US3830950A - Rotary furnaces of the plasma-arc heating type - Google Patents

Rotary furnaces of the plasma-arc heating type Download PDF

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Publication number
US3830950A
US3830950A US00401230A US40123073A US3830950A US 3830950 A US3830950 A US 3830950A US 00401230 A US00401230 A US 00401230A US 40123073 A US40123073 A US 40123073A US 3830950 A US3830950 A US 3830950A
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United States
Prior art keywords
furnace
plasma
enclosure
plate member
ring member
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Expired - Lifetime
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US00401230A
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English (en)
Inventor
H Schoumaker
D Yerouchalmi
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Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
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Commissariat a lEnergie Atomique CEA
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    • 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
    • F27D11/04—Ohmic resistance heating with direct passage of current through the material being heated
    • 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
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories or equipment specially adapted for rotary-drum furnaces
    • F27B7/34—Arrangements of heating devices

Definitions

  • the present invention is concerned with the construction of a leak-tight lock-chamber placed at least at one end of the rotary furnace in order to permit the introduction of a controlled atmosphere into said furnace.
  • Said device is particularly well suited to the plasma-arc furnace claimed in French Patent No. 1,526,999 in the name of Commissariat a IEnergie Atomique.
  • the difficulty lies in the fact that the furnace rotates about an axis whereas the lock-chamber must be stationary in order to permit the admission of the gas mixture.
  • Leak-tightness between the stationary portion and the rotating portion must achieve a particularly high standard since it has to be maintained between two different gases, namely on the one hand the gas mixture and on the other hand the cooling water vapor. Since the temperature conditions are very severe, it is very difficult to use a frictional bearing disc.
  • This invention is particularly directed to an improvement in rotary plasma-arc furnaces and is distinguished by the fact that the furnace is provided at each end with a chamber placed opposite to the moving enclosure of said furnace. Each chamber abuts a casing attached to the stationary enclosure is made leak-tight with respect to the moving enclosure by means rigidly fixed to the stationary enclosure so as to form a continuous gas curtain between said means and a front plate attached to the moving enclosure, a clearance being provided between said means and said plate.
  • the means for forming the gas curtain includes at least one torus havingthe same axis as the furnace, each torus being rigidly fixed to one end of a shell whilst the other end of said shell is rigidly fixed to the stationary enclosure.
  • Each toms is partially housed within a portion of the front plate which has a concave surface of revolution, at least one of the tori being provided, on that surface which faces said plate, with calibrated orifices.
  • Each torus is further provided with pipes for the admission of gas into each torus at a pressure which is higher than the pressure existing within said chamber.
  • a gas jet under pressure is produced between the moving portion and the stationary portion of the furnace.
  • the gas employed is either identical with the gas to be injected into the fumace or compatible with the latter. This accordingly avoids the need for any friction seal which would in any case not ensure a sufficient degree of leak-tightness against the gases employed and which would further result in an increase in the energy required for setting the furnace in rotation.
  • FIG. 1 is a partial external view, partially in crosssection showing part of the furnace in accordance with the invention
  • FIG. 2 shows a number of alternative forms of construction of the dynamic seal.
  • FIG. 1 shows the main constructional features of the rotary furnace of the plasma-arc heating type as described in French Patent No. l,526,999 cited in the foregoing.
  • said furnace comprises a stationary enclosure 1 and a moving enclosure 2 rotatably mounted within said enclosure 1 on bearings such as 3 which are carried by the latter.
  • the moving enclosure 2 has a substantially cylindrical central portion, the ends of which terminate in conical portions. Only one conical portion 15 is shown in the drawing in order to avoid complication of the illustration whilst the other end is identical with the first except for a few secondary details.
  • a crown-wheel 4 provided with a set of teeth 5 disposed in meshing engagement with a bevel pinion 6 which is fixed on the end of a driving shaft 7.
  • Said shaft is driven in rotation about its own axis by driving means (not shown in the drawings) and rotatably mounted on support bearings 8 and 9 which are mounted within a guide sleeve 10, said sleeve being rigidly fixed on a frame 11 which is attached to the stationary enclosure 1.
  • External cooling of the stationary enclosure 1 and of the moving enclosure 2 is carried out by means of a manifold 12 which is supplied in particular with water under pressure through connectingpipes 13.
  • Said manifold 12 is intended to deliver the water contained therein into spray tubes 14 so as to cause said water to circulate between the conical end portion 15 of the moving enclosure 2 and a front plate 16 which is substantially perpendicular to the axis of rotation of said enclosure.
