Burner tube, burner, melting furnace, process for producing a burner tube, process for melting a material to be melted and use of a ceramic material

Abstract

The invention relates to a burner tube (11) for a burner (10) for forming a hot gas stream for melting metal, preferably nonferrous metal, as material to be melted, wherein the burner tube is configured at least for directing the hot gas stream in the direction of the material to be melted, wherein the burner tube is made of an oxide ceramic fiber composite material.

Description

[0001] Burner tube, burner, melting furnace, method for producing a burner tube, method for melting a melting material and use of a ceramic material

[0002] The invention relates to a burner tube for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as the melting material, wherein the burner tube is designed at least to orient the hot gas stream in the direction of the melting material. The invention further relates to a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as the melting material. The invention further relates to a melting furnace for melting metal, preferably non-ferrous metal, as the melting material. The invention further relates to a method for producing a burner tube for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as the melting material, wherein the burner tube is designed at least to orient the hot gas stream in the direction of the melting material.The invention further relates to a method for melting metal, preferably non-ferrous metal, as melting material by means of a melting furnace, wherein a hot gas stream is generated by means of a burner of the melting furnace, wherein the hot gas stream is directed in the direction of the melting material by means of a burner tube of the burner, wherein the melting material is melted by the hot gas stream. Finally, the invention relates to the use of a ceramic material for producing a burner tube for a burner for generating a hot gas stream for melting metal, preferably non-ferrous metal, as melting material, wherein the burner tube is designed at least to direct the hot gas stream in the direction of the melting material.

[0003] A burner tube of the type described above is known, for example, from WO 2021 / 170652 A1. As a component of a melting furnace burner intended to generate a hot gas stream for melting metal, preferably non-ferrous metal such as aluminum or the like, as the melting material, it serves in particular to direct the hot gas stream toward the melting material. When the burner tube is used as intended, a frequently highly inhomogeneous temperature distribution occurs within the burner tube with a high temperature gradient, particularly in a longitudinal direction of the burner tube. In view of this, a material of the burner tube, which is typically glass, a glass-ceramic, or a pure or monolithic ceramic material, regularly fails, significantly reducing the service life of the burner tube. Therefore, melting a melting material is disadvantageously cost-intensive.

[0004] The present invention is therefore based on the object of proposing a burner tube, a burner, a melting furnace, a method for producing a burner tube, a method for melting a melting material and a use of a ceramic material which enables cost-effective melting of metal, preferably non-ferrous metal, as melting material.

[0005] This task is performed by a burner tube with the characteristics of the

[0006] Claim 1, a burner with the features of claim 8, a melting furnace with the features of claim 13, a method for producing a burner tube with the features of claim 14, a method for melting a melting material with the features of claim 17 and a use of a ceramic material with the features of claim 19.

[0007] The burner tube according to the invention for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material is designed at least to align the hot gas stream in the direction of the melting material, wherein the burner tube is made of an oxide-ceramic fiber composite material.

[0008] According to the invention, the burner tube for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal such as aluminum or the like, as the melting material is designed or provided at least for orienting or guiding the hot gas stream in the direction of the melting material. The melting temperature of the metal or non-ferrous metal can preferably be less than 1000°C.

