Molten raw material preheating device and arc melting furnace with preheater

Abstract

To provide a molten raw material preheating device capable of continuing the operation of an arc melting furnace even if a device which preheats molten raw material gets out of order.SOLUTION: A molten raw material preheating device 3 preheats molten raw material with an exhaust gas produced in an arc melting furnace 2 having a furnace cover opening / closing mechanism. The molten raw material preheating device 3 has: a preheating device body 46 which is fixed apart not to overlap with a furnace body upper part of the arc melting furnace 2 in a vertical view; and an exhaust gas introduction duct 47 which connects the arc melting furnace 2 and the preheating device body 46 and introduces an exhaust gas into the preheating device body 46. The preheating device body 46 has: a raw material feed port 56 through which the molten raw material is fed; holding means 61 which holds the molten raw material; an exhaust gas introduction port 67 which is connected to the exhaust gas introduction duct 47; an exhaust gas discharge port 68 through which the exhaust gas used to preheat the molten raw material is discharged; a raw material discharge port 58 which is open downward at a bottom part of the preheating device body 46; and a container 74 which receives the molten raw material discharged from the raw material discharge port 58.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a material preheating device for melting raw materials, such as scrap metal, using exhaust gas from an arc melting furnace, and to an arc melting furnace equipped with a preheating device. [Background technology]

[0002] In an arc melting furnace, an arc is generated between an electrode inserted in the furnace body and the melting material such as scrap metal, and the melting material is melted by the heat of the arc. Since high-temperature exhaust gas is generated from such an arc melting furnace during melting, this high-temperature exhaust gas can be used to preheat the melting material to be melted next.

[0003] In an arc melting furnace equipped with a preheating device used to preheat the melting raw materials, for example as shown in the following Patent Document 1, a cylindrical preheating device main body is provided at the top of the arc melting furnace. This preheating device main body is configured to be movable by a dolly, and when the melting raw materials are preheated, the preheating device main body is located near the furnace wall of the arc melting furnace, and when the preheated melting raw materials are charged into the furnace, the preheating device main body moves toward the center of the arc melting furnace. At this time, a furnace lid opening and closing mechanism is included on the preheating device side so that the preheating device main body and the furnace lid can move together.

[0004] However, in an arc melting furnace with a preheating device configured in this manner, if a malfunction occurs in a part on the preheating device side (for example, a moving cart), the arc melting furnace cannot lift or open / close the furnace cover by itself, and melting operations cannot be continued. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-68594 Summary of the Invention [Problem to be solved by the invention]

[0006] In view of the above circumstances, an object of the present invention is to provide a material preheating device and an arc melting furnace with a preheating device that can continue to operate the arc melting furnace even if a failure occurs in the device for preheating the material to be melted. [Means for solving the problem]

[0007] The first aspect of the present invention is a preheating device for melted raw materials, which is defined as follows: A melting material preheating device that preheats melting materials using exhaust gas generated in an arc melting furnace having a furnace lid opening and closing mechanism, A preheating device body fixedly installed above the furnace body of the arc melting furnace so as not to overlap with the furnace body when viewed from above; an exhaust gas introduction duct that connects the arc melting furnace and the preheating device main body and introduces exhaust gas into the preheating device main body; Equipped with The preheating device body includes: A raw material inlet for injecting the raw material to be melted; A holding means for holding the melting raw material; an exhaust gas inlet connected to the exhaust gas inlet duct; an exhaust gas outlet for discharging exhaust gas used in preheating the melting raw material; a raw material discharge port opening downward at the bottom of the preheating device body; a container for receiving the raw material discharged from the raw material discharge port; has.

[0008] According to the preheating device for molten raw materials of the first aspect thus defined, the preheating device body is fixed and does not move together with the furnace lid, so that it is not necessary to provide a mechanism for opening and closing the furnace lid on the preheating device side. Therefore, as in a normal arc melting furnace not equipped with a preheating device, the furnace lid opening and closing mechanism is provided on the arc melting furnace side. According to the first aspect of the melting raw material preheating device, even if the melting raw material preheating device breaks down, the furnace lid can be opened and closed by the furnace lid opening and closing mechanism provided on the arc melting furnace side, the function of charging the melting raw materials into the furnace is maintained, and the melting operation in the arc melting furnace can be continued.

