Heating module and heat treatment apparatus

Abstract

A heating module (10) comprising at least one heating element (12) configured to convert electric energy into heat during operation, whereby the at least one heating element (12) comprises ceramic material and is arranged to form at least one heating zone (14, 16, 18) comprising a plurality of shanks (30). The at least one heating zone (14, 16, 18) is configured to radiate heat outwards from the heating module (10) in a diverging manner. Each shank (30) is clamped to the external surface (24) of the heating module (10) and the lower end (34) of each shank (30) is unsecured, thereby securing the heating zone in position while permitting a lower end (34) of the heating zone to move vertically downwards. The heating element forms a plurality of heating zones, the heating zones (14, 16, 18) being arranged longitudinally at a plurality of vertical levels.

Description

[0001] HEATING MODULE AND HEAT TREATMENT APPARATUS

[0002] Field of Invention

[0003] The present invention relates to a heating module comprising at least one heating element configured to convert electric energy into heat during operation. The present invention also relates to a heat treatment apparatus comprising at least one such heating module.

[0004] Background of the Invention

[0005] Resistance-heated furnaces rely on the heat produced through the Joule effect within their heating elements when an electric current passes through them. Such heating elements (which are also known as resistors) may be made of metallic materials, such as iron- chromium-aluminium (FeCrAI) alloys, or ceramic materials, such as molybdenum disilicide (MoSiz).

[0006] US 2021 / 0068206A1 discloses is a multi-shank heater to be mounted on a flat support substrate, wherein, with a normal direction relative to the support substrate, which is a direction from the heater side toward the support substrate side, as a basis, the multishank heater has U-shaped pieces. To provide a multi-shank heater capable of improving energy output, an angle 0 of a planar direction of the U-shaped pieces, which is a direction from the heater side toward the support substrate side, is ±10° or more and ±60° or less.

[0007] US 6160957 discloses a flat infrared radiating panel including a wall made from ceramic fibre material. An electric heating element is adapted for connection to an electric current source for heating the element to a high temperature at which it will emit infrared radiation is fastened to the wall with the aid of staples. The heating element is mounted in spaced relationship with the surface of the wall and is retained between pairs of ceramic rods that engage opposite faces of the heating element.

[0008] DE 1809436 discloses a replaceable heating cartridge for electrically heated industrial furnaces, wherein the heating conductors of the heating cartridge are inserted into longitudinal grooves of a heating conductor carrier made of insulating material.

[0009] Metallic heating elements are typically only used for temperatures up to 1200°C whereas ceramic heating elements are suitable for use in applications requiring heating element temperatures exceeding 1200°C. Molybdenum disilicide heating elements can for example be effectively utilized for heating element temperatures up to 1850°C, which makes them suitable for demanding industrial heating applications in fields such as glass manufacturing and steel production. The utilization of ceramic heating elements has however faced some limitations due to the decreasing strength and creep resistance of ceramic material at elevated temperatures, which can lead to softening and deformation of ceramic heating elements during operation. Additionally, ceramic heating elements may experience detrimental deformation due to electromagnetic forces resulting from the interaction between electric currents flowing through them and the magnetic fields generated around them. These electromagnetic forces can cause undesired shape changes, size variations, and movement of the ceramic heating elements away from their intended installation position. If a ceramic heating element becomes bent or twisted out of shape during operation, the risk of unintended current paths is increased and the performance and structural integrity, as well as the safety, reliability, and efficiency of the heating element may be adversely affected.

[0010] Description of the Invention

[0011] In an aspect of the invention, there is provided an improved heating module comprising the features recited in claim 1.

[0012] The heating module comprises at least one heating element configured to convert electric energy into heat during operation. A longitudinal axis of the heating module extends in a vertical direction during operation. The at least one heating element comprises ceramic material and is arranged to form at least one heating zone comprising a plurality of shanks, i.e. two or more shanks. Each shank is connected to at least one adjacent shank and extends between an upper end of a heating zone and a lower end of a heating zone during operation. The at least one heating zone is mounted on an external surface of the heating module and configured to radiate heat outwards from the heating module in diverging manner during operation. The at least one heating zone is configured to extend at least 270° around a circumference of the external surface of the heating module. Each shank is clamped to the external surface of the heating module, and the lower end of each shank is unsecured, thereby securing the at least one heating zone in position while permitting a lower end of the at least one heating zone to move vertically downwards during operation. The at least one heating element is arranged to form a plurality of said heating zones, i.e. two or more heating zones. The plurality of heating zones is arranged longitudinally at a plurality of vertical levels during operation.

[0013] Detrimental deformation of the at least one heating element will thereby be reduced or prevented since the at least one heating element will move in a predicted way as its strength and creep resistance decrease at elevated temperatures. The shanks of each heating zone will namely be restrained or prevented from moving away from their intended installation position, and any bending or twisting of the unsecured lower end of each shank will be reduced or prevented since gravity will cause the lower end of each shank to move vertically downwards during operation. The heating module will therefore exhibit improved performance, structural integrity, safety, reliability, and efficiency, and the risk of unintended current paths during operation will be decreased.

[0014] Moreover, since the at least one heating zone is configured to extend at least 270° around the circumference of the external surface of the heating module, and since the at least one heating element is arranged to form a plurality of said heating zones, and the plurality of heating zones is arranged longitudinally at a plurality of vertical levels during operation - the heating module is configured to provide an omnidirectional and diverging heating capability while being devised to have an elongated shape.

[0015] Thus, the heating module can be utilised as a heating cartridge for high temperature heating.

[0016] Such a heating module has the ability to achieve high power density, i.e. a power density of at least 100 kW / m2at 1500°C, since it can withstand high temperatures (i.e. heating element temperatures exceeding 1200°C), thereby ensuring efficient heat output.

[0017] In this context, it is noted that the inventors have realised that an elongated heating module having a longer extension along its longitudinal axis than perpendicularly thereto, which heating module can be operated at temperatures exceeding 1200°C, can be enabled by the combination of the heating element comprising ceramic material and it being arranged to form a plurality of heating zones. When arranged along a vertical direction, each shank will be elongated due to thermal expansion. The inventors have realised that by utilising a plurality of heating zones, each heating zone comprising shanks extending between upper and lower ends of the respective heating zone, the heating zones and the shanks therein can be kept short. The provision of more than one heating zone arranged longitudinally at a plurality of vertical levels enables devising the heating module as an elongated heating module. Such comparatively shorter shanks extending only along each heating zone instead of along the entire heating module enable a design of the shanks that will not rupture due to gravity during operation at high temperatures.