[0009] According to the invention, the burner tube is formed from an oxide-ceramic fiber composite material (oxide fiber composite), i.e., a composite material comprising oxide-ceramic fibers and an oxide-ceramic matrix. In addition to comparatively high mechanical strength, this material advantageously exhibits comparatively high thermal strength, in particular thermal shock resistance, so that the burner tube formed from this material is resistant even in the face of a highly inhomogeneous temperature distribution in the burner tube with a high temperature gradient, particularly axially or in a longitudinal direction of the burner tube, and in particular despite a thermal expansion coefficient of the oxide-ceramic fiber composite material, which is typically 4 ppm / K to 10 ppm / K.The service life of the burner tube can be considerably increased, which enables the advantageously cost-effective melting of metal, preferably non-ferrous metal, as the melt. A further advantage of forming the burner tube from the oxide-ceramic fiber composite material results from the comparatively low thermal conductivity of < 10 W / (m K) of this material, as a result of which the area surrounding the burner tube does not heat up. A slow preheating cycle before operating a burner comprising the burner tube or a melting furnace comprising the burner is therefore not necessary. Furthermore, insulation or coating of this material or the burner tube can generally be dispensed with during production of the burner tube. Both of these lead to an advantageous reduction in operating and manufacturing costs. Furthermore, the oxide-ceramic fiber composite material has excellent corrosion and wear resistance.Oxidation resistance. Furthermore, the oxide-ceramic fiber composite material exhibits comparatively high electromagnetic transparency, so that the burner tube can be used for a particularly advantageous embodiment of a burner, which is described further below.

[0010] Nevertheless, the oxide-ceramic fiber composite material or the burner tube can have or be coated. A coating can be useful for further functionalization, for example, if additional sealing and / or improved gas flow and / or improved electrical conductivity and / or adapted corrosion protection are desired. Proven, state-of-the-art coating processes can be used to form the coating. The coating can be metallic and / or ceramic.

[0011] The burner tube may have a gas inlet and a gas outlet.

[0012] A gas or gas stream can be introduced into the burner tube via the gas inlet, while the gas or gas stream or hot gas stream can be discharged from the burner tube via the gas outlet. The burner tube can have a first opening forming the gas inlet at a first end of the burner tube and a second opening forming the gas outlet at a second end of the burner tube, so that the burner tube can be designed to allow gas to flow through or be passed through by a gas or gas stream along a length of the burner tube. Advantageously, the burner tube can have a straight or linear course. With the gas outlet, the burner tube, which can form a flow guide element of a burner, can then be arranged or aligned in such a way that the hot gas stream that can be formed by means of the burner or a heating device of the burner can be aligned or guided in the direction of the melt.The inside of the burner tube can be structured to influence the direction of the gas flow. The burner tube can also have multiple gas inlets and gas inlets.

[0013] Advantageously, the oxide-ceramic fiber composite material, i.e., the oxide-ceramic fibers and / or the oxide-ceramic matrix, can comprise an oxide of aluminum and / or zirconium and / or silicon and / or yttrium. The oxide-ceramic fiber composite material can therefore comprise aluminum oxide or aluminum(HI) oxide and / or zirconium oxide or zirconium(IV) oxide or zirconium dioxide and / or silicon oxide or silicon dioxide and / or yttrium oxide or yttrium(HI) oxide. The use of other oxides is conceivable.

[0014] Advantageously, the oxide-ceramic fiber composite can have an open porosity of 20% to 50% to achieve optimized mechanical and thermal strength. Despite the open porosity, the tightness of the oxide-ceramic fiber composite is sufficient to align and guide the hot gas flow. If greater tightness is desired, increased sealing can be achieved by coating the oxide-ceramic fiber composite or burner tube. The coating can comprise ceramic and / or metallic layers.

[0015] Advantageously, the oxide-ceramic fiber composite material can have a fiber volume fraction of 20% to 50% in order to achieve optimized wetting of the fibers by the matrix, which can further increase the mechanical and thermal strength.

[0016] Advantageously, the burner tube can be designed to be stable at least with regard to a temperature distribution in the burner tube in which an axial temperature gradient is up to 1 °C / mm, preferably 1.5 °C / mm, particularly preferably 2 °C / mm. The burner tube can then be designed to be stable at least with regard to a heating of the burner tube or a temperature distribution in the burner tube in which a temperature gradient or temperature difference based on a longitudinal axis of the burner tube or over the length is up to 500 °C, preferably 900 °C, particularly preferably 1300 °C. In a possible intended use of the burner tube, in which a gas or gas stream is introduced into the burner tube via the gas inlet, the gas or gas stream is subsequently heated within the burner tube and further subsequently the gas or gas stream is used as hot gas orAs a hot gas stream can be discharged from the burner tube via the gas outlet, a temperature in the burner tube along the longitudinal axis from a first end of the burner tube to a second end of the burner tube can increase from 15 °C to 1300 °C.

