Abstract:
An apparatus for making mineral fibers is provided. The apparatus comprises a rotary fiberizer capable of receiving molten mineral material and centrifuging the molten mineral material into mineral fibers. A fiberizer burner is connected to the rotary fiberizer. The fiberizer burner is configured to receive a first flow of combustion gas and burn the first flow of combustion gas to support the making of the mineral fibers. A gas supply assembly is configured to supply the fiberizer burner with the first flow of combustion gas. The gas supply assembly comprises a pilot assembly having a pilot burner. The pilot burner is operable to burn a pilot flame from a second flow of combustion gas. The pilot flame is operable to ignite the first flow of combustion gas flowing to the fiberizer burner. A flame sensor is operable to detect a change in the pilot flame and communicate the change in the pilot flame. A controller is configured to communicate with the flame sensor and control the first flow of combustion gas to the fiberizer burner and the second flow of combustion gas to the pilot assembly.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 60/963,057, filed Aug. 2, 2007, the disclosure of which is incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    This invention relates in general to the production of mineral fiber material, particularly of such materials as glass fiber. More particularly, this invention relates to controlling the flow of combustion gases to burners and pilot flames used in the production of mineral fibers. 
       BACKGROUND OF THE INVENTION 
       [0003]    In the manufacture of mineral fiber insulation, the mineral fibers are usually formed from molten mineral material using fiberizers. In a typical manufacturing operation, the molten mineral material is introduced into a plurality of fiberizers. The molten material is generated in a melter or furnace and is delivered to the fiberizers by way of a forehearth having a series of bushings. The fiberizers centrifuge the molten material and cause the material to be formed into fibers that are directed as a stream or veil to a collection unit. 
         [0004]    As the newly formed fibers exit the fiberizer, the fibers are maintained in a plastic, attenuable condition by heat supplied from an annular burner. High speed gases from an annular blower force the fibers downward toward a collection operation. The burner utilizes a flow of gas that is ignited by a pilot light assembly and regulated by one or more control valves. In some production facilities the control valves are manually operated and in other production facilities the control valves are automatically controlled. It would be advantageous if improvements could be made to the control valves. 
       SUMMARY OF THE INVENTION 
       [0005]    According to this invention there is provided an apparatus for making mineral fibers. The apparatus comprises a rotary fiberizer capable of receiving molten mineral material and centrifuging the molten mineral material into mineral fibers. A fiberizer burner is connected to the rotary fiberizer. The fiberizer burner is configured to receive a first flow of combustion gas and burn the first flow of combustion gas to support the making of the mineral fibers. A gas supply assembly is configured to supply the fiberizer burner with the first flow of combustion gas. The gas supply assembly comprises a pilot assembly having a pilot burner. The pilot burner is operable to burn a pilot flame from a second flow of combustion gas. The pilot flame is operable to ignite the first flow of combustion gas flowing to the fiberizer burner. A flame sensor is operable to detect a change in the pilot flame and communicate the change in the pilot flame. A controller is configured to communicate with the flame sensor and control the first flow of combustion gas to the fiberizer burner and the second flow of combustion gas to the pilot assembly. 
         [0006]    According to this invention there is also provided an apparatus for making mineral fibers. The apparatus comprises a rotary fiberizer capable of receiving molten mineral material and centrifuging the molten mineral material into mineral fibers. A fiberizer burner is connected to the rotary fiberizer. The fiberizer burner is configured to receive a first flow of combustion gas and burn the first flow of combustion gas to support the making of the mineral fibers. A gas supply assembly is configured to supply the fiberizer burner with the first flow of combustion gas. The gas supply assembly comprises a pilot assembly having a pilot burner. The pilot burner is operable to burn a pilot flame from a second flow of combustion gas. The pilot flame is operable to ignite the first flow of combustion gas flowing to the fiberizer burner. A flame sensor is operable to detect a change in the pilot flame and communicate the change in the pilot flame. A controller is configured to communicate with the flame sensor and control the first flow of combustion gas to the fiberizer burner and the second flow of combustion gas to the pilot assembly. The controller shuts off the first and second flows of combustion gas in the event of an upset condition. 