[0018] According to embodiments, the plurality of shanks may be arranged to have a small shank centre-to-centre distance, a, i.e. where 2D<a<10D, or 2D<a<8D, or 2D<a<6D, or 2D<a<4D, and D is the diameter of the at least one heating element, which may be 1 - 20 mm, such as 3 - 15 mm. Such a compact arrangement of shanks further increases the ability of the heating module to achieve a high power density since utilizes the heating module's surface to a higher extent, it helps to limit the deformation that occurs due to thermal expansion and contraction of the at least one heating element during heating and cooling cycles since it minimizes the mechanical stress induced by temperatures changes and thereby limits the strain on the at least one heating element, and it allows for more rapid heat transfer within the at least one heating element, resulting in faster heat-up times when a heating module is turned on.

[0019] According to embodiments, the at least one heating zone is configured to extend at least or equal 270, such as at least or equal to 300°, such at least or equal 310°, such as at least or equal 320°, at least or equal 330°, at least or equal 340°, at least or equal 350° around a circumference of the external wall of the heating module. The heating module may thereby be configured to provide omnidirectional heat radiation, i.e. to radiate heat uniformly in all directions (or "iso-tropically"). Such an external placement of at least one heating zone will minimize thermal stress within the heating module itself as the external surface of the heating module will expand uniformly during heating, reducing the risk of localized stress concentrations and cracking at elevated temperatures.

[0020] Assembling, accessing, or replacing a heating zone mounted on an external surface or wall of a heating module may also be simpler than assembling, accessing or replacing a heating zone mounted on an internal wall of a heating module. This may facilitate a "hot swap", in which one or more components of a heating system is / are replaced without shutting down an entire heating system, which may minimize disruptions during maintenance or repair work.

[0021] According to embodiments, the heating module comprises a support structure. Optionally, the heating module may comprise insulation material, which may be connected to the support structure, by mechanical joining and / or gluing for example. The at least one heating zone is mounted on an external surface of the support structure and / or on an external surface of the insulation material, which constitutes an external surface of the heating module. The support structure and / or the insulation material and may provide electrical insulation and / or thermal insulation and / or resistance to chemicals and / or resistance to heat and / or resistance to thermal degradation.

[0022] According to embodiments, the support structure comprises at least one of the following : refractory material, such as a refractory brick or a refractory castable, ceramic material, or ceramic fibre, metallic material. Further, according to embodiments, the support structure may be supported by at least one rod or at least one tube. The at least one rod or tube may be central and / or vertical. According to embodiments the support structure may be supported by a disc or a plate.

[0023] According to embodiments, the heating module may comprise at least one rod or tube, wherein the support structure is supported by the at least one rod or tube arranged centrally. In this manner, the support structure may be held in place along the longitudinal axis by the at least one rod or tube.

[0024] For instance, the at least one rod or tube may be arranged within the support structure.

[0025] In such embodiments, the at least one rod or tube is made of a material that maintains its integrity at high temperatures. Thus, the support structure and indirectly, the shanks of the heating zones, may be reliably supported in the vertical direction. For instance, the at least one rod or tube may be made from silicon carbide or aluminium oxide.

[0026] According to embodiments, the heating module may comprise a disc or a plate and / or a pin, wherein the support structure is supported by the disc or the plate or the pin. In this manner, the support structure may rest on the disc or the plate or the pin and thus, the weight of the support structure and of the shanks of the heating zones and of the terminals may be supported.

[0027] According to embodiments, the at least one rod or tube may be connected to the disc or the plate and / or the pin. In this manner, the weight of the support structure and of the shanks of the heating zones and of the terminals may be supported by the at least one rod or tube or the pin via the disc or the plate and / or the pin.

[0028] For instance, the disc or the plate may be directly or indirectly connected to the at least one rod or tube via threads, a bayonet coupling or the pin extending below the disc or the plate through a hole in the at least one rod or tube. In embodiments comprising the pin, it may extend through a hole in the at least one rod or tube immediately below the support structure.

[0029] According to embodiments, the insulation material comprises ceramic fibre insulation material, such as vacuum-formed ceramic fibre insulation.

[0030] According to embodiments, each shank is clamped to the external surface of the heating module at an upper end of the shank. Additionally, or alternatively, each shank is clamped at at least one point, or at a plurality of points, along its extension between an upper end of a heating zone and a lower end of the heating zone, such as at a point halfway between the upper end and lower end of the heating zone, while the lower end of each heating zone remains unsecured.

[0031] According to embodiments, each shank extends in a straight line or a bent line or curved line between the upper end of a heating zone and a lower end of a heating zone.

[0032] According to embodiments, the heating module comprises a plurality of parallel shanks. The plurality of parallel shanks may extend in a vertical direction or at an angle to the vertical direction during operation.

[0033] According to embodiments, the heating module comprises at least two terminals, each terminal comprising a first end that is configured to be connected to the at least one heating zone, and a second end that is configured to be connected to an electric power source or an adjacent terminal and wherein at least one of the second end of the at least two terminals of the heating module is configured to be connected to the electrical power source. A plurality of terminals may be connected to an electric power source individually, or in one or more groups. The first end of the at least two terminals may be connected to the at least one heating zone by welding using any suitable welding technique. Each of the second end of the at least two terminals may comprise a contact-improving coating.

[0034] According to embodiments, the first end of each terminal may be secured to the external surface of the heating module and relative to the external surface in at least one direction along the longitudinal axis. In this manner, it will be ensured that when the terminals are subjected to thermal elongation during operation of the heating module, the thermal elongation does not subject the heating zone to mechanical stress, such as the shanks of the heating zone which are connected to the terminals.

[0035] Since the terminals extend from above the heating zone to the heating zone, the first end of each terminal may be secured relative to the external surface of the heating module in a manner preventing the terminals from elongating in a downwardly direction.

[0036] According to embodiments, the at least one heating element and / or the at least two terminals comprises / comprise one or more of the following ceramic materials: a silicide, molybdenum disilicide (MoSi2), molybdenum disilicide alloyed with tungsten (W), chromium (Cr) or aluminium (Al), molybdenum disilicide containing an oxide. The physical properties of a silicide, such as MoSi?, for example its high temperature strength, thermal stability and fracture toughness at elevated temperature, can be improved by alloying with tungsten (W) or aluminium (Al) or chromium (Cr). Optionally, the at least one element and the at least two terminals comprise or consist of the same material.

