JPS62217303A - Control system for mill application amount - Google Patents

Abstract

PURPOSE:To prevent the jam of a mill by giving the time component to a flow rate measurement signal and also the primary delay component to the feedback material measurement signal respectively. CONSTITUTION:The flow rate measurement signal of the feedback material is supplied to a wafer W1 consisting of a primary delay filter to reduce the sudden variation of the W1. Thus a gentle signal is obtained to average the cyclic variation of a wafer W2. This average value is added with the waste time through a wafer W3 and fitted at a scale with a wafer W4 to be added at a wafer W6 with the measurement signal of the new material that is fitted at a scale at a wafer W5. Then the total addition of these W1-W6 are supplied to wafers W7-W9 to undergo the PID operation. Thus an operation signal is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in a cement manufacturing factory, etc., when the raw material input to the raw material grinding mill is a new raw material (N) before being crushed.
In addition to raw materials (Re
If the invention also includes a turn feed, it relates to a method for controlling the amount of cement raw material input into the mill, with the aim of keeping the amount of pulverization in the mill at an appropriate amount commensurate with the mill's capacity and preventing clogging of the mill.

[Conventional technology]

FIG. 1 shows an embodiment of the present invention and is an explanatory diagram that can also be used to explain the cement raw material grinding mill that is the object of the present invention. explain.

In Figure 1, 1 is a mill (also called a ball mill), 2
3.4 is a carry-in path, 5 to 8 are belt conveyors, 9 is a discharge path, 10 is a bucket elevator, and 11 is a separator.

Cement raw material weighed by quantitative weighing machine 2 (hereinafter referred to as new raw material N e in the sense of raw material that has never been crushed)
(also referred to as u Feed) is fed into the mill 1 via an input path 3. The inside of the mill 1 consists of a first chamber R1 and a second chamber R2 partitioned by a grid G. The new raw material is first crushed in the first chamber R1 by a plurality of iron balls (not shown) present in the chamber, and when it reaches a particle size of the same size, it passes through the grid G and reaches the second chamber R2.
Here too, after being further crushed by the balls, it is dropped onto the belt conveyor 5 via the discharge path 9.

The raw material that has been crushed and crushed once reaches the lower end of the bucket elevator 1o by a belt conveyor 5.

In the bucket elevator 10, a bucket (not shown) sucks up the crushed raw material carried by the belt conveyor 5, ascends to reach the upper end, places the raw material on the belt conveyor 8, and repeats this process.

The raw material placed on the conveyor 8 is transported to the separator 1
It will be put into 1.

Inside the separator 11, the input raw materials are sorted according to their particle size, and those with a sufficiently small particle size are transported to the next step (not shown) via a belt conveyor 6, while those with a coarse particle size are conveyed to the next step (not shown). The raw material is returned to the mill 1 via the conveyor 7 and the input path 4, and is again fed into the mill 1 together with the new raw materials from the input path 3 as return feed.

In this way, when the raw materials input into mill 1 include not only new raw materials but also returned raw materials, the amount of raw materials input into mill 1 is adjusted to an appropriate amount commensurate with the grinding capacity of mill 1. If you try to control it, the following problems arise.

The first is that the residence time of the raw material in mill 1 (the time required for pulverization) is longer for new raw materials, whereas the returned raw materials are raw materials that have been pulverized once and are inherently smaller in particle size than new raw materials. There is a difference that it is short because it is small, and this point needs to be taken into consideration.

Secondly, the amount of recycled material tends to fluctuate over time due to the fact that it is transported intermittently via the bucket elevator 10, and if the amount of recycled material decreases rapidly, If the amount of new raw material is rapidly increased in response to the adjustment needle, there is a problem in that the grinding capacity of the mill 1 is exceeded, and as a result, the grid G is clogged.

In addition, if the amount of raw material input into mill 1 is too small,
Dry striking by the iron balls may occur in the mill 1 and damage the mill, so it is necessary to control the amount of raw materials always fed into the mill.

