High performance direct absorption spectroscopy of pure and binary mixture hydrocarbon gases in the 6-11 mu m range

作者:Heinrich Robert; Popescu Alexandru*; Hangauer Andreas; Strzoda Rainer; Hoefling Sven
来源:Applied Physics B: Lasers and Optics , 2017, 123(8): 223.
DOI:10.1007/s00340-017-6796-6

摘要

The availability of accurate and fast hydrocarbon analyzers, capable of real-time operation while enabling feedback-loops, would lead to a paradigm change in the petro-chemical industry. Primarily gas chromatographs measure the composition of hydrocarbon process streams. Due to sophisticated gas sampling, these analyzers are limited in response time. As hydrocarbons absorb in the mid-infrared spectral range, the employment of fast spectroscopic systems is highly attractive due to significantly reduced maintenance costs and the capability to setup real-time process control. New developments in midinfrared laser systems pave the way for the development of high-performance analyzers provided that accurate spectral models are available for multi-species detection. In order to overcome current deficiencies in the availability of spectroscopic data, we developed a laser-based setup covering the 6-11 mu m wavelength range. The presented system is designated as laboratory reference system. Its spectral accuracy is at least 6.6 x 10(-3) cm(-1) with a precision of 3 x 10(-3) cm(-1). With a "per point" minimum detectable absorption of 1.3 x 10(-3) cm(-1) Hz(-1/2) it allows us to perform systematic measurements of hydrocarbon spectra of the first 7 alkanes under conditions which are not tabulated in spectroscopic database. We exemplify the system performance with measured direct absorption spectra of methane, propane, iso-butane, and a mixture of methane and propane.

  • 出版日期2017-8