Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND AND OBJECTS
This invention relates to the formation of fibers
from attenuable material and while the invention is adapted
for use in the formation of fibers from a wide variety of -~
attenuable materials, it is particularly suited to the at~
tenuation of various thermoplastic ~aterials, especially ~ -
mineral materials such as glass and similar compositions -
which are rendered molten by heating. As with the technique
be~ou~ -~ne~ o~7 cd
of theACanadian applications, the present invention may ~ -
10 be employed in connection not only with various mineral ~ -
materials, but also with certain organic materials which -~
are attenuable, such as polystyrene, polypropylene, poly-
carbonate and polyamides. Since the equipment or apparatus
is especially useful in the attenuation of glass and similar
thermoplastic 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 prior applications, such techniques being
identified as toration. For example, Canadian application
Serial No. 196,097, filed March 27, 1974, and also the com-
panion Canadian application Serial No. 196,120, 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 including
pairs of such tornadoes, and into which zone a stream of ~ -
molten glass is delivered, with resultant attenuation of
the glass stream.
'~ 1-
~3~ 7
:
In the equipment illustrated in said prior Canadian
applications 196,097 and 196,120, the orifice from which
the glass stream is delivered to the zone of interaction
is located at or adjacent to the boundary of the blast.
In our Canadian application Serial No. 245,501, filed Feb- -
ruary 11, 1976, toration arrangements are disclosed in which
the glass orifice is positioned in spaced relation to the
boundary of the blast, and in which the glass stream is
delivered by gravity from an orifice spaced from the blast
to the zone of interaction established by the interaction
of a jet and a larger blast. ;
;~ In Canadian applications Serial No. 290,246, filed
November 4, 1977, 265,560, filed November 12, 1976 and
290,253, filed November 4, 1977, both the glass orifices
, and the jet orifices are spaced from the boundary of the
~, blast, and the glass streams are delivered to the jets and
by the action of the jets are delivered into zones of inter-
'!
;~ action of the jets with the blast. In the appllcations
~ just mentioned, the glass streams are also subjected to
.,~, ~ .
two stageslof attenuation, one~stage occuring in the jet
^ and the other in the blast.
. ~ `' '''
Still further in our Canadian application Serial
No. 290,246, the secondary or carrier jet which delivers
the glass into the zone of interaction with the blast is
; 25 caused to develop a stable zone of laminar flow lying between ~ -~
a pair of counter-rotating whirls or tornadoes formed in
the jet flow upstream of the zone of penetration into the ~ -
blast, and the glass stream is delivered to the laminar
.. . . . . . .
zone and thereafter enters the region of the tornadoes of
the carrier jet, which latter merge downstream of the carrier
jet, but before the carrier jet reaches the principal blast.
As is pointed out in our Canadian application Serial No.
290,246, the operation just described results in a two-stage
attenuation, the first stage taking place as the glass stream
is advanced into the influence of the tornadoes of the car-
rier jet, and the second stage taking place after the carrier
jet and the partially attenuated stream enter the zone of
interaction of the carrier jet with the blast.
According to the disclosure of said Canadian applica- ~ !:
.,, ~ . .. .
tion 290,246, the zone of laminar flow and the tornadoes
of the carrier jet are developed as a result of deflection
of individual carrier jets provided for each fiberizing
center and, as is brought out in said Canadian application
~; 290,246, such deflection of a carrier jet contributes to
stability of introduction of the glass into the system,
notwithstanding the delivery of the glass to the carrier
jet at a point spaced appreciably from the boundary of the
principal blast.
The present invention, in common with Canadian
application 290,246, has as a major objective, the stabilizing
~ of the stream of glass or other attenuable material by de~
-~ velopment of a zone of laminar flow between tornadoes estab-
lished in a jet flow system. However, the jet flow system
of the present invention is somewhat different than that
of said prior application, but it also provides various
- -3-
of the advantages thereof together with certain other advan-
tages which are distinctive to the technique of the present
invention. -
In accordance with the present invention, jet
guiding or deflecting means are employed at each fiberizing
center. Instead of employing a jet deflector or baffle
of the kind disclosed in Canadian application 290,246,
the individual jets are each delivered into a concavely
curved trough-like jet guiding device, conveniently in the
form of a curved tube or elbow having the concave or inner ~ -
; wall removed, and the stream of attenuable material is intro- ~
duced into the jet flow in the region where the inner wall ~ -
of the tube has been removed. Thus, the stream of attenua- ;~
ble material is delivered to the jet in the region where
the jet is flowing through the concavely curved trough-like
guide.
