EP0714452A1 - Process and device for heat treatment in a hood type annealing furnace - Google Patents

Process and device for heat treatment in a hood type annealing furnace

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Publication number
EP0714452A1
EP0714452A1 EP94926826A EP94926826A EP0714452A1 EP 0714452 A1 EP0714452 A1 EP 0714452A1 EP 94926826 A EP94926826 A EP 94926826A EP 94926826 A EP94926826 A EP 94926826A EP 0714452 A1 EP0714452 A1 EP 0714452A1
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EP
European Patent Office
Prior art keywords
gas
nozzle
hood
annealing
annealing material
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP94926826A
Other languages
German (de)
French (fr)
Other versions
EP0714452B1 (en
Inventor
Georg Velten
Friedhelm Kühn
Walter Scheuermann
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LOI Thermprocess GmbH
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LOI Thermprocess GmbH
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/663—Bell-type furnaces
    • C21D9/673—Details, accessories, or equipment peculiar to bell-type furnaces
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/52—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for wires; for strips ; for rods of unlimited length
    • C21D9/54—Furnaces for treating strips or wire
    • C21D9/663—Bell-type furnaces
    • C21D9/667—Multi-station furnaces
    • C21D9/67—Multi-station furnaces adapted for treating the charge in vacuum or special atmosphere
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/767—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material with forced gas circulation; Reheating thereof

Definitions

  • the invention relates to a method for exchanging the atmosphere in a bell annealer, the fresh gas being blown into the bottom of the furnace and the gas mixture being formed being removed from the bottom of the furnace.
  • the invention further relates to a bell annealer for carrying out this method, with a base, an annealing material plate arranged on the base for carrying the annealing material, a blower arranged below a central opening of the annealing material plate, a hood surrounding the annealing material and the annealing material plate at a distance, and at least in each case a gas inlet and gas outlet arranged on the base.
  • Hood annealing furnaces are used in particular for the heat treatment of sheets that are wound into coils.
  • the latter are stacked one above the other on the annealing material plate, with its central "eye" forming a channel in the continuation of the central opening of the annealing material plate.
  • the air in the furnace is exchanged for protective gas.
  • the annealing treatment then begins, the fan sucking the gas centrally from top to bottom and conveying it laterally into the annular space between the annealing material and the hood.
  • At least one exchange of the atmosphere of the bell annealing furnace is therefore required for each batch. If you work with hydrogen, these processes multiply. The air must be expelled from the oven before heating up. This is done by blowing in nitrogen. The filling with hydrogen then takes place, the nitrogen being expelled. After the annealing treatment has ended, the hydrogen must first be expelled by blowing in nitrogen before the hood can be removed.
  • the fresh gas is blown into the furnace below the blower and conveyed by the blower into the annular space between the annealing material and the hood.
  • the resulting gas mixture is discharged through the gas outlet.
  • the gas input during the exchange of the atmosphere is quite considerable.
  • the volume flow is 100 to 180 m-Vh, normally for a period of 20 to 40 minutes. However, this presupposes the full functionality of the fan. If the fan fails, the rinsing time is approx. 24 hours. This loss of operating time is' great weight. There is also a not inconsiderable gas consumption.
  • the object of the invention is to remedy this and to enable a more economical, above all faster, exchange of the atmosphere.
  • the method according to the invention is characterized in that the fresh gas is blown into a flow path leading upwards as a high-speed jet and that the following relationship applies to the speed of the jet:
  • Vf free furnace space volume in liters
  • M A molecular weight of the gas to be flushed out in g / mol
  • p s density of the fresh gas in g / m 3
  • the device according to the invention is characterized in that the gas inlet is designed as an upwardly directed nozzle which opens into an upwardly flowing flow path.
  • the invention is based on the knowledge that the speed of the incoming jet significantly influences the exchange process and for the optimization of the speed the density of the gas to be flushed out and the
  • the high-speed beam can be directed through the central opening of the glow plate into the central channel formed by the "eyes" of the coils. It makes sense to make the shaft of the blower hollow and, if necessary with a corresponding extension, to use it as a nozzle.
  • the ratio of the distance between the center of the nozzle and the hood to the nozzle outlet diameter is between 2.5 and 8. If, for example, it is a question of exchanging H 2 for N2, the ratio is preferably> 7.5.
  • the nozzle advantageously opens at the level of the annealing material plate, the nozzle mouth being preceded by a flow length with a constant diameter which corresponds approximately to 5 times the nozzle outlet diameter. It has been found that very favorable flow conditions can be achieved in this way.
  • the nozzle exit area is preferably approximately 10% of the area of the gas outlet. This measure is also suitable for promoting the rinsing process.
  • the gas outlet is preferably arranged in the annular space between the annealing material and the hood diametrically opposite the nozzle. If several gas outlets and nozzles are provided, these are each arranged on a common sector, the sectors being opposite one another. In any case, a flow is forced which essentially follows the hood contour over a large area.
  • the gas outlet is preferably shielded by a baffle assigned to the blower, so that it detects, above all, the flow close to the hood, with transverse, short-circuit-like flows being largely rejected.
  • the bell annealer has a base 1 with an annealing plate 2.
  • the latter carries coils 3 stacked one above the other, in the present case four in number. Their "eyes" form a central channel 4, which connects to a central opening 5 of the glow ember plate 2.
  • a fan 6 works below the central opening 5.
  • the coils 3 and the annealing material plate 2 are covered by a hood 8 to form an annular space 7.
  • the bell annealer has a gas inlet in the form of an upwardly directed nozzle 9 which opens into the annular space 7. It generates a pulsed, upward-directed high-speed jet, the speed of which is 75 m / s, specifically at a volume flow of 130 m * - / h. It is a smooth jet nozzle with a diameter of 25 mm, the nozzle opening at the level of the annealing material plate 2. The ratio of the distance between the center of the nozzle and the hood to the nozzle diameter is 5.
  • a gas outlet 10 is provided, the diameter of which is 80 mm.
  • the gas outlet is shielded by a baffle 11 assigned to the blower 6.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Furnace Details (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)

