CA1115523A - Suppression of pollution in the manufacture of glass fibers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Method and apparatus for suppression of pollution in the manufacture of glass fibers by toration, i.e., by the technique in which attenuable material is fiberized by admitting the attenuable material into the zone of inter-action of gaseous jets directed transversely into a larger gaseous blast, the material being acted upon in the inter-action zone of the jet and blast to produce a highly atten-uated fiber. Most of the gases in the region of the tora-tion operation are freed of pollutants and are recirculated.

Description

5 S;f~

~UPPR~SSION OF POLLUTION IN
THE MANUF~CTURE ~F GLASS FIBERS

In our Canadian application No. 196,120, filed March 27, 1974, there is disclosed a new technique for pro-ducing fibers from attenuable materials, such as molten glass. Thus, in said prior application a gaseous jet is arranged to penetrate transversely into a larger gaseous .
blast in order to establish a zone of interaction, and the attenuable material such as the molten glass is admitted into the zone of interaction and this results in attenua-tion of the attenuable material thereby forminq filaments.
For introduction of the glass or other attenuable material into the zone of interaction, a stream of the molten glass~ :
is delivered from a glass supply orifice usually located in a position which, with reference to the blast, is down-stream of the jet. This fiberization technique is reEerred to as "toration" in the prior application above referred to.
' The present invention is concerned with improve-ments and variations both in the apparatus and in the method for making glass fiber blankets or mats by toration, i.e~, by techniques of the kind disclosed in the prior applica-tion above identified.

One aspect of the improvements of the present invention relates to the provision of certain features of :
apparatus and method for suppression of pollution in the --1-- ,, , *~^~

~15SZ3 manufacture of glass fiber blankets or the like. In our Canadian application No. 210,777, filed October 4, 1974, there are disclosed certain techniques for the :
suppression of pollution in glass fiber manufacture .
as applied to a variety of fiberizing techniques, and the present invention is concerned with adapta- ~ .
tion.s of certain of the techniques disclosed in application No. 210,777, which ~dàptations are particu-larly adapted to the suppression of pollution in fiberizing techniques of the kind disclosed in appli- .
cation No. 196,12û.

The present application is a division of our prior application Serial No. 245,255, filed February 9, 1976.
In one aspect of the invention, there is provided a method for forming a fiber blanket on a perforated ;
fiber-collecting surface defining at least a large part of one wall of a fiber-collec:ting chamber, comprising ~: ~
delivering streams of molten thermoplastic material into :
the chamber in a region spaced from the fiber-collecting surface, effecting fiberization of the streams by devel~- :
oping a gaseous fiber-attenuating current flowing from the region of the streams to and through the perforated collecting surface, and separating the gaseous curxent downstream of the collecting surface into por-tions and recirculating the portions to different regions of the chamber. .

pg/~ 2 -:..

SSZ~
In another aspect of -the invention, there is provided equipment for making glass fiber blanket comprising a sub-stantially closed fiber-receiving chamber, a perforated fiber-collecting conveyor defining at least a large part of one wall of the chamber, means for delivering streams of molten thermo-plas-tic material into the chamber, means for fiberizing molten material including jet means for effecting gaseous attenuation of the molten material in a r~gion spaced from the collecting conveyor, suction means for withdrawing gases from the chamber through the fiber-collecting conveyor and thereby form a fibrous blanket on the conveyor, means for spraying water and resin binder material on the fibers in the fiber-receiving chamber, and means for recirculating at least a portion of the gases into the fiber-receiving chamber.
According to another aspect of the invention there is provided equipment for making fiber blanket comprising a sub-stantially closed fiber-receiving chamber, a perforated fiber-collecting conveyor defining at least a large part of a wall of the chamber, means for admitting a stream of molten glass . 20 into the chamber, means for fiberizing molten glass including jet means for effecting gaseous attenuation oE the molten glass in a region spaced from the collecting conveyor, means defining a channel for directing the attenuated fibers from the region ~ to the collecting conveyor, suction means for withdrawing gases : from the chamber through the fiber~collecting conveyor and thereby form a fibrous blanket on the con~eyor, means for spraying water and resin binder material on the fibers after delivery from the channel, means for separating water with :
resinous materials carried thereby from the gaseous ; ~
sd/~ 3 : .

sz~
-currents, and means for recirculating at least a portion of the gases to and through the fiber~direct-ing channel.
The features of the present invention can most readily be explained after consideration of at least some of the equipment as represented more or less diagrammatically in the accompanying drawings in which the various figures may be hriefly described as follows:

pg/t~

.. . ..

