WO2009090260A2

WO2009090260A2 - Materially and energetically optimized bioethanol production process

Info

Publication number: WO2009090260A2
Application number: PCT/EP2009/050537
Authority: WO
Inventors: Wolfgang Ranfft; Werner Koschuh; Jose Neto
Original assignee: Desmet Ballestra Ethanol Gmbh
Priority date: 2008-01-17
Filing date: 2009-01-19
Publication date: 2009-07-23
Also published as: DE102008004971A1; WO2009090260A3; EP2240592A2

Abstract

The invention relates to an improved relatively economical process and a corresponding device for producing bioethanol from cereal and lignocellulose-containing biomasses in which a production line for cereal and a production line, operated simultaneously, for lignocellulose are operated as far as the saccharification stage and a specific fermentation, depending on the biomass used, and then the material streams are fed to a combined distillation and dewatering stage.

Description

Substantially and energetically optimized bioethanol production process

The invention relates to a method and a device for producing bioethanol from cereals and lignocellulose-containing biomasses according to the preambles of claims 1 and 10.

Raw materials for bioethanol production basically represent all plants that contain a correspondingly high content of fermentable substances.

In the European Economic Area, these are mainly the cereals wheat, rye and corn; Tritikale, barley, oats and millet are rarely used for this purpose. Furthermore, with the waste product of the sugar industry, molasses, a low-cost raw material in addition to sugar beets and potatoes. In other latitudes, rice, sugar cane and cassava are intensively used for alcohol production.

Great hopes are placed in this context also in the use or implementation of lignocelluloses. Lignocellulose consists of cellulose (Ce sugar, glucose), hemicellulose (C ₅ and C ₆ sugars, mainly xylose and mannose) and lignin (polymer of aromatic components); Cellulose and hemicellulose can be fermented to ethanol after appropriate pretreatment and hydrolysis; the remaining, non-fermentable fraction can be thermally converted to electricity and heat.

"Features of promising technologies for pre-treatment of lignocellulosic biomass" by Nathan Mosier and others, published in Bioresource Technology 96 (2005), page 673 -686, Elsevier publisher shows a good overview of the possibilities of pretreatment of lignocellulose, as described in Moment are common.

Sun and Cheng have in their article "Hydrolysis of lignocellulosic materials for ethanol production: a review", published in Bioresource Technologie 83 (2002), pages 1 -1 1, Elsevier Verlag reviewed the hydrolysis of lignocellulosematehal for bioethanol production.

It is well known, for example, from the protective documents DE 103210607 A1, DE 10327954 B4, EP 330686 B1, US 20050026261 A1 to obtain bioalcohol from cereals or, alternatively, to use lignocellulose according to the protective documents WO 2001060752 A1, WO 2003049538 A2 in order to obtain bioethanol. In the cases mentioned, which is also in the gray literature a digestion of lignocellulose biomass by hydrolysis in an acidic medium is used as a rule, although already in DE 3428661 C2 and the hydrolysis of crushed and mashed with solvents lignocellulosic biomass with high-tensioned water vapor is described in a Dispergerreaktor. However, a disclosure of such hydrolyzed biomass in combination with saccharified and fermented cereals - bioethanol - to work is not apparent.

From EP 105937 B1 a self-contained process for the production of alcohol from lignocellulosematehal by a combination of process steps is already known. The starting material is treated with sulfur dioxide and water under heat and pressure by the introduction of steam, mixed with alkaline solution to dissolve and remove the lignin from the cellulose content and sufficient water evaporated from the dissolved lignin for a fuel, which in turn is used as an energy source for steam generation becomes. The hydrolyzed cellulose is fermented to alcohol. In this respect, this is a single-purpose plant for the production of alcohol from lignocellulosic biomass. In addition, two other protection documents are known in which it is mentioned facultatively that different end products may be incurred. On the one hand, WO 1098041646 A1 mentions a process for utilizing biomass from agricultural crops, which is comminuted and compressed and separated into a low-solids phase and a solids-rich phase, the high-solids phase being treated with steam in overpressure. The final product is ethanol, pulp and biogas. According to WO 2007009463 A2, carbonaceous material is to be converted into ethanol by a continuous hydrothermal treatment and without the addition of chemicals. The resulting liquid and fiber fractions should be separated after this pretreatment. It is stated that the final product is fuel ethanol, animal feed and electricity or electricity.

All previous proposals have in common that they are special plants for the production of bioethanol either grain or lignocellulose. But such lines are not interoperatively coupled with each other.

