JPH0149546B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, raw materials supplied from a raw material potspa are crushed in a crusher, sent to a separator using a bucket elevator, etc., and separated into fine powder and coarse particles. relates to a control device for maintaining the maximum amount of product in a grinding mill that is returned to the inlet side of the grinder.

A crusher is used to crush lumps such as cement, coal, and various ores. This crusher has balls of various sizes placed inside a cylinder made of steel plate. As the cylinder rotates, the balls move, and the contents are pulverized by the impact and friction.

A pulverizing mill including this pulverizer usually has a configuration as shown in FIG. 1, in which raw materials are supplied to the pulverizer 1 at a flow rate F _i and exit from the pulverizer 1 after being pulverized. Thereafter, it is transported upward by a bucket elevator 2 and sent to a separator 3. The separator 3 separates the pulverized raw material into fine powder and coarse particles, and the fine powder is discharged as a product from the lower part of the separator 3 at a product flow rate F ₀ . Coarse particles that have not been sufficiently crushed are returned from the separator 3 to the inlet side of the crusher 1. Let this flow rate be F _r .

As shown in FIG. 2, the characteristics of the pulverizer are as follows: within a range where the supply flow rate F _i is small, all of the supplied raw materials are crushed into products, so the product flow rates F ₀ and F _i are equal. However, as F _i increases, the return flow rate F _r that returns to the inlet side of the pulverizer without being pulverized and remains coarse gradually increases, and the product flow rate F ₀ decreases. Therefore, there is a feed flow rate F _i that maximizes the product flow rate F ₀ . As F _i increases beyond this point, the mill becomes unstable and
The time spent in the crusher increases rapidly, resulting in a significant response delay and reduced efficiency.

In the current control system of the grinding mill, as shown in FIG. 6 controls the speed of the raw material constant feedware 8 that transfers the raw material from the raw material pumper 7 to control the supply flow rate F _i to the crusher 1, but it is difficult to find the maximum efficiency point mentioned above. Moreover, since this point is not constant over time and also changes depending on the properties of the raw material, it has been impossible to operate the grinding mill efficiently and to save energy.

It is an object of the present invention to provide a grinding mill control device that eliminates the above drawbacks, automatically finds the highest efficiency point where maximum production can be achieved, maintains stable operation at that point, and saves energy. .

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 is a block system diagram showing one embodiment of the grinding mill control device according to the present invention. In FIG. 4, a return flow meter 11 is provided on the return path from the separator 3 to the inlet side of the crusher 1 to detect the return flow rate F _r . Since the return flow rate F _r pulsates, an arithmetic unit 12 is provided to calculate the average value F _r over a certain period. moreover,
The rate of change ΔF− _r of this average value F− _r per certain period
An arithmetic unit 13 is provided to obtain the .

On the other hand, since the feed flow rate F _i from the feed flow meter 9 that outputs the feed flow rate F _i of the raw material from the feed rate and passing weight of the constant feedware 8 also pulsates, a computing device is used to calculate the average value F− _i over a certain period. 14 will be provided. Furthermore, an arithmetic unit 15 is provided for calculating the rate of change ΔF- _i of this average value F- _i every certain period.
A delay circuit 16 is provided to delay and output the rate of change ΔF- _i by the time required for a change in the supply flow rate F _i to appear at the outlet of the separator 3. By subtracting the ΔF- _r at this point from the ΔF- _i output from the delay circuit 16, the rate of change in the average value of the product flow rate ΔF- ₀ is obtained.
A subtractor 17 is provided to obtain the . Furthermore, this ΔF−
₀ divided by ΔF− _i from the delay circuit 16 to get ΔF/− ₀ /
A divider 18 is provided to calculate ΔF _i . Further, it is determined whether ΔF/- ₀ /ΔF _i from the divider 18 is positive or negative, and if it is positive, the set value is set to the raw material supply amount controller 20 as ΔF/- ₀ /ΔF.
The absolute value of _i is 1 to the maximum raw material supply flow rate of this grinding mill.
A comparator 19 is provided which outputs a signal that increases the set value by a value multiplied by an amount K corresponding to 3%, and outputs a signal that similarly decreases the set value in the case of a negative value. The raw material supply amount controller 20 adjusts the supply flow rate F _r of the constant feedware 8 so that the set value is increased or decreased based on the signal from the comparator 19 .

In the grinding mill control device according to one embodiment of the present invention configured as described above, the rate of change ΔF- _i of the average value of the raw material supply flow rate over a certain period and the influence of the change in the supply flow rate are completely expressed. Using the rate of change ΔF− _r of the average return flow rate in the separator 3, (ΔF− _i
-ΔF- _r ) In other words, since we are calculating the rate of change ΔF- ₀ in the average value of the product flow rate from the separator 3, we can calculate the change in the supply flow rate F _i and the resulting product flow rate _F0.
changes are captured from moment to moment. and,
Find the ratio ΔF/- ₀ /ΔF _i of the rate of change of the product flow rate to the momentary raw material supply amount, and if this value is positive, that is, the product flow rate is increasing, the raw material supply amount controller 20
Increase the set value of ΔF/ _-0 /ΔF _i by the amount K corresponding to 1 to 3% of the maximum raw material supply flow rate of this grinding mill, increase the supply flow rate F _i , and then increase the product. Control in the direction where the flow rate is maximum, ΔF/- ₀ /ΔF _i is negative,
In other words, when the product flow rate is decreasing, the set value of the raw material supply flow rate controller 20 is set by multiplying the absolute value of ΔF/- ₀ /ΔF _i by an amount K equivalent to 1 to 3% of the maximum raw material supply flow rate of this grinding mill. Since the control is performed in a direction to correct the excessive amount of raw material supplied by decreasing the amount by the amount of raw material supplied, the highest efficiency point where the product flow rate is maximum with respect to the amount of raw material supplied is always maintained.

