US3419667A - Electric furnace - Google Patents

Electric furnace Download PDF

Info

Publication number
US3419667A
US3419667A US625153A US62515367A US3419667A US 3419667 A US3419667 A US 3419667A US 625153 A US625153 A US 625153A US 62515367 A US62515367 A US 62515367A US 3419667 A US3419667 A US 3419667A
Authority
US
United States
Prior art keywords
tubes
tube
temperature
nozzles
furnace
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.)
Expired - Lifetime
Application number
US625153A
Other languages
English (en)
Inventor
Walz Alfred
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.)
Sued Chemie AG
Original Assignee
Sued Chemie AG
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 Sued Chemie AG filed Critical Sued Chemie AG
Application granted granted Critical
Publication of US3419667A publication Critical patent/US3419667A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/08—Bushings, e.g. construction, bushing reinforcement means; Spinnerettes; Nozzles; Nozzle plates
    • C03B37/081—Indirect-melting bushings
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/08—Bushings, e.g. construction, bushing reinforcement means; Spinnerettes; Nozzles; Nozzle plates
    • C03B37/09—Bushings, e.g. construction, bushing reinforcement means; Spinnerettes; Nozzles; Nozzle plates electrically heated
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/08—Bushings, e.g. construction, bushing reinforcement means; Spinnerettes; Nozzles; Nozzle plates
    • C03B37/09—Bushings, e.g. construction, bushing reinforcement means; Spinnerettes; Nozzles; Nozzle plates electrically heated
    • C03B37/092—Direct-resistance heating
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/02—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating
    • C03B5/033—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture in electric furnaces, e.g. by dielectric heating by using resistance heaters above or in the glass bath, i.e. by indirect resistance heating
    • C03B5/0336—Shaft furnaces
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B5/00—Melting in furnaces; Furnaces so far as specially adapted for glass manufacture
    • C03B5/16—Special features of the melting process; Auxiliary means specially adapted for glass-melting furnaces
    • C03B5/225—Refining
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S65/00—Glass manufacturing
    • Y10S65/04—Electric heat

