Note: Descriptions are shown in the official language in which they were submitted.
6~
FIBERIZATION ENERGY CONSERVATION
BACKGROUND AND OBJECTS
This invention relates to the formation of fibers
from attenuable material and is adapted for use in the forma-
tion of fibers from various tllermoplastic materials, es-
pecially mineral materials such as glass and similar com-
positions which are rendered molten by heating. Since
the equipment or apparatus is especially useful in the at-
tenuation of glass and similar thermoplas~ic materials,
the following description refers to the use of glass by
way of illustration.
Certain techniques for utilizing whirling currents ~ .
or tornadoes for the attenuation of molten glass have been
disclosed by us in Canadian applications, such techniques
being identified as toration. For example, Canadian ap~
plication Serial No . 196,097, filed March 27, 1974, and
also the Canadian companion application Serial No. 196,120l
filed March 27, 1974, disclose development of pairs of counter-
rotating tornadoes by directing a gaseous jet into a larger
gaseous blast, thereby creating a zone of interaction in-
cluding pairs of such tornadoes, and into which zone a stream
of molten glass is delivered, with resultant attenuation
of the glass stream.
Various different embodiments of equipment for
effecting toration are disclosed in various applications
referred to, but in all instances a jet or jet flow is caused
to penetrate an attenuating blast, the jet being of greater
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kinetic energy per unit of volume than the blast and having
a smaller cross sectional dimension than that of the blast
transversely of the blast. In all instances, the stream
of attenuable material is introduced into the zone of inter-
action between the jet and blast either directly under theaction of gravity or by initially delivering the stream into
the influence of the jet to be carried thereby into the
zone of interaction.
In considering the following analysis it is first
to be kept in mind that the attenuation of thermoplastic
materials such as glass must necessarily take place at an
elevated temperature. Thus, the glass is rendered molten
by heating, for instance to a temperature about about 1250C,
and for high efficiency the temperature of the attenuating
gases in contact with the stream of material and the fiber
as it is formed must also be sufficiently high to maintain
the glass at an appropriate elevated attenuating temperature.
In certain of the applications referred to, for
instance in application 196,097 both the blast and jet are
disclosed as having relatively high temperature, for instance
a temperature of the order of 800C for the jet and 1580C
for the blast. Although our Canadian application 290,253,
filed November 4, 1977, discloses a method contemplating
the employment of low jet temperatures, for instance a jet
~5 temperature of the order of ambient or room temperature,
prior application 290,253, discloses blast temperatures at
relatively high values such as those referrec to above.
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The technique of the present invention is in strik-
ing contrast to those referred to just above in that the
present invention makes possible the use of lower temperatures
not only for the jet (as in prior application 290,253),
but also for the blast. As the blast embodies relatively
large volumes o~ gas, only a portion of which is actively
utilized for the attenuation of each fiber being made, the
heating of the entire volume of the blast flow to relatively
high temperatures results in substantial heat or energy
loss.
The foregoing loss of energy in the known tech-
niques for tora~ion of thermoplastic materials is avoided
by the technique of the present invention, according to
which provision is made for localized combustion of fuel
in the immediate ~icinity of the attenuating fiber in the
zone of interaction between the jet and blast, so that the
desired attenuating temperature may be established and
maintained without the necessity for heating the total
volume of the blast. In this way the temperature of the
gases delivered from the blast generator may be greatly
reduced with consequent extensive energy saving.
This technique of the present invention, which
may be referred to as "energy localization" not only achieves
the desired energy conservation, but in addition this tech-
nique affords additional advantages. For example, thetechnique of the invention provides for rapid cooling of
the fibers after attenuationl and with many thermoplastic
materials such rapid cooling increases the strength charac-
teristics of the fibers formed. This also maximizes fiber
length, which is desirable for most purposes.
7~
In a broad aspect of the invention, it will be
seen that the invention provides a method ~or attenuatiny
thermoplastic mineral material comprising generating a gas-
eous blast, generating a gaseous jet having a smaller cross-
sectional dimension than that of the blast in a direction
transversely of the blast, the jet having greater kinetic
energy per unit of volume than the blast and being directed
transversely into the blast there~y developing a zone of
interac~ion having whirling gas currents, delivering a stream
of attenuable material into said zone, the yas currents
in said zone including fuel and comburent components in
proportions providing a combustible mixture, and igniting
said mixture in said zone.
The above method may be achieved by way of an
apparatus for attenuating thermoplastic mineral material
comprising a blast generator, means for generating a gaseous
jet having smaller cross sectional dimension than the blast
and directed to penetrate transversely into the blast to
develop a zone of interaction in the blast, means for
delivering a stream of molten material into the zone of
interaction, and separate means for introducing fuel into
the zone of interaction.
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Still other advantages are achieved by the tech-
nique of the invention, as will appear more fully here-
inafter, following description of various of the embodi-
ments of equipment usea~le according to the technique of
the invention.
