AU644694B2 - Apparatus and method for delivering inert gas into a molten metal transportation vessel - Google Patents

Description

OPI DATE 90/05S/92 APPLN. I D 86428 q1

PCT

INTERNATIG AOJP DATE 25/06/92 PCT NUMBER PCT/DE91/00814 (51) Internationale Patentklassifikation 5 (11) Internationale Verbffentlichungsnummer: WO 92/07099 C21C 1/06, C21B 7/14 Al (43) InternationalesI B08B 15/02 Verdffentlichungsdatum: 30. April 1992 (30.04.92, (21) Internationales Aktenzeichen: PCT/DE91/00814 (22) Internationales Anmeldedatum: 15. Oktober 1991 (15.10.91) Prloritlitsdaten: P 40 33 482.1 20. Oktober 1990 (20.10.90) DE (74) Anwalt: BRUNDERT, Harald; Kldckner-Werke AG, Patentabteilung, Kltbcknerstra~e 29, D-4 100 Duisburg I

(DE).

(81) Bestimmungsstaaten: AT (europdisches Patent), AU, BE (europfiisches Patent), BG, BR, CA, CH (europtiisches Patent), DE (europaisches Patent), DK (europtiisches Patent), ES (europ~isches Patent), F1, FR (europtiisches Patent), GB (europaisches Patent), GR (europllisches Patent), HU, IT (europtlisches Patent), JP, KR, LU (europtlisches Patent), NL (europtiisches Patent), PL, RO, SE (europliisches Patent), 513+ ,US.

Verdffentlicht Mit internalionalem Recherchenberich.

Anmielder OJir alle Bestimmungsstaarin ausser US): KLOCK- NER STAHL GMBH [DE/DEJ; Kl6cknerstrage 29, D- 4100 Duisburg 1 (DE).

(72) Erfinder; und Erfinder/Anmelder (nur fir US) DE HAAS, Hans [DE/ DE]; Imn Heideweg 41, D-2804 Lilienthal- Kiostermoor ULRICH, Klaus [DE/DE]; Eislebener Stralle 41, D-2800 Bremen tDE). GROTZMACHER, Klaus [DE/ DE]; Friedrich-IMLler-Str. 16, D-2800 Bremen (DE).

KRAUSE, Erha-,d [DE/DE]; Habichthorsterstr. 8, D- 2863 Ritterhud(, MOHNKERN, Horstmar [DE/ DEJ; Am M~r'khof 16, D-2863 Ritterhude LO- WENSTEIN, .Aanfred [DE/DEl; Mozartstrage 11, D- 2863 Ritterhude VOSS, Manfred [DE/DE]; Gliocksburgerstr. 101, D-2800 Bremen I WITT, Joachim [DE/DE]; Klemperhagen 44, D-2863 Ritterhude HAMMER, Uwe IDE/DE]; Solothurnerstr. D-2800 Bremen 41 (DE).

644 4'~i (54) Title: .]"Apparatus and method for delivering inert gis into a molten metal transportation vessel".

(54) Bezeichnung: VORRICHTUNG ZUM INERTISIEREN VON ABGIESSGEFASSEN SCHMELZFLOSSIGEN METALLEN FO2R DEN TRANSPORT VON (57) Abstract AAjj A device for rendering inert casting vessels for transporting molten metals, such as movable ladles or transfer ladles, rinces with an inert gas the cavity of each casting vessel located under the outlet opening of a transfer station, before and during inflow of the molten metal, so that all contact is avoided between the surface of the molten metal in the casting vessel and the oxygen in the atmosphere. In the area of each outlet opening 8) of a transfer station is arranged at least an inert gas blast pipe (23, 24), so that it never intercepts the stream of inflowing molten metal, that it is located outside the clearance profile of the casting vessel (10, 11) at least during its approach and departure, that ends before the opening (12) of the latter and that generates at its end facing the casting vessel (10, 11) an inert gas stream that enters the cavity (31) of the casting vessel (10, 11) next to the earn of molten metal at an angle a in relation to the vertical of more than 0' but less than 900.

