Glass batch liquefaction

Abstract

The initial step of melting glass, converting particulate batch materials to a partially melted, liquefied state, is carried out on a support surface of batch. As liquefied batch is drained from the surface, additional batch is fed onto the surface to maintain the surface substantially constant. The questions raised in reexamination request No. 90/000,701, filed Dec. 31, 1984 have been considered and the results thereof are reflected in this reissue patent which constitutes the reexamination certificate required by 35 U.S.C. 307 as provided in 37 CFR 1.570(e).

We claim: 
     
       1. A method of liquefying glass batch comprising: in a vessel having a cavity surrounded by sidewalls, an upper inlet end portion, and a lower outlet end portion, maintaining a lining on the interior of the sidewalls comprised of a stable layer of glass batch;   feeding glass batch into the vessel at the inlet end portion so as to form a transient layer of glass batch on the stable layer lining;   providing heat to the cavity to render the transient batch layer to a molten fluid which flows on the stable batch layer lining toward the outlet end and out of the vessel through an outlet opening in the outlet end portion; and   replenishing the transient glass batch layer by feeding additional glass batch onto the stable batch layer at a rate sufficient to maintain the stable batch layer lining substantially constant at a sufficient thickness to thermally protect the vessel from the heat within the cavity.   
     
     
       2. The method of claim 1 wherein the vessel is a metallic vessel. 
     
     
       3. The method of claim 1 wherein the surface of the stable layer of batch is a surface of revolution. 
     
     
       4. The method of claim 1 wherein the vessel and the stable layer of batch are rotated about the cavity. 
     
     
       5. The method of claim 1 wherein the vessel is an inclined cylindrical tube and is rotated about the axis of the tube. 
     
     
       6. The method of claim 1 wherein the vessel is a cylindrical or conical drum, the axis of which is substantially vertical. 
     
     
       7. The method of claim 6 wherein the vessel is metallic. 
     
     
       8. The method of claim 1 wherein the stable layer of batch is maintained at a thickness of at least 3 centimeters. 
     
     
       9. The method of claim 1 wherein the stable layer of batch is provided with a surface sloping at an angle greater than the natural angle of repose of the batch. 
     
     
       10. The method of claim 1 wherein the heat is provided by an oxygen enriched combustion flame. 
     
     
       11. The method of claim 1 wherein the batch is essentially free of sulfur. 
     
     
       12. The method of claim 1 wherein the batch fed to the transient layer is dry. 
     
     
       13. The method of claim 1 wherein replenishment of the transient batch layer includes distribution of batch onto substantially all portions of the surface of the transient batch layer. 
     
     
       14. The method of claim 1 wherein the replenishment of the transient batch layer comprises depositing a stream of batch onto the upper portion of the batch within the vessel and permitting portions of the deposited batch to tumble onto lower portions of the batch within the vessel. 
     
     
       15. The method of claim 1 wherein replenishment of the transient batch layer comprises dispersing a stream of batch onto the transient batch layer by means of a gas stream. 
     
     
       16. The method of claim 15 wherein the gas stream comprises a combustion flame. 
     
     
       17. The method of claim 1 wherein the molten fluid flowing out of the vessel includes a substantial portion of unmelted batch material. 
     
     
       18. The method of claim 17 wherein the molten fluid flowing out of the vessel is subsequently subjected to additional thermal energy so as to complete melting of the batch material. 
     
     
       19. The method of claim 1 wherein minor periodic erosion of the stable batch layer occurs and is repaired by controlling the rate of feeding additional batch so as to maintain a substantially constant interface between the stable batch layer and the transient batch layer. 
     
     
       20. The method of claim 19 wherein material eroded from the stable batch mass is entrained in the molten fluid passing from the vessel without substantially affecting the composition thereof. 
     
     
       21. The method of claim 1 wherein the stable batch layer and the transient batch layer have substantially the same composition. 
     
     
       22. The method of claim 1 wherein the stable batch layer is provided with a surface facing the cavity that is substantially a concave surface of revolution. 
     
     
       23. The method of claim 22 wherein the concave surface has a vertical axis of symmetry. 
     
     
       24. The method of claim 23 wherein the vessel is rotated about an axis corresponding to the vertical axis of symmetry. 
     
     
       25. The method of claim 1 wherein the glass batch is a soda/lime/silica glass batch and the molten fluid is drained from the vessel before its temperature exceeds 2300° F. 
     
