JPH0449033B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electrode insertion control device for a direct current melting furnace, and more particularly to a control device that inserts an electrode into the furnace as the electrode wears out. .

[Prior Art] Conventionally, a directly energized melting furnace has been used as an apparatus for melting glass raw materials, various industrial wastes, municipal garbage, and the like.

This direct energization type melting furnace is a heating furnace that forcibly passes an electric current through the material to be melted, thereby generating Joule heat to raise the temperature of the material to be processed, thereby melting the material.

The above-mentioned direct energization type melting furnace applies electricity directly to the object to be processed, so a plurality of electrodes are inserted into the object to be processed.

However, the length of the electrode gradually becomes shorter over time due to erosion or abrasion caused by the object to be treated. Therefore, the distance between the electrodes gradually increases, and the electrical resistance between the electrodes increases. As a result, the amount of current decreases at the same voltage, making it impossible to maintain a constant molten state of the object to be processed inside. In this case, if you adjust the current amount to keep it constant, the resistance will increase, so conversely,
A situation also occurred in which more Joule heat was generated than necessary and the object to be treated was heated too much, resulting in a change in the molten state and wasted energy.

Therefore, as the length of the electrodes is gradually reduced, it is necessary to insert the electrodes into the furnace so that the distance between the electrodes within the furnace is always constant. However, since the adjustment work involves electrodes that are carrying a high current and are under high temperature, in reality, the electrodes are considerably worn out and the time is shortened, considering safety and the complexity of the adjustment work. Adjustments between the electrodes could not be made until after this. As a result, more current is passed than necessary, or the amount of current is insufficient, making it difficult to precisely control the temperature inside the furnace or the melting state, which has an adverse effect on the quality of the objects to be processed inside.

[Object of the Invention] Therefore, it is an object of the present invention to provide a control device that automates the above-mentioned dangerous and complicated adjustment work and that maintains the distance between the electrodes within the furnace substantially constant at all times.

[Structure of the Invention] The gist of the present invention is, as shown in the basic configuration diagram in FIG. In the electrode insertion control device M4 of the energized melting processing furnace M3, an electrode insertion means M5 for inserting the electrode M1 into the melting processing furnace M3, an electrical resistance value detection means M6 for detecting the electrical resistance value between the electrodes M1, When the electrical resistance value between the electrodes M1 exceeds a predetermined value, the electrode insertion means M5 is driven and the electrode M1 is inserted.
An electrode insertion control device M4 for a directly energized melting furnace M3 is provided with a control means M7 for controlling the insertion of a predetermined amount of electrode No. 1 into the melting furnace M3. M8 is a power supply.

Next, embodiments of the present invention will be described based on the drawings.

[Embodiment] FIG. 2 is a schematic system diagram showing an embodiment of the electrode insertion control device for a direct current type melting processing furnace of the present invention. Here, reference numeral 1 indicates a direct energization type melting furnace, which is made of a refractory material, and electrode insertion holes 5 and 6 are provided at two locations on the furnace wall 3 on the side surface thereof, with the central axis of the melting furnace 1 being the central axis. .

Electrodes 7 and 8 made of metal molybdenum or graphite are supported by electrode holders 9 and 10 and inserted into the electrode insertion ports 5 and 6, and the tips 7a and 8a of the electrodes 7 and 8 are connected to the melting furnace 1. It has invaded the object to be processed 11 inside.

One of the electrodes 7 is connected to a conductive wire 13, and the other end of the conductive wire 13 is connected to one pole of a power source 15. The other electrode 8 is connected to a conductor 17 and connected to the other pole of a power source 15 via a switch 19 and an ammeter 21.

Further, a voltage source 23 for measuring the voltage between the electrodes 7 and 8 is connected between the two conducting wires 13 and 17.

Further, the electrodes 7 and 8 are provided with electrode insertion devices 25 and 27.
are attached, and their driving devices 29 and 31 function to feed the electrodes 7 and 8 toward the inside of the melting processing furnace 1 as necessary. The above electrode insertion device 2
5 and 27 are configured, for example, to hold the electrodes 7 and 8 with two rollers and send out the required amount of the electrodes 7 and 8 into the melting processing furnace 1 by rotation of a servo motor or the like connected to the rollers. . The drive devices 29 and 31 can be configured to control the amount of current and the time period for which the current is applied to the motors.

The electrode holders 9 and 10 have completely sealed cooling water passages 9a and 10a formed therein, and cooling water flows into the cooling water passages 9a and 10a in response to switching of the switching valve 33. supplied or stopped. However, when the switching valve 33 stops supplying the cooling water, air is sent into the cooling water passages 9a, 10a of the electrode holders 9, 10, and the cooling water inside is completely replaced with air. Further, the switching valve 33 switches between the cooling water and air as described above by means of its driving device 35.

