IE42770B1 - Process and apparatus for making fibres from attenuable material for example glass - Google Patents

Abstract

1525652 Glass fibre manufacture SAINT-GOBAIN INDUSTRIES 3 Feb 1976 [10 Feb 1975] 04197/76 Heading C1M In a process for making glass fibres, in which main gaseous blasts (154, 156, 158) and secondary gas jets (148, 150, 152) are disposed at an angle to produce interaction zones, molten glass being introduced into the zones (from crucibles 142, 144, 146) for attenuation into fibres, the fibres are carried in a current of gas 12 to a perforated collection surface (e.g. conveyor 180), and at least part of the gas which flows through the surface is recycled (29) to the interaction zone. The gascarried fibres, after emerging from ducts 168, 170, 172, may be cooled by water sprayers 50 and may be sized by sprayers 13. Gas passing through the conveyor 180 may be scrubbed (45) to remove excess size or fibre scraps, before being drawn by fans 19 through cyclones 25, and returned to the chamber 100 via pipe 34 (which may be partitioned-132). The separated water may be recycled via reservoir 52.

Description

This'invention relates to a process for producing a mat of fibres from attenuable material which may be thermoplastic material for example glass, in which a main gaseous blast and a secondary gaseous 5 jet of smaller cross-section are used, the initial directions of which are at an angle to each other, the kinetic energy per unit of volume of the secondary jet being sufficient to cause it to penetrate the main blast so as to give rise to a zone of interaction/ and a stream of the attenuable material being introduced la into the said zone where the material is converted into fibre. The invention also includes apparatus for carrying out the process.

An object of the invention is to improve 5. the known process, so as to reduce atmospheric pollution hy gas used in the process, and to improve distribution of fibres on a collecting surface.

According to this invention there is provided a process for producing a mat of fibres of attenuable . material on a perforated collecting surface in which a main gaseous blast and a secondary gaseous jet of smaller cross-section are used, the initial directions of which are at an angle to each other, the kinetic energy per unit of volume of the secondary jet heing . sufficient to cause it to penetrate the main blast so as to give rise to a zone of interaction, and a stream of the attenuable material being introduced into the said zone where the material is fiherized, wherein a current of gas is caused to flow from the said zone to . and through the collecting surface so as to carry the fibres on to the collecting surface to form the mat, and wherein at least part of the gas which flows through the surface is recycled to the said zone.

Also according to the invention, apparatus . for producing a mat of fibres of attenuable material, for example glass, coap«.«es-a fibre receiving chamber, a perforated fibre collecting conveyor which forms at least a major part of a wall of the chamber, means for creating a main gaseous blast directed into the chamber, means for creating at least one secondary gaseous jet of smaller cross-section than . the blast and directed transversely to the latter, the jet having a kinetic energy per unit of volume sufficient to cause it to penetrate the main blast and give rise to a zone of interaction, means for introducing the attenuable material into the zone . where it is attenuated to fibre, suction means located downstream of the conveyor for causing gas to flow through the conveyor to form a fibre mat thereon, and means for recycling to the receiving chamber at least part of the gas which flows through . the conveyor.

The invention will now be described by way . of example with reference to the drawings, in which:Figure 1 is an overall diagrammatic view of one embodiment of the apparatus of the invention; 200 Figure 2 is a perspective diagram of a second embodiment; Figure 3 is a plan of the apparatus of Figure 2, as viewed from the arrow C in Figure 8; Figure 4 is an elevation of the end of the . apparatus in Figure 2, as seen from the arrow D in Figure 2, but omitting parts thereof; Figure 5 is an elevation as seen from the arrow E in Figure 2, but omitting certain parts and including additional parts, partly broken away; Figure 6 is an enlarged diagram of an apparatus associated with one fibre attenuating . station, viewed in the same direction as in Figure 5 and with some parts shown diagrammatically; Figures 7 and 8 are diagrams of currents representing the action of regulating means used to provide for uniformity of distribution of the fibres . in the mat or the like; and Figures 9 and 10 are diagrams showing methods of distributing fibres whieh may be obtained by regulating devices shown diagrammatically in Figures 11 and 12.

