Electrode Sealing Device

Abstract

To provide an electrode seal device having sufficient seal performance while being a simple constitution and, upon the operation of an electric furnace or an LF, capable of suppressing the intrusion of the ambient air from the outside of the furnace to the inside of the furnace.SOLUTION: An electrode seal device seals the surrounding of an electrode of an electric furnace or an LF, and comprises: a nonconductive seal ring; and an inert gas feed source. The seal ring has a ring inner circumferential face and is composed in such a manner that the electrode is arranged at the inside than the ring inner circumferential face. A gap is present between the ring inner circumferential face and the electrode, the inert gas feed source feeds an inert gas to the seal ring, the electrode seal device is composed in such a manner that the inert gas fed from the inert gas feed source to the seal ring is fed from the seal ring to the gap, and the electrode seal device is composed in such a manner that the inert gas fed to the gap is blown from the gap to both the inside of the furnace and the outside of the furnace.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present application discloses an electrode sealing device. [Background technology]

[0002] There are known sealed heating furnaces, such as electric furnaces and LF (Ladle Furnaces), in which electrodes are inserted into electrode insertion holes provided in the furnace cover. Usually, there is a gap around the electrode in the electrode insertion hole, and the inside and outside of the furnace can be connected through the gap. That is, even a sealed heating furnace cannot completely block the intrusion of outside air into the furnace. In order to prevent the intrusion of outside air from the outside into the furnace, it is necessary to seal the periphery of the electrode. As disclosed in Patent Documents 1 to 5, various techniques for sealing the periphery of the electrode are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-022776 [Patent Document 2] Japanese Patent Application Publication No. 6-074654 [Patent Document 3] Japanese Utility Model Publication No. 63-011593 [Patent Document 4] Japanese Patent Application Publication No. 8-136164 [Patent Document 5] Japanese Patent Application Publication No. 9-324988 Summary of the Invention [Problem to be solved by the invention]

[0004] In a closed type heating furnace, the temperature inside the furnace and the temperature of the electrodes inside the furnace tend to be higher than in a non-closed type heating furnace. In such a closed type heating furnace, if outside air enters the furnace through the gap around the electrode during operation, the flow rate of the outside air entering through the gap is high, and the electrode is likely to be worn out due to oxidation directly below the gap around the electrode (directly below the electrode insertion hole). In this regard, it is necessary to properly seal the gap around the electrode, and in conventional electrode sealing devices, a complex configuration is required to ensure high sealing performance. A new electrode sealing device is needed that has a simple configuration but high sealing performance and can suppress the intrusion of outside air from outside the furnace into the furnace during operation of the electric furnace or LF. [Means for solving the problem]

[0005] As one of the means for solving the above problems, the present application provides: An electrode sealing device for sealing around an electrode of an electric furnace or LF having a furnace cover, comprising a non-conductive seal ring and an inert gas supply source; The seal ring has an inner peripheral surface, The seal ring is configured such that the electrode is disposed inside the ring inner circumferential surface, and a gap exists between the ring inner circumferential surface and a surface of the electrode, the inert gas supply source supplies an inert gas to the seal ring; The electrode sealing device is configured such that the inert gas supplied from the inert gas supply source to the seal ring is supplied from the seal ring to the gap, The electrode sealing device is configured so that the inert gas supplied to the gap is blown out from the gap to both the inside and the outside of the furnace. Electrode Sealing Device Disclose.

[0006] In the electrode seal device of the present disclosure, The inner circumferential surface of the ring may face a surface of the electrode, The inner circumferential surface of the ring may be provided with at least one discharge hole for discharging the inert gas.

[0007] In the electrode seal device of the present disclosure, The inner circumferential surface of the ring may face a surface of the electrode, The ring inner circumferential surface may include at least one groove extending along a circumferential direction of the seal ring, The inner circumferential surface of the ring may be provided with at least one discharge hole for discharging the inert gas into the groove.

[0008] In the electrode seal device of the present disclosure, The inner circumferential surface of the ring may face a surface of the electrode, The inner circumferential surface of the ring may include a plurality of discharge holes for discharging the inert gas, The plurality of discharge holes may be arranged along a circumferential direction of the seal ring.

