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EP0049488B1 - Method of and apparatus for decarburizing or neutrally annealing metal workpieces - Google Patents

Method of and apparatus for decarburizing or neutrally annealing metal workpieces Download PDF

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Publication number
EP0049488B1
EP0049488B1 EP81107820A EP81107820A EP0049488B1 EP 0049488 B1 EP0049488 B1 EP 0049488B1 EP 81107820 A EP81107820 A EP 81107820A EP 81107820 A EP81107820 A EP 81107820A EP 0049488 B1 EP0049488 B1 EP 0049488B1
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Prior art keywords
gas
furnace
oxygen
organic liquid
inert gas
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German (de)
French (fr)
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EP0049488A1 (en
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Reinhard Strigl
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Linde GmbH
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Linde GmbH
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    • 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
    • C21D3/00—Diffusion processes for extraction of non-metals; Furnaces therefor
    • C21D3/02—Extraction of non-metals
    • C21D3/04—Decarburising
    • 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
    • C21D1/76—Adjusting the composition of the atmosphere

Definitions

  • the invention relates to a method and a device for the decarburizing or carbon-neutral annealing of metal parts, the metal parts being exposed to high temperatures in an oven and an inert gas and an organic liquid which essentially decomposes into carbon monoxide and hydrogen at high temperatures, be initiated.
  • the annealing takes place at temperatures of approx. 650 to 1 050 ° C., the furnace atmosphere formed by the introduced gas withdrawing carbon from the annealing material or preventing decarburization or carburizing.
  • gas mixtures are conventionally used which are obtained by partially combusting a fuel gas (natural gas, propane) in a gas generator (see Gas Heat International, Volume 27, 1978, No. 9, pages 463 to 468).
  • the proportion of carbon monoxide, hydrogen, carbon dioxide, methane and nitrogen in the gas mixture depends, among other things, on the starting fuel and the gas mixture production process.
  • the proportions of the individual gases in the gas mixture can only be set within narrow limits due to the little variable combustion ratio.
  • the composition of the gas mixture to be introduced into the furnace cannot therefore be satisfactorily adapted to the different furnace conditions which are required for the individual annealing processes with the aid of the known processes.
  • the amount of gas produced in the gas generator per unit of time can only be regulated between 60% and 100% of the maximum generator output. This leads to high fuel or gas consumption, since excess gas has to be flared off.
  • FR-A-2 450 878 describes a device for generating a gas atmosphere.
  • the gas atmosphere is formed exclusively from an inert gas and an alcohol. Both the alcohol and the inert gas are fed into the furnace under pressure.
  • the invention is therefore based on the object of specifying a method with which a gas mixture which can be adapted in its composition to different annealing methods can be provided economically.
  • This object is achieved in that the organic liquid is sucked in and sprayed by an oxygen-containing gas via an injector, the jet formed is surrounded by an inert gas which flows essentially parallel to it and envelops it in the form of a jacket and is introduced into the furnace.
  • an organic liquid is introduced into the furnace in the form of fine droplets. Under the high temperatures prevailing in the furnace, it splits into carbon monoxide and hydrogen. Some or all of these gases react with the oxygen in the oxygen-containing gas, which is used to spray the organic liquid, into carbon dioxide and water. A gas atmosphere consisting of carbon monoxide, hydrogen, carbon dioxide, water and the inert jacket gas is thus established in the furnace chamber.
  • the proportions of the individual components in the gas atmosphere in the furnace space can be adjusted within wide limits, so that the gas atmosphere meets the desired furnace conditions - In particular with regard to the dew point and the carbon dioxide content - can be optimally adjusted.
  • a major advantage of the method according to the invention is that it does not require gas generators. In addition to investment costs for the gas generator, there are also no costs for a washing device or for a cleaning column, and the gas losses that previously occurred when the gas mixture produced in the gas generator was washed.
