EP3933335A1 - Indirectly heatable rotary kiln with internal coating of nickel-based alloy and use of an indirectly heatable rotary kiln - Google Patents

Indirectly heatable rotary kiln with internal coating of nickel-based alloy and use of an indirectly heatable rotary kiln Download PDF

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Publication number
EP3933335A1
EP3933335A1 EP20183853.9A EP20183853A EP3933335A1 EP 3933335 A1 EP3933335 A1 EP 3933335A1 EP 20183853 A EP20183853 A EP 20183853A EP 3933335 A1 EP3933335 A1 EP 3933335A1
Authority
EP
European Patent Office
Prior art keywords
rotary kiln
nickel
rotary
based alloy
rotary tube
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP20183853.9A
Other languages
German (de)
French (fr)
Inventor
Andreas Hajduk
Franziskus KÜSPERT
Andreas OVERHOFF
Matthias Uhl
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Riedhammer GmbH
Riedhammer GmbH and Co KG
Original Assignee
Riedhammer GmbH
Riedhammer GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Riedhammer GmbH, Riedhammer GmbH and Co KG filed Critical Riedhammer GmbH
Priority to EP20183853.9A priority Critical patent/EP3933335A1/en
Priority to US17/366,336 priority patent/US20220003499A1/en
Priority to JP2021110721A priority patent/JP7266641B2/en
Priority to KR1020210087517A priority patent/KR102623736B1/en
Publication of EP3933335A1 publication Critical patent/EP3933335A1/en
Pending legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/28—Arrangements of linings
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • C22C19/03—Alloys based on nickel or cobalt based on nickel
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/06—Metallic material
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
    • C23C4/06—Metallic material
    • C23C4/08—Metallic material containing only metal elements
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C23C4/129—Flame spraying
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
    • C23C4/12—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the method of spraying
    • C23C4/131—Wire arc spraying
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/08—Rotary-drum furnaces, i.e. horizontal or slightly inclined externally heated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/12—Rotary-drum furnaces, i.e. horizontal or slightly inclined tiltable
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories, or equipment peculiar to rotary-drum furnaces
    • F27B7/34—Arrangements of heating devices
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/0003—Linings or walls
    • F27D1/0006—Linings or walls formed from bricks or layers with a particular composition or specific characteristics
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D1/00—Casings; Linings; Walls; Roofs
    • F27D1/16—Making or repairing linings increasing the durability of linings or breaking away linings
    • F27D1/1678—Increasing the durability of linings; Means for protecting
    • F27D1/1684—Increasing the durability of linings; Means for protecting by a special coating applied to the lining

