Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H sub(2)S measurements in a petrochemical process gas stream

The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8- mu m continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulf...

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Bibliographic Details
Published in:Analytical and bioanalytical chemistry 2017-01, Vol.409 (3), p.729-739
Main Authors: Moser, Harald, Polz, Walter, Waclawek, Johannes Paul, Ofner, Johannes, Lendl, Bernhard
Format: Article
Language:English
Subjects:
Absorption
Cascades
Gas sensors
Mathematical analysis
Platforms
Prototypes
Safety
Sensors
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Summary:The implementation of a sensitive and selective as well as industrial fit gas sensor prototype based on wavelength modulation spectroscopy with second harmonic detection (2f-WMS) employing an 8- mu m continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H sub(2)S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH sub(4)) matrix of up to 1000 ppmv together with a varying H sub(2)S content was chosen as the model environment for the laboratory-based performance evaluation performed at TU Wien. A noise-equivalent absorption sensitivity (NEAS) for H sub(2)S targeting the absorption line at 1247.2 cm super(-1) was found to be 8.41910 super(-10) cm super(-1) Hz super(-1/2), and a limit of detection (LOD) of 150 ppbv H sub(2)S could be achieved. The sensor prototype was then deployed for on-site measurements at the petrochemical research hydrogenation platform of the industrial partner OMV AG. In order to meet the company's on-site safety regulations, the H sub(2)S sensor platform was installed in an industry rack and equipped with the required safety infrastructure for protected operation in hazardous and explosive environments. The work reports the suitability of the sensor prototype for simultaneous monitoring of H sub(2)S and CH sub(4) content in the process streams of a research hydrodesulfurization (HDS) unit. Concentration readings were obtained every 15 s and revealed process dynamics not observed previously.
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-016-9923-z