JP2014171417A - Bioethanol recovering method and bioethanol recovering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bioethanol recovering method and a bioethanol recovering system capable of preventing the entrainment of odorous components when recovering ethanol from fermentation liquid.SOLUTION: A bioethanol recovering method comprises an odorous component removal process II for removing odorous components from fermentation liquid as a preliminary process of an ethanol recovering process III for recovering ethanol from the fermentation liquid. A bioethanol recovering system comprising at least ethanol recovering means for recovering ethanol from the fermentation liquid, includes odorous component removal means for removing the odorous components from the fermentation liquid in the preliminary stage of the ethanol recovering means.

Description

  The present invention relates to a bioethanol recovery method and recovery system, and more particularly to a bioethanol recovery method and recovery system that can prevent odor components from being accompanied when ethanol is recovered from a fermentation broth.

  The energy production system that relies on fossil fuels so far continues to cause an increase in greenhouse gases such as carbon dioxide on the earth. On the other hand, not only in Japan, but also on the earth, there is abundant biomass, which is an unused biological organic resource such as plants, and it continues to accumulate every year.

  Since plants absorb carbon dioxide, using biomass as an energy resource can balance the carbon cycle on the earth and reduce the use of fossil resources, resulting in a reduction in greenhouse gases. Therefore, various developments are being actively promoted.

  Examples of energy resources obtained from biomass include methane gas, hydrogen gas, ethanol, and butanol. Among these, ethanol (bioethanol) (patent document 1), which can be produced by fermentation reaction with microorganisms such as yeast at normal temperature and normal pressure, has an amount of harmful substances in the exhaust gas accompanying combustion compared to gasoline. It is regarded as particularly important as an alternative liquid fuel for petroleum because of its small amount.

  However, since the concentration of ethanol produced by the fermentation method is as low as about 15% by mass in the fermentation broth, in order to use it as a liquid fuel, a step of recovering it from the fermentation broth is indispensable.

  FIG. 5 is a bioethanol recovery system according to the prior art.

  The fermented liquor containing ethanol produced in the fermenter 201 is introduced into the mash tower 202, and ethanol is separated and recovered from the fermented liquor by distillation.

  Reference numeral 203 denotes an evaporator that introduces the bottom liquid (non-distilled product) of the mash column 202 and recovers ethanol contained therein by distillation. The recovered ethanol is merged with the distilled ethanol from the mash column 202. .

  The distilled ethanol is then introduced into the rectification column 204, where ethanol is concentrated by further distillation.

  Thereafter, the concentrated ethanol is further introduced into the adsorption dehydration tower 205, where final purification is performed, and then the ethanol is stored in the purified ethanol storage tank 206.

JP 2009-011198 A

  The present inventor has focused on the fact that, in a conventional recovery process that depends on a distillation method, odor components derived from alcohol-fermenting bacteria, fermentation raw materials, and the like are accompanied with distilled ethanol. Even if the refined ethanol satisfies the specification purity as a liquid fuel or the like, the presence of such an odor causes anxiety and discomfort to the user.

  Therefore, an object of the present invention is to provide a bioethanol recovery method and a recovery system that can prevent odor components from being accompanied when ethanol is recovered from a fermentation broth.

  Other problems of the present invention will become apparent from the following description.

  The above problems are solved by the following inventions.

1.
A bioethanol recovery method comprising a odor component removal step of removing an odor component from the fermentation broth as a pretreatment of an ethanol recovery step of recovering ethanol from the fermentation broth.

2.
2. The bioethanol recovery method according to 1, wherein the odor component removal step further removes an odor component release source in addition to the odor component.

3.
2. The bioethanol recovery method according to 1 above, further comprising an odor component release source removal step of removing an odor component release source from the fermentation broth as a pretreatment of the odor component removal step.

