US2278275A - Seal for furnace openings - Google Patents

Description

V. E. M DONELL SEAL FOR FURNACE OPENINGS Filed June 19. 1941 VERNON E. MACDONELL ATTORNEYS Patented Mar. 31, 1942 SEAL FOR FURNACE OPENINGS Vernon E. MacDonell, Metuchen, N. J., assignor to International Smelting and Refining Company, a corporation of Montana Application June 19, 1941, Serial No. 398,710

9 Claims.

This invention relates to apparatus for sealing an aperture in a furnace or the like, and more particularly to apparatus for sealing a slot through which solid articles are charged into or withdrawn from a furnace. The invention has for its principal object the provision of an improved mechanical seal for apertures in furnaces and the like to prevent the escape of a special gas atmosphere maintained within the furnace, or the undesirable entry of air into the furnace, when a solid article is passed through the aperture.

Furnace openings and the like must be provided with seals for eficient and proper operation whenever a special gas atmosphere is maintained within the furnace, or whenever the entry of the outside atmosphere into the furnace should be prevented. Well-fitting mechanical seals are particularly desirable when close control of the composition of the furnace atmosphere is important.

The ideal mechanical seal is one which will conform to ordinary variations in the size and shape and to surface irregularities of the articles being passed through the aperture. Various mechanical furnace aperture seals have been proposed or used heretofore, but such seals have been far from adequate, especially for providing a closely fitting seal during the charging of articles such as copper cathodes which have very irregular surfaces. Mechanical seals provided by sliding doors or the like are unsatisfactory because the doors are of predetermined size and are frequently considerably higher and wider than the height and width of the articles being introduced into (or withdrawn from) the furnace. Furthermore, sliding doors must be opened slightly wider than the overall size of the article in order to permit it to pass unhindered through the furnace aperture. Flexible mechanical closures such as asbestos flaps and the like have the disadvantage that they also expose a larger portion of the furnace aperture than is required by the actual size of the article being charged to the furnace. Such flexible closures are opened by forcing the article through them, and hence the opening made is generally at leastas large as the maximum overall dimensions of the article. Moreover, the presence of sharp projections or other surface irregularities on metallic articles being passed through such a seal causes considerable mechanical damage to the relatively soft flexible seal material. Chain seals or closures, composed of chains hanging down across the furnace aperture, are adequately flexible and durable, but theopenings in the links of the chains permit quite free flow .of gases into or out of the furnace.

The present invention provides a mechanical seal for furnace apertures, and particularly for slots in furnaces and the like through which relatively thin solid articles are to be passed, which closely approaches the requirements, of an ideal mechanical seal. The new mechanical seal is especially suitable for sealing apertures through which articles such as copper cathodes having extremely irregular surfaces are to be passed. The sealing apparatus of the invention comprises a generally tubular member formed with a relatively wide slot extending lengthwise thereof and adapted to be mounted across the face of the aperture to be sealed. A plurality of relatively thin flat elements are positioned face to face within the tubular member throughout substantially the length of the slot therein. The flat elements are of such size and are so arranged as to be capable of projecting outwardly through the slot, and further are capable of movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member. The tubular member and the projecting portions of the flat elements together provide the seal for the furnace aperture. When a solid article is passed through the seal, the projecting portions of the fiat elements are pressed part way into the tubular member, and assume positions corresponding to the surface irregularities of the article. As a result a closely fitting seal is maintained even during passage of the article through the furnace aperture.

Advantageously the slotted tubular member is generally cylindrical, and the thin flat elements advantageously are in the form of thin discs or annular (washer-like) elements. The diameter of the discs or annular elements relatively to the inner diameter of the tubular member and to the width of the slot preferably is such that the discs are capable of limited movement in a direction perpendicular to the axis of the tubular member and are capable of projecting part way through the slot therein, but are incapable of being withdrawn completely from the tubular member through the slot. In using thin flat annular (washer-like) elements, it is advantageous to extend a retaining rod through the openings therein, and to secure the retaining rod at the ends of the tubular member, so as to prevent accidental loss of any annular element from within the tubular member. The diameter of the retaining rod should of course be sufficiently smaller than the diameter 'of the openings in the thin flat annular elements so thattheilatter will have sufficient freedom forlimited movement perpendicularly to the axis of the tubular member and relatively to one .another.

The invention will be understood more clearly from the following detailed descriptionof a specific embodiment considered .in conjunction with the accompanying drawing in which Fig. 1 is a longitudinal section through a fur-- nace having an aperture equipped with a mechanical seal according to the invention;

Fig. 2 is a vertical section showing details of the mechanical seal in position adjacent a furnace aperture; and

Fig. 3 is a side view, partly in section, of the mechanical seal shown in Fig. 2.

