US2681696A - Internal-combustion burner - Google Patents

Description

June 1954 c. J. STALEGO 81, 95

INTERNAL-COMBUSTION BURNER Filed May 3, 1951 INVENTOR CHARLES 1514mm.

v L A ORNEYS.

Patented June 22, 1954 UNITED STATES PATENT OFFICE INTERNAL-COMBUSTION BURNER Charles J. Stalego, Newark, Ohio, assignor to Owens-Corning Fiberglas Corporation, a corporation of Delaware 12 Claims. 1

This invention relates to internal combustion burners and more especially to a burner construction of a character especially adaptable for producing an intensely hot, high velocity gaseous blast suitable for attenuating heat softenable material to fibers.

Internal combustion burners have been employed to produce an attenuating blast for forming glass fibers where a fiber of comparatively small size or diameter is desired. In burners of this character, the blast is formed by burning a combustible fuel and air mixture, preferably a mixture of fuel gas and air, in a confined zone or chamber of the burner, the latter being provided with a relatively small or restricted orifice through which the intensely hot products of combustion are exhausted at a high velocity for attenuating glass or other heat softenable fiber forming material to fine fibers.

A burner of this character is disclosed in Stalego Patent 2,489,243, and one exemplary use of the burner for fiber formation involves continuously feeding elongated bodies or primary filaments of glass into the blast emanating from the burner in a direction substantially normal thereto whereby the advancing ends of the primary filaments are softened and drawn or attenuated into fine fibers by the velocity of the blast in the manner disclosed in the above mentioned Stalego patent.

Burners utilized for the stated purposes are subjected to exceedingly high temperatures being upwards of three thousand degrees Fahrenheit and such temperatures require the utilization of heat resisting refractory materials in the burner construction. The available refractories employed for the purpose are nevertheless subject to thermal shock and while the coefficient of expansion of such refractory materials is comparatively low, due to the thermal shock resulting from the wide range of temperatures encountered, the useful life before fracture ultimately occurs is comparatively short, being usually a matter of a few days.

It has been conventional practice in constructing such burners to employ a high temperature refractory at the orifice or blast discharge end of the burner having comparatively thick wall areas to provide the necessary strength to withstand the gas pressures developed during combustion and to minimize heat losses through radiation. The temperatures in the zone of the nozzle are usually between twenty-four hundred degrees and three thousand degrees Fahrenheit, while the temperature of theouter zone or perimeter of the wall may be approximately two thousand degrees Fahrenheit or less. While the thick walls adjacent the orifice are effective to withstand the gas pressures and minimize heat losses through radiation, they are however readily subject to thermal shock or expansion and ultimate fracture whereby the longevity of such burner under continuous operation as encountered in the attenuation of glass to fibers rarely exceeds a period of from fifteen to twenty days.

The present invention embraces a burner embodying a member of refractory material formed with a nozzle or blast orifice the walls of which are configurated to minimize or reduce the liability of the refractory to fracture under the stresses or thermal shock existent under high temperature operation.

An object of the invention is the provision of a member provided with an orifice suitably arranged to facilitate flow of gases therethrough in the form of a high temperature, high velocity blast, the walls of the member being configurated in a manner to reduce or minimize the internal stresses resulting from expansion and contraction under extreme variation in operating temperatures.

Another object of the invention resides in the provision of an orifice construction fashioned of refractory material for incorporation in a blast producing internal combustion burner wherein relatively thick walled portions of the refractory are slotted or relieved in a manner to reduce the molecular stresses or internal pressures generated by reason of the high temperatures of the burned gases whereby the tendency or liability for the refractory to fracture or fail in operation is greatly reduced and the life thereof correspondingly increased effecting material savings in the cost of fiber attenuating operations.

