EP2470678B1 - Device for degassing molten steel with an improved discharge nozzle - Google Patents

Device for degassing molten steel with an improved discharge nozzle Download PDF

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Publication number
EP2470678B1
EP2470678B1 EP10759802.1A EP10759802A EP2470678B1 EP 2470678 B1 EP2470678 B1 EP 2470678B1 EP 10759802 A EP10759802 A EP 10759802A EP 2470678 B1 EP2470678 B1 EP 2470678B1
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Prior art keywords
outlet nozzle
millimetres
spout
steel
melt
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German (de)
French (fr)
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EP2470678A1 (en
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Hans-Jürgen ODENTHAL
Dieter Tembergen
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SMS Group GmbH
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SMS Group GmbH
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
    • C22B9/055—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ while the metal is circulating, e.g. combined with filtration
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/10—Handling in a vacuum

Definitions

  • the present invention relates to a device for degassing a molten steel with an improved spout.
  • the present invention relates to a particular form of spout for avoiding dead water regions in a steel ladle.
  • the present invention further relates to a method of degassing the liquid steel with the improved spout.
  • the process for degassing liquid steel is an RH process (Ruhrstahl-Heraeus process).
  • RH process the liquid steel is conveyed from a ladle in a riser to an evacuation vessel.
  • a conveying gas, in particular argon is introduced into the riser above the steel bath level.
  • the injected into the riser through several nozzles argon stream breaks down into a variety of argon bubbles that rise in the immediate vicinity of the wall.
  • the conveyance of the liquid steel is made possible by the volume increase by argon in the riser and by the pressure difference between the external air pressure and the negative pressure in the evacuation vessel.
  • the argon bubbles entrain the melt and ensure a uniform melt circulation.
  • the partial pressure is lowered at the same time and the decarburization reaction is accelerated.
  • the steel sucked into the evacuation vessel is sprayed. This results in a strong increase in surface area and good degassing of the liquid steel.
  • Oxygen which is simultaneously introduced throughout the treatment period and replenished, among other things, from the slag, leads to the formation of carbon monoxide (CO). CO gas in the vacuum vessel, resulting in the desired decarburization is reached.
  • the fine decarburization can be optimized to the lowest possible values by additionally injected oxygen. A high rotational speed of the melt and thus an increase in the flow of carrier gas and an increase in the diameter of the bowl of the vacuum system lead to a faster decarburization process.
  • Out DE 19511640 C1 is a trunk for a degassing vessel with a refractory lining and arranged therein a gas purging device with multiple channels known.
  • the channels are distributed over the circumference of the trunk and extend, based on the central longitudinal axis of the trunk, through the refractory lining in the radial direction.
  • the channels can be connected to at least one gas supply line on the outside.
  • the channels are circumferentially arranged to form a nearly continuous gas curtain along the inner wall of the trunk in close succession.
  • a steady stream of liquid steel is reached into the vacuum vessel.
  • the distributed over the entire circumference, preferably fine-bubble gas supply allows a particularly fine distribution of the treatment gas at the same time greatly increased reaction volume between the treatment gas and molten steel. In this way, a higher and faster decarburization performance can be achieved, so that smaller amounts of reduction media are necessary.
  • Out JP 6299227 A there is known a method of producing very low carbon steel with a degassing apparatus, wherein the inlet trunk is positioned so that the distance between the axis of the inlet trunk and the axis of the metal bath is at least 10% of the inner diameter of the metal bath.
  • Out JP 1198418 A a device and a method for the vacuum degassing of molten steel is known, wherein both introduced into the inlet and outlet spout gas and alternately the function of the trunk can be changed.
  • Out JP 3271315 A is a RH vacuum decarburization of stainless steel known, the degassing and decarburization is achieved in a short time and the loss of chromium is reduced. The result is achieved by using low silicon steel and repeated degassing and decarburization with an RH vacuum vessel.
  • JP 2173204 A For example, a vacuum vessel for an RH degassing apparatus is known wherein an ultrasonic oscillator is installed at a contact point with the liquid steel in the vacuum vessel to destroy bubbles generated by the gas injection and to improve the reaction surface on the phase reaction.
  • Out JP 3107412 A discloses a method of producing very low carbon steel, wherein argon is injected at the same time during decarburization into both the inlet and outlet tubes.
  • JP 01275715 a degassing device is described, in whose outlet pipe gas supply openings are provided, by means of which an inert gas in the Molten steel can be blown in order to prevent the ingress of slag into the molten steel.
  • a dead water area is usually formed between the spout and the refractory wall of the ladle. Due to the downward stream of melt from the spout little material from the immediate vicinity is sucked in around the spout. As a result, the overall carbon concentration remains high due to the delayed homogenization. The dead water area mixes poorly with the rest of the melt because the average flow rate is low. Because of the low mass, momentum and energy exchange between the high carbon concentration dead water zone and the remainder of the low carbon concentration melt, the ladle melt often has to be recirculated until the desired final carbon content is achieved. Since the ladle melt has to circulate frequently, the treatment time is high.
  • the invention has for its object to provide an apparatus for degassing a molten steel with an improved spout, which reduces the formation of dead water areas.
  • the invention has for its object to provide an improved and reliable method for degassing and / or decarburization of molten steel, wherein the formation of dead water areas is reduced.
  • the object of the present invention is achieved by a device comprising at least one degassing vessel, a Stahlg screenpfanne, an inlet trunk and a gas purging device arranged therein and a spout.
  • the spout has at least one bore at the lower edge in the radial direction, relative to the central longitudinal axis of the spout, for sucking a carbonaceous melt from a dead water zone between the spout and the socket delivery and directing it into the downflow of the spout.
  • the device is preferably an RH plant.
  • the carbonaceous melt is drawn in from the dead water zone between the spout and the pan feed and directed into the downflow of the spout.
  • the size and number of holes at the bottom of the spout are dependent on the RH method and must be adjusted accordingly.
  • the main parameters are the geometry and immersion depth of the inlet and outlet probes and the negative pressure in the RH vacuum vessel.
  • the inventive device in particular the new shape of the spout, the local dead water area is reduced in size.
  • the treatment and circulation time of the melt can be advantageously shortened. This leads to the advantageous reduction of argon consumption and further cost reduction.
  • the productivity of the RH plant is increased.
  • a preferred embodiment of the invention is an outlet spout having a plurality of bores within a radius of 360 °.
  • the outlet trunk particularly preferably has several holes within a radius of 180 ° in the direction of the refractory wall the ladle. Due to the inventive design of the spout, the local dead water areas are effectively reduced.
  • the size and number of holes depends on the geometry and immersion depth of the spout and the vacuum in the evacuation vessel.
  • Another preferred embodiment of the invention is a spout, wherein the holes have a diameter of 10 mm to 50 mm, preferably 25 mm to 35 mm. With these diameters for the holes good results are achieved in the Totwasserreduzi für a spout.
  • a further preferred embodiment of the invention is a spout whose immersion depth in the molten steel of the ladle is from 300 mm to 1200 mm, preferably 400 mm to 1000 mm. In this range for the immersion depth good results are achieved in the Totwasserreduzi für spout.
  • a further preferred embodiment of the invention is a spout, wherein one or more holes 50 mm to 900 mm, preferably 100 mm to 700 mm, are arranged above the lower edge of the spout.
  • a further preferred embodiment of the invention is a spout, wherein holes in a row of holes or in several superposed rows of holes are on the spout. Preference is given to one or two superimposed rows of holes on the outlet trunk.
  • the object of the present invention is further achieved by the use of the spout according to the invention in a RH plant for reducing local dead water areas in a ladle.
  • a RH plant for reducing local dead water areas in a ladle.
  • RH plant I has a steel cistern 3 with a volume of 200 t.
  • the immersion depth of the spout 1 and the inlet trunk 4 was 600 mm.
  • the process time was 85 s.
  • the following process steps were carried out in the RH plant.
  • Argon 5 was introduced over the mirror of the steel bath 10 into the inlet trunk 4.
  • the liquid steel 10 was sucked from the ladle 3 into the inlet trunk 4.
  • the liquid steel 10 was conveyed from the inlet trunk 4 into the evacuation vessel 2 located above.
  • the liquid steel 10 was degassed in the evacuation vessel 2.
  • the liquid steel 10 was conveyed via the spout 1 back into the ladle 3.
  • a local Totwasser 9 formed between the spout 4 and the refractory wall 8 of the ladle 3 from. Due to the downwardly directed melt stream from the spout 4 little molten steel 10 was sucked in from the immediate vicinity of the spout 1 ago. As a result, the carbon concentration in the dead water area 9 remained high at a high level due to the delayed homogenization. The dead water area 9 mixed poorly with the remainder of the melt 10 because the average flow rate was low. The duration of the proceedings was high.
  • Fig. 2 shows a cross section through an inventive RH plant I with holes 7 in the spout 1 and with greatly reduced local Totwasser which 9 between the spout 1 and refractory wall 8 of the ladle 3.
  • the procedure was as in the example in Fig. 1 with the following differences.
  • the spout 1 had several holes 7 in the radial direction, based on the central longitudinal axis 6 of the spout 1 on the side towards the refractory wall 8 of the ladle 3.
  • the holes 7 were 150 mm above the lower edge of the spout 1 is arranged.
  • the immersion depth of the spout H snorkel was 400 mm.
  • Molten steel 10 was sucked in from the immediate vicinity around the spout 1 ago. The homogenization in the molten steel 10 was faster. Consequently, the carbon concentration in the dead water region 9 dropped. The process time was thereby greatly reduced.
  • FIGS. 3 and 4 illustrate the following example. First, the geometry of an RH plant in Table 1 and the physical quantities in Table 2 are explained.
  • Table 1 Geometry of the RH plant Measurement unit H melt Distance from the lower edge of the degassing vessel to the gas inlet 1350 meter D 1 Diameter of the degassing vessel 2200 meter D 2a Outer diameter of the inlet spout and the spout 1294 meter D 2i Inner diameter of the inlet spout and the spout 0650 meter D 3 Diameter of the ladle 3396 meter H snorkel Immersion depth of the spout 0.6 meter h nozzel Distance of the hole from the lower edge of the spout 0275 meter Physical sizes Measurement unit P 0 Pressure in the ladle at rest 100000 Pa P RH Pressure in the degassing vessel 200 Pa r ho Density of the melt 6930 - 7050 Kg / m 3 T Temperature of the melt 1600 ° C
  • the negative pressure in the RH vessel is gradually reduced, for example, from initially 250 mbar down to 2 mbar within about 6 min.
  • the pressure of 2 mbar is then also the lowest pressure in the RH vessel, in particular directly above the melt surface in the RH vessel.
  • the cycle time in an RH plant is about 10 minutes to 50 minutes.
  • the homogenization time in the melt at a spout without holes about 90 s to 480 s.
  • the homogenization time in the melt is approximately 85 s to 456 s for a spout with holes. This means a reduction in the cycle time of about 5%.
  • the number n of holes is preferably 3 to 9.
  • the number is preferably odd, since central hole should lie on the axis, therefore in the narrowest gap between Pfannenausmautation and proboscis.
  • the preferred bore diameter is 10 mm to 50 mm.
  • the row of holes should be positioned no more than 300 mm above the exit opening of the spout .
  • the row of holes in the vertical direction should not be closer than 300 mm below the melt surface in the steel ladle, otherwise there is a risk that slag will be sucked in from the surface.
  • two or more rows of holes can be arranged one above the other, see Table 2.
  • the holes in the spout can also be arranged between the two trunks, as it also collects in this area calmed melting material.

