EP2059603A1

EP2059603A1 - Method of producing bioalcohol, in particular bioethanol and/or biobutanol

Info

Publication number: EP2059603A1
Application number: EP07801949A
Authority: EP
Inventors: Andre Düx; Andreas Jupke; Dieter Mrotzek; Georg Ronge; Sebastian Schmidt; Matthias Böhm
Original assignee: Bayer Technology Services GmbH
Current assignee: Bayer AG
Priority date: 2006-08-30
Filing date: 2007-08-29
Publication date: 2009-05-20
Also published as: DE102006040567A1; NO20090950L; AR062602A1; RU2009111200A; WO2008025522A1

Abstract

The present invention relates to a method of producing bioalcohol, in particular ethanol or butanol, from biomass, in which the biomass is comminuted, the remaining biomass is fed to a fermentation and the alcohol is obtained from the product of the fermentation, characterized in that insoluble components and/or non-fermentable sugars are separated off from the biomass before the fermentation and/or yeast and bacteria are separated off after the fermentation.

Description

LIOHOL FROM A MAIZE, FROM THE FERMENTATION SOLIDS WAS ABOLISHED

The invention relates to a process for the production of bioalcohol, in particular bioethanol and / or biobutanol, from biomass, in particular from cereals and in particular from rye by fractional grinding, saccharification, fermentation and distillation. A special feature of the method is that after saccharification initially undissolved solid components and in a subsequent separation step non-fermentable carbohydrates (NFS: non fermentable sugars) such as pentosans and glucans are separated. As a result, the separation of valuable feed yeasts or, in the case of butanol, the separation of the bacteria for recycling after the fermentation (main fermentation) becomes possible for the production of ethanol. The NFS-rich phase obtained during the separation of non-fermentable carbohydrates is fermented in a separate fermentation step (secondary fermentation), which is carried out parallel to the main fermentation, optionally together with undissolved solid constituents. A particular advantage of the method is that a yield loss is avoided by sugar contained in the NFS phase, as this is also fermented in the parallel to the main fermentation Nebenfermentation to alcohol.

The fermentation of biomass is economically important from the point of view of the planned future addition of bioethanol and biobutanol to fuels. In the large-scale production of bioethanol can be in addition to the main ingredient ethanol but also recyclables for the feed industry, such as DDGS (Distillers' Dried Grains with Solubles) or valuable forage yeasts won.

The production of alcohols by fermentation of a biomass is one of the oldest biotechnological processes and is u.a. used for the production of alcoholic beverages, such as beer and wine. Also, the production of alcohol to be used industrially by fermentation of biomass has been known for a long time. At present, corresponding alcohols, especially ethanol, are used as starting material for the preparation of pharmaceutical compositions, cosmetic products, and a variety of chemicals.

The use of fermentative ethanol as an energy carrier has long been known, but was not used commercially due to the higher compared to the recovery of oil process costs in the past.

Due to the shortage of oil reserves and the reduction in CO ₂ demanded by the Kyoto Protocol, the potential use of bioethanol as an energy source has gained new importance. There is therefore a great need for improved processes for producing ethanol to a greater extent from biomass. Due to the agricultural overcapacity of the European Union, the use of cereals, especially rye, is of particular interest for the production of bioalcohol. An essential factor determining the manufacturing costs of a process is the starch content. The starch content of wheat is highest at 67.5% by weight, followed by triticale at 66.5% by weight and barley at 66.1% by weight. Rye has a starch content of 64.6% by weight and has a lower ethanol yield due to its grain shape, smaller grain size and higher content of non-fermentable pentosans. Rye has a relatively high protein content, which on the one hand has a negative effect on ethanol production, but on the other hand has a positive effect on Distillers' Dried Grains with Solubles (DDGS). However, there is still no experience with rye DDGS and it is therefore not yet established on the market as animal feed. The prospects for a possible market launch are assessed as positive. The production of ethanol from rye causes slightly higher conversion costs than wheat or triticale. These higher costs result from the application of viscosity-lowering enzymes to counteract the conglutination in the conversion process and the higher steam demand for DDGS drying. A Schlellerückführung is only possible in accordance with the Einmaischkonzentration and thus varies depending on the viscosity. If necessary, the raw material must be tested for its viscosity behavior before use. Another argument in favor of using rye is the limited availability of other cereals on typical rye sites. Triticale is one of these plants, but it is estimated that only about 50% of the rye area is economically viable for this crop type. Because of its low demands on fertilization and care and the current oversupply, it is available as a low-cost raw material for the production of bioethanol.

Numerous processes for the production of alcohols from biomass are known in the art. Since completely different biomasses are used as starting material for these processes, including sugar cane, sugar beet, cereals, etc., the processes for obtaining the bioalcohol differ greatly from each other. Even with the use of identical starting materials, there are different procedures.

The known fermentative processes for the production of ethanol from biomass, in particular cereals, have the following steps:

(a) the biomass is crushed;

(b) microorganisms are added to the biomass and a fermentation is carried out; and (c) The ethanol is separated from the biomass.

The separation of the ethanol is usually carried out by distillation. In this case, the remainder is stillage, which is usually concentrated and used as fertilizer or after drying as protein-containing feed.

Each of these process steps is described in the prior art in many embodiments (e.g., DE 3007138 A1, DE 10321607 A1, RU 2102 480).

DE 3007138 A1 describes a process for producing ethanol by fermenting a carbohydrate-containing substrate in one or more fermentation containers. After fermentation, the fermentation liquor is distilled, rectified and optionally dehydrated to anhydrous alcohol. The fermentation liquid is divided into at least one yeast concentrate flow and a yeast-free flow. The Hefekonzentratströmung is returned to the fermentation tank and divided the yeast-free phase by distillation in an ethanol-rich and a residual flow (vinasse). The residual flow is again partially fed to the fermentation tank. The advantages of the method described in DE 3007138 A1 are that the yeast-free flow can be processed in a simple evaporator using one or a few distillation stages by dividing them partially into an ethanol-rich first steam flow and into a first liquid bottom flow. The steam flow is fed to a plant for the production of the desired ethanol quality. The bottom flow is partially returned to the fermentation tank and partially fed to a power take-off unit in which this part is divided into an ethanol-rich second steam flow and a second liquid bottom flow which is low in ethanol. The ethanol-rich vapor stream can be used together with the first ethanol-rich vapor stream for the recovery of ethanol, for example in a rectification column. Although the method described in DE 3007138 A1 describes the separation of the yeast after the fermentation, it does not describe the steps required for the separation of yeast preceding the fermentation.