Because of the guiding action of the sides of
the trough-like portion of the guide and because of the r
induction of air or other ambient gas, each jet develops
a pair of whirls or tornadoes, with a central generally
laminar flow region lying between the tornadoes, and the
stream of attenuable material is introduced into the zone
of laminar flow between the tornadoes. In conse~uence, - `
a preliminary attenuation of the stream of attenuable mater-
ial is effected in the jet flow.
~, ;, , , ~
&:~7
: The invention also contemplates using the fore-
going jet flow system in combination with a gaseous blast
directed in a manner to intercept the jet and it is contem-
plated that the kinetic energy per unit of volume of the
jet be greater than that of the blast and further that the
cross sectional dimension of the jet be smaller than that
of the blast in a direction transversely of the blast, so
that the jet penetrates the blast and develops a zone of
interaction between the jet and blast, which zone is of
the type characterized by counter-rotating tornadoes, thereby
providing for a second stage of attenuation, according to
the toration type of technique more fully explained in the
prior Canadian applications above referred to.
`.
~ In the technique of the prior Canadian application ~.
~,-
290,246, a series of jets are generated in a side-byside
-.; relation and with a spacing sufficiently close to provide
for impingement of the jets upon each other at least down-
;. stream of the edge of the deflector plate, so that the
.,~ .
.~. impingement of the jets upon each other aids in developing
~ the counter-rotating tornadoes in pairs at opposite sides -.
., of a zone of substantially laminar flow. In contrast with
the foregoing, in the system of the present invention, the ~ -
pair of the tornadoes with the intervening zone of substan- ~
. tially laminar flow is generated without impingement of ~; adjacent jets upon each other, in view of which according
to the technique of the present invention any desired spac-
~.
ing of the jets may be adopted.
. :
-5- :
~.
96~7
Because of the development of tornadoes in the
curved guide element, the tornadoes of the pair developed
in each jet have the same directions of rotation as the
tornadoes în the zone of interaction of the jet flow with
the blast. In view of thisl any residual rotation of the
tornadoes of the jets will reinforce the toration tornadoes
in the zone of interaction of the jets with the blast.
In summary of the above, therefore, the present
invention may be broadly defined as providing a method for
attenuating attenuable material, comprising establishing a
gaseous jet, developing a pair of counter-rotating tornadoes
in the jet flow by deflecting the jet in a curved path and
shielding the lateral sides of the deflected flow from in- ~
duced air currents, thereby developing a pair of counter- ~ ;
rotating tornadoes w~th their aplces adjacent the lateral
sides of the curved flow and with a zone of substantially
7~ laminar flow at the concave side of the curved flow path -
between the upstream portions of the tornadoes, and delivering
a stream of attenuable material into the zone of laminar flow. `
The above method may be carried out by way of appar-
atus for use in fiberizing attenuable material comprising
- means for establishing a gaseous blast, means for establish-
ing a gaseous jet, a jet deflector in the path of the jet,
the deflector having a deflecting surface concavely curved
along the jet flow path, the deflector havlng a jet delivery
end positioned to direct the jet transversely into the blast,
.
and means for feeding a stream of attenuable material into
the influence of the jet in the region of the deflector.
Furthermore the above method may be effected through
apparatus for use in fiberizing attenuable material compris-
ing means for establishing a gaseous jet, a jet deflector in
pg/~") - 6 -
6~7
,
the path of the jet, the deflector comprising a trough-
shaped element receiving the jet toward one end thereof
and delivering the jet from the other end thereof, the
element being concavely curved axially of the trough,
and means for feeding a stream of attenuable material
into the influence of the jet in the region in which
the jet is flowing through the trough of the deflector
element.
