EP2217732B1 - Device for secondary and vacuum metallurgical treatment of liquid steel - Google Patents

Description

The invention relates to a device for secondary and vacuum metallurgical treatment of liquid steel, comprising a vacuum vessel, such as an RH, VD or VOD container, which is sealed for the vacuum process with a raised and lowered lid and / or Is connected to a sealed, further vacuum line is.

Such vacuum degassing with the mentioned types of containers are well known and allow a significant reduction in gas and carbon content after short treatment times, even with significant melt sizes. The required vacuum is applied by powerful, multi-stage steam jet vacuum pumps, mechanical pump sets or combinations of steam jet and mechanical vacuum pumps. Therefore, the seals used in these, for example, the RH process or vacuum circulation degassing and Kesselentgasungsanlagen is of great importance. Because some air leaks or an air intake during the vacuum process affect the economic operation of the system.

The DE 36 09 783 A1 discloses a device for secondary and vacuum metallurgical treatment of liquid steel, which can be closed sealed with a liftable and lowerable lid. Around the circumference at the upper end of the vacuum vessel, a sealing means is arranged and the lid is formed with a überstülpbaren collar.

The US 6,331,269 B1 relates to a vacuum pipe for connecting suction pipes of portable containers for the vacuum treatment of metallic materials, in particular steel. A sealing means, ie an inflatable, tubular sealing ring is arranged around the circumference of the upper pipeline, and a connecting end of the continuing vacuum pipeline engages in the sealing ring.

The DE 281501131 relates to a sealing device for vacuum systems. The system contains a vessel to be evacuated and a pressure-tight connectable raised and lowered lid. On the outer peripheral side of the lid, a heat-resistant, elastic tubular body is arranged, which is inserted in an approximately U-shaped peripheral flange at the upper end of the vessel. The tubular body is inflatable by means of compressed air.

For sealing the lowerable on a vacuum vessel lid, it is known, the seams or mating surfaces with flanges of suitable shape, eg formed therein sealing grooves, form and insert a full seal, hose seal, with or without sheathing, or the like for sealing. Although the flanges are provided with water cooling, the seal has only a short service life due to overheating, but also mechanical damage, hardening and acid attack. The seal change is also awkward.

An insufficiently tight seal may not necessarily be detected prior to the start of the process, so that as a consequence the vacuum necessary for the successful process may not be achieved. In order to keep such disturbances of the production process low, the suction power of the vacuum pumps is usually designed taking into account a larger leakage, which in turn increases the investment costs and the operating costs.

The invention is therefore based on the object to provide an improved seal in a device of the type mentioned, with which can avoid the disadvantages mentioned.

This object is achieved in that around the circumference at the upper end of the vacuum vessel and / or the vacuum pipe, a sealant is arranged and the lid and / or a terminal end of the continuing vacuum pipe is formed with a slip-on collar over the sealant. Here, two parallel and spaced from each other circumferentially arranged sealing means are provided, wherein a negative pressure generating suction device can be connected to the enclosed after the slipping of the lid annulus between the two sealing means. This makes it possible to ensure that the seal is no longer exposed to directly high thermal load due to heat radiation. In addition, the seal lies in a space protected from the slipped-over collar and can be preserved almost indefinitely, because even falling or dripping bears or liquid steel can no longer reach the seal. At the sealing point, no flanges are required, as well as their mechanical processing and a water cooling deleted.

Another significant advantage of the sealing concept is that a spatially and temporally separation of the functions "mechanical merging of the vacuum vessel and lid" and "vacuum-tight closure of the parts" takes place by the sealing means arranged according to the invention on the outer vessel or pipe wall.

A preferred embodiment of the invention provides that the sealing means placed annularly around the vacuum vessel and / or the connection end of the vacuum pipeline is radially expandable and thus can be pressed against the collar. In a preferred embodiment, this is done by means of an inflatable seal or a seal which can be pressed by a separate inflatable ring body to the collar. This results in a further optimized sealing, because with the inflation or -wide, the seal adapts automatically to any production-related unevenness of the enclosing surfaces of the cover collar and the vacuum vessel and / or the vacuum pipe.

It is proposed according to the invention that the sealing means can be connected to a pressure medium supply. As a result, the seal wear can be further reduced. The pressure medium supply can be switched on or controlled only when the lid has lowered into its final position or the sub-pipe pieces of the continuing vacuum pipeline have reached their Endfügeposition and the sealing function is required. When opening the vessel or lifting the lid and / or opening the vacuum pipe or removing their part pipe pieces from each other, the seal can be relieved or -spannt accordingly.

Advantageously, the invention can also be used for the ventilation of the vacuum vessel after the vacuum treatment. For this purpose, the seal is relaxed and vented the vacuum vessel over the forming annular gap.

