WO2024256949A1 - Compartmentalised immersion heater comprising electrically insulating ceramic powder - Google Patents

Compartmentalised immersion heater comprising electrically insulating ceramic powder Download PDF

Info

Publication number
WO2024256949A1
WO2024256949A1 PCT/IB2024/055653 IB2024055653W WO2024256949A1 WO 2024256949 A1 WO2024256949 A1 WO 2024256949A1 IB 2024055653 W IB2024055653 W IB 2024055653W WO 2024256949 A1 WO2024256949 A1 WO 2024256949A1
Authority
WO
WIPO (PCT)
Prior art keywords
immersion heater
sheath
compartment
wall
electrically insulating
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2024/055653
Other languages
French (fr)
Inventor
Guillaume LEVACHER
Matthias JIMENEZ Y SUSPERREGUI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Lethiguel SAS
Original Assignee
Lethiguel SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lethiguel SAS filed Critical Lethiguel SAS
Priority to EP24735311.3A priority Critical patent/EP4724221A1/en
Priority to CN202480038555.7A priority patent/CN121285437A/en
Publication of WO2024256949A1 publication Critical patent/WO2024256949A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D1/00—Treatment of fused masses in the ladle or the supply runners before casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/005—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like with heating or cooling means
    • B22D41/01—Heating means
    • B22D41/015—Heating means with external heating, i.e. the heat source not being a part of the ladle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/02—Ohmic resistance heating
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/78—Heating arrangements specially adapted for immersion heating
    • H05B3/82—Fixedly-mounted immersion heaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D99/0001—Heating elements or systems
    • F27D99/0006—Electric heating elements or system
    • F27D2099/0008—Resistor heating
    • F27D2099/0011—The resistor heats a radiant tube or surface
    • F27D2099/0013—The resistor heats a radiant tube or surface immersed in the charge

Definitions

  • the present invention relates to the field of foundry equipment and relates in particular to the foundry of non-ferrous metals having a relatively low melting point, typically below 1100°C.
  • the invention relates to an electric immersion heater for maintaining a previously melted metal bath in the liquid state or for melting a batch of solid metal, in particular alloys or non-alloyed metals of aluminum, magnesium or zinc.
  • an electric immersion heater is an electrical device which comprises a heating zone intended to be placed in contact with a bath of liquid metal to be heated, and a non-heating zone making it possible to make the connection between the heating zone and an electrical power supply unit.
  • an immersion heater In a foundry workshop, the most common use of an immersion heater is to maintain the temperature of a molten metal, previously melted using a gas furnace for example. For example, this temperature maintenance can be done in a liquid metal treatment ladle, during degassing or filtration of the liquid metal. According to a more recent application, designed by the applicant company, an immersion heater can be used to melt metal in the solid state and possibly to maintain the temperature of the molten metal thus obtained.
  • Immersion heaters for heating a bath of liquid metal have been known for decades, for example from GB 1 027 163, FR 2 720 888, they generally comprise one or more heating elements placed in a cylindrical sheath which separates them from the bath which they are to heat.
  • the sheath can be made of inert ceramic material, for example silicon nitride, boron nitride, SiAlON, silicon carbide.
  • the heating element can be made in the form of a heating ceramic, for example SiC, as is known from WO 2005/060314, or graphite, as described in FR 2 559 886 and FR 2 622 382.
  • Immersion heaters are also known for heating a bath of liquid metal, the tubular sheath of which comprises a plurality of metal heating elements which are embedded in an electrofused magnesia powder, which is an electrical insulator and has suitable thermal conductivity.
  • the immersion heaters which are currently on the market use this principle.
  • an immersion heater usually comprises an inert tubular sheath which surrounds a core comprising electrically insulating ceramic powder, for example electrofused magnesia, in which the heating elements of the immersion heater and the electrical supply lines necessary for the operation of these heating elements.
  • Electrically insulating ceramic powder has a very high production cost. Consequently, increasing the volume of the immersion heater in order to position more heating elements or heating elements of larger size and power in said immersion heater induces a cost, associated with the necessary electrically insulating ceramic powder, which is too high. We are therefore looking for an alternative way to reduce the cost of immersion heaters, without reducing their quality and longevity.
  • the present invention aims to remedy the limitations described above and in particular to provide an immersion heater offering increased heating capacity, while limiting the cost associated with this increase in power.
  • the invention aims at an immersion heater configured to be placed in contact with a material to be heated, in particular a molten non-ferrous metal, which comprises:
  • sheath delimiting a first compartment at least partly filled with electrically insulating ceramic powder, said sheath being configured to be placed in contact with the material to be heated,
  • the second compartment is filled at least in part with an inert material.
  • an immersion heater comprising a second solidly empty compartment
  • This thermal draft phenomenon occurs because the temperature difference between the bottom of the immersion heater with its resistors between 800°C and 1100°C and the top of the immersion heater which causes an air flow.
  • the hot air whose density and pressure are lower than those of cold air, rises in the tube.
  • the addition in the second compartment of an inert material, and in particular of a refractory ceramic insulator makes it possible to limit this thermal draft effect.
  • the inert material at least partially filling the second compartment delimited by the wall is a refractory ceramic insulating material. Said material may be of the flexible type, in a machined block or vacuum-molded.
  • the inert material at least partially filling the second compartment delimited by the wall comprises high temperature resistant fibers.
  • these high temperature resistant fibers are polycrystalline mullite fibers or silico-aluminous fibers.
  • the second compartment delimited by the wall is partly filled with an inert material and remains partly empty of solid material.
  • the second compartment delimited by the wall is filled at least partly with an inert gas which may be argon or another noble gas.
  • the second compartment is at least 30% by volume filled with an inert material, the remaining volume of the second compartment being left empty of solid material. In other embodiments, the second compartment is at least 40%, 60%, 80% or 90% filled with an inert material.
  • An electric immersion heater comprises a heating zone, and a non-heating zone for connecting the heating zone to a support of the immersion heater connected by means of an electrical supply.
  • the heating zone of the immersion heater is located on the lower part of the immersion heater, it comprises a plurality of heating elements, usually electrical resistors, brought to a high temperature by the passage of an electric current.
  • the part of the second compartment corresponding in height to the heating zone of the immersion heater is filled with inert material and the part of the second compartment corresponding in height to the non-heating zone of the immersion heater is left empty of solid material.
  • the immersion heater comprises at least one thermocouple type temperature sensor.
  • the at least one thermocouple is positioned in the first compartment of the immersion heater and more preferably in the heating zone of the immersion heater.
  • the at least one thermocouple is arranged in the electrically insulating ceramic powder.
  • the temperature sensor is protected by a glove finger.
  • the electrically insulating ceramic powder is selected from zinc oxide powder, alumina powder, magnesium oxide [magnesia] powder or boron nitride powder. It advantageously has good thermal conductivity.
  • the wall disposed inside the sheath and delimiting a compartment filled at least in part with an insulating material is formed at least in part from a ceramic material.
  • the wall can be formed from a material of comparatively low cost compared to the cost of electrically insulating ceramic powder, while exhibiting sufficient mechanical strength and thermal resistance characteristics.
  • the wall is formed from a high performance alloy, preferably a nickel-based alloy exhibiting low expansion at 1100°C.
  • the wall is formed from an alloy selected from Inconel alloys or CMSX single-crystal alloys.
  • a high-performance alloy or superalloy is a metal alloy having excellent mechanical strength and good creep resistance at high temperature, good surface stability and good resistance to corrosion and oxidation.
  • the sheath has a circular section.
  • the sheath has an external diameter greater than or equal to 50 millimeters, preferably greater than 75 mm, more preferably greater than 95 mm, and even more preferably greater than 115 mm.
  • the immersion heater has sufficient dimensions to include more heating elements or larger heating elements.
  • the wall is a tube of circular section.
  • the center of the circular section sheath and the center of the circular section wall are substantially identical, so that the first compartment, formed between the sheath and the wall, and intended to be filled at least in part with electrically insulating ceramic powder, has an annular section.
  • the heating elements can be arranged in said first compartment of annular section. The heating elements thus positioned are close to the sheath, thus allowing better diffusion of heat towards the sheath and indirectly towards the material to be heated.
  • the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath and in which the immersion heater comprises at least 15 turns, preferably at least 20 turns, preferably at least 20 turns, preferably at least 25 turns, preferably at least 30 turns.
  • the immersion heater comprises 36 turns.
  • a coil is a plurality of heating resistors supplied by the same current supplies and forming a substantially linear assembly arranged longitudinally in the immersion heater, preferably close to the sheath.
  • the immersion heater object of the invention is particularly distinguished from known immersion heaters in that the diameter of the first compartment delimited by the sheath can be increased in order to accommodate more heating elements or larger heating elements.
  • the immersion heater comprises 16, 24, 32 or 36 turns.
  • the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath and in which said turns are positioned close to the inner periphery of the sheath.
  • the turns thus positioned are close to the sheath, thus allowing better diffusion of heat towards the sheath and indirectly towards the material to be heated.
  • the heating elements comprise electrical resistors comprising molybdenum or an alloy selected from an iron-chromium-aluminum alloy [FeCrAl], a nickel alloy and a chromium alloy.
  • the device according to the invention advantageously has a cylindrical shape and a coaxial and symmetrical structure with respect to the central axis.
  • the device has a different shape and/or structure, for example an orthogonal section or a section of variable diameter.
  • a second object of the invention is represented by a method of manufacturing an immersion heater according to any one of the embodiments of the invention, in which a sheath, a tubular wall, a plurality of heating elements and an electrically insulating powder are supplied, said tubular wall is placed inside said sheath, the heating elements are introduced into the first compartment between the sheath and the wall, then said first compartment is filled with electrically insulating powder in stages, at least certain stages, and preferably each filling stage, being followed by at least one tamping stage.
  • FIG. 1 represents, schematically and in axial section view, a first embodiment of an immersion heater according to the invention
  • Fig 2 represents, schematically and in cross-sectional view, the immersion heater object of the first embodiment
  • Figures 1 and 2 show a first particular embodiment of an immersion heater 100 according to the invention.
  • Figure 1 shows an axial sectional view of the immersion heater.
  • Figure 2 shows a cross-sectional view of the heating part of the immersion heater 100, along the section plane A-A, visible in Figure 1.
  • the immersion heater 100 is an electric immersion heater comprising a heating zone 101, and a non-heating zone 102 making it possible to make the connection between the heating zone and a support of the immersion heater 100 connected to an electrical power supply means 110.
  • the immersion heater 100 is intended to be positioned in a tank [not shown] containing metal to be heated.
  • the heating zone 102 of the immersion heater 100 is intended to be placed in contact with the metal, whether it is a molten metal to be maintained at temperature in order to keep it in the liquid state or a solid metal to be heated.
  • the heating zone 101 of the immersion heater 100 comprises a plurality of heating elements, 115, 116, brought to a high temperature by the passage of an electric current; this is a resistive heating.
  • each heating element comprises an electrical conductor, which is in contact with an electrically insulating material 130 capable of transmitting its heat to a sheath 120 [external sheath] forming the outermost layer of the body of the immersion heater 100, which in turn transmits the heat to the metal or alloy to be melted or maintained in the liquid state.
  • the mechanism for transmitting heat from the sheath of the immersion heater to the metal in the tank is most efficiently by conduction, when the immersion heater is immersed in liquid metal or when its sheath touches solid metal over a significant fraction of its surface. Outside of these areas of direct contact, the heat transfer between the sheath and the metal contained in the tank is radiative and/or convective.
  • the heat transfer from the heating element 115 to the sheath 120 and then to the material to be heated 90 is represented by the arrow 80, in FIGS. 1 and 2.
  • the immersion heater 100 is for example configured to maintain in the liquid state a metal 90 in liquid form comprising a non-ferrous metal or an alloy with base of a non-ferrous metal which has a melting temperature sufficiently low to be compatible with the use of an electric immersion heater.
  • the non-ferrous metal may be any metal or alloy having a melting temperature which does not exceed approximately 1100°C.
  • the base metal may for example be chosen from aluminum, zinc, magnesium, copper, tin, lead, lithium, silver.
  • the sheath 120 of the immersion heater 100 is preferably formed from boron nitride or silicon nitride. These refractory materials have a high heat resistance and are chemically inert, in addition to offering satisfactory mechanical resistance.
  • the sheath 120 delimits a first compartment 150 inside which the heating elements, 115, 116, of the immersion heater 100 are arranged.
  • Said first compartment 150 is at least partly filled with electrically insulating ceramic powder 130.
  • the electrically insulating ceramic powder 130 is a material selected for its electrical insulating characteristics, allowing direct contact with the electrical conductors of the heating element, and for its heat conductor characteristics.
  • the electrically insulating ceramic powder 130 must have excellent temperature resistance, it must not degrade over time, allowing an effective service life of the immersion heater typically ranging from one to several tens of months of continuous use. It advantageously has good thermal conductivity.
  • the electrically insulating ceramic powder 130 is an electrofused magnesia [magnesium oxide: MgO] powder.
  • the electrofused magnesia powder is manufactured by melting magnesium oxide at a temperature exceeding 3,000°C.
  • the electrically insulating ceramic powder is selected from a zinc oxide [ZnO] powder, an alumina [Al2O3] powder or a boron nitride powder.
  • the immersion heater 100 comprises at least one wall 140 delimiting a second closed compartment 145, distinct from the first compartment.
  • Said second compartment has the function of reducing the quantity of electrically insulating ceramic powder 130 necessary for the manufacture of the immersion heater 100 and thus of reducing the manufacturing cost.
  • the wall 140 is typically a tubular wall, its axial section is advantageously circular.
  • the wall 140 is formed of a material having sufficient mechanical strength and thermal resistance characteristics, without requiring good thermal conduction.
  • the wall 140 is formed of ceramic, for example alumina.
  • the wall 140 is formed of mullite or jcordierit [Mji]
  • the wall is formed of a high-performance alloy, preferably a nickel-based alloy having low expansion at 1100°C.
  • the wall is formed of an alloy chosen from Inconel alloys or CMSX monocrystalline alloys.
  • the second compartment 145 delimited by the wall 140 remains partly empty of solid material.
  • the part of the second compartment empty of solid material comprises gas which may be air.
  • the air is expelled in order to be replaced by an inert gas, unlikely to oxidize the wall, which may be for example argon or another noble gas.
  • the second compartment 145 is at least partly filled with an inert material in particulate form.
  • the inert material contained in the second compartment 145 makes it possible to prevent a thermal draft phenomenon.
  • the inert material can also exert a counter-pressure against the wall 140.
  • said inert material comprises high temperature resistance fibers, for example polycrystalline mullite fibers or silico-alumina fibers.
  • said inert material is an alumina powder.
  • the sheath 120 typically has a circular section.
  • the outer diameter of the sheath 120 is at least 55 millimeters [hereinafter abbreviated “mm”], preferably at least 75 mm.
  • the diameter of the sheath 120 is greater than 95 mm or greater than 115 mm. Increasing the diameter of the sheath 120 makes it possible to place a greater number of heating elements 115, 116 inside the immersion heater 100, which makes it possible to increase its thermal power.
  • the wall 140 is a tube of circular section also, forming a second compartment 145 of round section shape.
  • the first compartment 150 formed on the one hand by the sheath 120 and on the other hand by the wall 140 thus has an advantageous annular shape for the placement of the heating elements, 115, 116, as detailed in the following paragraph.
  • the tube forming the wall 140 is of constant diameter over the entire height of the immersion heater.
  • the immersion heater 100 shown in FIGS. 1 and 2 comprises sixteen heating elements, of which only the heating elements 115 and 116 are labeled in FIGS. 1 and 2.
  • the immersion heater 100 comprises at least 20 heating elements, preferably at least 30 heating elements.
  • the heating elements are positioned close to the inner periphery of the sheath 120 in order to allow better heat transfer to the latter.
  • the heating elements, 115, 116 are arranged in a circle concentric with the circle formed by the sheath 120. Any other arrangement and any other number of heating elements can be adopted without departing from the scope of the present invention.
  • the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath 120 and said turns are positioned close to the inner periphery of the sheath 120.
  • the heating elements 115, 116 comprise electrical resistors comprising molybdenum or an alloy chosen from an iron-chromium-aluminium alloy [FeCrAl], a nickel and chromium alloy.
  • the tubular wall 140 forms a compartment with a rectangular or polygonal cross-section, for example octagonal or hexagonal.
  • the second compartment 145 formed by the wall 140 does not have the same dimensions over the entire height of the immersion heater 100.
  • the second compartment 140 at a cross-section in the non-heating part of the immersion heater 100 has a smaller surface area than the surface area of the second compartment 140 at a cross-section in the non-heating part of the immersion heater 100.
  • the immersion heater comprises a first compartment at least partly filled with electrically insulating ceramic powder and a plurality of walls arranged inside the first compartment, each of said walls delimiting a compartment which can remain empty of solid material or which can be filled at least partly with an insulating material.
  • a sheath 120, a tubular wall 140, a plurality of heating elements 115, 116 and an electrically insulating powder 130 are supplied, said tubular wall 140 is placed inside said sheath 120, the electrical conductors are introduced into the first compartment 150 between the sheath 120 and the wall 140, then said first compartment 150 is filled with electrically insulating ceramic powder in stages, at least some filling steps (and preferably each filling step) being followed by at least one compaction step.
  • the powder is pressed using a tamping tool in the shape of an annular or ring section, capable of being inserted from above into the annular space formed by the first compartment 150.
  • a tamping tool in the shape of an annular or ring section, capable of being inserted from above into the annular space formed by the first compartment 150.
  • said first compartment is gradually filled with a dense, packed bed of electrically insulating ceramic powder, which ensures excellent thermal contact with the heating elements 115, 116.
  • each step of introducing the electrically insulating ceramic powder, or at least one of these steps, and preferably at least the last, is followed by a step of compaction by vibrating the sheath 150 and/or the tube 140.
  • said compaction tool is produced as a vibrocompaction tool.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Resistance Heating (AREA)