     
       26. The method of claim 1 wherein the melted ingredients in the molten fluid flowing from the vessel include soda ash, caustic soda or boric acid. 
     
     
       27. The method of claim 26 wherein the molten fluid includes unmelted particles that include sand grains. 
     
     
       28. The method of claim 1 wherein the heat is provided to the cavity by means of a radiant heat source. 
     
     
       29. The method of claim 6 wherein the vessel is rotated about the axis of the drum. 
     
     
       30. The method of claim 29 wherein the drum is metallic and the upper inlet end portion of the vessel includes a ceramic lid. 
     
     
       31. The method of claim 29 wherein the batch within the vessel is provided with a surface facing the cavity that is substantially a concave surface of revolution. 
     
     
       32. The method of claim 29 wherein the batch is a flat glass batch and the molten fluid is drained from the vessel at a temperature no greater than 2300° F. 
     
     
       33. The method of claim 29 wherein heat is supplied to the cavity by a radiant energy source. 
     
     
       34. The method of claim 33 wherein the radiant energy source is an oxygen enriched combustion flame. 
     
     
       35. The method of claim 33 wherein the radiant energy source is an electric arc. 
     
     
       36. The method of claim 29 wherein the batch is a batch composition essentially free from sulfur and is fed to the vessel essentially dry. .Iadd. 
     
     
       37.  A method of liquefying glass batch in a vessel having an upper inlet portion, a lower outlet portion, and surrounding sidewalls comprising: (a) insulating the vessel with a layer of glass batch defining a sloped cavity within the vessel;   (b) heating the cavity to liquefy a transient layer of the glass batch which flows on an underlying stable layer of batch to the outlet immediately upon liquefaction;   (c) replenishing the transient layer of glass batch at a rate sufficient to maintain the stable layer of batch at a sufficient thickness to protect the vessel from undue thermal deterioration. .Iaddend. .Iadd.38. The method of claim 37 wherein the vessel is a metallic vessel. .Iaddend. .Iadd.39. The method of claim 37 wherein the surface of the stable layer of batch is a surface of revolution. .Iaddend. .Iadd.40. The method of claim 37 wherein the vessel and the stable layer of batch are rotated about the cavity. .Iaddend. .Iadd.41. The method of claim 37 wherein the vessel is an inclined cylindrical tube and is rotated about the axis of the tube. .Iaddend. .Iadd.42. The method of claim 37 wherein the vessel is a cylindrical or conical drum, the axis of which is substantially vertical. .Iaddend. .Iadd.43. The method of claim 42 wherein the vessel is   
     
     
        metallic. .Iaddend. .Iadd.44.  The method of claim 37 wherein the stable layer of batch is maintained at a thickness of at least 3 centimeters. .Iaddend. .Iadd.45. The method of claim 37 wherein the stable layer of batch is provided with a surface sloping at an angle greater than the natural angle of repose of the batch. .Iaddend. .Iadd.46. The method of claim 37 wherein the heat is provided by an oxygen enriched combustion flame. .Iaddend. .Iadd.47. The method of claim 37 wherein the batch is essentially free of sulfur. .Iaddend. .Iadd.48. The method of claim 37 wherein the batch replenishing the transient layer is fed to the vessel in a dry condition. .Iaddend. .Iadd.49. The method of claim 37 wherein replenishment of the transient batch layer includes distribution of batch onto substantially all portions of the surface of the transient batch layer. .Iaddend. .Iadd.50. The method of claim 37 wherein the replenishment of the transient batch layer comprises depositing a stream of batch onto the upper portion of the batch within the vessel and permitting portions of the deposited batch to tumble onto lower portions of the batch within the vessel. .Iaddend. .Iadd.51. The method of claim 37 wherein replenishment of the transient batch layer comprises dispersing a stream of batch onto the transient batch layer by means of a gas stream. 
     