  • the furnace atmosphere only forms after or when the gas mixture is introduced into the furnace. Since the gas reacts with the annealing material in statu nascendi, the reactivity of the furnace atmosphere is therefore considerably higher than, for example, that of a gas mixture generated in the gas generator and subsequently cleaned. For this reason, gas can be saved in the process according to the invention. This also means that the glow time is reduced.
  • Organic liquids that split into carbon monoxide and hydrogen when introduced into the heated furnace are, for example, alcohols. These are therefore particularly suitable in the process according to the invention. Because of the availability and the low production costs, methanol is preferably used in the process according to the invention.
  • Pure oxygen or an oxygen-nitrogen mixture is advantageously used as the oxygen-containing gas.
  • Compressed air has also proven to be completely suitable for the purpose according to the invention proven sufficiently. When these gases or gas mixtures are used, there is also no need to moisten the gas mixture to be introduced into the furnace.
  • the amount of inert gas that envelops the jet formed in the injector is freely controllable, a certain furnace pressure can be maintained and a desired dew point can be set in an advantageous embodiment of the inventive concept via the amount of inert gas serving as the jacket gas.
  • an addition device consisting of coaxial tubes opens into the furnace, a line for an organic liquid opening into the inner tube and a line for an inert gas opening into the outer tube.
  • the line for an organic liquid advantageously opens into the inner tube via a mixing device, via which a line for an oxygen-containing gas also opens into the inner tube.
  • a gas mixture which is variable in its composition and adaptable to the desired conditions within the furnace in terms of decarburization and redox effect can be provided with the process according to the invention, which is moreover more economical to use and cheaper than, for example, forming gas or ammonia. Fission gas.
  • a pipe 10 opens into a furnace 1, of which only part of the furnace wall is shown in the drawing. Via an T-piece 5, a flange 6, and a stuffing box head 7 with a seal 8 and a union nut 9, an injector 2 is on a pipe 10 connected.
  • the injector 2 projects coaxially and at a distance from the tube wall approximately up to the height of the inner wall of the furnace 1 into tube 10.
  • the injector 2 has two inputs 3 and 4. Via input 3, the injector is fed in a controllable manner with the oxygen-containing gas via a line (not shown).
  • the oxygen-containing gas should be compressed air.
  • the air enters a mixing nozzle at high speed and sucks in methanol via inlet 4 and a line (also not shown).
  • the mist-like mixture of air and fine methanol droplets flows within the injector 2 at high speed to the furnace chamber 1 and enters it in a jet.
  • the jet Before entering the furnace, the jet is surrounded by an inert gas, in the exemplary embodiment nitrogen, in the form of a jacket. The nitrogen is introduced into tube 10 via tube 11 and T-piece 5.
  • the device according to the invention is connected directly to the heat treatment furnace.
  • the nitrogen jacket gas flow which flows around the injector nozzle 12 can be regulated in throughput.
  • the reaction gas composition can thus be adapted to the desired furnace conditions in terms of its carbon monoxide, carbon dioxide, hydrogen, water and nitrogen content.
  • a two-component nozzle concentrically in an inlet pipe through which the nitrogen is passed.
  • the two-component nozzle is charged with methanol and with compressed air, nitrogen-oxygen mixtures, etc. as atomizing gas.
  • the glow time is 35 min.
  • the method according to the invention is particularly suitable for the decarburizing annealing of electrical sheets. However, it can also be used with advantage for bright annealing of steel sheets, copper, semi-finished bronze products and for the oxidizing annealing of stainless steels.

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  • 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)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
  • Furnace Details (AREA)

Description

Die Erfindung betrifft ein Verfahren und eine Vorrichtung zum entkohlenden oder kohlungsneutralen Glühen von Metallteilen, wobei die Metallteile in einem Ofen hohen Temperaturen ausgesetzt werden und in den Ofen ein Inertgas sowie eine organische Flüssigkeit, die sich bei hohen Temperaturen im wesentlichen in Kohlenmonoxid und Wasserstoff zersetzt, eingeleitet werden.The invention relates to a method and a device for the decarburizing or carbon-neutral annealing of metal parts, the metal parts being exposed to high temperatures in an oven and an inert gas and an organic liquid which essentially decomposes into carbon monoxide and hydrogen at high temperatures, be initiated.

