EP0038359A1 - Procede de fabrication d'alcool - Google Patents

Procede de fabrication d'alcool

Info

Publication number
EP0038359A1
EP0038359A1 EP80902322A EP80902322A EP0038359A1 EP 0038359 A1 EP0038359 A1 EP 0038359A1 EP 80902322 A EP80902322 A EP 80902322A EP 80902322 A EP80902322 A EP 80902322A EP 0038359 A1 EP0038359 A1 EP 0038359A1
Authority
EP
European Patent Office
Prior art keywords
solution
cellulosic material
alcohol
psi
hemicellulose
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
EP80902322A
Other languages
German (de)
English (en)
Other versions
EP0038359A4 (fr
Inventor
Alan M. Neves
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Biomass International Inc
Original Assignee
Biomass International Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US06/195,326 external-priority patent/US4425433A/en
Application filed by Biomass International Inc filed Critical Biomass International Inc
Publication of EP0038359A1 publication Critical patent/EP0038359A1/fr
Publication of EP0038359A4 publication Critical patent/EP0038359A4/fr
Ceased legal-status Critical Current

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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
    • C12P7/08—Ethanol, i.e. non-beverage produced as by-product or from waste or cellulosic material substrate
    • C12P7/10—Ethanol, i.e. non-beverage produced as by-product or from waste or cellulosic material substrate substrate containing cellulosic material
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

