FI62815C - FOERFARANDE OCH ANORDNING FOER FRAMSTAELLNING AV FIBER FRAON ETT TERMOPLASTISKT MINERALAEMNE - Google Patents

Description

I55F7I M (11'l NOTICE 62815 FLET * LJ UTLÄGGININQSSKRIFT · ^ ^ ^ i) tc ».ik.3 / in * .a.3 C 03 B 37/06 FINLAND — FINLAND (Μ) T818U3 (22) 08.06.78 ' 7 (23) AfaipUvt — GlMghatsdtf 08.06.J8 (41) Tullut JulktMkal - Bllvk offamHg 2k, 02 .79 nttMHMMw mHMM.nMtM.m- 30 U 82 P * t * nt- och registentyraltan 'AmM »uttagd eeh utUkrNkm ± x.ut (32) (33) (31) rrr * "* r · μοΗ (« μ ~ 8 «| Μ griortM 23.08.77

France-France (FR) 7725695 (71) Saint-Gobain Industries, 62, Bd Victor-Hugo, F-92209 Neuilly sur Geine,

France-France (FR) (72) Marcel Levecque, Saint-Gratien, Jean A. Battigelli, Rantigny,

Dominique Plantard, Rantigny, France-France (FR) (7 ^ 0 Berggren Oy Ab (5 ^) Method and apparatus for making fibers from a thermoplastic mineral material - Förfarande och anordning för framställning av fibrer frän ett thermoplastiskt minerämne

The invention relates to a method and an apparatus for producing fibers from a stretchable material and relates in particular to the stretching of thermoplastic materials, in particular mixtures of mineral materials such as glass and the like, which have been brought into a molten state by heating. However, since the device according to the present invention is of particular interest in the case of stretching glass and the like, the following description applies, for example, to the case of glass.

Some methods of using eddy currents to make fibers by stretching molten glass are known in the art.

In particular, French Patent 2,223,318 describes the formation of pairs of counter-rotating vortices in an interaction zone obtained by introducing a gas jet, called a secondary or carrier jet, into a larger main gas stream and penetrating it, causing it to penetrate. in it to be stretched.

Various types of equipment used for stretching material in the interaction zone have previously been described in the above-mentioned patent publication and in Finnish patent No. 61676 (Pat. No. 773788). In all cases, a gas flow or jet is caused to penetrate into the main stream, the kinetic energy per unit volume of which is greater than that of the main stream and whose jet cross-sectional dimension in the transverse direction of the main stream is smaller than that of the main stream. The strand of stretchable material is introduced into the jet-mainstream interaction zone either immediately by gravity or by first introducing the strand into a gas jet with it to be transported to the interaction zone.

The following analysis takes into account that the stretching of thermoplastic materials such as glass must necessarily take place at a high temperature. Thus, the glass is melted by heating it to a temperature above about 1250 ° C, for example, and in order to achieve good efficiencies, the temperature of the stretching gases in contact with the fiber and the fiber formed must also be high enough to heat the glass to a high temperature suitable for stretching.

In French Patent 2,223,318, the temperatures of both the secondary gas jet and the main stream are both relatively high, for example of the order of 800 ° C for the jet and 1580 ° C for the main stream.

Although the possibility of using low shower temperatures, for example close to room temperature, has been explained in the past, relatively high temperatures, such as those mentioned above, are also proposed for the mainstream.

However, since, on the one hand, the main gas stream contains large volumes of gas and, on the other hand, only a part of it is used to stretch the thermoplastic material in the interaction zone, heating the entire main stream gas to relatively high temperatures causes considerable energy losses.

This loss of energy is avoided by the technique according to the present invention, which, in contrast to the prior art, allows both the use of a low-temperature jet and the use of a main current with a relatively low temperature. The invention 3 6281 5 thus relates to a method for producing fibers from a thermoplastic mineral material, which comprises generating a main gas stream and at least one secondary gas jet having a cross section perpendicular to the main gas stream less than the main gas stream and having a kinetic energy per unit volume greater than the main gas the jet is directed transversely to and enters the main gas stream to form an interaction zone containing eddy currents, the method of which comprises feeding a strand of stretchable material into said zone, and the method of the invention being characterized by feeding a fuel component and combustion component in such a proportion and so as to obtain a combustible mixture in the interaction zone, whereby this mixture ignites in the interaction zone. As a result, the temperature of the gases leaving the main stream generator can be significantly lowered, saving energy accordingly.

The invention also relates to an apparatus for making spawns from a thermoplastic mineral material, the apparatus comprising: a main current generator, a transmitting means of at least one secondary gas jet having an outlet having a dimension transverse to the main stream smaller than the main stream outlet so directed, that it bounces and penetrates the main current, forming an interaction zone, and a feed source from which a filament of molten material is fed to said interaction zone, and the device according to the invention is characterized in that it comprises an independent means for supplying fuel to the interaction zone.

