JP2012117792A - Cooling method of electric furnace electrode lifting mast - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling method which prevents cooling defects in a top part of a lifting mast which moves up/down an electrode support beam, for supporting an electrode of an electric furnace.SOLUTION: Cooling water, which cools a lower box 7 having a box structure on the top part 3b of the lifting mast, is fed to a top part central box 1. A pipe 9 is extended to the neighborhood of a top part central box upper surface 2 and is disposed so that the cooling water hits the top part central box upper surface 2 first. The temperature rise of cooling water is avoided and the top part central box upper surface 2 is effectively cooled, and when the top part central box 1 is filled with cooling water, the cooling water passes through a pipe 4 from the top part central box 1 and is supplied to a top part-surrounding box 3 to perform cooling. In such a case, an air vent hole 6 is disposed on the uppermost part of a top part central box lateral surface 5 of the lifting mast 3a, air in the top part central box 1 of the lifting mast is extracted, the top part central box 1 is filled with the cooling water to the top part central box upper surface 2 and effective cooling is performed.

Description

  The present invention relates to a method for cooling an electrode raising / lowering mast in a three-phase AC type and DC type electric furnace.

  In general, a three-phase AC electric furnace has three graphite electrodes, and a DC electric furnace has one graphite electrode, which is inserted into the furnace in advance. An arc is generated between the electrodes to melt the material and heat the molten steel.

  And in an electric furnace, since it is necessary to control the insertion amount of the graphite electrode into the furnace, an electrode support device composed of an electrode holder for holding the electrode and an electrode support beam integrally formed with the electrode holder is indispensable. . In these, the invention of the electrode support apparatus applied to a three-phase alternating current system electric furnace is proposed (for example, refer patent document 1). Taking this Patent Document 1 as an example, it has a configuration as shown in FIG. 3 (side view) and FIG. 4 (plan view).

  In these drawings, 1a is a graphite electrode inserted into the furnace, 2a is an electrode holder for holding the graphite electrode 1a, 10 is an electrode support beam, 4a is a terminal, 5a is the terminal 4a and a furnace transformer (not shown). )) Is shown. Here, the electrode support beam 10 is made of a conductor made of copper or aluminum alloy for supplying a large current. When the electric furnace is operated, the electrode support beam 10 is large from the terminal 4a to the graphite electrode 1a via the electrode support beam 10 and the electrode holder 2a. Current is supplied. Further, the electrode support beam 10 is supported by the elevating mast 3a, and is controlled to be driven in the vertical direction by the elevating mast 3a to adjust the insertion amount of each graphite electrode 1a into the furnace, thereby generating a stable arc. It is like that.

  Since FIG. 4 is a three-phase AC arc furnace, the number of graphite electrodes 1a is three, and the electrode support device composed of the electrode holder 2a and the electrode support beam 10 is necessarily three. In the case of a DC electric furnace, one electrode holder and one electrode support device are sufficient.

  An electrode support device consisting of an electrode holder and an electrode support beam generates heat due to its internal resistance and induction heating when a large current is applied during operation, and from a flame or gas blown out of the furnace, or from a red hot electrode. Heated by radiation or heat conduction. Similarly, the contact surface between the electrode support beam and the lifting mast and the top of the lifting mast are also heated. Here, in order to prevent these thermal deformation and erosion damage, these always need to be cooled, and normally the function of cooling by a water flow method using cooling water as a cooling medium as described in Patent Document 1. Is given. However, since the elevating mast is driven and controlled in the vertical direction, the elevating mast usually has a vertical structure, and air bubbles are present in the cooling water as the cooling medium, so that the cooling water is passed through the elevating mast which is a vertical structure. When the water is used, air having a specific gravity lower than that of the cooling water is accumulated in the upper part to form an air layer, and the air layer causes poor cooling. When cooling was poor, there were problems such as the upper end of the lifting mast being deformed or causing water leakage.

Japanese Patent No. 3678379

  The problem to be solved by the present invention is to provide a cooling method for preventing poor cooling at the top of a lifting mast that supports and lifts an electrode of an electric furnace.

  The method of the present invention, which is a means for solving the above problems, will be described with reference to the drawings. The method of the first invention is a box structure from a top central box, a top peripheral box surrounding the periphery of the top central box, and a lower box disposed below the top central box so that the top of the lifting mast is uniformly cooled with cooling water. First, in order to cool the top of the lifting mast of the box structure, cooling water is supplied to the lower box and the lower box is water-cooled. Subsequently, the cooling water obtained by cooling the lower box with water is supplied to the top central box through a water supply pipe to the top central box. The top central box is cooled by filling the cooling water up to the top central box upper surface while pushing the air accumulated on the top central box upper surface by the water supply from the air vent opening at the top of the top central box side wall. Furthermore, the electric furnace electrode lifting mast comprising a method of cooling the top peripheral box by supplying water to the top peripheral box by using water supply piping in which cooling water obtained by cooling the top central box with water is provided from the top central box to the top peripheral box. It is a cooling method.