Das Glühen findet bei Temperaturen von ca. 650 bis 1 050 °C statt, wobei die durch das eingeleitete Gas gebildete Ofenatmosphäre dem Glühgut Kohlenstoff entzieht bzw. ein Entkohlen oder Aufkohlen verhindert. Zum nichtaufkohlenden Glühen von Metallteilen werden herkömmlicherweise Gasgemische eingesetzt, die durch Teilverbrennung eines Brenngases (Erdgas, Propan) in einem Gasgenerator gewonnen werden (siehe Gas Wärme International, Band 27, 1978, Heft 9, Seiten 463 bis 468). Der Anteil von Kohlenmonoxid, Wasserstoff, Kohlendioxid, Methan und Stickstoff am Gasgemisch ist unter anderem abhängig von Ausgangsbrennstoff und dem Gasgemisch-Herstellungsverfahren. Für ein bestimmtes Herstellungsverfahren sind aufgrund des nur wenig variablen Verbrennungsverhältnisses auch die Anteile der einzelnen Gase am Gasgemisch nur in engen Grenzen einstellbar. Die Zusammensetzung des in den Ofen einzuleitenden Gasgemisches ist daher den unterschiedlichen Ofenbedingungen, die für die einzelnen Glühverfahren erforderlich sind, mit Hilfe der bekannten Verfahren nicht in zufriedenstellender Weise anzupassen. Außerdem ist die im Gasgenerator pro Zeiteinheit hergestellte Gasmenge nur zwischen 60% und 100 % der maximalen Generatorleistung regelbar. Dies führt zu einem hohen Brennstoff- bzw. Gasverbrauch, da überschüssiges Gas abgefackelt werden muß.The annealing takes place at temperatures of approx. 650 to 1 050 ° C., the furnace atmosphere formed by the introduced gas withdrawing carbon from the annealing material or preventing decarburization or carburizing. For the non-carburizing annealing of metal parts, gas mixtures are conventionally used which are obtained by partially combusting a fuel gas (natural gas, propane) in a gas generator (see Gas Heat International, Volume 27, 1978, No. 9, pages 463 to 468). The proportion of carbon monoxide, hydrogen, carbon dioxide, methane and nitrogen in the gas mixture depends, among other things, on the starting fuel and the gas mixture production process. For a certain manufacturing process, the proportions of the individual gases in the gas mixture can only be set within narrow limits due to the little variable combustion ratio. The composition of the gas mixture to be introduced into the furnace cannot therefore be satisfactorily adapted to the different furnace conditions which are required for the individual annealing processes with the aid of the known processes. In addition, the amount of gas produced in the gas generator per unit of time can only be regulated between 60% and 100% of the maximum generator output. This leads to high fuel or gas consumption, since excess gas has to be flared off.

Durch die FR-A-2 450 878 ist eine Vorrichtung zur Erzeugung einer Gasatmosphäre beschrieben. Dabei wird die Gasatmosphäre ausschließlich aus einem inerten Gas und einem Alkohol gebildet. Sowohl der Alkohol als auch das inerte Gas werden unter Druck in den Ofen geleitet.FR-A-2 450 878 describes a device for generating a gas atmosphere. The gas atmosphere is formed exclusively from an inert gas and an alcohol. Both the alcohol and the inert gas are fed into the furnace under pressure.

