JPH0731115Y2 - Molten steel arc heating equipment - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to a molten steel heating device for arc heating the molten steel in a vessel such as a ladle or a crucible furnace for the purpose of refining.

[Conventional technology]

Conventionally, as this type of arc heating device, a voltage is applied between a graphite electrode that is driven up and down and a metal bottom electrode made of metal provided on the bottom of the furnace to generate an arc between the graphite electrode and molten steel. Many things are used. However, the one using this furnace bottom electrode has a problem that replacement work is difficult when the furnace bottom electrode is consumed or damaged. Therefore, for example, as disclosed in Japanese Patent Publication No. 1-23916,
Instead of the bottom electrode, there has been proposed a type using a dipping electrode in which the lower end portion inserted from above into the furnace body is immersed in molten steel.

[Problems to be solved by the invention] However, in the case of using this immersion electrode, when the lower part of the immersion electrode is worn or damaged and the lower end is separated from the molten steel surface, an arc is generated between the molten steel and the immersion electrode, Generally, there is a problem that the lower end portion of the immersion electrode made of a metal material is rapidly melted and consumed, and further, the refractory material forming the furnace wall of the container near the immersion electrode is also consumed.

This invention solves the above-mentioned conventional problems, and an object thereof is to provide an arc heating apparatus for molten steel capable of preventing rapid consumption of immersion electrodes and furnace wall refractory due to arc generation.

[Means for Solving the Problems]

In order to achieve the above object, an arc heating apparatus for molten steel of the present invention comprises a container for containing molten steel, a heating electrode and an immersion electrode extending in the vertical direction, the lower end portion of the immersion electrode is immersed in the molten steel, and the heating is performed. In a molten steel heating device for heating molten steel by an arc generated between the electrode and the molten steel, the heating electrode and the immersion electrode are held by separate lifting drive devices, and the immersion electrode is provided with a hole penetrating in the longitudinal direction, On the upper part of the immersion electrode, an arc light detector is arranged so that the arc light generated at the lower end of the immersion electrode enters through the hole, and the arc light is received in response to the output signal of the arc light detector. A raising / lowering control device for issuing a lowering command signal to the raising / lowering drive device of the immersion electrode during generation is provided.

As the immersion electrode in the present invention, various conductive materials such as metal can be used, but if a steel material having the same composition as molten steel is used, melting can be performed simultaneously with refining. If an alloy material is used as the immersion electrode, alloy steel having a desired alloy component can be melted.

Further, as the arc photodetector in the present invention, it is possible to use, for example, a photodiode using a CdS or silicon, a phototransistor, or the like which uses various conversion elements for converting light into an electric current as photodetectors. Since the light quantity of the arc light is much larger than the light quantity emitted by the molten steel or the slag, the generation of the arc can be detected with sufficient certainty by the conversion element. It should be noted that arc light has more ultraviolet light components than molten steel and slag, so it is particularly preferable to use a conversion element having excellent sensitivity in the ultraviolet light region.

[Action]

In the molten steel arc heating device of the present invention, when the immersion electrode is consumed or damaged and its lower end is separated from the molten steel surface and an arc is generated between the immersion electrode and the molten steel, the arc light generated by the arc causes the immersion electrode to pass through the hole of the immersion electrode. After that, it reaches the arc light detector. The elevating controller outputs a descending command signal to the elevating / lowering device in response to the output signal of the arc light detector, and the immersion electrode is driven in the descending direction so that the tip of the immersion electrode is immersed in the molten steel and the arc disappears in a short time. The consumption of the immersion electrode and the refractory on the furnace wall due to the arc is suppressed to a small amount.

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

In the figure, reference numeral 1 is a ladle which is a container, and is made by lining a refractory material on an iron skin. 2 is molten steel and 3 is slag. Reference numeral 4 is a heating electrode made of graphite, and 5 is an elevating / lowering device for holding the heating electrode 4. And the wire wound around the winding drum 9 driven by the motor 8.
10 is wound around a pulley 11 attached to the lower end of the electrode column 7. Further, 14 is a steel immersion electrode, 15 is a lifting drive device for holding the immersion electrode 14, the base of the electrode support arm 16 having a holder 16a at the tip, the upper end of the electrode column 17 guided to move up and down. The winding drum 19 which is fixed and driven by the motor 18
The wire 20 wound around the wire is wound around a pulley 21 attached to the lower end of the electrode column 17. The immersion electrode 14 is provided with a hole 22 penetrating in the longitudinal direction, and an arc light detector 23 composed of a photocell is attached to the upper end of the immersion electrode 14 with the light receiving surface facing the hole 22. There is. 24 is a lift control device, which compares the output signal of the arc light detector 23 with the current setting value corresponding to the minimum light amount at the time of arc generation, and outputs an arc generation signal S _a , and this arc detection circuit 25. In response to the generation signal S _a , the motor 18 is provided with a descending command signal S _d to drive the motor 18 in the descending direction of the immersion electrode 14, and a motor control circuit 26. Further, 30 is a heating control device, which applies a DC voltage between the heating electrode 4 and the immersion electrode 14 according to a known DC arc furnace control method such as constant electric power or constant voltage, and moves up and down via a lifting control device 31. The motor 8 of the drive unit 5 is provided with a heating electrode up / down command.