[0009] Here, the exhaust gas inlet of the preheating device body can be provided below the holding means, and the exhaust gas outlet can be provided above the holding means (second aspect). In this way, the exhaust gas introduced into the preheating device body flows upward from below the holding means, so that when multiple stages of holding means are provided in the preheating device body, the molten raw material held in the lower holding means closer to the raw material discharge outlet (the molten raw material scheduled to be discharged next) can be preheated more efficiently.

[0010] In addition, in the present invention, a bypass duct can be further provided, one end of which is connected to the preheating device body lower than the holding means and which avoids the preheating chamber in the preheating device body in which the melting raw material is stored, and guides the exhaust gas introduced into the preheating device body to an exhaust duct (third aspect). In this way, when the raw material to be melted is not preheated, the exhaust gas can be guided to the exhaust duct via a route that avoids the preheating chamber in the main body of the preheating device.

[0011] It is also possible to connect one end of a bypass duct to the exhaust gas introduction duct, and to guide the exhaust gas generated in the arc melting furnace to the exhaust duct (fourth aspect).

[0012] In addition, in this invention, either one of the end member of the furnace lid side duct and the end member of the preheating device side duct, which are arranged opposite each other, of the exhaust gas introduction duct can be configured to be movable forward and backward relative to the other (fifth aspect). In this way, when exhaust gas is circulated, the gap between the opposing end members can be reduced to prevent the inhalation of outside air. On the other hand, when it is necessary to avoid interference associated with movement, such as when tilting the furnace body, the gap between the end members can be increased to create a separation between the furnace cover side duct and the preheating device side duct.

[0013] The sixth aspect of the present invention provides an arc melting furnace with a preheating device as follows: The present invention is configured to include an arc melting furnace having a rotation device that supports the bottom of the furnace body and rotates the furnace body around an axis in the vertical direction, and a melting material preheating device of the first aspect. According to the arc melting furnace with a preheating device of the sixth aspect thus defined, the preheating device body of the melting material preheating device is fixedly installed separately from the upper part of the furnace body of the arc melting furnace so as not to overlap with it. Therefore, when the furnace body is rotated, it is not necessary to rotate the preheating device body together with the furnace body, and it is possible to avoid an increase in the load on the rotation device caused by the preheating device body. [Brief description of the drawings]

[0014] [Figure 1] 1 is a diagram showing a schematic configuration of an arc melting furnace with a preheating device according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a plan view of the arc melting furnace of FIG. 1. [Diagram 3] FIG. 2 is an enlarged view of the melting material preheating device of FIG. 1. [Figure 4] FIG. 4 is an explanatory diagram of the operation of the arc melting furnace with a preheating device according to the embodiment. [Diagram 5] FIG. 5 is an explanatory diagram of the operation of the arc melting furnace with a preheating device, continuing from FIG. 4. [Figure 6] FIG. 6 is an explanatory diagram of the operation of the arc melting furnace with a preheating device, continuing from FIG. 5. [Figure 7] This is a modified example in which the bypass flow path of the exhaust gas is different. [Figure 8] This is a modified example in which the height of the preheating device body, the location of the scrap bucket, and the arrangement of the fingers within the preheating device body are different. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Next, the melting material preheating device and the arc melting furnace with a preheating device of the present invention will be described in detail with reference to the drawings. Fig. 1 is a diagram showing the schematic configuration of an arc melting furnace with a preheating device according to one embodiment of the present invention. The arc melting furnace with preheating device 1 of this embodiment includes an arc melting furnace 2 and a melting raw material preheating device 3. The arc melting furnace 2 includes a furnace body 7 that contains the melting raw material, a furnace lid 14 that closes the charging port 8 at the upper end of the furnace body 7 in an openable and closable manner, an electrode 17 that passes through the furnace lid 14 and is inserted downward into the furnace body 7, and a rotating device 40. A current such as three-phase AC is applied to the electrode 17 to cause an electric discharge, thereby melting the melting raw material such as metal scrap charged into the furnace body 7.