Weiterhin ist es bekannt, angefeuchtetes Ammoniak-Spaltgas oder angefeuchtete Stickstoff-Wasserstoff-Gemische mit einem festen Stickstoff-Wasserstoff-Volumenverhältnis als Gasgemisch zum Glühen von Metallteilen einzusetzen. Stickstoff-Wasserstoff-Gemische sind jedoch teuer, so daß ihre Verwendung bisher nur gerechtfertigt war, wenn hohe Qualitätsansprüche an die geglühten Metallteile gestellt wurden, die mit den in einem Gasgenerator hergestellten Gasgemischen nicht zu erreichen waren.It is also known to use moistened ammonia cracked gas or moistened nitrogen-hydrogen mixtures with a fixed nitrogen-hydrogen volume ratio as a gas mixture for annealing metal parts. However, nitrogen-hydrogen mixtures are expensive, so that their use has so far only been justified if high demands were placed on the annealed metal parts, which could not be achieved with the gas mixtures produced in a gas generator.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren anzugeben, mit dem auf wirtschaftliche Weise ein in seiner Zusammensetzung an unterschiedliche Glühverfahren anpaßbares Gasgemisch bereitgestellt werden kann.The invention is therefore based on the object of specifying a method with which a gas mixture which can be adapted in its composition to different annealing methods can be provided economically.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die organische Flüssigkeit von einem sauerstoffhaltigen Gas über einen Injektor angesaugt und versprüht wird, der gebildete Strahl von einem im wesentlichen parallel zu diesem strömenden und diesen mantelförmig einhüllenden inerten Gas umgeben und in den Ofen eingeleitet wird.This object is achieved in that the organic liquid is sucked in and sprayed by an oxygen-containing gas via an injector, the jet formed is surrounded by an inert gas which flows essentially parallel to it and envelops it in the form of a jacket and is introduced into the furnace.

Erfindungsgemäß wird eine organische Flüssigkeit in Form feiner Tröpfchen in den Ofen eingeleitet. Unter den im Ofen herrschenden hohen Temperaturen spaltet sich diese in Kohlenmonoxid und Wasserstoff. Diese Gase setzen sich teilweise oder ganz mit dem Sauerstoff des sauerstoffhaltigen Gases, das zum Versprühen der organischen Flüssigkeit dient, in Kohlendioxid und Wasser um. Im Ofenraum stellt sich somit eine aus Kohlenmonoxid, Wasserstoff, Kohlendioxid, Wasser sowie dem inerten Mantelgas bestehende Gasatmosphäre ein. Da die organische Flüssigkeit, das sauerstoffhaltige Gas sowie das inerte Gas aus eigenen Vorratsspeichern entnommen und der Fluß dieser Fluide daher leicht geregelt werden kann, sind die Anteile der einzelnen Komponenten an der Gasatmosphäre im Ofenraum innerhalb weiter Grenzen einstellbar, so daß die Gasatmosphäre den gewünschten Ofenbedingungen - insbesondere hinsichtlich des Taupunktes und des Kohlendioxidgehaltes - optimal angepaßt werden kann.According to the invention, an organic liquid is introduced into the furnace in the form of fine droplets. Under the high temperatures prevailing in the furnace, it splits into carbon monoxide and hydrogen. Some or all of these gases react with the oxygen in the oxygen-containing gas, which is used to spray the organic liquid, into carbon dioxide and water. A gas atmosphere consisting of carbon monoxide, hydrogen, carbon dioxide, water and the inert jacket gas is thus established in the furnace chamber. Since the organic liquid, the oxygen-containing gas and the inert gas can be taken from our own storage facilities and the flow of these fluids can therefore be easily regulated, the proportions of the individual components in the gas atmosphere in the furnace space can be adjusted within wide limits, so that the gas atmosphere meets the desired furnace conditions - In particular with regard to the dew point and the carbon dioxide content - can be optimally adjusted.