Definitions

  • the invention relates to an indirectly heatable rotary kiln, the use of a nickel-based alloy and the use of an indirectly heatable rotary kiln.
  • An indirectly heatable rotary kiln is a specific type of rotary kiln.
  • a rotary tube furnace comprises a cylindrical rotary tube, which is mounted rotatably about its longitudinal axis with its longitudinal axis slightly inclined to the horizontal.
  • the rotary kiln is heated and rotated around its longitudinal axis.
  • material to be burned is introduced into the rotary kiln. Due to the inclination of the rotary kiln and its rotary movement, the material to be fired either automatically moves continuously from the higher to the lower end of the rotary kiln.
  • this movement can also be supported or brought about by corresponding fixtures in the rotary tube, for example spirals will.
  • the items to be fired are subjected to heat for the desired duration and temperature.
  • the duration of the passage of the material through the rotary kiln can be influenced by the inclination of the longitudinal axis, the length of the rotary kiln, the speed of rotation and - if available - the built-in components. While the material to be fired passes through the rotary kiln, a firing temperature of the desired level can be applied to it.
  • the rotary kiln is indirectly heated to act on the material to be fired in the rotary kiln.
  • the rotary kiln is heated from the outside.
  • the rotary tube can be heated from the outside by means of burners, for example gas burners, or electrical heaters. It is possible to heat the rotary kiln to temperatures well over 1,000 ° C.
  • the devices for heating the rotary tube for example a burner or an electrical heater, are usually arranged in an insulated housing which surrounds the rotary tube.
  • the kiln During the passage of the fuel through the rotary kiln, the kiln is exposed to temperature, in particular through contact with the hot inside surface of the rotary kiln and the thermal radiation emitted from the inside surface of the rotary kiln, and is thus thermally treated.
  • Indirectly heated rotary kilns are used in particular for the thermal treatment of bulk materials, for example granulates, powders or nanopowders.
  • a particular advantage of the thermal treatment of bulk materials in indirectly heated rotary kilns is that they pass through a very precisely defined temperature profile in the indirectly heated rotary kiln and can be treated under special process conditions, such as under an inert or protective gas atmosphere.
  • indirectly heated rotary kilns have proven useful for the thermal treatment of items to be fired, in particular also the bulk goods mentioned above.
  • the invention is based on the object of providing an indirectly heatable rotary kiln which can be used for the thermal treatment of a very wide range of items to be fired, in particular a wider range of items to be fired than those known from the prior art that can be indirectly heated Rotary kilns is possible.
  • the invention is based on the object of providing an indirectly heatable rotary kiln which can also be used for the thermal treatment of high-quality, particularly high-purity products that do not contaminate or only to a very small extent during the thermal treatment in the rotary kiln may, in particular not or only to a very small extent, may be contaminated by components of the indirectly heatable rotary kiln of the indirectly heatable rotary kiln.
  • the rotary tube of the indirectly heatable rotary tube furnace has a coating in the form of a nickel-based alloy on its inside.
  • the invention is based in particular on the knowledge according to the invention that it is technically not possible to provide an indirectly heatable rotary kiln which, on the one hand, has such a temperature resistance as well as a static and dynamic load capacity that it can withstand the thermal and physical loads, which a rotary kiln in an indirectly heated rotary kiln is subject to, and on the other hand also has such a mechanical strength, in particular abrasion resistance, and chemical or corrosive resistance that contamination of the fuel by components of the material of the rotary kiln can be prevented. Rather, the inventors have recognized that the objects according to the invention can only be achieved if the rotary tube is made of different materials.
  • the rotary tube is made of a material that is coated on the inside with another material, namely according to the invention a material in the form of a nickel-based alloy.
  • an indirectly heatable rotary tube of an indirectly heatable rotary kiln can be coated on the inside with a nickel-based alloy in an excellent manner.
  • a nickel-based alloy can provide a material which has excellent properties from the point of view of the mechanical and chemical strength described above.
  • a material can be made available which, when in contact with high-quality, high-purity products during their thermal treatment in the rotary kiln, emits practically no components by which the products could be contaminated.
  • nickel-based alloys have, in addition to good mechanical resistance (in particular also good abrasion resistance) and corrosion resistance, in particular excellent high temperature resistance (creep resistance), so that they are also suitable for use at high temperatures in an indirectly heatable rotary kiln, in particular, for example, for temperatures above 1,000 ° C, are suitable.
  • a nickel-based alloy is provided which is suitable for use temperatures above 1,000 ° C, in particular for use temperatures above 1,100 ° C.
  • the composition of the nickel-based alloy is possible in a very broad spectrum in order to meet the required requirements.
  • the nickel-based alloy can be in the form of one of the following nickel-based alloys: nickel-aluminum alloys, nickel-molybdenum alloys, nickel-tungsten carbide alloys or low-alloy nickel alloys.
  • the nickel-based alloy can comprise a proportion of nickel (Ni) in the range from 30 to 99.5%, more preferably in the range from 60-99.5% and particularly preferably in the range from 60-90%.
  • All information given here in% is information in% by mass and based on the total mass of the nickel-based alloy.
  • the proportions of the alloy components of the nickel-based alloy in% also indicate the chemical composition of the nickel-based alloy.
  • the nickel-based alloy comprises at least one of the following components in addition to nickel: Al (aluminum), Mo (molybdenum), WC (tungsten carbide), copper (Cu), titanium (Ti) or chromium (Cr).
  • the nickel-based alloy has a total proportion of Al, Mo, WC, Cu, Ti and Cr in the range of 0.5-70%, more preferably in the range of 0.5-40% and particularly preferably in the range of 10 - 40% included.
  • the nickel-based alloy comprises the above-mentioned proportions of nickel.
  • the nickel-based alloy comprises a proportion of A1 in the range from 0.5-20.0% and Ni in the range from 80.0-99.5%.
  • the nickel-based alloy comprises a proportion of Mo in the range from 0.5-20.0% and Ni in the range from 80.0-99.5%.
  • the nickel-based alloy comprises a proportion of WC in the range from 0.5-60.0% and Ni in the range from 40.0-99.5%.
  • the nickel-based alloy can in principle comprise one or more of the further known alloy components for nickel-based alloys.
  • the coating has a thickness in the range from 0.1 mm to 1.5 mm. According to the invention has It has been shown that if the coating is less than 0.1 mm thick, there is a risk that the material to be fired will come into contact with areas of the rotary kiln during the firing process, which could contaminate the material to be fired. It has also been found that if the coating is thicker than 1.5 mm, thermal stresses can occur in the coating, which can damage the coating. More preferably, the coating has a thickness in the range from 0.2 to 1.0 mm, even more preferably in the range from 0.4 to 0.8 mm and even more preferably in the range from 0.5 to 0.6 mm.
  • the indirectly heatable rotary tube can in principle be coated on the inside with the nickel-based alloy according to the invention using all of the technologies known from the prior art.
  • the coating can preferably be applied to the inside of the indirectly heatable rotary kiln by at least one of the following processes: thermal spraying or baking.
  • thermal spraying is a technology in which the material that will later form the coating, in the present case a nickel-based alloy, is first melted and then sprayed in a gas stream onto the surface to be coated, in the present case the inside of the rotary tube will.
  • the nickel-based alloy is applied to the inside of the rotary tube by means of flame spraying, more preferably by means of wire flame spraying.
  • the material to be coated As is known, during baking, the material to be coated, according to the invention a nickel-based alloy, is first applied in powder form or as an emulsion to the surface to be coated, in the present case the inside of the rotary tube, and then baked in under an inert atmosphere.
  • the coating made of a nickel-based alloy forms the inside of the rotating barrel.
  • the coating made of a nickel-based alloy thus forms the surface of the rotary kiln, with which the material to be thermally treated in the rotary kiln comes into contact as it passes through the rotary kiln.
  • the indirectly heatable rotary tube is in the form of a metallic rotary tube.
  • an indirectly heatable metallic rotary tube and a coating made of a nickel-based alloy can be optimally matched to one another in such a way that the rotary tube has an optimal temperature resistance and static and dynamic load capacity and, at the same time, thanks to the coating made of a nickel-based alloy on its inside, optimal mechanical strength (especially abrasion resistance) and chemical resistance.
  • a particular advantage of a metallic rotary tube lies in the fact that the properties, in particular the physical properties of the rotary tube and the coating, can be optimally matched to one another.
  • the thermal expansion behavior of a metallic rotary tube and the coating made of a nickel-based alloy can be optimally matched to one another and, in particular, can be adjusted to one another.
  • this also has the advantage that thermal stresses can be avoided during the firing process, which could arise in the event of a different thermal expansion behavior of the rotary kiln and the coating.
  • a preferred embodiment also provides that the difference in the coefficient of linear expansion between the rotary tube and the coating made of a nickel-based alloy is ⁇ 2.0, more preferably ⁇ 1.5 and even more preferably ⁇ 1.0.
  • the coefficient of linear expansion is the coefficient of linear expansion ⁇ at 20 ° C with ⁇ in 10 -6 ⁇ K -1 .
  • the rotary tube furnace according to the invention has a rotary tube made of steel, particularly preferably made of a heat-resistant steel.
  • a high-temperature steel is present, in particular a high-temperature steel which can be loaded, in particular dynamically, at temperatures above 600 ° C., or also above 1,000 ° C. and particularly preferably also above 1,200 ° C.
  • the rotary tube furnace according to the invention has a rotary tube made of a heat-resistant steel, in particular a highly corrosion-resistant steel.
  • the rotary tube furnace according to the invention has a rotary tube made of one of the following steels: ferritic steel, nickel-alloyed steel, austenitic steel or steel made of a nickel-based material.
  • the rotary tube furnace very particularly preferably has a rotary tube made of an austenitic steel.
  • the aforementioned steels in particular austenitic steel, can be coated on the inside with a nickel-based alloy, while meeting the aforementioned requirements with regard to high temperature resistance and static and dynamic load-bearing capacity of the rotary tube as well as coordinated properties, in particular physical properties of the rotary tube and coating, able to fulfill.
  • the steel of the rotary tube is made of steel
  • the steel of the rotary tube and the nickel-based alloy are in different alloys.
  • the steel of the rotary tube is optimized in particular with regard to high temperature resistance and the static and dynamic load-bearing capacity of the rotary tube.
  • the nickel-based alloy is optimized not only for temperature resistance but also in particular with regard to its requirements for mechanical strength, in particular abrasion resistance, and chemical resistance, in particular corrosion resistance.
  • the rotary tube of the rotary kiln according to the invention can moreover be designed in accordance with the indirectly heatable rotary tubes of indirectly heatable rotary kilns known from the prior art.
  • the rotary tube preferably has an internal diameter in the range from 100 to 3,000 mm.
  • the rotary tube preferably has a length in the range from 1,000 to 50,000 mm.
  • the rotary kiln according to the invention can be designed in accordance with the prior art.
  • the rotary kiln can be indirectly heated according to the technologies known from the prior art.
  • the rotary kiln according to the invention can have heating devices by means of which the rotary kiln can be heated indirectly, that is to say from the outside.
  • These heating devices can in particular be burners, preferably gas burners, or electrical heating devices.
  • the rotary tube is heated to temperatures of over 150 ° C., in particular also to temperatures of over 600 ° C., according to a preferred embodiment to over 1,000 ° C., more preferably to temperatures in the range from 1,000 to 1,200 ° C.
  • temperatures in the range from 1,100 to 1,200.degree is indirectly heated.
  • the aforementioned temperatures relate to the inside of the rotary kiln, that is to say the area of the rotary kiln where the material to be thermally treated by the rotary kiln is located when it passes through the rotary kiln.
  • the aforementioned temperatures relate in particular to the inside of the rotary tube in the area of the inlet, that is to say the higher end of the rotary tube, at which the material to be burned in the rotary tube is introduced into the rotary tube.
  • the rotary tube can be mounted rotatably about its longitudinal axis with a longitudinal axis slightly inclined to the horizontal, for example by means of roller bearings. Furthermore, as is known from the prior art, the rotary tube can be installed in an insulated housing which surrounds the rotary tube, with the heating devices for the rotary tube also being able to be arranged in this housing.
  • the rotary kiln can use the devices known from the prior art for feeding the kiln into the kiln, for removing the kiln thermally treated in the kiln from the kiln, for gas-tight sealing of the kiln (for setting a desired furnace atmosphere) and for any cooling of the kiln include thermally treated items to be fired.
  • the invention also relates to the use of the rotary kiln according to the invention for the thermal treatment of items to be fired, in particular for the thermal treatment of items to be fired in the form of bulk goods, in particular in the form of bulk goods in the form of granules, powders or nanopowders.
  • the rotary kiln is used for the thermal treatment of high-quality, especially high-quality, high-purity items to be fired, in particular items to be fired in the form of the aforementioned bulk goods, in particular in the form of high-quality, high-purity items to be fired that must not be contaminated by the rotary kiln.
  • the invention also relates to the use of a nickel-based alloy for coating the inside of an indirectly heatable rotary tube of an indirectly heatable rotary tube furnace.
  • the use of the nickel-based alloy takes place with the proviso that the rotary tube is coated on the inside with the nickel-based alloy, in particular by the aforementioned method.
  • the nickel-based alloy, the rotary tube and the rotary tube furnace can have the inventive features of the rotary tube furnace according to the invention disclosed herein.
  • FIG. 1 the rotary kiln, identified in its entirety by the reference numeral 1, of an indirectly heatable rotary kiln, not shown in detail, is shown.
  • the rotary tube 1 has an essentially tubular shape with a longitudinal axis L.
  • the rotary kiln 1 is mounted rotatably about its longitudinal axis L with a slight inclination of the longitudinal axis L to the horizontal H.
  • the rotary tube 1 is supported by roller bearings, not shown, on which the rotary tube 1 is rotatably supported on a substrate at its one, here higher end 2 and at its second, opposite, here lower end 3.
  • the rotary tube 1 consists of an austenitic steel tube 4 which has a coating of a nickel-based alloy 5 on the inside.
  • the rotary tube 1 has a length (along the longitudinal axis L) of 2,500 mm and a clear diameter (perpendicular to the longitudinal axis L) of 186 mm.
  • the nickel-based alloy 5 has the following chemical composition: Ni: 90 mass% Al: 10 mass%
  • the coating 5 has a thickness of 0.5 mm.
  • the difference in the linear expansion coefficient ⁇ (at 20 ° with ⁇ in 10 -6 K -1 ) of the austenitic steel 4 and the nickel-based alloy 5 is less than 1.0.
  • the nickel-based alloy 5 was applied to the inside of the austenitic steel 4 of the rotary tube 1 by means of wire flame spraying.
  • the rotary tube 1 can be heated indirectly from the outside via an electrical heater (not shown in detail).
  • the rotary kiln 1 is heated indirectly from the outside via the electrical heater.
  • the rotary kiln 1 material to be thermally treated is introduced into the rotary kiln 1 in the area of the upper end 2 via a device not shown in detail.
  • the rotary tube 1 is rotated about its longitudinal axis L via drive means (not shown in detail).
  • the rotary kiln 1 is heated by the heating devices and this heat is transferred to the material to be fired in the rotary kiln 1.
  • the material to be fired moves about its longitudinal axis L in the direction of the lower end 3 of the rotating tube 1.
  • the material to be fired is thermally treated in the rotating tube 1.
  • the material to be fired is removed from the rotary kiln 1 using devices not shown in detail.
  • the rotary kiln 1 is particularly suitable for the thermal treatment of material to be fired in the form of high-quality, high-purity products, in particular in the form of bulk goods, which must not be contaminated by the rotary kiln 1.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Coating By Spraying Or Casting (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)

Abstract

Die Erfindung betrifft einen indirekt beheizbaren Drehrohrofen, die Verwendung einer Nickelbasislegierung sowie die Verwendung eines indirekt beheizbaren Drehrohrofens.The invention relates to an indirectly heatable rotary kiln, the use of a nickel-based alloy and the use of an indirectly heatable rotary kiln.