Abstract

The invention relates to an immersion heater (100) configured to be brought into contact with a material to be heated (90), in particular a molten non-ferrous metal, the immersion heater comprising: - a sheath (120) defining a first compartment (150) that is at least partially filled with electrically insulating powder (130), the sheath being configured to be brought into contact with the material to be heated; - a wall (140) arranged inside the first compartment (150) and defining at least one second compartment (145), this second compartment being at least partially filled with an inert material; - a plurality of heating elements (115, 116) arranged in the electrically insulating ceramic powder (130) between the sheath (120) and the wall (140).

Description

DESCRIPTION DESCRIPTION

THERMOPLONGEUR COMPARTIMENTÉ COMPORTANT DE LA POUDRE CÉRAMIQUE ÉLECTRIQUEMENT ISOLANTE COMPARTMENTAL IMMERSION HEATER WITH ELECTRICALLY INSULATING CERAMIC POWDER

DOMAINE TECHNIQUE DE L’INVENTION TECHNICAL FIELD OF THE INVENTION

[0001] La présente invention relève du domaine des équipements de fonderie et concerne surtout la fonderie des métaux non ferreux présentant un point de fusion relativement bas, typiquement au-dessous de 1100 °C. [0001] The present invention relates to the field of foundry equipment and relates in particular to the foundry of non-ferrous metals having a relatively low melting point, typically below 1100°C.

[0002] L’invention vise un thermoplongeur électrique pour maintenir à l’état liquide un bain de métal préalablement fondu ou pour fondre un lot de métal solide, notamment des alliages ou métaux non alliés d’aluminium, de magnésium ou de zinc. [0002] The invention relates to an electric immersion heater for maintaining a previously melted metal bath in the liquid state or for melting a batch of solid metal, in particular alloys or non-alloyed metals of aluminum, magnesium or zinc.

ÉTAT DE LA TECHNIQUE STATE OF THE ART

[0003] Dans le contexte des équipements de fonderie, on appelle thermoplongeur électrique un dispositif électrique qui comporte une zone chauffante destinée à être mise au contact d’un bain de métal liquide à chauffer, et une zone non chauffante permettant de faire le lien entre la zone chauffante et un boîtier d'alimentation électrique. [0003] In the context of foundry equipment, an electric immersion heater is an electrical device which comprises a heating zone intended to be placed in contact with a bath of liquid metal to be heated, and a non-heating zone making it possible to make the connection between the heating zone and an electrical power supply unit.