[0009] In the electrode seal device of the present disclosure, The seal ring may include a flow passage for circulating the inert gas in a circumferential direction of the seal ring.

[0010] In the electrode seal device of the present disclosure, The flow path may be formed by an annular metal pipe embedded in the inner circumferential surface of the seal ring, The metal tube may have at least one discharge hole in a wall surface thereof for discharging the inert gas.

[0011] In the electrode seal device of the present disclosure, The gap between the inner circumferential surface of the ring and the surface of the electrode may be 3 mm or less.

[0012] In the electrode seal device of the present disclosure, The seal ring may be placed on the furnace roof of the electric furnace or the LF.

[0013] In the electrode seal device of the present disclosure, The furnace cover may include a barrier portion and a lift-up prevention portion, The horizontal movement of the seal ring may be limited within a range defined by the barrier portion, The vertical movement of the seal ring may be restricted between the upper surface of the furnace cover and the anti-floating portion.

[0014] The electrode sealing device of the present disclosure may be configured so that the inert gas supplied to the gap is blown out from the gap to both the inside and the outside of the furnace at a flow velocity of 1 m / s or more. Effect of the Invention

[0015] The electrode sealing device of the present disclosure has a simple structure but has high sealing performance. According to the present disclosure, the periphery of the electrode in the electric furnace or LF can be sealed, and the intrusion of outside air from the outside of the furnace into the furnace can be suppressed. This makes it possible to suppress, for example, abnormal wear of the electrode directly below the electrode insertion hole. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram showing an example of the configuration of an electrode sealing device, and FIG. 2 is a diagram showing the electrode sealing device as seen from above, with a furnace cover omitted. [Diagram 2] 2 is a diagram showing an example of the configuration of an electrode sealing device, and is a schematic diagram showing the configuration of a cross section taken along the line II-II in FIG. 1. [Diagram 3] 2 is an enlarged view of the structure of an end face in a region X of FIG. [Figure 4] 1 is a diagram showing an example of the configuration of an electrode sealing device, and FIG. 2 is a diagram showing the electrode sealing device as seen from above, with a furnace cover omitted. [Diagram 5] 5 is a diagram showing an example of the configuration of an electrode sealing device, and is a schematic diagram showing the configuration of a cross section taken along the line VV of FIG. 4. [Figure 6] 5 is a diagram showing an outline of the function of the electrode sealing device, and shows an enlarged view of the configuration of the end face in region Y of FIG. [Figure 7] FIG. 1 is a schematic diagram for explaining one of the problems that occurs when outside air enters the furnace from around the electrodes during operation of the heating furnace. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] 1. Basic configuration of electrode seal device As shown in FIGS. 1 to 3, the electrode sealing device 10 of the present disclosure is a device for sealing around an electrode 20 of an electric furnace or LF (heating furnace 100) having a furnace cover 30, and includes a non-conductive seal ring 1 and an inert gas supply source 2. The seal ring 1 has a ring inner circumferential surface 1a. The seal ring 1 is configured so that the electrode 20 is disposed inside the ring inner circumferential surface 1a, and a gap G exists between the ring inner circumferential surface 1a and the surface 20a of the electrode 20. The inert gas supply source 2 supplies an inert gas to the seal ring 1. The electrode sealing device 10 is configured so that the inert gas supplied from the inert gas supply source 2 to the seal ring 1 is supplied from the seal ring 1 to the gap G. The electrode sealing device 10 is also configured so that the inert gas supplied to the gap G is blown out from the gap G to both the inside and outside of the furnace.

[0018] 1.1 Seal ring The seal ring 1 has a ring inner surface 1a. The seal ring 1 may have an upper surface, a lower surface, and a ring outer surface. As described below, the lower surface of the seal ring 1 may be placed on a furnace lid 30. As shown in FIGS. 1 to 3, the ring inner surface 1a may face a surface 20a of an electrode 20, and the ring inner surface 1a may have at least one discharge hole (not shown in FIGS. 1 to 3) for discharging an inert gas.

