Title of Invention	ELECTRIC ARC FURNACE
Abstract	1. Electric arc furnace 2.1 The invention is directed to an electric arc furnace having a lower furnace vessel, an upper furnace vessel, and a furnace roof (2) which receives the electrodes and by which the upper furnace vessel can be closed, and a frame (3) which is movable horizontally on rails (6) and on which the furnace vessel is arranged. 2.2 According to the invention, the furnace roof (2) with the associated system components and the electrode support arm system (5) are arranged in a stationary manner, the entire furnace vessel comprising the lower furnace vessel and the upper furnace vessel is arranged on the frame (3) and is movable along with the latter out of the position below the furnace roof (2), wherein the railway (6) for the frame (3) is constructed in such a way that during the movement along the railway (6) the furnace executes inclinations which initially bring it into an inclination on the deslagging side and, as the movement continues, through a horizontal position into an inclination on the tapping side, wherein the central axis of inclination or center axis of the frame only moves horizontally during the relative movement relative to the furnace roof.

Title of Invention

ELECTRIC ARC FURNACE

Abstract

1. Electric arc furnace 2.1 The invention is directed to an electric arc furnace having a lower furnace vessel, an upper furnace vessel, and a furnace roof (2) which receives the electrodes and by which the upper furnace vessel can be closed, and a frame (3) which is movable horizontally on rails (6) and on which the furnace vessel is arranged. 2.2 According to the invention, the furnace roof (2) with the associated system components and the electrode support arm system (5) are arranged in a stationary manner, the entire furnace vessel comprising the lower furnace vessel and the upper furnace vessel is arranged on the frame (3) and is movable along with the latter out of the position below the furnace roof (2), wherein the railway (6) for the frame (3) is constructed in such a way that during the movement along the railway (6) the furnace executes inclinations which initially bring it into an inclination on the deslagging side and, as the movement continues, through a horizontal position into an inclination on the tapping side, wherein the central axis of inclination or center axis of the frame only moves horizontally during the relative movement relative to the furnace roof.

