EP0261461A2 - Method and apparatus for heat treating metal work pieces - Google Patents
Method and apparatus for heat treating metal work pieces Download PDFInfo
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- EP0261461A2 EP0261461A2 EP87112804A EP87112804A EP0261461A2 EP 0261461 A2 EP0261461 A2 EP 0261461A2 EP 87112804 A EP87112804 A EP 87112804A EP 87112804 A EP87112804 A EP 87112804A EP 0261461 A2 EP0261461 A2 EP 0261461A2
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- furnace
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- continuous furnace
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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
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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
- C21D1/763—Adjusting the composition of the atmosphere using a catalyst
Definitions
- the invention relates to a method for the heat treatment of metallic workpieces in a gas-heated continuous furnace under the action of a gas atmosphere, which consists essentially of nitrogen, hydrogen and carbon monoxide, and to a continuous furnace for carrying out the method.
- the heat treatment of metallic workpieces is often carried out in continuous furnaces, to which a treatment gas which is based on the type of heat treatment is supplied from the outside.
- a treatment gas which is based on the type of heat treatment is supplied from the outside.
- roller hearth furnaces for annealing semi-finished products made of iron or non-ferrous metals are known, which are equipped with so-called exogas, which in gas generators by exothermic combustion of hydrocarbons with air, or with so-called endogas, which in reactors filled with catalysts with the supply of heat also from hydrocarbon-air. Mixtures are generated, operated.
- the treatment gases produced in both processes essentially contain nitrogen, hydrogen and carbon monoxide and, under certain circumstances, also admixtures of carbon dioxide and water vapor.
- the exact mixing ratio of the components is chosen as it is with the respective type of Heat treatment in the main treatment zone, for example in the hot zone of the continuous furnace, is required.
- control and regulating methods are known with which the mixing ratio is influenced as a function of a size measured in the oven (VDI-Zeitung 98 (1956), No. 24, pages 1486 to 1490).
- the invention is therefore based on the object of making the known methods for the heat treatment of metallic workpieces in gas-fired continuous furnaces more economical.
- This object is achieved in that the gas atmosphere from a treatment gas containing nitrogen, hydrogen and carbon monoxide, which is fed to the continuous furnace in the region of its heating zone and which is generated immediately before it enters the continuous furnace by catalytic reaction of a gas containing hydrocarbons and air, and nitrogen , which is fed to the continuous furnace, on both sides of the supply point for the treatment gas, between the furnace inlet and the heating zone and between the heating zone and the furnace outlet.
- a gas atmosphere profile extending in the direction of the longitudinal extension of the continuous furnace is optimally built up, which starts from the furnace inlet with a zone of low reactivity, then reaches the highest reactivity in the region of the hot zone and finally in the region of the furnace outlet drops again to low reactivity.
- the process according to the invention thus leads to a higher reactivity in the hot zone of the furnace, without the furnace atmosphere in the vicinity of the furnace inlet and outlet becoming more toxic or flammable than with exogas.
- a direct consequence of this procedure is a considerable saving in terms of the consumption of hydrocarbon-containing gases, which can cost up to over 30%.
- the process according to the invention in addition to the advantage of its increased economic efficiency compared to known processes, also brings about an improvement in the quality, in particular the uniformity, of the treated workpieces, which is based on the fact that the composition of the gas atmosphere at every point in the furnace can be set in an optimal manner.
- an essential requirement for this advantage is the generation of the treatment gas by catalytic conversion immediately before it enters the continuous furnace.
- the gas atmosphere formed in the process according to the invention has a high buffering effect against air ingress and leaks in the radiant tube burners. In addition, soot formation and damage to the furnace lining are reliably avoided with the method according to the invention.
- the quantitative ratio between the treatment gas and the separately supplied nitrogen is advantageously selected such that the furnace atmosphere in the regions adjacent to the furnace inlet and outlet is less than 20%, preferably less than 10%, carbon monoxide and less than 30%, preferably less than 10%, contains hydrogen.