Abstract

PCT No. PCT/EP94/02619 Sec. 371 Date Feb. 16, 1996 Sec. 102(e) Date Feb. 16, 1996 PCT Filed Aug. 6, 1994 PCT Pub. No. WO95/05487 PCT Pub. Date Feb. 23, 1995Fresh gas is blown into the ring-shaped space between the annealing charge and the hood as an upwardly directed high-speed jet (9) at a velocity of approximately 80 m/s. The gas mixture which forms is evacuated through a gas outlet (10) arranged in the pedestal and diametrically opposite to the gas inlet. At a volume flow rate of about 130 m3/s, rinsing takes about 6 minutes.

Description

Verfahren und Vorrichtung zum Austauschen der Atmosphäre in einem Haubenglühofen Method and device for exchanging the atmosphere in a bell annealer
Die Erfindung betrifft ein Verfahren zum Austauschen der Atmosphäre in einem Haubenglühofen, wobei das frische Gas unten in den Ofen eingeblasen und das sich bildende Gasgemisch unten aus dem Ofen abgeführt wird. Ferner betrifft die Erfindung einen Haubenglühofen zur Durchführung dieses Verfahrens, mit einem Sockel, einer auf dem Sockel angeordneten Glühgutplatte zum Tragen des Glühgutes, einem unterhalb einer Zentralöffnung der Glühgutplatte angeordneten Gebläse, einer das Glühgut und die Glühgutplatte mit Abstand umgebenden Haube und je minde¬ stens einem am Sockel angeordneten Gaseinlaß und Gasauslaß.The invention relates to a method for exchanging the atmosphere in a bell annealer, the fresh gas being blown into the bottom of the furnace and the gas mixture being formed being removed from the bottom of the furnace. The invention further relates to a bell annealer for carrying out this method, with a base, an annealing material plate arranged on the base for carrying the annealing material, a blower arranged below a central opening of the annealing material plate, a hood surrounding the annealing material and the annealing material plate at a distance, and at least in each case a gas inlet and gas outlet arranged on the base.
Haubenglühöfen dienen insbesondere zur Wärmebehandlung von Blechen, die zu Coils gewickelt sind. Letztere werden überein¬ ander auf der Glühgutplatte gestapelt, wobei ihr zentrales "Auge" einen Kanal in Fortsetzung der Zentralöffnung der Glüh¬ gutplatte bildet. Nach dem Aufsetzen der Haube auf eine frische Charge wird die im Ofen befindliche Luft gegen Schutzgas ausge¬ tauscht. Sodann beginnt die Glühbehandlung, wobei das Gebläse das Gas zentral von oben nach unten ansaugt und seitlich in den Ringraum zwischen dem Glühgut und der Haube fördert.Hood annealing furnaces are used in particular for the heat treatment of sheets that are wound into coils. The latter are stacked one above the other on the annealing material plate, with its central "eye" forming a channel in the continuation of the central opening of the annealing material plate. After the hood has been placed on a fresh batch, the air in the furnace is exchanged for protective gas. The annealing treatment then begins, the fan sucking the gas centrally from top to bottom and conveying it laterally into the annular space between the annealing material and the hood.
Für jede Charge ist also mindestens ein Austausch der Atmo¬ sphäre des Haubenglühofens erforderlich. Wird mit Wasserstoff gearbeitet, so vervielfachen sich diese Vorgänge. Vor Beginn des Aufheizens muß die Luft aus dem Ofen ausgetrieben werden. Dies geschieht durch Einblasen von Stickstoff. Anschließend er¬ folgt die Füllung mit Wasserstoff, wobei der Stickstoff ausge¬ trieben wird. Nach Beendigung der Glühbehandlung muß erst der Wasserstoff durch Einblasen von Stickstoff ausgetrieben werden, bevor die Haube abgenommen werden kann.At least one exchange of the atmosphere of the bell annealing furnace is therefore required for each batch. If you work with hydrogen, these processes multiply. The air must be expelled from the oven before heating up. This is done by blowing in nitrogen. The filling with hydrogen then takes place, the nitrogen being expelled. After the annealing treatment has ended, the hydrogen must first be expelled by blowing in nitrogen before the hood can be removed.