Description

Die Erfindung betrifft einen indirekt beheizbaren Drehrohrofen, die Verwendung einer Nickelbasislegierung sowie die Verwendung eines indirekt beheizbaren Drehrohrofens.The invention relates to an indirectly heatable rotary kiln, the use of a nickel-based alloy and the use of an indirectly heatable rotary kiln.

Bei einem indirekt beheizbaren Drehrohrofen handelt es sich um eine bestimmte Bauart eines Drehrohrofens. Wie aus dem Stand der Technik bekannt, umfasst ein Drehrohrofen ein zylindrisches Drehrohr, das mit seiner leicht zur Horizontalen geneigten Längsachse drehbar um seine Längsachse gelagert ist. Beim Betrieb des Drehrohrofens wird das Drehrohr beheizt und um seine Längsachse gedreht. Am höher gelegenen Ende des Drehrohrs wird zu brennendes Gut in das Drehrohr eingegeben. Durch die Neigung des Drehrohrs und dessen Drehbewegung bewegt sich das Brenngut entweder selbsttätig kontinuierlich vom höher gelegenen zum niedriger gelegenen Ende des Drehrohrs. Alternativ kann diese Bewegung auch durch entsprechende Einbauten im Drehrohr, beispielsweise Spiralen, unterstützt oder bewirkt werden. Während dieses Durchgangs des Brennguts durch das Drehrohr wird das Brenngut für die gewünschte Dauer und Temperatur mit Hitze beaufschlagt. Die Dauer des Durchgangs des Brennguts durch das Drehrohr kann durch die Neigung der Längsachse, die Länge des Drehrohrs, die Rotationsgeschwindigkeit und - soweit vorhanden - die Einbauten beeinflusst werden. Während des Durchgangs des Brennguts durch das Drehrohr kann dieses mit einer Brenntemperatur in der gewünschten Höhe beaufschlagt werden.An indirectly heatable rotary kiln is a specific type of rotary kiln. As is known from the prior art, a rotary tube furnace comprises a cylindrical rotary tube, which is mounted rotatably about its longitudinal axis with its longitudinal axis slightly inclined to the horizontal. When the rotary kiln is in operation, the rotary kiln is heated and rotated around its longitudinal axis. At the higher end of the rotary kiln, material to be burned is introduced into the rotary kiln. Due to the inclination of the rotary kiln and its rotary movement, the material to be fired either automatically moves continuously from the higher to the lower end of the rotary kiln. Alternatively, this movement can also be supported or brought about by corresponding fixtures in the rotary tube, for example spirals will. During this passage of the items through the rotary kiln, the items to be fired are subjected to heat for the desired duration and temperature. The duration of the passage of the material through the rotary kiln can be influenced by the inclination of the longitudinal axis, the length of the rotary kiln, the speed of rotation and - if available - the built-in components. While the material to be fired passes through the rotary kiln, a firing temperature of the desired level can be applied to it.

Bei indirekt beheizten Drehrohröfen wird das Drehrohr zur Beaufschlagung des Brenngutes im Drehrohr indirekt beheizt. Hierzu wird das Drehrohr von außen beheizt. Beispielsweise kann das Drehrohr zur indirekten Beheizbarkeit insoweit mittels Brennern, beispielsweise Gasbrennern, oder elektrischen Heizungen von außen beheizt werden. Dabei ist es möglich, das Drehrohr auf Temperaturen bis weit über 1.000°C zu beheizen. Die Vorrichtungen zur Beheizung des Drehrohrs, also beispielsweise Brenner oder eine elektrische Heizung, sind üblicherweise in einem isolierten Gehäuse angeordnet, das das Drehrohr umgibt. Während des Durchgangs des Brennguts durch das Drehrohr wird das Brenngut dabei insbesondere durch Kontakt mit der heißen, innenseitigen Oberfläche des Drehrohres sowie durch die von der innenseitigen Oberfläche des Drehrohres abgestrahlten Wärmestrahlung mit Temperatur beaufschlagt und hierdurch thermisch behandelt.In the case of indirectly heated rotary kilns, the rotary kiln is indirectly heated to act on the material to be fired in the rotary kiln. For this purpose, the rotary kiln is heated from the outside. For example, for indirect heating, the rotary tube can be heated from the outside by means of burners, for example gas burners, or electrical heaters. It is possible to heat the rotary kiln to temperatures well over 1,000 ° C. The devices for heating the rotary tube, for example a burner or an electrical heater, are usually arranged in an insulated housing which surrounds the rotary tube. During the passage of the fuel through the rotary kiln, the kiln is exposed to temperature, in particular through contact with the hot inside surface of the rotary kiln and the thermal radiation emitted from the inside surface of the rotary kiln, and is thus thermally treated.

Indirekt beheizte Drehrohröfen werden insbesondere für die thermische Behandlung von Schüttgütern, beispielsweise Granulaten, Pulvern oder Nanopulvern eingesetzt. Vorteilhaft an der thermischen Behandlung von Schüttgütern in indirekt beheizten Drehrohröfen ist insbesondere, dass diese im indirekt beheizbaren Drehrohr ein sehr genau definiertes Temperaturprofil durchlaufen und unter besonderen Prozessbedingungen behandelt werden können, wie beispielsweise unter Inert- oder Schutzgasatmosphäre.Indirectly heated rotary kilns are used in particular for the thermal treatment of bulk materials, for example granulates, powders or nanopowders. A particular advantage of the thermal treatment of bulk materials in indirectly heated rotary kilns is that they pass through a very precisely defined temperature profile in the indirectly heated rotary kiln and can be treated under special process conditions, such as under an inert or protective gas atmosphere.

Grundsätzlich haben sich indirekt beheizte Drehrohröfen zur thermischen Behandlung von Brenngut, insbesondere auch den vorbezeichneten Schüttgütern bewährt.In principle, indirectly heated rotary kilns have proven useful for the thermal treatment of items to be fired, in particular also the bulk goods mentioned above.

Allerdings besteht insbesondere für hochwertige, hochreine Brenngüter oder Brenngüter, welche chemisch aggressive Bestandteile beinhalten die Gefahr, dass auf Grund von mechanischem Abrieb durch das Brenngut im Drehrohr während des Brennprozesses oder durch chemische Reaktionen des Brenngutes mit dem Drehrohr das Brenngut mit Bestandteilen des Drehrohres verunreinigt werden kann. Dieser Effekt kann bei unterschiedlichen Anwendungen durch die jeweils notwendige Ofenatmosphäre, beispielsweise eine hoch sauerstoffhaltige Ofenatmosphäre, noch verstärkt werden. Da solche Verunreinigungen für eine Vielzahl von Produkten nicht akzeptierbar ist, kommt die Verwendung eines indirekt beheizten Drehrohrofens für die thermische Behandlung von zahlreichen Brenngütern bislang nicht in Frage.However, especially for high-quality, high-purity items to be fired or items that contain chemically aggressive constituents, there is a risk that the items to be fired will be contaminated with components of the barrel due to mechanical abrasion caused by the items to be fired in the rotary kiln during the firing process or by chemical reactions of the items to be fired with the rotary kiln can. In the case of different applications, this effect can be intensified by the furnace atmosphere required in each case, for example a furnace atmosphere with a high content of oxygen. Since such impurities are unacceptable for a large number of products, the use of an indirectly heated rotary kiln for the thermal treatment of numerous kilns has not yet been considered.

