Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/06—Ethanol, i.e. non-beverage
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
  • B01D3/001—Processes specially adapted for distillation or rectification of fermented solutions
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E50/00—Technologies for the production of fuel of non-fossil origin
  • Y02E50/10—Biofuels, e.g. bio-diesel
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S435/00—Chemistry: molecular biology and microbiology
  • Y10S435/8215—Microorganisms
  • Y10S435/911—Microorganisms using fungi

Definitions

• the present invention relates to a process for the production of ethanol through fermentation of a carbohydrate containing substrate in a fermentor during continuous discharge of a stream of fermentation liquor from the fermentor, which stream is separated in a centrifugal separation step into a yeast enriched stream, which is recirculated to the fermentor, and an essentially yeast-free stream, which in a primary distillation step is separated into an ethanol enriched top stream and a residual liquid bottom stream, of which a part is recirculated to the fermentor and the residual part is supplied to a secondary distillation step for stripping off remaining ethanol to form a concentrated stillage impoverished in ethanol.
• one essential advantage of the process is the low water input and the low energy costs associated therewith for evaporation of the stillage obtained as by-product.
• a stillage with a maximum dry substance content (DS) of non-fermentable material of about 10 % by weight can be achieved, while in said continuous recirculation process normally a DS-content in the range of 22-25 % by weight is reached in the stillage from the secondary distillation step, the DS-content in the fermentor being in the order of 15 % by weight.
• DS dry substance content
• a further increase of the DS-content of the final stillage and thereby a further reduction of the evaporation energy required could be achieved by simply further reducing the water input to the process and increasing the fraction of the intermediate stillage recirculated from the primary distillation step.
• the minimal required water input is settled by two essentially different criteria.
• One criterium emanates from the fact that a certain part of the non-fermentable substance contained in the raw material, the concentration of which increases with reduced water input to the fermentor, consists of osmosis forming dissolved salts and molecularly dissolved substances.
• Increasing concentration of osmosis forming substances in the fermentation liquor leads to a condition, at which the yeast growth rate is less than the rate with which the living yeast cells are killed off.
• the total ethanol productivity decreases due to reduced number of active yeast cells and also due to decreasing ethanol productivity of still active yeast cells.
• the second criterium which can be dimensioning for the water input, is set by the flow condition of the system.
• the minimum water input limit is generally not set by the content of solsuble substances but by the maximum content of insoluble substances for achieving the required fluidity in the system.
• the fluidity conditions allow such a low water input that the fermentation almost completely stops due to a too high concentration of osmosis forming substances in the fermentor.
• the object of the present invention is to modify the process for ethanol fermentation of the introductively mentioned kind so that a further, in dry substance concentrated stillage is obtained from the secondary distillation step.
• This object has been reached in the process for ethanol fermentation on beet or cane sugar molasses and is primarily characterized in that the process water input is controlled, for example by controlling the concentration of the supplied molasses substrate, so that during a first period of time, the concentration of non-fermentable substance in the fermentor, calculated as water-free substance (DS) increases from a start value in the range 5-15 % by weight DS to a value in the range 20-30 % by weight DS , in which the range the ethanol productivity of the yeast is decreasing, whereafter the continuous fermentation and distillation with recirculation of said bottom stream is continued at last said high concentration of non-fermentable substance in the fermentor during a second period of time, so that the average concentration of non-fermentable substance in the fermentor during said two periods of time exceeds 20 % by weight DS.
• DS water-free substance
• beet and cane sugar molasses refers in this application to different sugar containing by-fractions obtained in recovering sugar from sugar canes and sugar beets.
• the present process is also characterized by the outstanding short residence time of 4-10 hours for the fermentation liquor in the fermentor, i.e. the average time before the liquor reaches the primary distillation step and is heated to about 80-100° C before a major part of it is returned in pasteurized condition to the fermentor.
• This contributes to a very low infection risk in the system.
• the infection risk is further reduced in the present process by the fact that the concentration of non-fermentable material and thereby the concentration of osmosis forming dissolved substances in the fermentor becomes higher than at any other known process giving a still more unfavourable environment for bacteria growth in the fermentor.
• the fermentation is carried out in two alternating fermentors, which are started up and emptied with such a time-lag so that one fermentor is connected to the primary distillation step when the other fermentor is disconnected.
• A. fermentor disconnected after a finished fermentation cycle contains an amount of fermentation liquor, which corresponds to the stream of intermediate stillage (i.e.
• the disconnected fermentor is suitably emptied by feeding its fermentation liquor to the secondary distillation step during an extended time, for example 80 hours, which increases the supply stream to the same, in this case with about 30 %.
• the fermentor is suitably dimensioned so that the desired ethanol production can be achieved also in the end of the operation period when the ethanol productivity of the yeast is the lowest.
• the maximum production capacity is not utilized during the first part of the operation period, during which the ethanol production is limited by the supply of fermentable sugar to the fermentor.
• One advantage of underdimensioning the feed of fermentable substance with respect to the maximum fermentation capacity is a somewhat further reduction of the constant low concentration of fermentable substance in the fermentor and the corresponding yield improvement due to reduced losses of fermentable material in the stillage.
• the process according to the present invention can of course be carried out so that a decreasing ethanol production is obtained during the operation period of the fermentor.
• a very interesting aspect of the present invention resides in the possibility of achieving constant ethanol flow through the primary distillation step during unlimited time and without buffer tanks by means of only two alternating fermentors while, compared with corresponding recirculation process with only one fermentor connected during longer time, a much more concentrated stillage is obtained from the secondary distillation step, the energy supply thereto being the same.
• unbroken flow lines refer to a continuous circuit with a fermentor FI connected to a primary distillation step PD. From a substrate preparation step (not shown) a molasses substrate is fed through line 1, valve 2 and line 3 to fermentor FI.
• the dotted flow lines illustrate the connection to the primary distillation step PD of a further, with fermentor FI alternating fermentor FII just by switching valves so that fermentor FI simultaneously is disconnected from the circuit. Therefore, the same reference figures have been used for the lines corresponding to the above stated lines for fermentor FI with the addition of the letter a. Further dotted flow lines are also drawn to show how a fermentor taken out of operation can be emptied by charging its fermentation liquor tc the secondary distillation step SD.
• the fermentor FII is connected to the continuous circuit by switching valves 6, 6a, 9, 2 and 15, while fermentor FI is disconnected thereby to be emptied from its fermentation liquor through lines 21 and 22 to the secondary distillation step SD.
• the example refers to continuous fermentation during a longer period of time (250 hours) in a fermentor under steady-state condition.
• a fermentor with a total liquid volume of 10 m 3 was charged with 0,7 m 3 prepropagated yeast culture of yeast species
• the fermentor was filled to a liquid volume of 7 m 3 .
• the filled fermentor was connected to the primary distillation step PD in a distillation plant, described above.
• 650 kg/h cane sugar molasses with a concentration of fermentable sugar (F) of 19,4 % by weight and a concentration of non-fermentable material (NF) of 15,5 % by weight.
• the recirculation ratio was controlled so that steady-state was maintained in the system.
• the recirculation ratio was 0,57, i.e. 57 % of the bottom stream discharged from the primary distillation step PD was recirculated to the fermentor. After continuous fermentation during 250 hours the following stream compositions were determined:
• the fermentor was filled during 20 hours with the same molasses substrate and the same yeast culture as used in example 1, however this time up to a liquid volume of about 10 m 3 .
• the fermentor was then connected to the same distillation equipment as used in example 1. 460 kg/h of the same cane sugar molasses as used in example 1, however now having a concentration of 30,2 % by weight fermentable sugar and a NF-content of 24,1 % by weight, was continuously fed to the fermentor. The water content of the substrate was thus reduced to 46 % by weight compared with 65 % by weight in the steady-state run according to example 1. The ratio recirculated intermediate stillage from the primary distillation step was raised to 73 %. Continuous supply of fermentation liquor from the fermentor to the primary distillation step, continuous recirculation of a part of the intermediate stillage from the primary distillation step and final stripping of the residual part of the intermediate stillage were maintained during 120 hours.
• NF non-fermentable substance
• the average values for the NF-content in the fermentor and in the discharged stillage were calculated, being 22,3 % by weight and 39,3 % by weight, respectively.
• the average production of ethanol was 63 kg/h, from which the ethanol productivity in the fermentor filled to 10 m 3 is calculated to about 6,3 kg/m 3 /h.
• the bacteria values stated in table 2 indicate a clear reduction of the amount of living bacteria when a concentration of non-fermentable material in the fermentor is in the order of 20 % by weight DS or higher.

