科研之友
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摘要
Simultaneous dual-species monitoring offers potential for control of large-scale practical combustion systems. The development and demonstration of two dual-species sensors for characterizing NOx abatement (NO/NH3) and combustor performance (CO/O-2) are described for potential application in boiler exhaust at coal-fired electric utilities. Tunable laser absorption sensors for simultaneous in-situ detection of these paired species were developed using fundamental-band vibrational transitions in the mid-infrared near 5.2 mu m for NO, combination-band transitions near 2.25 mu m for NH3, overtone-band transitions near 2.3 mu m for CO, and electronic transitions in the b-X system near 760 nm for O-2. Scanned-wavelength, 1f-normalized wavelength modulation spectroscopy with second harmonic detection (WMS-2f) was employed for real-time data processing. Spatial-and time-demultiplexing strategies were used to combine and separate the laser signals. The sensors were tested for simultaneous, continuous monitoring in laboratory combustion exhaust from a premixed ethylene-air flame at atmospheric pressure and varied equivalence ratios with exhaust temperature of similar to 620 K. A retro-reflected 3.58 m beam-path was used to mimic a single-ended installation in a boiler exhaust duct. NH3 mixtures were metered into the flame at different rates to test the response of the NO/NH3 sensor, and the CO/CO2 ratio was adjusted by fuel/air equivalence ratio. Trends in the measured concentration ratio of NO to NH3 were found to agree qualitatively with theoretical expectation, and the CO and O-2 measurements were confirmed by analysis of sampled gases. The laser absorption exhibited the fast time response needed for control sensors. These fast-response, simultaneous dual-species sensors for NO/NH3 and CO/O-2 show excellent promise for control and optimization of NOx abatement and furnace efficiency in practical combustion systems.
- 出版日期2013
