Production of ethanol
First Claim
1. In the method of producing ethanol from a carbohydrate-containing substrate mixed with non-fermentable solids, said method including the steps of continuously separating said substrate and solids into a flow rich in said solids and a substrate flow free from said solids, passing said substrate flow to a fermenter to produce ethanol by fermentation of said carbohydrate in the presence of yeast, withdrawing continuously from the fermenter a discharge stream of fermentation liquor containing yeast and ethanol, centrifugally separating said discharge stream continuously into at least a yeast concentrate flow and a yeast-free ethanol-containing flow, recirculating said yeast concentrate flow to the fermenter, and continuously separating said yeast-free flow into an ethanol-enriched flow and a residual flow, the improvement which comprises contacting at least part of said residual flow with said flow rich in solids to form a mixture, continuously separating said mixture in a plurality of separators into solids from which remaining substrate has been substantially removed and a flow enriched in substrate, and returning said flow enriched in substrate to the fermenter.
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Accused Products
Abstract
In the production of ethanol in plants, comprising a fermenter, a centrifugal separator for the recirculation of the yeast to the fermenter and a plant for the separation of a yeast-free flow, coming from the centrifugal separator, into one flow, rich in ethanol, and into one residual flow, the substrate, that is fed to the fermenter must be rid of solid substance, like fibres etc. In the separation of such solid substance a certain amount of substrate has been lost according to the methods utilized hitherto, or an unnecessarily high consumption of water and energy has occurred. According to the invention the solid substance, which is separated from the raw material flow, is washed, preferably countercurrently with said residual flow, which in turn, enriched in substrate, is fed to the fermenter. If a distillative method is used for said separation the residual flow is called slop.
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Citations
4 Claims
- 1. In the method of producing ethanol from a carbohydrate-containing substrate mixed with non-fermentable solids, said method including the steps of continuously separating said substrate and solids into a flow rich in said solids and a substrate flow free from said solids, passing said substrate flow to a fermenter to produce ethanol by fermentation of said carbohydrate in the presence of yeast, withdrawing continuously from the fermenter a discharge stream of fermentation liquor containing yeast and ethanol, centrifugally separating said discharge stream continuously into at least a yeast concentrate flow and a yeast-free ethanol-containing flow, recirculating said yeast concentrate flow to the fermenter, and continuously separating said yeast-free flow into an ethanol-enriched flow and a residual flow, the improvement which comprises contacting at least part of said residual flow with said flow rich in solids to form a mixture, continuously separating said mixture in a plurality of separators into solids from which remaining substrate has been substantially removed and a flow enriched in substrate, and returning said flow enriched in substrate to the fermenter.
Specification