EP2336372A2 - Method and device for regulating process gases for the thermoforming of metallic materials/workpieces in industrial ovens - Google Patents

Abstract

The method for controlling process gas for heat treatment of metallic materials/workpieces in industrial furnace (1), which comprises a treatment chamber (2), a combustion point (4) with a first valve (4.1) and a regulator (5) with pressure gauge, comprises processing the process gas in a component of a respective gas mixture in a limitable area and/or then utilizing as flushing gas in a rinse gassing. A quantity of the flushing gas of the gas mixture of the respective process gas is controllably guided to the industrial furnace and then burned in open combustion valve. The method for controlling process gas for heat treatment of metallic materials/workpieces in industrial furnace (1), which comprises a treatment chamber (2), a combustion point (4) with a first valve (4.1) and a regulator (5) with pressure gauge, comprises processing the process gas in a component of a respective gas mixture in a limitable area and/or then utilizing as flushing gas in a rinse gassing. A quantity of the flushing gas of the gas mixture of the respective process gas is controllably guided to the industrial furnace and then burned in open combustion valve. The rinsing gas of the combustion valve is closed, where the industrial furnace is controlled on a preset furnace pressure and is recorded permanently over the pressure gauges in such a way that a fresh gas valve is controlled so that a quantity of a fresh gas of the respective gas mixture of the process gas is provided necessary to a pressure reduction. The fresh gas valve is controlled in such a way that the pressure is recorded and held over the pressure gauges, where the combustion valve remains in the phase. The rinse gassing is activated and regulated. An excess pressure valve of the combustion point is opened to the pressure reduction controlled over a fixed limit value in large increase in pressure. A C-level required for the process independent from the pressure control of the furnace control is regulated by a C-potential regulator (3) and is adjusted over a gas- and air supply. The method is used for charge-wise heat treatment of the metallic materials/workpieces in the industrial furnace, which works according to break through principle. The activated rinse gassing is adjusted before a charge movement, a charge exchange or the loading of a charge. The controlled rinse gassing is activated until a rinsing time is expired or a selected carbon monoxide-level is reached. The requirement of the rinse gassing is initiated from the furnace control to liberate the furnace chamber of remnants of foreign gases. The method is used in inert gas recirculation systems for a gas carburization in which the components such as carbon dioxide, oxygen and water vapor is supplied with a hydrocarbon again to the carbon monoxide and hydrogen in an internal or an external treatment chamber of the industrial furnace in recirculating manner. A hand shifter and a shut-off valve are used for adjusting different combustion quantities in different combustion strands. An independent claim is included for a device for controlling process gases for heat treatment of metallic materials/workpieces in industrial furnace.

Description

Technical area

The invention relates to a method and a device for controlling process gases for heat treatment of metallic materials / workpieces in industrial furnaces having at least one treatment space, at least one Abbrandstelle with gas-tight sealable valve and a pressure control, wherein at least one component of the respective process gas in at least one process relevant Range of dimensions is processed.

State of the art

Generally, in industrial furnaces it is known that e.g. The flushing process is used for common carburizing fumigations. This means that a certain amount of inert gas is continuously fed continuously to the furnace and discharged from the furnace while burning (flaring) at a burn-off point. This purging is necessary in order to achieve a quasi-stationary equilibrium state in the atmosphere by mixing constantly-supplied inert gas and / or natural gas / air mixtures and thus to be able to regulate the C potential.

The disadvantage of this continuous furnace rinsing technique is, on the one hand, the thermal loss during flaring of the protective gas on the burnup and, on the other, the actual loss of gas, which must be compensated by new components of the process gas. In addition, the flared gas has a previously defined by the regulation C-potential, which is also no longer usable and simply burned.

