The Raman Spectrum of Gaseous CF4

Dynamic Detection of Decomposition Gases in Eco-Friendly C5F10O Gas-Insulated Power Equipment by Fiber-Enhanced Raman Spectroscopy

Dynamic detection of multiple C5F10O decomposition gases can more comprehensively and effectively evaluate the operating status of eco-friendly gas-insulated power equipment (GIPE), which is a technical support for promoting the construction of eco-friendly, low-carbon energy power systems. In this article, we propose a silicon noise suppression fiber-enhanced Raman spectroscopy (FERS) technique and design a FERS sensing system for the dynamic detection of multiple C5F10O decomposition gases. Benefiting from the effective hybrid silicon noise filtering technology, the spectrum noise of FERS can be suppressed by 90% and the system detection sensitivity can be improved by 4.22 times. Utilizing a 2 m-long antiresonant hollow-core fiber, the system achieved detection limits of 1.34 and 1.44 ppmv for CF4 and CO2, respectively, under the conditions of a laser power of 200 mW, a pressure of 0.5 MPa, and a measurement time of 120 s. Afterward, combining sample gas and density functional theory simulation, the characteristic peak positions for quantitative analysis of C5F10O decomposition gas were determined as follows: CF4: 906 cm-1, CO2: 1388 cm-1, C5F10O: 759 cm-1, CF2O: 965 cm-1, CF3H: 1117 cm-1, C2F4: 517 cm-1, C2F6: 807 cm-1, C3F6: 767 cm-1, C3F8: 780 cm-1, C3F7H: 857 cm-1, and C4F10: 770 cm-1. Finally, the sensing system conducted dynamic measurements of the partial discharge decomposition gases of the C5F10O GIPE for 5 days with a 2 h measurement interval. The content trends of C5F10O and decomposition gases CF4, CO2, C3F6, and C3F7H were obtained. These results fully demonstrate the capability of FERS technology for dynamically detecting the decomposition gases of the C5F10O GIPE.

Trace Analysis of C4F7N Insulating Gas Mixtures by Spontaneous Raman Spectroscopy and Gas Chromatography

2,3,3,3-Tetrafluoro-2-(trifluoromethyl) propanenitrile (C4F7N) is being researched as an alternative to sulfur hexafluoride (SF6) for applications in gas-insulated switchgear. We independently assessed the effectiveness of gas chromatography-mass spectrometry (GC-MS) and a novel method of feedback-assisted multipass cavity spontaneous Raman spectroscopy (SRS) for the trace quantification of impurities in C4F7N and its related byproducts. A total of 14 gases were identified with estimated concentrations as low as 20 ppm (ppm) for C3F6 using GC-MS and 7.4 ppm for CH4 using SRS and as high as 500 ppm for CF4 using GC-MS and 1430 ppm for CO using SRS. While GC-MS is highly effective in selectively detecting and quantifying trace contaminants, it necessitates separate detectors for various gases, such as CH4 and H2. SRS succeeded in detecting CF4 and C2F6 at concentrations of 465 and 100 ppm, respectively, and in placing an upper bound of several hundred ppm for the other analytes. Crucially, SRS holds potential for portability-and thus for field applications-in gas-insulated switchgear equipment diagnostics.