ONLINE MONITORING OF ALUMINIUM PRIMARY PRODUCTION GAS COMPOSITION BY USE OF FOURIER-TRANSFORM INFRARED SPECTROMETRY

摘要

Online monitoring of aluminium primary production raw gas is challenging due to the high concentration of HF in the presence of water. Tunable Diode Laser (TDL) analyzers retrofitted with sapphire optical windows allow for online monitoring of raw gas composistion. These systems are however limited to one or two gas constituents. In order to make use of multi-component analyzers like Fourier-Transform InfraRed Spectrometers (FTIR), HF must be selectively removed by filtration. This work presents some results from complete mapping of raw gas composition by comparing results from HF filtrated as well as non-filtrated measurements. The multivariate calibration models established for mapping of the raw gas is discussed. Open-path FTIR spectroscopy was applied in order to quantify fugitive emissions of HF and SO_2. Quantitation showed good correlation with reported emissions. Monitoring of fugitive PFC emissions was also evaluated.