[0016] The electrodes 17 are disposed inside the furnace body 7 at equal intervals (120° intervals) around the central axis L of the furnace body 7 near the center of the furnace lid 14, which is approximately circular in plan view. Each electrode 17 is supported by a gripper 23 fixed to the tip of an electrode support arm 22 extending horizontally. The electrode support arm 22 is fixedly connected to the upper end of an electrode support column 24 of a furnace lid / electrode lifting and rotating device 21 provided on a platform 33, and each electrode 17 is configured so that its height can be adjusted by an electrode lifting mechanism incorporated in the furnace lid / electrode lifting and rotating device 21.

[0017] The furnace lid 14 is suspended and supported by a furnace lid support arm 27 extending horizontally from the upper end of a ram cylinder 26 of the furnace lid / electrode lifting and rotating device 21. The furnace lid 14 can move up and down and rotate by a furnace lid opening and closing mechanism incorporated in the furnace lid / electrode lifting and rotating device 21, and can open the charging port 8 of the furnace body 7 to charge the melting materials into the furnace body 7.

[0018] The furnace lid 14 is provided with an opening 15 for discharging high-temperature exhaust gas generated during melting upward. The opening 15 is connected to an exhaust gas introduction duct 47 that connects the arc melting furnace 2 and the preheating device main body 46 and introduces the exhaust gas into the preheating device main body 46.

[0019] The furnace body 7 is formed as a cylindrical container with a bottom and an opening at the top, and includes a cylindrical side wall 9 and a furnace bottom 10. A tapping port 11 for tapping molten steel and a slag tapping port 12 for tapping molten residue are provided at opposing positions on the side wall 9 of the furnace body 7 (see FIG. 2).

[0020] The arc melting furnace 2 also includes a rotating device 40 for rotating the furnace body 7 and a tilting body 30 for tilting the furnace body 7 . The tilting body 30 comprises a pair of legs 31, 31, a tilting floor 32 supporting the furnace body 7, and a platform 33. Engagement teeth 35a and 31a are formed on the upper surface of the furnace base 35 supporting the tilting body 30 and on the lower surface of the leg 31 in contact therewith, respectively, and the engagement of these engagement teeth 35a and 31a prevents the tilting body 30 from shifting relative to the furnace base 35 during tilting.

[0021] One end of a drive cylinder (not shown) is connected to the tilting body 30, and the furnace body 7 is configured to tilt together with the tilting body 30 by extending or shortening the drive cylinder. For example, by tilting the entire furnace body 7 so that the side of the steel tapping port 11 faces downward, the molten metal (molten steel) of the melting raw material in the furnace body 7 is tapped from the steel tapping port 11. In addition, by tilting the entire furnace body 7 in the opposite direction to the above-mentioned steel tapping (i.e., so that the side of the slag tapping port 12 faces downward), the slag generated during the melting operation can be discharged to the outside from the slag tapping port 12.

[0022] The furnace body 7 of the arc melting furnace 2 is supported on the tilting bed 32 via a rotation device 40 that rotates the furnace body 7. Specifically, the rotation device 40 has a bearing member 42 fixed on the tilting bed 32, and a support frame 41 supported by the bearing member 42. The support frame 41 is an annular member with a gear body formed on its inner circumferential surface, and the furnace body 7 is fixed on its upper surface.

[0023] A gear body (not shown) is provided inside the support frame 41, which meshes with the gear body on the inner peripheral surface to rotate the support frame 41 around the central axis L. When the gear body rotates, the furnace body 7, which is fixed on the support frame 41 via an insulating plate 43, rotates around the central axis L in the vertical direction. When the furnace body 7 rotates, the position of the electrode 17 does not change. Therefore, the relative arrangement between the furnace body 7 and the electrode 17 changes with the rotation of the furnace body 7. Note that a specific configuration of the rotation device 40 that rotates the furnace body 7 is described in JP 2016-95123 A and the like.