[0019] The seal ring 1 may have a flow path for circulating the inert gas inside the outer periphery of the ring (for example, inside the seal ring 1 or on the inner periphery of the ring). The flow path may be connected to the above-mentioned discharge hole. The form of the flow path in the seal ring 1 may be any form that can appropriately supply the inert gas to the gap G, and may take various forms depending on the size of the seal ring 1, the positions and number of the discharge holes, the form of connection between the seal ring 1 and the inert gas supply source 2, etc. Specific examples of the flow path will be described later.

[0020] The seal ring 1 is configured so that the electrode 20 is disposed inside the ring inner circumferential surface 1a. In other words, a ring hole is defined by the ring inner circumferential surface 1a, and the electrode 20 can be inserted into the ring hole. The diameter of the ring hole (the inner diameter of the seal ring 1) is larger than the cross-sectional diameter (the electrode diameter) of the electrode 20. That is, a gap G exists between the ring inner circumferential surface 1a and the surface 20a of the electrode 20. The size of the gap G between the ring inner circumferential surface 1a and the surface 20a of the electrode 20 is not particularly limited. However, if the gap G is too large, it may be difficult to blow out the inert gas uniformly both inside and outside the furnace. On the other hand, if the gap G is too small, it may be difficult to insert the electrode 20 into the seal ring 1 or to raise and lower the electrode 20. The gap G may be, for example, 3 mm or less, or 1 mm or more.

[0021] There is no particular limit to the outer diameter (horizontal diameter) or thickness (vertical thickness) of the seal ring 1, and these may be appropriately determined depending on the size of the electric furnace or LF, the size of the electrode 20, the size of the installation space, the installation position, and the like. The seal ring 1 may be made of a non-conductive material, for example, a non-conductive refractory material. As such a refractory material, a known refractory material may be adopted. By making the seal ring 1 of a non-conductive material, it is possible to prevent an arc from jumping between the electrode 20 and the seal ring 1 and causing a ground fault during operation of the furnace.

[0022] The seal ring 1 does not need to be a perfect ring shape as a whole, and may be partially interrupted or may have irregularities or the like. The seal ring 1 may be made up of a single component as a whole, or may be made up of multiple components.

[0023] The installation position of the seal ring 1 in the electric furnace or LF may be any position that allows sealing of the gap around the electrode, for example, around the electrode 20 near the electrode insertion hole of the furnace lid 30. In consideration of ease of installation of the seal ring 1, the seal ring 1 may be placed on the furnace lid 30 of the electric furnace or LF as shown in Figures 1 to 3. Alternatively, the seal ring 1 may be installed under the furnace lid 30 (inside the furnace), although this is less easy to install.

[0024] 1.2 Inert gas supply The inert gas supply source 2 supplies an inert gas to the seal ring 1. The type of inert gas supplied to the seal ring 1 is not particularly limited. Examples include nitrogen and argon. When it is desired to reduce the nitrogen concentration in the furnace (when obtaining molten iron or steel with a low nitrogen concentration, for example), an inert gas other than nitrogen may be used. A specific example of the inert gas supply source 2 is a container filled with high-pressure inert gas.

[0025] The inert gas supply source 2 and the seal ring 1 may be connected, for example, by a pipe 3. The manner in which the inert gas supply source 2 and the seal ring 1 are connected is not particularly limited.

[0026] The pressure of the inert gas supplied to the seal ring 1 is not particularly limited, and may be, for example, atmospheric pressure or higher, or may be 0.10 MPa or higher. The flow rate and flow speed of the inert gas supplied to the seal ring 1 are not particularly limited, and may be appropriately determined depending on the scale of the apparatus, etc., so that the inert gas is blown out from the gap G both inside and outside the furnace.

[0027] The electrode sealing device 10 of the present disclosure is capable of sealing the periphery of the electrode 20 of an electric furnace or LF (heating furnace 100) with a simple configuration by comprising the above-mentioned seal ring 1 and inert gas supply source 2 as basic components. Note that "sealing the periphery of the electrode" in this application means sealing a gap that exists around the electrode in the electrode insertion hole of the furnace lid in an electric furnace or LF having a furnace lid.