With the foregoing in mind, attention is directed
to the following description of equipment employed accord-
ing to the invention, as illustrated in the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 is a somewhat diagrammatic elevational
view of the major fiber producing and iber collecting
components of one system useable according ~o the invention,
in which a pair of jets are employed at each fiberizing
15 center, certain parts being shown in vertical section; '
Figure 2 is an enlarged perspective diagrammatic
view illustrating the fiberizing action of the equipment
shown in Figure l;
Figure 3 is an enlarged vertical sectional view
through the components of one fiberizing center in the plane
of the jet orifices;
Figure 4 is a vertical sectional view of the com-
ponents of a fiberizing center according to another embodi-
ment of equipment useable according to the present invention,
74
this embodiment also being disclosed in Canadian application
290,246, filed November 4, 1977;
Figure 5 is a perspective diagrammatic view il-
lustrating the operation of the equipment shown in Figure
4;
Figure 6 (appearing on sheet 4 along with Figure
4) is a plan view of several adjacent jets and of portions
of the blast employed in the arrangement of Figures 4 and
5, but omitting the blast feed and the glass fibers being
formed;
Figure 7 is a view similar to Figure 4 but illu-
strating a modification;
Figure 8 is an elevational view, partly in ver-
tical section, and illustrating the adaptation of features
of the present invention to a fiberizing system of the general
kind shown in Figure ll of our application 196,097 above
referred to;
Figures 9a and 9b are somewhat diagrammatic sec
tional views through a fiberizing center, Figure 9a indicat~
ing the action at that fiberizing center, when the energy
localization technique of the present invention is not uti-
lized, and Figure 9b representing the same fiberizing center
when the energy localization technique of the present in-
vention is utilized, and
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Figure 10 is a graph illustrating an advantage
of the technique of the present invention as applied to
the fiberization of certain classes of thermoplas~ic mineral
materials.
DETAILED DESCRIPTION
In the following description reference is first
made to the structural arrangement shown in the drawings,
and thereafter the energy localization aspects of the opera-
tion of the equipment according to the techni~ue of the in-
vention will be analyzed.
Referring first to Figure 1, a blast generatoror burner is indicated in outline at 8, the generator hav-
ing a delivery device 9 from which a blast 10 is discharyed. ~ !
In the embodiment illustrated this discharge occurs in a
generally horizontal direction, but it is to be understoodthat the discharge may be directed in other directions.
A manifold 11 for compressed gaseous medium is
supplied with gas from a supply pipe 13 through a connection
12. As best seen in Figures 2 and 3 the manifold 11 is pro-
vided with pairs of jet oriEices 14 and 15~ the series ofsuch pairs of orifices being indicated in Figure 2 by the
numerals 14a-lSa, 14b-15b, 14c-15c, and 14d-15d. The jets
delivered from each of the pairs of orifices are indicated
by the corresponding letters above, and in this connection
it is noted that while th~ee pairs of jets appear in the
perspective view of Figure 2, only a single pair of jets
(a-a) appears in Figures 1 and 3.
,
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As generally represented in Figure 1 the pair
of jets at each fiberizing center, for ins~ance jets a-a
impinge upon each other in their common plane and produce
a combined carrier jet flow indicated at A in Figure 1,
in which a stream of attenuable material is subjected to
a preliminary stage of attenuation. The combined jet flow
proceeds downwardly and penetrates the blast 10 creating
a zone of interaction between the jet and the blast charac-
terized by whirling currents and which is utilized for a
second stage of attenuation~
In the arrangement as shown in Figures 1 and 3
a glass supply means is generally indicated at 16, this
means having a bushing 17, and the bushing having a series
of spaced glass discharge devices 18 each fed from a meter-
ing orifice 19. Glass bulbs or cones G are delivered fromthe devices 18, and from the bulbs, streams of glass S are
delivered in a downward direction, one such bulb and stream
being included at each of the fiberizing centers.
The fibers formed from a series of fiberizing
centers spaced transversely of the blast 10 are deposited
upon a foraminous conveyor or belt 20 in the form of a fiber
blanket B, as appears in Figure 1. This fiber laydown
occurs within a chamber defined, for example, by wall
structure such as indicated at 21. Suction boxes are de-
sirably provided below the conveyor 20, as indicated at22, the boxes being connected by ducts 23 with one or more
suction fans such as diagrammatically indicated at 24.
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The a~tenuating action effected by the equipment
as described above can best be explained and analyzed by
reference to Figures 2 and 3.
The action at each fiberizing center is preferably
5 related to the action of the jets or the je~ flow in ad~ !
joining fiberizing centers. In Figure 2, the illustration
represents the complete action at the fiberizing center
corresponding to jets b-b, but represents only a portion
of the action occurring at the fiberizing centers of jets
a-a and c-c. In Figure 3 the action at the fiberizing center
represented by jets a~a is shown on an enlarged scale, and
in analyzing the operation, attention is first directed
to the fact that immediately following the delivery of any
gaseous jet from an orifice, the jet induces ambient gas
or air. Thus, as shown in Figure 3, each of the jets a
comprises a central jet core indicated by the letter 1 and
a surrounding envelope of gases including induced air in-
dicated by the letter i. This envelope rapidly expands
as the jet flow proceeds, and as shown in Figure 3 the jet
core remains as a relatively short cone shaped central portion
Such a core has the velocity of the jet as delivered from
the orifice, but the surrounding envelope of induced air
is of diminished velocity as the jet flow proceeds. In
both Figures 2 and 3 numerous arrows have been applied
indicating the induction of air by the jet flow, and, in
Figure 3 also by the blast flow.
-7~ (a)
,
.