[Problem that the invention seeks to solve]

Therefore, in the present invention, in the raw material input amount control method of the mill into which new raw materials and returned raw materials are input, even if the input amount of returned raw materials changes suddenly, clogging etc. do not occur regardless of the sudden change in the input amount of the returned raw materials. The problem to be solved is to achieve appropriate control of raw material input. It is therefore an object of the present invention to provide a mill input control method which makes the above possible.

[Means for solving problems]

After passing the measurement signal of the returned raw material (flow rate) fed into the mill through a first-order delay element and further through a dead time element, the sum is taken with the measurement signal of the new raw material (flow rate) also fed into the mill. A controller is provided that generates a regulating output that compares the acid phase with a set value that makes the difference zero, and a control means that controls the amount of new raw material flowing into the mill using the regulating output as the set value. Established.

[Effect]

The problem in controlling the mill input amount using new raw materials and returned raw materials is the time required to crush the new raw materials and returned raw materials (
This is due to the variation in feed rate of new feedstock due to the difference in the residence time in the mill (mill residence time) and the flow rate variation of the return feedstock.

In order to eliminate the difference in time required for pulverizing the new raw material and the returned raw material, this invention provides a dead time component in the flow rate measurement signal of the returned raw material, and in order to reduce fluctuations in the returned raw material, the rapid Fluctuations are smoothed by adding a first-order lag component to the feedback raw material measurement signal, and periodic fluctuations are dealt with by averaging. As a result, fluctuations in the amount of new raw material input into the mill are minimized. This allows the mill to be pressed down, thereby preventing the mill from clogging.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

Since FIG. 1 is also an explanatory diagram showing one embodiment of the present invention,
Referring again to FIG. In the figure, reference numeral 20 denotes a flow rate transmitter that measures the flow rate of the returning raw material fed into the mill 1 from the inlet path 4 and transmits the measurement signal (A) to the controller 21. be. Reference numeral 22 denotes a flow rate transmitting and controlling device, which receives the weight of the new raw material weighed by the quantitative weighing machine (belt conveyor) 2 and the speed of the weighing machine 22 as a belt conveyor measured by a tachometer P. Then, the flow rate of the new raw material introduced into the mill 1 from the carry-in path 3 is measured, and the measurement signal (TI) is transmitted to the controller 21.

Furthermore, the flow rate transmission and flow rate control device 22 has a controller 21 that outputs a return raw material flow rate measurement signal (a) and a new raw material flow rate measurement signal (TI).
) is compared with the set value that is the sum of 0) and set the control output (
In addition to the motor M, the speed of the weighing machine 2 as a conveyor is controlled by the drive motor M.

FIG. 2 is an explanatory diagram showing the program in the controller (built-in microcomputer) 21 in FIG. 1 using a wafer connection diagram.

In the figure, the wafer W1 consists of a first-order lag filter (its transfer function is given by /(1+T,), K is a constant, T is a time constant, and S is a Laplace operator). Wafer W2 is an analog average wafer, wafer W3
Wafer W4. W5 is a wafer for adjusting the scale of returned raw materials and new raw materials for the total raw materials, wafer W6 is a wafer for calculating the total amount by adding the returned raw materials and new raw materials, and wafers W7 to W8 are set as the total amount. This is a wafer that performs P, T, and D control for deviations from the value SV. Wafers WIO to W12 are wafers for detecting and generating an alarm when the flow rate fluctuation of the returned raw material is too rapid.

Figure 3 shows the first-order lag filter (Eva Wl) in Figure 2.
) is a waveform diagram showing the input signal as a solid line and the output signal as a broken line.

From Fig. 3, the first-order lag filter (wafer Wl) is inputted with the flow rate measurement signal of the returned raw material, and if this is accompanied by rapid fluctuations, it is smoothed, fine fluctuation components are removed, and the rough fluctuations are smoothed out. It will be understood that the signal is output as a gradual signal that follows.

