JP3290981B2 - Production method of molten copper - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing molten copper applied to, for example, a continuous melting and casting line for copper.

(Prior Art) A shaft furnace is known as a copper melting furnace. This furnace has a feature that combustion efficiency is good, but has a drawback that molten copper cannot be held. For this reason,
A holding furnace for holding molten copper is provided between the shaft furnace and the tundish.

FIG. 1 is a process system diagram of a continuous melting and casting line for copper. The raw material M is charged from a raw material charging inlet 10a of the shaft furnace 10, and the charged raw material is burned and melted by three burners 11A to 11C arranged at a lower part of the furnace 10.
The molten copper is once held in the holding furnace 14 via the rounder 12.
The holding furnace 14 serves as a buffer for the downstream process, and the holding amount is adjusted by tilting the holding furnace 14. The molten copper overflowing from the holding furnace 14 flows into the casting wheel 20 via the rounder 16 and the tundish 18, and the continuously cast copper is sent to a rolling equipment 22 where it is rolled into a wire or the like.

The burners provided in the lower part of the shaft furnace 10 are burners of three systems of A zone, B zone and C zone from below.
By controlling the fuel pressure of each burner 11A to 11C individually, the amount of molten copper and the temperature of molten copper are controlled, and the so-called overhang phenomenon (raw material is difficult to melt locally) Phenomenon).

Further, burners 13, 17, 15 are also provided in the rounders 12, 16 and the holding furnace 14, respectively, in order to maintain the molten copper temperature and to control the residual oxygen concentration in the molten copper.

(Problems to be Solved by the Invention) By the way, the raw material charged into the shaft furnace 10 is a mixture of electrolytic copper and turning chips, and the shape differs for each raw material charged, and the surface area / volume ratio varies and is constant. Without
Therefore, the amount of heat required for melting is not constant. In addition, since control is performed on heat, in this type of control, the delay time is one.
Very large, ~ 2 hours.

In order to solve this problem, conventionally, attempts have been made to control the fuel pressure of each burner by PID control, but modeling and parameter setting are difficult, and satisfactory results have not been obtained. That is, the conventional PID control method cannot maintain the amount of copper in the holding furnace, cannot control the molten copper temperature, lowers the combustion efficiency of the shaft furnace, results in an increase in fuel efficiency, and causes problems such as burner clogging. Various problems have occurred frequently, such as generation of smelting, unstable amount of molten copper oxygen, and occurrence of a shelf hanging phenomenon of raw materials in the furnace. For this reason, conventionally, as a method for producing molten copper, a manual operation method relying on the skill and experience of a skilled worker has been exclusively used.
Therefore, in order to perform efficient control, it is necessary for this operation to require a skilled person.

The present invention has been made in order to solve such a problem, and it is possible to maintain the molten copper amount within a predetermined value range and to keep the molten copper temperature constant without relying on skilled personnel and experience. It is an object of the present invention to provide a method for producing molten copper having high thermal efficiency.

(Means for Solving the Problems) In order to achieve the above-mentioned object, according to the present invention, the combustion amount of each burner of a shaft furnace and a holding furnace is controlled so that an appropriate amount of molten copper melted by the shaft furnace is discharged. In a method for producing molten copper that is temporarily stored in a holding furnace at an appropriate temperature, the amount of molten copper in the holding furnace is detected, and the temperature of the molten copper in the holding furnace or the temperature of the molten copper flowing out of the holding furnace is detected and detected. The rate of change of the molten copper amount is determined from the amount of molten copper, the rate of change of the molten copper temperature is determined from the detected molten copper temperature, the detected molten copper amount, the rate of molten copper change, the molten copper temperature,
And the rate of change of molten copper temperature as variables, a fuzzy amount corresponding to the burn amount of each burner is obtained from a membership function corresponding to each variable, and a burn amount of each burner is obtained from a logical OR of the obtained fuzzy amounts of each burner. The burner of the shaft furnace and the burner of the holding furnace are controlled in accordance with the obtained combustion amount of each burner, and the amount of molten copper and the temperature of the molten copper in the holding furnace are controlled within a required value range. A method for producing molten copper is provided.

(Function) Membership functions and fuzzy inference corresponding to each variable of molten copper amount, molten copper change rate, molten copper temperature, and molten copper temperature change rate are used to analyze the experience of thermal experts and control procedures by cans. Based on the relationship between the control of the burner of the shaft furnace and the burner of the holding furnace and the amount of molten copper and the temperature of the molten copper, the shaft furnace was prepared in advance so as to be able to cope with a time-delayed system. The relationship between the control of the burner and the burner in the holding furnace and the rate of change of molten copper amount and the rate of change of molten copper temperature has been added.

The control of the burner by fuzzy inference makes it possible to obtain an excellent control accuracy without inferior to the control by a heat expert.