This technique of the present invention, referred to as "energy localization", results in high energy savings and provides additional benefits. For example, it makes it possible to cool the fibers rapidly after stretching, which improves the strength properties of the fibers in the case of a large number of thermoplastic materials. This also makes it possible to obtain very long fibers, a result which is particularly desirable for certain applications.

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Other advantages of the invention will become apparent from the following description of various embodiments of the invention as set forth in the accompanying drawing.

Fig. 1 is a schematic elevational view of the main parts of a defibering and fiber receiving apparatus used according to the invention, in which each defibering center comprises one pair of jets and some parts of which are shown in section.

Fig. 2 is a schematic perspective view, on a larger scale, showing the operation of the defibering device of Fig. 1.

Figure 3 is a vertical sectional view, on a larger scale, of the members forming the fiberization center in the plane of the outlets of the jets.

Figure 4 is a vertical sectional view of the members of the defibering center in another embodiment of the device according to the invention, which is also described in the above-mentioned Finnish Patent No. 61676 (Pat. No. 773788).

Fig. 5 is a perspective schematic view illustrating the operation of the device of Fig. 4.

Figure 6 is a plan view of a plurality of adjacent jets and mainstream portions corresponding to Figures 4 and 5, with the glass feed and emerging fibers omitted.

Fig. 7 is a view similar to Fig. 4, except that it comprises a further member.

Fig. 8 is an elevational view, partly in vertical section, showing the application of the features of the present invention to a defibering device as shown in Fig. 11 of French Patent 2,223,318.

Figures 9a and 9b are schematic sectional views of a defibering center, with Figure 9a illustrating the defibering conditions and process in the flow zone without "energy localization", while Figure 9b shows the same fiberization center, except that the energy localization method of the invention is used.

Fig. 10 is a diagram showing the advantage provided by the present invention when certain types of thermoplastic minerals are used for defibering.

The following detailed description first discusses the device shown in the drawing and then analyzes aspects related to the localization of energy in the operation of the device.

Let us first consider Figure 1, at which point 8 schematically shows a main current generator such as a burner provided with a tube 9 which transmits a main current 10 in an approximately horizontal direction. This may, however, be directed in other directions.

A supply pipe 13, which is connected to the junction box of the jets 11 via a connecting pipe 12, supplies a pressurized gas, for example compressed air, to this. It can also be seen from Figures 2 and 3 that the jet distribution box 11 comprises pairs of holes 14, 15 for transmitting jets, and adjacent pairs of outlet holes are indicated by references 14a, 15a; 14b, 15b; 14c, 15c; 14d, 15d; 14e, 15e. Showers leaving these outlet pairs are marked with the corresponding letters. Figure 2 is a perspective view of three pairs of jets, while Figures 1 and 3 show only one pair of jets, a. Each fiber pair is answered by one defibering center.

In each defibering center, the jets of one pair of jets, e.g. jets a, a, collide with each other in their common plane and form a combined flow, denoted in Fig. 1 by the letter A j where the strand of stretchable material is subjected to the first stage of stretching. The conjoined flow, i.e. the conjoined carrier jet, advances downward and penetrates into the main stream 10, forming with this an interaction zone which is used for the second stage of stretching.

In these figures, the source of the glass feed is shown schematically at 16. It comprises a traction plate 17 with a series of glass feed stoppers 18 spaced apart, each nip having a feed opening 18a, and an upstream dosing opening 19 on the upstream side. in the form of G, from which the glass fibers S flow downwards, already. ' 6281 5 I created each defibering center comprising one blank and a thread. The fibers formed from the fiberization centers distributed transversely to the width of the main stream 10 are then deposited on a perforated conveyor, i.e. a belt 20, into a fiber layer B. The distribution of fibers to this conveyor takes place inside a chamber delimited by, for example, a wall 21 and suction chambers 22. is connected by wires 23 to one or more suction fans 24. The drying performed by the device described above has been analyzed in more detail in connection with Figures 2 and 3.

As already mentioned above, the process specific to each transport center is preferably combined with the effect of the jets of the neighboring center. Figure 2 shows the stretching process complete for the fiberization center corresponding to jets b, b, and only partially for the centers corresponding to jets a, a and c, c. Figure 3 shows on a larger scale what happens in the defibering center to which the jets a, a belong. In order to analyze the process, i.e. operation, it should be immediately recalled that each gas jet induces the movement of ambient air from its outlet. As a result, each jet a has a central portion j, i.e. a core, surrounded by a gas jacket containing induced air and denoted by the letter i. This jacket expands rapidly as the jet flow progresses, while the jet core remains a relatively small, conical central portion. The gases forming the core have the same velocity as the jet as it leaves its outlet hole, while the velocity of the gases in the jacket decreases as the flow progresses. The arrows shown in Figures 2 and 3 indicate the air induction caused by the flow of the jets, but also by the main flow.

