EP0636189A1 - Procede de fabrication d'un gaz protecteur ou reactionnel pour le traitement thermique de metaux - Google Patents

Procede de fabrication d'un gaz protecteur ou reactionnel pour le traitement thermique de metaux

Info

Publication number
EP0636189A1
EP0636189A1 EP93908854A EP93908854A EP0636189A1 EP 0636189 A1 EP0636189 A1 EP 0636189A1 EP 93908854 A EP93908854 A EP 93908854A EP 93908854 A EP93908854 A EP 93908854A EP 0636189 A1 EP0636189 A1 EP 0636189A1
Authority
EP
European Patent Office
Prior art keywords
oxygen
nitrogen
gas
reactor
vol
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.)
Withdrawn
Application number
EP93908854A
Other languages
German (de)
English (en)
Inventor
Gerhard Gross
Johannes Vetter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Messer Griesheim GmbH
Original Assignee
Messer Griesheim GmbH
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Messer Griesheim GmbH filed Critical Messer Griesheim GmbH
Publication of EP0636189A1 publication Critical patent/EP0636189A1/fr
Withdrawn legal-status Critical Current

Links

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
    • 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
    • C21D1/763—Adjusting the composition of the atmosphere using a catalyst

Definitions

  • the invention relates to a method for producing a protective or reaction gas for the heat treatment of metals.
  • Heat treatments of metallic work pieces are carried out in the known heat treatment furnaces under a protective or reaction gas atmosphere.
  • the gas atmosphere mainly consists of the inert gas component nitrogen with different proportions of hydrogen and carbon monoxide.
  • Hydrogen is used to remove contaminants that have entered the furnace chamber, e.g. Binding oxygen to hydrogen, while CO is used to adjust the carbon level in the protective gas atmosphere, e.g.
  • the inert gas component nitrogen is obtained and liquefied in very pure form in low-temperature air separation plants with an oxygen content ⁇ 10 vpm.
  • the liquid nitrogen is stored in vacuum-insulated tanks at the consumer.
  • the reactive gas components H 2 and CO are either also stored in the pressure vessel or generated on site by splitting methanol or by endothermic conversion of hydrocarbons with air. Mixing with cryogenic nitrogen creates a very pure protective gas atmosphere, ie low dew point and low CO 2 concentration with the desired composition.
  • nitrogen can now also be obtained from the air by means of adsorbent or permeative processes. This nitrogen is produced by the pressure swing adsorption (PSA) or membrane process.
  • PSA pressure swing adsorption
  • Oxygen contents in the protective gas ⁇ 10 vpm are necessary for bright annealing of all metals.
  • Non-cryogenically generated nitrogen must therefore be cleaned up.
  • the oxygen reaction with hydrogen using a palladium or copper oxide catalyst is state of the art.
  • Another option is to add natural gas or propane to the non-cryogenically generated nitrogen and introduce this mixture into the hot part of the heat treatment system. This leads to the formation of
  • the C level is reduced not only by the oxygen content in the contaminated nitrogen of approx. 0.1 to 5 vol.% oxygen, but also by the water vapor that inevitably arises. This leads to a low carburization depth, which has to be compensated for by a longer carburization time.
  • the existing oxygen post-purification processes or conversion processes are therefore either too complex or generate an inert gas which is unsuitable for most heat treatment processes.
  • the invention is therefore based on the object of converting the oxygen in the contaminated nitrogen in such a way that a protective gas suitable for the heat treatment is produced.
  • the invention is based on the surprising finding that the oxygen content required for the endothermic reaction can be reduced from approximately 15% by volume to 0.1% by volume.
  • the necessary oxygen actuator varies depending on the desired shielding gas quality between 0.1 ⁇ ⁇ 0.3.
  • an oxygen actuator of ⁇ ⁇ 0.25 residual methane is present due to a lack of oxygen.
  • the methane content that may be required for the heat treatment can also be set by selecting the oxygen actuator. This lack of oxygen can also occur in a PPE system due to the process. Because when the throughput is reduced, the oxygen content is reduced at the same time. It is therefore not necessary to regulate the amount of methane.
  • the oxygen is completely converted into the protective gas components desired for the heat treatment using the method described above.
  • the composition of the protective gas is a function of the process temperature T, the oxygen concentration X in nitrogen and the oxygen actuator ⁇ .
  • PSA-N 2 systems operate at residual oxygen levels in nitrogen of approx. 2 to 5 vol.% In an economical optimum.
  • the shielding gas composition that arises corresponds to a high quality monogas, e.g. for the carbon neutral annealing of unalloyed and low-alloyed metals.