Ein wesentlicher Vorteil des erfindungsgemäßen Verfahrens besteht darin, daß es keine Gasgeneratoren erfordert. Neben Investitionskosten für den Gasgenerator entfallen ebenso die Kosten für eine Waschvorrichtung bzw. für eine Reinigungssäule sowie die Gasverluste, die sich bisher bei einer Wäsche des im Gasgenerator hergestellten Gasgemisches einstellten. Erfindungsgemäß bildet sich die Ofenatmosphäre erst nach bzw. beim Einleiten des Gasgemisches in den Ofen. Da das Gas mithin in statu nascendi mit dem Glühgut reagiert, ist die Reaktivität der Ofenatmosphäre daher wesentlich höher, als beispielsweise die eines im Gasgenerator erzeugten und anschließend gereinigten Gasgemisches. Aus diesem Grund läßt sich beim erfindungsgemäßen Verfahren Gas einsparen. Außerdem bedingt dieser Sachverhalt eine Verkürzung der Glühzeit.A major advantage of the method according to the invention is that it does not require gas generators. In addition to investment costs for the gas generator, there are also no costs for a washing device or for a cleaning column, and the gas losses that previously occurred when the gas mixture produced in the gas generator was washed. According to the invention, the furnace atmosphere only forms after or when the gas mixture is introduced into the furnace. Since the gas reacts with the annealing material in statu nascendi, the reactivity of the furnace atmosphere is therefore considerably higher than, for example, that of a gas mixture generated in the gas generator and subsequently cleaned. For this reason, gas can be saved in the process according to the invention. This also means that the glow time is reduced.

Organische Flüssigkeiten, die sich beim Einleiten in den erhitzten Ofen in Kohlenmonoxid und Wasserstoff spalten, sind beispielsweise Alkohole. Diese eignen sich daher beim erfindungsgemäßen Verfahren besonders. Wegen der Verfügbarkeit und der geringen Herstellungskosten findet Methanol beim erfindungsgemäßen Verfahren bevorzugt Anwendung.Organic liquids that split into carbon monoxide and hydrogen when introduced into the heated furnace are, for example, alcohols. These are therefore particularly suitable in the process according to the invention. Because of the availability and the low production costs, methanol is preferably used in the process according to the invention.

Als sauerstoffhaltiges Gas werden mit Vorteil reiner Sauerstoff oder Sauerstoff-Stickstoff-Gemisch eingesetzt. Auch komprimierte Luft hat sich als für den erfindungsgemäßen Zweck völlig ausreichend erwiesen. Bei der Verwendung dieser Gase bzw. Gasgemische erübrigt sich zudem eine Anfeuchtung des in den Ofen einzuleitenden Gasgemisches.Pure oxygen or an oxygen-nitrogen mixture is advantageously used as the oxygen-containing gas. Compressed air has also proven to be completely suitable for the purpose according to the invention proven sufficiently. When these gases or gas mixtures are used, there is also no need to moisten the gas mixture to be introduced into the furnace.

Da die Menge des Inertgases, das den im Injektor gebildeten Strahl einhüllt, frei regelbar ist, kann in einer vorteilhaften Ausgestaltung des Erfindungsgedankens über die Menge des als Mantelgas dienenden inerten Gases ein bestimmter Ofendruck aufrechterhalten und ein gewünschter Taupunkt eingestellt werden.Since the amount of inert gas that envelops the jet formed in the injector is freely controllable, a certain furnace pressure can be maintained and a desired dew point can be set in an advantageous embodiment of the inventive concept via the amount of inert gas serving as the jacket gas.

In einer zur Durchführung des erfindungsgemäßen Verfahrens geeigneten Vorrichtung mündet in den Often eine aus koaxialen Rohren bestehende Zugabevorrichtung, wobei in das Innenrohr eine Leitung für eine organische Flüssigkeit mündet und in das Außenrohr eine Leitung für ein Inertgas mündet. Bei einer derartigen Vorrichtung mündet mit Vorteil die Leitung für eine organische Flüssigkeit über eine Mischvorrichtung in das Innenrohr, über die außerdem eine Leitung für ein sauerstoffhaltiges Gas in das Innenrohr mündet.In a device suitable for carrying out the method according to the invention, an addition device consisting of coaxial tubes opens into the furnace, a line for an organic liquid opening into the inner tube and a line for an inert gas opening into the outer tube. In the case of such a device, the line for an organic liquid advantageously opens into the inner tube via a mixing device, via which a line for an oxygen-containing gas also opens into the inner tube.

