Simultaneous In Situ Measurement of CO, H 2 O, and Gas Temperatures in a FullSized Coal-Fired Power Plant by Near-Infrared Diode Lasers

We present what is to our knowledge the first near-infrared diode-laser-based absorption spectrometer that is suitable for simultaneous in situ measurement of carbon monoxide, water vapor, and temperature in the combustion chamber (20-m diameter, 13-m path length) of a 600-MW lignite-fired power plant. A fiber-coupled distributedfeedback diode-laser module at 1.56 (mu)m served for CO detection, and a Fabry-Perot diode laser at 813 nm was used to determine H2 O concentrations and temperature from multiline water spectra. Despite severe light losses (transmission, <10^-3 ) and strong background radiation we achieved a resolution of 1.9 * 10^-4 (1(sigma)) fractional absorption, equivalent to 200 parts in 106 by volume of CO (at 1450 K, 105 Pa) with 30-s averaging time.