When employing a pair of jets of substantially
the same kinetic energy and preferably also of substantially
the same size, with the two jets having axes lying in a
common plane and converging toward each other so that -the
jets impinge upon each other preferably at an acute angle,
the combined flow of the jets downstream of the region of
impingement is caused to spread laterally, i.e., is caused
to spread in directions transverse to the common plane of
the axes of the two jets. The pairs of jets or the planes
of the axes thereof are positioned sufficiently close to
each other so that the lateral spreading of the combined
flow is obstructed by virtue of impingement of the combined
flow of one pair of jets upon the laterally spreading com-
bined flow of the adjoining pairs of jets. This impingement
of the combined flow of adjoining pairs oE jets develops
two pairs of miniature tornadoes in each jet flow, with
the points of origin or apices of the tornadoes of each
pair being positioned in spaced relation toward opposite
sides of the common plane of the axes of the jets. When
viewed as in Figures 2 and 3, the upper pair of these minia-
ture tornadoes, indica-ted at tu-tu, have whirling currents
circulating or turning in directions toward each other at
the upper side of the tornadoes and away from each other
at the lower side. On the other hand, the lower pair of
tornadoes indicated by letters tl turn in the opposite
directions, as is indicated.
Between the two pair of tornadoes in the region
of impingement of the jets upon each other, a zone L of
laminar flow associated with the tornadoes is developed
this zone having high intensity in-flow of induced air,
and it is into this laminar flow zone at the side of the
upper pair of tornadoes that the stream of gla.ss is intro-
duced. As clearly appears in Figures 2 and 3, the stream
S of the glass is developed from the glass bulb, which bulb
or cone is located in a position horizontally offset from
the ~et delivery device. However, because the glass of
the bulb G is in attenuable or flowable condition as released
from the delivery device, the stream S of ~he attenuable
glass is deflected from the horizontally offset position
of the bulb toward the laminar flow zone L, this deflection
occurring as a result of the intense in-flow of induced
air, and this effect assures entrance of the stream of
attenuable material into the laminar zone. Indeed, even
with some misalignment of the glass delivery device 18 with
respect to the pairs of jets, the in-flow of induced air
will automatically compensate for such misalignment and
bring the glass stream into proper position.
From the above, it will be seen that by develop-
ing the pairs of tornadoes with the intervening zone of
laminar flow at each fiberizing center, and by delivering
the attenuable material in attenuable condition into the
region near said zone, the induced air automatically carries
the stream of attenuable material into the zone of laminar
flow and automatically compensates for misalignment, thereby
providing a highly stable introduction of the attenuable
material into the system.
y~
The arrangement as described above and the action
of the induced air currents provides for stable introduc-
tion of the attenuable material into the system, even where
the glass delivery devices are appreclably spaced away from
S the jet delivery devices, which is desirable in order to
facilitate maintenance of appropriate temperature control
for both the ylass delivery devices and the jet delivery
devices .
As seen in Figure 2, the pairs oE tornadoes tu
and tl tend to merge downstream of the laminar zone L, and
as the flow progresses downstream the tornadoes tend to
lose their identity, as is indicated (toward the right of
Figure 2) by the sectional showing of the two pairs of tor-
nadoes origînating with the jets c-c. The merged jet flow
of each pair of jets then proceeds downward to penetrate
the blast 10 as is indicated in Figure 2 for the jet flow
originating with the pair of jets b-b, and within the flow
of the blast, the jet develops the zone of interaction char
acterized by an additional pair of tornadoes indicated at
T, this interaction being identified as toration and fully
explained in the Canadian applications 196,097 and 196,120
identified above.
Also as shown in Figures 2 and 3, each stream
S of glass is subjected to a preliminary attenuation in
the jet flow between the zone of laminar 10w or point of
introduction of the glass, and the point of penetration
of the jet into the blast, and the partially attenuated
stream is subjected to further attenuation in the zone of
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interaction of the jet flow with the blast. ~s indicated
in the drawings, these two stages of attenuation are effect~
ed without fragmentation of the glass stream, so that each
stream produces a single fiber.
The action of the jets at each fiberizing center,
particularly in the development of the pairs of tornadoes
with the intervening zone of laminar Elow, is achieved by
employment of pairs of jets which are preferably of substan-
tially the same kinetic energy per unit of volume; preferably
also, the jets of each pair are of approximately the same
cross sectional area, but some leeway is permissible with
respect to the relation between the cross sectional areas
of the two jets of a pair, particularly if the kinetic
energy per unit of volume of each jet is substantially the
same.
Moreover, the jets need not necessarily have exactly
the same cross sectional dimensions in directions transvexse
to and parallel to the common plane of the axes of the two
jets. However, it is preferred that the cross sectional
dimensions should be substantially the same; and further,
that the dimensions of the jets of adjoining pairs should
be substantially the same, in order to provide uniformity
in the development of the pairs of tornadoes with the inter-
vening zones of laminar flow, as the laterally spreading
combined jet flow of each pair of jets impinges upon ihe
combined jet flow of adjoining pairs of jets. Uniformity
of the jets at each fiberizing station also provides uniformity
in the merging of the tornadoes of the jet flow at each
, , : ,
fiberizing center, and this in turn provides uni~ormity
of fiberizing conditions in the toration zones created by
the penetration of the jets into the blast.
