title: Implementation of a quantum cascade laser-based gas sensor prototype for sub-ppmv H2S measurements in a petrochemical process gas stream.
abstract: 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-μm continuous-wave distributed feedback quantum cascade laser (CW-DFB-QCL) for monitoring hydrogen sulfide (H2S) at sub-ppm levels is reported. Regarding the applicability for analytical and industrial process purposes aimed at petrochemical environments, a synthetic methane (CH4) matrix of up to 1000 ppmv together with a varying H2S content was chosen as the model environment for the laboratory-based performance evaluation performed at TU Wien. A noise-equivalent absorption sensitivity (NEAS) for H2S targeting the absorption line at 1247.2 cm-1was found to be 8.419 × 10-10cm-1Hz-1/2, and a limit of detection (LOD) of 150 ppbv H2S 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 H2S 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 H2S and CH4content in the process streams of a research hydrodesulfurization (HDS) unit. Concentration readings were obtained every 15 s and revealed process dynamics not observed previously.
authors.affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, 1060, Vienna, Austria.
authors.forename: Harald
authors.initials: H
authors.lastname: Moser
authors.affiliation: OMV R&M GmbH, 2320, Schwechat, Austria.
authors.forename: Walter
authors.initials: W
authors.lastname: Pölz
authors.affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, 1060, Vienna, Austria.
authors.forename: Johannes Paul
authors.initials: JP
authors.lastname: Waclawek
authors.affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, 1060, Vienna, Austria.
authors.forename: Johannes
authors.initials: J
authors.lastname: Ofner
authors.affiliation: Institute of Chemical Technologies and Analytics, Vienna University of Technology, 1060, Vienna, Austria. bernhard.lendl@tuwien.ac.at.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Lendl
keywords: HDS monitoring; Hydrogen sulfide; Infrared laser spectroscopy; Laser sensor; Methane; Quantum cascade lasers