US3743753A - Electrical ceiling heating in tunnel kilns - Google Patents

Electrical ceiling heating in tunnel kilns Download PDF

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Publication number
US3743753A
US3743753A US00212406A US3743753DA US3743753A US 3743753 A US3743753 A US 3743753A US 00212406 A US00212406 A US 00212406A US 3743753D A US3743753D A US 3743753DA US 3743753 A US3743753 A US 3743753A
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United States
Prior art keywords
kiln
fingers
heating
tunnel
electrical ceiling
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Expired - Lifetime
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US00212406A
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English (en)
Inventor
F Petzi
H Baumann
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Individual
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Individual
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Publication of US3743753A publication Critical patent/US3743753A/en
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    • 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
    • H05B3/62—Heating elements specially adapted for furnaces
    • H05B3/66—Supports or mountings for heaters on or in the wall or roof

Definitions

  • ABSTRACT [30] Foreign Application Priority Data
  • An electrical heating device in a tunnel kiln comprises NOV. 10, 1971 Germany P 21 55 a plurality of U- or U- haped heating elements disposed transversely across the top of the tunnel.
  • the US. Cl. elements are only upported at each end III".
  • Cl. members of aluminiferous material about the Fleld of Search bends of the elements are looped The elements are inclined inwardly towards the center of the References Cited tunnel at an angle of 10 to the vertical.
  • the invention relates to electrical ceiling heating in tunnel kilns for the ceramic industry by means of heating elements bent in U-shaped configuration, more especially in double U-shaped configuration, which extend transversely to the longitudinal walls of the kiln.
  • the heating elements used for producing high temperatures are formed from bare unprotected heat conductors which have only slight strength and tend to break easily. On account of these characteristics it is customary to arrange ceramic supporting plates under the heating elements in the ceiling of the kiln and to rest the heating elements loosely on these supporting plates. It is also customary not to place the heating conductors directly onto the ceramic plates, but onto loose grains of highly aluminiferous material, which grains are expressly placed on the ceramic plates so that the heating conductors can contract and expand due to thermal effects in a substantially unhindered manner.
  • a disadvantage in the known type of design of the electrical tunnel kiln ceiling heating is that, for heating the material to be fired, by way of example for sintering electrical and magnetic materials, the heat conductors have to provide, from above, not only the useful heat for the firing of the material, but also the heat which is required to overcome the thermal insulation of the supporting plates. Apart from the necessity of having to supply the heat loss caused by the supporting plates, the supporting plates cause in addition a temporal delay of the heat conduction and require, moreover, a higher temperature of the heating conductor than would be necessary if the heat could be directed directly from the heating conductor to the goods for firing. Preventing direct heating of the article to be fired from above, however, at least in the high temperature ranges, is the fact that here the intrinsic weight of the heating conductors is already likely to bring about too great a sagging of the conductors leading to destruction thereof.
  • the problem underlying the invention is to preclude in the case of electrical ceiling heating in tunnel kilns for the ceramic industry by means of heating elements bent in U-shaped configuration, more especially in double U-shaped configuration which extend transversely to the longitudinal walls of the kiln, the disadvantages which have hitherto been caused by the supporting plates which bear the heating elements.
  • the free ends of the fingers are inclined slightly towards the inner space of the kiln, by way of example have an angle of in relation to the perpendicular side walls of the kiln. Moreover, it is adviseable for the length of the freely upwardly projecting finger part to amount to at leastone-fifth of the clear width of the kiln channel.
  • the fingers are inserted with their lower ends securely held in a kiln brick.
  • the fingers it is advisable for the fingers to be shaped similarly to short pipe-pieces and for the kiln bricks receiving the fingers to be rounded downwards towards the kiln space from the front upper side. Due to this rounding the effect is that the heating conductors can carry out their own motions largely without resistance, more especially as they are not exposed to any mechanical attacks by points or edges.
  • the mounting, in accordance with the invention, of the electrical heating elements on the ceiling of the tunnel kiln produces, in addition to abolishing the disadvantages caused by the previous use of supporting plates, in addition the further advantages that the heating elements can be exchanged individually without having to interrupt the operation of the kiln. To exchange the elements it is sufficient to remove from the outside the stopper bricks at the heating element in question and to exchange this latter for a new heating element and to replace the stopper bricks.
  • FIG. 1 is a diagrammatic representation of an electrically heated sliding plate tunnel kiln, in longitudinal section;
  • FIG. 2 is a partial section, illustrating the side view of an installed heating conductor, through the tunnel kiln in accordance with FIG. 1;
  • FIG. 3 is a section along the line III-III in FIG. 2.
  • a tunnel kiln has, in known manner along its channel 1, a pre-heating zone A, a firing zone B and a cooling zone C.
  • Serving for the transportation of the articles to be fired from entrance end 2 to exit end 3' are sliding plates 4 which are moved along the channel 1, and thus conduct the article to be fired W (FIG. 2) which is carried by the plates 4, through the zones A, B and C.
  • an electrical ceiling heating which is formed from bare metal heating conductors 5 which are bent in double U-shaped configuration and which loop around, with their bends 6, 7 and 8, fingers 9, 10 and 11. In this way, they span the kiln channel 1 suspended in the air, so that the heat they produce arrives, without any hinderance, from above directly on the article W to the fired.
  • the fingers 9, l0 and 11 are designed in the shape of round tubes and consist of a highly aluminiferous material which does not react chemically with the material, of the heating elements 5, which softens at a high heating temperature on its upper surface.
  • the heating conductor does as expected expand and sag towards the center of the channel 1, as is indicated by the dot-dash double line 5 in FIG. 2, but the suspension of the heating conductors from the fingers along the heating section is maintained in such a way that, even in the case of a maximum sagging D, no contact takes place between the heating conductor and the article being fired.
  • the fingers 9, 10, 11 are inserted into the kiln bricks 13, 14, 15. Their free ends are slightly inclined towards the inner space 1 of the kiln by the angle a; they form, by way of example in relation to the perpendicular sidewalls 16, 17 of the kiln, an angle A of It has additionally proved to be favorable to dimension the length L of the freely upwardly projecting part of the fingers at least one-fifth as great as the clear width B of the kiln channel 1.
  • An electrical ceiling heating means in a tunnel kiln for the ceramic industry comprising: heating elements bent in U-shaped configuration and extending transversely between the longitudinal walls of the kiln across the tunnel, the regions of the bending points of the heating elements being supported relative to the longitudinal walls of the kiln, upwardly projecting fingers made of a highly aluminiferous material and supported by the longitudinal, walls of the kiln, the heating elements with their bends being looped around the fingers and spanning the kiln space free from other support, the free ends of the fingers being slightly upwardly inclined towards the inner space of the kiln at a 10 angle.