Description

Die vorliegende Erfindung betrifft eine Vorrichtung zur Entgasung einer Stahlschmelze mit einem verbesserten Auslaufrüssel. Die vorliegende Erfindung betrifft insbesondere eine besondere Form eines Auslaufrüssels zur Vermeidung von lokalen Totwassergebieten (dead water region) in einer Stahlgießpfanne. Die vorliegende Erfindung betrifft weiter ein Verfahren zur Entgasung vom flüssigen Stahl mit dem verbesserten Auslaufrüssel.The present invention relates to a device for degassing a molten steel with an improved spout. In particular, the present invention relates to a particular form of spout for avoiding dead water regions in a steel ladle. The present invention further relates to a method of degassing the liquid steel with the improved spout.

Bei dem Verfahren zur Entgasung vom flüssigen Stahl handelt es sich um ein RH-Verfahren (Ruhrstahl-Heraeus Verfahren). Beim RH-Verfahren wird der flüssige Stahl aus einer Gießpfanne in einem Steigrohr in ein Evakuierungsgefäß befördert. Ein Fördergas, insbesondere Argon, wird über dem Stahlbadspiegel in das Steigrohr eingeführt. Der in das Steigrohr über mehrere Düsen injizierte Argonstrom zerfällt in eine Vielzahl von Argonblasen, die in unmittelbarer Wandnähe aufsteigen. Die Beförderung des flüssigen Stahls wird durch die Volumenvergrößerung durch Argon im Steigrohr und durch den Druckunterschied zwischen dem äußeren Luftdruck und dem Unterdruck im Evakuierungsgefäß ermöglicht. Die Argonblasen reißen die Schmelze mit und sorgen für einen gleichmäßigen Schmelzumlauf. Der Partialdruck wird gleichzeitig gesenkt und die Entkohlungsreaktion beschleunigt. Der in das Evakuierungsgefäß eingesaugte Stahl wird zersprüht. Dadurch treten eine starke Oberflächenvergrößerung und eine gute Entgasung des flüssigen Stahls ein.The process for degassing liquid steel is an RH process (Ruhrstahl-Heraeus process). In the RH process, the liquid steel is conveyed from a ladle in a riser to an evacuation vessel. A conveying gas, in particular argon, is introduced into the riser above the steel bath level. The injected into the riser through several nozzles argon stream breaks down into a variety of argon bubbles that rise in the immediate vicinity of the wall. The conveyance of the liquid steel is made possible by the volume increase by argon in the riser and by the pressure difference between the external air pressure and the negative pressure in the evacuation vessel. The argon bubbles entrain the melt and ensure a uniform melt circulation. The partial pressure is lowered at the same time and the decarburization reaction is accelerated. The steel sucked into the evacuation vessel is sprayed. This results in a strong increase in surface area and good degassing of the liquid steel.