le Rflckseite (57) Zusammenfassung Die Erfindung betrifft eine Vorrichtung zum Inertisieren von Abgieggefi1Een fflr den Transport von schmelzfliissigen Metallen, beispielsweise von verfahrbaren Pfannen oder Torpedogefgaen, die den Hafilraumn jedes unter einer Auslauf6ffnung einer Obergabestation positionierten AbgieLggefages sowohi vor dem Einlag als auch wahrend des Einlaufens des schmelzfliissigen Metalls mit einem Inertgas derart spfllt, dag zwischen der schmelzflossigen Metal loberflache im Abgieggefaa und dem Luftsauerstoff kein Kontakt entsteht, wobei in der Umngebung jeder Auslauf6ffnung 8) einer Obergabestation (2) mindestens emn Inertgas-Blasrohr (23, 24) derart angeordnet ist, da es in keinem Fall den Strahl des einlaufenden schmelzfitissigen Metalls schneidet, zumnindest. wiihrend der An- und Abfahrt des Abgieggeffies (10, 11) sich augerhalb von dessen Freiraumprofil befindet und vor dessen Offnung (12) endet und an seinem dem AbgieggefAR (10, 11) zugewandten Ende einen inertgasstrahl erzeugt, der unter einem Winkel a gegen die Vertikale, der gr8ger als 00 und kleiner als ein rechter Winkel ist, neben demn Strahl des schmelzflflssigen Metalls in den Hohlraumn (3 1) des Abgiefggefdges (10, 11 eintritt.

BESTIMMUNGEN DER "SU" Die Bestimmung der "SU" hat Wiz-kung in der Russischien Fdideration. Es ist noch nicht bekannt, ob soiche Bestimmungen in anderen Stamten der ehemnaligen Sowjflun.*n Wirkung haben.

LEDIGLICH ZUR INFORMATION Code, die zur Identifizierung von PCT-Vertragsstaacen auf den Kopfb~gen der Schriften, die internationale Anmeldungen gemnfss demn PCT verbffentlichen.

0sterreich Australiun Barhadoi Burkina Pawi Bulgarian Benin Bra sillen Kadu Zsentrzilu Afrikunishu Re~pubi~k Kongo Sichwui,.

('6te dvoire Dutschland Dilncmark Spaniun Finniand Frankrih Gabon Vercinigtas Kianigruich Guinea Griechunland Ungarn Itlnic"~ Japan Demokratische Volksrepuhlik Korea Republik Korea Liechtenstein Sri Lanka Lux~emburg Monac~o Mad agaskar Mali Moingulci Mauritanian Malawi Nicdtariande Norwcgtun Polen Rumfifliun Sudan Szhweden ScLgal Soviet Union Tsc had Togo Vmrinigte Statn von Amerikla -lA- The present invention relates to an apparatus and method for delivering inert gas into a molten metal transportation vessel.

A generic apparatus of this type is known from Patent Specification DE-PS 39 03 444, in which there is disclosed an apparatus which pushes inert gas through a flexible supply line in the vicinity of a casting vessel positioned below an outlet opening of a transfer station, through a separable coupling adjoining the latter, through a fixed line system adjoining the latter on the outer surface of the casting vessel and through one or more inlet openings in the wall of the casting vessel into the interior of this casting vessel, with the inlet opening(s) being arranged in the wall of the casting, vessel such that they are always above the maximum liquid level in the casting vessel and below the upper edge of the opening of the casting vessel.

In the case of this above-cited apparatus, it has however proved disadvantageous that, first of all, all the casting vessels which are to be used in a smelting operation for transport of the described type have to be provided with the above-described inlet openings, in particular it having to be taken into account that these inlet openings must pass through both the outer iron casing and the conventionally present refractory lining of each casting vessel, which from the outset implies that the inlet openings may in each .base only be made in the casting vessel by means of complicated subsequent work after the conventional production thereof. Even in the case of relining a casting vessel as a result of wear, the final remaking of.the inlet openings can only t" be carried out after all the other repair measures by means of complicated subsequent work. Furthermore, in the proposed making of the inlet openings, the possibility can never be reliably ruled out that molten metal or slag might pass into the inlet openings despite the predetermined spacing between the maximum liquid level and the position of the inlet openings during pouring of the molten metal into a casting vessel or during its transport in such a casting vessel, and that these inlet openings are then blocked up, which again results in complicated maintenance work.