Another object of the invention resides in the provision of a nozzle or orifice construction for use under extremely high temperatures of burning gases shaped or configurated in a manner to reduce the stresses arising by reason or" temperature diiferential existent between the throat of the nozzle or orifice and the exterior zones of the refractory material without sacrificing the strength characteristics necessary to withstand the pressures developed by combustion.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

Figure 1 is a semidiagrammatic elevaticnal view illustrating the utilization of a form of the invention for producing a blast of gases of combustion adapted for the attenuation of heat softenable fiber forming materials;

Figure 2 is an elevational view of a burner construction embodying the invention, certain portions being shown in section for purposes of illustration, and

Figure 3 is an end elevational view of the construction illustrated in Figure 2 particularly showing the configuration of refractory construction defining the blast orifice.

While the embodiment of the invention disclosed is of a character particularly useful in apparatus for producing very fine fibers through the attenuation of fiber forming material fed into an intensely hot gaseous blast, it is to be understood that the orifice construction embcdying the principles of this invention may be utilized to advantage with other types of burners or combustion devices where comparatively high temperatures are encountered.

Referring to the drawings and first with re spect to Figure 1, there is illustrated an apparatus for attenuating fibers from fiber forming materials such as glass utilizing a blast producing burner embodying the invention. The arrangement illustrated includes a receptacle or forehearth H] adapted to contain a supply of molten fiber forming material such as molten glass. Disposed beneath the receptacle is is a feeder !2 formed with a plurality of small orifices or outlets forfiowing or feeding a plurality of streams S of the'molten material. The streams 3 moving downwardly are substantially solidified by the cooling effects of the surrounding atmosphere and are gathered together and directed between feed rolls M; which serve to draw the streams into primary filaments.

The filaments or rods F so formed are directed by a suitable guide it into a blast B projected from a restricted orifice formed in a forward wall or nose portion of a combustion burner 20. The burner 26 is formed with a chamber 22 in which a combustible mixture of gaseous fuel and air is burned, the burned gases being discharged through an orifice providing an intensely hot, high velocity blast which engages the advancing ends of the primary filaments F moving into the blast, the heat of the blast softening the advancing ends which are continuously attenuated or drawn out to fine fibers by the force and velocity of the blast.

The attenuated fibers are conveyed by the blast to a collecting zone preferably including a movable foraminous conveyor 24 mounted upon supporting rollers 26. The forward flight of the conveyor forms a' collecting surface upon which the attenuated fibers pile up or accumulate in a mat formation which is continuously removed from the collecting zone by the. conveyor. A chamber 28 disposed rearwardly of the forward fiight of the conveyor is connected with a source of reduced pressure or suction to facilitate the adherence and collection of the fibers upon the conveyor.

The burner construction for producing the high velocity attenuating blast for fiber forming purposes is inclusive of a metal shell 34 suitably adapted and shaped to enclose a refractory wall 4 construction 36 preferably composed of two telescopically arranged elements or layers 3'? and 38, the multi-layer construction facilitating expansion and contraction attendant the wide temperature changes and variations encountered in the burner. The burner is formed with a transverse wall 40 containing a plurality of perforations or apertures 42 for admitting a combustible mixture to the chamber 22 through a duct in the fitting 35 secured to a flange associated with the burner shell 34. The fitting 45 may be connected by means of a tube 48 with a supply of fuel gas mixed with air in the proper proportions to form an eflicient combustible mixture.

The burner construction is provided at its forward end with a member 59 formed with an orifice 52 through which the intensely hot gases of combustion from the combustion chamber 22 are projected in the form of an intensely hot, high velocity blast B. As shown in Figure 3, the orifice is preferably elongated in a horizontal direction to accommodate or overreach the plurality of primary filaments F which are concomitantly fed into the blast in side by side relation. The member 50 is formed of a high temperature resistant refractory material of a character adaptable to withstand the temperatures of the hot gases projected through the orifice 52.