[0024] Next, the melting raw material preheating device 3 will be described. The melting raw material preheating device 3 preheats the metal scrap as the melting raw material by using the high-temperature exhaust gas from the furnace body 7. The melting raw material preheating device 3 is equipped with a rectangular cylindrical preheating device body 46 that constitutes the main body of the device, and an exhaust gas introduction duct 47 that connects the preheating device body 46 to the arc melting furnace 2 and introduces the exhaust gas into the preheating device body 46.

[0025] The exhaust gas introduction duct 47 is composed of a lid-side duct 49 having one end connected to the lid 14, and a preheater-side duct 50 having one end connected to the preheater body 46. As shown in Fig. 2, the connection between the lid-side duct 49 and the preheater-side duct 50 is composed of a flange-shaped end member 49a of the lid-side duct 49 and a flange-shaped end member 50a of the preheater-side duct 50, which are arranged opposite each other.

[0026] Here, the end member 50a of the preheating device side duct 50 is fitted onto the outside of the duct main body 50b so as to be slidable in the axial direction. A cylinder rod 52 that extends or contracts relative to a cylinder tube 51 attached to the duct main body 50b is attached to the end member 50a, and the gap δ between these end members can be adjusted by moving the end member 50a forward or backward relative to the opposing end member 49a. When preheating the metal scrap in the preheating device main body 46, the end member 50a is advanced to be close to the opposing end member 49a. On the other hand, when it is necessary to avoid interference between the furnace cover side duct 49 and the preheating device side duct 50 due to the movement, such as when tilting the furnace body 7, the end member 50a can be retreated (to increase the gap δ) to put it in a disconnected state with the opposing end member 49a. The configuration of the connection between the furnace cover side duct 49 and the preheating device side duct 50 is not limited to this, and can be appropriately changed as necessary as long as one of the end members 49a and 50a can be advanced and retreated relative to the other. For example, the cylinder 51 for advancing and retreating the end member 50a can be attached to a part on the ground side other than the duct main body 50b.

[0027] Next, the preheating device body 46, which constitutes the main part of the melting material preheating device 3, is composed of a square tubular member having a heat-resistant structure. For example, the heat-resistant structure may be a heat-resistant steel or water-cooled pipe (water-cooled panel) structure, and a heat insulating material (refractory material) is applied to the inner or outer surface as necessary. As shown in Fig. 1, the preheating device body 46 is fixed on the foundation beam 55 at a position away from the arc melting furnace 2 so as not to overlap with the upper part of the furnace body of the arc melting furnace 2 when viewed from above.

[0028] Fig. 3 is an enlarged view of the preheating device body 46 of Fig. 1. In the figure, reference numeral 56 denotes a raw material inlet at the upper end of the preheating device body 46, which is opened and closed by a pair of cover plates 57, 57 that are driven to open and close to the left and right by a drive mechanism not shown. Reference numeral 58 denotes a raw material discharge port that opens downward at the bottom of the preheating device body 46 and is opened and closed by a pair of blocking plates 60, 60 that swing about a support shaft 59 by a drive mechanism (not shown). The pair of blocking plates 60, 60 enable the discharge of preheated scrap when open, but maintain a closed state except when the preheated scrap is being discharged, thereby preventing the leakage of introduced exhaust gas and catching any metal scrap S held by the holding means 61 if it falls.

