DE102019006940A1 - Device for delaying metal dusting at the cold-warm transitions in heat treatment systems which are operated with carbon-containing atmospheres in the process interior. - Google Patents

Abstract

According to the state of the art, the superfluous and / or used gas atmosphere is brought out of the treatment room (interior of item 2) by means of a flare (item 5), which is usually tubular and is located directly below or above the fan baffle (item 9 ) (if present) has its inlet opening for the gas to be discharged. The inlet opening is in the warm area (here for example 950 ° C during the carbonization process). The gas atmosphere, which is located in the narrow space between the retort (item 2) and the cover shoulder (item 4) when the lid (item 3) is closed and during the heat treatment, loses depending on the distance from the production area (here 950 ° C) towards the underside of the lid (item 3) at temperature (this area of the treatment room "interior of item 2" is not heated). The temperature of the gas atmosphere passes through the temperature range of 630 ° C to 600 ° C, the closer the gas atmosphere is The closer the gas atmosphere, viewed from the production area, is to the uninsulated underside of the lid (item 3), the lower the atmospheric upheavals or movements in this area. The carbon remaining in the gas atmosphere, which has not diffused into the metal products, precipitates as soot in the cold-warm transition area (on the neck area of the inner retort wall "Item 2.1" and the cover bevel "Item 4.1"). The gas atmosphere, which is hardly in motion in this treatment room area (interior of item 2) and the unfavorable temperature of the gas atmosphere in this treatment room area (interior of item 2), promotes soot formation and promotes the soot precipitation area (Fig. 2: item 2). In order to counteract the massive formation of soot and prevent the formation of metal dusting, the gas atmosphere must pass through the critical temperature range (here 600 ° C to 630 ° C) as quickly as possible To achieve this, the gas atmosphere must leave the treatment room (interior of item 2) from this area as quickly as possible.

Description

The invention belongs to the technical field of "high temperature corrosion".

State of the art:

To illustrate, the "state of the art" is described using a shaft furnace from the field of heat treatment.

Shaft furnaces are used, among other things, to introduce carbon into the surface area of metal products (here, for example, gears of a transmission) in order to make them wear-resistant through subsequent hardening / quenching.

In order to be able to guarantee this wear-resistant condition, the metal products are exposed to a carbon-containing gas atmosphere when they are warm.

• Einem Gehäuse (Pos.1), einer Retorte (Pos.2) und einem Deckel (Pos.3). Im Gehäuse (Pos.1) integriert befindet sich in der Regel eine Isolierung, ein Heizsystem und eine Retorte in deren Innenraum die Metallerzeugnisse für die Wärmebehandlung positioniert werden können.
• Der zum Gehäuse zählende Boden ist in der Regel ebenfalls isoliert. Die Retorte (Pos.2) besteht aus einer temperaturbeständigen Legierung und wird während der Prozesse thermisch beansprucht.
• Der Deckel, (Pos.3) welcher in den meisten Fällen die Retorte unter Zuhilfenahme des Gehäuses (Pos.1) verschließen kann, taucht mit seinem Boden („Anschäftung (Pos.4)“ bestehend aus einer temperaturbeständigen Legierung), in die Retorte (Pos.2) ein und wird während der Prozesse thermisch beansprucht.
• Die Anschäffung (Pos.4) des Deckels (Pos.3) ist von innen isoliert (gemäß Pos.11). Sie wird von mehreren Rohren (Pos.5 und Pos.8) durchdrungen, welche ebenfalls aus temperaturbeständigen Legierungen bestehen.

At the prevailing high process temperatures (here for example 950 ° C), the carbon contained in the gas atmosphere diffuses into the metal products. A shaft furnace basically consists of the following components:

• A housing (item 1), a retort (item 2) and a cover (item 3). In the housing (item 1) there is usually an insulation, a heating system and a retort in the interior of which the metal products for the heat treatment can be positioned.
• The floor belonging to the housing is usually also insulated. The retort (item 2) consists of a temperature-resistant alloy and is thermally stressed during the processes.
• The lid (item 3), which in most cases can close the retort with the aid of the housing (item 1), dips into the retort with its base ("attachment (item 4)" made of a temperature-resistant alloy) (Item 2) and is thermally stressed during the processes.
• The bevel (item 4) of the cover (item 3) is insulated from the inside (according to item 11). It is penetrated by several pipes (item 5 and item 8), which are also made of temperature-resistant alloys.