It has already been mentioned in the US patent application US 2007 / 0161095A1 that, from the simultaneous use of biomass, lignocellulose and agricultural products such as cereals as starting raw materials receive various end products, for example biodiesel but also nanocomposites or electricity. However, the treatment should essentially be carried out through the participation of ionic liquids and gases with specific reaction conditions. A simultaneous parallel operation of a bioethanol plant and a lignocellulosic ethanol plant are not mentioned.

It is striking that the trend towards bioethanol in some areas means that crops are scarce or that the lignocellulose-containing materials are not always available for seasonal reasons. Therefore, the invention is based on the problem to optimize the bioethanol production from grain and lignocellulose.

The problem is solved by the features of claims 1 and 10. Further developments of the inventions are contained in the dependent claims.

The first solution of the problem comprises according to the invention a method for processing of grain and lignocellulose to bioethanol in a production line for grain and at the same time the production line for lignocellulose up to the saccharification stage and a specific fermentation depending on the biomass used is operated and then the streams into one common distillation and dehydration step. This initially saves the construction of parallel distillation and dehydration stages and allows variable use of certain amounts of raw materials in one line or the other while jointly processing the applied products and energies.

In one embodiment, to improve the economics of the lignocellulose processing line, after hydrolysis of the biomass, excess steam may be withdrawn and used elsewhere in the production line or withdrawn for use in the grain production line.

After the hydrolysis stage in the production line for the processing of lignocellulose resulting liquid phase can according to the invention largely separated from a solid phase and the liquid phase of a biogas plant are supplied for further optimal utilization. The residues after distillation and dewatering (vinasse) can be fed to this biogas plant, in which then vinasse and the hemicellulose-rich liquid phase to biogas according to the invention are implemented together.

Preferably, the biogas can be used for power generation and the use of electricity in the vicinity or the production lines or mixed with the natural gas or city gas via a low-pressure gas distribution network.

The process of the invention is preferably carried out so that the lignocellulose is digested in the hydrolysis step so that the hydrolyzed mass has a largely neutral pH, preferably in the range of pH 5 to 7 by dispensing with the addition of acids or alkalis.

The process makes it possible to feed the two co-operating bioethanol plants with variable amounts of cereals and lignocellulose-containing biomasses, the proportion of lignocellulose, based on the amount of cereal used, being from 1 to a maximum of 50% by weight. So it can, for example, deliver the grain and straw at the same job site of cereal farmers. On the other hand, any lignocellulosic biomass can be processed.

Preferably, the final ethanol concentration will have a final ethanol concentration of 4 to 19 volume percent both in the processing of grain and in the processing of lignocellulose prior to the distillation step.

The second solution relates to a device for processing the biomass types cereals and lignocellulose to bioethanol, in particular for Carrying out the method described above, wherein at least one each arranged in series device for pretreatment, digestion, saccharification, fermentation of saccharified masses for each Biomassenart be operated simultaneously or in parallel, but by only one common charge for both lines distillation apparatus and dewatering apparatus for concentrating the obtained Ethanols supplement finds.

The device according to the invention is designed so that both lines are coupled to a biogas plant for receiving vinasse from the distillation device and liquid phases from one of the hydrolyzing device for lignocellulose downstream separation device for solids and liquids.

The hydrolysis part of the lignocellulose line can be connected to a discharge device of steam to the grain line and the biogas plant can be coupled to a power generation plant.

The invention is best illustrated by comparing the state of the art in widespread manufacturing processes for the recovery of ethanol from lignocellulose and from cereals, respectively, and contrasting them with the present inventive concept, described by means of diagrams of the production process.

At the moment there are three common methods for co-production of ethanol, heat and electricity from lignocelluloses, which however can not be represented industrially for the most diverse, mostly financial reasons.

In the future, large bioethanol plants expect production costs of 0.26 Euro / l (12.4 Euro / GJ) and further reduction due to technological developments to 0.18 Euro / l (8.6 Euro / GJ). FIGS. 1-4 show various methods for producing ethanol according to the prior art.

Figure 1 shows a biomass process developed by the "National Renewable Energy Laboratory, USA": combination of steam pretreatment and mild acid hydrolysis of the hemicellulose fraction followed by enzymatic hydrolysis of the cellulose, with cellulose hydrolysis and fermentation of xylose and glucose monomers proceeding therein Fermentation organism is the genetically modified bacterium Zymomonas mobilis.

Fig. 2 shows a biomass process developed by "BC International Corporation, Canada": two-stage acid hydrolysis (first stage releases hemicellulose sugar, second stage cellulose-sugar),

Figure 3 shows a biomass process developed by "Logen Corporation, Canada": steam digestion with dilute acid for the release of the hemicellulose sugars and subsequent hydrolysis of the cellulose.