[0004] Dans un atelier de fonderie, l’utilisation la plus courante d’un thermoplongeur vise à maintenir en température un métal en fusion, préalablement fondu au moyen d’un four à gaz par exemple. À titre d’exemple, ce maintien en température peut se faire dans une poche de traitement de métal liquide, lors du dégazage ou de la filtration du métal liquide. Selon une application plus récente, conçue par la société requérante, un thermoplongeur peut être utilisé pour fondre du métal à l’état solide et éventuellement pour maintenir en température le métal en fusion ainsi obtenu. [0004] In a foundry workshop, the most common use of an immersion heater is to maintain the temperature of a molten metal, previously melted using a gas furnace for example. For example, this temperature maintenance can be done in a liquid metal treatment ladle, during degassing or filtration of the liquid metal. According to a more recent application, designed by the applicant company, an immersion heater can be used to melt metal in the solid state and possibly to maintain the temperature of the molten metal thus obtained.

[0005] Des thermoplongeurs destinés à chauffer un bain de métal liquide sont connus depuis des décennies, par exemple de GB 1 027 163, FR 2 720 888, ils comprennent en règle générale un ou plusieurs éléments chauffants placés dans une gaine cylindrique qui les séparent du bain qu’ils doivent chauffer. Comme enseigné par FR 2 699 038 la gaine peut être réalisée en en matériau céramique inerte, par exemple en nitrure de silicium, nitrure de bore, SiAlON, carbure de silicium. L’élément chauffant peut être réalisé sous la forme d’une céramique chauffante, en SiC par exemple, comme cela est connu de WO 2005/060314, ou en graphite, comme décrit dans FR 2 559 886 et FR 2 622 382. [0005] Immersion heaters for heating a bath of liquid metal have been known for decades, for example from GB 1 027 163, FR 2 720 888, they generally comprise one or more heating elements placed in a cylindrical sheath which separates them from the bath which they are to heat. As taught by FR 2 699 038 the sheath can be made of inert ceramic material, for example silicon nitride, boron nitride, SiAlON, silicon carbide. The heating element can be made in the form of a heating ceramic, for example SiC, as is known from WO 2005/060314, or graphite, as described in FR 2 559 886 and FR 2 622 382.

[0006] On connaît également des thermoplongeurs pour chauffer un bain de métal liquide dont la gaine tubulaire comprend une pluralité d’éléments chauffants métalliques qui sont noyés dans une poudre de magnésie électrofondue, qui est un isolant électrique et présente une conductivité thermique convenable. Les thermoplongeurs qui sont actuellement sur le marché utilisent ce principe. [0006] Immersion heaters are also known for heating a bath of liquid metal, the tubular sheath of which comprises a plurality of metal heating elements which are embedded in an electrofused magnesia powder, which is an electrical insulator and has suitable thermal conductivity. The immersion heaters which are currently on the market use this principle.

[0007] Dans un contexte d’électrification des méthodes industrielles et plus particulièrement des méthodes de fonderie, notamment en vue de limiter l’usage de moyens de chauffage plus traditionnels reposant sur l’usage d’énergie fossiles, il existe un besoin de dispositifs électriques fournissant une puissance électrique, et donc une capacité de chauffage, plus importante que celle offerte par les dispositifs actuels. [0007] In a context of electrification of industrial methods and more particularly of foundry methods, in particular with a view to limiting the use of more traditional heating means based on the use of fossil fuels, there is a need for electrical devices providing electrical power, and therefore a heating capacity, greater than that offered by current devices.

[0008] Afin de répondre à ce besoin, plusieurs thermoplongeurs actuellement disponibles peuvent être utilisés de concert dans un même bain. En fonction de la capacité de chauffage nécessaire à apporter à un four, autant de thermoplongeurs que nécessaires sont mobilisés. La durée de vie des gaines dans un bain de métal liquide étant limitée, ces thermoplongeurs doivent être remplacés régulièrement. L’augmentation de leur nombre engendre une augmentation à la fois du coût d’investissement et du coût de maintenance. L’alternative à la multiplication des thermoplongeurs serait de prévoir des thermoplongeurs de capacité et de taille plus importantes. Cependant, l’augmentation de la taille des thermoplongeurs se heurte à certaines difficultés d’ordre technique et économique. [0008] In order to meet this need, several immersion heaters currently available can be used together in the same bath. Depending on the heating capacity required to be provided to a furnace, as many immersion heaters as necessary are used. Since the service life of the sheaths in a liquid metal bath is limited, these immersion heaters must be replaced regularly. Increasing their number results in an increase in both the investment cost and the maintenance cost. The alternative to increasing the number of immersion heaters would be to provide immersion heaters of greater capacity and size. However, increasing the size of the immersion heaters comes up against certain technical and economic difficulties.

OBJETS DE L’INVENTION OBJECTS OF THE INVENTION

[0009] La société requérante a constaté qu’il n’était pas possible de produire à un prix raisonnable un thermoplongeur de forte puissance. En effet, cette augmentation de puissance est coûteuse en raison des matériaux employés dans la structure d’un thermoplongeur. Comme indiqué ci-dessus, un thermoplongeur comporte usuellement une gaine tubulaire inerte qui entoure un cœur comportant de la poudre céramique électriquement isolante, par exemple de la magnésie électrofondue, dans laquelle sont noyés les éléments chauffants du thermoplongeur ainsi que les conduites d’alimentation électriques nécessaires au fonctionnement de ces éléments chauffants. La poudre céramique électriquement isolante présente un coût de production très important. Par conséquent, l’augmentation du volume du thermoplongeur en vue de positionner dans ledit thermoplongeur davantage d’éléments chauffants ou des éléments chauffant de plus grandes taille et puissance induit un coût, associé à la poudre céramique électriquement isolante nécessaire, qui est trop important. On cherche donc une voie alternative pour diminuer le coût des thermoplongeurs, sans pour autant diminuer leur qualité et longévité. [0009] The applicant company found that it was not possible to produce a high-power immersion heater at a reasonable price. Indeed, this increase in power is expensive because of the materials used in the structure of an immersion heater. As indicated above, an immersion heater usually comprises an inert tubular sheath which surrounds a core comprising electrically insulating ceramic powder, for example electrofused magnesia, in which the heating elements of the immersion heater and the electrical supply lines necessary for the operation of these heating elements. Electrically insulating ceramic powder has a very high production cost. Consequently, increasing the volume of the immersion heater in order to position more heating elements or heating elements of larger size and power in said immersion heater induces a cost, associated with the necessary electrically insulating ceramic powder, which is too high. We are therefore looking for an alternative way to reduce the cost of immersion heaters, without reducing their quality and longevity.

[0010]Ainsi, la présente invention vise à remédier aux limitations décrites ci-avant et notamment à fournir un thermoplongeur offrant une capacité de chauffage augmentée, tout en limitant le coût associé à cette augmentation de puissance. [0010]Thus, the present invention aims to remedy the limitations described above and in particular to provide an immersion heater offering increased heating capacity, while limiting the cost associated with this increase in power.

[0011]À cet effet, selon un premier objet, l’invention vise un thermoplongeur configuré pour être mis en contact avec une matière à chauffer, notamment un métal non ferreux en fusion, qui comporte : [0011]To this end, according to a first object, the invention aims at an immersion heater configured to be placed in contact with a material to be heated, in particular a molten non-ferrous metal, which comprises:

- une gaine délimitant un premier compartiment au moins en partie rempli de poudre céramique électriquement isolante, ladite gaine étant configurée pour être mise en contact avec la matière à chauffer, - a sheath delimiting a first compartment at least partly filled with electrically insulating ceramic powder, said sheath being configured to be placed in contact with the material to be heated,

- une paroi disposée à l’intérieur dudit premier compartiment et délimitant au moins un deuxième compartiment, ce dernier étant au moins en partie rempli d’un matériau inerte, - a wall arranged inside said first compartment and delimiting at least a second compartment, the latter being at least partly filled with an inert material,

- une pluralité d’éléments chauffants disposés dans la poudre céramique électriquement isolante, entre ladite gaine et ladite paroi. - a plurality of heating elements arranged in the electrically insulating ceramic powder, between said sheath and said wall.

[0012] Grâce à ces dispositions, une partie du premier compartiment, délimité par la gaine, et qui, dans les thermoplongeurs connus de l’art antérieur, est habituellement rempli de poudre céramique électriquement isolante comporte à la place un matériau inerte ou un gaz dont le coût est bien moindre que le coût de la poudre céramique électriquement isolante. [0012] Thanks to these arrangements, a part of the first compartment, delimited by the sheath, and which, in the immersion heaters known from the prior art, is usually filled with electrically insulating ceramic powder, instead comprises an inert material or a gas whose cost is much lower than the cost of the electrically insulating ceramic powder.

[0013] Selon l’invention, le deuxième compartiment est rempli au moins en partie d’un matériau inerte. Les inventeurs ont découvert que la mise en œuvre d’un thermoplongeur comportant un deuxième compartiment vide de manière solide avait pour effet d’occasionner un phénomène de tirage thermique. Ce phénomène de tirage thermique se produit car la différence de température entre le bas du thermoplongeur avec ses résistances entre 800°C et 1100°C et le haut du thermoplongeur qui entraîne un flux d’air. L’air chaud, dont la densité et la pression sont plus faibles que celles de l’air froid, monte dans le tube. L’ajout dans le deuxième compartiment d’un matériau inerte, et tout particulièrement d’un isolant céramique réfractaire, permet de limiter cet effet de tirage thermique. [0014] Dans des modes de réalisation, le matériau inerte remplissant au moins en partie le deuxième compartiment délimité par la paroi est un matériau isolant céramique réfractaire. Ledit matériau peut être de type souple, en bloc usiné ou moulé sous vide [0013] According to the invention, the second compartment is filled at least in part with an inert material. The inventors have discovered that the implementation of an immersion heater comprising a second solidly empty compartment has the effect of causing a thermal draft phenomenon. This thermal draft phenomenon occurs because the temperature difference between the bottom of the immersion heater with its resistors between 800°C and 1100°C and the top of the immersion heater which causes an air flow. The hot air, whose density and pressure are lower than those of cold air, rises in the tube. The addition in the second compartment of an inert material, and in particular of a refractory ceramic insulator, makes it possible to limit this thermal draft effect. [0014] In embodiments, the inert material at least partially filling the second compartment delimited by the wall is a refractory ceramic insulating material. Said material may be of the flexible type, in a machined block or vacuum-molded.

[0015] Dans des modes de réalisation, le matériau inerte remplissant au moins en partie le deuxième compartiment délimité par la paroi comporte des fibres à haute tenue en température. Par exemple, ces fibres à haute tenue ne température sont des fibres poly-cristallines de mullite ou des fibres silico-alumineuses. [0015] In embodiments, the inert material at least partially filling the second compartment delimited by the wall comprises high temperature resistant fibers. For example, these high temperature resistant fibers are polycrystalline mullite fibers or silico-aluminous fibers.