In order to perform the refining of the molten steel 2 in the DC ladle refining apparatus 35 having the above-mentioned configuration, a dimension measuring sensor between the upper end of the ladle and the molten steel surface (not shown) is based on the initial length of the immersion electrode 14 at the start of operation. Then, a signal is given to the motor control circuit 26, and the lower part of the immersion electrode 14 is immersed in the molten steel 2 to a predetermined depth to start the operation. By applying DC power from the heating control device 30, an arc 36 is generated between the heating electrode 4 and the molten steel 2 for refining, but the light receiving surface of the arc photodetector 23 faces the hole 22 of the immersion electrode 14. Therefore, the arc light of the arc 36 of the heating electrode 4 does not reach the arc detector 23. Further, the light emitted from the molten steel 2 has a lower light intensity than the arc light, and the arc light detector 23
Only outputs a small current corresponding to this low light level,
The arc detection circuit 25 does not generate an output. When the lower part of the immersion electrode 14 is consumed or damaged due to the progress of refining and the lower end thereof is separated from the upper surface of the molten steel 2, an arc is generated between the lower end and the molten steel 2. The arc light of this arc is incident on the arc light detector 23 as a large amount of light, the arc detection circuit 25 emits an arc detection signal S _a due to the large current output generated by the arc light detector 23, and in response to this, the motor control is performed. Since the circuit 26 outputs the descending command signal S _d to the motor 18, the elevating / lowering drive device 15 drives the immersion electrode 14 in the descending direction. When the lower end of the immersion electrode 14 is immersed in the molten steel 2, the arc is stopped, so that the output current of the arc photodetector 23 becomes a small current and the immersion electrode lowering operation is stopped, and refining is continued.

As described above, the immersion electrode 14 returns to the immersion state in a short time after the arc is generated, so that the arc of the immersion electrode 14 can reduce the consumption and the consumption of the furnace wall refractory of the ladle 1 near the immersion electrode 14 to a small amount. is there.

The present invention is not limited to the above-described embodiment, and, for example, the material of each electrode, the arc light detector 23, and the lifting control device.
The specific configurations of 24, the lifting drive device 15, etc. may be other than the above. Also, as shown in FIG.
The upper end of the hole 22 may be closed and the arc detector 23 may be attached to the upper side of the immersion electrode 14.

Further, the heating device for heating the molten steel by the direct current arc has been described above, but the present invention can be applied to a heating device for heating the molten steel by the alternating current arc.

[Effect of device]

As described above, according to this invention, when an arc is generated between the immersion electrode and the molten steel, the immersion electrode is driven downward based on the detection signal of the arc photodetector, and the arc is extinguished in a short time. It is possible to prevent rapid consumption of the immersion electrode and the furnace wall refractory due to the arc. Further, since the immersion electrode may be arranged in the vicinity of the furnace wall, the heating electrode can be arranged in the central part of the container far from the furnace wall, and the consumption of the furnace wall refractory due to the arc of the heating electrode can be suppressed to a small amount. it can.

[Brief description of drawings]

FIG. 1 is a device layout connection diagram of a DC ladle refining device showing an embodiment of the present invention, and FIG. 2 is a longitudinal sectional view showing another embodiment of the immersion electrode. 1 ... Ladle (container), 2 ... Molten steel, 4 ... Heating electrode, 5
...... Lifting drive device, 14 ...... Immersion electrode, 15 ...... Lifting drive device, 18 ...... Motor, 23 ...... Arc light detector, 24 ...... Lifting control device, 25 ...... Arc detection circuit, 26 ...... Motor Control circuit, 35 ... DC ladle refining device.

Claims (1)

[Scope of utility model registration request] 1. A container for containing molten steel, and a heating electrode and a dipping electrode extending in the vertical direction, the lower end of the dipping electrode is dipped in the molten steel, and an arc generated between the heating electrode and the molten steel is used to remove the molten steel. In a molten steel arc heating device for heating, the heating electrode and the immersion electrode are held by separate lifting and lowering drive devices, a hole penetrating in the longitudinal direction is provided in the immersion electrode, and the immersion electrode is provided above the immersion electrode. The arc light detector is arranged so that the arc light generated at the lower end enters through the hole, and while the arc light is generated by receiving the output signal of the arc light detector, the immersion electrode An arc heating device for molten steel, comprising an elevating control device for issuing a descending command signal to an elevating drive device.