Industrial application of apodized gas sensor for on-line and in situ measurement of CO and CO 2 concentration
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RESEARCH
Industrial application of apodized gas sensor for on‑line and in situ measurement of CO and CO2 concentration Alireza Khorsandi1 · Saeed Ghavami Sabouri1 Received: 15 February 2020 / Accepted: 21 September 2020 / Published online: 7 October 2020 © Islamic Azad University 2020
Abstract The performance of an apodized gas sensor is demonstrated through simultaneous detection of CO and C O2 absorption lines around 1.57 µm in the recuperator channel of a gas-fired industrial furnace at Shahid Montazeri power plant (SMPP) industry. This led to the concentration measurement of targeted molecules as less than ~ 1% and 9.5%, respectively, at atmospheric pressure and 350 °C, indicating close consistency with the reference data reported by SMPP. A minimum detectable absorption of ~ 0.4 × 10−3, corresponding to a detection sensitivity of ~ 4.8 × 10−9 cm−1 Hz−1/2 is measured in this application. Keywords Wavelength modulation spectroscopy · Apodized gas sensor · Tunable diode laser
Introduction Since most of the hazardous and pollutant molecules such as carbon monoxide (CO), nitric oxide (NO), methane (CH4) and carbon dioxide (CO2) exhibit sufficient absorption strengths in the near-infrared (NIR) region, much efforts have been conducted toward the development of new and simple spectroscopic methods. Tunable diode laser absorption spectroscopy (TDLAS) has shown very promising tools for in situ and on-line process control of industrial emissions, quantification of medical compounds and for security purposes as well [1]. Since the development of high efficient semiconductor lasers in the past 25 years, a remarkable improvement to the gas diagnostic systems has been attained using numerous TDLAS schemes [2]. Because of high performance and fast response characteristics of NIR-TDLAS base gas sensors, they have reached the expected detection sensitivities down to ppbv levels required, for example, in quantitative monitoring of medical markers in the human exhaled breath [3]. Those sensors have a very simple and robust setup and are compatible with many low-loss and cost-effective elements like optical fibers and glass-based lenses and windows. The essential requirements for an ideal gas sensor is a light * Alireza Khorsandi [email protected] 1
Department of Physics, University of Isfahan, Isfahan 81746‑73441, Iran
source possessing high spectral purity and beam quality, long time stability and broad tunability, wide dynamic range and immunity to environmental disturbances. Most of the above requirements have been met by the well-established continuous wave (CW) and room-temperature operated, distributed feedback (DFB) [4] and quantum cascade (QC) [5] lasers. These lasers are receiving a great interest in the NIR due to their excellent properties including single-mode operation, high spectral purity and sufficient optical power which make a DFB laser very competitive to other conventional sources such as Fabry–Perot-based and vertical cavity surface emitting lasers (VCSEL). However, scientific reports on