• Einbringung der Atmosphäre (technische Gase) in den Retorteninnenraum (Pos.2), Positionierung von Sonden für verschiedene Messaufgaben, Folienlöcher, Probenlöcher und der Abfacklung (Pos.5) über die die verbrauchte Atmosphäre aus der Retorte (Pos.2) ausgebracht wird und so zur Zündflamme / Zündvorrichtung (Pos.6 und Pos.7) Zwecks Verbrennung gelangt.

The penetrations serve the following purposes:

• Introduction of the atmosphere (technical gases) into the retort interior (item 2), positioning of probes for various measuring tasks, foil holes, sample holes and the flare (item 5) through which the used atmosphere is discharged from the retort (item 2) and this way to the pilot flame / ignition device (items 6 and 7) for combustion.

Deficiencies in the state of the art: In the case of the thermally loaded components of a shaft furnace system, metal dusting occurs in the hot-cold transition area of the treatment interior (here the retort neck (item 2.1) and the cover bevel (item 4.1).

Metalusting destroys the sheet metal in the affected area to such an extent that the material thickness of the sheet metal area concerned decreases.

This process leads to breakthroughs (holes, cracks, etc.) in the sheet concerned.

If “breakthroughs” have occurred in the retort (item 2) as a result of metalusting, the furnace atmosphere can enter the boiler room.

If the furnace system is electrically heated, the carbon in the furnace atmosphere diffuses into the heating elements and destroys them.

If the retort (item 2) is heated with gas burners, the exhaust gases from the burners (with corresponding pressure differences) enter the retort interior (item 2) through the opening and cause damage to the metal products. If the damage caused by metalusting has resulted in “breakthroughs” in the abutment (item 4), the carbon in the furnace atmosphere diffuses into the insulation (according to item 11) of the furnace lid (item 3).

In unfavorable circumstances, deflagrations or explosions can occur. The heat treatment process for the metal products can also be controlled more poorly, since changes in temperature in the treatment room (interior of item 2) can lead to undesirable feedback from the media. Process gases and soot that were previously able to penetrate the inside of the lid (item 3) through a "breakthrough" can return to the treatment room (inside of item 2) due to changes in the process temperatures and falsify the measurement results or the actual treatment status.

• Das Metaldusting so weit zu verzögern oder zu verringern, dass die thermisch beanspruchten Bauteile des Behandlungsinnenraumes „hier Retorte (Pos.2) und Deckel Anschaffung (Pos.4)“ im Kalt-Warmübergang weniger durch Metaldusting verschleißen und somit eine längere Standzeit aufweisen.

My problem:

• To delay or reduce the metal dusting to such an extent that the thermally stressed components of the treatment interior "here retort (item 2) and cover purchase (item 4)" wear less in the cold-warm transition due to metal dusting and thus have a longer service life.

Solution: Relocation of the inlet opening of the flare line (s) (item 5) for the used or excess production gases, which are led to the pilot flame for combustion, out of the temperature range of the heat treatment processes, and into the space between the neck area of the retort inner wall and the cover bevel into it.

(This position is marked in the drawing "Fig.2" with "Pos.5.1")

• Nach dem Stand der Technik wird die überflüssige und oder verbrauchte Gasatmosphäre, mittels einer Abfacklung (Pos.5) aus dem Behandlungsraum (Innenraum von Pos.2) gebracht. Die Abfackelung ist im Regelfall rohrförmig ausgeführt und direkt unter oder über dem Lüfterleitblech (Pos.9) (falls vorhanden) befindet sich die Eintrittsöffnung für das auszubringende Gas. Die Eintrittsöffnung liegt im Warmbereich (hier zum Beispiel 950°C beim Kohlungsprozess). Die Gasatmosphäre, welche sich im schmalen Zwischenraum zwischen Retorte (Pos.2) und Deckel-Anschäftung (Pos.4) bei geschlossenem Deckel (Pos.3) und während der Wärmebehandlung befindet, verliert je nach Abstand vom Produktionsbereich (hier zum Beispiel 950°C) in Richtung zur Deckelunterseite (Pos.3) an Temperatur (dieser Bereich der Retorte (Pos.2) ist nicht beheizt).