- the continuous furnace is heated by means of a jet tube burner and the treatment gas is fed to the continuous furnace via a cross section which is arranged concentrically with the burner chamber and at least one of the jet tube burners which is arranged in the region of the hot zone and is filled with catalyst.
- Preferred areas of application of the method according to the invention are recrystallization and the carbon-neutral or decarburizing annealing of semi-finished products in roller hearth furnaces.
- a continuous furnace for carrying out the method according to the invention with jet tube burners arranged over its longitudinal extent is advantageously designed such that at least one of the jet tube burners arranged in the area of the hot zone of the continuous furnace has a cross section arranged concentrically with the burner chamber and filled with catalyst for the generation of the treatment gas and in With regard to the longitudinal extent of the continuous furnace, gas feeds for nitrogen are arranged on both sides of the radiant tube burner (s) having a cross section filled with catalyst, in the region between the furnace inlet and the hot zone and in the region between the hot zone and the furnace outlet.
- the roller hearth furnace 1 has a furnace inlet 2, from which metallic workpieces are fed continuously or discontinuously through the furnace 1 to the furnace outlet 3 by means of transport rollers 4.
- the furnace 1 is heated by a number of radiant tube burners 5 with natural gas as the fuel gas so that the workpieces passing through the furnace 1, e.g. should be annealed in a carbon-neutral manner, first heated slowly, then reaching the highest temperature approximately in the middle of the furnace and finally slowly cooling the furnace outlet 3 again.
- a 6 of the jet tube burner 5 is designed as an internally heated catalytic reactor in that the burner chamber is surrounded concentrically by an annular space filled with catalyst for generating the treatment gas. Also owns the furnace 1 has two gas feeds 7 which are arranged on both sides in the longitudinal direction of the furnace to the jet tube burner 6 which is designed as a catalytic reactor. In the case of larger or longer ovens, several special jet tube burners 6 and / or further gas feeds 7 can also be provided.
- a natural gas / air mixture is fed to the jet tube burners 5 for heating.
- the natural gas-air mixture is additionally fed to the second cross section containing the catalyst, where a treatment gas with approximately 40% nitrogen, 38% hydrogen and 18% carbon monoxide is produced by endothermic reaction and through a gas distributor 8 is blown into the interior of the furnace 1.
- pure nitrogen is introduced into the furnace 1 via the gas feeds 7, which dilutes the treatment gas in the region of the furnace inlet 2 and the furnace outlet 3 so that the gas atmosphere there only contains about 8% hydrogen and also about 8% carbon monoxide.
- a gas atmosphere profile is built up in this way in furnace 1 over its longitudinal extent, which has its highest reactivity in the hot zone and its lowest reactivity at furnace inlet 2 and at furnace outlet 3.
- the changing composition of the furnace atmosphere can be caused, on the one hand, by changes in the mixing ratio of the natural gas-air mixture which is fed to the furnace 1 via the jet tube burner 6 designed as a catalytic reactor, and, on the other hand, by changes in the amount of nitrogen introduced into the furnace 1 via the gas feeds 7 can be adapted in any way and extremely precisely to the respective requirements.
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- Crystallography & Structural Chemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Furnace Details (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
- Tunnel Furnaces (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
Es wird ein Verfahren zur Wärmebehandlung metallischer Werkstücke in einem gasbeheizten Durchlaufofen unter Einwirkung einer Gasatmosphäre beschrieben, wobei die Gasatmosphäre im wesentlichen aus Stickstoff, Wasserstoff und Kohlenmonoxid besteht. Um dieses Verfahren durch Einsparung von Gas wirtschaftlicher zu gestalten, wird vorgeschlagen, die Gasatmosphäre aus einem Stickstoff, Wasserstoff und Kohlenmonoxid enthaltenden Behandlungsgas, das dem Durchlaufofen im Bereich seiner Heizzone zugeführt und das unmittelbar vor seinem Eintritt in den Durchlaufofen durch katalytische Umsetzung eines Kohlenwasserstoffe und Luft enthaltenden Gases erzeugt wird und Stickstoff, der dem Durchlaufofen, beidseitig der Zuführungsstelle für das Behandlungsgas, zwischen Ofeneinlauf und Heizzone sowie zwischen Heizzone und Ofensauslauf zugeführt wird, zu bilden. A method for the heat treatment of metallic workpieces in a gas-heated continuous furnace under the action of a gas atmosphere is described, the gas atmosphere consisting essentially of nitrogen, hydrogen and carbon monoxide. In order to make this process more economical by saving gas, it is proposed that the gas atmosphere consist of a treatment gas containing nitrogen, hydrogen and carbon monoxide, which is fed to the continuous furnace in the region of its heating zone and immediately before it enters the continuous furnace by catalytic conversion of a hydrocarbon and air containing gas is generated and nitrogen, which is fed to the continuous furnace, on both sides of the supply point for the treatment gas, between the furnace inlet and the heating zone and between the heating zone and the furnace outlet.