Further, on the inner surface of the processing furnace 1 of one electrode holder 10, there is a temperature detector 37 for measuring the electrode holder surface temperature.
is attached to output a signal corresponding to the temperature of the inner surface of the processing furnace 1 of the electrode holder 10.

39 is an arithmetic control circuit, which operates the driving device 2 of the electrode insertion devices 25 and 27 based on signals input from the ammeter 21, voltmeter 23, and temperature detector 37.
9, 31 or to the drive device 35 of the switching valve 33,
By outputting a drive signal, the amount of insertion of the electrodes 7 and 8 or switching of the switching valve 33 is controlled.

As shown in FIG. 3, the arithmetic control circuit 39 is constituted by a microcomputer. Here, the calculation control circuit 39 includes a CPU 40, a fixed memory ROM 41 in which control programs and various data necessary for calculation are stored, a RAM 42 for temporary storage,
The device includes a backup RAM 43 whose power is backed up by a battery so as to retain memory even after the power switch is turned off, an input/output port 44, and an output port 45, and each element is connected by a bus line 46. The input/output port 44 includes buffer circuits 47, 48, 49 and a multiplexer 5.
The output signals of an ammeter 21, a voltmeter 23, and a temperature detector 37 are connected via an A/D converter 51. Further, from the output port 45, a drive circuit 52,
A control signal is output to the drive circuits 52, 53, 54, and the drive circuits 29, 31 of the electrode insertion devices 25, 27 and the switching valve 33, respectively.
A drive current is output to the drive device 35 of.

Among the above-mentioned configurations, the combination of the electrode insertion devices 25, 27 and their driving devices 29, 31 corresponds to the electrode insertion means, and the combination of the ammeter 21 and the voltmeter 23 corresponds to the electrical resistance value detection means, and the calculation The control circuit 39 corresponds to control means.

Next, a flowchart of a first control example applied to this embodiment and executed by the arithmetic control circuit 39 is shown in FIG.

Here, 110 represents initial settings. For example, this is a process of driving the cooling water switching valve 33 and setting the cooling water to flow to the electrode holders 9 and 10. 120 represents a step in which the amount of current is read as A based on the detection signal from the ammeter 21, and the voltage is read as V based on the detection signal from the voltmeter 23. 130 represents a step for calculating the electrical resistance value between the electrodes 7 and 8. Here, the electrical resistance value R is calculated using the formula R=V/A. 140 is the electrical resistance value R obtained in step 130
represents the step of determining whether or not is greater than or equal to a predetermined value R1. 150 represents a step of switching the switching valve 33 from the cooling water side to the air side to supply air to the electrode holders 9 and 10. The process of step 150 is as follows:
This is done in order to raise the temperature of the electrode holders 9, 10, melt the stuck substances 11a, 11b around the electrodes 7, 8 shown in FIG. 2, and make the movement of the electrodes 7, 8 smooth. Returning to FIG. 4 again, 160 measures the temperature of the inner surface of the processing furnace 1 of the electrode holder 10 with the temperature detector
7 represents the step of reading as Th based on the detection signal of No. 7. 170 represents a step for determining whether the temperature Th determined in step 160 is 800° C. or higher. 180 represents a step of outputting a driving current to each driving device 29, 31 in order to drive the electrode insertion devices 25, 27 by a predetermined amount, for example, by an amount to restore the increased resistance. 190 represents a step for reading the amount of current A and voltage V, similar to step 120. 200 represents a step for calculating the electrical resistance value R, similar to step 130. Similar to step 140, 210 represents a step for determining whether the electrical resistance value R is greater than or equal to a predetermined value R1. Step 220 is switching valve 3
3 represents the step of switching from the air side to the cooling water side and supplying cooling water to the electrode holders 9 and 10. This prevents thermal deterioration of the electrodes 7, 8, holders 9, 10, etc., and also covers the periphery of the electrodes 7, 8 again with solidified material, allowing the object to be processed to be removed from between the electrode holders 9, 10 and the electrodes 7, 8. This is to prevent leakage.

When the processing of the first control example described above is started, initial settings are first made in step 110. Next, step 120 is executed, and the values of the current amount A and the voltage V are detected and read. Next step 130
The electrical resistance value R is calculated using the above values of V and A, and the next step 140 is performed based on the value of R.
A comparison is made with a predetermined value R1.