[0028] 1.3 Other configurations The electrode sealing device 10 of the present disclosure may include the following additional configurations in addition to the above basic configuration. Figures 4 to 6 show an example of the electrode sealing device 10 including the basic configuration and additional configurations. Although Figures 4 to 6 show a form in which a plurality of additional configurations are adopted to the basic configuration as shown in Figures 1 to 3, in the electrode sealing device 10 of the present disclosure, only some of the additional configurations shown in Figures 4 to 6 may be adopted to the basic configuration as shown in Figures 1 to 3. Furthermore, additional configurations other than the additional configurations as shown in Figures 4 to 6 may be adopted.

[0029] 4 to 6, in the electrode seal device 10, the ring inner peripheral surface 1a may face the surface 20a of the electrode 20, and the ring inner peripheral surface 1a may have at least one groove 1b extending along the circumferential direction of the seal ring 1, and the ring inner peripheral surface 1a may have at least one discharge hole 1cx for discharging the inert gas in the groove 1b. As a result, a space extending in the circumferential direction with a constant size is secured between the ring inner peripheral surface 1a of the seal ring 1 and the surface 20a of the electrode 20, making it easier to spread the inert gas uniformly in the circumferential direction, making it difficult for the pressure of the inert gas to be biased in the circumferential direction, and making it easier for the inert gas to be blown out uniformly from the entire circumference of the gap G between the ring inner peripheral surface 1a of the seal ring 1 and the surface 20a of the electrode 20 to both inside and outside the furnace.

[0030] As shown in Figs. 4 to 6, in the electrode seal device 10, the ring inner circumferential surface 1a may face the surface 20a of the electrode 20, and the ring inner circumferential surface 1a may have a plurality of discharge holes 1cx for discharging the inert gas, and the plurality of discharge holes 1cx may be arranged along the circumferential direction of the seal ring 1. For example, the plurality of discharge holes 1cx may be arranged on a concentric circle centered on the axis (the central axis of the ring hole) of the seal ring 1. This makes it easier to uniformly distribute the inert gas in the circumferential direction between the ring inner circumferential surface 1a of the seal ring 1 and the surface 20a of the electrode 20, making it difficult for the pressure of the inert gas to be biased in the circumferential direction, and making it easier for the inert gas to be blown out uniformly from the entire circumference of the gap G between the ring inner circumferential surface 1a of the seal ring 1 and the surface 20a of the electrode 20 to both inside and outside the furnace. The intervals between the plurality of discharge holes 1cx in the circumferential direction are not particularly limited, and may be, for example, equal intervals. The number of the multiple discharge holes 1cx is not particularly limited, and may be, for example, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, or 8 or more. Only one discharge hole 1cx (one row) may be provided in the vertical direction, or multiple discharge holes 1cx (two or more rows) may be provided.

[0031] As shown in Figs. 4 to 6, in the electrode sealing device 10, the seal ring 1 may have a flow path for circulating the inert gas in the circumferential direction of the seal ring 1. In this case, as shown in Figs. 4 to 6, the flow path may be formed by an annular metal pipe 1c embedded in the ring inner circumferential surface 1a of the seal ring 1, and the annular metal pipe 1c may have at least one discharge hole 1cx for discharging the inert gas in its tube wall surface. Note that "embedded in the ring inner circumferential surface 1a" means that the metal pipe 1c is disposed on the outer circumferential side of the ring (opposite side to the electrode) with respect to the surface of the ring inner circumferential surface 1a that may be closest to the electrode 20. When viewed from the inner circumferential side of the ring, a part of the metal pipe 1c may be exposed without being covered by the ring material, or the entire metal pipe 1c (except for the discharge hole 1cx) may be embedded inside the ring. Alternatively, the flow passage provided in the seal ring 1 may include a first flow passage including an inlet for the inert gas supplied from the inert gas supply source 2, a second flow passage connected to the first flow passage and having an annular shape extending in the circumferential direction of the seal ring 1, and a third flow passage branched from the second flow passage and connected to the discharge hole 1cx. In this way, by providing the flow passage extending in the circumferential direction in the seal ring 1, the inert gas can be easily distributed uniformly in the circumferential direction, and the pressure deviation in the circumferential direction is unlikely to occur, and the inert gas can be easily blown out uniformly from the entire circumference of the gap G between the ring inner surface 1a of the seal ring 1 and the surface 20a of the electrode 20 to both inside and outside the furnace.