  • the present invention relates to the manufacture of alcohol. More particularly, it relates to a process for the continuous production of ethanol.
  • yeast is added to a solution of simple sugars.
  • Yeast is a small micro ⁇ organism which uses the sugar in the solution as food, and in doing so, expels ethanol and carbon dioxide as byproducts.
  • the carbon dioxide comes off as a gas, bubbling up through the liquid, and the ethanol stays in solution.
  • the yeast stagnate when the concentration of the ethanol in solution approaches about 18 percent by volume, whether or not there are still fermentable sugars present.
  • the sugars used in such traditional fermentation processes had typically contained from about 6 percent to 20 percent of the larger, complex sugars (such as dextrins and dextrose) which take a much longer time to undergo fermentation, if they will undergo fer- mentation, than do the simple hexose sugars (such as glucose and fructose).
  • complex sugars such as dextrins and dextrose
  • simple hexose sugars such as glucose and fructose
  • malt enzymes which aid in the hydrolysis of starches and conversion of the higher complex dextrin and dextrose sugars which are present in the sugar solutions of the prior art fermentation processes. While such malt enzymes add a desirable flavor to ethanol produced for human consumption, the
  • OMPI malt enzymes do nothing to make ethanol a more advanta ⁇ geous liquid fuel substitute and, in fact, could create problems for such a use.
  • sugars used in the fermentation process is important to the efficiency of production and the yield of ethanol. It is highly desirable that sugars used in the fermenta ⁇ tion process preferably be the simple hexose sugars so that the fermentation period is minimized and as much as possible of the sugar can be utilized in the fermentation process, thereby resulting in a higher yield of ethanol.
  • the present invention is directed to a continuous method of manufacturing alcohol, preferably ethanol, which is suitable for use as a liquid fuel, from cellu ⁇ lose-containing materials.
  • the process of the present invention preferably begins with cellulose-containing materials, including materials which are typically considered as wastes.
  • the cellulosic materials are prepared by chopping, grinding, and/or milling processes which reduce the cellulosic material to a powdered feedstock.
  • This feedstock undergoes a delignification process which separates the three major components of the cellu- losic source materials: cellulose, hemicellulose, and lignin.
  • the feedstock is mixed with a dilute acid solution and heated to an elevated temperature at a slight pressure for a short period of time. After the acid is neutralized, easily digestible starches and sugars and the hemicellulose remain in solution, while the lignin and cellulose are filtrable solids. The hemicellulose solution is ready to be hydrolyzed to simple sugars.
  • OMPI there are alternative processes for separating the lignin and cellulose solids.
  • the lignin and cellulose solids are mixed with a moderate concentration of cadoxen (a highly basic solvent) and then heated to an elevated temperature and a slight pressure for a relatively short period of time.
  • the lignin and cellulose solids are chilled and reacted with a chilled, highly concentrated acid for a relatively short period of time.
  • the resultant solution contains the cellulose, while the lignin remains as filtrable solids.
  • the cellulose When the cadoxen process is used, the cellulose is precipitated as a soft floe by cooling and aqueous dilution; when the acid process is used, the cellulose is precipitated as a soft floe by the addition of methanol.
  • the soft floe cellulose and the previously separated hemicellulose solution are combined prior to hydrolyzation.
  • the lignin and cellulose solids are heated under high pressure in the presence of steam to a temperature in excess of about 480°F for a short period of time. The solids are then ejected into a flash chamber which is maintained at about atmospheric pressure. The resulting material is combined with the previously separated hemicellulose solution prior to hydrolyzation.
  • the hydrolyzation process is conducted in a relatively dilute acid solution at an elevated temperature under pressure for a short period.
  • the subsequently obtained solution is neutralized to a pH of about 4.5 to 5.0, and the lignin solids are separated.
  • the resultant slurry or "wort" contains essentially only simple hexose sugars, as opposed to the larger complex sugars.
  • yeast nutrients are added.
  • the wort is then pumped into a continuous fermentation vessel where it can be almost completely fermented in a period as short as about 3 to 6 hours -- a period significantly less than the prior art processes requiring 72 hours.
  • the present invention also includes alternative methods for fermenting the wort to ethanol and then purifying the ethanol.
  • the liquid in the top of the fermentation vessel which contains a high concentration of ethanol, is allowed to enter a secondary fermentation tank where fermentation continues for a few more hours in order to convert essentially all of the sugars to ethanol.
  • the resultant solution called "wash”, is heated to a high temperature and then distilled under low pressure. This high temperature, low pressure distillation results in a high degree of separation of the ethanol in only a single distillation.
  • the resultant ethanol distillate can then undergo final processing where it may be dehydrated, denatured, stored, and/or blended with other components into a motor fuel.
  • carbon dioxide which is a signifi ⁇ cant byproduct of the fermentation process
  • the carbon dioxide By pulling a vacuum on the top of the fermentation vessel, the carbon dioxide will carry the ethanol from the fermentation solution.
  • the ethanol can be easily obtained by cooling the carbon dioxide-ethanol vapor and collecting the ethanol condensate. The ethanol can then be finally processed.
  • a still further alternative method uses the sparging carbon dioxide technique to remove ethanol from the fermentation vessel under reduced pressure and then the vaporized ethanol is put through a distillation tower under reduced pressure so that a legally anhydrous ethanol product is obtained without the use of complicated distillation techniques.
  • Figure 1 is a block diagram representation of the ethanol manufacturing process of the present invention.
  • Figure 2 is a schematic representation of an embodi ⁇ ment of that portion of the continuous manufacturing process of the present invention in which the cellulosic materials are converted into simple sugars in preparation for the fermentation process.