Zusammenfassend läßt sich feststellen, daß mit dem erfindungsgemäßen Verfahren ein in seiner Zusammensetzung variierbares und den gewünschten Bedingungen innerhalb des Ofens in Bezug auf Entkohlungs- und Redoxwirkung anpaßbares Gasgemisch bereitgestellt werden kann, das zudem wesentlich wirtschaftlicher einzusetzen und billiger ist, als beispielsweise Formiergas oder Ammoniak-Spaltgas.In summary, it can be stated that a gas mixture which is variable in its composition and adaptable to the desired conditions within the furnace in terms of decarburization and redox effect can be provided with the process according to the invention, which is moreover more economical to use and cheaper than, for example, forming gas or ammonia. Fission gas.

Im folgenden soll anhand einer schematischen Skizze ein Ausführungsbeispiel einer erfindungsgemäßen Vorrichtung beschrieben und das Verfahren erläutert werden.In the following, an exemplary embodiment of a device according to the invention is to be described with reference to a schematic sketch and the method is explained.

In einen Ofen 1, von dem in der Zeichnung lediglich ein Teil der Ofenwand dargestellt ist, mündet ein Rohr 10. Über ein T-Stück 5, einen Flansch 6, sowie einen Stopfbuchsenkopf 7 mit Dichtung 8 und Überwurfmutter 9 ist ein Injektor 2 an Rohr 10 angeschlossen. Der Injektor 2 ragt koaxial und mit Abstand zur Rohrwand etwa bis zur Höhe der Innenwand des Ofens 1 in Rohr 10 hinein.A pipe 10 opens into a furnace 1, of which only part of the furnace wall is shown in the drawing. Via an T-piece 5, a flange 6, and a stuffing box head 7 with a seal 8 and a union nut 9, an injector 2 is on a pipe 10 connected. The injector 2 projects coaxially and at a distance from the tube wall approximately up to the height of the inner wall of the furnace 1 into tube 10.

An das T-Stück ist ein weiteres Rohr 11 angeflanscht. Der Injektor 2 besitzt zwei Eingänge 3 und 4. Über Eingang 3 wird der Injektor über eine nicht dargestellte Leitung in regelbarer Weise mit dem sauerstoffhaltigen Gas gespeist. Im Ausführungsbeispiel soll das sauerstoffhaltige Gas komprimierte Luft sein. Die Luft tritt mit hoher Geschwindigkeit in eine Mischdüse und saugt dabei über Eingang 4 und eine ebenfalls nicht dargestellte Leitung Methanol an. Das nebelförmige Gemisch aus Luft und feinen Methanoltröpfchen strömt innerhalb des Injektors 2 mit hoher Geschwindigkeit zum Ofenraum 1 und tritt strahlförmig in diesen ein. Vor dem Eintritt in den Ofen wird der Strahl von einem inerten Gas, im Ausführungsbeispiel Stickstoff, mantelförmig umgeben. Der Stickstoff wird über Rohr 11 und T-Stück 5 in Rohr 10 eingeleitet. Die erfindungsgemäße Vorrichtung ist unmittelbar an den Wärmebehandlungsofen angeschlossen. Wie der Methanolfluß zur Injektordüse und der zur Verdüsung dienende Luftstrom ist auch der Stickstoff-Mantelgasstrom, der die Injektordüse 12 umspült, im Durchsatz regelbar. Damit kann die Reaktionsgaszusammensetzung in ihrem Kohlenmonoxid-, Kohlendioxid-, Wasserstoff-, Wasser- und Stickstoffgehalt den gewünschten Ofenbedingungen angepaßt werden.Another pipe 11 is flanged to the T-piece. The injector 2 has two inputs 3 and 4. Via input 3, the injector is fed in a controllable manner with the oxygen-containing gas via a line (not shown). In the exemplary embodiment, the oxygen-containing gas should be compressed air. The air enters a mixing nozzle at high speed and sucks in methanol via inlet 4 and a line (also not shown). The mist-like mixture of air and fine methanol droplets flows within the injector 2 at high speed to the furnace chamber 1 and enters it in a jet. Before entering the furnace, the jet is surrounded by an inert gas, in the exemplary embodiment nitrogen, in the form of a jacket. The nitrogen is introduced into tube 10 via tube 11 and T-piece 5. The device according to the invention is connected directly to the heat treatment furnace. Like the methanol flow to the injector nozzle and the air flow used for atomization, the nitrogen jacket gas flow which flows around the injector nozzle 12 can be regulated in throughput. The reaction gas composition can thus be adapted to the desired furnace conditions in terms of its carbon monoxide, carbon dioxide, hydrogen, water and nitrogen content.

