EP0073537B1 - Smoke elbow support for an electric arc furnace - Google Patents

Abstract

Arc furnace has a furnace shell, a furnace lid with lid ring and a lid lifting and swivelling means as well as a lid opening in the furnace lid for exhausting the flue gas from the interior of the furnace and a flue gas exhaust nozzle for removing the flue gases above the lid opening, the nozzle being supported on the furnace lid ring. By means of this design feature as well as a guide arrangement and a locking means the flue gas exhaust nozzle can be completely integrated into the operating steps of the arc furnace in a simple and economical fashion.

Description

The invention relates to an electric arc furnace with a furnace, a furnace cover with a cover ring and a cover lifting and swiveling device, a cover hole for the flue gas extraction from the interior of the furnace being carried out in the furnace cover and a flue gas extraction nozzle arranged for the continuation of the flue gases above the cover hole.

The constructive design of the flue gas extraction nozzle and in particular its assignment to the electric arc furnace are of greater importance because it represents the connecting link in the flue gas detection system between the movable furnace vessel and the stationary installed flue pipe and secondly has to be fully integrated into the individual work operations of the furnace operation.

• - Das Chargieren: Hierzu wird normalerweise der Ofendeckel vom Ofengefäss gehoben, aus dem Bereich des Ofengefässes ausgeschwenkt und nach erfolgter Chargierung des Ofens wieder in die Ausgangslage zurückgebracht und auf das Ofengefäss abgesenkt.
• - Das Schmelzen. Es werden die heissen und staubhaltigen Abgase in Direktabsaugung aus dem Ofengefäss über ein viertes Deckelloch abgesaugt.
• - Das Ausgiessen. Der Ofen wird sukzessive bis zu seiner vollständigen Entleerung gekippt.
• - Das Deckelschwenken. Der Ofendeckel wird durch eine Deckelhebe- und Schwenkvorrichtung, den sogenannten Oberofen, zuerst vertikal nach oben vom Ofenkessel abgehoben und dann horizontal zur Seite weggeschwenkt.

The main work operations in arc furnace operation are:

• - Charging: For this purpose, the furnace lid is normally lifted from the furnace vessel, swung out of the region of the furnace vessel and, after the furnace has been charged, returned to the starting position and lowered onto the furnace vessel.
• - The melting. The hot and dusty exhaust gases are extracted by direct extraction from the furnace vessel through a fourth cover hole.
• - The pouring out. The furnace is gradually tilted until it is completely empty.
• - Swing the lid. The furnace lid is first lifted vertically upwards by a lid lifting and swiveling device, the so-called upper furnace, and then swung horizontally to the side.

In the currently known direct extraction systems in arc furnaces, the extraction nozzle is attached to the upper furnace (cover lifting device). The lower end of the nozzle is located above the cover hole at a distance that is slightly larger than that of a cover lift. The free space between the furnace cover and the extraction nozzle is closed by a cylindrical transition piece, the so-called collar, into which the lower end of the extraction nozzle protrudes telescopically on its upper side and the lower end of the collar is supported on the furnace cover above the cover hole. The collar is made of heat-resistant steel sheet and has no significant weight. Since the lower part of the collar is subjected to high thermal stress, it is normally water-cooled to prevent scaling and warping. However, an additional cooling circuit with monitoring and control devices is required for this. When lifting the cover, the collar is either lifted by an additional lifting device or, since it rests freely on the furnace cover, is also lifted by it.

The suction nozzle and thus also the collar are arranged perpendicular to the curved surface of the lid and normally form an angle of 18-20 degrees with the lid axis. When lifting the lid without an additional lifting device, the lid lifting direction and the sliding direction of the collar deviate by this angular amount and lateral forces occur which are transferred to the lid arch.

While the contact surface of the cover and collar can still be kept relatively gas-tight, this is no longer the case for design reasons if the upper part of the collar overlaps with the lower part of the connecting piece. The consequence of this is an uncontrolled gas leak at the transition point from the collar to the neck.

It can be seen from the above explanations that, in the currently known direct extraction systems in arc furnaces, the collar makes additional expenditure necessary for the furnace lid lifting and also impairs the effectiveness of the flue gas extraction.