Beim Austausch der Atmosphäre wird das frische Gas unter¬ halb des Gebläses in den Ofen eingeblasen und vom Gebläse in den Ringraum zwischen dem Glühgut und der Haube gefördert. Gleichzeitig wird das entstehende Gasgemisch durch den Gasaus¬ laß abgeführt. Der Gaseintrag beim Austausch der Atmosphäre ist ganz er¬ heblich. Der Volumenstrom beträgt 100 bis 180 m-Vh, und zwar im Normalfall für eine Dauer von 20 bis 40 Minuten. Dies setzt al¬ lerdings die volle Funktionsfähigkeit des Gebläses voraus. Fällt das Gebläse aus, so beträgt die Spühlzeit ca. 24 Stunden. Dieser Verlust an Betriebszeit fällt' schwer ins Gewicht. Hinzu kommt ein nicht unerheblicher Gasverbrauch.When the atmosphere is exchanged, the fresh gas is blown into the furnace below the blower and conveyed by the blower into the annular space between the annealing material and the hood. At the same time, the resulting gas mixture is discharged through the gas outlet. The gas input during the exchange of the atmosphere is quite considerable. The volume flow is 100 to 180 m-Vh, normally for a period of 20 to 40 minutes. However, this presupposes the full functionality of the fan. If the fan fails, the rinsing time is approx. 24 hours. This loss of operating time is' great weight. There is also a not inconsiderable gas consumption.
Der Erfindung liegt die Aufgabe zugrunde, hier Abhilfe zu schaffen und einen wirtschaftlicheren, vor allem rascheren Aus¬ tausch der Atmosphäre zu ermöglichen.The object of the invention is to remedy this and to enable a more economical, above all faster, exchange of the atmosphere.
Zur Lösung dieser Aufgabe ist das Verfahren nach der Erfin¬ dung dadurch gekennzeichnet, daß das frische Gas als nach oben gerichteter Hochgeschwindigkeitsstrahl in einen nach oben führenden Strömungsweg eingeblasen wird und daß für die Geschwindigkeit des Strahls folgende Beziehung gilt:To achieve this object, the method according to the invention is characterized in that the fresh gas is blown into a flow path leading upwards as a high-speed jet and that the following relationship applies to the speed of the jet:
K-Vf-MA 22,4-ps-A wobeiKV f -M A 22.4-p s -A where
Vf = freies Ofenraumvolumen in LiterVf = free furnace space volume in liters
MA = Molgewicht des auszuspülenden Gases in g/mol ps = Dichte des frischen Gases in g/m3 M A = molecular weight of the gas to be flushed out in g / mol p s = density of the fresh gas in g / m 3
(die Daten gelten für den Normzustand)(the data apply to the normal state)
A = Eintrittsquerschnitt des frischen Gases in m2 K = Faktor mit dem Wert >. 1, vorzugsweise 6.A = inlet cross-section of the fresh gas in m 2 K = factor with the value>. 1, preferably 6.
Dabei kann es u.U. vorteilhaft sein, den Hochgeschwindigkeitsstrahl pulsierend zu erzeugen.It may be be advantageous to generate the high-speed beam pulsating.
Die erfindungsgemäße Vorrichtung kennzeichnet sich dadurch, daß der Gaseinlaß als nach oben gerichtete Düse ausgebildet ist, die in einem nach oben führenden Strömungsweg mündet.The device according to the invention is characterized in that the gas inlet is designed as an upwardly directed nozzle which opens into an upwardly flowing flow path.
Die Erfindung basiert auf der Erkenntnis, daß die Geschwindigkeit des eintretenden Strahls den Austauschvorgang maßgeblich beeinflußt und für die Optimierung der Geschwindigkeit die Dichte des auszuspülenden Gases und die The invention is based on the knowledge that the speed of the incoming jet significantly influences the exchange process and for the optimization of the speed the density of the gas to be flushed out and the
Sehr gute Ergebnisse wurden mit einer Glattstrahldüse von konstantem Durchmesser erzielt. Denkbar sind allerdings auch Düsen mit Einschnührungen.Very good results were achieved with a smooth jet nozzle of constant diameter. However, nozzles with constrictions are also conceivable.