Embodiment An embodiment of the present invention will be described below in detail with reference to the drawings. The process system of the copper continuous melting and casting line is as follows:
Since there is no change from the conventional one except for the sensor and the fuel pressure control device relating to the control of the present invention, the detailed description of the already described portions will be omitted.

The present invention is based on the following findings by the inventors. When the burner of each zone of the shaft furnace 10 of the copper continuous melting and casting line is manually controlled by a skilled person, unlike conventional PID control, there is almost no operation trouble such as a so-called shelf hanging phenomenon or burner clogging, and Focusing on the fact that the amount of molten copper and the temperature of molten copper in the holding furnace 14 can be maintained within an allowable range near the target value, various studies have led to the following findings.

A zone burner 11A at the bottom of shaft furnace 10
By controlling this, it has a great influence directly on the adjustment of the hot water temperature, and when the fuel pressure of the A zone burner 11A is too high, the above-mentioned shelf hanging phenomenon occurs. B zone burner
11B affects the amount of dissolution, and when it is desired to adjust the amount of dissolution without changing the temperature of the hot water, it is most effective to change the fuel pressure of the burner 11B. Also, burner 11C in C zone is
It greatly affects the amount of dissolution, and if it is too large, the temperature of the hot water may be lowered.

The inventors have found a control method using a fuzzy inference operation as means for reflecting these findings in automatic control.

FIGS. 1 and 2 show a control device applied to the method of the present invention. The control device (ECU) 30 includes an arithmetic circuit 30a, a fuzzy controller 30b, a burner fuel pressure control device 30c, and the like, which are connected in this order.

The tilt angle sensor 32 and the hot water temperature sensor 34 for detecting the temperature of the molten copper flowing out of the tundish 18 are provided on the input side of the arithmetic circuit 30a.
Is connected. The tilt angle sensor 32 detects the amount of molten copper in the holding furnace 14 by detecting the tilt angle of the holding furnace 14 instead of directly detecting the amount of molten copper in the holding furnace 14. Arithmetic circuit
A molten copper amount signal Ai1 and a molten copper temperature signal Ai2 are input to 30a from these sensors.

On the other hand, a control valve 11 for regulating the fuel pressure to the A zone burner 11A is provided on the output side of the burner fuel pressure control device 30c.
a, a control valve 11b for adjusting the fuel pressure to the B zone burner 11B, a control valve 11c for adjusting the fuel pressure to the C zone burner 11C, and a control valve 15a for adjusting the fuel pressure to the holding furnace burner 15; These valves are connected, and these valves are controlled by a drive signal output from the control device 30c.

The arithmetic circuit 30a uses the molten copper amount signal Ai1 and the molten copper temperature signal Ai2 as external input signals, and further calculates a time change of these signals by the following equation given by a general equation.

Y = h × [x (t0) −x (t)] where Y is an internal input variable, x (t0) and x
(T) is the amount of molten copper or the temperature of molten copper at times t0 and t, respectively, and h is a coefficient. When the variable x is the amount of molten copper, Y
Is the molten copper amount change rate ΔAi1, and when the molten copper temperature is the molten copper temperature change rate ΔAi2.

The arithmetic circuit 30a supplies these external input variables and internal input variables to the fuzzy controller 30b.

The fuzzy controller 30b, based on the input variables,
The fitness is estimated from a membership function prepared in advance for each variable. For example, FIGS. 3 and 4 show the membership functions of the molten copper amount Ai1 and the combustion amount Ao1 of the A zone burner 11A, respectively, and show a known mamdani (Mamd).
The fitness is calculated by the method of ani) (MAX-MIN method). In the figure, the label of the fuzzy set means NB = Negative Big NS = Negative Small ZE = Zero PS = Positive Small PB = Positive Big.

The following fuzzy inference is performed from the membership function as described above.

Rule 1) If the molten copper amount Ai1 is ZE and the molten copper temperature Ai2
Is PB, the adjustment amount Ao1 of the burner 11A is set to NS.

Rule 2) If the molten copper amount Ai1 is PB and the molten copper temperature Ai2
If is ZE, the adjustment amount Ao1 of the burner 11A is set to ZE (intermediate amount).

Rule 3) Such rules are prepared by the number of combinations of each fuzzy set of the membership function for the molten copper amount Ai1 and each fuzzy set of the membership function for the molten copper temperature Ai2. And the fuzzy quantity in the condition part of each rule is ANDed, and the fuzzy quantity in the conclusion part is also ANDed.

The following table is an example of a list of rules for fuzzy inference.

Then, the conclusion of each rule is determined by, for example, the method of the center of gravity (logical sum), and the degree of conformity of the combustion amount Ao1 of the burner 11A (fuzzy amount)
Is calculated.

The calculation of the degree of conformity of the combustion amount Ao1 of the burner 11A described above was performed based on the molten copper amount Ai1 and the molten copper temperature Ai2, but if necessary, a combination of the molten copper amount change rate ΔAi1 and the molten copper temperature Ai2, the molten copper temperature The similarity is calculated based on a combination of the change rate ΔAi2 and the molten copper temperature Ai2 and the like, and the final fitness of the burned amount Ao1 of the burner 11A is calculated by the logical sum of the computed fitnesses.

