WO1998004370A1

WO1998004370A1 - Shrouding means

Info

Publication number: WO1998004370A1
Application number: PCT/GB1997/001911
Authority: WO
Inventors: Ian Ellis
Original assignee: Foseco International Limited
Priority date: 1996-07-26
Filing date: 1997-07-15
Publication date: 1998-02-05
Also published as: AU3551497A; EP0914222A1; TW358047B; ATE190253T1; DE69701401D1; AR007971A1; EP0914222B1; GB9615765D0; ZA976433B

Abstract

A means to shroud molten metal flowing from an outlet in a molten metal handling vessel, comprises a tubular shroud (20) having an enlarged head portion (22) to be fixed to the underside of the vessel in correspondence with the outlet, and a sleeve or collar (10, 40) to fit over the tubular shroud, with one end (11, 41) of the sleeve or collar (10, 40) in contact with the enlarged head portion (22), the sleeve or collar (10, 40) having an inlet (12, 42) for gas and a gas conduit (13, 43) to lead the gas to the interior of the enlarged head portion (22) of the shroud (20). The vessel may be a ladle and the shrouding means may be fixed to the underside of the ladle or it may be fixed to the ladle via a slide gate valve.

Description

SHROUDtNG MEANS

This invention relates to a shrouding means to be attached to the underside of a molten metal handling vessel and is particularly concerned to provide an improved means of attaching a shroud to the vessel.

In the handling of molten metal, it is well known to protect the molten metal from air as the molten metal is poured from, e.g. a ladle, into another vessel below the ladle, e.g. a tundish in the continuous casting of steel. This is achieved by attaching a tube known as a shroud to the underside of the upper vessel to surround the outlet from that vessel. Various means of attachment of the shroud to the underside of the vessel have been proposed and it is also conventional practice to supply an inert gas, e.g. argon, to the shroud to prevent leakage of air into the shroud via, for example, the shroud/vessel underside interface.

The vessel, as indicated above, may be a ladle for steel and for convenience the invention will be more specifically described below with reference to a ladle for steel, although it will be appreciated that it is not intended to be limited thereto.

Access to the underside of a ladle and particularly to the ladle/shroud interface is very often restricted, which can render the provision of delivery means for inert gas to the interface difficult.

Conventional delivery means include:

i) a direct connection in the side of a flange on the ladle shroud, this leading to the internal bore of the shroud where the gas is distributed uniformly around the internal perimeter of the shroud by means of, for example, a permeable annular ring. n) a circular metal enclosure placed on the ladle shroud flange and through which the gas is distributed to the shroud/ladle interface

The present invention aims to provide an improved fixing means to attach the shroud to the e g ladle, which means provides an improved delivery means for the inert gas

Accordingly, the invention provides in one aspect a means to shroud molten metal flowing from an outlet in a molten metal handling vessel, the means comprising a tubular shroud having an enlarged head portion to be fixed to the underside of the vessel in correspondence with the outlet and a sleeve or collar to fit over the tubular shroud with one end of the sleeve or collar in contact with the enlarged head portion, the sleeve or collar having an inlet for gas and a gas conduit to lead the gas to the interior of the enlarged head portion of the shroud

The invention also provides in a second aspect a sleeve or collar for use in the shrouding means of the invention, the sleeve or collar having dimensions to be received over the tubular portion of a shroud and having an inlet for gas and a conduit attached to the sleeve or collar to deliver the gas to one end of the sleeve or collar, and means to attach the sleeve or collar to the shroud and/or to a molten metal handling vessel

The vessel is preferably a ladle and the shroud may be attached to the underside of the ladle via, for example, a conventional slide gate valve to control flow of molten metal from the ladle

The shroud may be fixed to the underside of the ladle or to the slide gate valve by any convenient means Such fixing means are well known in the art and do not form a part of the present invention The fixing means may be adapted so that the sleeve is attached to the ladle, the shroud then being held in place by its enlarged head portion resting on the upper perimeter of the sleeve