Der Hochgeschwindigkeitsstrahl kann durch die Zentralöff¬ nung der Glühplatte hindurch in den von den "Augen" der Coils gebildeten zentralen Kanal hineingerichtet werden. Dabei bietet es sich an, die Welle des Gebläses hohl auszubilden und, ggf. unter entsprechender Verlängerung, als Düse einzusetzen.The high-speed beam can be directed through the central opening of the glow plate into the central channel formed by the "eyes" of the coils. It makes sense to make the shaft of the blower hollow and, if necessary with a corresponding extension, to use it as a nozzle.
Vorteilhafter kann es sein, die Düse in dem Ringraum zwi¬ schen dem Glühgut und der Haube münden zu lassen, da hier be¬ sonders günstige Zuström- und Ansaugverhältnisse herrschen. Dies gilt insbesondere dann, wenn, wie es in Weiterbildung der Erfindung vorgeschlagen wird, das Verhältnis von Abstand zwi¬ schen der Düsenmitte und der Haube zu Düsenaustrittsdurchmesser zwischen 2,5 und 8 liegt. Handelt es sich beispielsweise darum, H2 gegen N2 auszutauschen, so ist das Verhältnis vorzugsweise >7,5.It can be more advantageous to let the nozzle open into the annulus between the annealing material and the hood, since there are particularly favorable inflow and suction conditions. This applies in particular if, as is proposed in a development of the invention, the ratio of the distance between the center of the nozzle and the hood to the nozzle outlet diameter is between 2.5 and 8. If, for example, it is a question of exchanging H 2 for N2, the ratio is preferably> 7.5.
Vorteilhafterweise mündet die Düse in Höhe der Glühgutplat¬ te, wobei der Düsenmündung eine Anströmlänge mit konstantem Durchmesser vorgeschaltet ist, die etwa dem 5fachen des Düsen¬ austrittsdurchmessers entspricht. Es wurde gefunden, daß auf diese Weise sehr günstige Strömungsverhältnisse erzielt werden können.The nozzle advantageously opens at the level of the annealing material plate, the nozzle mouth being preceded by a flow length with a constant diameter which corresponds approximately to 5 times the nozzle outlet diameter. It has been found that very favorable flow conditions can be achieved in this way.
Vorzugsweise beträgt die Düsenaustrittsfläche ca. 10 % der Fläche des Gasauslasses. Auch diese Maßnahme ist geeignet, den Spülvorgang zu fördern.The nozzle exit area is preferably approximately 10% of the area of the gas outlet. This measure is also suitable for promoting the rinsing process.
Dabei wird der Gasauslaß vorzugsweise in dem Ringraum zwi¬ schen dem Glühgut und der Haube diametral gegenüber der Düse angeordnet. Sind mehrere Gasauslässe und Düsen vorgesehen, so werden diese jeweils auf einem gemeinsamen Sektor angeordnet, wobei die Sektoren einander gegenüber liegen. In jedem Falle wird eine Strömung erzwungen, die im wesentlichen großflächig der Haubenkontur folgt. Vorzugsweise ist der Gasauslaß von einem dem Gebläse zuge¬ ordneten Leitblech abgeschirmt, so daß er vor allen Dingen die haubennahe Strömung erfaßt, wobei quergerichtete, kurzschlußar¬ tige Strömungen weitgehend abgewiesen werden.The gas outlet is preferably arranged in the annular space between the annealing material and the hood diametrically opposite the nozzle. If several gas outlets and nozzles are provided, these are each arranged on a common sector, the sectors being opposite one another. In any case, a flow is forced which essentially follows the hood contour over a large area. The gas outlet is preferably shielded by a baffle assigned to the blower, so that it detects, above all, the flow close to the hood, with transverse, short-circuit-like flows being largely rejected.
Als erfindungswesentlich offenbart gelten auch solche Kom¬ binationen der erfindungsgemäßen Merkmale, die von den vorste¬ hend diskutierten Verknüpfungen abweichen.Combinations of the features according to the invention that deviate from the links discussed above are also considered to be disclosed as essential to the invention.
Die Erfindung wird im folgenden anhand eines bevorzugten Ausführungsbeispiels im Zusammenhang mit der beiliegenden Zeichnung näher erläutert. Die Zeichnung zeigt einen schemati¬ schen Vertikalschnitt durch einen Haubenglühofen nach der Er¬ findung.The invention is explained below with reference to a preferred embodiment in connection with the accompanying drawings. The drawing shows a schematic vertical section through a bell annealer according to the invention.