4).
In a bioethanol recovery system comprising at least an ethanol recovery means for recovering ethanol from a fermentation broth,
A bioethanol recovery system comprising an odor component removing means for removing an odor component from the fermentation broth before the ethanol recovery means.

5.
5. The bioethanol recovery system according to 4, wherein a rotating conical column is used as the odor component removing means.

6).
6. The bioethanol recovery system according to 4 or 5 above, further comprising an odor component release source removal means for removing an odor component release source from the fermentation broth before the odor component removal means.

7).
7. The bioethanol recovery system according to 6, wherein a solid-liquid separation unit is used as the odor component release source removal unit.

8).
The bioethanol recovery system according to any one of 4 to 7, wherein a rotating conical column is used as the ethanol recovery means.

9.
9. The bioethanol recovery system according to any one of 4 to 8, further comprising ethanol purification means for removing impurities from the ethanol recovered by the ethanol recovery means for purification.

10.
10. The bioethanol recovery system according to 9, wherein membrane separation means is used as the ethanol purification means.

  ADVANTAGE OF THE INVENTION According to this invention, the collection | recovery method and collection | recovery system of bioethanol which can prevent the accompanying of the odor component at the time of collect | recovering ethanol from a fermented liquid can be provided.

Process drawing showing an example of a bioethanol recovery method according to the present invention Explanatory drawing which shows an example of the bioethanol recovery system according to the present invention Schematic cross-sectional side view showing a configuration example of a first rotating conical column that is an odor component separating means Schematic cross-sectional side view showing a configuration example of a second rotating conical column that is an ethanol recovery means Bioethanol recovery system according to the prior art

  The present invention prevents odor components from being accompanied when ethanol is recovered from a fermentation broth.

  The odor component that can be prevented from being accompanied by recovered ethanol according to the present invention is obtained by removing ethanol from components that can be sensed by humans, for example, esters such as ethyl acetate, propanol, butanol, amyl alcohol, etc. Preferred examples include polyhydric alcohols, grain odor components, and yeast odor components.

  Although the fermentation broth used for this invention is explained in full detail behind, it is preferable that it is a fermentation broth containing ethanol (bioethanol) produced | generated by fermenting biomass with alcohol-fermenting bacteria in a fermenter.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a process diagram showing an example of a bioethanol recovery method according to the present invention.

  In FIG. 1, I is an odor component emission source removing step for removing an odor component emission source from a fermentation broth, II is an odor component removal step for removing an odor component from a fermentation broth, and III is an odor component release. This is an ethanol recovery step for recovering ethanol from the fermentation broth from which the odor component release source and the odor component have been previously removed by the source removal step I and the odor component removal step II.

  In the example of FIG. 1, the fermentation broth is first subjected to an odor component release source removal step I, where the odor component release source is removed from the fermentation broth.

  The odor component release source is not particularly limited as long as it is a release source capable of releasing odor components, and preferred examples include cereal residues and microorganisms such as yeast.

  Since these odor component release sources can continuously release the odor component, from the viewpoint of more reliably achieving the effects of the present invention, as shown in the figure, before the odor component removal step II, the odor component release source removal step Preferably I is performed. That is, on the contrary, when the odor component removal step II is performed prior to the odor component release source removal step I, a new odor component is generated from the odor component release source during the processing in the odor component removal step II. May be released. Therefore, even if the odor component release source is removed in the odor component release source removal step I, the released odor component may remain as a new odor component in the fermentation broth, which is not preferable.

  On the other hand, as shown in FIG. 1B, it is possible to remove the odor component and the odor component emission source (odor component and odor component emission source removal step V) in one step. That is, during the odor component removal process, the amount of odor components released from the odor component release source is a problem amount, and the odor components in the fermentation broth sent to the ethanol recovery step III can be removed, or When the odor component emission source can be removed together with the removal of the components, the odor component emission source removal step I and the odor component removal step II do not have to be provided as separate steps, as shown in FIG.