Full Text	ELECTRIC ARC FURNACE The invention is directed to an electric arc furnace with a lower furnace vessel, an upper furnace vessel, and a furnace roof which receives the electrodes and by which the upper furnace vessel can be closed, and a frame which is movable horizontally on rails and on which the furnace vessel is arranged. Both tiltable and non-tilting electric arc furnaces are known. EP 0 049 926, for example, discloses a tiltable arc furnace whose furnace vessel is movable horizontally out of the position below the furnace roof after the furnace roof with the electrodes is raised. The electric arc furnace according to WO 03/029499 is likewise tiltable, but can also remain stationary. In this furnace, the tapping channel is provided in a separately built-on bay which is removably fitted to the terminating wall of the furnace vessel which is round itself. For tapping, the furnace vessel is tilted so that the liquid metal enters the tapping channel in the bay. In the non-tiltable variant, a pressure is built up in the bay so that the metal is initially kept away from the tap and then - when the tap is opened - immediately flows in. The lower furnace vessel has a bottom taphole at its lowest point through which the furnace can be completely emptied when required. A metallurgical vessel with a tapping device based on the principle of a waterlock or siphon is known from DE 199 19 378 Al, By virtue of this design, the vessel also need not be tilted for tapping. In electric arc furnaces, it is necessary to remove the furnace roof for charging so that the interior of the furnace can be filled by means of a scrap basket. For this purpose, in the electric arc furnace according to EP 0 049 926, the electrodes are first moved out of the furnace by raising them so that the roof of the furnace can be lifted subsequently and swung to the side. Corresponding lifting and swiveling arrangements are necessary for this purpose. The known tiltable or non-tiltable furnace constructions, including the accompanying units, are expensive and costly to operate and maintain. It is the object of the invention to provide an electric arc furnace which is not tiltable on the one hand and in which, on the other hand, the furnace roof need not be swung out and lifted and the electrodes need not be swung out. This object is met by the features of patent claim 1. Advantageous embodiments are indicated in the subclaims. The essential difference in the electric arc furnace according to the invention is that tilting of the furnace for purposes of deslagging and tapping the molten steel is dispensed with. Instead of a furnace tilting system, a furnace moving system is now used, and the furnace roof need no longer be lifted or swiveled. As was mentioned above, the furnace tilting system is dispensed with in its entirety. Specifically, this furnace tilting system comprises the following components: • tilting cylinder, including valve block • tilting lock, including tilting lock cylinder • emergency tilting valve • control, limit switch, tilt angle sensor • Approximately 3 metric tons of welded steel plate construction. The currently conventional tilting frame supporting the furnace vessel system is changed to a translationally horizontally movable frame similar to a ladle transfer car. This frame is symmetrical and has two axles. In contrast to the tilting frame (tilting platform), this frame dispenses with heavy tilting cradles and also, because it eliminates the roof swiveling movement, does away with the complicated added-on construction which until now served to receive the large rolling bearings which were required for that purpose. The resulting savings on material amounts to approximately 35 to 40 metric tons depending on the furnace size, representing heavy, labor-intensive welded steel plate construction. These savings extend further to the mechanical machining, e.g., for the bearing seat or the contour of the cradle, which is also expensive. The platform construction covering this frame is now symmetrical and is likewise appreciably smaller and completely does away with supporting framing. The rolling paths (with costly rolling path teeth, approximately 101 of expensive steel slab) which were formerly required are replaced by about 25 m of contoured railway. These rails comprise cast members (ADI, globular graphite iron). The process taking place when moving the frame will be described below with reference to the drawing. The frame is driven, for example, by two stationary electric-motor drives on the tapping side (similar to a crane hoist). Each drive acts on a cable drum with a roll-off steel cable end and a roll-up steel cable end, depending on the movement direction. The cable ends are connected on both sides of the vessel frame to the center axle. Only one deflection roller, by which the cable can also be pretensioned if need be, is located on the deslagging side. Depending on the rotation direction of the drives, the frame is pulled in one direction or the other without the cable fastening points being moved vertically. This reduces the lifting work of the moving masses to a minimum. In principle, this technique does not require any changes to the conventional, proven upper vessel system (lower vessel and upper vessel, tapping system, furnace door). Basically, there is no change in the upper vessel and lower vessel. Only the contour of the furnace bottom, i.e., the ascending angle of the bottom in the tapping area, need be adapted, if necessary, to the required angle of inclination that can be realized. At the same time, the solution according to the invention affords the possibility of dispensing with the swinging out of the furnace roof system, e.g., for purposes of charging the furnace vessel, and, therefore, at the same time dispensing with the swiveling out of the electrode support arm system. Therefore, the swivel gantry system, including the roof supporting structure arms, is entirely done away with. This accounts for an additional 35 to 40 tons of heavy, mechanically machined welded steel plate construction. The electrode column guide frame, formerly part of the swivel gantry, is now cast from reinforced concrete and is part of the furnace foundation or transformer vault. This also does away with the need for water cooling of the above-mentioned structural component parts. The swivel system and swivel drive are dispensed with without substitution. Further, the elbow on the afterburning chamber side can now be designed so as to be stationary because there is no swiveling movement of the furnace roof to consider. Because of the contour of the railway, the furnace vessel system is removed from the furnace roof automatically when moving in direction of the tapping position and is automatically moved toward the furnace roof when moving in direction of the operating position. Therefore, not only is there no longer a need for a furnace roof lifting mechanism (including the roof lifting cylinder), but there is also no longer a need to place the latter in the immediate vicinity of current-conducting parts, which always caused problems with creeping currents (induction) and arcing (St. Elmo's fire). Dispensing with the water cooling, insulation, and equipotential bonding in this area results in additional savings. The spoke frame of the furnace roof is changed only with respect to the arrangement of the spokes, but otherwise basically remains more or less unchanged. Since the furnace roof need no longer be raised, the three receptacles for the roof lifting mechanism are completely eliminated. Instead, four of six spokes are lengthened outward parallel to the transverse axis of the furnace. These elongations are supported on the left-hand side and right-hand side on expansions of the guide frame foundation and on separate foundations on both sides of the afterburning chamber. The furnace roof can be accessed directly via steps which are cast integral with the guide frame foundation. The roof platform is installed directly on the roof in the form of grating elements. This is