US3485611A

US3485611A - Rotary apparatus for making ceramic fibers

Info

Publication number: US3485611A
Application number: US553492A
Authority: US
Inventors: Joseph E Blaze Jr
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1966-05-27
Filing date: 1966-05-27
Publication date: 1969-12-23
Anticipated expiration: 1986-12-23
Also published as: DE1596332B2; SE322310B; JPS5210933B1; BE699113A; ES341084A1; DE1596332A1; NL6707289A; GB1195885A; BR6789807D0

Description

Dec. 23, 1969 "3,485,611

ROIARY APPARATUS FOR MAKING CERAMIC FIBERS Filed May 2'7, 1966 .1. s. BLA E, JR

2 Sheets-Sheet 1 INVENTOR. Joseph E.Blaze, Jr

ATTORNEY 2 SheetsSheet 2 Dec. 23, 1969 J. E. sLAzE, JR

ROTARY APPARATUS FOR MAKING CERAMIC FIBERS Filed May 27. 1966 3,485,611 Patented Dec. 23, 1969 lice 3,485,611 ROTARY APARATUS FOR MAKING CERAMTC FKBERS Joseph E. Blaze, Jan, Alliance, @hio, assignor to sue Babcock 8: Wiicox Company, New York, N.Y., a corporation of New .i'ersey Filer May 27, 1966, Ser. No. 553,492 lint. Cl. (103%: 37/04 US. CI. 65-15 7 Claims ABSTRACT OF THE DISCLDSURE Apparatus for making fiber from a salt decomposition solution wherein the fibers are formed by centrifugal force extrusion of the solution with the fibers thereafter gently lifted by an air or other gas stream for collection on a moving belt. The mass of fibers is heated to drive off moisture and calcined in a relatively high temperature zone to convert the salt to metallic oxides.

This invention relates to apparatus for making fibers from a fiberizable mixture, and especially from a mixture of viscous ceramic material.

The apparatus of the present invention employs a rotatable member provided at its periphery wi;h an annular array of fine openings through which the fiberizable mixture is extruded under the pressure of centrifugal forces into long fine fibers.

The apparatus of the present invention also includes, in association with the rotatable member, means for gently collecting the fibers and forming a relatively shot-free mat or body of fibers which is subsequently calcined. Collection may be accomplished by a housing suitably equipped to operate at subatmospheric internal pressure, and having a foraminous conveyor covering an opening in the bottom of the housing. The fiber is collected on the conveyor for conveyance through a calcining oven. By having the foraminous collecting conveyor positioned above the spinning member, the extruded fibers are lifted into contact with the conveyor and held there by suction, while the shot is hurled aside by centrifugal force and, in any event, is not collected on the conveyor. The lifting of the formed fibers from the spinning member to the conveyor is preferably initiated by an air ring which surrounds the spinning member and issues a gentle, upwardly moving air stream.

In the drawings:

FIG. 1 is a partly diagrammatic, elevational view of fiber making apparatus constructed and arranged according to the invention;

FIG. 1A is an enlarged schematic view of the fiber col lecting device of the apparatus of FIG. 1; and

FIG. 2 is an enlarged elevational view of the fiber forming device employed in the apparatus of FIG. 1.

The illustrated apparatus for carrying out the invention comprises a support including a base 12 and an upright post 14 on which is journalled a rotatable member or spinner 16 formed to shape fiberizable material into elongated fine fibers by centrifugal action. There is further provided a conduit 18 for delivering fiberizable material in liquid form from a tank 20 to the rotatable member 16 and novel means including a housing 22 for collecting the formed fibers. Subsequently, the fibers are dried, as by infrared heat lamps 24, while passing thereunder on a conveyor 26, and then calcined while moving through a kiln 28 on another conveyor 30.

As shown in FIG. 2, the rotatable member 16 is in the form of hollow disc 32 having its upper and lower broad fiat surfaces disposed horizontally and being provided at its periphery with an annular series of radially and horizontally elongated, equally spaced, fine openings 34 of about .020 inch in diameter. The openings 34 communicate with the hollow interior 36 of the disc 32.

