Method of making fibers with a burner/air ring assembly for rotary fiberizers

#The present invention relates to a rotary fiberization process and apparatus and, in particular, to a rotary fiberization process and apparatus which utilizes a rotary fiberizer equipped with a burner/air ring assembly wherein pressurized air is used to cool an annular air cooled burner and then supplied to an air ring where it is discharged into the fiberization zone of the process at a high velocity.

#The use of high velocity pressurized or compressed air to augment rotary glass fiberization processes is common in the glass fiber industry. The rotary fiberizer of these processes employ rotary fiberizing rotors and air rings. Molten glass is introduced into the rotating fiberizing rotors and fiberized by passing outward through orifices in the peripheral sidewalls of the fiberizing rotors. In the air rings, high pressure air is distributed by means of an annular manifold to narrow slots or small diameter orifices and discharged through those narrow slots or small diameter orifices into the fiberization zones of the processes adjacent the outer surfaces of the fiberizing rotor sidewalls. The constrictions caused by these narrow slots or small diameter orifices are such as to impart high velocities to the air, approaching or slightly exceeding sonic velocities, as the air exits the manifolds through the slots or orifices and enters the fiberization zones of the processes. The momentum of the high velocity air in the fiberization zones is transferred to the glass fiber primaries as the glass fiber primaries are spun from the rotating fiberizing rotors used in these processes. This momentum accelerates the glass fiber primaries to higher attenuation velocities and attenuates the glass fibers to finer diameter fibers.

#However, the effects of air rings on these processes are not all positive. The high velocity air jets from the air rings aspirate or draw considerable amounts of ambient air into the fiberization zones of these processes and there are several drawbacks to this phenomenon. First, an undetermined portion of the momentum of the air jets is consumed during the process of accelerating the ambient air as it is pulled into the fiberization zones by the air jets. However, a second, and more important effect, is the cooling effect that occurs on the outer surfaces of the rotor sidewalls from the flow of cool air over or adjacent the outer surfaces of the sidewalls.

#FIG. 1 is a schematic vertical cross section through one fiberizing station of a rotary fiberizing operation of the present invention.

#FIG. 2 is a schematic vertical cross section through a first burner/air ring assembly of the present invention.

#FIG. 3 is a schematic vertical cross section through a second burner/air ring assembly of the present invention.

#FIG. 1 shows a rotary fiberizer 20 which employs the burner/air ring assembly 22 of the present invention. The rotary fiberizer 20 includes a rotating fiberizing rotor 24, a molten fiberizable material entry port 26, preferably one or more natural gas burners 28, and the burner/air ring assembly 22. A stream 30 of a molten fiberizable material, such as but not limited to glass, is introduced into the rotating fiberizing rotor 24 through the entry port 26. As the stream 30 of molten fiberizable material strikes the upper surface of the bottom wall 32 of the fiberizing rotor 24, the centrifugal forces generated by the rotation of the fiberizing rotor 24 causes the molten fiberizable material to flow outwardly across the upper surface of the bottom wall 32 of the fiberizing rotor and up the annular peripheral sidewall 34 of the fiberizing rotor. The annular peripheral sidewall 34 of the fiberizing rotor is provided with a plurality, typically several thousand to tens of thousands, of very small diameter fiberizing orifices or holes 36 which are typically between 0.018 inches and 0.024 inches in diameter. The centrifugal forces generated by the rotation of the fiberizing rotor 24 causes the molten fiberizable material to pass outwardly through the fiberizing orifices or holes 36 to form primary fibers. Upon exiting the fiberizing orifices 36, these primary fibers are introduced directly into a heated fiberization zone that surrounds the outer surface of the peripheral sidewall 34 of the fiberizing rotor 24 where the primary fibers are further attenuated by high velocity air jets or streams into fibers 38. The fibers 38 then pass down through a collection chamber where a binder is typically applied to the fibers. Normally, the fibers 38 are then collected on a moving air permeable conveyor 40 (air is drawn down through the conveyor) or other collection surface to form a mat or blanket 42 of randomly oriented fibers.

#The burner(s) 28 used in the preferred embodiment of the invention are operated at an air/gas throughput high enough to cause a slight positive pressure within and above the fiberizing rotor 24 to prevent or greatly reduce the amount of relatively cool ambient air drawn into the rotary fiberizer through the entry port 26. In addition, to preventing the ingress of cool ambient air through the entry port 26, the heat from the bumer(s) 28 helps to maintain the molten fiberizable material within the fiberizing rotor at the desired temperature and viscosity for fiberization through the fiberizing orifices or holes 36 in the sidewall 34 of the fiberizing rotor 24.

#As shown in FIG. 1, the burner/air ring assembly 22 is mounted concentrically with respect to the fiberizing rotor 24. The burner/air ring assembly 22 includes an air cooled burner 44 and an air ring or manifold 46. While FIG. 1 illustrates the burner/air ring assembly 22 of the present invention and the concentric mounting of the burner/air ring assembly relative to the fiberizing rotor 24, FIGS. 2 and 3 better illustrate the details of two preferred embodiments of the burner/air ring assembly 22.