appreciably more convenient than the steep ladder steps which were used formerly and which are now likewise dispensed with. Also, water cooling can be omitted in this area. The alloying connection piece is arranged on the slag door side of the exhaust elbow so that the entire alloying system can also be arranged in a stationary manner. This leads to substantial savings. The connection to the cooling water network is carried out on the transformer vault side. Four simple compensators are now used instead of two expensive swivel joints. Long hose connections with large nominal widths coming from the transformer vault wall are entirely dispensed with. The above-mentioned innovations and changes lead to appreciable savings in the sphere of servicing and maintenance. The tie rods which carried the electrode guide columns are dispensed with because they are now arranged in an expansion of the hydraulic chamber below the furnace platform on fixedly anchored bearing blocks. This means that the regulating cylinders are no longer freely suspended, but rather are protected and maintenance-friendly. Long hose lines are dispensed with because a swiveling movement need no longer be taken into account. The transformer vault and furnace foundation are more integrated. The load distribution in the foundation is appreciably more favorable because the furnace load is now introduced via four wheels instead of only two cradle standing points. Below the furnace platform, the hydraulic chamber extends to the furnace foundation. This also creates additional space for more chambers, e.g., for the climate control system, and the like. On the whole, conditions below the furnace platform are substantially simplified. Because of the boundary conditions that are created in this way, a doghouse of a furnace enclosure can be implemented in a simpler maimer. The design of the cooling water supply is substantially more favorable in terms of acquisition and particularly with regard to engineering resources. There are fewer water-cooled structural component parts. This also results in savings on maintenance. There are no longer any exposed pipelines below the furnace platform. All pipelines, particularly the larger nominal widths, can be accessed by the crane. Hose lines which formerly made it possible to tilt the arc furnace are dispensed with. Instead, the hoses supporting the translational movement of the furnace are guided via the energy chain and are positioned on the furnace platform so as to be easily accessible. The DN300 hoses to the furnace roof with a length of 13 m are dispensed with because the roof is now stationary. Instead, there are two or four simple DN300 compensators. Swivel joints are also no longer used. The quantity of hoses for coolant water, hydraulic oil, compressed air, and so on, is appreciably reduced because there are no longer any tilting, lifting or swiveling movements. This substantially eases the piping situation at the transformer vault wall as well as the space conditions on the furnace platform in the area of the transformer vault. All of the other media such as coal, oxygen, nitrogen, argon, etc. can likewise be supplied via the energy chain. A movable bay maintenance platform is done away with in its entirety, i.e., no costly electric-motor chain drive and no movable parts are required in this area. The bay maintenance platform is now part of the furnace foundation (the furnace platform) and spans the ladle pit in the manner of a bridge. This bridge is accessible from two sides and can be constructed appreciably wider than the previous maintenance platform, which offers distinct advantages with respect to taphole upkeep. This maintenance bridge is accessed via descents from the furnace platform. This affords additional advantages with respect to changing the taphole. Nozzle brick breakout devices (hydraulic, pneumatic or mechanical) which are frequently demanded by customers can easily be mounted on this maintenance bridge. The electrode settling state and electrode jointing state remain unchanged. The electrode resetting device is now integrated in the furnace roof or is fitted to the roof-center supporting ring. A circular rail (a square) is added to the upper side of the latter for this purpose. The resetting device comprises three supports which are oriented in a star-shaped manner relative to one another. While this "star" is joined at its origin, rollers moving on the rails mentioned in the beginning are located at the three outer ends. This rotatable base frame is protected from the radiation of the hot electrodes by solid refractory covers. Further, each of these arms carries a centrally spring-cushioned refractory monoblock of the same diameter as the electrodes. This arrangement is positioned at a phase offset of 60° relative to the electrodes and can be rotated by these same 60° by means of a pneumatic drive. Accordingly, the apertures in the roof center can be electively opened or closed. To reset the electrodes, these electrodes are initially moved into their highest position, the resetting device is then rotated by 60° and the roof center openings are closed. The electrodes are then successively moved down until they contact the monoblocks, the electrodes are detached, the electrode support arms are raised corresponding to the respective resetting length, the electrodes are reattached and then moved into their highest position again. Contact with the monoblocks can be monitored by means of the hydraulics (pressure monitoring and/or flow monitoring) so that the regulating cylinders are stopped before the entire weight of the electrode support arms and guide columns comes to rest on the resetting device or the springs of the monoblocks are fully compressed. The high-current cables need no longer compensate for swiveling and tilting movements and are accordingly no longer twisted (80° - 90°) and can be shorter than before. This means that the life of the cables is substantially prolonged. Accordingly, the cables are basically improved. For the reasons stated above, the costs of repair and overhaul are also reduced. The reactance can also be lowered because of shorter cable lengths. This translates to a higher input of energy in the furnace, reduced circuit feedback, and longer arcs. Further, there is appreciably less breakage of and damage to the electrodes because of the omitted movements. Due also to the absence of swiveling movement, the cost of laying pipe and hose to the transformer vault wall is substantially lower and savings on engineering and purchasing are ensured. Due to fewer pipes at the transformer vault wall, a maintenance platform such as is frequently requested by customers is easier to implement. The time sequences of the novel concept and the conventional concept are described for purposes of comparison. Novel furnace concept 1. Power on 2. Power off 3. The furnace movement is started. The furnace supporting frame is inclined for deslagging (-5°). At the same time, the furnace vessel moves away from the furnace roof. 4. At the conclusion of the deslagging process, the furnace is inclined for tapping (+5°). 5. Tapping is initiated. During tapping, the first scrap basket is prepared for charging above the open furnace. 6. The tapping is stopped by rapidly moving the furnace frame back so that the vessel automatically inclines by -10° (in -5° position). 7. The taphole is trimmed, the stopper is closed, and the tapping channel is filled. 8. The first scrap basket is set. 9. The furnace is moved back. 10. Power on 11. Power off 12. The furnace vessel is moved for setting the second scrap basket which has been prepared in the meantime. 13. The second scrap basket is set. 14. The furnace is moved back. 15. Power on. Conventional furnace concept 1. Power on 2. Power off 3. The furnace is tilted by three degrees. 4. Tapping is initiated. 5. The tapping is stopped by rapidly tilting back. 6. The taphole is trimmed, the stopper is closed and the tapping channel is filled. 7. The furnace is tilted into horizontal position. 