[0017] Advantageously, the burner tube can be designed to be resistant at least to a temperature distribution in the burner tube in which a radial temperature gradient is up to 10 °C / mm, preferably 20 °C / mm, particularly preferably 25 °C / mm, and most preferably 50 °C / mm. The burner tube can then be designed to be resistant at least to heating of the burner tube or a temperature distribution in the burner tube in which a temperature gradient or temperature difference across a wall thickness of the burner tube is up to 500 °C, preferably 900 °C, particularly preferably 1300 °C.

[0018] Advantageously, the burner tube can have a length of > 500 mm and / or a diameter or outer diameter of > 20 mm and / or a wall thickness of < 50 mm, preferably < 10 mm, particularly preferably < 3 mm. For example, the length can be 500 mm to 1500 mm and / or the diameter can be 20 mm to 200 mm and / or the wall thickness can be 1 mm to 5 mm.

[0019] The outer diameter and / or inner diameter of the burner tube can vary along its length.

[0020] The burner tube may have a circular cross-sectional shape or any other cross-sectional shape.

[0021] The burner tube can be made of one or more parts.

[0022] Further advantageous embodiments of the burner tube emerge from the descriptions of the features of the subclaims referring back to method claim 14.

[0023] The burner according to the invention for forming a hot gas stream for melting metal, preferably non-ferrous metal, as the melting material comprises at least one burner tube according to the invention. The burner tube can form a flow guide element of the burner. The burner can comprise a plurality of, in particular two or three, burner tubes or flow guide elements.

[0024] The burner can comprise a preferably electrically operated heating device for generating the hot gas stream. The burner can generate the hot gas stream (ultra high temperature thermo jet) by heating a gas or gas stream that can be fed to the burner using the heating device. If the heating device is electrically operated, green electricity can advantageously be used to operate it, so that the burner can be operated in an essentially CO2-neutral manner, unlike natural gas burners, for example. The heat-carrying gas can be freely selected and is free of impurities, which leads to a high-quality melt. Nitrogen or a noble gas, such as argon, can preferably be used as the gas. A gas mixture can also be employed.

[0025] In one embodiment of the burner, the heating device can be designed as a plasma generation device for generating a plasma. The burner can be connected to an electrical power supply and also to a first supply for a plasma gas, by means of which the plasma can be formed. Furthermore, the burner can be connected to a second supply for the gas or gas stream, from which the hot gas stream can be formed by means of the plasma.

[0026] In an alternative embodiment of the burner, the heating device can be designed as an inductive heating device. The burner can be connected to an electrical power supply and, in particular via the gas inlet, to a supply for the gas or gas stream, from which the hot gas stream can be formed by heating or preheating the gas or gas stream by means of the inductive heating device.

[0027] Advantageously, the inductive heating device can have an induction coil arranged on the outside of the burner tube and an inductively heatable heating element, preferably made of a metal, preferably refractory metal, and arranged in the burner tube, wherein the heating element can have channels through which gas can flow. The induction coil can be arranged at least in sections or in a heating section of the burner tube, on the outside or on the outer circumference of the burner tube, preferably surrounding the burner tube. Furthermore, the burner tube can serve as a support for the heating element. The heating element can be arranged in the burner tube or in an interior space of the burner tube, in particular in the region of the heating section. The gas or the gas stream can pass through the first opening or the gas inlet into the burner tube or into the interior space of the burner tube and can be heated in the burner tube or interior space in a region of the heating section.For this purpose, as the gas or gas stream flows through the channels, heat can be transferred from the heater, which is heated by electrical currents induced in the heater, to the gas or gas stream. The heated gas or gas stream can then leave the burner tube as hot gas or hot gas stream through the second opening or gas outlet. This particularly advantageous embodiment of the burner is made possible by the aforementioned comparatively high electromagnetic transparency of the oxide-ceramic fiber composite material used to form the burner tube. Contactless heating of any designed heater is thus possible. This eliminates the need for electrical connection cables or a fuel supply. Furthermore, heat does not have to be supplied via a wall of the combustion tube. Instead, heat is transferred directly to the gas or gas stream.The radiator can form the channels. The channels can extend in the longitudinal direction.

