| 摘要 |
Ethanol is prepared by fermenting beet sugar molasses or cane sugar molasses in a fermenter. The ethanol which is formed in the fermenter is recovered by operating a primary distillation step PD in circuit with the fermenter FI. A wort stream 5 is removed continuously from the fermenter FI, and the yeast-free wort is supplied, after separating and recirculating the yeast contained in the wort 5, to the primary distillation step PD. A part stream 14 of the bottom stream 13 from the primary distillation step PD is recirculated to the fermenter. By regulating the supply of water to the process circuit such that the concentration of non- fermentable substance in the fermenter FI is increased, during a first time period, from a starting value in the region of 5-15% by weight of dry substance DS to a value in the region of 20-30% by weight of DS, and by maintaining the latter high concentration during a second time period such that the average content of non- fermentable substance in the fermenter during these two time periods exceeds 20% by weight of DS, a drass which is on average very concentrated can be removed continuously from the process.
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