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EP0364709B1 - Method of producing a gas-annealing atmosphere in a heat-treating device - Google Patents

Method of producing a gas-annealing atmosphere in a heat-treating device Download PDF

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Publication number
EP0364709B1
EP0364709B1 EP89116228A EP89116228A EP0364709B1 EP 0364709 B1 EP0364709 B1 EP 0364709B1 EP 89116228 A EP89116228 A EP 89116228A EP 89116228 A EP89116228 A EP 89116228A EP 0364709 B1 EP0364709 B1 EP 0364709B1
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Prior art keywords
gas
air
atmosphere
alcohol
treatment device
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French (fr)
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EP0364709A1 (en
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Reinhard Dipl.-Ing. Strigl
Andreas Dipl.-Ing. Dey
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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
    • 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 for producing a treatment gas atmosphere in a heat treatment device by thermal decomposition of starting materials introduced into the treatment room of the heat treatment device.
  • Methods for producing treatment gas atmospheres in particular from the field of heat treatment of metallic workpieces, are known which, on the one hand, generate a suitable treatment gas from natural gas and air in gas generators located outside the heat treatment device or in catalyst steel pipes integrated within the heat treatment device.
  • processes are known in which a suitable treatment gas atmosphere is produced by introducing nitrogen and methanol into the treatment room of a heat treatment device (see prior art and processes of DE 30 19 830 B2).
  • the former methods have the disadvantage that they are relatively inflexible both with regard to the amount of treatment gas and with regard to the composition of the treatment gas.
  • the object of the present invention is therefore to provide an inexpensive method with high flexibility and simple design.
  • This object is achieved in that hydrocarbon gas, alcohol, air and nitrogen are introduced simultaneously and adjacent to one another into the treatment room of a heat treatment device, in a stoichiometric ratio to one another such that the sum S of the mass ratios of the mass of the individual starting materials m n to mass of the source material air m L , so gives a value in the range 0.2 to 4, preferably 0.5 to 2.0.
  • a treatment gas is created that essentially consists of carbon monoxide, Hydrogen and nitrogen exist, to which any nitrogen content can be added by adding more nitrogen than the nitrogen content already present in the air.
  • the method according to the invention represents a method which contains many advantages of the previously known methods.
  • the proposed method takes advantage of the economic advantage that is obtained by using inexpensive hydrocarbon gas, for example natural gas, methane, propane, butane, for atmosphere production, while on the other hand, the simplicity of atmosphere generation by introducing the starting materials into suitable, problem-free areas the stoichiometrically exact ratio of variable proportions preserved in the heat treatment device remains without disadvantages, as mentioned at the outset.
  • the reaction processes also appear to be positively influenced by the adjacent introduction of the starting media, in particular hydrocarbon gas and alcohol. Temperatures of about 700 ° C. and more are necessary in the treatment room of the heat treatment device.
  • the alcohol is atomized into the furnace with nitrogen and / or air, with the other starting materials being supplied in a suitable amount in a manner directly surrounding the atomizing jet in a manner that surrounds the atomizing jet.