S~3 Figure 1 is a schematic representation of all of the major components of one embodiment of a plant incor-porating not only the equipment of a plant for effecting fiberization of molten ~lass by toration and the formation of a Eiber blanket, but also various devices for suppres-sion of pollution, as will be described more fully herein-after.

Figures 2 to 12 inclusive are somewhat diagram-matic and schematic outline views of another plant of the general kind above referred to but illustrating various additional structural parts and relationships thereof, and in which:

Figure 2 is a schematic outline perspective repre-; ;
sentation of the major components of both the fiberizingand pollution suppression equipment of this embodiment;

Figure 3 is an outline plan view of the equipment shown in Figure 2, Figure 3 being taken generally as indi- .
cated by the arrow C applied to Figure 2;

Figure 4 is an outline end elevational view of the equipment of Figure 2, taken generally as indicated ~ ;
by the arrow D on Figure 2, but omitting certain parts for the sake of simplicity;

Figure 5 is a side outline elevational view, taken generally as indicated by thP arrow E on Figure 2, but also omitting certain parts, and having additional parts broken away to disclose others lying within;

S7~ , Figure 6 is an enlarged diagrammatic outline view of equipment associated with one of the fiberizing stations viewed in the same direction as Figure 5 and with certain ~.
parts shown purely schematically in order to simplify the illustration;

Figures 7 and 8 are flow diagrams illustrating the action of one form of adjustment means provided for enhancing uniformity of fiber distribution in the fiber blanket being made; and ~ ' `'`~
Figures 9 and 10 are additional diagrams of fiber distribution patterns which may be accomplished by ad~ust- .
ment of certain devices diagrammatically illustrated in Figures ll and 12.

The advantages and features of the arrangements :;
of Figures 1-12 can most readily be explained after considera tion of at least some of the equipment as represented more or less diagrammatically in the accompanying drawings.
Therefore, reference is first made to Figure 1 and in connec-~: , tion with that figure, it is to be noted that while certain aspects of the equipment for fiberization and fiber collec-tion may be physically arranged in the general manner indi~
cated in Figure l, the principals to be explained with rela-tion to Figure 1 are not necessarily limited to that arrange-ment, but are equally applicable to other arrangements such as that shown in Figures 2 to 12.

-6- :

.

SS~

It is also to be noted in connection with the following description of Figure 1 that certain of the parts of the fiberization equipment there shown are identified by reference numerals which are either the same as or related to those employed in Figures 15A, 15B, 15C and 15D of our prior application Serial No, 196,1~0, above referred to, and that certain of the parts of the pollution suppression equipment are identified by reference numerals which are either the same as or related to those employed in the draw-ings illustrating various of the embodiments of pollution suppression equipment as disclosed in the drawings of our copending application Serial No. 210,777, above identified.

In addition to certain features of the pollution suppression equipment which are arranged in the same manner or in the same general manner as in our copending application Serial No. 210,777, the present application also discloses other features of arrangement which are not disclosed in said prior application.

Considering now the fiberization equipment shown in Figure 1, reference is first made to the blast or princi :
pal jet generators 154, 156 and 158 and also to the cooperat-ing secondary or carrier jet generators 14~, 150 and 152.
Thes~ generators produce interacting jets which, as is fully disclosed hereinabove/ create zones of interaction into which molten glass is admitted rom orifices in the crucibles . :~

142, 144 and 146. The molten glass may be supplied to the crucibles, for instance from the forehearth branches 136, 13B and 1400 .

