JPH0367741B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for controlling a crushing system that automatically searches for an optimal set value for the load of a crusher.

(Prior Art) As a control method for a system in which cement pulverization is performed using a pulverizer such as a tube mill, there is a method of controlling the load at a constant value. This is to set the load represented by the amount of material to be crushed that passes through the crusher, the amount that remains in the crusher, etc. to an optimal value so that the maximum crushing efficiency can be obtained. In this case, the optimal set value varies depending on the properties of the object to be crushed and the condition of the crusher, and is not constant.
Therefore, in order to cope with this change, the set value of fixed value control is made variable, and the set value is changed to a higher value by calculating and comparing the average grinding efficiency for a certain period of time for each set value. A system control method is used that automatically searches for This optimum set value search control is based on the premise that the grinding efficiency for each level of set value can be compared on the basis of the same fineness. In this sense, measurement of the fineness and control of the fineness of the ground product is essential. However, conventionally, the load optimum setting value search control and the fineness control are performed independently.

(Problems to be Solved by the Invention) As described above, in the conventional control system in which the optimum setting value search control for the crusher load and the product fineness control are performed independently, the following problems occur. There was an inconvenience.

First, when the set value of load control is changed, the grinding system becomes unstable transiently. Therefore, in order to compare the effects between the set value levels, it is necessary to wait for the calculation of the grinding efficiency for a certain period of time after changing the set value. In conventional control methods, it takes a long time to stabilize the system, and the waiting time is also set long for safety reasons, so the search speed for the optimal point becomes slow.

Second, when comparing the set value levels for comparing grinding efficiency, it is possible to misjudge that factors other than the effect of changing the set value, such as changes in the properties of the material to be crushed, are involved, and change the set value to the one with lower grinding efficiency. There are cases where this happens. Conventional control methods are insufficient to counter this problem;
There are problems in both accuracy and speed of optimal point search.

Thirdly, the fineness of the product fluctuates as the set value of load control is changed, but it takes time to stabilize the fineness with only feedback control.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling a crushing system that solves the above-mentioned problems and improves the accuracy and speed of searching for the optimum value of the load.

(Means for Solving the Problems) The present invention is applicable to searching for the optimum setting value of a load that changes due to disturbance and controlling the setting value of the crushing system to follow the optimum point using an online hill-climbing method or the like. Accordingly, the present invention is characterized in that feedforward control of the fineness of the product is performed in conjunction with changes in the set value of the load control. In this case, the stabilization of the grinding system is determined using the measured value of the fineness together with the measured value of the load. Changes in the properties of the material to be crushed are also detected using load measurement values and fineness measurement values.
Avoid misjudgment when changing setting values.

(Function) By performing feed forward control of the fineness in conjunction with changes in the load setting value as described above, fluctuations in the fineness are detected as in the past and the fineness control is performed based on this. The instability period of the grinding system can be shortened compared to the conventional method. In addition, by using the fineness measurement value and the load measurement value, it is possible to reliably judge whether the grinding system has stabilized, and it is possible to misjudge the change of the setting value in the optimal setting value search control due to disturbance during setting value level comparison. can also be avoided.

(Example) Examples of the present invention will be described below.

FIG. 1 shows the configuration of a crushing system according to an embodiment of the present invention. In the figure, numeral 1 is a pulverizer such as a ball mill, which pulverizes the material to be pulverized supplied from a feeder 3 . The pulverized material discharged from the outlet of the pulverizer 1 is conveyed to the separator 2 by a bucket elevator 4. The separator 2 classifies the pulverized material, discharges a portion as a product, and returns the remainder to the pulverizer 1 again. There is a load measuring device 5 on the discharge port side of the crusher 1, and based on the measured value, a controller 6 adjusts the feeder 3 so that the load on the crusher 1 is constant.
is controlled. At the discharge port of the separator 2, there is a device 8 for measuring the fineness of the pulverized material, and the separator 2 is controlled by a controller 9 based on the measured value.
Reference numeral 7 denotes a calculator, into which data such as the supply amount of the material to be crushed and the power of the crushing system, as well as the outputs of the load measuring device 5 and the powderiness measuring device 8, are input. The computer 7 provides a load target value to the load controller 6, and provides a feed forward signal for fineness control to the fineness controller 9.

The control operation of this crushing system will be explained with reference to the flowchart of FIG. First, it is assumed that this crushing system is operating stably at a certain load control setting value. The amount of pulverization at this time is integrated over a certain period of time to calculate the pulverization efficiency (step S1).

Next, the computer 7 instructs the controller 6 to change the target value in order to search for the optimal set value for crushing load control (step S2). Note that the magnitude of the load on the crusher 1 is measured by the current or electric power of the bucket elevator 4 and the sound pressure emitted from the crusher 1. Fluctuations in production fineness can be expected when changing load settings. Therefore, the fineness is controlled by the controller 9 using the feed forward control of the computer 7 (step S3). More specifically, the load on the pulverizer 1 increases as the amount of material to be pulverized that passes through the pulverizer increases, and the powderiness at the outlet of the pulverizer also becomes coarser. As the amount of powder passing through the crusher increases, the amount of powder inserted into the separator 2 also increases. Therefore,
When the load setting value is controlled to be increased, the rotation speed of the separator 2 is increased, and when fine adjustment of the fineness distribution is required, the air volume is controlled to be decreased.