  According to the knowledge of the present inventor, since the odor component release source is contained in the fermentation liquid as a solid content, it is preferable to use the solid-liquid separation means as the odor component removal means in the odor component release source removal step I. it can. A preferred configuration example of such solid-liquid separation means will be described in detail later.

  In the odor component release source removal step I, a part of ethanol may be removed from the fermentation solution together with the odor component release source. Therefore, it is also preferable to provide an ethanol return step (not shown here) that separates and recovers ethanol removed together with the odor component release source and returns it to the fermentation broth.

  The fermentation broth from which the odor component has been removed by the odor component release source removal step I is then subjected to the odor component removal step II, where the odor component is removed from the fermentation broth.

  The odor component removal means in the odor component removal step II is not particularly limited as long as it can remove the odor component, but it is preferable to use one having high selectivity for removing the odor component with respect to ethanol. Since odor components are usually more volatile than ethanol, using this property, the fraction consisting mainly of odor components in the fermentation broth is used at a relatively low temperature (that is, ethanol volatilization is suppressed). In particular, a means for volatilizing and removing ethanol at a high temperature and extracting it by volatilizing ethanol at a high temperature can be preferably used. Specifically, a two-stage rotating cone column described later can be preferably used.

  Also, in this two-stage rotating conical column, when the odor component emission source is separated into the discharge line on the side of hardly volatile substances such as water in the second stage column and separated into ethanol products without adverse effects, solid-liquid separation, etc. The odor component emission source removing step I can be omitted.

  Next, in both the example of FIG. 1 (a) and the example of FIG. 1 (b), the fermentation liquid from which the odor component release source and the odor component have been removed is subjected to the ethanol recovery step III, where the fermentation liquid The ethanol is recovered from.

  The ethanol recovery means in the ethanol recovery step III is not particularly limited as long as it can recover ethanol from the fermentation broth, but from the viewpoint of more prominently achieving the effects of the present invention, particularly means for volatilizing and recovering ethanol, particularly A rotating conical column described later can be preferably used.

  A means for volatilizing and recovering ethanol, particularly a rotating conical column, is excellent in ethanol recovery efficiency, and at the same time, is excellent in recovery efficiency of volatile components including odor components other than ethanol. For this reason, when the odor component is contained in the fermentation broth, there is a disadvantage that a large amount of the odor component is entrained in the recovered ethanol. On the other hand, in the present invention, the odor components in the fermentation broth and further the odor component release source capable of continuously generating the odor components are removed in advance, so that ethanol is volatilized and recovered. By using a means, particularly a rotating conical column, it is possible to bring out an advantage of excellent ethanol recovery efficiency in a state where odor components are prevented from being entrained in the recovered ethanol.

  In addition, the rotating conical column is significantly energy-saving compared to the conventional distillation method, which is an energy-intensive process that is said to consume about half the energy of ethanol produced.

  As described above, ethanol from which odor components are prevented is recovered from the ethanol recovery step III.

  In the present invention, it is preferable that the ethanol recovered in the ethanol recovery step III is further subjected to the ethanol purification step IV.

  The ethanol purification means in the ethanol purification step IV is not particularly limited as long as it can be purified (ethanol concentration increased) by removing impurities (substantially water) from the ethanol. In particular, a membrane separation means is preferably used. be able to.

  According to the knowledge of the present inventor, some of the odor components that can be contained in the fermentation broth may be easily adsorbed to the separation membrane provided in the membrane separation means, and there is a concern of promoting the deterioration of the separation membrane. It was. On the other hand, in the present invention, since the odor component is removed in advance, the degree of freedom in selecting the material of the separation membrane can be expanded and the durability thereof can be improved. In particular, when a rotating cone column is used as an ethanol recovery means in the ethanol recovery step II, organic acids such as acetic acid are also efficiently removed, and therefore, deterioration of the separation membrane due to organic acids can be prevented.