Grundsätzlich ist es auch möglich, eine Zweistoffdüse konzentrisch in einem Einleitungsrohr anzubringen, durch das der Stickstoff geleitet wird. Die Zweistoffdüse wird mit Methanol und mit Preßluft, Stickstoff-Sauerstoff-Gemischen usw. als Zerstäubungsgas beschickt.In principle, it is also possible to mount a two-component nozzle concentrically in an inlet pipe through which the nitrogen is passed. The two-component nozzle is charged with methanol and with compressed air, nitrogen-oxygen mixtures, etc. as atomizing gas.

Beispielexample

Zum entkohlenden Glühen von Elektroblechen werden beispielsweise pro Zeiteinheit 1,5 m3 Preßluft in einen Glühofen eingeleitet, wobei über den Injektor 2,5 I Methanol angesaugt und versprüht werden. Dem so gebildeten Strahl wird Stickstoff als Mantelgas in einer Menge von 21 m3 zugegeben. Im Ofen stellt sich bei einem Druck von 10 mm WS eine Atmosphäre ein, die zu etwa 2 Vol.% Kohlenmonoxid, zu 3 Vol.% aus Kohlendioxid, zu 7 Vol.% aus Wasserstoff, zu 2 Vol.% aus Wasser und zu 86 Vol.% aus Stickstoff besteht. Die Glühzeit beträgt etwa 20 Minuten, der Taupunkt hat einen Wert von + 20 °C.For the decarburizing annealing of electrical sheets, for example, 1.5 m 3 of compressed air per unit of time are introduced into an annealing furnace, 2.5 l of methanol being sucked in and sprayed through the injector. Nitrogen is added to the jet thus formed as a jacket gas in an amount of 21 m 3 . At a pressure of 10 mm water pressure, an atmosphere is created in the furnace that contains approximately 2% by volume of carbon monoxide, 3% by volume of carbon dioxide, 7% by volume of hydrogen, 2% by volume of water and 86% Vol.% Consists of nitrogen. The glow time is about 20 minutes, the dew point is + 20 ° C.

Zum kohlungsneutralen Glühen werden z. B. 10 m3 N2 mit 3 % 02, 8 I Methanol, 6 m3 Stickstoff in den Glühofen eingeleitet. Die Ofenatmosphäre setzt sich etwa wie folgt zusammen :

Figure imgb0001
For carbon-neutral annealing z. B. 10 m 3 N 2 with 3% 0 2 , 8 I methanol, 6 m 3 nitrogen introduced into the annealing furnace. The furnace atmosphere is roughly as follows:
Figure imgb0001

Die Glühzeit beträgt 35 min.The glow time is 35 min.

Das erfindungsgemäße Verfahren eignet sich besonders zum entkohlenden Glühen von Elektroblechen. Es ist aber auch mit Vorteil zum Blankglühen von Stahlblechen, Kupfer, Bronzehalbzeug sowie zum oxidierenden Glühen von Edelstählen einsetzbar.The method according to the invention is particularly suitable for the decarburizing annealing of electrical sheets. However, it can also be used with advantage for bright annealing of steel sheets, copper, semi-finished bronze products and for the oxidizing annealing of stainless steels.

