Thermochemical conversion of brown coal and biomass in a pressurised fluidised bed gasifier with hot gas filtration using ceramic channel filters: measurements and gasifier modelling
Biomass (wood and Miscanthus pellets) and Rhenish brown-coal were gasified using a 1.5 MWth (max.) pressurised fluidised bed gasification (PFBG) installation. NOx precursor and tar emissions were studied by varying process parameters like the fuel type, pressure, temperature and air factor. Carbon conversions were well above 80%. Fuel-nitrogen conversion into NH3 was mostly above ca. 50%. Fuel-nitrogen conversion into HCN was significantly lower. Results were in-line with comparable investigations with bottom feeding. Measurements of the gas composition for Miscanthus gasification were compared with a steady-state model based on elementary reaction chemistry and heterogeneous gas–char reactions related to the emission of nitrogen species. A flash pyrolysis model (FG-DVC-biomass version) was applied to determine the initial yields. Measurements and model simulation results were in reasonably good agreement.