  In addition, the membrane separation means has an advantage that energy saving can be realized as compared with a distillation column or the like that requires a large amount of heat energy. A preferred configuration example of such membrane separation means will be described in detail later.

  Next, a bioethanol recovery system for carrying out the bioethanol recovery method according to the present invention described above will be described.

  FIG. 2 is an explanatory diagram showing an example of a bioethanol recovery system according to the present invention.

  In FIG. 2, 1 is a fermenter, 2 is a solid-liquid separation means (odor component release source removing means), 3 is an evaporator (ethanol return means), and 4 is a first rotating cone column. (Odor component separation means), 5 is a second rotating conical column (ethanol recovery means), 6 is an ethanol purification means, and 7 is a purified ethanol storage tank.

  The fermenter 1 ferments the introduced fermentation raw material with alcohol-fermenting bacteria to produce a fermentation liquid containing ethanol (bioethanol).

  Although it does not specifically limit as a fermentation raw material introduce | transduced into the fermenter 1, The biomass etc. which originate in a grain etc. can be illustrated preferably.

  The fermentation temperature in the fermenter 1 is preferably in the range of 30 ° C to 45 ° C. At such a fermentation temperature, the production of ethanol is promoted, and at the same time, the amount of odorous components or odorous component release sources is increased. Therefore, the effect of the present invention is more likely to be achieved.

  The fermented liquor produced | generated in the fermenter 1 is introduce | transduced into the solid-liquid separation means 2 which is an odor component discharge | release source removal means.

  In the illustrated example, the solid-liquid separation unit 2 is configured to sequentially separate the fermentation liquid into a solid-liquid separation by a continuous strainer 21, a centrifugal separator 22, an oil layer separator 23, and a membrane separation unit 24.

  The fermentation liquor is first introduced into the continuous strainer 21 where a relatively large odor component release source is removed as a solid content.

  The fermentation broth that has passed through the continuous strainer 21 is then introduced into the centrifuge 22.

  The centrifuge 22 is not particularly limited, but it is preferable to use a continuous centrifuge, and specifically, a vertical centrifuge or a horizontal centrifuge (decanter) can be preferably exemplified. A vertical centrifuge is preferable from the viewpoint of highly removing microorganisms such as yeast as a source.

  The fermentation broth from which the odor component release source has been removed in the centrifuge 22 is then introduced into the oil layer separator 23. Here, the odor component release source (or odor component) that exists as a suspended matter (such as oil) that cannot be removed by centrifugation is removed from the fermentation broth.

  The fermented liquor that has passed through the oil layer separator 23 is then introduced into the membrane separation means 24, where further odor component release sources (relatively small) are removed.

  The separation membrane provided in the membrane separation means 24 is not particularly limited, but a microfiltration membrane (MF membrane), an NF membrane, an ultrafiltration membrane (UF membrane) or the like can be appropriately selected and used. Is preferred.

  The fraction on the solid side containing the odor component release source removed by the continuous strainer 21, the centrifugal separator 22, the oil layer separator 23 and the membrane separation means 24 is introduced into the evaporator 3 which is an ethanol return means.

  The evaporator 3 collects ethanol from the solid fraction by distillation. The recovered ethanol is returned to the fermentation broth by the return pipe 31.

  The return position by the return pipe 31 is preferably the rear stage of the solid-liquid separation means 2 and the front stage of the first rotating conical column (odor component separation means) 4. On the other hand, the residue after distillation in the evaporator 3 is suitably used, for example, as feed or feed additive.

  The solid-liquid separation means 2 does not necessarily need to be constituted by the continuous strainer 21, the centrifugal separator 22, the oil layer separator 23, and the membrane separation means 24, and may be constituted by combining one or more of them. It is also preferable to use a sedimentation tank or the like instead of the continuous strainer 21.

  The fermentation broth from which the odor component release source has been removed by the solid-liquid separation means 2 is then introduced into the first rotating cone column 4 which is the odor component separation means.