The upper end of the sleeve and the lower end of the head portion of the shroud may conveniently be provided with locating means, e g lugs on the one and holes in the other, to assist accurate location of the two together

The gas conduit in the sleeve may terminate in correspondence with a channel in the head portion of the shroud and/or with holes leading to the interface between the upper end of the enlarged head and the vessel or slide gate valve Alternatively or additionally, a perforated ring, e g of metal, may be attached to the outside of the sleeve at its upper end to assist delivery of the gas around the shroud

The gas inlet on the sleeve may conveniently be an annular protrusion on the external face of the sleeve for coupling to a gas line, e g a source of argon

The sleeve may be made of any suitable material, steel being preferred, and it may be re-usable

The ladle shroud may be made of any suitable refractory material, e g graphitised alumina conventionally used

The sleeve may, if necessary, be insulated internally with refractory heat-insulating material to reduce heat transfer through the sleeve or it may be cooled, e g by air or inert gas

The invention provides an improved shrouding means that can readily be used to replace existing systems and in which the accessibility of the delivery means for inert gas is improved Specific embodiments of the invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a diagrammatic illustration of a sleeve of the invention;

Figure 2 is a view in the direction of arrow A in Figure 1 ;

Figure 3 is a longitudinal section through the sleeve of Figure 1 ;

Figure 4 shows the sleeve of Figure 1 in position on a ladle shroud;

Figure 5 is a similar view to Figure 1 of a modified sleeve; and

Figure 6 is a view in the direction of arrow B in Figure 5.

In Figures 1 to 3 a steel sleeve 10 has an end ring 11 to be connected to the underside of the flanged enlarged head of a shroud. The sleeve has an inlet connector 12 for attachment to a source of inert gas.

The connector 12 leads to a pipe 13 running internally along the length of the sleeve to exit at its end 11 at an outlet 13A.

The sleeve has on its exterior adjacent the end remote from end 11 , two equi-spaced support blocks 14 which may be used, where desired, in robot attachment system (not shown). At end 11 , sleeve 10 has, also on its exterior, three equi-spaced location lugs 15 to assist location with a shroud.

In Figure 4 sleeve 10 is shown slid over the tubular length 21 of a shroud 20 until it meets the underside of the enlarged head 22 of the shroud. A fibre gasket 23 is positioned between the end 11 of sleeve 10 and the flanged underside of head 22, although it will be appreciated that other sealing means may be employed, if desired

The lugs 15 of sleeve 10 fit into corresponding holes 24 in the head of the shroud

Outlet 13A of the pipe 13 feeds into a channel 25 in the head 22 which in turn feeds to an annular recess 26 in the head

A meltable gasket 27, which is to seal between the head of the shroud and the underside of a ladle or slide gate valve (not shown) is shown positioned on the end of head 22 remote from sleeve 10

As shown in Figure 4, the sleeve 10 is provided with a fibre insulating sleeve 30

In Figures 5 and 6 sleeve 40 has an end ring 41 to be connected to the underside of the flanged enlarged head of a shroud (not shown) The sleeve has an inlet connector 42 for attachment to a source of inert gas The connector 42 leads to a pipe 43 running externally along the length of the sleeve towards end ring 41 Pipe 43 leads into a perforated annular ring 44 running around the exterior of the sleeve adjacent the end ring 41 As can be seen in Figure 6, the perforations 45 are in the surface of the ring 44 facing the end ring 41 whereby a shrouding of inert gas can be provided in the restricted area where the sleeve is attached to a ladle shroud

It will be appreciated that the precise means of delivery of inert gas into the head of the shroud may vary considerably For example, the head may contain an annular ring of permeable material into which the gas is fed via suitable holes and channels communicating with the outlet of the gas pipe in the sleeve The actual means of connection to the ladle may be any suitable means and are not specifically described here.