         [0007]    According to this invention there is also provided a method of making mineral fibers comprising the steps of: providing a rotary fiberizer capable of receiving molten mineral material and centrifuging the molten mineral material into mineral fibers, connecting a fiberizer burner to the rotary fiberizer, the fiberizer burner configured to receive a first flow of combustion gas and burn the first flow of combustion gas to support the making of the mineral fibers, providing a gas supply assembly configured to supply the fiberizer burner with the first flow of combustion gas, the gas supply assembly comprising, a pilot assembly having a pilot burner, the pilot burner operable to burn a pilot flame from a second flow of combustion gas, the pilot flame operable to ignite the first flow of combustion gas flowing to the fiberizer burner, a flame sensor operable to detect a change in the pilot flame and communicate the change in the pilot flame, a controller configured to communicate with the flame sensor and control the first flow of combustion gas to the fiberizer burner and the second flow of combustion gas to the pilot assembly, sensing a change in the pilot flame, communicating the change in the pilot flame to the controller, and controlling the first and second flows of combustion gas in response to the sensed change in the pilot flame. 
         [0008]    Various advantages of this invention will become apparent to those skilled in the art from the following detailed description of the invention, when read in light of the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a schematic representation in elevation of an apparatus for manufacturing glass fibers. 
           [0010]      FIG. 2  is a schematic representation in elevation of an apparatus for manufacturing glass fiber insulation material. 
           [0011]      FIG. 3  is a partial cross-sectional elevational view of the fiberizer of the apparatus illustrated in  FIGS. 1 and 2 . 
           [0012]      FIG. 4  is a side view in elevation of the gas supply assembly of the apparatus of  FIGS. 1 and 2 . 
           [0013]      FIG. 5  is a partial cross-sectional elevational view of the pilot assembly and flame sensor of the apparatus of  FIGS. 1 and 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0014]    For the purposes of simplicity and clarity, the invention will be described in terms of glass fiber manufacturing, but the inventive method and apparatus are applicable as well to the manufacture of fibrous products of other mineral materials, such as rock, slag and basalt. 
         [0015]    A glass fiberizing apparatus  10  for producing glass fibers is shown in  FIG. 1 . While  FIG. 1  illustrates a glass fiberizing apparatus  10  for producing glass mats or glass blankets, it should be appreciated that the invention can be used for producing other forms of glass fiber based material, such as for example chopped glass fibers. Examples of glass fiberizing apparatus include U.S. Pat. No. 5,474,590 to Lin, U.S. Pat. No. 4,831,746 to Kim, U.S. Pat. No. 4,537,610 to Armstrong, U.S. Pat. No. 4,280,253 to Holt, and U.S. Pat. No. 4,263,033 to Michalek, all of which are incorporated herein by reference. Referring again to  FIG. 1 , a plurality of fiberizers  12  receives molten glass material from a forehearth  14 . The plurality of fiberizers  12  generate veils  16  of glass fibers  18  and hot gases. In the embodiment shown in  FIG. 1 , the veils  16  are directed downward through a chamber or forming hood  20 , and onto a foraminous collecting conveyer  22 , which gathers the glass fibers  18  into a continuous mat or blanket  24 . The travel of the veils  16  through the forming hood  20  enables the glass fibers  18  and accompanying hot gases to cool considerably by the time they reach the conveyor  22 . Typically, the glass fibers  18  and gases reaching the conveyor  22  are at a temperature no greater than about 300 degrees Fahrenheit. Water sprayers  26  spray fine droplets of water onto the hot gases in the veil  16  to help cool the flow of hot gases. Binder sprayers  28 , positioned beneath the water sprayers  26 , are used to direct a resinous binder onto the downwardly moving glass veils  16 . 
         [0016]    While the embodiment shown in  FIG. 1  illustrates the forming of a continuous mat or blanket  24 , in another embodiment as shown in  FIG. 2 , the veils  16  can be used to manufacture loose fill insulation. In this embodiment, a plurality of fiberizers  12  form the veils  16  from the glass fibers  18  as described above. Although only one fiberizer  12  is shown, it is to be understood that any number of fiberizers  12  can be employed. As further shown in  FIG. 2 , water sprayers  26  spray fine droplets of water onto the hot gases in the veil  16  to help cool the flow of hot gases. However, in this embodiment, there are no binder materials applied to the glass fibers  18  formed by each fiberizer  12 . Instead, a lubricant material, such as a silicone compound or an oil emulsion, for example, can be applied to the glass fibers  18  by lubricant sprayers  29 . Application of a lubricant material to the glass fibers  18  prevents damage to the glass fibers  18  as they move through downstream manufacturing apparatus (not shown) and come into contact with apparatus components as well as other glass fibers  18 . The lubricant will also be useful to reduce dust in the ultimate product. Typically, the final glass wool product contains about 1 percent oil by weight, although other concentrations can be used. 
         [0017]    Once the lubricant material is applied to the glass fibers  18 , an entrance  32  to a gathering member  30  receives the glass fibers  18 . The gathering member  30  is adapted to receive both the glass fibers  12  and the accompanying flow of hot gases in the veil  16 . The downward flow of gases in the veil  16  is created by an annular blower (not shown) and an annular burner (also not shown) connected with the fiberizer  12 . The momentum of the flow of gases will cause the glass fibers  18  to continue to move through the gathering member  30  to downstream manufacturing operations (not shown). 
         [0018]    As shown in  FIG. 3 , each fiberizer  12  includes a spinner  33  having a spinner peripheral wall  34 . Examples of fiberizers  12  and spinners  33  include U.S. Pat. No. 4,246,017 to Phillips, U.S. Pat. No. 5,474,590 to Lin, U.S. Pat. No. 5,582,841 to Watton et al., U.S. Pat. No. 5,785,996 to Snyder, and U.S. Pat. No. 4,246,017 to Phillips, all of which are incorporated herein by reference. Referring again to  FIG. 3 , each spinner  33  rotates on a spindle  36 . The rotation of the spinner  33  centrifuges molten glass through orifices  38  in the spinner peripheral wall  34  to form glass fibers  18 . The glass fibers  18  are maintained in a soft, attenuable condition by the heat of a fiberizer burner  40 . Optionally, another burner or burners (not shown) may be also used to provide heat to the interior of the fiberizer  12 . A blower  42 , using induced air through passage  44 , is positioned to pull and further attenuate the glass fibers  18 . While the fiberizer burner  40  and the blower  42  shown in  FIG. 3  are configured in the illustrated positions relative to the spinner  33 , it should be appreciated that the fiberizer burner  40  and the blower  42  can be configured in other positions relative to the spinner  33 . 
         [0019]    In the embodiment shown in  FIG. 3 , the fiberizer burner  40  provides heat to the fiberizer  12  through the combustion of gases. In one embodiment, the gases can be a mixture of gasses, such as for example a mixture of fuel gas and air. Alternatively the mixture of gases can be another mixture suitable for combustion, such as for example fuel gas and oxygen. 
         [0020]    Referring now to  FIG. 4 , the first automatic shutoff valve  51   a  controls the first flow of combustion gases through a burner supply pipe  53  to the fiberizer burner  40 . The burner supply pipe  53  is configured for a pipe having an inside diameter in a range of from about 3.00 inches to about 5.00 inches. In another embodiment the pipe can have an inside diameter of less than about 3.00 inches or more than about 5.00 inches. 
         [0021]    As generally shown in  FIG. 4 , a gas supply assembly  50  controls a first flow of combustion gases in direction D 1  and a second flow of combustion gases in direction D 2 . The first flow of combustion gases is used to supply the fiberizer burner  40 . The first flow of combustion gases is controlled by a first automatic shutoff valve  51   a . A second flow of combustion gas is used to maintain a pilot flame within a pilot assembly  64 . The second flow of combustion gases is controlled by a second automatic shutoff valve  51   b . As will be described later in more detail, the first and second automatic shutoff valves,  51   a  and  51   b , are controlled by a controller  70  and are configured to shut off the first flow of combustion gas to the fiberizer burner  40  and the second flow of combustion gas to the pilot assembly  64  in the event of an upset condition. The term “upset condition” is defined to mean any condition that potentially affects the ignition of the first and second flows of combustion gases within the fiberizer burner  40  and the pilot assembly  64 . Examples of upset conditions include natural disasters, power failures, machinery malfunctions and human error. 
         [0022]    In general, the gas supply assembly  50  is configured to perform several functions including: regulating the second flow of combustion gases to the pilot assembly  64 , igniting the first flow of combustion gases flowing to the fiberizer burner, and detecting and sensing the condition of a pilot flame within the combustion tube  66 . As illustrated in  FIG. 4 , the gas supply assembly  50  is configured for a pipe having an inside diameter in a range from about 0.375 inches to about 1.5 inches. In another embodiment, the pipe can have an inside diameter of less than about 0.375 inches or more than about 1.5 inches. 
         [0023]    The gas supply assembly  50  includes an optional first valve  52 . The optional first valve  52  is configured to provide a master on/off valve for the second flow of combustion gases to the pilot assembly  64 . In normal operation, the first valve  52  is maintained in an open position. In the illustrated embodiment, the first valve  52  is a manually operated ball valve. Alternatively, the first valve  52  can be another type of valve sufficient to provide a master on/off valve for the second flow of combustion gases. In other embodiments, the gas supply assembly  50  can be operated without the first valve  52 . 
         [0024]    The optional first valve  52  is connected to a regulator valve  56  by a first connector  54 . The first connector  54  is configured to provide a gas-tight connection between the first valve  52  and the regulator valve  56 . In the illustrated embodiment, the first connector  54  is a male×male union. In another embodiment, the first valve  52  can be connected to the regulator valve  56  by another type of connector sufficient to provide a gas-tight connection. 
         [0025]    The regulator valve  56  is configured to reduce or increase the pressure of the incoming second flow of combustion gas and provide a desired outlet pressure of the second flow of combustion gas to downstream operations. Regulator valves are commercially available, such as for example, the Maxitrol Model 325-3 Lever Acting Design from Maxitrol Company in Southfield, Mich. However, other regulator valves  56  can be used. In the illustrated embodiment, the pressure of the incoming second flow of combustion gas is in a range from about 20-25 in H 2 O and the outlet pressure is in a range from about 2-4 in H 2 O. 
         [0026]    The regulator valve  56  is connected to an optional pressure gauge  60  by a pipe connector  58 . The pipe connector  58  is configured to provide a gas-tight connection between the regulator valve  56  and the pressure gauge  60 . In the illustrated embodiment, the pipe connector  58  has male threads on each end. In another embodiment, the regulator valve  56  can be connected to the pressure gauge  60  by another type of connector sufficient to provide a gas-tight connection. 
         [0027]    The outlet pressure of the second flow of combustion gas is monitored by an optional pressure gauge  60 . Pressure gauges are commercially available, such as for example, the Ashcroft Model 1490A Low Pressure Diaphragm Gauge from Ashcroft Corporation Stratford, Conn. However, other pressure gauges  60  can be used. In other embodiments, the gas supply assembly  50  can be operated without the pressure gauge  60 . 
         [0028]    In the illustrated embodiment shown in  FIG. 4 , the optional pressure gauge  60  is connected to a pilot assembly  64  by a flexible connector  62 . The flexible connector  62  is configured to provide a gas-tight flexible connection between the pressure gauge  60  and the pilot assembly  64 . In the illustrated embodiment, the flexible connector  62  is a stainless-steel, braided, gas rated flexible hose. In another embodiment, the pressure gauge can be connected to the pilot assembly  64  by another type of connector sufficient to provide a flexible gas-tight connection. In yet another embodiment, the pressure gauge  60  can be connected to the pilot assembly  64  by a rigid connector, such as for example a union or a segment of threaded pipe, sufficient to provide a gas tight connection between the pressure gauge  60  and the pilot assembly  64 . 
