Real-time process control using diode laser absorption sensors

Douglas S. Baer; E. R. Furlong; Ronald K. Hanson

doi:10.1117/12.255327

21 October 1996 Real-time process control using diode laser absorption sensors

Douglas S. Baer, E. R. Furlong, Ronald K. Hanson

Proceedings Volume 2834, Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Process Monitoring; (1996) https://doi.org/10.1117/12.255327
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

A multiplexed diode-laser sensor system, based on absorption spectroscopy techniques and comprised of two InGaAsP diode lasers and fiber-optic components, has been developed to measure temperature and species concentration non- intrusively over a single path for closed-loop process control. The system was applied to measure and control the gas temperature in the post-flame gases 6 mm above the surface of a Hencken burner. The wavelengths of the lasers were independently current-tuned across H₂O transitions near 1343 nm and 1392 nm. Temperature was determined from the ratio of measured peak absorbances, and H₂O concentration was determined from the measured peak absorbance of one transition set at the measured temperature. A closed-loop feedback system was demonstrated to control the mean temperature and the amplitude of temperature fluctuations at particular frequencies by appropriately modulating the fuel flow rate. The results obtained demonstrate the potential of multiplexed diode lasers for rapid, continuous, in situ measurements and control of gas dynamic parameters in high-temperature combustion flowfields and other environments with difficult optical access.

Citation Download Citation

Douglas S. Baer, E. R. Furlong, and Ronald K. Hanson "Real-time process control using diode laser absorption sensors", Proc. SPIE 2834, Application of Tunable Diode and Other Infrared Sources for Atmospheric Studies and Industrial Process Monitoring, (21 October 1996); https://doi.org/10.1117/12.255327

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