[0037] According to embodiments, the at least one heating element is arranged to form a plurality of alternating peaks and valleys, such as a plurality of alternating U-shaped peaks and valleys, or a zig-zag pattern, or a spiral, or a porcupine design, or a loop.

[0038] According to embodiments, at least one of the following components has a circular or an elliptical or a polygonal cross section: an external surface of the heating module, an external surface of the support structure, an external surface of the insulation material, the at least one heating zone.

[0039] The at least one heating element is arranged to form a plurality of heating zones, and the plurality of heating zones is arranged horizontally around a circumference of the heating module. A heating module may comprise a plurality of both horizontally arranged heating zones and longitudinally arranged heating zones.

[0040] According to embodiments, each heating zone may have a vertical extension within a range of 0.3 - 1.5 m. In this manner, the shanks made of ceramic material of each heating zone may not rupture due to gravity acting on the shanks during operation when the shanks reach high temperatures, such as higher than 1200°C, such as 1500°C or more. Thus, the heating zone will maintain its integrity as the thermal creep will be reduced. Namely, during the foreseeable lifespan of the heating zone, i.e. before the heating zone needs replacing due to further factors, such as erosion due to the high temperature use, the weight of ceramic shanks within this range of length may not cause the shanks to elongate to such an extent that the shanks will rupture.

[0041] According to embodiments, each shank is clamped at a distance, d, from the external surface of the heating module. The distance, d, is from 0 to 2D, such as 0.5D to 1.5 wherein D is a diameter of heating element. This will ensure that the heating element is separated from the external surface of the support structure and thereby will ensure that more heat will be radiated. Further, this will help to avoid potential reactions between the at least one heating element and the external surface of the heating module on which it is mounted which could negatively affect the at least one heating element's performance and structural integrity. It also allows the at least one heating element to expand and contract without causing stress or cracking in the at least one heating element or the external surface of the heating module. Also, it will facilitate better heat dissipation, minimizes localized hotspots, ensures more uniform heating, and reduces the risk of unintended current paths.

[0042] According to embodiments, the least one heating element has a diameter, D, and the heating module comprises at least one of the following : at least two terminals having a diameter of 2D to 3D, a shank centre-to-centre distance, a, where 2D<a<10D, or 2D<a<8D, or 2D<a<6D, or 2D<a<4D, a distance between heating zones arranged at a plurality of vertical levels of A, where 2D<A<20D, or 2D<A<18D, or 2D<A<16D, or 2D<A<14D, or 2D<A<12D, or 2D<A<10D, or 2D<A<8D, or 2D<A<6D, or 2D<A<4D, a distance between clamps > 4D, or > 5D, or > 6D, or >8D, or > 10D, or > 12D, or > 14D, or > 16D, or > 18D, or > 20D.

[0043] The diameter, D, of the at least one heating element may be at least 1 mm, at least 2 mm, at least 3 mm, or at least 4 mm, or at least 5 mm, or at least 6 mm, or at least 7 mm, or at least 8 mm, or at least 9 mm, or at least 10 mm, and up to 3 mm, up to 4 mm, or up to 5 mm, or up to 6 mm, or up to 7 mm, or up to 8 mm, or up to 9 mm, or up to 10 mm, or up to 11 mm, or up to 12 mm, or up to 13 mm, or up to 14 mm, or up to 15 mm, or up to 16 mm, or up to 17 mm, or up to 18 mm, or up to 19 mm, or up to 20 mm.

[0044] The present invention also concerns a heat treatment apparatus comprising at least one compartment configured to receive at least one object that is to be heat-treated, and at least one heating module according to any of the embodiments described herein. The at least one compartment may at least partly surround the at least one heating module.

[0045] Further discussed herein is a method for manufacturing a heating module according to any of the embodiments described herein, wherein the heating module comprises at least one heating element configured to convert electric energy into heat during operation.

[0046] The method comprises arranging at least one heating element comprising ceramic material to form at least one heating zone comprising a plurality of shanks, whereby each shank is connected to at least one adjacent shank and extends between an upper end of a heating zone and a lower end of a heating zone during operation. The method also comprises mounting the at least one heating zone on an external surface of the heating module, whereby the at least one heating zone is configured to radiate heat outwards from the heating module in a diverging manner during operation. The method further comprises clamping each shank to the external surface of the heating module leaving the lower end of each shank unsecured, thereby securing the at least one heating zone in position while permitting a lower end of the at least one heating zone to move vertically downwards during operation.

[0047] According to embodiments, the method also comprises at least one of the following :

[0048] - providing the heating module with a support structure, and optionally with insulation material, and mounting the at least one heating zone on an external surface of the support structure or on an external surface of the insulation material, which constitutes an external surface of the heating module,

[0049] - providing the heating module with a support structure wherein the support structure comprising at least one of the following : refractory material, such as a refractory brick or a refractory castable, ceramic material, ceramic fibre or metallic material,

[0050] - providing the heating module with insulation material comprising ceramic fibre insulation material, such as vacuum-formed ceramic fibre insulation,

[0051] - clamping each shank to the external surface of the heating module at an upper end of the shank,

[0052] - providing the heating module with at least two terminals, each terminal comprising a first end and a second end, and connecting the first end of the at least two terminals to the at least one heating zone, and connecting the second end of the at least two terminals of the heating module to an electric power source or an adjacent terminal and wherein at least one of the second end of at least two terminals of the heating module is configured to be connected to the electrical power source,

[0053] - optionally connecting the first end of the at least one terminal to the at least one heating zone by welding,

[0054] - optionally providing each second end of the at least two terminals with a contactimproving coating,

[0055] - providing the heating module with at least one heating element and / or at least two terminals comprising one of the following ceramic materials: The heating module (10) according to any preceding claim, wherein the at least one heating element (12) and / or the at least two terminals (26) comprises one or more of the following ceramic materials: a silicide, molybdenum disilicide (MoSi2), molybdenum disilicide alloyed with tungsten (W), chromium (Cr) or aluminium (Al), molybdenum disilicide containing an oxide,

[0056] - arranging each shank to extend in a vertical direction during operation,

