HYDRODYNAMIC STUDIES OF AN ADVANCED FLUIDIZED-BED BIOREACTOR FOR DIRECT COAL-LIQUEFACTION

Advanced bioreactors can play an important role in coal utilization an d conversion. To obtain the high throughput and low inventory required for large-scale bioprocessing of coal, a new family of bioreactors is being developed. The reactors on which this study is focused are cont inuous columnar bioreactors, which can be operated as three-phase syst ems. In particular, this study is oriented toward fluidized-bed system s for direct biological interactions with fine (30-150 mum) coal parti cles. Illinois no. 6 bituminous coal was ball-milled and then suspende d in a 0.1% aqueous solution of the surfactant (Tween 80 (polyoxyethle ne), which was used to reduce particle aggregation. Experimental fluid ized-bed studies were then performed, using size-screened coal fractio ns. Studies were performed to quantify the extent of particle segregat ion and to quantify particle mixing effects within the reactor. To do so, pressure drop vs time data has been recorded as a function of axia l position along the bed height. To better understand this experimenta l data, predictive mathematical models based on fundamental principles of mass and momentum transfer have been developed. Comparisons of mod el predictions with experimental data are presented.