Definitions

  • An electric furnace for melting materials includes a pair of coaxially arranged symmetrcal electrodes defining an annular space between them through which the materials to be melted are passed. To prevent sticking of the material in the sintering area the electrodes are maintained at a temperature above the sintering temperature of the material throughout their length of contact with the material. Where it is desired to form fibers and the like, the molten material may pass through difuser nozzles supplied with heated air. If it is desired to form a com-mon, flowing :melt of material, the individual strings of molten material may be combined in a funnel-like structure.
  • the present invention relates to electric furnaces in general, and more particularly to an electric furnace which is especially suited for melting of glass, minerals and other materials by direct resistance heating.
  • the electric furnace disclosed in the above mentioned patent consists essentially of coaxially arranged symmetrical tubes or electrodes, which tubes at their upper ends are connected to the terminals of an electric current source and which tubes at their lower ends make conducting contact.
  • An annular space is defined between the tubes through which the materials to be melted are passed. These materials are supplied to the upper end of the annular space and are steadily heated as they move downwardly between the tubes until they reach their melting temperature. Outlet openings are provided at the junction of the tubes for the molten material.
  • Such electric furnaces may be used for the manufacture of fibers and threads by providing discharge nozzles for the molten material which operate according to the difuser principle.
  • One difficulty which has been found for such installation is that the blast of air or other dfiusing medium directs cold air in the blowing nozzles and which hits the molten material, thereby raising its viscosity too high.
  • this quenching of the jet of melt prior to the fiber formation leads to an undesirable action upon the process of fi-ber formation.
  • a furnace of this type for the formation of materials other than fibers or threads. Since a melting furnace generally has outlet nozzles in the annular space which are located certain distances from each other, generally with compressed air ditfusers connected to them, diificulty is experienced in the production of small amounts of molten glass such as 'would be used for special purposes as photographic lens and the like.
  • Yet another object of the present inventon is to provide a new and improved electric furnace which minimizes diificulties created by sticking of the material in the sintering zone.
  • Yet a further object of the present invention resides in the provision of an improved electric furnace of the type provided with ditfuser nozzles wherein diiculties arising from the increase in viscosity of the molten metal when mixed with cold air of the blowing nozzles is minimized.
  • Yet a further object of the present invention is the provision of an improved electric furnace of the typedescribed wherein small amounts of molten material may be produced which are not fibrous in form.
  • an improved electric furnace of the type having a direct, electrical resistance heating for materials which can be molten and which preferably have a high melting point.
  • a furnace consists of vertically arranged tubes defining elect-rodes which preferably are concentric and symmetrical. The upper ends of the tubes are connected to a source of current, and the lower ends of the tubes make conducting contact. The annular space between the tubes accom modates the material to be molten.
  • the inner tube is generally cylindrical
  • the outer tube is defined by generally cylindrical portions at its upper and lower ends interconnected by an intermediate funnel-shaped portion so that the temperature of the inner tube along the region at which it makes contact with the material to be molten is equal to or higher than the melting temperature of the material and that the temperature of the external tube in all of the region where it makes contact with the material to be molten is higher than the sintering temperature of the material, and in the regions of the outlet nozzles defined at the juncture of the tubes the molten material will reach at least the melting temperature.
  • the air or fluid supplied to the diifuser nozzles first passes through one of the tubes for cooling the upper portion of the furnace, and thereafter the heated air is supplied to the ditfuser nozzles.
  • the heated air does not adversely aifect the viscosity of the molten material passing therethrough.
  • the nozzles formed at the juncture of the inner and outer tubes are of a relatively large diameter and run out into a collecting funnel which is located underneath the furnace, the streams of molten material being com bined in the collecting funnel so as to form one common,
  • FIG. 1 is ⁇ a central vertical section through an electric furnace which embodies one form of the invention
  • FIG. 2 is a central vertical section through an electric furnace which embodies another form of the invention.
  • FIG. 4 is a central vertical section through the lower part of yet another modified form of furnace.
  • the supporting device of the internal tube 11 consists of an internally conical screw collar ring 22, the internal diameter of which tapers off upwardly from the outer diameter of the internal tube 11; it is filled in by the internal tube 11, which in this region is equipped with a slit 23.
  • the internal tube itself is filled with a tapered shank 24 which has the same slope as the collar ring 22.