  The first rotating conical column 4 brings the introduced fermentation liquid into contact with the carrier gas and countercurrent gas-liquid, and volatilizes and removes odor components in the carrier gas.

  A configuration example of a rotating cone column used as the first rotating cone column 4 in the present invention will be described with reference to FIG.

  FIG. 3 is a schematic sectional side view of the first rotating conical column 4.

  Reference numeral 41 denotes a rotating cone column apparatus, in which a housing 102 is provided in a sealable tower-shaped main body 101.

  The housing 102 has a liquid inlet 110a for introducing the fermented liquid at the upper part and a gas outlet 120b for discharging the carrier gas, and a liquid outlet 110b for discharging the processed fermented liquid at the lower part. And a gas inlet 120a for introducing a carrier gas.

  Reference numeral 103 denotes a rotatable central shaft spanned from the upper side to the lower side in the housing 102, and 103 a is a motor for rotating the central shaft 103.

  A first inversion cone 104 that is rotatable with the rotation of the central shaft 103 is attached to the central shaft 103.

  The first inversion cone 104 is configured by a vertically inverted cone, that is, a plate-shaped conical surface having a curved surface that is not the bottom surface of the cone with the apex facing downward. The rotation axis of the first inversion cone 104 is coaxial with the central axis 103.

  The first inversion cone 104 is extended so as to leave a gap that allows the liquid to flow between the inner wall of the housing 102.

  Moreover, it is preferable that at least one fin 104 a extended from the lower surface is provided on the lower surface of each first inversion cone 104.

  The central shaft 103 is provided with a plurality of such first inversion cones 104 at a predetermined pitch in the vertical direction (the axial direction of the central shaft 103).

  Reference numeral 105 denotes a second inversion cone extended from the inner wall of the housing 102 so as to be adjacent to the lower side of the first inversion cone 104.

  The second reversing cone 105 is also configured by a vertically inverted cone, that is, a plate-shaped conical surface of a curved surface that is not the bottom surface of the cone with the apex facing downward. The second reversing cone 105 is fixed to the housing 102 side and holds a gap that allows the liquid to flow between the first reversing cone 104 and the first reversing cone 104. They are arranged in parallel.

  The vicinity of the apex of the second reversing cone 105 is notched, thereby forming a gap that allows the liquid to flow through the central axis 103.

  A plurality of such second inversion cones 105 are provided on the inner wall of the housing 102 in the vertical direction at the same predetermined pitch as the first inversion cones 104.

  In the illustrated example, a plurality of first inversion cones 104 and a plurality of second inversion cones 105 are alternately arranged along the vertical direction one by one through a gap that allows liquid to flow. Yes.

  Reference numeral 130 denotes a jacket (temperature adjusting means) for keeping the temperature in the housing 102 at a predetermined temperature. The jacket 130 has an inlet 130a and an outlet 130b for cold water or hot water.

  In use, the fermentation liquid is supplied to the upper part of the housing 102 of the main body 101 through the liquid inlet 110a, and a carrier gas for recovering odor components from the fermentation liquid is supplied into the housing 102 through the gas inlet 120a. Supply to the bottom.

  The central shaft 103 is rotated by the power of the motor 103a while at least a part of the supplied fermentation broth stays in the housing 102.

  In the housing 102, when the fermented liquid flowing from the liquid inlet 110 a to the liquid outlet 110 b flows into the surface of the first inversion cone 104 on the side of the central axis 103, the fermented liquid is moved outward (with the central axis 103 with the rotation of the first inversion cone 104. In the opposite direction). Next, the fermented liquid dispersed outward flows into the surface opposite to the central axis 103 of the lower second inversion cone 105, and inwards (in the direction of the central axis 103) along the taper of the surface. It is made to flow down.

