JPH0722394U - DC arc furnace - Google Patents

Abstract

(57) [Abstract] [Purpose] To increase the melting angle of the arc in the furnace body by increasing the deflection angle of the arc toward the center of the furnace body. [Constitution] A furnace body 1 in which a lower electrode 13 arranged at a bottom portion and a refractory material 14 arranged at a peripheral side portion are supported by a jacket P.
Upper and lower conductors 21, 23 and upper and lower conductors, which are arranged so as to vertically penetrate two upper electrodes 19, 20 on a furnace lid 17 for covering 6, and are connected to the upper and lower electrodes 19, 13 and 20, 13, respectively. 22 and 24 are extended in directions away from each other, and the jacket P is made of the non-magnetic material 15, so that the magnetic field generated by the current passing through the lower conductors 23 and 24 is applied to the jacket P.
Each upper electrode 19 and 20 so as not to interfere with
The deflection angle α of the arcs 28 and 29 generated between the raw material 27 and the raw material 27 is increased.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a direct-flow arc furnace for melting raw materials of a cold iron source, which is made of scrap or pig iron as a block.

[0002]

[Prior art]

 Conventionally, for melting a cold iron source with scrap or pig iron as a block, as shown in FIG. 5, a furnace main body 2 having a lower electrode 1 at the bottom and an upper part of the furnace main body 2 are closed. Furnace lid 3, one upper electrode 4 penetrating vertically through the furnace lid 3 so as to be able to move up and down, a lower conductor 5 connected to the lower electrode 1 and extending in the radial direction, and the upper electrode. From the upper conductor 6 connected to the pole 4 and extending in the radial direction, the transformer 8 and the rectifier 9 arranged between the extended ends of the lower conductor 5 and the upper conductor 6 and connected to the AC power supply 7. A DC arc furnace having a power supply circuit 10 is used.

However, the conventional DC arc furnace shown in FIG. 5 has a problem that an arc generated between the upper electrode and the raw material (molten steel) is generated in a deflected direction.

That is, the lower conductor 5 connected to the lower electrode 1 and the upper conductor 6 connected to the upper electrode 4 are provided in the radial direction with respect to the furnace body 2, and the upper conductor 6 is the furnace lid 3 On the other hand, the lower conductor 5 is provided so as to be able to move up and down, but since the lower conductor 5 cannot take a large space in the lower portion of the furnace main body 2, it is provided at a position near the arc 11 generation portion. A strong magnetic force generated by the electric current will act on the arc 11. This magnetic field is generated in the direction of the clockwise arrow A by the right-handed screw law by the current flowing through the lower conductor 5 toward the lower electrode 1.

An electric current flowing upward in the upper electrode 4 crosses the magnetic field. Therefore, from the direction of the electric current (upward) and the direction of the magnetic field (A direction), the arc 11 is generated according to Fleming's left-hand rule. Receives a force F toward the furnace peripheral wall in a direction opposite to the direction in which the lower conductor 5 is extended, and the raw material 12 is less likely to be melted on the side opposite to the deflection direction, and unmelted residue may occur. , Hot spots are generated, the temperature in the furnace becomes non-uniform, the melting efficiency is significantly reduced, and the arc 11 is deflected, so that the arc 11 moves toward the furnace peripheral wall, and the furnace peripheral wall is damaged. Had problems such as.

In order to improve the above-mentioned problems, as shown in FIG. 6, a lower electrode 13 is provided on the bottom portion, a refractory material 14 is provided on the peripheral side portion, and a jacket P made of a steel plate 36 is provided on the outer periphery. A supported furnace body 16, a furnace lid 17 provided so as to close the upper portion of the furnace body 16, and two furnace lids 17 arranged so as to vertically penetrate through the furnace lid 17 with a required gap in the horizontal direction. Upper electrodes 19 and 20, upper conductors 21 and 22 connected to the respective upper electrodes 19 and 20 and extending in directions away from the other upper electrodes, and the upper electrodes 21 and 22 connected to the lower electrode 13 respectively. Two lower conductors 23 and 24 extending in the same direction as the conductors 21 and 22 and the extending ends of the upper and lower conductors 21 and 23 on the one side and the extending ends of the upper and lower conductors 22 and 24 on the other side. DC arc furnace provided with power supply circuits 25 and 26 separately arranged in each Is being considered.