Heretofore theorifice member of a conventional burner has been formed with comparatively thick wall portions which were readily amenable to thermal shock and which usually fractured after a comparatively few days of use. The orifice member of the present invention is configurated in a manner providing adequate strength to withstand the pressures of the burning gases within the chamber and adjacent the orifice and which is shaped to reduce or substan-- tially eliminate the liability to fracture under thermal shock. As particularly shown in Figure 3, the peripheral portion of the member 50 is configurated with a plurality of spaced peripheral segments 51 formed by radially arranged kerfs or slots 58 separating the segments. The contour of the orifice 52 is thereby bounded or embraced by a wall portion which is continuous, the outer portion of which is peripherally relieved of extreme molecular stresses through the presence of the radial slots. Thus under the extremely hightemperatures encountered in the burning gases, the wall portion 60 being of reduced thickness may readily expand and contract under thermal shock with comparative ease and facility without liability of fracturing because the temperature differential in and throughout the wall or zone portion 60 surrounding the orifice is substantially uniform and hence stresses or forces are minimized or reduced which would otherwise tend to fracture the member 50.

Through the provision of the segmental formation of the peripheral areas or zones of member 50, expansion and contraction of the segments is readily accommodated through the presence of the radial slots 58 so that even though the expansion and contraction under wide temperature variations ensues in the segments 51, the circumferentially directed stresses are greatly reduced because of lack of continuity of the thick wall area and hence the comparatively thin wall portion at 60 boundingor defining the orifice may expand a greater amount than the segments whereby the tendency of the orifice wall to fracture is minimized or substantially'eliminated through the facility that the segments are virtually permitted expansion and contraction independently of the thin continuous wall portion 66 adjacent the orifice. While the presence of the radial slots 58 subdivides the peripheral portions of the member 50, the radial thickness of the segments provides the necessary strength characteristics in radial directions from the orifice to withstand the pressure of the gases at the zone of the orifice.

It has been found that the construction of the orifice plate or member in the manner hereinbefore described provides an arrangement whereby the life of the burner is many times that of constructions heretofore used which were amendable to fracture after a short period of use.

It is apparent that, within the scope of the in vention, modifications and difierent arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

What I claim is:

1. A burner of the character disclosed adapted to burn a combustible mixture in a confined zone, said burner having a restricted orifice through which intensely hot gases of combustion are projected as a high velocity blast; the portion of the burner provided with the orifice being formed of high temperature resistant refractory material and having a relatively thin wall portion defining the orifice and a thick wall portion formed rearwardly of the orifice, said thick wall portion having peripherally spaced-apart areas of reduced thickness for minimizing thermal shock in the refractory material.

2. A burner of the character disclosed adapted to burn a combustible mixture in a confined zone, said burner having a restricted orifice through which intensely hot gases of combustion are projected as a high velocity blast; the portion of the burner provided with the orifice being formed of high temperature resistant refractory material having a thin wall defining the orifice and progressively increasing in thickness rearwardly into a relatively thick wall, said thick wall being formed with peripherally spaced recesses for minimizing thermal shock in the refractory material.

3. A. burner of the internal combustion type adapted to burn a combustible mixture in a confined zone for producing a blast of intensely hot gases of combustion; the interior of the burner being lined with refractory material, said burner having a nose portion formed of refractory material and provided with an orifice through which the gases of combustion are projected as a blast; the wall bounding the exit of the orifice being continuous and relatively thin, the refractory material adjacent and rearwardly of the orifice being relatively thick, the peripheral 'zone of said relatively thick portion being reduced in cross section at spaced zones to interrupt the peripheral accretion of molecular stresses of expansion and contraction.

4. A. burner of the internal combustion type adapted to burn a combustible mixture in a confined zone, said burner being provided with a restricted orifice through which intensely hot gases of combustion are projected as a high velocity blast; the interior of the burner being lined with refractory and the orifice being formed in refractory material; the wall defining the orifice being relatively thin; the refractory wall portion adjacent and rearwardly of the orifice being relatively thick, the periphery of said 6 thick wall portion being formed with spaced radially disposed slots providing spaced zones whereby the stresses of expansion and contraction resulting from temperature changes are localized in said zones.