Sauerstoff, der während der gesamten Behandlungszeit gleichzeitig eingeführt und unter anderem aus der Schlacke nachgeliefert wird, führt zur Bildung von Kohlenmonoxid (CO). CO gast im Vakuumgefäß aus, wodurch die gewünschte Entkohlung erreicht wird. Die Feinentkohlung kann auf möglichst niedrige Werte durch zusätzlich eingeblasenen Sauerstoff optimiert werden. Eine hohe Umlaufgeschwindigkeit der Schmelze und damit eine Erhöhung des Fördergasstromes sowie eine Vergrößerung des Rüsseldurchmessers der Vakuumanlage führen zu einem schnelleren Entkohlungsablauf.Oxygen, which is simultaneously introduced throughout the treatment period and replenished, among other things, from the slag, leads to the formation of carbon monoxide (CO). CO gas in the vacuum vessel, resulting in the desired decarburization is reached. The fine decarburization can be optimized to the lowest possible values by additionally injected oxygen. A high rotational speed of the melt and thus an increase in the flow of carrier gas and an increase in the diameter of the bowl of the vacuum system lead to a faster decarburization process.

Aus DE 19511640 C1 ist ein Rüssel für ein Entgasungsgefäß mit einer feuerfesten Auskleidung und einer darin angeordneten Gasspüleinrichtung mit mehreren Kanälen bekannt. Die Kanäle sind über den Umfang des Rüssels verteilt und verlaufen, bezogen auf die Mittenlängsachse des Rüssels, durch die feuerfeste Auskleidung in radialer Richtung. Die Kanäle sind an der Außenseite an mindestens eine Gaszuführleitung anschließbar.Out DE 19511640 C1 is a trunk for a degassing vessel with a refractory lining and arranged therein a gas purging device with multiple channels known. The channels are distributed over the circumference of the trunk and extend, based on the central longitudinal axis of the trunk, through the refractory lining in the radial direction. The channels can be connected to at least one gas supply line on the outside.

Die Kanäle sind zur Ausbildung eines nahezu kontinuierlichen Gasschleiers entlang der Innenwand des Rüssels in dichter Folge umlaufend angeordnet. Ein gleichmäßiger Strom von flüssigem Stahl wird bis ins Vakuumgefäß erreicht. Die über den gesamten Umfang verteilte, vorzugsweise feinblasige Gaszuführung ermöglicht eine besonders feine Verteilung des Behandlungsgases bei einem gleichzeitig stark erhöhten Reaktionsvolumen zwischen Behandlungsgas und Stahlschmelze. Auf diese Art und Weise lässt sich eine höhere und schnellere Entkohlungsleistung erzielen, so dass geringere Mengen an Reduktionsmedien notwendig sind.The channels are circumferentially arranged to form a nearly continuous gas curtain along the inner wall of the trunk in close succession. A steady stream of liquid steel is reached into the vacuum vessel. The distributed over the entire circumference, preferably fine-bubble gas supply allows a particularly fine distribution of the treatment gas at the same time greatly increased reaction volume between the treatment gas and molten steel. In this way, a higher and faster decarburization performance can be achieved, so that smaller amounts of reduction media are necessary.

Aus JP 6299227 A ist ein Verfahren zur Herstellung von Stahl mit sehr geringem Kohlenstoffanteil mit einer Entgasungsvorrichtung bekannt, wobei der Einlaufrüssel so positioniert ist, dass die Distanz zwischen der Achse des Einlaufrüssels und der Achse des Metallbades mindestens 10% des inneren Durchmessers des Metallbades beträgt.Out JP 6299227 A For example, there is known a method of producing very low carbon steel with a degassing apparatus, wherein the inlet trunk is positioned so that the distance between the axis of the inlet trunk and the axis of the metal bath is at least 10% of the inner diameter of the metal bath.

Aus JP 1198418 A ist eine Vorrichtung und ein Verfahren zur Vakuumentgasung von geschmolzenem Stahl bekannt, wobei sowohl in den Einlauf- und Auslaufrüssel Gas eingeleitet und abwechselnd die Funktion der Rüssel geändert werden kann.Out JP 1198418 A a device and a method for the vacuum degassing of molten steel is known, wherein both introduced into the inlet and outlet spout gas and alternately the function of the trunk can be changed.

Aus JP 57200514 A ist ein Verfahren zur Entgasung vom geschmolzenen Stahl bekannt, wobei die Entgasungswirkung durch eine Entgasung in einer RH-Vakuum Apparatur verbessert wird, in dem ein Inertgas in einen Stahlschmelzgefäß vom Boden eingeblasen wird.Out JP 57200514 A A method for degassing molten steel is known, wherein the degassing effect is improved by degassing in an RH vacuum apparatus in which an inert gas is injected into a steel melting vessel from the bottom.

Aus JP 3271315 A ist ein RH-Vakuum Entkohlungsverfahren von Edelstahl bekannt, wobei die Entgasung und Entkohlung in kurzer Zeit erreicht und der Chromverlust reduziert wird. Das Ergebnis wird durch die Verwendung von Stahl mit geringem Siliziumgehalt und durch wiederholte Entgasung und Entkohlungsvorgänge mit einem RH-Vakuumgefäß erreicht.Out JP 3271315 A is a RH vacuum decarburization of stainless steel known, the degassing and decarburization is achieved in a short time and the loss of chromium is reduced. The result is achieved by using low silicon steel and repeated degassing and decarburization with an RH vacuum vessel.

Aus JP 2173204 A ist ein Vakuumgefäß für eine RH-Entgasungsvorrichtung bekannt, wobei ein Ultraschall Oszillator an einer Kontaktstelle mit dem flüssigen Stahl im Vakuumgefäß eingebaut wird, um Blasen zu zerstören, die durch die Gaseinblasung erzeugt werden und um die Reaktionsoberfläche an der Phasenreaktion zu verbessern.Out JP 2173204 A For example, a vacuum vessel for an RH degassing apparatus is known wherein an ultrasonic oscillator is installed at a contact point with the liquid steel in the vacuum vessel to destroy bubbles generated by the gas injection and to improve the reaction surface on the phase reaction.

Aus JP 11158536 A ist ein Verfahren zum Schmelzen von Stahl mit sehr niedrigem Kohlenstoffgehalt bekannt, wobei Inertgas durch das Einlaufrohr unter das zugesetzte Aluminium in das Gefäß beim Auslaufrüssel zum Umlauf nach der Entkohlung eingeblasen wird.Out JP 11158536 A For example, a method of smelting very low carbon steel is known wherein inert gas is injected through the inlet tube under the added aluminum into the vessel at the spout for circulation after decarburization.

