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

Abstract

Biomass (wood and Miscanthus pellets) and Rhenish brown-coal were gasified using a 1.5 MW th (max.) pressurised fluidised bed gasification (PFBG) installation. NO x 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 NH 3 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.