The fermentative production of butanol (because of the by-products acetone and ethanol also called ABE fermentation) has been known for years. Until about 1930/1940, for example, plants were operated in South Africa. A particular challenge is that the microorganisms for the conversion of dextrins / glucose into butanol tolerate a maximum butanol concentration of 1-3% by weight (see, eg, Jones, Woods, Microbiological Reviews, 1986, pp. 484-524). Beyond this limit, the microorganisms become inactive and the fermentation is stopped. Due to this maximum butanol concentration, the workup of the mash for product recovery is very complex in terms of apparatus and energy. A Purely distillative workup requires about 8-9 t of steam per ton of butanol. Meanwhile, this technology is being intensively researched in terms of using biobutanol as biofuel.

In the production of ethanol and / or butanol from biomass, in particular cereals, such as wheat, rye or triticale, and here in particular rye separation steps are required before the fermentation, without the separation of the bio-organism (eg, yeast in the ethanol fermentation or bacteria in Butanolfermentation) can not be performed or only with difficulty. In addition, in some cases it may be economical to at least partially expel the bioorganism concentrate flow after the fermentation unit and to produce a valuable feed in the ethanol fermentation by suitable steps or to allow the advantageous cell recycling in the butanol fermentation. It would be advantageous in the course of the process to separate the alcohol from the bioorganism solution and other solid by-products from the processing of the cereals as effectively as possible, first to optimize the yield of the alcohol extraction, moreover to minimize the cost of drying the obtained feed ,

In the RU 2102480 a process for the production of ethanol is described, in which the yeast is separated after the fermentation, partially recycled to the fermentation and partially discharged. However, the starchy raw material used for ethanol production is comminuted by a Vollvermahlung, with a separation of the solids takes place after the saccharification. On the one hand, this results in the disadvantage that the drying of the separated solids is expensive because of the higher moisture content, but on the other hand the separation also leads to sugar losses and thus ultimately to a lower ethanol yield based on the amount of raw material used. The separation of the yeast is by sedimentation, but is not described in detail.

In DE 10321607 Al a process for the production of ethanol from rye or wheat vinasse is described in which both the particulate form and soluble globular proteins are separated in advance of the alcohol separation. The separation of the soluble globular proteins takes place by denaturation by means of Lewis acids and subsequent separation by means of micro- or ultrafiltration. In this method, the yeast is completely discharged after fermentation. Disadvantages are the increased operating costs through the use of Lewis acids, the required by the required Vollvermahlung, increased energy expenditure for drying the particulate proteins, if you want to use them as feed. In addition, there may be losses of saccharificable starch by the separation of soluble globular proteins. It is also questionable whether the maintenance of the described method can be reduced by using micro or ultrafiltration equipment.

Separation of non-fermentable carbohydrates (e.g., pentosans and glucans) is not described in the previously cited publications.

For the fermentation of butanol from starchy or sugary raw materials, there are many approaches (see eg Schügerl, Biotechnology Advances, 2000, p 581-599), which confirm that retention of the bio-organisms (bacteria), including cell immobilization (See, for example, Huang, Ramey, Yan, Applied Biochemistry and Biotechnology, 2004, pp. 887-898; Ramey, DOE Report DE-F-G02-00ER86106, Production of Butyric Acid and Butanol from Biomass, 2004; Zhu, Yang, Biotechn., Progr., 2003, pp. 365-372), which improves space-time yield, and that separation techniques such as extraction, adsorption, gas stripping, and pervaporation can reduce the overall energy expense for butanol recovery.

However, none of these sources take account of the fact that, in particular when using starchy raw materials, in particular cereals, such as e.g. Rye, wheat, barley and maize the solids contained in the raw material (bran, fibers, non-fermentable starch, proteins) are exposed to serious problems such concepts:

- Cell retention: would also hold back and accumulate the other solids

- Immobilization: risk of constipation, fouling

- Extraction columns: danger of blockage, fouling

- Pervaporation: danger of constipation, fouling

The invention is therefore based on the object of providing an economical process for producing bioalcohol, in particular bioethanol and / or biobutanol, from biomass, preferably cereals, in particular based on rye, in which no complicated grinding or denaturing of the vinasse is required, in which the valuable feed yeasts can be separated and recycled after the fermentation, and in addition to the main alcohol (ethanol and / or butanol) and valuable feed yeasts can be obtained as possible without elaborate drying. A special challenge is the separation of the yeast after fermentation with the highest possible ethanol yield.

The object is achieved according to the invention in that insoluble solid constituents and non-fermentable carbohydrates, hereinafter referred to as NFS (non-fermentable sugar), are separated and the thus purified sweet Mash in a fermentation, hereinafter referred to as main fermentation, is fermented to alcohol. Surprisingly, it was found that when using cereals, especially when using rye as raw material, a separation of the yeast after fermentation, especially by higher molecular weight, non-fermentable carbohydrates (eg pentosans and glucans) is not possible or only under much more difficult conditions and that Separation of the non-fermentable carbohydrates prior to fermentation, which allows separation of the yeasts after the main fermentation from the ethanol-containing vinasse, in order to supply them again to the fermentation and / or to disperse them.

The invention relates to a process for the production of alcohol from biomass, in which the biomass is comminuted, the remaining biomass is fed to a fermentation and the alcohol is obtained from the product of the fermentation, characterized in that insoluble solid constituents and / or non-fermentable sugars be separated from the biomass before fermentation and / or bio-organisms (yeast and / or bacteria) after the fermentation.

The invention preferably relates to a process for the production of alcohol from biomass with the following steps:

a. Comminution of biomass

b. Optional starch liquefaction and saccharification

c. Separation of insoluble solids and / or non-fermentable

Sugar from the biomass

d. fermentation

e. Separation of the bioorganism (yeast and / or bacteria)

f. Alcohol extraction.