Description
Die Erfindung betrifft ein Verfahren zur Wärmebehandlung metallischer Werkstücke in einem gasbeheizten Durchlaufofen unter Einwirkung einer Gasatmosphäre, die im wesentlichen aus Stickstoff, Wasserstoff und Kohlenmonoxid besteht sowie einen Durchlaufofen zur Durchführung des Verfahrens.The invention relates to a method for the heat treatment of metallic workpieces in a gas-heated continuous furnace under the action of a gas atmosphere, which consists essentially of nitrogen, hydrogen and carbon monoxide, and to a continuous furnace for carrying out the method.
Die Wärmebehandlung metallischer Werkstücke wird häufig in Durchlauföfen durchgeführt, denen ein in seiner Zusammensetzung auf die Art der Wärmebehandlung abgestelltes Behandlungsgas von außen zugeleitet wird. So sind z.B. Rollenherdöfen zum Glühen von Halbzeugen aus Eisen oder auch Nichteisenmetallen bekannt, die mit sogenanntem Exogas, das in Gasgeneratoren durch exotherme Verbrennung von Kohlenwasserstoffen mit Luft, oder mit sogenanntem Endogas, das in mit Katalysatoren gefüllten Reaktoren unter Wärmezufuhr ebenfalls aus Kohlenwasserstoff-Luft-Gemischen erzeugt wird, betrieben werden. Die bei beiden Verfahren entstehenden Behandlungsgase enthalten im wesentlichen Stickstoff, Wasserstoff und Kohlenmonoxid sowie unter Umständen noch Beimengungen von Kohlendioxid und Wasserdampf. Das genaue Mischungsverhältnis der Komponenten wird so gewählt, wie es bei der jeweils vorliegenden Art der Wärmebehandlung in der Hauptbehandlungszone, z.B. in der heißen Zone des Durchlaufofens, erforderlich ist. Zur Aufrechterhaltung des richtigen Mischungsverhältnisses oder zu einer gezielten Änderung desselben sind Steuer- und Regelverfahren bekannt, mit denen das Mischungsverhältnis in Abhängigkeit einer im Ofen gemessen Größe beeinflußt wird (VDI-Zeitung 98 (1956), Nr. 24, Seiten 1486 bis 1490).The heat treatment of metallic workpieces is often carried out in continuous furnaces, to which a treatment gas which is based on the type of heat treatment is supplied from the outside. For example, roller hearth furnaces for annealing semi-finished products made of iron or non-ferrous metals are known, which are equipped with so-called exogas, which in gas generators by exothermic combustion of hydrocarbons with air, or with so-called endogas, which in reactors filled with catalysts with the supply of heat also from hydrocarbon-air. Mixtures are generated, operated. The treatment gases produced in both processes essentially contain nitrogen, hydrogen and carbon monoxide and, under certain circumstances, also admixtures of carbon dioxide and water vapor. The exact mixing ratio of the components is chosen as it is with the respective type of Heat treatment in the main treatment zone, for example in the hot zone of the continuous furnace, is required. In order to maintain the correct mixing ratio or to change it in a targeted manner, control and regulating methods are known with which the mixing ratio is influenced as a function of a size measured in the oven (VDI-Zeitung 98 (1956), No. 24, pages 1486 to 1490).
