Influence of feed concentration and residence time on the efficiency and gas yield of Supercritical Water Gasification of Glycerol

The experiments discussed in this thesis have been performed in the Department of Chemical Engineering, Process & Systems Engineering Laboratory, at Åbo Akademi University in Turku. Supercritical Water Gasification of glycerol has been carried out on a laboratory scale at 600 °C and 250 bar, by setting three levels of feed concentration (2.5, 5 and 10%) and three levels of volume flow rate of nitrogen (125, 250 and 375 ml/min). The latter, which is inversely proportional to the residence time, is used to push the biomass solution into the reactor. The choice of these parameters was a consequence of the previous experiments made in the same laboratory and of a careful bibliographic survey. The experiments, indeed, were performed in order to study the influence of feed concentration and residence time on the efficiency and gas yield of SCWG of glycerol, as the effect of temperature and pressure has already been widely investigated. Besides, the aim of this thesis is also to evaluate the effect of heterogeneous catalysis on the gasification process, by using two different types of reactors: SS 316 (without catalytic properties), and the catalytic INCONEL 625. The outputs of the process investigated in this thesis are the volume concentration of hydrogen, carbon dioxide, methane, carbon monoxide, ethane and ethylene of the syngas produced; the gasification and cold gas efficiencies and the gas yields. Eventually, a simplified design of experiments of the volume concentration of the hydrogen has been performed in order to have a qualitative overview of the effects of the input parameters.