[0016] Dans des modes de réalisation, le deuxième compartiment délimité par la paroi est en partie rempli d’un matériau inerte et reste en partie vide de matière solide. Avantageusement, le deuxième compartiment délimité par la paroi est rempli au moins en partie d’un gaz inerte qui peut être de l’argon ou un autre gaz noble. [0016] In embodiments, the second compartment delimited by the wall is partly filled with an inert material and remains partly empty of solid material. Advantageously, the second compartment delimited by the wall is filled at least partly with an inert gas which may be argon or another noble gas.

[0017] Dans des modes de réalisation, le deuxième compartiment est au moins rempli à hauteur de 30% en volume d’un matériau inerte, le volume restant du deuxième compartiment était laissé vide de matière solide. Dans d’autres modes de réalisation, le deuxième compartiment est au moins rempli à hauteur de 40%, à hauteur de 60%, à hauteur de 80% ou à hauteur de 90% d’un matériau inerte. [0017] In embodiments, the second compartment is at least 30% by volume filled with an inert material, the remaining volume of the second compartment being left empty of solid material. In other embodiments, the second compartment is at least 40%, 60%, 80% or 90% filled with an inert material.

[0018]Un thermoplongeur électrique comporte une zone chauffante, et une zone non chauffante permettant de faire le lien entre la zone chauffante et un support du thermoplongeur raccordé à moyen d’alimentation électrique. La zone chauffante du thermoplongeur se trouve sur la partie inférieure du thermoplongeur, elle comporte une pluralité d’éléments chauffants, habituellement des résistances électriques, portés à haute température par le passage d'un courant électrique. [0018]An electric immersion heater comprises a heating zone, and a non-heating zone for connecting the heating zone to a support of the immersion heater connected by means of an electrical supply. The heating zone of the immersion heater is located on the lower part of the immersion heater, it comprises a plurality of heating elements, usually electrical resistors, brought to a high temperature by the passage of an electric current.

[0019] Avantageusement, la partie du deuxième compartiment correspondant en hauteur à la zone chauffante du thermoplongeur est remplie de matériau inerte et la partie du deuxième compartiment correspondant en hauteur à la zone non chauffante du thermoplongeur est laissée vide de matière solide. [0019] Advantageously, the part of the second compartment corresponding in height to the heating zone of the immersion heater is filled with inert material and the part of the second compartment corresponding in height to the non-heating zone of the immersion heater is left empty of solid material.

[0020] Ces dispositions permettent d’obtenir l’effet de prévention de phénomène de tirage thermique, tout en limitant la quantité de matériau inerte nécessaires à la fabrication du thermoplongeur. [0020] These provisions make it possible to obtain the effect of preventing the phenomenon of thermal draft, while limiting the quantity of inert material necessary for the manufacture of the immersion heater.

[0021] Dans des modes de réalisation, le thermoplongeur comporte au moins un capteur de température de type thermocouple. Avantageusement, l’au moins un thermocouple est positionné dans le premier compartiment du thermoplongeur et plus préférentiellement dans la zone chauffante du thermoplongeur. [0022]Ainsi, l’au moins un thermocouple est disposé dans la poudre céramique électriquement isolante. Avantageusement, le capteur de température est protégé par un doigt de gant. [0021] In embodiments, the immersion heater comprises at least one thermocouple type temperature sensor. Advantageously, the at least one thermocouple is positioned in the first compartment of the immersion heater and more preferably in the heating zone of the immersion heater. [0022]Thus, the at least one thermocouple is arranged in the electrically insulating ceramic powder. Advantageously, the temperature sensor is protected by a glove finger.

[0023] Dans des modes de réalisation, la poudre céramique électriquement isolante est choisie parmi une poudre d’oxyde de zinc, une poudre d’alumine, une poudre d’oxyde de magnésium [magnésie) ou une poudre de nitrure de bore. Elle présente avantageusement une bonne conductivité thermique. [0023] In embodiments, the electrically insulating ceramic powder is selected from zinc oxide powder, alumina powder, magnesium oxide [magnesia] powder or boron nitride powder. It advantageously has good thermal conductivity.

[0024] Dans des modes de réalisation, la paroi disposée à l’intérieur de la gaine et délimitant un compartiment rempli au moins en partie d’un matériau isolant est formée au moins en partie d’un matériau céramique. [0024] In embodiments, the wall disposed inside the sheath and delimiting a compartment filled at least in part with an insulating material is formed at least in part from a ceramic material.

[0025] Grâce à ces dispositions, la paroi peut être formée d’un matériau de coût comparativement faible par rapport au coût de la poudre céramique électriquement isolante, tout en présentant des caractéristiques de résistance mécanique et de résistance thermique suffisante. [0025] By means of these arrangements, the wall can be formed from a material of comparatively low cost compared to the cost of electrically insulating ceramic powder, while exhibiting sufficient mechanical strength and thermal resistance characteristics.

[0026] Dans des modes de réalisation, la paroi est formée d’un alliage haute performance, préférentiellement un alliage à base de nickel présentant une faible dilatation à 1100°C. Par exemple, la paroi est formée d’un alliage choisi parmi les alliages Inconel ou les alliages monocristallins CMSX. [0026] In embodiments, the wall is formed from a high performance alloy, preferably a nickel-based alloy exhibiting low expansion at 1100°C. For example, the wall is formed from an alloy selected from Inconel alloys or CMSX single-crystal alloys.

[0027] On désigne par alliage à haute performance ou superalliage un alliage métallique présentant une excellente résistance mécanique et une bonne résistance au fluage à haute température, une bonne stabilité surfacique ainsi qu'une bonne résistance à la corrosion et à l'oxydation. [0027] A high-performance alloy or superalloy is a metal alloy having excellent mechanical strength and good creep resistance at high temperature, good surface stability and good resistance to corrosion and oxidation.

[0028] Dans des modes de réalisation, la gaine présente une section circulaire. Avantageusement, la gaine présente un diamètre extérieur supérieur ou égal à 50 millimètres, de préférence supérieur à 75 mm, plus préférentiellement supérieur à 95 mm, et encore plus préférentiellement supérieur à 115 mm. [0028] In embodiments, the sheath has a circular section. Advantageously, the sheath has an external diameter greater than or equal to 50 millimeters, preferably greater than 75 mm, more preferably greater than 95 mm, and even more preferably greater than 115 mm.

[0029] Grâce à ces dispositions, le thermoplongeur présente des dimensions suffisantes pour comporter d’avantage d’éléments chauffants ou des éléments chauffant de plus grande taille. [0029] Thanks to these provisions, the immersion heater has sufficient dimensions to include more heating elements or larger heating elements.

[0030] Dans des modes de réalisation, la paroi est un tube de section circulaire. Avantageusement, le centre de la gaine de section circulaire et le centre de la paroi de section circulaire sont sensiblement identiques, de sorte que le premier compartiment, formé entre la gaine et la paroi, et destiné à être rempli au moins en partie de poudre céramique électriquement isolante, présente une section annulaire. [0031] Grâce à ces dispositions, les éléments chauffants peuvent être disposés dans ledit premier compartiment de section annulaire. Les éléments chauffants ainsi positionnés se trouvent proches de la gaine, permettant ainsi une meilleure diffusion de la chaleur vers la gaine et indirectement vers la matière à chauffer. [0030] In embodiments, the wall is a tube of circular section. Advantageously, the center of the circular section sheath and the center of the circular section wall are substantially identical, so that the first compartment, formed between the sheath and the wall, and intended to be filled at least in part with electrically insulating ceramic powder, has an annular section. [0031] Thanks to these arrangements, the heating elements can be arranged in said first compartment of annular section. The heating elements thus positioned are close to the sheath, thus allowing better diffusion of heat towards the sheath and indirectly towards the material to be heated.

[0032] Dans des modes de réalisation, les éléments chauffants sont arrangés en spires sensiblement droites disposées sensiblement parallèles à un axe parcourant le centre de la gaine et dans lequel le thermoplongeur comporte au moins 15 spires, préférentiellement au moins 20 spires, préférentiellement au moins 20 spires, préférentiellement au moins 25 spires, préférentiellement au moins 30 spires. Par exemple, le thermoplongeur comporte 36 spires. [0032] In embodiments, the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath and in which the immersion heater comprises at least 15 turns, preferably at least 20 turns, preferably at least 20 turns, preferably at least 25 turns, preferably at least 30 turns. For example, the immersion heater comprises 36 turns.

[0033] On appelle spire une pluralité de résistances chauffantes alimentées par les mêmes amenées de courant et formant un ensemble sensiblement linéaire disposée longitudinalement dans le thermoplongeur, préférentiellement à proximité de la gaine. [0033] A coil is a plurality of heating resistors supplied by the same current supplies and forming a substantially linear assembly arranged longitudinally in the immersion heater, preferably close to the sheath.

[0034] Comme détaillé précédemment, le thermoplongeur objet de l’invention se distingue tout particulièrement des thermoplongeurs connus en ce que le diamètre du premier compartiment délimité par la gaine peut être augmenté afin d’accommoder d’avantage d’éléments chauffant ou des éléments chauffants de plus grande taille. Ainsi, avantageusement, le thermoplongeur comporte 16, 24, 32 ou 36 spires. [0034] As detailed above, the immersion heater object of the invention is particularly distinguished from known immersion heaters in that the diameter of the first compartment delimited by the sheath can be increased in order to accommodate more heating elements or larger heating elements. Thus, advantageously, the immersion heater comprises 16, 24, 32 or 36 turns.

[0035] Dans des modes de réalisation, les éléments chauffants sont arrangés en spires sensiblement droites disposées sensiblement parallèles à un axe parcourant le centre de la gaine et dans lequel lesdites spires sont positionnées à proximité du pourtour intérieur de la gaine. [0035] In embodiments, the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath and in which said turns are positioned close to the inner periphery of the sheath.

[0036] Grâce à ces dispositions, les spires ainsi positionnées se trouvent proches de la gaine, permettant ainsi une meilleure diffusion de la chaleur vers la gaine et indirectement vers la matière à chauffer. [0036] Thanks to these arrangements, the turns thus positioned are close to the sheath, thus allowing better diffusion of heat towards the sheath and indirectly towards the material to be heated.