Die bekannten Verfahren und ihre neueren Weiterentwicklungen arbeiten technisch weitgehend zufriedenstellend, jedoch ist ihre Anwendung auf große Öfen, insbesondere auf langgestreckte Durchlauföfen, nicht immer in dem Maße wirtschaftlich, wie es wünschenswert wäre. Der Gesamtgasverbrauch, d.h. der Verbrauch an Brenngas und Behandlungsgas, ist wegen der räumlichen Ausdehnung solcher Öfen größer als er zur eigentlichen Wärmebehandlung notwendig wäre. Dieser Nachteil ist, insbesondere wegen des Verbrauchs von wertvollen kohlenwasserstoffhaltigen Gasen, von nicht zu vernachlässigender Bedeutung.The known methods and their more recent developments work largely satisfactorily from a technical point of view, but their use on large furnaces, in particular on elongated continuous furnaces, is not always economical to the extent that it would be desirable. The total gas consumption, i.e. The consumption of fuel gas and treatment gas is greater than would be necessary for the actual heat treatment because of the spatial expansion of such furnaces. This disadvantage is of not insignificant importance, particularly because of the consumption of valuable hydrocarbon-containing gases.
Der Erfindung liegt deshalb die Aufgabe zugrunde, die bekannten Verfahren zur Wärmebehandlung metallischer Werkstücke in gasbeheizten Durchlauföfen wirtschaftlicher zu gestalten.The invention is therefore based on the object of making the known methods for the heat treatment of metallic workpieces in gas-fired continuous furnaces more economical.
Diese Aufgabe wird dadurch gelöst, daß die Gasatmosphäre aus einem Stickstoff, Wasserstoff und Kohlenmonoxid enthaltenden Behandlungsgas, das dem Durchlaufofen im Bereich seiner Heizzone zugeführt und das unmittelbar vor seinem Eintritt in den Durchlaufofen durch katalytische Umsetzung eines Kohlenwasserstoffe und Luft enthaltenden Gases erzeugt wird, und Stickstoff, der dem Durchlaufofen, beidseitig der Zuführungsstelle für das Behandlungsgas, zwischen Ofeneinlauf und Heizzone sowie zwischen Heizzone und Ofenauslauf zugeführt wird, gebildet wird.This object is achieved in that the gas atmosphere from a treatment gas containing nitrogen, hydrogen and carbon monoxide, which is fed to the continuous furnace in the region of its heating zone and which is generated immediately before it enters the continuous furnace by catalytic reaction of a gas containing hydrocarbons and air, and nitrogen , which is fed to the continuous furnace, on both sides of the supply point for the treatment gas, between the furnace inlet and the heating zone and between the heating zone and the furnace outlet.
Mit dem erfindungsgemäßen Verfahren wird in einem Durchlaufofen in optimaler Weise ein sich in Richtung der Längsausdehnung des Durchlaufofens erstreckendes Gasatmosphärenprofil aufgebaut, das vom Ofeneinlauf her mit einer Zone geringer Reaktivität beginnt, dann im Bereich der heißen Zone die höchste Reaktivität erreicht und schließlich im Bereich des Ofenauslaufs wieder zur geringer Reaktivität absinkt. Verglichen mit einer Exogasatmosphäre führt das erfindungsgemäße Verfahren somit zu einer höheren Reaktivität in der heißen Zone des Ofens, ohne daß die Ofenatmosphäre in der Nähe von Ofenein- und auslauf giftiger oder brennbarer wird als bei Exogas. Eine unmittelbare Folge dieser Verfahrensweise ist eine erhebliche Einsparung bezüglich des Verbrauches kohlenwasserstoffhaltiger Gase, die kostenmäßig bis über 30 % betragen kann.With the method according to the invention, a gas atmosphere profile extending in the direction of the longitudinal extension of the continuous furnace is optimally built up, which starts from the furnace inlet with a zone of low reactivity, then reaches the highest reactivity in the region of the hot zone and finally in the region of the furnace outlet drops again to low reactivity. Compared to an exogas atmosphere, the process according to the invention thus leads to a higher reactivity in the hot zone of the furnace, without the furnace atmosphere in the vicinity of the furnace inlet and outlet becoming more toxic or flammable than with exogas. A direct consequence of this procedure is a considerable saving in terms of the consumption of hydrocarbon-containing gases, which can cost up to over 30%.
