JPS6363028B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a method for controlling the operation of dry tower mill equipment.

[Conventional technology]

The dry tower type crusher is, for example,
This is a known pulverizer also disclosed in No. ``Dry Tower Type Attrition Pulverizer''. As shown in Figures 1 and 2, this crusher has a shaft at the center of a closed circular column 1, a screw 3 is attached to this shaft, and a geared motor 4 moves the screw 3 in the direction of lifting the contents. Rotate. The material to be crushed is supplied to the crusher in a fixed amount by a supply device 5, for example, a rotary valve. The supplied materials to be crushed may be crushed by themselves, but usually a crushing medium such as steel balls is filled in the crusher, and the materials to be crushed are lifted together with the crushing medium by a screw. , it falls along the wall, and during this time it is crushed by the grinding action of the grinding medium and the object to be crushed.
The product thus crushed is discharged from the crushing tower,
Necessary products are classified and collected and sent to the product storage area.

In the equipment shown in Figure 1, there is a wind classifier inside the pulverizer, and the pulverized products blown up by the air blown from the bottom of the circular tower are classified, and those below a certain particle size are discharged with the wind and sent to cyclone 2. It is finally recovered here. Therefore, it is preferable that the pulverized product having a particle size smaller than the target particle size can be recovered as a product, but the problem is that the air flow blowing up inside the pulverizer may cause blow-by, which causes the operating conditions of the pulverizer to become unsteady, resulting in unstable operation. There is.

In the apparatus shown in Fig. 2, the pulverized product is extracted by the downward flow of air extracted from the inside of the pulverizer by the blower 6, and the pulverized product is recovered by the cyclone 2 and bag filter 7 in an open circuit system, so that the target particles can be Crushed products larger than the diameter are also collected as products, which is not only inconvenient, but the part of the bottom of the column where the materials to be crushed are densely packed blocks the passage of descending airflow, making operation unstable and reducing the amount of product. However, there are drawbacks such as large fluctuations in product particle size.

[Problem to be solved by the invention]

As mentioned above, in both Figures 1 and 2, the crushed products are discharged from the crusher by the airflow from the blower, so even if the supply amount of the crushed materials is constant, the crushed materials will be removed between the crushing media. As the amount of filling and packing density changes, the ventilation resistance inside the pulverizer fluctuates greatly, and not only does the amount of pulverized product discharge become uneven, but sometimes continuous operation is interrupted due to an abnormal increase in the amount of pulverized product. There are disadvantages such as the blower becoming inoperable or the blower power increasing abnormally.

In order to eliminate this drawback, the present inventors did not use ventilation at all as one of the lower extraction methods.
A device has been proposed in which the pulverized product is extracted from the lower end of the circular column using a mechanical extractor and transported, but the method of the present invention is designed to maintain the pulverizing efficiency at its highest in this case and reduce wear and tear on the pulverizing media. After repeated research,
The most appropriate operation control method for a tower-type crusher with a mechanical drafting device for crushed products was developed.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a method for controlling the operation of a tower-type crusher having a mechanical drafting device for crushed products, which includes a circuit for supplying crushed products extracted from the lower end of the circular column to a classifier, and a classifying device. A coarse powder recovery circuit is provided to recover the fine powder classified by the machine and return the coarse powder to the circular column, and the amount of crushed product withdrawn is controlled so as to keep the amount of crushed product supplied to the classification device constant. Detects the retention height of the material to be crushed in the circular column,
A feature of the present invention is that based on this detected value, the supply amount of the material to be crushed is controlled so as to keep the residence height within a certain range.

[Effect]

The present invention will be explained below with reference to the block diagram of FIG. The material to be crushed is supplied to the crusher by a supply device 5, for example, a variable speed quantitative feeder (supply amount b),
The level a of the material to be crushed in the closed circular column 1 is detected, and the supply amount b is adjusted in response to fluctuations in this detected value. It is desirable to automate the adjustment at this time, but it may also be done manually. Note that to detect the level of the material to be crushed inside the circular column, it is preferable to use an ordinary sound level meter 8 installed near the outer surface of the circular column, which has been proposed separately by the present inventors. The pulverized product is extracted from the lower part of the column by a variable speed extraction device 11, such as a cylindrical screw conveyor with a variable speed drive (extraction amount c), and is passed through a subsequent transporter 12 (transport amount d) to a classification device. Enter 13. The transport amount d is measured by a measuring device 9. The fine powder classified by the classifier 13 that falls within the standard is sent as a product to a storage area (not shown) (discharge amount g), and the coarse powder that does not meet the standard is returned to the pulverizer (return amount f). Here, the transporter 12 is suitably a closed type such as a bucket elevator, and one capable of measuring the transport amount d. Although some pulverized product storage chambers may be provided between the extraction device 11 and the transporter 12, as a general rule, the extraction amount c and the transportation amount d are equal during steady operation.