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• Chemical & Material Sciences (AREA)
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• Engineering & Computer Science (AREA)
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• Bioinformatics & Cheminformatics (AREA)
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• General Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Biochemistry (AREA)
• Biotechnology (AREA)
• General Engineering & Computer Science (AREA)
• General Health & Medical Sciences (AREA)
• Genetics & Genomics (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)
• Apparatus Associated With Microorganisms And Enzymes (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
• Steroid Compounds (AREA)
• Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)
• Compounds Of Unknown Constitution (AREA)
• Peptides Or Proteins (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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• 1986
  • 1986-01-31 SE SE8600429A patent/SE450897B/sv not_active IP Right Cessation
  • 1986-10-30 AT AT86906971T patent/ATE70087T1/de not_active IP Right Cessation
  • 1986-10-30 DE DE8686906971T patent/DE3682781D1/de not_active Expired - Fee Related
  • 1986-10-30 JP JP61505965A patent/JPH01502155A/ja active Pending
  • 1986-10-30 US US07/209,476 patent/US4886751A/en not_active Expired - Fee Related
  • 1986-10-30 AU AU65954/86A patent/AU591736B2/en not_active Ceased
  • 1986-10-30 HU HU865440A patent/HU201971B/hu unknown
  • 1986-10-30 EP EP86906971A patent/EP0291503B1/en not_active Expired - Lifetime
  • 1986-10-30 BR BR8607244A patent/BR8607244A/pt unknown
  • 1986-10-30 WO PCT/SE1986/000498 patent/WO1987004724A1/en active IP Right Grant
• 1987
  • 1987-01-20 IN IN60/CAL/87A patent/IN166750B/en unknown
  • 1987-01-21 PH PH34746A patent/PH22961A/en unknown
  • 1987-09-29 DK DK511487A patent/DK158272C/da not_active IP Right Cessation
  • 1987-09-29 KR KR1019870700881A patent/KR880700857A/ko not_active Application Discontinuation
• 1988
  • 1988-07-29 FI FI883587A patent/FI883587A/fi not_active IP Right Cessation

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