The new mechanical seal S is shown in Fig. 1 applied to the charging slot 5 of the fuel-fired muiile furnace having a melting chamber 6 separated from a combustion chamber 1 by a refractory arch 8. The melting chamber has a bottom or floor Ill and an end wall II of refractory construction. Fuel is introduced into the combustion chamber through a burner I2. In this type of furnace the fuel is burned in the combustion chamber so as to heat the arch 8 to an elevated temperature for supplying radiant heat to the melting chamber 6. When a suitable non-oxidizing or reducing gas atmosphere is maintained in the melting chamber IS, a furnace of the type shown is particularly adapted for melting relatively pure copper shapes such, for example, as copper cathodes, and the invention will be described herein, for purposes of illustration, with respect to the sealing of the cathode charging slot of this type of furnace.

The copper cathodes C are introduced into the melting chamber 6 of the furnace through the charging slot 5 located in the furnace end wall II. In charging, the cathodes are deposited on an inclined rack I3 and are pushed downwardly along the rack through the charging slot 5 and on to an inclined table or ledge 14 located within the furnace under the heating arch 8. As additional cathodes are charged to the furnace each cathode is pushed by those behind it downwardly along the rack through the charging slot and on to the ledge I4. The sealing apparatus, or mechanical seal S is appropriately secured to the outside of the furnace structure adjacent the charging slot 5.

The seal comprises a generally cylindrical tubular member or pipe I5 secured, as by screws IE, to an angle iron H. The angle iron in turn is mounted appropriately on the outside of the furnace structure immediately above the charging slot 5. The cylindrical member 15 preferably is sufiiciently long to extend at least the full width of the charging slot 5, and should in any event be as long as the cathodes to be charged are wide. Eye-bolts I8 are secured to the cylindrical member I5 through one leg of the angle iron I! to facilitate handling of the sealing apparatus.

The cylindrical member I5 is formed with a relatively wide, longitudinally extending slot 20. Such a slot may be formed by cutting a longitudinal segment from the lower portion of the cylindrical member. The inner edges of the slot are preferably cut away as shown in Fig. 2 so as to provide relatively flat surfaces on the interior of the cylindrical member in the vicinity of the slot 20.

The cylindrical member I5 is mounted adjacent the charging slot 5 so that the longitudinal slot 20 faces the inclined rack I3. A plurality of thin annular elements or washers 2|, each of a diameter slightly greater than the width of the slot 20 but less than the inner diameter of the cylindrical member l5, are positioned face to face within the cylindrical member throughout substantially its entire length. Since the diameter of the washers 2| is slightly greater than the width of the slot 20,the washers lie for the most part within the cylindrical member, and are held from falling out by the cylindrical member at the edges of the slot 20. A portion of each washer 2|, however, is capable of projecting a substantial distance through the slot 20, and the washers are free to move edgewise and substantially independently of one another to a limited extent into and out of the interior of the cylindrical member I5. The cylindrical member advantageously is mounted in such a position that the Washers 2|, in their extreme projecting position, make contact with the surface of the inclined rack I3, and thus completely seal off the charging slot 5.

The washers 2| are assembled face to face, preferably over the full length of the charging slot 5, with just suflicient clearance-between'them to allow for thermal expansion to occur without preventing free rise and fall within the limits required by the thickness of the copper cathodes charged through the slot 5.

As the longitudinal slot 20 in the cylindrical member I5 is at about the same angle to the horizontal as the inclined rack I3, the washers 2| tend to fall against the relatively fiat surface of the lower edge E of the slot 20, so that contact is maintained at all times between the washers and the cylindrical member. Such contact is of value for maintaining continuity of the seal regardless of the vertical position of the washers.

The washers 2| are further held in position within the cylindrical member I5 by means of a retaining rod 22 extending through the central hole in each washer. The diameter of the rod 22 is sufficiently smaller than the diameter of the holes through the washers 2| so as not to interfere with the desired limited movement of the washers relatively to one another. The rod 22 is held in place by means of plugs 23 mounted at each end of the cylindrical member I5 and through which the ends of the rod project. The rod 22 prevents any accidental dropping of the washers through the slot 20 if the cylindrical member I5 becomes warped or if the slot 20 otherwise is caused to open too wide. If desired, the rod 22 may be employed as the principal means for retaining the washers 2| in place, and its use permits of making the slot 20 wider than could otherwise be done safely.

It is apparent from the foregoing that the new mechanical seal is adapted to conform, across the entire width of the charging slot 5, with the shape of the copper cathodes being passed therethrough and with any surface irregularities on the face of the cathodes. The washers which project downwardly along the sides of the copper cathode maintain a seal across the face of the unoccupied portion of the charging slot 5, while the washers in contact with the surface of the copper cathode provide a mechanical seal which conforms closely at all times to the irregular surfaces of the cathodes. In the specific embodiment of the invention described hereinabove the washers are adapted to rotate as the cathode or other article is pushed through the seal. This feature provides rolling contact between the mechanical seal and the copper cathode, and so permits relatively free passage of the cathode without impairing the quality of the seal.