The disc 32 is driven for rotation about a vertical axis by a vertically elongated tubular drive shaft 38 which is turned, through a pair of drive gears 40 and 41, by a variable speed electric motor 42. The latter has its axis disposed vertically and utilizes a flange 43 to rigidly connect it to post 14. The drive shaft 38, horizontally offset from the motor axis, is supported for rotation about a vertical axis by upper and

lower journals

44 and 46, both of which are carried on the supporting post 14. The hub of gear 41 is rigidly and coaxially connected to the motor shaft 47, and the hollow hub of gear 40 is rigidly and c0- axially secured to the drive shaft 38. The conduit 18 extending from tank 20 has a vertical end portion which is stationarily secured by clamp 48 to support 10, and passes through the hub of gear 40 and the hollow central portion of drive shaft 33, terminating in the disc interior 36. A bushing 50 is disposed between the upper end of the drive shaft 38 and the conduit 18 to effect a fluid-tight seal therebetween.

The holes or openings 34 in the disc 32 are sufliciently small to produce fibers less than 5 microns in diameter and preferably 2 to 3 microns in diameter from a fiberizable mixture having a viscosity of 40 to 45 poises at 80 F. It should be understood that if the viscosity of the mixture is too low there will be a high percentage of shot or unfiberized solution produced with the fiber, while mixtures having an excessively high viscosity may plug the openings 34. The disc 32 is driven by the motor 42 to rotate at a peripheral speed of between 5,000 and 7,000 ft./min., and preferably 6,000 ft./min. The disc diameter is preferably 12 to 24 inches. The disc speed is adjusted in the mentioned speed range to provide the centrifugal force best suited, for extrusion, to the viscosity of the fiberizable material. If the peripheral speed of the disc 32 is too slow there will be a tendency for the fiberizable material to dry in the openings 34, thus clogging them and reducing production, whereas excessive speed results in fibers that are too short and too weak as compared with the quality fibers which can be produced at the proper rotational speed.

Fiberizable material is fed to the rotatable member 16 from the tank 20 under pressure from an air compressor 52, the outlet of which is parallel connected as shown to the interior of the tank 20 by a line 53 and also to an air ring 54 by a line 55. The air ring 54 is disposed annularly about the drive shaft 38 on a slightly larger diameter than the disc 32, with a series of apertures or outlet holes (not shown) formed in the upper surface of the air ring, in order to provide a gentle, diffused air stream which moves upwardly adjacent the periphery of the disc 32 and lifts the formed fibers extruded from the openings 34. A valve 58 in the conduit 18 is provided to permit the tank 20 to be drained.

T he housing 22 is supported from overhead structure generally designated by the numeral 60. An endless conveyor belt 66 of woven nylon or other foraminous material travels within the housing 22 over three triangularly oriented pulleys 68, one of which is driven by a motor (not shown). As shown in FIG. 1A, the housing 22 includes a bottom wall 70, the left-hand side of which has a large opening formed therein covered by part of the conveyor belt 66. The right-hand portion of the bottom wall 7 0 is imperforate. The assembly is such that the open portion of the bottom wall 70 is superjaceut the rotating member 16.

A suction fan 72 or other suitable air exhausting apparatus is provided at an end wall of housing 22 to draw room air upwardly through the conveyor belt portion covering the opening in the bottom wall '70 and then discharge it back to the room so as to maintain the interior of the housing 22 at subatmospheric pressure and thus create a suction on the downwardly facing surface of that portion of the conveyor belt 66 covering and passing over the opening in the bottom Wall 70. With this arrangement, the extruded fibers are lifted upwardly by the air stream issuing from the air ring 54 into the vicinity of that portion of the conveyor belt 66 operating at a negative pressure or suction and the formed fibers are thus collected and retained thereon. Of course, the thickness of the fiber buildup is determined by the speed of the conveyor belt 66 and the output of the spinner 16, and to some extent by the amount of suction at the collecting surface of the belt 66. A satisfactory vacuum has been provided on the collecting surface of the belt 66 by providing a suction fan having air moving capacity of 1600 cubic feet per minute for a bottom opening or collection area of about 4 square feet. Thus, it is preferred that the suction fan have an air moving capacity of about 400 cubic feet per minute for each square foot of effective collecting area on the belt 66.