         [0029]    The first flow of combustion gas is ignited at the fiberizer burner  40  by the pilot assembly  64 . The pilot assembly  64  is configured to provide a small gas powered pilot flame  65  within a combustion tube  66 , as shown in  FIG. 5 . The pilot flame  65  is kept alight in order to serve as an ignition source for the first flow of combustion gas. Pilot assemblies are commercially available, such as for example, the Bloom Model No. 3001-202-04 from Bloom Engineering Company, Inc. in Pittsburgh, Pa. However, other pilot assemblies  64  and other pilot mechanisms can be used. 
         [0030]    As shown in  FIGS. 4 and 5 , the pilot assembly  64  is connected to the combustion tube  66 . A flame sensor  68  is also connected to the combustion tube  66 . The flame sensor  68  includes a flame rod  69 . The flame sensor  68  is configured such that the flame rod  69  is positioned within the flame envelope of the pilot flame  65 . The flame rod  69  is configured to detect the presence of the pilot flame  65  within the combustion tube  66 . In the illustrated embodiment the flame rod  69  detects the presence of the pilot flame  65  within the combustion tube  66  by the electric current rectification properties of the pilot flame  65 . Alternatively, the flame rod  69  can detect the presence of the pilot flame  65  within the combustion tube  66  using other methods, such as for example detecting the heat produced by the pilot flame  65  or detecting the envelope of the pilot flame  65 . Flame sensors  68  are commercially available, such as for example, the Honeywell Model No. C7007A from Honeywell Inc. in Golden Valley, Minn. However, other pilot flame sensors  68  can be used. The flame sensor  68  is further configured to provide a signal to the controller  70  verifying the presence of the pilot flame  69  within the combustion tube  66 . 
         [0031]    In operation, the second automatic shutoff valve  51   b  allows a flow of combustion gases to the pilot assembly  64 . The second flow of combustion gas is pressure regulated by the pressure regulator  56 . The pilot flame  65  within the combustion tube  66  is lit. The presence of the pilot flame  65  is detected by the flame rod  69  of the flame sensor  68 . The flame sensor  68  generates a signal indicating the presence of the pilot flame  65  within the combustion tube  66 . The signal from the flame sensor  68  is communicated to the controller  70 . The controller  70  operates the first automatic shutoff valves  51   a , allowing the first flow of combustion gas to flow through the burner supply pipe  53  to the fiberizer burner  40 . The first flow of combustion gas through the burner supply pipe  53  is ignited by the pilot flame  65  within the pilot assembly  64  and the fiberizer burner  40  provides heat to the fiberizer  12 . In the event of an upset condition, the flame rod  69  of the flame sensor  68  senses a change in the pilot flame  65 . The change in the pilot flame  65  generates a signal which is communicated from the flame sensor  68  to the controller  70 . The controller  70  communicates with the first and second automatic shutoff valves,  51   a  and  51   b , to stop the first flow of combustion gas to the fiberizer burner  40  and the second flow of combustion gas to the pilot assembly  64 . As described above, the controller  70  is configured to receive signals from the flame sensor  68  and subsequently communicate with the first and second automatic shutoff valves,  51   a  and  51   b , to step the first flow of combustion gas to the fiberizer burner  40  and the second flow of combustion gas to the pilot assembly  64 . In the illustrated embodiment, the controller  70  is a microprocessor-based device such as for example a programmable logic controller. In other embodiments, the controller  70  can be other devices, such as for example a laptop computer, sufficient to receive signals from the flame sensor  68  and subsequently communicate with the first and second automatic shutoff valves,  51   a  and  51   b , to stop the first flow of combustion gas to the fiberizer burner  40  and the second flow of combustion gas to the pilot assembly  64 . In the illustrated embodiment, the controller  70  is configured to receive communication from the flame sensor  68  as to the condition of the pilot flame  65 . In other embodiments, the controller  70  can initiate communication to the flame sensor  68  verifying the condition of the flame sensor  68 . 
         [0032]    The principle and mode of operation of this invention have been described in its preferred embodiments. However, it should be noted that this invention may be practiced otherwise than as specifically illustrated and described without departing from its scope.