Es hat in der Vergangenheit nicht an Versuchen gefehlt, einen indirekt beheizbaren Drehrohrofen zur Verfügung zu stellen, der ein indirekt beheizbares Drehrohr aus einem Material umfasst, durch welches die vorbezeichnete Verunreinigung von Brenngut, insbesondere also von Brenngut in Form von hochwertigen, hochreinen Produkten, vermieden wird. Unter dem Gesichtspunkt der notwendigen Temperaturbeständigkeit sowie statischen und dynamischen Belastbarkeit des Materials des Drehrohrs sind der möglichen Auswahl des Materials des Drehrohrs insoweit jedoch Grenzen gesetzt. Dies hat zur Folge, dass auch bei einer möglichen Anpassung des Materials des Drehrohrs eines indirekt beheizbaren Drehrohrofens an die Anforderungen des Brennguts die Verwendung eines indirekt beheizbaren Drehrohrofens für bestimmte Brenngüter bislang nicht in Frage kam.There has been no lack of attempts in the past to provide an indirectly heatable rotary kiln which comprises an indirectly heatable rotary kiln made of a material that avoids the aforementioned contamination of items to be fired, in particular items to be fired in the form of high-quality, high-purity products will. From the point of view of the necessary temperature resistance and the static and dynamic loading capacity of the material of the rotary tube, however, there are limits to the possible selection of the material of the rotary tube. As a result, even with a possible adaptation of the material of the rotary kiln of an indirectly heatable rotary kiln to the requirements of the material to be burned, the use of an indirectly heatable rotary kiln for certain objects to be burned was previously out of the question.

Der Erfindung liegt die Aufgabe zugrunde, einen indirekt beheizbaren Drehrohrofen zur Verfügung zu stellen, der für die thermische Behandlung eines sehr breiten Spektrums von Brenngut verwendet werden kann, insbesondere eines breiteren Spektrums von Brenngut, als dies mit den aus dem Stand der Technik bekannten indirekt beheizbaren Drehrohröfen möglich ist. Insbesondere liegt der Erfindung insoweit die Aufgabe zugrunde, einen indirekt beheizbaren Drehrohrofen zur Verfügung zu stellen, der auch für die thermische Behandlung von hochwertigen, insbesondere hochreinen Produkten verwendet werden kann, die während der thermischen Behandlung im Drehrohrofen nicht oder nur in einem sehr geringen Umfang verunreinigt werden dürfen, insbesondere nicht oder nur in einem sehr geringen Umfang durch Bestandteile des indirekt beheizbaren Drehrohrs des indirekt beheizbaren Drehrohrofens verunreinigt werden dürfen.The invention is based on the object of providing an indirectly heatable rotary kiln which can be used for the thermal treatment of a very wide range of items to be fired, in particular a wider range of items to be fired than those known from the prior art that can be indirectly heated Rotary kilns is possible. In particular, the invention is based on the object of providing an indirectly heatable rotary kiln which can also be used for the thermal treatment of high-quality, particularly high-purity products that do not contaminate or only to a very small extent during the thermal treatment in the rotary kiln may, in particular not or only to a very small extent, may be contaminated by components of the indirectly heatable rotary kiln of the indirectly heatable rotary kiln.

Zur Lösung dieser Aufgabe wird erfindungsgemäß zur Verfügung gestellt ein indirekt beheizbarer Drehrohrofen, der die folgenden Merkmale umfasst:

  • Ein indirekt beheizbares Drehrohr;
  • das Drehrohr weist innenseitig eine Beschichtung aus einer Nickelbasislegierung auf.
To solve this problem, an indirectly heatable rotary kiln is provided according to the invention, which includes the following features:
  • An indirectly heated rotary kiln;
  • the inside of the rotary tube has a coating made of a nickel-based alloy.

Überraschend hat sich erfindungsgemäß herausgestellt, dass die vorbezeichneten Aufgaben dadurch gelöst werden können, dass das Drehrohr des indirekt beheizbaren Drehrohrofens auf seiner Innenseite eine Beschichtung in Form einer Nickelbasislegierung aufweist.According to the invention, it has surprisingly been found that the aforementioned objects can be achieved in that the rotary tube of the indirectly heatable rotary tube furnace has a coating in the form of a nickel-based alloy on its inside.

Die Erfindung beruht insbesondere auf der erfindungsgemäßen Erkenntnis, dass es technisch nicht möglich ist, ein indirekt beheizbares Drehrohr zur Verfügung zu stellen, das gleichzeitig zum einen eine solche Temperaturbeständigkeit sowie statische und dynamische Belastbarkeit aufweist, dass es den thermischen und physikalischen Belastungen standhält, denen ein Drehrohr in einem indirekt beheizten Drehrohrofen unterworfen ist, als auch zum anderen ferner eine solch mechanische Festigkeit, insbesondere Abriebfestigkeit, und chemische beziehungsweise korrosive Beständigkeit aufweist, dass eine Verunreinigung des Brennguts durch Bestandteile des Materials des Drehrohres verhindert werden kann. Vielmehr haben die Erfinder erkannt, dass die erfindungsgemäßen Aufgaben nur dann gelöst werden können, wenn das Drehrohr aus unterschiedlichen Materialien besteht. Erfindungsgemäß besteht das Drehrohr insoweit aus einem Material, das innenseitig mit einem anderen Material, nämlich erfindungsgemäß einem Material in Form einer Nickelbasislegierung, beschichtet ist. Dies ermöglicht es, das Material des Drehrohrs spezifisch hinsichtlich der geforderten Temperaturbeständigkeit sowie statischen und dynamischen Belastbarkeit zu optimieren, während das Beschichtungsmaterial neben einer Temperaturbeständigkeit auch spezifisch hinsichtlich seiner Anforderungen an eine mechanische Festigkeit, insbesondere Abriebfestigkeit, sowie chemische Beständigkeit, insbesondere Korrosionsbeständigkeit, optimiert werden kann.The invention is based in particular on the knowledge according to the invention that it is technically not possible to provide an indirectly heatable rotary kiln which, on the one hand, has such a temperature resistance as well as a static and dynamic load capacity that it can withstand the thermal and physical loads, which a rotary kiln in an indirectly heated rotary kiln is subject to, and on the other hand also has such a mechanical strength, in particular abrasion resistance, and chemical or corrosive resistance that contamination of the fuel by components of the material of the rotary kiln can be prevented. Rather, the inventors have recognized that the objects according to the invention can only be achieved if the rotary tube is made of different materials. According to the invention, the rotary tube is made of a material that is coated on the inside with another material, namely according to the invention a material in the form of a nickel-based alloy. This makes it possible to optimize the material of the rotary kiln specifically with regard to the required temperature resistance as well as static and dynamic load capacity, while the coating material, in addition to temperature resistance, can also be specifically optimized with regard to its requirements for mechanical strength, in particular abrasion resistance, and chemical resistance, in particular corrosion resistance .

Erfindungsgemäß wurde überraschend erkannt, dass ein indirekt beheizbares Drehrohr eines indirekt beheizbaren Drehrohrofens zum einen hervorragend innenseitig durch eine Nickelbasislegierung beschichtet werden kann. Zum anderen wurde erfindungsgemäß erkannt, dass durch eine solche Nickelbasislegierung ein Material zur Verfügung gestellt werden kann, das unter dem Gesichtspunkt der vorbezeichneten mechanischen und chemischen Festigkeit hervorragende Eigenschaften aufweist. Insbesondere kann auf Basis einer solchen Nickelbasislegierung ein Material zur Verfügung gestellt werden, welches bei Kontakt mit hochwertigen, hochreinen Produkten während deren thermischer Behandlung im Drehrohr praktisch keine Bestandteile abgibt, durch welche die Produkte verunreinigt werden könnten.According to the invention, it was surprisingly recognized that an indirectly heatable rotary tube of an indirectly heatable rotary kiln can be coated on the inside with a nickel-based alloy in an excellent manner. On the other hand, it was recognized according to the invention that such a nickel-based alloy can provide a material which has excellent properties from the point of view of the mechanical and chemical strength described above. In particular, on the basis of such a nickel-based alloy, a material can be made available which, when in contact with high-quality, high-purity products during their thermal treatment in the rotary kiln, emits practically no components by which the products could be contaminated.

Ferner weisen Nickelbasislegierungen neben einer guten mechanischen Beständigkeit (insbesondere auch einer guten Abriebfestigkeit) und Korrosionsbeständigkeit insbesondere auch eine hervorragende Hochtemperaturbeständigkeit (Kriechfestigkeit) auf, so dass sie auch für einen Einsatz bei hohen Temperaturen in einem indirekt beheizbaren Drehrohr, insbesondere beispielsweise auch für Temperaturen über 1.000°C, geeignet sind.Furthermore, nickel-based alloys have, in addition to good mechanical resistance (in particular also good abrasion resistance) and corrosion resistance, in particular excellent high temperature resistance (creep resistance), so that they are also suitable for use at high temperatures in an indirectly heatable rotary kiln, in particular, for example, for temperatures above 1,000 ° C, are suitable.