In a particular embodiment of the process, ethanol is produced from biomass.

In a further embodiment of the process, butanol is produced from biomass.

In the following, the individual process sections are explained in detail. The method of the present invention is illustrated in FIG. The comminution of the biomass is usually carried out by complete grinding or fractional grinding. First, the pre-cleaned grain is fed to a milling unit to expose the starch particles contained therein. The mean particle size during milling is usually from 0.1 to 2 mm, preferably from 0.1 to 1 mm. Grain fractions with a low starch content (shell fraction) and a high proportion of viscosity-increasing substances, such as, for example, pentosans and glucans (bran fraction), are preferably separated off (fractional milling). For comminuting the cereal grains and for separating the shell fraction, apparatuses corresponding to the state of the art are used (for example, a combination of double roller chairs with a basket sifter, possibly with an upstream sanding machine).

For some raw materials such as sugar cane or sugar beet, step b) d. H. Starch liquefaction and saccharification optional. For cereals, starch liquefaction and saccharification are again required.

In a particular embodiment of the method, the biomass is cereals, in particular rye, and the method comprises the following steps:

a. Comminution of biomass

b. Starch liquefaction and saccharification

c. Separation of insoluble solid components and / or non-fermentable sugars from the biomass

d. fermentation

e. Separation of the bioorganism (yeast and / or bacteria)

f. Alcohol extraction,

optional fractions having a lower starch content (shell fraction) and a high proportion of viscosity-increasing substances (glutinous fraction) are separated off prior to liquefaction prior to step (b).

In starch liquefaction, the starch particles contained in the cereal flour are liquefied, ie converted into dextrins and the mash viscosity is lowered by enzymes (46). For this purpose, the water used in the Anmaischen is added with enzymes and then with the flour below the gelatinization, ie at a temperature of 20 - 80 ⁰ C, preferably but mixed 40-60 ° C. The gelatinization in cereals is from 50 to 8O ⁰ C, wheat 53-65 ⁰ C and at 55 to 7O ⁰ Rye by C. In this case, a Anmaischeverhältnis of 1 -3 kg water / kg flour, but preferably from 1.5 - 2.5 kg of water / kg of flour sought. After mixing the mash at temperature above the gelatinization temperature and thus Gelatinisierungs- or to a temperature of 50 is - 100 ⁰ C, but preferably at a temperature of 70 - 100 ⁰ C heated. This can be done either by direct steam injection or indirectly, but preferably directly. The enzymes used for the liquefaction can be found in the corresponding technical literature (Norbert Schmitz (ed.) Bioethanol in Germany Publication Series Renewable Resources Volume 21; 2003; Landwirtschaftsverlag GmbH; 48165 Münster). Examples of possible enzymes include amylases, xylanases, glucanases or cellulases (for example the commercial products BAN 480 L, Novozym 50024, Liquozyme SC). The same enzymes can be used for liquefaction in the production of biobutanol. The liquefaction takes place at pH values between 3 and 8, preferably between 5 and 6 and more preferably between 5.3 and 5.7. The resulting mash usually has a dry matter content (TS) of 20-40% by weight, preferably 30-35% by weight. The dry matter content is adjusted by adding process water (6) and stillage (5). The starch liquefaction can take place in one or more apparatuses connected in series. The residence time depends on the amount of enzyme used and is usually between 0.5 and 5 h, preferably between 1 and 3 h. The heating can be done either by direct steam injection or indirectly, but preferably directly.

After liquefaction is usually a cooling of the mash to 40 - 70 ⁰ C either by means of a heat exchanger or by flash evaporation under vacuum.

This is followed by saccharification of the mash, ie the transformation into a sweet mash. The dextrins are converted into glucose, which can then be fermented in the fermentation to alcohol, (ethanol or butanol). In the saccharification unreacted dextrins are still converted into fermentable glucose in the fermentation. The saccharification reaction usually takes place at temperatures between 30 and 70 ^° C., preferably between 60 and 65 ^° C. The residence time depends on the amount of enzyme used and is usually between 15 and 40 h, preferably 20 and 30 h. The pH is usually between 3 and 7, preferably between 5 and 6, and more preferably between 5.3 and 5.7. The saccharification can take place in one or more stirred stirred tanks (stirred tank cascade) or in a tubular reactor with or without internals. In saccharification, suitable saccharification enzymes (glucoamylase, eg the commercial product Spirizyme Fuel) are used (47). For pH adjustment and phosphorus Supplying the yeast cells added later, phosphoric acid (48) can be added. In addition to phosphoric acid, other acids, such as sulfuric acid, are suitable for adjusting the pH.

In particular in the case of butanol fermentation, it is also possible optionally to dispense with the saccharification partially or completely, since the clostridia known from the cited literature are also able to partially convert the liquefied starch without the saccharification step.

In step c) of the process according to the invention, the preparation of the sweet mash follows by separation of undissolved solid constituents in order to minimize the necessary residence time of the subsequent fermentation reaction and secondly to allow the separation of the bioorganism (yeast and / or bacteria) after fermentation. The separation is preferably carried out mechanically e.g. by means of separators or decanters. The amount of the resulting concentrate phase containing a large part of the undissolved solid constituents corresponds to about 2-70% by weight of the supplied mash, depending on the type of milling (fractionating or fully comminuting). In the case of fractional milling this proportion is below 40 wt .-%. The moisture content of this concentrate phase is usually from 30 to 95 wt.%.

To minimize the sugar losses, it may be advantageous to supply the separated undissolved solids to a single or multi-stage water wash, wherein a wash ratio is preferably adjusted from 0.5 kg water: 1 kg concentrate phase - 5 kg water: 1 kg concentrate phase. The undissolved solid components washed with water, if appropriate recovered from the process, are preferably collected and transported for DDGS drying. The overflow laden with sugar is preferably recycled partly for mashing into starch liquefaction. The other partial flow is preferably used to adjust the sugar concentration in the fermentation. The sugar concentration is usually adjusted so that about 10 wt.% Ethanol or 1-3 wt.% Butanol are achieved during fermentation.

In a further embodiment of the process, the separated, undissolved solids are fed together with NFS to a secondary fermentation. In this way, sugar losses can also be minimized.