5. A burner adapted to burn a combustible mixture in a confined zone, said burner being provided with an orifice through which the products of combustion are projected as an intensely hot, high velocity blast; the interior walls of the burner being lined with refractory material; a block of high temperature resistant refractory material at the forward end of the burner and in. which the orifice is formed, the wall portion of the block at the forward end of the orifice being comparatively thin and progressively increasing in thickness in a direction rearwardly of the orifice, the portion of greater thickness being peripherally recessed at spaced zones to reduce thermal shock.

6. A burner adapted to burn a combustible mixture in a confined zone, said burner being formed with an orifice through which the prodnets of combustion are projected as an intensely hot, high velocity blast; the interior walls of the burner being lined with refractory material; a block of high temperature resistant refractory material at the forward end of the burner and in which the orifice is formed, the wall portion of the block. at the forward end of the orifice being comparatively thin and of increased thickness rearwardly of the orifice, the portion of increased thickness being formed with radially disposed, peripherally spaced recesses forming sections in which the stresses of expansion and contraction occurring the the thickened wall are isolated whereby the tendency of the wall to fracture is substantially minimized.

7. A burner adapted to burn a combustible mixture in a confined zone, said burner being provided with a transversely elongated orifice through which the products of combustion are projected as an intensely hot, high velocity blast; the interior walls of the burner being lined with refractory material; a member of high temperature resistant refractory disposed at one end of the burner and formed with the orifice of elongated shape to provide a ribbon-like blast; the wall defining the exit zone of the or'mce being relatively thin and progressively increasing in thickness to substantially circular configuration in a direction rearwardly of the orifice; the portion of substantially circular configuration being formed with peripherally spaced slots to inhibit the cumulation of stresses of thermal shock in the relatively thick portion of the member resulting from the high temperatures of the gases in the blast.

8. A member of refractory material for use with a moving stream of intensely hot gases having an orifice defining the cross-sectional contour of the gas stream, said member being formed with a comparatively thin wall bounding the exit zone of the orifice and a thickened wall pertion spaced from the exit zone, said thickened wall being formed with peripherally isolated portions for minimizing the stresses resulting from thermal shock.

9. A member of refractory material for use with a moving stream of intensely hot gases having an orifice defining the cross-sectional contour of the gas stream, said member being formed with a comparatively thin wall bounding the exit zone of the orifice and a thickened wall portion spaced rearwardly from the exit zone,

being lined with refractory material; a mem- V ber of refractory material disposed at one end of the burner and formed with the orifice elongated in a transverse direction to provide a ribbon-like blast; the wall defining the orifice being relatively thin at the exit zone and progressively increasing in thickness to substantially circular configuration in a direction rearwardly of the orifice; the circular configuration being formed with peripherally spaced radially arranged slots forming isolated sections inhibiting the accretion in the thickened wall portion of molecular stresses set up by the temperature differential existent between the relatively thin and thickened walls adjacent the orifice.

11. A burner of the internal combustion type adapted to burn a combustible mixture in a confined zone, said burner being provided with a restricted orifice through which intensely hot 9 gases of combustion are projected as a high velocity blast; the interior of the burner being lined with refractory material, the Wall of refractory material defining the orifice being relatively thin and the Wall of material rearwardly of the orifice being relatively thick, said thick wall portion being formed with spaced-apart areas of reduced thickness at its exterior zone to inhibit the accretion of molecular stresses occurring under high temperatures whereby tendency of the material to fracture is substantially reduced.

12. A burner adapted to burn a combustible mixture in .a confined zone, said burner being formed with an orifice through which the products of combustion are projected as an intensely hot, high velocity blast; the interior walls of the burner and the portion thereof in which the orifice is formed being of a high temperature resistant refractory material, a zone of the refractory disposed adjacent and rearwardly of the orifice being relatively thick and having its exterior periphery formed with spaced-apart areas of reduced thickness providing for substantially unrestricted expansion and retraction of the refractory in the exterior zone without materially reducing the strength of the refractory material bounding the orifice.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,559,527 Williams July 3, 1951 2,561,200 Hess July 17, 1951

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