Überraschenderweise wurde gefunden, daß das erfindungsgemäße Verfahren außer dem Vorteil seiner gegenüber bekannten Verfahren erhöhten Wirtschaftlichkeit auch eine Verbesserung der Qualität, insbesondere der Gleichmäßigkeit der Qualität, der behandelten Werkstücke mit sich bringt, die darauf beruht, daß die Zusammensetzung der Gasatmosphäre an jeder Stelle des Ofens in optimaler Weise eingestellt werden kann. Eine wesentliche Voraussetzung für diesen Vorteil ist neben der getrennten Stickstoffzufuhr die Erzeugung des Behandlungsgases unmittelbar vor seinem Eintritt in den Durchlaufofen durch katalytische Umsetzung. Darüber hinaus hat die beim erfindungsgemäßen Verfahren gebildete Gasatmosphäre eine hohe Pufferwirkung gegenüber Lufteinbrüchen und Undichtigkeiten in den Strahlrohrbrennern. Außerdem werden Rußbildung und Schäden an der Ofenausmauerung mit dem erfindungsgemäßen Verfahren sicher vermieden.Surprisingly, it was found that the process according to the invention, in addition to the advantage of its increased economic efficiency compared to known processes, also brings about an improvement in the quality, in particular the uniformity, of the treated workpieces, which is based on the fact that the composition of the gas atmosphere at every point in the furnace can be set in an optimal manner. In addition to the separate supply of nitrogen, an essential requirement for this advantage is the generation of the treatment gas by catalytic conversion immediately before it enters the continuous furnace. In addition, the gas atmosphere formed in the process according to the invention has a high buffering effect against air ingress and leaks in the radiant tube burners. In addition, soot formation and damage to the furnace lining are reliably avoided with the method according to the invention.
Bei der Durchführung des erfindungsgemäßen Verfahrens wird vorteilhaft das Mengenverhältnis zwischen Behandlungsgas und dem getrennt zugeleiteten Stickstoff so gewählt, daß die Ofenatmosphäre in den dem Ofeneinlauf und dem Ofenauslauf benachbarten Bereichen weniger als 20 %, vorzugsweise weniger als 10 %, Kohlenmonoxid und weniger als 30 %, vorzugsweise weniger als 10 %, Wasserstoff enthält.When carrying out the process according to the invention, the quantitative ratio between the treatment gas and the separately supplied nitrogen is advantageously selected such that the furnace atmosphere in the regions adjacent to the furnace inlet and outlet is less than 20%, preferably less than 10%, carbon monoxide and less than 30%, preferably less than 10%, contains hydrogen.
Besonders vorteilhaft ist auch eine Weiterentwicklung des erfindungsgemäßen Verfahrens, bei der der Durchlaufofen über Strahlrohrbrenner beheizt wird und das Behandlungsgas dem Durchlaufofen über einen konzentrisch zum Brennerraum mindestens eines der im Bereich der heißen Zone angeordneten Strahlrohrbrenner angeordneten und mit Katalysator gefüllten Querschnitt zugeleitet wird.Also particularly advantageous is a further development of the method according to the invention, in which the continuous furnace is heated by means of a jet tube burner and the treatment gas is fed to the continuous furnace via a cross section which is arranged concentrically with the burner chamber and at least one of the jet tube burners which is arranged in the region of the hot zone and is filled with catalyst.
Die Verwendung derartiger Katalysatorrohre ist zwar von anderen Wärmebehandlungsöfen her schon bekannt, doch hat es sich gezeigt, daß ihre Verwendung im Rahmen des erfindungsgemäßen Verfahrens besonders vorteilhaft ist.The use of such catalyst tubes is already known from other heat treatment furnaces, but it has been shown that their use is particularly advantageous in the process according to the invention.