When using a pair of jets with the same kinetic energy per unit volume of the jets, preferably of approximately the same dimension, and the center lines of the two jets are in the same plane and converge so that they preferably collide with each other at an acute angle, the combined flow propagates to the sides downstream of the area where the two jets collide, i. propagate in directions transverse to the plane of the center lines of the jets.

The jet pairs, i.e. the planes containing their centerlines, are so close to each other that in each defibering center the lateral propagation of the combined flow from one jet copper is limited, i.e. disturbed, by their collision with the flow of neighboring jet pairs during their propagation. This intersection of two merged neighboring flows generates two pairs of tortuous vortices for each flow, with the peaks of the vortices of the same pair being spaced apart on different sides of the plane of the center lines of the jets. The upper and lower vortex pairs are schematically drawn in Figures 2 and 3. The vortices of the upper pair are denoted by tu, tu, and those oyat consisted of currents rotating toward each other at the top of the vortices and in opposite directions at the bottom of them. Instead, the vortices of the lower pair, denoted by t1, tl, rotate in the opposite direction to the vortices of the upper pair.

Between these two pairs of vortices, in the area of jet collision, a laminar flow zone L associated with these vortices is formed, at which the induction of induced air is very strong, and it is in this laminar flow zone, on the side of the upper vortices, that the glass fiber 5 is fed. This thread is formed from a glass blank or cone G, the position of which is displaced with respect to the jet transmitting device. Since the glass cone G is pullable, i.e. in the fluid state, upon leaving the feed nipple, the strand S of stretchable glass moves relative to the original position of the cone in the direction of the laminar flow zone L due to strong absorption of induced air, and this phenomenon ensures the strand of stretchable material enters the laminar. As a result, even if there is a small defect in the extension of the glass feed nipple 18 relative to the jet pair, the effect of the induced air automatically compensates for this defect and directs the glass fiber to the appropriate salary.

Thus, it is clear that by forming at least one pair of vortices in each defibering center flanking the laminar flow zone and feeding the material in a stretchable state to an area close to this zone, the material fiber is automatically transported to this zone by automatically induced air currents. possible stretching errors, which leads to a st-bHing of the supply of stretchable material to the system. This stability is achieved even when the glass feed nipples are at a considerable distance from the jet delivery device, a distance that is desirable to facilitate proper temperature control and maintenance in both the feed nipples and the jet delivery devices.

On the downstream side of the laminar zone L, the vortices tu, tu but also tl, tl, tend to coincide, and as the flow progresses downstream they tend to lose their identity, as shown in Figure 2 in the section showing the two pairs of vortices in the showers c, c. The combined flow of each pair of jets then proceeds downward to penetrate into the main stream 10, as shown for the flow from the pair of jets b, b. The combined jet then forms with and within the main stream the zone of interaction which has been completely analyzed in the aforementioned French patent publication 2,223,318 and which comprises an additional pair of vortices T.

It should be noted that each plane containing the center lines of the jets of the same pair preferably intersects the main current in a straight line which is practically parallel to this direction of travel.

Each glass fiber S is thus subjected to primary stretching in the flow of converged jets, between the laminar flow zone, i.e. the glass feed point and the point where the jet penetrates into the main stream, after which the partially stretched filament is subjected to further stretching by said flow and main current interaction. It can be seen from the figure that these two stretching steps are performed without breaking the glass strands, so that each strand forms a single fiber.

In order to carry out the process described above in each defibering center, namely the formation of vortex pairs, each of which borders the laminar flow, a pair of jets is preferably used, the jets of which preferably have the same kinetic energy per unit volume. The cross-sectional areas of these two jets should also preferably be equal, although it is possible to allow a small difference between these areas, especially if the kinetic energies of the two jets per unit volume are practically the same. In addition, the cross-sections of two jets of the same defibering driver are preferably of the same shape.

Furthermore, it is not necessary that the cross-sectional dimensions of the jet be the same in the direction of and perpendicular to the plane containing the centerlines of the jets, and moreover, these dimensions need not be equal to the corresponding dimensions of another jet of the same pair. However, it is desirable and advantageous for these dimensions to be the same or very close to each other within a single jet, but also for two jets of a single fiberization center. In addition, it is desirable that the dimensions of the neighboring jet copper be substantially the same in order to uniformly form vortex pairs flanking the zones of the laxinar flow as each flow impinges on the adjacent flow as it propagates laterally. This similarity of jets from adjacent defibering centers makes it possible to achieve uniform defibering conditions in the different interaction zones generated by the jet penetration into the main stream.

For infiltration to occur, the combined flow must have a greater kinetic energy per unit volume than the main flow when it reaches this.

It should also be noted that jets grouped in pairs must have certain special characteristics in order to form the flow zone of the laminar into which the glass fiber can be fed without breaking. In fact, it is important that their centerlines are in substantially the same plane and meet each other in this plane, preferably at a sharp angle.