  • the carbon potential of the treatment gas atmosphere generated according to the invention is regulated via the natural gas and / or air component supplied, the regulation being carried out by measuring a size of the atmosphere which characterizes the carbon potential and by correspondingly varying one or both of the relevant components.
  • the carbon potential can also be influenced by an additional addition of a further hydrocarbon medium, in particular a further hydrocarbon gas, to the treatment room of the heat treatment device, the carbon potential of the atmosphere being determined by means of a variable which characterizes the carbon potential, such as the carbon dioxide, water or oxygen content the atmosphere.
  • a further hydrocarbon medium in particular a further hydrocarbon gas
  • the alcohol is evaporated before being fed to the heat treatment device and mixed with the other starting materials in gaseous form and this finished premix is introduced into the treatment room.
  • the reaction of the starting materials can also be carried out according to the invention supported by a catalyst, for example in that the reaction of the hydrocarbon gas with the air is carried out immediately upon entry into the treatment room by a catalyst arranged there or in that the alcohol is fed to the treatment room.
  • the heat treatment device evaporates and is mixed together with the other starting materials in gaseous form, and this mixture is converted into treatment gas as soon as it enters the treatment room with the aid of a catalyst arranged there.
  • catalyst variants are particularly advantageous for processes at the lower temperature threshold and guarantee the complete conversion of the starting materials.
  • a pipe 10 opens into a furnace 1, of which only part of the furnace wall is shown in the drawing.
  • An injector 2 is attached to the pipe via a first orifice 5 and a second orifice 6 with a gland head 7 with a seal 8 and a union nut 9 10 connected.
  • the injector 2 projects coaxially into the tube 10 at a distance from the tube 10 and the tube 11 of the second orifice approximately to the level of the inside of the furnace wall.
  • Supply lines for one of the output gases can be coupled to the introduction pieces 5 and 6.
  • the injector 2 has two inputs 3 and 4. Via the input 3, the injector is fed with nitrogen in a controllable manner via a line (not shown).
  • the nitrogen enters a mixing nozzle at high speed and sucks in methanol via inlet 4 and a line (also not shown).
  • the mist-shaped mixture of nitrogen and fine methanol droplets flows inside the injector 2 at high speed to the furnace and enters it in a jet.
  • the jet When entering the furnace, the jet is surrounded by a premixed mixture of natural gas and air in the form of a jacket, which is introduced via the mouthpiece 6 with the associated pipe 11. Via the mouthpiece 5, further nitrogen is also supplied up to a desired nitrogen content.
  • the throughput of all streams in this injection device is basically adjustable.
  • the treatment gas consisting essentially of carbon monoxide, hydrogen and nitrogen can thus be regulated as desired, particularly with regard to its carbon potential.
  • an increase in the proportion of the hydrocarbon gas in the starting mixture leads to an increase in the carbon potential
  • the increase in the proportion of air leads to a reduction in the carbon potential.
  • the method according to the invention is thus particularly suitable for the carburizing and carbon-neutral annealing of ferrous metal workpieces and - with suitable control - can also be used for decarburizing annealing processes.
  • the method according to the invention thus represents a versatile and economically advantageous method.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Tunnel Furnaces (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)