After the separation of undissolved solid constituents, the separation of non-fermentable carbohydrates (NFS) is preferably carried out. The NFS phase is usually separated mechanically by decanting or filtering, preferably decanting. The remaining mash (11) exiting in the overflow is fed to the fermentation (hereinafter referred to as main fermentation (14)). In a particular embodiment of the process, the NFS phase is fed to a secondary fermentation operated parallel to the main fermentation, this secondary fermentation converting the residual sugar and increasing the yield of alcohol production. Usually, the amount of flow to the main fermentation and the amount of electricity for Nebenfermentation in the ratio 0.5: 1 - 20: 1, but preferably in the ratio 1: 1 - divided 10: 1.

For the mechanical separation of the NFS phase usually known in the prior art apparatuses such as decanters or separators are used.

To improve the separation flocculants are preferably added.

For example, both anionic and cationic flocculants can be used as flocculants. Acrylamides having a strong cationic copolymer (for example Praestol 853 BC, Stockhausen GmbH & Co KG), acrylamides having a weakly cationic copolymer (for example Praestol 611 BC, Stockhausen GmbH & Co KG) have proven particularly suitable.

Acrylamides with a weakly cationic copolymer (for example Praestol 853 BC, Stockhausen GmbH

& Co KG), Copoylmer acrylamide with acrylate (weak anionic, for example Praestol 2520 from Stockhausen GmbH & Co KG) and medium anionic acrylamide copolymer with acrylate (e.g.

Praestol 2540 from Stockhausen GmbH & Co KG). The admixing of the flocculant is usually carried out as a 0.01-1% solution in water. In this case, preferably 10 to 1000 ppm, based on solids, are metered in. By the use of flocculants is the

Separation of the NFS phase significantly improved. The sedimentation rate is significantly increased (factor 10 - 50). It also makes it possible to NFS phase and insoluble

Separate solid components in a single step. Thus, it is preferable to supply the insoluble solid components along with the NFS phase to the minor fermentation.

For the fermentation, the mash is usually cooled to temperatures between 25 and 50 ^° C., preferably between 30 and 45 ^° C. The cooling of the mash can take place both before and after the NFS separation, but preferably after the NFS separation.

Due to the high dilution required in butanol fermentation, after saccharification and prior to fermentation, additional water (e.g., recycled water, stillage, or process water) is added to adjust the desired final fermentation concentration.

In the fermentation phase, the fermentation of glucose to ethanol takes place. The main fermentation can be operated continuously or discontinuously, but preferably continuously. The operating temperature is preferably 25-50 at 30 - 42 ⁰ C. The necessary residence time depends on the amount of yeast used and is usually between 10 and 30 h. In this case, an ethanol content above 10 wt .-% is usually achieved. The yeast content is usually between 0.3 and 0.9% by weight at the start of fermentation. The final sugar content is ldR less than 0.1 wt .-%. The pH is preferably 4-6.

If the fermentation of glucose into butanol is carried out in the fermentation phase, the main fermentation can be carried out continuously or discontinuously, but preferably continuously. Examples of the fermentation commonly used bacteria provides eg Jones, or Woods, Microbiological Reviews, 1986, p. 484-524. The use of immobilized bacteria known in the art is also possible (see, for example, Huang, Ramey, Yan, Applied Biochemistry and Biotechnology, 2004, pp. 887-898, Ramey, DOE Report DE-F-G02- 00ER86106, Production of Butyric Acid and Butanol Frorn Biomass, 2004; US 5,563,069; Zhu, Yang, Biotechn. Progr., 2003, pp. 365-372). The operating temperature is usually 25 to 50 preferably 30 to 42 ^° C. The necessary residence time depends on the amount of bacteria used, and is usually between 30 and 60 hours. In this case, a butanol content of 0.5 to 3 wt .-% is usually achieved. The bacterial content is usually between 0.5 and 5% by weight at the start of fermentation. The final sugar content is ldR less than 0.1 wt .-%. The pH is preferably 4-7.

In a particular embodiment of the process, the separation of the substrate (yeast and / or bacteria) takes place after the main fermentation. This can be done mechanically by methods known from the prior art, for example by means of a decanter or separator. The mash is usually divided into two fractions of different densities. In the heavy phase, the ethanol fermentation is the so-called yeast milk containing 10 to 30 wt% TS (20 wt% TS). This is preferably partially returned to the fermentation and partially removed to obtain yeast. Butanol fermentation uses the heavy phase to retain the bacteria and optionally recycle it. Thus, in the downstream area, a solids-free processing of the mash is possible and a cell recycling to increase the space-time yield. The light phase usually has a dry matter content of 0-10% by weight TS. Flocculation aids can be used to improve yeast separation. As a possible flocculant z. B. bentonite, silica sol and gelatin or weak to strong amonic copolymers of acylamide and Natπumacrylat m different combinations applicable. The use of flocculants on the one hand significantly reduces the sedimentation rate by factors of 1-10 and on the other the sediment volume (30-100% by volume in comparison to the sediment volume without flocculant). The amount of flocculant used is preferably 10-100,000 ppm on solid. The hefereiche phase (yeast milk) obtained in the yeast separation usually has an alcohol content of about 6 to 10 wt .-%, which would mean a loss of alcohol. The alcohol contained in the yeast milk is separated in a particular embodiment of the process in a rectification column. Subsequently, the yeast is usually dried using the prior art methods.

The recovery of ethanol or butanol from incurred in the fermentation vinasse is usually carried out by distillation. The fermented mash is preheated and then degassed in the degassing column. In order to minimize the loss of alcohol, the alcohol contained in traces in the gas stream is washed out in the exhaust air scrubber and mixed back into the mash stream.

In the mashing column, the alcohol is expelled under vacuum. By vacuum, but also by the yeast separation carried out after the fermentation, the column can be operated at relatively low temperatures, whereby the risk of fouling can be reduced.

