Rugged multiwavelength NIR and IR analyzers for industrial process measurements

Timo S. Hyvarinen; Pentti Niemela

doi:10.1117/12.20263

1 August 1990 Rugged multiwavelength NIR and IR analyzers for industrial process measurements

Timo S. Hyvarinen, Pentti Niemela

Proceedings Volume 1266, In-Process Optical Measurements and Industrial Methods; (1990) https://doi.org/10.1117/12.20263
Event: The International Congress on Optical Science and Engineering, 1990, The Hague, Netherlands

Abstract

This paper discusses the advantages that can be achieved by using integrated multichannel detectors instead of the traditional filter wheel construction in process analyzers and presents four accomplished applications. Integrated multichannel detectors include several parallel detector elements each equipped with a specific interference filter and a Peltier cooler in one hermetic package. Advantages gained by filter integration are good withstanding of ambient stresses and low price due to small size. Multichannel detectors enable the use of different chopper techniques and rugged miniature and highly reliable analyzer constructions. Furthermore multichannel detectors provide exactly simultaneous measurement at each wavelength. This minimizes noise caused by rapid variations in fast moving nonhomogeneous process streams. The first application described is a two wavelength water monitor designed for on-line measurement of water content in lubricating oils. It has to meet high temperatures and high relative humidities in production plant environments. The oil analyzer is an advanced instrument that continuously measures oil content of water effluents in marine and land based applications. The peat moisture meter is a rugged portable NIR instrument constructed without any moving parts. Finally a four-wavelength NIR reflectance instrument is described. In a pilot application in a wood grinding plant the instrument with fibre optics is used to achieve a true in-line moisture measurement of the pulp stream having a speed of 15 - 40 rn/s and temperature of 125 - 145 OC. 1.

Citation Download Citation

Timo S. Hyvarinen and Pentti Niemela "Rugged multiwavelength NIR and IR analyzers for industrial process measurements", Proc. SPIE 1266, In-Process Optical Measurements and Industrial Methods, (1 August 1990); https://doi.org/10.1117/12.20263

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