If the distance between electrodes 7 and 8 is appropriate, R
Since is less than R1, the determination here is "NO", and the process returns to step 120 to start the process of reading the current amount and voltage.

In this way, as long as the distance between the electrodes 7 and 8 is an appropriate distance, in this flowchart, steps 120,
Processes 130 and 140 will be repeated.

Next, if the electrodes 7 or 8 become shorter due to wear, erosion, etc., the resistance between the electrodes 7 and 8 will increase, but if the resistance exceeds the predetermined value R1, the process in step 140 will say "YES". ”. Next, step 150 is executed, and the electrode holder 9,
10, the supply of cooling water is stopped by the action of the switching valve 33, and air is replaced. Next, step 160 is executed and the temperature Th of the surface of the electrode holder 10 is read. Normally, the inside of the electrode holder 10 is cooled with cooling water, so the temperature detected by the temperature detector 37 is around 100°C, but in the process of step 150, the cooling water is stopped and air is replaced instead. Since the electrode holders 9 and 10 are replaced, the temperature of the electrode holders 9 and 10 will rapidly rise due to the heat in the furnace. If the temperature is lower than 800℃, it will be determined as "NO" in step 170.
The process of step 160 is repeated again, but if Th exceeds 800° C. or higher due to continued temperature rise, a determination of ``YES'' is made in step 170. This determines that the temperature at which the solidified materials 11a and 11b in the furnace 1 are completely melted has been exceeded.
Next, step 180 is executed, the electrode insertion device is driven for the first time, and a predetermined amount of the electrodes 7 and 8 are inserted into the melting furnace 1.
It will be inserted inside. Then step 190
is executed, the current amount A and the voltage V are read, and then the electrical resistance value R is calculated in step 200.
Next, in step 210, it is determined whether the electrical resistance value R is greater than or equal to R1. If the electrical resistance value R does not become less than R1 even if a certain amount of electrodes are inserted in one execution of step 180, a determination of "YES" is made in step 210, and step 180 is executed again.
A second fixed amount of electrode insertion is performed. In this way, the electrode insertion process is repeated until the electrical resistance value R becomes less than the predetermined value R1.

When the distance between the electrodes 7 and 8 is reduced to an appropriate distance and the electrical resistance R is less than the predetermined value R1, step
210 is determined as “NO”, then step 220
At the switching valve 33, cooling water is supplied to the electrode holders 9 and 10.
will be supplied by switching. As a result, the solidified materials 11a and 11b of the object to be processed 11 are again fixed to the surfaces of the electrode holders 9 and 10 exposed in the melting processing furnace 1 and in the vicinity thereof. As a result, the space between the electrodes 7, 8 and the electrode holders 9, 10 is sealed, and leakage of the melted material of the object to be processed 11 can be prevented. The process then returns to 120 and repeats the process as described above.

As described above, according to this control example, by always maintaining the distance between the electrodes 7 and 8 at an appropriate distance, it is possible to contribute to improving the efficiency of the melting operation and saving electrical energy, and furthermore, it is possible to contribute to improving the efficiency of the melting operation and saving electric energy. 11
By melting a and 11b in advance before inserting the electrodes, there is no need to push in the electrodes 7 and 8 with more force than necessary, the insertion devices 25 and 27 can be simple devices, and the electrodes 7 and 8 are not damaged. It's something that doesn't exist.

Next, FIG. 5 shows a second control example. This second control example is the first control example in which control for instructing when to replace the electrodes is added.

Here 320, 330, 340, 350, 360, 370,
390, 410, 420, 430 and 440 are steps 120, 130, 140, 150, 160, 170, 180, 190 of the first control example.
This represents a step that performs the same processing as the corresponding steps 200, 210, and 220.

310 represents the initial setting step, and the first
The switching valve 3 is configured to supply cooling water to the electrode holders 9 and 10 in the initial setting of step 110 in the control example.
In addition to switching the length L of the electrodes 7 and 8, the length L of the electrodes 7 and 8 is also set. 380 represents a step of determining whether the length L of the electrode is less than or equal to a predetermined value L1.
400 represents a step in which a value obtained by subtracting a predetermined length a from L is newly set as L. 450 is electrode 7,8
This represents the step of outputting a warning message using a buzzer, warning lamp, etc.