The conveyor belt 66 moves in a triangular path in the direction of the arrows shown in FIG. 1A. The fibers which collect on the belt 66 as it travels past the opening in the housing 22 are conveyed to a position immediately beneath the imperforate portion of the bottom wall 70, whereupon the suction effect is negated and the fibers drop onto the top side of the conveyor 26 at its upper end. The conveyor 26 includes an inclined elongated conveyor belt 74 which travels on a pair of pulleys 76, one of which is motor driven (not shown).

The main purpose of the conveyor 26 is to facilitate the drying and compacting of the fibers under the penetrating heat of the infrared lamps 24. To this end, the conveyor 26 is sufiiciently long, for example 10 feet, to provide about 10 minutes of heating time at a travel speed of about 1 ft./min.

Intermediate the ends of the conveyor 26 the fibrous mat carried on the belt 74 is compacted by the action of still another conveyor 78 comprising an endless belt 80 and pulleys 82, arranged as shown in FIG. 1. It will be noted that the belt 80 and the belt 74 are in converging relationship in the direction of travel in order to effect the desired compaction and thus obtain a fibrous mat of the desired density at this stage of processing. For example, the spinner 16 may produce to cubic feet of fibrous material per hour and the fibrous blanket delivered to the conveyor 26 will have a density of about /2 pound per cubic foot; but after compression by the action of the conveyor 78 the blanket may have a density of 2 to 3 pounds per cubic foot. Since the drying temperatures experienced by the blanket on the conveyor 26 are in the range of 275-375 F. an aluminum screening material is a suitable belting material for the belts 74 and 80. The dried, compacted fibrous blanket is now in condition to be calcined in the kiln 28.

The kiln 28 comprises refractory wall structure supported on a stand 83. The kiln 28 has first and second chambers 84 and 86, respectively, each provided with individual heating elements 87, and 87A respectively to provide two zones of heating, the first chamber 84 operating at about a temperature of 700 F. in order to further dry the fibers and remove the last traces of acids from the initial chemical mix; and the second and final chamber 86 is operated at about 1900 F. in order to calcine the fibers.

The conveyor 30 is operated at the samerate of travel as the conveyor 26, and it includes a stainless steel belt 88, a pair of pulleys 90 and a motor 92 connected by a drive belt 93 for driving one of the pulleys at the same rate of travel as the conveyor 26. In addition, a conveyor 94 having an endless stainless steel belt 96 carried on three puleys 98, and suitably driven, serves to further compress the fibrous blanket to a density of between 3 and 8 pounds per cubic foot in the first chamber 84. As shown in FIG. 1, this is accomplished in a manner similar to the action of the conveyors 26 and 78 already described, since the

belts

88 and 96 are arranged in converging relationship in the direction of travel, with maximum compression being attained adjacent the partition between the first and second chambers of the kiln.

Although it will be apparent that the invention is applicable to the fiberization of both inorganic and organic materials, including plastics, and glass materials, it is especially Well suited to the making of long fibers below 5 microns in diameter from viscous aqueous solutions of materials which decompose or otherwise react to form refractory oxides at room temperature. For example, an aqueous solution of zirconium salts can be processed with the apparatus here disclosed to produce long fibers having a diameter of less than 5 microns.

ZrG fiber can be made from a fiberizable mixture comprising zirconium oxychloride, water, and preferably an additive for stabilizing the fiber to provide the cubic form of the crystalline lattice molecule. Additives such as CaO, Y O Ce0 or MgO have produced the desired result.