  The fermented liquor that has flowed down further flows into the surface of the first inversion cone 104 provided on the lower side on the side of the central axis 103, descends the inside of the housing 102 while repeating the same process as described above, and the lower liquid outlet 110b. Head to.

  On the other hand, the carrier gas supplied to the lower part in the housing 102 passes between the plurality of first inversion cones 104 and the second inversion cones 105, that is, reverses the same path as the flow of the fermentation broth described above. However, the inside of the housing 102 is raised and headed toward the upper gas outlet 120b.

  In such a process, the flow of the fermentation broth is brought into countercurrent contact with the flow of the carrier gas directed in the opposite direction, and odor components in the fermentation broth are extracted into the gas.

  The fermentation liquid from which the odor component is removed and the carrier gas containing the odor component from the fermentation liquid are respectively recovered from the liquid outlet 110b and the gas outlet 120b.

  From the standpoint of highly removing odor components, a return mechanism for returning the fermentation liquor from the liquid outlet 110b to the first rotating cone column 1 may be provided to perform repeated processing.

  In the present invention, the operating conditions of the first rotating conical column 4 are preferably such that the temperature in the housing 102 is in the range of 20 ° C. or higher and lower than 40 ° C., and the pressure is in the range of −90 kPaG to +10 kPaG. Is preferred. In addition, it is also preferable that the inside of the housing 102 is set to approximately normal temperature (room temperature) and approximately normal pressure (atmospheric pressure) without performing temperature / pressure adjustment.

  The temperature in the housing 102 can be set by, for example, the jacket (temperature adjusting means) 130 described above. The pressure setting can be adjusted by, for example, the power of the vacuum pump 43 for circulating the carrier gas.

  The carrier gas from the gas outlet 120b is introduced into the condenser 42, and by cooling it, the liquid odor component is trapped.

  In particular, as shown in the figure, when the carrier gas is circulated and used, the carrier gas returned into the housing 102 is introduced, and the odor removing means 44 for removing the odor component remaining in the gas is provided. It is also preferable to provide. The odor removing means 44 is not particularly limited, but for example, a deodorizing material column or the like can be preferably used.

  The fermentation liquid from which the odor component is removed by the first rotating cone column 4 is recovered from the liquid outlet 110b and then introduced into the second rotating cone column 5 which is an ethanol recovery means.

  FIG. 4 shows a configuration example of a rotating cone column used as the second rotating cone column 5 in the present invention.

  FIG. 4 is a schematic cross-sectional side view of the second rotating conical column 5, and the same reference numerals as those in FIG. 3 denote the same components.

  The second rotating cone column 5 basically has the same configuration as that of the first rotating cone column 1, but instead of the odor component to be collected in the first rotating cone column 1, ethanol is used here. Can be collected.

  That is, the second rotating conical column 5 causes the introduced fermentation liquor to come into contact with the carrier gas introduced by the vacuum pump 53 in a countercurrent gas-liquid contact, and the ethanol is volatilized in the carrier gas to condense ethanol. Separation and recovery to 52.

  In the present invention, the operating conditions of the second rotating conical column 5 are such that the temperature in the housing 102 is preferably in the range of 40 ° C. or higher and 79 ° C. or lower, and the pressure is in the range of −90 kPaG to +10 kPaG. Is preferred.

  In the present invention, the odor component release source and the odor component in the fermentation liquid are removed in advance by the solid-liquid separation means 2 and the first rotating cone column 4, so that the ethanol recovered in the second rotating cone column 5 is recovered. In addition, the presence of odor components is highly prevented.

  The ethanol recovered in the second rotating cone column 5 is then introduced into the ethanol purification means 6 to remove impurities (substantially water).

  In the illustrated example, the ethanol purification means 6 includes a membrane separation means. Specifically, the ethanol purification means 6 is configured to sequentially purify ethanol by the pervaporation deorganic membrane device 61 and the dehydration membrane device 63.