  • Figure 3 is a schematic representation of an embodi ⁇ ment of a portion of the continuous manufacturing process of the present invention in which the simple sugars are fermented to ethanol and carbon dioxide and each is processed into final products.
  • Figure 4 is a schematic representation of an alter ⁇ native embodiment of that portion of the continuous manu ⁇ facturing process of the present invention depicted in Figure 3.
  • Figure 5 is a schematic representation of an alternative embodiment of that portion of the continuous manufacturing process of the present invention depicted in Figure 2 in which the cellulosic materials are converted into simple sugars in preparation for the fermentation process.
  • Figure 6 is a schematic representation of an alternative embodiment of that portion of the continuous manufacturing process of the present invention depicted in Figures 3 and 4.
  • the present invention relates to a method of manu ⁇ facturing alcohol in a continuous manufacturing process which uses cellulose-containing wastes as the starting materials. It has been found that cellulosic materials often considered as wastes can be utilized in the ethanol manufacturing process of the present invention to produce ethanol in a better yield and at a significantly reduced cost, as compared with the prior art processes. It will be recognized that any starch-containing material (such as barley, corn, rice, wheat, and other small grains) in which the starch can be readily converted to simple sugars, as well as any sugar-containing material (such as sugar beets or sugar cane) may be used according to the disclosed process. Nevertheless, it is not necessary nor is it economically desirable to limit the use of the present invention to such expensive starch or sugar- containing materials.
  • any starch-containing material such as barley, corn, rice, wheat, and other small grains
  • any sugar-containing material such as sugar beets or sugar cane
  • cellulosic materials contain three major components: cellulose, hemicellulose, and lignin, in the approximate ratios of 4:3:3, respectively. How- - ever, these are only approximations; for example, softwood contains a typical ratio of 42:25:28, corncobs contain proportions of about 40:36:13 with an additional 8 percent simple sugars, whereas city garbage contains about 75 to 90 percent cellulose.
  • Cellulose is a homogenous polymer of anhydroglucose units linked together by 1,4-beta-glucosidic linkages, as compared to the 1,4 and 1,6 alpha-linkages of starch.
  • Hemicellulose is a mixture of simple or mixed polysaccharides, including polymers of pentoses (such as xylose and arabinose) , hexoses (such as mannose, galactose and glucose), and sugar acid.
  • Lignin is a branched polymer macromolecule having three-dimensional randomly linked polyphenolic units. The general aromatic character of lignin, as well as the prevelance of covalent carbon bonds, prevents reversion to monomers during processing lignin and cellulose from the "woody" fibrous cell walls of plants and is the cementing material between adjacent cell walls.
  • cellulose is strongly hydrolysis resistant because (1) cellulose is a highly ordered crystalline structure and (2) lignin physically surrounds and seals the cellulose.
  • the difficulty in using cellulose in the manufacturing of ethanol is the necessity to free the cellulose molecules from the lignin seal and the crystalline structure, but once this is done, the 1,4-beta-glucosidic linkages in cellulose are no more difficult to hydrolyze than the 1,4-alpha- glucosidic linkages in starch.
  • nearly any cellulose- containing material may be a starting material for the present invention, many materials heretofore considered only as wastes may be utilized. Recent statistics demon ⁇ strate the plentiful availability of such cellulosic waste resources, as compared to traditional petroleum and ethanol resources:
  • the cellulosic materials are sorted. This may be accomplished in any convenient manner.
  • Teledyne National Corporation markets a series of machines capable of various sorting, shreading, drying, and compressing operations which reduce the cellulosic material from the wastes to a pelletized form.
  • the pelletized cellulosic material can be easily ground to the necessary size.
  • the cellulosic starting materials 10 are subjected to chopping, grinding, and milling operations in order to reduce the starting materials to a workable size. These operations are generally designated as grinding process 12.
  • the feedstock has an average particle size of not greater than about 1/8 inch.
  • the feedstock should be small enough that when diluted, it will pass through about a 20 mesh screen. If readily hydrolyzable starch or sugar- containing materials, such as grains or sugar beets, are used, the average size of the feedstock materials need not be so small.
  • wet grinders such as represented as grinder 14 in Figure 2, have been found to be more efficient and to use less energy than dry grinders. Furthermore, the use of hot water (near its boiling point) has been found to aid the grinding process.
  • the resulting feedstock 16 is next subjected to ' a delignification process 20 in which the three major components of the feedstock (cellulose, hemicellulose, and lignin) are separated.
  • the hemicellulose along with the easily digestable starches and sugars are removed.
  • Feedstock 16 is diluted with water, combined with dilute acid 22 and heated in cooking vessel 24 at an elevated temperature under slight pressure.
  • acid 22 which is preferably sulfuric acid, may be added in concentrations upwards of 20 percent by volume, concentrations in the range of about 0.5 percent to 2.0 percent have been found to be generally sufficient.
  • OMPI desirable to heat the feedstock at a temperature of about 200°F to 300°F at a pressure of about 5 psi to 50 psi for about 2 to 10 minutes under conditions of agitation.
  • the presently preferred conditions are a temperature of about 225°F at a pressure of about 15 psi for about 3 to 6 minutes.
  • neutralizer 28 may be added at 30 to the acidic feedstock solution as it is removed from cooking vessel 24 until a pH of about 4.0 to 6.0 is obtained. If the acidic feedstock is neutralized, the preferable neutralizers are sodium carbonate or sodium bicarbonate. Separator 32 filters the resultant solution (containing the readily digestible starches, sugars, and hemicellulose 34), from the solids (containing the cellulose and lignin) . Hemicellulose 34 is then ready for the acid hydrolysis process of cooking vessel 68, which is discussed in detail hereinafter. Hemicellulose 34 may be combined at 62 with the cellulose (after the cellulose has been delignified) prior to hydrolysis or it may be hydrolyzed and then fermented separately. Since the hemicellulose-containing solution is to be reacidified during the subsequent hydrolysis step and since neutralization is not generally necessary in order for the hemicellulose to dissolve into solution, it has been found that the neutralization step can generally be omitted.
  • the solids separated from the hemicellulose solution are next processed to separate the lignin from the cellulose.
  • This may be accomplished by alternative methods.
  • the solids are diluted with water and mixed at 36 with a cadoxen solvent 38 (ethylene diamine cation in an aqueous concentration of about 25 percent by volume) to an amount of about 10 percent to 20 percent by volume of water.
  • the resulting solution is pumped into cooking vessel 40, preferably designed so that the solution entering the vessel is instantaneously heated by jet heater 42.
  • the solution in cooking vessel 40 is heated to an elevated temperature of from about 150°F to 240°F and a pressure from about atmospheric pressure to about 15 psi for about 2 to 10 minutes under conditions of agitation.
  • Such conditions have been found to be sufficient to break up the lignin seal surrounding the cellulose and break down the high order cellulose structure such that the cellulose will dissolve into solution. It will be appreciated that a longer residency time or a higher temperature and pressure may be needed depending on the particular starting cellulosic material used, how lightly the cellulose is bonded by the lignin, or the size to which the cellulosic starting materials had been ground.
  • the presently preferred conditions are at a temperature of about 200°F at atmospheric pressure for about 3 to 6 minutes.
  • the undissolved solids containing mostly lignin 44 may be filtered from the cellulose-containing solution by separator 46.
  • lignin solids 44 may be dried, such as by vacuum dryer 48, and then used as a fuel for the heating plant 50, which supplies heat to the entire manufacturing operation. Recycling of the byproducts, such as using the lignin, can be a significant factor in the economic feasibility of the ethanol manufacturing process of the present invention. It will be appreciated that the lignin need not be separated from the cellulose solution at this point in the process since the lignin is not subject to degradation in the subsequent hydrolysis process. For example, in a given particular processing facility, it may be easier to accomplish this lignin separation after hydrolyzation of the cellulose; such a filtration could easily be accomplished after the mixture had been cooled in cooler 86. At this point in the process, the mixture would not be strongly acid nor would it be strongly basic. The presence of the strong acids or bases used in the delignification process can cause maintenance problems in separator 46.
  • the cellulose-containing cadoxen solution is then cooled in cooling vessel 54 and diluted with water. As solution 52 cools, the cellulose precipitates as a soft floe which can be filtered from the cadoxen solvent by separator 56. Cadoxen solvent 38 may then be recycled, as indicated in Figure 2.
  • This soft floe cellulose 58 must be quickly subjected to acid hydrolysis; otherwise, the soft floe will harden and become resistant to acid hydrolysis. That it is necessary to quickly hydrolyze the soft floe soon after it forms is a significant reason why those skilled in the prior art have not heretofore been able to use cellulosic starting materials in the batch processes of the prior art.
  • concentrated sulfuric acid may be used as an alternative to the cadoxen treatment for delignification of the cellulose.
  • sulfuric acid in concentrations of about 60 percent to 90 percent by weight, and preferably of about 72 percent to 75 percent, is added to the lignin and cellulose solids which are filtered from the hemicellulose solution by separator 32.
  • Other acids may be used.
  • hydrochloric acid in concentrations of about 30 percent to about 60 percent, preferably about 40 percent, has been found to effectively delignify the cellulosic material.
  • the solids and concentrated acid may be cooked at a temperature of from about 150°F to 240°F for about 2 to 10 minutes, (preferably at a temperature of about 200°F for a period of about 3 to 6 minutes).
  • the resultant solution is cooled and diluted with methanol, the cellulose will precipitate as a soft floe.
  • OMPI _ 30°F to 60°F (the preferable temperature is about 40°F to 50°F) and then allowing the reaction to proceed with vigorous agitation for about 1 to 10 minutes.
  • the high acid concentration at such cool temperatures is still capable of breaking down the lignin and cellulose structures and dissolving the cellulose.
  • the cool temperatures slow the degradation of the cellulose by minimizing the formation of hydrogen ion which would begin to hydrolyze the cellulose into cellibose which is not fermentable. Under these temperature conditions, most of the cellulose will dissolve in the concentrated acid.
  • the resultant acid solution when diluted with methanol, will yield a soft floe precipitate of cellulose 58.
  • cooking vessel 40 (shown in Figure 2) would be replaced by a cooling vessel in which the temperature of the reactants could be lowered to the desired temperature.
  • This cellulose precipitate 58 can be separated and hydrolyzed as if the cadoxen treatment were used.
  • the acid and methanol are preferably recycled.
  • cellulose 58 in the form of a soft floe
  • water for convenience in handling and mixed at 62 with hemicellulose 34.
  • This slurry is then mixed with acid 64, preferably sulfuric acid, to obtain a concentration by volume of water of about 0.5 percent to 10 percent. It has been found that this mixing is best accomplished in a continuous slurry mixing tank 66, so that there is a complete mixing of the components.
  • the slurry is heated in cooking vessel 68, preferably instantaneously by jet- heater 70, to a temperature of about 200°F to 400°F at a pressure of about 15 psi to 200 psi for a period of about 2 to 10 minutes. It will be appreciated that the temper- ature, pressure, and residency time are interdependent so
  • the hydrolyzed slurry is neutralized at 74 to a preferable pH of about 4.5 to 5.0; preferable neutralizers 72 are sodium carbonate and sodium bicarbonate.
  • This slightly acid slurry is properly called “wort,” represented as 76 in Figure 1, although colloquially it is referred to as “mash.”
  • the wort must be cooled to the fermentation temperature, which is preferably in the range of 88°F to 90°F. According to the continuous manufacturing process of the present invention, it is advantageous to cool the wort in a series of cooling processes 78, thereby minimizing the amount of energy necessary.
