D7.4 - Measurement of Dissolved Gases in Anaerobic Biogenic Media

SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Proceedings SENSOR 2011
D7 - Medical II
M. Schelter, J. Zosel, F. Berthold, W. Oelßner, U. Guth - Meinsberg Kurt-Schwabe Research Institute, Ziegra-Knobelsdorf (Germany)
654 - 658


The anaerobic production of biogas from biomass is one of the most important pillars of renewable energy sources worldwide. This transformation is based on the complex teamwork of thousands of different microbes. The concentration of dissolved hydrogen is one of the key parameters known to indicate process stability limitations. In this work a measuring system for dissolved hydrogen in anaerobic biogenic media with high selectivity and sensitivity is presented, which provides high longterm stability and maintenance free operation. Due to the fact, that a long-term stable and selective measurement of dissolved hydrogen with membrane covered amperometric sensors is connected with some inevitable difficulties, a new approach was taken into account, which is based on a membrane free extraction of small amounts ofdissolved substances by a carrier gas flow. After chromatographic separation the components of this gas mixture are measured in a high temperaturesolid electrolyte cell made of yttria stabilized zirconia (YSZ), which is operated in a coulometric regime, resulting in the immediate total titration of hydrogen and other reducing gases by oxygen ions pumped through the YSZ. This method enables highly sensitive and calibration-free measurements without baseline drifting and a linear response to hydrogen concentrations between 0.5 ... 100 vol.- ppm according to the Faraday law. The complete measurement system was investigated in distilled water with defined amounts of dissolved hydrogen and methane. It indicates constant transfer of both gases into the extraction gas flow as well as longterm stable performance of the chromatographic measurement. Testing the system in a biogas lab plant and a biogas plant proofs the stable performance and the reliable resolution of dissolved hydrogen with high selectivity.