[0057] - arranging the at least one heating element to form a plurality of alternating peaks and valleys, such as a plurality of alternating U-shaped peaks and valleys, or a zig-zag pattern, or a spiral, or a porcupine design, or a loop,

[0058] - providing at least one of the following components with a circular or an elliptical or a polygonal cross section: an external surface of the heating module, an external surface of the support structure, an external surface of the insulation material, the at least one heating zone,

[0059] - providing at least one heating zone that extends at least or equal to 270°, or at least or equal to 300°, or at least or equal to 310°, or at least or equal to 320°, or at least or equal to 330°, or at least or equal to 340°, or at least or equal to 350° around a circumference of the external wall of the heating module,

[0060] - arranging the at least one heating element to form a plurality of said heating zones horizontally around the circumference of the heating module, and / or longitudinally at a plurality of vertical levels,

[0061] - clamping each shank at a distance, d, from the external surface of the heating module,

[0062] - providing the heating module with at least one heating element having a diameter, D, and with at least one of the following :

[0063] - at least two terminals having a diameter of 2D to 3D,

[0064] - a shank centre-to-centre distance, a, where 2D<a<10D, or 2D<a<8D, or 2D<a<6D, or 2D<a<4D,

[0065] - a distance between heating zones arranged at a plurality of vertical levels of A, where 2D<A<20D, or 2D<A<18D, or 2D<A<16D, or 2D<A<14D, or 2D<A<12D, or 2D<A<10D, or 2D<A<8D, or 2D<A<6D, or 2D<A<4D,

[0066] - a distance between clamps > 4D, or > 5D, or > 6D, or >8D, or > 10D, or > 12D, or > 14D, or > 16D, or > 18D, or > 20D,

[0067] - clamping each shank to the external surface of the heating module with at least one clamp, such as at least one clamp comprising ceramic material,

[0068] - clamping each shank at at least one point along its extension between an upper end of a heating zone and a lower end of the heating zone,

[0069] - optionally welding ceramic material to form the at least one heating element,

[0070] - connecting at least one clamp to the external wall of the support structure and / or to the external wall of the insulation material by at least one of: mechanical joining and / or gluing and / or welding.

[0071] The steps of a method according to any embodiment of the invention may be carried out in any suitable order and not necessarily in the order recited. A plurality of steps may be carried out at the same time. Part of a step may be carried out before carrying out at least part of another step.

[0072] All embodiments of the invention and particular features mentioned herein may be taken in isolation or in combination with any other embodiments and / or particular features mentioned herein (hence describing more particular embodiments and particular features than disclosed herein) without departing from the disclosure of the invention. Definitions

[0073] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0074] The term "shank" is intended to mean a part of a heating element that contributes to the overall heat distribution and performance of the heating element.

[0075] The term "heating zone" is intended to mean the heat generating part of a heating element. The "heating zone" comprises a plurality of shanks.

[0076] The term "during operation" is intended to mean during the time the at least one heating element is being used convert electric energy into heat.

[0077] The term "the heating zone is configured to radiate heat outwards from the heating module in a diverging manner" is intended to mean that the heat generated by the heating module is spread outwards in an essentially homogeneously distributed pattern. The heat does not radiate from a planar surface or in a converging manner, as would be the case if heat is radiated from a furnace wall or radially inwards from a heating zone mounted on an internal surface of a cylindrical support structure.

[0078] The term "an external surface of the heating module" is intended to mean one or more outermost or exposed or visible layers of a heating module which face outwards.

[0079] A "lower end of a heating zone" encompasses not only the lowest part of a heating zone during operation but may also include a lower portion of the heating zone, i.e. up to 10%, or up to 5%, of the total height of the heating zone measured from the lowest part of the heating zone.

[0080] The "upper end of a shank" encompasses not only the highest part of a shank during operation but also includes the upper portion of the shank, i.e. up to 30%, or up to 25%, or up to 20%, or up to 15%, or up to 10%, or up to 5%, of the total height of the heating zone measured from the highest part of the shank.

[0081] The term "permitting a lower end of the at least one heating zone to move vertically downwards during operation" is intended mean that when the ceramic material of the heating element expands thermally during operation at elevated heating element temperatures, gravity will cause the lower end of the heating zone to move vertically downwards.

[0082] The term "vertical" as regards the extension of a heating module, or a support structure or a shank is intended to mean at right angles to a horizontal plane, or in a direction that is ±45°, or ±30°, or ±20°, or ±10°, or ±5° from a vertical direction.

[0083] The term "support structure" is intended to mean a load-carrying arrangement of the heating module. The support structure holds the at least one heating zone, and optionally the insulation material, in place and provides mechanical strength and stability to the heating module.

[0084] The term "clamp" is intended to mean at least one fastener, such as a brace, band, or clasp, for securing each shank to an external surface of a heating module. A single clamp may be used to secure one or more shanks to an external surface of a heating module. Alternatively, a plurality of clamps may be used to secure one or more shanks to an external surface of a heating module. Each shank may be secured to an external surface of a heating module by at least one of: mechanical joining and / or gluing and / or welding.

[0085] Terms such as "diameter", "circumference", "sector" and "radially outwards" are not intended to imply that a component is necessarily circular, but should be interpreted to also include an equivalent term, such as "width", "perimeter", "part" and "in a direction away from the centre" if a component is not circular.

[0086] A "first end" and / or a "second end" of a terminal encompasses not only the end / s of a terminal but may also include an end portion of the terminal, i.e. up to 10% or up to 5% of the total length of the terminal.

[0087] As used herein, the term "comprises" will take its usual meaning in the art, namely indicating that the component includes but is not limited to the relevant features (i.e. including, among other things). The term "comprises" also includes references to a component "consisting of" the relevant feature(s) or material(s).

[0088] Description of the Figures

[0089] Figure 1: schematically shows a perspective view of a heating module according to an embodiment of the invention,

[0090] Figure 2: schematically shows a side view of part of the heating module shown in Figure 1, Figure 3: schematically shows an enlarged view of an upper part of a heating zone of the heating module shown in Figures 1 and 2,

[0091] Figures 4 & 5: schematically show cross sections of a heating module according to embodiments of the invention,

[0092] Figures 6 & 7: schematically show cross sections of a heat treatment apparatus according to embodiments of the invention,

[0093] Figure 8 schematically show a perspective view of an omnidirectional cylindrical heating module,

[0094] Figure 9 schematically shows an enlarged view of an upper end of a lower heating zone of the heating module shown in Figure 8, and

[0095] Figure 10 schematically shows a partly exploded side view of a cylindrical heating module.

