CEM - Abstract

Abstract Information :

The Hydrogen molecule has for a long time been considered as non-absorbing in the infrared region. Indeed, H2 is a symmetrical diatomic molecule, like N2 or O2. But its absorption does exist in infrared, it is just that its absorption pics are very limited compared to other gases, and it could not be observed by standard IR gas analyzers. In 2015, AP2E was able to develop the measurement of Hydrogen using a near-infrared laser source. This achievement was possible thanks to OFCEAS measurement technic, or Optical Feedback Cavity Enhanced Absorption Spectroscopy. This gas analysis technology was developed by the University Joseph Fourier. OFCEAS essentially differs from the older technology enhanced-cavity TDLAS by its feedback principle: a part of the emitted radiation is returned from the chamber to the laser, enabling the tuning of the laser and the cavity, creating a resonance phenomenon. The measuring cavity in which the sample is analyzed is equipped with high reflectivity mirrors (>99,99%), providing an optical path up to 20 km. The consequence of this phenomenon is the identification of intense absorption peaks with narrow spectral width. With its long measuring pathlength, OFCEAS is therefore able to measure lower concentrations of gases in flue gas than standard analyzers. Achieving ppb measurement of dangerous gases such as HF, HCl, NH3, CHOH; and ppm measurement of H2. The correct measurement of lower gas concentrations will become critical in the next years, as governments are committed globally to reduce their environmental impact. And therefor to reduce the industrial emissions of harmful gases, and consider the combustion of H2 as a substitute to Natural Gas for power generation. Therefore, the OFCEAS technic might be of great help to reach Net Zero goal.