High-temperature dual-species (CO/NH3) detection using calibration-free scanned-wavelength-modulation spectroscopy at 2.3 μm. (1st December 2021)

• Record Type: Journal Article
• Authors: Raza, Mohsin; Ma, Liuhao; Yao, Shunchun; Chen, Longfei; Ren, Wei
• Is Part Of: Fuel. Volume 305(2021)
• Publication Date: 2021-12-01
• Subjects: Absorption spectroscopy -- Scanned-wavelength-modulation spectroscopy -- In-situ sensing -- Ammonia -- Carbon monoxide -- Distributed feedback laser; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2021.121591
• Languages: English
• ISSNs: 0016-2361

Abstract

Highlights: Calibration-free scanned-wavelength-modulation spectroscopy was demonstrated for high-temperature dual-species (CO/NH3 ) detection. Single DFB laser was employed to simultaneously detect CO and NH3 at 2.3 μm. The noise equivalent absorption coefficient of 3.5 × 10 -6 cm −1 for CO and 4.9 × 10 -7 cm −1 for NH3 was obtained at 700 K with absorption path length of 20 cm. The developed dual-species sensor has a promising potential to be applied in the exhaust of practical combustion systems such as NH3 monitoring for NOx abatement in SCR aftertreatment and CO sensing to optimize combustor efficiency. Abstract: A dual-species sensor based on scanned-wavelength-modulation spectroscopy (scanned-WMS) with the 2 f /1 f detection is developed for calibration-free CO and NH3 detection in high-temperature environments. A 2.3 μm distributed feedback (DFB) diode laser was used to exploit the CO and NH3 lines centred at 4300.7 cm −1 and 4301.13 cm −1, respectively. The DFB laser was scanned across the target absorption lines at 100 Hz with fast sinusoidal modulation at 5 kHz. The spectral fitting strategy was employed to least-square fit the simulated and measured WMS-2 f /1 f spectra. The integrated absorbance of target transitions inferred from the scanned-WMS-2 f/ 1 f spectral fitting was used to determine the species concentration. The performance of the developed sensor was validated by simultaneously measuring species concentrations under various temperatures (300–700 K) and at 1 atm in a high-temperature gas cell. The noise equivalent absorption (NEA) coefficient of 3.5 × 10 -6 cm −1 for CO and 4.9 × 10 -7 cm −1 for NH3 was achieved at 700 K with an absorption path length of 20 cm. The developed dual-species sensor has the potential to be applied in the exhaust of practical combustion systems such as NH3 monitoring for NOx abatement in selective catalytic reduction (SCR) aftertreatment and CO sensing for optimizing combustor efficiency.