TEMPERATURE MONITORING INSTRUMENT FOR GLASS MANUFACTURING

THE MEASUREMENT OF TEMPERATURES OF MOLTEN GLASS IS IMPORTANTTO CONTROL THE MANUFACTURING PROCESS. THERE IS A NEED FOR BETTER NON-CONTACT MEASUREMENTS OF SURFACE TEMPERATURES AND TEMPERATURES WITHIN THE BULK GLASS. THE REQUIRED SURFACE TEMPERATURE MEASUREMENTS CAN BE MADE USING RADIANCE DATA AT THE CHRISTIANSEN FREQUENCY. THE CHRISTIANSEN EFFECT IS A PHENOMENON EXHIBITED BY ALL GLASSES IN WHICH THE SCATTERING AND REFLECTION OF ELECTROMAGNETIC RADIATION BY PARTICLES OR SURFACES DISAPPEARS. THUS, IF ONE MEASURES THE RADIANCE OF A MATERIAL AT THE CHRISTIANSEN FREQUENCY, THE TEMPERATURE OFTHE SURFACE CAN BE OBTAINED. THIS IS SO BECAUSE THE ABSORPTION IS HIGH ENOUGH SO THAT A VERY THIN SURFACE LAYER IS OPAQUE. THE SURFACE MUST THEN HAVE AN EMISSIVITY OF UNITY, SINCE IT DOES NOT REFLECT OR TRANSMIT. THE TEMPERATURE IS THUS THE SAME AS A BLACK-BODY HAVING THE SAMERADIANCE AT THE CHRISTIANSEN FREQUENCY. U.S. PATENT NO. 4,985,858 WAS RECENTLY GRANTED TO ADVANCED FUEL RESEARCH, INC FOR THIS METHOD. AS ONE MOVES TO SHORTER WAVELENGTHS, THE ABSORPTION IS REDUCED AND THE PENETRATION DEPTH OF ELECTROMAGNETIC RADIATION INTO THE MATERIAL INCREASES. THE TEMPERATURE DETERMINED BY THE MEASURED RADIANCE WILL BE AN AVERAGE ALONG A LINE-OF-SIGHT OVER THIS PENETRATION DEPTH. BY GOING TO FREQUENCIES CORRESPONDING TO DECREASING VALUES OF ABSORPTION, AVERAGE TEMPERATURES ARE DETERMINED FOR INCREASING DEPTHS INTO THE MATERIAL AND HENCE A TEMPERATURE PROFILE CAN BE OBTAINED. THE OBJECTIVES OF PHASES I AND II ARE TO DEVELOP A METHOD AND PROTOTYPE INSTRUMENT TO MAKE MEASUREMENTS OF THE SURFACE AND INTERIOR TEMPERATURES OF GLASS DURING MANUFACTURING. PHASE I WILL DEMONSTRATE THE FEASIBILITY OF THE APPROACH, FIRST IN THE LABORATORY USING HEATED GLASS BLOCKS AND THEN IN A FIELD TEST AT A GLASS PLANT. A FOURIER TRANSFORM INFRARED (FT-IR) SPECTROMETER WILL EMPLOYED FOR PHASE I. AN INEXPENSIVE SINGLE FREQUENCY SYSTEM WILL BE DEVELOPED IN PHASE II.