[0037] Dans des modes de réalisation, les éléments chauffants comportent des résistances électriques comportant du molybdène ou un alliage choisi parmi un alliage de fer- chrome-aluminium [FeCrAl], un alliage de nickel et un alliage de chrome. [0037] In embodiments, the heating elements comprise electrical resistors comprising molybdenum or an alloy selected from an iron-chromium-aluminum alloy [FeCrAl], a nickel alloy and a chromium alloy.

[0038] Abstraction faite des éléments chauffants et des éléments de connexion électrique vers l’extérieur, le dispositif selon l’invention présente avantageusement une forme cylindrique et une structure coaxiale et symétrique par rapport à l’axe central. On peut envisager également d’autres modes de réalisation dans lesquels le dispositif présente une forme et/ou une structure différente, par exemple une section orthogonale ou une section de diamètre variable. [0039] Un deuxième objet de l’invention est représenté par un procédé de fabrication d’un thermoplongeur selon l’un quelconque des modes de réalisation de l’invention, dans lequel on approvisionne un gaine, une paroi tubulaire, une pluralité d’éléments chauffants et une poudre électriquement isolante, on place ladite paroi tubulaire à l’intérieur de ladite gaine, on introduit les éléments chauffants dans le premier compartiment entre la gaine et la paroi, puis on remplit ledit premier compartiment de poudre électriquement isolante par étapes, au moins certaines étapes, et de préférence chaque étape, de remplissage étant suiviefs] par au moins une étape de tassement. [0038] Apart from the heating elements and the electrical connection elements to the outside, the device according to the invention advantageously has a cylindrical shape and a coaxial and symmetrical structure with respect to the central axis. Other embodiments can also be envisaged in which the device has a different shape and/or structure, for example an orthogonal section or a section of variable diameter. [0039] A second object of the invention is represented by a method of manufacturing an immersion heater according to any one of the embodiments of the invention, in which a sheath, a tubular wall, a plurality of heating elements and an electrically insulating powder are supplied, said tubular wall is placed inside said sheath, the heating elements are introduced into the first compartment between the sheath and the wall, then said first compartment is filled with electrically insulating powder in stages, at least certain stages, and preferably each filling stage, being followed by at least one tamping stage.

BRÈVE DESCRIPTION DES FIGURES BRIEF DESCRIPTION OF THE FIGURES

[0040] D’autres avantages, buts et caractéristiques particulières de l’invention ressortiront de la description non limitative qui suit d’au moins un mode de réalisation particulier du thermoplongeur objet de la présente invention, en regard des dessins annexés, dans lesquels : [0040] Other advantages, aims and particular characteristics of the invention will emerge from the following non-limiting description of at least one particular embodiment of the immersion heater which is the subject of the present invention, with reference to the appended drawings, in which:

[0041] [Fig 1] représente, schématiquement et en vue de coupe axiale, un premier mode de réalisation d’un thermoplongeur selon l’invention, [0041] [Fig 1] represents, schematically and in axial section view, a first embodiment of an immersion heater according to the invention,

[0042] Fig 2] représente, schématiquement et en vue de coupe transversale, le thermoplongeur objet du premier mode de réalisation, [0042] Fig 2] represents, schematically and in cross-sectional view, the immersion heater object of the first embodiment,

[0043] Les numéros de référence mentionnés sur les figures se rapportent à : [0043] The reference numbers mentioned in the figures relate to:

90 un liquide à chauffer 90 a liquid to heat

80, 81 une flèche représentant un flux de chaleur 80, 81 an arrow representing a heat flow

100 un thermoplongeur 100 an immersion heater

110 un moyen d’alimentation en courant électrique 110 a means of supplying electric current

115, 116 des résistances chauffantes 115, 116 heating resistors

120 une gaine 120 a sheath

130 poudre céramique électriquement isolante 130 electrically insulating ceramic powder

140 la paroi tubulaire 140 the tubular wall

145 un deuxième compartiment 145 a second compartment

150 un premier compartiment DESCRIPTION DÉTAILLÉE DE L’INVENTION 150 a first compartment DETAILED DESCRIPTION OF THE INVENTION

[0044] La présente description est donnée à titre non limitatif, chaque caractéristique d’un mode de réalisation pouvant être combinée à toute autre caractéristique de tout autre mode de réalisation de manière avantageuse. [0044] The present description is given without limitation, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

[0045] On observe, sur les figures 1 et 2 un premier mode de réalisation particulier d’un thermoplongeur 100 selon l’invention. En figure 1, une vue en coupe axiale, du thermoplongeur est présentée. En figure 2, une vue en coupe transversale dans la partie chauffante du thermoplongeur 100, selon le plan de coupe A-A, visible en figure 1, est présentée. [0045] Figures 1 and 2 show a first particular embodiment of an immersion heater 100 according to the invention. Figure 1 shows an axial sectional view of the immersion heater. Figure 2 shows a cross-sectional view of the heating part of the immersion heater 100, along the section plane A-A, visible in Figure 1.

[0046] Le thermoplongeur 100 est un thermoplongeur électrique comportant une zone chauffante 101, et une zone non chauffante 102 permettant de faire le lien entre la zone chauffante et un support du thermoplongeur 100 raccordée à moyen d’alimentation électrique 110. Le thermoplongeur 100 est destiné à être positionné dans une cuve [non représentée] contenant du métal à chauffer. La zone chauffante 102 du thermoplongeur 100 est destinée à être mise au contact du métal, qu’il s’agisse d’un métal en fusion à maintenir en température en vue de le conserver à l’état liquide ou d’un métal solide à chauffer. [0046] The immersion heater 100 is an electric immersion heater comprising a heating zone 101, and a non-heating zone 102 making it possible to make the connection between the heating zone and a support of the immersion heater 100 connected to an electrical power supply means 110. The immersion heater 100 is intended to be positioned in a tank [not shown] containing metal to be heated. The heating zone 102 of the immersion heater 100 is intended to be placed in contact with the metal, whether it is a molten metal to be maintained at temperature in order to keep it in the liquid state or a solid metal to be heated.

[0047] La zone chauffante 101 du thermoplongeur 100 comporte une pluralité d’éléments chauffants, 115, 116, portés à haute température par le passage d'un courant électrique ; il s’agit d’un chauffage résistif. Comme cela sera expliqué en plus grand détail ci-dessous, chaque élément chauffant comporte un conducteur électrique, qui est en contact avec un matériau électriquement isolant 130 capable de transmettre sa chaleur à une gaine 120 [gaine externe] formant la couche la plus externe du corps du thermoplongeur 100, qui transmet à son tour la chaleur au métal ou à l'alliage à fondre ou à maintenir à l’état liquide. [0047] The heating zone 101 of the immersion heater 100 comprises a plurality of heating elements, 115, 116, brought to a high temperature by the passage of an electric current; this is a resistive heating. As will be explained in greater detail below, each heating element comprises an electrical conductor, which is in contact with an electrically insulating material 130 capable of transmitting its heat to a sheath 120 [external sheath] forming the outermost layer of the body of the immersion heater 100, which in turn transmits the heat to the metal or alloy to be melted or maintained in the liquid state.

[0048] Le mécanisme de transmission de la chaleur de la gaine du thermoplongeur vers le métal dans la cuve se fait de manière la plus efficace par conduction, lorsque le thermoplongeur est immergé dans du métal liquide ou lorsque sa gaine touche sur une fraction significative de sa surface du métal solide. En dehors de ces zones de contact direct le transfert thermique entre la gaine et le métal contenu dans la cuve est radiatif et/ou convectif. Le transfert de chaleur depuis l’élément chauffant 115 vers la gaine 120 puis vers la matière à chauffer 90 est représenté par la flèche 80, en figures 1 et 2. [0048] The mechanism for transmitting heat from the sheath of the immersion heater to the metal in the tank is most efficiently by conduction, when the immersion heater is immersed in liquid metal or when its sheath touches solid metal over a significant fraction of its surface. Outside of these areas of direct contact, the heat transfer between the sheath and the metal contained in the tank is radiative and/or convective. The heat transfer from the heating element 115 to the sheath 120 and then to the material to be heated 90 is represented by the arrow 80, in FIGS. 1 and 2.

[0049] Le thermoplongeur 100 est par exemple configuré pour maintenir à l’état liquide un métal 90 sous forme liquide comportant un métal non ferreux ou un alliage à base d’un métal non ferreux qui présente une température de fusion suffisamment basse pour être compatible avec l’utilisation d’un thermoplongeur électrique. En particulier, le métal non ferreux peut être tout métal ou alliage présentant une température de fusion qui ne dépasse pas environ 1100°C. Le métal de base peut par exemple être choisi parmi l’aluminium, le zinc, le magnésium, le cuivre, l'étain, le plomb, le lithium, l’argent. [0049] The immersion heater 100 is for example configured to maintain in the liquid state a metal 90 in liquid form comprising a non-ferrous metal or an alloy with base of a non-ferrous metal which has a melting temperature sufficiently low to be compatible with the use of an electric immersion heater. In particular, the non-ferrous metal may be any metal or alloy having a melting temperature which does not exceed approximately 1100°C. The base metal may for example be chosen from aluminum, zinc, magnesium, copper, tin, lead, lithium, silver.

[0050] La gaine 120 du thermoplongeur 100 est préférentiellement formée en nitrure de bore ou nitrure de silicium. Ces matériaux réfractaires ont une forte résistance à la chaleur et sont inertes chimiquement, en plus d’offrir une résistance mécanique satisfaisante. La gaine 120 délimite un premier compartiment 150 à l’intérieur duquel sont disposés les éléments chauffants, 115, 116, du thermoplongeur 100. [0050] The sheath 120 of the immersion heater 100 is preferably formed from boron nitride or silicon nitride. These refractory materials have a high heat resistance and are chemically inert, in addition to offering satisfactory mechanical resistance. The sheath 120 delimits a first compartment 150 inside which the heating elements, 115, 116, of the immersion heater 100 are arranged.

[0051] Ledit premier compartiment 150 est au moins en partie rempli de poudre céramique électriquement isolante 130. La poudre céramique électriquement isolante 130 est un matériau sélectionné pour ses caractéristiques d’isolant électrique, permettant un contact direct avec les conducteurs électriques de l’élément chauffant, et pour ses caractéristiques de conducteur de chaleur. De plus, la poudre céramique électriquement isolante 130 doit présenter une excellente tenue à la température, elle ne doit pas se dégrader dans la durée, permettant une durée de vie effective du thermoplongeur allant typiquement d’une à plusieurs dizaines de mois d’utilisation en continu. Elle présente avantageusement une bonne conductivité thermique. [0051] Said first compartment 150 is at least partly filled with electrically insulating ceramic powder 130. The electrically insulating ceramic powder 130 is a material selected for its electrical insulating characteristics, allowing direct contact with the electrical conductors of the heating element, and for its heat conductor characteristics. In addition, the electrically insulating ceramic powder 130 must have excellent temperature resistance, it must not degrade over time, allowing an effective service life of the immersion heater typically ranging from one to several tens of months of continuous use. It advantageously has good thermal conductivity.