. . The fibre mat producing apparatus shown in Figure 1 comprises main gaseous blast generators 154, 156 and 158, and secondary gaseous jet generators 148, 150 and I52. Each pair of main blast and jet generators creates a zone of interaction into which . .molten glass is introduced from the orifices in crucibles 142, 144 and 146. The molten glass is supplied to the crucibles from duets 136, 138 and 140.

It is preferred to combine a plurality of secondary gaseous jets with each main gaseous blast, . a plurality of molten glass streams, each associated with one gaseous jet, being admitted into each main blast and resulting in groups of fibre-attenuating 4. -42770 centres associated with each main blast generator Ϊ54, 156 and 158. Further, a plurality of main bla'st generators and of secondary jet generators, as well as glass supply orifices may be disposed . transversely with respect to the apparatus. Thus, as can be seen in Figure 1, each main blast generator, for example the generator 154, constitutes only one generator of a series of generators aligned transversely of the apparatus. All the fibre attenuating centres . direct the attenuated fibres into a hollow guide 168, 170 or i72. These guides form ducts or channels for directing the fibres downwards along an inclined path from the fibre attenuating centres, the fibres being carried to a perforated collecting surface in the form . of a conveyor 180.

Gas emanating from the main blast and secondary jet generators of each group flow with the fibres into i the upper, inlet ends of the ducts formed by the hollow guides 168, 170 and I72, and these currents of fibres . and gas are indicated at 12 in Figure 1.

As seen in Figure 1, the fibre attenuating . means is disposed at a distance from the conveyor 180 and further is disposed in a receiving chamber 100 formed by several walls preferably mainly closed.

. The conveyor 180 forms at least a major part of one wall of the receiving chamber, and the conveyor carries the mat to the left, as seen in Figure 1, and . out oi the chamber below the left-hand wall.

Openings are provided for introduction of fuel and air needed for the main blast and secondary jet generators.

. To collect the fibres on the conveyor, suction chambers 16 are positioned below the receiving,zone of the conveyor, these chambers being open at the top and having duets 17 so that they communicate respectively with cyclone separators 18.

. Each separator 18 has a duct communicating with a suction fan 19 which delivers discharged gas ihto a pipe 34. The latter is a recycling duct connected to one end of the fibre receiving chamber 100, as shown. Guide partitions 132 are arranged in the . zone where the pipe 34 is connected to the chamber lOO and they distribute uniformly gas recycled to the chamber 100.

To cool the fibres as they emerge from the guide ducts 168, I70 and I72, water sprayers 50 are . disposed above and below the streams 12 of fibres and gas. Downstream of the water sprayers, additional spray nozzles 13 spray onto the fibres a liquid resinous binder, for example a hardenable adhesive or glue, or a thermosetting material which is hardened . during subsequent heating of the mat, for example in an oven (not shown) through which the mat passes after being discharged from the chamber 100.

Because of the sprayed water and resinous binder the gas discharged by the vacuum chambers 16 carry considerable quantities of water and resinous components. These components, as well as small scraps of fibre which may pass through the receiving . conveyor 180, are carried by the gas as it is discharged and have to be extracted from the gas before recycling to the chamber '100. This extraction is carried out by the cyclone separators 18 and separation is assisted by washing, which is carried out hy water . sprays 45 inside the vacuum chambers 16.

The flow of gas in the recycling or recirculating system shown in Figure 1 is indicated by arrows 29. In the chamber 100, the gas current is not created only hy the fans 19 hut is reinforced by . th.e action of the main blast and secondary jets from the fibre attenuating centres. Since the upper ends of the guide duets 168, 170 and 172 are open at these centres, recirculated gas enters the upper ends of the ducts, and other parts of the recycled gas are directed . towards the gas currents and fibres 12 beyond the discharge ends of the ducts.

The liquid components extracted by the cyclone separators 18, as well as various components entrained, are discharged at the lower ends of the separators at . discharge openings 25 and accumulate in a sump 103.