[0028] The channels can have a straight or linear course to achieve a particularly straight hot gas flow. Furthermore, the channels can have a helical or winding course to achieve optimized heating of the gas flow. The heating element can be obtained by twisting small tubes, preferably made of the metal or refractory metal, which can form the channels.

[0029] Heat insulation of the burner or burner tube can be provided between the burner tube and the induction coil, which can be, for example, a coating or a ceramic fiber fleece.

[0030] The melting furnace according to the invention for melting metal, preferably non-ferrous metal, as melting material comprises a burner according to the invention.

[0031] The melting furnace can be an otherwise familiar and unchanged melting furnace. Preferably, the melting furnace can be a shaft furnace, hearth furnace, or crucible furnace.

[0032] The melting furnace may comprise a container for holding the molten melt, which may be a melting tank or a crucible. The container may be arranged in the melting furnace.

[0033] If the burner comprises the plasma generation device as a heating device, the burner can be arranged on the melting furnace to form a plasma in the form of a free gas torch and transfer heat by radiation to the melting material. The burner can be designed, dimensioned, arranged and / or aligned such that the formed plasma is arranged at a distance from the metallic melting material, and the hot gas flow directed towards the melting material can be formed by means of the plasma. The formed plasma therefore never comes into direct contact with the unmelted melting material or the molten melting material or a melt of the melting material. This also makes it possible to avoid the use of an electrode that contacts the melting material or the melt, since no such electrode should be present.

[0034] In the method according to the invention for producing a burner tube for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material, wherein the burner tube is or will be formed at least for orienting the hot gas stream in the direction of the melting material, the burner tube is formed from an oxide-ceramic fiber composite material.

[0035] For the advantageous effects of the method according to the invention, reference is made to the description of the advantages of the burner tube according to the invention.

[0036] The use of the oxide-ceramic fiber composite material in the manufacture of the burner tube creates comparatively greater flexibility with regard to possible geometric designs of the burner tube. Thus, when using the oxide-ceramic fiber composite material, the burner tube can be manufactured using a winding and / or braiding process, which allows a wide variety of geometric designs to be flexibly created in a simple manner. The geometry or cross-sectional shape of the burner tube can be easily determined by the geometry or cross-sectional shape of a winding core. Furthermore, the material thickness or wall thickness can be easily determined by a number of superimposed winding layers or windings. Furthermore, the burner tube can be manufactured starting from ceramic fiber fabrics.

[0037] Advantageously, fibers of the oxide-ceramic fiber composite material can be oriented at an angle of 25° to 65°, preferably 45°, to a longitudinal axis of the burner tube.

[0038] Further embodiments of the method emerge from the descriptions of the features of the subclaims which refer back to device claim 1.

[0039] In the method according to the invention for melting metal, preferably non-ferrous metal, as melting material by means of a melting furnace, a hot gas stream is formed by means of a burner of the melting furnace, wherein the hot gas stream is directed in the direction of the melting material by means of at least one burner tube of the burner, wherein the melting material is melted by the hot gas stream, wherein the burner tube is formed from an oxide-ceramic fiber composite material.

[0040] For the advantageous effects of the method according to the invention, reference is made to the description of the advantages of the burner tube according to the invention.

[0041] In an advantageous embodiment of the method, a gas stream can be introduced into the burner tube via a gas inlet of the burner tube, wherein the gas stream can be heated in the burner tube by means of a preferably inductive heating device of the burner to form the hot gas stream, wherein the hot gas stream can be discharged from the burner tube via a gas outlet of the burner tube.