Although the sealing apparatus has been described hereinabove in connection with the sealing of a charging slot through which copper cathodes are charged into a furnace, the invention is not limited to this specific application. Apparatus according to the invention may be used with advantage to seal either charging or discharging apertures in furnaces of various types, as for example melting furnaces, heat treating or annealing furnaces, or the like. The new apparatus also is useful as a mechanical seal for apertures, in equipment other than furnaces, through which relatively thin solid articles, especially articles of irregular surface configuration, are to be passed,

I claim:

1. Apparatus for sealing an aperture in afurnace or the like comprising a generally tubular member formed with a relatively wide slot extending lengthwise thereof and adapted to be mounted across the face of the aperture to be sealed, and a plurality of relatively thin fiat elements positioned face to face within the tubular member throughout substantially the length of the slot therein. the flat elements being capable of projecting outwardly through the slot and further being capable of movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member.

2. Apparatus for sealing an aperture in a furnace or the like comprising a generally cylindrical tubular member formed with a relatively wide slot extending lengthwise thereof and adapted to be mounted across the face of the aperture to be sealed, and a plurality of thin discs positioned face to face within the tubular member throughout the length of the slot therein, the diameter of the discs being such with respect to the width of the slot as to be capable of projecting part way through the slot but incapable of being withdrawn completely from the tubular member through the slot.

3. Apparatus for sealing an aperture in a furnace or the like comprising a generally tubular member formed with a relatively wide slot extending lengthwise thereof and adapted to be mounted across the face of the aperture to be sealed, a plurality of relatively thin fiat elements each having an opening therein positioned face to face within the tubular member throughout substantially the length of the slot therein, the flat elements being capable of projecting outwardly through the slot-and further being capable of movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member, and a retaining rod extending through the openings in the flat elements.

4. Apparatus for sealing an aperture in a furnace or the like comprising a generally cylindrical tubular member formed with a relatively wide slot extending lengthwise thereof and adapted to be mounted across the face of the aperture to be sealed, a plurality of thin annular elements positioned face to face within the tubular member throughout the length of the slot therein, the outer diameter of said annular elements being such with respect to the width of the slot that the elements are capable of projecting part way through the slot but are incapable of being withdrawn completely from the tubular member through the slot, and a retaining rod of less diameter than the openings in the annular elements extending through said openings so as to prevent accidental loss of any annular memher from within the tubular member.

5. The combination with a furnace having an aperture therein of a closure seal for said aperture comprising a generally tubular member formed with a relatively wide longitudinally extending slot and mounted across the face of the furnace aperture, and a plurality of relatively thin flat elements positioned face to face within the tubular member throughout substantially the length of the slot therein, the flat elements being capable of projecting outwardly through the slot so as to provide a seal across the furnace aperture, and further being capable of movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member so as to permit a solid article to be passed through the furnace aperture.

6. The combination with a furnace having an aperture therein of a closure seal for said aperture comprising a generally cylindrical tubular member formed with a relatively wide longitudinally extending slot and mounted across the face of the furnace aperture, and a plurality of thin discs positioned face to face within the tubular member throughout the length of the slot therein, the discs being of such diameter relatively to the inner diameter of the tubular member and to the width of the slot as to be capable of projecting outwardly through the slot to provide a seal across the furnace aperture but incapable of being withdrawn from the tubular member through the slot, and the discs further being capable of movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member so as to conform with an irregular surface of a solid article being passed through the furnace aperture.

7. Apparatus of the character described comprising a generally tubular member formed with a relatively wide slot extending lengthwise thereof, and a plurality of relatively thin flat elements positioned face to face within the tubular memher, said flat elements being capable of limited movement relatively to one another in a direction perpendicular to the axis of the tubular member and of projecting part way through the slot, but being incapable of being withdrawn completely from the tubular member through the slot.

8. Apparatus of the character described comprising a generally cylindrical tubular member formed with a relatively wide slot extending lengthwise thereof, and a plurality of thin discs positioned face to face within the tubular member throughout the length of the slot therein, said discs being of such diameter relatively to the inner diameter of the tubular member and to the width of the slot as to be capable of limited movement relatively to one another in a direction perpendicular to the axis of the tubular member and to be capable of projecting part way through the slot, but to be incapable of being withdrawn completely from the tubular member through the slot.

9. Apparatus of the character described comprising a generally tubular member formed with a relatively wide slot extending lengthwise thereof, a plurality of relatively thin flat elements each having an opening therein positioned substantially face to face within the tubular element and being capable of projecting part way through the slot therein, and a retaining rod secured to the tubular member extending through the openings in the fiat elements, said retaining rod being of such size relatively to the openings in the flat elements that the latter are capable of limited movement relatively to one another in a direction substantially perpendicular to the axis of the tubular member. I

VERNON E. MACDONELL.

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