  • the dew point increases to + 18 ° C and the CO 2 concentrations to 1.0% by volume.
  • a protective gas is ideally suited for the heat treatment of non-ferrous metals.
  • Higher CO and H 2 concentrations are achieved by increasing the oxygen concentration in nitrogen.
  • the higher oxygen concentration in the N 2 can be adjusted depending on the process by increasing the throughput of the PSA or membrane system.
  • the higher oxygen concentration upstream of the reactor can also be achieved by adding air to non-cryogenic nitrogen.
  • FIG. 1 shows a heated reactor filled with the catalyst, which is arranged outside the heat treatment furnace.
  • Fig. 2 is a filled with the catalyst heated reactor which is integrated in the heat treatment furnace.
  • Reactor integrated in the heat treatment furnace and heated by it.
  • the air becomes a pressure swing adsorption or
  • the residual oxygen content in the nitrogen which is due to incomplete separation, is 0.1 to 5% by volume, depending on the throughput.
  • Pressure swing adsorption systems 10 operate at residual oxygen levels in nitrogen of approximately 2 to 5% by volume in the economic optimum.
  • the nitrogen contaminated with residual oxygen is fed via a gas supply 14 to a heat exchanger 11 and to the heated reactor 12 filled with the catalyst.
  • the heat exchanger 11 is arranged in a suitable location in the heat treatment furnace 13 and serves to preheat the contaminated nitrogen in order to increase the throughput of the reactor 12.
  • the reactor 12 is installed next to the heat treatment furnace 13 in FIG. 1.
  • the reactor bed consisting of the catalyst with the active components nickel, platinum, palladium or rhodium is heated indirectly electrically (Q closed) or by a burner to the desired process temperature of 600 to 1,000 ° C. in a controlled manner.
  • the hydrocarbon available for the endothermic conversion such as natural gas (methane) or propane, butane, town gas or heating oil, is mixed with the oxygen-contaminated nitrogen in the ratio necessary for the reaction before entering the reactor 12 and the gas mixture to the reactor 12 supplied.
  • the endothermic catalytic conversion of the oxygen maintained by supplying energy by means of hydrocarbons, for example using methane theoretically takes place in the reactor 12 with the oxygen actuator of 0.1 ⁇ A. ⁇ 0.3 required for this reaction as follows:
  • the maximum oxygen content in the protective gas is ⁇ 10 vpm.
  • the dew point can be set between - 32 ⁇ TP ° C ⁇ + 18 and the carbon dioxide concentration (CO 2 ) between 0.001 ⁇ X CO 2 vol.% ⁇ 1.2, depending on the temperature and the oxygen actuator.
  • CO 2 carbon dioxide concentration
  • This lack of oxygen can also be adjusted in a pressure swing adsorption system by reducing the throughput, so that methane control is not absolutely necessary.
  • Lower H 2 and CO concentrations are achieved through the lower oxygen contents in nitrogen with constant oxygen actuator ⁇ .
  • Lower H 2 and CO concentrations in the protective gas are advantageously required for bright annealing.
  • Higher H 2 and CO concentrations, as are required for carbonation-neutral annealing, are made possible by higher oxygen contents in nitrogen with a constant oxygen actuator and are achieved by additional admixture of air in the contaminated nitrogen.
  • the reactor 12 filled with the catalyst is integrated in the heat treatment furnace 13.
  • the reactor 12 is heated by a burner in a controlled manner to the desired process temperature of 600 to 1,000 ° C.
  • FIG. 3 shows an embodiment in which one or more reactors 12, 12.1, 12.2, 12.3 are integrated in the heat treatment furnace 13. The heating is carried out exclusively by the heat treatment furnace 13 (furnace heating), the maximum process temperature in the reactor 12 'being predetermined by the furnace temperature.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Catalysts (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)

Abstract

L'azote produit de manière non cryogène, comme celui qui est fabriqué avec des systèmes à membranes ou à adsorption par variation de pression, ne peut être utilisé, ou bien seulement de manière limitée, pour le traitement thermique des métaux, en raison de sa teneur élevée en oxygène, de l'ordre de 0,1 à 5 % en volume. Selon l'invention, un gaz protecteur convenant au traitement thermique des métaux est fabriqué par conversion catalytique endothermique de l'oxygène résiduel au moyen d'hydrocarbures.
EP93908854A 1992-04-13 1993-03-27 Procede de fabrication d'un gaz protecteur ou reactionnel pour le traitement thermique de metaux Withdrawn EP0636189A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE19924212307 DE4212307C2 (de) 1992-04-13 1992-04-13 Verfahren zur Herstellung eines Schutz- oder Reaktionsgases für die Wärmebehandlung von Metallen
DE4212307 1992-04-13
PCT/EP1993/000749 WO1993021350A1 (fr) 1992-04-13 1993-03-27 Procede de fabrication d'un gaz protecteur ou reactionnel pour le traitement thermique de metaux

