EP2508829A1 - Method and industrial furnace for use of a protective gas as a heating gas - Google Patents

Abstract

To increase the energy efficiency in an industrial furnace (1) operated by means of heating gas and inert gas for the heat treatment of materials, a first burner (3.1) is operated in front of a second burner (1.2) for heating, the second burner (3.2) is then switched on and operated, if a power of the first burner (3.1) required to reach a temperature setpoint of the industrial furnace (1) has fallen below, and the second burner (3.2) is then switched off and not operated when the temperature setpoint is reached (FIG. 2).

Description

Technical area

The invention relates to a method and an industrial furnace for the use of a protective gas arising as a heating gas, primarily for use in an industrial furnace as well as multi-chamber furnace or pusher furnace comprising a high-temperature furnace and an upstream preheating furnace. The inventive method is applicable to any processes and industrial furnaces, where a heat treatment of materials using heating gas and inert gas takes place.

It is assumed that the pertinent experts - such as the DE 10 2008 020 449 A1 - Can already perform generic industrial furnaces so that in principle an energy-efficient operation is feasible. This includes in particular that the housing at least partially surrounding and spaced from the housing wall insulating provided and between the housing wall and insulating convection chambers can be formed.

However, the priority is to improve the process of using gas as well as protective gases from the outset.

State of the art

The so-called endogas accumulating in industrial furnaces is technically and functionally defined as a gas mixture generated in the generator, which can be used as protective gas against oxidation.

The protective gas used in industrial furnaces is any gas mixture which protects against unwanted chemical reactions on the component to be heat-treated. For example, Nitrogen used as a protective gas against oxidation and carburization and decarburization.

A so-called endogas can only protect against oxidation as a protective gas, as carbon is released. Endogas is thus a carbon carrier gas, which serves for the carburization of components.

For the purposes of the invention, although the resulting protective gas includes the standard but limited functional designation Endogas in professional circles, but the invention is not limited solely to accumulating endogas.

In the case of industrial furnaces working with inert gas, the experts have already dealt with the reduction of pollutant emission values sufficiently, as is the case for example in EP 0 282 715 has been described.

In addition, however, it is also about using the energy content of unused gases in the process.

• Gemäß DE 34 32 952C2 wird die Aufgabe erkannt, die Brenner, die während des Öffnens des Ofens im Bereich der Ofenöffnungen Brenngase verbrennen, auf einfache und wirtschaftliche Weise zu betreiben. Erfindungsgemäß soll dort das Abgas des Ofens gekühlt, verdichtet und gespeichert und anschließend zumindest teilweise einem oder mehreren Brennern im Bereich der Ofenöffnungen als Brenngas zugeführt werden. Dazu wird eine geeignete Vorrichtung vorgeschlagen.

Here are characterized methods for using the energy content of effluent from industrial furnace systems furnace exhaust gases, which include the following solutions:

• According to DE 34 32 952 C2 the task is recognized, the burners that burn during the opening of the furnace in the oven openings combustion gases, to operate in a simple and economical manner. According to the invention, the exhaust gas of the furnace is cooled there, compressed and stored and then at least partially fed to one or more burners in the region of the furnace openings as fuel gas. For this purpose, a suitable device is proposed.

By using the exhaust gas as the fuel gas, the heat veils can be formed completely independent of Petroprodukten.

A further improved and known method for utilizing the energy content of the kiln exhaust gases flowing out of industrial furnaces is provided according to DE 197 20 620 A1 to collect at least part of it and to reuse it for heating, possibly also with the addition of another heating medium.

An advantageous variant of the method thus consists in that the furnace exhaust gas is tapped out of the furnace at least at a significant Ausflußstelle and with a fan - optionally with the addition of further fuel - one or more, to supply conventional heating radiant tubes of the furnace.

The furnace exhaust gases can be supplied under additional pressure or by suction combustion.

In known in the art, including multiple chambers or treatment rooms comprehensive industrial furnace systems, such. also in push-through furnace systems, according to the process gases used, the process steps known at least according to an internal prior art proceed as follows:

a) Gas start and burner start in a pusher furnace

There is a supply of natural gas in this case in an associated preheating furnace via a loop of a so-called high-temperature furnace, initially a gas type is triggered. Then runs in a control device from an automatic start routine, in the course of a tightness control of the loop is performed.

b) Gas start and burner start in the preheating furnace

Analogously to step a), the automatic start routine also runs from here in the control device. If so-called open burners are used here, the industrial furnace must first be brought into a safe ground state. For this purpose, the furnace doors are first closed, and the industrial furnace is purged via air lines of the participating burner with a 5 times oven volume in air. Then, a tightness control is performed by means of a tightness control unit on the Heizgaswie natural gas line. Before starting the burner, the oven doors are opened again. Then this burner and a so-called pilot burner are started. For example, if burner ionization monitoring signals a stable flame, the oven doors are closed again and the preheat oven is brought to operating temperature by the burner (as a heating burner). wherein the pilot burns until the preheat furnace is switched off again.

c) Fumigation of the pusher furnace

After a temperature of eg at least 750 ° C is exceeded,
the pusher furnace can be gassed with inert gas. Depending on the type of gasification either so-called endogas or nitrogen / methanol as carrier gas is introduced into the system. The proper fumigation of the pusher is completed when a set via a pressure relief flap of the overpressure is reached and at the same time has set a target C-level in the oven.

An analysis of these ongoing process steps showed due to the effluent and abzubrennenden kiln exhaust gases that the use of these so-called endogas as inert gas combustion for increasing the energy efficiency of an industrial furnace is in need of improvement.

Presentation of the invention

The invention is based on the object to increase the efficiency of inert gas as Endogasverbrennung in industrial furnaces in general and especially in multi-chamber ovens as well as pusher ovens and use the resulting, but so far without further energetic use effluent protective gas as heating gas more efficient, such. also in a high-temperature furnace and preheating furnace comprising the pusher furnace systems.

1. a) Gasstart und Brennerstart in einem Industrieofen,
2. b) Gasstart und Brennerstart auch in einem zugehörigem Vorwärmofen und/oder
3. c) Begasung des Industrieofens
   sowieso erfolgen können, sodann erfindungsgemäß darüber hinausgehend
4. d) eine Einstellung eines ersten Brenners als Schutzgasbrenner durchgeführt wird, wobei dann erfindungsgemäß die Schritte und/oder Bedingungen
5. e) Start des ersten Brenners,
6. f) Betrieb des ersten Brenners,
7. g) Abschalten des ersten Brenners,
8. h) Ausfall des ersten Brenners,
9. i) Beachtung eines zu geringen Druckes vor dem ersten Brenner beim Betrieb desselben

ablaufen oder eingehalten werden.The invention solves this problem for the process conditions of an industrial furnace so that initially as described above, the steps

1. a) gas start and burner start in an industrial furnace,
2. b) Gas start and burner start also in an associated preheating furnace and / or
3. c) Fumigation of the industrial furnace
   anyway, then according to the invention beyond
4. d) an adjustment of a first burner is carried out as a protective gas burner, in which case according to the invention the steps and / or conditions
5. e) start of the first burner,
6. f) operation of the first burner,
7. g) switching off the first burner,
8. h) failure of the first burner,
9. i) Note that the pressure in front of the first burner is too low during operation

expire or be complied with.

1. 1. Die Verwendung des ersten Brenners als Schutzgasbrenner, in welchem das Schutzgas mit einem gegenüber dem Heizgas wie Erdgas geringerem Brennwert verbrannt wird, wobei
   • für eine sichere Zündung des Schutzgases für den ersten Brenner als Schutzgasbrenner ein permanent brennender, mit Heizgas wie Erdgas betriebener dritter Brenner als Zündbrenner und/oder
   • zur Überwachung einer Brennerflamme eine UV-Sonde verwendet werden;
2. 2. eine funktionserhaltende Versorgung des ersten Brenners (Schutzgasbrenner) mittels eines das Schutzgas z.B. aus einer Eingangsschleuse der Ofenanlage wie z.B. Durchstoßofenanlage absaugenden Gebläses, wobei
   • zur Regelung einer Absaugmenge das Gebläse frequenzgeregelt wird,
   • zum Schutz vor Überhitzung das Gas in einer Gaskühleinrichtung gekühlt wird;
   • mittels des Gebläses der Druck des Gases auf den für den ersten Brenner erforderlichen Wert verändert wird,
   • der Druck in der Leitung mit Hilfe eines z.B. Drucksensors permanent überwacht und mit Hilfe eines Frequenzumformers des Gebläses innerhalb eines bestimmten Druckbereichs gehalten wird und/oder
   • unter ständiger Kontrolle des Ofendrucks mittels eines Ofendruckmeßumformers geregelt wird;
3. 3. die zusätzliche Verwendung eines zweiten Brenners als eigentlichen Heizgasbrenner oder herkömmlichen Heizbrenners zum alleinigen Heizen des z.B. Vorwärmofens für den Fall, daß kein Schutzgas aus der z.B. Durchstoßanlage zur Verfügung steht, wobei der einsatzfähige erste Brenner als Schutzgasbrenner vorrangig für die Beheizung des Ofens verwendet und der zweite Brenner als Heizbrenner nur dann zugeschaltet wird, wenn die Leistung des ersten Brenners für das Heizen nicht ausreicht.

For this purpose:

1. 1. The use of the first burner as a protective gas burner, in which the protective gas is burned with a relation to the heating gas such as natural gas lower fuel value, wherein
   • for a secure ignition of the protective gas for the first burner as a protective gas burner a permanently burning, operated with fuel gas such as natural gas third burner as a pilot burner and / or
   • to monitor a burner flame, a UV probe is used;
2. 2. a function-maintaining supply of the first burner (inert gas burner) by means of a protective gas, for example, from an entrance lock the furnace such as pusher exhaust system fan, wherein
   • for controlling a suction amount, the fan is frequency-controlled,
   • to prevent overheating, the gas is cooled in a gas cooler;
   • the pressure of the gas is changed to the value required for the first burner by means of the blower,
   • the pressure in the pipe is permanently monitored by means of eg a pressure sensor and kept within a certain pressure range by means of a frequency converter of the fan and / or
   • is controlled under constant control of the furnace pressure by means of a kiln pressure transducer;
3. 3. the additional use of a second burner as the actual fuel gas burner or conventional heating burner for heating only the example preheating furnace in the event that no protective gas from the example puncture is available, the operational first burner used as a protective gas burner primarily for the heating of the furnace and the second burner is only switched on as a heating burner if the output of the first burner is insufficient for heating.

This general procedure according to the invention is intensified under the conditions of the above process conditions a) to c) and after the above step d), namely the setting of the first burner as protective gas burner, by the following steps according to the invention:

e) Start of the first burner

Prior to the start of the first burner as a protective gas burner analogous to the start of the second burner (fuel gas burner, natural gas burner) in the furnace system such as pusher first carried out a tightness control by means of a leak control unit. For this purpose, prevail in a main valve such as gas solenoid valve in the line for the inert gas a form. Before the tightness control, the above-mentioned fan is turned on, which promotes the inert gas against the closed main valve. A burning point on, for example, an inlet lock of the furnace is opened during the tightness control, since in the meantime no gas is removed from the furnace via the first burner. After the tightness check, the first burner is started and the burning point is closed.

The further step according to the invention consists in the following:

f) Operation of the first burner

After the first burner has been started as a shielding gas burner, it receives priority in operation before the second burner. This means that the second as actual heating or natural gas burner is always switched on only when the power of the first burner to reach the temperature setpoint in the furnace system such as the preheating oven is not sufficient. In the opposite case, this also means that only the second burner is always switched off as inert gas burner when the setpoint of the furnace is reached. Only when the temperature then rises even further, the power of the first burner such as inert gas burner, e.g. be steadily reduced via an air control flap as a throttle for the air.

If the e.g. If the amount of gas removed from the pusher furnace should temporarily lead to a slight increase in the furnace pressure, this is acceptable within limits, since correspondingly more gas is released via a burn-off point - e.g. even on an oil bath - can be discharged. Nevertheless, the first burner is switched off as a shielding gas burner at a defined maximum value of the furnace pressure, and the Abbrandstelle on the entrance lock is opened. This reduces the furnace pressure quickly again. If the preheating furnace needs energy for preheating, the first burner is switched on as a protective gas burner.

Optionally, the following situation as a method step is considered and expanded with the invention:

g) switching off the first burner

If the industrial furnace such as pusher furnace is in operating states in which no safe protective gas supply to the first burner is guaranteed, this is switched off and the heating of the example preheating takes place exclusively on the second burner as a natural gas or heating burner. This can be done during the opening hours of the Doors be the case. After opening the doors, the first burner is not switched on again as a shielding gas burner until the furnace pressure has reached a specified nominal value.

With the invention, the following operating situation can be configured with a further step:

h) Failure of the first burner as inert gas burner

Should the first burner fail due to a malfunction and not be able to start, a main valve, such as a valve, will promptly be opened. Solenoid valve closed, the fan switched off and a shut-off valve opened. In this case, only the second burner, such as natural gas burner or heating burner, takes over the heating of the preheating furnace.

Finally, the invention also perfects the following situation:

i) Pressure too low in front of the first burner

As a controlled variable for the frequency converter of the blower for the shielding gas, the pre-pressure before the first burner is used. The target is a pre-printed form of e.g. about 20-30 mbar constant. If this pressure drops, the speed of the fan is increased via the frequency converter.

In summary, the method according to the invention, involving the steps described above and a related device on an industrial furnace designed as a pusher run with a high-temperature furnace upstream preheating oven so that the performance of the first burner is continuously controlled as a protective gas burner during operation in the preheating oven to the optimally utilize the amount of inert gas available to the high-temperature furnace:

The available amount of inert gas is initially determined by the fact that the burnup of the high temperature furnace and possibly the oil bath adjusted with respect to the Ausströmvolumens and beyond the weight load of check valves at the Abbrandstellen the furnace pressure can be set at the first commissioning of the system.

Then, after these adjustments, the high temperature furnace is continuously gassed with inert gas. Thus, the protective gas volume flow is fixed, with which the first burner can be supplied as inert gas burner. It is created the condition that just as much inert gas can be burned as quasi heating gas, as would flow out of the burn-off point at the entrance lock of the high-temperature furnace according to the prior art or otherwise.

For this reason, serves as a controlled variable for the first burner, the furnace pressure of the high-temperature furnace. If the furnace pressure rises, an air control flap in front of the first burner is opened further, whereby the power and thus the gas consumption of the first burner increases.

If, due to the larger gas intake of the first burner, the pre-pressure should drop before this, the speed of the fan is increased by means of a frequency converter, whereby the delivery volume increases. The speed is increased until a constant pre-pressure in front of the first burner of e.g. 20-30 mbar.

With decreasing furnace pressure, the air control flap is closed again to reduce the power of the first burner.

Before the start of the first burner - as in a conventional natural gas burner practiced as Heizgasbrenner - first performed a tightness control (this purpose, a tightness control unit according to TC410 from Kromschröder can be used).

Prerequisite for the performance of the Dichtiekeitskontrolle is that in front of the main valve in the supply line for the inert gas prevails. For this reason, the fan is switched on before the start of the leak check, which promotes against the closed main valve.

The burn-off point of the high-temperature furnace is opened during the leak-tightness control, since no gas is removed from the furnace via the first burner in this state (ie currently). Only when the tightness check has been successfully completed will the first burner be started and the burn-off point will be closed.

After the first burner has been started in this way, the processes according to the invention have the effect that the operation of the first burner as a protective gas burner takes precedence over the second burner as a heating burner.

This means that the second burner is always switched on only when the power of the first burner is insufficient to reach the temperature setpoint of the preheating furnace.

In the opposite case, only the second burner heating burner is always switched off when the setpoint for the heating of the furnace is reached. Only when the temperature rises even further, the power of the first burner via the air control flap can be steadily reduced.

If the amount of gas temporarily removed from the high-temperature furnace should lead to a slight increase in the furnace pressure, this can be controlled to a limited extent, especially since correspondingly more gas is emitted via the burn-off point - such as, for example. at the oil bath - is dischargeable.

In principle, the first burner is switched off at a maximum value of the furnace pressure which still has to be defined, and the burning point at the entrance lock is opened. This will quickly reduce the furnace pressure again. If the preheat furnace needs heating energy of this kind again, the first burner will be switched on anyway.

Only when the high-temperature furnace is in operating states in which no safe protective gas supply to the first burner is ensured, this is switched off. The heating of the preheating furnace then takes place exclusively via the second burner as a heating burner.

This situation may e.g. during the door opening times. Therefore, after opening the doors, the first burner is switched on again as a protective gas burner when the furnace pressure has reached the setpoint.

If the first burner fails as a protective gas burner due to an unforeseeable disturbance and can not be restarted, the main valve is closed according to the invention, the fan is switched off and the shut-off valve is opened. In this case, the second burner takes over the heating of the preheating furnace.

If the pressure in front of the first burner is too low, the pre-pressure upstream of the first burner is used as the controlled variable for the frequency converter of the blower. The aim is to obtain a pre-printed form of e.g. 20-30 mbar constant. If the pressure drops, the speed of the fan is increased via the frequency converter.

The invention disclosed herein is determined by the method according to the features of claims 1 to 10, for which purpose an industrial furnace can be used which comprises the features of claims 11 to 16.

The invention will be further described by way of example with reference to an example of an industrial furnace and the method of the invention with reference to schematic drawings.

Brief description of the drawings

• Fig. 1 das Funktionsschema eines erfindungsgemäßen Industrieofens zur Durchführung des Verfahrens am Beispiel eines Durchstoßofens mit Hochtemperaturofen und Vorwärmofen und
• Fig. 2 ein Fließbild eines zusammenhängenden erfindungsgmäßen Verfahrensablaufs mit den Schritten und Bedingungen analog eines dafür einsetzbaren Programms.

Show it

• Fig. 1 the functional diagram of an industrial furnace according to the invention for carrying out the method using the example of a pusher furnace with high-temperature furnace and preheating furnace and
• Fig. 2 a flow diagram of a coherent erfindungsgmäßen process flow with the steps and conditions analogous to a program that can be used.

Best way to carry out the invention

According to Fig. 1 an industrial furnace 1 designed as a pusher furnace installation comprises a high-temperature furnace 2 with a door 2.1 for loading and a door for discharge 2.2 of batches of heat-treatable components and an exhaust gas burner 2.4 arranged at a combustion point 2.5, to which a shut-off valve 2.5.1 and an overpressure flap 2.8 are assigned.

The high-temperature furnace 2 is preceded by a Vorwärmofen 3 with a door for loading 3.5 and a door for discharging 3.6 to be treated with preheat batches of components comprising a first burner 3.1 with the first control device 3.1.1 and a second burner 3.2 with second control 3.2. 1 has.

The thus formed industrial furnace 1 is a supply line for a heating gas 4 with a tightness control unit 4.1, a supply line with a main valve 5.1 for a by means of a blower 7 eligible, by means of a gas cooling device 2.6 cooled and controllable by a third control device 2.7 inert gas 5 and a supply line for air 6 associated with an air damper 6.1 as throttle.

A control and regulation unit 8 links the first control device 3.1.1, second control device 3.2.1 and third control device for the functions of the process according to the process for the use according to the invention of the resulting protective gas as a heating gas according to the method described below.

From the Fig. 2 the process according to the procedure of the use of the resulting protective gas as heating gas in a program algorithm is shown in a comprehensible manner. This is stored in the control and regulating unit 8, so that the first burner 3.1 is operated mainly in front of the second burner 1.2 for heating the industrial furnace 1, the second burner 3.2 is then switched on and operated when one to achieve a temperature setpoint of Industrial furnace 1 required power of the first burner 3.1 is exceeded, and the second burner 3.2 is then turned off and not operated when the temperature set point is reached.

• ein mit Heizgas versorgter, als Sicherheitszündbrenner für den ersten Brenner 3.1 betriebener dritter Brenner 3.3 verwendet,
• zur Überwachung des ersten Brenners 3.1 eine UV-Sonde 3.4 eingesetzt,
• das Gebläse 7 über einen Frequenzumformer geregelt,
• bei einem Ansteigen der Temperatur über einen Temperatur-Sollwert die Leistung des ersten Brenners 3.1 durch Verwendung der Luftregelklappe 6.1 als reduziert und
• bei einem Anstieg des Druckes im Industrieofen 1 entsprechend mehr Schutzgas über die Abbrandstelle 2 abgeführt, der erste Brenner 3.1 bei einem definierten Höchstwert des Drucks abgeschaltet, die Abbrandstelle 2.5 geöffnet und der Druck reduziert, wobei der erste Brenner 3.1 bei einem Bedarf an Leistung im Industrieofen 1 wieder eingeschaltet wird.

With reference to Fig. 1 be there

• a third burner 3.3 supplied with heating gas and operated as a safety ignition burner for the first burner 3.1,
• used to monitor the first burner 3.1 a UV probe 3.4,
• the fan 7 is controlled by a frequency converter,
• with an increase in temperature over a temperature setpoint, the power of the first burner 3.1 by using the air damper 6.1 as reduced and
• with an increase in the pressure in the industrial furnace 1 correspondingly more protective gas is discharged via the burn-off point 2, the first burner 3.1 is switched off at a defined maximum value of the pressure, the burn-off point 2.5 opened and the pressure is reduced, the first burner is switched on 3.1 when a need for power in the industrial furnace 1 again.

1. a) als Gasstart und Brennerstart,
2. b) als Gasstart und Brennerstart in dem Vorwärmofen 3,
3. c) als Begasung des Industrieofens,
4. d) als Einstellung des ersten Brenners 3.1 als Schutzgasbrenner für den Vorwärmofen 3,
5. e) als Start des ersten Brenners 3.1,
6. f) als Betrieb des ersten Brenners 3.1,
7. g) als Abschalten des ersten Brenners 3.1,
8. h) als Ausfall des ersten Brenners 3.1
9. i) als Anliegen eines zu geringen Druckes vor dem ersten Brenner 3.1 beim Betrieb desselben

mit den Bezugsziffern der beteiligten Bezugszeichen bezeichnet.In the out Fig. 2 These are obvious processes with

1. a) as gas start and burner start,
2. b) as a gas type and burner start in the preheating furnace 3,
3. c) as fumigation of the industrial furnace,
4. d) as a setting of the first burner 3.1 as a protective gas burner for the preheating furnace 3,
5. e) as the start of the first burner 3.1,
6. f) as the operation of the first burner 3.1,
7. g) as switching off the first burner 3.1,
8. h) as a failure of the first burner 3.1
9. i) as a concern of too low pressure before the first burner 3.1 during operation of the same

denoted by the reference numerals of the participating reference numerals.

With the according to Fig. 1 a program is presented to automatically run the method according to the invention by means of the control and regulating unit 8.

• der Gasstart und Brennerstart im Hochtemperaturofen 2 mittels der dritten Steuereinrichtung 2.7 zur Einspeisung von Heizgas über die Zuleitung 4 sichergestellt ist, wobei zunächst der Gasstart an der ersten Steuereinrichtung 3.1.1 der Gaseingangsstrecke ausgelöst wird, wonach über die zweite Steuereinrichtung 3.2.1 eine automatische Startroutine mit einer Dichtigkeitskontrolle in der Zuleitung 4 abläuft, danach die Zufuhr von Heizgas freigegeben wird und zunächst der zweite Brenner 3.2 und der dritte Brenner 4 mittels Heizgas startfähig gesteuert werden,
• beim Gasstart und Brennerstart im Vorwärmofen 3 mittels der zweiten Steuereinrichtung 3.2.1 zunächst die Türen 2.1, 2.2, 3.5, 3.6 geschlossen werden und der Industrieofen 1 über die Zuleitung für Luft 6 für besagte Brenner 3.1,3.2, 3.3 mit einem mehrfachen Ofenvolumen an Luft gespült wird, sodann an der Zuleitung für Heizgas 4 eine Dichtigkeitskontrolle mittels der Dichtigkeitskontrolleinheit 4.1 durchgeführt wird, danach die die Türen 2.1, 2.2, 3.5, 3.6 geöffnet sowie der zweite Brenner 3.2 und der dritte Brenner 3.3 gestartet werden, nach einer Flammenüberwachung des zweiten Brenners 3.2 die Türen 2.1, 2.2, 3.5, 3.6 geschlossen werden, der Vorwärmofen 3 durch den zweiten Brenner 3.2 auf eine Betriebstemperatur gefahren wird und der dritte Brenner 3.3 so lange brennend betrieben wird, bis der Vorwärmofen 3 wieder abgeschaltet wird,
• die Einspeisung von Schutzgas in den mit einer Temperatur von > 750°C aufgeheizten Hochtemperaturofen 2 mittels der dritten Steuereinrichtung 2.7 erfolgt, wobei das Hauptventil 5.1 der Zuleitung für Schutzgas 5 für den ersten Brenner 3.1 geschlossen und das Absperrventil 2.5.1 der Abbrandstelle 2.5 geöffnet ist, der Abgasbrenner 2.4 der Abbrandstelle 2.5 bereits vor dem Start des Begasungssystems gestartet wurde und die Begasung des Industrieofens 1 abgeschlossen wird, wenn ein über die Überdruckklappe 2.8 der Abbrandstelle 2.5 eingestellter Überdruck erreicht ist und sich gleichzeitig ein angestrebter C-Pegel im Ofen eingestellt hat, und dann das Schutzgas für den Betrieb des ersten Brenners 3.1 verwendet wird und
• die Einstellung des ersten Brenners 3.1 als Schutzgasbrenner für den Vorwärmofen 3 zu einer derartigen Regelung seiner Leistung führt, dass die zur Verfügung stehende Menge an Schutzgas zunächst bei einer Erstinbetriebnahme des Industrieofens 1 nach Feststellung
  • ■ der Abbrände an der Abbrandstelle 2.5 oder
  • ■ eines Ausströmvolumens von Schutzgas oder
  • ■ über eine Gewichtsbelastung einer Rückschlagklappe
    oder der Überdruckklappe 2.8 der Abbrandstelle 2.5 der Ofendruck eingestellt wird, wobei nach diesen Einstellungen und der kontinuierlichen Begasung des Industrieofens 1 mit Schutzgas der den ersten Brenner 3.1 versorgende Volumenstrom an Schutzgas festgestellt wird und somit nur so viel Schutzgas verbrannt wird, wie bisher, d.h. ohne die erfinderischen Maßnahmen, aus der Abbrandstelle 2.5 ausströmte, wobei als Regelgröße für den ersten Brenner 3.1 der Ofendruck des Durchstoßofens verwendet wird.

Thus, the program with the above-indicated procedures ensures the functions integrated according to the invention that

• the gas type and burner start is ensured in the high-temperature furnace 2 by means of the third control device 2.7 for feeding fuel gas via the supply line 4, wherein first the gas type is triggered at the first control device 3.1.1 of the gas inlet line, after which via the second control device 3.2.1 an automatic start routine runs with a tightness control in the supply line 4, then the supply of fuel gas is released and first the second burner 3.2 and the third burner 4 are controlled startable by means of fuel gas,
• in the gas type and burner start in the preheating furnace 3 by means of the second control device 3.2.1 first the doors 2.1, 2.2, 3.5, 3.6 are closed and the industrial furnace 1 via the air supply 6 for said burner 3.1,3.2, 3.3 with a multiple furnace volume of air is flushed, then on the supply line for fuel gas 4 a tightness control is carried out by means of the tightness control unit 4.1, then the doors 2.1, 2.2, 3.5, 3.6 opened and the second burner 3.2 and the third burner 3.3 are started, after a flame monitoring of the second burner 3.2 the doors 2.1, 2.2, 3.5, 3.6 are closed, the preheating furnace 3 is driven by the second burner 3.2 to an operating temperature and the third burner 3.3 is operated so long burning until the preheating furnace 3 is switched off again,
• the supply of inert gas in the heated with a temperature of> 750 ° C high-temperature furnace 2 by means of the third control device 2.7, wherein the main valve 5.1 of the supply line for inert gas 5 for the first burner 3.1 closed and the shut-off valve 2.5.1 the burn-off point 2.5 is opened the combustor 2.4 of the burnup point 2.5 was already started before the start of the aeration system and the fumigation of the industrial furnace 1 is completed when an overpressure set via the pressure flap 2.8 of the burn-off point 2.5 is reached and at the same time a target C-level has been set in the furnace, and then the shielding gas is used for the operation of the first burner 3.1 and
• the setting of the first burner 3.1 as a protective gas burner for the preheating furnace 3 to such a regulation of its performance leads to the Available amount of inert gas initially at a first commissioning of the industrial furnace 1 after detection
  • ■ the burns at the burn-off point 2.5 or
  • ■ an outflow volume of inert gas or
  • ■ over a weight load on a non-return valve
    or the pressure flap 2.8 of Abbrandstelle 2.5 the furnace pressure is set, which is determined by these settings and the continuous gassing of the industrial furnace 1 with inert gas of the first burner 3.1 supplying flow of inert gas and thus only as much inert gas is burned, as before, ie without the inventive measures, from the burn-off point 2.5 flowed out, being used as a controlled variable for the first burner 3.1, the furnace pressure of the pusher furnace.

Furthermore, the program ensures that to perform the leak check before the main valve 5.1 of the supply line for shielding gas 5, a form by means of the blower 7 is set, which acts against the closed main valve 5.1, wherein the burn-off 2.5 is opened during the tightness control and the first burner 3.1 1 no protective gas is supplied.

1. a) ein Abschalten des ersten Brenners 3.1, wenn seine Versorgung mit Schutzgas nicht gewährleistet ist, wobei dann der Vorwärmofen 3 über den zweiten Brenner 3.2, vorrangig während der Öffnungszeit der Türen 2.1, beheizt wird und bei geöffneten Türen 2.1, 2.2, 3.5, 3.6 der erste Brenner 3.1 nur dann betrieben wird, wenn der Ofendruck einen vorgegebenen Sollwert erreicht hat, oder
2. b) ein Schließen des Hauptventils 5.1, wenn der erste Brenner 3.1 aufgrund einer Störung ausfällt oder nicht startfähig ist, wobei das Gebläse 7 ausgeschaltet, das Absperrventil 2.5.1 geöffnet ist und der zweite Brenner 3.2 den Vorwärmofen 3 beheizt, oder
3. c) eine Erhöhung der Drehzahl des Gebläses 7 über den Frequenzumformer 7.1, wenn vor dem ersten Brenner 3.1 ein zu geringer Druck anliegt, wobei als Regelgröße für den Frequenzumformer 7.1 der Vordruck vor dem ersten Brenner 3.1 verwendet und als Zielgröße ein Vordruck vorrangig ein Bereich von 20-30 mbar gehalten wird.

In addition, the program realized

1. a) switching off the first burner 3.1, if its supply of inert gas is not guaranteed, in which case the preheating furnace 3 via the second burner 3.2, primarily during the opening time of the doors 2.1, is heated and open doors 2.1, 2.2, 3.5, 3.6 the first burner 3.1 is operated only when the furnace pressure has reached a predetermined setpoint, or
2. b) closing the main valve 5.1 if the first burner 3.1 fails due to a malfunction or is not bootable, the Fan 7 is turned off, the shut-off valve 2.5.1 is open and the second burner 3.2 heats the preheating furnace 3, or
3. c) an increase in the rotational speed of the blower 7 via the frequency converter 7.1, if applied too low pressure before the first burner 3.1, where used as a controlled variable for the frequency converter 7.1, the form upstream of the first burner 3.1 and as a target form a form primarily a range of 20-30 mbar is maintained.

Industrial Applicability

With the invention resulting in industrial furnaces protective gases, which have so far drained without further use, used as a heating gas, which significantly improves the utility of industrial furnaces and their efficient and environmentally friendly use for the operating industry.

