Fluidized bed gasification of coal-oil and coal-water-oil slurries by oxygen-steam and oxygen-CO2 mixtures

摘要

Polish bituminous coal, German brown (subbituminous) coal and rapeseed oil were selected for preparation of coal-oil slurry (COS) and coal-oil in water slurry (COWS) with content of coal about 50 mass%. Laboratory, electrically heated gasifier with fluidized bed (FB) of sand particles was used for the coal slurries gasification with steam-02 and CO2-O2 mixtures (ER = 0,19-0.23) at temperatures between 800 and 925 °C, FB gasification with mixtures of O2/CO2 (CO2/dry fuel mass ratio 1-2,4) can generate producer gas with LHV values about 8-10 MJ/m~3, The heating value of the dry, N2-free producer gas from CO2-O2 gasification is lower in comparison with gasification by steam-O2 mixtures at comparable conditions. The heating value of the producer gas is influenced by a relatively high content of methane, ethylene and BTX compounds. The yield of heavier tar compounds (excluding BTX) is high, exceeding 20 g tar/kg of dry German coal based COS and exceeding 36 g/kg of fuel for Polish coal based COS. Cold gas efficiency is higher for fuel gas from gasification of COS based on the German, subbituminous coal. FB gasification (ER≈0.2) of the COWS prepared from the Polish coal (contents of coal, water and oil 47,40 and 12 mass% respectively) reduces tar yield approximately to an half (related to gasification of the corresponding COS slurry), but simultaneously moderately reduces the heating value (LHV) of the dry, nitrogen free producer gas.