Nach einer bevorzugten Ausführungsform ist eine Nickelbasislegierung vorgesehen, die für Einsatztemperaturen über 1.000°C geeignet ist, insbesondere für Einsatztemperaturen über 1.100°C.According to a preferred embodiment, a nickel-based alloy is provided which is suitable for use temperatures above 1,000 ° C, in particular for use temperatures above 1,100 ° C.

Erfindungsgemäß hat sich herausgestellt, dass die Zusammensetzung der Nickelbasislegierung in einem sehr breiten Spektrum möglich ist, um die geforderten Anforderungen zu erfüllen.According to the invention it has been found that the composition of the nickel-based alloy is possible in a very broad spectrum in order to meet the required requirements.

Nach einer bevorzugten Ausführungsform kann die Nickelbasislegierung in Form einer der folgenden Nickelbasislegierungen vorliegen: Nickel-Aluminium-Legierungen, Nickel-Molybdän-Legierungen, Nickel-Wolframcarbid-Legierungen oder niedriglegierte Nickellegierungen.According to a preferred embodiment, the nickel-based alloy can be in the form of one of the following nickel-based alloys: nickel-aluminum alloys, nickel-molybdenum alloys, nickel-tungsten carbide alloys or low-alloy nickel alloys.

Die Nickelbasislegierung kann einen Anteil an Nickel (Ni) im Bereich von 30 bis 99,5 %, weiter bevorzugt im Bereich von 60 - 99,5 % und besonders bevorzugt im Bereich von 60 - 90 % umfassen.The nickel-based alloy can comprise a proportion of nickel (Ni) in the range from 30 to 99.5%, more preferably in the range from 60-99.5% and particularly preferably in the range from 60-90%.

Alle hierin gemachten Angaben in % sind Angaben in Masse-% und bezogen auf die Gesamtmasse der Nickelbasislegierung. Die Anteile der Legierungsbestandteile der Nickelbasislegierung in % geben ferner die chemische Zusammensetzung der Nickelbasislegierung an.All information given here in% is information in% by mass and based on the total mass of the nickel-based alloy. The proportions of the alloy components of the nickel-based alloy in% also indicate the chemical composition of the nickel-based alloy.

Nach einer Ausführungsform ist vorgesehen, dass die Nickelbasislegierung neben Nickel wenigstens einen der folgenden Bestandteile umfasst: Al (Aluminium), Mo (Molybdän), WC (Wolframcarbid), Kupfer (Cu), Titan (Ti) oder Chrom (Cr).According to one embodiment it is provided that the nickel-based alloy comprises at least one of the following components in addition to nickel: Al (aluminum), Mo (molybdenum), WC (tungsten carbide), copper (Cu), titanium (Ti) or chromium (Cr).

Nach einer Ausführungsform ist vorgesehen, dass die Nickelbasislegierung einen Gesamtanteil an Al, Mo, WC, Cu, Ti und Cr im Bereich von 0,5 - 70 %, weiter bevorzugt im Bereich von 0,5 - 40 % und besonders bevorzugt im Bereich von 10 - 40 % umfasst. Gleichzeitig kann bevorzugt vorgesehen sein, dass die Nickelbasislegierung die oben bezeichneten Anteile an Nickel umfasst.According to one embodiment it is provided that the nickel-based alloy has a total proportion of Al, Mo, WC, Cu, Ti and Cr in the range of 0.5-70%, more preferably in the range of 0.5-40% and particularly preferably in the range of 10 - 40% included. At the same time, it can preferably be provided that the nickel-based alloy comprises the above-mentioned proportions of nickel.

Nach einer Ausführungsform ist vorgesehen, dass die Nickelbasislegierung einen Anteil an A1 im Bereich von 0,5 - 20,0 % und Ni im Bereich von 80,0 - 99,5 % umfasst.According to one embodiment it is provided that the nickel-based alloy comprises a proportion of A1 in the range from 0.5-20.0% and Ni in the range from 80.0-99.5%.

Nach einer Ausführungsform ist vorgesehen, dass die Nickelbasislegierung einen Anteil an Mo im Bereich von 0,5 - 20,0 % und Ni im Bereich von 80,0 - 99,5 % umfasst.According to one embodiment it is provided that the nickel-based alloy comprises a proportion of Mo in the range from 0.5-20.0% and Ni in the range from 80.0-99.5%.

Nach einer Ausführungsform ist vorgesehen, dass die Nickelbasislegierung einen Anteil an WC im Bereich von 0,5 - 60,0 % und Ni im Bereich von 40,0 - 99,5 % umfasst.According to one embodiment it is provided that the nickel-based alloy comprises a proportion of WC in the range from 0.5-60.0% and Ni in the range from 40.0-99.5%.

Über die vorbezeichneten Legierungsbestandteile hinaus kann die Nickelbasislegierung grundsätzlich einen oder mehrere der weiteren bekannten Legierungsbestandteile für Nickelbasislegierungen umfassen.In addition to the aforementioned alloy components, the nickel-based alloy can in principle comprise one or more of the further known alloy components for nickel-based alloys.

Erfindungsgemäß ist bevorzugt vorgesehen, dass die Beschichtung eine Dicke im Bereich von 0,1 mm bis 1,5 mm aufweist. Erfindungsgemäß hat sich herausgestellt, dass bei einer Dicke der Beschichtung unter 0,1 mm die Gefahr besteht, dass das Brenngut während des Brennprozesses im Drehrohrofen in Kontakt mit Bereichen des Drehrohres tritt, wodurch das Brenngut verunreinigt werden könnte. Ferner hat sich herausgestellt, dass bei einer Dicke der Beschichtung über 1,5 mm thermische Spannungen in der Beschichtung auftreten können, die zu einer Beschädigung der Beschichtung führen können. Weiter bevorzugt weist die Beschichtung eine Dicke im Bereich von 0,2 bis 1,0 mm, noch bevorzugter im Bereich von 0,4 bis 0,8 mm und noch bevorzugter im Bereich von 0,5 bis 0,6 mm auf.According to the invention it is preferably provided that the coating has a thickness in the range from 0.1 mm to 1.5 mm. According to the invention has It has been shown that if the coating is less than 0.1 mm thick, there is a risk that the material to be fired will come into contact with areas of the rotary kiln during the firing process, which could contaminate the material to be fired. It has also been found that if the coating is thicker than 1.5 mm, thermal stresses can occur in the coating, which can damage the coating. More preferably, the coating has a thickness in the range from 0.2 to 1.0 mm, even more preferably in the range from 0.4 to 0.8 mm and even more preferably in the range from 0.5 to 0.6 mm.

Das indirekt beheizbare Drehrohr kann grundsätzlich durch sämtliche der aus dem Stand der Technik bekannten Technologien innenseitig mit der erfindungsgemäßen Nickelbasislegierung beschichtet werden. Bevorzugt kann die Beschichtung insoweit durch wenigstens eines der folgenden Verfahren auf die Innenseite des indirekt beheizbaren Drehrohrs aufgetragen sein: Thermisches Spritzen oder Einbrennen. Bekanntermaßen handelt es sich bei thermischem Spritzen um eine Technologie, bei der der die spätere Beschichtung bildende Werkstoff, im vorliegenden Fall also eine Nickelbasislegierung, zunächst aufgeschmolzen und anschließend in einem Gasstrom auf die zu beschichtende Oberfläche, im vorliegenden Fall also die Innenseite des Drehrohrs, aufgespritzt wird. Nach einer bevorzugten Ausführungsform des thermischen Spritzens wird die Nickelbasislegierung mittels Flammspritzen, noch bevorzugter mittels Drahtflammspritzen auf die Innenseite des Drehrohres aufgetragen.The indirectly heatable rotary tube can in principle be coated on the inside with the nickel-based alloy according to the invention using all of the technologies known from the prior art. In this respect, the coating can preferably be applied to the inside of the indirectly heatable rotary kiln by at least one of the following processes: thermal spraying or baking. As is known, thermal spraying is a technology in which the material that will later form the coating, in the present case a nickel-based alloy, is first melted and then sprayed in a gas stream onto the surface to be coated, in the present case the inside of the rotary tube will. According to a preferred embodiment of thermal spraying, the nickel-based alloy is applied to the inside of the rotary tube by means of flame spraying, more preferably by means of wire flame spraying.

Bekanntermaßen wird beim Einbrennen der zu beschichtende Werkstoff, erfindungsgemäß also eine Nickelbasislegierung, zunächst pulverförmig oder als Emulsion auf die zu beschichtende Oberfläche, im vorliegenden Fall also die Innenseite des Drehrohrs, aufgebracht und anschließend unter inerter Atmosphäre eingebrannt.As is known, during baking, the material to be coated, according to the invention a nickel-based alloy, is first applied in powder form or as an emulsion to the surface to be coated, in the present case the inside of the rotary tube, and then baked in under an inert atmosphere.