[0032] As shown in Figs. 4 and 5, the furnace lid 30 may include a barrier portion 31 and a floating prevention portion 32, and the horizontal movement of the seal ring 1 may be limited within a range defined by the barrier portion 31, and the vertical movement of the seal ring 1 may be limited between the upper surface of the furnace lid 30 and the floating prevention portion 32. In this case, the diameter of the range defined by the barrier portion 31 may be the same as the outer diameter of the seal ring 1, or may be larger than the outer diameter. In particular, when the diameter of the range defined by the barrier portion 31 is larger than the outer diameter of the seal ring 1, the freedom of the horizontal position of the seal ring 1 increases. That is, on the furnace lid 30, the seal ring 1 can freely slide horizontally within the range defined by the barrier portion 31. As a result, for example, even if the position of the electrode 20 is displaced in the horizontal direction due to the elevation or lowering of the electrode 20, the seal ring 1 can follow the displacement of the electrode 20, and damage to the electrode 20 and the seal ring 1 can be easily suppressed. The shape of the barrier portion 31 is not particularly limited, and may have a shape (annular) corresponding to the outer periphery of the seal ring 1, may be a discontinuous arc shape, may be flat, may be rod-shaped, may be an irregular convex shape, or may be any other shape. In addition, the floating prevention portion 32 restricts the vertical movement of the seal ring 1, so that the seal ring 1 is not unnecessarily lifted in the vertical direction when the electrode 20 rises, etc., and the vertical position of the seal ring 1 is easily maintained appropriately. As a result, even if the electrode 20 moves in the horizontal or vertical direction, the electrode seal device 10 can easily seal the periphery of the electrode appropriately. The shape of the floating prevention portion 32 is also not particularly limited, and various shapes can be adopted.

[0033] The electrode sealing device 10 may be configured so that the inert gas supplied to the gap G is blown out from the gap G to both the inside and outside of the furnace at a flow rate of 1 m / s or more. This makes it possible to further suppress the intrusion of outside air from the outside of the furnace into the inside of the furnace around the electrode 20. The flow rate of the inert gas blown out from the gap G can be adjusted by the flow rate, pressure, etc. of the inert gas supplied to the gap G.

[0034] 1.4 Issues with conventional technology In a closed electric furnace having a furnace cover and a normal LF (closed heating furnace), a gap exists around the electrode in the electrode insertion hole of the furnace cover. In a closed heating furnace, the pressure inside the furnace is often reduced to suppress dust generation outside the furnace. In this case, outside air is likely to enter the furnace through the gap. In addition, the temperature inside the furnace and the temperature of the electrodes inside the furnace are likely to become high compared to a non-closed heating furnace. In such a closed heating furnace, when outside air enters the furnace through the gap around the electrode during operation, the flow rate of the outside air entering through the gap is high, and the electrode is likely to be locally worn out due to oxidation directly below the gap around the electrode (directly below the electrode insertion hole). For example, as shown in FIG. 7, the electrode is locally worn out near the gap, causing the electrode to become constricted, and in some cases, the electrode may break. In order to prevent such abnormal wear of the electrode, it is necessary to properly seal the area around the electrode near the gap, but the conventional electrode seal device tends to have a complicated device configuration. Therefore, a new electrode sealing device is needed that has a simple configuration but high sealing performance and can suppress the intrusion of outside air from outside the furnace into the furnace during operation of the electric furnace or LF.

[0035] 1.5 Functions and Effects of the Electrode Seal Device of the Present Disclosure In contrast, the electrode sealing device 10 of the present disclosure, as shown in Figures 3 and 6, supplies an inert gas around the electrode, and the inert gas is blown out from the gap G to both the inside and outside of the furnace, thereby preventing the intrusion of outside air from the outside of the furnace into the inside of the furnace around the electrode, and as a result, prevents the abnormal wear of the electrode described above. In addition, the inert gas is blown onto the surface of the electrode, which is expected to have the effect of cooling the surface of the electrode, and it is believed that this also makes it easier to prevent abnormal wear of the electrode.