Der Haubenglühofen weist einen Sockel 1 mit einer Glühgut¬ platte 2 auf. Letztere trägt übereinander gestapelte Coils 3, im vorliegenden Falle vier an der Zahl. Deren "Augen" bildenden einen zentralen Kanal 4, der sich an eine Zentralöffnung 5 der Glühglutplatte 2 anschließt. Unterhalb der Zentralöffnung 5 ar¬ beitet ein Gebläse 6. Die Coils 3 und die Glühgutplatte 2 wer¬ den unter Bildung eines Ringraums 7 von einer Haube 8 abge¬ deckt.The bell annealer has a base 1 with an annealing plate 2. The latter carries coils 3 stacked one above the other, in the present case four in number. Their "eyes" form a central channel 4, which connects to a central opening 5 of the glow ember plate 2. A fan 6 works below the central opening 5. The coils 3 and the annealing material plate 2 are covered by a hood 8 to form an annular space 7.
Der Haubenglühofen weist einen Gaseinlaß in Form einer nach oben gerichteten Düse 9 auf, die in den Ringraum 7 mündet. Sie erzeugt einen gepulsten, nach oben gerichteten Hochgeschwindig¬ keitsstrahl, dessen Geschwindigkeit 75 m/s beträgt, und zwar bei einem Volumenstrom von 130 m*--/h. Es handelt sich um eine Glattstrahldüse mit einem Durchmesser von 25 mm, wobei die Düse auf der Höhe der Glühgutplatte 2 mündet. Das Verhältnis von Ab¬ stand zwischen der Düsenmitte und der Haube zu Düsendurchmesser beträgt 5.The bell annealer has a gas inlet in the form of an upwardly directed nozzle 9 which opens into the annular space 7. It generates a pulsed, upward-directed high-speed jet, the speed of which is 75 m / s, specifically at a volume flow of 130 m * - / h. It is a smooth jet nozzle with a diameter of 25 mm, the nozzle opening at the level of the annealing material plate 2. The ratio of the distance between the center of the nozzle and the hood to the nozzle diameter is 5.
Diametral gegenüber der Düse 9 und ebenfalls im Bereich des Ringraums 7 ist ein Gasauslaß 10 vorgesehen, dessen Durchmesser 80 mm beträgt. Der Gasauslaß wird von einem dem Gebläse 6 zuge¬ ordneten Leitblech 11 abgeschirmt. Mit dieser Anordnung ist es möglich, die ^-Atmosphäre des Ofens mit N2 bis auf einen Restgehalt von 4 % in 6 Minuten zu spülen, wobei es keine wesentliche Rolle spielt, ob das Gebläse mitläuft oder nicht.Diametrically opposite the nozzle 9 and also in the area of the annular space 7, a gas outlet 10 is provided, the diameter of which is 80 mm. The gas outlet is shielded by a baffle 11 assigned to the blower 6. With this arrangement, it is possible to purge the ^ atmosphere of the furnace with N2 to a residual content of 4% in 6 minutes, regardless of whether the fan is running or not.
Im Rahmen der Erfindung sind durchaus Abwandlungsmöglich¬ keiten gegeben. So können die Abmaß- und Verfahrensparameter in Grenzen variiert werden, so lange ein nach oben gerichteter Hochgeschwindigkeitsstrahl mit den gewünschten Ansaug-, Misch- und Spüleigenschaften erzeugt werden kann, dessen Geschwindig¬ keit der erfindungsgemäßen Beziehung entspricht. Dieser Strahl kann auch beispielsweise durch die Welle des Gebläses 6 hin¬ durch in den zentralen Kanal 4 gerichtet werden. Ferner besteht die Möglichkeit, mit mehreren Gaseinlässen und ggf. auch mehre¬ ren Gasauslässen zu arbeiten, wobei allerdings die diametrale Anordnung erhalten bleiben sollte. Modifications are quite possible within the scope of the invention. The dimensional and process parameters can thus be varied within limits, as long as an upward high-speed jet with the desired suction, mixing and rinsing properties can be generated, the speed of which corresponds to the relationship according to the invention. This jet can also be directed, for example, through the shaft of the fan 6 into the central duct 4. There is also the possibility of working with several gas inlets and possibly also several gas outlets, although the diametrical arrangement should be retained.

