| abstract |
An on-line, fiber-optic based apparatus for monitoring the concentration of a chemical substance at a plurality of locations in a chemical processing system comprises a plurality of probes, each of which is at a different location in the system, a light source (40), optic fibers for carrying light to (60, 64, 68) and from (80, 82, 84) the probes, a multiplexer (50) for switching light from the source from one probe to the next in series, a diode array spectrophotometer (92) for producing a spectrum from the light received from the probes, and a computer (94) programmed to analyze the spectra so produced. The probes allow the light to pass through the chemical substance (70) so that a portion of the light is absorbed before being returned to the multiplexer. A standard (66) and a reference cell (62) are included for data validation and error checking. |