Da in jüngster Zeit Durchlauföfen zur Wärmebehandlung überwiegend mit Erdgas beheizt werden, ist die Anwendung des erfindungsgemäßen Verfahrens bei solchen Öfen besonders wirtschaftlich, wenn das Behandlungsgas aus einem Erdgas-Luft-Gemisch erzeugt wird, da auf diese Weise lediglich Stickstoff als zusätzliches Medium am Durchlaufofen zur Verfügung stehen muß.Since continuous furnaces for heat treatment have recently been heated predominantly with natural gas, the use of the method according to the invention in such furnaces is particularly economical if the treatment gas is generated from a natural gas / air mixture, since in this way only nitrogen is used as an additional medium in the continuous furnace Must be available.
Bevorzugte Anwendungsgebiete des erfindungsgemäßen Verfahrens sind das Rekristallisieren und das kohlungsneutral- oder entkohlende Glühen von Halbzeugen in Rollenherdöfen.Preferred areas of application of the method according to the invention are recrystallization and the carbon-neutral or decarburizing annealing of semi-finished products in roller hearth furnaces.
Ein Durchlaufofen zur Durchführung des erfindungsgemäßen Verfahrens mit über seine Längsausdehnung angeordneten Strahlrohrbrennern ist mit Vorteil so ausgebildet, daß mindestens einer der im Bereich der heißen Zone des Durchlaufofens angeordneten Strahlrohrbrenner einen konzentrisch zum Brennerraum angeordneten und mit Katalysator gefüllten Querschnitt für die Erzeugung des Behandlungsgases aufweist und in Bezug auf die Längsausdehnung des Durchlaufofens, beidseitig zu dem oder den einen mit Katalysator gefüllten Querschnitt aufweisenden Strahlrohrbrennern, im Bereich zwischen Ofeneinlauf und heißer Zone sowie im Bereich zwischen heißer Zone und Ofenauslauf Gaszuführungen für Stickstoff angeordnet sind.A continuous furnace for carrying out the method according to the invention with jet tube burners arranged over its longitudinal extent is advantageously designed such that at least one of the jet tube burners arranged in the area of the hot zone of the continuous furnace has a cross section arranged concentrically with the burner chamber and filled with catalyst for the generation of the treatment gas and in With regard to the longitudinal extent of the continuous furnace, gas feeds for nitrogen are arranged on both sides of the radiant tube burner (s) having a cross section filled with catalyst, in the region between the furnace inlet and the hot zone and in the region between the hot zone and the furnace outlet.
Im folgenden wird ein Ausführungsbeispiel des erfindungsgemäßan Verfahrens anhand eines in der Figur schematisch dargestellten Rollenherdofens beschrieben.An exemplary embodiment of the method according to the invention is described below using a roller hearth furnace shown schematically in the figure.