The invention seeks to remedy this. The invention, as characterized in the claims, achieves the object of creating an arc furnace with direct extraction of the exhaust gases by means of a flue gas extraction connection, with which the exhaust gases are optimally recorded and which can be integrated in a simple and economical manner into the work operations of the arc furnace, in that the nozzle is supported on the furnace cover ring.

• - Der Ofendeckel und der Rauchgasstutzen können gemeinsam auf einfache Weise, lediglich mit der Deckelhebe- und Schwenkvorrichtung ausgewechselt werden.
• - Der Rauchgasstutzen kann vor dem Deckelwechsel, beispielsweise durch den Stahlwerkshallenkran, von dem auszuwechselnden Deckel abgehoben und nach erfolgtem Deckelwechsel wieder auf dem neuen Deckel in der konstruktiv dafür vorgesehenen Position aufgesetzt wird. Diese Lösung stellt sich als Normalfall dar, da der Ofendeckel einem höheren Verschleiss unterworfen ist als der Stutzen und dementsprechend häufiger ausgewechselt werden muss.
• - Der Ofendeckel und der Rauchgasstutzen können gemeinsam mit der Deckelhebe- und Schwenkvorrichtung auf den Deckelauswechselplatz transportiert werden und dort kann, beispielsweise mit dem Stahlwerkshallenkran, der ursprüngliche Stutzen vom auszuwechselnden Deckel abgehoben und auf dem neuen, in der dafür vorgesehenen Lage positioniert wird. Danach wird der neue Deckel samt dem ursprünglichen Stutzen in die Ausgangslage zurückgeschwenkt und auf das Ofengefäss aufgelegt.
• - Aufwendige Vorrichtungen und Regelanlagen zur Flüssigkeitskühlung des Kragens entfallen.

The advantages achieved by the invention are essentially as follows:

• - The furnace lid and the flue gas nozzle can be replaced together in a simple manner, only with the lid lifting and swiveling device.
• - The flue gas nozzle can be lifted from the cover to be replaced before the cover is changed, for example by the steelworks hall crane, and after the cover has been replaced it can be put back on the new cover in the position provided for this purpose. This solution presents itself as a normal case, since the furnace cover is subject to greater wear than the socket and therefore has to be replaced more frequently.
• - The furnace lid and the flue gas nozzle can be transported together with the lid lifting and swiveling device to the lid replacement area and there, for example with the steelworks hall crane, the original nozzle can be lifted from the lid to be replaced and positioned on the new one in the intended position. Then the new cover, including the original nozzle, is returned to the starting position pivots and placed on the oven vessel.
• - Elaborate devices and control systems for liquid cooling of the collar are eliminated.

The objection that it is less time-consuming to lift a relatively light collar than a flue gas nozzle weighing several tons becomes insignificant if one takes into account that the mass of the nozzle is only a fraction of the mass of the entire lid, and accordingly the lid lifting device is not subjected to much more stress .

The socket is supported on the cover ring in a non-positive or positive manner, so that it remains immovably fixed on the cover ring when the furnace is tilted or when the cover is pivoted.

An advantageous further development of the subject matter of the invention can be seen in the fact that the nozzle is provided with a guide arrangement which interacts with the cover lifting and pivoting device in such a way that the nozzle is guided when the cover is lifted and is supported when the furnace is tilted. This constructive measure eliminates the need for positive and form-fitting support of the nozzle on the cover ring in the tilting direction for pouring out or emptying the furnace.

According to claim 3, the guide assembly contains on the one hand at least one guide rail running in the lifting direction of the furnace cover, and on the other hand at least a few guide rollers.

According to claim 4, the guide rail is guided between two guide rollers.

According to claim 5, the guide rail is firmly connected to the support arm of the lid lifting device and the guide rollers are firmly connected to the nozzle.

According to claim 6, the guide rail is firmly connected to the socket and the guide rollers are firmly connected to the support arm of the lid lifting device. The advantageous effect of the solution according to claims 3, 4, 5 and 6 is to be seen in the fact that, with relatively little design effort, the nozzle is reliably guided during the lifting or lowering movement.

According to claim 7, the guide assembly contains at least a pair of guide levers which are articulated with the same ends to the support arm of the lid lifting device and with the other ends to the nozzle and the support of the nozzle on the cover ring is carried out via at least one further lever.