As described above, the grinding mill control device according to the present invention takes advantage of the characteristics of the grinder, automatically discovers the highest efficiency operating point, and has the remarkable effect of realizing stable and energy-saving grinding mill operation. play.

In addition, in the above embodiment, the return flow meter 11
A similar control system can be applied when a product flow meter is installed in the product line to directly measure the product flow rate F ₀ . Further, in the above embodiment, each calculation function is shown as a separate calculation unit, but it is clear that these functions may be integrated and implemented in a digital controller using a microcomputer or the like.

[Brief explanation of drawings]

Figure 1 is a block system diagram showing the general configuration of a grinding mill, Figure 2 is a graph showing the characteristics of the grinder,
FIG. 3 is a block system diagram showing a conventional example of a control system for a grinding mill, and FIG. 4 is a block system diagram showing an embodiment of a grinding mill control system according to the present invention. 1...Crusher, 2...Bucket elevator, 3
... Separator, 7 ... Raw material pots, 8 ... Raw material constant feedware, 9 ... Supply flow meter, 11 ... Return flow meter, 12, 14 ... Average value calculator, 13, 15 ... Average value Arithmetic unit for calculating the rate of change for each fixed period, 16...Delay circuit, 17
...Subtractor, 18...Divider, 19...Comparison device, 20...Raw supply amount controller, F _i ...Raw material supply flow rate, F _r ...Return flow rate, F ₀ ...Product flow rate.

Claims (1)

[Claims] 1. The raw material supplied from the raw material popper by constant feedware is pulverized by a pulverizer, sent to a separator by a bucket elevator, etc., and separated into fine powder and coarse grain, and the fine powder is discharged as a product. In the grinding mill where the coarse particles are returned to the inlet side of the grinder,
The ratio of the rate of change in the average value of _{the product flow rate F 0 to} the rate of change ΔF- _i in the average value of the _{raw material supply flow rate F i ΔF/- 0 /}
The means for determining ΔF _i and the set value of the raw material supply amount controller that adjusts the raw material supply flow rate F _i of the raw material constant feedware when this ΔF/− ₀ /ΔF _i is positive are determined by determining ΔF/− ₀ /ΔF _i Increase the absolute value by the amount K corresponding to 1 to 3% of the maximum raw material supply flow rate of this grinding mill, and then increase ΔF/- ₀ /ΔF
and a comparison device that reduces the set value by a value obtained by multiplying the absolute value of ΔF/− ₀ /ΔF _i by an amount K corresponding to 1 to 3% of the maximum raw material supply flow rate of this grinding mill when _i is negative. A grinding mill control device characterized by controlling the raw material supply amount so as to maintain the maximum product flow rate. 2. The means for determining ΔF/− ₀ /ΔF _i includes a return flow meter that detects the return flow rate F _r of the separator, an arithmetic function that determines the average value F− _r of the return flow rate F _r over a certain period, and a calculation function that calculates the average value F r of the return flow rate F − A calculation function for calculating the rate of change ΔF− _r for each fixed period, a supply flow meter for detecting _the raw material supply flow rate F _i , and a calculation function for calculating the average value F− _i of the raw material supply flow rate F _i for a fixed period. , an arithmetic function that calculates the rate of change ΔF- _i of this average value F- _i at regular intervals, and a delay that delays and outputs the ΔF- _i by the time required for the influence of the change in the raw material supply flow rate to appear at the separator outlet. circuit, a subtraction function that subtracts ΔF- _r at this point from ΔF- _i output from this delay circuit to obtain the rate of change ΔF- _{0 in the average value of the product flow rate, and a subtraction function that calculates the rate of change ΔF-0 in} the average value of the product flow rate. The grinding mill control device according to claim 1, further comprising a division function for calculating ΔF/− ₀ /ΔF _i by dividing by _i . 3 The means for calculating ΔF/- ₀ /ΔF _i consists of a product flow meter that detects the product flow rate F ₀ of the separator, an arithmetic function that calculates the average value F- 0 of the product flow rate F ₀ over a certain period, and a calculation function that calculates the average value F- ₀ of the product flow rate F 0 over a certain period − A calculation function to calculate the rate of change ΔF− ₀ for each fixed period, a supply flow meter to detect the raw material supply flow rate _{F i ,} and a calculation function to calculate the average value F− _i of the raw material supply flow rate F _i for a fixed period. , an arithmetic function that calculates the rate of change ΔF- _i of this average value F- _i every fixed period, and outputs the ΔF- _i delayed by the time required for the influence of the change in the raw material supply flow rate to appear at the outlet of the separator. A delay circuit and a division function that divides ΔF- ₀ at this point by ΔF- _i output from the delay circuit to obtain ΔF/- ₀ /ΔF _i . A grinding mill control device according to scope 1.