Claims

A n s p r ü c h e Expectations
1. Verfahren zum Austauschen der Atmosphäre in einem Haubenglühofen, wobei das frische Gas unten in den Ofen eingeblasen und das sich bildende Gasgemisch unten aus dem Ofen abgeführt wird, d a d u r c h g e k e n n z e i c h n e t , daß das frische Gas als nach oben gerichteter Hochgeschwindigkeitsstrahl in einen nach oben führenden Strömungsweg eingeblasen wird und daß für die Geschwindigkeit des Strahls folgende Beziehung gilt:1. A method for exchanging the atmosphere in a bell annealer, wherein the fresh gas is blown into the bottom of the furnace and the gas mixture that is formed is discharged from the bottom of the furnace, characterized in that the fresh gas is blown as an upward high-speed jet into an upward flow path and that the following relationship applies to the velocity of the jet:
K'Vf-MA K'Vf-M A
22,4-ps-A wobei22.4-p s -A where
Vf = freies Ofenraumvolumen in LiterVf = free furnace space volume in liters
MA = Molgewicht des auszuspülenden Gases in g/mol ps = Dichte des frischen Gases in g/m3 M A = molecular weight of the gas to be flushed out in g / mol p s = density of the fresh gas in g / m 3
(die Daten gelten für den Normzustand)(the data apply to the normal state)
A = Eintrittsquerschnitt des frischen Gases in m2 K = Faktor mit dem Wert >. 1, vorzugsweise 6.A = inlet cross-section of the fresh gas in m 2 K = factor with the value>. 1, preferably 6.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß der Hochgeschwindigkeitsstrahl pulsierend erzeugt wird.2. The method according to claim 1, characterized in that the high-speed jet is generated pulsating.
3. Haubenglühofen mit einem Sockel (1), einer auf dem Sockel angeordneten Glühgutplatte (2) zum Tragen des Glühgutes (3), einem unterhalb einer Zentralöffnung (5) der Glühgutplatte angeordneten Gebläse (6), einer das Glühgut und die Glühgutplatte mit Abstand umgebenden Haube(8) und je mindenstens einem am Sockel angeordneten Gaseinlaß und Gasauslaß ( 10) , d a d u r c h g e k e n n z e i c h n e t , daß der Gaseinlaß als nach oben gerichtete Düse (9) ausge¬ bildet ist, die in einem nach oben führenden Strömungsweg mün¬ det.3. Bell annealing furnace with a base (1), an annealing material plate (2) arranged on the base for carrying the annealing material (3), a fan (6) arranged below a central opening (5) of the annealing material plate, one of the annealing material and the annealing material plate at a distance surrounding hood (8) and at least one gas inlet and gas outlet (10) arranged on the base, characterized in that the gas inlet is formed as an upwardly directed nozzle (9) which opens into an upward flow path.
4. Haubenglühofen nach Anspruch 3, dadurch gekennzeichnet, daß die Düse (9) in dem Ringraum (7) zwischen dem Glühgut (3) und der Haube (8) mündet.4. bell annealer according to claim 3, characterized in that the nozzle (9) in the annular space (7) between the annealing material (3) and the hood (8) opens.
5. Haubenglühofen nach Anspruch 4, dadurch gekennzeichnet, daß das Verhältnis von Abstand zwischen der Düsenmitte und der Haube (8) zu Düsenaustrittsdurchmesser zwischen 2,5 und 8 liegt.5. bell annealer according to claim 4, characterized in that the ratio of the distance between the center of the nozzle and the hood (8) to the nozzle outlet diameter is between 2.5 and 8.