  • a threaded end 25 of the shank 24 protrudes above and beyond the screw collar ring 22, and by aid of a tightening nut 26 is braced against the collar ring 22. This clamping produces both a thermally and an electrically good transition from the internal tube 11 to the .supporting device.
  • Cooling tubes 27 pass through the tapered shank 24 and a cooling medium is directed therethrough.
  • a lower edge 30 of the screw collar ring 22 protrudes beyond the annular space between the two melting tubes 11 and 12, and is at the same height with the lower edge 21 of the ring 15.
  • An annular funnel-shaped hopper 31 is formed between the rings 22 and 15 concentric with the tubes 11 and 12 and having an annular discharge 33 intermediate the rings 11 and 12 and narrower than the space between them and into which material 32 to be molten is poured.
  • a heat insulating layer surrounds the outer tube and prevents excessive thermal losses.
  • the cross section through the material between the tu bes 11, 12, through which a current flows, is dimensioned so that the temperature of the internal tube 11, where it makes contact with the material to be molten, is higher than the melting temperature of such material.
  • the section close to the uppermost contact point at the base of the cone 3211 of poured material has the highest temperature. This simply means that the material to be molten is present as a melt and in this way make contact with the total surface of the internal tube 11.
  • the best possible heat transfer to the material is created; thus the best thermal yield is obtained from 'the energy transformed in the internal tube 11.
  • the temperature regulation is very easy, the nelt from the inlet to the outlet nozzles 14 passes over a long enough path as a melt so that it will become degassed and fined.
  • the thermal balance shows different values, so that only the lower section which surrounds closely the outlet nozzles will reach the melting temperature of the batch to be molten.
  • the temperature upwardly drops but at the base of the cone 32a it is still above the sintering temperature of the material to be molten.
  • the losses due to radiation towards the outside and the material to be employed for heat insulation remain within tolerable limits, and at the same time one prevents the batch sintering in the annular space between the tubes into the shape of large lumps, which would stop the flow of material and cause a ruination of the urnace, or at least a stoppage thereof.
  • the temperature at the outlet nozzles 14 is in the range of 1400 C. to 1500 C.
  • the hottest spot of the internal cylinder lies close to the base of the cone of poured material and is about 1600 C.
  • the critical temperature at which the noble metal becomes alloyed With the ignoble metal of the supporting device will be about 600 C. Therefore one must bring about orcefully inside the internal tube 11 a temperature drop of about 1000 C. in the region of the freely standing cone 32a of poured material. The conditions for the handling of the outer tube are not so complicated.
  • the heat which flows from the supporting device goes automatically upwardly and will then become exploited for the preheating of the material in the funnel tube (not shown), and this too is a feature beneficial for the overall performance of the melting furnace.
  • the melting furnace 38 consists essentially of two concentrical, vertical tubes 11, 12 from a noble metal of a high melting point, preferably Pt or a Pt alloy.
  • the two tubes 11, 12 at their lower ends are connected with each other in an electrically conducting manner, and are equipped with a crown of outlet nozzles 14 for the molten goods.
  • the internal tube 11 and the external tube 12 at their upper ends are each attached to a supporting device in the manner heretofore described and in this way are kept coaxial.
  • the supporting device of the external tube includes the ring 15 around which a thrust collar 19 is placed.
  • An electric lead 20 is Secured to the thrust collar 19.
  • the removal tube 43 for the coolant is guided concentrically inside the internal tube to the lower end thereof and protrudes below beyond the opening of the internal tube 11, so that it may support an annular ditfuser discharge nozzle 44.
  • This discharge nozzle 44 consists of the internal body 45 with rotation symmetry, -which is attached at the lower end of the discharge tube 43, and which has the shape of an urn, with a rounded-off, upper edge covered by a lid or plate 46. Between the edge of the urn structure and the lid 46 is defined an annular slot 47 for the removal of the heated cooling gas.
  • the inside of the internal body 45 of the discharge nozzle is connected to the inside of the removal tube 43 by a plurality of holes 48 in the tube wall.
  • the external 'body of the discharge nozzle 44 is made up of a cylindrical annular sheath 49 which surrounds the internal body 45 in spaced relation.
  • a jacketing 50 ⁇ is located beyond and above the upper edge of the sheath 49 to define an annular slot 51. If the external supporting ring 15 is equipped With cooling Channels, then this air too, which became preheated in this external supporting device, may be drected to the ditfuser discharge nozzle 44.
  • the molten material is first suoked in in the form of filaments and then, by means of turbulence, is separated into many individual filaments of very small diameter.
  • the flow velocity is considerably diminished thereby improving the eficiency of the areodynamic effect.