Aus JP 3107412 A ist ein Verfahren zur Herstellung von Stahl mit sehr niedrigen Kohlenstoffgehalt bekannt, wobei während der Entkohlung sowohl in das Einlauf- wie das Auslaufrohr zur gleichen Zeit Argon eingeblasen wird.Out JP 3107412 A discloses a method of producing very low carbon steel, wherein argon is injected at the same time during decarburization into both the inlet and outlet tubes.

Ferner ist aus der JP 05214426 ein weiterer Entgasungsbehälter bekannt, bei welchem seitlich in einem Steigrohr und in einem Auslaufohr jeweils mindestens eine Bohrung für eine Treibgasleitung eingebracht ist.Furthermore, from the JP 05214426 another degassing known, in which at least one bore for a propellant gas line is introduced laterally in a riser and in an outlet pipe.

In der JP 01275715 ist eine Entgasungseinrichtung beschrieben, in deren Auslaufrohr Gaszuführöffnungen vorgesehen sind, mittels welchen ein Inertgas in die Stahlschmelze eingeblasen werden kann, um das Eindringen von Schlacke in die Stahlschmelze zu verhindern.In the JP 01275715 a degassing device is described, in whose outlet pipe gas supply openings are provided, by means of which an inert gas in the Molten steel can be blown in order to prevent the ingress of slag into the molten steel.

Es hat sich gezeigt und wird durch numerische Simulationen belegt, dass sich in der Stahlgießpfanne einer RH-Anlage lokale Strömungsgebiete, sogenannte Totwassergebiete bilden, die sich relativ spät, erst nach etwa zwei Minuten mit der übrigen Schmelze vermischen.It has been shown and proved by numerical simulations that form in the steel ladle of an RH plant local flow areas, so-called dead water areas, which mix relatively late, after about two minutes with the rest of the melt.

Die im Stand der Technik bekannten Vorrichtungen und Verfahren weisen den Nachteil auf, dass sich Totwassergebiete in der Stahlgießpfanne bilden durch die die Homogenisierungszeit der Schmelze erhöht wird.The devices and methods known in the prior art have the disadvantage that dead water areas in the steel ladle form by which the homogenization time of the melt is increased.

Ein Totwassergebiet bildet sich üblicherweise zwischen dem Auslaufrüssel und der Feuerfestwand der Gießpfanne. Durch den nach unten gerichteten Schmelzenstrahl aus dem Auslaufrüssel wird wenig Material aus der direkten Umgebung um den Auslaufrüssel her angesaugt. Folglich bleibt die Kohlenstoffkonzentration dort aufgrund der verzögerten Homogenisierung insgesamt auf einem hohen Niveau. Das Totwassergebiet vermischt sich schlecht mit der übrigen Schmelze, da die mittlere Strömungsgeschwindigkeit niedrig ist. Aufgrund des geringen Massen-, Impuls- und Energieaustausches zwischen dem Totwassergebiet mit hoher Kohlenstoffkonzentration und der übrigen Schmelze mit niedriger Kohlenstoffkonzentration muss die Pfannenschmelze häufig umgewälzt werden bis der gewünschte Endkohlenstoffgehalt erreicht ist. Da die Pfannenschmelze häufig umlaufen muss, ist die Behandlungszeit hoch.A dead water area is usually formed between the spout and the refractory wall of the ladle. Due to the downward stream of melt from the spout little material from the immediate vicinity is sucked in around the spout. As a result, the overall carbon concentration remains high due to the delayed homogenization. The dead water area mixes poorly with the rest of the melt because the average flow rate is low. Because of the low mass, momentum and energy exchange between the high carbon concentration dead water zone and the remainder of the low carbon concentration melt, the ladle melt often has to be recirculated until the desired final carbon content is achieved. Since the ladle melt has to circulate frequently, the treatment time is high.

Der Erfindung liegt die Aufgabe zugrunde, eine Vorrichtung zur Entgasung einer Stahlschmelze mit einem verbesserten Auslaufrüssel bereitzustellen, der die Bildung von Totwassergebieten reduziert.The invention has for its object to provide an apparatus for degassing a molten steel with an improved spout, which reduces the formation of dead water areas.

Der Erfindung liegt die Aufgabe zugrunde, ein verbessertes und zuverlässiges Verfahren zur Entgasung und / oder Entkohlung einer Stahlschmelze bereitzustellen, wobei die Bildung von Totwassergebieten reduziert wird.The invention has for its object to provide an improved and reliable method for degassing and / or decarburization of molten steel, wherein the formation of dead water areas is reduced.

Die Aufgabe der vorliegenden Erfindung wird gelöst, durch eine Vorrichtung, die mindestens ein Entgasungsgefäß, eine Stahlgießpfanne, einen Einlaufrüssel und eine darin angeordnete Gasspüleinrichtung und einen Auslaufrüssel umfasst. Der Auslaufrüssel weist an der Unterkante in radialer Richtung, bezogen auf die Mittenlängsachse des Auslaufrüssels, mindestens eine Bohrung auf, um eine kohlenstoffhaltige Schmelze aus einem Totwassergebiet zwischen dem Auslaufrüssel und der Pfannenzustellung anzusaugen und in den Abwärtsstrom des Auslaufrüssels zu leiten.The object of the present invention is achieved by a device comprising at least one degassing vessel, a Stahlgießpfanne, an inlet trunk and a gas purging device arranged therein and a spout. The spout has at least one bore at the lower edge in the radial direction, relative to the central longitudinal axis of the spout, for sucking a carbonaceous melt from a dead water zone between the spout and the socket delivery and directing it into the downflow of the spout.

Die Vorrichtung ist bevorzugt eine RH-Anlage.The device is preferably an RH plant.

Als Folge eines sich einstellenden Venturi-Effekts wird die kohlenstoffhaltige Schmelze aus dem Totwassergebiet zwischen dem Auslaufrüssel und der Pfannenzustellung angesaugt und in den Abwärtsstrom des Auslaufrüssels geleitet.As a result of a self-adjusting Venturi effect, the carbonaceous melt is drawn in from the dead water zone between the spout and the pan feed and directed into the downflow of the spout.

Die Größe und die Anzahl der Bohrungen an der Unterkannte des Auslaufrüssels sind abhängig von dem jeweiligen RH-Verfahren und müssen daran angepasst werden. Wesentliche Parameter sind die Geometrie und Eintauchtiefe der Ein- und Auslaufrüssel sowie der Unterdruck im RH-Vakuumgefäß.The size and number of holes at the bottom of the spout are dependent on the RH method and must be adjusted accordingly. The main parameters are the geometry and immersion depth of the inlet and outlet probes and the negative pressure in the RH vacuum vessel.

Es muss verhindert werden, dass nicht zu viel Schmelze von Außerhalb in den Auslaufrüssel transportiert wird und dadurch möglicherweise oben schwimmende Schlacke von der freien Oberfläche der Stahlgießpfanne mit eingesaugt wird.It must be prevented that not too much melt from outside is transported into the spout and thus possibly sucking up-floating slag from the free surface of the steel ladle with.

