Ethanol bioproduction in three-phase fluidized bioreactors

Abstract EN

Abstract In the last decade bioalcohol has become more and more important as an alternative energy source and chemical feed stock.

Bioethanol production has been proposed as a gasoline enhancer to reduce greenhouse gases, gasoline imports, and to boost the economy. Circulating fluidized beds (CFB) have been used in a variety of industrial processes due to their distinct advantages of uniform temperature distribution, high gas-to- particle mass and heat transfer rates and flexible operation. The present study deals with the experimental analysis of the circulating fluidized bed reactor, which is applied to the fermentation of glucose to ethanol.

The study takes into consideration the presence of three different phases; yeast (solid) which is continuously fluidized by the liquid stream (glucose solution), and the gas bubbles which greatly enhance mixing and the wake phase which follows tracks of the gas bubbles.

The reactor performance is analyzed as a function of major operating conditions, the yeast mass in the reactor (30-150gm/l), the concentration of glucose in feed (10-150gm/l), reaction temperature (15,25,30,36,37, and 40?C) , and velocities of gas and liquid feeds (0.01-0.1m/s). The results indicate that high glucose conversions can be obtained at high gas velocities, low liquid velocities, high yeast concentration, and an optimum operating temperature of 36oC.-