For purposes of penetration o~ the jet ~low into
the blast, when the jet 10w reaches the blast it should
have higher kinetic energy per unit of volume, than the
blast.
It is also to be noted that for the purpose of
establishing the zone of laminar flow, into which the stream
of glass may be introduced without fragmentation, it is
important that the jets be established so that their axes
are directed substantially in a common plane and impinge
upon each other in said plane, preferably at an acute angle.
In a system such as described above in relation
to Figures 1, 2 and 3, the energy localization features
of the present invention may be utilized in any of several
different ways, but it is first to be kept in mind that
according to the present invention it is contemplated that
the gas currents in the zone of interaction, i.e. in the
toration zone, formed by penetration o~ the jet flow into
the blast, shall include fuel and comburent components in
proportions providing a combustible mixture. Preferably
the fuel and comburent components in the immediate vicinity
of the attenuable material should be present in approxi-
mately stoichi~metric proportions. The manner in whichthese components are introduced into the zone of interaction
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will be explained more fully hereinafter following the
structural description of the other embodiments of the
equipment illustrated in the drawings.
Turning now to the arrangement illustrated in
Figures 4, 5 and 6, as above noted, this embodiment of the
equipment is also disclosed in our Canadian application
290,246.
In this embodiment a series of secondary or carrier
jets are provided and a deflector Eor ~he jets is associated
with the series, the deflected jets being directed into
paths penetrating the blast, the streams of glass being
introduced into the jet flow and being delivered by the
jets into the zones of interaction into the blast.
In connection with the embodiment of the equipment
shown in Figures 4, 5 and 6 reference is first made to Figure
4 which shows the principle components of a fiberizing center.
Toward the left in Figure 4 there is shown a blast
generator 25 having a nozzle structure 26 from which the
blast 27 is deliveredO
A jet manifold box i5 indicated at 28, this mani-
fold having a series of jet oriEices 29 through which are
delivered a series of jets ~indicated in Figure 5 by the
letters a, b, c and d). The jet manifold 20 may be supplied
with pressurized jet fluid from the supply line 30 through
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, ' '
the connection 31. The jet mani~old 28 serves to l.tount
a deflector strip 40 overlying the series oE jets and having
its free edge 41 positioned so that the jets impinge upon
the deflector.
A bushing 32 associated with a forehearth or other
appropriate glass supply means indicated at 33 is provided
with glass orifice means indicated at ~4, and the stream
of glass S is delivered into the flow of the jet to be des-
cribed hereinafter and is carried downwardly to the zone
of interaction in the blast 27. As will be explained,
fiberization occurs in the jet and also in the blast, and
as the blast delivers the fibers toward the right as viewed
in Figure 4l a fiber blanket is laid down upon a perforated
traveling conveyor or belt of the kind described above with
reference to Figure 1.
As seen particularly in Figure 5, the blast nozzle
2~ is of substantial width. The bushing 33 Eor the supply
of glass preferably also has substantial dimension in the
direction perpendicular to the plane of Figure 4 in order
to provide for the supply of glass to a multiplicity of
the glass delivery devices 34.
It is contemplated that the jets delivered from
the jet orifices 29 be subjected to the guiding action of
certain elements or devices which cooperate with the jets
in generating pairs oE counter-rotating whirls or tornadoes
which are utilized for at least the preliminary attenuation
of the streams of attenuable material and also ~or purposes
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6~74
of feed of the partially at~enuated filaments into the zone
of interaction provided by penetration o~ the jets into
the blast, i.e. into the toration zones. For the purpose
of de~eloping the counter-rotating pairs of tornadoes, the
deflector plate 40 is associated with a group of the jet
orifices. As seen particularly in Figure 5, the guide or
deflector plate is desirably formed as a bent plate, one
portion of which overlies and is secured to the jet manifold
box and the other portion of which has a free edge 41 lying
in a position in the path of flow of the jets delivered
from the jet orifices 29, advantageously along a line inter-
secting the axes of the jet orifices.
As is graphically illustrated, particularly in
Figure 5, this position of the deflector plate 40 and its
edge 41 results in impingement of each of the jets upon
the underside of the plate 40 with conse~uent spreading
of the jets. Thus, in Figure 5, the flow of four of the
jets originating from orifices a, b, c and d is shown,
and it will be seen that as the edge 41 of the plate is
approached, each of the jets spreads laterally.
It is contemplated according to the invention
that the jet ori~ices 29 be placed sufficiently close to
each other and also that the de~lector or guiding means
be arranged so that upon lateral spreading, the adjacent
~5 or adjoining jets will impinge upon each other in the region
of the edge 41 of the deflector plate~ Preferably, the
adjacent jets impinge upon each other at or close to the
L6'~
free edge 41 of the guide plate 40 as is shown in Figure
5. This results in the generation of pairs of counter-ro-
tating whirls or tornadoes which are indicated in Figure
5 in association with each of the three jets delivered ~rom
the orifices a, b and c.
In analyzing the formation of these tornadoes,
particular re~erence is made to those associated with the
jet originating from orifice b in Figure 5. Thus, it will
be seen that tornadoes 42b and 43b, are generated and that
these two tornadoes have their apices originating substan-
tially at the edge 41 o~ the deflector 40 at opposite sides
of the jet at the zone in which the spreading jet impinges
upon the adjacent spreading jets delivered from orifices
a and c. The tornadoes 42b and 43b are oppositely rotating
and the tornadoes enlarge as they progress, until they meet
at a point spaced downstream from the edge 41 of the de-
flector. These tornadoes 42b and 43b also have currents
in the downstream direction, as will be seen.