[0096] All of the drawings have not necessarily been drawn to scale and the dimensions of certain features may have been exaggerated for the sake of clarity.

[0097] Detailed description

[0098] The invention is illustrated by way of the following examples, which are not intended to be limiting on the general scope of the invention.

[0099] Figure 1 schematically shows a perspective view of an omnidirectional cylindrical heating module 10 comprising at least one heating element 12 comprising ceramic material and configured to convert electric energy into heat during operation. The at least one heating element 12 comprises one of the following ceramic materials: a silicide, molybdenum disilicide (MoSi?), molybdenum disilicide alloyed with tungsten (W) or aluminium (Al) or chromium, molybdenum disilicide containing an oxide or a combination thereof. Such ceramic materials have a high melting point, and good oxidation and corrosion resistance in various atmospheres, including nitrogen, hydrogen, and reducing environments.

[0100] In the illustrated example, the heating module 10 is mounted in a furnace or ladle roof 13. However, a heating module 10 according to the present invention does not necessarily have to be mounted in a floor, wall or roof of a heat treatment apparatus, but may be used in hanging applications.

[0101] The heating module 10 is arranged so that a longitudinal axis, A, of the heating module 10 extends in a vertical direction during operation. A heating module 10 according to the present invention may be positioned at an angle to the vertical direction during operation. For example, a heating element 10 may extend at an angle of up to 45° from the vertical direction, such as up to 30° from the vertical direction, when used to achieve a heating element temperature up to 1200°C, and at an angle of up to 20°, or up to 10° from the vertical direction when used to achieve a heating element temperature exceeding 1200°C. At heating element temperatures exceeding 1500°C, a vertical alignment is advantageous.

[0102] The at least one heating element 12 is arranged to form a plurality of cylindrical heating zones 14, 16, 18. In the illustrated example, the heating module 10 comprises three cylindrical heating zones 14, 16, 18 arranged longitudinally at three vertical levels with one omnidirectional heating zone 14, 16, 18 per vertical level. Each heating zone 14, 16, 18 is namely configured to extend at least 270°, such as at least 330°, around a circumference of an external wall or surface 24 of the heating module 10.

[0103] The heating module 10 comprises a cylindrical support structure 20 located radially inwards of the cylindrical heating zones 14, 16, 18 and insulation material 22, such as ceramic fibre insulation material, connected to the support structure 20, whereby the at least one heating zone 14, 16, 18 is mounted on an external surface of the insulation material 22, which constitutes an external surface 24 of the heating module 10. Insultation material 22 may be connected to the support structure 20 by mechanical joining and / or gluing.

[0104] The heating zones 14, 16, 18 are configured to radiate heat outwards from the heating module 10 in a diverging manner, during operation, i.e. radially outwards from the longitudinal axis A of the heating module 10. Heat is thereby distributed evenly without being focused at a single point or in a single two-dimensional plane. Such a design ensures uniform, efficient and consistent heat distribution across a desired space, optionally reaching all parts of a surrounding space. This is beneficial for applications such as industrial process equipment where consistent temperature profiles are crucial.

[0105] The heating module 10 comprises a plurality of terminals 26. Each terminal 26 comprises a first end (not shown in Figure 1, see further below with reference to Figures 8 and 9) that is configured to be connected to a heating zone 14, 16, 18, by welding for example, and a second end 28 that is configured to be connected to an electric power source or to an adjacent terminal. The second end 28 of at least two terminals 26 may comprise a contact-improving coating. Each terminal 26 may comprise ceramic material, such as the same ceramic material as the at least one heating element 12. In the illustrated embodiment, each terminal 26 has a uniform diameter of about 2D, where D is the diameter of the at least one heating element 12, i.e. a diameter D of one shank 30 of the heating zones 14, 15, 18. The diameter, D, of the at least one heating element 12 may be 3-12 mm. The at least two terminals 26 do not necessarily have to have a uniform diameter.

[0106] The second end 28 of a terminal 26 of a heating module 10 according to the present invention does not necessarily have to be located at the top of the heating element 10 during operation, as shown in Figure 1. The second end 28 of one or more terminals 26 may be located at a side of the heating element 12.

[0107] According to embodiments, one or more complementary heating arrangements, such as one or more heating arrangements comprising a heating element mounted on a planar support structure, may be mounted at the top and / or the bottom of a heater module 10 according to the present invention.

[0108] As can be more clearly seen in Figure 2, each heating zone 14, 16, 18 comprises a plurality of parallel vertical shanks 30 which each extend between an upper end 32 of a heating zone 14, 16, 18, and a lower end 34 of a heating zone 14, 16, 18 during operation. In the illustrated example, the plurality of shanks 30 is arranged to form a plurality of alternating U-shaped peaks 36 and U-shaped valleys 38, whereby the upper ends of two adjacent shanks 30 are connected to form a U-shaped peak 36 at an upper end 32 of the heating zone 14, 16, 18 and the lower ends of two adjacent shanks 30 are connected to form a U- shaped valley 38 at the lower end 34 of a heating zone 14, 16, 18. The highest part of each U-shaped peak 36 constitutes the upper end of 32 of a heating zone 14, 16, 18 and the lowest part of each U-shaped valley 38 constitutes the lower end of 34 of a heating zone 14, 16, 18. A plurality of shanks 30 may be arranged in any other suitable manner, such as in a zig-zag pattern, or a spiral, or a porcupine design, or a loop.

[0109] The heating module 10 comprises a plurality of clamps 40 and each shank 30 is clamped to the external surface 24 of the heating module 10 at a plurality of points along its extension between the upper end 32 and the lower end 34 of the heating zone leaving a lower end of each shank 30 unsecured. This secures each heating zone 14, 16, 18 in position while permitting a lower end 34 of each heating zone 14, 16, 18 to move vertically downwards when the at least one heating element 12 thermally expands during operation. The heating module 10 exhibits a small shank centre-to-centre distance, a, of about 2D and a vertical distance, A, between adjacent heating zones 14, 16, 18 of 8D. The clamps 40 are evenly spaced with a vertical distance of 8 D between clamps 40. The at least one heating zone 14, 16, 18 may have any desired length, L, such as a length of 100 mm to 2000 mm.