This, according to the state of the art, typical ethanol recovery from biomass is described in REITH, J.H .; VEENKAMP, J.M. and VAN REE, R. (2001): Co-production of bioethanol, electricity and heat from biomass wastes: potential and R & D issues. ECN, Nedalco, ATO contribution to the First European Conference on Agriculture & Renewable Energy; 6-8 May 2001, RAI, Amsterdam, The Netherlands, on the Internet on 16.01.2008,14: 17: 14 at http://www.ecn.nl/docs/library/report/2001/rx0101 1.pdf , In the fermentation, genetically modified microorganisms are probably used.

In Fig. 4, the essential procedural steps are now - after the general state of the art known per se - shown for bioethanol production based on cereals. After preparation of the raw material according to the process steps shown - storage / cleaning, grinding, mashing - follows the conversion of carbohydrates Liquefaction, saccharification - in sugars usable for the microorganism, which are then converted into alcohol by fermentation.

In the subsequent downstream part of the process, the alcohol is separated (distillation) and further concentrated (dewatering) for

End product bioethanol. The residue from the distillation, on the other hand, can either be disposed of or further processed in various ways.

Figure 5 shows the invention with the simultaneously and at one site operated in parallel plants for ethanol production from grain (upper part of the figure) or lignocellulose (lower part of the figure) and their linkage of the invention in a schematic process plan, which roughly divides the individual treatment stages.

Wheat, corn, rye, triticale, barley, or sugar-containing raw materials such as sugar beet, potatoes, molasses, etc. can be used as the raw material. Cereal straw, wood, grass, bagasse, waste paper, green waste, etc. are used as raw materials containing lignocellulose. For example, a farmer growing energy crops can supply both the threshed grain and the straw (fresh cornhoppers).

Description of the grain line:

The grain, here for example triticale, with the highest possible starch and low protein content is first ground in a grinder. Depending on the raw material, the grain is reduced to, for example, a particle size of less than 1 mm. In contrast to the prior art, bran accumulating here is not screened out.

In the next reactor, the usual mashing of the ground material, followed by the liquefaction in another device. There will be a

Mixture of milled cereal with water and an enzyme solution reached. After heating to a predeterminable liquefaction temperature (depending on the type of liquefaction enzyme) of 50-15 ° C and a residence time of 0.5-2.0 hours as a function of enzyme concentration, the starch is degraded in a neutral or slightly basic environment. The pH range is adjusted to 5.0-6.5 depending on the liquefaction enzyme to achieve good degradation of the starch in dextrins. The following container is a saccharification device. By addition of saccharification enzyme, the degradation of dextrins into fermentable mono-, di-, and trisaccharides is effected while maintaining a predetermined, monitored pH range, depending on the liquefaction enzyme, pH 4.0-5.5. In this case, depending on the liquefaction enzyme, with a temperature of 50- 65 ° C driven at a residence time of 1 - 48 h, depending on the enzyme concentration.

In the following facility, the fermentation stage, the fermentable sugar is converted into ethanol and carbon dioxide by adding yeast. This process lasts for 12-50 hours and provides a final ethanol concentration of, for example, 5.0-13.0, preferably in the range of about 4-19, weight percent. Parallel to the anaerobic fermentation, a partial flow of the yeast is aerated aerobically in a side stream of another container, so that sufficient Hefezellsubstanz is formed. Thereafter, the biomass is conveyed to a distillation device.

Description of the Liqnocellulosine line:

The abandoned biomass, for example, straw, is using mills and

Shredders shredded to a particle size of 0.5 - 10 cm.

The shredded straw is suspended in a reactor by addition of water in a suspension, then by means of direct steam, without addition of chemicals and alkalis or acids, heated to 160-220 ° C, in

Dependence on the types of raw materials and with residence times of 10- 120

Minutes unlocked. The bulk of the hemicellulose goes into

Solution. The lignocellulose is digested in the hydrolysis step so that the hydrolyzed mass has a largely neutral pH, preferably in the range of pH 5 to 7. In the process itself, acids are released, which cause a slight pH drop, but should not and will not leave the said pH range. This has several advantages. By dispensing with the addition of chemicals, no byproducts hindering the following process can arise. In the said pH range, no or only a slight attack on the materials of the plant parts is observed, which increases the profitability of production by extending the life of the plant.