According to the invention, two sealing means are arranged parallel to and spaced from each other circumferentially, wherein a negative pressure generating suction device can be connected to the enclosed after the slipping of the lid and / or joining the pipe sections of the continuing vacuum pipe annulus between the two sealing means. This allows one between the negative pressure inside the vacuum vessel and to generate the atmospheric pressure to the ambient negative pressure. As a result, an air leakage acting on the vacuum vessel interior, in particular in the low vacuum region, can be further reduced. The minimization of air leakage is of particular interest in systems with mechanical vacuum generators to limit the required extraction capacity. Furthermore, this allows the tightness of these sealant reliably and quickly check, regardless of the installed for the metallurgical process vacuum generator. Faults can be detected before the actual treatment begins, with a positive effect on the operational safety of the system.

Fig. 1

als Einzelheit einer Vakuum-Entgasungsanlage in einem Längsschnitt ein zum Stand der Technik zählendes, durch einen aufgesetzten Deckel abgedichtet verschlossenes Vakuumgefäß mit darin zuvor eingebrachter Schmelzenpfanne;

Fig. 2

in einer sehr schematischen Darstellung eine Abdichtung zwischen Vakuumgefäß und Deckel, in durchgezogenen Linien in der Betriebsposition und strichpunktiert mit abgehobenem Deckel dargestellt;

Fig. 3

als Einzelheit einen Querschnitt eines möglichen Dichtmittels bzw. einer Dichtung, das bzw. die radial aufblasbar ist, wie strichpunktiert angedeutet;

Fig. 4

als Einzelheit zwei erfindungsgemäß im parallelen Abstand voneinander angeordnete Dichtmittel mit an den zwischen den Dichtmitteln eingeschlossenen Ringraum angeschlossener Unterdruckerzeugungsvorrichtung, schematisch dargestellt; und

Fig. 5

eine Vakuumrohrleitungs-Anordnung, einerseits in gekoppelter Betriebslage und andererseits in entkoppelter Außenbetriebslage (vgl. die rechte Hälfte der Figur) dargestellt.

Further features and details of the invention will become apparent from the claims and the following description of illustrated in the drawings embodiments of the invention. Show it:

Fig. 1

as a detail of a vacuum degassing in a longitudinal section a counting of the prior art, sealed by an attached lid closed vacuum vessel with previously introduced melt pan;

Fig. 2

in a very schematic representation of a seal between the vacuum vessel and lid, shown in solid lines in the operating position and dash-dotted with lifted lid;

Fig. 3

as a detail, a cross section of a possible sealant or a seal which is radially inflatable, as indicated by dash-dotted lines;

Fig. 4

as a detail, two according to the invention arranged in parallel spaced sealant with the enclosed between the sealing means annulus connected vacuum generating device, shown schematically; and

Fig. 5

a vacuum piping arrangement, on the one hand in coupled operating position and on the other hand in decoupled external operating position (see the right half of the figure) shown.

The Fig. 1 shows a known type of vacuum degassing, in which in a vacuum vessel 1, a filled with liquid metal 2 melt pan 3 is set. The vacuum vessel 1 is sealed by a liftable and lowerable cover 4 with the interposition of an annular full seal 5. The full seal is received by sealing grooves which are incorporated in complementary flanges 6 and 7 on the one hand of the lid 4 and on the other hand of the vacuum vessel 1. The cover 4 is provided with connections 8 for supply lines 9 for the introduction of alloying materials and a centrally arranged oxygen lance 14.

This in Fig. 2 The sealing concept shown differs significantly from the known or conventional, the example of Fig. 1 above-described seal between flanges 6, 7 of the lid 4 and vacuum vessel 1 from. Because in the execution Fig. 2 the lid is no longer placed with a flange on a flange pad, but starting from the in Fig. 2 Dropped dashed, raised inoperative position of 104 'numbered lid lowered and placed over the vacuum vessel 100. The cover 104 is for this purpose formed with a downwardly bent, the vacuum vessel 100 cross collar 10.

The collar 10 of the over-pushed lid 104 settles on a sealing means 11 which is disposed at the upper end 12 just below the vessel opening around the circumference of the vacuum vessel 100. The ring around the circumference of the vacuum vessel 100 laid sealing means 11 is preferably designed as a radially expandable expandable seal 13, the or in the Fig. 3 shown configuration, but can also be designed arbitrarily tubular. By this sealing concept is advantageously a spatial and temporal separation of the functions "mechanical merging of vacuum vessel and lid" and "vacuum-tight closure of the parts".