Moreover, it proves disadvantageous in the disclosed apparatus that coupling and uncoupling of the flexible inert gas supply line to the fixed line system on the casting vessel requires additional manipulations which are normally to be carried out by hand and whereof the actual carrying out, for example when the casting vessels are positioned below a casting deck, although control of applying inert gas to the supply line conventionally takes place on or above the casting deck, can only be monitored with additional technical expenditure, the omission of which can lead to serious damage to the entire apparatus and to undesired outward flow of inert gas.

The above-mentioned disadvantages consequently result on the one hand in economically undesirable increased investment and/or maintenance costs and on the other hand in additional safety risks.

The object of the present invention is thus to further develop the previously known generic apparatus for making inert casting vessels for the transport of molten metals in such a way that it is possible to dispense with incorporating the casting vessels in the actual apparatus for making them inert and that the inert gas outlet opening(s) of each apparatus is acted upon through one or more permanently adjoining supply lines with inert gas, it being possible to monitor and bring about this action from a ingle predetermined place and to keep the investment and maintenance costs to as low a level as possible.

In a first aspect, the present invention provides an apparatus for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel: the apparatus comprising an inert gas blowing tube having an inlet end connected to a supply of inert gas and an outlet end arranged to deliver a jet of inert gas downwardly into the vessel in the proximity of the stre:am of molten metal at an angle greater than 00 and less than 900 with respect to vertical.

In a second aspect, the present invention provides a method for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel, the method comprising delivering a jet of inert gas downwardly into the vessel, in the proximity of the stream of molten metal, at an angle greater than 00 and less than 900 with respect to vertical, whereby contact between the surface of the molten metal and atmospheric oxygen is substantially prevented.

In preferred embodiments of the invention, it proves particularly advantageous that there is arranged in the environs of each outlet opening of the transfer station at least one inert gas blowing tube in such a way that it under no circumstances intersects the stream of molten metal, is located, at least during approach and departure of the vessel, outside the clearance profile thereof and ends before the opening thereof and produces, at its outlet end, an inert gas jet which enters the hollow space of the vessel at an angle u to the vertical which is larger than 00 and smaller than 900 in the proximity of the stream molten metal, because in this manner, instead of comprehensive, in some cases even repeated subsequent work on a plurality of casting vessels only a single installation of a suitable inert gas blowing tube P21949B429 -4arrangement in the environs of each outlet opening is necessary. Because of the arrangement of each inert gas blowing tube outside the stream of molten metal, advantageously, no expensive high-melting materials but only inexpensive commercially available steel tubes can be used and also no preventative measures have to be taken against possible spraying of the stream of molten metal onto parts of the inert gas blowing tubes with the consequence of an increase in size in the jet surface, which would be undesired with respect to possible chemical reactions. Furthermore, because of the arrangement of each inert gas blowing tube outside the clearance profile of the vessel, at least during the approach and departure thereof to and from the outlet opening, advantageously no additional manipulations of the vessel are r'quired. Where a casting deck or a corresponding screen between the space of supplying the molten metal to the transfer station and the space of the casting vessels is present it is possible to control and monitor the application of inert gas to the inert gas blowing tubes from one of these spaces, preferably from that line supplying the molten metal to the transfer station. Moreover, the arrangement of each inert gas blowing tube to produce an inert gas jet which enters the hollow space of the vessel at an angle a to the vertical in the proximity of the stream of molten metal advantageously produces the surprising effect that, at least for a suitable region of the angle a between 00 and 900 and for a correspondingly suitable region of delivery the inert gas between the stream of molten metal and the wall of the vessel, despite the spatial distance between the outlet end of the inert gas blowing tube and the hollow space of the vessel, rendering the vessel inert succeeds reliably. Even a single inert gas blowing tube may be adequate to ensure constant filling of the respectively present hollow space of the vessel with inert gas both prior to and during introduction of the stream of molten metal into the vessel because of the gas

I"

P21949B/429 4A flow which arises. It is furthermore to be regarded as advantageous in the above-described overall arrangement that each inert gas blowing tube may also be provided with a permanently adjoining, fixedly positioned supply line arrangement to be regulated by means of known control elements such as valve arrangements of known type, because such supply line arrangements are simple to monitor and to maintain.

