The development of a harsh environment ammonia slip sensor based on tunable diode laser absorption spectroscopy is presented. A hybrid optical sensor design, through combination of wavelength modulation spectroscopy (WMS) and alignment control, is proposed as an approach towards reliable in-situ measurements in misalignment prone harsh environments. 1531.59 nm, 1553.4 nm and 1555.56 nm are suggested as possible absorption lines for trace ammonia measurement (<1ppm at 10m path length at 500K) in gas turbine exhaust conditions. Design and performance of the alignment control system are presented in detail. Effect of misalignment related measurement degradation is investigated and significant improvement in measurement fidelity is demonstrated through the use of the hybrid optical sensor design.

Date Published: 13 May 2015
PDF: 7 pages
Proc. SPIE 9491, Sensors for Extreme Harsh Environments II, 94910D (13 May 2015); doi: 10.1117/12.2178117

Published in SPIE Proceedings Vol. 9491:
Sensors for Extreme Harsh Environments II
Debbie G. Senesky; Sachin Dekate, Editor(s)