FIG. 4 is a diagram for explaining the function of the analog average wafer W2 in FIG. In Fig. 4, the function of wafer W2 is to divide the time period T into n equal parts, measure the signal level (output of wafer W1) at the n times, and calculate and output the average value. be. That is, it can be said that the analog averaging wafer W2 is a wafer that averages periodic fluctuations in the flow rate measurement signal of the returned raw material.

The general operation will be explained with reference to FIG. 2 again.

The flow rate measurement signal of the returned raw material is smoothed out from its rapid fluctuations to become a gentle signal at the wafer W1, and then its periodic fluctuations are averaged at the wafer W2. Then, the average value is given a dead time at wafer W3 (which means that the current new raw material is combined with the returned raw material after a certain period of time commensurate with the dead time, and becomes the subject of adjustment. After the scale is adjusted on wafer W4, it is added to the flow rate measurement signal of the new raw material whose scale was adjusted on wafer W5 at wafer W6, and the sum (total amount) is input to wafers W7 to W9. , PID calculations are performed, and a manipulated output is generated.

Next, the alarm generation operation by the wafer WIO-W12 will be explained. The average value signal from wafer W2 is subtracted from wafer Wll
, the difference (
If the difference value exceeds the upper limit value H or the lower limit value set in the upper and lower limit limiter wafer W12, the upper limit alarm H
Or output the lower limit warning IL.

〔Effect of the invention〕

As explained above, according to the present invention, the time required for pulverization between the returned raw material and the new raw material (residence time in the mill)
This not only prevents clogging of the mill due to poor adjustment due to the difference in flow rate, but also prevents clogging of the mill due to oversupply of new raw material due to rapid fluctuations in the flow rate of returned raw material. This method has the advantage that it is possible to realize mill input amount control.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the present invention, and FIG.
FIG. 3 is an explanatory diagram showing the control program in the controller 21 in the form of a wafer connection diagram. FIG. 3 shows the input signal of the first-order lag filter (wafer Wl) in FIG. 2 with a solid line, and the output signal with a broken line. FIG. 4 is a diagram for explaining the function of wafer W2 in FIG. 2. Explanation of symbols 1... Mill, 2... Quantitative weighing machine, 3.4... Loading path, 5-8... Belt conveyor, 9... Carrying out path, 1
0...bucket elevator, 11...separator, 2
0...Flow rate transmitter, 21...Controller, 22...Flow rate transmitter and flow rate control device

Claims (1)

[Claims] 1) A mill that crushes and discharges input raw materials, and a mill that examines the particle size of the crushed raw materials discharged from the mill, and selects those exceeding a predetermined particle size and uses them as return raw materials. , a return means for feeding the raw material back into the mill separately from the new raw material, the amount of the raw material being fed into the mill,
In a mill input amount control method for controlling the amount to an appropriate amount commensurate with the grinding capacity of the mill, the amount of the returned raw material input into the mill per unit time (hereinafter referred to as the feedback input amount) is measured and output as an electrical signal. a first measuring means for outputting an output, and a second measuring means for measuring the amount of new raw material input per unit time (hereinafter referred to as the new input amount) input into the mill by the new raw material inputting means and outputting it as an electrical signal. a measuring means, a first-order lag element that receives the feedback input amount signal obtained by the first measuring means and outputs it with a first-order lag, and inputs the feedback input amount signal to which the first-order lag has been applied; and a dead time element that is outputted with a dead time determined in relation to the difference in residence time between the new raw material and the returned raw material in the mill, and the new input amount signal obtained by the second measuring means and the dead time element. means for calculating the sum with the output signal of the time element; and a means for receiving the sum signal, comparing a certain setting value and the sum signal to find the difference, and adjusting the adjustment signal so that the difference becomes zero. a control means for controlling the amount of new input into the mill in the new raw material input means using the adjustment signal from the adjustment means as a set value input;
A mill input amount control system characterized by comprising: