MXPA97004858A

MXPA97004858A - Method and apparatus to produce lana mine

Info

Publication number: MXPA97004858A
Application number: MXPA/A/1997/004858A
Authority: MX
Inventors: Yang Alain; Thouvenin Jeanmarie; Aube Jeanyves
Original assignee: Gruenzweig + Hartmann Ag 67059 Ludwigshafen De
Priority date: 1995-10-27
Filing date: 1997-06-27
Publication date: 1998-10-30

Abstract

The present invention relates to a method for producing mineral wool, the molten mineral material being fed to a spinning machine, whose peripheral wall comprises a multiplicity of orifices with small diameters through which the molten mineral material is centrifuged to form filaments, which are subjected to an attenuating effect complementary to a flow of gas flowing along, and which heats the peripheral wall of the spinning machine, and which is generated by a concentric annular burner configured concentrically to the spinning machine, characterized because: the burner outlet area is subdivided into a radially internal annular hot zone and a radially external annular cooling zone of substantially higher temperature

Description

METHOD AND APPARATUS FOR PRODUCING MINERAL WOOL The invention relates to a method for producing mineral wool, the molten mineral material being fed to a spinning machine as defined in the opening clause of claim 1, and to an apparatus for fiberizing mineral material by means of internal centrifugation with a machine. of spinning as defined in the opening clause of claim 2. High-quality mineral fibers can be produced by internal centrifugation, wherein the melting is fed into a spinning machine that rotates to a high speed, and having a multiplicity of small holes in its peripheral wall, through which fusion can arise as fused filaments of a correspondingly small diameter. The exiting filaments are subjected to the jet of an annular burner, and are thus attenuated to form fibers of a required fineness, which subsequently solidify and accumulate on a lower conveyor, where the mineral fiber mat is formed. This process is well known in the art as the so-called TEL process. With these fibrillating units, mineral materials of different compositions are fibrized. These mineral compositions may have high, normal, or low melting points, and therefore, different fiberization temperatures. The burner of these filarization units, on the other hand, operates with a specified optimum setting, and therefore, at a specified operating temperature that must not be changed substantially in order not to leave the optimum operating region of the burner. Therefore, the burner jet gases can have a temperature of 1550 ° C to 1600 ° C, with an optimum operation setting of the burner, which would be a suitable temperature to fiber glass of high melting point. Through minor changes to the burner setting, this temperature could be lowered to, for example, from 1300 ° C to 1350 ° C, with a burner setting still close to the optimum, to accommodate different temperature requirements of the spot glasses. lowest fusion. The overheating of the filaments of materials with a low melting point will lead to a reduction in viscosity to such an extent that the fusion attenuated by the jet gases will escape from the attenuation zone before solidification, so that, under the influence of the surface tensions, the fibers still melted will be transformed into untargeted non-fibrous particles in the resulting mineral wool mat. Accordingly, there is a need to fiber other mineral material such as low melting point glass with jet gas temperatures as low as 1200 ° C or even lower. Reducing the burner outlet temperature to this extent, by changing the burner setting, would lead to non-optimal burner operating conditions that are undesirable.Therefore, it is an object of the present invention to provide a method and a apparatus that allow the fibrization of low melting point mineral materials, which require jetting temperatures substantially lower than those produced by the burner under the optimum operating conditions.This object is obtained in a methodical aspect, because the area of The burner outlet is subdivided into a radially internal annular hot zone and a radially external annular cooling zone of substantially lower temperature.In the aspect of construction, this object is obtained by providing injection elements to cool the gas as the air in the external peripheral wall of the burner outlet, and because the direction of the injection n is essentially transverse to the flow direction of the burner gases in l 'injection region. With the invention in this way the temperature of the jet gases will not be reduced in a homogeneous manner as in the case where the intake of fuels is reduced towards the burner, or where cooling air is previously mixed with the burner gases. This has the consequence that the radially internal zone remains comparatively hot, and possibly even at the temperature of the uncooled gases of the burner. This effect is desirable, since the region of the rows of holes in the peripheral wall of the spinning machine must be maintained at comparatively high temperatures greater than the liquid, or that the temperature of devitrification or crystallization, to allow the flow of glass to through the holes. On the other hand, it is desirable to cool the attenuated fibers rather quickly, to solidify them sufficiently to avoid a return springing effect of the attenuated fibers into the veins of the material under the influence of the surface tension, and also to prevent emissions of volatile components of glass, for example sodium, by a strong effect of temperature. These poor quality fibers from the veins of the material or other forms other than fiber, also lead to a higher content of non-fibrized particles in the resulting mineral wool mat. The rather drastic cooling effect caused in the radially external cooling zone tends to avoid that undesired effect.

Moreover, the injection of the cooling gas through the external peripheral wall of the burner outlet does not result in a substantial readjustment in the burner in the case of a change in the composition of the material. For example, if glass with a high melting point is fibrillated, the cooling air intake can simply be closed, and in the case of fiberizing of lower melting points, any required amount of cooling air can be simply admitted. turning a valve. Accordingly, the optimum fit for any composition of material to be fibrillated can be obtained without appreciable effort. The fact that the direction of the injection of the cooling gases is essentially transverse to the flow direction of the burner gases eliminates any appreciable increase in the impulse and the effects of the kinetic energy of the burner gases. Accordingly, the admission of the cooling gas does not appreciably change the attenuation effect caused by the burner gases, so that the intake of cooling gas does not change the operating conditions of the apparatus in this respect. Although the cooling effect of the cooling gas tends to increase the viscosity of the mineral material, it is essentially balanced by the increase in energy content of the overall gas flow, by introducing the cooling gas. Therefore, the operating conditions of the apparatus, including the attenuation effect, remain substantially unchanged, regardless of the admission of a greater or lesser amount of cooling gas to accommodate the temperature needs of the glass composition being fibrizing. From PCT 94/04469, an additional external fan is known which supplies cooling air from a position radially outwardly of the burner outlet. In this case, the burner outlet is positioned radially inward on the upper outer rim of the spinning machine. This configuration is especially suitable for the fiberization of hard glass having a high melting point, and having a low viscosity at the melting point. The cooling air of this known embodiment intersects the flow of jet gases at the outer periphery of the spinning machine, at a point where fiber attenuation almost ends to increase the viscosity at that point. The gas flow of the fan is essentially parallel to the flow of the jet gas, and therefore, is added to the impulse and to the kinetic energy of the composite flow. However, with the present invention, the gases arising from the burner outputs themselves, are cooled in a specific non-homogeneous manner without appreciably increasing their momentum, to allow the fibrization of the mineral material with a temperature characteristic compared with which the The temperature of the uncooled jet gas would be unduly high to produce non-fibrillated particles. The sub-claims contain further improvements of the apparatus of the invention. In a preferred embodiment, the diameter of each hole in the shape of a pierced hole is between 1 and 3 millimeters, in particular about 2 millimeters. In this way, adequate flow conditions are obtained for the cooling gas to penetrate the flow of the jet gas. The distance between two consecutive uniformly distributed holes in the shape of the through holes is preferably between 2 and 15 millimeters, in particular between 5 and 12 millimeters, the higher values being preferred with the single row configurations, and the lower values being preferred with multi-row configurations, with the distance measured between the stepped holes of different rows. The distance between two rows is typically between 2 and 10 millimeters. Also, the injection elements may comprise an outlet in the form of at least one continuous circumferential groove, allowing this configuration an easier adjustment of the flow characteristics, by adjusting the width of the slot. Typically, the width of this slot is between 0.3 and 1 millimeter. Other advantages, details, and features of the invention can be seen from the following description in conjunction with the drawings, in which: Figure 1 is a schematic view of an apparatus of the invention in longitudinal section. Figure la is a detail of Figure 1 in an amplified view, but for an alternative embodiment. Figure IB is a further modification in a view as in Figure la. Figure 2 is a representation of the temperature distribution across the width of the burner outlet, just below the exit area. Figure 3 is a representation of the temperature distribution that results radially outward of the peripheral wall of the spinning machine of the centrifuge device. The fiberizing unit of the apparatus as shown in a simplified manner in Figure 1, consists mainly of a spinning machine 1, the peripheral wall 2 having a multiplicity of discharge orifices. The peripheral wall 2 is connected to a flange 3 by means of the connecting band 4, referred to as a "veil" due to its shape. As illustrated by the drawing, the peripheral wall 2, the web 4, and the tab 3 are formed as a whole in a single unitary passage. The flange 3 is mounted on a support arrow , which is hollow in the embodiment shown, and through this cavity the molten mineral material is supplied. The support arrow 5 - or even the flange 3 - further supports a concentric distribution element 6, usually referred to as a "cup" or "basket". The dispensing cup 6, with a peripheral wall having a relatively low number of holes with comparatively large diameters, serves as the bottom wall of the spinning machine, and distributes the stream of molten mineral material by separating it into a plurality of filaments that are extend on the inner circumference of the peripheral wall 2. The spinning machine 1 is surrounded by several heating devices: an annular coil of medium frequency 7 which heats particularly the bottom portion of the spinning machine 1, especially with the object to compensate for the insufficient heating by the burner and the cooling in contact with the air of the environment which is considerably cooled by the considerable amounts of air sucked by the spinning machine revolution 1, 'and *' an annular external burner cooled by water 8. The ends of the peripheral walls 9 and 10 of the external burner 8 are configured to a slight diameter from the spinning machine 1, for example, of the order of 5 millimeters, with the inner wall 10 approximately flush with the outer upper edge of the spinning machine 1. The external annular burner 8 generates a flow of high temperature gas and high velocity directed substantially in a vertical direction, and which consequently passes along the peripheral wall 2. The gas flow, on the one hand, serves to heat or maintain the temperature of the peripheral wall 2, and on the other hand part, it contributes to the attenuation of the filaments of the molten mineral spun into fibers. As shown in the drawing, the external burner 8 is preferably surrounded at a greater radial distance by a ring of the cold air fan 11, whose main objective is to limit the radial expansion of the flow of hot gas, and in this way prevent the formed fibers come into contact with the annular magnet 7. The external heaters of the spinning machine 1 are supplemented inside by an internal annular burner 12, which is placed inside the supporting arrow 5, and is used during the start phase of the fiberising unit to preheat the cup 6.

The general construction of the fiberizing unit as described above is conventional. According to the invention, the ring conduit containing the cooling chamber 14 for the outer peripheral wall 9 is subdivided by a partition wall 15 for accommodating a lower chamber 16 for the cooling air. The chamber 16 is in fluid communication with the outlet of the burner through a series of holes 17 in the outer peripheral wall 9. A tr of the holes 17, the cooling air, or any other cooling gas, or any Another cooling gas enters the burner outlet and mixes there with the burner gases. The holes 17 extend in a direction transverse to the flow direction of the burner gases at the burner outlet. Accordingly, the kinetic energy of the jet gas arising from the burner outlet does not change appreciably, so that the attenuation conditions are not appreciably influenced by the presence or by the absence of cooling air. The shape and configuration of the holes 17 can be adapted to the needs of the given case. In the example installation shown, there is a row of holes 17 with a diameter of 2 millimeters and a distance between two consecutive holes of 17 or 10 millimeters. Taking into account that the diameter of the spinning machine is 400 millimeters, there are 120 holes 17 configured around •• e the entire circumference of the ring conduit 13 in a uniform distribution in a row. If it is adequate, the holes 17 could also be configured in two or more rows, and the Figure shows an example of this mode, the mutual distance being between the 2 millimeter holes 17 of different rows of 5.5 millimeters. Also, the holes 17 could be replaced by a slot 18 as shown in Figure Ib, which would give the advantage of adjusting the width of the vertical slot as shown schematically and is symbolized by the double arrow of Figure Ib. With this alternative configuration of the holes 17 or the slot 18, different needs for practical application can easily be accommodated in a given case. In Figures 2 and 3, the temperature distribution measured with two practical modalities is shown. While Figure 2 shows the temperature distribution at a level of 1 millimeter below the exit area of a burner outlet, Figure 3 shows the temperature distribution at a level of the uppermost orifices of the peripheral wall 2 of the spinning machine 1, at a distance of 19 millimeters below the exit area of the burner outlet. The radial measurement distance given in Figures 2 and 3 of the abscissa t * measured from the exit wall 9. The temperature distribution curve A was measured in a manner as shown in Figure 1, with two rows of holes 17, while curve B is without injection of cooling gas. Curves A and B are rather self-explanatory. Figure 2 shows the influence of the cooling gas on the left side, which lowers the temperature in this cooled zone designated as C. As shown in Figure 3, the temperature near the perimeter of the spinning machine 1 rises, and it decreases sharply in the cooled zone C at a distance of several millimeters radially outside thereof, to assist in the rapid solidification of the attenuated fibers. The effects caused by the invention have been described above with an emphasis on the production of fibrils from low melting point glasses. However, these effects can obviously also be used for the fiberization of mineral material with high melting points, if the temperature of the burner is generally increased, and subsequently cooled by the supply of cooling gas through the holes 17 or the slot 18.

Claims

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A method for producing mineral wool, the molten mineral material being fed to a spinning machine (1), whose peripheral wall (2) comprises a multiplicity of holes with small diameters through which the molten mineral material is centrifuged to form filaments, which are subjected to an attenuating effect complementary to a gas flow that flows along, and which heats the peripheral wall (2) of the spinning machine (1), and which is generated by a concentric annular burner (8) configured concentrically to the spinning machine (1), characterized in that: the burner outlet area (8) is subdivided into a radially internal annular hot zone and a radially external annular cooling zone of a substantially lower temperature.

2. An apparatus for the fiberization of mineral material by means of internal centrifugation, with a spinning machine (1) whose peripheral wall (2) comprises a multiplicity of holes with a small diameter through which the molten material is centrifuged for forming filaments, which are subjected to the effect of complementary attenuation of a flow of gas flowing along, and which heats the peripheral wall (2) of the spinning machine (1), and which is generated by a concentric annular burner external (8) configured concentrically to the spinning machine (1), characterized in that: injection elements (17, 18) are provided to cool the gas-like air in the external peripheral wall (9) of the burner outlet, and because the direction of the injection is essentially transverse to the flow direction of the burner gases in the injection region.

3. The apparatus according to claim 2, characterized in that the diameter of each hole (17) in the shape of a pierced hole, is between 1 and 3 millimeters, in particular about 2 millimeters. The apparatus according to claim 2 or 3, characterized in that the distance between two consecutive uniformly distributed holes is between 2 and 15 millimeters, in particular between 5 and 12 millimeters. The apparatus according to claim 4, characterized in that a plurality of at least two rows are formed in the holes, the distance between the neighboring rows being between 2 and 10 millimeters, preferably 5 millimeters. 6. The apparatus according to claim 2 in any of claims 2 to 5, characterized in that the injection element comprises an outlet in the form of a continuous circumferential groove (18). The apparatus according to claim 6, characterized in that the width of the slot (18) is between 0.3 and 1 millimeter. The apparatus according to claim 6 or 7, characterized in that the width of the slot is adjustable.