8. The furnace roof is swung out. 9. The first scrap basket is positioned over the open vessel. 10. The first scrap basket is set. 11. The empty scrap basket is removed. 12. The furnace roof is swung in. 13. Power on 14. Power off 15. The furnace roof is swung out. 16. The second scrap basket is positioned over the open vessel. 17. The second scrap basket is set. 18. The empty scrap basket is removed. 19. The furnace roof is swung in. 20. Power Although the movement speed of the furnace vessel is not mentioned in this juxtaposition, it is immediately clear that a whole range of partial processes can take place in parallel in the novel concept. This is particularly clear with regard to the setting of the scrap baskets. When the speeds of ladle transfer cars of this order of magnitude, which surely move at 0.4 m per second, i.e., opening of the furnace (approximately 9 m) can be accomplished in under 25 seconds, are compared to the angular speeds for swiveling the roof on the same order of magnitude, it is clear that an arc can be operated more efficiently with the novel concept, i.e., a reduction in tap-to-tap time is possible. A mirror-symmetrical arrangement of the vessel system (including movable frame, independently supplied with media such as cooling water) is conceivable. While melting takes place in one system, tapping can take place in the other system, its tap can be serviced, and its first full scrap basket set. Accordingly, parallel operation of the mirror-symmetrical furnace system is possible. If one of the vessels must be closed again, this parallel operation can be interrupted without having a negative effect on the operation of the other vessel system. Accordingly, a time-consuming vessel changing process (vessel exchanging technique) can be dispensed with to the benefit of longer power-on times. The deslagging zone is large enough so that a vehicle for carrying away or clearing the slag can easily access the slag pit by both sides of the afterburning chamber. Both vessel systems, or their movable supporting frames, could be provided with a bridge-like expansion in the area of the slag door which, for example, has a temperature lance and sampling lance and facilitates maintenance work. In view of the additional enormous potential savings, this variant is a useful addition to the overall concept. The variant described above also makes it possible to use "CONARC covers" (oxygen blowing) next to the respective tapping position. Costly swiveling drives can also be dispensed with in this connection. Accordingly, in contrast to the current CONARC system, four roller rotary connections (two for the furnace roof, one for the oxygen ^anicei and oivs fpr the electrode support arms) can be dispensed with. The invention will be described in the following with reference to the drawing. The drawing shows the electric arc furnace installation. However, only the parts or units essential to an understanding of the invention are described. The furnace vessel is designated in its entirety by 1. This furnace vessel 1 comprises a lower furnace vessel, an upper furnace vessel and the furnace roof 2. The transformer vault with the hydraulic chamber is designated by 4. The electrode support arm system with the electrodes passing through the furnace roof 2 is designated by 5. The core idea of the invention is the arrangement of the upper furnace vessel and lower furnace vessel on a frame 3 and the horizontal movement thereof on a railway 6. Since the furnace is not tiltable but must be inclined for deslagging and tapping, the construction of the railway 6 is crucial. The contour of the railway 6 is selected in such a way that the center axis of the frame 3, which can be referred to as the central axis of inclination, always moves on level between the wheel axles (no vertical paths). This means that as the furnace starts to move out of the working position, the axis on the deslagging side descends, while the axis on the tapping side ascends. The upper furnace vessel automatically moves away (descends) from the furnace roof, which is why a roof lifting mechanism can be dispensed with. This process brings the furnace to an inclination of-5° (toward the left-hand side referring to the drawing) at which excess slag runs out. The furnace continues to move horizontally at this inclination until the upper vessel is no longer covered by the furnace roof. The axis on the deslagging side now ascends again, while the axis on the tapping side descends in turn. In this way, the furnace is initially brought into the horizontal again. In this position, depending on the process step, the second scrap basket can be set. The vessel then continues to descend for tapping at +5° (inclines toward the right-hand side). In this position, the tap is opened and the molten steel can flow into the ladle on the ladle car 10. The tapping is concluded in that the furnace is now rapidly moved back until reaching the -5° position. In this position, the pool at the flow-out (residual amount of molten steel) is prevented. Further, the stationary bay maintenance platform 9 is located directly below the tap. After the taphole is serviced, the tap is closed again and the first scrap basket is set at the same point. The furnace is then moved farther in direction of the working position so that the upper vessel coming from below again joins snugly with the furnace roof 2. The scrap basket is designated by 11. Patent Claims 1. Electric arc furnace having a lower furnace vessel, an upper furnace vessel, and a furnace roof (2) which receives the electrodes and by which the upper furnace vessel can be closed, and a frame (3) which is movable horizontally on rails (6) and on which the furnace vessel is arranged, characterized in that the furnace roof (2) with the associated system components and the electrode support arm system (5) are arranged in a stationary manner, in that the entire furnace vessel comprising the lower furnace vessel and the upper furnace vessel is arranged on the frame (3) and is movable along with the latter from the position below the furnace roof (2), wherein the railway (6) for the frame (3) is constructed in such a way that during the movement along the railway (6) the furnace executes inclinations which initially bring it into an inclination on the deslagging side and, as the movement continues, through a horizontal position into an inclination on the tapping side, wherein the center axis of inclination or center axis of the frame only moves horizontally during the relative movement relative to the furnace roof. 2. Electric arc furnace according to claim 1, characterized in that the frame (3) has, at least at its two longitudinal ends, a wheel axle with wheels whose axial spacing is adapted to the railway (6) in such a way that the two axles or pairs of wheels are located on corresponding inclined areas of the railway when the frame and, therefore, the furnace vessel are in horizontal position. 3. Electric arc furnace according to one of the preceding claims, characterized in that the railway (6) has a sinusoidal shape with horizontally extending crest areas. 4. Electric arc furnace according to one of the preceding claims, characterized in that the railway (6) is trough-shaped in the area in which the furnace vessel is located below the furnace roof (2). 5. Electric arc furnace according to one of the preceding claims, characterized in that the frame (3) is movable by means of a cable drive. 6. Electric arc furnace according to claim 5, characterized in that an electric- motor drive with two cable drums is provided on the tapping side for a roll-off portion of cable and a roll-up portion of cable, wherein the ends of the cable are fastened to the frame (3) at both sides of the center axis, and a deflection roller is provided on the deslagging side for the return of the deslagging-side portion of cable. 7. Electric arc furnace according to one of the preceding claims, characterized in that a ladle transfer car with ladle is positioned below the railway (6) in the tapping position of the furnace.

