US 3395005 A
Description (OCR text may contain errors)
J. STELMAH July 30, 1968 METHOD AND APPARATUS FOR PROCESSING HEAT SOFTENABLE MATERIAL 2 Sheets-Sheet 1 Filed Dec. 15, 1964 R o T. N E V m JoHu STELMQH fi v Jul 30, 1968 J. STELMAH 3,395,005
METHOD AND APPARATUS FOR PROCESSING HEAT SOFTENABLE MATERIAL Filed Dec. 15, 1964 2 Sheets-Sheet 2 I Em ADMIxmRE AIR E INVENTOR. JOHN STE'L MAH 4. XWW? A r TOF/VEY United States Patent METHOD AND APPARATUS FOR PROCESSING HEAT SOFTENABLE MATERIAL John Stelmah, Somerville, N..I., assignor to Johns-Manville Corporation, New York, N.Y., a corporation of New York Filed Dec. 15, 1964, Ser. No. 418,452
2 Claims. (Cl. 65-5) ABSTRACT OF THE DISCLOSURE Method of enhancing and stabilizing the flame of a gas-air burner for fiber attenuation comprising providing an air deficient burning mixture of fuel and air and proportionately introducing therein additional air to complete combustion, and means therefor comprising a combustion chamber with an inlet for added air and intermediate said inlet and the chambers outlet, a recessed portion for mixing and initiating burning of the air deficient mixture.
This invention relates generally to improvements in forming propulsion streams, as commonly employed in the attenuation of heat softenable materials such as glass fibers, and has particular reference to novel method and apparatus for producing a hot gaseous blast to form or attenuate a source of heat softenable material into fibers or filaments.
Glass fibers are produced by subjecting primary filaments to a gaseous blast which attenuates the filaments into fine fibers. The primary filaments may be formed by exuding molten glass through orifices in the base of a melting crucible or by delivering molten glass into engagement with a spinner which through centrifugal forces causes the molten glass to flow through orifices in the side wall of the spinner.
In the attenuation of glass fibers the source of material to be attenuated is continuously advanced, thus in order to obtain generally uniform heating conditions, it is necessary to produce the heating gases at a rate at least as great as that at which the work is advanced. Generally, there is no time for soaking heat. Consequently, it has been deemed desirable in some cases to use a premixed fuel to accelerate the combustion process. However, certain difiiculties have been experienced in the ignition of such fuels in regard to flash-back and blow-off of the generated flame.
Refractory tunnel-type burners are know in the art as means for accelerating the speed of combustion of burning gaseous mixtures. However, one of the problems that has plagued the industry in the use of high velocity gas flow is the stabilization of the flame. It has been heretofore suggested to provide auxiliary pilot flames to envelop and stabilize the main flame. It has also been suggested to use metal bluff bodies in burners to create an area of turbulence and low velocity to stabilize burning. However, certain disadvantages are attendant with these arrangements, such as more complex construction, use of additional fuel in operating the pilot flames, and substantial reduction in velocity of the moving stream, which reduction in velocity materially reduces the attenuating force.
It is an object of this invention to provide an improved method and apparatus for attenuating glass fibers in which combustion of a combustible admixture and the operational efiiciency are enhanced.
It is another object of this invention to provide means for stabilizing the flame in a refractory-lined burner.
It is a further object of this invention to provide method and apparatus for selectively controlling the completion 3,395,005 Patented July 30, 1968 "ice of combustion of burning gases in relation to the zone where the material to be attenuated is introduced into the burning gases.
To accomplish the stated objects, the novel method and apparatus of this invention is designed to deliver one or more streams of fuel, which may be partially premixed with air, into a peripheral recess portion, open to and facing a refractory lined combustion chamber, in which recess portion combustion of the admixture is initiated. Preferably, fuel and air are introduced under pressure and tangentially into the recess portion where they are retained by centrifugal force until mixing is complete and combustion is initiated. When all of the air is supplied into the recess, combustion is completed there; thus combining high temperature and high heat release to the area of the burner immediately adjacent to the recess portion. When part of the air is supplied under pressure through secondary ports, external of the recess portion and preferably superjacent thereto, completion of the combustion may be selectively controlled by selectively proportioning the amount of air which is introduced into the recess portion and that which is introduced through the secondary ports. Thus, completion of combustion and the concomitant high heat release may be selectively controlled at desired elevation, preferably in the zone adjacent to where the material to be attenuated is introduced into the gaseous stream.