LIST OF REFERENCE NUMBERS

1

= Industrieofen

2

= Hochtemperaturofen

2.1

= Tür zur Beladung

2.2

= Tür zur Entladung

2.3

= Abgasbrenner

2.4

= Abbrandstelle

2.5.1

= Absperrventil

2.5

= Gaskühleinrichtung

2.6

= dritte Steuereinrichtung

2.7

= Überdruckklappe

3

= Vorwärmofen

3.1

= erster Brenner

3.1.1

= erste Steuereinrichtung

3.2

= zweiter Brenner

3.2.1

= zweite Steuereinrichtung

3.3

= dritter Brenner

3.4

= UV-Sonde

3.5

= Tür zur Beladung

3.6

= Tür zur Entladung

4

= Zuleitung für Heizgas

4.1 1

= Dichtigkeitskontrolleinheit

5

= Zuleitung für Schutzgas

5.1

= Hauptventil

6

= Zuleitung für Luft

6.1

= Luftregelklappe, Drosselklappe

7

= Gebläse

7.1

= Frequenzumformer

8

= Steuer-und Regeleinheit

Fig. 1 and Fig. 2

1

= Industrial furnace

2

= High temperature oven

2.1

= Door for loading

2.2

= Door for unloading

2.3

= Exhaust gas burner

2.4

= Burning point

2.5.1

= Shut-off valve

2.5

= Gas cooling device

2.6

= third control device

2.7

= Overpressure flap

3

= Preheating furnace

3.1

= first burner

3.1.1

= first control device

3.2

= second burner

3.2.1

= second control device

3.3

= third burner

3.4

= UV probe

3.5

= Door for loading

3.6

= Door for unloading

4

= Supply line for heating gas

4.1 1

= Leakage control unit

5

= Supply line for inert gas

5.1

= Main valve

6

= Supply line for air

6.1

= Air damper, throttle

7

= Blower

7.1

= Frequency converter

8th

= Control unit

Fig. 2

1. a) gas start and burner start,
2. b) gas start and burner start in the preheating furnace 3,
3. c) fumigation of the industrial furnace,
4. d) setting of the first burner 3.1 as a protective gas burner for the preheating furnace 3,
5. e) start of the first burner 3.1,
6. f) operation of the first burner 3.1,
7. g) switching off the first burner 3.1,
8. h) failure of the first burner 3.1,
9. i) Concerns of low pressure before the first burner 3.1

Claims (17)