According to the DE 10 2008 029 001.7 B 1 the process effect of the gas flow in industrial furnaces has been improved by supplying a hydrocarbon as required for carburization and protecting the C potential in the shielding gas and eliminating non-controllable and / or undesired reactions in order to save protective gas and reduce heating energy losses. This created a new inert gas recirculation system for gas carburization. In this react in a processing room of an industrial furnace, the components of carbon dioxide, oxygen and water vapor with a supplied hydrocarbon back to carbon monoxide and hydrogen, namely catalytically supported. Advantageously, the reprocessing of already "spent" inert gas, ie a protective gas with a low C potential is achieved. The C potential regulation takes place in the processing chamber of the treatment chamber. The "treated" protective gas can then be fed back into the treatment chamber at one or more points, so that a real cycle process for the gas carburization sets.

In this case, the protective gas is no longer burned regularly, but fed back to the heating chamber by recirculation, after it has undergone an intermediate step, the treatment in an internal or external treatment room. It is thus no longer flushed as before, but reused.

Due to the carburization inside the heating chamber, the concentrations of CO ₂ , H ₂ O and O _{2 increase} and the C level drops. This depleted gas is now not burned, but passed by means of a Umwälzers in said processing space, which is locally separated from the heating chamber. Here, by the finely dosed addition of natural gas, a C-level enrichment takes place, the following reactions take place and the concentrations fall again.

This according to the DE 10 2008 029 001.7 B 1 cited fumigation was according to the DE 10 2009 038 598.3 developed in which the generation and enrichment of the protective gas in this case can be done as a separate preparation and separate from the batch. Thus, the batch can always be charged with a homogeneous gas atmosphere.

But still require for process-related and safety reasons, industrial furnaces in the implementation of heat treatments with z. B. the process gases described a Abbrandstelle with gas-tight sealable valve and a pressure control, although. Not primarily a permanent flaring serves, but must also hold the function of an explosion protection. In the process, this burn-off point, which functions in this way, should be regularly closed in a gastight manner, but be able to open under certain conditions. Known Abbrandstellen in this context are functionally internally known state of the art by a permanent gas flow and thus disadvantageously characterized by high gas losses. The only mechanical solution is that one is not complete gastight final overpressure flap is provided to reduce overpressure occurring in the furnace chamber, which is not normally regulated, but at best opened according to empirical values set rigid.

Explanation of the essence of the invention

The invention has for its object to provide a method and a device for controlling process gases for heat treatment of metallic materials / workpieces in industrial ovens of the type mentioned, in which the Abbrandstelle is opened only depending on process gas related needs, in compliance both the safety as well as the process gas-saving conditions, this being solved by an arrangement of valves and valves, which release different and process-related burn rates.

1. a) in einem ersten Schritt bei geöffnetem Abbrandventil eine Menge eines Spülgases des Gasgemisches des jeweiligen Prozessgases dem Industrieofen gesteuert zugeführt und dann abgebrannt wird,
2. b) in einem zweiten Schritt nach dem vorgenanntem Schritt der Spülbegasung das Abbrandventil geschlossen wird, der Industrieofen auf einen voreingestellten Ofendruck geregelt und permanent über den Druckmesser erfasst wird, wozu mindestens ein Frischgasventil so geregelt wird, dass dieses eine zum Druckaufbau benötigte Menge eines Frischgases des jeweiligen Gasgemisches des Prozessgases bereitstellt und
3. c) in einem dritten Schritt bei erreichtem Solldruck des Industrieofens das Frischgasventil derart geregelt wird, dass dieser Druck weiterhin über den Druckmesser erfasst und gehalten wird, wobei in dieser Phase das Abbrandventil weiterhin geschlossen bleibt, um nur eine ggf. anfallende Verlustgasmenge zu ersetzen.

This object is achieved in a method for controlling process gases for heat treatment of metallic materials / workpieces in industrial furnaces, which have at least one treatment space, at least one Abbrandstelle with at least a first valve and a pressure control with pressure gauge, wherein the process gas in at least one component of a respective gas mixture is treated in a limited range and / or used as purge gas in a step of a Spülbegasung, basically solved by

1. a) in a first step with the burn-off valve open, an amount of a purge gas of the gas mixture of the respective process gas is supplied to the industrial furnace controlled and then burned off,
2. b) in a second step after the aforementioned step of flushing the burnup valve is closed, controlled the industrial furnace to a preset furnace pressure and permanently detected by the pressure gauge, including at least one fresh gas valve is controlled so that this required for pressure buildup amount of a fresh gas of provides respective gas mixture of the process gas and
3. c) in a third step at the setpoint pressure of the industrial furnace, the fresh gas valve is controlled such that this pressure is still detected and held by the pressure gauge, in which phase the burn-off valve remains closed to replace only a possibly resulting amount of lost gas.

