Glass furnace bottom wall construction

Claim 1

A BOTTOM WALL CONSTRUCTION FOR A GLASS MELTING FURNACE COMPRISING, IN COMBINATION: AN UNINTERRUPTED MOLTEN-GLASS CONTACTING LAYER OF ABRASION RESISTANT ZIRCON BRICKS; A PLURALITY OF SUPERIMPOSED UNINTERRUPTED LAYERS OF FIREBRICKS OF FIRST QUALITY UNDERLYING AND SUPPORTING SAID LAYER OF ZIRCON BRICKS, SAID FIREBRICKS OF FIRST QUALITY HAVING A PYROMETRIC CONE EQUIVALENT OF AT LEAST 33 AND HAVING THE ABILITY TO WITHSTAND CONTACT WITH MOLTEN GLASS FOR PROLONGED PERIODS WITHOUT LOSS OF USEFUL PROPERTIES; A PLURALITY OF SUPERIMPOSED LAYERS OF FIREBRICKS OF A SECOND QUALITY UNDERLYING AND SUPPORTING SAID FIREBRICKS OF A FIRST QUALITY, SAID FIREBRICKS OF A SECOND QUALITY HAVING A PYROMETRIC CONE EQUIVALENT OF AT LEAST 31.5 AND LESS THAN THAT OF SAID FIREBRICKS OF FIRST QUALITY, HAVING NO SUBSTANTIAL ABILITY TO WITHSTAND CONTACT WITH MOLTEN GLASS FOR PROLONGED PERIODS, AND HAVING A COEFFICIENT OF THERMAL CONDUCTIVITY WHICH IS LESS THAN THE COEFFICIENT OF THERMAL CONDUCTIVITY OF THE FIREBRICKS OF FIRST QUALITY; A LAYER OF INSULATING FIREBRICKS UNDERLYING AND SUPPORTING SAID LAYERS OF FIREBRICKS OF SECOND QUALITY, SAID INSULATING FIREBRICKS HAVING A REHEAT CHANGE OF NOT MORE THAN 2% AT 2250* F., A BULK DENSITY OF NOT MORE THAN 48 POUNDS PER CUBIC FOOT, AND A COEFFICIENT OF THERMAL CONDUCTIVITY AT 2000* F. OF THE ORDER OF 2 B.T.U. PER SQUARE FOOT PER INCH OF THICKNESS PER HOUR; AND METALLIC SUPPORTING STRUCTURE UNDERLYING AND SUPPORTING SAID LAYER OF INSULATING FIREBRICKS, A LAYER OF AN ASBESTOS-BEARING SHEET MATERIAL UNDERLYING SAID LAYER OF INSULATING FIREBRICKS AND SUPPORTED DIRECTLY ON SAID METALLIC SUPPORTING STRUCTURE.