JPH0712874Y2 - Bottom electrode for DC arc furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a bottom electrode of a DC arc furnace.

[Conventional technology]

Generally, the life of the bottom electrode of a DC arc furnace is determined by measuring the temperature of the electrode rod using a thermocouple.The temperature detection value indicates the actual length of the electrode rod during melting. Since it is not an accurate representation, it is only a guideline for indicating the state of the electrode rod, and the thermocouple is affected by electromagnetic induction due to arc discharge between the electrodes, so the measured value itself is inaccurate. It was difficult to accurately detect the wear state of the.

[Problems to be solved by the device]

This invention solves the above-mentioned conventional problems, and an object thereof is to provide a bottom electrode for a DC arc furnace which can detect the worn state of an electrode rod with high accuracy.

[Means for Solving the Problems]

In order to achieve the above object, a bottom electrode for a DC arc furnace according to the present invention is a detection unit in which two metal wires are arranged in parallel at a small interval in a refractory surrounding the side surface of an electrode rod. A plurality of embedded upper end portions at different depth positions from the upper surface of the refractory, and connect each of the detection units to each other via a switching switch that switches and connects the desired detection unit to a conduction detection circuit. It is characterized in that it is connected to a detection circuit.

[Action]

In the furnace bottom electrode of the present invention, the refractory surrounding the side surface of the electrode rod is worn out by the furnace operation, and when the molten metal reaches the upper end of the detection unit, the two metal wires forming this detection unit are separated. Short-circuited by molten metal. This short circuit is detected by the continuity detection circuit, which indicates that the refractory has worn to the embedded upper end position of the detection unit. The electrode rod is melted and worn as the wear of the refractory surrounding the side surface progresses, and the upper end position of the electrode rod is near the upper position of the worn refractory. The upper end position of can be known. Also, since the wear of the refractory and the electrode rod is detected by a plurality of detection units with different upper end positions, it is possible to know the wear rate as well as the wear speed (progress of wear), and when the maximum wear amount is reached. Is easy to estimate,
The hearth electrode can be replaced safely and securely.

〔Example〕

 An embodiment of the present invention will be described below with reference to FIG.

In the figure, reference numeral 1 denotes a hearth for a DC arc furnace, which is formed by lining a hearth refractory 3 on a steel shell 2. 4 is an electrode rod made of a round copper rod,
The upper part or the middle part of a plurality of electrode rods 4 is embedded and fixed in a refractory material 5. Between the refractory material 5 layer and the hearth refractory material 3, an amorphous refractory material 6 is filled to form a refractory material 5. The hearth refractory 3 is integrated. Reference numeral 7 is a cover for attaching to the hearth floor, 8 is a connecting plate for power feeding, and a terminal plate 9 fixed to this connecting plate 8 is connected to a DC power source (not shown). Reference numerals 10a to 10d denote detection units, each of which is formed by arranging two metal wires 11 in parallel at a small interval, and the upper end of each refractory 5 is located at a different depth position from the upper surface 5a of the refractory 5 to be fire-resistant. It is buried in the object 5. Further, 12 is a continuity detection circuit, which is connected to one power supply circuit 13 for generating a predetermined DC voltage between two terminals and one terminal side of this power supply circuit 13 to detect the generation of a current and emit a buzzer detection signal. And a current detection circuit 14.
Reference numeral 15 is an interlocking type switching switch,
~ 10d so as to be sequentially connected to the continuity detection circuit 12,
Each detection unit 10a-10d is connected to each contact of this switching switch 15.

In the furnace bottom electrode 16 having the above-described configuration, first, as shown in the drawing, the power supply circuit 1 is connected to the detection unit 10a whose upper end is at the highest position.
The switching switch 15 is set so that the voltage of 3 is applied. When the refractory 5 is worn down to the position of the depth H indicated by the chain line 17 due to the furnace operation, the molten metal reaches the upper end position of the detection unit 10a and short-circuits the two metal wires 11 and 11 forming the detection unit 10a. . Since the current detection circuit 14 detects this short-circuit current and issues an alarm signal, the refractory 5
Is detected to the position of depth H. At this time, the electrode rod 4 is also worn down to the position of the depth H. Next, the switching switch 15 is switched to the state in which the voltage is applied to the detection unit 10b, and the refractory 5 is moved to the upper end position of the detection unit 10b.
Also, when the electrode rod 4 is worn, it can be detected by the operation of the continuity detecting circuit 12 in the same manner as described above, and the wear state can be sequentially detected by the detecting units 10c and 10d in the same manner. From the upper end position of each detection unit 10a to 10d and each conduction detection time, reaching the limit thickness of the refractory 5 and the limit length of the electrode rod 4 requiring electrode replacement (the wear depth is the maximum allowable value). Since it is possible to estimate the time), the furnace bottom electrode 16 may be replaced before that time.

It should be noted that in the above embodiment, the switching switch 15 is set at small time intervals.
If the continuity is detected while repeating the switching, the minimum thickness (maximum wear depth) of the refractory 5 at each point in time can be detected, for example, when the refractory 5 is locally deeply worn, and the safety can be improved. Is.

The present invention is not limited to the above embodiment, and the number and the installation position of the detection units may be other than those described above, and the conduction detection circuit 12 may have a circuit configuration other than the above. Further, a detection signal other than the buzzer sound may be issued as the continuity detection signal.

[Effect of device]

As described above, according to the present invention, the upper end positions of the refractory and the electrode rod can be detected by the conduction detection of the detection unit, and this detection directly detects not the temperature but the position, so that the wear state can be accurately detected. .

Also, the detection unit consists of two metal wires, and since it is not exposed on the bottom of the furnace at the beginning of operation, the penetration amount of the metal wire into the molten steel is very small and does not affect the quality of the molten steel. Also, the distance between the two metal wires is small, so
Local wear of the hearth can also be reliably detected. In addition, wear detection of refractories and electrode rods is performed by multiple detection units with different upper end positions, so the wear rate as well as the wear rate (progress of wear) can be known, and the estimation of the time when the maximum allowable wear amount is reached The hearth electrode can be replaced safely and securely. Further, since the switching switch is used, only one conduction detecting unit is required for a plurality of detecting units, and the cost of the apparatus is low.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a hearth electrode showing an embodiment of the present invention. 4 ... Electrode rod, 5 ... Refractory, 5a ... Top surface, 10a-10d ...
… Detection unit, 11 …… Metal wire, 12 …… Continuity detection circuit,
13 ... power supply circuit, 14 ... current detection circuit, 15 ... switching switch, 16 ... bottom electrode.

Claims (1)

[Scope of utility model registration request] 1. A detection unit formed by arranging two metal wires in parallel at a small interval in a refractory surrounding the side surface of an electrode rod, has an upper end portion at a different depth position from the upper surface of the refractory. , And a plurality of them are buried, and each of the detection units is connected to the continuity detection circuit via a switching switch for switching and connecting the desired detection unit to the continuity detection circuit. Bottom electrode.