If a pressure medium supply (not shown) connected after the slipping of the lid 104 and compressed air or the like is introduced into the cavity of the inflatable seal 13 expands the inflatable seal 13 radially (see Fig. 3 dash-dotted schematically drawn Aufweitposition 13 ') and presses against the inner wall of the collar 10 at. At the end of the vacuum treatment, the inflatable seal 13 is relieved or relaxed, so that the cover 104 without contact to the sealant 11 and the inflatable seal 13 in the inoperative position (see cover 104 'in Fig. 2 ) can be raised. Furthermore, the pressure medium supply can also be used for the ventilation of the vacuum vessel 1, to which the expansion seal 13 relaxes and the vacuum vessel 1 is vented through an annular gap thereby forming.

In the case of the inventive seal execution Fig. 4 two such sealing means or inflatable seals 13a, 13b arranged parallel and spaced from each other around the circumference of the vacuum vessel 100. After slipping over the lid 104 and widening of the inflatable seals 13a, 13b is located between the inflatable seals 13a, 13b of the collar 10 of the lid 104 and the outer wall of the vacuum vessel enclosed annular space 15 before. A suction device 16 connected to this annular space can generate a negative pressure between the negative pressure in the interior of the vacuum vessel 100 and the atmospheric pressure to the surroundings, which contributes to the reduction of air leaks.

The Fig. 5 shows a vacuum pipe 200, which is connected to the vacuum vessel (not shown here), of which two partial pipe sections 200 'and 200 "which can be coupled to one another can be seen.

Around the circumference at the connection end 212 of one partial tube section 200 "of the vacuum pipeline 200, a sealing means 211 is arranged, which is designed as a radially expandable inflatable seal 213. At the connection end 212 in alignment with the connection end 201 of the other partial tube section 200 'of the continuing vacuum pipeline 200 a collar 210 is formed which, when the two partial tube sections 200 'and 200 "are joined together, which abut one another here with the end faces of their tube ends, overlies the sealing means 211 and the inflatable seal 213.

Here, too, it is provided that compressed air or the like is introduced into the cavity of the inflatable seal 213 after the collar 210 has been slipped over or overlapped by means of a pressurized medium supply, so that the inflatable seal 213 expands radially (compare the illustration in the left-hand illustration of the Fig. 5 shown as a detail on an enlarged scale inflatable seal 213 with dash-dotted schematically widened position 213 ') and pressed against the inner wall of the collar 210. Upon completion of the vacuum treatment or a Durchleitvorganges by the vacuum tube 200, the bellows seal 213 is relieved or relaxed, so that the collar 210 can be moved without contact to the sealant 211 and the inflatable seal 213 in an inoperative position.

The coupling or decoupling of the partial pipe sections 200 'and 200 "of the vacuum pipeline 200 takes place here via a cylinder 214 and a compensator 215 which permits the movement or setting stroke and at the same time strains or stresses compensating, integrated in the partial pipe section 200'.

LIST OF REFERENCE NUMBERS

1

vacuum vessel

2

liquid metal

3

melting pan

4

cover

5

full seal

6

flange

7

flange

8th

Connection

9

supply

10

collar

11

sealant

12

Upper end of vessel

13; 13a, 13b

inflatable seal

14

oxygen lance

15

annulus

16

suction

100

vacuum vessel

104

cover

200

Vacuum manifolds

200 '

Partial pipe section (the vacuum pipeline)

200 '

Partial pipe section (the vacuum pipeline)

201

terminal end

210

collar

211

sealant

212

terminal end

213

inflatable seal

214

cylinder

215

compensator

Claims (3)

1. A device for the secondary and vacuum metallurgical treatment of liquid steel, comprising a vacuum vessel (1; 100) such as an RH-, VD- or VOD container, which can be closed in sealing manner for the vacuum process using a raisable and lowerable cover (4; 104) and/or is connected to a sealing forwarding vacuum pipe (200), wherein a sealing means (11; 13; 211; 213) is arranged around the circumference at the upper end (12; 212) of the vacuum vessel (100) and/or the vacuum pipe (200), and the cover (4; 104) and/or a connecting end (201; 212) of the forwarding vacuum pipe (200) is configured with a collar (10; 210) that can be folded over the sealing means (11; 13; 211; 213), characterised in that two sealing means (13a, 13b) are provided and extend around the circumference parallel and at a distance from one another, wherein a suction device (16) that generates a negative pressure can be connected to the annular space (15) that is enclosed between the two sealing means (11; 13) after the cover (104) has been turned up.
2. The device according to claim 1,
   characterized in that
   the sealing means (13; 213) placed in the manner of a ring around the vacuum vessel (100) and/or the vacuum pipe (200) can be pressed in radially expending manner against the collar.
3. The device according to claim 2,
   characterized in that
   the sealing means (13; 213) can be connected to a pressure medium supply.

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