The table below is an example of a list of rules for fuzzy inference based on a combination of the molten copper temperature change rate ΔAi2 and the molten copper temperature Ai2.

Similarly, the burner amount of the burners 11B to 11C and the burner 14
The respective fitness levels (fuzzy amounts) of Ao2 to Ao4 are calculated.

The membership function and the rules of fuzzy inference are
It is necessary to set the optimum one according to the capacity, shape, etc. of the applied shaft furnace, holding furnace, rounder, tundish, etc., and these are set, for example, by the analysis of a questionnaire survey of a plurality of heat experts, experiments, etc. You.

The control output values Ao1 to Ao4 calculated by the fuzzy controller 30b are supplied to the burner fuel pressure control device 30c, converted into drive signals for the control valves 11a to 11c and 15a described above, and output to these valves.

FIG. 5 shows the time change of the amount of molten copper during the production of molten copper to which the method of the present invention is applied in comparison with the conventional manual control, and the time of the amount of molten copper by the fuzzy control of the method of the present invention. The change is the same or smaller than that of the conventional manual control in the amount of molten copper.

In the above-described embodiment, the molten copper amount and the molten copper temperature of the holding furnace and the time rate of change thereof were used as input variables. However, the rotational speed of the casting wheel, the molten copper temperature at the rounder 12, the molten copper The dissolved oxygen amount, the raw material charge amount, and the like may be used as input variables.
Further, the control output may be the burner burner of the rounders 12, 16 or the burner burner of the tundish 18.

(Effects of the Invention) As described above in detail, according to the method for producing molten copper of the present invention, the amount of molten copper in the holding furnace is detected, and the temperature of the molten copper in the holding furnace or the flow out of the holding furnace is detected. The molten copper temperature is detected, the rate of change of the molten copper amount is determined from the detected molten copper amount, the rate of change of the molten copper temperature is determined from the detected molten copper temperature, the detected molten copper amount, the molten copper amount change rate, Using the copper temperature and the molten copper temperature change rate as variables, a fuzzy amount corresponding to the combustion amount of each burner is obtained from a membership function corresponding to each variable, and each burner is obtained from a logical sum of the obtained fuzzy amounts of each burner. The burner of the shaft furnace and the burner of the holding furnace were controlled in accordance with the obtained burner of each burner, and the amount of molten copper and the temperature of the molten copper in the holding furnace were controlled within a required value range. Therefore, it is possible to automatically control complex control systems with time delays, At least the same control as the control operated by the kneading operator can be realized. And, since extremely stable control can be realized for the target molten copper amount and the target molten copper temperature, as a result, the fuel saving effect is large, and the excellent effect that the ingot quality can be stabilized can be improved. Play.

[Brief description of the drawings]

1 is a layout diagram of a continuous melting and casting apparatus to which the method of the present invention is applied, FIG. 2 is a block diagram showing an internal configuration of a control unit (ECU) 30, and FIG. 3 is a membership function with respect to a molten copper amount Ai1. FIG. 4 is a graph showing a membership function of the burner Ao1 in the A zone disposed at the lower part of the shaft furnace with respect to the combustion amount Ao1, and FIG. 5 is a graph showing the molten copper Ai1 when the molten copper is produced by the method of the present invention. 5 is a graph showing a time change of the graph. 10: shaft furnace, 11A-11C: burner, 12: rounder, 14: holding furnace, 15: burner, 16: rounder, 18
…… Tandish, 20 …… Cast wheel, 30 …… Control device (EC
U), 32: tilt angle sensor, 34: molten copper temperature sensor.

Claims (1)

(57) [Claims] 1. A method of manufacturing molten copper, comprising: controlling a combustion amount of each burner of a shaft furnace and a holding furnace to store an appropriate amount of molten copper melted by the shaft furnace once at an appropriate temperature in the holding furnace. The amount of molten copper in the holding furnace is detected, the temperature of the molten copper in the holding furnace or the temperature of the molten copper flowing out of the holding furnace is detected, and the rate of change in the amount of molten copper is calculated from the detected amount of molten copper. The change rate of the molten copper temperature is determined from the temperature, and the detected molten metal amount, the molten copper amount change rate, the molten copper temperature, and the molten copper temperature change rate are each a variable, and the burner is determined from the membership function corresponding to each variable. The fuzzy amount corresponding to the burned amount of each burner is obtained, the burned amount of each burner is obtained from the OR of the obtained fuzzy amounts of each burner, and the burners of the shaft furnace and the holding furnace according to the obtained burned amount of each burner. To control the amount of molten copper and the temperature of molten copper in the holding furnace. A method for producing molten copper, which is controlled to a required value range.