[0052] Selon un exemple de réalisation, la poudre céramique électriquement isolante 130 est une poudre de magnésie [oxyde de magnésium : MgO] électrofondue. La poudre de magnésie électrofondue est fabriquée par fusion d’oxyde de magnésium à une température dépassant les 3 000°C. Dans d’autres modes de réalisation la poudre céramique électriquement isolante est choisie parmi une poudre d’oxyde de zinc [ZnO], une poudre d’alumine [AI2O3] ou une poudre de nitrure de bore. [0052] According to an exemplary embodiment, the electrically insulating ceramic powder 130 is an electrofused magnesia [magnesium oxide: MgO] powder. The electrofused magnesia powder is manufactured by melting magnesium oxide at a temperature exceeding 3,000°C. In other embodiments, the electrically insulating ceramic powder is selected from a zinc oxide [ZnO] powder, an alumina [Al2O3] powder or a boron nitride powder.

[0053]À l’intérieur du premier compartiment 150 délimité par la gaine 120, le thermoplongeur 100 comporte au moins une paroi 140 délimitant un deuxième compartiment 145 fermé, distinct du premier compartiment. Ledit deuxième compartiment a pour fonction de réduire la quantité de poudre céramique électriquement isolante 130 nécessaire à la fabrication du thermoplongeur 100 et ainsi d’en réduire le coût de fabrication. La paroi 140 est une typiquement une paroi tubulaire, sa section en coupe axiale est avantageusement circulaire. [0053]Inside the first compartment 150 delimited by the sheath 120, the immersion heater 100 comprises at least one wall 140 delimiting a second closed compartment 145, distinct from the first compartment. Said second compartment has the function of reducing the quantity of electrically insulating ceramic powder 130 necessary for the manufacture of the immersion heater 100 and thus of reducing the manufacturing cost. The wall 140 is typically a tubular wall, its axial section is advantageously circular.

[0054] La paroi 140 est formée d’un matériau présentant des caractéristiques de résistance mécanique et de résistance thermique suffisantes, sans nécessiter une bonne conduction thermique. Préférentiellement, la paroi 140 est formée de céramique, par exemple d’alumine. Selon d’autres exemples de mise en œuvre, la paroi 140 est formée en mullite ou jcordièrit [Mji]|[TH2]. Selon d’autres modes de mise en œuvre, la paroi est formée d’un alliage haute performance, préférentiellement un alliage à base de nickel présentant une faible dilatation à 1100°C. Par exemple, la paroi est formée d’un alliage choisi parmi les alliages Inconel ou les alliages monocristallins CMSX. [0054] The wall 140 is formed of a material having sufficient mechanical strength and thermal resistance characteristics, without requiring good thermal conduction. Preferably, the wall 140 is formed of ceramic, for example alumina. According to other examples of implementation, the wall 140 is formed of mullite or jcordierit [Mji]|[TH2]. According to other embodiments, the wall is formed of a high-performance alloy, preferably a nickel-based alloy having low expansion at 1100°C. For example, the wall is formed of an alloy chosen from Inconel alloys or CMSX monocrystalline alloys.

[0055] Dans un mode de réalisation, le deuxième compartiment 145 délimité par la paroi 140 reste en partie vide de matière solide. La partie du deuxième compartiment vide de matière solide comporte du gaz qui peut être de l’air. Préférentiellement, l’air est chassé en vue d’être remplacé par un gaz inerte, peu susceptible d’oxyder la paroi, qui peut être par exemple l’argon ou un autre gaz noble. [0055] In one embodiment, the second compartment 145 delimited by the wall 140 remains partly empty of solid material. The part of the second compartment empty of solid material comprises gas which may be air. Preferably, the air is expelled in order to be replaced by an inert gas, unlikely to oxidize the wall, which may be for example argon or another noble gas.

[0056] Le deuxième compartiment 145 est au moins en partie rempli d’un matériau inerte sous forme particulaire. Le matériau inerte contenu dans le deuxième compartiment 145 permet de prévenir un phénomène de tirage thermique. Le matériau inerte peut également exercer une contre-pression contre la paroi 140. [0056] The second compartment 145 is at least partly filled with an inert material in particulate form. The inert material contained in the second compartment 145 makes it possible to prevent a thermal draft phenomenon. The inert material can also exert a counter-pressure against the wall 140.

[0057] Par exemple, ledit matériau inerte comporte des fibres à haute tenue en température, par exemple des fibres poly-cristallines de mullite ou des fibres silico alumineuses. Selon une autre variante, ledit matériau inerte est une poudre d’alumine. [0057] For example, said inert material comprises high temperature resistance fibers, for example polycrystalline mullite fibers or silico-alumina fibers. According to another variant, said inert material is an alumina powder.

[0058] La gaine 120 présente typiquement une section circulaire. Avantageusement, le diamètre extérieur de la gaine 120 est d’au moins 55 millimètres [ci-après abrévié « mm »], préférentiellement d’au moins 75 mm. Selon une alternative de réalisation, le diamètre de la gaine 120 est supérieur à 95 mm ou supérieur à 115 mm. L’augmentation du diamètre de la gaine 120 permet de placer un nombre plus important d’éléments chauffants 115,116 à l’intérieur du thermoplongeur 100, ce qui permet d’augmenter sa puissance thermique. [0058] The sheath 120 typically has a circular section. Advantageously, the outer diameter of the sheath 120 is at least 55 millimeters [hereinafter abbreviated “mm”], preferably at least 75 mm. According to an alternative embodiment, the diameter of the sheath 120 is greater than 95 mm or greater than 115 mm. Increasing the diameter of the sheath 120 makes it possible to place a greater number of heating elements 115, 116 inside the immersion heater 100, which makes it possible to increase its thermal power.

[0059] De plus, la paroi 140 est un tube de section circulaire également, formant un deuxième compartiment 145 de forme section ronde. Le premier compartiment 150 formé d’une part par la gaine 120 et d’autre part par la paroi 140 présente ainsi une forme annulaire avantageuse pour le placement des éléments chauffants, 115, 116, comme détaillé dans le paragraphe suivant. Préférentiellement, le tube formant la paroi 140 est de diamètre constant sur toute la hauteur du thermoplongeur. [0059] In addition, the wall 140 is a tube of circular section also, forming a second compartment 145 of round section shape. The first compartment 150 formed on the one hand by the sheath 120 and on the other hand by the wall 140 thus has an advantageous annular shape for the placement of the heating elements, 115, 116, as detailed in the following paragraph. Preferably, the tube forming the wall 140 is of constant diameter over the entire height of the immersion heater.

[0060] De tels tubes en alumine sont des produits courants qui existent sur le marché pour d’autres utilisations ; de ce fait, leur prix est significativement plus faible que celui de la quantité de poudre de magnésie électrofondue [par exemple] économisée par l’insertion d’un tel tube dans le dispositif selon l’invention. [0061] Le thermoplongeur 100 représenté sur les figures 1 et 2 comporte seize éléments chauffants dont seuls les éléments chauffants 115 et 116 sont légendés en figures 1 et 2. Dans d’autres modes de réalisation, le thermoplongeur 100 comporte au moins 20 éléments chauffants, préférentiellement au moins 30 éléments chauffants. Préférentiellement et comme illustré en figures 1 et 2, les éléments chauffants sont positionnés à proximité du pourtour intérieur de la gaine 120 afin de permettre un meilleur transfert de chaleur vers ces dernières. En d’autres termes, si l’on considère une section du thermoplongeur 100 tel qu’illustré en figure 2, les éléments chauffants, 115, 116, sont disposés en cercle concentrique avec le cercle formé par la gaine 120. On peut adopter toute autre disposition et tout autre nombre d’éléments chauffant sans sortir du cadre de la présente invention. [0060] Such alumina tubes are common products which exist on the market for other uses; therefore, their price is significantly lower than that of the quantity of electrofused magnesia powder [for example] saved by the insertion of such a tube in the device according to the invention. [0061] The immersion heater 100 shown in FIGS. 1 and 2 comprises sixteen heating elements, of which only the heating elements 115 and 116 are labeled in FIGS. 1 and 2. In other embodiments, the immersion heater 100 comprises at least 20 heating elements, preferably at least 30 heating elements. Preferably and as illustrated in FIGS. 1 and 2, the heating elements are positioned close to the inner periphery of the sheath 120 in order to allow better heat transfer to the latter. In other words, if we consider a section of the immersion heater 100 as illustrated in FIG. 2, the heating elements, 115, 116, are arranged in a circle concentric with the circle formed by the sheath 120. Any other arrangement and any other number of heating elements can be adopted without departing from the scope of the present invention.

[0062] Préférentiellement, les éléments chauffants sont arrangés en spires sensiblement droites disposées sensiblement parallèles à un axe parcourant le centre de la gaine 120 et lesdites spires sont positionnées à proximité du pourtour intérieur de la gaine 120. [0062] Preferably, the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath 120 and said turns are positioned close to the inner periphery of the sheath 120.

[0063] Préférentiellement, les éléments chauffants 115, 116 comportent des résistances électriques comportant du molybdène ou un alliage choisi parmi un alliage de fer- chrome-aluminium [FeCrAl], un alliage de nickel et de chrome. [0063] Preferably, the heating elements 115, 116 comprise electrical resistors comprising molybdenum or an alloy chosen from an iron-chromium-aluminium alloy [FeCrAl], a nickel and chromium alloy.

[0064] Selon un mode de réalisation particulier [non illustré], la paroi 140 tubulaire forme un compartiment de section transversale de forme rectangulaire ou polygonale, par exemple octogonal ou hexagonale. [0064] According to a particular embodiment [not illustrated], the tubular wall 140 forms a compartment with a rectangular or polygonal cross-section, for example octagonal or hexagonal.