The above DC arc furnace is equipped with two upper electrodes 19 and 20, and the arcs 30 and 31 generated between the electrodes 19 and 20 connected to the respective power circuits 25 and 26 and the raw material 27. By directing it toward the center of the furnace body, it is possible to improve the melting efficiency of the raw material 27, prevent the consumption of the peripheral wall of the furnace, and promote the concentrated melting of unmelted raw material or the elimination of hot spots. This is an improvement over the conventional device shown in FIG.

[0008]

[Problems to be solved by the device]

 However, as explained in Fleming's left-hand rule, the arcs 30 and 31 are bent in the direction F toward the center of the furnace body 16, but the deflection angles of the arcs 30 and 31 are the arcs 30 and 31. It depends on the strength of the magnetic force that acts. On the other hand, in the DC arc furnace shown in FIG. 6, since the jacket P covering the furnace body 16 is formed of the steel plate 36, when a current flows through the lower conductors 23 and 24, as shown in FIG. As described above, the upper part of the magnetic field G generated by the electric current passes through the steel plate 36 forming the casing P of the furnace body 16 and is distorted.

Therefore, the magnetic force acting on the arcs 30 and 31 generated between the upper electrodes 19 and 20 and the raw material 27 is weakened, so that the deflection angle β of the arcs 30 and 31 is small. In addition, the deflection angle β is determined to be a constant small angle. For this reason, the raw material 27 is likely to be left unmelted in the central portion of the bottom of the furnace body 16 and only the outer side is heated, so that the melting efficiency of the raw material 27 in the furnace body 16 by the arcs 30 and 31 can be increased too much. If the interval between the upper electrodes 19 and 20 is narrowed in order to dissolve the raw material 27 in the central portion, the raw material 27 in the peripheral portion is likely to be left unmelted or only the central portion There is a problem in that it is heated to generate hot spots and the dissolution efficiency is reduced.

In view of the above situation, the present invention prevents the magnetic field generated by the lower conductor of the furnace body from being greatly distorted by the outer casing, and increases the deflection angle of the arc to increase the melting efficiency of the raw material of the furnace body. In addition, the lower conductor is formed into a coil shape, the magnetic force generated from the current is strengthened, and the deflection angle of the arc is increased to direct the arc toward the center of the furnace body and It is an object of the present invention to provide a direct current arc furnace in which the melting efficiency is further improved and the deflection angle of the arc can be selected.

[0011]

[Means for Solving the Problems]

 According to a first aspect of the present invention, there is provided a furnace main body in which a bottom lower electrode and a peripheral side refractory material are supported by a casing, a furnace lid provided so as to close an upper portion of the furnace main body, and a required horizontal interval. And two upper electrodes arranged so as to vertically penetrate the furnace lid, an upper conductor connected to each of the upper electrodes and extending in a direction away from the other upper electrode, and the lower electrode. And two lower conductors connected to each other and extending in the same direction as the respective upper conductors, and separately between the extending ends of the upper and lower conductors on one side and the extending ends of the other upper and lower conductors on the other side. A DC arc having a power supply circuit arranged therein, wherein the jacket body of the furnace body is made of a non-magnetic material.

According to a second aspect of the present invention, there is provided a furnace main body in which a lower electrode on the bottom and a refractory material on the peripheral side are supported by an outer casing, a furnace lid provided so as to close an upper portion of the furnace main body, and a furnace required horizontally Two upper electrodes that are arranged so as to vertically penetrate the furnace lid with a space of, and an upper conductor that is connected to each of the upper electrodes and extends in a direction away from the other upper electrode. Two lower conductors connected to the lower electrode and extending in the same direction as the respective upper conductors, and between the extending ends of the upper and lower conductors on one side and between the extending ends of the other upper and lower conductors, respectively. A DC arc having a power supply circuit separately arranged in the coil, the two lower conductors are wound in a coil shape, and a portion close to the bottom surface of the furnace body extends in the direction in which the lower conductors extend. And the magnetic force that allows an electric current to flow from the outside of the furnace body toward the center of the furnace body. This is the one in which the converted portion is formed.

According to a third aspect of the present invention, a partition wall made of a magnetic material is disposed between a portion of the coil-shaped magnetic force strengthening portion that is close to the furnace body and a portion that is remote from the furnace body.