[0110] According to some embodiments, each heating zone 14, 16, 18 has a vertical extension within a range of 0.3 - 1.5 m, such as within a range of 0.5 - 1.5 m, such as 0.8 - 1.3 m. That is, the at least one heating zone 14, 16, 18 may have a length L of 300 mm to 1500 mm, such as 500 mm to 1500 mm, such as of 800 mm to 1300 mm.

[0111] Figure 3 schematically shows an enlarged view of an upper end 32 of a heating zone 16 of the heating module 10 shown in Figures 1 and 2. Each shank 30 is clamped to the external surface 24 of the heating module 10 at an upper end of the shank 30 using a clamp 40. Additionally, each shank 30 is clamped to the external surface 24 of the heating module 10 at at least one point along its extension between the upper end 32 and the lower end 34 of the heating zone 16. A clamp 40 may be pressed into a heating module's support structure 20 and / or insulation material 22, such as to a depth of up to 20 cm, 10 cm, up to 5 cm, up to 3 cm, up to 2 cm or up to 1 cm.

[0112] According to embodiments, an external surface 24 of a heating module 10 or its support structure 20 or its insulation material 22 may comprise a cavity or opening for receiving at least one clamp 40.

[0113] Figure 4 schematically shows a cross section of a polyhedral heating module 10 according to embodiments of the invention. Figure 4 shows only one shank 30 of at least one heating element 12 clamped to an external surface 24 of the heating module's insulation material 22 for the sake of clarity. Each shank 30 is clamped at a distance, d, from the external surface 24 of the heating module 10 leaving its lower end unsecured.

[0114] The at least one heating element 12 may be arranged to form a plurality of heating zones 14, 16, 18 horizontally around the periphery of the heating module 10, one heating zone 14, 16, 18 on each side of the polyhedral heating element for example and / or at least one heating element 12 may be arranged to form a plurality of heating zones vertically along a longitudinal axis, A, of the heating module 10.

[0115] The external surface 24 of the heating module 10 has a hexagonal cross section but an external surface 24 of a heating module 10 according to the present invention may have any suitable cross-section, such as a circular or an elliptical cross section, or a polygonal cross section having any number of sides, such as three, four, five, six, seven, eight, nine, ten, eleven, twelve or more sides. Similarly, an external surface 24 of the support structure 20, an external surface 24 of the insulation material 22 or the at least one heating zone 14, 16, 18 may have any suitable cross-section, such as a circular or an elliptical cross section, or a polygonal cross section having any number of sides, such as three, four, five, six, seven, eight, nine, ten, eleven, twelve or more sides.

[0116] The cross section of a heating module 10 need not necessarily have sides of the same length, or equal interior angles.

[0117] The heating module 10 comprises a support structure 20, such as a support structure 20 comprising a central rod and a plurality of hexagonal plates which are connected to insulation material 22.

[0118] Figure 4 shows only one shank 30 of at least one heating element 12 that has been arranged to form at least one heating zone 14, 16, 18. Each shank 30 is clamped to an external surface 24 of the insultation material 22, which constitutes an external surface of the heating module 10, leaving its lower end unsecured.

[0119] Figure 5 schematically shows a cross section of a heating module 10 having an elliptical support structure 20. Figure 5 shows only one shank 30 of at least one heating element 12 for the sake of clarity. Each shank 30 is clamped to an external surface 24 of the support structure 20, which constitutes an external surface 24 of the heating module 10, leaving the lower end of each shank 30 is unsecured.

[0120] Figure 6 schematically shows a plan view of a heat treatment apparatus 42 according to embodiments of the invention. The heat treatment apparatus 42 comprises a compartment 44 configured to receive at least one object that is to be heat-treated and four cylindrical heat modules 10 suspended inside the compartment 44. At least one heating zone 14, 16, 18 may be configured to extend around one or more sectors of the circumference of an external wall 24 of each heating module 10 so as to radiate heat at one or more desired radiation angles.

[0121] A heating module 10 according to the present invention may be configured to heat different parts of a compartment 44, or different compartments 44 of heat treatment apparatus 42, to different temperatures by independently controlling individual heating zones 14, 16, 18, or adjusting the electric power supplied to one or more specific heating zones 14, 16, 18.

[0122] According to embodiments, the shape of an external surface 24 of a heating module 10 is adapted to conform to the geometry of a surface of an object that is to be heat treated in a heat treatment apparatus 42 so that a homogeneous irradiation of the surface of the object may be achieved.

[0123] Figure 7 schematically shows a heat treatment apparatus 42 according to an embodiment of the invention which comprises a compartment 44 configured to receive at least one object that is to be heat-treated. The heat treatment apparatus 42 comprises an omnidirectional heating module 10 having an elliptical external surface 24. The compartment 44 surrounds the heating module 10.

[0124] The perimeter of an elliptical external surface 24 provides a larger surface area for at least one heating element 14, 16, 18 compared to a circular external surface with a circumference of the same magnitude. A longer conducting path (i.e. a greater length of the at least one heating element 12) may therefore be provided on an elliptical external surface 24 having a particular perimeter than on a circular external surface having the same circumference so more electrical power will be converted to heat. An elliptical external surface 24 may therefore be used to increase the power density (the heat output per unit area) of a heating module 10. Additionally, in restricted spaces, such as in a small heat treatment apparatus 42, using a heating module 10 having an elliptical external surface 24 will not significantly increase the overall size of the heating module 10.

[0125] A heating module 10 or a heat treatment apparatus 42 according to any of the embodiments of the present invention may be used to achieve a heating element temperature of at least 1200°C, or at least 1300°C, or at least 1400°C, or at least 1500°C, or at least 1600°C, or at least 1700°C, or at least 1800°C, or at least 1900°C.

[0126] Figure 8 schematically shows a perspective view of an omnidirectional cylindrical heating module 10. The embodiment of Figure 8 resembles in much the embodiment of Figures 1 to 3. Accordingly, in the following is reference also made to the discussion of Figures 1 to 3.

[0127] Again, the heating module 10 comprises at least one heating element 12. The at least one heating element 12 is arranged to form a plurality of cylindrical heating zones 14, 16, 18. In the illustrated example of Figure 8, the heating module 10 comprises two cylindrical heating zones 14, 16 arranged longitudinally at two vertical levels along the longitudinal axis A.