The bottom product, the so-called vinasse, is fed to the vaporizing steam. The head vapors are condensed and given up as reflux to the mash column. A liquid side draw, so-called crude alcohol, is added directly to the azeotropic column for further concentration and purification steps. From the azeotrope a fusel oil fraction is withdrawn as a side stream, condensed in the side stream condenser and passed into a decanter. The aqueous phase of this separation step is returned to the azeotropic column. The concentrated fusel oil is discharged. The distillate consists of an alcohol-water mixture of approximately azeotropic composition. The distillate from the azeotrope column is added to the dewatering column. In this column, pure ethanol (about 99.7%) is withdrawn as bottoms product with cyclohexane as entraining agent.

The distillate of the dewatering column is cooled and passed into a decanter where two liquid phases are separated:

The organic phase is added as reflux back to the dewatering column, whereas the aqueous phase is added to the cyclohexane column. In the cyclohexane work-up column, the water is separated from the entrainer and leaves the column as a bottom product for wastewater collection. A side stream is passed to the dewatering column containing the recovered entrainer. Low boilers are removed as needed with the top stream of the cyclohexane workup column.

Loss of trailing agent will be replaced by external supplies. As an alternative to the purely distillative process but also combination of rectification and membrane processes (eg reverse osmosis, vapor permeation or Pervaiporation) and / or adsorption is conceivable.

The latter are preferably used for ethanol drying.

The alcohol dehydration by means of adsorption takes place, for example, according to the pressure swing adsorption method (PSA). As adsorbent mainly zeolites are used. The PSA process has lower energy requirements than the previously described heteroazeotrope process with thermal integration. In addition, no further release agent is required here, which is particularly advantageous with regard to the production of animal feed as co-product of bioethanol production.

The recovery of butanol from the vinasse is usually also by distillation, preferably in a continuous distillation process. In a rectification called in a first mash or beer column, at the top the butanol and other by-products of the fermentation (for example ethanol and acetone) and the water content resulting from the thermodynamic equilibrium are removed. After the boiling sequence acetone and azeotropic ethanol are now separated by distillation. The drying of the azeotropic ethanol can - if necessary - be carried out again by azeotropic rectification or pressure swing adsorption. The remaining water-butanol mixture, which forms a heteroazeotrope, can now be worked up by means of heteroazeotrophic rectification or pressure swing distillation. The thereby separated water can be recycled in the process.

In a particular embodiment of the method, syrup and / or molasses (41) originating from the sugar production together with the mash (12) freed from NFS are fed to the main fermentation (14) and / or together with the NFS phase to the secondary fermentation (13). This possibility represents an interesting utilization of by-products of sugar production. The thick juice can be used on the one hand to lower the viscosity and on the other hand to adjust the sugar content of the mash to be fermented.

To avoid losses in yield, in a particular embodiment of the process, the separated phase in the separation of NFS, which is a mixture of NFS and included sugar solution, a fermentation parallel to the main fermentation, hereinafter referred to as Nebenfermentation, to avoid losses in yield fed. In a further embodiment of the method, the undissolved solid constituents separated during the solids separation are fed to the secondary fermentation. The advantage is that it can eliminate the need to avoid sugar loss water wash.

The fermentation in the Nebenfermentation can be operated continuously or discontinuously, but preferably continuously. The operating temperature is preferably 25-50 at 30 - 42 ⁰ C. The necessary residence time depends on the amount of yeast used, and is usually between 10 and 30 h. In this case, an ethanol content of up to> 10% by weight is usually achieved. The yeast content is at the start of fermentation: usually between 0.3 to 0.9% by weight.

The sugar end content is i.d.R. <0, 1 wt .-%. The pH is usually 4-6.

The resulting in the fermentation vinage can also be used after alcohol separation and drying together with the resulting in the comminution bran and the separated before fermentation undissolved solids as valuable feed (DDGS: Distiller's Dried Grains with Solubles).

The main task of vaporizing is to concentrate the vinasse from the distillation. In this unit, the concentration of the vinasse is carried out by single or multi-stage evaporation, with a multi-stage process is usually preferred because of the high energy demand.

To further reduce energy consumption, it is sometimes possible to use waste heat from the process, eg from DDGS drying. Depending on the type of use (feed or fuel), vinasse is concentrated to a TS content (dry matter TS) of 15-60% by weight, but preferably up to a DS content of 25-50% by weight. The degree of concentration depends on the type of raw material used for the production of bioalcohol. As a rule, however, the highest possible TS contents are sought. By the aid of flow aids, which can be added during the Schleppezeindampfung or even further upstream in the process (eg in the fermentation), the flowability of the concentrated stillage and thus the degree of concentration can be increased. The separated water is reintroduced into the process as so-called process water, which reduces the need for fresh water. The concentrate obtained during the vaporizing evaporation is dried together with the bran separated during the grinding by means of a process which corresponds to the prior art. This results in a so-called dry vat (DDGS). Details of the production of dry stillage are described, for example, in the journal "Die Branntweinwirtschaft" May 1976, pages 138 to 141.

The separating steps carried out before the fermentation make it possible to separate valuable feed yeasts after the fermentation. The NFS-rich phase resulting from the separation of non-fermentable carbohydrates is optionally fermented with undissolved solid constituents in a separate fermentation step. In a particular embodiment, the method described can also be used to process syrup and / or molasses originating from sugar production into ethanol.

The separation of the yeast after the fermentation, in addition to the production of an additional feed and significant advantages in the distillation and processing of the residues can be achieved because the pollution tendency of the apparatus significantly reduced and thus the potential for heat integration can be much better used.

Further, by recycling the yeasts, an additional fermentation step otherwise required to grow yeasts can be eliminated. This also increases the ethanol yield.

The inventive method provides in a preferred embodiment in addition to the main ingredient ethanol two different feeds, namely DDGS (Distiller's Dried Grains with Solubles) and yeast.

According to the invention, the method has particular advantages in the production of ethanol from cereals, and in particular rye as biomass:

high yield in the alcohol extraction by minimizing the losses,

- Obtaining a dry fraction by-product, used as feed or as

Fuel is recoverable,

Optimization of energy consumption. pictures:

In the following figures, particular embodiments of the method according to the invention are presented without being limited thereto.

Fig. 1: fractionated grinding, 2-step husk and NFS separation, 2-straße fermentation (main and secondary fermentation), two feeds (yeast and DDGS), yeast recycling.