Abstract

The invention relates to a method of producing a gas-annealing atmosphere in a heat-treating device by thermal decomposition of the starting materials introduced into the treatment chamber of the heat-treating device. An inexpensive, flexible and simply-constructed method is achieved by the simultaneous introduction, performed adjacent to one another, of hydrocarbon gas, alcohol, air and nitrogen into the treatment chamber of the heat-treating device, the starting materials being introduced in a stoichiometric ratio to one another in such a way that the total S of the mass ratios of the mass of the starting materials mn to the mass of the starting material air mL, i.e. <IMAGE> gives a value in the range from 0.2 to 4, preferably 0.5 to 2.0. <IMAGE>

Description

Die Erfindung betrifft ein Verfahren zur Herstellung einer Behandlungsgasatmosphäre in einer Wärmebehandlungseinrichtung durch thermische Zersetzung von in den Behandlungsraum der Wärmebehandlungseinrichtung eingeleiteten Ausgangsstoffen.The invention relates to a method for producing a treatment gas atmosphere in a heat treatment device by thermal decomposition of starting materials introduced into the treatment room of the heat treatment device.

Es sind Verfahren zur Herstellung von Behandlungsgasatmosphären, insbesondere aus dem Bereich der Wärmebehandlung von metallischen Werkstücken bekannt, die einerseits aus Erdgas und Luft in außerhalb der Wärmebehandlungseinrichtung liegenden Gasgeneratoren oder in innerhalb der Wärmebehandlungseinrichtung integrierten Katalysatorstahlrohren ein geeignetes Behandlungsgas erzeugen. Andererseits sind Verfahren bekannt, bei denen durch Einführen von Stickstoff und Methanol in den Behandlungsraum einer Wärmebehandlungseinrichtung eine geeignete Behandlungsgasatmosphäre hergestellt wird (siehe Stand der Technik und Verfahren der DE 30 19 830 B2). Die erstgenannten Verfahren besitzen jedoch den Nachteil, daß sie sowohl bezüglich der Behandlungsgasmenge als auch bezüglich der Behandlungsgaszusammensetzung relativ unflexibel sind. Diese Nachteile sind bei den zweitgenannten Verfahren zwar überwunden, diese Verfahren sind jedoch aus ökonomischer Sicht aufgrund der höheren Kosten inbesondere von Methanol weniger günstig. Des weiteren sind Verfahren bekannt, bei denen der Behandlungsraum der Behandlungseinrichtung direkt mit Erdgas und Luft beaufschlagt wird - bei dieser Methode ist aber ein großer Analysen- und Regelungsaufwand notwendig.Methods for producing treatment gas atmospheres, in particular from the field of heat treatment of metallic workpieces, are known which, on the one hand, generate a suitable treatment gas from natural gas and air in gas generators located outside the heat treatment device or in catalyst steel pipes integrated within the heat treatment device. On the other hand, processes are known in which a suitable treatment gas atmosphere is produced by introducing nitrogen and methanol into the treatment room of a heat treatment device (see prior art and processes of DE 30 19 830 B2). The However, the former methods have the disadvantage that they are relatively inflexible both with regard to the amount of treatment gas and with regard to the composition of the treatment gas. Although these disadvantages have been overcome in the case of the second-mentioned processes, these processes are less economical from an economic point of view due to the higher costs, in particular of methanol. Furthermore, methods are known in which natural gas and air are directly applied to the treatment room of the treatment facility - however, this method requires a great deal of analysis and regulation.

Aufgabenstellung der vorliegenden Erfindung ist es daher, ein kostengünstiges Verfahren mit hoher Flexibilität und einfacher Ausgestaltung anzugeben.The object of the present invention is therefore to provide an inexpensive method with high flexibility and simple design.

Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß gleichzeitig und benachbart zueinander Kohlenwasserstoffgas, Alkohol, Luft und Stickstoff in den Behandlungsraum einer Wärmebehandlungseinrichtung eingeleitet werden und zwar in einem stöchiometrischen Verhältnis zueinander derart, daß die Summe S der Massenverhältnisse der Masse der einzelnen Ausgangsstoffe mn zur Masse des Ausgangsstoffs Luft mL, also

Figure imgb0001
einen Wert im Bereich 0. 2 bis 4, vorzugsweise 0.5 bis 2.0, ergibt. Das bedeutet, daß ein Behandlungsgas entsteht, das im wesentlichen aus Kohlenmonoxid, Wasserstoff und Stickstoff besteht, denen durch weitere Stickstoffzugabe ein beliebiger Stickstoffanteil über dem bereits aus der Luft vorhandenen Stickstoffanteil hinaus zugefügt werden kann.This object is achieved in that hydrocarbon gas, alcohol, air and nitrogen are introduced simultaneously and adjacent to one another into the treatment room of a heat treatment device, in a stoichiometric ratio to one another such that the sum S of the mass ratios of the mass of the individual starting materials m n to mass of the source material air m L , so
Figure imgb0001
 gives a value in the range 0.2 to 4, preferably 0.5 to 2.0. This means that a treatment gas is created that essentially consists of carbon monoxide, Hydrogen and nitrogen exist, to which any nitrogen content can be added by adding more nitrogen than the nitrogen content already present in the air.