Der Rollenherdofen 1 besitzt einen Ofeneinlaß 2, von dem mittels Transportrollen 4 metallische Werkstücke kontinuierlich oder diskontinuierlich durch den Ofen 1 hindurch dem Ofenauslauf 3 zugeführt werden. Der Ofen 1 wird über eine Anzahl von Strahlrohrbrennern 5 mit Erdgas als Brenngas so beheizt, daß die den Ofen 1 durchlaufenden Werkstücke, die z.B. kohlungsneutral geglüht werden sollen, zunächst langsam erhitzt werden, dann ungefähr in der Ofenmitte die höchste Temperatur erreichen und schließlich dem Ofenauslauf 3 zu wieder langsam abkühlen.The roller hearth furnace 1 has a
Im Bereich der heißen Zone des Ofens 1 ist einer 6 der Strahlrohrbrenner 5 dadurch als innenbeheizter katalytischer Reaktor ausgebildet, daß der Brennerraum konzentrisch von einem mit Katalysator gefüllten ringförmigen Raum zur Erzeugung des Behandlungsgases umgeben ist. Außerdem besitzt der Ofen 1 zwei Gaszuführungen 7, die in Längsrichtung des Ofens beidseitig zu dem als katalytischer Reaktor ausgebildeten Strahlrohrbrenner 6 angeordnet sind. Bei größern oder längeren Öfen können auch mehrere spezielle Strahlrohrbrenner 6 und/oder weitere Gaszuführungen 7 vorgesehen sein.In the area of the hot zone of the furnace 1, a 6 of the
Beim Betrieb des Ofens wird den Strahlrohrbrennern 5 ein Erdgas-Luft-Gemisch zur Beheizung zugeführt. Bei dem als katalytischen Reaktor ausgebildeten Strahlrohrbrenner 6 wird das Erdgas-Luft-Gemisch zusätzlich dem zweiten, den Katalysator enthaltenden Querschnitt zugeführt, wo durch endotherme Umsetzung ein Behandlungsgas mit ungefähr 40 % Stickstoff, 38 % Wasserstoff und 18 % Kohlenmonoxid erzeugt und durch einen Gasverteiler 8 in den Innenraum des Ofens 1 eingeblasen wird. Zusätzlich wird über die Gaszuführungen 7 reiner Stickstoff in den Ofen 1 eingeleitet, der das Behandlungsgas im Bereich des Ofeneinlaufs 2 und des Ofenauslaufs 3 so verdünnt, daß dort die Gasatmosphäre nur noch etwa 8 % Wasserstoff und ebenfalls etwa 8% Kohlenmonoxid enthält. Ingesamt wird auf diese Weise in Ofen 1 über seine Längsausdehnung eine Gasatmosphärenprofil aufgebaut, das in der heißen Zone seine höchste und beim Ofeneinlauf 2 und beim Ofenauslauf 3 seine niedrigste Reaktivität aufweist. Die wechselnde Zusammensetzung der Ofenatmosphäre kann einerseits durch Änderungen des Mischungsverhältnisses des Erdgas-Luft-Gemisches, das über den als katalytischen Reaktor ausgebildeten Strahlrohrbrenner 6 dem Ofen 1 zugeführt wird, und andererseits durch Änderungen der Menge des über die Gaszuführungen 7 in den Ofen 1 eingebrachten Stickstoffs in beliebiger Weise und außerordentlich genau den jeweils vorliegenden Erfordernissen angepaßt werden.When the furnace is operating, a natural gas / air mixture is fed to the
Durch das erfindungsgemäße Verfahren kann bei einem Durchlaufofen der beschriebenen Art eine erhebliche Einsparung an Behandlungsgas erzielt werden. So konnten beispielsweise in einem speziellen Fall einer Wärmebehandlung 220 m³/h Exogas durch nur 100 m³/h Stickstoff, 6 m³/h Erdgas und 15 m³/h Luft ersetzt werden.With the method according to the invention, a considerable saving in treatment gas can be achieved in a continuous furnace of the type described. For example, in a special case of heat treatment, 220 m³ / h of exogas could be replaced by only 100 m³ / h of nitrogen, 6 m³ / h of natural gas and 15 m³ / h of air.
