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  • 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
  • C12P5/00—Preparation of hydrocarbons or halogenated hydrocarbons
  • C12P5/02—Preparation of hydrocarbons or halogenated hydrocarbons acyclic
  • C12P5/023—Methane
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  • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
  • C12M21/04—Bioreactors or fermenters specially adapted for specific uses for producing gas, e.g. biogas
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
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  • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
  • C12M21/12—Bioreactors or fermenters specially adapted for specific uses for producing fuels or solvents
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  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M43/00—Combinations of bioreactors or fermenters with other apparatus
  • C12M43/02—Bioreactors or fermenters combined with devices for liquid fuel extraction; Biorefineries
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M43/00—Combinations of bioreactors or fermenters with other apparatus
  • C12M43/08—Bioreactors or fermenters combined with devices or plants for production of electricity
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M45/00—Means for pre-treatment of biological substances
  • C12M45/02—Means for pre-treatment of biological substances by mechanical forces; Stirring; Trituration; Comminuting
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M45/00—Means for pre-treatment of biological substances
  • C12M45/20—Heating; Cooling
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M47/00—Means for after-treatment of the produced biomass or of the fermentation or metabolic products, e.g. storage of biomass
  • C12M47/12—Purification
• • 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
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B43/00—Engines characterised by operating on gaseous fuels; Plants including such engines
  • F02B43/10—Engines or plants characterised by use of other specific gases, e.g. acetylene, oxyhydrogen
  • F02B2043/103—Natural gas, e.g. methane or LNG used as a fuel
• • 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
  • 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
  • Y02E50/30—Fuel from waste, e.g. synthetic alcohol or diesel

Definitions

• sugar beets An alternative feedstock to sugarcane is sugar beets.
• Sugar beets can be grown successfully in a wide variety of climates ranging from the warm areas of California's imperial valley to the much cooler climate of North Dakota, thus making it possible to locate an ethanol production facility in virtually any part of the country in close proximity to its feedstock source and avoid the prohibitive expense of transporting feedstock materials over long distances.
• sugar beets also require less water for their cultivation and produce higher yields of feedstock material per acre thus lessening the burden on land and water resources.
• sugars extracted from sugar beets can be fermented directly to ethanol without the need of such treatment.
• Sugar beet strains grown for sugar production traditionally have been selected for maximum sucrose yield without regard to their content of other sugars.
• the use of sugar beets for ethanol production is not subject to such constraints. Instead, ethanol production can make use of so-called "energy beet" strains which produce higher total fermentable sugar yields. This further enhances the efficiency and cost-effectiveness of producing ethanol from sugar beets.
• Another object of the invention is to provide a process and apparatus for producing ethanol from sugar beets which requires less energy input than prior ethanol production processes.
• a further object of the invention is to provide a process and apparatus for producing ethanol from sugar beets which poses a minimal burden on the environment.
• Yet another object of the invention is to provide a process and apparatus for producing ethanol from sugar beets which is net-energy neutral or near net-energy neutral.
• An additional object of the invention is to provide a process and apparatus for producing ethanol from sugar beets which can operate after start-up using only the water content of the beets without additional supplies of water.
• a still further object of the invention is to provide a process and apparatus for producing ethanol from sugar beets which is readily scalable to produce modest or large amounts of ethanol to meet existing demand.
• a process for producing ethanol comprising subjecting sugar beets to size reduction and pressing to obtain a sugar-containing juice and a residual beet pulp; pasteurizing the sugar-containing juice; fermenting the pasteurized juice with yeast to obtain an ethanol-containing fermentate; separating the yeast from the fermentate; recovering substantially pure ethanol from the fermentate; anaerobically digesting the residual beet pulp to produce methane, and combusting the methane to obtain energy.