[0014]

[Action]

 In the DC arc furnace according to claim 1, an upper conductor connected to each of the two upper electrodes arranged is extended in a direction away from the other upper electrode, and two electrodes are connected to the lower electrode. And the arcs generated between one upper electrode and the raw material and the arcs generated between the other upper and lower electrodes are connected to the respective lower conductors. Under the influence of the magnetic field created by the current flowing in the furnace, a force is applied in the direction opposite to the direction in which the lower conductor is extended, and a force is applied toward the center of the furnace body. Since the body is made of non-magnetic material, when a current flows through each lower conductor, the magnetic field created by the current is not distorted and weakened by the outer body, but penetrates the outer body. , It is possible to apply a stronger magnetic force to each arc than before. Therefore, it is possible to increase the deflection angle of the arc and direct the arc toward the central portion of the furnace body.

In the DC arc furnace according to claim 2, two lower conductors are wound in a coil shape, and a portion close to the bottom surface of the furnace body extends in the direction in which the lower conductors extend and from outside the furnace body. Since the magnetic force strengthening part is formed so that the current flows toward the center side of the furnace body, the magnetic force generated by the current is greatly strengthened and a strong magnetic force acts on the arc generated between the upper and lower electrodes. Therefore, the arc deflection angle can be increased to direct the arc toward the center of the furnace body, and the strength of the magnetic force can be changed by changing the number of times the lower electrode is wound in the magnetic force strengthening section. The deflection angle of the arc can be selected.

In the DC arc furnace according to the third aspect of the present invention, since electric currents flow in opposite directions in the proximity portion and the separation portion of the magnetic force strengthening portion formed in a coil shape, the directions of the magnetic fields generated from the proximity portion and the separation portion are also opposite. At this time, the influence on the arc of the distant part far from the arc is small with respect to the near part close to the arc, but the magnetic field formed at the distant part may still adversely affect the arc. At that time, if a partition wall made of a magnetic material is placed between the proximity part and the separation part of the magnetic force strengthening part to the furnace body, it is possible to block the magnetic force generated from the separation part and prevent the adverse effect of reducing the arc deflection angle. it can.

[0017]

【Example】

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

1 and 2 show an embodiment of the DC arc furnace according to claim 1, the same parts as those in FIG. 6 are designated by the same reference numerals, and detailed description thereof will be omitted. Only the features of the device will be explained.

A jacket P that surrounds and supports the lower electrode 13 at the bottom of the furnace body 16 and the refractory material 14 at the peripheral side is made of a non-magnetic material 15 such as stainless steel.

Next, the operation of the above embodiment will be described.

In the DC arc furnace of FIG. 1, the upper conductors 21 and 22 connected to the two upper electrodes 19 and 20 respectively arranged are extended in a direction away from the other upper electrodes 19 and 20 and Two lower conductors 23, 24 are connected to the lower electrode 13 and extend in the same direction as the upper conductors 21, 22, respectively, and between the extending ends of one of the upper and lower conductors 21, 23 and the other. Since separate power supply circuits 25 and 26 are respectively arranged between the extending ends of the upper and lower conductors 22 and 24, the arc generated between the upper electrode 19 on one side and the raw material 27. 28 and the arc 29 generated between the other upper electrode 20 and the raw material 27, due to the influence of the magnetic field generated by the currents flowing through the respective lower conductors 23 and 24, as in the case of FIG. , 24 respectively receives the force F in the direction opposite to the extending direction. At the same time, the current flowing vertically upward from the lower electrode 13 through the upper electrodes 19 and 20 is the magnetic field generated by the current of the other upper electrode (in the case of the upper electrode 19, the magnetic field of the upper electrode 20 and the upper electrode 20). In this case, the magnetic field of the upper electrode 19 causes a force in the direction of further increasing the force F, and the arcs 28 and 29 are directed toward the center of the furnace body 16.

At this time, since the outer casing P that supports the lower electrode 13 on the bottom and the refractory material 14 on the peripheral side is formed of the non-magnetic material 15 such as stainless steel, as shown in FIG. Even if the magnetic field G generated by the currents flowing through the partial conductors 23 and 24 contacts the bottom surface of the furnace body 16, the magnetic field G penetrates the jacket P without being distorted by the jacket P due to the property of the non-magnetic body 15. Therefore, the magnetic field G of the contacted portion is applied to the arcs 28 and 29 without being weakened.

Therefore, a stronger magnetic force than before can be applied to the arcs 28, 29 to increase the deflection angle of the arcs 28, 29 from β in FIG. 6 to α in FIG. The raw material 27 supplied to the center of the furnace 16 is effectively melted, and the unmelted residue of the raw material 27 at the bottom center of the furnace body 16 can be prevented from occurring, and more uniform heating can be performed as compared with the conventional case. It is possible to increase the dissolution efficiency.