  • Said front plate 16 is rigidly fixed to the corresponding end of said moving enclosure.
  • the stationary enclosure 1 has a sheet-metal extension 18 of generally cylindrical shape and rigidly fixed to said enclosure 1.
  • the chamber is closed by a plate 19 which is attached to the sheet-metal extension 18.
  • a cylindrical shell 22 is rigidly fixed to the plate 19.
  • Said shell 22 terminates at the end which is not attached to the plate 19 in a hollow torus 23 which thus completely surrounds the nose 21 of the furnace 2.
  • the plate 16 is provided along its periphery with a surface 24 having a conical shape and the torus 23 is engaged in the opening of said concave surface without coming into contact with the latter.
  • the torus 23 is provided with calibrated orifices such as 25 which are uniformly spaced over that portion of surface of said torus which faces the concave surface 24.
  • the hollow torus 23 is further provided with a gas admission pipe 26 which passes through the plate 19.
  • the leak-tight chamber 20 is defined n the one hand by the plate 16 rotates with the furnace 2, and on the other hand by the shell 22 and the torus 23 which are stationary since they are rigidly fixed to the plate 19.
  • the plate 1 is traversed by a pipe 27 for the admission of the gas or gas mixture which is intended to form the atmosphere of the furnace and by the plasma gun 28, this latter being fitted with a static seal 29 which is secured to the plate 19.
  • Cooling pipes 30 are also placed on the external face of the plate 19.
  • FIG. 2 shows a number of alternative designs of said torus 23.
  • the torus has a circular cross-section as in FIG. 1.
  • the torus 23 also has a circular crosssection but is provided on that face which is located opposite to the surface 24 with splines 31 formed between the orifices 25 of the torus 23. Said splines thus form the equivalent of baffles and the seal thus provided is even further enhanced.
  • FIG. 2c shows a torus having an oval cross-section.
  • the sealing system comprises on the one hand a torus 23 which is identical with the torus described in the foregoing and on the other hand, a second torus 23' which is provided in addition with a deformable wall 32 without any orifice. Said second torus is fitted with a pipe 26 for the admission of gas under pressure. Said second torus 23' cooperates with a second concave surface 24 which is formed in the front plate 16.
  • the operation of the sealing device which is shown in FIG. 2d is as follows: when the furnace is being rotated, only the torus 23' is supplied with gas, with the result that a gas curtain is thus formed and ensures leak-tightness.
  • the torus 23' When the torus 23' is put under pressure, its wall 32 is deformed and comes into intimate contact with the portion 24 of the front plate 16, thus forming a seal between the lock-chamber and the remainder of the enclosure.
  • this mode of operation serves to provide a static seal which is favorable both to the production of a vacuum and to the removal of gases contained in the charge.
  • the torus 23' serves to regulate the leakage flow rate of the gas which is discharged from the torus 23.
  • the gas which is injected into the tori 23 can be either identical with the gas which is introduced through the pipe 27 into the lock-chamber 20 and which will therefore constitute the atmosphere of the furnace or may altematively be different but must nevertheless remain compatible with the first gas.
  • the pressure of the gas injected into the torus 23 is slightly higher than that which prevails within the enclosure 1 and within the lock-chamber 20. There is thus no leakage of gas from the enclosure 1 to the lock-chamber 20.
  • the sealing device could also be very readily constituted by two coaxial tori which are identical with the torus 23 and cooperate with two portions of concavesurface 24.
  • a plasma-arc furnace comprising:
  • a rotatable cylindrical furnace body having an opening in at least one end thereof adapted to admit a plasma arc
  • a plasma heat source mounted in said stationary enclosure for generating the plasma arc
  • annular plate member secured to said end of said cylindrical portion and surrounding said opening
  • sealing means mounted within said stationary enclosure for ejecting a gas directly against said plate member to form a fluid seal therewith.
  • a plasma-arc furnace comprising:
  • a rotatable cylindrical furnace body having an opening in at least one end thereof adapted to admit a plasma arc
  • a plasma heat source mounted in said stationary enclosure for generating the plasma arc
  • annular plate member secured to said end of said cylindrical portion and surrounding said opening, said plate member having a circumferential groove in a surface facing said stationary enclosure;
  • sealing means comprising a toroidal ring member mounted within said stationary enclosure and having a portion thereof situated within said groove in said plate member in a spaced relationship therewith;
  • At least one orifice in said ring member for ejecting said gas against said plate member to form a fluid seal therewith.
  • a second toroidal ring member having a portion thereof situated within said second groove in a spaced relationship therewith, said ring member having a deformable surface adjacent to said second groove, and means for urging said deformable surface into contact with said plate member.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Furnace Details (AREA)
  • Plasma Technology (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
US00401230A 1972-10-06 1973-09-27 Rotary furnaces of the plasma-arc heating type Expired - Lifetime US3830950A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR7235622A FR2202583A5 (enrdf_load_stackoverflow) 1972-10-06 1972-10-06