According to claim 8, the guide lever are of equal length and are arranged in parallel. The guide arrangement according to claims 7 and 8 has the advantage that the guide rollers can be omitted.

According to claim 9, the guide arrangement comprises a locking device for securing the nozzle in a raised position. The constructive measure according to claim 9 enables the cover to be separated from the connector since the connector remains guided and locked in the lid lifting and swiveling device after it has been locked, and the necessary work operations, for example changing the lid or repairs to the lid, are carried out with the lid, regardless of the connector can be.

According to claim 10, the guide arrangement and / or the locking device are arranged symmetrically on both sides of the nozzle. The advantage according to claim 10 is that the form-fitting and non-positive support of the connector on the cover ring can be dispensed with completely, since the connector is guided in both tilting directions of the furnace.

The invention is explained below with reference to exemplary embodiments shown in the drawing.

• Figur 1 eine schematische Darstellung der Vorderansicht einer beispielsweisen Ausführungsform eines Lichtbogenofens,
• Figur 2 eine schematische Draufsicht des Ofens gemäss Fig. 1,
• Figur 3 eine schematische Seitenansicht des Ofens gemäss Fig. 1,
• Figur 4 einen vergrösserten, vertikalen und teilweisen Schnitt durch die Vorderansicht eines Rauchgasabsaugstutzens einschliesslich einer ersten Variante einer beispielsweisen Ausführungsform einer Leitanordnung und einer Arretiervorrichtung für den Stutzen,
• Figur 5 einen vergrösserten, vertikalen teilweisen Schnitt durch die Seitenansicht eines Rauchgasabsaugstutzens gemäss Fig.4.
• Figur 6 einen vergrösserten, vertikalen teilweisen Schnitt durch die Vorderansicht eines Rauchgasstutzens einschliesslich einer zweiten, beispielsweisen Variante einer Leitanordnung und Arretiervorrichtung.
• Fig. 1 zeigt eine schematische Darstellung der Vorderansicht einer beispielsweisen Ausführungsform eines Lichtbogenofens.

The drawing shows:

• FIG. 1 shows a schematic illustration of the front view of an exemplary embodiment of an arc furnace,
• FIG. 2 shows a schematic top view of the furnace according to FIG. 1,
• FIG. 3 shows a schematic side view of the furnace according to FIG. 1,
• FIG. 4 shows an enlarged, vertical and partial section through the front view of a flue gas suction nozzle, including a first variant of an exemplary embodiment of a guide arrangement and a locking device for the nozzle,
• FIG. 5 shows an enlarged, vertical partial section through the side view of a flue gas extraction nozzle according to FIG. 4.
• FIG. 6 shows an enlarged, vertical partial section through the front view of a flue gas nozzle, including a second, for example variant of a guide arrangement and locking device.
• Fig. 1 shows a schematic representation of the front view of an exemplary embodiment of an arc furnace.

The arc furnace 1 with furnace cover 5 is mounted in an opening on the platform 6, which is supported on two roller cradles 7, which in turn are supported on the weighing beams 8, which are firmly anchored to the foundation 9. The pouring spout 2 can also be seen in FIG. 1. A movable rotary console 10 is arranged on the platform 6, to which the cover lifting and swiveling device 11 is fastened. The cover lifting and swiveling device 11 consists of a support arm 13 and a support arm column 12.

The platform 6 also carries three electrode positioning columns 14, of which only one is visible in FIG. 1. The electrode adjusting columns 14 are hydraulically connected to be movable individually in the vertical direction with electrode adjusting cylinders 15. The electrode support arms 16 are fastened to the electrode adjusting columns 14 and the electrodes 18 are held in electrode holders 17 at their outer ends.

Of the total of three electrode support arms 16, only one is again completely visible, and only two of the electrodes 18 can be seen, the third being covered. On the furnace cover 5, the cover ring 4 of which rests on the cover support ring 3 of the furnace 1, the flue gas outlet 19 with flange 20 is arranged. The attachment of the socket 19 is not shown in FIG. 1 and its guide arrangement within the support arm 13 of the cover lifting and pivoting device 11 is only indicated by the guide rail 21, it is shown in detail in FIGS. 4, 5 and 6. On the cover ring 4 of the furnace cover 5, support eyes 22 are attached, in which support cables 23 are fastened in the exemplary embodiment of FIG. 1, of which only two of a total of four are visible. The support cables 23 are guided over rollers 24, which are mounted in roller carriers 25 on the support arm 13. The support cables 23 are connected to the hydraulic cylinder 26, which can lift or lower the furnace cover 5 from the furnace boiler 1.