[0029] Numeral 61 denotes a holding means for holding scrap metal S, which is a raw material for melting, and is provided in two stages inside the preheating device body 46. The holding means 61 mainly comprises a pair of freely swinging forks 64, 64, which are made up of a number of heat-resistant steel fingers 63 fixed in parallel at small intervals in the direction perpendicular to the paper surface, on a horizontally extending rotating shaft 62 arranged along the opposing side walls of the preheating device body 46. In the fork 64, the fingers 63 can be swingable together with the rotating shaft 62 by a drive mechanism not shown. The holding means 61 holds the scrap metal S with the fingers 63 in a substantially horizontal position, as shown by the solid line in Fig. 3. When the fingers 63 are tilted downward, as shown by the two-dot chain line in the figure, a scrap drop opening is formed between the tips of the opposing fingers 63. In this example, an upper preheating chamber 65a and a lower preheating chamber 65b are formed in the preheating device body 46 by installing two stages of holding means 61, one above the other.

[0030] An exhaust gas inlet 67 connected to the preheater side duct 50 of the exhaust gas introduction duct 47 is provided on the side wall below the lower preheating chamber 65b of the preheater body 46, and an exhaust gas outlet 68 connected to the exhaust duct 70 is provided on the side wall above the upper preheating chamber 65a of the preheater body 46. The high-temperature exhaust gas introduced into the preheating device body 46 through the exhaust gas inlet 67 flows upward inside the preheating device body 46, heats the metal scrap stored in the preheating chambers 65a and 65b, and is then discharged into the exhaust duct 70. The other end of the exhaust duct 70 is connected to the intake port of a blower for blowing air to a dust collector (not shown).

[0031] Further, a second exhaust gas exhaust port 72 is provided on the side wall below the lower preheating chamber 65b of the preheating device main body 46. One end of a bypass duct 71 is connected to this second exhaust gas exhaust port 72. The other end of the bypass duct 71 is connected to the exhaust duct 70, and the bypass duct 71 forms a bypass flow path that guides the exhaust gas to the exhaust duct 70, avoiding the preheating chambers 65a, 65b in the preheating device main body 46. Dampers 71a and 70a are provided near the second exhaust gas outlet 72 of the bypass duct 71 and near the exhaust gas outlet 68 of the exhaust duct 70, respectively, as switching means operated when switching the exhaust gas flow path. Note that a gate valve may be used as the switching means instead of the damper.

[0032] As shown in FIG. 1, below the raw material discharge port 58, a scrap bucket 74 serving as a container for receiving the metal scrap S discharged from the raw material discharge port 58 is supported on a cart 75. As shown in Figure 1, this scrap bucket 74 has a cylindrical trunk 76 at the top, which is the main body, and an opening / closing door 77 that opens in two at the center on either side at the bottom. Reference numeral 78 denotes a seam at the tip of the opening / closing door 77 on the closing side. The opening / closing door 77 opens and closes in a two-way state at the center. After this scrap bucket 74 contains preheated metal scrap (preheated scrap) inside, it is suspended by a crane wire and moved to above the arc melting furnace 2, and the opening and closing door 77 is opened to load the preheated scrap into the arc melting furnace 2.

[0033] Next, the operation of the preheating arc melting furnace 1 during melting operation will be described. First, the electrode 17 is lifted from the furnace lid 14 and moved to the side, and the furnace lid 14 is then raised and rotated to the side to open the charging port 8 of the furnace body 7 (see FIG. 4). Then, scrap metal (not preheated scrap metal) is charged into the furnace by a scrap bucket 80 suspended by a crane wire and moved to above the arc melting furnace 2.

[0034] 5, the furnace cover 14 is returned to its original position on the arc melting furnace 2, and the electrodes 17 are inserted into the furnace. Meanwhile, in the preheating device main body 46, scrap metal is charged from the raw material charging port 56 by the scrap bucket 80 that is suspended by the crane wire and moved onto the preheating device main body 46, and the scrap metal S is stored in each of the preheating chambers 65a, 65b. The scrap bucket for charging the metal scrap into the arc melting furnace 2 and the scrap bucket for charging the metal scrap into the preheating device main body 46 may be different scrap buckets.