Publications (1)

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US3830950A true US3830950A (en) 1974-08-20

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US00401230A Expired - Lifetime US3830950A (en) 1972-10-06 1973-09-27 Rotary furnaces of the plasma-arc heating type

Country Status (7)

Country Link
US (1) US3830950A (enrdf_load_stackoverflow)
AU (1) AU6093373A (enrdf_load_stackoverflow)
BE (1) BE805312A (enrdf_load_stackoverflow)
CA (1) CA995984A (enrdf_load_stackoverflow)
DE (1) DE2349926A1 (enrdf_load_stackoverflow)
FR (1) FR2202583A5 (enrdf_load_stackoverflow)
GB (1) GB1435793A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937866A (en) * 1973-10-17 1976-02-10 La Soudure Electrique Autogene, Procedes Arcos Process of striking an arc for a plasma beam inside an enclosure and a stick-electrode for carrying out the process
US4037043A (en) * 1975-04-16 1977-07-19 Tibur Metals, Ltd. Extended arc furnace and process for melting particulate charge therein
US4217479A (en) * 1977-04-29 1980-08-12 Swiss Aluminium Ltd. High temperature reactor
US4220843A (en) * 1977-04-29 1980-09-02 Swiss Aluminium Ltd. Process for melting material
US4443186A (en) * 1982-04-14 1984-04-17 The United States Of America As Represented By The United States Department Of Energy Solar heated rotary kiln
US5382002A (en) * 1993-10-08 1995-01-17 Evans; Marvin Apparatus for heat treating a particulate material
US5798496A (en) * 1995-01-09 1998-08-25 Eckhoff; Paul S. Plasma-based waste disposal system
US5808267A (en) * 1995-01-09 1998-09-15 Eckhoff; Paul S. Plasma gun with gas distribution plug

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE8306107D0 (sv) * 1983-11-07 1983-11-07 Skf Steel Eng Ab Tetningsanordning
CN114440622B (zh) * 2022-01-17 2024-01-26 上海应用技术大学 回转窑窑体及采用燃料再燃技术降低水泥回转窑NOx的方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3286012A (en) * 1963-04-11 1966-11-15 Centre Nat Recherche Apparatus for treating materials at high temperatures
US3697660A (en) * 1970-03-16 1972-10-10 Jury Fedorovich Frolov Device for sealing gap between electrode and lining of electric arc furnace

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3286012A (en) * 1963-04-11 1966-11-15 Centre Nat Recherche Apparatus for treating materials at high temperatures
US3697660A (en) * 1970-03-16 1972-10-10 Jury Fedorovich Frolov Device for sealing gap between electrode and lining of electric arc furnace

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3937866A (en) * 1973-10-17 1976-02-10 La Soudure Electrique Autogene, Procedes Arcos Process of striking an arc for a plasma beam inside an enclosure and a stick-electrode for carrying out the process
US4037043A (en) * 1975-04-16 1977-07-19 Tibur Metals, Ltd. Extended arc furnace and process for melting particulate charge therein
US4217479A (en) * 1977-04-29 1980-08-12 Swiss Aluminium Ltd. High temperature reactor
US4220843A (en) * 1977-04-29 1980-09-02 Swiss Aluminium Ltd. Process for melting material
US4443186A (en) * 1982-04-14 1984-04-17 The United States Of America As Represented By The United States Department Of Energy Solar heated rotary kiln
US5382002A (en) * 1993-10-08 1995-01-17 Evans; Marvin Apparatus for heat treating a particulate material
US5798496A (en) * 1995-01-09 1998-08-25 Eckhoff; Paul S. Plasma-based waste disposal system
US5808267A (en) * 1995-01-09 1998-09-15 Eckhoff; Paul S. Plasma gun with gas distribution plug

Also Published As

Publication number Publication date
FR2202583A5 (enrdf_load_stackoverflow) 1974-05-03
BE805312A (fr) 1974-01-16
CA995984A (en) 1976-08-31
DE2349926A1 (de) 1974-04-11
GB1435793A (en) 1976-05-12
AU6093373A (en) 1975-04-10

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