.. ..
,. , " ~ . .

s~

As e~plained herein and also in our priar applica-tion 196,120, a plurality of secondary jets are preferably associated wi~h each blast, and a plurality of glass streams, one associated with each secondary jet, are admitted into ~ ~
each blast, thereby providing groups of fiberizing stations ;
associated with each blast generator 154, 15~ and 158.
Still further, a plurality of the blast generators and asso~
ciated generators for secondary jets, and also orifices for admission of glass streams, are provided transversely of the equipment. Thus, when viewed as in Figure 1, each blast generator, for instance the generator 154, represents only one of a series which are aligned with each other.
All of the fiberizing centers established by the groups~ ~;
of generators deliver the attenuated fibers into a common ~;
hollow guide 168, 170 or 172. These guides, in effect, form channels for directing the fibers from the several groups of fiberization stations downwardly in an inclined path from the zone of fiberization toward the perforated fiber-collecting conveyor 180. Guides of this type are desirably tapered in plan form to provide a progressively reduced width, for instance in the manner shown in Figure 15B of the prior application 196,120.

' As is fully explained in our application Serial No. 196,120, each jet is of smaller cross section than the blast and has kinetic energy greater than that of the blast in the operational area thereof. This may be achieved by employing a jet of higher velocity than the blast.

- , , ~ . . ..

As will be understood, the gases from the blast generators and the jet generators in each group flow with the fibers into the upper or inlet ends of the channels fQrmed in the hollow guides 168, 170 and 172, and each of these fiber and gas streams is indicated in Figure 1 by the reference numeral 12.
' ~
As seen in Figure 1, the fiberization equipment is arranged in spaced relation to the fiber-collecting conveyor 180 and is located in a fiber-receiving chamber 100 formed by various wall elements and preferably being substantiall.y closed. The fiber-collecting conveyor 180 defines at least in large part one of the walls of the collecting chamber and this conveyor serves to carry the formed blanket to the left out of the chamber below the left hand end wall.
As will be understood, appropriate openings are provided for the introduction of the fuel and air needed for the blast and jet generators, and in addition~ there are openings appropriate to the accommodation of the molten ylass fore-hearth branches and crucibles to provide for admission of the molten glass into the fiberization equipment~

To provide for collection of the fibers on the perforated fiber-collecting conveyor, suction chambers 16 are positioned beneath the fiber-collecting run of the con-veyor, the chambers being open at the top and having ducts :

17 connected therewith and respectively communicating with cyclone separators 18. Each cyclone separator has an offtake connection extended to a blower or exhaust fan 19 which discharges the exhausted gases into the duct 34, constitut-ing a recirculating duct which is connected with one end of the fiber-receiving chamber 100. Baffles 132 in the region where the duct 34 is connected with the chamber 100 serve to uniformly distribute the recirculating gases in the fiber-receiving chamber.

For the purpose of cooling the fibers as they are delivered from the guides 168, 170 and 172, water sprayers .` `:
50 are provided, preferably both abo~e and below the fiber and gas stream 12 delivered from each of the guides. Down-stream of the water sprayers, additional spray nozzles 13 are provided and these additional nozzles serve to spray onto the fibers a liquid binder resin material, preferably a binder which is adapted to harden or cure upon subsequent "
heating of the formed blanket, for instance in an oven through which the blanket is delivered after being discharged from the left of Figure 1.

Because of the spraying of the fibers with the water and with the liquid binder resin material, the gases which are withdrawn through the suction chambers 16 carry with them substantial quantities of moisture and also resin ": ~ , ss~

constituents. It is contemplated that such constituents and also small fiber pieces which may be carried through the collecting conveyor by the gases being exhausted, should be removed from the gases before recirculation thereof back into the fiber-receiving chamber. This separation is effected in the embodiment illustrated by means of the cyclone separators 18. The separation is enhanced and assisted by the scrubbing action sf additional water spraying nozzles 45 which are arranged within the suctio~ chambers 16.

The general flow pattern of the gases in the recir-culating system shown in Figure 1 is indicated at various places by the arrows 29. In the fiber-receiving chamber, the gas flow is not only established by the exhaust fans 19, but also tends to be augmented by the action of the blast and jets at the fiberizing centers. Because the upper ends of the guides 168, 170 and 172 are open in the zones of the fiberizing centers, portions of the recirculating , gases are induced to enter the upper ends of the guides and other portions join the gas and fiber streams 12 beyond the discharge enas of the guide.