The starchy raw material is first subjected to a fractional grinding, grain fractions with a low share of starch (shell fraction) and a high proportion of viscosity-increasing substances such as pentosans and glucans (bran fraction) are separated. Subsequently, the mashing of the flour obtained during the grinding takes place. For this, water recovered from the process (e.g., stillage) is used. The mash is then liquefied and saccharified. Thereafter, the separation of undissolved solid components takes place. These are fed together with the resulting in the fractional grinding shells and bran DDGS drying. Subsequent to the separation of undissolved solid components, the separation of non-fermentable sugar is preferably carried out with the aid of a flocculant. The non-fermentable sugar rich phase is fed to a Nebenfermentation, the remaining mash of the main fermentation and fermented the sugar then contained to alcohol. The yeast contained in the product of the main fermentation is partially separated, wherein the separated yeast partially fed back to the fermentation and partially discharged for the production of feed yeast. The remaining after the yeast separation and incurred in the secondary fermentation alcohol, ethanol or butanol-containing vinasse is fed to a further workup to obtain the ethanol.

Fig. 2: Fractional milling, 1-step husk and slime separation, 2-straße fermentation, two feeds (yeast and DDGS), yeast recycling

In contrast to the method described above, the undissolved solid components are also fed to the secondary fermentation.

Fig. 3: fractionated grinding, husk and slime separation, 2-straße fermentation, two feeds (yeast and DDGS), yeast recycling

The Vaπante represented takes into account the fact that when using flocculants both the separation of undissolved solid components and the non-fermentable sugar can be done in one step. Fig. 4: Fractional milling, husk and slime separation, 2-straße fermentation, two feeds (yeast and DDGS), yeast recycling

In comparison with the previous variant (FIG. 3), thick juice from sugar production is still used as raw material for alcohol production in this variant. Through targeted admixture with the main or secondary fermentation, the viscosity can be lowered and an optimum sugar content for the fermentation can be set. The addition of thick juice is also in the process variants of Fig. 1 u. Fig. 2 conceivable.

Fig. 5: (butanol fermentation) fractionated grinding, husk and slime separation, 2-straße fermentation, a feed (DDGS), bacterial recycling

The processing of the grain until the separation of the NFS is carried out analogously to Fig. 1. However, especially suitable bacteria are used for the butanol fermentation. These are fed to both the main fermentation and the secondary fermentation. In the main fermentation, a separation and recycling of the bacteria can be performed. The mash streams of the two fermentations are fed to the Schlempekolonne. This separates the biomass from the organic products (especially butanol, acetone, ethanol). The organic products are withdrawn in approximately azeotropic composition at the top of the Schlempekolonne and fed to your further work-up. The bottoms of the Schlempekolonne, the vinasse (biomass and water, approximately free of the organic fermentation products) is thickened by evaporation in a further work-up step and then dried. The dry goods are u.a. can be used as feed.

Fig. 6: (butanol fermentation) fractionated grinding, husk and slime separation, 2-straße fermentation, a feed (DDGS), bacterial recycling

Variant 6 differs from Variant 5 in that the undissolved constituents which are obtained in the UF separation are fed to the secondary fermentation.

Fig. 7: (butanol fermentation) fractionated grinding, husk and slime separation, 2-straße fermentation, a feed (DDGS), bacterial recycling

Variant 7 shows, in deviation to Fig. 6, that the separation of the undissolved solid constituents and the NFS with the addition of flocculants can also take place in one step.

Fig. 8: (butanol fermentation) fractionated grinding, husk and slime separation, 2-straße fermentation, a feed (DDGS), bacterial recycling As an extension of variant 7, thick juice from sugar production is also used as raw material for alcohol production. Through targeted admixture with the main or secondary fermentation, the viscosity can be lowered and an optimal sugar content for the fermentation can be set. The addition of thick juice is also conceivable in the process variants of FIGS. 5 and 6.

The process for producing butanol differs from the process for producing ethanol (FIGS. 1-4) in that

instead of yeast bacteria are used as microorganisms. These are also separated behind the fermentation, but then completely returned, for example.

Due to the high required dilution of the product in the fermentation is carried out during the production of butanol, a splitting of the recycled water to mashing and fermentation.

Depending on the use and modification of the butanol-producing bacteria in addition to the main product and lower amounts of acetone and ethanol, so that the

Processing of the products after fermentation must be adjusted accordingly.

embodiments

Example 1: husk, slime and yeast separation

The following experiment is limited to the steps of liquefaction, saccharification, husk / NFS separation, fermentation and yeast separation, since fractional milling alone is not a technical innovation. Accordingly, commercial rye flour was used.

When mashing, 83 kg of rye flour and 166 kg of water, which already contained the enzymes required for liquefaction (Novozyme 50024: 50 .mu.l / kg flour, Liquozyme SC DS: 200 .mu.l / kg of flour) at 55 ⁰ C were mixed. By adding a 2 mol% sulfuric acid solution, a pH of 5.5 was set.

Then, the liquefaction was carried out at 85 ⁰ C and a residence time of 1 h. After cooling to 55 ⁰ C, the saccharification took place. The saccharification enzymes used were Novozyme 50024 (500 μl / kg flour) and Spirizyme Fuel (500 μl / kg flour).

After saccharification, the insoluble solids contained in the mash were separated in a decanter. 19.1 kg of concentrate were obtained, which were washed with washing water in a ratio of 1: 1. The high solids fraction was about 8% based on the flow of sweetmeat.

After washing, 13 kg of concentrate were obtained, which was fed together with the bran to DDGS drying.

In the subsequent NFS separation, 18.3 kg of a slime-like concentrate (NFS phase) having a moisture content of 66.4% by weight were separated by means of a decanter.

After separation of the NFS phase, the remaining mash was fed to a fermentation. The fermentation was carried out at 38 ⁰ C and a pH of 5.5 and a residence time of 20 h. In this case, 22 g of yeast were added per liter of fermentation mixture.

Subsequently, the yeast separation was carried out. In this case, 25.3 kg of yeast concentrate having a residual moisture content of 82% by weight were separated by means of a decanter. Example 2: Simulation of the ethanol yield by means of Aspen +

The ethanol yield of the inventive method of FIG. 1 was determined by means of a simulation with a process engineering software (Aspen +).