The arrangement of the present invention as brief-
ly described above, provides an effective technique for
fiberizing attenuable material and in which each stream of
attenuable material is preferably subjected to a two stage
attenuation without, however, fragmenting the stream. The
foregoing and various other objects and advantages will be
brought out more fully hereinafter in the following detail- ~`
ed description of the invention in connection with the 1 -
accompanying drawings. ~ -~
BRIEF DESCRIPTION OF DRAWINGS
, ~
Figure 1 is a somewhat diagrammatic perspective
view of the major fiber producing and collecting components
- of a system according to the present invention incorporating
a plurality of flberizing centers each arranged ln the manner
above briefly described, the view illustrating certain parts
3 in section, and one portion of the system being broken out
in order to facilitate illustration of certain characteristics
.,j ,~
of the system;
~3~ ~
~ Pg/~? - 6A - I
7
:.,
:
Figure 2 is an enlarged fragmentary perspective .
view of one of the jet generating and guiding devices and -
of the jet flow developed thereby, and further showing the :~
delivery of a stream of attenuable material to the jet flow; :.~
'''
Figure 3 is an enlarged vertical sectional view . ;;
through the components of one fiberizing center taken in
, .. .
the plane of the jet and of the device for delivering the , : .
stream of attenuable material to the jet, this view also ~--
; showing a portion of the blast generating means and par- ;
. 10 ticularly illustrating certain dimensions to be taken into i
account in establishing operating conditions in accordance
with the preferred practice of the present invention;
~s~
Figure 4 is a fragmentary elevational view taken --
substantially as indicated by the line 4-4 on Figure 3;
~ ,
'~1 15 and
~.i, . :
", ! . .'
Figure 5 is a horizontal sectional view through
~,:! a portion of the delivery means for the attenuable material,
:~; also indicating certain dimensions to be taken into account.
, ' i :
~"
,}~ DETAILED DESCRIPTION
~s,
20 As above mentioned since the technique of the
.~ present invention is especially useful in the attenuation
. of glass and similar thermoplastic materials, the following
description refers to the use of glass as the thermoplastic
.~ material.
'~
:.: -7-
.,
.. . ... . . . . . .
~$~ 7
Referring first to the general arrangement of ~ :
the components of the fiberizing system of the invention,
particular reference is made to Figure 1 which somewhat
diagrammatically illustrates an installation embodying a
S plurality of fiberizing centers.
A blast delivery device is indicated at 6. This
may comprise a delivery nozzle associated with a burner,
thereby delivering a hot gaseous blast of the products of
combustion, the blast being indicated at B. The blast is
desirably of greater width or transverse dimension than
the jets to be described below.
:.
A manifold 7 for supplying the gas for the jets, : -
for instance compressed air, is arranged in spaced relation
to the blast delivery device and a series of jet delivery
; 15 devices 8 are associated with orifices in the jet manifold
7. . ~ .
Each of the devices 8 (see also Figure 2) is con- :
veniently formed of a bent tube or elbow, of either constant
or varying radius, one end of which is secured in an orifice
in the manifold wall. The concave portion, for instance
about one-half of the elbow is cut away or removed, thereby :~
leaving a trough shaped delivery and deflecting device 9.
As seen in Figure 2, a glass bulb or cone 10 is
associated with each of the jet delivery devices, the glass
cone being delivered from an appropriate supply device not
shown in Figures 1 or 2 but illustrated in Figures 3, 4
and 5. Thus, a bushing 11 is shown in Figure 3, this bush-
. ~ . - .. ... - -
. . . . .
ing desirably being of width sufficient to overlie the series
of jets, and the bushing being provided with a series of
glass delivery devices, each including a metering orifice
12 and a delivery reservoir 13.
,-:
From the above it will be seen that each fiber-
izing center includes a jet delivery device and a glass
delivery device associated with each other and in addition
associated with the blast, and each one of the fiberizing
centers operates to produce a single filament.
.'`'' ,' ' ~ ,
'` 10 In considering the action occurring at each fiber-
izing center, attention is directed to the enlarged view
J of Figure 2 which somewhat diagrammatically illustrates ~;
the action which occurs in the delivery or discharge of
each jet. Because of the curvature of the jet delivery
: ,,; . - .