Claims (6)

1. A method for decarburizing or neutrally annealing metal workpieces, in which the metal workpieces are subjected to high temperatures in a furnace and both an inert gas and an organic liquid, which at high temperatures is decomposed essentially into carbon monoxide and hydrogen, are introduced into the furnace, characterised in that the organic liquid is sucked in and sprayed by an oxygen-containing gas through an injector, the jet formed is surrounded by an inert gas, which essentially flows parallel to the jet and surrounds the latter in the form of a jacket, and is introduced into the furnace.
2. A method as claimed in Claim 1, characterised in that the organic liquid is an alcohol, in particular, methanol.
3. A method as claimed in one of Claims 1 or 2, characterised in that the oxygen-containing gas is air, a mixture of oxygen and nitrogen, or pure oxygen.
4. A method as claimed in one of Claims 1 to 3, characterised in that the inert gas is nitrogen.
5. A method as claimed in one of Claims 1 to 4, characterised in that the pressure and dew point of the gas atmosphere which is present in the furnace are adjusted by controlling the amount of inert gas.
6. Apparatus for carrying out the method as claimed in Claim 1 comprising addition means consisting of coaxial pipes and opening into the furnace, a supply line for an organic liquid opening into the inner pipe and a supply line for an inert gas opening into the outer pipe, characterised in that the supply line for an organic liquid opens into the inner pipe through a mixing device ; and that, moreover, a supply line for the supply of an oxygen-containing gas opens into the inner pipe through the mixing device.
EP81107820A 1980-10-04 1981-10-01 Method of and apparatus for decarburizing or neutrally annealing metal workpieces Expired EP0049488B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19803037643 DE3037643A1 (en) 1980-10-04 1980-10-04 METHOD AND DEVICE FOR THE DECOLARIZING OR COAL-NEUTRAL GLOWING OF METAL PARTS
DE3037643 1980-10-04

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EP0049488A1 EP0049488A1 (en) 1982-04-14
EP0049488B1 true EP0049488B1 (en) 1985-02-20

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EP81107820A Expired EP0049488B1 (en) 1980-10-04 1981-10-01 Method of and apparatus for decarburizing or neutrally annealing metal workpieces

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EP (1) EP0049488B1 (en)
AT (1) AT375679B (en)
AU (1) AU547114B2 (en)
BR (1) BR8106371A (en)
DE (2) DE3037643A1 (en)
ZA (1) ZA816859B (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3506131C1 (en) * 1985-02-22 1986-05-22 Aichelin GmbH, 7015 Korntal-Münchingen Process for the heat treatment of in particular metallic workpieces and device for carrying out the process
DE3808146A1 (en) * 1988-03-11 1989-09-21 Messer Griesheim Gmbh METHOD FOR PRODUCING A PROTECTIVE GAS FOR THE HEAT TREATMENT OF IRON AND NON-FERROUS METALS
DE3830559C1 (en) * 1988-09-08 1989-03-09 Linde Ag, 6200 Wiesbaden, De
DE102004047985A1 (en) * 2004-10-01 2006-04-06 Linde Ag Process for the preparation of atmospheres during heat treatments

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1049407B (en) * 1959-01-29 Aachen Dr.-Ing. Wolfgang Gruhl Process for the decarburization of iron in the solid state
DE1106787B (en) * 1956-04-26 1961-05-18 Renault Device for feeding a group of heat treatment furnaces for metals with protective gas from vapors of organic liquids which are enriched with nitrogen
FR1157164A (en) * 1956-08-04 1958-05-27 Renault Process for preparing a mixture of nitrogen and organic product vapor to provide a heat treatment atmosphere
DE1235352B (en) * 1959-08-26 1967-03-02 Renault Safety device on an atomizer heater for the production of protective gas for the heat treatment of metals
GB2037816B (en) * 1978-11-30 1982-10-27 Boc Ltd Heat treatment method
FR2450878A1 (en) * 1979-03-05 1980-10-03 Air Liquide INSTALLATION GENERATING AN ATMOSPHERE FOR HEAT TREATING METALS

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DE3037643A1 (en) 1982-05-13
BR8106371A (en) 1982-07-13
AU547114B2 (en) 1985-10-10
DE3169071D1 (en) 1985-03-28
ZA816859B (en) 1982-09-29
AT375679B (en) 1984-08-27
ATA129881A (en) 1984-01-15
AU7598381A (en) 1982-05-06
EP0049488A1 (en) 1982-04-14

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