Advantageously, in a fourth step, the rinsing fumigation (cf step one) can be activated and adjusted.

The method is further developed in that at a large pressure increase in a fifth step, a pressure flap of Abbrandstelle controlled to release pressure over a fixed limit is opened.

If the process requires the setting of a C-level, it can be regulated independently of the pressure control of the furnace control by at least one C-potential controller and adjusted via a gas and air supply.

The method can be used for batch heat treatments or for heat treatment of metallic materials / workpieces in industrial furnaces (1) that work according to the piercing principle.

The activated in the fourth step Spülbegasung can be adjusted before a batch movement, a batch change or the loading of a batch.

The controlled Spülbegasung can be activated until a purge time expired or a selected CO content is reached.

The purge purge request may be initiated from the furnace control to relieve the furnace chamber of foreign gas residuals.

The method is particularly suited for use in inert gas recirculation systems where, for gas carburization in an internal or external processing room of the industrial furnace, the components carbon dioxide, oxygen and water vapor react with a hydrocarbon feed to recirculate carbon monoxide and hydrogen.

In the case of a large increase in pressure, in the fifth step an overpressure flap of the burn-off point is opened, which in itself is ideally closed in a gastight manner during steps one to four.

The use of a manual valve in the burn-up makes the method applicable even in the special case, if due to very low amounts of gas depletion of the furnace atmosphere takes place and so a defined small amount of gas must be permanently burned, which is usually below the usual burn rates.

• in dem ersten Schritt im Sinne einer Steuerung nach Chargenwechsel bei geöffnetem Abbrandventil dem Industrieofen die Spülgasmenge des Gasgemisches zugeführt und abgebrannt wird, um den Ofenraum von Resten von Fremdgasen zu befreien, wobei diese gesteuerte Spülbegasung solange aktiv bleibt, bis eine Spülzeit abgelaufen oder der gewählte CO-Gehalt z.B. in einer Heizkammer des Industrieofen erreicht ist und die Anforderung der Spülbegasung aus der Ofensteuerung initiiert wird,
• in dem zweiten Schritt nach vorgenannter Spülphase im Sinne einer Regelung besagtes Abbrandventil geschlossen wird, die Regelung den Indutrieofen auf einen voreingestellten Ofendruck bringt, der permanent über einen Druckmesser erfasst wird, wozu ein Frischgasventil so gesteuert wird, dass dieses die zum Druckaufbau benötigte Frischgasmenge bereitstellt,
• in dem dritten Schritt im Sinne einer Regelung bei erreichtem Sollofendruck besagtes Frischgasventil so gesteuert wird, dass dieser Druck, weiterhin erfasst über den Ofendruckmesser, gehalten wird, wobei in dieser Phase das Abbrandventil weiterhin geschlossen ist, um nur die durch z.B. Undichtigkeiten benötigte Verlustgasmenge zu ersetzen, wobei der für den Prozess benötigte C-Pegel unabhängig von der Druckregelung von der Ofensteuerung geregelt und über Gas- und Luftzufuhr eingestellt wird und in dieser Phase das Abbrandventil im Normalfall geschlossen ist,
• in dem vierten Schritt die Spülbegasung (vgl. Schritt 1) aktiviert und vor z.B. einer Tür- und Chargenbewegung eingeregelt wird und schließlich
• in dem fünften Schritt bei großem Druckanstieg die Überdruckklappe zum Druckabbau gesteuert über einen festen Grenzwert hinaus geöffnet wird.

