Method of producing ethanol through fermentation of carbohydrates

摘要

Residue-free production of ethanol and unicellular protein in a gas-fluidized bed, in which ethanol production takes place in a gas-fluidized bed (stirred fluidized bed, fluid column), the particle fraction of which consists of a wet microorganism mass, e.g. Saccharomyces cerevisiae. A nutrient solution with fermentable carbohydrates is sprayed onto the fluidized particles. The ethanol, which evaporates with the water, is precipitated in a condenser on the discharge side, so that the fluidized bed serves as bio-reactor as well as one-stage distillation plant (together with the cooling system). Thus, the mash column, which is normally used for alcohol production with the submersion method, is not needed in the present invention. In place of the residue, a protein-rich product with 30-40% dry mass is formed, which, during continuous operation, can be removed at certain intervals from the bioreactor and can be dried to the desired degree. The propagation of the microorganisms can be regulated through the oxygen content of the gas phase; the ethanol production can be regulated through the infeed of the nutrient solution. The gas used for fluidization is recirculated into the bed. The partial oxygen pressure can be controlled by adding other gases to the air, such as nitrogen or carbon dioxide, particularly carbon dioxide, which forms the yeast itself.