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Intrinsically Safe Fiber-Optic Photoacoustic Gas Sensor for Coal Spontaneous Combustion Monitoring | IEEE Journals & Magazine | IEEE Xplore

Intrinsically Safe Fiber-Optic Photoacoustic Gas Sensor for Coal Spontaneous Combustion Monitoring


Abstract:

A high-sensitivity fiber-optic photoacoustic (PA) gas sensor has been presented for coal spontaneous combustion monitoring. The gas sensing head is connected with the dem...Show More

Abstract:

A high-sensitivity fiber-optic photoacoustic (PA) gas sensor has been presented for coal spontaneous combustion monitoring. The gas sensing head is connected with the demodulator by two optical fibers, which are used to transmit the laser light for generating PA signal and the white light for detecting PA pressure, respectively. The gas sensing head itself does not have electronic components, resulting in intrinsic safety. The filtered gas diffuses into the unsealed miniature PA chamber. A 1531.6-nm laser is used to excite acetylene (C2H2) gas molecules to produce PA pressure waves. The generated PA signal is detected by a Fabry–Perot (F-P) interferometric cantilever, which is demodulated by a high-speed spectral demodulation method. Theoretical and experimental results show that high-concentration methane (CH4) background gas has an impact on PA response of trace C2H2. This is mainly due to the changes in the gas specific heat ratio and cantilever response due to the change in mixed gas concentration. Another near-infrared laser with a wavelength of 1653.7 nm is chosen to measure the concentration of CH4 to eliminate the influence of high-concentration CH4 gas. Experimental results indicated that C2H2 detection limit can reach 1 ppm with the background CH4 concentration range of 0%–50%.
Article Sequence Number: 7005109
Date of Publication: 27 June 2022

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