~;~ 15 device 9 and because ofthe shielding of the lateral sides
,~ of the jet in the trough of the element 9, there is a ten-
! dency to develop whirling currents or tornadoes adjacent
the opposite sides of the concave trough 9, these tornadoes
~,;
being indicated in Figure 2 at 14, the direction of rotation
20 being shown by the arrows. The tornadoes 14 have their
apices or points of origin adjacent the side walls of the
,~,;
concave trough of the device 8, and the tornadoes develop
and enlarge in the downstream direction, progressively merging
with the intermediate laminar flow portion L of the jet. -~
25 The zone of substantial laminar flow is characterized by ~ ~;
~ pronounced inflow of induced air, indicated by the arrows ~;
:~'
g_
., ,. ' ~
- - : , , ,
on Figure 2, and this air induction tends to draw the stream
of glass from the bulb or cone 10 and to cause that stream
to enter the jet flow in the laminar flow region between
the tornadoes 14.
In Figure 2 attention is called to the fact that
the jet flow is broken out downstream of the point where
the reference numeral 14 is applied to the tornadoes, and
the tornadoes gradually merge in the downstream direction
:~ and become less distinct, as is indicated by the dash line
illustration toward the lower right corner in Figure 2. `
Comparison of Figures 1 and 2 also shows that the tornadoes
of the pair developed in each jet and the tornadoes developed
as a result of penetration of the jet into the blast, have ~
the same directions of rotation. ~ -:
' 15 Induction of air into the jet continues and the
jet flow then proceeds downstream at an inclined angle as
illustrated particularly in Figure 1 so that each jet pene- - .
trates and meets the blast B, with resultant attenuating
, action referred to hereinafter.
-
As above mentioned, the stream of glass enters
the zone of laminar flow of the jet intermediate the develop-
ing tornadoes, this entry of the stream being indicated
" at S in Figure 2. The stream is then advanced by the action
of the tornadoes and is in facet subjected to a preliminary
attenuation by the jet action in the zone between the pair
of tornadoes, thereby progressively diminishing the size ~-
of the stream to form a filament. The entry of the glass
--10--
stream S into the zone of substantially laminar flow is :-
of advantage for several reasons including the fact that
the absence of turbulence in the zone into which the glass
is introduced diminishes tendency to fragment the glass
stream, and thereby assists in producing filaments or fibers
of substantial length. In addition, the induced air cur- :
rents in the region of the zone of laminar flow tend auto-
matically to draw the glass stream into the mid region be~
tween the tornadoes, and this tendency is of sufficient ~;
magnitude to automatically compensate for some misalignment
of the glass delivery orifice in relation to the jets.
.~ :
Although, the attenuation of the glass stream
effected in the influence of the jet may be sufficient to
`~ provide a fiber product useful for certain purposes, it
is preferred to effect further attenuation in the influence
of the blast, as described herebelow, and the fiber will :-
. thereby be subjected to two sequential stages of attenuation.
~ .
As seen in Figure 1, the second stage of attenua-
tion occurs as a result of the penetration of the jet into `~ ;
the blast, thereby establishing a zone of interaction in -
which the attenuation occurs in consequence of toration,
; such toration being extensively analyzed and considered
in various of the applications above identified, especially
in the Canadian application 196,097 and also in copending
,,
Canadian application 290,246. ~-
:~
-11-
, . .. . . . . .. . ..
For the purposes of effecting toration, the jet -
is directed toward and penetrates the blast. Such penetra-
tion occurs in consequence of employment of a jet having
a kinetic energy per unit of volume which is greater than
that of the blast. In addition, the cross section or at
least the cross sectional dimension of the jet should be
smaller than that of the blast in a direction transverse
of the blast. The dimensional and kinetic energy relation- `
ships just referred to, should exist at the zone of penetra-
tion of the jet into the blast, and since, in accordance
with the present invention, the jet flow at the time of
~- penetration into the blast is made up of the merged torna-
does 14a and the induced air, it is necessary to employ
~;~ jets of higher kinetic energy at the point where the jet
~; 15 is discharged through the orifice in the wall of the jet
manifold 7.
~ .' - ~ ,
As explained in the Canadian applications above
referred to, the penetration of the jet flow into the blast
~` results in the development of a pair of tornadoes which
appear in Figure 1 at 15 in the region where the jet and
; blast have been broken out. The pairs of tornadoes 15 are
also counter-rotating in the senses indicated in Figure
;~ 1, and at each fiberizing center, the partially attenuated
stream or filament is subjected to an additional attenuating
force under the influence of the high velocity currents
associated with the tornadoes 15, thereby effecting a second
stage of attenuation and producing a fine fiber.