The invention will be more fully understood, and further objects and advantages thereof will become apparent by reference to the following detailed description in conjunction with the accompanying drawing.
FIG. 1 is a cross-sectional elevational view of a burner of the present invention taken along line 11 of FIG. 2 and shown in conjunction with a rotary spinner for forming glass fibers;
FIG. 2 is a cross-sectional plan view of the burner shown in FIG. 1 and taken along line 22 of FIG. 1;
FIG. 3 is a cross-sectional elevational view of another embodiment of a burner of this invention; and
FIG. 4 is a view of a burner shown and taken along line 44 of FIG. 3.
Referring to the drawing, in FIG. 1 is a rotor or spinner 10, which may be of any suitable type known in the art to Which molten glass is fed through conduit 12 from a suitable source (not shown) such as a forehearth furnace. The upstanding wall 14 is provided with a plurality of apertures or orifices 16 through which the molten glass is exuded or projected outwardly by virtue of centrifugal forces created by the rotation of the spinner 10.
Disposed super-jacent to the wall 14 is a refractory-lined and annular combustion space or chamber 18 from which hot products of combustion emanate through discharge port 20 preferably in the form of an annular blast to attenuate the glass exuded through orifices 16.
Inlet ports 22 are disposed circumferentially and are adapted to deliver an admixture of fuel and air into a recess portion 24 of chamber 18, in which recess portion 24 burning of the admixture is initiated. Preferably, the burner ports 22 are disposed to tangentially introduce the admixture into the recess portion 24. It will be understood that a premix of fuel and air may be introduced through the inlet ports 22 or that the fuel component of the admixture may be introduced through some of the inlet ports and that the air component of the admixture may be introduced through other of the inlet ports. Tangential firing into the recess portion 24 produces a rapid eflicient mixing of the components of the combustible admixture. The refractory 26 defining the recess portion becomes hot very quickly and thus provides a means of maintaining stable ignition. It is preferable that the depth d of the recess portion be at least one half its height h. Convection heat from the flame of the combusted mixture heats the wall portions 26 defining the recess to incandescence and thus continued stable ignition is facilitated.
As illustrated in FIGS. 1 and 2, the gaseous fuel component is fed under pressure through pipe 28 leading from the main supply passage 30 and extending into port 22. Valve 32 is provided in passage 30 to control the total volume of fuel emitted to recess portion 24 through one or more pipes 28.
The air component is supplied under pressure through main supply passage 34 which divides into passages 36 and 38. Valve 40 is provided in passage 34 to control the total volume of air to the chamber 18 while valve 42 is provided to proportion the air from passage 34 between primary passage 36 and secondary passage 38. The primary passage 36 is shown to lead to preheat chamber 44 which is open to port 22; however, it will be understood that primary passage 36 may lead directly to one or more ports 22.
The secondary air passage 38 leads to one or more secondary air ports 46. The port 46 is illustrated to be annular in form, having a central axis coincident with the axis of the spinner, but it will be understood that a plurality of smaller openings may be provided to define a corresponding number of ports 46, and may be arranged in circular array around chamber 18. One or more of the secondary ports 46 are positioned to selectively discharge a portion of the combustion air in axial alignment with the discharge port 20' of the combustion chamber. By varying the ratio of air that is introduced into the recess 24 through ports 22 and that which is introduced through the secondary ports 46, it is possible to regulate the elevation or zone where complete combustion occurs and high heat is released. Preferably, the high heat release area should be immediately adjacent to the orifices 16 of the spinner from which the molten glass is exuded.
The components of the gaseous fuel to be burned are fed tangentially into the recessed or track portion 24 in proportions so as to provide a rich admixture (an excess of fuel from that required to reduce a stoichiometric mixture). As the rich admixture burns and leaves the recessed track portion 24, additional or secondary air is provided in quantities sufficient to produce a stoichiometric mixture. As previously indicated, the zone where substantially complete combustion occurs may be selectively controlled by suitably proportioning the primary and secondary air, and regulating their respective pressures.
The temperature of the gases burning in the recessed track portion 24 is measured by thermocouple 48 while the temperature of the gases adjacent to the discharge orifices is measured by thermocouple 50. The thermocouples 48 and 50 are electrically connected through their respective leads 52 and 56 to recording temperature control 56 which in turn through suitable relays actuates the servomotor 58 which. regulates the opening and closing of valve 42 in the air supply line 34 thereby proportioning the air to passages 36 and 38 and subsequently through their respective discharge ports 22 and 46.