[0035] Electricity is then applied to the electrodes 17 to heat and melt the metal scrap in the furnace. The exhaust gas generated at this time rises inside the furnace and is introduced into the preheating device body 46 through the opening 15 in the furnace lid 14 and the exhaust gas introduction duct 47 as shown by the arrow in Fig. 5. The exhaust gas passes through the gaps between the fingers 63 of the holding means 61 provided in the lower stage to heat the metal scrap S in the lower preheating chamber 65b, and then passes through the gaps between the fingers 63 of the holding means 61 provided in the upper stage to heat the metal scrap S in the upper preheating chamber 65a. The exhaust gas after heating the metal scrap S is discharged through the exhaust duct 70.

[0036] Then, after the volume of the unmelted raw metal material in the furnace is reduced by melting the scrap metal initially charged in the furnace, scrap metal preheated in the preheating device main body 46 is additionally charged (additional charge). Specifically, as shown in FIG. 6, the fingers 63 and the blocking plate 60 constituting the lower-stage holding means 61 are opened as shown by the two-dot chain line, and the preheated scrap metal S is dropped into the scrap bucket 74. On the other hand, on the arc melting furnace 2 side, the electrode 17 is lifted from the furnace lid 14 and moved to the side, and the furnace lid 14 is lifted upward and then rotated to the side to open the charging port 8 of the furnace body 7. Next, the scrap bucket 74 containing the preheated metal scrap (preheated scrap) is carried over to above the furnace body 7, and the preheated scrap is charged into the furnace. It should be noted that by placing materials incompatible with the preheating device (materials that are not suitable for melting in the preheating device) in the scrap bucket 74 beforehand, or by stacking the materials incompatible with the preheating device on top of the preheated scrap after it has been discharged into the scrap bucket 74, it becomes possible to charge the materials incompatible with the preheating device and the preheated scrap in one go.

[0037] After the recharging, the furnace cover 14 is returned to its original position on the arc melting furnace 1, the electrodes 17 are inserted into the furnace, and heating and melting are resumed. When the scrap metal is melted, three hot spots (close to the electrodes) and three cold spots (distant from the electrodes) are generated around the circumference of the furnace body 7, causing the scrap metal to melt unevenly, so in this example, the furnace body 7 is rotated around the vertical axis L (see FIG. 1) with the furnace lid 14 separated upward, to switch the positions of the hot spots and cold spots. In this way, the scrap metal can be melted more uniformly.

[0038] After a melting period in which the scrap metal charged in the furnace body 7 is melted to produce molten steel, and a heating period in which the temperature of the produced molten steel is increased and its composition is adjusted, the furnace body 7 is tilted to tap the molten steel. After the tapping is completed, the furnace body 7 is tilted back to its original position, and the series of operations is completed.

[0039] Although an example of additional charging using preheated scrap preheated in the preheating device main body 46 has been described above, if the melting material preheating device 3 breaks down, melting operation can be continued by charging normal metal scrap that has not been preheated into the furnace as additional melting material using a scrap bucket 80 as shown in Fig. 4. If preheating cannot be performed due to a breakdown in the melting material preheating device 3, the exhaust gas flow path switching dampers 70a, 71a disposed in the duct can be operated to switch the exhaust gas flow path to a bypass path that does not pass through the preheating chambers 65a, 65b.

[0040] According to the molten raw material preheating device 3 of this embodiment configured as described above, the preheating device body 46 is fixed and does not move integrally with the furnace lid 14, so there is no need to provide a furnace lid opening and closing mechanism on the preheating device side. Therefore, like a normal arc melting furnace not equipped with a preheating device, the furnace lid opening and closing mechanism is provided on the arc melting furnace 2 side. In other words, the molten raw material preheating device 3 of this embodiment can be retrofitted to a normal arc melting furnace not equipped with a preheating device. According to this melting raw material preheating device 3, even if the melting raw material preheating device 3 breaks down, the furnace lid 14 can be opened and closed by the furnace lid opening and closing mechanism provided on the arc melting furnace 2 side, the function of charging the melting raw materials into the furnace is maintained, and the melting operation in the arc melting furnace 2 can be continued.

