Classifications

• • 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
  • F27D99/0033—Heating elements or systems using burners
  • F27D99/0035—Heating indirectly through a radiant surface
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/003—Apparatus
  • C23C2/0036—Crucibles
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
  • C23C2/06—Zinc or cadmium or alloys based thereon
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
  • C23C2/34—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the shape of the material to be treated
  • C23C2/36—Elongated material
  • C23C2/38—Wires; Tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F27—FURNACES; KILNS; OVENS; RETORTS
  • F27B—FURNACES, KILNS, OVENS, OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
  • F27B3/00—Hearth-type furnaces, e.g. of reverberatory type; Tank furnaces
  • F27B3/10—Details, accessories, or equipment peculiar to hearth-type furnaces
  • F27B3/20—Arrangements of heating devices

Definitions

• the present invention relates to a method of heating tanks for molten metal baths, such as tanks for galvanizing steel wires, in which the wires move in the form of a sheet in a substantially continuous manner in the direction of their length through a bath of molten zinc.
• These galvanizing tanks can be of metal crucible or ceramic crucible.
• the heating mode of such tanks must be studied so that at no time the temperature of the wall of the crucible thereof does not exceed the critical temperature of 450 ° C.
• there are different modes of heating namely heating by circulation of hot smoke at high speed, heating of the side walls by radiation by making use of burners called "flat flame", heating by electrical resistance arranged the along the walls and above the tank and finally the induction heating.
• heating by circulation of hot smoke at high speed heating of the side walls by radiation by making use of burners called "flat flame”
• heating by electrical resistance arranged the along the walls and above the tank heating by electrical resistance arranged the along the walls and above the tank and finally the induction heating.
• tanks with a ceramic crucible these being made of pieces of refractory material, or even of poured concrete, there is therefore no temperature limitation contrary to what is the case with tanks with steel crucible.
• Such tanks are generally heated by radiation from a cover placed above the surface of the bath or by immersion of silicon carbide exchanger fingers.
• the high temperature prevailing under the cover accelerates the oxidation of the metal surface by the water vapor accumulating above this surface.
• One of the essential aims of the present invention is to provide a heating method which makes it possible to remedy the various drawbacks described above and this while ensuring a very efficient transfer of heat to the molten metal.
• thermoly conductive refractory material and substantially impermeable to gases, in particular to oxygen, brought into direct and permanent contact with the upper surface of the above-mentioned bath, a heat source being arranged above or inside this element allowing the heating of the latter and, essentially by convection, the bath itself.
• the invention also relates to an installation for heating tanks for molten metal baths, such as galvanizing tanks, and more particularly an installation for the implementation of the above method.
• This installation is characterized by the fact that it comprises at least one element made of thermally conductive refractory material and substantially impermeable to gases, in particular to oxygen, which can be brought into direct and permanent contact with the upper surface of the above-mentioned bath, a heat source being arranged above or inside this element allowing the heating of the latter and, essentially by convection, the bath itself.
• the element of refractory material is arranged so as to be able to float freely on the bath of molten metals.
• Figure 1 is a schematic side view of this first embodiment of one invention.
• FIG. 2 is, on a larger scale, a schematic sectional view along the line II-II of FIG. 1.
• FIG. 3 is a cross section along line III-III of FIG. 2.
• the invention relates to a process for heating tanks 1 for a bath of molten metal 2 according to which use is made of a succession of elements of refractory material 3 which is thermally conductive and substantially impermeable to gases, in particular to oxygen, who are brought into direct and permanent contact with the upper surface 4 of the bath 2.
• a heat source 5 is arranged above this element 3 allowing the heating of the latter, the heating of the bath itself thus being essentially produced by convection from this element.
• At least 60% of its surface 4 is covered with the element made of refractory material 3.
• refractory elements 3 freely floating on the surface 4 of the bath 2 of molten metals.
• the process according to the invention is in principle applicable for the heating of any type of molten metal bath, this process is particularly applicable to galvanizing tanks containing a bath of molten zinc which is crossed by a sheet of steel wire 6 to be covered with a zinc film.
• refractory elements 3 formed by silicon carbide slabs of rectangular shape placed freely next to each other on the surface of the bath 2 , in the longitudinal direction of the tank 1, that is to say in the direction of movement of the ply of wires 6.
• These elements 3 are, in this specific embodiment, completely free from each other, the joints remaining between two adjacent elements being filled with granules of a refractory material 7, such as granules of worm iculite.
• a refractory material 7 such as granules of worm iculite.
• these joints make it possible to intercept the relative displacements of the elements 3 and the thermal expansions.
• different types of heat sources can be used to heat the refractory elements 3, generally a preference is given, as illustrated by the drawings, to fuel air-gas burners with premix or not.
• the refractory elements 3 are placed on the bath 2 so as to provide an access passage 8 between the refractory elements 3 and the neighboring edge of the tank 1 to thus allow easy positioning. of the sheet of steel wires 6 in the bath below the elements 3.
• the embodiment of the installation for the implementation of this process comprises, above each of the elements 3, a cover 9 of refractory material delimiting with the latter a space 10 in which are mounted burners 5 terminating in this space 10. These burners 5 are oriented towards the refractory element 3 thus causing the heating thereof and, by conduction, also of the bath on which this element floats.
• a single burner can be provided per element which is then equipped with several injectors.
• the burner or burners 5 mounted above a given refractory element 3 are possibly entirely independent of the burner or burners mounted above the other elements 3, so as to thus allow perfect control of the heating the successive zones of the bath 2 pass through which the layer of wires 6 to be galvanized passes.
• one or more chimneys 11 are incorporated in each cover 9, for the evacuation of combustion gases, and deflectors 12 are advantageously provided on each element 3, in the space 10 allowing the circulation of gases to be controlled. of combustion in this space.
• the tank 1 generally has a horizontal section of rectangular shape. At each end of this tank is provided a free zone 13 and 14 respectively, that is to say in which a heated refractory element is not provided, as shown in FIG. 1. Zone 13 constitutes the zone d entry of the layer of wires 16 into the bath, while the opposite zone 14 constitutes the exit zone.
• the arrow 15 indicates the direction of movement of the wires 6 through the bath.
• this layer of wires enters obliquely in zone 13 and moves in an inclined position relative to the surface of the bath 2. It then undergoes, in zone 14, an upward deflection around a guide ramp 16 extending transversely relative to the tank before leaving the bath through this zone 14.
• the bottom 17 of the tank is also inclined and preferably extends parallel to the sheet of wires 6, below the refractory elements 3.
• the elements 3 are arranged one after the other in the direction of the length of the tank, by providing on either side of each element an access passage. 8 reserved for threading or positioning of the ply of wires 6 in the bath, below the elements 3, as already mentioned above.
• the width of this access passage 8 can, for example, be of the order of 10 cm.
• the rectangular slabs forming, in this particular embodiment, the refractory elements 3 extend with their longest side transversely to the longitudinal direction of the tank. The length of the long sides of these slabs therefore corresponds to the internal width of the tank 1 reduced by twice the width of the access passage 8. Generally, this width is of the order of 1 to 2 meters.
• the distance separating the edge before the of the tank of the first element 3 floating on the bath is generally of the order of 1 meter
• the central area 20 of the bath in which are the refractory elements 3 generally extending over a distance of the order of several meters in the direction of the length of the wires and the distance separating the last refractory element 3 from the rear edge 14 of the tank 1 being generally around 1.5 to 2 m.
• the length of the smallest side of the refractory elements is generally of the order of 75 cm, while the width of the joints separating two adjacent refractory elements is generally of the order of 10 to 20 cm.
• the cover 9 can be placed freely on the corresponding element 3 or be fixed to the latter.
• This cover has on either side, on the side of the longitudinal edges of the tank, wings 18 threaded on guide rods 9 which stand vertically on the longitudinal edges of the tank, so as to ensure the displacement of the element 3 parallel to the surface 4 of the bath 2 during a variation in the level thereof.
• the elements 3 could be locked in a determined position relative to the tank to maintain intimate contact between this element and the surface of the bath 2. This could by example be made by providing means for fixing the wings 18 of the cover 9 in a determined position on the guide rods 19.
• the elements 3 therefore do not float freely on the bath 2 and can be pressed slightly into it. This can especially be useful when the face of the elements 3 facing the bath has fins, not shown in the figures, with the aim of promoting heat exchange between the elements 3 and the bath 2.
• a common energy supply 21 can be provided for the burners 5 of the same cover 9.
• the end refractory elements can be heated by the enthalpy of the fumes coming from the neighboring elements. In these cases, there is therefore no separate burner for these end elements.
• the elements 3 can be held relative to each other by a kind of jumper, not shown, which makes it possible to ensure their relative position while preventing the accumulation of mattes in the joints between elements neighbors.
• the heating obtained by the use of the refractory element 3 is applicable for all the baths of molten metals, such as the baths of galvanization, galfanisation, tinning, etc.
• the heating process, according to the invention, of such baths has the great advantage of compactness of the equipment thanks to the fact that there is no longer any surface of the unused tank and this while allowing easy access by the two passages 8 between the lateral edges of the tank 1 and the elements 3 for the threading operations in the case of galvanizing wires.
• Another very important advantage compared to the processes using immersed fingers is that it is possible to start the installation while the metal is in the solid state in the tank.
• the invention is not limited to the various embodiments described above of the method and the installation according to the invention, but that different variants can be envisaged within the framework of the invention as well with regard to the nature of the refractory materials used, that the shape of the consti ⁇ tutive parts, such as of the refractory element 3, and of the cover 9 mounted thereon, that the type of heating means used, that materials from which the tank is made, it can therefore be formed from a metal crucible tank, such as steel, or a ceramic crucible tank.
• the heat source could for example be formed of electrical resistances incorporated in the refractory elements 3.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Coating With Molten Metal (AREA)
• Devices For Medical Bathing And Washing (AREA)