  The method of the second invention is such that the cooling water obtained by cooling the lower box with water is supplied to the top central box by the water supply pipe to the top central box. The water supply pipe to the top central box is extended to the vicinity of the top surface of the top central box. To do. In this way, the electric furnace electrode lifting mast cooling method according to the means of claim 1, wherein the cooling water supplied from the lower box is supplied so that the cooling water directly hits the upper surface of the top central box.

  The following effects can be achieved by the method for cooling an electric furnace electrode lifting mast according to the method of the present invention. In the invention of the first means, since the air accumulated in the top central box of the lifting mast is efficiently removed, the cooling water is filled up to the top surface of the top central box, so that the top surface of the top central box can be effectively cooled. In the invention of the second means, the top central box of the lifting mast is supplied with cooling water from the lower box, so normally the top central box starts to accumulate cooling water from the lower surface, and finally the upper surface is filled with cooling water. It will be cooled. However, in this method, since the temperature of the cooling water rises while the cooling water is accumulated, the upper surface is finally cooled by the water whose temperature has risen, and the cooling efficiency is poor. Therefore, in the invention of the second means, since the cooling water supplied from the lower box is first piped so as to hit the top central box upper surface, the cooling water supplied into the top central box reaches the top central box upper surface. Temperature rise can be avoided, and the top central box upper surface of the lifting mast can be effectively cooled.

Elevating mast and electrode support beam side view (elevating mast part is a sectional view) Elevating mast top cross-sectional view (cross-sectional view taken along arrow AA in FIG. 1) Side view of electrode support device Plan view of electrode support device for three-phase AC arc furnace

  The form for implementing this invention is demonstrated using FIGS. 1-4. Generally, in an electric furnace, a graphite electrode 1a is inserted into the furnace, and an arc is generated between the graphite electrode 1a and a material such as iron scrap previously charged in the furnace to melt the material such as iron scrap. While making it molten steel, the molten steel is heated. And in an electric furnace, since it is necessary to control the insertion amount of the graphite electrode 1a in the furnace, the electrode support which consists of the electrode holder 2a which hold | grips the graphite electrode 1a, and the electrode support beam 10 comprised integrally with it Equipment is essential. The electrode support beam 10 is coupled to the upper end of the elevating mast 3a, and the elevating mast 3a is driven and controlled in the vertical direction to generate a stable arc by adjusting the amount of the graphite electrode 1a inserted into the furnace. It is like that.

  When a large current is applied during operation of the electric furnace, the electrode support device generates heat due to the internal resistance and induction heating of the electrode support device, and from the flame and gas blown up from the furnace, and further from the red hot graphite electrode 1a. Heated by radiation or heat conduction. Similarly, the contact surface between the electrode support beam 10 and the elevating mast 3a and the elevating mast top 3b are also heated. Therefore, it is necessary to always cool in order to prevent thermal deformation and melting loss of these members, and a cooling function is provided by a water flow method using cooling water as a cooling medium. However, in the lifting mast 3a, as described above, the lifting mast 3a is normally vertically driven in order to drive and control the lifting mast 3a in the vertical direction. Since air bubbles are present, when cooling water is passed through the vertical elevating mast top portion 3b, which has a vertical structure, air having a specific gravity lower than that of the cooling water accumulates in the upper portion, resulting in poor cooling due to the air layer. When the cooling is poor, there are problems such as deformation of the upper end of the elevating mast 3a or water leakage.

  In the present invention, the top 3b of the lifting mast has a box structure for cooling uniformly, and when the top central box 1 is filled with cooling water, the top peripheral box 3 passes from the top central box 1 through the pipe 4. Cooling water is supplied to On the other hand, by providing an air vent hole 6 at the top of the top central box side surface 5 of the lift mast 3a, air accumulated in the top center box 1 of the lift mast is released and the top center box top surface 2 is filled with cooling water. The central box upper surface 2 can be effectively cooled.