[0041] In the melting raw material preheating device 3 of this embodiment, the exhaust gas inlet 67 of the preheating device body 46 is provided below the holding means 61, and the exhaust gas outlet 68 is provided above the holding means 61. Since the exhaust gas introduced into the preheating device body 46 flows upward from below the holding means 61, when multiple stages of holding means 61 are provided in the preheating device body 46, the metal scrap held in the lower holding means 61 close to the raw material outlet 58 (the metal scrap scheduled to be discharged next) can be preheated more efficiently.

[0042] In addition, in the preheating device 3 for melting raw materials in this embodiment, a bypass duct 71 is further provided, one end of which is connected lower than the holding means 61 of the preheating device main body 46 and which guides the exhaust gas introduced into the preheating device main body 46 to the exhaust duct 70, avoiding the preheating chambers 65a, 65b in the preheating device main body 46 in which the metal scrap is stored. When the raw materials for melting are not preheated, the exhaust gas can be guided to the exhaust duct 70 via a route that avoids the preheating chambers 65a, 65b in the preheating device main body 46.

[0043] In the preheating device 3 for molten raw materials of this embodiment, the end member 50a of the preheating device side duct 50 of the exhaust gas introduction duct 47 is configured to be movable toward and away from the end member 49a of the opposing furnace lid side duct 49. Therefore, when exhaust gas is circulated, the gap δ between the opposing end members can be made small to suppress the intake of outside air, while when it is necessary to avoid interference due to movement, such as when tilting the furnace body 7, the gap δ between the end members can be made large to separate the furnace lid side duct 49 and the preheating device side duct 50.

[0044] The arc melting furnace with preheating device 1 of this embodiment is configured to include an arc melting furnace 2 equipped with a rotation device 40 that supports the furnace bottom 10 of the furnace body 7 and rotates the furnace body 7 around an axis L in the vertical direction, and a melting material preheating device 3. According to this arc melting furnace with preheating device 1, the preheating device body 46 of the melting material preheating device 3 is fixedly installed away from the upper part of the furnace body of the arc melting furnace 2 so as not to overlap with it. Therefore, when the furnace body 7 is rotated, it is not necessary to rotate the preheating device body 46 together, and it is possible to avoid an increase in the load on the rotation device 40 caused by the preheating device body 46.

[0045] Although the embodiment of the present invention has been described in detail above, this is merely an example, and the present invention can be configured in various modified forms without departing from the spirit of the present invention. (1) For example, in the above embodiment, two preheating chambers are provided in the preheating device body, but the number of preheating chambers provided in the preheating device body may be one or three or more. (2) In the above embodiment, the raw material preheating device is combined with an arc melting furnace equipped with a rotating device. However, the raw material preheating device of the present invention can also be combined with an arc melting furnace not equipped with a rotating device. (3) In the above embodiment, a scrap bucket is used as a container for receiving the raw materials for melting discharged from the raw material discharge port. However, it is also possible to configure the furnace to charge preheated scrap into a container other than a scrap bucket. In the above embodiment, non-preheated scrap metal is initially charged into the furnace. However, when a series of melting operations (charging raw materials, melting, and tapping) are performed continuously, it is possible to initially charge preheated scrap metal into the furnace.

[0046] (4) In the above embodiment, one end of the bypass duct 71 is connected to the second exhaust gas outlet 72 provided on the side wall of the preheating device main body 46, but in some cases, as shown in Fig. 7, it is also possible to provide a bypass duct 71 to directly connect the upstream exhaust gas introduction duct 47 and the downstream exhaust duct 70 so as to prevent exhaust gas from entering the preheating device main body 46. Note that, although 47b, 70b, and 71b in the figure are dampers serving as exhaust gas flow path switching means, they may be changed to gate valves.