[0042] Further embodiments of the method emerge from the descriptions of the features of the subclaims which refer back to device claims 1 and 8.

[0043] According to the invention, an oxide-ceramic fiber composite material is used as the ceramic material for producing a burner tube for a burner for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material, wherein the burner tube is designed at least to align the hot gas stream in the direction of the melting material.

[0044] For the advantageous effects of the use according to the invention, reference is made to the description of the advantages of the burner tube according to the invention.

[0045] Further embodiments of the use emerge from the descriptions of the features of the subclaims referring back to device claim 1 and method claim 14.

[0046] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawings.

[0047] They show:

[0048] Fig. 1 is a perspective view of a burner;

[0049] Fig. 2 a is a partial view of a radiator from the front;

[0050] Fig. 2b a partial view of the radiator from one side;

[0051] Fig. 3 is a sectional view of a melting furnace. Fig. 1 shows a burner 10 which comprises a burner tube 11 made of an oxide-ceramic fiber composite material. In a heating section 12 of the burner tube 11, an induction coil 13 of an inductive heating device 16 of the burner 10 is arranged on the outer circumference of the burner tube 11, surrounding the burner tube 11. Furthermore, in an interior of the burner tube 11 (not shown here), in a region of the heating section 12, there is arranged an inductively heatable heating element 20 made of a refractory metal, of the inductive heating device 16. The burner tube 11 is designed to be gas-flowable or capable of being flowed through by a gas or gas stream. The gas flow can enter the interior of the burner tube 1 1 in a flow direction indicated by an arrow 15 through a first opening 14 of the burner tube 1 1 forming a gas inlet and located at one end of the burner tube 1 1.By means of the inductive heating device 16, the gas flow in the interior in the region of the heating section 12 can be heated. For this purpose, as the gas or gas flow flows through channels 21 of the heating element 20, heat can be transferred from the heating element 20, which is heated by electrical currents induced in the heating element 20 by means of the induction coil 13, to the gas or gas flow. This creates a hot gas flow, which can leave the burner tube 11 again through a second opening 17 of the burner tube 11, which forms a gas outlet and is located at the other end of the burner tube 11. A directed hot gas flow can therefore be formed by means of the burner 10. The flow direction of the hot gas flow is indicated by an arrow 18. The burner tube 11 has a straight course. The first opening 14 is therefore opposite the second opening 17.A heat insulation 19 of the burner 1 1 is arranged between the induction coil 13 and the burner tube 1 1.

[0052] A summary of Figs. 2a-b shows sections of a heating element 22 formed by twisting small tubes 23 made of a refractory metal, which form channels 24. The channels 24 have a helical shape.

[0053] Fig. 2 shows a melting furnace 25 comprising a housing 26 made of a thermally insulating material, in which an inclined melting platform 27 of the melting furnace 25 is provided. An unmelted melt 28 can be arranged on the melting platform 27. A burner 30 of the melting furnace 25 is arranged on a housing wall 29 at a distance from the melt 28, which burner is designed to form a hot gas stream directed onto the melt 28. To direct the hot gas stream onto the melt 28, the burner 30 comprises at least one burner tube (not shown here). Under the action of the hot gas stream, the melt 28 can be melted, wherein the molten melt can be received in a container 31 of the melting furnace 25 designed as a crucible. The inclined inclination of the melting platform

[0054] 27 enables a melt of the melting material 28 or the molten melting material 28 to drip into the container 3 1. Hot exhaust gas can be removed from the melting furnace 25 via an exhaust 32 of the melting furnace 25.

Claims

Patent claims 1. Burner tube (11) for a burner (10, 30) for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material (28), wherein the burner tube is designed at least to align the hot gas stream in the direction of the melting material, characterized in that the burner tube is designed from an oxide-ceramic fiber composite material.

