Browsing by Subject "Near-infrared reflection spectroscopy (NIRS)"

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    Entwicklung und Erprobung eines Online-Messsystems für Biogasanlagen auf Basis der Nah-Infrarot-Reflexionsspektroskopie (NIRS)
    (2013) Stockl, Andrea; Jungbluth, Thomas
    Due to the EU?s and Germany?s political goals of expanding the use of renewable energy sources, the utilization of biomass for energy supply is expected to continue growing in the coming years. Consequently, the efficiency of biogas plants will have to be improved further. This applies both to raising the energy yield from the input materials and exploiting the full potential of the technical installations. During the four phases of the anaerobic digestion (AD) process, volatile fatty acids such as acetic and propionic acids are produced as intermediates. These compounds can be used as indicators of the function and stability of the digestion process. So far, volatile fatty acids have to be determined by sampling the digester content and analyzing the sample in the laboratory (e.g., by gas chromatography). It is thought that by using near-infrared-reflection spectroscopy (NIRS) for online measuring, the management and control of biogas plants could be facilitated, considerably. This was to be investigated in a project funded by the Baden-Württemberg Ministry of Rural Areas and Consumer Protection within the ?research platform on bioenergy? Baden-Württemberg?. In this study, a NIR-measurement system was calibrated for determining the concentration of volatile fatty acids in two semi-continuously operated, bench-scale digesters at mesophilic and thermophilic temperature level. For each of the two digesters, one NIR-sensor was calibrated for acetic and propionic acid, and a second one for total acid equivalents. The experimental studies were divided into three stages. The chapters of this research work consist of three peer-reviewed papers that describe these experiments.