Durch die erfindungsgemäße Vorrichtung, insbesondere der neuen Form des Auslaufrüssels wird das lokale Totwassergebiet in seinen Abmessungen reduziert. Die Behandlungs- und Umlaufzeit der Schmelze kann vorteilhaft verkürzt werden. Das führt zur vorteilhaften Senkung des Argonverbrauchs und zur weiteren Kostenreduktion. Die Produktivität der RH-Anlage wird gesteigert.The inventive device, in particular the new shape of the spout, the local dead water area is reduced in size. The treatment and circulation time of the melt can be advantageously shortened. This leads to the advantageous reduction of argon consumption and further cost reduction. The productivity of the RH plant is increased.

Eine bevorzugte Ausgestaltung der Erfindung ist ein Auslaufrüssel, der mehrere Bohrungen im Umkreis von 360° aufweist. Der Auslaufrüssel weist besonders bevorzugt mehrere Bohrungen im Umkreis von 180° in Richtung der Feuerfestwand der Gießpfanne auf. Durch die erfindungsgemäße Ausgestaltung des Auslaufrüssels werden die lokalen Totwassergebiete wirksam reduziert.A preferred embodiment of the invention is an outlet spout having a plurality of bores within a radius of 360 °. The outlet trunk particularly preferably has several holes within a radius of 180 ° in the direction of the refractory wall the ladle. Due to the inventive design of the spout, the local dead water areas are effectively reduced.

Die Größe und die Anzahl der Bohrungen sind von der Geometrie und Eintauchtiefe des Auslaufrüssels sowie dem Unterdruck im Evakuierungsgefäß abhängig.The size and number of holes depends on the geometry and immersion depth of the spout and the vacuum in the evacuation vessel.

Eine weitere bevorzugte Ausgestaltung der Erfindung ist ein Auslaufrüssel, wobei die Bohrungen einen Durchmesser von 10 mm bis 50 mm, bevorzugt 25 mm bis 35 mm aufweisen. Bei diesen Durchmessern für die Bohrungen werden gute Ergebnisse bei der Totwasserreduzierung erzielt.Another preferred embodiment of the invention is a spout, wherein the holes have a diameter of 10 mm to 50 mm, preferably 25 mm to 35 mm. With these diameters for the holes good results are achieved in the Totwasserreduzierung.

Eine weitere bevorzugte Ausgestaltung der Erfindung ist ein Auslaufrüssel, dessen Eintauchtiefe in der Stahlschmelze der Gießpfanne von 300 mm bis 1200 mm, bevorzugt 400 mm bis 1000 mm beträgt. In diesem Bereich für die Eintauchtiefe werden gute Ergebnisse bei der Totwasserreduzierung erzielt.A further preferred embodiment of the invention is a spout whose immersion depth in the molten steel of the ladle is from 300 mm to 1200 mm, preferably 400 mm to 1000 mm. In this range for the immersion depth good results are achieved in the Totwasserreduzierung.

Eine weitere bevorzugte Ausgestaltung der Erfindung ist ein Auslaufrüssel, wobei eine oder mehrere Bohrungen 50 mm bis 900 mm, bevorzugt 100 mm bis 700 mm, oberhalb der Unterkante des Auslaufrüssels angeordnet sind. Dadurch wird der vertikale Abstand zwischen den Bohrungen und der Pfannenschlacke möglichst groß. Es wird verhindert, dass Pfannenschlacke in den Auslaufrüssel angesaugt wird.A further preferred embodiment of the invention is a spout, wherein one or more holes 50 mm to 900 mm, preferably 100 mm to 700 mm, are arranged above the lower edge of the spout. As a result, the vertical distance between the holes and the ladle slag is as large as possible. It is prevented that ladle slag is sucked into the spout.

Eine weitere bevorzugte Ausgestaltung der Erfindung ist ein Auslaufrüssel, wobei sich Bohrungen in einer Bohrungsreihe oder in mehreren übereinander liegenden Bohrungsreihen am Auslaufrüssel befinden. Bevorzugt sind eine oder zwei übereinander liegende Bohrungsreihen am Auslaufrüssel.A further preferred embodiment of the invention is a spout, wherein holes in a row of holes or in several superposed rows of holes are on the spout. Preference is given to one or two superimposed rows of holes on the outlet trunk.

Die Aufgabe der vorliegenden Erfindung wird durch ein Verfahren zur Entgasung einer Stahlschmelze gelöst, wobei

  1. a) ein Fördergas, insbesondere Argon, über dem Stahlbadspiegel in einen Einlaufrüssel eingeleitet wird,
  2. b) flüssiger Stahl aus einer Gießpfanne in den Einlaufrüssel gesogen wird
  3. c) flüssiger Stahl aus dem Einlaufrüssel in ein darüber befindliches Evakuierungsgefäß befördert wird,
  4. d) flüssiger Stahl entgast und entkohlt wird und
  5. e) flüssiger Stahl über einen Auslaufrüssel in die Gießpfanne befördert wird,
wobei der Auslaufrüssel an der Unterkante in radialer Richtung, bezogen auf die Mittenlängsachse des Auslaufrüssels, mindestens eine Bohrung aufweist, durch welche eine kohlenstoffhaltige Schmelze aus einem Totwassergebiet zwischen dem Auslaufrüssel und der Pfannenzustellung angesaugt und in den Abwärtsstrom des Auslaufrüssels geleiten wird.The object of the present invention is achieved by a method for degassing a molten steel, wherein
  1. a) a conveying gas, in particular argon, above the Stahlbadspiegel in a Inflow trunk is initiated
  2. b) sucking liquid steel from a ladle into the inlet spout
  3. c) transporting liquid steel from the inlet trunk into an evacuation vessel above it,
  4. d) degassing and decarburizing liquid steel, and
  5. e) transporting liquid steel through a spout into the ladle,
wherein the spout at the lower edge in the radial direction, relative to the central longitudinal axis of the spout, has at least one bore through which a carbonaceous melt is sucked from a Totwassergebiet between the spout and the Pfannenzustellung and directed in the downward flow of the spout.

Die Aufgabe der vorliegenden Erfindung wird weiter durch die Verwendung des erfindungsgemäßen Auslaufrüssels in einer RH-Anlage zur Reduzierung von lokalen Totwassergebieten in einer Gießpfanne gelöst. Durch die Verwendung des erfindungsgemäßen Auslaufrüssels werden lokale Totwassergebiete wirksam reduziert.The object of the present invention is further achieved by the use of the spout according to the invention in a RH plant for reducing local dead water areas in a ladle. By using the spout according to the invention local dead water areas are effectively reduced.

Die Erfindung wird anhand einer Zeichnung weiter im Einzelnen erläutert. In der Zeichnung ist ein Ausführungsbeispiel der Erfindung dargestellt.The invention will be explained in more detail with reference to a drawing. In the drawing, an embodiment of the invention is shown.

