Non-intrusive in situ detection of methyl chloride in hot gas flows using infrared degenerate four-wave mixing

摘要

We demonstrate the potential of infrared degenerate four-wave mixing (IR-DFWM) as a tool for non-intrusive in situ spatially resolved detection of CH3Cl in reactive hot gas flows especially feasible for applications to biomass combustion and gasification. IR-DFWM spectra of CH3Cl, by probing ro-vibrational transitions belonging to the fundamental stretching modes v(1) and v(4), have been successfully recorded in gas flows diluted with nitrogen at atmospheric pressure and elevated temperatures up to 820K. In order to identify the spectral lines of CH3Cl, the recorded IR-DFWM spectra are compared with simulations using molecular parameters extracted from the HITRAN database. The potential interference from water vapor is discussed from measurements of H2O spectrum at 820K combined with simulations of H2O IR-DFWM spectrum based on the HITEMP database, and it was found that the (Q)Q(6) line of the v(1) band is relatively free from water interference at elevated temperatures. At atmospheric pressure, the detection limits for temperatures at 296, 550 and 820K were estimated to be 2.1, 3.1 and 6.2 (x10(15) molecules/cm(3)), respectively, by scanning the (Q)Q(6) line of the v(1) band. These results show the potential of interference free detection of CH3Cl with IR-DFWM in harsh environments like combustion. Copyright (c) 2015 John Wiley & Sons, Ltd.