Abstract High solid fermentation during bioethanol production is a promising process engineering strategy to reduce total energy use and water requirements, and to improve productivity. However, ethanol toxicity at higher concentrations restricts the corn solids to 30–32% (w/w) during dry grind corn ethanol process. This work, using in situ ethanol removal, results in two big improvements in the fermentation process: 1) achieve complete fermentation of high solids slurries (up to 42%) at typical commercial enzyme dosages, and 2) fasten the fermentation process for currently used process with 32% solids. Application of vacuum at optimal times during fermentation (1 h at 12, 24, 36, and 48 h) of 40% corn solids resulted in complete fermentation, compared to about 12% residual glucose in the conventional process. The ethanol yield of 0.42 L/kg of dry corn with about 80% ethanol conversion efficiency was 88% higher than that of the conventional process at 42% solids (0.22 L/kg dry corn). Application of 1.5 h of vacuum at 18 and 24 h of fermentation with 32% solids resulted in high fermentation rates and decreased the fermentation time by more than 50%. Shorter fermentation times can allow processing of more material with the same equipment and allow smaller fermentation tanks in new plants, which would lead to both, lower capital and operating cost.

中文翻译：

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提高干磨玉米生产生物乙醇生产工艺的发酵技术

摘要 生物乙醇生产过程中的高固体发酵是一种有前景的工艺工程策略，可以减少总能源使用和水需求，并提高生产力。然而，在干磨玉米乙醇过程中，较高浓度的乙醇毒性将玉米固体限制在 30-32% (w/w)。这项工作使用原位乙醇去除，对发酵过程产生了两大改进：1) 在典型的商业酶剂量下实现高固体浆液 (高达 42%) 的完全发酵，以及 2) 加快目前使用的发酵过程固体含量为 32% 的工艺。在 40% 玉米固体的发酵过程中（1 小时、12、24、36 和 48 小时）的最佳时间应用真空导致完全发酵，而传统工艺中的残余葡萄糖约为 12%。乙醇收率为0。乙醇转化效率约为 80% 的 42 L/kg 干玉米比 42% 固体（0.22 L/kg 干玉米）的常规工艺高 88%。在固体含量为 32% 的发酵 18 小时和 24 小时时应用 1.5 小时真空可提高发酵率并将发酵时间缩短 50% 以上。更短的发酵时间可以允许使用相同的设备处理更多的材料，并允许在新工厂中使用更小的发酵罐，这将导致更低的资本和运营成本。