Die Beschichtung aus einer Nickelbasislegierung bildet die Innenseite des Drehrohrs. Damit bildet die Beschichtung aus einer Nickelbasislegierung die Oberfläche des Drehrohrs, mit der das im Drehrohr thermisch zu behandelnde Brenngut beim Durchlauf durch das Drehrohr in Kontakt kommt.The coating made of a nickel-based alloy forms the inside of the rotating barrel. The coating made of a nickel-based alloy thus forms the surface of the rotary kiln, with which the material to be thermally treated in the rotary kiln comes into contact as it passes through the rotary kiln.

Nach einer besonders bevorzugten Ausführungsform liegt das indirekt beheizbare Drehrohr in Form eines metallischen Drehrohrs vor. Erfindungsgemäß hat sich herausgestellt, dass ein indirekt beheizbares metallisches Drehrohr und eine Beschichtung aus einer Nickelbasislegierung optimal derart aufeinander abgestimmt werden können, dass das Drehrohr eine optimale Temperaturbeständigkeit sowie statische und dynamische Belastbarkeit und gleichzeitig durch die Beschichtung aus einer Nickelbasislegierung auf seiner Innenseite eine optimale mechanische Festigkeit (insbesondere Abriebfestigkeit) und chemische Beständigkeit aufweist. Ein besonderer Vorteil eines metallischen Drehrohres liegt insbesondere auch darin, dass die Eigenschaften, insbesondere die physikalischen Eigenschaften des Drehrohres und der Beschichtung optimal aufeinander abgestimmt werden können. Insbesondere können das Wärmedehnungsverhalten eines metallischen Drehrohres und der Beschichtung aus einer Nickelbasislegierung optimal aufeinander abgestimmt werden und insbesondere einander angeglichen werden. Dies hat insbesondere auch den Vorteil, dass thermische Spannungen während des Brennprozesses, die bei einem unterschiedlichen Wärmedehnungsverhalten von Drehrohr und Beschichtung entstehen könnten, vermeiden werden können.According to a particularly preferred embodiment, the indirectly heatable rotary tube is in the form of a metallic rotary tube. According to the invention, it has been found that an indirectly heatable metallic rotary tube and a coating made of a nickel-based alloy can be optimally matched to one another in such a way that the rotary tube has an optimal temperature resistance and static and dynamic load capacity and, at the same time, thanks to the coating made of a nickel-based alloy on its inside, optimal mechanical strength (especially abrasion resistance) and chemical resistance. A particular advantage of a metallic rotary tube lies in the fact that the properties, in particular the physical properties of the rotary tube and the coating, can be optimally matched to one another. In particular, the thermal expansion behavior of a metallic rotary tube and the coating made of a nickel-based alloy can be optimally matched to one another and, in particular, can be adjusted to one another. In particular, this also has the advantage that thermal stresses can be avoided during the firing process, which could arise in the event of a different thermal expansion behavior of the rotary kiln and the coating.

Insoweit ist nach einer bevorzugten Ausführungsform auch vorgesehen, dass die Differenz des Längenausdehnungskoeffizienten zwischen dem Drehrohr und der Beschichtung aus einer Nickelbasislegierung < 2,0 beträgt, bevorzugter < 1,5 und noch bevorzugter < 1,0. Der Längenausdehnungskoeffizient ist der Längenausdehnungskoeffizient α bei 20°C mit α in 10-6 · K-1.In this respect, a preferred embodiment also provides that the difference in the coefficient of linear expansion between the rotary tube and the coating made of a nickel-based alloy is <2.0, more preferably <1.5 and even more preferably <1.0. the The coefficient of linear expansion is the coefficient of linear expansion α at 20 ° C with α in 10 -6 · K -1 .

Nach einer bevorzugten Ausführungsform weist der erfindungsgemäße Drehrohrofen ein Drehrohr aus Stahl, besonders bevorzugt aus einem warmfesten Stahl vor. Besonders bevorzugt liegt ein hochwarmfester Stahl vor, insbesondere ein hochwarmfester Stahl, der bei Temperaturen oberhalb 600°C, oder auch oberhalb 1.000°C und besonders bevorzugt auch oberhalb 1.200°C belastbar, insbesondere dynamisch belastbar ist.According to a preferred embodiment, the rotary tube furnace according to the invention has a rotary tube made of steel, particularly preferably made of a heat-resistant steel. Particularly preferably, a high-temperature steel is present, in particular a high-temperature steel which can be loaded, in particular dynamically, at temperatures above 600 ° C., or also above 1,000 ° C. and particularly preferably also above 1,200 ° C.

Nach einer bevorzugten Ausführungsform weist der erfindungsgemäße Drehrohrofen ein Drehrohr aus einem hitzebeständigen Stahl auf, insbesondere einem hochkorrosionsbeständigen Stahl.According to a preferred embodiment, the rotary tube furnace according to the invention has a rotary tube made of a heat-resistant steel, in particular a highly corrosion-resistant steel.

Nach einer bevorzugten Ausführungsform ist vorgesehen, dass der erfindungsgemäße Drehrohrofen ein Drehrohr aus einem der folgenden Stähle aufweist: Ferritischer Stahl, nickellegierter Stahl, austenitischer Stahl oder Stahl aus einem Nickelbasiswerkstoff. Ganz besonders bevorzugt weist der Drehrohrofen ein Drehrohr aus einem austenitischen Stahl auf.According to a preferred embodiment it is provided that the rotary tube furnace according to the invention has a rotary tube made of one of the following steels: ferritic steel, nickel-alloyed steel, austenitic steel or steel made of a nickel-based material. The rotary tube furnace very particularly preferably has a rotary tube made of an austenitic steel.

Erfindungsgemäß wurde festgestellt, dass die vorbezeichneten Stähle, insbesondere austenitischer Stahl, hervorragend mit einer Nickelbasislegierung innenseitig beschichtet werden können und dabei die vorbezeichneten Anforderungen hinsichtlich einer hohen Temperaturbeständigkeit sowie statischen und dynamischen Belastbarkeit des Drehrohres sowie aufeinander abgestimmter Eigenschaften, insbesondere physikalischer Eigenschaften von Drehrohr und Beschichtung, erfüllen können.According to the invention, it was found that the aforementioned steels, in particular austenitic steel, can be coated on the inside with a nickel-based alloy, while meeting the aforementioned requirements with regard to high temperature resistance and static and dynamic load-bearing capacity of the rotary tube as well as coordinated properties, in particular physical properties of the rotary tube and coating, able to fulfill.

Soweit das Drehrohr aus Stahl besteht, liegen der Stahl des Drehrohrs und die Nickelbasislegierung in unterschiedlichen Legierungen vor. Dabei ist der Stahl des Drehrohrs, wie oben ausgeführt, insbesondere hinsichtlich einer hohen Temperaturbeständigkeit sowie statischen und dynamischen Belastbarkeit des Drehrohres optimiert. Demgegenüber ist die Nickelbasislegierung, wie oben ausgeführt, neben einer Temperaturbeständigkeit auch insbesondere hinsichtlich ihrer Anforderungen an eine mechanische Festigkeit, insbesondere Abriebfestigkeit, sowie chemische Beständigkeit, insbesondere Korrosionsbeständigkeit, optimiert.If the rotary tube is made of steel, the steel of the rotary tube and the nickel-based alloy are in different alloys. As stated above, the steel of the rotary tube is optimized in particular with regard to high temperature resistance and the static and dynamic load-bearing capacity of the rotary tube. In contrast, as explained above, the nickel-based alloy is optimized not only for temperature resistance but also in particular with regard to its requirements for mechanical strength, in particular abrasion resistance, and chemical resistance, in particular corrosion resistance.

Das Drehrohr des erfindungsgemäßen Drehrohrofens kann im Übrigen gemäß den aus dem Stand der Technik bekannten, indirekt beheizbaren Drehrohren von indirekt beheizbaren Drehrohröfen gestaltet sein. Bevorzugt weist das Drehrohr einen Innendurchmesser im Bereich von 100 bis 3.000 mm auf. Ferner weist das Drehrohr bevorzugt eine Länge im Bereich von 1.000 bis 50.000 mm auf.The rotary tube of the rotary kiln according to the invention can moreover be designed in accordance with the indirectly heatable rotary tubes of indirectly heatable rotary kilns known from the prior art. The rotary tube preferably has an internal diameter in the range from 100 to 3,000 mm. Furthermore, the rotary tube preferably has a length in the range from 1,000 to 50,000 mm.