Landscapes

  • Resistance Heating (AREA)
  • Furnace Details (AREA)
  • Tunnel Furnaces (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)
  • Furnace Charging Or Discharging (AREA)
US00212406A 1971-11-10 1971-12-27 Electrical ceiling heating in tunnel kilns Expired - Lifetime US3743753A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2155838A DE2155838C3 (de) 1971-11-10 1971-11-10 Elektrische Deckenheizung an Tunnelofen

Publications (1)

Publication Number Publication Date
US3743753A true US3743753A (en) 1973-07-03

Family

ID=5824717

Family Applications (1)

Application Number Title Priority Date Filing Date
US00212406A Expired - Lifetime US3743753A (en) 1971-11-10 1971-12-27 Electrical ceiling heating in tunnel kilns

Country Status (7)

Country Link
US (1) US3743753A (de)
JP (1) JPS4855432A (de)
DE (1) DE2155838C3 (de)
FR (1) FR2166937A5 (de)
GB (1) GB1395591A (de)
IT (1) IT970348B (de)
NL (1) NL7214952A (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392052A (en) * 1981-04-03 1983-07-05 Bulten-Kanthal Ab Device for carrying electrical resistance elements

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2916846C2 (de) * 1979-04-26 1982-02-25 Ludwig Riedhammer GmbH & Co KG, 8500 Nürnberg Hochtemperaturofen
DE3019571C2 (de) * 1980-05-22 1982-07-01 Ludwig Riedhammer GmbH & Co KG, 8500 Nürnberg Hochtemperaturofen
FR2578966A1 (fr) * 1985-03-15 1986-09-19 Graniou Louis Four electrique a haute temperature dont les resistances disposees sous la voute sont des tubes conducteurs chauffants disposes en chainettes, maintenus en place par des suspentes refrigerees
AT17549U1 (de) * 2021-05-19 2022-07-15 Plansee Se Halteelement für einen hochtemperaturofen

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1547000A (en) * 1925-07-21 Electbic furnace
US1864334A (en) * 1927-03-10 1932-06-21 Electric Furnace Co Metallic resistor for electric furnaces
US2264716A (en) * 1940-02-21 1941-12-02 Westinghouse Electric & Mfg Co Electric furnace

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1547000A (en) * 1925-07-21 Electbic furnace
US1864334A (en) * 1927-03-10 1932-06-21 Electric Furnace Co Metallic resistor for electric furnaces
US2264716A (en) * 1940-02-21 1941-12-02 Westinghouse Electric & Mfg Co Electric furnace

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4392052A (en) * 1981-04-03 1983-07-05 Bulten-Kanthal Ab Device for carrying electrical resistance elements

Also Published As

Publication number Publication date
JPS4855432A (de) 1973-08-03
NL7214952A (de) 1973-05-14
IT970348B (it) 1974-04-10
DE2155838C3 (de) 1979-12-06
FR2166937A5 (de) 1973-08-17
DE2155838B2 (de) 1979-04-19
GB1395591A (en) 1975-05-29
DE2155838A1 (de) 1973-05-17

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