FIG. 3 shows an embodiment of the DC arc furnace according to claim 2, wherein the two lower conductors 23, 24 are wound around the lower conductors 23, 24 in a coil shape to form a furnace body 16 Each coil of the proximity portion 32 with respect to the bottom surface of the furnace extends in the direction in which the lower conductors 23, 24 are extended, and moreover, from the outside of the furnace body 16 toward the center of the furnace body 16. The magnetic force enhancing portion 34 is formed so that the current flows. Incidentally, reference numeral 33 in the figure denotes a separating portion of the magnetic force strengthening portion 34 on the side separated from the furnace body 16.

The operation of the above embodiment will be described.

In the DC arc furnace of FIG. 3, magnetic force strengthening portions 34 are formed on the two lower conductors 23 and 24, and each magnetic force strengthening portion 34 has a proximity portion 32 with respect to the bottom surface of the furnace body 16. Each of the lower conductors 23 and 24 extends in the extending direction and is wound in a coil shape so that a current flows from the outside of the furnace body 16 toward the center of the furnace body 16. Therefore, a very strong magnetic force can be generated in the proximity portion 32, and thus a strong magnetic force can be applied to the arcs 28, 29 generated between the upper electrodes 19, 20 and the raw material 27.

Therefore, the deflection angle of the arcs 28 and 29 can be increased from β in FIG. 6 to α in FIG. 3 by applying a stronger magnetic force to the arcs 28 and 29 than in the prior art. The raw material 27 supplied to the center of the main body 16 can be effectively melted to prevent the raw material 27 from being left unmelted in the central portion of the bottom of the furnace main body 16 and to be more uniformly melted than in the conventional case. It is possible to increase the dissolution efficiency.

Further, the magnetic force strengthening portion 34 can select the deflection angle α of the arcs 28, 29 by changing the number of times the lower electrodes 23, 24 are wound.

In the above-described embodiment, the deflection angle α can be increased regardless of whether the jacket P is the steel plate 36 or the non-magnetic member 15 such as stainless steel.

Further, in the magnetic force strengthening portion 34, the direction of the electric current is opposite between the proximity portion 32 and the separating portion 33, and the direction of the generated magnetic field is also opposite, so that the magnetic field generated by the separating portion 33 causes the arcs 28, 29 There may be an adverse effect that works to suppress the deflection.

In order to solve this problem, it is preferable to separate the separating portion 33 from the arcs 28 and 29 as much as possible. In the case of FIG. 3, however, the magnetic force strengthening portion 34 has a configuration in which it is coiled in the vertical direction. Since the vertical dimension becomes large, it is also effective to wind the coil horizontally.

FIG. 4 shows an embodiment of the DC arc furnace according to claim 3, wherein the magnetic force strengthening portion 34 having the coil shape shown in FIG. 3 is provided between the proximity portion 32 and the separating portion 33 with respect to the furnace body 16. A partition wall 35 made of a magnetic material (for example, a steel plate) is provided.

In the DC arc furnace of FIG. 4, a partition wall 35 made of a magnetic material is arranged between the magnetic field strengthening portion 34 having a coil shape and the proximity portion 32 and the separation portion 33 with respect to the furnace body 16. The magnetic force generated from the separating portion 33 of the coil-shaped magnetic force strengthening portion 34 can be blocked, and the adverse effects on the arcs 28 and 29 can be reduced.

As a result, the deflection angle α of the arcs 28 and 29 can be increased more stably.

It should be noted that the present invention is not limited to the above-mentioned embodiment, and various shapes of the furnace body can be adopted, and only the position near the lower conductor of the outer casing is made nonmagnetic. It may be configured as a body, it may be arbitrarily placed so that the position between the upper portion of each coil and the coil-shaped magnetic field strengthening portion is in the shortest and most efficient position, and the shape of the partition wall is arbitrarily selected. Needless to say, various modifications can be made without departing from the scope of the present invention.

[0036]

[Effect of device]

 In the DC arc furnace according to claim 1, since two upper electrodes are provided and the lower conductors are extended in the direction away from the other upper electrode, an arc generated between each upper electrode and the raw material is generated. , Under the influence of the magnetic field created by the current flowing through each of the lower conductors, a force is applied in the direction opposite to the direction in which the lower conductors are extended, and each arc receives a force toward the center of the furnace body. However, at this time, since the jacket of the furnace body is made of a non-magnetic material, when the current flows through each lower conductor, even if the magnetic field created by the current contacts the bottom of the furnace body, The magnetic force is not weakened by the property of the non-magnetic material that is not affected by, and a stronger magnetic force than before can be applied to the arc generated between the upper and lower electrodes.