Applications Claiming Priority (3)

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• 1995
  • 1995-03-21 BE BE9500247A patent/BE1009250A3/fr not_active IP Right Cessation
• 1996
  • 1996-03-19 WO PCT/BE1996/000030 patent/WO1996029442A1/fr not_active Application Discontinuation
  • 1996-03-19 BR BR9607875A patent/BR9607875A/pt not_active Application Discontinuation
  • 1996-03-19 ES ES96907962T patent/ES2129260T3/es not_active Expired - Lifetime
  • 1996-03-19 DE DE69601303T patent/DE69601303T2/de not_active Expired - Fee Related
  • 1996-03-19 EP EP96907962A patent/EP0815279B1/de not_active Expired - Lifetime
  • 1996-03-19 US US08/894,473 patent/US5876661A/en not_active Expired - Fee Related
  • 1996-03-19 MX MX9707215A patent/MX9707215A/es not_active Application Discontinuation
  • 1996-03-19 KR KR1019970706022A patent/KR19980702617A/ko not_active Application Discontinuation
  • 1996-03-19 JP JP8527915A patent/JPH11502261A/ja active Pending
  • 1996-03-19 CA CA002217394A patent/CA2217394A1/fr not_active Abandoned
  • 1996-03-19 AU AU51394/96A patent/AU694336B2/en not_active Ceased

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