Claims (5)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT87112804T ATE89868T1 (en) | 1986-09-10 | 1987-09-02 | METHOD AND DEVICE FOR THE HEAT TREATMENT OF METALLIC WORKPIECES. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3630833 | 1986-09-10 | ||
| DE19863630833 DE3630833A1 (en) | 1986-09-10 | 1986-09-10 | METHOD AND DEVICE FOR HEAT TREATING METAL WORKPIECES |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0261461A2 true EP0261461A2 (en) | 1988-03-30 |
| EP0261461A3 EP0261461A3 (en) | 1989-03-15 |
| EP0261461B1 EP0261461B1 (en) | 1993-05-26 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP87112804A Expired - Lifetime EP0261461B1 (en) | 1986-09-10 | 1987-09-02 | Method and apparatus for heat treating metal work pieces |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0261461B1 (en) |
| AT (1) | ATE89868T1 (en) |
| BR (1) | BR8704618A (en) |
| DE (2) | DE3630833A1 (en) |
| ES (1) | ES2042524T3 (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0435033A1 (en) * | 1989-12-23 | 1991-07-03 | Linde Aktiengesellschaft | Method for providing and distributing treatment gases for heat treatments |
| EP0458183A3 (en) * | 1990-05-19 | 1992-04-01 | Linde Aktiengesellschaft | Method for making available treatment gases for heat treatments |
| DE4343927C1 (en) * | 1993-12-22 | 1995-01-05 | Linde Ag | Method for thermal treatment of workpieces under treatment gas |
| EP0778354A1 (en) * | 1995-12-07 | 1997-06-11 | Linde Aktiengesellschaft | Process for supplying controlled atmosphere gases into a heat treatment furnace and heat treatment plant |
| EP0856587A1 (en) * | 1997-01-29 | 1998-08-05 | Praxair Technology, Inc. | Process for the heat treatment of iron-based metal parts in an active atmosphere with a high potential of carbon |
| WO2005035799A1 (en) * | 2003-10-08 | 2005-04-21 | Messer Austria Gmbh | Method for heat-treating iron-containing materials |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3842372C2 (en) * | 1988-12-16 | 1996-10-02 | Induktionserwaermung Fritz Due | Device for the heat treatment of metallic workpieces |
| FR2668584B1 (en) * | 1990-10-26 | 1994-03-18 | Lair Liquide | PROCESS FOR DEVELOPING A HEAT TREATMENT ATMOSPHERE AND HEAT TREATMENT PLANT. |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD31283A (en) * | ||||
| DE1433735B1 (en) * | 1963-09-21 | 1969-09-04 | Werner Goehring | Process for achieving a furnace atmosphere with which an oxidation-free heat treatment of workpieces made of steel can be carried out while at the same time influencing the carbon content |
| DD131292A1 (en) * | 1977-03-28 | 1978-06-14 | Arnd Mueller | DEVICE FOR PROTECTING GAS GENERATION IN THE OVEN ROOM |
| DE3440876A1 (en) * | 1984-11-08 | 1986-05-15 | Linde Ag, 6200 Wiesbaden | METHOD AND DEVICE FOR PRODUCING A PROTECTIVE GAS ATMOSPHERE |
-
1986
- 1986-09-10 DE DE19863630833 patent/DE3630833A1/en not_active Withdrawn
-
1987
- 1987-09-02 ES ES87112804T patent/ES2042524T3/en not_active Expired - Lifetime
- 1987-09-02 DE DE8787112804T patent/DE3785989D1/en not_active Expired - Fee Related
- 1987-09-02 AT AT87112804T patent/ATE89868T1/en not_active IP Right Cessation
- 1987-09-02 EP EP87112804A patent/EP0261461B1/en not_active Expired - Lifetime
- 1987-09-04 BR BR8704618A patent/BR8704618A/en unknown
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0435033A1 (en) * | 1989-12-23 | 1991-07-03 | Linde Aktiengesellschaft | Method for providing and distributing treatment gases for heat treatments |
| EP0458183A3 (en) * | 1990-05-19 | 1992-04-01 | Linde Aktiengesellschaft | Method for making available treatment gases for heat treatments |
| DE4343927C1 (en) * | 1993-12-22 | 1995-01-05 | Linde Ag | Method for thermal treatment of workpieces under treatment gas |
| EP0778354A1 (en) * | 1995-12-07 | 1997-06-11 | Linde Aktiengesellschaft | Process for supplying controlled atmosphere gases into a heat treatment furnace and heat treatment plant |
| EP0856587A1 (en) * | 1997-01-29 | 1998-08-05 | Praxair Technology, Inc. | Process for the heat treatment of iron-based metal parts in an active atmosphere with a high potential of carbon |
| WO2005035799A1 (en) * | 2003-10-08 | 2005-04-21 | Messer Austria Gmbh | Method for heat-treating iron-containing materials |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3785989D1 (en) | 1993-07-01 |
| EP0261461A3 (en) | 1989-03-15 |
| DE3630833A1 (en) | 1988-03-17 |
| EP0261461B1 (en) | 1993-05-26 |
| ATE89868T1 (en) | 1993-06-15 |
| ES2042524T3 (en) | 1993-12-16 |
| BR8704618A (en) | 1988-04-26 |
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