In a preferred embodiment of the apparatus according to the invention, it is very advantageous to install inert gas blowing tubes of invariable length, because these incur particularly low investment and maintenance costs, where adequate filling of the hollow space of the vessel can be guaranteed also when producing the desired inert gas jet above the opening of the casting vessel.

In an alternative preferred embodiment of the apparatus according to the invention, on the other hand, it proves advantageous to construct each inert gas blowing tube, at least at its outlet end facing the vessel, as a telescopic tube which can be pushed in and out, because, although this increases the investment and P21949B/429 maintenance costs, in particular cases it permits a useful influencing of the gas flow in the vessel by partly inserting the inert, gas blowing tube in the opening of the vessel, it being possible to control and monitor such a telescope-type movement of the inert gas blowing tube without difficulties even from a control stand from which the outlet end of the inert gas blowing tube facing the vessel cannot be seen.

A further preferred embodiment of the apparatus according to the invention is characterized in that noise dampers of known type are mounted on the outlet ends of the inert gas blowing tubes facing the vessel, because such noise dampers may be assembled on the outlet ends in a simple manner and the noise level in the environs of the transfer station can then be considerably reduced for those working there.

If the apparatus according to the invention is one at a transfer station on the casting deck of a blast furnace, the inert gas blowing tubes may in a quite particularly advantageous manner be installed in the viewing tubes normally available in the casting deck for observiing the liquid level in the respective casting vessel at least over a substantial part of its length because this avoids having to carry onat additional measures in the casting deck from the outset, whic:h further reduces the investment costs and moreover permits on the one hand a constant visual check of the inert gas blowing tubes and on the other hand a cost-effective carrying out of any maintenance work required on these inert gas blowing tubes.

In a further advantageous construction of the above-mentioned embodiment of the present invention, at least one further inert gas blowing tube projects into the inlet region of each viewing tube on the casting deck side and serves to produce in the respective viewing tube a dynamic pressur6 in opposition to the chimney effect of each viewing tube as regards the hot gases out of the respective casting vessel, and this has the effect that on the one hand the necessary protection against the said hot gases of those working at the casting deck which hitherto was normally effected by means of a dynamic pressure developed from compressed air in the viewing tube is further provided and on the other hand additional oxygen-containing gas mixture, such as for example compressed air, can under no circumstances pass through the viewing tube into the opening region of the respective casting vessel and there, by causing eddies with the inert gas cuztain surrounding the jet'of molten metal or with the above-described inert gas jet directed into the casting vessel, transport oxygen t. the molten metal in the casting vessel.

Here, it proves particularly advantageous if not only the inert gas blowing tubes for providing gas to the casting vessels but also the additional inert' gat' blowing tubes for building up a dynamic pressure in 'the viewing tubes are provided with a respective separately actuable control element, because in this manner the inert gas consumption in the pertinent region of the overall apparatus can be matched in optimum manner to the operating requirements i.e. a minimum of inert gas consumption with maximum operational reliability.

Suitable inert gases for operation of the apparatus according to the invention and for use in the method according to the invention are advantageously in particular nitrogen or the off gases of complete combustion of a suitable fuel, for example natural gas or mineral oil.

An example embodiment of the apparatus according to the invention is illustrated in the drawing: The single figure of the drawing shows first of all a section through the casting deck 1 of a blast furnace having a transfer station 2 which is arranged in a depression of the casting deck 1 and substantially comprises: a largely gas-tight housing 3 which is in two parts and is seated on the casting deck 1 and whereof 'the upper part is constructed in the case illustrated as a traversable cover; a pivotal channel 4 connected to transport channels (not visible in the present illustration) on the casting deck 1; distributor channels 5, 6; and outlet openings 7, 8. The transfer station 2 guides a jet 9 of molten metal by means of the pivotal channel 4 alternately into casting vessels 10 and 11, for example traversable ladles or torpedo vessels which are set down with their openings 12 below the outlet openings 7, 8. The interior of the transfer station 2, to prevent the production of metal and other oxides at the surface of the molten metal, is acted upon by means of a main supply line 13, a distributor station 14, a supply line 15 and outlet nozzles 16 with an inert gas, for example nitrogen or off gas from complete combustion of natural gas or mineral oil, it being possible for cooling of the pivotal channel 4 to take place at the same time. With a similar aim in view, the outlet openings 7, 8 are provided with annular nozzles 17, 18 which, during the transfer of molten metal to a casting vessel 10, 11, are acted upon by inert gas through supply lines 19, 19' and thus form a tubular inert gas curtain 20 around the jet 9, which extends from the exit of the respective outlet openings 7, 8 at least as far as the opening 12 of the respective casting vessel 10, 11.