Full Text

ELECTRIC ARC FURNACE
The invention is directed to an electric arc furnace with a lower furnace vessel, an upper furnace vessel, and a furnace roof which receives the electrodes and by which the upper furnace vessel can be closed, and a frame which is movable horizontally on rails and on which the furnace vessel is arranged.
Both tiltable and non-tilting electric arc furnaces are known. EP 0 049 926, for example, discloses a tiltable arc furnace whose furnace vessel is movable horizontally out of the position below the furnace roof after the furnace roof with the electrodes is raised.
The electric arc furnace according to WO 03/029499 is likewise tiltable, but can also remain stationary. In this furnace, the tapping channel is provided in a separately built-on bay which is removably fitted to the terminating wall of the furnace vessel which is round itself.
For tapping, the furnace vessel is tilted so that the liquid metal enters the tapping channel in the bay.
In the non-tiltable variant, a pressure is built up in the bay so that the metal is initially kept away from the tap and then - when the tap is opened - immediately flows in.
The lower furnace vessel has a bottom taphole at its lowest point through which the furnace can be completely emptied when required.
A metallurgical vessel with a tapping device based on the principle of a waterlock or siphon is known from DE 199 19 378 Al,
By virtue of this design, the vessel also need not be tilted for tapping.
In electric arc furnaces, it is necessary to remove the furnace roof for charging so that the interior of the furnace can be filled by means of a scrap basket.

For this purpose, in the electric arc furnace according to EP 0 049 926, the electrodes are first moved out of the furnace by raising them so that the roof of the furnace can be lifted subsequently and swung to the side.
Corresponding lifting and swiveling arrangements are necessary for this purpose.
The known tiltable or non-tiltable furnace constructions, including the accompanying units, are expensive and costly to operate and maintain.
It is the object of the invention to provide an electric arc furnace which is not tiltable on the one hand and in which, on the other hand, the furnace roof need not be swung out and lifted and the electrodes need not be swung out.
This object is met by the features of patent claim 1. Advantageous embodiments are indicated in the subclaims.
The essential difference in the electric arc furnace according to the invention is that tilting of the furnace for purposes of deslagging and tapping the molten steel is dispensed with. Instead of a furnace tilting system, a furnace moving system is now used, and the furnace roof need no longer be lifted or swiveled.
As was mentioned above, the furnace tilting system is dispensed with in its entirety. Specifically, this furnace tilting system comprises the following components:
• tilting cylinder, including valve block
• tilting lock, including tilting lock cylinder
• emergency tilting valve
• control, limit switch, tilt angle sensor
• Approximately 3 metric tons of welded steel plate construction.
The currently conventional tilting frame supporting the furnace vessel system is changed to a translationally horizontally movable frame similar to a ladle transfer car. This frame is symmetrical and has two axles. In contrast to the tilting frame (tilting platform), this frame dispenses with heavy tilting cradles and also, because it eliminates the roof swiveling movement, does away with the complicated added-on construction

which until now served to receive the large rolling bearings which were required for that purpose. The resulting savings on material amounts to approximately 35 to 40 metric tons depending on the furnace size, representing heavy, labor-intensive welded steel plate construction. These savings extend further to the mechanical machining, e.g., for the bearing seat or the contour of the cradle, which is also expensive.
The platform construction covering this frame is now symmetrical and is likewise appreciably smaller and completely does away with supporting framing.
The rolling paths (with costly rolling path teeth, approximately 101 of expensive steel slab) which were formerly required are replaced by about 25 m of contoured railway. These rails comprise cast members (ADI, globular graphite iron). The process taking place when moving the frame will be described below with reference to the drawing.
The frame is driven, for example, by two stationary electric-motor drives on the tapping side (similar to a crane hoist). Each drive acts on a cable drum with a roll-off steel cable end and a roll-up steel cable end, depending on the movement direction. The cable ends are connected on both sides of the vessel frame to the center axle. Only one deflection roller, by which the cable can also be pretensioned if need be, is located on the deslagging side. Depending on the rotation direction of the drives, the frame is pulled in one direction or the other without the cable fastening points being moved vertically. This reduces the lifting work of the moving masses to a minimum.
In principle, this technique does not require any changes to the conventional, proven upper vessel system (lower vessel and upper vessel, tapping system, furnace door).
Basically, there is no change in the upper vessel and lower vessel. Only the contour of the furnace bottom, i.e., the ascending angle of the bottom in the tapping area, need be adapted, if necessary, to the required angle of inclination that can be realized. At the same time, the solution according to the invention affords the possibility of dispensing with the swinging out of the furnace roof system, e.g., for purposes of charging the furnace vessel, and, therefore, at the same time dispensing with the swiveling out of the electrode support arm system.