Because of the spacing of the apices or points
of generation of the tornadoes 42b and 43b and because of
the progressive enlargement of those tornadoes, a generally
triangular zone 44b intervenes between the tornadoes and
the edge 41 of the deflector plate, and this triangular
zone is of relatively low pressure and is subjected to in-
tensive in~low of induced air, but the flow in this zoneis substantially laminar. This is the zone into which the
stream of molten glass or other attenuable material is intro-
duced into the system, and because of the character of this
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triangular laminar zone the stream of glass is not frag-
mented but is advanced as a single attenuating stream into
the region between the pair of tornadoes.
~ ttention is now called to the fact that the direr-
tions of rotation of the currents in the tornadoes 42b and
43b are opposite, being clockwise for tornado 42b and counter
clockwise for tornado 43b as viewed in Figure 5. Thus,
the currents in these two tornadoes approach each other
at the upper side thereof and then flow downwardly toward
the central or laminar zone 44b.
The directions of rotation just referred to are
further indicated by arrows for the tornadoes 45a and 46a
in connection with the corresponding pair of tornadoes as-
sociated with the jet delivered from the orifice a. It
will be understood that in the illustration of the jet flow
originating from orifice a, the flow has been shown as cut
off or sectioned adjacent to the downstream end of the zone
of laminar flow 44a, i.e. adjacent to the zone in which
the pair of tornadoes have bePn enlarged and commence the
2~ mutual merging which occurs as the jet flow proceeds. With
the illustration just referxed to, it further clearly appears
that the jet flow originating from orifice a not only in-
cludes the pair of tornadoes 45a and 46a but also includes
another pair of tornadoes 47a and 48a, the directions oE
rotation of which are also opposite to each other, as shown
in Figure 5, but in this case, the tornado 47a at the le~t,
as viewed in Figure 5, rotates in a counter clockwise direction,
whereas the tornado 48a at the right rotates in the clockwise
.. ..
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direction. It will be understood that similar duplicate
pairs of tornadoes are generated by and associated with
each of the jets.
Still referring to Figure 5, as the flow proceeds
from the plane in which the tornadoes are illustrated or
the jet delivered from orifice a, all four of the tornadoes
tend to merge and reform a more generalized jet flow and
this is indicated in Figure 5 by a section 49c, representing
a downstream section of the jet flow oriyinating from orifice
c. As will be seen, the whirling motions of the tornadoes
are diminishing in intensity and the entire flow/ including
the laminar flow of the central zone of the jet, intermix
with each other in the region indicated at ~9c, and there-
after the jet progresses downwardly toward the blast which
is indicated at 27 in Figure 5 and referred to more fully
hereinafter.
In the illustration of Figure 5 it will be under-
stood that for the sake of clarity, the showing of the
various portions of the jet flow is somewhat schematic.
For instance, in a zone spaced somewhat downstream of the
points of origin, the pairs of tornadoes originating in
one jet appear in the figure as being somewhat separated
from the pair of tornadoes originating in adjoining jets,
whereas, in fact, the tornadoes of adjoining jets would
be substantially contiguous.
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Because of the jet ~low in the laminar zone and
in the pairs of tornadoes, particularly the upper pair of
each group, the introduction of the stream of attenuable
material, which is indicated in Figure 5 as S for the fiber-
izing center including the jet orifice b, results in theprogression of the stream into the laminar flow of
the central zone. This carries the stream into the zone
of high velocity lying between the pairs of tornadoes and,
in conse~uence, the stream is attenuated as is shown in
Figure 5. It is found that this attenuation occurs substan-
tially within a planar zone indicated in Figure 5 at P.
The action of the pairs of tornadoes causes a whipping of
the attenuated fiber substantially within the planar zone
P, so that this attenuation does not result in projection
of the fibers being formed laterally toward the adjoining
jets.
Further jet flow causes the jet, together with
the attenuating fiber carried thereby, to penetrate the
upper boundary of the blast 27, the jet flow still retaining
~0 sufficient kinetic energy to effect such penetration of
the blast, and thereby initiate a secona phase of fiberi-
zation which proceeds or is effected, in accordance with
the principles fully explained in the prior applications
referred to above. Indeed, in the region of penetration
of the jets into the blast, the flow and velocity of each
jet is still sufficiently concentrated near the center of
each jet so that each jet acts individually to develop a
zone of interaction in the blast. Thus, from Figure 5 it
will be noted that in the zone of interaction, i.e. in the
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6/7~
toration zone, a pair of oppositely rotating whirls or tor-
nadoes indicated at TT, are generated, thereby developing
the currents which cause further attenuation of the fiber
being formed. The fiber is thereafter carried by the com-
bined flow of the jet and blast to a suitable collectionmeans, for instance a travelling perforated conveyor such
as indicated diagrammatically at 20 in Figure 1.
As will be understood, both in the laminar zone
adjacent to the edge of the deflector and also as the jet
flow progresses downstream, air is induced, and this in-
duction of air is clearly indicated by arrows applied to
the jet flow in Figure 5.