Das erfindungsgemäße Verfahren stellt ein Verfahren dar, das viele Vorteile der vorbekannten Verfahren beinhaltet. Einerseits nutzt das vorgeschlagene Verfahren den ökonomischen Vorteil, den man durch die Verwendung von preiswertem Kohlenwasserstoffgas, also beispielsweise Erdgas, Methan, Propan, Butan, zur Atmosphärenherstellung erhält, während andererseits die Einfachheit der Atmosphärenerzeugung durch Einleiten der Ausgangsstoffe in geeigneten, problemlos, in Bereichen um das stöchiometrisch exakte Verhältnis herum, variierbaren Anteilen in die Wärmebehandlungseinrichtung erhalten bleibt ohne Nachteile, wie etwa eingangs genannt, mitzubringen. Die Reaktionsabläufe scheinen darüber hinaus, nach Erkenntnissen der Anmelderin, durch die benachbarte Einleitung der Ausgangsmedien, insbesondere von Kohlenwasserstoffgas und Alkohol, positiv beeinflußt. Im Behandlungsraum der Wärmebehandlungseinrichtung sind dabei Temperaturen von etwa 700°C und mehr notwendig.The method according to the invention represents a method which contains many advantages of the previously known methods. On the one hand, the proposed method takes advantage of the economic advantage that is obtained by using inexpensive hydrocarbon gas, for example natural gas, methane, propane, butane, for atmosphere production, while on the other hand, the simplicity of atmosphere generation by introducing the starting materials into suitable, problem-free areas the stoichiometrically exact ratio of variable proportions preserved in the heat treatment device remains without disadvantages, as mentioned at the outset. According to the applicant's knowledge, the reaction processes also appear to be positively influenced by the adjacent introduction of the starting media, in particular hydrocarbon gas and alcohol. Temperatures of about 700 ° C. and more are necessary in the treatment room of the heat treatment device.

Zwei grundsätzliche Kombinationen von Ausgangsstoffen zur Durchführung des erfindungsgemäßen Verfahrens sind:

Figure imgb0002
Two basic combinations of starting materials for carrying out the process according to the invention are:
Figure imgb0002

Ein Vergleich mit dem bekannten Stickstoff-Methanol-Verfahren bei dem Methanol und Stickstoff in einen Behandlungsraum wie folgt eingeführt werden, 2CH₃OH + 4 N₂ → 2CO + 4H₂ + 4N₂,

Figure imgb0003
zeigt, daß mit dem erfindungsgemäßen Verfahren ein gleichwertiges Behandlungsgas durch den Einsatz von zusätzlichen, preiswerten Ausgangsstoffen wie Kohlenwasserstoffgas und Luft der Aufwand an teuren Medien, wie Methanol und Stickstoff etwa um die Hälfte reduziert werden kann. Dagegen bleibt die Flexibilität sowohl im Hinblick auf die Menge als auch im Hinblick auf die Zusammensetzung erhalten.A comparison with the known nitrogen-methanol process in which methanol and nitrogen are introduced into a treatment room as follows, 2CH₃OH + 4 N₂ → 2CO + 4H₂ + 4N₂,
Figure imgb0003
 shows that with the method according to the invention an equivalent treatment gas can be reduced by about half the cost of expensive media such as methanol and nitrogen by using additional, inexpensive starting materials such as hydrocarbon gas and air. On the other hand, flexibility is maintained in terms of both quantity and composition.

Zur Ausführung des erfindungsgemäßen Verfahrens wird in einer vorteilhaften Ausgestaltungsvariante der Erfindung der Alkohol mit Stickstoff und/oder Luft zerstäubt in den Ofen eingebracht, wobei direkt benachbart dazu die anderen Ausgangsstoffe in geeigneter Menge in einer den Zerstäubungsstrahl mantelartig umgebenden Weise zugeführt werden.To carry out the method according to the invention, in an advantageous embodiment variant of the invention, the alcohol is atomized into the furnace with nitrogen and / or air, with the other starting materials being supplied in a suitable amount in a manner directly surrounding the atomizing jet in a manner that surrounds the atomizing jet.

Dadurch ergeben sich gute Mischungs- und Reaktionverhältnisse für die Behandlungsgasausgangsstoffe.This results in good mixing and reaction ratios for the treatment gas starting materials.

In einer Variante wird das Kohlenstoffpotential der erfindungsgemäß erzeugten Behandlungsgasatmosphäre über den zugeführten Erdgas- und/oder Luftanteil geregelt, wobei die Regelung mit Hilfe der Messung einer das Kohlenstoffpotential kennzeichnenden Größe der Atmosphäre und durch entsprechende Variation eines oder beider betreffender Anteile erfolgt.In one variant, the carbon potential of the treatment gas atmosphere generated according to the invention is regulated via the natural gas and / or air component supplied, the regulation being carried out by measuring a size of the atmosphere which characterizes the carbon potential and by correspondingly varying one or both of the relevant components.

