JPH01167575A - Dc arc furnace - Google Patents

Abstract

PURPOSE:To reduce the incurring of an electric loss through reduction of the number of electric contacts, by a method wherein a conductor part extending from an electrode clamp to the bus on the stationary secondary side of a DC source through an electrode support arm is formed by a flexible cable formed by inserting a conductor in a resilient substance hose. CONSTITUTION:An upper electrode 11 is supported by an electrode clamp 12 and an electrode support arm 13, and is elevatable by means of an electrode elevating mechanism 14. A conductor part extending from the electrode clamp 12 clamping the electrode 11 to the bus 19 on the stationary secondary side of a DC source 18 through the electrode arm 13 is formed by a flexible hose 16 having water cooling structure in which a conductor 15 is inserted into a resilient substance hose 14 and cooling water is fed to the interior thereof. Therefore, as compared with a DC arc furnace having a flexible cable connected to the other end side of a support arm bus approximately in parallel to the electrode support arm 13, the number of electrical connection parts is reduced, the incurring of an electric loss can be reduced, and the dissolution efficiency can be improved.

Description

[Detailed description of the invention] [Purpose of the invention]

(Industrial Application Field) The present invention relates to a direct current arc furnace used for steel manufacturing mainly using scrap as a raw material. (Prior art) Conventionally, the blast furnace-converter method, which uses iron ore as raw material, has been widely adopted as a method suitable for mass production. Electric furnace steelmaking has also been widely adopted. In this electric furnace steelmaking, AC arc furnaces are usually used, and as they gradually become larger and more powerful, UHP furnaces (ultra-high power furnaces) are developed, which is an alternative to the blast furnace-converter method. It has become established as a steel manufacturing method for mass production. However, in AC arc furnaces operated by UHP, there is a limit to the reduction of circuit impedance for effective use of high power energy, and the problem of flicker increases.
Since there is a limit to the electrode current density due to the electrode skin effect peculiar to alternating current, there has been some reconsideration of direct current arc furnaces that supply direct current between the upper electrode and the bottom electrode. This DC arc furnace has not made much progress until now due to workability reasons, but in recent years, high power capacity AC-
The development of rectifier equipment for C conversion has greatly contributed to this reconsideration, and the conventionally known DC arc furnace has a furnace cover that covers the top of the furnace body, which consists of furnace walls and a furnace shell. , an upper electrode connected to, for example, the cathode side of the DC power source is provided so as to be movable up and down, and a hearth bottom electrode connected to, for example, the anode side of the DC power source is provided at the bottom portion of the furnace body;
By generating a direct current arc between the upper electrode and the bottom electrode, the scrap charged into the furnace was heated and melted by the arc. In such a DC arc furnace, the diameter of the electrode is smaller at the same current value than in a conventional AC arc furnace, and due to this smaller diameter, the electrode surface oxidation loss is reduced, and the temperature at the tip of the electrode is lower than in an AC furnace. It is possible to bring about advantages such as a reduction in electrode consumption due to a reduction in graphite sublimation, a reduction in flicker level, and a reduction in the number of arc nozzles. (Problems to be Solved by the Invention) As described above, conventional DC arc furnaces have several advantages over AC arc furnaces, but the supply of DC power to the upper electrode is different from that of conventional AC arc furnaces. As in the case, a rigid support arm base &Ii (copper plate, copper pipe, etc.) is fixed in a nearly parallel state to an electrode support arm that can be raised and lowered and has an electrode clamp at the tip that grips the upper electrode, and this rigid support arm base One end side is electrically connected to the electrode clamp, and the other end side of the rigid support arm busbar is electrically connected to one end side of the flexible electric wire, and the other end side of the flexible electric wire is connected to a DC power source. (The configuration of the power connection part of an AC arc furnace is described in "Steel Handbook," p. 532, p. 10, Electric Furnace Steel Manufacturing Method (published by the Japan Iron and Steel Institute on December 25, 1981). , ), there are many electrical connections, which increases electrical loss, which is undesirable for reducing energy costs and improving melting efficiency. (Object of the Invention) This invention was made in view of the above-mentioned problems, and aims to reduce power loss due to electrical connections,
The purpose of the present invention is to provide a DC arc furnace that can reduce energy costs and improve melting efficiency.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a DC power source comprising an upper electrode connected to one side of a DC power source and held by an electrode clamp, and a bottom electrode connected to the other side of the DC power source. In the arc furnace, the conductor section from the electrode clamp to the fixed secondary side bus bar or rectifier of the DC power source via the electrode support arm is formed by a flexible cable in which the conductor is placed in an elastic hose. As necessary, the flexible cable constituting the conductor section from the electrode clamp to the fixed secondary side bus bar or rectifier of the DC power supply via the electrode support arm supplies cooling water into the elastic hose. It is characterized by a water-cooled structure that cools the conductor. (Embodiment) FIG. 1 shows an embodiment of a DC arc furnace according to the present invention. This DC arc furnace 1 consists of pillars 3 installed on the base flpZ.
．． The furnace body 5 is supported by the furnace body 5, and a furnace lid 6 is disposed on the furnace body 5.The furnace M6 is suspended by a support 7, and can be moved up and down and rotated. In addition, the electrodes penetrate through the reactor lid 6 and are arranged at equal intervals (12
Upper electrode 1 consisting of three graphite electrodes, for example, with a spacing of 0'
1 is installed. These upper electrodes 11 are each supported by an electrode clamp 12, an electrode support arm 13, etc., and can be raised and lowered by an electrode lifting mechanism 14. Furthermore, the upper electrode 11 has, on its electrode clamp 12 side,
As shown in FIG. 2, a flexible cable 16 has a conductor 15 inserted into an elastic hose 14 made of, for example, a rubber hose.
One end of the flexible cable 16 is electrically connected, and the middle part of the flexible cable 16 is supported by a bracket 17° 17 provided on the electrode support arm 13, and the other end of the flexible cable 16 is It is connected to the cathode side of the rectifier 20 of the DC power source 18, in this embodiment, the rectifier 20 via a fixed secondary bus 19 connected to the DC power source 18. Further, the flexible cable 16 is a water-cooled cable that supplies cooling water into the elastic hose 14 to cool the conductor 15. Furthermore, a furnace body tilting mechanism 26 is provided on the foundation 2, and an exhaust gas duct 27 is provided on the upper portion of the furnace. Further, in the bottom part of the furnace body 5, electrodes are arranged at equal intervals in the circumferential direction on the same electrode pitch circle centered on the core C (120
Three furnace bottom electrodes 25 made of, for example, a conductive metal are arranged in a penetrating manner at the bottom electrode 25, and each furnace bottom electrode 25 is connected to a rectifier 20 of the DC power source 18, in this embodiment, a rectifier 20 by an electrode lead (not shown). It is connected to the anode side of. In the DC arc furnace 1 having such a configuration, the fixed secondary bus 19 of the DC power supply 18 (which may be a rectifier 20 in other embodiments) is connected from the electrode clamp 12 that grips the upper electrode 11 through the electrode support arm 13. Since the conductor part up to the electrode support arm (. 13) Compared to a DC arc furnace that adopts the structure of an AC arc furnace as it is, in which a flexible electric wire is connected to the other end of the support arm busbar using a rigid support arm busbar installed almost parallel to the The number of electrically connected parts is reduced, electrical loss in the connected parts can be reduced, energy costs can be reduced, and melting efficiency can be improved. Next, in the DC arc furnace 1 having the above structure, the capacity □Volume 2
When melting was carried out while cooling the conductor 15 by flowing cooling water into the elastic hose 14 of the flexible cable 16, a rigid support made almost parallel to the electrode support arm (13) was formed. Power consumption could be reduced by about 5% compared to the case where power was supplied using arm busbars and flexible electric wires. In addition, in the above embodiment, the upper electrode 11 and the hearth bottom electrode 2
5 are both 3 trees, but the number is not limited to this, and the fixed secondary side bus 19 can be abolished,
The flexible cable 16 may be connected directly to the rectifier 20 of the DC power supply 18.