The liquid constituents which are separated in the cyclone separators 1~, together with various constituents entrained thereby are discharged from the lower ends of the separators through the discharge openings 25 and collect , in the sump 103, and in this way, various of the liquid and solid constituents which are picked up or entrained by the gas flow stream are separated and isolated, so that they are not returned into the fiber-receiving chamber with the recirculating gasesO For further suppression of pollu-tion, these separated liquids are specially treated as will be described hereinafter, but here it is first noted that although virtually all of the gases which are drawn from the receiving chamber through the fiber-collecting conveyor are recirculated to the fiber-receiving chamber, some gases are withdrawn ~rom the receiving chamber through the duct ;
35 under the influence of the fan 44. This fraction of the circulating gases represents a quantity on the order of 5~ to 10% of the total amount flowing through the per-forated collecting conveyor and represents approximately that percentage of additional gases which are constantly being introduced under the action of the blast and jet gen- ~ ~-erators employed at the fiberization stations. The gases withdrawn under the action of the fan 44 are delivered into and through a burner device 39 in which the temperature is elevated to a point preferably above 600C, after which the treated gases may be expelled to the atmosphere sub-stantially without objectionable pollution. All of the remaining 90~ to 95~ of the gases are recirculated, and thus do not pollute the atmosphere.

In addition to recirculation of the gases, the system in Figure 1 also contemplates treatment of and recir-culation of water delivered from the cyclone separators .

~ 5~

18. For this purpose, a pump 104 transfers the water from ~
, ~
the sump 103 into the tank 52, a screen or filter diagram- ~ -matically indicated at 51 being interposed in order to sepa-rate solids before the water is delivered into the tank.
The water is recirculated from the tank 52 by a pump 53 through the heat exchanger 105 for the purpose of cooling the water, the cooled water being returned to the tank 52 through the screen or filter device 51 providing for separa-tion of solids. The cooler 105 is adapted to be cooled by a heat transfer medium recirculated by means of a pump 107 through the cooling unit 106. The details of construc-tion of these parts may take a variety of forms and need not be considered herein as they form no part of the present invention per se.

Water is also withdrawn from the tank 52 by means of pump 55 and is delivered thereby, preferably under suit-able adjustable controls not illustrated, to the water spray nozzles 50 and 45. The pump 55 may also deliver water to the station 108 for preparation of the fiber binder or siz-ing which may take any suitable form and from which the binder material is delivered to the spray nozzles 13. ~;
:' Still further, some of the water is preferably delivered to the station 109 or treatment to separate resin constituents carried in solution. This is preferably efected in the manner more fully described in our application Serial ~;

No. 210,777, according to which the water is subjected to an increased pressure and to an increased temperature, after which it is cooled. This treatment results in insolubliz-ing resin constitutents, which may then readily be separated, for instance by means of a centrifuge. The purified water is then returned to the tank 52 for reuse. The solid con-stituents separated at the station 109 and also by the filter 51 associated with the tank 52 are transferred by means of suitable conveyors 112 and 57 to the waste treatment station 113 which, as disclosed in our application just mentioned, may consist of a heater or burner in which the solid waste materials are brought to a temperature of the order of 600 to 700C so as to burn the resin binder con-stituents present and also to sinter any fibers present.
The latter may, if desired, be reintroduced into the fiber circulation system, i.e., into the constituents from which the molten glass is prepared for fiberization.

Make-up water may be introduced into the system by means of the supply connection 111 delivering into the ;
tank 52.

Various of the foregoing structural and opera-tional features described with reference to Figure 1 are also incorporated in the embodiment illustrated in Figures

2 to 12, but in addition, certain portions of the equipment are differently arranged and further advantageous features are incorporated in the arrangement of Figures 2 to 1~.

s~

For the purpose of this explanation and description, reference is first made to Figure 6 which is a schematic illustration of one of several fiberizing units or stations incorporated in the equipment shown more generally in Fig-ures 2, 3, 4 and 5. As above indicated, Figure 6 also sche-matically shows the relationship of parts at a fiberizing station on a much larger scale than the other figures of this group. Molten glass may be fed to the station shown in Figure 6 in the same general manner as described above with reference to Figure 1, i.e., by means of a forehearth branch 136 communicating with a crucible 142 having a bush-ing as shown, with apertures from which streams of molten glass may be admitted into the fiberizing zones as estab-lished by the interaction of secondary jets created by the generator 148 and delivered through jet nozzles as shown, cooperating with the blast delivered from the discharge ;
lips of the blast generator 154. The gas and fiber stream :
12 delivered from this fiberizing station is received in ~, .
the upper or open inlet end of the tubular guide 168 which ' directs the stream downwardly to the perforated fiber-collect-ing conveyor 180 (see Figures 2, 3 and 5).