Therefore, the swivel gantry system, including the roof supporting structure arms, is entirely done away with. This accounts for an additional 35 to 40 tons of heavy, mechanically machined welded steel plate construction. The electrode column guide frame, formerly part of the swivel gantry, is now cast from reinforced concrete and is part of the furnace foundation or transformer vault. This also does away with the need for water cooling of the above-mentioned structural component parts.
The swivel system and swivel drive are dispensed with without substitution.
Further, the elbow on the afterburning chamber side can now be designed so as to be stationary because there is no swiveling movement of the furnace roof to consider.
Because of the contour of the railway, the furnace vessel system is removed from the furnace roof automatically when moving in direction of the tapping position and is automatically moved toward the furnace roof when moving in direction of the operating position. Therefore, not only is there no longer a need for a furnace roof lifting mechanism (including the roof lifting cylinder), but there is also no longer a need to place the latter in the immediate vicinity of current-conducting parts, which always caused problems with creeping currents (induction) and arcing (St. Elmo's fire). Dispensing with the water cooling, insulation, and equipotential bonding in this area results in additional savings.
The spoke frame of the furnace roof is changed only with respect to the arrangement of the spokes, but otherwise basically remains more or less unchanged.
Since the furnace roof need no longer be raised, the three receptacles for the roof lifting mechanism are completely eliminated. Instead, four of six spokes are lengthened outward parallel to the transverse axis of the furnace. These elongations are supported on the left-hand side and right-hand side on expansions of the guide frame foundation and on separate foundations on both sides of the afterburning chamber. The furnace roof can be accessed directly via steps which are cast integral with the guide frame foundation. The roof platform is installed directly on the roof in the form of grating elements. This is appreciably more convenient than the steep ladder steps which were used formerly and which are now likewise dispensed with. Also, water cooling can be omitted in this area.

The alloying connection piece is arranged on the slag door side of the exhaust elbow so that the entire alloying system can also be arranged in a stationary manner. This leads to substantial savings.
The connection to the cooling water network is carried out on the transformer vault side. Four simple compensators are now used instead of two expensive swivel joints. Long hose connections with large nominal widths coming from the transformer vault wall are entirely dispensed with.
The above-mentioned innovations and changes lead to appreciable savings in the sphere of servicing and maintenance. The tie rods which carried the electrode guide columns are dispensed with because they are now arranged in an expansion of the hydraulic chamber below the furnace platform on fixedly anchored bearing blocks. This means that the regulating cylinders are no longer freely suspended, but rather are protected and maintenance-friendly.
Long hose lines are dispensed with because a swiveling movement need no longer be taken into account.
The transformer vault and furnace foundation are more integrated. The load distribution in the foundation is appreciably more favorable because the furnace load is now introduced via four wheels instead of only two cradle standing points.
Below the furnace platform, the hydraulic chamber extends to the furnace foundation. This also creates additional space for more chambers, e.g., for the climate control system, and the like.
On the whole, conditions below the furnace platform are substantially simplified. Because of the boundary conditions that are created in this way, a doghouse of a furnace enclosure can be implemented in a simpler maimer.
The design of the cooling water supply is substantially more favorable in terms of acquisition and particularly with regard to engineering resources. There are fewer water-cooled structural component parts. This also results in savings on maintenance.
There are no longer any exposed pipelines below the furnace platform. All pipelines, particularly the larger nominal widths, can be accessed by the crane.

Hose lines which formerly made it possible to tilt the arc furnace are dispensed with. Instead, the hoses supporting the translational movement of the furnace are guided via the energy chain and are positioned on the furnace platform so as to be easily accessible.
The DN300 hoses to the furnace roof with a length of 13 m are dispensed with because the roof is now stationary. Instead, there are two or four simple DN300 compensators. Swivel joints are also no longer used.
The quantity of hoses for coolant water, hydraulic oil, compressed air, and so on, is appreciably reduced because there are no longer any tilting, lifting or swiveling movements. This substantially eases the piping situation at the transformer vault wall as well as the space conditions on the furnace platform in the area of the transformer vault.
All of the other media such as coal, oxygen, nitrogen, argon, etc. can likewise be supplied via the energy chain.
A movable bay maintenance platform is done away with in its entirety, i.e., no costly electric-motor chain drive and no movable parts are required in this area. The bay maintenance platform is now part of the furnace foundation (the furnace platform) and spans the ladle pit in the manner of a bridge. This bridge is accessible from two sides and can be constructed appreciably wider than the previous maintenance platform, which offers distinct advantages with respect to taphole upkeep. This maintenance bridge is accessed via descents from the furnace platform. This affords additional advantages with respect to changing the taphole. Nozzle brick breakout devices (hydraulic, pneumatic or mechanical) which are frequently demanded by customers can easily be mounted on this maintenance bridge.
The electrode settling state and electrode jointing state remain unchanged.
The electrode resetting device is now integrated in the furnace roof or is fitted to the roof-center supporting ring. A circular rail (a square) is added to the upper side of the latter for this purpose. The resetting device comprises three supports which are oriented in a star-shaped manner relative to one another. While this "star" is joined at its origin, rollers moving on the rails mentioned in the beginning are located at the three outer ends.