Similarly, an alumina fiber may be made from a solution of aluminum chloride and/or aluminum sulphate with one or more additives such as hydrochloric acid. acetic acid, hydrofiuosilicic acid, powdered aluminum. boric oxide, chromic oxide, colloidal silica, and colloidal alumina. More specifically, a suitable fiberizable mixture may consist of 1500 parts aluminum chloride in aqueous solution, 400 parts powdered aluminum, 100 parts colloidal silica, and 10 parts boric oxide. Preferably, the fiberizable mixture should be stable against recrystallization, possess a viscosity of 40 to 45 poises at room temperature, and employ a liquid vehicle that readily volatilizes in air. Water is a suitable vehicle, whereas oils and silicone materials are of such low volatility as to be unsuitable.

What is claimed is:

1. In fiber making apparatus, the combination of a fiber forming device for making'elongated fine fibers from viscous fiberizable material, said device including a hollow member rotatable about a vertical axis, means for rotating said hollow member, means forming an annular array of horizontally spaced openings in and through the periphery of said hollow member through which said fiberizable material is extruded by centrifugal action only, means for passing fiberizable material upwardly coaxially of said vertical axis of rotation into said member; a downwardly transversely moving foraminous surface disposed above said hollow member, means for creating suction at said surface above said member for collecting formed fibers thereon; and means for gently lifting formed fibers from said member to said surface without attenuating said fibers by an upwardly moving air stream.

2. In fiber making apparatus, the combination according to claim 1 including a support, a journal for said member on said support, a housing including a horizontally extending bottom wall having an opening which is formed therein and covered by said foraminous surface, said suction creating device maintaining the interior of said housing at subatmospheric pressure.

3. Fiber making apparatus comprising the combination according to claim 2, and means defining with said foraminous surface a movable conveyor for transporting collected fibers away from the opening in said housing, said fibers being released from said surface by loss of suction.

4. Fiber making apparatus comprising the combination according to claim 3, further including heating means and means for receiving fibers released from said foraminous surface and transporting them to said heating means.

5. Fiber making apparatus according to claim 4 Where- 2 5 in said heating means includes a chamber for calcining said fibers.

6. Fiber making apparatus according to claim 4, further including means for compacting said fibers while they are transported comprising convergent conveyor belts.

7. Apparatus for producing fibers from viscous fiberizable material comprising:

(a) a spinning device including a hollow disc rotatable in a horizontal plane about a vertical axis, and means for rotating said disc,

(b) a storage tank for said fiberizable material,

(c) means including a passageway between said tank and said disc for conveying said viscous material from said tank to the interior of said disc, said passageway being defined at least partly by a vertical tube disposed in coaxial relationship with said disc and communicating with the interior thereof,

(d) means for collecting fibers produced by said spinning device, said collecting means including a housing positioned above said spinning device, said housing having a bottom opening formed therein, a movable conveyor belt of foraminous construction part of which covers said bottom opening, and means for evacuating air from said housing and drawing air into said housing through said foraminous belt whereby a suction force is created on that portion of said belt covering said bottom opening in said housing,

3 485 till (e) means providing upwardly directed air streams from locations disposed below and about the periphery of said disc whereby fibers produced by said spinning device are lifted upwardly toward the bottom opening in said housing for collection on said foraminous belt,

(f) a kiln,

(g) a conveyor for transporting fibers through said kiln for curing,

(h) and means for moving said foraminous belt beyond the bottom opening in said housing in order to remove the suction force from said belt and thereby release said fibers onto said conveyor.

References Cited UNITED STATES PATENTS 2,569,472 10/1951 Hommel 654 2,586,774 2/1952 Bastain et a1. 659 3,014,235 12/1961 Snow 656 3,327,503 6/1967 Labino 65l6 X S. LEON BASHORE, Primary Examiner ROBERT L. LINDSAY, Assistant Examiner US. Cl. X.R.