Über die vorbezeichneten, erfindungsgemäßen Merkmale hinaus kann der erfindungsgemäße Drehrohrofen gemäß dem Stand der Technik gestaltet sein. Insoweit kann das Drehrohr gemäß den aus dem Stand der Technik bekannten Technologien indirekt beheizbar sein. Insoweit kann der erfindungsgemäße Drehrohrofen Heizeinrichtungen aufweisen, über die das Drehrohr indirekt - also von außen - beheizbar ist. Bei diesen Heizeinrichtungen kann es sich insbesondere um Brenner, bevorzugt Gasbrenner, oder elektrische Heizeinrichtungen handeln. Bevorzugt kann vorgesehen sein, dass das Drehrohr über diese Heizeinrichtungen auf Temperaturen von über 150°C, insbesondere auch auf Temperaturen von über 600°C, nach einer bevorzugten Ausführungsform auf über 1.000°C, weiter bevorzugt auf Temperaturen im Bereich von 1.000 bis 1.200°C und nach einer besonders bevorzugten Ausführungsform auf Temperaturen im Bereich von 1.100 bis 1.200°C indirekt beheizbar ist. Die vorbezeichneten Temperaturen beziehen sich auf die Innenseite des Drehrohrs, also den Bereich des Drehrohrs, an dem sich das durch das Drehrohr thermisch zu behandelnde Brenngut beim Durchgang durch das Drehrohr befindet. Die vorbezeichneten Temperaturen beziehen sich insbesondere auf die Innenseite des Drehrohrs im Bereich des Einlaufs, also des höher gelegenen Endes des Drehrohres, an dem das im Drehrohr zu brennende Gut in das Drehrohr eingegeben wird.In addition to the aforementioned features according to the invention, the rotary kiln according to the invention can be designed in accordance with the prior art. In this respect, the rotary kiln can be indirectly heated according to the technologies known from the prior art. To this extent, the rotary kiln according to the invention can have heating devices by means of which the rotary kiln can be heated indirectly, that is to say from the outside. These heating devices can in particular be burners, preferably gas burners, or electrical heating devices. It can preferably be provided that the rotary tube is heated to temperatures of over 150 ° C., in particular also to temperatures of over 600 ° C., according to a preferred embodiment to over 1,000 ° C., more preferably to temperatures in the range from 1,000 to 1,200 ° C. and, according to a particularly preferred embodiment, to temperatures in the range from 1,100 to 1,200.degree is indirectly heated. The aforementioned temperatures relate to the inside of the rotary kiln, that is to say the area of the rotary kiln where the material to be thermally treated by the rotary kiln is located when it passes through the rotary kiln. The aforementioned temperatures relate in particular to the inside of the rotary tube in the area of the inlet, that is to say the higher end of the rotary tube, at which the material to be burned in the rotary tube is introduced into the rotary tube.

Ferner kann das Drehrohr, wie aus dem Stand der Technik bekannt, mit einer leicht zur Horizontalen geneigten Längsachse um seine Längsachse drehbar gelagert sein, beispielsweise über Wälzlager. Ferner kann das Drehrohr, wie aus dem Stand der Technik bekannt, in einem isolierten Gehäuse eingebaut sein, das das Drehrohr umgibt, wobei auch die Heizeinrichtungen für das Drehrohr in diesem Gehäuse angeordnet sein können. Ferner kann der Drehrohrofen die aus dem Stand der Technik bekannten Einrichtungen zur Aufgabe des Brenngutes in das Drehrohr, zur Entnahme des im Drehrohr thermisch behandelten Brenngutes aus dem Drehrohr, zur gasdichten Abdichtung des Drehrohrs (zur Einstellung einer gewünschten Ofenatmosphäre) sowie für eine etwaige Kühlung des thermisch behandelten Brenngutes umfassen.Furthermore, as is known from the prior art, the rotary tube can be mounted rotatably about its longitudinal axis with a longitudinal axis slightly inclined to the horizontal, for example by means of roller bearings. Furthermore, as is known from the prior art, the rotary tube can be installed in an insulated housing which surrounds the rotary tube, with the heating devices for the rotary tube also being able to be arranged in this housing. Furthermore, the rotary kiln can use the devices known from the prior art for feeding the kiln into the kiln, for removing the kiln thermally treated in the kiln from the kiln, for gas-tight sealing of the kiln (for setting a desired furnace atmosphere) and for any cooling of the kiln include thermally treated items to be fired.

Gegenstand der Erfindung ist auch die Verwendung des erfindungsgemäßen Drehrohrofens zur thermischen Behandlung von Brenngut, insbesondere zur thermischen Behandlung von Brenngut in Form von Schüttgütern, insbesondere in Form von Schüttgütern in Form von Granulaten, Pulvern oder Nanopulvern. Insbesondere wird der Drehrohrofen zur thermischen Behandlung von hochwertigem, insbesondere hochwertigem hochreinem Brenngut, insbesondere Brenngut in Form der vorbezeichneten Schüttgüter, verwendet, insbesondere in Form von solchem hochwertigem, hochreinem Brenngut, welches durch das Drehrohr nicht verunreinigt werden darf.The invention also relates to the use of the rotary kiln according to the invention for the thermal treatment of items to be fired, in particular for the thermal treatment of items to be fired in the form of bulk goods, in particular in the form of bulk goods in the form of granules, powders or nanopowders. In particular, the rotary kiln is used for the thermal treatment of high-quality, especially high-quality, high-purity items to be fired, in particular items to be fired in the form of the aforementioned bulk goods, in particular in the form of high-quality, high-purity items to be fired that must not be contaminated by the rotary kiln.

Gegenstand der Erfindung ist ferner auch die Verwendung einer Nickelbasislegierung zur innenseitigen Beschichtung eines indirekt beheizbaren Drehrohrs eines indirekt beheizbaren Drehrohrofens. Die Verwendung der Nickelbasislegierung erfolgt dabei mit der Maßgabe, dass das Drehrohr innenseitig mit der Nickelbasislegierung beschichtet wird, insbesondere durch die vorbezeichneten Verfahren. Bei dieser Verwendung können die Nickelbasislegierung, das Drehrohr sowie der Drehrohrofen die hierin offenbarten, erfindungsgemäßen Merkmale des erfindungsgemäßen Drehrohrofens aufweisen.The invention also relates to the use of a nickel-based alloy for coating the inside of an indirectly heatable rotary tube of an indirectly heatable rotary tube furnace. The use of the nickel-based alloy takes place with the proviso that the rotary tube is coated on the inside with the nickel-based alloy, in particular by the aforementioned method. With this use, the nickel-based alloy, the rotary tube and the rotary tube furnace can have the inventive features of the rotary tube furnace according to the invention disclosed herein.

Weitere Merkmale ergeben sich aus den Ansprüchen, der Figur eines Ausführungsbeispiels sowie der zugehörigen Beschreibung des Ausführungsbeispiels.Further features emerge from the claims, the figure of an exemplary embodiment and the associated description of the exemplary embodiment.

Sämtliche Merkmale der Erfindung können, einzeln oder in Kombination, beliebig miteinander kombiniert sein.All of the features of the invention can be combined with one another as desired, individually or in combination.

Nachfolgend wird ein Ausführungsbeispiel eines erfindungsgemäßen Drehrohrofens näher erläutert.An exemplary embodiment of a rotary kiln according to the invention is explained in more detail below.

Dabei zeigt, stark schematisiert und nicht maßstabsgerecht,

Figur 1
eine Schnittansicht eines Drehrohrs eines erfindungsgemäßen Drehrohrofens entlang seiner Längsachse.
It shows, highly schematic and not to scale,
Figure 1
a sectional view of a rotary tube of a rotary kiln according to the invention along its longitudinal axis.

In Figur 1 ist das in seiner Gesamtheit mit dem Bezugszeichen 1 gekennzeichnete Drehrohr eines nicht näher dargestellten, indirekt beheizbaren Drehrohrofens dargestellt. Das Drehrohr 1 weist eine im Wesentlichen rohrförmige Gestalt mit einer Längsachse L auf. Das Drehrohr 1 ist mit einer leichten Neigung der Längsachse L zur Horizontalen H drehbar um seine Längsachse L gelagert. Hierzu ist das Drehrohr 1 über nicht dargestellte Wälzlager, auf denen das Drehrohr 1 an seinem einen, hier höheren Ende 2 und an seinem zweiten, gegenüberliegenden, hier unteren Ende 3 drehbar auf einem Untergrund gelagert. Das Drehrohr 1 besteht aus einem austenitischen Stahlrohr 4, das innenseitig eine Beschichtung aus einer Nickelbasislegierung 5 aufweist.In Figure 1 the rotary kiln, identified in its entirety by the reference numeral 1, of an indirectly heatable rotary kiln, not shown in detail, is shown. The rotary tube 1 has an essentially tubular shape with a longitudinal axis L. The rotary kiln 1 is mounted rotatably about its longitudinal axis L with a slight inclination of the longitudinal axis L to the horizontal H. For this purpose, the rotary tube 1 is supported by roller bearings, not shown, on which the rotary tube 1 is rotatably supported on a substrate at its one, here higher end 2 and at its second, opposite, here lower end 3. The rotary tube 1 consists of an austenitic steel tube 4 which has a coating of a nickel-based alloy 5 on the inside.