This rotatable base frame is protected from the radiation of the hot electrodes by solid refractory covers. Further, each of these arms carries a centrally spring-cushioned refractory monoblock of the same diameter as the electrodes. This arrangement is positioned at a phase offset of 60° relative to the electrodes and can be rotated by these same 60° by means of a pneumatic drive. Accordingly, the apertures in the roof center can be electively opened or closed. To reset the electrodes, these electrodes are initially moved into their highest position, the resetting device is then rotated by 60° and the roof center openings are closed. The electrodes are then successively moved down until they contact the monoblocks, the electrodes are detached, the electrode support arms are raised corresponding to the respective resetting length, the electrodes are reattached and then moved into their highest position again. Contact with the monoblocks can be monitored by means of the hydraulics (pressure monitoring and/or flow monitoring) so that the regulating cylinders are stopped before the entire weight of the electrode support arms and guide columns comes to rest on the resetting device or the springs of the monoblocks are fully compressed.
The high-current cables need no longer compensate for swiveling and tilting movements and are accordingly no longer twisted (80° - 90°) and can be shorter than before. This means that the life of the cables is substantially prolonged. Accordingly, the cables are basically improved. For the reasons stated above, the costs of repair and overhaul are also reduced.
The reactance can also be lowered because of shorter cable lengths. This translates to a higher input of energy in the furnace, reduced circuit feedback, and longer arcs.
Further, there is appreciably less breakage of and damage to the electrodes because of the omitted movements.
Due also to the absence of swiveling movement, the cost of laying pipe and hose to the transformer vault wall is substantially lower and savings on engineering and purchasing are ensured.
Due to fewer pipes at the transformer vault wall, a maintenance platform such as is frequently requested by customers is easier to implement.

The time sequences of the novel concept and the conventional concept are described for purposes of comparison.
Novel furnace concept
1. Power on
2. Power off
3. The furnace movement is started. The furnace supporting frame is inclined for deslagging (-5°). At the same time, the furnace vessel moves away from the furnace roof.
4. At the conclusion of the deslagging process, the furnace is inclined for tapping (+5°).
5. Tapping is initiated. During tapping, the first scrap basket is prepared for charging above the open furnace.
6. The tapping is stopped by rapidly moving the furnace frame back so that the vessel automatically inclines by -10° (in -5° position).
7. The taphole is trimmed, the stopper is closed, and the tapping channel is filled.
8. The first scrap basket is set.
9. The furnace is moved back.
10. Power on
11. Power off
12. The furnace vessel is moved for setting the second scrap basket which has been prepared in the meantime.
13. The second scrap basket is set.
14. The furnace is moved back.
15. Power on.

Conventional furnace concept
1. Power on
2. Power off
3. The furnace is tilted by three degrees.
4. Tapping is initiated.
5. The tapping is stopped by rapidly tilting back.
6. The taphole is trimmed, the stopper is closed and the tapping channel is filled.
7. The furnace is tilted into horizontal position.
8. The furnace roof is swung out.
9. The first scrap basket is positioned over the open vessel.
10. The first scrap basket is set.
11. The empty scrap basket is removed.
12. The furnace roof is swung in.
13. Power on
14. Power off
15. The furnace roof is swung out.
16. The second scrap basket is positioned over the open vessel.
17. The second scrap basket is set.
18. The empty scrap basket is removed.
19. The furnace roof is swung in.
20. Power Although the movement speed of the furnace vessel is not mentioned in this juxtaposition, it is immediately clear that a whole range of partial processes can take place in parallel in the novel concept. This is particularly clear with regard to the setting

of the scrap baskets. When the speeds of ladle transfer cars of this order of magnitude, which surely move at 0.4 m per second, i.e., opening of the furnace (approximately 9 m) can be accomplished in under 25 seconds, are compared to the angular speeds for swiveling the roof on the same order of magnitude, it is clear that an arc can be operated more efficiently with the novel concept, i.e., a reduction in tap-to-tap time is possible.
A mirror-symmetrical arrangement of the vessel system (including movable frame, independently supplied with media such as cooling water) is conceivable. While melting takes place in one system, tapping can take place in the other system, its tap can be serviced, and its first full scrap basket set.
Accordingly, parallel operation of the mirror-symmetrical furnace system is possible. If one of the vessels must be closed again, this parallel operation can be interrupted without having a negative effect on the operation of the other vessel system. Accordingly, a time-consuming vessel changing process (vessel exchanging technique) can be dispensed with to the benefit of longer power-on times. The deslagging zone is large enough so that a vehicle for carrying away or clearing the slag can easily access the slag pit by both sides of the afterburning chamber.
Both vessel systems, or their movable supporting frames, could be provided with a bridge-like expansion in the area of the slag door which, for example, has a temperature lance and sampling lance and facilitates maintenance work.
In view of the additional enormous potential savings, this variant is a useful addition to the overall concept.
The variant described above also makes it possible to use "CONARC covers" (oxygen blowing) next to the respective tapping position. Costly swiveling drives can also be dispensed with in this connection. Accordingly, in contrast to the current CONARC system, four roller rotary connections (two for the furnace roof, one for the oxygen ^anicei and oivs fpr the electrode support arms) can be dispensed with.
The invention will be described in the following with reference to the drawing. The drawing shows the electric arc furnace installation. However, only the parts or units essential to an understanding of the invention are described.