Having in mind the foregoing description of the
general nature of the equipment and operation contemplated
according to the present invention, attention is now called
to certain permissible variations and ranges of operatin~
conditions which may be employed.
As with the first embodiment of the equipment
described above, the fuel and comburent components may be
introduced into the system of Figures 4, 5 and 6 in various
ways which will be referred to more fully hereinafter.
However, attention is first directed to the follow-
ing structural description of the embodiments of Figures
7 and 8.
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The arrangement shown in Figure 7 is much like
that which appears in Figure 4, and similar reference charac-
ters have been applied. In Figure 7, however, a separate
means for introducing fuel or comburent components into
the zone of interaction is illustrated. Here a suppl~
connection 35 is indicated and a series of spaced delivery
nozzles 36 are associated with the supply 35 and are direct-
ed into the blast in the region adjoining and immediately
upstream of the zone of interaction which is indicated in
Figure 7 at Z.
In Figure 8 the blast generator is indicated at
50, the blast being delivered through the nozzle 51 into
a zone defined at its upper side by a plate structure 52
and at its lower side by a plate structure 53, the latter
being curved downwardly away from the mean plane of the
blast. If desired this plate may be provided with cooling
tubes 53a associated therewith.
The bushing 55 for the glass supply is provided
with a series of orifices one of which is indicated at 56,
the orifices being spaced from each other transversely of
the width of the blast in order to deliver streams of the
attenuable material into the blast. Just upstream of the
glass delivery orifices, the upper plate 52 is provided
with a series of jet orifices 29, one associated and aligned
with each one of the glass delivery orifices. The orifices
29 are supplied from a manifold 54 to which the compressed
jet fluid is supplied through the connections 54a and 54b.
~7~
The plate 52 further is provided with a manifold
passage 57 having a series of orifices 57a spaced from each
other transversely of the blast and each one associated
and aligned with the pairs of glass and jet orifices 56
and 29. This manifold 57 is supplied with a gaseous fuel
as by the supply connection indicated at 59 which may be
connected with a principal supply 60.
A downstream plate 58 is positioned at the upper
boundary of the blast, this plate having a cooling tube
58a. This arrangement is similar to that provided in Figure
11 of our Canadian application 196,097. `~
In the embodiment of Figure 8 fuel is introduced
through the orifices 57a and air is employed for the carrier
jets introduced through the orifices 29, thereby providing
a mixture of fuel and comburent in the zone of interaction
in the blast.
In addition provision is also made in the embodi
ment of Figure 8 for the introduction of additional air
into the blast upstream of the zone of interaction. For
this purpose, upper and lower air supply passages 61 and
62 are provided in a portion of the structure in the region
of the connection of the blast generator 50 and the nozzle
structure 51, and each of these supply passages is provided
with a slot or with a plurality of supply orifices as in-
dicated at 63.
-22-
~ ~f~
In an embodiment such as shown in Figure 8, the
introduction of air into the blast as just referred to ac-
complishes certain important purposes related to the energy
localization technique. Thus, with the combustion of fuel
in the zone of interaction, it is not necessary to use a
blast having as high a temperature as is required where
combustion of fuel is not occurring in the zone of inter-
action. In view of this a special embodiment comprising
a burner of the type similar to that shown in Figure 7 but
burning a smaller quantity of fuel, is used to heat the
additional air supplied through the passages 61, 62 and
63 in order to obtain a blast at relatively low temperature.
The effect of using a blast of lower temperature will appear
more fully hereinafter in the analysis given in connection .-
with Figures 9a and 9b.
r
Instead of providing a blast flow of lower tempera-
ture in the manner described just above, it is also possible
to completely eliminate the use of a blast burner and use
as a blast generator some other system of producing a blast
having a lower temperature, for instance, by employing a
heat exchange device rather than a burner.
Further reference to techniques for introducing
the fuel and comburent components into any of the structural
arrangements described above, will be pointed out herein-
after, but attention is now directed to the comparativeFigures 9a and 9b for the purpose of analysis of the energy
localization and conservation technique as provided accord
ing to the invention~
-23-
As above indicated Figure 9a represents a t~pical
toration type of fiberization operation without the addition
to the system of the energy localization technique of the
present invention. In this Figure the blast delivery nozzle
is indicated at 64, it being understood that the blast de-
livered from this nozzle is preferably of substantial width,
i.e. substantial dimension in a direction perpendicular
to the plane of the figure, so that a series of pairs of
jet and glass suppl~ devices 65 and 66 may be associated
with the blast and thus provide for the production of a
multiplicity of fibers.
In this Figure (9a) the glass stream is indicated
at S and the secondary jet at J, the zone of interaction
between the jet and the blast being indicated at Z. With
such a system and with a typical glass composition, the
temperature of the jet may be of the order of 800C ~as
disclosed in prior application 196,097) or the jet may have
a temperature closer to ambient (as disclosed in prior ap-
plication 290,253). In either event according to the tech-
niques of the prior applications referred to the temperature
of the blast would be of the order of 1500 to 1750C, (de-
pending somewhat on the temperature of the jet) in order
to provide the desired temperature in the zone of interaction
for the purpose of effe~ting attenuation of the glass stream.