The method can particularly develop its advantages by combining a sequence of method steps one to five, if

• in the first step in the sense of a control after batch change with open burn-off valve the industrial furnace, the purge gas of the gas mixture is fed and burned to rid the furnace chamber of residues of foreign gases, this controlled Spülbegasung remains active until a purge time expired or the selected CO Content is reached, for example, in a heating chamber of the industrial furnace and the request for flushing fumigation is initiated from the furnace control,
• in the second step after said rinsing phase in the sense of a regulation said burn-off valve is closed, the control brings the indutry furnace to a preset furnace pressure, which is permanently detected by a pressure gauge, for which a fresh gas valve is controlled so that it provides the amount of fresh gas needed to build up pressure,
• said fresh gas valve is controlled in the third step in the sense of a regulation at Sollominendruck reached so that this pressure, further recorded on the furnace pressure gauge, is maintained, in which phase the burn-off valve is still closed to replace only the loss of gas required by eg leaks , wherein the required for the process C-level is controlled independently of the pressure control of the furnace control and adjusted by gas and air supply and in this phase, the burn-off valve is normally closed,
• in the fourth step, the rinsing fumigation (see step 1) is activated and regulated before, for example, a door and batch movement, and finally
• in the fifth step, when the pressure increases greatly, the overpressure flap is opened in a controlled manner to reduce the pressure above a fixed limit value.

• eines Druckes,
• einer Temperatur und/oder
• von Zusammensetzungen der Komponenten des Prozessgases

aufweisen.For the purposes of the invention, the above-mentioned finite region for the treatment of the process gas in at least one component of a respective gas mixture may have the dimensions

• a print,
• a temperature and / or
• of compositions of the components of the process gas

exhibit.

Furthermore, the mentioned processing space of the industrial furnace can be used both in accordance with DE 10 2008 029 001.7 B1 internally or according to the DE 10 2009 038 598.3 be formed externally, wherein the latter is a generation and enrichment of a protective gas as a separate preparation and separated from the batch.

1. a) die Aufbereitungskammer für die Aufbereitung des Prozessgases,
2. b) mindestens eine Abbrandstelle für den Abbrand des Spülgases mit mindestens einem Abbrandventil für eine gesteuerte Abführung einer Menge des Spülgases des Gasgemisches,
3. c) die Druckregelung mit Druckmesser für den voreinstellbaren und permanent erfassbaren Ofendruck und
4. d) ein Frischgasventil für die Bereitstellung der zum Druckaufbau benötigten Menge des Frischgases des jeweiligen Gasgemisches des Prozessgases.

The device for carrying out the method comprises

1. a) the processing chamber for the treatment of the process gas,
2. b) at least one burning point for the combustion of the purge gas with at least one burn-off valve for a controlled discharge of an amount of the purge gas of the gas mixture,
3. c) the pressure control with pressure gauge for the presettable and permanently detectable furnace pressure and
4. d) a fresh gas valve for the provision of the required pressure to build up the amount of fresh gas of the respective gas mixture of the process gas.

The gastight sealable overpressure flap of Abbrandstelle for controlled pressure reduction completes the device.

By acting independently of the pressure control of the furnace control C-potential controller, the regulated adjustment of the gas and air supply takes place.

For special cases, such as too small amounts of gas lost from the furnace, a manual valve is provided in order to generate an at least necessary for the maintenance of the atmospheric composition loss gas by gas erosion.

The device comprises valves as solenoid valves or adjustable valves, which are controlled depending on the process state in the oven and release the flow to Abbrandstelle. In different combustion strands so different amounts of gas can be burned. Depending on the program step, furnace pressure and the atmosphere composition, different valves are activated and so only the minimum required amount of gas is burned off. In the event of a malfunction, all valves release the passage and thus enable a quick rinsing out of the oven chamber. A hitherto also usual overpressure flap according to the invention but now designed so that it closed up to a certain furnace pressure tightly closed and opens regulated when exceeded and thus - also substantially regulated - ensures rapid pressure reduction.

The furnace pressure regulation takes place via the controlled addition of a gas mixture. Normally, the burning point is closed by means of the overpressure flap. For pressure control, the furnace pressure is constantly detected and fed to the required for holding the pressure mixture amount.