  The pervaporation deorganic membrane device 61 includes a deethanol membrane that can selectively permeate ethanol, and a permeate side region of the deethanol membrane is connected to a vacuum pump 65 and maintained in a reduced pressure state. .

  As the deethanol membrane provided in the pervaporation deorganic membrane device 61, a membrane capable of expressing the function of selectively permeating ethanol by refusing the access of water to the membrane surface and allowing the approach of ethanol is used. For example, a hydrophobic zeolite separation membrane can be preferably used.

  As the hydrophobic zeolite separation membrane, for example, a membrane composed of artificial silicalite is preferably used rather than natural zeolite, and these are used after further appropriately hydrophobizing the surface if necessary.

  As the hydrophobized zeolite separation membrane, a hydrophobic zeolite, for example, a silicalite membrane surface in which a polymer such as an aliphatic hydrocarbon or titanium is introduced can be preferably used. When a titanosilicate membrane obtained by substituting a part of the silica with titanium is excellent in ethanol separation efficiency, it is possible to remarkably exhibit the durability improvement effect due to the removal of the odor component in advance.

  The form of the deethanol membrane is not particularly limited, and for example, a hollow fiber membrane or a flat membrane can be preferably used.

  By supplying ethanol to the pervaporation deorganic membrane device 61, the ethanol is separated in a vaporized state on the permeation side through the deethanol membrane.

  In the present invention, the pervaporation deorganic membrane device 61 generates a purified product that has been purified to an ethanol concentration of preferably 85% by mass or more on the permeation side of the deethanol membrane.

  In order to promote the separation of ethanol, it is also preferable to replace the permeate side with a carrier gas.

  62 is a vapor compressor, which is preferably 100 ° C. or higher, more preferably 120 ° C. or higher by adiabatically compressing ethanol vapor generated on the permeation side of the pervaporation / deorganic membrane device 61, The dehydration efficiency of the dehydration membrane provided in the dehydration membrane device 63 is improved. If the vapor compressor 62 is used, heating can be performed with a small energy consumption, which is preferable in the present invention.

  The ethanol that has passed through the vapor compressor 62 is supplied to a dehydration membrane provided in the dehydration membrane device 63 in the form of a mixed vapor containing water as an impurity.

  The dehydration membrane included in the dehydration membrane device 63 selectively permeates water, thereby dehydrating water to the permeation side of the membrane. This transmission side region is kept in a reduced pressure state by being connected to the vacuum pump 67.

  The dehydration membrane is not particularly limited, and for example, a zeolite membrane subjected to hydrophilic treatment can be preferably used.

  The ethanol supplied to the dehydration membrane is usually required to have a sufficiently high ethanol concentration. However, in the present invention, as described above, the ethanol concentration from the pervaporation deorganic membrane device 61 is preferably ethanol. Is purified to a range of 85% by mass or more, and thus a dehydration membrane can be suitably applied.

  Purified ethanol that has passed through the dehydration membrane device 63 is sucked into the vacuum pump 65, introduced into the cooler 64, condensed, and then stored in the purified ethanol storage tank 7.

  The water separated by the dehydration membrane device 63 is introduced into the cooling device 66 by being sucked by the vacuum pump 67, condensed, and then stored in a separation water tank (not shown) as necessary.

  It is also preferable to use a dehydration tower instead of the dehydration membrane device 63 described above.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

Example 1
Using the bioethanol recovery system shown in FIG. 2, ethanol was recovered from the fermentation broth and further purified.

  Table 1 shows the material balance and composition at locations indicated by A to H below. The locations indicated by A to H below correspond to the locations indicated by reference signs A to H in FIG.