  The top central box 1 of the lifting mast 3a is supplied with water from the lower box 7. The top central box 1 supplied with water from the lower box 7 is such that if the pipe 9 from the lower box 7 is opened to the bottom central box lower surface 8, cooling water begins to accumulate from the top central box lower surface 8, and finally The top central box upper surface 2 will be cooled. If it becomes like this, since the temperature of a cooling water will rise while cooling water accumulates and the top center box upper surface 2 will be cooled by the cooling water which temperature rose, the cause of the cooling failure of the top central box upper surface 2 It was. Therefore, in the means of the present invention, the piping 9 is provided extending to the vicinity of the top central box upper surface 2 so that the cooling water supplied from the lower box 7 first hits the top central box upper surface 2. By doing in this way, the temperature rise of a cooling water can be avoided and the top center box upper surface 2 of the raising / lowering mast 3a can be cooled effectively.

  Embodiments of the present invention will be described with reference to the drawings. 1 to 3, in general, an electric furnace is a material in which a graphite electrode 1a is inserted into the furnace and an arc is generated between a material such as iron scrap previously charged in the furnace and the graphite electrode 1a. Is melted to obtain molten steel, and the molten steel is heated.

  By the way, in the electric furnace, it is necessary to control the insertion amount of the graphite electrode 1a into the furnace. For this purpose, an electrode support device comprising an electrode holder 2a for holding the graphite electrode 1a and an electrode support beam 10 integrally formed with the electrode holder 2a is erected in the vicinity of the electric furnace as an indispensable device. The electrode support beam 10 is coupled to the upper end of the elevating mast 3a, and in order to stably support the electrode support beam 10, the upper portion of the elevating mast 3a directly below the electrode support beam 10 and the top central box 1 above the upper portion. The ribs 11 are reinforced with the lower surface of the top peripheral box 3 provided around the top. The elevating mast 3a whose upper part is reinforced by the ribs 11 is thus controlled in the vertical direction to adjust the insertion amount of the graphite electrode 1a into the furnace. Further, the lower surface of the top peripheral box and the upper side wall of the lift mast are reinforced by ribs, which are arranged around the top central box at the bottom of the electrode support beam connected to the upper end of the lift mast. As with the above-described lifting mast, a thermal load is also applied to the rib. Therefore, a cavity is provided inside the rib so that cooling and cooling can be performed, and water supply and drainage is provided to prevent thermal deformation and weld cracking.

  The interior of the elevating mast top 3b is a box structure formed by a top central box 1, a top peripheral box 3 surrounding the periphery, and a lower box 7 disposed below the top central box 1, and has a box structure. Box 1, top perimeter box 3, and lower box 7 are water cooled. The top central box 1 is provided with an air vent hole 6 at the top of the side wall so that the inside air can be sufficiently discharged by being replaced with the cooling water supplied, and the opening of the pipe 9 from the lower box 7 can be opened. It is provided in the vicinity of the top central box upper surface 2 and further has a pipe 4 for supplying cooling water from the top central box 1 to the top peripheral box 3.

  According to the embodiment having the above-described configuration, the cooling of the elevating mast top 3b is improved by the method of the means of the present invention, so that deformation of the contact surface between the elevating mast 3a and the electrode support beam 10 and water leakage can be avoided. it can.

DESCRIPTION OF SYMBOLS 1 Top center box 2 Top center box upper surface 3 Top periphery box 4 Water supply piping to top periphery box and drain piping of top center box used also 5 Top center box side surface 6 Air vent hole 7 Lower box 8 Top center box lower surface 9 Top center Water supply piping to box (drain piping for lower box)
DESCRIPTION OF SYMBOLS 10 Electrode support beam 11 Rib 1a Graphite electrode 2a Electrode holder 3a Elevating mast 3b Elevating mast top 4a Terminal

Claims (2)

  Formed into a box structure from a top central box provided at the top of a lifting mast that lifts and lowers an electrode support beam that supports an electrode of an electric furnace, a top peripheral box surrounding the periphery, and a lower box disposed below the top central box In order to cool the top of the lifting mast with water, cooling water is supplied to the lower box, the lower box is water-cooled, and the cooling water obtained by water cooling the lower box is supplied to the top central box through a water supply pipe to the top central box. The top central box was cooled with water by filling the top central box with the cooling water while pushing the air accumulated on the top central box upper surface from the air vent opening opened at the top of the top central box side wall, and the top central box was water cooled. Top perimeter box by water supply piping arranged cooling water from top central box to top perimeter box The method of cooling an electric furnace lift mast, characterized in that the water supply to cool the top periphery box.   The cooling water that has been cooled by the lower box is supplied to the top central box by the water supply pipe to the top central box.The water supply pipe to the top central box is extended to the vicinity of the top surface of the top central box, and the cooling water supplied from the lower box is The method for cooling an electric furnace electrode elevating mast according to claim 1, characterized in that it comprises a method of supplying water so as to directly contact the top surface of the top central box.

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