FIG. 2 shows a schematic top view of the furnace according to FIG. 1.

The reference numerals from FIG. 1 apply to the same parts for FIG. 2 as for the other drawings.

2, the lid lifting device 11 with the double-T profile beams 29 and the connecting cross member 28 can be seen.

U-shaped profile beams 30 are fastened to the double-T profile beams 29 perpendicularly to them, between which the connecting piece 19 is arranged. The guide rail 21 is located between the profile beams 30 and the connecting piece. The slag door 27 is attached to the furnace boiler 1.

In addition to the lid lifting and swiveling device 11, the electrode adjusting columns 14 are arranged on the rotary console 10, which, as described in detail in FIG. 1, have electrode support arms 16, on the outer ends of which the electrodes 18 are held in electrode holders 17. After the furnace cover 5 has been lifted off the furnace boiler 1 by the lift-off mechanism described in FIG. 1, the cover device 11 together with the lifted cover 5 is pivoted out of the region of the furnace boiler 1 laterally until the latter is completely exposed and the electric arc furnace is charged can.

Since, as already mentioned, the electrode positioning columns 14 are also located on the rotary console 10, they are also pivoted out, and in order to be able to carry out this pivoting operation at all, it goes without saying that the electrodes are first pulled over the upper edge of the furnace boiler 1.

FIG. 1 shows a schematic side view of the furnace according to FIG. 1.

The flue gas suction nozzle 19, which is located within the symmetrically arranged guide rails 21, is supported on the cover ring 4 by the support 36 and the foot 37.

FIG. 4 shows an enlarged, vertical and partial section through the front view of a flue gas extraction connector 19 including a first variant of an exemplary embodiment of a guide arrangement 21, 38 and a locking device 39, 42 for the connector 19.

The flange 19 with its flange 34 is positioned genetically above the cover hole 33, a gap 35 being located between the cover lining 31 and the flange 34 of the nozzle 19. On the other hand, the socket 19 is exactly in alignment with the fixed flue gas discharge shaft 43. The gap 51 is provided between the flue gas discharge shaft 43 and the flange 20 of the socket 19. The two stomata 35 and 51 ensure that the connector 19 does not abut the brick lining 31 and the flue gas duct 43 neither in its static position nor when it is lifted. The columns 35 and 41 are dimensioned such that the external air supply is kept to a minimum with sufficient scope for the lifting maneuver of the nozzle 19.

The nozzle 19 is supported with its entire mass on the support 36 and the foot 37 of the support 36 on the cover ring 4.

The cover ring 4 lies on the cover support ring 3, which is firmly connected to the furnace vessel 1. The refractory lining 32 is located within the furnace vessel 1.

The nozzle 19 is guided by the guide arrangement, which consists of guide rail 21 and guide rollers 38, when lifting the nozzle 19 or the furnace cover 5 and supported when the furnace is tilted. In the exemplary embodiment, the guide rail 21 is fixedly connected to the support arm 13 of the lid lifting and pivoting device 11 by the U-profile carrier 30 and double-T profile carrier 29. The support arm 13 is only shown schematically in FIG. To reinforce this connection, a reinforcing plate 40 is additionally attached. The guide rollers 38 are firmly connected to the socket 19 and the guide rail 21 is guided between two pairs of guide rollers 38.

5 shows the enlarged, vertical partial section V-V according to FIG. 4.

In the projecting eye 41 of the socket 19, the guide rollers 38, which are not visible in FIG. 5, are firmly connected to the socket 19 via roller shafts 38 ".

The support edge 38 'secures the guide rollers 38 and thus also the socket 19 against lateral displacement.

In Fig. The locking device 39, 42 'can be seen, which secures the nozzle 19 in a raised position. It consists of the displaceable pin 39, which is arranged in the bore 21 'of the guide rail 21, and of the bore 42' within the projecting eye 42 of the connector 19.