Claims

1 A means to shroud molten metal flowing from an outlet in a molten metal handling vessel, characterised in that the means comprises a tubular shroud (20) having an enlarged head portion (22) to be fixed to the underside of the vessel in correspondence with the outlet and a sleeve or collar (10, 40) to fit over the tubular shroud with one end (11 , 41) of the sleeve or collar (10, 40) in contact with the enlarged head portion (22), the sleeve or collar (10, 40) having an inlet (12, 42) for gas and a gas conduit (13, 43) to lead the gas to the interior of the enlarged head portion (22) of the shroud (20).

2. Shrouding means according to Claim 1 characterised in that the vessel is a ladle and the shroud (20) is fixed to the underside of the ladle.

3 Shrouding means according to Claim 1 characterised in that the vessel is a ladle and the shroud (20) is fixed to the ladle via a slide gate valve.

4 Shrouding means according to Claim 1 characterised in that the vessel is a ladle, the sleeve or collar (10, 40) is fixed to the ladle and the shroud (20) is held in place by its enlarged head portion (22) resting on the upper perimeter of the sleeve or collar (10, 40).

5 Shrouding means according to any one of Claim 1 to 4 characterised in that the upper end (1 1, 41) of the sleeve or collar (10, 40) and the lower end of the head portion (22) of the shroud (20) are provided with locating means.

6 Shrouding means according to Claim 5 characterised in that the locating means comprises lugs (15) on either the sleeve or collar (10, 40) or the shroud (20) and holes (24) in the other.

7. Shrouding means according to any one of Claims 1 to 6 characterised in that the gas conduit in the sleeve or collar (10, 40) terminates in correspondence with a channel (25) in the head portion (22) of the shroud (20).

8. Shrouding mean according to any one of Claims 1 to 7 characterised in that the gas conduit (13, 43) in the sleeve or collar (10, 40) terminates with holes leading to the interface between the upper end of the enlarged head (22) of the shroud (20) and the vessel or slide gate valve.

9. Shrouding means according to any one of Claims 1 to 8 characterised in that a perforated ring (44) is attached to the outside of the sleeve or collar (10, 40) at its upper end (11).

10. Shrouding means according to any one of Claims 1 to 9 characterised in that the gas inlet (12, 42) on the sleeve or collar (10, 40) is an annular protrusion (44) on the external face of the sleeve or collar (10,

40).

11. Shrouding means according to any one of Claims 1 to 10 characterised in that sleeve or collar (10, 40) is made of steel.

12. Shrouding means according to any one of Claims 1 to 11 characterised in that the shroud (20) is made of refractory material.

13. Shrouding means according to any one of Claims 1 to 12 characterised in that the sleeve or collar (10, 40) is insulated internally with refractory heat-insulating material.

14. A sleeve or collar (10, 40) for use in a shrouding means according to Claim 1 characterised in that the sleeve or collar (10, 40) has dimensions to be received over the tubular portion (21) of a shroud (20), an inlet (12, 42) for gas, a conduit (13, 43) attached to the sleeve or collar (10, 40) to

5 deliver gas to one end of the sleeve or collar (10, 40), and means to attach the sleeve or collar (10, 40) to the shroud (20) and/or to a molten metal handling vessel.

15. A sleeve or collar (10, 40) according to Claim 14 characterised in that the sleeve or collar (10, 40) has locating means for locating the sleeve o or collar (10, 40) on the shroud (20).

16. A sleeve or collar (10, 40) according to Claim 15 characterised in that the locating means comprises lugs (15) or holes.

17. A sleeve or collar (10, 40) according to any one of Claims 14 to 16 characterised in that the sleeve or collar (10, 40) has a perforated ring (44) 5 attached to its outside at its upper end (11 , 41).

18. A sleeve or collar (10, 40) according to any one of Claims 14 to 17 characterised in that the gas inlet (12, 42) is an annular protrusion on the external face of the sleeve or collar (10, 40).

19. A sleeve or collar (10, 40) according to any one of Claims 14 to 18 0 characterised in that the sleeve or collar (10, 40) is made of steel.

20. A sleeve or collar (10, 40) according to any one of Claims 14 to 19 characterised in that the sleeve or collar (10, 40) is insulated internally with refractory heat-insulating material.