Fermentation process for the manufacture of an organic compound

Claim 1

A process for the manufacture of ethanol or a like volatile organic compound which process comprises the steps of fermenting in a fermenter a carbohydrate with a micro-organism which will convert the carbohydrate into ethanol or a like volatile organic compound, continuously transferring a portion of the fermentation medium, through a heat exchanger where it receives a supply of heat which raises the temperature of the medium to a temperature which is below that at which the micro-organism is rapidly rendered inactive, but which is such that subsequent evaporation of ethanol or the like volatile organic compound at a reduced pressure will be facilitated, to a separator where ethanol or the like volatile organic compound is evaporated from the fermentation medium at a temperature which is not deleterious to the micro-organism by subjecting the fermentation medium to a reduced pressure and recycling part or all of the remaining fermentation medium to the fermenter, the rate of the circulation of fermentation medium from the fermenter to the separator and back being such that the amount of ethanol or like volatile organic compound in the fermentation medium in the fermenter is kept sufficiently low so as not to detrimentally affect the rate of fermentation, subjecting the vapour issuing from the separator to a fractional distillation column containing a low pressure drop contacting medium under reduced pressure thereby to separate the components of the vapour, compressing the vapour issuing from the top of the fractionation distillation column thereby raising its temperature, recondensing the compressed vapour in a heat transfer system to provide heat, and using said heat both for evaporating ethanol or the like volatile organic compound from the fermentation medium in the separator and for said frictional distillation of the vapour.