Das Drehrohr 1 weist eine Länge (entlang der Längsachse L) von 2.500 mm und einen lichten Durchmesser (senkrecht zur Längsachse L) von 186 mm auf.The rotary tube 1 has a length (along the longitudinal axis L) of 2,500 mm and a clear diameter (perpendicular to the longitudinal axis L) of 186 mm.

Die Nickelbasislegierung 5 weist folgende chemische Zusammensetzung auf: Ni: 90 Masse-% Al: 10 Masse-% The nickel-based alloy 5 has the following chemical composition: Ni: 90 mass% Al: 10 mass%

Die Beschichtung 5 weist eine Dicke von 0,5 mm auf.The coating 5 has a thickness of 0.5 mm.

Die Differenz des linearen Längenausdehnungskoeffizienten α (bei 20° mit α in 10-6 K-1) des austenitischen Stahls 4 und der Nickelbasislegierung 5 beträgt weniger als 1,0.The difference in the linear expansion coefficient α (at 20 ° with α in 10 -6 K -1 ) of the austenitic steel 4 and the nickel-based alloy 5 is less than 1.0.

Um den austenitischen Stahl 4 des Drehrohres 1 mit der Nickelbasislegierung 5 zu beschichten, wurde die Nickelbasislegierung 5 mittels Drahtflammspritzen auf die Innenseite des austenitischen Stahls 4 des Drehrohres 1 aufgetragen.In order to coat the austenitic steel 4 of the rotary tube 1 with the nickel-based alloy 5, the nickel-based alloy 5 was applied to the inside of the austenitic steel 4 of the rotary tube 1 by means of wire flame spraying.

Das Drehrohr 1 ist über eine nicht näher dargestellte elektrische Heizung von außen indirekt beheizbar.The rotary tube 1 can be heated indirectly from the outside via an electrical heater (not shown in detail).

Bei der praktischen Anwendung wird das Drehrohr 1 über die elektrische Heizung von außen indirekt beheizt.In practical use, the rotary kiln 1 is heated indirectly from the outside via the electrical heater.

Ferner wird im Drehrohr 1 thermisch zu behandelndes Brenngut im Bereich des oberen Endes 2 über eine nicht näher dargestellte Einrichtung in das Drehrohr 1 eingetragen. Gleichzeitig wird das Drehrohr 1 über nicht näher dargestellte Antriebsmittel um seine Längsachse L gedreht. Durch die Heizeinrichtungen wird das Drehrohr 1 erhitzt und diese Wärme auf das im Drehrohr 1 befindliche Brenngut übertragen. Gleichzeitig bewegt sich das Brenngut aufgrund der Rotationsbewegung des Drehrohrs 1 um seine Längsachse L in Richtung des unteren Endes 3 des Drehrohrs 1. Während dieses Durchgangs des Brenngutes 1 durch das Drehrohr 1 wird das Brenngut thermisch im Drehrohr 1 behandelt. Nach dem Durchgang des Brennguts durch das Drehrohr 1 wir das Brenngut über nicht näher dargestellte Vorrichtungen aus dem Drehrohr 1 entnommen.Furthermore, in the rotary kiln 1, material to be thermally treated is introduced into the rotary kiln 1 in the area of the upper end 2 via a device not shown in detail. At the same time, the rotary tube 1 is rotated about its longitudinal axis L via drive means (not shown in detail). The rotary kiln 1 is heated by the heating devices and this heat is transferred to the material to be fired in the rotary kiln 1. At the same time, due to the rotational movement of the rotating tube 1, the material to be fired moves about its longitudinal axis L in the direction of the lower end 3 of the rotating tube 1. During this passage of the material 1 through the rotating tube 1, the material to be fired is thermally treated in the rotating tube 1. After the material to be fired has passed through the rotary kiln 1, the material to be fired is removed from the rotary kiln 1 using devices not shown in detail.

Das Drehrohr 1 eignet sich in besondere Weise zur thermischen Behandlung von Brenngut in Form von hochwertigen, hochreinen Produkten, insbesondere in Form von Schüttgütern, die durch das Drehrohr 1 nicht verunreinigt werden dürfen.The rotary kiln 1 is particularly suitable for the thermal treatment of material to be fired in the form of high-quality, high-purity products, in particular in the form of bulk goods, which must not be contaminated by the rotary kiln 1.

Claims (15)

Indirekt beheizbarer Drehrohrofen, umfassend die folgenden Merkmale: 1.1 Ein indirekt beheizbares Drehrohr (1); 1.2 das Drehrohr (1) weist innenseitig eine Beschichtung (5) aus einer Nickelbasislegierung auf. Indirectly heatable rotary kiln, comprising the following features: 1.1 An indirectly heatable rotary kiln (1); 1.2 the rotary tube (1) has a coating (5) made of a nickel-based alloy on the inside. Drehrohrofen nach Anspruch 1, wobei die Nickelbasislegierung einen Anteil an Nickel im Bereich von 30 - 99,5 % umfasst.Rotary kiln according to claim 1, wherein the nickel-based alloy comprises a proportion of nickel in the range from 30 to 99.5%. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Nickelbasislegierung neben Ni wenigstens einen der folgenden Bestandteile umfasst: Al, Mo oder WC.Rotary kiln according to at least one of the preceding claims, wherein the nickel-based alloy comprises at least one of the following components in addition to Ni: Al, Mo or WC. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Nickelbasislegierung einen Anteil an A1 im Bereich von 0,5 - 20,0 % und Ni im Bereich von 80,0 - 99,5 % umfasst.Rotary kiln according to at least one of the preceding claims, wherein the nickel-based alloy comprises a proportion of A1 in the range from 0.5 to 20.0% and Ni in the range from 80.0 to 99.5%. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Nickelbasislegierung einen Anteil an Mo im Bereich von 0,5 - 20,0 % und Ni im Bereich von 80,0 - 99,5 % umfasst.Rotary kiln according to at least one of the preceding claims, wherein the nickel-based alloy comprises a proportion of Mo in the range from 0.5 to 20.0% and Ni in the range from 80.0 to 99.5%. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Nickelbasislegierung einen Anteil an WC im Bereich von 0,5 - 60,0 % und Ni im Bereich von 40,0 - 99,5 % umfasst.Rotary kiln according to at least one of the preceding claims, wherein the nickel-based alloy comprises a proportion of WC in the range from 0.5 to 60.0% and Ni in the range from 40.0 to 99.5%. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Beschichtung (5) eine Dicke im Bereich von 0,1 mm bis 1,5 mm aufweist.Rotary kiln according to at least one of the preceding claims, wherein the coating (5) has a thickness in the range from 0.1 mm to 1.5 mm. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche, wobei die Beschichtung (5) durch wenigstens eines der folgenden Verfahren aufgetragen ist: Thermische Spritzen oder Einbrennen.Rotary kiln according to at least one of the preceding claims, wherein the coating (5) is applied by at least one of the following methods: thermal spraying or baking. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche mit einem metallischen Drehrohr (1).Rotary tube furnace according to at least one of the preceding claims with a metallic rotary tube (1). Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche mit einem Drehrohr (1) aus Stahl.Rotary tube furnace according to at least one of the preceding claims, with a rotary tube (1) made of steel. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche mit einem Drehrohr (1) aus einem warmfesten Stahl.Rotary tube furnace according to at least one of the preceding claims, with a rotary tube (1) made of a heat-resistant steel. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche mit einem Drehrohr (1) aus einem hitzebeständigen Stahl.Rotary tube furnace according to at least one of the preceding claims, with a rotary tube (1) made of a heat-resistant steel. Drehrohrofen nach wenigstens einem der vorhergehenden Ansprüche mit einem Drehrohr (1) aus austenitischem Stahl.Rotary tube furnace according to at least one of the preceding claims, with a rotary tube (1) made of austenitic steel. Verwendung einer Nickelbasislegierung zur innenseitigen Beschichtung eines indirekt beheizbaren Drehrohrs eines indirekt beheizbaren Drehrohrofens.Use of a nickel-based alloy for the inside coating of an indirectly heatable rotary kiln of an indirectly heatable rotary kiln. Verwendung des Drehrohrofens nach wenigstens einem der Ansprüche 1 bis 14 zur thermischen Behandlung von Brenngut.Use of the rotary kiln according to at least one of Claims 1 to 14 for the thermal treatment of material to be fired.
EP20183853.9A 2020-07-03 2020-07-03 Indirectly heatable rotary kiln with internal coating of nickel-based alloy and use of an indirectly heatable rotary kiln Pending EP3933335A1 (en)

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