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Installation of a Multiplexed Raman System in a Chemical Process

Volume 58, Number 12 (Dec. 2004) Page 1500-1505

Weyer, Lois G.; Yee, Dupon; Pearson, Gary I.; Wade, John


A 785 nm laser dispersive Raman system was installed in a hazardous chemical production plant to monitor two reactors, a still, and a holding tank with measurement directly through sight glasses. Compositional information for several raw materials, intermediates, and products was obtained using partial least squares (PLS) calibrations. Discriminate analysis was used to exclude extremely poor spectra while including usable ones. Derivative/standard normal variate (SNV) treatment was found to be effective for correcting for background fluorescence and for large differences in spectral intensity. Final regression equations incorporated temperature fluctuations, occasional fluorescence, some sunlight effects, large intensity variations, and large compositional changes. Various installation problems were solved via data treatment or mechanical changes. The Raman system provides information for control of the process, resulting in cost savings and improved safety.