Es zeigen:

  • Fig. 1 einen Querschnitt durch eine RH-Anlage nach dem Stand der Technik ohne Bohrungen im Auslaufrüssel und mit einem lokalen Totwassergebiet zwischen dem Auslaufrüssel und der Feuerfestwand der Gießpfanne,
  • Fig. 2 einen Querschnitt durch eine erfindungsgemäße RH-Anlage mit Bohrungen im Auslaufrüssel und mit reduziertem lokalen Totwassergebiet zwischen dem Auslaufrüssel und der Feuerfestwand der Gießpfanne,
  • Fig. 3 einen Querschnitt durch eine erfindungsgemäße RH-Anlage im Ruhezustand und
  • Fig. 4 einen Querschnitt durch eine erfindungsgemäße RH-Anlage im Betriebszustand.
Show it:
  • Fig. 1 a cross section through a prior art RH plant without holes in the spout and with a local Totwassergebiet between the spout and the refractory wall of the ladle,
  • Fig. 2 a cross section through an inventive RH plant with holes in the spout and reduced local Totwassergebiet between the spout and the refractory wall of the ladle,
  • Fig. 3 a cross section through an inventive RH plant at rest and
  • Fig. 4 a cross section through an RH plant according to the invention in the operating state.

Die in Fig. 1 dargestellte RH-Anlage I weist eine Stahlgießwanne 3 mit einem Volumen von 200 t auf. Die Eintauchtiefe des Auslaufrüssels 1 and des Einlaufrüssels 4 betrug jeweils 600 mm. Die Prozesszeit betrug 85 s. In der RH-Anlage wurden folgende Verfahrensschritte durchgeführt. Argon 5 wurde über dem Spiegel des Stahlbads 10 in den Einlaufrüssel 4 eingeführt. Der flüssige Stahl 10 wurde aus der Gießpfanne 3 in den Einlaufrüssel 4 gesogen. Der flüssige Stahl 10 wurde aus dem Einlaufrüssel 4 in das darüber befindliche Evakuierungsgefäß 2 befördert. Der flüssige Stahl 10 wurde im Evakuierungsgefäß 2 entgast. Der flüssige Stahl 10 wurde über den Auslaufrüssel 1 wieder in die Gießpfanne 3 befördert. Ein lokales Totwassergebiet 9 bildete sich zwischen dem Auslaufrüssel 4 und der Feuerfestwand 8 der Gießpfanne 3 aus. Durch den nach unten gerichteten Schmelzenstrahl aus dem Auslaufrüssel 4 wurde wenig Stahlschmelze 10 aus der direkten Umgebung um den Auslaufrüssel 1 her angesaugt. Folglich blieb die Kohlenstoffkonzentration im Totwassergebiet 9 aufgrund der verzögerten Homogenisierung insgesamt auf einem hohen Niveau. Das Totwassergebiet 9 vermischte sich schlecht mit der übrigen Schmelze 10, da die mittlere Strömungsgeschwindigkeit niedrig war. Die Verfahrensdauer war hoch.In the Fig. 1 shown RH plant I has a steel cistern 3 with a volume of 200 t. The immersion depth of the spout 1 and the inlet trunk 4 was 600 mm. The process time was 85 s. The following process steps were carried out in the RH plant. Argon 5 was introduced over the mirror of the steel bath 10 into the inlet trunk 4. The liquid steel 10 was sucked from the ladle 3 into the inlet trunk 4. The liquid steel 10 was conveyed from the inlet trunk 4 into the evacuation vessel 2 located above. The liquid steel 10 was degassed in the evacuation vessel 2. The liquid steel 10 was conveyed via the spout 1 back into the ladle 3. A local Totwassergebiet 9 formed between the spout 4 and the refractory wall 8 of the ladle 3 from. Due to the downwardly directed melt stream from the spout 4 little molten steel 10 was sucked in from the immediate vicinity of the spout 1 ago. As a result, the carbon concentration in the dead water area 9 remained high at a high level due to the delayed homogenization. The dead water area 9 mixed poorly with the remainder of the melt 10 because the average flow rate was low. The duration of the proceedings was high.

Fig. 2 zeigt einen Querschnitt durch eine erfindungsgemäße RH-Anlage I mit Bohrungen 7 im Auslaufrüssel 1 und mit stark reduzierten lokalen Totwassergebiet 9 zwischen dem Auslaufrüssel 1 und Feuerfestwand 8 der Gießpfanne 3. Der Verfahrensablauf war wie im Beispiel in Fig. 1 mit den folgenden Unterschieden. Der Auslaufrüssel 1 wies mehrere Bohrungen 7 in radialer Richtung auf, bezogen auf die Mittenlängsachse 6 des Auslaufrüssels 1 auf der Seite hin zur Feuerfestwand 8 der Gießpfanne 3. Die Bohrungen 7 waren 150 mm oberhalb der Unterkante des Auslaufrüssels 1 angeordnet. Die Eintauchtiefe des Auslaufrüssels Hsnorkel betrug 400 mm. Stahlschmelze 10 wurde aus der direkten Umgebung um den Auslaufrüssel 1 her angesaugt. Die Homogenisierung in der Stahlschmelze 10 erfolgte schneller. Folglich sank die Kohlenstoffkonzentration im Totwassergebiet 9. Die Verfahrensdauer wurde dadurch stark verringert. Fig. 2 shows a cross section through an inventive RH plant I with holes 7 in the spout 1 and with greatly reduced local Totwassergebiet 9 between the spout 1 and refractory wall 8 of the ladle 3. The procedure was as in the example in Fig. 1 with the following differences. The spout 1 had several holes 7 in the radial direction, based on the central longitudinal axis 6 of the spout 1 on the side towards the refractory wall 8 of the ladle 3. The holes 7 were 150 mm above the lower edge of the spout 1 is arranged. The immersion depth of the spout H snorkel was 400 mm. Molten steel 10 was sucked in from the immediate vicinity around the spout 1 ago. The homogenization in the molten steel 10 was faster. Consequently, the carbon concentration in the dead water region 9 dropped. The process time was thereby greatly reduced.