That is, in the present invention, the crushing system is made into a closed circuit as described above, and the amount of the crushed product inputted into the classifier is controlled to be kept at a constant value, and the level of the crushed material a in the crusher is controlled. By controlling the supply amount of the material to be crushed so as to keep it within a certain range, the purpose is to ensure the optimum residence time of the material to be crushed in the crusher and to always operate at the highest grinding efficiency. The supply amount, that is, the transportation amount d, is determined so that the particle size of the subdivision and the yield etc. are appropriate values, and the extraction amount c is determined so that the subdivision particle size and yield etc.
When controlling , the amount of coarse powder returned to the pulverizer changes in accordance with changes in the particle size distribution of the pulverized product, so the level a of the material to be pulverized in the pulverizer also changes. Next, the supply amount b of the material to be crushed is increased or decreased so that the deviation between the level a of the material to be crushed in the crusher and the set value is within a certain range.

In this way, the material to be crushed can be allowed to stay in the grinding media packed bed in the grinder for just the desired residence time, and the performance of the classifier 13 can also be kept constant. In other words, it is possible to maintain the crushing efficiency of the crusher at the highest level and to maintain the overall operating conditions from the supply of the material to be crushed to the final product at all times in the best condition.

In addition, the setting conditions of each machine, such as the size of the crushing media, the filling amount, and the transportation amount d (amount supplied to the classifier)
Settings etc. also differ depending on the type of material to be crushed and the target particle size of the crushed material, etc., and by understanding these basic conditions in advance, setting the optimum conditions, and implementing the present invention, it is possible to improve the tower type crusher. Able to operate at maximum efficiency.

〔Example〕

The present invention was carried out using a tower-type crusher having an operation control system as shown in FIG.

The main specifications of the equipment are: Cylindrical column diameter: 1170mm Height: 3500mm Screw diameter: 900mm Grinding media: Steel ball extraction chute with a diameter of 17mm: Inclined at 45 degrees Extraction machine: Variable speed motor driven cylindrical screw conveyor Transport machine: Bucket Elevator classification device: Air flow classification separator Feed device: Variable speed motor driven rotary valve Material to be crushed: Material to be crushed in blast furnace slag tower Level detector: Ordinary sound level meter The results were as follows.

Depending on the condition of the fine powder obtained by classification, adjust the fineness adjustment device of the classifier to determine the appropriate supply amount d to the classifier, and then adjust the amount c taken out from the pulverizer to reach this set value. When continuous operation was carried out while controlling the amount of material to be crushed, it was possible to easily adjust the supply amount of the material to be crushed according to fluctuations in the level of the material to be crushed in the crusher, and the overall operation was also able to be smoothly controlled.

Specifically, in a 24-hour operation test, the powderiness target was a plain value of 4000 cm ² /g, but the actual value was 3900 ~
The supply amount b remained within the range of 4100 cm ² /g, and the fluctuation of the supply amount b remained within ±3% of the average during that period, and remained almost constant. The change was within a range that would not cause any damage, demonstrating that this method is extremely reliable in terms of stable operation. In addition, to manage the fine powder plain value this time, sampling was performed every 15 minutes, but based on actual results, it was judged that general sampling every few hours would be sufficient.

〔Effect of the invention〕

According to the present invention, even when there is a change in the material to be crushed or a change in the product, the tower-type crusher can be operated under optimal conditions in response to the change.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams of a dry tower type crusher, both of which discharge the crushed material in an air flow type, and FIG. 3 is a block diagram of an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Closed circular tower, 2... Cyclone, 3... Screw, 4... Geared motor, 5... Material supply device to be crushed, 6... Blower, 7... Bag filter, 8... Ordinary sound level meter, 9 ...Measuring device, 11...
...Extracting device, 12...Transporting machine, 13...Classifying device, a...Retention height of the material to be crushed in the circular column, b...Amount of material to be crushed, c...Amount of extraction, d...Amount of transportation, f...Return amount, g...Feeding amount.

Claims (1)

[Claims] 1. A closed circular column, a shaft rotating at its center, a screw attached to the shaft, a material supply device provided at the top of the column, and a mechanical pulverized product extraction device provided at the bottom end of the column. A method for controlling the operation of a column-type pulverizer comprising: a circuit for supplying the pulverized product extracted from the lower end of the circular column to a classifier; and a circuit for recovering fine powder classified by the classifier and transferring coarse powder into the circular column. A return coarse powder recovery circuit is provided to control the amount of pulverized products to be withdrawn so as to keep the amount of pulverized products supplied to the classification device constant, and to detect the height of the pulverized material in the circular column. A method for controlling the operation of a tower-type pulverizer, characterized in that the supply amount of the material to be pulverized is controlled based on a detected value so as to maintain the residence height within a certain range.