JPS63134068A - Method of controlling crushing system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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 is pulverized 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 setting value is
It varies depending on the properties of the material 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 the planting control is made variable, and the set value is changed to a higher value by calculating and comparing the average crushing efficiency for a certain period of time for each set value. A system control method is used that automatically searches for This optimum setting value search control is based on the premise that the grinding efficiency for each level of one shift 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 set value levels, it is necessary to wait for calculation of the crushing 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, between the set value levels for comparing the crushing efficiency, if factors other than the effect of changing the set value, such as changes in the properties of the material to be crushed, are involved, it may be misjudged and the set value will be changed to the one with lower crushing efficiency. There are cases where this happens. Conventional control methods have insufficient countermeasures against this problem, and have problems in terms of both the accuracy and speed of optimal point search.

Thirdly, the fineness of the product fluctuates as the set value of the 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 searches for the optimal set value of a load that changes due to disturbance, and controls the set value of the crushing system to follow the optimal point using an online hill-climbing method or the like. The present invention is characterized in that feedforward control of the powderiness of the product is performed in conjunction with changes in the load control set value. 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 object to be crushed are also detected using the load measurement value and the fineness measurement value, thereby avoiding misjudgment in changing the set value.

(Function) By performing feedforward control of the fineness in conjunction with changes in the load setting value as described above, it is possible to detect fluctuations in the fineness and control the fineness based on the conventional method. In comparison, the period of instability of the grinding system can be shortened. 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) The present invention will be explained in detail below.

The figure 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 crushed material discharged from the discharge port of the crusher 1 is conveyed to the separator 2 by the packet elevator 4. The separator 2 classifies the pulverized material, discharges a portion as a product, and returns the remainder to the pulverized material 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 controls the supply 1a3 so that the load on the crusher 1 is constant. At the discharge port of the separator 2, there is a device 8 for measuring the fineness of the pulverized material.
The separator 2 is controlled by the controller 9 based on the measured value. 7 is a calculator, and in addition to data such as the amount of material to be crushed and the power of the crushing system, there is also a load measuring device! ! 5, the output of the fineness measurement value @8, etc. are input. The computer 7 provides a load target value to the load controller 6, and provides a feedforward signal to the fineness controller 9 for controlling the fineness.

The control operation of this crushing system will be explained. First calculation 7
From then on, the controller 6 is instructed to change the target value in order to search for the optimal set value for crusher load control. The magnitude of the load on the crusher 1 is measured by the current or electric power of the packet elevator 4 and the sound pressure emitted from the crusher 1. When changing the load setting, fluctuations in product fineness are expected. Therefore, by using feedforward control of calculation vs. 7, controller 9
to control the fineness. To explain more specifically, the load on the crusher 1 increases, for example, as the amount of material to be crushed that passes through the crusher increases, and the degree of powder at the crushing outlet also becomes coarser. . As the amount of powder passing through the crusher increases, the amount of powder fed into the separator 2 also increases. Therefore, the air volume is controlled to be lowered when necessary. By performing such feedforward 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 unstable time due to changing the setting value of the grinding system is shortened. be able to.

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 grinding system is determined by the fineness measuring device 8.
The determination is made by comparing each output of the crusher load measuring device 5 with a predetermined setting pattern of fineness and crusher load. 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 duration 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 search speed for the optimum setting position can be improved.

After that, for a certain period of time, the computer 7 integrates the supply amount of the crusher and the power of the crushing system to find the average crushing efficiency, compares this with the efficiency at other load settings, and increases the load to the one with higher efficiency. Change the setting value. By repeating the above control, it is possible to quickly make the load setting value of the crushing system 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 setting value will change due to factors other than the change in the setting value, and the setting 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 example, changes in the properties of the material to be crushed,
It is detected by the output of the powder degree measuring device 8 and the crusher load measuring device M5. 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 below. 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 power consumption of the drive motor of the packet elevator, which is a transportation device for passing through the mill and exiting the mill. 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 a command is given to the computer to start searching for the optimum point, Calculator d checks whether the fineness and the amount passing through the mill match the target values, and if they match, it starts integrating the amount of grinding and power. , calculate the average grinding efficiency after a pre-specified time has elapsed. 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 system to the expected fineness change. 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 it with the grinding 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 time required after changing the setting value was shortened from 90 minutes to 40 to 70 minutes, and the accuracy of searching for the optimum 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 the drawing]

The figure shows a grinding system according to one embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Pulverizer, 2... Separator, 3... Supply machine, 4... Packet elevator, 5... Pulverizer load measuring device, 6... Controller, 7... Calculator, 8... Powderness measuring device, 9... Controller.

Claims (1)

[Claims] A method for controlling a grinding system that automatically searches for an optimal load setting value for a grinder, characterized in that feed-forward control of product fineness is performed as the load control setting value is changed. Control method.