6. Haubenglühofen nach einem der Ansprüche 3 bis 5, dadurch gekennzeichnet, daß die Düse (9) in Höhe der Glühgutplatte (2) mündet, wobei der Düsenmündung eine Anströmlänge mit konstantem Durchmesser vorgeschaltet ist, die etwa dem Fünffachen des Düsenaustrittsdurchmessers entspricht.6. bell annealer according to one of claims 3 to 5, characterized in that the nozzle (9) opens at the level of the annealing plate (2), the nozzle mouth being connected upstream of an inflow length of constant diameter which corresponds to approximately five times the nozzle outlet diameter.
7. Haubenglühofen nach einem der Ansprüche 3 bis 6, dadurch gekennzeichnet, daß die Düsenaustrittsfläche ca. 10% der Fläche des Gasauslasses (10) beträgt.7. bell annealer according to one of claims 3 to 6, characterized in that the nozzle exit area is approximately 10% of the area of the gas outlet (10).
8. Haubenglühofen nach einem der Ansprüche 3 bis 7, dadurch gekennzeichnet, daß der Gasauslaß (10) im Bereich des Ringraums (7) zwischen dem Glühgut (3) und der Haube (8) diametral gegenüber der Düse (9) angeordnet ist.8. bell annealer according to one of claims 3 to 7, characterized in that the gas outlet (10) in the region of the annular space (7) between the annealing material (3) and the hood (8) is arranged diametrically opposite the nozzle (9).
9. Haubenglühofen nach Anspruch 8, dadurch gekennzeichnet, daß der Gasauslaß (10) von einem dem Gebläse (6) zugeordneten Leitblech (11) abgeschirmt ist. 9. bell annealer according to claim 8, characterized in that the gas outlet (10) from a blower (6) associated baffle (11) is shielded.
EP94926826A 1993-08-19 1994-08-06 Process and device for heat treatment in a hood type annealing furnace Expired - Lifetime EP0714452B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4327975A DE4327975A1 (en) 1993-08-19 1993-08-19 Method and device for exchanging the atmosphere in a bell annealer
DE4327975 1993-08-19
PCT/EP1994/002619 WO1995005487A1 (en) 1993-08-19 1994-08-06 Process and device for exchanging the atmosphere in a hood type annealing furnace

Publications (2)

Publication Number Publication Date
EP0714452A1 true EP0714452A1 (en) 1996-06-05
EP0714452B1 EP0714452B1 (en) 1999-01-13

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Application Number Title Priority Date Filing Date
EP94926826A Expired - Lifetime EP0714452B1 (en) 1993-08-19 1994-08-06 Process and device for heat treatment in a hood type annealing furnace

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US (1) US5730930A (en)
EP (1) EP0714452B1 (en)
CN (1) CN1043058C (en)
AT (1) ATE175725T1 (en)
DE (2) DE4327975A1 (en)
RU (1) RU2127325C1 (en)
WO (1) WO1995005487A1 (en)

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RU2127325C1 (en) 1999-03-10
CN1043058C (en) 1999-04-21
EP0714452B1 (en) 1999-01-13
DE4327975A1 (en) 1995-02-23
WO1995005487A1 (en) 1995-02-23
ATE175725T1 (en) 1999-01-15
US5730930A (en) 1998-03-24
CN1138352A (en) 1996-12-18
DE59407661D1 (en) 1999-02-25

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