There are various attempts to industrialize the supercritical water gasification (SCWG) of wet biomass process, however, there are still process challenges to overcome. Such challenges include slurry pumpability, energy efficiency, low conversion, char and tar formation, and clogging problems due to salt precipitation. Fortunately, some of the aforementioned challenges can be eliminated by having long residence times, high heating rates and utilization of fluidized bed reactors. This study presents the first results and experiences obtained from the TU Delft/Gensos semi-pilot scale setup which has a capacity of 50 kg/h and incorporates a fluidized bed reactor. A dry starch concentration of 4.4 wt % was used as feedstock. Reactor temperatures of 500 °C, 550 °C and 600 °C, and the mass flow rates of 24.5 kg/h and 35 kg/h were tested. The results indicate that the heating profile in the heat exchanger and the residence time at higher temperatures (>500 °C) play a significant role in the conversion efficiencies. No clogging problem was observed, however small quantities of char (2.3 wt % at highest) and oil production (10.4 wt % at highest) were observed. The highest carbon gasification efficiency was 73.9% and this was obtained at a reactor temperature of 600 °C and at a feed flow rate of 24.5 kg/h.

There is a growing interest in organic Rankine cycle (ORC) turbogenerators because of their ability to efficiently utilize external heat sources at low-to-medium temperature in the small-to-medium power range. High-temperature ORC turbines typically operate at very high pressure ratio and expand the organic working fluid in the dense-vapor thermodynamic region, thus requiring computational fluid dynamics (CFD) solvers coupled with accurate thermodynamic models for their performance assessment and design. In this paper we present a steady-state three-dimensional viscous CFD study of the Tri-O-Gen ORC radial turbine, including the radial nozzle, the rotor and the diffuser. The turbine operates with toluene as the working fluid, whose accurate thermophysical properties are obtained with a look-up table approach. Based on the 3D simulation results, together with a 2D fluid dynamic optimization procedure documented elsewhere, an improved nozzle geometry is designed, manufactured and experimentally tested. Measurements show it delivers 5 kW_e or 4% more net power output, as well as improved off-design performance.