As in the arrangement of Figure 1 and further as in various of the arrangements described in our prior application 196,120, for instance in connection with Fig- :
ures 15A, 15B, 15C and 15D of said prior application, the ~ -~

fiberizing centers are arranged in multiple transversely of the collecting conveyor and in addition, the fiberizing units or stations are multiplied lenythwise of the collect-ing conveyor as is schematically illustrated in Figure 5 wherein five forehearth branches 136 to 140 are shown, as well as the five associated tubular guides 168 to 172.

In Figure 3, the mul~iplication of the fiberizing stations transversely of the collecting conveyor 180 is indicated schematically at a to f.

Figure 3 also shows in dot and dash outline the location of the forehearth branches 136 to 140 for feeding each of the groups of fiberizing stations a to f. These forehearth branches may be fed from a forehearth as indi-cated at FH. ;~
:':
It is to be understood that each one of the fiber-izing stations a to f will include a plurality of fiberiz-ing centers, i.e., a plurality of secondary jets cooperat-ing with individual streams of molten glass, in the manner fully developed hereinabove.

"
In the embodiment illustrated in Figures 2 to 12 inclusive, and especially in Figures 3 to 6 inclusive, various reference characters have been applied to parts of the equipment corresponding to many of the parts shown in Figure 1. It will be seen, however, that Figures 2 to 12 inclusive schematically represent a different organiza-tion and arrangement of a number of the structural features and devices employed~ Svme of the significant differences are discussed just below.

As will be seen in the isometric schematic view ~ .
of Figure 2 and in Figures 5 and 6, the fiber-receiving chamber 100 overlies the fiber-collecting conveyor 180 and the fiber-receiving chamber has upward extensions lOOa in the region of each one of the guides 168 to 17~, with the fiberizing equipment associated with these guides arranged at the upper portion of each extension. Portions of two such upward extensions are generally indicated in schematic outline in Figure 6 and it will be seen that adjacent exten-sions lOOa are spaced from each other sufficiently to accom- -modate an operator, as is indicated, so that the operator will have access to certain adjustable equipment to be de-scribed.
' ~

As in Figure 1, suction chambers 16 are arranged . ;:
under the fiber-collecting run of the conveyor 180, and these chambers are connected by ducts 17 with the cyclone separators 18. Exhaust fans 19 draw the gases from the suction chamber 16 through the cyclone separators 18 and ;~

-17- ;

` -~` 1115S~3 deliver the gases, after separation of liquids carried in suspension, into the duct 34 provided for recirculation of the gases. In the embodiment shown in Figures 2 to 6, the recirculating gas stream is subdivided into separate portions and reintroduced into the system at different points.
Thus, the branch ducts 34a and 34b extend laterally from the principal duct 34, and as best seen in Figures 2 and

3, the continuation of the duct 34 toward the left in those figures includes a U-shaped section 34c which delivers a portion of the recirculating gases directly into the end of the chamber 10~ upstream of the series of fiberizing stations.

Baffles 132 are also provided to uniformly dis-tribute the gas flow into the chamber 100. Adjustable vanes 101 in the duct 34c provide for control of the proportion of the gases delivered directly to the end of the chamber 100 and to the region of the fiber guides 168-17~. Control of the gas distribution between these two regions is impor-tant as it may be used to in~luence the general character of the fiber blanket, especially with respect to the orienta-tion of the fibers. Increase in the opening of the vanes with consequent increase in the amount of the gases deliv-ered into the end of chamber 100 tends to increase orienta-tion of the fibers lengthwise of the conveyor 180. On the other hand, decrease in the opening of the vanes 101 with consequent increase o~ the amount of the gases delivered to the region of the fiber guides 168-172 tends to increase the transverse orientation of fibers.