Die Beeinflussung des Kohlenstoffpotentials kann aber auch durch eine zusätzliche Zugabe eines weiteren Kohlenwasserstoffmediums, insbesondere eines weiteren Kohlenwasserstoffgases, in den Behandlungsraum der Wärmebehandlungseinrichtung erfolgen, wobei das Kohlenstoffpotential der Atmosphäre mit Hilfe einer das Kohlenstoffpotential kennzeichnenden Größe, wie beispielsweise der Kohlendioxid-, Wasser- oder Sauerstoffgehalt der Atmosphäre, geregelt wird.However, the carbon potential can also be influenced by an additional addition of a further hydrocarbon medium, in particular a further hydrocarbon gas, to the treatment room of the heat treatment device, the carbon potential of the atmosphere being determined by means of a variable which characterizes the carbon potential, such as the carbon dioxide, water or oxygen content the atmosphere.

Die folgenden Ausgestaltungen sind günstige Varianten und Weiterbildungen der Erfindung. In einer ersten Version wird der Alkohol vor der Zufuhr zur Wärmebehandlungseinrichtung verdampft und mit den anderen Ausgangsstoffen in Gasform zusammengemischt und diese fertige Vormischung in den Behandlungsraum eingeleitet. Die Umsetzung der Ausgangsstoffe kann erfindungsgemäß auch durch einen Katalysator unterstützt erfolgen, und zwar beispielsweise dadurch, daß die Reaktion des Kohlenwasserstoffgases mit der Luft unmittelbar beim Eintritt in den Behandlungsraum durch einen dort angeordneten Katalysator unterstützt ausgeführt wird oder dadurch, daß der Alkohol vor der Zufuhr zur Wärmebehandlungseinrichtung verdampft und mit den anderen Ausgangsstoffen in Gasform zusammengemischt und diese Mischung unmittelbar beim Eintritt in den Behandlungsraum mit Hilfe eines dort angeordneten Katalysators zu Behandlungsgas umgesetzt wird.The following configurations are favorable variants and developments of the invention. In a first version, the alcohol is evaporated before being fed to the heat treatment device and mixed with the other starting materials in gaseous form and this finished premix is introduced into the treatment room. The reaction of the starting materials can also be carried out according to the invention supported by a catalyst, for example in that the reaction of the hydrocarbon gas with the air is carried out immediately upon entry into the treatment room by a catalyst arranged there or in that the alcohol is fed to the treatment room The heat treatment device evaporates and is mixed together with the other starting materials in gaseous form, and this mixture is converted into treatment gas as soon as it enters the treatment room with the aid of a catalyst arranged there.

Diese Katalysatorvarianten sind insbesondere bei Verfahren an der unteren Temperaturschwelle vorteilhaft und garantieren die vollständige Umsetzung der Ausgangsstoffe.These catalyst variants are particularly advantageous for processes at the lower temperature threshold and guarantee the complete conversion of the starting materials.

Im folgenden soll anhand einer schematischen Skizze beispielhaft die Erzeugung von Behandlungsgas in erfindungsgemäßer Weise beschrieben werden.The generation of treatment gas in the manner according to the invention will be described below using a schematic sketch as an example.

