Investigation of the Oxy-fuel Gasification of Coal in a Laboratory-Scale Spouted-Bed Reactor: Reactor Modifications and Initial Results

Fluidized-bed gasifiers in combination with integrated gasification combined cycle (IGCC) technology are an efficient way to make use of low-value coal, waste, and biomass for power generation. However, air/steam blown gasifiers produce a fuel gas diluted with N₂, making expensive CO₂?N₂ separation processes necessary for integration with carbon capture and storage technology. To overcome this limitation, a novel process is proposed in this work where the bed is fluidized with an O2/CO₂ mixture, with CO₂ being recycled from the combusted fuel gas stream. A laboratory-scale spouted-bed gasifier was developed to investigate the potential of this concept. This work focuses on the overall operability of the gasifier as well as the effect of operating parameters on the gasification performance of two different coals when high partial pressures of CO₂ are employed. The temperature increase in the range of 850?950 °C produced a significant increase in carbon conversion, while the effect of the O/C ratio was more marked at the lower end of that temperature range. The tar release decreased with both the temperature and O/C ratio and was mainly observed during the beginning of each run, before the carbon content of the bed reached levels high enough to provide effective tar-cracking mechanisms.