  • the temperature can be instantaneously lowered to about 260°F to 220°F. It is preferable to then add yeast nutrients 82 to the wort because at this tempera- ture, they are automatically sterilized and become com ⁇ pletely mixed with the wort. Heating the yeast nutrients and the wort to a temperature in excess of 200°F results in a significant advance over the prior art by preventing bacterial contamination of the fermentation vessels.
  • the wort may then be pumped into a vacuum flash cooler 84,
  • OMPI preferably a barometric condenser and ejector, where it is further cooled to a temperature of about 160°F to 120°F.
  • the wort is then pumped through cooler 86 where cooling water is added to bring the solution down to the fermentation temperature and the pH is adjusted to about 4.5 to 5.0. At this point, the wort is ready for fermentation process 90.
  • the lignin and cellulose solids are pumped into cellulose digester 240 which is maintained at a steam pressure of between about 600 and about 1500 psi (which, according to conventional steam tables, produces temperatures of about 480°F to about 600°F) for a period of about 3 to 30 minutes.
  • the preferred conditions are about 700 psi (corresponding to about 500°F) for about 10 to 15 minutes.
  • Pressures .of about 600 to 700 psi are required in order for the cells to become sufficiently hydrated to undergo the "popcorn popping" effect when the hydrated cells are subjected to atmospheric pressure.
  • the hydrated materials are then ejected into flash chamber 242 which is maintained near atmospheric pressure.
  • flash chamber 242 which is maintained near atmospheric pressure.
  • OMPI materials from a pressure of from about 600 psi to 1500 psi to atmospheric pressure results in disrupting of the lignin and exposing the cellulosic cell.
  • the "popcorn popper" process does not separate the lignin and cellulose, but merely exposes the cellulose so that it can be readily hydrolyzed.
  • the resultant slurry (as it leaves flash chamber 242) is combined at 244 with hemicellulose 34.
  • This slurry is then mixed with acid 246, preferably sulfuric acid, to a concentration of from about 0.5 to about 10 percent in continuous mixing tank 248, preferably about 0.5 percent.
  • acid 246, preferably sulfuric acid to a concentration of from about 0.5 to about 10 percent in continuous mixing tank 248, preferably about 0.5 percent.
  • the slurry is hydrolyzed in cooking vessel 250 under the same conditions discussed with respect to the hydrolysis in cooking vessel 68 of Figure 2.
  • the cellulose is easily hydrolyzed under such conditions while the lignin remains uneffected by the acid at the described pressures and temperatures.
  • the hydrolyzed slurry is cooled through discharge into flash cooler 252.
  • the slurry is then neutralized at 254 with neutralizer 256.
  • the sugars and are in solution, while the lignin, any undissolved cellulose, and other nonhydrolyzable components of the feedstock (such as plastic or other complex molecules which may be present in feedstocks such as garbage) are solids.
  • These solids can be easily separated at 258, dried, then utilized as previously described.
  • a convenient method of separating the solid from the fermentable sugars is the use of a vacuum filter belt which draws the solution from solids by use of a vacuum.
  • a distinct advantage of a vacuum filter belt is that it simultaneously sufficiently cools the solution prior to fermentation without the use of coolers 84 and 86 (shown in Figure 2). After yeast nutrients 260 are added to the sugar-containing solution (i.e., wort) and any minor changes in the temperature or pH of the solution is made, the solution is ready for fermentation.
  • yeast nutrients 260 are added to the sugar-containing solution (i.e., wort) and any minor changes in the temperature or pH of the solution is made, the solution is ready for fermentation.
  • the wort prepared from cellulosic materials according to the processes of the present invention contains a very high proportion of simple sugars that are readily fermentable. Hence, nearly all of the sugars are converted in the fermentation process. Furthermore, unlike prior art processes, there is no need to add malt enzymes to the wort in order to convert the dextrins into fermentable sugars.
  • the present invention includes three alternative methods by which the sugars of the wort are fermented to alcohol and the alcohol is purified. These alternative methods are illustrated in Figures 3, 4 and 6 and are hereinafter separately discussed.
  • the wort which has been cooled to about 88°F to 90°F, which has had the pH adjusted to about 4.5 to 5.0, and which has been diluted with water to a concentration of about 15 percent to 25 percent sugar by weight
  • the primary fermentation vessel 92 where it has a residency time of from about 6 hours to 11 hours, but preferably about 8 hours.
  • Vessel 92 is provided with agitator means 94 which is preferably equipped with means capable of maintaining the solution of the wort within the preferable fermentation temperature range.
  • yeast Periodically (such as at the beginning of each startup cycle), sufficient yeast (preferably brewers yeast), generally represented as 88 in Figure 1, is added to the primary fermentation vessel to bring the yeast cell count up to a concentration of about 100 million cells per milliliter in four hours. It has been found that under the conditions of the present invention, yeast is continuously propogated during the fermentation at a rate sufficient to maintain this optimum population. As the wort undergoes fermentation, ethanol and carbon dioxide are produced in relative percentages of about 51 percent to 49 percent, respectively. Unlike the batch system of the prior art where the carbon dioxide is allowed to escape into the atmosphere or merely collected for sale as a byproduct, it has been found advantageous to utilize this produced carbon dioxide, represented as 96, for conversion to other useful products, discussed hereinafter.
  • Primary fermentation vessel 92 preferably has a constant level overflow to a secondary fermentation vessel 98 for an additional fermentation residency time of about 2 hours to 5 hours, preferably about 3 hours.
  • advan ⁇ tageous to utilize such a secondary fermentation vessel as it aids in achieving nearly complete fermentation of the sugars in the wort.
  • Such an arrangement also allows any slower fermenting sugars to remain in the fermentation vessels for a longer time in order to complete the fermentation process.
  • Secondary fermentation vessel 98 is also provided with agitator and means 99 in order to maintain the proper fermentation temperature. Accordingly, the total fermentation time is approximately 8 to 15 hours, preferably about 11 hours.
  • the ethanol- containing wash is pumped to the distillation system, generally represented as 100, where it is heated in heater 102 which is located in the base of the distilla- tion tower 104.
  • heater 102 can economically raise the temperature of the wash to be distilled.
