SE432442B - PROCEDURE FOR PREPARING ETHANOL BY CONTINUOUS SPRAYING OF A CARBOHYDRATE-SUBSTRATE, WHICH AN ETHANOLANRICATED FLUID IS SEPARATED UNDER VACUUM BEFORE DISTRIBUTING THE VETERINARY WINE - Google Patents

Description

The object of the present invention is to provide a method of the kind mentioned in the introduction, at. which the capacity of the centrifugal separator used only needs to be relatively low, where the yeast is recycled without being damaged, and where one has great freedom of choice to choose suitable operating conditions for the extraction of ethanol by distillative method.

According to the invention, such a process is characterized in that fermentation liquid is fed directly to a simple evaporator unit, corresponding to one or a few distillation bottoms, in which vacuum is maintained, in which it is divided into a first ethanol-enriched meadow stream, which is fed to a plant for producing the desired ethanol grade, and _d_ç_l¿ in a first liquid, yeast-containing bottom stream, a portion of which is returned to the fermentor, while the remainder is centrifugally separated into at least one yeast concentrate stream, which is returned to the fermentor, and in a yeast-free flow, a stripping unit, in which dough is divided into a second, ethanol-enriched steam stream and dough into an ethanol-depleted second liquid bottom stream.

In a preferred embodiment of the method according to the invention, the second is applied to. ethanol enriched the vapor flow the simple evaporator unit, directly or as an indirect heat source. According to the procedure, the yeast is not exposed to any high temperature, while at the same time no high centrifugal separator capacity is required. The operating conditions for ethanol extraction can be selected optimally.

If the substrate has been made by enzymatic degradation of cellulose or starch raw material, it is an advantage that the simple evaporator unit operates at low pressure and thus low temperature, since the enzymes thereby. does not take damage, but can be recovered. The tendency to crust formation is also smaller in the simple evaporator unit as it is operated at low temperature.

In the following, the method according to the invention will be described in more detail with reference to the attached figure, which schematically shows a plant for carrying out the method.

In the figure, 1 denotes one (or more) fermenters, 2 a simple evaporator unit, corresponding to one or a few distillation bottoms, 3 a centrifugal separator and 4 a simple stripper unit. A plant for producing the desired ethanol grade is indicated by a condenser 5 and a distillation column 6. A line 7 connects the fementor 1 to the impurity unit 2, from which a bottom line 8 in turn suffers into two branches 9, 10 , of which. the branch 9 leads to the centrifugal separator 3 and the branch 10 to the balm to the femur 1. From the one-trimmed gallbladder 3 to a lead 11: mile than; the stripper unit 4 and a line 12 back to the mentor. In this case, the centrifugal separator is also provided with a sludge outlet 15. A line 14 connects the simple stripper unit 4 to the simple evaporator unit 2, from which in turn a connection 15 leads to the condenser 5. An inlet pipe 16 is intended to supply substrate to the fermenter, while an outlet pipe 17 'is intended to remove formed carbon dioxide. The simple evaporator unit 2 resp. the simple stripper unit 4 are provided with heater loops 16 resp. 19.

The plant operates as follows: Substrate is fed continuously through the inlet pipe 16, and a suitable yeast content is maintained in the fermenter 1. Fermentation liquid including yeast is continuously withdrawn through line 7 and evaporated at relatively low temperature under vacuum in the single. evaporator unit 2. The bottom stream exits through line 8 and is distributed so that a portion returns to the fermenter through line 10 and the remaining portion is fed to the centrifugal separator 3 through line 9. In the cenophageal separator 3 the incoming stream is divided into a yeast concentrate stream, which returns to the mentor 1 through the line 12, a yeast-free flow, which is supplied to the simple. the stripper unit through the line 11 and an intermittent sludge flow, consisting of dead yeast cell substance etc., which is diverted through the line 15. The ethanol-enriched meadow flow from the simple stripper unit 4 is led through the line 14 to the simple evaporator unit 2 and contributes to the friend supply to this device. Steam. is supplied as needed through the heating loop 18 as well as through the heating loop 19. which heats the simple stripper unit 4. The combined ethanol azarilcade vapor stream from the simple evaporator unit 2 departs through line 15 to condensate 5 and is then fed to the distillation column 6 to produce the desired ethanol grade.

The following operating data may be mentioned as an example of operation of a plant for carrying out the process according to the invention: hail Reed sock molasses of strength 40 ° Bx is continuously dosed through the inlet 16 of the fermenter 1 In the fermenter a yeast concentration of 2.5 weight

Claims (2)

7905916-8 4 by recirktzlation. Under these operating conditions, a residence time of approximately 6 hours is required to achieve almost complete leveling. A flow of the fermentation broth, containing about 0.1% by weight of unfermented sugar and about 5% by weight of ethanol, is continuously pumped over to the simple evaporator unit 2, in which a pressure of 50 mm Hg is maintained. The boiled yeast boils. the mash at 3500 and steam, containing 30-35% by weight of ethanol is discharged and condensed in the condenser 5. The diluted ethanol is concentrated and further purified in the distillation column 6. The bottom stream from the single evaporator unit 2 divides into two streams, so that about 80% returned to the fermenter 1 and 7: centrifuged in the centrifugal separator 5, which operates at a high speed. The yeast concentrate is pumped back to the fermenter 1 through the line 12, while the yeast-free flow is evaporated in the simple stripper unit 4, which is designed as a relatively short column. The ethanol-enriched steam from the stripper unit 4 is either led directly into the simple evaporator unit 2 or used for indirect heating thereof, whereby the energy losses can be minimized. The sewage flow from the simple stripper unit 4 contains about 55% soluble dry matter and can easily be further treated, for example in a braking furnace. Pat entki-av A process for the production of ethanol by continuous fermentation of a carbonate-containing substrate in one or more fermenters, wherein a yeast-containing stream is divided by centrifugal separation into a yeast concentrate stream and a yeast-free stream, characterized by simply pre-fermenting a liquid directly. evaporator unit, corresponding to one or a few distillation bottoms, in which vacuum is maintained, in which it is divided gl; in a first, ethanol-enriched steam stream, which is fed to a plant for the production of the desired ethanol grade, and partly in a first liquid-yeast-containing bottom stream, a portion of which is returned to the fermenter, while the remaining part is divided by centrifugal separation into a yeast concentrate stream, which is returned to the fermentor and in a yeast-free flow, possibly in a slurry stream, the yeast-free stream being fed to a stripping unit in which it is divided into a second, ethanol-enriched steam stream and partly in a liquid dehydrated bottom flow. 2. A method according to claim 1, characterized in that the second, ethanol-enriched steam stream is fed to the simple evaporator unit.