[0036] In a closed heating furnace, the intrusion of outside air from around the electrodes is suppressed, and in addition to the effect of suppressing the abnormal wear of the electrodes, the following effects can be expected. That is, the oxygen partial pressure in the furnace can be reduced, improving the reduction efficiency in the furnace. In addition, when carbonaceous material is added to the furnace to react with the molten material in the furnace, loss due to oxidation of the carbonaceous material is reduced. In addition, depending on the type of inert gas supplied, nitrogen pickup of the molten metal in the furnace can be prevented. Furthermore, heat loss due to exhaust gas from the inside of the furnace to the outside of the furnace can also be reduced.

[0037] 2.Heating furnace The technology of the present disclosure also has an aspect of a heating furnace equipped with the above-mentioned electrode sealing device 10. That is, as shown in Figs. 1 to 6, the heating furnace of the present disclosure is a heating furnace 100 which is an electric furnace or an LF, and is equipped with a furnace lid 30, an electrode 20, and an electrode sealing device 10. The furnace lid 30 has an electrode insertion hole, and the electrode 20 is inserted into the electrode insertion hole of the furnace lid 30. The electrode sealing device 10 seals around the electrode 20 in the electrode insertion hole. In the heating furnace 100, the configurations other than the furnace lid 30, the electrode 20, and the electrode sealing device 10 may be the same as those of a conventional heating furnace. The configurations of the heating furnace 100 are as described above, and will not be described here.

[0038] The heating furnace 100 equipped with the furnace cover 30 may have a high temperature inside the furnace during operation. For example, the temperature may be so high that the electrode 20 becomes red hot inside the furnace. For example, the temperature inside the furnace may be 1000°C or higher. Even in such a case, in the heating furnace 100 of the present disclosure, the periphery of the electrode 20 is appropriately sealed, thereby suppressing abnormal wear of the electrode 20 directly below the electrode insertion hole.

[0039] The heating furnace 100 may be depressurized during operation. This can suppress dust generation from the inside of the furnace to the outside of the furnace. The pressure in the furnace during operation may be, for example, less than atmospheric pressure, and may be -30 Pa or less. In the heating furnace 100 of the present disclosure, even if the inside of the furnace is under such a reduced pressure, the area around the electrode 20 is appropriately sealed, so that the intrusion of outside air from around the electrode 20 into the furnace can be suppressed.

[0040] 3. Sealing method around electrodes in electric furnaces or LF The technology disclosed herein also has an aspect of being a method for sealing around an electrode in an electric furnace or LF. That is, the method disclosed herein is a method for sealing around an electrode in an electric furnace or LF having a furnace cover, and is characterized in that an inert gas is supplied to a gap around the electrode in the electric furnace or LF, and the inert gas is blown out from the gap to both the inside and outside of the furnace. The problem-solving mechanism by the method disclosed herein has been described above. EXAMPLES

[0041] The effects of the technology of the present disclosure will be described in more detail below with reference to examples; however, the technology of the present disclosure is not limited to the following examples.

[0042] 1. Example An electrode seal device was placed in a closed type direct current reduction electric furnace to confirm its effectiveness. The electrode diameter was 10 inches (φ254 mm), and a seal ring was placed on the furnace cover and around the electrode to seal the periphery of the electrode. The seal ring had an inner diameter of φ258 mm (gap G: 2 mm), an outer diameter of φ500 mm, and a vertical thickness of 80 mm, and a groove with a vertical width of 20 mm and a depth of 30 mm was provided on the inner surface of the seal ring all around the circumference. In addition, a total of 16 discharge holes with a hole diameter of φ3 mm were provided in the groove along the extension direction of the groove. When the electric furnace was in operation, a total of 1 Nm was discharged from the discharge holes into the groove. 3 The area around the electrode was sealed by supplying inert gas (nitrogen or argon) at a flow rate of 1000 / min and blowing the inert gas at a flow rate of about 5 m / s from the gap G between the inner surface of the seal ring and the surface of the electrode to both the inside and outside of the furnace. During operation, slag reduction using carbonaceous material and melting of iron scrap were carried out while reducing the pressure inside the electric furnace (gauge pressure: -30 Pa).