In the case of pressure rise gasification, the maximum possible gas mixture quantity is supplied when a minimum furnace pressure is not reached until a set opening time of the valves has expired or a preset furnace pressure has been reached. The control of the Abbrandventile takes place here analogous to the furnace pressure control.

Brief description of the figures

Fig. 1

den verfahrensgemäßen Ablauf einer erfindungsgemäßen Regelung als schematisches Blockschaltbild in einem ausgewählten Beispiel und

Fig. 2

ein Ausführungsbeispiel betreffend eine Anordnung eines Abbrandventils und einer mit Handschieber und Magnetventil ausgestatteten zweiten Abbrandleitung

In the drawings show

Fig. 1

the procedural sequence of a control according to the invention as a schematic block diagram in a selected example and

Fig. 2

an embodiment relating to an arrangement of a Abbrandventils and equipped with manual and solenoid valve second Abbrandleitung

Best way to carry out the invention

In the Fig. 1 is shown schematically in one embodiment, an industrial furnace 1 with a treatment room 2. The treatment chamber 2 is connected to a control 5 via a pressure gauge 5.1 in connection, the control 5 both request signals for a Spülbegasung from a conventional furnace control 9 and receives signals from a C-potential controller 3 and the pressure gauge 5.1 on the furnace pressure. Furthermore, the controller 5 receives values from a CO analyzer 8.

The control gives signals for opening or closing a, e.g. as a solenoid valve Abbrandventils 4.1, a Abbrandstelle 4 and signals of a. when . Solenoid valve running fresh gas valve. 7

• in einem ersten Schritt wird im Sinne einer Steuerung nach z.B. einem Chargenwechsel bei geöffnetem Abbrandventil 4.1 dem Industrieofen 1 eine Spülgasmenge 6.1 eines Gasgemisches zugeführt und abgebrannt, um den Ofenraum von Resten von Fremdgasen zu befreien, wobei diese gesteuerte Spülbegasung solange aktiv bleibt, bis eine Spülzeit abgelaufen oder der gewählte CO-Gehalt z.B. in einer nicht näher dargestellten Heizkammer, gemessen über den CO-Analysator 8, des Industrieofen erreicht ist und die Anforderung der Spülbegasung aus der üblichen Ofensteuerung 9 initiiert wird,
• in dem zweiten Schritt wird nach vorgenannter Spülphase im Sinne einer Regelung besagtes Abbrandventil 4.1 geschlossen, die Regelung 5 den Industrieofen auf einen voreingestellten Ofendruck bringen, der permanent über den Druckmesser 5.1 erfasst wird, wozu die Einstellung des Frischgasventils 7 so gesteuert wird, dass dieses eine zum Druckaufbau benötigte Frischgasmenge 6.2 bereitstellt,
• in dem dritten Schritt wird im Sinne einer Regelung bei erreichtem Sollofendruck besagtes Frischgasventil 7 so gesteuert, dass dieser Druck, weiterhin erfasst über den Druckmesser 5.1, gehalten wird, wobei in dieser Phase das Abbrandventil 4.1 1 weiterhin geschlossen ist, um nur die durch z.B. Undichtigkeiten benötigte Verlustgasmenge zu ersetzen, wobei der für den Prozess benötigte C-Pegel unabhängig von der Druckregelung von der Ofensteuerung über den C-Potentialregler 3 geregelt und über Gas- und Luftzufuhr eingestellt wird.

According to the method

• In a first step, in the sense of a control after, for example, a batch change with open burn-off 4.1 the industrial furnace 1 a purge gas 6.1 of a gas mixture supplied and burned to rid the furnace chamber of residues of foreign gases, said controlled Spülbegasung remains active until a purge time has expired or the selected CO content, for example, in a heating chamber, not shown, measured via the CO analyzer 8, the industrial furnace is reached and the request of Spülbegasung from the usual furnace control 9 is initiated
• In the second step, after the aforementioned rinsing phase in the sense of a regulation, said burn-off valve 4.1 is closed, the control 5 bring the industrial furnace to a preset furnace pressure, which is permanently detected by the pressure gauge 5.1, for which purpose the setting of the fresh gas valve 7 is controlled so that this one fresh gas quantity 6.2 required for building up pressure
• in the third step, said fresh gas valve 7 is controlled in the sense of a control when the setpoint pressure has been reached so that this pressure, which is still recorded via the pressure gauge 5.1, is maintained, whereby in this phase the burn-off valve 4.1 1 is still closed in order to prevent only leakage, for example Required loss of gas to replace, the required for the process C-level is controlled independently of the pressure control of the furnace control via the C-potential controller 3 and adjusted via gas and air supply.

This sets the basic principle of the procedure.

In this example, in a fourth step, the rinsing fumigation (see step 1) is activated and regulated before, for example, door and batch movement.

Finally, in a fifth step with a large increase in pressure, an overpressure flap 4.3 controlled to release pressure can be opened beyond a fixed limit value.

• a) die Aufbereitungskammer 2 für die Aufbereitung des Prozessgases,
• b) mindestens die eine Abbrandstelle 4 für den Abbrand des Spülgases 6.1 mit mindestens einem Abbrandventil 4.1,
• e) die Regelung 5 mit Druckmesser 5.1 für den voreinstellbaren und permanent erfassbaren Ofendruck und
• f) mindestens einem Frischgasventil 7 für die Bereitstellung der benötigten Spülgasmenge 6.1 und der zum Druckaufbau benötigten Menge des Frischgases 6.2 des jeweiligen Gasgemisches des Prozessgases und
• g) die gasdicht verschliessbare Überdruckklappe 4.3 der Abbrandstelle 4 zum gesteuerten Druckabbau.

For this, the device for carrying out the method essentially comprises.

• a) the treatment chamber 2 for the treatment of the process gas,
• b) at least one burn-off point 4 for the burn-up of the flushing gas 6.1 with at least one burn-off valve 4.1,
• e) the regulation 5 with pressure gauge 5.1 for the presettable and permanently detectable furnace pressure and
• f) at least one fresh gas valve 7 for the provision of the required purge gas quantity 6.1 and the amount of fresh gas required 6.2 of the respective gas mixture of the process gas and
• g) the gas-tight sealable overpressure flap 4.3 of burn-off point 4 for controlled pressure reduction.

An associated manual valve 4.2 with shut-off valve 4.4 allows by appropriate slide positions the continuous burning of a small amount of exhaust gas.

Industrial Applicability

The invention makes it possible that the Abbrandstelle 4 is opened only in response to process gas-related needs, in compliance with both the safety conditions and the environmentally friendly saving of process gases.

LIST OF REFERENCE NUMBERS

1

= Industrial furnace

2

= Treatment room

3

= C potential controller

4

= Burning point

4.1

= Burn-off valve

4.2

= Hand slider

4.3

= Overpressure flap

4.4

= Shut-off valve

5

= Regulation

5.1

= Pressure gauge

6

= Gas mixture

6.1

= Amount of purge gas

6.2

= Amount of fresh gas

7

= Fresh gas valve

8th

= CO analyzer

9

= Oven control

Claims (18)