  • an improved melting furnace consists essentially of the two concentric, vertical tubes 11', 12' which are similar to the tubes 11, 12 heretofore described except as t-o the manner of jointer at their lower ends. At their lower edges the two tubes 11', 12' are connected to each other in an electrically conducting manner, as by a ring or rim 65 provided with a plurality of outlet openings 14' for the molten goods.
  • a collecting funnel 66 is placed at the lower edge of the outer tube 12. This funnel 66 catches the melted streams which leave the outlet openings 14', combines them and discharges them at its outlet 67 as a common flow of melt.
  • the diameters of the outlet openings 14' thereby are dimensioned so that the melt runs out of the furnace solely under the action of gravity; there is no nozzle effect.
  • For melts of ordinary glass a diameter of about 2 mm. and more was found suitable for the discharge openings 14'.
  • it may be surrounded by a thermal insulation.
  • the flow of melt which leaves the outlet 67 of the funnel 66 may be passed into a processing machine, as this is commonly done.
  • a melting furnace of the type having direct electrical resistance heating for melting material and formed by vertically arranged concentric tubes defining electrodes, the tubes making conducting contact at their lower ends and provided with discharge nozzles at their junction, an annular space being defined between the tubes to accommodate the material to be melted; the improvement wherein the inner tube is generally cylindrical, and the outer tube is defined by generally cylndrical portions at its upper and lower ends interconnected by an intermediate funnelshaped portion so that the temperature of the internal tube along the full region at which it makes contact with the material to be melted is equal to or higher than the melting temperature of the material, and the temperature of the external tube in all of the region where it makes contact with the material to be melted is higher than the sintering temperature of the material, and in the region of the discharge nozzles the material will reach at least the melting temperature.
  • a melting furnace of the type having direct electrical resistance heating for melting materials and fonmed by vertically arranged concentric tubes defining electrodes, the tubes making conducting contact at their lower ends and provided with discharge nozzles at their junction, an annular space being defined between the tubes to accommodate the material to be melted;
  • a melting furnace of the type having direct electrical resistance heating for melting material and formed by vertically arranged concentric tubes defining electrodes, the tubes making conducting contact at their lower ends and provided with discharge nozzles at their junction, an annular space being defined between the tubes to accommodate material to be melted; the improvement comprising blast nozzles for directing a flow of fluid into the flow of molten material from said discharge nozzles, cooling means for the upper end of at least one of said tubes where it is supported, and a removal line from said cooling means extending through the inner one of said tubes and through the lower end thereof connected to said blast nozzles to serve as a supply line for the blast air to said blast nozzles.
  • a melting furnace of the type having direct electrical resistance heating for melting materials and formed by vertically arranged concentric tubes defining electrodes, the tubes making conducting contact at their lower ends and provided -with discharge nozzles at their junction, an annular space being defined between the tubes to accommodate the material to be melted; the improvement defining a blast nozzle below said discharge nozzles for directing a flow of fluid into the outflow of molten material from said outflow nozzles, means for providing blast fluid to said blast nozzle, a hollow symmetrical hub being provided with an annular slot, and an annular sheath encirclin-g said hub' to form a diffuser nozzle which is common to all the furance discharge nozzles.
  • a mixing furnace of the type having direct, electrical resistance heating for melting materials and formed by vertically arranged concentric tubes defining electrodes, the tubes making conducting contact at the lower ends and provided with discharge nozzles at their junction, an annular space being defined between the tubes to accommodate the material to be melted;
  • the improvement including a blast nozxzle for directing a flow of fluid into the outflow of molten material from said discharge nozzles, said blast nozzles including a removal line extending through the inner one of said tubes and protruding below the outflow nozzles of the melting furnace, said removal line being closed at its bottom end and provided with a plurality of bores spaced across the periphery of its cylindrical wall and located at approximately the height of said discharge nozzles.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Manufacturing & Machinery (AREA)
  • Furnace Details (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Spinning Methods And Devices For Manufacturing Artificial Fibers (AREA)
US625153A 1966-03-25 1967-03-22 Electric furnace Expired - Lifetime US3419667A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DEW41224A DE1293399B (de) 1966-03-25 1966-03-25 Schmelzeinrichtung mit direkter elektrischer Widerstandsheizung zur Herstellung von Faeden und Fasern aus vorzugsweise hochschmelzbaren Stoffen
DEW41713A DE1293972B (de) 1966-03-25 1966-06-01 Schmelzeinrichtung mit direkter elektrischer Widerstandsheizung fuer vorzugsweise hochschmelzbare Stoffe
DEW41774A DE1293973B (de) 1966-03-25 1966-06-10 Schmelzeinrichtung mit direkter elektrischer Widerstandsheizung zur Herstellung von Faeden und Fasern aus vorzugsweise hochschmelzbaren Stoffen