2. Burner tube according to claim 1, characterized in that the oxide-ceramic fiber composite material comprises an oxide of aluminum and / or zirconium and / or silicon and / or yttrium.

3. Burner tube according to claim 1 or 2, characterized in that the oxide-ceramic fiber composite material has an open porosity of 20% to 50%.

4. Burner tube according to one of the preceding claims, characterized in that the oxide-ceramic fiber composite material has a fiber volume fraction of 20% to 50%.

5. Burner tube according to one of the preceding claims, characterized in that the burner tube (11) is designed to be stable at least in view of a temperature distribution in the burner tube in which an axial temperature gradient is up to 1 °C / mm, preferably 1.5 °C / mm, particularly preferably 2 °C / mm.

6. Burner tube according to one of the preceding claims, characterized in that the burner tube (11) is designed to be stable at least in view of a temperature distribution in the burner tube in which a radial temperature gradient is up to 10 °C / mm, preferably 20 °C / mm, particularly preferably 25 °C / mm, most particularly preferably 50 °C / mm.

7. Burner tube according to one of the preceding claims, characterized in that the burner tube (11) has a length of > 500 mm and / or an outer diameter of > 20 mm and / or a wall thickness of < 50 mm, preferably < 10 mm, particularly preferably < 3 mm.

8. Burner (10, 30) for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material (28), comprising at least one burner tube (11) according to one of the preceding claims.

9. Burner according to claim 8, characterized in that the burner (10, 30) comprises a heating device for forming the hot gas flow, wherein the heating device is designed as a plasma generating device for generating a plasma.

10. Burner according to claim 8, characterized in that the burner (10, 30) comprises a heating device for forming the hot gas flow, wherein the heating device is designed as an inductive heating device (16).

11. Burner according to claim 10, characterized in that the inductive heating device (16) has an induction coil (13) arranged on the outside of the burner tube (11) and an inductively heatable heating element (20, 22), preferably made of a metal, preferably refractory metal, and arranged in the burner tube, wherein the heating element has channels (21, 24) through which gas can flow.

12. Burner according to claim 11, characterized in that the channels (21, 24) have a straight or helical course.

13. Melting furnace (25) for melting metal, preferably non-ferrous metal, as melting material (28), comprising a burner (10, 30) according to one of claims 8 to 12.

14. A method for producing a burner tube (11) for a burner (10, 30) for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material (28), wherein the burner tube is designed at least to align the hot gas stream in the direction of the melting material, characterized in that the burner tube is designed from an oxide-ceramic fiber composite material.

15. The method according to claim 14, characterized in that the burner tube (11) is manufactured using a winding process and / or braiding process.

16. Method according to claim 14 or 15, characterized in that fibers of the oxide-ceramic fiber composite material are oriented at an angle of 25° to 65°, preferably 45°, to a longitudinal axis of the burner tube (11).

17. A method for melting metal, preferably non-ferrous metal, as melting material (28) by means of a melting furnace (25), wherein a hot gas stream is formed by means of a burner (10, 30) of the melting furnace, wherein the hot gas stream is directed in the direction of the melting material by means of at least one burner tube (11) of the burner, wherein the melting material is melted by the hot gas stream, characterized in that the burner tube is formed from an oxide-ceramic fiber composite material.

18. The method according to claim 17, characterized in that a gas stream is introduced into the burner tube via a gas inlet of the burner tube (11), wherein the gas stream is heated in the burner tube by means of a preferably inductive heating device of the burner (10, 30) to form the hot gas stream, wherein the hot gas stream is discharged from the burner tube via a gas outlet of the burner tube.

19. Use of a ceramic material for producing a burner tube (11) for a burner (10, 30) for forming a hot gas stream for melting metal, preferably non-ferrous metal, as melting material (28), wherein the burner tube is designed at least to align the hot gas stream in the direction of the melting material, characterized in that the ceramic material is an oxide-ceramic fiber composite material.

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