  • One of the unique features of the present invention is the high temperature, low pressure operation of the distillation tower.
  • vacuum pump 106 By placing vacuum pump 106 at the top of distillation tower 104, the pressure within the tower is reduced.
  • vacuum distillation has been utilized in the synthetic vitamin industry, such uses were at very low temperatures in order to protect the vitamins from degradation.
  • the temperature of the ethanol-containing wash will be above the boiling point of ethanol at the pressures in the distillation tower, which pressures are kept as low as possible, preferably about 2 psi to 10 psi.
  • This hybrid system of high temperature, low pressure allows for greater separation of the ethanol than conventional distillation towers or low-temperature vacuum distillation towers.
  • the effectiveness of any distillation tower is determined by its ability to make a rapid exchange of the components between the liquid and vapor phases, which is a function of the vapor-liquid interfacial area and the flow characteristics of the vapor.
  • the high temperature, low pressure system increases the velocity of the vapor traveling upward, thereby increasing the interphase transfer between liquid and vapor and resulting in an increased stripping action of the distillation tower.
  • the collision force is much greater than in conventional towers.
  • the vacuum changes the total pressure thereby making the separation easier because the relative volatility of the components of the solution is changed.
  • care must be taken so that the upward forces of the vacuum are not so great as to create a lift on the liquid droplets which is greater than the gravity forces on the droplets.
  • the ethanol- containing wash is pumped into the base of a distillation tower three feet in diameter and forty-eight feet high in which the lower section serves as a stripping section with about twenty perforated plates and the upper section as a rectifying column with about twenty-six bubble cap plates. Because of the reduced pressure under which the distillation is accomplished, a large cross-sectional area is preferred so that upward movement of the vapor is not inhibited by the expansion of the vapor caused by the reduced pressure. Otherwise, the capacity of the distillation tower is greatly reduced. Steam is sparged into the entering wash at about 3 psi thereby heating the solution to its boiling point. Accordingly, the ethanol is immediately vaporized upon entering the distillation tower.
  • O c ⁇ / Vacuum pump 106 reduces the pressure at the top of the distillation tower by preferably 20 psi to 30 psi. This results in a vapor rich in ethanol rapidly rising through the tower. As the vapor is drawn up the tower, it collides with droplets of water and ethanol which have condensed, resulting in a stripping action whereby the water is generally returned to the bottom of the distillation tower and the ethanol is generally drawn to the exit at the top of the tower. When the vapor exists at the top of the tower, it is easily condensed by cooling at 108.
  • a portion of distillate 110 is returned to the tower as reflux to increase the stripping action and to control the proof of- the distillate.
  • the remainder of the ethanol distillate is sent to final processing 112.
  • the concentration of the resulting ethanol product can be controlled. For instance, by allowing a larger portion of the distillate to return to the tower, the refluxing action is increased so that the distillate obtains a higher ethanol concentration. Concentrations of approximately 95 percent (190 proof) ethanol can be obtained. Should concentrations of only 140 or 150 proof be needed, such as in a blended ethanol-based fuel, a lesser amount of the distillate is returned to the tower.
  • the undistilled components or residues of the wash which remain in the bottom of the distillation tower can be continuously removed and dried, such as in vacuum dryer 114.
  • the dried residue can be used as a supplement to animal feeds or as a fertilizer.
  • the dried residue can be used .as fuel for heating plant or as a fertilizer.
  • This pressurized sparging of finely divided carbon dioxide through jet 194 into the fermentation vessel will carry a mixture of ethanol and water from the fermented solution in vapor form.
  • the preferred rate of carbon dioxide flow has been found to be about 0.01 cubic feet per minute to 0.5 cubic feet per minute per gallon of solution in the fermentation vessel.
  • the sparging carbon dioxide will, use the collision with the fermentation solution (like the plates in the distillation tower) to strip away the ethanol for which carbon dioxide has an affinity. It is preferable that the carbon dioxide sparge be finely divided and be spread out so as to make contact with nearly all of the wort in the fermentation vessel. This can be accomplished by using any suitable sparge head, preferably a carbon or aloxite sparge head. Although it is preferable to have a temperature control means 200 to maintain the temperature of the fermentation solution, it is not necessary to also have an agitator means because the sparging carbon dioxide will provide sufficient agitation.
  • the nonethanol portions of the fermented solution including the dead yeast cells are gradually removed from the fermentation vessel through overflow 212 at the top of fermentation vessel 192, dried (such as in vacuum dryer 214), and used as a supplement to animal feed, as a fuel, or as a fertilizer.
  • the ethanol is sent to final pro ⁇ cessing 112 where it may be dehydrated at 116 by benzene distillation or salt dehydration, may be denatured with methanol 120 or other approved formulas according to law, and/or may be stored.
  • the ethanol may also be blended at 117 with other components, generally represented as 118, to make an ethanol-based fuel, such as that disclosed in copending United States application serial No. 087,618 filed October 23, 1979.
  • the third method of the present invention by which the sugars are fermented to alcohol and the alcohol is purified is directed to removing the ethanol from the wort and distillating it to legally anhydrous purity.
  • the wort is pumped into primary fermentation vessel 262 where it has a residency time of between about 3 to 6 hours, but preferably about 4 hours. Even though the residency time is very short, as compared to prior art methods (and the other methods of the present invention), most of the sugars are completely fermented within that time period because, under the conditions outlined below, it is possible to maintain a population of up to 500 million yeast cells per milliliter.
  • the secondary fermentation vessel also serves as a recycling station because the dead yeast cells (which float) tend to migrate to the top of the vessel where they ultimately overflow into settling tank 268.