In einen Ofen 1, von dem in der Zeichnung lediglich ein Teil der Ofenwand dargestellt ist, mündet ein Rohr 10. Über ein erstes Einmündungsstück 5 und ein zweites Eimündungsstück 6 mit einem Stopfbuchsenkopf 7 mit Dichtung 8 und Überwurfmutter 9 ist ein Injektor 2 an das Rohr 10 angeschlossen. Der Injektor 2 ragt koaxial mit Abstand zu Rohr 10 und dem Rohr 11 des zweiten Einmündungsstücks etwa bis zur Höhe der Innenseite der Ofenwand in Rohr 10 hinein. An die Einleitungsstücke 5 und 6 sind Versorgungsleitungen für eines der Ausgangsgase ankuppelbar. Der Injektor 2 besitzt zwei Eingänge 3 und 4. Über Eingang 3 wird der Injektor über eine nicht dargestellte Leitung in regelbarer Weise mit Stickstoff gespeist. Der Stickstoff 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 Stickstoff und feinen Methanoltröpfchen strömt innerhalb des Injektors 2 mit hoher Geschwindigkeit zum Ofen und tritt strahlförmig in diesen ein. Beim Eintritt in den Ofen wird der Strahl von einem vorgemischten Gemisch aus Erdgas und Luft mantelförmig umgeben, das über das Einmündungsstück 6 mit dazugehörigem Rohr 11 eingeleitet wird. Über das Einmündungsstück 5 wird darüber hinaus weiterer Stickstoff bis zu einem gewünschten Stickstoffanteil zugeführt. Grundsätzlich ist auch eine andere Belegung der zwei Einmündungen und auch eine Verdüsung des Alkohols mit Luft möglich.A pipe 10 opens into a furnace 1, of which only part of the furnace wall is shown in the drawing. An injector 2 is attached to the pipe via a first orifice 5 and a second orifice 6 with a gland head 7 with a seal 8 and a union nut 9 10 connected. The injector 2 projects coaxially into the tube 10 at a distance from the tube 10 and the tube 11 of the second orifice approximately to the level of the inside of the furnace wall. Supply lines for one of the output gases can be coupled to the introduction pieces 5 and 6. The injector 2 has two inputs 3 and 4. Via the input 3, the injector is fed with nitrogen in a controllable manner via a line (not shown). The nitrogen enters a mixing nozzle at high speed and sucks in methanol via inlet 4 and a line (also not shown). The mist-shaped mixture of nitrogen and fine methanol droplets flows inside the injector 2 at high speed to the furnace and enters it in a jet. When entering the furnace, the jet is surrounded by a premixed mixture of natural gas and air in the form of a jacket, which is introduced via the mouthpiece 6 with the associated pipe 11. Via the mouthpiece 5, further nitrogen is also supplied up to a desired nitrogen content. In principle, it is also possible to occupy the two openings differently and to spray the alcohol with air.

Der Durchsatz aller Ströme in dieser Eindüsvorrichtung ist grundsätzlich einstellbar. Damit kann das Behandlungsgas im wesentlichen bestehend aus Kohlenmonoxid, Wasserstoff und Stickstoff insbesondere im Hinblick auf sein Kohlenstoffpotential wunschgemäß geregelt werden. Eine Vergrößerung des Anteils des Kohlenwasserstoffgases in der Ausgangsmischung führt dabei prinzipiell zu einer Erhöhung des Kohlenstoffpotentials, wogegen die Erhöhung des Anteils der Luft zu einer Erniedrigung des Kohlenstoffpotentials führt. Durch Messung einer kohlenstoffpotential- anzeigenden Große in der Behandlungsgasatmosphäre und entsprechende Regelung einer oder beider auf das Kohlenstoffpotential im wesentlichen Einfluß nehmenden Ausgangsgase, ist die Regelbarkeit einer erfindungsgemäß erzeugten Behandlungsgasatmosphäre gegeben.The throughput of all streams in this injection device is basically adjustable. The treatment gas consisting essentially of carbon monoxide, hydrogen and nitrogen can thus be regulated as desired, particularly with regard to its carbon potential. In principle, an increase in the proportion of the hydrocarbon gas in the starting mixture leads to an increase in the carbon potential, whereas the increase in the proportion of air leads to a reduction in the carbon potential. By measuring a quantity indicating carbon potential in the treatment gas atmosphere and correspondingly controlling one or both of the starting gases which essentially influence the carbon potential, the controllability of a treatment gas atmosphere produced according to the invention is given.