Effects of the Invention As described above, the present invention includes an upper electrode connected to one side of a DC power source and held by an electrode clamp, and a bottom electrode connected to the other side of the DC power source. In the DC arc furnace, the conductor section from the electrode clamp to the fixed secondary side bus bar or rectifier of the DC power source via the electrode support arm is constructed of a flexible cable in which the conductor is placed in an elastic hose. In addition to providing a rigid support arm busbar approximately parallel to the electrode support arm, the number of electrical contacts can be reduced compared to when flexible electric wires are connected to the support arm busbar, thereby further reducing electrical loss. It is possible to achieve remarkable effects of reducing energy costs and improving dissolution efficiency.

[Brief explanation of the drawing]

FIG. 1 is an explanatory view showing one embodiment of a DC air furnace according to the present invention, and FIG. 2 is a sectional view of a flexible cable. DESCRIPTION OF SYMBOLS 1... DC arc furnace, 11... Upper electrode 12... Electrode clamp, 13... Electrode support arm, 14... Elastic hose, 15... Conductor, 16... Flexibility Cable, 18... DC power supply, 19... Fixed secondary side bus bar, 20... Rectifier, 25... Hearth bottom electrode. Representative Patent Attorney Yutaka Oshio

Claims (2)

[Claims] (1) In a DC arc furnace equipped with an upper electrode connected to one side of a DC power source and held by an electrode clamp, and a bottom electrode connected to the other side of the DC power source, an electrode support arm is connected to the electrode clamp. The DC arc furnace side is characterized in that the conductor portion from the DC power supply to the fixed secondary side bus bar or the rectifier is constituted by a flexible cable having a conductor inserted in an elastic hose. (2) The flexible cable that constitutes the conductor from the electrode clamp to the fixed secondary bus or rectifier of the DC power supply via the electrode support arm is water-cooled by supplying cooling water into the elastic hose to cool the conductor. The DC arc furnace according to claim 1, which is a cable.