Once the feedforward control is performed, the fineness is measured by the fineness measuring device 8, and it is determined whether or not the fineness is within a predetermined range (step S4). Feedback control is performed so that Here, if the fineness deviates from the predetermined range, the rotation speed and air volume of the separator 2 are changed (step S5), and the process returns to step S4 again. If the degree of fineness is within the predetermined range, the rotation speed and air volume of the separator 2 are corrected so that the degree of fineness is closer to the predetermined value (step S6), and the process moves to the step of accumulating the amount of pulverization (step S7).

By performing such feed-forward control, compared to the conventional method in which the fineness is controlled after detecting fluctuations in the fineness with the fineness measuring device 8, the instability time caused by changing the setting value of the grinding system is reduced. Can be shortened. The instability time, which is the waiting time during which the milling efficiency cannot be calculated with a new load setting, is shortened in this embodiment.

Next, the timing of stabilization of the crushing system is determined by comparing each output of the fineness measuring device 8 and the crusher load measuring device 5 with a predetermined setting pattern of fineness and crusher load, respectively. . It is difficult to judge this stabilization timing based only on either the powder degree or the crusher load. For this reason, in the past, a long waiting time was set in consideration of safety, but in this embodiment, reliable judgment can be made by using data on both the powder degree and the crusher load. As a result, the speed of searching for the optimal setting value can be improved.

Thereafter, for a certain period of time, the computer 7 integrates the supply amount of the crusher and the power of the crusher to determine the average crushing efficiency (steps S7 to S9). This average crushing efficiency (current average crushing efficiency A) is compared with the efficiency at other load settings (previous average crushing efficiency B) (step S10).
Then, according to the judgment result of (A-B), the load setting value is further changed to the one with better efficiency (step
S11 to S13), feed forward control (step
Return to S3). By repeating the above control,
It is possible to quickly make the load setting value of the crusher follow the changing optimum setting value.

On the other hand, if the properties of the material to be crushed suddenly change while comparing the level of crushing efficiency, the comparison of each set value will change due to factors other than the change in the set value, and the set value will be changed to the one with lower efficiency due to a misjudgment. There are cases where this is done. Once a wrong decision is made, the grinding efficiency will decrease until it reaches the true optimum value several cycles later. In this embodiment, such changes in the properties of the material to be crushed are detected by the outputs of the powderiness measuring device 8 and the crusher load measuring device 5. If a change in properties is detected, the past data is temporarily erased, and after the crushing system is stabilized, the operation of comparing the crushing efficiency for each set value is started again. This makes it possible to avoid erroneous judgments about changing set values due to changes in the properties of the object to be crushed.

An example in which the system of this embodiment is specifically applied to a cement crushing process will be described next. A laser diffraction type particle size measuring device was used, and cement samples were sampled from the process and dispersed in a gas phase to measure particle size distribution. The rotational speed and air volume of the air separator were controlled so that this measured value became the required value. At the same time, data regarding this particle size was entered into a computer.

The crusher was a tube mill, and its load was determined from the amount of mill passage, that is, the power consumption of the drive motor of the bucket elevator, which is a conveyor at the mill exit. The amount retained in the mill can also be detected by detecting sound using other known means, such as a microphone. The initial value of mill load control is set by a person. After that, when you give the computer a command to start searching for the optimum point, the computer checks whether the fineness and the amount passing through the mill match the target values, and if they do, it starts integrating the amount of grinding and power. After a pre-specified time has elapsed, the average grinding efficiency is calculated. During this time, if an abnormality is detected in the amount passing through the mill or the degree of fineness, the integration is cleared and the integration is restarted after the grinding system is stabilized.

Next, the mill passing amount set value is changed by a predetermined width in a predetermined direction. Simultaneously with this change, the separator is operated as a feed forward control for expected fineness changes. Once the amount passing through the mill and the degree of fineness are stabilized, the amount of grinding and power are integrated to calculate the grinding efficiency for this set value. After calculating the average grinding efficiency,
Compare with the crushing efficiency at the previous setting value. Then, the settings are changed by a predetermined width in the direction of more efficient grinding.

With this method, the waiting time after changing the setting value was shortened from 90 minutes to 40 to 70 minutes, and the accuracy of searching for the optimal setting value was also improved.

(Effects of the Invention) As described above, according to the present invention, by using information on fineness control for load optimum setting value search control, the optimum setting value search is performed with higher precision, faster speed, and higher efficiency than in the past. Allows control of the mold grinding system.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a crushing system according to an embodiment of the present invention, and FIG. 2 is a flowchart for explaining the operation of the apparatus of the embodiment. DESCRIPTION OF SYMBOLS 1...Crusher, 2...Separator, 3...Feeder, 4...Bucket elevator, 5...Crusher load measuring device, 6...Controller, 7...Calculator, 8...
...Powdness measuring device, 9...Controller.

Claims (1)

[Claims] 1. In a method for controlling a grinding system, the grinding efficiency is determined by varying the load control setting value of the grinder, and the optimum setting value for the load that maximizes the grinding efficiency is automatically searched. A method for controlling a grinding system, characterized in that, in addition to feedback control to keep the powder level constant, feed-forward control of the fineness of a product is performed in accordance with a change in a set value for load control.