In the exemplary embodiment according to FIGS. 4 and 5, only one side of the connector 19 is guided or set up for locking. But it is self-evident It goes without saying that the guide arrangement 21, 38 and the locking device 39, 42 'can be arranged symmetrically on both sides of the socket 19 and the socket 19 can be guided and locked on both sides.

• Deckelwechsel :
  • Soll der Ofendeckel 5, umfassend den Deckelring 4 und das feuerfeste Mauerwerk 31, zum Deckelwechsel angehoben werden, wird der Hydraulikzylinder 26 betätigt, der Zugkräfte auf die Tragseile 23 und Oesen 22 ausübt und der Deckel 5 angehoben wird. Da der Stutzen 19 auf dem Deckelring 4 des Deckels 5 abgestützt ist, wird er automatisch mitgehoben und durch die Leitanordnung 21, 38 geführt bis die Bohrung 42' des vorspringenden Auges 42 des Stutzens 19 sich auf gleicher Höhe wie die Bohrung 21' der Führungsschiene 21 befindet. Dann kann der verschiebbare Zapfen 39 in die Bohrung 42' eingeführt und der Stutzen 19 arretiert werden.

The functioning of the guide arrangement 21, 38 and the locking device 39, 42 'is described below:

• Changing the lid:
  • If the furnace cover 5, including the cover ring 4 and the refractory masonry 31, is to be lifted to change the cover, the hydraulic cylinder 26 is actuated, which exerts tensile forces on the support cables 23 and eyelets 22 and the cover 5 is lifted. Since the connector 19 is supported on the cover ring 4 of the cover 5, it is automatically lifted and guided through the guide arrangement 21, 38 until the bore 42 'of the projecting eye 42 of the connector 19 is at the same height as the bore 21' of the guide rail 21 located. Then the displaceable pin 39 can be inserted into the bore 42 'and the connector 19 can be locked.

The cover 5 is now separated in the swiveled-out position on the cover replacement site from the socket 19 by simply lowering the cover 5 and the socket 19 remains guided and locked in the support arm 13 of the cover lifting and pivoting device 11. The cover 5 separated from the socket 19 can now be opened completely the lid replacement area can be lowered and replaced. The new cover 5 is raised by the support ropes 23 until the connector 19 is completely supported on the cover ring 4 of the cover 5. Then the displaceable pin 39 is removed from the bore 42 'of the projecting eye 42 in the socket, the cover 5 together with the socket 19 is pivoted back into the starting position and the cover 5 and socket 19 are placed together on the cover support ring 3 of the furnace vessel 1 and the melting process can start again.

• Beim normalen Chargiervorgang werden Deckel 5 samt Stutzen 19 aus dem Bereich des Ofengefässes geschwenkt und nach erfolgtem Chargieren wieder in die Ausgangslage zurückgebracht und auf dem ofengefäss 1 abgesenkt. Eine Arretierung des Stutzens 19 erübrigt sich bei einem normalen Chargiervorgang.

Charging the oven:,

• In the normal charging process, cover 5 together with connecting piece 19 are pivoted out of the area of the furnace vessel and, after charging has been carried out, returned to the starting position and lowered on furnace vessel 1. Locking the nozzle 19 is unnecessary in a normal charging process.

6 shows an enlarged, vertical partial section through the front view of a connecting piece 19 including a second exemplary variant of a guide arrangement 47, 47 'and locking device 39, 42'.

The socket 19 is supported with its mass completely on the cover ring 4 via a further lever 44 and a U-profile carrier 45, which serves as a foundation for the lever 44.

The lever 44 is fixedly connected to the U-profile support by the connecting piece 46, the lever 44 and connecting piece 46 in turn being connected to one another in an articulated manner by means of bolts 49 "and 49" '.

In this exemplary variant, the guide of the connecting piece 19 consists of two guide levers 47, 47 ', which are connected to the support arm 13 of the cover lifting and pivoting device 11 by means of connecting ends 48, U-shaped profile supports 30 and double-T profile supports 29 having the same ends . The support arm 13 is only shown schematically in FIG. 6. The connection of the rectified ends of the guide levers 47, 47 'to the connecting bracket 48 is articulated, since it is carried out by movably mounted bolts 49. The other ends of the guide levers 47, 47 'are in turn connected to the connecting piece 19 by movably mounted bolts 49'. In Figure 6, the connection of the guide lever 47 to the socket 19 is covered by the mounting bracket 50 and thus not visible.