SS~;~

:, A stack or offtake flue ST is provided and may be connected with the duct 34 through the normally closed vanes 34d. A normally closed vent gate 34e (see Figure 2) is also provided. It is contemplated that for safety purposes the gate 34e and the vanes 34d may be opened, in which event air will enter the duct 34 past the gate 34e and the gases will be discharged through the stack ST instead of being recirculated.

As best seen in Figure 6, the gases which flow into the branch duct 34a are delivered through apertures adjacent to the upper or inlet end of the adjacent guide, Figure 6 illustrating this relationship with respect to the fiber guide indicated by the numeral 168. At the upper end of the guide 168, the guide is shaped to avoid turbu lence in the Elow, and the gases from this source enter the upper end of the guide in part by induction which tends to be set up b~ the blasts and jets cooperating with guide 168. Only one blast generator 154 and one jet generator 148 is shown in Figure 6, but it will be understood that these devices are arranged in multiples as is indicated schematically at a to f in Figures 2 and 3~ Such multiple arrangement is also shown in Figure 15B of our prior appli~
cation 196,120.

With further reference to Figure 6, it will be seen that some of the gases flowing through the branch duct 34b are also delivered through apertures into the region ; ~:

';

of the upper or entrance end of the guide 168 whiah i5 sim-ilarly enlarged to minimize turbulent flow. This wall further preferably includes an adjustable movable wall section 168a pivoted at 168b and provided with an adjustable screw device 168c having a handle projecting into the space between adja-cent extensions 100a of the receiving chamber, so that an operator may adjust the position of this wall section.
Preferably such a wall section, separately adjustable, is provided in alignment with each of the fiberizing stations a to f, thereby providing control over the fiber distribu-tion, as is described more fully hereinafter~ One or more access doors may be provided so that an operator may readily observe the operating conditions and may also have service access to portions of the equipment at the fiberizing centers.

From further reference to Figure 6, it will be seen that each of the branch ducts 34a and 34b is provided with additional openings for delivery of some of the gases adjacent the opposite sides of the duct 168 in the spaces provided within the upward chamber extension 100a, th2se portions of the ~ases flowing downwardly into the main part of the chamber 100 adjacent to the lower or discharge end of the guide 168.

Toward its lower end, at least one wall of the guide 168 is also desirably provided with a flexible or deflectable section 168d, with an adjustable screw 168e 5~

by which the operator may adjust the position of the flexible wall and thereby effect further control over fiber distribu-tion in the manner described hereinafter.

Referring now to Figures 7 to 12 inclusive which schematically illustrate certain aspects to the fiber dis-tribution control provided with the adjustable features above described, it is first noted that Figures 7 and 8 each indicate in outline the guide 168, the upper or inlet end of the guide being presented toward the top of these figures and the discharge end toward the bottom thereof.
It will here be seen that six pivoted wall sections 168a are indicated, these being respectively aligned with the fiberizing zones of a to f. Each one of these wall sections is, of course, pivotally mounted and adjustable in the manner described above with reference to Figure 6. At times, fiberiza-tion or fiber distribution may develop some lack of uniform-ity across the width of the guide 168, as is illustrated in the region of Figure 7 indicated by the arrow x. This condition may be remedied and the fibers more uniformly distributed across the width of the guide by adjustment of the pivoted wall section 168a lying in the path indi-cated by the let-ter x in Figure 7. The adjustment to cor~
rect would conform with that shown in Figures 6 and 8, in which the gas flow passage from the duct 34b is reduced in the zone where the fibers are not sufficiently concen-trated. The result of this is that additional fibers flowing in the adjacent zones will flow into the zone where the fiber concentration is insufficient, this action being sche-matically represented by various flow lines and arrows applied to Figure 8.

In instances where the fiber concentration is insufficient toward one edge of the guide, as compared with the other edge, (for instance toward the right as compared with the left when viewed as in Figure 9) the flexible wall section 168d may be adjusted to an inclined position by :
means of the adjustment screws 168e. The nature of this adjustment will be clear from the schematic illustration of Figures ll and 12. The effect of this adjustment is to cause some of the fiber flow to shift frQm the left toward ~ :~
the right as viewed in Figures ll and 12, this shift being schematically indicated by the flow lines in Figure lO. :
::;
From the foregoing, it will be seen that the arrange- ::
ment of the present application provides for effective and extensive suppression of pollution originating from glass ~:
fiber blanket manufacturing plants, especially plants utiliz- ~.
ing toration fo~ fiber production as herein disclosed. ~:
' ;.`
The manner of recirculating the gases present in and around the fiber equipment is advantageously util-ized, particularly by dividing the recirculating gas stream into portions which are reintroduced at different points , ~; ..
~22-:;
.

