【摘要】 为解决固定化增殖酵母发酵生产酒精过程中生成的 CO₂气体附着在酵母载体表面,影响传质及生物反应速率,导致发酵过程操作条件恶化等问题,并针对发酵过程反应速度慢、要求液相停留时间长的特点,在外循环准三相流化床生物反应器发酵生产酒精过程中考察了固定化增殖酵母颗粒的特性、流化床生物反应器的流动特性及液相混合,提出了经修正的液相混合模型.在此基础上,对外循环流化床生物反应器应用于固定化酵母颗粒增殖和发酵生产酒精的过程进行了研究.更多还原

【Abstract】 An external circulation fluidized-bed bioreactor was studied and applied in continuous ethanol fermentation with alginate beads of immobilized yeast cells.The fluidization characteristics of alginate beads,fluidized state and liquid mixing were measured.Under the conditions of continuous ethanol fermentation,liquM mixing was well described by an ideally mixed flow reactor and a mixing coefficient.After proliferated for 48 hours in the bioreactor, the number of yeast cells in alginate beads increased from 10~6/ml to more than 10~9/ml. The ethanol fermentation utilizing molasses in the bioreactor was operated continuously, resulting in effluent ethanol concentration up to 9.0%(V/V),bioreactor productivity 14.2 g/h and the molasses conversion more than 92%.The macrokinetics of fermentation could be de- scribed by the modified Michaelis-Menten equation.Because of the intense interaction of beads with circulating liquids,it was observed in the experiments of continuous ethanol fermentation that carbon dioxide and the product Of fermentation,which adhered to the surface of alginate beads of immobilized yeast cells,was separated easily from the surface of beads and exhausted rapidily from the bioreactor in very small bubbles.The fermentation operation was very stable.更多还原