A: Fermentation liquid after fermenter 1 B: Fermentation liquid after odor component release source removal means 2 C: Return liquid in return pipe 31 after evaporator 3 D: Fermentation liquid after odor component removal means 4 E: Ethanol recovery means Recovery ethanol fraction after 5 F: Ethanol fraction after pervaporation deorganic membrane device 61 G: Ethanol fraction before dehydration membrane device 63 H: Ethanol fraction after dehydration membrane device 63 (purified ethanol)

(Comparative Example 1)
Using the bioethanol recovery system according to the prior art shown in FIG. 5, ethanol was recovered from the same fermentation broth as in Example 1 and further purified.

  Table 1 shows the material balance and composition at the locations indicated by A 'to D' below. Note that the locations indicated by A ′ to D ′ below correspond to the locations indicated by reference signs A ′ to D ′ in FIG. 5.

A ′: Fermentation liquid after fermenter 201 B ′: Distillation ethanol fraction after moromi tower 202 C ′: Distillation ethanol fraction after rectification tower 204 D ′: Ethanol fraction after adsorption dehydration tower 205 (purification) ethanol)

  In Table 1, the odor component is the total amount of esters such as ethyl acetate, polyhydric alcohols such as propanol, butanol and amyl alcohol, grain odor components and yeast odor components, and the organic acid is an organic acid such as acetic acid. Is the total amount.

<Evaluation>
From Table 1, it can be seen that in Example 1, entrainment of odorous components in the recovered ethanol fraction after ethanol recovery means 5 (location E above) is highly prevented.

  From the comparison between Example 1 and Comparative Example 1, it can be seen that according to the present invention, the concentration of the odorous component contained in the final product (purified ethanol) can be greatly reduced.

  In Example 1, a rotating cone column is used as the odor component removing means 4 and the ethanol recovery means 5, and membrane separation means (purified pervaporation deorganic membrane device 61 and dehydration membrane device 63) is used as the ethanol purification means. As a result, it was confirmed that the thermal energy can be significantly reduced compared with Comparative Example 1 and energy saving can be achieved.

1: Fermenter 2: Solid-liquid separation means (odor component release source removal means)
21: Continuous strainer 22: Centrifuge 23: Oil layer separator 24: Membrane separation means 3: Evaporator (ethanol return means)
31: Return piping 4: First rotating conical column (odor component removing means)
5: Second rotating conical column (ethanol recovery means)
6: Ethanol purification means 61: Pervaporation deorganic membrane device 62: Vapor compressor 63: Dehydration membrane device 7: Purified ethanol storage tank
I: Odor component emission source removal process
II: Odor component removal process
III: Ethanol recovery process
IV: Ethanol purification process

Claims (10)

  A bioethanol recovery method comprising a odor component removal step of removing an odor component from the fermentation broth as a pretreatment of an ethanol recovery step of recovering ethanol from the fermentation broth.   2. The bioethanol recovery method according to claim 1, wherein the odor component removal step further removes an odor component release source in addition to the odor component.   The bioethanol recovery method according to claim 1, further comprising an odor component release source removal step of removing an odor component release source from the fermentation broth as a pretreatment of the odor component removal step. In a bioethanol recovery system comprising at least an ethanol recovery means for recovering ethanol from a fermentation broth,
A bioethanol recovery system comprising an odor component removing means for removing an odor component from the fermentation broth before the ethanol recovery means.   5. The bioethanol recovery system according to claim 4, wherein a rotating conical column is used as the odor component removing means.   6. The bioethanol recovery system according to claim 4 or 5, further comprising an odor component release source removal means for removing an odor component release source from the fermentation broth in a preceding stage of the odor component removal means.   The bioethanol recovery system according to claim 6, wherein a solid-liquid separation unit is used as the odor component release source removal unit.   The bioethanol recovery system according to any one of claims 4 to 7, wherein a rotating conical column is used as the ethanol recovery means.   The bioethanol recovery system according to any one of claims 4 to 8, further comprising ethanol purification means for removing impurities from the ethanol recovered by the ethanol recovery means for purification.   The bioethanol recovery system according to claim 9, wherein membrane separation means is used as the ethanol purification means.

Images