The locking device 39, 42 'consists of the displaceable pin 39 which is arranged in a hole in the fastening bracket 50 which is not visible in FIG. 6.

The mounting bracket 50 is connected with its widened lower part 50 'firmly to the U-section support 30, the double-T section support 29 and the support arm 13 of the cover lifting and pivoting device 11.

If the cover 5 is raised by the movement mechanism 22, 23, 26 described in detail in FIG. 4, the forces are transmitted via the U-shaped support 45, the connecting piece 46 and the further lever 44 to the connecting piece 19 and this is also lifted and relative moved to the support arm 13 of the lid lifting and pivoting device 11 and guided by the guide levers 47, 47 '. Since the guide levers 47, 47 'are arranged in parallel and have the same length, the connecting piece 19 is guided at right angles to the support arm 13 when it is lifted and in an arc with the radius of the length of the guide levers 47 and 47' from the pin bearing 49 to the pin bearing 49 ' swung out to the left. Therefore, the further lever 44 is articulated both on the socket with the bolt 49 "and on the connecting piece 46 with the bolt 49" ', so that the lever 44 can follow the slight movement of the socket 19 in the left direction when the socket 19 is raised .

When the cover 5 or the socket 19 is raised, the bore 42 'in the projecting eye 42 of the socket 19 is moved to the left once in the vertical direction and on the other hand in the horizontal direction by the amount AS and if the bore in the connection bracket 50' is congruent, in which the sliding pin 39 is arranged, with the bore 42 ', the pin 39 can be inserted into the bore 42'.

The connector 19 remains guided and locked in the support arm 13 of the cover lifting and pivoting device 11 after the cover 5 has been lowered again and thus separated from the connector 19.

The same functional features, which were described in detail in FIG. 4, apply to the further work operations, such as changing the cover and charging the furnace.

Claims (10)

1. Arc furnace with a furnace shell (1), a furnace cover (5) with a cover ring (4), and a cover-lifting and pivoting device (11), a cover hole (33) for drawing off the flue gas from the furnace interior being made in the furnace cover (5), and a flue-gas extraction connection piece (19) being located above the cover hole (33) for conveying the flue gases further on, characterised in that the connection piece (19) is supported on the furnace-cover ring (4).

2. Arc furnace according to Claim 1, characterised in that the connection piece (19) is provided with a guide arrangement (21, 38 ; 47, 47') which interacts with the cover-lifting and pivoting device (11), in such a way that the connection piece (19) is guided during lifting and supported during the tilting of the furnace.

3. Arc furnace according to Claim 2. characterised in that the guide arrangement (21, 38) contains, on the one hand, at least one guide rail (21) extending in the lifting direction of the furnace cover (5) and, on the other hand, at least one pair of guide rollers (38).

4. Arc furnace according to Claim 3, characterised in that the guide rail (21) is guided between two guide rollers (38).

5. Arc furnace according to one of Claims 2 to 4, characterised in that the guide rail (21) is connected firmly to the supporting arm (13) of the cover-lifting device (11), and in that the guide rollers (38) are connected firmly to the connection piece (19).

6. Arc furnace according to one of Claims 2 to 4, characterised in that the guide rial (21) is connected firmly to the connection piece (19), and in that the guide rollers (38) are connected firmly to the supporting arm (13) of the cover-lifting device (11).

7. Arc furnace according to Claim 2, characterised in that the guide arrangement (47, 47') contains at least one pair of guide levers (47, 47') which are articulated, by means of ends extending in the same direction, to the supporting arm (13) of the cover-lifting device (11) and, by means of the other ends, to the connection piece (19), and the connection piece (19) is supported on the cover ring (4) via at least one further lever (44).

8. Arc furnace according to Claim 7, characterised in that the guide levers (47,47') are of equal length and are arranged parallel to one another.

9. Arc furnace according to one of Claims 2 to 8, characterised in that the guide arrangement (21, 38 ; 47, 47') incorporates a retention device (39, 42') for securing the connection piece (19) in the lifted position.

10. Arc furnace according to one or more of Claims 2 to 9, characterised in that the guide arrangement (21, 38 ; 47, 47') and/or the retention device (39, 42') are arranged symmetrically on both sides of the connection piece (19).

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