tube mill 12 to the inlet of the separator 14
₁ carry amount (hereinafter, referred to as the mill output flour weight) performs power stationary control of the bucket elevator 13 to operate the feed amount of Constant feed ware 11 (P) so as to maintain the Q to the set value, the fine powder fineness The set value of the bucket elevator electric power is changed in a step-like manner while being kept constant, and the raw material supply amount P, the mill discharge amount Q, and the mill discharge A ₁ at the time when each is stabilized.
The specific surface area S and the mill discharge power E are recorded.

Note that the milling amount Q is specifically shown in FIG.
As shown in ( ₁ ), a calibration curve between the mill dusting amount Q1 and the load power of the bucket elevator 13 (mill dusting transport power E) is obtained in advance, and is a calculated value obtained from the calibration curve. The same test is performed on the clinker CLb and the clinker CLc stored in the silos 10b and 10c, respectively, and each data is recorded.

(3) As a result, the following matters were confirmed. (a) When the circulation rate CL (the value obtained by dividing the separator return powder amount (Q-P) by the raw material supply amount (P)) increases, the mill discharge A
The specific surface area of _{No. 1} becomes smaller, and exists on substantially the same curve in the case of the clinker having the same grinding characteristics (FIG. 3). The specific surface area of the mill Deco A ₁ be the same circulation rate as the grinding properties are good increases (in Fig. 3 I>II> III).

(B) Mill output Q and mill power consumption (tube mill load power E divided by raw material supply P (kw)
The relationship of h / T)) exists on substantially the same curve for the clinkers having the same grinding characteristics, and the curve is a downwardly convex curve having a minimum value. Further, as the characteristics to be pulverized are better, the above-mentioned minimum value is present in the direction in which the amount of milled powder Q is smaller, and the unit power of the mill is smaller (FIG. 4). A flow meter (not shown) is provided on the coarse powder conveying path from the separator 14 to the tube mill 12.
Is installed, the circulation rate CL is equal to the coarse powder transport amount R.
The same result can be obtained by using a value obtained by dividing by the raw material supply amount P.

Based on such knowledge, the raw material supply amount P
And the milling amount Q and the milling specific surface area S,
The characteristics to be crushed of the object to be crushed are determined, and control is performed to optimize the flow rate in the crusher based on the characteristics to be crushed. Therefore, by continuously monitoring the crushing characteristics of the crushed material during actual operation, and when the change occurs, automatically finding the optimum crushing conditions and controlling the closed-circuit crushing system accordingly, it is always possible to always , High grinding efficiency can be maintained, and loss due to mill clogging can be eliminated. By the way, as a result of the comparison test with the conventional example, the mill capacity was from 48 T / H to 51 T / H.
, The basic unit of power is 35.3 kwh / T to 33.2 kwh /
Approximately 6% improvement in T was observed.

[0032]

As described above, according to the present invention, in the control method of the closed-circuit pulverizing system according to the first aspect, the pulverization state of the pulverizer is determined by setting the pulverization state of the pulverizer as the characteristic of the pulverizer in the pulverizer. By evaluating based on the input / output amounts P, R, and Q and the fineness S of the crushed product, which is the result of the powder particle size measurement, the presence or absence of a change in the characteristics to be crushed is quickly detected at the time of crushing, and the detection result is fed back. To set an optimal control target. Therefore, it is possible to optimize the amount of the crushed material passing through the crusher, improve the crushing efficiency, eliminate the possibility of clogging of the raw material in the crusher, and reduce the operation loss due to the idling of the crusher. Avoided,
The operation efficiency of the closed circuit pulverizing system can be improved.

[0033]

[0034]

In the powder manufacturing apparatus according to the second aspect,
By applying the control method of the closed-circuit pulverizing system according to claim 1, the presence or absence of a factor that reduces the production efficiency of the powder is detected at an early stage and appropriately dealt with, and the target transport amount of the powder having a predetermined particle size is determined. , The operating efficiency of the closed circuit pulverizing system can be optimized, and the operating cost of the powder production apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a powder manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a bucket elevator load current value and a mill dusting amount in the embodiment.

FIG. 3 is a graph showing a relationship between a circulation rate and a specific surface area of milled powder in the embodiment.

FIG. 4 is a graph showing the relationship between the amount of milled powder and the basic unit of electric power in the embodiment.

FIG. 5 is a system diagram showing a conventional powder manufacturing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Constant feedware 11a Control motor 12 Tube mill 13 Bucket elevator conveyance machine 13a Drive motor 14 Separator (classifier) 21 Fineness measuring device 22 Control device 23 Control device

────────────────────────────────────────────────── (5) References JP-A-58-170552 (JP, A) JP-A-6-31193 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B02C 25/00

Claims (2)

(57) [Claims] 1. A raw material is supplied to a pulverizer and pulverized. The pulverized product pulverized by the pulverizer is transferred to a classifier by a transporter, and the pulverized product is classified by the classifier according to a set fineness. Are classified into fine powder and coarse powder, and the fine powder is discharged as a product,
The coarse powder is returned from the classifier to the pulverizer in a closed-circuit pulverization system in powder production to be subjected to re-pulverization, and a raw material supply amount P to the pulverizer, and Circulation determined by the transport amount Q of the crushed product or the return amount R of the coarse powder returned from the classifier to the pulverizer.
Based on the circulating rate CL and the fineness S of the crushed product, a characteristic curve of the fineness with respect to the circulation rate CL of the raw material in the crusher is obtained.
Estimate the power source for the transport amount corresponding to this characteristic curve.
Unit characteristic curve is estimated, and this characteristic curve
The optimum transport amount Q _opt that minimizes the power consumption unit is determined, and
Deviation between the optimal transport amount Q _opt and the actually measured transport amount Q of the crushed product
A method for controlling a closed-circuit pulverization system, comprising adjusting a raw material supply amount P to a pulverizer according to a difference . 2. A powder manufacturing apparatus comprising a closed-circuit pulverizing system to which the control method according to claim 1 is applied.