JPH0636469Y2 - Detector for consumption of bottom electrode of DC arc furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a furnace bottom electrode consumption amount detecting device for a DC arc furnace, and in particular, it is capable of accurately grasping the consumption state of the furnace bottom electrode. .

(Prior Art) Conventionally, for example, in a large-capacity arc furnace for steelmaking, an AC arc furnace has been the mainstream because it is easy to supply power and control voltage. On the other hand, in recent years, the capacity of semiconductor elements for electric power can be increased due to the progress of semiconductor technology, and accordingly, the arc furnace is also shifting from an AC arc furnace to a DC arc furnace. This DC arc furnace
The route to the transformer for the furnace and the equipment are the same as those of the AC type, but after the voltage is reduced to the furnace voltage by the transformer for the furnace, the AC is converted to DC by the rectifying device such as a thyristor device. Then, in the case of the thyristor system, the reactor is inserted in the DC circuit. Further, the DC circuit is composed of a secondary conductor (anode side) up to the furnace bottom electrode and a secondary conductor (cathode side) up to a movable electrode made of a carbon electrode.

A conventional AC arc furnace is always composed of three movable electrodes, but in the case of a DC arc furnace, it is not necessarily three, and at least one electrode may be used. That is,
It is possible to construct a single electrode up to about 150t furnace, and the circumference of the electrode is simple, but a furnace bottom electrode is required. The life and safety of this furnace bottom electrode are very important issues.

Now, the bottom electrode in a DC arc furnace is usually a furnace bottom refractory in the center of which is provided with a large number of current-carrying pins embedded as an anode. Also, each energizing pin is
An ordinary round bar is processed into an end, attached to a current collector plate and connected to a secondary conductor.Furthermore, the lower end of each current-carrying pin is forcibly air-cooled to prevent melting damage to the current-carrying pin in the refractory. There is. Of course, the portion of the refractory material in contact with the molten steel above the current-carrying pin melts, but as long as the refractory material is present, it melts and solidifies repeatedly, and is not consumed. However, when the refractory is worn out, the number of current-carrying pins will decrease accordingly.

(Problems to be Solved by the Invention) In such a DC arc furnace, the life of the bottom electrode is an important factor, and it is extremely important to manage the life. Therefore, conventionally, thermocouples are individually inserted into a large number of energizing pins to monitor the temperature of the energizing pins, and when the maximum temperature reaches the control limit temperature, the furnace bottom electrode is replaced.

However, such a method has the following problems. That is, the electrode temperature is not always in a reproducible proportional relationship with the remaining amount (remaining thickness) of the bottom electrode of the furnace, and other influences such as the hearth temperature, air-cooling condition, and energization current level are large. If the residual amount of the bottom electrode and the reduction amount are reduced, it is impossible to accurately and quantitatively grasp the consumption amount of the furnace bottom electrode. Therefore, although it is effective as a measure for preventing the bottom electrode of the bottom electrode from falling out, it has not been sufficiently utilized as the scheduling data for the bottom electrode replacement and the replacement determination data for reducing the unit consumption of the bottom electrode.

The present invention has been made to solve the above problems, and can accurately and easily grasp the amount of consumption of the bottom electrode, prevent the bottom electrode from falling out, and replace the bottom electrode. It is an object of the present invention to provide a highly reliable apparatus for detecting the amount of consumption of the bottom electrode of a DC arc furnace, which is highly effective for the scheduling and reduction of the unit consumption of the bottom electrode.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, at least two electrodes embedded with insulators in a structure of a bottom electrode in a DC arc furnace, and Of which, the standard 1
The present invention is configured by including a conductivity detecting means for detecting conductivity between the book electrode and another electrode.

(Operation) Therefore, in the furnace bottom electrode consumption amount detecting device of the present invention,
When the furnace bottom electrode is consumed and the upper surface of the refractory that contacts molten steel decreases,
Since the molten steel comes into contact with the upper ends of the two electrodes buried with the insulators in between before the exhaustion, the electrical conductivity between the electrodes is detected by the electrical conductivity detecting means, so that the consumption of the furnace bottom electrode is reduced. It becomes possible to detect.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of the configuration of a furnace bottom electrode wear amount detecting device for a DC arc furnace according to the present invention. In FIG. 1, in a furnace bottom refractory 2 in the center of the furnace, which constitutes a part of the furnace bottom electrode 1 of the DC arc furnace, as shown in the drawing, a steel current-carrying pin 3 is used.
Are embedded to form an anode. Also, each energizing pin 3
Is a steel round bar that is end-processed. These are attached to a current collector plate 4, connected to a secondary conductor 6 via a terminal 5, and a DC voltage is applied between it and a movable electrode (cathode) not shown. I am trying to do it. Further, the lower end of each energizing pin 3 is subjected to forced air cooling to prevent melting damage of the energizing pin in the refractory.