  • the live yeast cells become dormant with the diminishing food supply and sink to the bottom of vessel 266 where they are recycled at 270 to primary fermentation vessel 262.
  • the solids which are collected in settling tank 268 are separated by a screw press 272 and dried. These solids make an excellent livestock feed supplement because they consist of proteins, heavy weight sugars, and other organic compounds.
  • the ethanol vapor from fermentation vessels 262 and 264 is fed directly into distillation tower 274 in the vapor state.
  • the ethanol (which is still in a vaporized state) is in a minimum concentration of about 15 to 20 percent when it enters the distillation tower. This is significant when compared to typical distillation towers when the ethanol only comprises about 4 to 10 percent of the liquid solution entering the tower and where the ethanol must be vaporized from a liquid solution once it has entered the distillation tower. Because the ethanol concentration is much greater (in the present invention) as it enters the distillation tower, less separation on the part of the tower will be required.
  • Vacuum pump 280 draws a vacuum in the distillation tower of about 20 to 26 inches of mercury, preferably about 25 inches of mercury. This greatly reduced pressure allows for a much greater separation of the ethanol. Moreover, the reduced pressure reduces the ethanol and water azeotrope so that the resulting product is about 99.6 percent ethanol (as compared to being able to obtain 95% ethanol at atmospheric pressure) with only one pass through the distillation tower. The resulting ethanol thus meets the legal requirements of 99.3% for anhydrous ethanol without the need for expensive benzene distillation procedures or the like. It has been found that with the ethanol entering the distillation tower in a vapor state and a reduced pressure of about 25 inches of mercury, the temperature at the bottom of the tower is about 110°F and the temperature midway up the distillation tower is about 90°F.
  • the ethanol coming off of distillation tower 274 is liquidified by condensor 276. Some of the ethanol is passed through reflux drum 284 and then recycled back to the distillation tower at 278 in order to increase the efficiency of the tower.
  • the carbon dioxide which is separated from the ethanol by the reflux drain contains a small percentage of ethanol. Accordingly, it is pre- ferable to pass this vapor through scrubber 282 so that this ethanol can be ultimately collected.
  • a significant feature of the present invention is that a single vacuum source 280 is used to remove the ethanol from the wort in fermentation tanks 262 and 266 and to distill the ethanol in tower 274.
  • This design allows for the maintaining of a lower ethanol concentration in the fermentation vessels while keeping the concentration of the vaporized ethanol entering the distillation tower relatively high, thereby minimizing the amount of separation which must be accomplished by the distillation tower.
  • condensor 276 is placed in the vacuum line between the distillation tower 274 and the vacuum pump 280. With this orientation, it is much easier to maintain the required vacuum because as the ethanol condenses at 276, it increases the vacuum pull on the distillation tower.
  • One of the important features of the present invention is its versatility in accomodating a variety of starting materials. Accordingly, as the available starting materials vary over a period of time or several different types of starting materials become available, no significant modification need be made to the process of the present invention.
  • a source of pulped cellulose could simply be added into the process before the cadoxen or concentrated acid step of the delignification process, such as through valve 140 depictedin Figure 2.
  • materials could be added just before the acid hydrolysis, such as through valve 142.
  • starting materials containing simple sugars were available, they might be added to the continuous process at a point just before the fermentation process, such as through valve 144, which would subject the materials to a temperature high enough to sterilize them.
  • methanol 120 for denaturing and the major components of a blended ethanol-based fuel, benzene 122 and acetylene 124 can be synthetically manufactured in carbon dioxide conversion unit 126 from the excess carbon dioxide produced as a byproduct of the fermentation process.
  • addi ⁇ tional quantities of ethanol can be synthetically pro ⁇ quizzed from the excess carbon dioxide.
  • the process of producing this synthetic ethanol 130 utilizes the hereto ⁇ fore wasted carbon dioxide byproduct of the fermentation process to dramatically increase the yield of ethanol. In fact, without increasing the amount of starting cellulosic materials or the size or number of the processing vessels or distillation towers, it is possible to nearly double the production of ethanol.
  • carbon dioxide from the fermentation vessels can be reacted with carbon at elevated temperatures (such as about 600°C to 1000°C) to produce carbon monoxide: C + C0 2 ⁇ > 2CO
  • Carbon monoxide can be reacted with water at temperatures of about 200°C to 500°C to form hydrogen and carbon dioxide:
  • carbon monoxide and hydrogen in the presence of a variety of well-known mixed metal oxide catalysts can be combined at temperatures of about 300°C to 600°C and pressures of about 100 to 200 atmospheres to produce both methanol and benzene:
  • Methanol can also be produced by the well-known Fisher- Tropsch process. Additionally, carbon monoxide can be combined with methane (which can be made from carbon monoxide and hydrogen, anaerobic digestion, or natural gas) and water at temperatures of about 300°C to 600°C over iron catalysts to yield ethanol and iron oxide:
  • OMPI ethanol without increasing the amount of cellulosic starting materials.
  • acetylene can be produced from methane with a low electric discharge, and ethylene, a basic chemical in the petrochemical industry, can be produced.
  • each processing step can be conducted in a vessel specially designed for each operation and at the temperature and pressure conditions most suited for that operation. By conducting each operation at the optimum conditions, the yield of ethanol can be greatly improved.
  • One of the most significant advantages of the present invention is that the fermentation time is dramatically reduced from about 72 hours to a total about three to six hours. This reduction is possible because of the high yeast population and the minimizing of ethanol inhibition. Because there is a constant flow of wort into the fermentation vessel and ethanol out of the vessel, there is a continuous propogation of yeast during the fermentation process which maintains an optimum population.