Figuren 3 und 4 verdeutlichen das folgende Beispiel. Zunächst werden die Geometrie einer RH-Anlage in Tabelle 1 und die physikalischen Größen in Tabelle 2 erläutert. Tabelle 1 Geometrie der RH-Anlage Messung Einheit Hmelt Abstand von der Unterkante des Entgasungsgefäßes bis zum Gaseinlauf 1.350 Meter D1 Durchmesser des Entgasungsgefäßes 2.200 Meter D2a Aussendurchmesser des Einlaufrüssels und des Auslaufrüssels 1.294 Meter D2i Innendurchmesser des Einlaufrüssels und des Auslaufrüssels 0.650 Meter D3 Durchmesser der Gießpfanne 3.396 Meter Hsnorkel Eintauchtiefe des Auslaufrüssels 0.6 Meter hnozzel Abstand der Bohrung von der Unterkannte des Auslaufrüssels 0.275 Meter Tabelle 2 Physikalische Größen Messung Einheit P0 Druck in der Gießpfanne im Ruhezustand 100.000 Pa PRH Druck im Entgasungsgefäß 200 Pa rho Dichte der Schmelze 6930 - 7050 Kg/m3 T Temperatur der Schmelze 1600 °C FIGS. 3 and 4 illustrate the following example. First, the geometry of an RH plant in Table 1 and the physical quantities in Table 2 are explained. Table 1 Geometry of the RH plant Measurement unit H melt Distance from the lower edge of the degassing vessel to the gas inlet 1350 meter D 1 Diameter of the degassing vessel 2200 meter D 2a Outer diameter of the inlet spout and the spout 1294 meter D 2i Inner diameter of the inlet spout and the spout 0650 meter D 3 Diameter of the ladle 3396 meter H snorkel Immersion depth of the spout 0.6 meter h nozzel Distance of the hole from the lower edge of the spout 0275 meter Physical sizes Measurement unit P 0 Pressure in the ladle at rest 100000 Pa P RH Pressure in the degassing vessel 200 Pa r ho Density of the melt 6930 - 7050 Kg / m 3 T Temperature of the melt 1600 ° C

Der Unterdruck im RH-Gefäß wird allmählich reduziert, zum Beispiel von anfangs 250 mbar bis herunter auf 2 mbar innerhalb von etwa 6 min. Der Druck von 2 mbar ist dann auch der tiefste Druck im RH-Gefäß, insbesondere direkt oberhalb der Schmelzenoberfläche im RH-Gefäß.The negative pressure in the RH vessel is gradually reduced, for example, from initially 250 mbar down to 2 mbar within about 6 min. The pressure of 2 mbar is then also the lowest pressure in the RH vessel, in particular directly above the melt surface in the RH vessel.

Die Zykluszeit beträgt in einer RH-Anlage etwa 10 min bis 50 min. Die Homogenisierungszeit beträgt in der Schmelze bei einem Auslaufrüssel ohne Bohrungen etwa 90 s bis 480 s. Die Homogenisierungszeit beträgt in der Schmelze bei einem Auslaufrüssel mit Bohrungen etwa 85 s bis 456 s. Das bedeutet eine Reduzierung der Zykluszeit um etwa 5 %.The cycle time in an RH plant is about 10 minutes to 50 minutes. The homogenization time in the melt at a spout without holes about 90 s to 480 s. The homogenization time in the melt is approximately 85 s to 456 s for a spout with holes. This means a reduction in the cycle time of about 5%.

Die Anzahl n der Bohrungen beträgt bevorzugt 3 bis 9. Die Zahl ist bevorzugt ungerade, da zentrale Bohrung auf der Achse, daher im engsten Spalt zwischen Pfannenausmauerung und Rüssel liegen sollte.The number n of holes is preferably 3 to 9. The number is preferably odd, since central hole should lie on the axis, therefore in the narrowest gap between Pfannenausmauerung and proboscis.

Der Winkel α zwischen den Bohrungen ist abhängig von der Anzahl n der Bohrungen. Bei bis zu 3 Bohrungen beträgt α = 10° bis 20°. Dadurch erfolgt eine gezielte Absaugung des Totwassers aus dem Bereich zwischen Pfannenzustellung und Rüsselwand. Bei bis zu 9 Bohrungen beträgt α = 7.5° - 11.25°. Dies entspricht dann einem abgedeckten Bereich von 60° bis 90°.The angle α between the holes depends on the number n of holes. For up to 3 holes, α = 10 ° to 20 °. This results in a targeted extraction of the dead water from the area between Pfannenzustellung and trunk wall. For up to 9 holes, α = 7.5 ° - 11.25 °. This then corresponds to a covered area of 60 ° to 90 °.

Der bevorzugte Bohrungsdurchmesser liegt bei 10 mm bis 50 mm.The preferred bore diameter is 10 mm to 50 mm.

Bei einer üblichen Eintauchtiefe des Auslaufrüssels von Hsnorkel = 600 m, sollte die Bohrungsreihe maximal 300 mm oberhalb der Austrittsöffnung des Auslaufrüssels positioniert sein. Die Bohrungsreihe in vertikaler Richtung soll nicht näher als 300 mm unterhalb der Schmelzenoberfläche in der Stahlgießpfanne sein, sonst besteht die Gefahr, dass Schlacke von der Oberfläche mit angesaugt wird.With a standard immersion depth of the outlet spout of H snorkel = 600 m, the row of holes should be positioned no more than 300 mm above the exit opening of the spout . The row of holes in the vertical direction should not be closer than 300 mm below the melt surface in the steel ladle, otherwise there is a risk that slag will be sucked in from the surface.

Bei Eintauchtiefen größer als 600 mm können alternativ auch zwei oder mehr Bohrungsreihen übereinander angeordnet werden, siehe Tabelle 2.For immersion depths greater than 600 mm, alternatively, two or more rows of holes can be arranged one above the other, see Table 2.

Vorteilhaft ist auch eine einzige, vertikale Bohrungsreihe im Raum zwischen Rüsselaußenwand und Feuerfestzustellung der Pfanne. Auf diese Weise wird das gesamte Totraummaterial, das sich hauptsächlich hier sammelt, sehr gezielt in den Rüssel angesaugt.Also advantageous is a single vertical row of holes in the space between the trunk outer wall and refractory lining of the pan. In this way, the whole Dead space material, which collects mainly here, very specifically sucked into the trunk.

Weiterhin können die Bohrungen im Auslaufrüssel auch zwischen den beiden Rüsseln angeordnet werden, da sich auch in diesem Bereich beruhigtes Schmelzenmaterial sammelt.Furthermore, the holes in the spout can also be arranged between the two trunks, as it also collects in this area calmed melting material.

Charakteristische Parameter bei Variation der Eintauchtiefe des Auslaufrüssels am Beispiel des Rüssel-Innendurchmessers Di = 650 mm und dem Unterdruck im RH-Gefäß 2 mbar gehen aus Tabelle 3 hervor. Tabelle 3 EintauchtiefeE) AnzahlA) AbstandV) AnzahlB) WinkelW) BohrungsdurchmesserD) Hsnorkel in mm m H in mm N α in° D in mm 400 1 100 3 10 30 600 1 300 5 15 30 800 2 200 3 10 30 500 5 15 100 3 10 1000 2 400 5 10 30 700 5 15 E) Eintauchtiefe des Auslaufrüssels
A) Anzahl der übereinander liegenden Bohrungsreihen am Auslaufrüssel
V) Vertikaler Abstand zwischen der Rüssel-Unterkante und den Bohrungsreihen
B) Anzahl der Bohrungen
W) Winkel zwischen den Bohrungen
D) Bohrungsdurchmesser Characteristic parameters with variation of the immersion depth of the spout on the example of the trunk inner diameter D i = 650 mm and the negative pressure in the RH vessel 2 mbar are shown in Table 3. Table 3 Immersion depth E) Number A) Distance V) Number B) Angle W) Bore diameter D) H snorkel in mm m H in mm N α in ° D in mm 400 1 100 3 10 30 600 1 300 5 15 30 800 2 200 3 10 30 500 5 15 100 3 10 1000 2 400 5 10 30 700 5 15 E) Immersion depth of the spout
A) Number of superimposed rows of holes at the spout
V) Vertical distance between the trunk lower edge and the rows of holes
B) Number of holes
W) Angle between the holes
D) bore diameter