[0065] Selon un mode de réalisation particulier [non illustré], le deuxième compartiment 145 formé par la paroi 140 ne présente pas les mêmes dimensions sur toute la hauteur du thermoplongeur 100. Par exemple, le deuxième compartiment 140 au niveau d’une coupe transversale dans la partie non chauffante du thermoplongeur 100 présente une surface moindre que la surface du deuxième compartiment 140 au niveau d’une coupe transversale dans la partie non chauffante du thermoplongeur 100. [0065] According to a particular embodiment [not illustrated], the second compartment 145 formed by the wall 140 does not have the same dimensions over the entire height of the immersion heater 100. For example, the second compartment 140 at a cross-section in the non-heating part of the immersion heater 100 has a smaller surface area than the surface area of the second compartment 140 at a cross-section in the non-heating part of the immersion heater 100.

Selon un mode de réalisation particulier [non illustré], le thermoplongeur comporte un premier compartiment au moins en partie rempli de poudre céramique électriquement isolante et une pluralité de parois disposées à l’intérieur du premier compartiment, chacune desdites paroi délimitant un compartiment pouvant rester vide de matière solide ou pouvant être rempli au moins en partie d’un matériau isolant According to a particular embodiment [not illustrated], the immersion heater comprises a first compartment at least partly filled with electrically insulating ceramic powder and a plurality of walls arranged inside the first compartment, each of said walls delimiting a compartment which can remain empty of solid material or which can be filled at least partly with an insulating material.

[0066] Nous décrivons ici un procédé de fabrication du thermoplongeur selon l’invention. [0066] We describe here a method of manufacturing the immersion heater according to the invention.

Les inventeurs se sont aperçus que le bon contact thermique entre les conducteurs électriques et la gaine 120 dépend de la densité du lit de poudre céramique électriquement isolante avec lequel ces conducteurs sont en contact. Selon l’invention, on approvisionne un gaine 120, une paroi tubulaire 140, une pluralité d’éléments chauffants 115,116 et une poudre électriquement isolante 130, on place ladite paroi tubulaire 140 à l’intérieur de ladite gaine 120, on introduit les conducteurs électriques dans le premier compartiment 150 entre la gaine 120 et la paroi 140, puis on remplit ledit premier compartiment 150 de poudre céramique électriquement isolante par étapes, au moins certaines étapes (et de préférence chaque étape) de remplissage étant suivie(s) par au moins une étape de tassement. The inventors realized that good thermal contact between the conductors electrical conductors and the sheath 120 depends on the density of the bed of electrically insulating ceramic powder with which these conductors are in contact. According to the invention, a sheath 120, a tubular wall 140, a plurality of heating elements 115, 116 and an electrically insulating powder 130 are supplied, said tubular wall 140 is placed inside said sheath 120, the electrical conductors are introduced into the first compartment 150 between the sheath 120 and the wall 140, then said first compartment 150 is filled with electrically insulating ceramic powder in stages, at least some filling steps (and preferably each filling step) being followed by at least one compaction step.

[0067] Dans un premier mode de réalisation, au cours de cette étape de tassement, on presse la poudre à l’aide d’un outil de tassement forme annulaire ou en section d’anneau, capable de s’insérer par le haut dans l’espace annulaire formé par le premier compartiment 150. Ainsi on remplit progressivement ledit premier compartiment d’un lit dense et tassé de poudre céramique électriquement isolante, qui assure un excellent contact thermique avec les éléments chauffants 115,116. [0067] In a first embodiment, during this tamping step, the powder is pressed using a tamping tool in the shape of an annular or ring section, capable of being inserted from above into the annular space formed by the first compartment 150. Thus, said first compartment is gradually filled with a dense, packed bed of electrically insulating ceramic powder, which ensures excellent thermal contact with the heating elements 115, 116.

[0068] Dans une première variante de ce procédé, chaque étape d’introduction de la poudre céramique électriquement isolante, ou au moins une de ces étapes, et de préférence au moins la dernière, est suivie d’une étape de tassement par mise en vibration de la gaine 150 et/ou du tube 140. [0068] In a first variant of this method, each step of introducing the electrically insulating ceramic powder, or at least one of these steps, and preferably at least the last, is followed by a step of compaction by vibrating the sheath 150 and/or the tube 140.

[0069] Dans une autre variante de ce procédé, ledit outil de tassement est réalisé comme un outil de vibrocompactage. [0069] In another variant of this method, said compaction tool is produced as a vibrocompaction tool.

[0070] Ces deux variantes peuvent être combinées. [0070] These two variants can be combined.

Claims

REVENDICATIONS [Revendication 1] Thermoplongeur [100] configuré pour être mis en contact avec une matière à chauffer (90), notamment un métal non ferreux en fusion, caractérisé en ce qu’il comporte : [Claim 1] Immersion heater [100] configured to be placed in contact with a material to be heated (90), in particular a molten non-ferrous metal, characterized in that it comprises: - une gaine (120) délimitant un premier compartiment (150) au moins en partie rempli de poudre céramique électriquement isolante (130), ladite gaine étant configurée pour être mise en contact avec la matière à chauffer, - a sheath (120) delimiting a first compartment (150) at least partly filled with electrically insulating ceramic powder (130), said sheath being configured to be placed in contact with the material to be heated, - une paroi (140) disposée à l’intérieur du premier compartiment (150) et délimitant au moins un deuxième compartiment (145), ce dernier étant rempli au moins en partie d’un matériau inerte, - a wall (140) arranged inside the first compartment (150) and delimiting at least one second compartment (145), the latter being filled at least in part with an inert material, - une pluralité d’éléments chauffants (115, 116) disposés dans ladite poudre céramique électriquement isolante (130), entre ladite gaine (120) et ladite paroi (140). - a plurality of heating elements (115, 116) arranged in said electrically insulating ceramic powder (130), between said sheath (120) and said wall (140). [Revendication 2] Thermoplongeur (100) selon la revendication 1, dans lequel la paroi (140) disposée à l’intérieur de la gaine (120) et délimitant un deuxième compartiment (145) rempli au moins en partie d’un matériau isolant est formée au moins en partie de matériau céramique. [Claim 2] Immersion heater (100) according to claim 1, in which the wall (140) disposed inside the sheath (120) and delimiting a second compartment (145) filled at least in part with an insulating material is formed at least in part of ceramic material. [Revendication 3] Thermoplongeur selon l’une des revendications 1 ou 2, dans lequel ladite poudre céramique électriquement isolante (130) est choisie parmi une poudre d’oxyde de zinc, une poudre d’alumine, une poudre de magnésie électrofondue, ou une poudre de nitrure de bore. [Claim 3] An immersion heater according to one of claims 1 or 2, wherein said electrically insulating ceramic powder (130) is selected from a zinc oxide powder, an alumina powder, an electrofused magnesia powder, or a boron nitride powder. [Revendication 4] Thermoplongeur (100) selon l’une des revendications 1 à 3, dans lequel ledit matériau inerte remplissant au moins en partie le deuxième compartiment (145) délimité par la paroi (140) comporte des fibres à haute tenue en température, par exemple des fibres poly-cristallines de mullite ou des fibres silico alumineuses. [Claim 4] Immersion heater (100) according to one of claims 1 to 3, in which said inert material at least partially filling the second compartment (145) delimited by the wall (140) comprises fibers with high temperature resistance, for example polycrystalline mullite fibers or silico-alumina fibers. [Revendication 5] Thermoplongeur (100) selon l’une des revendications 1 à 4, dans lequel le deuxième compartiment (145) délimité par la paroi (140) est en partie rempli d’un matériau inerte et reste en partie vide de matière solide. [Claim 5] Immersion heater (100) according to one of claims 1 to 4, in which the second compartment (145) delimited by the wall (140) is partly filled with an inert material and remains partly empty of solid material. [Revendication 6] Thermoplongeur (100) selon la revendication 5, dans lequel le thermoplongeur comporte une zone chauffante (101), abritant les éléments chauffants, et une zone non chauffante (102) et dans lequel la partie du deuxième compartiment (145) correspondant en hauteur à la zone chauffante (101) du thermoplongeur est remplie de matériau inerte et la partie du deuxième compartiment (145) correspondant en hauteur à la zone non chauffante (102) du thermoplongeur est laissée vide de matière solide. [Claim 6] An immersion heater (100) according to claim 5, wherein the immersion heater comprises a heating zone (101), housing the heating elements, and a non-heating zone (102) and wherein the part of the second compartment (145) corresponding in height to the heating zone (101) of the immersion heater is filled with inert material and the part of the second compartment (145) corresponding in height to the non-heating zone (102) of the immersion heater is left empty of solid material. [Revendication 7] Thermoplongeur (100) selon l’une des revendications 1 à 6, dans lequel la gaine (120) présente une section circulaire. [Claim 7] Immersion heater (100) according to one of claims 1 to 6, in which the sheath (120) has a circular section. [Revendication 8] Thermoplongeur (100) selon la revendication 7, dans lequel la gaine (120) présente un diamètre extérieur supérieur ou égal à 50 millimètres, de préférence supérieur à 75 mm, plus préférentiellement supérieur à 95 mm, et encore plus préférentiellement supérieur à 115 mm. [Claim 8] Immersion heater (100) according to claim 7, in which the sheath (120) has an external diameter greater than or equal to 50 millimeters, preferably greater than 75 mm, more preferably greater than 95 mm, and even more preferably greater than 115 mm. [Revendication 9] Thermoplongeur (100) selon l’une des revendications 1 à 8, dans lequel la paroi (140) est un tube de section circulaire. [Claim 9] Immersion heater (100) according to one of claims 1 to 8, in which the wall (140) is a tube of circular section. [Revendication 10] Thermoplongeur (100) selon l’une des revendications 7 ou 8 et selon la revendication 9, dans lequel le centre de la gaine (120) de section circulaire et le centre de la paroi (140) de section circulaire sont sensiblement identiques, de sorte que le premier compartiment formé entre la gaine (120) et la paroi (140) et destiné à être rempli au moins en partie de poudre céramique électriquement isolante présente une section annulaire. [Claim 10] Immersion heater (100) according to one of claims 7 or 8 and according to claim 9, in which the center of the sheath (120) of circular section and the center of the wall (140) of circular section are substantially identical, so that the first compartment formed between the sheath (120) and the wall (140) and intended to be filled at least in part with electrically insulating ceramic powder has an annular section. [Revendication 11] Thermoplongeur (100) selon l’une des revendications 1 à 10, dans lequel les éléments chauffants sont arrangés en spires sensiblement droites disposées sensiblement parallèles à un axe parcourant le centre de la gaine (120) et dans lequel le thermoplongeur comporte au moins 15 spires, préférentiellement au moins 20 spires, préférentiellement au moins 20 spires, préférentiellement au moins 25 spires, préférentiellement au moins 30 spires. [Claim 11] Immersion heater (100) according to one of claims 1 to 10, in which the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath (120) and in which the immersion heater comprises at least 15 turns, preferably at least 20 turns, preferably at least 20 turns, preferably at least 25 turns, preferably at least 30 turns. [Revendication 12] Thermoplongeur (100) selon l’une des revendications 1 àll, dans lequel les éléments chauffants sont arrangés en spires sensiblement droites disposées sensiblement parallèles à un axe parcourant le centre de la gaine (120) et dans lequel lesdites spires sont positionnées à proximité du pourtour intérieur de la gaine (120). [Revendication 13] Procédé de fabrication d’un thermoplongeur selon l’une quelconque des revendications 1 à 12, dans lequel on approvisionne une gaine (120), une paroi tubulaire (140), une pluralité d’éléments chauffants (115,116) et une poudre céramique électriquement isolante (130), on place ladite paroi tubulaire (140) à l’intérieur de ladite gaine (120), on introduit les éléments chauffants (115,116) dans le premier compartiment (150) entre la gaine (120) et la paroi (140), puis on remplit ledit premier compartiment (150) de poudre céramique électriquement isolante par étapes, au moins certaines étapes, et de préférence chaque étape, de remplissage étant suivie(s) par au moins une étape de tassement. [Claim 12] Immersion heater (100) according to one of claims 1 to 11, in which the heating elements are arranged in substantially straight turns arranged substantially parallel to an axis running through the center of the sheath (120) and in which said turns are positioned close to the inner periphery of the sheath (120). [Claim 13] A method of manufacturing an immersion heater according to any one of claims 1 to 12, wherein a sheath (120), a tubular wall (140), a plurality of heating elements (115,116) and an electrically insulating ceramic powder (130) are provided, said tubular wall (140) is placed inside said sheath (120), the heating elements (115,116) are introduced into the first compartment (150) between the sheath (120) and the wall (140), and then said first compartment (150) is filled with electrically insulating ceramic powder in stages, at least some of the filling stages, and preferably each filling stage, being followed by at least one tamping stage.
PCT/IB2024/055653 2023-06-12 2024-06-10 Compartmentalised immersion heater comprising electrically insulating ceramic powder Ceased WO2024256949A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP24735311.3A EP4724221A1 (en) 2023-06-12 2024-06-10 Compartmentalised immersion heater comprising electrically insulating ceramic powder
CN202480038555.7A CN121285437A (en) 2023-06-12 2024-06-10 Compartment immersion heater comprising electrically insulating ceramic powder