[0128] Alternatively, the heating module 10 may comprise more than two cylindrical heating zones 14, 16 arranged longitudinally at vertical levels along the longitudinal axis A. For instance, the heating module 10 may comprise three cylindrical heating zones 14, 16, 18 as shown in Figure 1 or more than three heating zones, such as four, five, or six heating zones.

[0129] Again, the heating module 10 comprises a cylindrical support structure 20 located radially inwards of the cylindrical heating zones 14, 16.

[0130] As discussed above, the heating module 10 comprises a plurality of terminals 26. In the illustrated example, there are provided four terminals 26, two each to / from each of the heating zones 14, 16.

[0131] The terminals 26 leading to / from the lower heating zone 16 of the heating element 12 extend through the upper heating zone 14. For this purpose, the shanks 30 of the upper heating zone 14 are not arranged around the full circumference of the heating module 10. A circumferential gap G is provided in the upper heating zone 14 for the terminals 26 of the lower heating zone 16 to extend along the upper heating zone 14 for connection to the lower heating zone 16.

[0132] More generally phrased : A circumferential gap G is provided in a higher level heating zone 14 for the terminals 26 of a lower level heating zone 16 to extend along the higher level heating zone 14 in the circumferential gap G for connection to the lower level heating zone 16, wherein the higher and lower levels relate to the longitudinal axis A and its vertical extension.

[0133] Accordingly, this principle may be applied in the embodiment of Figures 1 to 3 comprising three heating zones 14, 16, 18 for terminals 26 to extend along the upper and mid-level heating zones 14, 16, to the lowermost level heating zone 18, as well as for heating modules comprising a heating element 12 with more than three vertically arranged heating zones 14, 16, 18.

[0134] Alternative ways of leading the terminals 26 to / from lower level heating zones 16, 18 may be used, such as leading the terminals 26 within a central aperture of the support structure 20. As discussed above, each terminal 26 comprises a first end 46 and a second end 28. The first end 46 is configured to be connected to a heating zone 14, 16, e.g. by welding.

[0135] Figure 9 schematically shows an enlarged view of an upper end 32 of the lower heating zone 16 of the heating module 10 shown in Figure 8.

[0136] In Figure 9, the first ends 46 of the terminals 26 leading to / from the lower heating zone 16 are clearly shown.

[0137] The first end 46 of each terminal 26 is secured to the external surface 24 of the heating module 10. The first end 46 of each terminal 26 is secured relative to the external surface 24 in at least one direction along the longitudinal axis A of the heating module 10. Thus, thermal elongation of the terminal 26 is directed upwardly, such that the shanks 30 are not subjected to deformation by the terminals 26.

[0138] Any suitable fastening device can be used to achieve the securing of the first end 46 of each terminal 26 along the longitudinal axis A. Such a fastening device may be combined with a suitably devised first end 46 of the relevant terminal 26. That is, the first end 46 may be formed such that it engages with the fastening device.

[0139] In the embodiment of Figures 8 and 9, the first ends 46 of the terminals 26 leading to / from the lower heating zone 16 are secured to the external surface 24 of the heating module 10 via fastening devices comprising clamps 40' in a similar manner to the shanks 30 of the heating zones 14, 16. Since each of the terminals 26 has a larger diameter than the shanks 30, to which the terminals 26 connect, the first ends 46 of the terminals 26 include a diameter reduction in the transition to the relevant shanks 30. A tight fit between the clamp 40' and the first end 46 of a terminal 26 at a position where its diameter is reduced or at the shank 30, ensures that the terminal 26 cannot move downwardly. Thus, a thermal elongation of the terminal 26 is forced upwardly, where it does not affect the shank 30 and where measures can be arranged for accommodating the thermal elongation.

[0140] As discussed above, with reference to Figure 3, each shank 30 is clamped to the external surface 24 of the heating module 10 at an upper end of the shank 30 using a clamp 40.

[0141] The clamps 40' securing the first ends 46 of the terminals 26 to the external surface 24 are positioned at a vertical level proximate that of the clamps 40 clamping the upper ends of the shanks 30 to the external surface 24. For instance, the clamps 40' related to the first ends 46 of the terminals 26 may be arranged within + / - 10% of a length of the shanks 30 from the clamps 40 related to the upper ends of the shanks 30. In this manner, the shanks 30 which are connected to the terminals 26 will have approximately the same length as the other shanks 30, which ensures similar thermal elongation of each of all of the shanks 30.

[0142] Figure 10 schematically shows a partly exploded side view of a cylindrical heating module 10. The heating module 10 is a heating module 10 as discussed above with reference to any of Figures 1 to 9. Accordingly, in the following reference is also made to the discussions of Figures 1 to 9.

[0143] Figure 10 is presented primarily to illustrate an example of how a support of the herein discussed heating module 10 may be devised. Accordingly, inter alia the heating element 12 has been omitted in Figure 10.

[0144] The support structure 20 of the heating module 10 comprises one section 20', 20" for each heating zone 14, 16 of the heating element 12 of the heating module 10. In Figure 10, the sections 20', 20" are shown separated from each other. However, in a fully assembled state of the heating module 10, the sections 20', 20" may be arranged abutting against each other.

[0145] The heating module 10 comprises at least one rod or tube 48. In Figure 10, the at least one rod or tube 48 is indicated with broken lines. The support structure 20 is supported by the at least one rod or tube 48 arranged centrally within the support structure 20. In the illustrated example, the support structure 20 is supported by the centrally arranged at least one rod or tube 48.

[0146] Accordingly, each of the sections 20', 20" may be provided with a central aperture, through which the at least one rod or tube 48 may extend.

[0147] The heating module 10 comprising a disc or a plate 50. The support structure 20 is supported by the disc or the plate 50 and / or a pin 52.

[0148] According to some embodiments, such as in the illustrated embodiment, the at least one rod or tube 48 is connected to the disc or the plate 50 and / or the pin 52. In this manner, the support structure 20 may be supported by the at least one rod or tube 48 via the disc or plate 50 and / or the pin 52. As indicated in Figure 10, the support structure 20 is supported by a lowermost disc or plate 50 and / or a pin 52, which in turn is connected to the at least one rod or tube 48. Such a disc or plate 50 and / or a pin 52 may support all sections 20', 20''of the support structure 20. Alternatively, one or more further discs or plates 50' and / or pins 52may be provided for supporting at least one of the sections 20'. Also, such one or more further discs or plates 50' and / or pins 52may be connected to the at least one rod or tube 48.