     
        .Iaddend. .Iadd.52.  The method of claim 51 wherein the gas stream comprises a combustion flame. .Iaddend. .Iadd.53. The method of claim 37 wherein the liquefied material flowing out of the vessel includes a substantial portion of unmelted batch material. .Iaddend. .Iadd.54. The method of claim 53 wherein the molten fluid flowing out of the vessel is subsequently subjected to additional thermal energy so as to complete melting of the batch material. .Iaddend. .Iadd.55. The method of claim 37 wherein minor periodic erosion of the stable batch layer occurs and is repaired by controlling the rate of feeding additional batch so as to maintain substantially constant interface between the stable batch layer and the transient batch layer. .Iaddend. .Iadd.56. The method of claim 55 wherein material eroded from the stable batch mass is entrained in the molten fluid passing from the vessel without substantially affecting the composition thereof. .Iaddend. .Iadd.57. The method of claim 37 wherein the stable batch layer and the transient batch layer have substantially the same composition. .Iaddend. .Iadd.58. The method of claim 37 wherein the cavity is provided with a surface that is substantially a concave surface of revolution. .Iaddend. .Iadd.59. The method of claim 58 wherein 
     
     
        the concave surface has a vertical axis of symmetry. .Iaddend. .Iadd.60. The method of claim 59 wherein the vessel is rotated about an axis corresponding to the vertical axis of symmetry. .Iaddend. .Iadd.61. The method of claim 37 wherein the glass batch is a soda-lime-silica glass batch and the liquefied batch flows from the vessel before its temperature exceeds 2300° F. .Iaddend. .Iadd.62. The method of claim 37 wherein the melted ingredients in the liquefied batch flowing from the vessel include soda ash, caustic soda or boric acid. .Iaddend. .Iadd.63. The method of claim 62 wherein the liquefied batch includes unmelted particles that include sand grains. .Iaddend. .Iadd.64. The method of claim 37 wherein the heat is provided to the cavity by means of a radiant heat source. .Iaddend. .Iadd.65. The method of claim 42 wherein the vessel is rotated about the axis of the drum. .Iaddend. .Iadd.66. The method of claim 65 wherein the drum is metallic and the upper inlet end portion of the vessel includes a ceramic lid. .Iaddend. .Iadd.67. The method of claim 65 wherein the cavity is provided with a surface that is substantially a concave surface of revolution. .Iaddend. .Iadd.68. The method of claim 65 wherein the batch is a flat glass batch and the molten fluid is drained from the vessel at a temperature no greater than 2300° F. .Iaddend. 
     
     
        .Iadd.69.  The method of claim 65 wherein heat is supplied to the cavity by a radiant energy source. .Iaddend. .Iadd.70. The method of claim 69 wherein the radiant energy source is an oxygen enriched combustion flame. .Iaddend. .Iadd.71. The method of claim 69 wherein the radiant energy source is an electric arc. .Iaddend. .Iadd.72. The method of claim 65 wherein the batch is a batch composition essentially free from sulfur and 
     
     
        is fed to the vessel essentially dry. .Iaddend. .Iadd.73.  A method of liquefying glass batch comprising: in a vessel having a substantially vertically symmetrical cavity surrounded by sidewalls, an upper inlet end portion, and a lower outlet end portion, maintaining a lining on the interior of the sidewalls comprised of a stable layer of glass batch;   feeding glass batch into the vessel at the inlet end portion so as to form a transient layer of glass batch on the stable layer lining;   providing heat to the cavity to render the transient batch layer to a molten fluid which flows on the stable batch layer lining toward the outlet end and out of the vessel through an outlet opening in the outlet end portion; and   replenishing the transient glass batch layer by feeding additional glass batch onto the stable batch layer at a rate sufficient to maintain the stable batch layer lining substantially constant at a sufficient thickness to thermally protect the vessel from the heat within the cavity. .Iaddend.   
     
     
        .Iadd.74.  A method of liquefying glass batch comprising: in a vessel having a cavity surrounded by sidewalls, an upper inlet end portion, and a lower outlet end portion, maintaining a lining on the interior of the sidewalls comprised of a stable layer of glass batch;   feeding glass batch into the vessel at the inlet end portion so as to form a transient layer of glass batch on the stable layer lining;   providing heat to the cavity to render the transient batch layer to a molten fluid that includes incompletely melted portions and which flows on the stable batch layer lining toward the outlet end and out of the vessel through an outlet opening in the outlet end portion while still including incompletely melted portions; and   replenishing the transient glass batch layer by feeding additional glass batch onto the stable batch layer at a rate sufficient to maintain the stable batch layer lining substantially constant at a sufficient thickness to thermally protect the vessel from the heat within the cavity. .Iaddend.