On the other hand, in the furnace bottom refractory 2 in the peripheral portion and the center portion of the furnace, a plurality of (two in this embodiment) rod-shaped electrodes 7 and 8 for detecting wear are embedded. Here, one reference electrode 7 is provided so as to penetrate from the bottom portion of the furnace bottom refractory 2 to the upper portion as shown in the figure, and the other electrode 8 is provided as the bottom portion of the furnace bottom refractory 2 as shown in the figure. From the center to the central position. Further, the lower end of the electrode 7 is connected to the power supply 11 via the conductor 91 and the relay 10, and the lower end of the electrode 8 is connected to the power supply 11 via the conductor 92. Further, the relay 10 operates to close a contact (not shown) to generate an alarm. And this conductor
The 91, 92, the relay 10, and the power supply 11 constitute a conductivity detecting means for detecting the conductivity between the electrodes. In FIG. 1, 12 is a refractory material forming the hearth of the DC arc furnace, and 13 is molten steel.

In the apparatus for detecting the amount of wear of the bottom electrode of the DC arc furnace configured as described above, at the beginning of the operation of the DC arc furnace, the furnace bottom refractory 2 is hardly consumed and the furnace bottom refractory contacting the molten steel 13 is consumed. The upper surface A of 2 is in the illustrated state. And
Since the furnace bottom refractory 2 is an insulator, two electrodes 7,8
No electric path is formed between them. Therefore, in this case, since the relay 10 does not operate, the alarm is not output, and it can be understood that the remaining amount of the furnace bottom refractory 2 is large, that is, the consumption amount of the furnace bottom electrode 1 is small.

Next, when the furnace bottom refractory 2 is consumed with the operation of the DC arc furnace, the upper surface A of the furnace bottom refractory 2 in contact with the molten steel 13 decreases.
Then, when the upper surface A of the furnace bottom refractory 2 is consumed up to the state of the broken line in the figure which is the upper end of the electrode 8, the two electrodes 7,
Since molten steel comes into contact with 8, an electric conduction path is formed by the power source 11 → conductor 92 → electrode 8 → molten steel 13 → electrode 7 → conductor 91 → relay 10 → power source 11. Therefore, in this case relay 10
Is activated and an alarm is output, and it is possible to understand that the remaining amount of the furnace bottom refractory 2 is small, that is, the consumption amount of the furnace bottom electrode 1 has increased and the limit has been reached.

As described above, the apparatus for detecting the amount of wear of the bottom electrode of the DC arc furnace according to the present embodiment has the following effects.

(A) It becomes possible to detect the state of wear of the furnace bottom electrode 1 (furnace bottom refractory 2) extremely accurately, easily, and accurately.

(B) By setting an alarm based on the consumption progress pattern data of the bottom electrode 1 (furnace bottom refractory 2), it becomes possible to fully utilize it for estimating and preparing the replacement time of the bottom electrode 1.

(C) Since the consumption state of the furnace bottom electrode 1 (furnace bottom refractory 2) can be accurately grasped, it is possible to reduce the unit consumption of the furnace bottom electrode 1.

(D) Since a conventional thermocouple is not used to detect the wear state of the bottom electrode 1 (furnace bottom refractory 2), there is no risk of damage or failure of the detector. It is possible to perform detection with extremely high reliability.

In the above-mentioned embodiment, the case where two wear detecting electrodes are buried is described. However, the present invention is not limited to this, and only three or more wear detecting electrodes are buried in the furnace bottom refractory, and each of them is buried. The upper end position may be provided with several levels and the alarms may be output by the corresponding number of steps.

FIG. 2 schematically shows the construction of an embodiment in which three electrodes are embedded in a furnace bottom refractory, and the same parts as those in FIG. 1 are designated by the same reference numerals. In FIG.
Reference numeral 14 is an electrode newly embedded in the furnace bottom refractory 2, and its lower end is connected to the power source 11 via the conductor 93 and the relay 15. Here, the upper end of the electrode 14 is the other electrodes 7 and 8
It is provided so as to be located approximately in the middle of the upper end of the. Further, when the relay 15 operates, a contact (not shown) is closed to generate an alarm. Therefore,
In this embodiment, since the alarm is output in two steps in association with the consumption of the furnace bottom refractory 2 of the furnace bottom electrode 1, it is possible to detect the consumption of the furnace bottom electrode with higher reliability.

Further, in the above-described embodiment, the current-carrying pin 3 of the furnace bottom electrode 1 itself may be used as the reference electrode 7.

Furthermore, in the above embodiment, a movable electrode of a DC arc furnace may be used as the reference electrode 7.

(Effect of the Invention) As described above, according to the present invention, it is possible to accurately and easily grasp the consumption amount of the bottom electrode, prevent the bottom electrode from falling out, and schedule the bottom electrode replacement. It is possible to provide a highly reliable apparatus for detecting the consumption of the bottom electrode of a DC arc furnace, which is highly effective in reducing the unit consumption of the bottom electrode.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a furnace bottom electrode wear amount detecting device for a DC arc furnace according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1 ... Furnace bottom electrode, 2 ... Furnace bottom refractory, 3 ... Current-carrying pin, 4 ... Current collector plate, 5 ... Terminal, 6 ... Secondary conductor, 7, 8, 14 ... Electrode, 91, 92,
93 ... Conductor, 10, 15 ... Relay, 11 ... Power supply, 12 ... Refractory, 13
… Molten steel.

Claims (1)

[Scope of utility model registration request] 1. At least two electrodes embedded in a structure of a bottom electrode in a DC arc furnace with an insulator therebetween, and one of the electrodes, which is a reference electrode, and another electrode. An apparatus for detecting the consumption of the bottom electrode of a DC arc furnace, comprising: an electric conductivity detecting means for detecting the electric conductivity between the electrodes.