'~
~ .
~ -12-
~ ~6~a ~
The fibers produced in this way as a result of
the action of the several fiberizing centers in an installa-
tion such as diagrammatically illustrated in Figure 1 are
appropriately collected, for instance by being laid down
on a perforated fiber collector such as indicated at 16 :~
in Figure 1. This conveyor travels over one or more suc-
tion boxes such as shown in 16 in consequence of which the
fibers are laid down as a fiber blanket or mat F on the
moving conveyor 16 in the general manner illustrated in
Figure 1 and more fully described in various of applicant's
prior Canadian applications fully identified hereinabove.
~' ~
- It will be understood that an appropriate binder
such as a resin binder may be sprayed upon the fibers, for
instance in the region of the zone broken out in Figure
1, and the binder carrying fiber may be delivered by the ~ :~
conveyor 1~ to an appropriate facility, such as an oven,
for curing the binder.
As above indicated, it is desired to employ a - :
jet having a greater kinetic energy per unit of volume than
that of the blast regardless of the temperature of the :-~
gases. This may be achieved in various ways, for instance
by utilizing for the jet and blast gas supplies originating :~ -
with burners, so that both of them are at elevated temperatures,
and therefore at low density, and in this event, the desired
high kinetic energy of the jet may be attained by employing
a jet velocity higher than that of the blast. On the other
hand, it is also possible to establish the desired kinetic
energy relationship by employing a jet of relatively low
; temperature, and therefore of high density, for instance
compressed air at room temperature, the blast being gen-
erated by the use of relatively high temperature combustion
products, and in this case, the velocity of the jet need
- not be as high as where the jet is generated from high
temperature gases. Indeed, with a relatively low tempera-
- ture jet, the velocity of the jet may even be lower than
the velocity of the blast and still provide the desired
kinetic energy relationship between the jet and blast, i.e.
a relationship in which the kinetic energy per unit of volume
- of the jet is higher than that of the blast so that it will
-~,3,~ penetrate into the blast and thus provide the desired tora-
tion zone of interaction between the jet and blast.
Turning now to Figures 3, 4 and 5, it is noted
that these figures indicate the relationship between the
three major components of a fiberizing center, i.e. the
means for developing the blast, the means for developing
the jet and the means for introducing the attenuable ma-
terial. In these figures, symbols or legends have been
applied to refer to various parameters, such as ranges and
angles, all of which are referred to in one or another of
the tabulations herebelow. The tables give not only ap-
propriate ranges, but also indicate certain preferred values.
-14-
In considering the symbols and legends, reference
is first made to Table I indicating values for the bushing
11 and the devices for the supply of the attenuable material. ~ -
TABLE I
~ 5 (mm)
:. Symbol Preferred Range
Value
d 2 1- ~ 5
1 1 1 3 5 : ~
lR 5 0 > 10
d 2 1 > 5
DR 5 1 > 10
;:
With reference to the jet supply, see the follow~
ing table.
TABLE II
(mm, degree)
Symbol Preferred Range
Value
dJ 2 0.5 ~ 4 :
lJ 3 1 > 15
YJ 5 1.0- >
45 20 ~goo
RD 2.5 2 ~ 3
dJ
With regard to the blast, note the following table.
TABLE III
(mm)
Symbol Preferred Range
Value
1 10 5~ 20
Certain interrelationships of the components are
also to be noted, as given in the table just below. ~
- ~ '
TABLE IV ; ~ -
(mm, degree)
Symbol Preferred Range ,~
Value ;
JB 45 20 ~ 90
BJ -5 +10 ~ -20
JF 5 1 ~ 8
JF 5 0- ~ 15
ZJB 20 15 > 35
DB 16 o - ~30
lD 2 1- ~ 3
In connection with the symbol XBJ, it will be
noted that in the illustration of Figure 3, XBJ is indicated -~
at a negative value, i.e., with the blast nozzle in a posi-
tion (in relation to the direction of flow of the blast)
which is upstream of the position of the jet.
n~
With reference to the dimension ZDB it will be
noted that it is contemplated that the lower edge of the
deflector may be positioned at th boundary of the blast,
and in this event the tornadoes of the jet continue into
and reinforce the tornadoes formed in the toration or inter-
action zone in the blast, thereby providing improved con-
tinuity of the attenuation effects of the jet flow and the
blast.