Method for using a combustible shielding gas as heating gas for a first burner (3.1) in an industrial furnace (1) operated by means of heating gas and combustible protective gas for the heat treatment of materials, a second burner (3.2) used as a fuel gas burner and at least one burn-off point (2.5) wherein the first burner (3.1) is operated in preference to the second burner (1.2) for heating the industrial furnace (1), the second burner (3.2) is then switched on and operated when one for reaching a temperature setpoint of the industrial furnace ( 1) required power of the first burner (3.1) is exceeded, and the second burner (3.2) then turned off and not operated when the temperature set point is reached. A method according to claim 1, characterized in that a supplied with fuel gas, as a safety ignition burner for the first burner (3.1) operated third burner (3.3) is used. A method according to claim 1 or 2, characterized in that for monitoring the first burner (3.1), a UV probe (3.4) is used. Method according to one of claims 1 to 3, characterized in that the combustible shielding gas is supplied to the first burner (3.1) by means of a frequency-controlled blower (7). Method according to one of claims 1 to 4, characterized in that when the temperature rises above a setpoint temperature, the power of the first burner (3.1) is reduced by using an air control flap (6.1) as a throttle in a supply line (6) for air , Method according to one of claims 1 to 5, characterized in that with an increase in pressure in the industrial furnace (1) correspondingly more combustible protective gas via the Abbrandstelle (2.5, 2.6) of the industrial furnace (1) dissipated, the first burner (3.1) at a the maximum pressure is switched off, the burn-off point (2.5) is opened at an inlet lock and the pressure is reduced, wherein the first burner (3.1) is turned on again when there is a need for power in the industrial furnace (1). Method according to one of Claims 1 to 6 for the industrial furnace (1) designed as a push-through furnace installation, comprising a high-temperature furnace (2) with doors (2.1, 2.2) operated with combustible protective gas and a preheating furnace / pre-oxidation furnace with doors (3.5, 3.6), characterized by the sequence of the following steps: a) gas type and burner start in the high-temperature furnace (2) by means of a control and regulating unit 8 for feeding fuel gas via a supply line for fuel gas (4), wherein first the gas type is triggered at a first control device (3.1.1) a gas inlet path, after which over a second control device (3.2.1) runs an automatic start routine with a tightness control in the supply line (4), then the supply of fuel gas is released and first the second burner (3.2) and the third burner (3.3) are controlled startable by means of fuel gas, so that a supply of heating gas is ensured b) Gas type and burner start in Vorwärmofen / Voroxidationsofen (3) by means of the second control device (3.2.1), in which the automatic start routine runs, first the doors (2.1, 2.2) are closed and the preheating / pre-oxidation (3) via a supply line for air (6) for said burners (3.1, 3.2, 3.3) is purged with a multiple furnace volume with air, then at the supply line for fuel gas (4) a tightness control is carried out by means of a tightness control unit (4.1), then the doors (2.1, 2.2) is opened and the second burner (3.2) and the third burner (3.3) are started, after a flame monitoring of the second burner (3.2) the doors (2.1, 2.2, 3.5, 3.6) are closed, the preheating / pre-oxidation (3) is driven by the second burner (3.2) to an operating temperature and the third burner (3.3) is operated so long burning until the preheating / pre-oxidation furnace (3) is switched off again, c) feeding of combustible inert gas in the heated high-temperature furnace (2) by means of a control and regulating unit (8), wherein a main valve (5.1) of the supply line for combustible protective gas (5) for the first burner (3.1) closed and a shut-off valve (2.5 .1) the Abbrandstelle (2.5) is opened, an exhaust gas burner (2.4) of Abbrandstelle (2.5) was already started before the start of the aeration system and the fumigation of the high temperature furnace (2) is completed when a via a pressure relief flap (2.8) of the Abbrandstelle (2.5) set pressure state is reached and at the same time set a desired atmosphere in the oven, and then the combustible shielding gas for the operation of the first burner (3.1) is used, and d) adjustment of the first burner (3.1) as a protective gas burner for the preheating / pre-oxidation (3) by such a regulation of its performance that the available amount of combustible inert gas initially at a first commissioning of the industrial furnace (1) after detection i. the burnings at the burn-off point (2.5) or ii. an outflow volume of combustible inert gas or iii. via a weight load of a check valve or the overpressure flap (2.8) of the burn-off point (2.5) the furnace pressure is set, whereby after these settings and the continuous gassing of the high temperature furnace (2) with combustible inert gas of the first burner (3.1) supplying volumetric flow of combustible inert gas is detected and thus only as much inert gas is burned, as hitherto from the erosion point ( 2.5) was discharged, being used as a controlled variable for the first burner (3.1), the furnace pressure of the high-temperature furnace. Method according to one of claims 1 to 7, characterized in that for carrying out the tightness control before the main valve (5.1) of the supply line for combustible protective gas (5), a pre-pressure by means of the blower (7) is set, which acts against the closed main valve (5.1), wherein the Abbrandstelle (2.5) is opened during the tightness control and the first burner (3.1) is still no combustible inert gas is supplied. Method according to one of claims 1 to 8, characterized by at least one of the processes, such as ■ a shutdown of the first burner (3.1), if its supply of combustible inert gas is not guaranteed, in which case the preheating / Voroxidationsofen (3) via the second burner (3.2), primarily during the opening time of the doors (2.1, 2.2), heated is and with the doors open (2.1, 2.2), the first burner (3.1) is operated only when the furnace pressure has reached a predetermined setpoint, or ■ closing the main valve (5.1) if the first burner (3.1) fails or is not able to start due to a fault, the blower (7) is switched off, the shut - off valve (2.5.1) is open and the second burner (3.2) opens Preheating furnace / pre-oxidation furnace (3) heated, or ■ An increase in the speed of the fan (7) via a frequency converter (7.1), if before the first burner (3.1) is applied too low a pressure, as a controlled variable for the frequency converter (7.1), the pre-pressure before the first burner (3.1) used and, as a target, a pre-pressure is given priority to a range of 20-30 mbar. Method according to one of claims 1 to 9, characterized by the use of a program for operating the industrial furnace (1) for controlling and regulating at least one of the steps or one of the conditions a) Gas start and burner start in a high-temperature furnace (2), b) gas start and burner start in an associated preheating / pre-oxidation furnace (3), c) fumigation of the high-temperature furnace, d) setting a first burner (3.1) as protective gas burner for the preheating / pre-oxidation furnace (3), e) start of the first burner (3.1) as protective gas burner, f) operation of the first burner (3.1), g) switching off the first burner (3.1), h) failure of the first burner (3.1), i) too little pressure in front of the first burner (3.1) during operation. Industrial furnace (1) for carrying out the method according to one of Claims 1 to 9, having a first burner (3.1) operated in front of a second burner (3.2) for heating the preheating furnace / pre-oxidation furnace (3), the second burner (3.2) then being switched on is when a to reach a temperature setpoint of the industrial furnace (1) required power of the first burner (3.1) is exceeded, and the second burner (3.2) is then switched off when the temperature setpoint is reached. Industrial furnace (1) according to claim 11 with a third burner (3.3) which can be operated as a safety ignition burner, at least one burn-off point (2.5), a frequency-controlled blower (7) and an air control flap (6.2) as a throttle valve for an air supply. Industrial furnace (1) according to claim 11 or 12, characterized by a UV sensor (3.4) monitoring the first burner (3.1). An industrial furnace (1) according to any one of claims 11 to 13, which is designed as a pusher-type furnace system of an operated with combustible protective gas high temperature furnace (2) with doors (2.1, 2.2) and a pre-heating / Voroxidationsofen (3) with doors (3.5, 3.6), characterized by a control unit (8), the a) a first control device (3.1.1) for a gas type at a gas inlet line and b) a second control device (3.2.1) for an automatic start routine with a tightness control in a feed line (4) for the heating gas and a gas start and burner start in the preheating / pre-oxidation furnace (3), includes. Industrial furnace (1) according to one of claims 11 to 14, characterized by a) a tightness control unit (4.1) for a tightness control and b) a main valve (5.1) and a shut-off valve (2.5.1) in the supply line for flammable inert gas (5). Industrial furnace (1) according to one of Claims 11 to 15, characterized by a gas cooling device (2.6) protecting against overheating of the combustible protective gas. Industrial furnace (1) according to one of Claims 11 to 16, characterized by a control and regulating unit (8) for controlling and integrating the first control device (3.1.1), second control device (3.2.1) and third control device (3.2.1) Control of furnace operation.

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