Das erfindungsgemäße Verfahren eignet sich so insbesondere zum aufkohlenden und kohlungsneutralen Glühen von Eisenmetallwerkstücken und ist - bei geeigneter Regelung - auch für entkohlende Glühvorgänge einsetzbar. Das erfindungsgemäße Verfahren stellt also ein vielseitig anwendbares und ökonomisch günstiges Verfahren dar.The method according to the invention is thus particularly suitable for the carburizing and carbon-neutral annealing of ferrous metal workpieces and - with suitable control - can also be used for decarburizing annealing processes. The method according to the invention thus represents a versatile and economically advantageous method.

Claims (7)

1. A method of producing a treatment gas atmosphere in a thermal treatment device by thermal decomposition of starting substances introduced into the treatment chamber of the thermal treatment device, characterised in that simultaneously and adjacent to one another, hydrocarbon gas, alcohol, air and nitrogen are introduced into the treatment chamber of a thermal treatment device in a stoichiometric ratio to one another such that the sum S of the mass ratios of the mass of the individual starting substances mn to the mass of the starting substance air mL, thus
Figure imgb0005
 has a value in the range of 0.2 to 4, preferably 0.5 to 2.0.
2. A method as claimed in Claim 1, characterised in that the alcohol is introduced into the furnace atomized with nitrogen and/or air, the other starting substances likewise being introduced into the furnace, directly adjacent thereto, in a suitable quantity and so as to surround the atomization jet in the form of a casing.
3. A method as claimed in one of Claims 1 to 2, characterised in that the carbon potential of the treatment gas is regulated via the supplied natural gas- and/or air constituent, where the carbon potential of the atmosphere is regulated by means of a parameter of the atmosphere which indicates the C-level, by varying one or both constituents.
4. A method as claimed in one of Claims 1 to 2, characterised in that the carbon potential is regulated by an additional addition of a further hydrocarbon medium, in particular further hydrocarbon gas, where the carbon potential of the atmosphere is regulated by means of a parameter of the atmosphere which indicates the C-level, by varying the addition of the additional hydrocarbon.
5. A method as claimed in one of Claims 1 to 4, characterised in that before it is supplied to the thermal treatment device, the alcohol is vaporized and mixed with the other starting substances in gaseous form, and this mixture is introduced into the treatment chamber.
6. A method as claimed in one of Claims 1 to 4, characterised in that the reaction of the hydrocarbon gas with the air takes place directly on entry into the treatment chamber, assisted by a catalyst arranged at this point.
7. A method as claimed in one of Claims 1 to 4, characterised in that before it is supplied to the thermal treatment device, the alcohol is vaporized and mixed with the other starting substances in gaseous form, and this mixture is converted into treatment gas directly on entry into the treatment chamber with the assistance of a catalyst arranged at this point.
EP89116228A 1988-09-08 1989-09-02 Method of producing a gas-annealing atmosphere in a heat-treating device Expired - Lifetime EP0364709B1 (en)

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AT89116228T ATE77841T1 (en) 1988-09-08 1989-09-02 PROCESS FOR CREATING A TREATMENT GAS ATMOSPHERE IN A THERMAL TREATMENT FACILITIES.

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DE3830559 1988-09-08
DE3830559A DE3830559C1 (en) 1988-09-08 1988-09-08

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EP0364709B1 true EP0364709B1 (en) 1992-07-01

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DE4308803A1 (en) * 1993-03-19 1994-09-22 Leybold Durferrit Gmbh Process and appliance for producing a carbon-containing gaseous treatment atmosphere

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CH643597A5 (en) * 1979-12-20 1984-06-15 Maag Zahnraeder & Maschinen Ag METHOD FOR ADJUSTABLE CARBONING OR HEATING IN PROTECTIVE GAS FROM WORKPIECE STEEL.
DE3037643A1 (en) * 1980-10-04 1982-05-13 Linde Ag, 6200 Wiesbaden METHOD AND DEVICE FOR THE DECOLARIZING OR COAL-NEUTRAL GLOWING OF METAL PARTS
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PT91642B (en) 1995-08-09
DE3830559C1 (en) 1989-03-09
ATE77841T1 (en) 1992-07-15
PT91642A (en) 1990-03-30
EP0364709A1 (en) 1990-04-25
DE58901774D1 (en) 1992-08-06
ES2033500T3 (en) 1993-03-16

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