In order also to prevent the production of metal and other oxides at the surface of the molten metal, including the lower end of the jet 9, in the interior of the casting vessels 10, 11, there is arranged in each viewing tube 21, 22 let into the casting deck 1 the substantial longitudinal section of a respective inert gas blowing tube 23, 24, with each inert gas blowing tube 23, 24 being acted upon by inert gas through supply lines 25, 26 from the distributor station 14 in conjunction with controllable and regulable valve arrangements 27, 28 of known type, in t!he case illustrated installed outside the respective viewing tube 21, 22.

At the end of each inert gas blowing tube 23, 24 facing the casting vessel 10, 11, the inert gas exits through a noise damper 29, 30 of known type as a directed jet which enters the hollow space 31 of the casting vessel 10, 11 at a finite angle a to the vertical which is larger than 00 and smaller than a right angle, next to the jet 9 of molten material, and there, because of the gas flow produced, displaces or keeps away air oxygen from the hollow space 31, displacement of the air oxygen already being initiated before the start of letting molten metal into the casting vessel 10, 11.

The use of noise dampers 29, 30 is also a protective measure which may be carried out in simple manner in conjunction with the use of inert gas blowing tubes 23, 24 on behalf of those working in the environs of the transfer station 2, as is the installation respectively of a second short inert gas blowing tube 32, 33 in the inlet regions of the viewing tubes 21, 22 on the casting deck side, and these are also acted upon by inert gas from the distributor station 14 through the supply lines 25, 26, which may however be controlled and regulated by means of separate valve arrangements 34, 35 independently of the inert gas blowing tubes 23, 2f. Normally, during the entire operating time of the transfer station 2 they blow inert gas into the ends of the viewing tubes 21, 22 remote from the casting vessels 10, 11 in order to produce therein a sufficient dynamic pressure to prevent the chimney action of the viewing tubes 21, 22 as regards the hot gases out of the casting vessels 10, 11 or out of the environs thereof, which could otherwise become a safety risk for those working on the casting deck 1 without it being possible for this development of a dynamic pressure to give rise to the danger of additional oxygen-containing gas mixture for example compressed air in any way passing into the opening region of each casting vessel 10, 11 and there, as a result of eddies with the inert gas curtain 20 surrounding the jet 9 of molten metal or with the inert gas jet produced by the inert gas blowing tubes 23, 24 oxygen being transported to the molten metal in the casting vessel 10, 11.

As the inert gas for use in the apparatus according to the invention, which as regards its concrete execution is of course not restricted to the example embodiment illustrated, in particular nitrogen or the off gases of complete combustion of natural gas or mineral oil can be used.

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List of reference numerals 1 2 3 4 7, 9 12 13 14 16 17, 21, 23, 27, 29, 31 11 19, 19', 25, 26 18 22 24, 32, 33 28, 34, 35 30 Casting deck Transfer station Housing Pivotal channel Distributor channels Outlet openings Jet of molten metal Casting vessels Openings of the casting vessels Main supply line for inert gas Distributor station Supply lines Outlet nozzles Annular nozzles Tubular inert gas curtain Viewing tubes InTrt gas blowing tubes Valve arrangements Noise dampers Hollow space of the casting vessel IwS ,j 7c.: 4.)

Claims (18)

1. An apparatus for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel, the apparatus comprising an inert gas blowing tube having an inlet end connected to a supply of inert gas and an outlet end arranged to deliver a jet of inert gas downwardly into the vessel in the proximity of the stream of mclten metal at an angle greater than 00 and less than 900 with respect to vertical.