In the system described above in connection with Figures 1, 2 and 3, the features related to energy localization can be used in several ways. First, according to the invention, it is possible that the gas streams when the jet penetrates in the interaction zone formed inside the main stream contain flammable and combustion-maintaining ingredients in such a proportion that the mixture is flammable. Preferably, the fuel and combustion maintainer are in an approximately stoichiometric ratio in the immediate vicinity of the material to be stretched. The manner in which these components are introduced into the interaction zone will be explained in detail below after explaining the other embodiments shown in the drawing of the device.

Thus, let us consider the device according to Figures 4, 5 and 6, which is also described in Finnish Patent No. 61676 (Pat. No. 773788). Here, a series of secondary or carrier gas jets with a deflector are developed. In this case, the direction of the jets changes and they are directed towards the main stream into which they penetrate, and the glass strands are fed into the jet stream, which then carries them with them to the corresponding interaction zones formed in the main stream. Let us first consider Figure 4, which schematically shows the various main parts of the defibering center. On the left is a part of a burner, i.e. a generator 25, which includes a tube 26 from which the main current 27 leaves. The jet distribution box 28 has a series of outlet openings 29 from which the jets, indicated by the letters a, b, c and d in Fig. 5, leave. A pressure medium can be fed to the jet distribution box 28 up to a connecting pipe 31 connected to the supply pipe 30. A deflector plate or flap 40 is attached to this junction box 28, which covers the jet set and the edge 41 of which is in such a position that the jets collide with the deflector.

The drive plate 32 associated with the front piece or other suitable glass feed source 33 is provided with feed nipples 34, and one glass strand is directed toward each jet stream to be described, to be then directed downstream to the interaction zone with the main stream 27. As the description progresses in more detail, the defibering takes place in the jet but also in the main stream, and then this dispenses the fibers to the right, as shown in Fig. 4, so that they form a layer which lands on a perforated conveyor belt.

Tube 26, from which the main current originates, has a large outlet. Preferably, the dimension of the traction plate 32 in a direction perpendicular to the plane of Figure 4 is also large, so that glass can be fed from it to all the nipples 34.

The jets leaving the outlets 29 are subjected to a change of direction, i.e. control, by a deflector which works together with the jets to develop counter-rotating pairs of vortices used for at least primary stretching but also to transport partially stretched strands into the jet mains interaction zone. To develop vortex pairs rotating in opposite directions of the jets, the deflector plate 40 is associated with a group of jet outlets. As shown in particular in Figure 5, the deflector plate is preferably in the form of a bent plate, part of which covers the jet box to which it is attached, and the other part having a free edge 41 in the path of the jets from the outlets 29 and preferably along a line intersected by the jet outlets .

This location of the deflector plate 40 and its edge 41 causes each jet to collide with the inner surface of the plate 40, resulting in the spreading of the jets. Thus, Figure 5 shows the flow of the four jets leaving the outlets a, b, c and d, and it is observed that each of them spreads to the sides as it approaches the edge 41 of the slab.

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According to the invention, the outlets 29 of the jets are close enough to each other and the deflector is located so that when the jets are spread towards the sides, they collide with their neighboring jets at the edge 41 of the slab. Preferably, as shown in Fig. 5, this collision of the neighboring jets takes place as close as possible to the free edge 41 of the deflector plate 40. As a result, all three rotating pairs of vortices shown in Fig. 5 leaving the outlets a, b and c form .

In order to analyze the formation of vortices in each jet, vortices 42b and 43b associated with the jet leaving the outlet b are specifically considered. It is noted that the peaks of these vortices are located substantially at the edge of the deflector plate 40 on opposite sides of the jet, close to the area where the jet, when spread, impinges on its neighboring jets from the outlets a and c, which are also spreading. The vortices 42b and 43b rotate in opposite directions, and then expand as they advance until they meet some distance downstream of the edge 41 of the deflector plate. These vortices 42b and 43b also have a downstream component.

Due to the distance between the vertices of the vortices 42b and 43b, i.e., the formation points, and taking into account their gradual expansion, an approximately triangular zone 44b is formed between these vortices and the edge of the deflector plate. This triangular zone has a relatively low pressure and a large amount of induced air flows into it, but its flow remains almost laminar. It is in this zone that the filament of molten glass or other stretchable material is fed, and due to the laminar nature of the flow in this triangular zone, the glass filament does not break but is directed to the area between said two vortices.

The directions of rotation of the currents in the jet vortices 42b and 43b are opposite; the vortex 42b rotates clockwise in the representation of Figure 5 and the vortex 43b counterclockwise. Thus, the currents in the two vortices converge at their tops and then flow downward toward the center region of the laminar zone 44b.

For the pair of jets 45a and 46a associated with the jet leaving the outlet a, the directions of rotation described above are indicated by arrows. It should be noted that the cross-section of the jet stream leaving the opening a is shown as 12,62815 at the downstream end of the laminar flow zone 44a, i. near the point where the two vortices, after expansion, begin to coincide, a phenomenon that continues as the jet flow travels downstream. It is also clear that the jet flow leaving the outlet a includes not only a pair of vortices 45a, 46a, but also a second pair of vortices 47a, 48a having opposite directions of rotation, as shown in Figure 5, but in this case the vortex 48a rotates clockwise and the vortex 47a counterclockwise . Such two pairs of vortices, of course, develop in and are associated with each shower.

With respect to Fig. 5, it should also be noted that as the flow proceeds from the plane where the vortices associated with the outlet a are shown, these four vortices tend to coalesce and form a less distinct flow, as seen from the jet flow 49c from the outlet c. The intensity of the vortex movements decreases and the flow as a whole, including the laminar flow in the central zone of the jet, mixes in the area shown at 49c, and the jet then continues its journey downwards towards the main stream 27.

In Fig. 5, the representation of the different parts of the jet is made schematic for the sake of clarity. For example, in the zone slightly downstream of the vortex origin, the vortex pairs generated in each jet are shown slightly spaced apart from the vortex pair generated in each neighboring jet, whereas in reality these different vortices are virtually in contact with each other.

Due to the shape of the flow, feeding a strand of stretchable material in the laminar zone and vortex pair of the jet, especially in the upper pair of each group, denoted by the letter S for the fiberization center to which the jet outlet b belongs, causes the strand to entrain the mid-zone laminar. This transports the filament to the high velocity zone between the two vortices, and as a result, the filament is stretched, as shown in Fig. 5. This stretching takes place in a zone substantially corresponding to the plane P. The effect of the vortex pairs of the jet causes the stretched fiber to whip substantially in the zone of the plane P, so that the stretching does not result in the fibers being formed being ejected into adjacent jets.

The jet then flows up to the upper limit of the main stream 27, carrying 13 6281 5 stretched fibers, and its kinetic energy per unit volume must still be large enough for it to penetrate into the main stream.

Then begins the second stage of defibering, which follows the principles described in the aforementioned French Patent 2,223,318.

In the area where the secondary jets penetrate into the main stream, the flow and velocity of each jet are, of course, still sufficiently concentrated in the vicinity of the centerline for each jet to be able to develop a zone of interaction with the main stream on a jet-by-jet basis. Thus, in Figure 5, one pair of counter-rotating vortices TT develops in the interaction zone, which generates currents that cause further stretching of the fiber being formed. The combined flow of jet and main stream then conveys this fiber to an appropriate receiving device, for example the conveyor 20 of Figure 1.

Figure 5 shows, without induction, arrows in the direction of the jet flow, and shows that air is induced in the laminar zone near the edge of the deflector plate, but also along the distance as the jet flows downstream.

The operating conditions which can be used in the method according to the invention when using the device described above will be specified as the description continues, which also defines the areas within which these conditions may vary.

As in the first embodiment of the device described above, the combustible and combustion-maintaining component can be fed into the system shown in Figs. 4, 5 and 6 in various ways, which will be explained below.

Let us first consider the device according to Fig. 7, in which the same reference numerals as in Figs. 4 are used for their common parts.

Figure 7 shows an additional means for feeding the combustible and combustion-maintaining component in the interaction zone. The combustible or combustion-maintaining material supply pipe 35 communicates with a series of spray nozzles 36 spaced apart from the main stream in such a way as to supply the medium to the area immediately adjacent to the interaction zone Z, directly upstream. In Fig. 8, the main current generated by the generator 50 leaves the tube 51 in a zone bounded at the top by a plate 52 and below by a plate 53 which curves downwards from the central plane of the main current of the distancing support. If desired, cooling pipes 53a can be mounted on this base plate. The glass feed drawing plate 55 is provided with spaced apertures 56 located across the width of the main stream transverse to its direction of travel so as to feed strands of stretchable material into this main stream. Immediately upstream of the glass feed openings, the top plate 52 has a series of shower outlets 29, each of which is connected to a corresponding glass feed opening with it in extension. A pressure medium is supplied to the openings 29 from a manifold 54 connected to lines 54a and 54b.

The plate 52 further includes a second manifold 57 connected to a series of adjacent outlets 57a located transverse to the main stream, each of which is connected to and extends with one of the glass inlet 56 and the corresponding jet outlet 29.

Fuel gas is supplied to the manifold 57 along line 59, which may communicate with main supply line 60.

The downstream plate 58, located along the main current boundary region, forms this upper boundary and has a cooling pipe 58a. Some of the members of this device are analogous to those shown in Fig. 11 of the above-mentioned patent publication 2223 3 8.

In the embodiment according to Fig. 8, fuel is supplied, for example, through supply openings 57a, while air used for secondary jets enters through openings 29, which makes it possible to cause the fuel and combustion maintainer to mix in the interaction zone with the main stream.

In addition, additional air may be supplied to the main stream upstream of the interaction zone, upstream and downstream of the supply ducts 61 and 62 located in the area where the main stream 50 generator is connected to the pipe 51. Each supply duct terminates in a slot or set of supply openings schematically 63. The purpose of supplying this additional air to the main stream is to achieve certain favorable conditions, for example a suitable main stream temperature, which conditions are related to the energy localization technique. In fact, when the combustion of the fuel takes place in the interaction zone, it is not necessary to use a main stream with a temperature as high as that required without this local combustion. As a result, significant energy savings can be achieved in mainstream development.

It is quite obvious that in order to generate a main flow with a relatively low temperature and the desired speed, it is possible, instead of using an additional air supply, to completely eliminate the use of a burner and replace it with any other system, such as a heat exchanger. .

Before considering other means of supplying fuel and combustion preservative, reference is made to Figures 9a and 9b, which are now compared with each other in order to analyze the energy localization process according to the invention and the energy to be achieved as a result, i.e. fuel savings.

Figure 9a shows the conditions under which stretching occurs between the jet and the main stream in the developed interaction zone without the energy localization technique. The outlet pipe 64 generates a main current with a width, i.e. the dimension in the direction perpendicular to the plane of the figure is preferably large, so that several pairs of glass supply (65) and jet outlet (66) members can be connected to the main stream, so that a large number of fibers can be produced. The glass fiber and the secondary jet are denoted S and J, respectively, and the interaction between the jet and the main stream is denoted by the zone Z. When using such a system and a conventional glass mixture, the jet temperature can be either 800 ° C (as described in 2,223,318) or much lower. that is, near room temperature. In both cases, the temperature of the main stream varies between 1500 ° C and 1750 ° C depending on the temperature of the jet, so that the desired temperature for stretching the glass fiber is obtained in the interaction zone. Figure 9a shows the temperature of 1700 ° C at the mouth of the main flow outlet pipe, the main stream whose core C extends to the zone of interaction with its jet, although the zone where the stretching actually takes place is in fact between the main stream temperature and the jet temperature. On the downstream side of the interaction zone, successive isothermal curves represent a gradual decrease in temperature, for example 1600 ° C, 1400 ° C and 1200 ° C.

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Fig. 9b schematically shows the same members of the device as in Fig. 9a, but under the conditions that prevailed when using the energy localization technique of the present invention. For this purpose, a pressurized mixture containing fuel gas can be fed to the jet transmitter 65, while additional air or oxygen can be fed through a pipe 64 from which the main stream leaves a much lower temperature at the time of departure than when operating under the conditions of Figure 9a. The temperature of the main stream may be, for example, on the order of 600 ° C as it leaves the tube, as indicated by the iso-terra curves, and the temperature of most of the gases then decreases, reaching, for example, about 400 °, 300 ° and 200 ° C downstream of the tube. corresponding to the iso-thermal curves of 1600 °, 1400 ° and 1200 ° C in Figure 9a.

Although it is possible to feed the fuel with the main stream, it is preferred that the fuel forms part of the secondary jet, i. that it is fed to the gases of the secondary jet as described above.

Thus, the function of the jet J is not only to form the interaction zone into which the glass fiber S is conveyed, but also to supply to this a fuel component which is thoroughly mixed with the combustion-maintaining agent, in particular the excess air supplied by the main stream to the interaction zone. Thanks to the eddy currents present in the interaction zone, it is possible to achieve the very thorough mixing that is sought.

Regarding the ratio of fuel to combustion maintainer It should be noted at the outset that it is better to use stoichiometric ratios.

However, a combustible mixture can also be obtained in ratios other than stoichiometry. Thus, when mixed with natural gas, the amount of air can vary between about 0.8 and about 1.7 times the amount of air corresponding to the stoichiometric ratio. These appropriate amounts of fuel and combustion maintainer form a combustible mixture in the interaction zone having a flash point lower than the temperatures of the molten glass alloys normally used for defibering so that the glass fiber produced to be fed to the interaction zone can ignite the combustible mixture formed therein. As a result, the desired temperature, for example 1700 ° C, can be reached in the interaction zone Z and thus allow the material thread to be stretched and converted into fiber, despite the fact that the main stream temperature on both said zone, upstream and downstream is much lower than 17 62 81 5. In addition, it should be noted that the interaction zone formed with each jet cannot comprise more than a small fraction of the total volume of the main stream. Thus, since only this part necessarily needs to reach the higher temperature required for stretching, a very high energy saving is achieved with the method according to the invention, compared to systems in which the entire volume of the main stream is heated to the stretching temperature.

It is also important to note that the technique of stretching in the interaction zone is particularly well suited for locating thermal energy due to the low pressure and low velocity region formed in the immediate vicinity of each glass fiber and surrounding it in general, without the need for any other material member.

Thus, a fuel or combustion maintainer can be injected into the interaction zone to form a combustible mixture, while the presence of hot glass allows this mixture to be ignited. The high-velocity vortex currents characteristic of the flow-zone are used in local energy technology to provide a thorough mixing of the fuel and the combustion-maintaining agent, as already described. On the other hand, since these eddy currents sometimes move in the direction of flow, sometimes upstream, there are inevitably areas in the interaction zone where the flow rate is relatively low compared to the main current rate. The existence of these low flow rate ranges is therefore one of the conditions for the ignition of the combustible mixture to take place and for stable combustion to be maintained. The importance of this feature should be emphasized by recalling that when a mixture of natural gas and air is used, the rate of flame propagation is of the order of 0.3 to a few meters per second at 20 ° C. Although this rate of flame propagation increases as the temperature rises, it always remains inherently low compared to the main current rate. However, since the interaction zone is also characterized by the presence in its certain regions of a flow at a rate lower than the rate of propagation of the flame, it is possible to ignite the fuel mixture and maintain a stable combustion. The above reasons seem to be able to explain the phenomena of ignition and combustion stability in the interaction zone, but it is probably possible to find other explanations for these phenomena.

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In addition, in the system described in connection with Fig. 9b, the flame front tends to remain adhered to the ignition source, i. the glass fiber itself, that is to say, the fiber whose substance is intended to be raised or maintained at the appropriate temperature. In fact, this flame infection is able to provide the other hand, as a result, the temperature of the glass is much higher than the ignition temperature of the mixture, and may be increased up to two-fold Ahan with respect to, and on the other side because of contact with the glass filaments with a surface of a boundary layer of the fuel mixture in the glass of heat transferred may syttymisolosuh -teisiin. It therefore follows that there is a combustible layer around the glass which triggers a local and stable combustion in the neighboring layer spas and in the interaction zone, which remains adhered to the glass fiber to be stretched.

Since much of the heat exchange with the glass fiber occurs through contact of hot gases with its surface, the technique of the present invention effectively ensures · the transfer of heat necessary to maintain the glass fiber in a stretchable state, since the zone of strong heat release is just said fiber. immediately surrounding zone.

Another advantage of the method according to the invention is that the strength of the fibers made from them with numerous glass alloys is improved when the temperature of the fiber is rapidly reduced after the stretching is completed. Thus, the preferred conditions occur here, as the isotherms of Figure 9b clearly show.

In the device shown in Figures 1, 2 and 3, the gas jet pair a, a can thus contain the fuel component necessary to achieve the desired result, and consequently not only conveys the glass to the interaction zone with the main stream, but also feeds fuel to it. to the system by the main current 10, as in Figure 9b. In this way, and by selecting the jet and main stream temperatures as mentioned above in connection with this figure, the desired energy localization and fuel savings can be achieved.

Similarly, in the embodiment of Figures 4, 5 and 6, it is possible, if desired, to supply the fuel component entirely with the gas jet, allowing air to be supplied simultaneously with the main stream, preferably reducing the temperature of the latter to 19 6281 5, as proposed above in Figure 9b. to achieve savings.

In the variants shown in Figures 7 and 8, the fuel can be fed independently of the jet, i. separately, as already explained.

As for the combustion maintainer, especially the air, it can be fed either with the shower itself or with the main stream, or with both.

Fig. 8 shows an embodiment of an apparatus used to supply air with the main stream and in which air is added to this stream before the outlet pipe 51. By this means the required total gas volume and desired temperature can be obtained by burning only a small amount of main stream gases, whereby the localized combustion process interacting in the zones surrounding the filaments to provide the local increase in temperature required for stretching, as described in connection with Figure 9b.

The energy localization process according to the invention also offers special advantages in the stretching of certain categories, such as the stretching of certain types of stones and other natural or synthetic minerals, for which the range of stretching temperature is particularly narrow. The diagram in Figure 10 shows the change in viscosity η as a function of temperature t for two different types of stretchable materials, one of which, 10a, is glass commonly used for defibering, while the other, 10b, refers to natural stone in which the temperature range leading to stretching viscosity, is very limited. It is noted from this diagram that the viscosity range between A and B, which allows stretching, corresponds to a much wider temperature range (ta-t ^) on glass than on stone (temperature range t ^ -t '^).

By feeding an appropriate amount of fuel to the mainstream interaction zone, the zone where the temperature suitable for stretching the rock or any similar material is can be expanded downstream, thus facilitating the maintenance of the desired viscosity for a longer period of time.

With respect to the stretching devices or processes shown in Figures 1-3, 4-6 and 7, in which a strand of stretchable material accompanies the stretching material. . i 20 6281 5 exposed to the jet before it enters the mainstream, it should be noted that although both the fuel and the combustion maintainer are both present in the stream at the point where the strand of stretchable material is fed into the stream, ignition does not necessarily occur at this point. It may even, depending on the different operating conditions selected, such as the temperature or speed of the jet, not occur until the jet has reached or penetrated the main stream.

In this specification, the values of the various parameters set forth below correspond to and illustrate the operating conditions that may be used in accordance with the invention, but are not intended to limit the invention in any way. Specifically, although the exemplified fuel is a natural gas, it may still consist of synthesis gas or a mixture, and certain fuels may also be used, atomized or vaporized.

When using the defibering center of Figures 1-3, the main stream 10 is generated from heated, pressurized air and has a temperature of about 600 ° C, a speed of about 300 m / sec and a pressure of about 0.18 bar. The center lines of the two secondary jets form an angle of 60 ° C. One of these showers is a mixture of one volume of natural gas and 3 parts of air, and the other shower consists of 4 parts by volume of air. The temperature of the jets is about 20 ° C, and otherwise their speed is about 330 m / sec and the pressure is about 2.5 bar. The glass fiber is fed at a temperature of about 1300 ° C.

When using the defibering center described in connection with Fig. 7, the same conditions as mentioned above can be used with respect to the main stream 27. The shower consists of air with a temperature of 20 ° C, a speed of 330 m / sec and a pressure of 2.5 bar. In this case, the natural gas is supplied via the transmission device 36 at a pressure of about 0.5 bar and a speed of 200 m / sec. The glass leaves the feed nozzle 34 at a temperature of about 1300 ° C.

Claims (15)

21 6281 5 A method of making fibers from a thermoplastic mineral material, comprising generating a main gas stream and at least one secondary gas jet having a cross section perpendicular to the main gas stream less than the main gas stream and having a kinetic energy per unit volume greater than the main gas stream and the jet is penetrates it to form an interaction zone containing eddy currents, according to which a strand of stretchable material is fed to said zone, characterized in that a fuel component and a combustion-maintaining component are fed to the gas streams in such a proportion and so that the combustible mixture interacts, the mixture ignites in the interaction zone. A method according to claim 1, characterized in that the fuel component and the combustion-maintaining component are in an approximately stoichiometric ratio in the interaction zone. Method according to claim 1 or 2, characterized in that one of said components fed to the interaction zone forms at least a part of the jet or the main stream. Method according to one of the preceding claims, characterized in that one of the components fed to the interaction zone forms at least part of the jet and the other of the components fed to this zone forms at least part of the main stream. Method according to one of the preceding claims, characterized in that the fuel fed to the interaction zone forms part of the jet and the combustion-maintaining component at least part of the main stream. A method according to claim 1 or 2, characterized in that the combustion maintenance agent introduced into the interaction zone forms part of the secondary jet or main stream and that the fuel component is introduced into said zone generating a pressurized flue gas jet directed towards the main stream and entering the interaction zone. 22 6281 5 A method according to claim 6, characterized in that the fuel jet directed towards the main stream enters it from a point located upstream of the secondary jet. A method according to claim 1 or 2, characterized in that the fuel component is introduced into the interaction zone by generating a pressurized flue gas jet directed towards and entering the main stream upstream of the secondary jet and the combustion maintainer being introduced into the main stream in the form of air. fed to it under pressure on the upstream side of said flue gas jet. Method according to any one of the preceding claims, characterized in that the temperature of the main stream in the region located upstream of the interaction zone is lower than the temperature of the strand of stretchable material fed to said zone. Method according to one of the preceding claims, characterized in that the strand of stretchable material is fed into the interaction zone at a temperature at least equal to the ignition temperature of the mixture of fuel and combustion-maintaining component. A method according to any one of the preceding claims, characterized in that a plurality of jets are used, a filament of thermoplastic material is fed to each interaction zone, each of the secondary jets and the main stream, to form a combustible mixture of fuel and combustion maintainer in each interaction zone and this mixture in each zone. An apparatus for making fibers from a thermoplastic mineral material, the apparatus comprising: a main current (27) generator (26, 50). at least one secondary gas jet transmitting member (28, 54) having outlet openings (29) having a dimension, i.e. a width transverse to the main stream, smaller than the main stream outlet port directed to intersect and penetrate the main stream 6281 5 23 interaction zone (Z), and a supply source (32, 56) from which a filament of molten material is fed to said interaction zone (Z), characterized in that it comprises an independent means (35, 57) for supplying fuel to the interaction zone (Z). Device according to Claim 12, characterized in that the fuel supply element (57) has a supply opening (57a) located at the boundary of the main stream (27). Device according to Claim 12, characterized in that the fuel supply element (35) comprises a transmission device (36), the outlet opening of which is located at a distance from the boundary of the main current (27). Device according to claim 12, characterized in that the fuel supply member (35, 57) is located so as to take the fuel into the main stream (27) upstream of the zone where the secondary jet penetrates into the main stream.