[0047] (5) In the above embodiment (FIGS. 1 and 3), the longitudinal direction of the fingers 63 is arranged on the paper, but it is also possible to arrange the longitudinal direction of the fingers 63 in the depth direction of the paper. In this case, as shown in the example of FIG. 8, the fingers 63 are arranged rotated by approximately 90 degrees, and many fingers 63 are arranged side by side at small intervals on the paper. (6) In the above embodiment, the charging inlet 8 at the top of the furnace body 7 and the material discharge port 58 opening downward at the bottom of the preheating device main body 46 are at approximately the same height when viewed from above, but as shown in the example of Figure 8, it is also possible to install the molten material preheating device 3 so that the material discharge port 58 is lower than the charging inlet 8 when viewed from above. This allows the height of the preheating device to be lowered, making it less susceptible to restrictions on the building height. (7) In the above embodiment, the cart 75 supporting the scrap bucket 74 is installed on a fixed bed. However, as shown in the example of FIG. 8, it is also possible to dig a pit in the fixed bed and install the scrap bucket 74 and the cart 75 in the pit. (8) In the above embodiment, a pair of cover plates 57, 57 is provided on the raw material inlet 56, but this may be changed to a single cover. In this case, the exhaust gas outlet 68 may be provided on the single cover. (9) In the above embodiment, the scrap metal is charged from the raw material charging port 56 using the scrap bucket 80. However, the scrap metal may be charged using a conveyor. [Explanation of symbols]

[0048] 1 Arc melting furnace with preheating device 2. Arc melting furnace 3. Melting material preheating device 7 Furnace body 10 Hearth bottom 21 Furnace lid / electrode lifting and rotating device (furnace lid opening and closing mechanism) 40 Rotating Device 46 Preheating device body 47 Exhaust gas introduction duct 49 Furnace cover side duct 49a End member 50 Preheater side duct 50a End member 56 Raw material input port 58 Raw material discharge port 61 Holding means 65a Upper preheating chamber 65b Lower preheating chamber 67 Exhaust gas inlet 68 Exhaust gas outlet 70 Exhaust Duct 71 Bypass Duct 74 Scrap bucket (container) S Metal scrap (melting material)

Claims

1. A melting material preheating device that preheats melting materials using exhaust gas generated in an arc melting furnace having a furnace lid opening and closing mechanism, A preheating device body fixedly installed above the furnace body of the arc melting furnace so as not to overlap with the furnace body when viewed from above; an exhaust gas introduction duct that connects the arc melting furnace and the preheating device main body and introduces exhaust gas into the preheating device main body; Equipped with The preheating device body includes: A raw material inlet for injecting the raw material to be melted; A holding means for holding the melting raw material; an exhaust gas inlet connected to the exhaust gas inlet duct; an exhaust gas outlet for discharging exhaust gas used in preheating the melting raw material; a raw material discharge port opening downward at the bottom of the preheating device body; a container for receiving the raw material discharged from the raw material discharge port; A melting raw material preheating device having the above structure.

2. 2. The melting material preheating device according to claim 1, wherein the exhaust gas inlet is provided below the holding means, and the exhaust gas outlet is provided above the holding means.

3. 3. The melting raw material preheating device according to claim 2, further comprising a bypass duct, one end of which is connected to the preheating device body lower than the holding means and which avoids a preheating chamber in the preheating device body in which the melting raw material is stored, and which guides exhaust gas introduced into the preheating device body to an exhaust duct.

4. 3. The melting material preheating device according to claim 2, further comprising a bypass duct, one end of which is connected to the exhaust gas introduction duct and which guides the exhaust gas generated in the arc melting furnace to an exhaust duct, bypassing a preheating chamber in the preheating device body in which the melting material is stored.

5. 2. The melting material preheating device according to claim 1, wherein the exhaust gas introduction duct is configured such that either one of the end members of the furnace lid side duct and the end member of the preheating device side duct, which are arranged opposite each other, can advance and retreat relative to the other.

6. 13. An arc melting furnace with a preheating device, comprising: an arc melting furnace having a rotation device for supporting a furnace bottom portion of the furnace body and rotating the furnace body about an axis in a vertical direction; and the melting material preheating device according to claim 1.

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