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR2305907A FR3149746A1 (en) 2023-06-12 2023-06-12 COMPARTMENTAL IMMERSION HEATER WITH ELECTRICALLY INSULATING CERAMIC POWDER
FRFR2305907 2023-06-12

Publications (1)

Publication Number Publication Date
WO2024256949A1 true WO2024256949A1 (en) 2024-12-19

Family

ID=87974736

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IB2024/055653 Ceased WO2024256949A1 (en) 2023-06-12 2024-06-10 Compartmentalised immersion heater comprising electrically insulating ceramic powder

Country Status (4)

Country Link
EP (1) EP4724221A1 (en)
CN (1) CN121285437A (en)
FR (1) FR3149746A1 (en)
WO (1) WO2024256949A1 (en)

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3050833A (en) * 1958-05-19 1962-08-28 Thermal Mfg Company Method of making electrically insulated heating units
GB1027163A (en) 1961-08-23 1966-04-27 Morganite Thermal Designs Ltd Improvements in and relating to electrical resistance heaters
FR2517918A1 (en) * 1981-12-09 1983-06-10 Bonet Andre Mfg. electric element embedded in heat transfer unit - using ceramic former with resistance wire wound over and sprayed on insulating sheath fitting into metallic heat transfer unit
FR2559886A1 (en) 1984-02-16 1985-08-23 Electricite De France Electric heating device comprising a resistive heating element
FR2622382A2 (en) 1986-06-26 1989-04-28 Electricite De France Electrical heating device including a metal sheath associated with an inert gas supply circuit
GB2258592A (en) * 1991-08-09 1993-02-10 Paul Walter Dominic Tolkien Inert gas protects carbon heating element
FR2699038A1 (en) 1992-12-08 1994-06-10 Electricite De France Immersible electric heating rod for molten metals, etc. - has sealed tubular container with disposable protective sheath covering section near molten surface.
FR2720888A1 (en) 1994-06-03 1995-12-08 Electricite De France Protective envelope for electric components esp, immersion heating elements used e.g. in aluminium@ prodn.
JPH118049A (en) * 1997-06-19 1999-01-12 Mitsui Mining & Smelting Co Ltd Molten metal heater and method of assembling the same
WO2005060314A1 (en) 2003-12-18 2005-06-30 Electricite De France Electric immersion heater comprising a sheath heating element
CN105960033A (en) * 2016-07-12 2016-09-21 北京中兴实强陶瓷轴承有限公司 Heater
US9993870B2 (en) * 2015-03-26 2018-06-12 Pyrotek High-Temperature Industrial Products Inc. Heated control pin

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3050833A (en) * 1958-05-19 1962-08-28 Thermal Mfg Company Method of making electrically insulated heating units
GB1027163A (en) 1961-08-23 1966-04-27 Morganite Thermal Designs Ltd Improvements in and relating to electrical resistance heaters
FR2517918A1 (en) * 1981-12-09 1983-06-10 Bonet Andre Mfg. electric element embedded in heat transfer unit - using ceramic former with resistance wire wound over and sprayed on insulating sheath fitting into metallic heat transfer unit
FR2559886A1 (en) 1984-02-16 1985-08-23 Electricite De France Electric heating device comprising a resistive heating element
FR2622382A2 (en) 1986-06-26 1989-04-28 Electricite De France Electrical heating device including a metal sheath associated with an inert gas supply circuit
GB2258592A (en) * 1991-08-09 1993-02-10 Paul Walter Dominic Tolkien Inert gas protects carbon heating element
FR2699038A1 (en) 1992-12-08 1994-06-10 Electricite De France Immersible electric heating rod for molten metals, etc. - has sealed tubular container with disposable protective sheath covering section near molten surface.
FR2720888A1 (en) 1994-06-03 1995-12-08 Electricite De France Protective envelope for electric components esp, immersion heating elements used e.g. in aluminium@ prodn.
JPH118049A (en) * 1997-06-19 1999-01-12 Mitsui Mining & Smelting Co Ltd Molten metal heater and method of assembling the same
WO2005060314A1 (en) 2003-12-18 2005-06-30 Electricite De France Electric immersion heater comprising a sheath heating element
US9993870B2 (en) * 2015-03-26 2018-06-12 Pyrotek High-Temperature Industrial Products Inc. Heated control pin
CN105960033A (en) * 2016-07-12 2016-09-21 北京中兴实强陶瓷轴承有限公司 Heater

Also Published As

Publication number Publication date
FR3149746A1 (en) 2024-12-13
CN121285437A (en) 2026-01-06
EP4724221A1 (en) 2026-04-15

Similar Documents

Publication Publication Date Title
EP0012050B1 (en) Cooled electrode for making contact with a metal melt
EP1514630A1 (en) Resistance welding electrode and method for its manufacture
EP1649949B1 (en) Method of heating forging tools in a forging device, and releasable furnace element for heating such tools
FR2591325A1 (en) BACKGROUND ELECTRODE FOR FUSION OVENS
CA1247179A (en) Electrical connecting device to be mounted on the wall of a metallurgical vessel in direct contact with a molten metal
WO2024256949A1 (en) Compartmentalised immersion heater comprising electrically insulating ceramic powder
EP0183631B1 (en) Wall electrode for a metallurgical direct current electrical furnace
EP0671116B1 (en) Electric melting device
FR2624318A1 (en) ELECTRICAL IGNITION DEVICE RESISTANT TO OXIDATION AT HIGH TEMPERATURE
EP0536018A1 (en) Wall electrode for metallurgical electric direct current furnace
FR2498012A1 (en) DISCHARGE RECEPTACLE FOR HIGH PRESSURE SODIUM VAPOR BLADES
FR2707272A1 (en) Improvements brought to the cooled rollers for the handling of products in particular metallurgical and iron and steel.
FR2499964A1 (en) PROCESS FOR REDUCING STRIURES IN FUSED SILICA
FR2565141A1 (en) Device for the guiding and the electrical supplying of a metal filler wire for arc welding, and its method of manufacture
FR2875513A1 (en) Protection of the ceramic sleeve of an immersion heater for a molten metal bath, notably of aluminium, using ultrasonic waves to prevent a build-up of aluminium oxide
FR2489948A1 (en) DEVICE FOR PRODUCING AND COATING A MELT BATH OF MINERAL OR METALLIC MATERIALS
WO2005060314A1 (en) Electric immersion heater comprising a sheath heating element
FR2577372A1 (en) METHOD AND ELEMENT FOR HEATING ELECTRICALLY CONDUCTIVE FLUID, SUCH AS MOLTEN METAL
FR2907353A1 (en) DEVICE FOR HEATING A LIQUID METAL BATH.
FR2921859A1 (en) RIGID CORE FOR THE MANUFACTURE OF TIRES.
BE430103A (en)
FR2475797A3 (en) VOLTAGE LIMITER AND MANUFACTURING METHOD THEREOF
WO2024213642A1 (en) Electrode support for glass-making furnace
FR2479057A1 (en) INDUCTION BRASER PRESS ON A FLAT SURFACE OF A METALLIC PART, A THERMAL CONDUCTIVE COATING
BE493627A (en)

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 24735311

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2024735311

Country of ref document: EP

Effective date: 20260112

WWE Wipo information: entry into national phase

Ref document number: 2024735311

Country of ref document: EP

NENP Non-entry into the national phase

Ref country code: DE

ENP Entry into the national phase

Ref document number: 2024735311

Country of ref document: EP

Effective date: 20260112

ENP Entry into the national phase

Ref document number: 2024735311

Country of ref document: EP

Effective date: 20260112

ENP Entry into the national phase

Ref document number: 2024735311

Country of ref document: EP

Effective date: 20260112

ENP Entry into the national phase

Ref document number: 2024735311

Country of ref document: EP

Effective date: 20260112

WWP Wipo information: published in national office

Ref document number: 2024735311

Country of ref document: EP