THE DEVELOPMENT OF A FIBER OPTIC LASER ABSORPTION WATER SEN-SOR.

INDUSTRIAL DRYING OPERATIONS ARE MAJOR USERS OF ENERGY, REPRESENTING APPROXIMATELY 4 TO 6% OF TOTAL ENERGY USE BY U.S. INDUSTRY (OR APPROXIMATELY 1.2 TO 1.8 QUADS PER YEAR). SIGNIFICANT FRACTIONS OF THIS DRYING ENERGY ARE USED BY INDUSTRIES WHICH ARE CAPABLE OF EMPLOYING SOPHISTICATED CONTROL SYSTEMS FOR THEIR DRYING PROCESSES SUCH AS PULP AND PAPER, FOOD, TEXTILES, AND LUMBER. IN ADDITION, THE USE OF HYGROMETERS BY THESE INDUSTRIES TO MONITOR THE HUMIDITY IN THEIR DRYING CHAMBERS AND PROVIDE REAL-TIME PROCESS CONTROL INFORMATION HAS BEEN IDENTIFIED AS A ROUTE TO BOTH SIGNIFICANT ENERGY SAVINGS AND IMPROVED PRODUCT QUALITY. IN ORDER FOR THESE HYGROMETERS TO BE USEFUL TO THE ABOVE INDUSTRIES, THEY MUST BE ABLE TO MEASURE HUMIDITY RELIABILITY AT TEMPERATURES UP TO 450 DEGREES CENTIGRADE, AT HIGH HUMIDITY (50 TO 100%), AND IN ENVIRONMENTS CONTAINING PARTICULATES AND/OR FOULING OR CORROSIVE VAPORS. THIS PROJECT ADDRESSES THE DEVELOPMENT OF AN INNOVATIVE MULTIPLE SENSOR HYGROMETER PERMITTING MEASUREMENTS OF THE ABSOLUTE HUMIDITY IN THE TYPES OF INDUSTRIAL ENVIRONMENTS DISCUSSED ABOVE AND WHICH COULD BE USED IN A PROCESS CONTROLSYSTEM. IT WOULD USE A COMBINATION OF PROVEN SENSOR HEAD AND INNOVATIVE, NEAR INFRARED, DIODE LASER TECHNOLOGIES. THIS COMBINATION PERMITS OPERATION OF SEVERAL SENSOR HEADS CONNECTED BY OPTICAL FIBERS TO A SINGLE LASER/DETECTOR/ELECTRONICS PACKAGE, WHICH POTENTIALLY OFFERSLOWER SENSOR COSTS (AND, THEREBY, APPLICABILITY TO A WIDER RANGE OF INDUSTRIAL USERS) THAN EXISTING DESIGNS. THE OBJECTIVE OF THE PROJECT IS THE DEVELOPMENT OF A COMMERCIAL SENSOR FOR MONITORING AND CONTROLLING HUMIDITY IN INDUSTRIALDRYING CHAMBERS. AS A FIRST STEP TOWARDS THIS GOAL, A LABORATORY PROOF-OF-CONCEPT BREADBOARD WILL BE CONSTRUCTED IN PHASE I TO INVESTIGATE THE FUNDAMENTAL LIMITATIONS ON SENSITIVITY, SELECTIVITY, AND LINEARITY FOR WATER VAPOR DETECTION. IN PHASE II, A BRASSBOARD FIBER OPTIC LASER ABSORPTION WATER SENSOR (FLAWS) INSTRUMENT WILL BE CONSTRUCTED AND TESTED IN AN INDUSTRIAL DRYING CHAMBER, PROBABLY IN THE PULP AND PAPER INDUSTRY.