.
;5~2~

in the system, thereby increasing the uniformity of fiber distribution in the blanket being made. Tendencies for inaccuracy in fiber distribution may be corrected by adjust- ~:
able equipment readily accessible to an operator during the fiber production operation.

In connection with various of the devices of the pollution suppression equipment, for instance the units shown in Figure 1 at 39, 105, 106, 108, 109 and 113, it is pointed out that further information concerning the pol-lution suppression equipment may be found in our copending ' application Serial No. 210,777. ..

';

-23- :

Claims (11)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for forming a fiber blanket on a perfor-ated fiber-collecting surface defining at least a large part of one wall of a fiber-collecting chamber, compris-ing delivering streams of molten thermoplastic material into the chamber in a region spaced from the fiber-collecting surface, effecting fiberization of said streams by developing a gaseous fiber-attenuating current flowing from the region of said streams to and through the perforated collecting surface, and separating the gaseous current downstream of the collecting surface into portions and recirculating said portions to different regions of said chamber.

2. A method as defined in claim 1 in which one of said portions of the recirculating gaseous current is recirculated to the region of delivering of said streams of thermoplastic material.

3. A method as defined in claim 1 in which said portions of the recirculating gaseous current are recirculated to the fiber-collecting chamber in regions spaced from each other upstream and downstream of said gaseous fiber-atten-uating current.

4. Equipment for making glass fiber blanket compris-ing a substantially closed fiber-receiving chamber, a per-forated fiber-collecting conveyor defining at least a large part or one wall of said chamber, means for deliver-ing streams of molten thermoplastic material into the cham-ber, means for fiberizing molten material including jet means for effecting gaseous attenuation of the molten material in a region spaced from the collecting conveyor, suction means for withdrawing gases from said chamber through the fiber-collecting conveyor and thereby form a fibrous blanket on the conveyor, means for spraying water and resin binder material on the fibers in the fiber-receiving chamber, and means for recirculating at least a portion of the gases into the fiber-receiving chamber.

5. Equipment as defined in Claim 4 and further including means defining a channel for directing the attenu-ated fibers from said spaced region to the collecting con-veyor, a duct receiving the gases from said suction means, and means for effecting recirculation of at least a portion of said gases into the upstream end of said channel to flow therethrough in the direction of travel of the fibers.

6. Equipment as defined in Claim 5 and further including means for separating binder resin constituents from the gaseous currents before recirculation thereof to the upstream end of said channel.

7. Equipment as defined in Claim 5 and further including means for separating water with resinous materials carried thereby from said gaseous currents, and means for recirculating the gases to the upstream end of said channel.

8. Equipment for making fiber blanket comprising a substantially closed fiber-receiving chamber, a perforated fiber-collecting conveyor defining at least a large part of a wall of said chamber, means for admitting a stream of molten glass into the chamber, means for fiberizing molten glass including jet means for effecting gaseous attenuation of the molten glass in a region spaced from the collecting conveyor, means defining a channel for directing the atten-uated fibers from said region to the collecting conveyor, suction means for withdrawing gases from said chamber through the fiber-collecting conveyor and thereby from a fibrous blanket on the conveyor, means for spraying water and resin binder material on the fibers after delivery from said channel, means for separating water with resinous materials carried thereby from said gases, and means for recirculat-ing at least a portion of the gases to and through the fiber-directing channel.

9. Equipment as defined in Claim 8 and further including means for separating resinous materials from the separated water, and means for recirculating at least a portion of the water to the water spraying means.

10. Equipment as defined in Claim 8 and further including means for recirculating a portion of the gases to the fiber-collecting side of the fiber-collecting con-veyor.

11. Equipment as defined in Claim 4 and further including means for recirculating at least a portion of the withdrawn gases into the fiber-collecting chamber and adjustable means for varying the amount of gases recircu-lated.