In Figure 9a a temperature of 1700C is indicated at the
mouth of the blast nozzle and since the core of the blast
indicated at C extends to the zone of interaction of the
jet with the blast, the zone in which the attenuation is
-24-
- a~6~7~
actually occurring will have a temperature intermediate
that of the blast and that of the jet. Downstream of the
zone of interaction the isotherm lines are indicated at
pro~ressively lower temperatures, for instance 1600C,
1400C and 1200C.
In comparison with the foregoing, in Figure 9b,
exactly the same apparatus components are indicated, but
Figure 9b represents the prevailing conditions where the
energy localization technique of the present invention is
applied to the same equipment as shown in Figure 9a. For
this purpose, the jet device 65 may be supplied with fuel ~ !
under pressure, for instance a combustible gas mixture,
and additional air or oxygen may be delivered through the
blast nozzle 64; and in a typical case the gases of the
blast at the point of delivery are contemplated to be at
a much lower temperature than when operating as in Figure
9a. For example the blast temperature may be in the range
from about 550C to 650C, for instance of the order of
600C, as delivered from the blast nozzle 64, and a large
proportion of the volume of the gases will of course decrease
in temperature as indicated by the isotherm lines, for
instance to temperatures of about 400C, 30GC and 200C
in positions downstream of the blast delivery nozzle in
zones comparable to the isotherm lines indicating tempera-
tures of 1600C, 1400C and 1200C in Figure 9a.
-25-
''~ ' ".
Although it is possible to introduce the fuel
in the blast, it is pre~erred to introduce the fuel as a
portion of a jetr as above described.
Thus, in one embodiment of the technique according
Figure 9b, the jet J not only serves to establish the zone
of interaction desired and into which the glass stream S
is delivered, but in addition the jet provides a fuel com-
ponent in the zone of interaction and this fuel component,
because of the whirling currents which are characteristic
of the zone of interaction is intimately admixed with the
comburent, namely the excess of air brought to the zone
of interaction by the blast flow.
In considering the ratio of fuel to comburent,
it is first pointed out that under theoretically ideal con-
ditions, stoicheometric proportions of fuel and comburentwould be employed. However, a combustible mixture may be
provided throughout a range varying from the stoicheometric
ideal. Thus, in the case of the use of natural gas and
air, the quantity of the air may range from about 0.8 to
about 1.7 of the quantity of air providing stoicheometric
proportions.
With such appropriate quantities o air ~nd fuel,
the zone of interaction comprises a combustible mixture,
and this mixture in a typical technique according to the
invention has an ignition point in a range below tempera-
tures of typical molten glass compositions employed for
fiberization, so that the delivery o~ the glass stream
-26-
.
-
7~L
serves not only to introduce the attenuable material into
the zone of interaction but also serves to ignite the com-
bustible mixture of the fuel and comburent brought into
the zone of interaction respectively by the jet and blast.
In consequence the desired temperature, for example 1700C
may be provided in the zone of interaction in order to
provide for attenuation of the glass stream to form the
fiber, the zone Z in Figure 9b being indicated as being
at 1700C, notwithstanding the fact that the blast tempera~
ture both upstream and downstream of the zone of interaction
is at a much lower temperature.
It is further to be noted that in the technique
as diagrammed in Figure 9b the zone of interaction provided
by each of a series of jets may comprise only a very small
portion of the total volume of the blast flow, and since
this small volume is the only portion which need be elevat-
ed in temperature to the higher value required for attenua-
tion, a very large energy economy is effected, as compared
with systems in which the entire volume of the blast is
heated to the attenuation temperature.
It should also be noted that the toration fiberizing
technique is especially well adapted to the localization
of thermal energy because of the Eormation of a local zone
of low pressure and velocity that is formed immediately
adjacent to and generally surrounding each glass stream,
without the need for the interposition of physical structure.
The fuel or comburent can be injected into the zone of inter-
action to form a combustible mixture and the hot glass is
present for ignition of the mixture.
- ~27-
The zone of interaction i5 characterized by whirl-
ing currents or tornadoes of high velocity, and these currents
are useful in the energy localization technique of the pre-
sent invention for the purpose of e~fecting an intimate
admixture of the fuel and comburent. However, in the zone
of interaction, since the whirling currents around the tor-
nadoes move in directions upstream of the blast and then
in directions downstream of the blast, this necessarily gene-
rates zones in which low veloclties are present with respect
to the blast flow, and this is also of importance in the
technique of the present invention in providing a condition
in which ignition o~ the combustible mixture may occur and
in which stable combustion may be maintained. The importance
of this will be apparent when keeping in mind that with
a combustible mixture, formed, for example, of natural gas
and air the flame propagation rate is of the order of 0.3 ~ ;
to a few meters per second at 20C. Although this flame
propagation rate rises somewhat with rise in temperature,
it is still quite low, as compared with the velocities of
the blast. Nevertheless the zone of interaction is also
characterized by flow in certain regions at velocities well
below the flame propagation rate, in view of which ignition
and maintenance of stable combustion may be established.
Although it is believed the foregoing represents an explanation
of the reasons why ignition and stable combustion may be
established in the zone of interaction, it i5 also possible
there may be other reasons why the desired ignition and
stable combustion occurs.