[0043] 2. Comparative Example Except for not providing an electrode seal device, the electric furnace was operated in the same manner as in the example. It was confirmed that a gap of 30 mm was generated around the electrode in the electrode insertion hole of the furnace cover, and that outside air entered the furnace at a high flow rate from the outside to the inside of the furnace during operation.

[0044] 3.Results In the examples, after the electric furnace was operated, no abnormal wear of the electrode was observed directly below the electrode insertion hole. This is thought to be because the area around the electrode was sealed, preventing outside air from entering the furnace from outside. In addition, the oxygen partial pressure in the furnace was reduced during the operation of the electric furnace, so that the (T.Fe) of the slag could be reduced to 1 mass% or less by slag reduction using carbonaceous material. In addition, when iron scrap was melted using argon as an inert gas, the nitrogen concentration after melting could be kept low. In addition, the thermal efficiency in the furnace was improved by reducing the exhaust gas flow rate.

[0045] On the other hand, in the comparative example, after the electric furnace was operated, the electrode was locally and significantly worn directly below the electrode insertion hole, which was thought to be due to the influence of air oxidation. [Explanation of symbols]

[0046] 10 Electrode sealing device 1 Seal ring 1a Inner surface of ring 1b Groove 1c Circular metal tube (flow path) 1cx discharge hole 2 Inert gas supply source 3 Piping 20 electrodes 20a surface 30 Hearth lid 31 Barrier 32 Floating prevention part 100 Heating furnace (electric furnace or LF with furnace lid)

Claims

1. An electrode sealing device for sealing around an electrode of an electric furnace or LF having a furnace cover, comprising a non-conductive seal ring and an inert gas supply source, The seal ring has an inner peripheral surface, The seal ring is configured such that the electrode is disposed inside the ring inner circumferential surface, and a gap exists between the ring inner circumferential surface and a surface of the electrode, The inner circumferential surface of the ring faces the surface of the electrode, The ring inner peripheral surface includes at least one groove extending along a circumferential direction of the seal ring, the inner circumferential surface of the ring is provided with at least one discharge hole for discharging the inert gas into the groove, the inert gas supply source supplies an inert gas to the seal ring; The electrode sealing device is configured such that the inert gas supplied from the inert gas supply source to the seal ring is supplied from the seal ring to the gap, The electrode seal device is configured so that the inert gas supplied to the gap is uniformly blown out from the gap to both the inside and outside of the furnace at a flow rate of 1 m / s or more. Electrode sealing device.

2. The inner circumferential surface of the ring faces the surface of the electrode, the inner circumferential surface of the ring is provided with a plurality of discharge holes for discharging the inert gas; The plurality of discharge holes are arranged along the circumferential direction of the seal ring. The electrode seal device according to claim 1 .

3. The seal ring includes a flow path for circulating the inert gas in a circumferential direction of the seal ring. The electrode sealing device according to claim 1 or 2.

4. the flow passage is formed by an annular metal pipe embedded in the inner peripheral surface of the seal ring, The metal tube has at least one discharge hole for discharging the inert gas on a wall surface thereof. The electrode seal device according to claim 3 .

5. The gap between the inner peripheral surface of the ring and the surface of the electrode is 3 mm or less. The electrode sealing device according to any one of claims 1 to 4.

6. The seal ring is placed on the furnace cover of the electric furnace or the LF. The electrode sealing device according to any one of claims 1 to 5.

7. The furnace cover includes a barrier portion and a lift-up prevention portion, the horizontal movement of the seal ring is limited within a range defined by the barrier portion; The vertical movement of the seal ring is limited between the upper surface of the furnace cover and the floating prevention part. The electrode sealing device according to claim 6 .

8. A heating furnace which is an electric furnace or an LF, comprising a furnace cover, an electrode, and an electrode sealing device; The furnace cover has an electrode insertion hole, The electrode is inserted into the electrode insertion hole of the furnace cover, The electrode sealing device is an electrode sealing device according to any one of claims 1 to 7, and seals around the electrode in the electrode insertion hole. Heating furnace.

9. The pressure inside the heating furnace is -30 Pa or less. The heating furnace according to claim 8.

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