Publications (1)

Publication Number Publication Date
EP0636189A1 true EP0636189A1 (fr) 1995-02-01

Family

ID=6456692

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93908854A Withdrawn EP0636189A1 (fr) 1992-04-13 1993-03-27 Procede de fabrication d'un gaz protecteur ou reactionnel pour le traitement thermique de metaux

Country Status (3)

Country Link
EP (1) EP0636189A1 (fr)
DE (1) DE4212307C2 (fr)
WO (1) WO1993021350A1 (fr)

Families Citing this family (18)

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Publication number Priority date Publication date Assignee Title
US5441581A (en) * 1994-06-06 1995-08-15 Praxair Technology, Inc. Process and apparatus for producing heat treatment atmospheres
US5968457A (en) * 1994-06-06 1999-10-19 Praxair Technology, Inc. Apparatus for producing heat treatment atmospheres
DE19545764C2 (de) * 1995-12-07 2000-02-17 Linde Ag Verfahren zur Schutzgaserzeugung für einen Wärmebehandlungsofen und Wärmebehandlungsanlage
US6531105B1 (en) 1996-02-29 2003-03-11 L'air Liquide-Societe Anonyme A'directoire Et Conseil De Surveillance Pour L'etude Et L'exploitation Des Procedes Georges Claude Process and apparatus for removing carbon monoxide from a gas stream
DE19608894A1 (de) * 1996-03-07 1997-09-18 Linde Ag Verfahren zur Schutzgasversorgung eines Wärmebehandlungsofens und Wärmebehandlungsanlage
DE19610722B4 (de) * 1996-03-19 2006-07-13 Air Liquide Deutschland Gmbh Verfahren zum Herstellen von Schutz- oder Reaktionsgasen für die Wärmebehandlung von Metallen
NZ314334A (en) * 1996-04-19 1997-09-22 Boc Group Inc Method of heat treating a metal with nitrogen rich gas preheated and then having oxygen-reactive gas added
US6007763A (en) * 1996-04-23 1999-12-28 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process and installation for preparing a heat treatment atmosphere
FR2747593B1 (fr) * 1996-04-23 1998-05-29 Air Liquide Procede d'elaboration d'une atmosphere de traitement thermique et methode de regulation d'un tel procede
FR2747594B1 (fr) * 1996-04-23 1998-05-29 Air Liquide Procede et installation d'elaboration d'une atmosphere de traitement thermique
DE19649356A1 (de) * 1996-11-28 1998-06-04 Messer Griesheim Gmbh Verfahren und Vorrichtung zum Herstellen eines N¶2¶, CO und H¶2¶ enthaltenden Gasgemischs
DE19651878C2 (de) * 1996-12-13 2002-01-17 Messer Griesheim Gmbh Verfahren zum Herstellen eines Schutz- oder Reaktionsgases für die Wärmebehandlung von Metallen
IT1291205B1 (it) * 1997-03-18 1998-12-29 Rivoira S P A Procedimento per la generazione di un'atmosfera protettiva a basso punto di rugiada ed esente da ossigeno, per l'effettuazione di
FR2807746B1 (fr) 2000-04-13 2002-12-13 Air Liquide Procede de production d'un melange comportant de l'hydrogene et du co
DE10051203A1 (de) * 2000-10-16 2002-04-25 Linde Ag Verfahren und Vorrichtung zur Erzeugung eines CO- und H2-haltigen Behandlungsgases für die Wärmebehandlung
US6881242B2 (en) * 2003-01-13 2005-04-19 Ati Properties, Inc. Hydrogen reclamation apparatus and method
US20070107818A1 (en) * 2005-11-16 2007-05-17 Bowe Donald J Deoxygenation of furnaces with hydrogen-containing atmoshperes
FR2915694B1 (fr) * 2007-05-03 2009-06-05 Air Liquide Procede ameliore de brasage d'aluminium a pression atmospherique

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2822048C2 (de) * 1978-05-20 1984-05-17 Loi Industrieofenanlagen Gmbh, 4300 Essen Anlage zur Erzeugung von Behandlungsgas für die Behandlung metallischer Gegenstände
FR2649123B1 (fr) * 1989-06-30 1991-09-13 Air Liquide Procede de traitement thermique de metaux
FR2668584B1 (fr) * 1990-10-26 1994-03-18 Lair Liquide Procede d'elaboration d'une atmosphere de traitement thermique et installation de traitement thermique.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9321350A1 *

Also Published As

Publication number Publication date
DE4212307A1 (de) 1993-10-14
DE4212307C2 (de) 1994-07-28
WO1993021350A1 (fr) 1993-10-28

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