The simulation serves, in particular, to map the overall method with the relevant return currents and to determine the energy consumption of the individual method sections. In the modeling of the process were solid / solid and solid / liquid separation with

Split models shown, with the split factors used for this purpose partially in the state of

Technique known, some were determined experimentally or in some cases based on assumptions. The simulation of the process stages liquefaction, saccharification and fermentation was carried out assuming experience levels of conversion. thermal

Separation methods, such as rectification or evaporation, have been used with step models

(e.g., Radfrac).

The following parameters were set in the simulation:

Rye quantity: 3.75 kg / h

Emmaischverhältnis: 2: 1

Ethanol concentration after fermentation: 10% by weight

The method according to the invention was simulated as follows.

The rye is first fed to a milling unit. It is estimated that an estimated 0.5 kg / h is separated as a shell or bran fraction.

Subsequently, the grain is mashed with water returned essentially from the process. The simulation was carried out with a mashing ratio of 2 (2 kg water / kg rye flour). The temperature of the mash is 48 ^° C. The process parameters of the liquefaction of rye are also known in the art. Thus, a temperature of about 85 ⁰ C is selected, which is adjusted by admixing water vapor (0.05 kg steam / kg mash). After liquefaction, the mixture is first cooled to 63 ° C. by means of flash evaporation and then the saccharification. For saccharification, suitable enzymes are added. Dextrins are converted into sugar. The sugar content after saccharification is estimated to be about 20% by weight. After saccharification, the separation of undissolved solids. The high solids fraction is estimated at 1.64 kg / hr. The separated undissolved solids are washed with water (1 kg wash water / 2 kg undissolved solids). The sugar-containing wash water is essentially fed to the fermentation. Through the wash, the sugar content of the separated undissolved solids is estimated to be <4% by weight.

Following the separation of the undissolved solids, the NFS separation takes place. The sweet mash is split in a ratio of 2: 1 into a low-NFS and an NFS-rich stream.

The low-NFS stream (about 7.1 kg / h) is fed to the main fermentation, while the NFS-rich stream is fed to the secondary fermentation. In the fermentation occurring CO ₂ is fed to avoid ethanol losses of an absorption column. For leaching the

Ethanols are used about 0.74 kg of water. After fermentation, the ethanol content is about 10% by weight. The product of the Nebenfermentation is fed to ethanol production, while after the main fermentation first yeast is separated. For this purpose, the product of the main fermentation is divided into a yeast-rich and a low-yeast fraction in a ratio of 1: 5.

About 70% of the high-yeast fraction is returned to fermentation, the remaining 30

% for the extraction of feed yeast removed.

The low-yeast fraction (about 6.5 kg / h) is mixed together with the product of the Nebenfermentation and fed to ethanol production. This is done in the simulation by distillation, m the mash column alcohol and water are separated at 300 mbar. The bottom of this column, the so-called stillage (estimated at 5 kg / h) is fed to a 6-stage evaporation and there evaporated at different pressures (estimated 0.1 to 0.5 bar). The concentrated vinasse (estimated at 1.8 kg / h), along with the shell and bran fractions from the milling and the undissolved solids separated after saccharification, are sent to drying. The drying process produces 1.51 kg / h of DDGS. The heat produced by condensation of the evaporated water is used for vaporizing. The water separated in DDGS drying and in vaporizing is returned to the process, e.g. for maceration.

The distillate of the Schlempekolonne (estimated 1.8 kg / h) is fed to the azeotrope. The ethanol is separated at an estimated 2 bar in azeotropic composition as the top product. The water separated at the bottom of the column (estimated at 0.7 kg / h) is reused in the process. From the azeotrope is a fusel oil fraction as Side stream withdrawn, condensed in the side stream condenser and passed into a decanter. The aqueous phase of this separation step is returned to the azeotropic column. The concentrated fusel oil (estimated 7 g / h) is discharged. The distillate from the azeotrope column is added to the dewatering column. This is operated at a pressure of approximately 12 bar. In this case, water is withdrawn using cyclohexane as entrainer as the top product and pure ethanol (estimated lkg / h with 99.7 wt .-%) as the bottom product.

The distillate of the dewatering column (estimated 3.7 kg / h) is cooled in a heat exchanger to an estimated 140 ⁰ C and passed into a separating bottle in which two liquid phases are separated:

The organic phase (estimated at 3 kg / h) is added as reflux back into the dewatering column, whereas the aqueous phase is added to the recovery column.

In the cyclohexane work-up column (operating pressure estimated at 2 bar), the water is separated from the entraining agent and leaves the column as bottom product (estimated at 67 g / h) for wastewater collection. A side stream is passed to the dewatering column containing the recovered entrainer. Low boilers are removed as needed with the top stream of the cyclohexane workup column.

Loss of trailing agent will be replaced by external supplies.

The amount of ethanol recovered is estimated to be 1 kg / h in the simulation described. An additional 1.51 kg / h of DDGS and 0.11 kg / h of yeast are estimated to be produced.

Example 3: Energy consumption of the overall process for the production of ethanol from biomass

Example 2 illustrates which ethanol yields and consumption figures can be achieved by the process presented. The energy consumption of the overall process according to FIG. 1 was also simulated by means of Aspen +.

The Eriϊndungsgemäße method resulted from a rye amount of 3.75 kg, a DDGS amount of 1.51kg and a yeast amount of 0.11 kg based on 1 kg of ethanol. Main energy consumers are the Verfahrensschπtte distillation and drying.

Here, the following consumption figures based on 1 kg of ethanol were determined

distillation

Steam consumption [MJ / kg] 3.1

Power consumption [MJ / kg] 0.1

Sum [MJ / kg] 3.2

desiccation

Steam consumption [MJ / kg] 5.4

Power consumption [MJ / kg] 0.1

Sum [MJ / kg] 5.5

Distillation & drying

Steam consumption [MJ / kg] 8.5

Power consumption [MJ / kg] 0.2

Sum [MJ / kg] 8,7

In conventional processes for producing bioethanol from cereals, for example wheat, the specific consumption in drying and distillation is between 9.5 and 16 MJ / kg of ethanol.

In addition, ethanol production from rye is more expensive compared to wheat, for example. For example, the cost of DDGS drying is significantly higher. This fact underscores all the more the attractiveness of the described invention.