The furnace vessel is designated in its entirety by 1. This furnace vessel 1 comprises a lower furnace vessel, an upper furnace vessel and the furnace roof 2.
The transformer vault with the hydraulic chamber is designated by 4.
The electrode support arm system with the electrodes passing through the furnace roof 2 is designated by 5.
The core idea of the invention is the arrangement of the upper furnace vessel and lower furnace vessel on a frame 3 and the horizontal movement thereof on a railway 6. Since the furnace is not tiltable but must be inclined for deslagging and tapping, the construction of the railway 6 is crucial.
The contour of the railway 6 is selected in such a way that the center axis of the frame 3, which can be referred to as the central axis of inclination, always moves on level between the wheel axles (no vertical paths). This means that as the furnace starts to move out of the working position, the axis on the deslagging side descends, while the axis on the tapping side ascends. The upper furnace vessel automatically moves away (descends) from the furnace roof, which is why a roof lifting mechanism can be dispensed with. This process brings the furnace to an inclination of-5° (toward the left-hand side referring to the drawing) at which excess slag runs out. The furnace continues to move horizontally at this inclination until the upper vessel is no longer covered by the furnace roof. The axis on the deslagging side now ascends again, while the axis on the tapping side descends in turn. In this way, the furnace is initially brought into the horizontal again. In this position, depending on the process step, the second scrap basket can be set. The vessel then continues to descend for tapping at +5° (inclines toward the right-hand side). In this position, the tap is opened and the molten steel can flow into the ladle on the ladle car 10. The tapping is concluded in that the furnace is now rapidly moved back until reaching the -5° position. In this position, the pool at the flow-out (residual amount of molten steel) is prevented. Further, the stationary bay maintenance platform 9 is located directly below the tap. After the taphole is serviced, the tap is closed again and the first scrap basket is set at the same point. The furnace is then moved farther in direction of the working position so that the upper vessel coming from below again joins snugly with the furnace roof 2. The scrap basket is designated by 11.

Patent Claims
1. Electric arc furnace having a lower furnace vessel, an upper furnace vessel, and a furnace roof (2) which receives the electrodes and by which the upper furnace vessel can be closed, and a frame (3) which is movable horizontally on rails (6) and on which the furnace vessel is arranged, characterized in that the furnace roof (2) with the associated system components and the electrode support arm system (5) are arranged in a stationary manner, in that the entire furnace vessel comprising the lower furnace vessel and the upper furnace vessel is arranged on the frame (3) and is movable along with the latter from the position below the furnace roof (2), wherein the railway (6) for the frame (3) is constructed in such a way that during the movement along the railway (6) the furnace executes inclinations which initially bring it into an inclination on the deslagging side and, as the movement continues, through a horizontal position into an inclination on the tapping side, wherein the center axis of inclination or center axis of the frame only moves horizontally during the relative movement relative to the furnace roof.
2. Electric arc furnace according to claim 1, characterized in that the frame (3) has, at least at its two longitudinal ends, a wheel axle with wheels whose axial spacing is adapted to the railway (6) in such a way that the two axles or pairs of wheels are located on corresponding inclined areas of the railway when the frame and, therefore, the furnace vessel are in horizontal position.
3. Electric arc furnace according to one of the preceding claims, characterized in that the railway (6) has a sinusoidal shape with horizontally extending crest areas.
4. Electric arc furnace according to one of the preceding claims, characterized in that the railway (6) is trough-shaped in the area in which the furnace vessel is located below the furnace roof (2).
5. Electric arc furnace according to one of the preceding claims, characterized in that the frame (3) is movable by means of a cable drive.

6. Electric arc furnace according to claim 5, characterized in that an electric-
motor drive with two cable drums is provided on the tapping side for a roll-off portion of
cable and a roll-up portion of cable, wherein the ends of the cable are fastened to the
frame (3) at both sides of the center axis, and a deflection roller is provided on the
deslagging side for the return of the deslagging-side portion of cable.
7. Electric arc furnace according to one of the preceding claims,
characterized in that a ladle transfer car with ladle is positioned below the railway (6) in
the tapping position of the furnace.

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=vMt0g30GQvujexUEyQVYeQ==&loc=egcICQiyoj82NGgGrC5ChA==

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Patent Number

269275

Indian Patent Application Number

386/CHE/2010

PG Journal Number

42/2015

Publication Date

16-Oct-2015

Grant Date

13-Oct-2015

Date of Filing

15-Feb-2010

Name of Patentee

SMS SIEMAG AG

Applicant Address

EDUARD-SCHLOEMANN-STRASSE 4, 40237 DUSSELDORF

Inventors:

#	Inventor's Name	Inventor's Address
1	ERTL, MARKUS	VASANT VIHAR A-8/26, 1ST FLOOR, NEW DELHI-110057
2	ARORA, ATUL	H 4, OLD GOBIND PURA EXTENSION, NEW DELHI-110051

PCT International Classification Number

C21C 5/52

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA