Title - FIBERING DEVICE FOR MANUFACTURING MINERAL FIBERS COMPRISING A FIBERING ROTATING PLATE AND PROCEDURE FOR MODIFYING THE TEMPERATURE OF SAID FIBERING ROTATING PLATE

Abstract

This document relates to a fiber forming device (1) for manufacturing mineral fibers, comprising a perforated fiber forming plate (10) to enable the manufacture of fibers by centrifugation. The fiber forming device comprises at least one annular burner (122) that produces an annular gas stream for stretching the fibers and an evacuation system for evacuating combustion gases generated by the burner. The fiber forming device is further characterized by a means for varying the temperature (100) of the plate, said temperature variation means being an air circulation means (110) arranged between the annular burner and the evacuation system to control the flow (F) of the combustion gases.

Description

-03'00' DEVICE FOR MODIFYING THE TEMPERATURE OF A FIBER PLATE The present invention relates to the field of fiber optic devices. PREVIOUS TECHNIQUE Insulating glass fibers are commonly produced by internal centrifugation. This involves introducing molten glass into a centrifuge, also known as a fiber-forming plate, which rotates at high speed and has numerous perforations around its periphery. Under centrifugal force, the glass is projected through these perforations in the form of filaments. Sometimes, the centrifugal force is supplemented by a high-temperature, high-velocity gas stream emitted tangentially to the perforated wall of the centrifuge. These techniques place the centrifuge under considerable stress due to mechanical (high rotational speed), thermal (glass temperatures around 1000 °C), and chemical (glass corrosion) factors.However, the quality of the fibers produced depends heavily on the proper functioning of the centrifuge, that is, on its state of wear and compliance with the speed and temperature settings. There is virtually no reason to modify the speed due to alterations during manufacturing, especially since it can be completely controlled independently of all other parameters if, for example, the shaft is driven by a properly guided asynchronous motor. The specified rotational speed can therefore be considered strictly met. In contrast, the temperature of the centrifuge is sensitive to a large number of factors such as, for example, the action of the internal burners that heat the inside of the centrifuge and of complementary heating means, for example, by magnetic induction, which are aimed more especially at the lower part of the centrifuge, the temperature of the glass, the flow rate of the glass, the temperature of any gaseous drawing current emitted in the immediate vicinity of the centrifuge or in any way of the more or less hot environment that reigns around the centrifuge, the more or less intense cooling due to the rotation at a higher or lower speed and the centrifuge itself which, in particular, can become deformed after a certain period of use and, therefore, suffer differently from the heating action of the burners. Furthermore, fiber quality depends on the gas flow used to draw the fibers. In fact, the gas flow rate and temperature determine the degree of fiber draw. This degree of draw, in turn, determines the fiber quality. Currently, burner regulation is achieved by adjusting the fuel / oxidizer flow parameters, which alters the gas flow and / or temperature. This modification of the gas flow and / or temperature, therefore, alters the fiber quality. There is therefore a need for a fiber-coating device in which the plate temperature can be adjusted without altering the gas stream. SUMMARY OF THE INVENTION The present invention is therefore proposed to solve these problems by providing a device that allows precise regulation of the temperature of the fiber plate. To that effect, the invention relates to a fiberizing device for manufacturing mineral fibers, comprising a perforated fiberizing plate to allow the manufacture of fibers by internal centrifugation. Said fiberizing device comprises at least one annular burner that produces an annular gas stream for stretching the fibers and an evacuation system for evacuating combustion gases generated by said burner, characterized in that said fiberizing device further comprises a means for varying the temperature of said plate, which includes an air circulation device arranged to control the evacuation flow of the combustion gases. This fiber wrapping device advantageously allows the temperature of an area of ​​the fiber wrapping plate to be modified for the purpose of regulation. According to one example, the fiber plate comprises an annular wall perforated with multiple holes and extended laterally by means of an upper and a lower part and IF-2019-79511811-APN-ANP#INPI Page 1 of 8 The air circulation device is arranged to modify the temperature locally at a point on said plate. According to one example, the air circulation device is arranged to modify the temperature locally, at the junction of the upper part and the annular wall. According to one example, the air circulation device includes a main duct with a first end connected to a first secondary duct used as an air outlet and a second end connected to a second secondary duct into which the air enters. This air circulation device further comprises flow-varying means arranged to create an additional flow in the main duct that either adds to or opposes the incoming airflow. According to one example, the means of varying the flow comprise a turbine suitable for being controlled and set in rotation, clockwise or counterclockwise, to provide a flow in two different directions. According to one example, the flow variation means comprise two turbines, each turbine arranged to provide flow in a single direction. These turbines are positioned so that their flows are opposite. According to one example, the flow variation means comprise two air injection nozzles connected to an air compressor circuit equipped with valves. These air injection nozzles are arranged in the center of the main duct, which has a variable diameter that allows for the creation of a negative pressure. According to one example, both air injection nozzles are located, each at one end of the main duct, which has, at each end, a larger diameter to allow the vacuum to be generated. According to one example, the flow variation means comprise two annular air injection nozzles connected to an air compressor circuit equipped with valves. These annular air injection nozzles are provided with an annular outlet that generates an annular or partially annular jet, and these annular air injection nozzles are arranged so that the annular air jet diffuses along the inner wall of the duct, allowing a negative pressure to be generated. According to one example, the second secondary duct comprises a parallel inner and outer wall arranged in a U-shaped profile with two parallel flanges connected by a perpendicular flange. The two parallel flanges are open to allow the entry of combustion gases, and an opening is made in the extension of the perpendicular flange for connecting this second secondary duct to the main duct. According to one example, the fiber device further comprises a second means of varying the temperature of said plate, arranged in front of the lower part of said plate. The presence of this second means of temperature variation of said plate allows, being associated with the first means of temperature variation, to act in a complementary way and fine-tune the modification of the plate temperature in different places and obtain a temperature profile in which several points are regulated. According to one example, the upper part is a veil that connects the plate to the motor shaft and the lower part is an inner lip folded in the direction of the motor shaft. According to one example, the upper part is an inner lip folded in the direction of the motor shaft and the lower part is a veil that forms the bottom of the plate. The invention also relates to a method for modifying the temperature of a fiber wrapping plate of a fiber wrapping device according to the invention, characterized by comprising the following steps: - measure the temperature at a point on said plate using a measuring module; - compare the temperature measured by said measuring module with a setpoint value; - modify the evacuation flow of combustion gases by generating an additional flow in the main duct that adds to or opposes said evacuation flow by means of said air circulation device. According to one example, this air circulation device is arranged to modify the temperature at the junction of the upper part and the annular wall. According to one example, the flow modification is done manually. According to one example, the flow modification is done automatically. IF-2019-79511811-APN-ANP#INPI Page 2 of 8 According to one example, the stage of modifying the exhaust flow of combustion gases comprises a sequence of injecting an additional flow that is added to said exhaust flow and / or a sequence of injecting an additional flow that opposes said exhaust flow. The present invention also relates to a computer program that has instructions for the execution of all or part of the steps of a procedure according to the invention, when said program is executed by computer. The present invention also relates to a computer-readable recording medium on which a computer program is recorded that has instructions for the execution of all or part of the steps of a procedure according to the invention. DESCRIPTION OF THE FIGURES Other features and advantages will become clear from the description below, which is indicative and not exhaustive, with reference to the attached drawings, in which: - Fig. 1 is a schematic representation of a fiber system according to the invention; - Fig. 1a is a schematic representation of a centrifuge variant of the fiber system; - Figures 2 to 4 are representations of the air circulation means according to the invention; - Fig. 5 is a schematic representation of a first mode of execution of flow variation means used in air circulation means; - Figs. 6a and 6b are schematic representations of a second mode of execution of flow variation means used in air circulation means; - Figs. 7a and 7b are schematic representations of a third mode of execution of flow variation means used in air circulation means; - Fig. 8 is a schematic representation of a fiber system that uses first means of temperature variation and second means of temperature variation. DETAILED DESCRIPTION OF THE INVENTION Figure 1 shows a cross-sectional view of a fiber system 1. This fiber system comprises a centrifuge, here referred to as the fiber plate 10, connected to a high-speed rotating drive shaft 12, which has a large number of holes. Under the action of centrifugal force, the glass is projected through these holes in the form of filaments. The fiber plate 10 is an internal centrifugation device for micrometer-diameter mineral fibers. A fiber plate 10 comprises an annular wall 10a perforated with many holes, extended laterally by an upper and a lower portion. In a first configuration, as shown in Figure 1, the upper portion is a veil 10b connecting the plate to the drive shaft, and the lower portion is an internal lip 10c folded in the direction of the drive shaft 12. In a second configuration, the upper portion of said plate with a bottom, shown in Figure 1a (which replaces the centrifuge beyond the dashed line), is an internal lip 10c' folded in the direction of the drive shaft, and the lower portion is a veil 10b' forming the bottom of the plate 10'. In a non-exhaustive embodiment of the device according to Figure 1, the centrifuge is fixed to a shaft 12. The shaft 12 and the centrifuge 10 are driven by a rapidly rotating motor (not shown). The shaft 12 is hollow, and the molten glass passes from the unshown feeding means in the shaft to a distribution container 13, into which the molten glass is poured. The container is also rotated, so that the molten glass is projected onto its perforated peripheral wall and, from there, in the form of voluminous strands onto the peripheral wall of the centrifuge, forming a permanent reservoir of molten glass on this wall, which feeds the perforated holes in it. This wall is inclined at approximately 1 to 10° from the vertical. IF-2019-79511811-APN-ANP#INPI Page 3 of 8 In a non-exhaustive embodiment of the device according to figure 1a, the molten glass is fed from the side of the motor shaft onto the bottom of the fiber plate formed by the veil 10b'. This fiber plate is heated by a heating module 20. The heating module 20 comprises an annular burner 22 that allows for the attenuation of the fibers. This internal combustion annular burner 22 includes a combustion chamber fed with fuel and oxidizer. The chamber includes a casing (provided with a first closed end and a second open outlet end through which the combustion gases exit). This casing has at least two opposing walls connecting both ends. The annular burner 22 includes, in the chamber and at the first closed end, at least one combustion device fed with oxidizer and fuel. The glass filaments projected out of the holes in the plate under the effect of centrifugal force are then subjected to the action of an annular gaseous current from the annular burner 22 at high temperature and speed along the wall of the centrifuge, which thins and stretches them into fibers. The aforementioned fiber optic device also includes a bell 11 for recovering and evacuating combustion gases. According to the invention, the fiber-drawing device 1 further comprises a means for varying the temperature of the plate 100. This temperature-raising means 100 is arranged to modify the temperature at a point on the plate. This point is preferably the point on the plate called the high point of the strip or the rounding point. In fact, this point is located in the area of ​​the junction between the upper part and the perforated annular wall 10a through which the molten glass passes. The plate temperature-raising means advantageously operates in a space between said plate 10 and the burner 22 without interfering with the drawing gas stream. The temperature-raising means 100 is thus capable of modifying the temperature at the high point of the strip of the fiber-drawing plate 10 and, consequently, the temperature profile along the strip, independently of the drawing means. The temperature variation means 100 is here an air circulation means 110 used to control the flow rate F of the combustion gases evacuated from the annular burner 22. It has been found that the flow rate of these gases significantly influences the plate's rounding temperature and its thermal equilibrium. Consequently, the air circulation means 110 according to the present invention allows for decreasing or increasing the evacuation of combustion gases to the hood 11, thereby modifying the temperature of the rounding (upper part of the band) of a fiber plate. This air circulation means 110 is, for example, arranged to open between the fiber plate-burner assembly and the combustion gas evacuation system, which comprises, for example, a hood 11 provided with an evacuation duct 11a. In one embodiment, the air circulation means 110 is presented as shown in section in Figure 2. The air circulation means 110 comprises a main duct 111 with two ends. A first end 111a is called the exhaust end and is connected to a first secondary duct 112, also called the chimney duct. This first secondary duct 112 is used to evacuate a portion of the combustion gases from the burner to the flue gas evacuation system. A second end 111b is called the collector end and is connected to a second secondary duct 113, also called the collector duct. This second secondary duct 113 is used to collect the combustion gases from the annular burner. For this purpose, this second secondary duct 113 has a shape adapted to collect the combustion gases around the fiber plate and, therefore, may include an annular collector. In a non-exhaustive example, shown in Figures 3 and 4, the second secondary duct 113 has an annular shape, that is, it comprises two concentric tubular walls, an inner wall 113b and an outer wall 113a, connected by a flange 13c to form a U-shaped channel, i.e., with two parallel flanges 113a and 113b connected to each other by a perpendicular flange 113c. Both parallel flanges 113a and 113b, opposite the flange, form an opening to allow the entry of combustion gases, as shown in Figure 3, which is a cross-sectional view along axis AA' of the fiber assembly shown in Figure 4. For the connection of this second secondary duct 113 to the main duct 111, an opening can be made in the outer tubular wall 113a in the extension of the flange. IF-2019-79511811-APN-ANP#INPI Page 4 of 8. Perpendicular, this opening allows a connecting duct 113d to extend for connection to the main duct 111. This duct 113d may or may not have a constant cross-section. In the case of a non-constant cross-section (not shown), the opening in the second secondary duct 113 will have a larger cross-section than that of the main duct 111. This comprehensive example has the advantage of being able to draw the combustion gases around the entire shaft 12 that supports the centrifuge 10. Of course, the second secondary duct 113 can have all possible shapes that allow a similar result to be obtained, especially a truncated conical shape formed by the internal wall 113b and the external wall 113a. To allow modification of the exhaust gas flow, the air circulation system 110 further comprises flow variation means 120, controlled by a control unit (not shown). These combustion gas flow variation means 120 are used to provide an additional flow f in the ducts, either adding to or opposing the exhaust flow F. If the combustion gas flow variation means 120 adds an air flow f to the exhaust flow F, it creates a suction effect that increases the exhaust gas flow rate. If the combustion gas flow variation means 120 creates an air flow f directed in the opposite direction to the exhaust flow F, it creates a backpressure flow. This backpressure flow is then generated in the opposite direction to the exhaust flow F.Thus, this backpressure flow reduces the evacuation rate of the combustion gases. In a first embodiment, shown in Figure 5, the flow variation means comprise at least one turbine 121. This turbine is arranged in the main duct 111 for easier integration. In the case of a single turbine 121, it will be designed to be bidirectional, meaning it can rotate clockwise or counterclockwise. Consequently, depending on the direction of rotation of turbine 121, it will be possible to improve exhaust by more efficiently drawing in combustion gases or to slow down exhaust by generating a backpressure flow. In the case of more than one turbine, not shown, two turbines 121 will be provided. Each turbine will have a specific direction of rotation that allows for intake or exhaust. These turbines may have a fixed or adjustable rotation speed to modify the flow. In a second embodiment, shown in Figures 6a and 6b, the flow variation means comprise at least two air injection nozzles 122. These air injection nozzles 122 are connected to an air compressor circuit 123 by means of valves 124. These air injection nozzles 122 are arranged to inject an additional air flow f with a power and / or speed higher than the normal exhaust gas flow. These air injection nozzles 122 are arranged in the main duct 111. The main duct 111 may or may not have a uniform diameter. The air injection nozzles 122 are then arranged at ends 111a and 111b of the main duct. These air injection nozzles 122 are arranged to have opposite injection directions; the air injection nozzle 122 at one end of the main duct injects air in a direction opposite to the direction of the air injected by the air injection nozzle 122 at the other end. This arrangement of the air injection nozzles 122 at these ends 111a and 111b is made so that these nozzles 122 are oriented towards the main duct part 111 and their operation is detailed below. For the air injection nozzle 122, oriented towards end 111a (i.e., towards the exhaust), the operation consists of the air injection causing an acceleration of the combustion gases in the adjacent area. This acceleration creates a low-pressure area that draws the combustion gases outwards and accelerates them. For the air injection nozzle 122, oriented towards end 111b (i.e., towards the manifold), the operation consists of injecting air in the opposite direction to the exhaust flow F of the combustion gases. This slows down, or reduces, the exhaust flow F of the combustion gases. These air injection nozzles 122 can be located in the axial center of the main duct 111 or be eccentric. IF-2019-79511811-APN-ANP#INPI Page 5 of 8 Temperature regulation involves manipulating two factors: temperature and flow rate. Flow rate is used to create the suction effect. Therefore, a change in flow rate alters the effect of this additional flow, f. For example, when suctioning combustion gases, increasing the flow rate of the additional flow, f, will draw in the combustion gases more intensely, thus increasing the temperature at the burner's edge. Conversely, when using suction for blowing, increasing the flow rate will decrease the temperature. In the case of regulation by modifying the temperature of the injected air, this only has an effect when it is in blowing mode. In fact, this blowing mode is used to lower the temperature of the fiber plate. Thus, with a constant flow rate, a decrease in the temperature of the injected air causes a decrease in the temperature of the fiber plate. To modify the temperature of the injected air, a conventional cooling system with water circulation can be used. In a third embodiment, shown in Figures 7a and 7b, the flow variation means 120 comprise at least two air amplifiers 125. Each air amplifier consists of an annular air injection nozzle 125a arranged in the duct. This annular air injection nozzle 125a has an annular outlet and injects an annular air jet j into the duct. The air jet may be fragmented or not. This annular air jet j is located on the inner wall of the duct and diffuses along this inner wall. This diffusion along the inner wall is made possible by the Coanda effect, whereby a fluid jet is attracted to a convex surface over which it flows, in this case, the inner wall of the duct.The annular air jet creates a difference between the annular flow and the flow in the central part of the duct, thus generating a low-pressure area. This low-pressure area creates a suction effect. The 125a annular nozzles are arranged in the duct in opposite directions, meaning that the two nozzles release airflow in opposite directions. Thus, depending on which annular air injection nozzle is activated, the resulting vacuum creates a suction effect that either increases the evacuation of combustion gases by drawing them in, or decreases their evacuation by inducing a suction effect that works against the flow of exhaust gases. For the different execution methods, the regulation can be carried out manually or automatically. To achieve the most consistent regulation possible, it is advantageous to ensure that the different valves of the air circulation device are operated in such a way that they are not actuated simultaneously. In fact, a regulation that simultaneously modified the opening of the valves for air injection (i.e., the injection of an additional flow f opposing the exhaust flow F) and for air extraction (i.e., the injection of an additional flow f adding to the exhaust flow F) would be unstable, resulting in fluctuating temperatures and negatively impacting fiber quality. Conversely, a sequential control system allows for less temperature fluctuation. Specifically, this type of control means that the valve being used is closed before the valve in the other circuit opens. Therefore, the control system comprises several steps. In an example where the air circulation device is in suction mode, meaning the temperature is high, the temperature is lowered by closing the suction valve. If closing this valve sufficiently lowers the temperature, the valve in the inflation circuit does not open. However, if the temperature does not drop sufficiently after closing the suction valve, the inflation valve is gradually opened.Thus, the stage of modifying the exhaust flow of the combustion gases F comprises an injection sequence of an additional flow f that is added to said exhaust flow and / or an injection sequence of an additional flow that opposes said exhaust flow. In a variant shown in the cross-sectional view of Figure 8, another means of temperature variation is provided. This second means of temperature variation for plate 220 comprises an induction coil 221 connected to a frequency generator 222, which serves as the first means of temperature variation. This frequency generator 222 generates a signal SI sent to the induction coil 221. This signal is what allows IF-2019-79511811-APN-ANP#INPI Page 6 of 8. Modulating the induction power of the induction coil 222 allows for varying the heating temperature. As a reminder, when the SI signal, which is a frequency-modulated electrical current, flows through the induction coil 221, it generates a magnetic field that, in turn, induces electrical currents in the nearby metal. The eddy current and hysteresis losses produced in this metal dissipate thermal energy (heat) through the Joule effect. This induction coil 221 is located at the bottom of the fiber stranding plate, and more specifically, beneath the stranding plate. This induction coil is positioned opposite the fiber strand created by the plate, in order to locally heat this lower area of ​​the plate. In this way, it is possible to have a plate profile that is precisely regulated, since the first means of variation used by the air circulation device regulates the high point, also called the rounding of the plate, while the second means of temperature variation regulates the low point of the plate. This profile regulation uses plate temperature measurements. To obtain this reading, the first step involves using a temperature sensor, such as a pyrometer connected to a reciprocating mirror. The mirror is rotated at a certain frequency to scan the fiber plate 10 and obtain a temperature curve as a function of the mirror's angular position. Alternatively, the pyrometer can be mounted pivotally and therefore not connected to a mirror. This curve is cleverly processed by the computing unit to extract at least one specific point. Then, a method for determining specific points is used. The method for determining specific points according to the invention comprises a first sub-step consisting of collecting temperature measurements of the fiber plate using a temperature measuring module 40 to provide a computing unit 30 with a curve representing the temperature as a function of the angular position of the temperature measuring device. These measurements can be retrieved immediately or from a memory unit in which they are stored. A second sub-stage of the determination method involves processing the data using the calculation unit 30 to calculate and obtain the second derivative of the temperature curve as a function of the mirror's angular position 43. This second derivative is used to find specific / characteristic points. In fact, the second derivative allows us to obtain the variation of the slope. In a third sub-stage of the determination method, the second derivative of the temperature curve as a function of the angular position of mirror 43 is analyzed, using the calculation unit 30, to find the specific / characteristic points. These specific / characteristic points are the points where the second derivative is equal to zero. Next, it is possible to define what the characteristic point corresponds to. It will be understood that the representative points of the lower part of the plate band and the plate rounding are on both sides of said hot spot, at the ends of the curve. In the case of the present invention, two characteristic / particular points are sought. These points correspond to the lower part of the plate band and the rounding of the plate. In addition, a fourth optional sub-step of the determination method can be performed. This fourth optional sub-step consists of finding the hot spot of the fiber plate. To do this, the calculation unit 30 finds the absolute maximum of the curve corresponding to this hot spot. This hot spot is the specific / characteristic central point located between the points corresponding to the temperature of the lower part of the plate band and the plate's rounding. This use of the second derivative allows, advantageously, independence from fluctuations in the plate's dimensions. In fact, the plate's dimensions can vary with wear and / or vibrations. However, despite this variation in the plate's dimensions, its overall shape remains identical. Therefore, the specific / characteristic points remain constant. This allows for the precise identification of these specific points. Consequently, subsequent adjustments are always made at the exact and truly representative points on the plate. In a third stage, the temperature values ​​of particular points are used for the regulation of the fiber plate 10. IF-2019-79511811-APN-ANP#INPI Page 7 of 8 Of course, the present invention is not limited to the illustrated example, but may be subject to the various variations and modifications that may arise for people with experience in the trade. IF-2019-79511811-APN-ANP#INPI Page 8 of 8 Argentine Republic - National Executive Branch 2019 - Year of Exports Additional Signature Sheet Graphic Report Number: IF-2019-79511811 -APN-ANP#INPI CITY OF BUENOS AIRES Monday, September 2, 2019 Reference: 20190100650 The document was imported by the GEDO system with a total of 8 page(s). Digitally signed by GESTION DOCUMENTAL ELECTRONICA - GDE DN: cn=ELECTRONIC DOCUMENTARY MANAGEMENT - GDE, c=AR, o=GOVERNMENT SECRETARY OF MODERNIZATION, ou=ADMINISTRATIVE MODERNIZATION SECRETARY, serialNumber=CUIT 30715117564 Date: 2019.09.02 20:45:38 -03'00' Marcelo Esteban Rubino Administrative Assistant National Patent Administration National Institute of Industrial Property Digitally signed by GESTION DOCUMENTAL ELECTRONICA GDE DN: cn=GEST10N ELECTRONIC DOCUMENTARY - GDE, c=AR, o=GOVERNMENT SECRETARY OF MODERNIZATION, ou=ADMINISTRATIVE MODERNIZATION SECRETARY, serialNumber=CUIT 30715117564 Date: 2019.09.02 20:45:38 -03'00'

Claims

1. A fibering device (1) for manufacturing mineral fibers comprising a perforated rotating fibering plate (10, 10') to allow the manufacture of fibers by internal centrifugation, said fibering device comprising at least one annular burner (22) that produces an annular gas flow for stretching the fibers and an evacuation system (11) for evacuating combustion gases generated by said burner, characterized in that said fibering device further comprises a means for varying the temperature (100) of said rotating plate, including an air circulation device (110) arranged to control the evacuation flow (F) of the combustion gases. 17 Claims follow