System for recycling water to facilitate the production of ethanol

#The present application relates to a system that reduces water usage in the production of ethanol by recycling water. The present application also relates to a method of recycling water in an ethanol production process in a biorefinery. The present application further relates to a biorefinery employing a system that recycles water in the ethanol production process.

#Ethanol can be produced from grain-based feedstocks (e.g., corn, sorghum/milo, barley, wheat, soybeans, etc.), from sugar (e.g., sugar cane, sugar beets, etc.), or from biomass (e.g., lignocellulosic feedstocks, such as switchgrass, corn cobs and stover, wood, or other plant material).

#In a conventional ethanol plant, corn is used as a feedstock and ethanol is produced from starch contained within the corn. Corn kernels are cleaned and milled to prepare starch-containing material for processing. Corn kernels can also be fractionated to separate the starch-containing material (e.g., endosperm) from other matter (such as fiber and germ). The starch-containing material is slurried with water and liquefied to facilitate saccharification, where the starch is converted into sugar (e.g., glucose), and fermentation, where the sugar is converted by an ethanologen (e.g., yeast) into ethanol. The fermentation product is beer, which comprises a liquid component, including ethanol, water, and soluble components, and a solids component, including unfermented particulate matter (among other things). The fermentation product is sent to a distillation system where the fermentation product is distilled and dehydrated into ethanol. The residual matter (e.g., whole stillage) comprises water, soluble components, oil, and unfermented solids (e.g., the solids component of the beer with substantially all ethanol removed, which can be dried into dried distillers grains (DDG) and sold, for example, as an animal feed product). Other co-products (e.g., syrup and oil contained in the syrup), can also be recovered from the whole stillage. Water removed from the fermentation product in distillation can be treated for re-use at the plant.

#FIG. 1 is a perspective view of a biorefinery comprising a corn-based ethanol production facility.

#FIGS. 2A, 2B and 2C are schematic block diagrams of an ethanol production process.

#FIGS. 3A and 3B are schematic block diagrams of water filtration in an ethanol production facility.

#Referring to FIG. 1, a biorefinery 100 comprising an ethanol production facility configured to produce ethanol from corn is shown. The biorefinery 100A comprises an area 102 where corn is delivered and prepared to be supplied to the ethanol production facility. The ethanol production facility comprises apparatus 104A for preparation and treatment (e.g. milling) of the corn into corn flour suitable for fermentation into fermentation product in a fermentation system 104B. The ethanol production facility comprises a distillation system 104C in which the fermentation product is distilled and dehydrated into ethanol. As shown in FIG. 1A, the biorefinery 100 may also comprise a by-product treatment system (shown as comprising a centrifuge 106A, a dryer 106B and an evaporator 106C).

#Referring to FIGS. 2A and 2B, in an ethanol production process 200A and 200B, corn can be prepared for further treatment in a preparation system 202. As seen in FIG. 2B, the preparation system 202 may comprise a cleaning 202A or screening 202B step to remove foreign material, such as rocks, dirt, sand, pieces of corn cobs and stalk, and other unfermentable material. After cleaning/screening, the particle size of corn can be reduced by milling to facilitate further processing. The corn kernels may also be fractionated into starch-containing endosperm and fiber and germ. The milled corn or endosperm is slurried with water, enzymes and agents to facilitate the conversion of starch into sugar (e.g. glucose). The sugar is converted into ethanol by an ethanologen (e.g. yeast) in a fermentation system 204. The product of fermentation (i.e. fermentation product) is beer, which comprises a liquid component, including ethanol and water and soluble components, and a solids component, including unfermented particulate matter (among other things). The fermentation product is sent to a distillation system 206. In the distillation system, the fermentation product is distilled and dehydrated into ethanol. As shown in FIG. 2C, the removed components (e.g., whole stillage), which comprise water, soluble components, oil and unfermented solids (e.g., the solids component of the beer with substantially all ethanol removed), can be dried into dried distillers grains (DDG) and sold as an animal feed product. Other co-products, for example, syrup (and oil contained in the syrup), can also be recovered from the stillage. Water removed from the fermentation product in distillation can be treated for re-use at the plant.

#Referring to FIGS. 3A and 3B, water that is sourced from a water supply 302 (e.g., a municipal water system or a well) can be treated in a treatment system 210 to prepare it for use in an ethanol production process (for example, the ethanol production process 200A or 200B) or a steam generation system 304. The treatment system 210 can be used to reduce the level of contaminants (e.g., dissolved solids or suspended solids) that may be present in the water. The supply of water from the water supply 302 and treated water is balanced so that the soluble components in the water are maintained at a suitable level for the steam generation system 304, for the fermentation system 204 and for other plant systems.