The over-all burner temperature is maintained by regulating the total fuel and air input which is controlled by valves 32 and 34, which in turn are operated by servomotor 60. The servomotor 60 is energized by the temperature sensing device 62 connected by lead 64 from thermocouple 66.
In order to facilitate ignition of the rich mixture within the recessed track portion, an additional pilot track having separate pilot burners may be provided immediately adjacent to the main recessed portion.
While primarily applicable to burners used in rotary spinning of staple fibers, the instant invention may also be used in connection with line burners for attenuating fibers from filaments which are introduced in planar array from a suitable source such as melting crucible 68 and guided through rolls 92 and 94 in front of a burner 70 as illustrated in FIG. 3. A rich admixture is fed to the annular recessed portion 72 through one or more ports 74.
The recessed portion 74 is located adjacent to the entrance 76 of the combustion chamber shown to be in the form of tunnel 78 but sufiiciently far enough away from the entrance 76 to provide sufficient refractory 80 to define the side wall 82 of the recessed track portion 72. As the rich admixture is burned it leaves the recessed track 72 in a series of spirals which move through the combustion chamber. A secondary port 84 is provided at the entrance 76 of the tunnel 78 to make up the deficiency in air and to provide essentially a stoichiometric burning mixture within the combustion chamber. By varying the ratio of air which is introduced into the recessed track portion 74 and that introduced through the secondary port 84, it is possible to regulate the point at which complete combustion occurs, whether it be within the chamber 78 or just outside the discharge outlet 86. Preferably, the combustion occurs just outside the chamber 78 in the zone where the filaments are being fed into the gaseous blast emanating from the burner 70. The means for suitably controlling the ratio of air introduced into the recessed portion 74 and into the secondary port 82 may be similar to that described in conjunction with the apparatus shown in FIGS. 1 and 2, and hence will not be further described.
In each of the burners described, the total fuel input to the burner remains unchanged but by selectively proportioning the amount of primary air and secondary air it is possible to control completion of combustion and the concomitant high heat released at the desired elevation or area within or outside of the respective combustion chambers. Thus, it is possible to define a longer attenuation zone which is efiective to keep the fibers molten for a period of time for greater attenuation.
Although the burners of this invention have been described in detail as to their component parts, it will be apparent that various changes and modifications may suggest themselves to one skilled in the art, all falling within the scope of the invention as defined by the subjoined claims.
What I claim:
1. A method of producing fibers from heat softenable material, which comprises:
(a) advancing a source of molten fiber producing material adjacent to the outlet of a refractory lined combustion chamber having a main portion and a periph eral recessed portion;
(b) introducing fuel and air under pressure sufiicient to cause rotation and tangently into said peripheral recessed portion of said combustion chamber, there being a deficiency of air to provide a rich admixture;
(c) initiating combustion of said admixture in said recessed portion;
(d) discharging the partially combusted admixture into said main portion of said combustion chamber and advancing said partially combusted admixture toward said outlet;
(e) introducing additional air under pressure into said main portion of said combustion chamber;
(f) controlling the zone where combustion of said partially combusted admixture is completed by proportioning the total air introduced between that introduced as part of said rich admixture and that introduced as additional air; and
(g) discharging the completely combusted admixture into the advancing path of said material to attenuate said material into fibers.
2. Apparatus for processing heat softened material comprising, in combination;
refractory wall means defining a combustion chamber having a main portion with a discharge outlet and a recessed annular portion facing said main portion and being in open communication therewith;
first port means tangential to said recessed annular portion for introducing combustible components therein;
second port means axially aligned with the axial extent of and directed toward the discharge outlet of References fitted said main portion; said first port means located intermediate the said sec- UNITED STATES PATENTS 0nd port means and the combustion chamber dis- 3,233,990 2/1966 Stephens t aL 65-6 charge outlet; 5 3,249,413 5/1966 Simmers et 'al. 6516 proportioning means for proportioning the total volume 2,777,508 1/1957 Jurisich 158--4 of combustible components between said first and Second F means; and DONALL H. SYLVESTER, Primal Examiner.
feeding means for introducing heat softenable material transversely into the blast emitted from said dis- LINDSAY, Assistant Examinercharge outlet. 10