Method for controlling process gases for heat treatment of metallic materials / workpieces in industrial furnaces (1), having at least one treatment space (2), at least one burnup point (4) with at least one first. Valve (4.1) and a. Having control (5) with pressure gauge (5.1), wherein the process gas is treated in at least one component of a respective gas mixture (6) in a limited range and / or used as purge gas (6.1) in a step of a Spülbegasung, characterized in that a) in a first step with the burn-off valve (4.1) open, a quantity of a flushing gas (6.1) of the gas mixture (6) of the respective process gas is supplied to the industrial furnace (1) in a controlled manner and then burned off, b) in a second step after the aforementioned step of Spülbegasung the burn-off valve (4.1) is closed, the industrial furnace (1) regulated to a preset furnace pressure and permanently detected by the pressure gauge (5.1), including the fresh gas valve (7) is regulated in that this provides a quantity of a fresh gas (6.2) of the respective gas mixture (6) of the process gas required for pressure build-up and c) in a third step at the setpoint pressure of the industrial furnace, the fresh gas valve (7) is controlled so that this pressure continues to be detected and held by the pressure gauge (5.1), wherein in this phase the burn-off valve (4.1) remains closed to only replace any accumulated loss gas. A method according to claim 1, characterized in that in a fourth step, the flushing fumigation (see step a)) is activated and adjusted. A method according to claim 1 or 2, characterized in that at a large pressure increase in a fifth step, an overpressure flap (4.3) of the Abbrandstelle (4) controlled to release pressure over a fixed limit value is opened. Method according to one of claims 1 to 3, characterized in that a required for the process C-level regardless of the pressure control of the furnace control is regulated by means of at least one C-potential controller (3) and adjusted via a gas and air supply. Method according to one of claims 1 to 4, characterized by its application for batch heat treatments of metallic materials / workpieces. Method according to one of claims 1 to 5, characterized by its use in heat treatments in industrial furnaces (1), which operate on the piercing principle. Method according to one of claims 1 to 6, characterized in that in the fourth step, the activated Spülbegasung is adjusted before a batch movement, a batch change or the loading of a batch. Method according to one of claims 1 to 7, characterized in that the controlled Spülbegasung is activated until a purge time has expired or a selected CO content is reached. Method according to one of claims 1 to 8, characterized in that the request of Spülbegasung is initiated from the furnace control to free the furnace chamber from residues of foreign gases. Method according to one of claims 1 to 9, characterized by its use in inert gas recirculation systems for gas carburizing, in which react in an internal or external processing space of the industrial furnace (1) the components carbon dioxide, oxygen and water vapor with a hydrocarbon supplied to carbon monoxide and hydrogen recirculating , Method according to one of Claims 1 to 10, characterized in that the overpressure flap (4.3) of the burn-up point (4) which opens at a large pressure rise in the fifth step is closed in a gastight manner during steps one to four. Method according to one of claims 1 to 11, characterized by the use of a manual valve (4.2) and a shut-off valve (4.4) for setting different amounts of burn-off in different combustion strands. Method according to one of claims 1 to 12, characterized by the combination of a sequence of method steps one to five. Apparatus for carrying out the method, comprising d) a treatment chamber for the treatment of the process gas, e) at least one burn-off point (4) for burning off a flushing gas (6.1) with at least one burn-off valve (4.1) for controlled removal of a quantity of the flushing gas (6.1) of the gas mixture (6), f) a control (5) with pressure gauge (5.1) for a presettable and permanently detectable furnace pressure and g) a fresh gas valve (7) for providing a required for pressure buildup amount of a fresh gas (6.2) of the respective gas mixture (6) of the process gas. Apparatus according to claim 14, characterized by a gas-tight sealable overpressure flap (4.3) of the Abbrandstelle (4) for the controlled pressure reduction. Apparatus according to claim 14 or 15, characterized by an independent of the pressure control of the furnace control acting C-potential controller (3) for the controlled adjustment of a gas and air supply. Device according to one of Claims 14 to 16, characterized by a manual slide (4.2) for setting different burnup quantities in different burnup strands. Device according to one of claims 14 to 17, characterized by the combination a) the treatment chamber (2) for the treatment of the process gas with at least one Abbrandstelle (4) for the combustion of a purge gas (6.1), at least one Abbrandventil (4.1) for a controlled discharge of an amount of purge gas (6.1) of the gas mixture (6) , a pressure control (5) with Pressure gauge (5.1) for a presettable and permanently detectable furnace pressure and a fresh gas valve (7) for providing a required amount of pressure to build up a fresh gas (6.2) of the respective gas mixture (6) of the process gas, b) a gas-tight closable overpressure flap (4.3) of the burn-off point (4) for controlled pressure reduction, c) acting independently of the pressure control of the furnace control C-potential controller (3) for the controlled adjustment of a gas and air supply and d) a manual valve (4.2) and a shut-off valve (4.4) for setting different burnup rates in different burnup strands.

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