Publications (1)

Publication Number Publication Date
US3419667A true US3419667A (en) 1968-12-31

Family

ID=27213461

Family Applications (1)

Application Number Title Priority Date Filing Date
US625153A Expired - Lifetime US3419667A (en) 1966-03-25 1967-03-22 Electric furnace

Country Status (5)

Country Link
US (1) US3419667A (de)
BE (1) BE695928A (de)
DE (3) DE1293399B (de)
GB (1) GB1185194A (de)
NL (1) NL6704389A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112321135A (zh) * 2020-09-28 2021-02-05 江苏孚日玻璃科技有限公司 一种环保节能保温的玻璃窑炉及其工作方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2233435A (en) * 1938-02-26 1941-03-04 Owens Corning Fiberglass Corp Glass stock for electric melting
US2350829A (en) * 1939-05-25 1944-06-06 Scharfnagel Rudolf Molten glass extruding apparatus
US2600490A (en) * 1947-04-21 1952-06-17 Corning Glass Works Glass melting method
US2680772A (en) * 1950-12-02 1954-06-08 Ferro Corp Method for producing porcelain enamel
US3109045A (en) * 1958-03-03 1963-10-29 Owens Illinois Glass Co Electrically heated glass melting unit
US3212871A (en) * 1960-12-16 1965-10-19 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Electrically heated tank furnace for melting quartz
US3230291A (en) * 1963-04-16 1966-01-18 Walz Alfred Electric furnace

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2233435A (en) * 1938-02-26 1941-03-04 Owens Corning Fiberglass Corp Glass stock for electric melting
US2350829A (en) * 1939-05-25 1944-06-06 Scharfnagel Rudolf Molten glass extruding apparatus
US2600490A (en) * 1947-04-21 1952-06-17 Corning Glass Works Glass melting method
US2680772A (en) * 1950-12-02 1954-06-08 Ferro Corp Method for producing porcelain enamel
US3109045A (en) * 1958-03-03 1963-10-29 Owens Illinois Glass Co Electrically heated glass melting unit
US3212871A (en) * 1960-12-16 1965-10-19 Patent Treuhand Ges Fuer Elektrische Gluehlampen Mbh Electrically heated tank furnace for melting quartz
US3230291A (en) * 1963-04-16 1966-01-18 Walz Alfred Electric furnace

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112321135A (zh) * 2020-09-28 2021-02-05 江苏孚日玻璃科技有限公司 一种环保节能保温的玻璃窑炉及其工作方法

Also Published As

Publication number Publication date
GB1185194A (en) 1970-03-25
DE1293399B (de) 1969-04-24
NL6704389A (de) 1967-09-26
BE695928A (de) 1967-09-01
DE1293973B (de) 1969-04-30
DE1293972B (de) 1969-04-30

Similar Documents

Publication Publication Date Title
US3580976A (en) Device for regulating the temperature of glass at the outlet of a very high temperature glass melting furnace
US3260587A (en) Method of melting glass with submerged combustion heaters and apparatus therefor
US5123941A (en) Apparatus for producing mineral wool
US2244267A (en) Electric furnace
US3212871A (en) Electrically heated tank furnace for melting quartz
SE8006744L (sv) Stralningspanna
EP0369642A2 (de) Verfahren zum Schmelzen von Stoffen
US3429972A (en) Very high temperature electric melting furnace
US2754346A (en) Glass melting furnace
US2814657A (en) Method and apparatus for heating glass
US3511916A (en) Electric resistance bushing for forming glass fibers
US4592770A (en) Glass melter
US4504302A (en) Homogenizing apparatus glass making furnace and method of homogenizing glass
US3147328A (en) Electric glassmaking furnace
US3524206A (en) Method and apparatus for melting thermoplastic materials
US3419667A (en) Electric furnace
US3636293A (en) Method and apparatus for melting vitreous-type materials
US5112378A (en) Bottom outlet device for a glass melting furnace
US3663192A (en) Glass melting pot
JPS5818083A (ja) プラズマ溶解炉
US2455908A (en) Method of making glass fibers
US3340415A (en) Induction gas ionizer having a rotatable envelope
US4217082A (en) Spin cup means for the production of metal powder
US3508900A (en) Quartz melting and tube forming furnace
US3230291A (en) Electric furnace