Description of the function with reference symbols (pos.) To the drawing:

• According to the state of the art, the superfluous and / or used gas atmosphere is removed from the treatment room (interior of item 2) by means of a flare (item 5). The flaring is usually tubular and the inlet opening for the gas to be discharged is located directly below or above the fan baffle (item 9) (if present). The inlet opening is in the warm area (here for example 950 ° C during the carbonization process). The gas atmosphere, which is located in the narrow space between the retort (item 2) and the cover shoulder (item 4) when the lid (item 3) is closed and during the heat treatment, loses depending on the distance from the production area (here for example 950 ° C) in the direction of the underside of the lid (item 3) in terms of temperature (this area of the retort (item 2) is not heated).

The temperature of the gas atmosphere passes through the temperature range from 630 ° C to 600 ° C, the closer the gas atmosphere is to the non-insulated underside of the cover (item 3).

The closer the gas atmosphere is from the production area (treatment room and interior from item 2) to the non-insulated underside of the lid (item 3), the lower the atmospheric upheavals or movements in this area. The carbon remaining in the gas atmosphere, which has not diffused into the metal products, falls in the cold-warm transition area (on the neck area of the inner wall of the retort (item 2.1) and the cover bevel (item 4.1) at a temperature of around 600 ° C to 630 ° C) as soot.

The gas atmosphere, which is hardly in motion in this area of the treatment room (space between items 2.1 and 4.1), and the unfavorable temperatures of the gas atmosphere in this area of the treatment room (space between items 2.1 and 4.1), promote the formation of soot and promote soot in the soot. Precipitation area ( 2 : Item 2.1 and Item 4.1) the occurrence of metalusting.

In order to counteract the massive soot formation and to prevent the formation of metal dusting, the gas atmosphere must pass through the critical temperature range (here 600 ° C to 630 ° C) as quickly as possible.

In order to achieve this, the gas atmosphere must leave this treatment room area (interior area of item 2) as quickly as possible.

• Durch die im oberen Teil beschriebenen Maßnahme, wird die Häufigkeit, der durch Metaldusting verursachten Reparaturintervalle reduziert. Die Produktivität der Anlage wird erhöht und die Reparaturkosten werden gesenkt.

Advantages of the invention:

• The measures described in the above section reduce the frequency of the repair intervals caused by metal dusting. The productivity of the system is increased and the repair costs are reduced.

References to sources

• DE000003012338C2
• DE102008020449A1
• W0002005052197A1

Bibliography

• "HIGH TEMPERATURE CORRUSION"
• University of Siegen
• Faculty IV - Department of Mechanical Engineering
• Institute for Materials Technology
• Chair of Materials Science and Testing Prof. Dr.-Ing. H.-J.Christ
• Priv.Doz.Dr.-Ing.habil. Bronislava Gorr 04/03/2018

Figure list

• 1 Item 1 = housing with base Item 2 = retort Item 3 = cover Item 4 = shoulder Item 5 = flaring Item 6 = pilot flame Item 7 = ignition device Item 8 = sample, probes or foil Item 9 = fan baffle Item 10 = fan Item 11 = insulation Item 12 = heating elements
• 2 Item 2 = retort Item 2.1 = retort with metal dusting Item 3 = cover Item 4 = bevel Item 4.1 = bevel with metal dusting Item 5.1 = new position of the flare system Item 6 = pilot flame Item 7 = ignition device Item 11 = Insulation pos. 12 = heating coils

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 000003012338 C2 [0022]
• DE 102008020449 A1 [0022]
• WO 002005052197 A1 [0022]

Claims (1)

A device for delaying metal dusting on thermally stressed system components of heat treatment systems, which are located in the process interior of the heat treatment system and are in contact with warm carbon-containing technical production gases of the respective heat treatment itself, characterized in that the positioning of at least one inlet opening on at least one flaring line for Excess and / or used technical gases from a heat treatment process in which the area of the heat treatment system is or are positioned in which metal dusting occurs.

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