Thus various liquid and solid components collected or entrained by the gas current are extracted and isolated so that they are not returned to the chamber 100 with the recirculated gas. For further reduction of atmospheric pollution, the separated liquids are treated as will he described, but it is necessary . first to note that although virtually all the gas evacuated from the chamber 100 through the conveyor 180 is recirculated into the chamber 100, part of the gas is discharged from the chamber 100 through a duct 35 hy the action of a fan 44. This discharged part of . the gas is about 5 to 10% of the total quantity flowing through the conveyor and represents approximately the percentage of additional gas supplied by the main blast and secondary jet generators. The gas discharged through the duct 35 is conveyed to a . combustion apparatus 39 in which the temperature rises to over’ 600°C, the treated gas then being ejected into the atmosphere without undesirable pollution. 90 to 95% of the gas passing through the fibre mat is recycled and consequently does not pollute the . atmosphere.

In addition to recycling the gas the apparatus of Figure i provides for treatment of water emanating from the cyclone separators 18 and which is recycled. For this purpose, a pump 104 passes water from the . sump 103 into a reservoir 52; a mesh or filter 51 traps solid particles before the water reaches the reservoir. The water is pumped from the reservoir 52 43770 by a pump 53 to a heat exchanger 105 ta cool the , ♦ water. Th'e cooled water is returned to the reservoir 52. The heat· exehanger 105 is cooled by a heat transfer agent circulated by a pump 107 via a cooling . system 106. The details of construction of these elements do not form part of the invention.

Water is also drawn from the reservoir 52 by a pump 55 which directs it, via appropriate control means (not shown), to the water spray nozzles 50 and . 45- The pump 55 can also transmit water to a station 108 for preparation of binder or dressing of fibres, which may be carried out in suitable manner and whence liquid binder is conveyed to the spray nozzles 13.

Also, some of the water is carried to a . station 109 to be treated for extraction of the binder components which are conveyed in solution. At the station 109 the water is subjected to higher pressure and higher temperature, after which it is cooled.

The result of this treatment is to render the resinous . components insoluble and they are then easily extracted, for example by a centrifuge. The purified water is then returned to the reservoir 52 to be used again. Solid components extracted at the station 109 and also by the filter 51 are transferred by conveyors 112 . and 57 to a waste treatment station 113 which comprises a reheater or a burner in which solid waste is heated to a temperature of 600 to 700°C to burn the components 43770 of the resinous binder and also to agglomerate any fibres. These latter may be reintroduced into the fibre cycle, that is to say, into the components from which the molten glass is prepared for use in fibre . attenuation.

Supplementary water may be introduced into the apparatus by a supply connector ill communicating with the reservoir 52.

Various features described above with reference 10. to Figure i are incorporated in the embodiment of the apparatus shown in Figures 2 to 12, but some parts of this apparatus are differently arranged, and other advantageous features are incorporated.

Referring for example to Figure 6, which is a 15. diagrammatic representation of a fibre attenuation centre in the apparatus shown in Figures'2, 3, 4 and 5, molten glass may be carried to the centre in the same manner as described above with reference to Figure 1, that is to say by a duct 156 communicating with a . crucible 142 from which streams of molten glass may be carried into the attenuation zones created by interaction of secondary jets created by the generator 148 in conjunction with the main blast created by the generator 154. The flow of gas and fibres 12 reaches . the upper or inlet end of the hollow guide or duct 168 which directs the current downwardly towards the perforated fibre-collecting conveyor 180 which is seen in Figures 2, 3 and 5.

As in the apparatus of Figure 1 the attenuating centres are disposed in groups transversely of the conveyor as illustrated diagrammatically in Figure 5, . in which five projecting branches 136 to 140 are shown, as are also the five guide ducts 168 to 172 associated with them. in Figure 3, the arrangement of attenuating stations in rows transversely of the conveyor 180 is illustrated diagrammatically by . a to f; as can be seen, there are five such rows, each of six stations.

Figure 3 also shows in dotted lines the positions of the ducts 136 to 140 for supplying each row of stations a to f.

. ' Referring more particularly to Figures 2 to 4, various reference numerals have been applied to corresponding parts shown in Figure 1. It will be seen that Figures 2 to 12 diagrammatically show a different arrangement of some parts, which will be . considered.

As can be seen in Figure 2 and in Figures 5 and 6, the chamber 100 is above the conveyor 180 and comprises upwards extensions 100a in the vicinity of each duct 168 to 172, the fibre attenuating . device related to each duct being disposed in the upper part of each extension 100a. Parts of two of these extensions 100a are shown in Figure 6 from which can he seen adjacent extensions 100a are well spaced apart to allow room ior the operator shown to have access to control devices which will be described.

. The suction chambers 16 are below the conveyor 180 and are connected hy ducts 17 to the cyclone separators 18. The extraction fans 19 pass the gases from the chambers 16 via the cyclone separators 18 and, after extraction of liquid held in suspension, iO. through the duct 34 for recycling the gas. In the embodiment shown in Figures 2 to 6, the recycled gas current is divided into separate portions and returned into the chamber 100 at various points. Thus, duct branches 34a and 34b extend laterally from the main ig. duct 34, and as can be seen from Figures 2 and 3, the extension of the duct 34 to the left in these figures is in the form of a U-shaped section 34c which carries part of the recycled gas directly to the end of the chamber 100 upstream of the fibre attenuating stations.

. As can be seen in Figure 6, the gas which flows in the branch duct 34a is carried via apertures near the upper or inlet end of the neighbouring guide duct 168. At its upper end the duet 168 is shaped as shown to avoid backwash in the flow, and gas emanating . from this source enters the top end of the duct 168 partly by induction created by the main blast and the secondary jets. Only a single main blast generator 154 and a single secondary jet generator 148 are shown in Figure 6 but it will be understood that these devices are arranged in groups or rows as shown diagrammatically at a to f in Figures 2 and 3.

Referring again to Figure 6, part of the gas 5. circulating in the branch duct 34b is also carried through apertures in the vicinity of the duct 168 which is likewise shaped to reduce turbulence in flow, Further, the duct 168 has a movable flap 168a pivoted at 168b and provided with an adjustable screw . device 168c with a handle projecting into the area between the adjacent extensions 100a so that the , operator can regulate the position of the flap. It is independently, regulable and is in alignment with each of the fibre attenuating stations a to f, so , making it possible to monitor distribution of the fibres, as will be described below. One or several access doors ad allow the operator to observe the attenuation of the fibres and to have access for maintenance of the stations.

. Referring again to Figure 6, each branch duct 34a and 34b has additional apertures for passage of portions of the gas from each side of the duct 168 into the spaces inside the extension 100a, these portions of the gas flowing downwards in the main . part of the chamber 100 via passages contiguous with the lower discharge end of the duct 168.

At the lower end of at least one duct 168 is a wall section 168d which is flexible and deformable 13. by means of regulating screws l68e by which the operator can regulate the position and form of the flexible wall section and so exercise additional control over distribution of the fibres.

. In industrial production products are needed in which the fibre weight per unit of surface area, that is to say the distribution, iX uniform. This result is not usually achieved naturally, and it is necessary to provide means for . directing the fibres to particular locations in the mat-forming zone. The irregularities of distribution of fibres may be localised or may affect the whole mat.

Reference will now be made to Figures 7 and . θ» each of which shows in plan a duct 168, of which the upper or inlet end can be seen at the top and the fibre discharge end at the bottom. Also shown are the pivotable wall portions or shutters 168a,for correcting local irregularities in distribution.

, Each is independently regulable as described above.

The shutters 168a can be moved to a greater or less extent into the flow of air induced at 29 by the current of fibres and gas 12. When any of these shutters is thus moved, for example that for the . zone x, Figure 7, where there is a lack of fibres, it acts as an obstacle (see Figure 8) in the stream of induced air 29, and downstream of which a slipstream is created with return currents into the flow of induced fluid 29. These return currents locally 14. deflect the path of the fibres towards the downstream side of the shutter. Then, as Figure 8 shows, there is a regrouping of the fibres downstream of the shutter, the tendency of which is to- render the distribution of fibres in the mat more uniform.

Figures 9 and 10, in which the duets 168 are shown in plan, show an overall irregularity in the distribution of fibres, with an excessive concentration of fibres along the left edge compared with the right edge, as seen in Figure 9.

Figures il and 12 illustrate means for correcting this irregularity. By modifying the form of the outlet cross-section of the duct 168, that is, by deforming the flexible wall 168d by means of the regulating screws l68e, so that, Figure 12, the outlet cross-section of the duct 168 is larger on the right than on the left, so the quantity of gas flowing there is increased and therefore so is the quantity of fibres accompanying the gas and evacuated near the right-hand edge of the duct. This change is diagrammatically represented by the flow lines in Figure 10. By appropriately adjusting the screws 168e, it is possibd e to distribute the fibres discharged from the duct 168 uniformly.

The possibility of dividing the recycled gas into several portions which are reintroduced at different points in the apparatus provides an advantage, in that it makes it possible to modify the structure of the fibre mat, that is, the orientation of the fibres in the finished mat.

Referring again to Figures 5 and 6, part of . the recycled gas 29 is brought into contact with the resultant current 12 at the level tf the upper end of the duct 168, in a zone close to the devices 142, 148 and 154 and accompanying the current 12 as far as the conveyor 180. Another part is brought, into . Bontact with the current 12 near the lower end of the duct 168 and accompanies it as far as the conveyor 180. The flow resulting from the mixture of the current 12 with the gas 29 follows a path from the attenuating device to the receiving . conveyor and forms a considerable angle with the latter. This angle is generally between 60° and 90°, although the flow can he substantially vertical.

Another part of the recycled gas is carried hy the extension 34c (Fig.2) of the duet 34, at the . upstream end of the chamber 100 (with respect to the attenuating stations) in a zone above and in the immediate proximity of the conveyor 180 and in a direction substantially parallel to it.

A flap 101 (Fig. 5) makes it possible to . regulate the quantity of recycled gas 29 admitted from the duct 3?«e and therefore to regulate the velocity of the horizontal flow parallel to the conveyor 180 with respect to that of the descending gas flow from the attenuating stations.

When the velocity of the horizontal flow is great with respect to that of the descending flow, ' there is a marked tendency for the fibres.or segments of fibres to be deposited in layers parallel to the .conveyor 180, so imparting to the mat and to the finished product better thermal insulating properties, and greater elasticity measured at right-angles to the major faces of the mat.

When the velocity of the descending flow is 10. great with respect to that of the horizontal flow, there is a marked tendency for the fibres to be deposited on the conveyor in a· very tangled, texture, so conferring on the mat and on the finished product greater resistdnce to crushing. It is thus po-ssible i5.to give the finished produet those characteristics roost appropriate for its use.

Safety means are provided, Figure 2. These comprise a chimney 34f which may be isolated from or reconnected to the duct 34 by the flap 34d. A flap .34e can connect the apparatus directly to asmosphere, particularly for starting-up.

Claims (32)

1. CLAIMS:1. A process for producing a mat of fibres of attenuable material on a perforated collecting surface ., in which a main gaseous blast and a secondary jet of 5 smaller cross-section are used, the initial directions of which are at an angle to each other, the kinetic energy per unit of volume of the secondary jet being sufficient to cause it to penetrate the main blast so , as to give rise to a zone of interaction, and a stream 10 of the attenuable material being introduced into the said zone where the material is fiberized, wherein a current of gas is caused to flow from the said zone to and through the collecting surface so as to carry the fibres on to the collecting surface to form the

2. A process according to Claim 1, wherein a liquid binder is sprayed on the fibres before they reach the 20 collecting surface.

3. A process according to Claim 2, wherein, after formation of the mat, resinous components of the , binder entrained in the gas are partially separated out before recycling of the gas. 42779 4. 2 77 θ'

4. A process according to any of Claims 1 to 3, wherein the current of gas flowing from the zone is divided into several parts after passage through the collecting surface, which parts are recycled to 5. Fibre guiding means comprise walls inclined at an oblique angle towards the conveyor'.* 5. 5. the jet having a kinetic energy per unit of volume sufficient to cause it to penetrate the main blast and give rise to a zone of interaction, means for introducing the attenuable material into the zone where it is attenuated to fibre, suction means 5. 10. A process according to Claim 8, wherein at least insoluble resinous components of a binder and/ or fibre scraps are separated from the water which is then recycled and sprayed into the current of gas downstream of the collecting surface. 5. A process according to any preceding claim wherein gas which is recycled to the zone is delivered

5. different locations hetween the zone and the collecting surface.

6. A process according to any preceding claim, wherein part of the gas is recycled in the vicinity of the collecting surface in a direction substantially parallel to that surface.

7. A process according to any preceding claim, wherein a cooling liquid, for example Water, is

8. A process according to any preceding claim, wherein the gas is scrubbed by spraying water down25. stream of the collecting surface.

9. A process according to Claim 7, wherein at least insoluble resinous components of a binder and/or fibre scraps are separated from the cooling liquid or water which is then recycled and sprayed on to the fibres. 10. 10. located downstream of the conveyor for causing gas ( to flow through the conveyor to form a fibre mat thereon, and means for recycling to the receiving chamber at least part of the gas which flows through the conveyor. 10.

10. to the zone with a flow direction substantially parallel to that of the main gaseous blast.

11. A process according to Claim 4, wherein the ratio of flow velocity of the gas current parts which are recycled above and in the vicinity of the collecting surface is varied to control orientation and

12. A process according to any preceding claim, wherein the current of gas is channelled over a portion of its path to the. collecting surface, the

13. An apparatus for producing a mat of fibres of attenuable material, comprising a fibre receiving chamber, a perforated fibre collecting conveyor which forms at least a major part of a wall of the chamber, means for creating a main gaseous blast directed into the chamber, means for creating at least one secondary gaseous jet of a smaller cross-section than the blast and directed transversely to the latter,

14. *. An apparatus according to Claim 13, wherein the receiving chamber is substantially closed, the means for creating the gaseous blast heing located in an upper part of the chamber. 15. An apparatus according to Claim 13 or Claim 14, having means for spraying liquid binder onto the fibres upstream of the conveyor.. 15.

15. distribution of the fibres in the mat. 15 mat, and wherein at least part of the gas which flows through the surface is recycled to the said zone.

16. , having means for spraying water onto the fibres in the receiving chamber. 17. , having means for scrubbing the gas with water downstream of the conveyor and means for separating water and entrained substances from the gas, which means is connected to the suction means, and the suction ., means delivering scrubbed gas to the recycling means.

17. An apparatus according to any of Claims 13 to

18. „18. An apparatus according to any of Claims 13 to

19. An apparatus according to any of Claims 15 to 18, having means for separating at least the insoluble resinous components of the binder and/or fibre scraps :/, from the water, and means for recycling at least part of the water to the spraying means in the receiving chamber. 20 · 20. An apparatus according to Claim 18, having means , for separating at least the insoluble resinous components of the hinder and/or fibre scraps from the water, and means for recycling at least part of the water to the scrubbing means. -. 20. 20. cross-section of the current in the channelled portion being modified to control the flow of gas and entrained fibres, so as to adjust the distribution of fibres on the collecting surface.

20. sprayed on the fibres upstream of the collecting surface.

21. An apparatus according to Claims 19 or 20, having means for cooling the separated water before recycling it to the spraying or scrubbing means respectively.

22. An apparatus according to any of Claims 13 to 21, wherein the recycling means comprises a duct receiving gas from the suction means, the duct being connected to the receiving chamber.

23. An apparatus according to any of Claims 13 to 22, wherein the recycling means comprises means for dividing the gas into several parts and recycling the said parts to different zones of the receiving chamber.

24. An apparatus according to any of Claims 13 to 23, having a fibre guiding channel for directing attenuated fibres frpm the said zone to the collecting conveyor. 25. 25. An apparatus according to Claim 22, wherein the recycling duct is so positioned that at least part of the recycled gas is delivered to the receiving chamber in the same general direction as the main blast.

25. 16. An apparatus according to Claim 15, having means for separating resinous components of the hinder from the gas before recycling the gas to the receiving chambei 43770 25.

26. An apparatus according to Claim 24, wherein the recycling duct is divided into at least two branch ducts connected to the receiving chamber and recycling one part of the gas to the upstream end of the channel and another part to the vicinity of the conveyor.

27. An apparatus according to Claim 24, wherein the recycling duet comprises at least two branch ducts connected to the receiving cjhamher and recycling one part of the gas into the upstream end of the channel and another part to an intermediate position between the said zone and the conveyor.

28. An apparatus according to Claim 24, wherein the

29. An apparatus according to Claim 24 or 28, wherein the channel has at least an adjustable wall portion to vary its cross-section so as to regulate the gas l0 flow and fibre distribution.

30. An apparatus according to Claim 23, having adjustable means for varying the proportion of gas between the divided parts thereof.

31. A process for producing a mat of glass fibres X5 substantially as herein described with reference to the drawings.

32. An apparatus for producing a mat of glass fibres constructed and arranged substantially as herein described and shown in the drawings.