2. An apparatus as claimed in claim 1 wherein the inert gas blowing tube is of invariable length and is positioned firstly, to not intersect the stream of molten metal introduced into the vessel from the transfer station and secondly, to not impede approach and departure of the vessel below the transfer station.

3. An apparatus as claimed in claim 1 wherein the inert gas blowing tube is of variable length and, in use, is positioned firstly, to not intersect the stream of molten metal introduced into the vessel from the transfer station and secondly, tn not impede approach and departure of the vessel below the transfer station.

4. An apparatus as claimed in claim 3 wherein the inert gas blowing tube is a telescopic tube.

An apparatus as claimed in any one of the preceding claims wherein a noise damper is located at the outlet end of the inert gas blowing tube.

6. An apparatus as claimed in any one of the preceding claims wherein at least a portion of the inert gas blowing tube is located within a viewing tube arranged to allow observation of molten metal within the vessel.

7. An apparatus as claimed in claim 6 wherein the viewing tube is arranged to allow observation of mrolten metal within the vessel from a casting deck.

8. An apparatus as claimed in claim 6 or claim 7 wherein the viewing tube is arranged to receive a supply 11 of inert gas whereby a dynamic pressure of inert gas within the viewing tube can be generated in opposition to any gasses drawn into the viewing tube from the vessel.

9. An apparatus as claimed in any one of the preceding claims wherein the supply of inert gas comprises a supply line and a valve arrangement for controlling supply of inert gas to the inert gas blowing tube.

An apparatus as claimed in claim 9 wherein there are a plurality of inert gas blowing tubes and a corresponding plurality of supply lines and valve arrangements and wherein the supply lines are connected to an inert gas distributor.

11. An apparatus as claimed in claim 9 wherein the supply line and the valve arrangement are located on or above a casting deck.

12. An apparatus as claimed in claim 10 wherein the supply lines, the valve arrangements and the inert gas distributor as located on or above a casting deck.

13. An apparatus for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel, the apparatus being substantially as herein described with reference to the accompanying drawing.

14. A method for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel, the method comprising delivering a jet of inert gas downwardly into the vessel, in the proximity of the stream of molten metal, at an angle greater than 00 and less than 900 with respect to vertical, whereby contact between the surface of the molten metal and atmospheric oxygen is substantially prevented.

A method as claimed in claim 14 wherein the inert gas is an off gas of complete combustion of a fuel. 'P21949B/429 12

16. A method as claimed in claim 15 wherein the fuel is natural gas or mineral oil.

17. A method as claimed in claim 14 wherein the inert gas is nitrogen.

18. A method for delivering inert gas into a molten metal transportation vessel prior to and/or during introduction of a stream of molten metal into the vessel from an outlet opening of a transfer station located above the vessel, the method being substantially as herein described with reference to the accompanying drawing. Dated this 14th day of October 1993 KLOCKNER STHAL GmbH By its Patent Attorneys 1 GRIFFITH HACK CO. Kl6ckner Stahl GmbH Kl6cknerstraBe 29, 4100 Duisburg 1 'Apparatus and method for delivering inert gas into a molten metal transportation vessel". Abstract The invention relates to an apparatus for making inert casting vessels for the transport of molten metals, for example traversable ladles or torpedo vessels, which flushes with an inert gas the hollow space of each casting vessel positioned below an outlet opening of a transfer station both before letting in and also while the molten metal runs in, in such a way that no contact is produced between the molten metal surface and the casting vessel and the air oxygen, at least one inert gas blowing tube (23, 24) being arranged in the environs of each outlet opening 8) of a transfer station in such a way that it under no circumstances intersects the jet of molten metal running in, is located, at least during the approach and departure of the casting vessel (10, 11), outside the clearance profile thereof and ends before the opening (12) thereof and produces, at its end facing the casting vessel (10, 11), an inert gas jet which enters the hollow space (31) of the casting vessel 11) at an angle a to the vertical which is larger than 00 and smaller than a right angle, next to the jet of the molten metal. See Fig. i.