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Abstract

Procede de production d'alcool, en continu de preference de l'ethanol (130), a partir de materiaux de cellulose (10). Les materiaux de cellulose (10) sont delignifies de sorte que l'hemicellulose (34) et la cellulose (58) peuvent etre ulterieurement hydrolyses (60) en sucres simples (76). Ces sucres sont fermentes (90) en presence d'une levure (88) pour produire de l'ethanol (110) et de l'acide carbonique (96). La vapeur d'alcool est extraite de la solution de fermentation sous pression reduite puis elle est distillee (100). On fait barboter le gaz carbonique au travers de la solution de fermentation (90) de maniere a faciliter l'extraction de l'alcool de la solution de fermentation. Le gaz carbonique est recueilli et utilise dans la fabrication de quantites additionnelles d'ethanol ou autres produits chimiques de base.
EP19800902322 1979-10-23 1981-05-04 Procede de fabrication d'alcool. Ceased EP0038359A4 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US8819679A 1979-10-23 1979-10-23
US88196 1979-10-23
US195326 1980-10-20
US06/195,326 US4425433A (en) 1979-10-23 1980-10-20 Alcohol manufacturing process

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EP0038359A1 true EP0038359A1 (fr) 1981-10-28
EP0038359A4 EP0038359A4 (fr) 1982-02-16

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EP19800902322 Ceased EP0038359A4 (fr) 1979-10-23 1981-05-04 Procede de fabrication d'alcool.

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EP (1) EP0038359A4 (fr)
JP (1) JPS56501311A (fr)
CA (1) CA1168998A (fr)
DK (1) DK274481A (fr)
MC (1) MC1503A1 (fr)
NO (1) NO812106L (fr)
WO (1) WO1981001154A1 (fr)

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DE3277699D1 (en) * 1982-10-04 1987-12-23 Baron Howard Steven Strouth Method of manufacturing alcohol from ligno-cellulose material
YU25697A (sh) * 1997-06-18 1999-07-28 Dušan Ćirić Postupak za dobijanje etil alkohola iz celuloze
ES2259260B1 (es) * 2004-07-14 2007-06-16 Angel Garcia Moreno Procedimiento para la evaporacion de aguas residuales y/o productos de cola aplicable en procesos de destilacion aprovechando la energia calorifica perdida en la salida de fluido de refrigeracion e instalacion.

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3314797A (en) * 1963-04-12 1967-04-18 Georgia Pacific Corp Converting lignocellulose materials into yeast containing stock feed
FR2419351A1 (fr) * 1978-03-08 1979-10-05 Purdue Research Foundation Procede de recuperation et d'utilisation de la cellulose a l'aide d'acide sulfurique

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Publication number Priority date Publication date Assignee Title
US2053769A (en) * 1933-08-15 1936-09-08 Dreyfus Henry Removal of volatile compounds from a fermenting medium
US2451156A (en) * 1944-06-19 1948-10-12 Mattos Annibal Ramos De Process and apparatus for producing alcohol by fermentation
US2862819A (en) * 1954-08-05 1958-12-02 Miller Brewing Apparatus for and method of removing impurities from highly volatile gas
US3234026A (en) * 1956-08-17 1966-02-08 Coutts Morton William Process for the manufacture of beer, ale and the like
US3212932A (en) * 1963-04-12 1965-10-19 Georgia Pacific Corp Selective hydrolysis of lignocellulose materials
US3212933A (en) * 1963-04-12 1965-10-19 Georgia Pacific Corp Hydrolysis of lignocellulose materials with solvent extraction of the hydrolysate
US3799845A (en) * 1971-07-06 1974-03-26 Badger Co Beer distillation
US3930042A (en) * 1973-12-14 1975-12-30 Distillers Co Yeast Ltd Production of vodka
US4094740A (en) * 1974-09-27 1978-06-13 Lang John L Preparation of liquid fuel and nutrients from solid municipal waste
US4009075A (en) * 1975-08-22 1977-02-22 Bio-Industries, Inc. Process for making alcohol from cellulosic material using plural ferments

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3314797A (en) * 1963-04-12 1967-04-18 Georgia Pacific Corp Converting lignocellulose materials into yeast containing stock feed
FR2419351A1 (fr) * 1978-03-08 1979-10-05 Purdue Research Foundation Procede de recuperation et d'utilisation de la cellulose a l'aide d'acide sulfurique
GB2017710A (en) * 1978-03-08 1979-10-10 Purdue Research Foundation Process for Recovering and Utilizing Cellulose Using Sulfuric Acid

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of WO8101154A1 *

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NO812106L (no) 1981-06-19
EP0038359A4 (fr) 1982-02-16
DK274481A (da) 1981-06-22
CA1168998A (fr) 1984-06-12
JPS56501311A (fr) 1981-09-17
MC1503A1 (fr) 1983-11-17
WO1981001154A1 (fr) 1981-04-30

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