The number of fiberizing centers may run up to
as many as 150, but in a typical installation where glass
or some similar thermoplastic material is being fiberized,
- a bushing having 70 delivery devices or orifices is ap-
propriate.
The term "supply orifice" for attenuable material
used in the description is to be interpreted in a broad
sense; it can mean either an isolated orifice carrying material
toward a j~t flowing in a deflector, or a feed slot associated
with a row of jets, or a series of orifices. The row of
orifices can be replaced by a slot disposed transversely
to the flow of the blast, downstream of a row of jets and
associated deflectors, attenuable material issuing from
the slot thereby being divided by the action of the jets
including the induced air currents, into a series of cones
with ~treams of the material extending from the cones and
entering the laminar zones of the individual jets.
-17-
~ ~$Ç~ ~
In connection with the operating conditions, it
` is first pointed out that the conditions of operating the
system according to the present invention will vary in accor- -
dance with a number of factors, for example in accordance
; 5 with the characteristics of the material being attenuated.
As above indicated, the system of the present
invention is capable of use in the attenuation of a wide
range of attenuable materials. In the attenuation of glass
or other inorganic thermoplastic materials, the temperature ~
of the bushing or supply means will of course vary accord- ;-
ing to the particular material being fiberized. The tempera-
ture range for materials of this general type may fall be-
tween about 1400 and 1800C. With a typical glass composi-
tion, the bushing temperature may approximate 1480C.
The pull rate may run about 20 to 150 kg/hole
per 24 hours, typical values being from about 50 to about
80 kg/hole per 24 hours when fiberizing typical inorganic
thermoplastic materials as referred to in the preceding
paragraph.
Certain values with respect to the jet and blast
are also of significance, as indicated in tables just below
in which the following symbols are used, these values being
applicable for typical inorganic thermoplastic materials
above referred to.
T = Temperature
p = Pressure
V = Velocity
p = Density
-18-
TABLE V - JET
Symbol Preferred Range
Value
pJ (bar) 2.5 1 ~ 50
: 5 TJ (C) 20 10 ~1100 ~ -
- VJ (m/sec) 300 200~ 900
2 ) 2.1 0.8~ 40 .
TABLE VI - BLAST
Symbol Preferred Range
Value
pB (mbar) 95 30 -~ 250 ~
TB (C) 1450 1350 -~ 1800 ~ :.
VB (m/s) 320 200~ 550
~ B) (bar) 0.2 0.06-~ 0.5
It is to be kept in mind that where both the jet
and blast are employed, it is contemplated that the jet
shall preferably have a cross section smaller than that
of tbe blast and shall penetrate the blast in order to
develop a zone of interaction in which the secondary or
: 20 toration phase of the attenuation will be effected. For
this purpose, the jet must have greater kinetic energy than
the blast, per unit of volume of the jet and blast in the
operational area thereof. Typically the jet and blast may
have kinetic energy ratio of 10 to 1.
' -19-
~1~$6~7
.: :
The technique of the present application is of
advantage for numerous reasons some of which are in common
with certain of our prior applications above referred to
and some of which are distinctive to the technique of the
present application, and various of the advantages are of
significance in connection with the fiberization of various
materials and especially of thermoplastic mineral composi-
tions such as glass and other similar materials. Thus,
stability of introduction of the glass and consequent stabil-
ity of the glass cone is provided, notwithstanding substantialseparation of the major components of the system, includ-
ing substantial separation or interspacing between the glass
supply means, the jet device, and the blast generator. -~
Separation of these components, in turn, makes possible
more accurate control of the relative temperatures prevail-
ing in or at the several components, and temperature control
is desirable for effective and efficient fiberization.
The technique of the present invention also pro-
vides for development of pairs of tornadoes in the jet flow,
which pairs of tornadoes are highly stable, especially in
that they have their apices or points of origin within the
curved trough-like jet deflector, in view of which the points
or origin of the tornadoes are substantially fixed. This,
in turn, provides for stability of feed of the attenuable
material. The use of the individual trough-like deflectors
also provides for the development of the tornadoes in each
jet flow independently of the adjacent jets, and in view
of this, any desired spacing of the jets may be employed.
-20-
..