Therefore, by increasing the deflection angle of the arc and directing the arc toward the central part of the furnace body, the unmelted material is prevented from remaining in the central part of the bottom of the furnace body, and the melting efficiency of the material of the furnace body by the arc is increased. Can be improved.

In the DC arc furnace according to claim 2, two lower conductors are wound in a coil shape, and a portion close to the bottom surface of the furnace body extends in a direction in which the lower conductors are extended and from the outside of the furnace body. Since the magnetic force strengthening part is formed so that the current flows toward the center side of the furnace body, when the current flows through each lower conductor, the strong magnetic force corresponding to the number of turns of the magnetic force strengthening part is arced. Therefore, the arc change angle can be increased according to the number of coil turns to prevent the unmelted material from remaining in the center of the bottom of the furnace body and to effectively melt the material to improve melting efficiency. Can be made.

In the DC arc furnace according to claim 3, since the partition wall made of a magnetic material is arranged between the portion close to the furnace body and the portion away from the furnace body of the coil-shaped magnetic force strengthening portion, the coil-shaped magnetic force is increased. It is possible to prevent the adverse effect on the arc by blocking the magnetic force generated from the distant part of the strengthened part, and thus to improve the melting efficiency of the raw material toward the central part of the furnace body more stably.

[Brief description of drawings]

FIG. 1 is a cut front view showing an embodiment of a DC arc furnace of claim 1.

FIG. 2 is a view taken along the line II-II in FIG.

FIG. 3 is a cut front view showing an embodiment of the DC arc furnace of claim 2;

FIG. 4 is a cut front view showing an embodiment of the DC arc furnace of claim 3;

FIG. 5 is a cut front view showing an example of a conventional DC arc furnace.

FIG. 6 is a cut front view showing another example of a conventional DC arc furnace.

7 is a VII-VII direction arrow view of FIG. 6;

[Explanation of symbols]

 13 Lower Electrode 14 Refractory Material 15 Non-Magnetic Material 16 Furnace Main Body 17 Furnace Lid 19 Upper Electrode 20 Upper Electrode 21 Upper Conductor 22 Upper Conductor 23 Lower Conductor 24 Lower Conductor 25 Power Supply Circuit 26 Power Supply Circuit 32 Proximity 33 Separation 34 34 Magnetic Strengthening Section 35 Partition wall P jacket

Claims (3)

[Scope of utility model registration request] 1. A furnace body in which a bottom electrode on the bottom and a refractory material on the peripheral side are supported by an outer casing, a furnace lid provided so as to close the upper part of the furnace body, and a required space in the horizontal direction. And two upper electrodes arranged so as to vertically penetrate the furnace lid, an upper conductor connected to each of the upper electrodes and extending in a direction away from the other upper electrode, and connected to the lower electrode. And the two lower conductors extending in the same direction as the upper conductors, and the two lower conductors are separately arranged between the extending ends of the one upper and lower conductors and between the extending ends of the other upper and lower conductors. A DC arc furnace comprising a power supply circuit, wherein the jacket body of the furnace body is made of a non-magnetic material. 2. A furnace body in which a bottom electrode on the bottom and a refractory material on the peripheral side are supported by an outer casing, a furnace lid provided to close the upper part of the furnace body, and a required space in the horizontal direction. And two upper electrodes arranged so as to vertically penetrate the furnace lid, an upper conductor connected to each of the upper electrodes and extending in a direction away from the other upper electrode, and connected to the lower electrode. And the two lower conductors extending in the same direction as the upper conductors, and the two lower conductors are separately arranged between the extending ends of the one upper and lower conductors and between the extending ends of the other upper and lower conductors. A DC arc having a power supply circuit, wherein the two lower conductors are wound in a coil shape, and a portion close to the bottom surface of the furnace body extends in a direction in which the lower conductors extend and from outside the furnace body. A magnetic field strengthening part was formed so that current could flow toward the center of the furnace body. The DC arc furnace according to claim 1, wherein: 3. The DC arc furnace according to claim 2, wherein a partition wall made of a magnetic material is arranged between a portion close to and away from the furnace body of the coil-shaped magnetic force strengthening portion.