BezugszeichenlisteLIST OF REFERENCE NUMBERS

II
RH-EntgasungsanlageRH degasser
11
AuslaufrüsselDiscontinued trunk
22
Evakuierungsgefäß / VakuumgefäßEvacuation vessel / vacuum vessel
33
Gießpfanne / Stahlgießpfanne / SchmelzgefäßLadle / ladle / crucible
44
Einlaufrüssel / SteigrohrInlet trunk / riser
55
Gasspüleinrichtung / Inertgas / ArgonGas purifier / inert gas / argon
66
Mittenlängsachsecentral longitudinal axis
77
Bohrungdrilling
88th
FeuerfestwandRefractory wall
99
Totwassergebietdead water
1010
Stahlschmelzemolten steel
P0 P 0
Druck in der Gießpfanne im RuhezustandPressure in the ladle at rest
PRH P RH
Druck im EntgasungsgefäßPressure in the degassing vessel
Hmelt H melt
Abstand von der Unterkante des Entgasungsgefäßes bis zum GaseinlaufDistance from the lower edge of the degassing vessel to the gas inlet
D1 D 1
Durchmesser des EntgasungsgefäßesDiameter of the degassing vessel
D2a D 2a
Aussendurchmesser des Einlaufrüssels und des AuslaufrüsselsOuter diameter of the inlet spout and the spout
D2i D 2i
Innendurchmesser des Einlaufrüssels und des AuslaufrüsselsInner diameter of the inlet spout and the spout
D3 D 3
Durchmesser der GießpfanneDiameter of the ladle
rhorho
Dichte der SchmelzeDensity of the melt
Hsnorkel H snorkel
Eintauchtiefe des AuslaufrüsselsImmersion depth of the spout
hnozzel h nozzel
Abstand der Bohrung von der Unterkannte des AuslaufrüsselsDistance of the hole from the lower edge of the spout
HH
Abstand von der Unterkante des Entgasungsgefäßes und SchmelzspiegelDistance from the lower edge of the degassing vessel and melting mirror
Z1 Z 1
Anstieg der SchmelzeRise of the melt
ΔzAz
Abstand von der Unterkante des Entgasungsgefäßes und GaseinlaufDistance from the lower edge of the degassing vessel and gas inlet
TT
Temperatur der SchmelzeTemperature of the melt

Claims (13)

  1. Device for degassing a steel melt, comprising an evacuation vessel (2), a casting ladle (3), an inlet nozzle (4) with a gas flushing device (5) arranged therein and an outlet nozzle (1), wherein the outlet nozzle (1) has at the lower edge in radial direction referred to the centre longitudinal axis (6) of the outlet nozzle (1) at least one bore (7) so as to suck up melt with carbon content from a deadwater region (9) between the outlet nozzle (1) and the ladle infeed and to conduct it into the downward flow of the outlet nozzle (1).
  2. Device according to claim 1, wherein the outlet nozzle (1) has a plurality of bores (7).
  3. Device according to claim 1 or 2, wherein the outlet nozzle (1) has a plurality of bores (7) in the surrounding area of 360°.
  4. Device according to any one of claims 1 to 3, wherein the outlet nozzle (1) has a plurality of bores (7) in the surrounding area of 180° in the direction of the refractory wall (9) of the casting ladle (3).
  5. Device according to any one of claims 1 to 4, wherein the bores (7) have a diameter of 10 millimetres to 50 millimetres.
  6. Device according to claim 5, wherein the bores (7) have a diameter of 25 millimetres to 35 millimetres.
  7. Device according to any one of claims 1 to 6, wherein the immersion depth of the outlet nozzle (7) in the steel melt (10) in the casting ladle (3) is from 300 millimetres to 1200 millimetres.
  8. Device according to claim 7, wherein the immersion depth of the outlet nozzle (7) in the steel melt (10) in the casting ladle (3) is from 400 millimetres to 1000 millimetres.
  9. Device according to any one of claims 1 to 8, wherein one or more bores (7) are arranged 50 millimetres to 900 millimetres above the lower edge of the outlet nozzle (1).
  10. Device according to claim 9, wherein one or more bores (7) are arranged 100 millimetres to 700 millimetres above the lower edge of the outlet nozzle (1).
  11. Device according to any one of claims 1 to 10, wherein bores (7) are disposed in a bore row or in a plurality of bore rows, which lie one above the other, at the outlet nozzle (1).
  12. Method for degassing a steel melt, wherein
    a) a conveying gas, particularly argon, is introduced above the surface of the steel bath in an inlet nozzle (4),
    b) liquid steel (10) is conducted from a casting ladle (3) into the inlet nozzle (4),
    c) liquid steel (10) is conveyed from the inlet nozzle (4) into an evacuation vessel (2) disposed thereabove,
    d) liquid steel (10) is degassed and
    e) liquid steel (10) is conveyed by way of an outlet nozzle (1) into the casting ladle (3), wherein the outlet nozzle (1) has at the lower edge in radial direction referred to the centre longitudinal axis (6) of the outlet nozzle (1) at least one bore (7) through which a melt with carbon content is sucked up from a deadwater region (9) between the outlet nozzle (1) and the ladle infeed and conducted into the downward flow of the outlet nozzle (1).
  13. Use of an outlet nozzle according to any one of claims 1 to 11 in an RH plant for reduction of local deadwater regions (9) in a casting ladle (3).
EP10759802.1A 2009-08-28 2010-08-20 Device for degassing molten steel with an improved discharge nozzle Active EP2470678B1 (en)

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DE102009039260A DE102009039260A1 (en) 2009-08-28 2009-08-28 Apparatus for degassing a molten steel with an improved spout
PCT/EP2010/005124 WO2011023337A1 (en) 2009-08-28 2010-08-20 Device for degassing molten steel with an improved discharge nozzle

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EP2801627A1 (en) 2013-05-06 2014-11-12 Siemens VAI Metals Technologies GmbH Vacuum treatment vessel for the treatment of molten metal, in particular for a RH installation
KR102421018B1 (en) * 2014-05-21 2022-07-14 노벨리스 인크. Mixing eductor nozzle and flow control device
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RU2473704C1 (en) 2013-01-27
US20120160063A1 (en) 2012-06-28
EP2470678A1 (en) 2012-07-04
TWI454579B (en) 2014-10-01
DE102009039260A1 (en) 2011-03-03
TW201120221A (en) 2011-06-16
WO2011023337A1 (en) 2011-03-03
US9181602B2 (en) 2015-11-10
BR112012004433B1 (en) 2018-06-12

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