After this hydrolysis, the mass is cooled to the desired saccharification temperature in two flash vessels connected in series. The steam thus obtained is used, for example, in the grain-based plant part as shown by a dashed arrow in FIG. 5. The use of the extracted steam elsewhere in this plant and in the grain line is also considered to be inventive.

In the next process step, a solid / liquid separation of the cooled mass is carried out by means of a filter, preferably a suitable bandpass filter or a screw press. The liquid phase is pumped into a biogas plant, fed to the solid phase of the saccharification.

The saccharification is achieved by adding commercial cellulases. For saccharification, the residence time of about 48 h at the predeterminable temperature of about 40-60 ° C, depending on the type of enzyme used. The cellulose is enzymatically degraded into glucose monomers.

The following process step is the fermentation; After saccharification, a standard Saccharomyces fermentation is carried out at 30-40 ° C, which ends in a final ethanol concentration of, for example, about 5% by volume. Specifically, because of the frequent rejection of genetically modified biofuels, no genetically modified material or microorganisms suitable for this purpose should be used here.

Now the product obtained is pumped to the distillation device.

Description of the process steps common to both lines: The alcoholic fermented solution from the grain line and the fermented masses from the lignocellulosic line are combined and distilled in a first step, a mashing column, to about 50% by weight ethanol.

In the next step, the ethanol-Λ / vasergic mixture obtained is then concentrated in a rectification device to about 90 wt .-% ethanol. The solution is further concentrated to at least 99.0% by volume of ethanol by means of a further dewatering treatment, for example an entrainer distillation or by molecular sieve technologies or pervaporation.

The residue obtained in these stages, the so-called vinasse, is taken off at the bottom of the mash column and fed to the biogas plant. In the prior art it is attempted to obtain methane via sewage sludge or to introduce the vinasse into animal feed. According to the invention, however, the entire vinasse in the biogas plant is reacted with the hemicellulosic liquid phase from the lignocellulosic line into biogas. The resulting biogas will then continue to be used to generate electricity. The process from the biogas production can - as is well known - so discharged or be fed to another, aerobic treatment.

Claims

claims:

1. A process for processing of cereals and lignocellulose to bioethanol, characterized in that a production line for grain and a simultaneously operated production line lignocellulose up to the saccharification stage and a specific fermentation depending on the biomass used and then the streams in a common distillation and Drainage step.

2. The method according to claim 1, characterized in that at the production line for processing lignocellulose after hydrolysis of the biomass excess steam in this production line is used elsewhere or deducted for use in the production line for the grain.

3. The method according to claim 1, characterized in that after the hydrolysis stage in the production line for the processing of lignocellulose, a liquid phase largely separated from a solid phase and the liquid phase of a biogas plant is supplied.

4. The method according to any one of the preceding claims, characterized in that the residues are fed to the biogas plant after the distillation and dewatering (stillage).

5. The method according to any one of the preceding claims, characterized in that in the biogas plant vat and the hemicellulose rich liquid phase are converted to biogas.

6. The method according to claim 5, characterized in that the biogas is used to generate electricity.

7. The method according to claim 1, characterized in that the lignocellulose is digested in the hydrolysis step so that the hydrolyzed mass has a largely neutral pH, preferably in the range of pH 5 to 7 by dispensing with the addition of acids or alkalis.

8. The method according to claim 1, characterized in that the two simultaneously operated with each other bioethanol plants are charged with variable amounts of cereals and lignocellulose biomass, wherein the proportion of lignocellulose, based on the amount of cereal used, is 1 to a maximum of 50 weight percent.

A process according to any one of the preceding claims, characterized in that the final ethanol concentration has a final ethanol concentration of 4-19% by volume both in the processing of cereals and in the processing of lignocellulose prior to the distillation stage.

10. An apparatus for processing the biomass species cereals and lignocellulose to bioethanol, in particular for carrying out the method according to one of the preceding claims, wherein at least one of the devices comprising at least one in series device for pretreatment, digestion, saccharification, fermentation of saccharified masses for each biomass species can be operated simultaneously or in parallel, characterized by only one distillation apparatus and dewatering apparatus, which can be jointly charged for both lines, for concentrating the ethanol obtained.

1 1. Apparatus according to claim 10, characterized in that both lines are coupled to a biogas plant for receiving vinasse from the distillation device and liquid phases from one of the hydrolyzing device for lignocellulose downstream separation device for solids and liquids.

12. The apparatus of claim 10 or 1 1, characterized in that the hydrolysis part of the lignocellulose line is connected to a discharge device of steam to the grain line.

13. The apparatus of claim 10, 11 or 12, characterized in that the biogas plant is coupled to a power plant.