An additional economic advantage is also the fact that in addition to ethanol and the feed DDGS also valuable yeasts can be obtained. Example 4 Simulation of Butanol Yield by Aspen +

The simulation of Example 4 was modified so that no yeast was added in the fermentation, but a fermentation onsbalance was simulated (Jones, Woods, 1986) with Clostridium acetobutyhcum. After the fermentation, there is a mash containing about 1.5% by weight of butanol.

For the separation of solids after the main fermentation, which essentially represents a retention of the biomass (bacteria) due to the previously performed separation steps, a split ratio of 5: 1 (solids-free fraction vs. concentrated biomass) was likewise assumed. The concentrated biomass is optionally recruited completely in the fermentation. The resulting mash is then first fed to a distillation column, which is operated to achieve a maximum bottom temperature of about 75 ⁰ C in vacuo.

At the top of the column, the products butanol, acetone and ethanol are removed, the water content of this fraction is about 61%. The bottom product contains the remaining biomass from the secondary fermentation and about 95% of the water from the fermentation mash. In the next step, the acetone is removed from the distillate of this column in a rectification column at about 3 bar overpressure (acetone amount about 0.14 kg / h). In a further operated at about 0.8 bar overpressure column azeotropic ethanol is separated as the top product, which is dried in a second step in a pressure swing adsorption to> 99% purity. This results in an amount of ethanol of about 0.04 kg / h.

The pressures of the columns were chosen so that an energy connection can be realized.

The remaining amount of butanol and water is separated in a heteroazeotrope rectification (2 stripping columns with associated phase separation) into a pure butanol stream (about 0.49 kg / h) and a butanol-poor water stream (amount about 1.07 kg / h). The water can be used as a recycle stream in the process again.

The bottom product of the mash column is concentrated in a 4-stage evaporation to a dry matter content of about 30%. The resulting condensates are reused as Recyclmgwasser The concentrate is mixed with the separated bran (+ bowls and husks) and dried to about 90% dry matter content. The vapors of the drying run the first stage of evaporation, so that no separate steam for the operation of the evaporation is necessary. Example 5: Energy consumption of the overall process for the production of butanol from biomass

From the simulation, for example 4, the following energy consumption results for the production of 0.49 kg / h of butanol from about 3.75 kg / h of grain:

Heating the mash to liquefaction temperature: 0.5 kg / h steam consumption

- Specific steam consumption: approx. 1 kg steam / kg butanol

Distillation / separation of the organic products from the mash: 42 kg / h steam consumption

specific steam consumption: approx. 8.5 kg steam / kg butanol

Drying and evaporation

The drying was calculated as a steam-operated rotary dryer. Pro t evaporated water while about 1.3 t of steam are needed. This results in a required amount of steam of 2.6 t / h for a DDGS amount of 1.5 kg / h and a drying of 39% dry matter (mixture bran + husks + switching with concentrate from evaporation) to 90% dry matter content.

- Specific steam consumption: approx. 1.7 kg steam / kg DDGS.

Claims

claims

A process for the production of alcohol from biomass, in which the biomass is comminuted, the remaining biomass is fed to a fermentation and the alcohol is recovered from the product of the fermentation, characterized in that insoluble solid constituents and / or non-fermentable sugars from the Biomass before the

Fermentation and / or yeast or bacteria are separated after fermentation.

2. The method according to claim 1 characterized by the following steps:

a. Comminution of biomass,

b. Optional strong liquefaction and saccharification,

c. Separation of insoluble solid components and / or non-fermentable

Sugar from the biomass,

d. fermentation

e. Separation of the yeast or bacteria

f. alcohol recovery

3. The method of claim 1 or 2, wherein the biomass in the comminution to a mean particle size of 0.05 - 2 mm, preferably to an average particle size of 0.1 - 1 mm and particularly preferably from 0.1 - 0, 7 mm is crushed.

4. The method according to any one of claims 1 or 2, characterized in that the biomass is grain and the biomass is milled after comminution with water and a liquefaction and saccharification is supplied.

5. The method according to claim 4, characterized in that fractions with a lower starch content (shell fraction) and a high proportion of viscosity-increasing substances (glutinous fraction) before step b) are separated.

6. The method according to claim 1, characterized in that after liquefaction takes place saccharification

7. The method of claim 5, wherein separating the undissolved solids contained after saccharification and / or the non-fermentable sugars.

8. The method according to any one of the preceding claims, characterized in that in the separation of non-fermentable sugars anionic or cationic flocculants, acrylamides and copolymers mixtures are used.

9. The method according to any one of the preceding claims, characterized in that the mixing of the flocculant takes place as a 0.01 - 1% solution.

10. The method according to any one of the preceding claims, characterized in that 10 to 1000 ppm of flocculant are added based on solids.

11. The method according to any one of the preceding claims, characterized in that in the

Separation of the yeast anionic or cationic flocculants, preferably bentonite, silica sol and gelatin or weak to strong anionic copolymers of acrylamide and sodium acrylate in various combinations, can be used.

12. The method according to any one of claims 8 to 11, characterized in that the amount of flocculant in the Hefeabtrennung 10 - 100000 ppm based on solids.

13. The method according to claim 1, characterized in that the biomass is grain.

14. The method according to claim 1, characterized in that the biomass is rye.

15. The method according to any one of claims 1 to 14, characterized in that the separated insoluble solid components and / or non-fermentable sugars are added to a Nebenfermentation.

A process according to any of the preceding claims, wherein the syrup and / or molasses originating from sugar production are supplied to the secondary fermentation and / or the main fermentation.

17. The method of claim 12 wherein the discharged yeast and after the

Hefeabtrennung remaining low-yeast fraction together with the running off of the secondary fermentation vinification of alcohol, preferably one Are fed to distillation or rectification and a dry fraction is obtained, which can be used as feed or fuel.

18. The method according to any one of the preceding claims, are prepared in the ethanol or butanol.

19. The method according to any one of the preceding claims, is prepared in the ethanol.

20. The method according to any one of the preceding claims, wherein the butanol is prepared and after the fermentation, the bacteria are separated and completely recycled to the fermentation.