-28-
As a substantial proportion of the heat necessary
to maintain the glass stream in attenuable condition is
transferred ~o the stream by contact of the hot gases with
the surface of the glass stream, the technique disclosed
results in a very eEficient transfer of heat to the glass
stream because the gases of the zone where intense heat
is developed are in close contact with the surface of the
glass stream.
Still further it should be noted that the system
as described above in connection with ~igure 9b takes ad-
vantage of the natural tendency for the flame to adhere
to the source of ignition, which in this system is the glass
stream itself, i.e., the stream of material which it is
desired to elevate to the appropriate attenuation tempera-
ture. This is because the temperature is higher and abouttwice the ignition temperature of the mi~ture and because
on the surface of the glass stream a boundary layer of com
bustible mixture develop and is brought to ignition con-
ditions by the heat given off by the glass. In consequence
a layer immediately around the glass is ignited and this
initiates a localized and stable combustion adhering to
the glass stream in the adjacent layers in the zone of inter-
action.
Still another advantage of the technique of the
present invention is the fact that with many glass composi-
tions the strength of fibers produced is increased if the
fiber temperature is rapidly reduced after fiberization
-29-
-
is completed. Ideal conditions for this purpose are pre-
sent in the system of the invention, as is readily apparent
from Figure 9b~
Returning to a consideration of the equipment
shown in Figures 1, 2, and 3 it will now be understood that
if desired the pair of jets a-a may comprise the fuel com-
ponent of the system and thus serve not only to carry the
glass into the zone of interaction in the blast but also
to introduce the fuel into the zone of interaction, and,
as in Figure 9b, air may be introduced into the system by
the blast 10. In this manner, with temperatures such
as those referred to in connection with Figure 9b for the
jet and blast, the desired energy localization and fuel
conservation may be achieved.
In connection with the embodiment of Figures 4,
5 and 6, if desired the entire volume of the fuel component
may be introduced with the jet, and air may be introduced
with the blast, preferably with reduction of blast tempera-
ture to values such as suggested above in connection with
Figure 9b in order to take full advantage of the fuel econo-
mies thereby attained.
In each of Figures 7 and 8 the fuel component
may be introduced separately from the jet, as already des
cribed. In Figure 7 air may be introduced elther by means
of the jet itself or by the blast, or both. One embodiment
of the equipment for introducing air with the blast is shown
-30-
.
in Figure 8, and as there shown the air is added to the
blast flow near the discharge nozzle 51. The introduction
o~ the air or comburent component into the blast is desir-
able because in this way the total volume of gases required
for the blast is provided without the necessity for heating
the total volume to the elevated temperatures required in
the zones of interaction where the fiberization occurs,
the advantages of which are explained above with particular
reference to Figure 9b.
The energy localization system of the present
invention also has special advantages in the attenuation
of certain classes materials, such as certain types of rock
and other mineral materials, either natural or synthetic,
with which the attenuation temperature range is very narrow.
In the graph of Figure 10 the viscosity and temperature
relationships or two different types of attenuable materials
are illustrated, one representing glass commonly used for
fiberization, and the other representing a naturally occuring
rock material having a narrow temperature range in which
the viscosity is suitable for fiberization. From the graph
it will be seen that the fiberization viscosity lying between
points A and B occurs over a much wider temperature range
(temperature range ta ~ tb)~ for the glass, than for the
rock (temperature range tal - tbl).
By introducing fuel in appropriately controlled
quantity into the toration or interaction zone in the blast,
the appropriate fiberization temperature for the rock or
-31-
similar materials may be extended somewhat downstream, there-
by facilitating maintenance of the desire~ ~iberization
viscosity for a longer interval.
In connection with the fiberization systems, such
as shown in the embodiments of Figures 1 to 3, 4 to 6, and
7, in each of which the stream of attenuable material is
introduced into the influence of the jet upstream of the
zone in which the jet penetrates the blast, if both fuel
and comburent are present in the jet flow at the point to
which the stream of attenuable material is delivered, the
point of ignition will not necessarily occur at the point
of delivery of the stream of attenuable material, and the
ignition may therefore not take place until the jet approaches
the blast or even enters the blast, depending upon various
15 operating conditions, such as the temperature and velocity -~
of the jet.
The fuel employed desirably comprises natural
or synthetic gas, but certain liquid fuels may be used in
vaporized or carbureted form.
As illustrating operating conditions which may
be used according to the present invention, the following
conditions may be employed:
With a fiberizing center of the kind shown in
Figures 1 to 6, the blast 27 is established by heating and
compressing a volume of air and has a temperature of about
600C, a velocity of about 300 m/s and a pressure of about
,
-32-
6~1
0.18 bar. The axes of the two jets intersect at an angle
of 60. One of the two jets comprises a mixture of 1 part
in volume of natural gas and 3 parts of air. The other
has 4 parts of air in volume each jet having a temperature
of about 20, a velocity of about 330 and a pressure of
about 2.5 bar. The glass is delivered at a temperature
of about 1300C.
With a fiberizing center of the kind shown in
Figure 7, the same blast conditions as mentioned above may
be employed and the jet may have a temperature of 20C,
a velocity of 330 m/s and a pressure of 2.5 bar. In this
case natural gas is fed to the device 36 at a pressure of
0.5 bar and a velocity of 900 m/s. The glass is delivered
from the device 34 at about 1300~C.
.