• an apparatus for producing ethanol from sugar beets comprising a size reducing apparatus for reducing the sugar beets to small particles; at least one press for pressing sugar-containing juice out of the ground beet particles; a pasteurizer for pasteurizing the sugar-containing juice; a heat exchanger for transferring heat from pasteurized juice discharged from the pasteurizer to incoming juice to be introduced into the pasteurizer; a fermenter for fermenting the pasteurized sugar-containing juice; a still for distilling an ethanol/water azeotrope from fermentate recovered from the fermenter; a membrane separator for separating substantially pure ethanol from the ethanol/water azeotrope from the still, and an anaerobic digester for digesting pulp from said at least one press to produce methane.
• FIG. 1 is a schematic diagram of an ethanol production installation in accordance with the present invention
• Fig. 2 is a partial schematic diagram of an alternate arrangement for extracting sucrose from sugar beets
• FIG. 3 is a side elevation view of an anaerobic digester for converting waste pulp to methane
• Fig. 4 is a plan view of the anaerobic digester of Fig. 3. DETAILED DESCRIPTION
• the production of ethanol commences with the cultivation of so-called "energy beets", which have been selected for maximum production of fermentable sugars.
• the germ plasm for such beets is available from commercial seed vendors such as Syngenta Seeds, Inc. of Longmont, Colorado.
• the beets preferably are washed in the field utilizing a portable washing apparatus to reduce their tare weight.
• the portable washer preferably recycles the wash water to minimize water consumption. Tops from the beets may be left in the field as a soil enhancer. The washed and topped beets are then transported to the processing facility.
• the beets are comminuted or ground to fine particles for further processing.
• This size reduction may advantageously be achieved with a conventional hammer mill.
• Other types of size reducing or grinding apparatus might also be used.
• the resulting particle size should be sufficiently small to maximize release of sugars from the beet pulp, but not so small that it becomes difficult to separate the pulp particles from the sugar- containing juice.
• the particle size will be less than about 15 mm, more preferably less than 10 mm.
• the beet particles are pressed in a screw press to release the sugar-containing juice from the residual pulp.
• the pulp is subjected to one or more additional pressing operations to recover additional sugar-containing juice, which is combined with the juice from the initial pressing stage.
• Pulp from the pressing stage or stages is stored for later use as described hereinafter. It is preferred to store the pulp under anaerobic conditions to prevent deterioration prior to later use.
• the pressed juice is then centrifuged to remove any solids. If desired, an optional filtration may be performed prior to centrifugation to reduce the load on the centrifuge. Solids recovered from the centrifuge are a valuable by-product useful as a potting soil.
• the sugar-containing juice is then pasteurized by heating it briefly to a temperature of 85°C.
• hot juice being discharged from the pasteurizer is passed through a heat exchanger in heat exchange relation with the incoming juice being supplied to the pasturizer, so that most of its heat is transferred to the incoming juice, and minimal additional energy is required to heat the incoming juice to the pasteurization temperature.
• the juice leaves the pasteurizer at a temperature which is suitable for the introduction of the yeast, typically approximately 32 to 35°C. As a result, it is not necessary to add heat to the juice in the fermenter, which further improves the energy efficiency of the overall process.
• the introduction of the juice into the fermenter at a temperature of approximately 32° C means that the yeast can be introduced immediately into the fermenter to start fermentation instead of having to delay introduction of the yeast until the juice reaches the proper temperature. Consequently, the process of the invention can complete the fermentation in about 48 hours or less, compared to conventional commercial scale production processes which can take up to 90 hours.
• the pasteurized sugar-containing juice is fermented in the fermenter with yeast to produce ethanol.
• yeasts for alcohol production are known to persons skilled in the art, e.g. from the genus Saccharomyces such as Saccharomyces cerevisiae.
• a nitrogen source such as urea may also be introduced into the fermenter to provide essential nitrogen for the yeast used to effect fermentation.
• the fermentable sugar-containing juice introduced into the fermenter typically will have an initial sugar content of approximately 18 to 22 Brix.
• the natural sugar content of the juice may be boosted by the addition of supplemental raw sugar and/or molasses feedstock.
• periodic additions of supplemental feedstock having a sugar content of about 30 Brix may be made to maintain the fermentable sugar level at at least about 5 Brix, preferably about 15 Brix, for at least the first 24 hours, preferably approximately 30 hours, of the fermentation.
• the yeast may be activated by preconditioning it for three to six hours prior to introduction into the fermenter. Fermentation is continued for a total of 36 to 72 hours, preferably less than 48 hours, or until no more ethanol is being produced.
• Batch fermentations are preferred to facilitate periodic cleaning of the fermenter in order to prevent accumulation of contaminating microorganisms which would compete with the yeast for the sugar feedstock but not produce ethanol.
• the fermentation equipment advantageously may be sterilized using a cleaning agent such as a peroxyacetic acid/hydrogen peroxide solution.
• Liquid fermentate from the completed fermentation is then centrifuged to remove yeast solids. A portion of the separated yeast can be recycled though a return line back to be used in the next fermentation. Excess yeast is useful as a fertilizer and/or soil conditioner byproduct.
• Liquid supernatant from the centrifuge is then distilled to separate a 95% ethanol/5% water azeotrope from the fermentation residue or stillage.
• the 95% ethanol is then subjected to a membrane separation dewatering step to separate essentially pure ethanol from the residual water.
• Suitable separation membranes are commercially available, for example, from Whitefox Technologies of Calgary, Canada. The use of combined distillation and membrane separation stages facilitates a high degree of energy efficiency and enables ethanol to be produced at a net energy approaching as low as 8000 btu per gallon.
• the relatively high approximately 75% water content of sugar beets can be used as a source of process water for the ethanol production process, thus further lessening the water demand.
• the overall process can also become substantially water neutral.
• Residues from the anaerobic digestion contain significant amounts of potassium, nitrogen and phosphorous soil nutrients and can be used as a natural fertilizer by-product and/or as a soil conditioner.
• the natural fertilizer and soil conditioner by-products of the process can be utilized locally for growing the next crop of sugar beets, thereby reducing or eliminating the requirement for bringing in chemical fertilizers.
• the overall process is thus extremely energy efficient and results in a minimal environmental burden.
• washing device 2 is a portable apparatus which can be taken to the field so that the beets can be washed before transport.
• washing device 2 will include a recirculation system 3 for recirculating the wash water to minimize water consumption and the water disposal burden.
• the topped and washed beets are then transported to a size reduction station 4, which may be comprised of a plurality of hammer mills or other suitable comminuting apparatus for reducing the beets to small particles, preferably less than about 15 mm, more preferably less than about 10 mm, in size.
• the ground beets are then conveyed to a press, such as a screw press, where they are pressed to extract sugar-containing juice.
• the apparatus may comprise one or more additional presses 5' so that the pulp recovered from the initial press may be subjected to additional pressing.
• the beets will be subjected to at least two or three pressing stages in order to extract as much sugar-containing juice as possible from the beet pulp.
• the pressed beet pulp is then conveyed to a storage station 6 where it can be stored, preferably under anaerobic conditions, for later use.
• stored pulp is transferred to a washing station 10 where it is washed with a controlled amount of water to recover any soluble fermentable sugars remaining with the pulp.
• Washed pulp from washing station 10 is then passed to an anaerobic digester 7, where it is digested to produce combustible methane gas.
• the methane is collected in a suitable vessel 8 and ultimately may be used to provide energy for the ethanol production process, e.g. by driving a methane fueled electric generator 9 or for producing steam.
• sugar-containing juice from the press or presses and the washing station is combined and conveyed to a pasteurizer 14.
• the sugar-containing juice Prior to introduction into pasteurizer 14, the sugar-containing juice may be passed through a centrifuge 12 to remove any residual solids. If desired, an optional filter 11 may be interposed upstream of centrifuge 12 to reduce the solids load on the centrifuge.
• the sugar-containing juice is also passed through a heat exchanger 13 before being introduced into pasteurizer 14 in heat exchange relation with hot sugar-containing juice being discharged from the pasteurizer to reduce the heat requirement of the pasteurizer and also to cool the pasteurized juice to a temperature which will not inactivate the subsequently added yeast.
• Pasteurized sugar-containing juice is then introduced together with yeast from a yeast source 15 into a fermenter 16, where it is fermented to produce an ethanol-containing liquid.
• the yeast source may be provided with a preconditioning tank 17 where the yeast can be pretreated so that it is fully active when introduced into fermenter 16.
• Fermenter 16 may also be provided with a nitrogen source, such as urea source 18, to assure sufficient essential nitrogen is available to the yeast.
• fermenter 16 may be provided with an oxygen or air source 19 for introducing oxygen to assure that a proper aerobic condition for the desired fermentation is maintained in the fermenter.
• Fermenter 16 may also be connected with a supplemental source 20 of a fermentable feedstock, such as raw sugar or molasses, to maintain optimum fermentation conditions in the fermenter.
• fermenter 16 discharges the fermented liquid fermentate into a centrifuge 21, which separates any solids, primarily yeast, from the ethanol- containing fermentate. If desired, a recirculation line 22 may be provided between centrifuge 21 and yeast source 15, so that some or all of the separated yeast may be recycled.
• the ethanol-containing fermentate passes from centrifuge 21 to a still 23, where an ethanol/water azeotrope 24 is distilled from the fermentate.
• the stillage residue from still 23 is substantially water and is conveyed away through line 25 for use as process water.
• the ethanol/water azeotrope is conducted to a membrane separator 26, where the ethanol and water are separated to obtain substantially pure ethanol 27. In test runs of the process of the invention it has been found possible to obtain an ethanol product which is 99.2% pure.
• the process and apparatus of the invention can achieve a net energy requirement of less than 9,000 btu/gallon.
• the process and apparatus of the invention are thus considerably more energy efficient than prior art commercial processes for production of ethanol (from corn), which typically require an energy input on the order of 12,000 btu/gallon.
• Fig. 2 shows an alternate arrangement for extracting sucrose and/or other fermentable sugars from sugar beets.
• pulp from the size reduction step which preferably is a hammer mill, is introduced through a feed line 29 into a first tank 30 together with juice from presses 5, 5' and thoroughly mixed.
• Residence time in mixing tank 30 may vary from about 5 to about 15 minutes, preferably about 8 minutes.
• the pulp/juice mixture then passes through a connecting line 31 to a macerator 32 and then to a heat exchanger 33 where they are heated to from 65 to 80° C, preferably from 70 to 75° C.
• the heated pulp mixture from heat exchanger 33 then passes through a connecting line 34 to a second mixing tank 35, where it is further mixed and digested, whereby the cell walls are denatured.
• the processed pulp thence passes through line 36 back to the presses 5, 5'.
• Excess sugar- containing juice having a Brix of 14 or more is continuously removed from mixing tank 30 through connecting line 37 and pumped to centrifuge 12 for further processing in accordance with the scheme of Fig. 1.
• FIG. 3 is a side view of a preferred anaerobic digestion apparatus 38.
• Anaerobic digester 38 is comprised of a tank 39 filled with a grate of fixed, plastic film membranes 40.
• tank 39 The interior of tank 39 is maintained under anaerobic conditions, and a consortia of bacteria attach to the membranes 40 and grow as a fixed biofilm.
• a liquid suspension of pressed and washed beet pulp is introduced into tank 39 through inlet 41.
• the liquid level in tank 39 is such that the fixed, plastic film membranes are fully submersed in the liquid.
• a series of alternating internal baffles 42, 42' extending transversely across tank 39 form a serpentine pathway through the tank as indicated by arrows 43.
• the pulp flows along this serpentine pathway through the grate of film membranes 40 and then exits through a discharge outlet 44.
• the bacteria convert both soluble and particulate organic matter to methane.
• a small amount of carbon dioxide may also form.
• the resulting biogas product can be collected and used as a fuel or as a synthesis gas.
• the apparatus of the invention thus enables a more rapid throughput of pulp and yet has a smaller footprint and requires less space than conventional anaerobic digester systems consisting of large rectangular or circular concrete or steel tanks.

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• 2013
  • 2013-01-25 WO PCT/US2013/023252 patent/WO2013116113A1/fr not_active Ceased

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