Advanced diode-laser absorption sensors for combusion monitoring and control

Douglas S. Baer; Edward R. Furlong; Radu M. Mihalcea; Michael E. Webber; Ronald K. Hanson

doi:10.1117/12.337462

22 January 1999 Advanced diode-laser absorption sensors for combusion monitoring and control

Douglas S. Baer, Edward R. Furlong, Radu M. Mihalcea, Michael E. Webber, Ronald K. Hanson

Proceedings Volume 3535, Advanced Sensors and Monitors for Process Industries and the Environment; (1999) https://doi.org/10.1117/12.337462
Event: Photonics East (ISAM, VVDC, IEMB), 1998, Boston, MA, United States

Abstract

A multiplexed diode-laser absorption sensor system, comprised of two distributed feedback (DFB) InGaAsP diode lasers and fiber-optic components, has been developed to non-intrusively measure gas temperature and H₂O concentration over a single path in the combustion region of a 50-kW purposed annular dump combustor. The wavelengths of the DFB lasers were independently current-tuned at 10-kHz rates across H₂O transitions near 1343 nm and 1392 nm. Temperature and water vapor concentration were determined from the measured absorbances. In addition, measurements of CO, C₂H₂, and C₂H₄ concentrations in the exhaust were determined from absorption spectra recorded using a fast-sampling probe, a multi-pass absorption cell, an external cavity diode laser (ECDL), and a distributed feedback diode laser (DFB). The ECDL was tuned over the CO R(13) transition near 1568 nm and the C₂H₂ P(17) transition near 1535 nm, and the DFB laser was tuned over selected C₂H₄ transitions near 1646 nm. A correlation was established between the magnitude of the measured temperature oscillations in the combustion region and measured concentrations of CO and hydrocarbons in the exhaust. Adaptive control strategies were applied to maximize the coherence of the temperature oscillations and thus optimize the combustor performance. The closed-loop control system was able to adaptively optimize the phase and amplitude of the applied forcing within 100 ms, and the forcing frequently within 10 seconds. These results demonstrate the applicability of multiplexed diode-laser absorption sensors for rapid, continuous measurements and control of multiple flowfield parameters, including trace species concentrations, in high-temperature environments.

Citation Download Citation

Douglas S. Baer, Edward R. Furlong, Radu M. Mihalcea, Michael E. Webber, and Ronald K. Hanson "Advanced diode-laser absorption sensors for combusion monitoring and control", Proc. SPIE 3535, Advanced Sensors and Monitors for Process Industries and the Environment, (22 January 1999); https://doi.org/10.1117/12.337462

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