AN ON-LINE WAVEGUIDE REFRACTOMETER FOR THE EDIBLE OIL HYDROGENATION PROCESS

AN OPTICAL WAVEGUIDE OF KNOWN REFRACTIVE INDEX (RI) CHARACTERISTICS BECOMES AN ON-LINE PROCESS REFRACTOMETER FOR MEASURING THE RI, HENCE IODINE VALUE (IV), OF EDIBLE OILS UNDERGOING PARTIAL HYDROGENATION. THE REFRACTOMETER OPERATES IN THE PRESENCE OF NICKEL CATALYST AND DIATOMACEOUS EARTH USED IN THE HYDROGENATION PROCESS. THE CLADLESS WAVEGUIDE, EXCITED BY A MONOCHROMATIC LIGHT SOURCE, WOULD BE IMMERSED IN SAMPLED OIL CONTINUOUSLY FLOWING FROM THE HYDROGENATION VESSEL. THE OIL TEMPERATURE IS MODULATED, VARYING THE OIL RI. THE LIGHT TRANSMITTED THROUGH THE WAVEGUIDE UNDERGOES A SHARP ATTENUATION, AS PREDICTED BY SNELL'S LAW AND FRESNEL'S EQUATIONS, WHEN THE OIL RI AND WAVEGUIDE (REFERENCE) RI COINCIDE. THE REFRACTOMETER MEASURES THE TEMPERATURE AT THIS MINIMUM AND, USING A PROGRAMMABLE ALGORITHM, CORRECTS THE OIL RI TO A STANDARD TEMPERATURE AND WAVELENGTH. THE REFRACTOMETER'S REAL-TIME OUTPUT MAY BE RI UNITS, IV UNITS AND/OR A SIGNAL FOR PROCESS CONTROL. CALIBRATION FOR SPECIFIC OILS IS ACCOMPLISHED BY VARYING THE ALGORITHM'S COEFFICIENTS. THIS INSTRUMENT ELIMINATES THE DISADVANTAGES ASSOCIATED WITH THE CURRENT STANDARD OFF-LINE MEASUREMENT METHOD USING THE ABBE REFRACTOMETER.