When the second control example as described above is started, the first control example starts.
As in the control example, as long as the electrical resistance value R is less than the predetermined value R1, the current amount A and the voltage V are read, and the process of calculating the electrical resistance value R is repeated. If the electrical resistance value R becomes equal to or greater than the predetermined value R1, a determination of "YES" is made in step 340, and then in step 350, the supply of cooling water to the electrode holders 9 and 10 is stopped, and the inside is replaced with air. will be done. Next, in steps 360 and 370, the solidified substances 11a and 11b of the object to be processed 11 are melted, and if they are melted, a determination of "YES" is made in step 370.
Next, step 380 is executed, and it is determined whether the length L of the electrodes 7, 8 is less than or equal to a predetermined value L1. Here, the length L of the electrodes is updated when the electrodes 7 and 8 are replaced. The value of this L is the backup RAM4.
3, so that the previous lengths of electrodes 7 and 8 can be used when the control device is restarted after the control device is powered off to stop the operation of the entire system. It's getting old. At this step 380, the electrodes 7 and 8 are not worn out yet, and the L
If the value exceeds L1, the determination is "NO", and then step 390 is executed, and the electrode insertion device is driven to insert a predetermined amount of electrodes 7 and 8 into the melting furnace 1. Next, in step 400, L is set to the value of La. Here, the value of a represents the amount inserted in step 390 above.
That is, in order to remember that the length L of the electrode has been reduced by the predetermined length a in step 390, L is subtracted in step 400. Then step 410
The current amount A and the voltage V are read in step 420, and then the electrical resistance value R is calculated in step 420. Then, in step 430, it is determined whether the electrical resistance value R is greater than or equal to a predetermined value R1. If the resistance value has not yet reached an appropriate value, return to step 380 again.
The length L of electrodes 7 and 8 is compared with L1, and L is still
If it is not below L1, step 390 is executed again and the process of inserting the electrode is repeated. Steps 380, 390, 400 above,
By repeating steps 410, 420, and 430, if R becomes less than R1 before L becomes less than L1, a determination of "NO" is made in step 430, and then, in step 440, the switching valve is set for the electrode holders 9 and 10. By switching 33, cooling water is supplied.
Then, the process returns to step 320 again.

On the other hand, while repeating the above steps, R
If L becomes less than or equal to L1 before becoming less than R1, a determination of ``YES'' is made in step 380, and then step 450 is executed. At step 450, a buzzer or lamp notifies the supervisor that replacement is necessary, and this control is ended and control of electrode insertion is stopped. In this way, the operation of the melting furnace 1 is stopped by the replacement warning displayed by the supervisor, and the electrodes 7 and 8 can be replaced at an appropriate time.

As described above, according to this control example, in addition to the effects of the first control example, the lifespan of the electrodes 7 and 8 can be automatically checked, and the electrodes 7 and 8 can be replaced at an appropriate time. This eliminates the need to replace the electrodes while they are still fully usable, or to replace them after they become unnecessarily short and difficult to control the distance between the electrodes, contributing to resource and energy savings.

[Effects of the Invention] According to the electrode insertion control device for a directly energized melting furnace of the present invention, the electrode insertion control device for a directly energized melting furnace has the following advantages: The electrode insertion control device includes: an electrode insertion means for inserting the electrode into the melting processing furnace; an electric resistance value detection means for detecting the electric resistance value between the electrodes; In this case, the electrode insertion means is driven and the electrode is inserted into the melting furnace by a predetermined amount with control means, so that the distance between the electrodes is always maintained at an appropriate state, so that the electric energy can be reduced. Since it is efficiently converted into thermal energy, it contributes to energy saving, maintains the quality of the melted material in the furnace at a constant level, increases yield, and also contributes to resource saving. Furthermore, as a side effect, it also leads to complete work.

[Brief explanation of the drawing]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a schematic system diagram showing one embodiment of the invention, Fig. 3 is a block diagram of its arithmetic control circuit, and Fig. 4 is the first embodiment of the above embodiment. FIG. 5 is a flowchart showing a control example. FIG. 5 is a flowchart of a second control example. 1... Direct current melting furnace, 7, 8... Electrode, 9, 10... Electrode holder, 21... Ammeter, 23... Voltmeter, 25, 27... Electrode insertion device, 33... Switching Valve, 37...Temperature detector, 39
...Arithmetic control circuit.

Claims (1)

[Scope of Claims] 1. An electrode insertion control device for a direct current melting furnace that inserts an electrode into a workpiece and melts the workpiece using Joule heat, wherein the electrode is inserted into the melting furnace. an electrode insertion means; an electric resistance value detection means for detecting an electric resistance value between the electrodes; and when the electric resistance value between the electrodes exceeds a predetermined value, the electrode insertion means is driven to insert the electrode into a melting processing furnace. 1. A control device for controlling the insertion of an electrode in a directly energized melting furnace, comprising: control means for controlling the electrode insertion by a predetermined amount into the melting furnace.