[0149] At least one heating one heating module 10 according to any of the embodiments of the invention may be manufactured by providing a support structure 20, optionally comprising insulation material 22, and arranging at least one heating element 12 comprising ceramic material to form at least one heating zone 14, 16, 18 which comprises a plurality of shanks 30. The method comprises arranging each shank 30 to extend between an upper end of a heating zone 14, 16, 18 and a lower end 34 of a heating zone 14, 16, 18 during operation and connecting each shank 30 to at least one adjacent shank 30.

[0150] The method also comprises mounting the at least one heating zone 14, 16, 18 on an external surface 24 of the heating module 10, i.e. an external surface of the support structure 20 and / or an external surface of the insulation material 22 so that the at least one heating zone 14, 16, 18 will radiate heat outwards from the heating module 10 in a diverging manner during operation. The method further comprises clamping each shank 30 to the external surface 24 of the heating module 10, using at least one clamp, and leaving the lower end 34 of each shank 30 unsecured. The at least one heating zone 14, 16, 18 will thereby be secured in position during operation while the lower end 34 of the at least one heating zone 14, 16, 18 will be permitted to move vertically downwards during operation.

[0151] Such a method may also be used when manufacturing a heat treatment apparatus according to any of the embodiments of the invention.

[0152] Options and examples for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all options and examples for all other aspects, features and parameters of the invention. For example, any feature disclosed with respect to the heating module or heat treatment apparatus may be regarded as having been disclosed in the method for manufacturing a heating module or a heat treatment apparatus and vice versa.

Claims

Claims1. A heating module (10) comprising at least one heating element (12) configured to convert electric energy into heat during operation, wherein a longitudinal axis (A) of the heating module (10) extends in a vertical direction during operation, whereby the at least one heating element (12) comprises ceramic material, and is arranged to form at least one heating zone (14, 16, 18) comprising a plurality of shanks (30), whereby each shank (30) is connected to at least one adjacent shank (30) and extends between an upper end of a heating zone (14, 16, 18) and a lower end (34) of a heating zone (14, 16, 18) during operation, the at least one heating zone (14, 16, 18) is mounted on an external surface (24) of the heating module (10), and configured to radiate heat outwards from the heating module (10) in a diverging manner during operation, wherein the at least one heating zone (14, 16, 18) is configured to extend at least 270° around a circumference of the external surface (24) of the heating module (10) each shank (30) is clamped to the external surface (24) of the heating module (10) and the lower end (34) of each shank (30) is unsecured, thereby securing the at least one heating zone (14, 16, 18) in position while permitting a lower end (34) of the at least one heating zone (14, 16, 18) to move vertically downwards during operation), and wherein the at least one heating element (12) is arranged to form a plurality of said heating zones (14, 16, 18), and the plurality of heating zones (14, 16, 18) is arranged longitudinally at a plurality of vertical levels during operation.

2. The heating module (10) according to claim 1, wherein the heating module (10) comprises a support structure (20), and optionally insulation material (22), whereby the at least one heating zone (14, 16, 18) is mounted on an external surface (24) of the support structure (20) and / or on an external surface (24) of the insulation material (22).

3. The heating module (10) according to claim 2, comprising at least one rod or tube (48), wherein the support structure (20) is supported by the at least one rod or tube (48) arranged centrally.

4. The heating module (10) according to claim2 or 3, comprising a disc or a plate (50) and / or a pin (52), wherein the support structure (20) is supported by the disc or the plate (50) and / or the pin (52).

5. The heating module (10) according to claim 3 and 4, wherein the at least one rod or tube (48) is connected to the disc or the plate (50) and / or the pin (52).

6. The heating module (10) according to any preceding claim, wherein each heating zone (14, 16, 18) has a vertical extension within a range of 0.3 - 1.5 m.

7. The heating module (10) according to any preceding claim, wherein each shank (30) is clamped to the external surface (24) of the heating module (10) at an upper end of the shank (30).

8. The heating module (10) according to any preceding claim, comprising at least two terminals (26), wherein each terminal comprises a first end (46) that is configured to be connected to the at least one heating zone (14, 16, 18), and a second end (28) that is configured to be connected to an electric power source or an adjacent terminal (26) and wherein at least one of the second end (28) of the at least two terminals (26) of the heating module (10) is configured to be connected to the electrical power source.

9. The heating module (10) according to claim 8, wherein the first end (46) of each terminal (26) is secured to the external surface (24) of the heating module (10) and relative to the external surface (24) in at least one direction along the longitudinal axis (A).

10. The heating module (10) according to any preceding claim, wherein the at least one heating element (12) and / or the at least two terminals (26) comprises one or more of the following ceramic materials: a silicide, molybdenum disilicide (MoSi2), molybdenum disilicide alloyed with tungsten (W), chromium (Cr) or aluminium (Al), molybdenum disilicide containing an oxide..

11. The heating module (10) according to any preceding claim, wherein the at least one heating element (12) is arranged to form a plurality of alternating peaks and valleys, such as a plurality of alternating U-shaped peaks and valleys, or a zig-zag pattern, or a spiral, or a porcupine design, or a loop.

12. The heating module (10) according to any preceding claim, wherein at least one of the following components has a circular or elliptical or polygonal cross section: an external surface (24) of the heating module (10), an external surface (24) of the support structure (20), an external surface (24) of the insulation material (22) or the at least one heating zone (14, 16, 18).

13. The heating module (10) according to any preceding claim, wherein each shank (30)is clamped at a distance, d, from the external surface (24) of the heating module (10).

14. The heating module (10) according to any one of claims 8 - 10, wherein the least one heating element (12) has a diameter, D, and the heating module (10) comprises at least one of the following : at least two terminals (26) having a diameter of 2D to 3D, a shank (30) centre-to-centre distance, a, where 2D<a<10D, a distance between heating zones (14, 16, 18) arranged at a plurality of vertical levels of A, where 2D<A<20D, a distance between clamps > 4D.

15. A heat treatment apparatus (42) comprising at least one compartment (44) configured to receive at least one object that is to be heat-treated, wherein the heat treatment apparatus (42) comprises at least one heating module (10) according to any preceding claim, and optionally, in that the at least one compartment (44) at least partly surrounds the at least one heating module (10).

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