JPH051710B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for continuously obtaining high concentration alcohol by concentrating low concentration alcohol such as biomass alcohol.

In this specification, the term pervaparation method, ie, "pervaporation method" or "pervaporation method" is used to refer to the term "pervaparation method" or "pervaporation method" in which the secondary side of the permeable membrane is brought into a state of lower pressure than the primary side, and a liquid phase mixture is formed on the primary side. A membrane separation method in which a specific component in a mixture is mainly passed through the membrane to the secondary side in a gas phase to increase the concentration of the component.

Conventional technology and its problems As a method of obtaining high concentration alcohol by fermentation, there is a method that uses a batch method and does not reuse yeast, which is the fermenting bacteria, as seen in the brewing of alcoholic beverages. When trying to continuously produce fermented alcohol from fermented alcohol, use flocculating-sedimenting yeast or immobilized bacterial cells.
By preventing bacteria from flowing out of the fermenter, and by extracting some of the mash inside the fermenter to the outside of the tank and adjusting the alcohol concentration in the tank, it prevents the bacteria from dying and speeds up the fermentation. There are ways to speed up the process.

Conventionally, in the continuous production process of alcohol from biomass as described above, as shown in FIG. 9, a method has been adopted in which the mash extracted from a fermenter 81 is led to a distillation column 82 and distilled to increase the concentration of alcohol. It was getting worse. In addition, in the same figure, 83
is a capacitor, and 84 is a reboiler. However, this method requires a large multi-stage distillation column that consumes a large amount of thermal energy in order to increase the alcohol concentration to the target value, and since the alcohol/water mixture has an azeotropic point, it is difficult to increase the concentration of alcohol to the target value. There was a limit to the concentrated concentration of alcohol.

This invention was made in view of the above points,
The object of the present invention is to provide an alcohol concentration method that can completely overcome problems such as large consumption of thermal energy and concentration limits caused by azeotropic points.

Means for Solving Problems In order to achieve the above object, the alcohol concentration method according to the present invention subjects the mash extracted from the fermenter to evaporation treatment in the continuous alcohol production process, condenses the generated vapor, and then pervades the alcohol concentration method. It is characterized by obtaining high-concentration alcohol by subjecting it to membrane separation treatment using a parison method.

The above-mentioned mash is obtained by extracting a portion of the mash inside the fermenter to the outside of the fermenter, for example, in order to adjust the alcohol concentration in the fermenter to prevent bacterial cells from dying and to speed up the fermentation rate.

In a preferred embodiment of the invention, flash distillation is applied as the evaporation means.

EXAMPLES Next, the present invention will be explained in more detail with reference to examples.

Example 1 In FIG. 1, fermentation raw material biomass is subjected to alcoholic fermentation by culturing yeast in a fermenter 1. A portion of the mash produced by fermentation of the biomass is extracted outside the tank in order to prevent bacterial cells from dying and to speed up the fermentation rate by adjusting the alcohol concentration in the tank. After the moromi extracted in this way is heated in the preheater 2,
It is flushed into the flash tank 3 which is under reduced pressure. Through this flash distillation, flash vapor containing alcohol and water as main components is generated, and bacterial cells and solid components in the mash remain at the bottom of the tank as a distillation residue.

The flash vapor passes through a demister 4 in the same tank 3 to remove minute droplets from the vapor, and then is condensed in a condenser 7, and then the condensed liquid is led to a membrane separation tank 5. The inside of the tank 5 is divided into two parts, a primary side and a secondary side, by a permeable membrane 6, and the secondary side is brought into a lower pressure state than the primary side by a vacuum pump or the like. Further, as the permeable membrane 6, a silicone rubber-based membrane is used which selectively permeates alcohol over water. When the condensate of the flash vapor is supplied to the primary side of the tank 5, the alcohol content therein preferentially permeates through the permeable membrane 6 in the gas phase.
As a result of membrane separation using the pervaporation method, highly concentrated alcohol vapor is obtained from the secondary side.

The low concentration alcohol remaining on the primary side is removed from the membrane separation tank 5.
After leaving the fermenter, it joins with the distillation residue from the flash tank 3, a part of the combined liquid is returned to the bottom of the fermenter 1, and the remainder is extracted from the system.

The permeable membrane is not limited to those mentioned above, and is selected in consideration of selectivity to permeable substances, permeation rate, etc. Furthermore, if a cellulose acetate membrane that transmits water more selectively than alcohol is used instead of the silicone rubber membrane, high concentration alcohol can be obtained from the primary side.

In the flow shown in FIG. 1, the mash is preheated before being subjected to flash distillation, so the temperature becomes higher than that during fermentation, and as a result, the microorganisms in the mash may be killed or damaged. In such cases, preheating before flash distillation is omitted, the pressure inside the flash tank is reduced further, flash distillation is carried out at a low temperature, and the distillation residue is heated on the way back to the fermenter to adjust the fermentation temperature and the bacterial cells are heated. Measures are taken to prevent death or damage.

Next, the alcohol concentration process will be explained based on FIG. 2 showing the vapor-liquid equilibrium relationship and FIG. 3 showing the separation performance of the membrane. If the alcohol concentration of the liquid phase mash extracted from the fermenter is XA, the alcohol concentration of the gas phase obtained by flash evaporation will be YA according to the vapor-liquid equilibrium line in Figure 2. In this case, it is necessary that not only the flash vapor but also the minute droplets be completely removed by the demister. Next, when the condensate of the flash vapor having an alcohol concentration of YA is supplied to the primary side of a membrane separation tank equipped with an alcohol selective permeation membrane having the separation performance shown in Figure 3, the alcohol concentration on the secondary side will be as shown in Figure 3. It can be raised to YB. If the concentration YB thus obtained has not yet reached the target value, a condenser and a membrane separation tank are further arranged in series on the downstream side of the membrane separation tank 5, and the alcohol-containing vapor of the concentration YB is It is condensed in the same manner as above, and the condensate is subjected to membrane separation treatment by the pervaporation method. As a result, the alcohol concentration is increased to YC as shown in FIG.

Example 2 FIG. 4 shows an example in which two membrane separation layers are arranged in series. The tank 5 on the upstream side is equipped with an alcohol selectively permeable membrane 6 as in the first embodiment, and the tank 21 on the downstream side is equipped with a water selectively permeable membrane 22. The alcohol-containing vapor coming out of the secondary side of the tank 5 on the upstream side is condensed in the condenser 24 and then supplied to the primary side of the tank 21 on the downstream side, and high concentration alcohol is obtained from the same upstream side. , low concentration alcohol vapor flows out from the secondary side of the tank 21 and is condensed in the condenser 23. The other configuration of this embodiment is exactly the same as that of the first embodiment.

This embodiment is particularly suitable when the alcohol concentration of the mash is low and the alcohol concentration cannot reach the target value with one membrane separation tank. Further, both membrane separation tanks may be equipped with the same type of selectively permeable membrane, or three or more may be provided as necessary.

Example 3 FIG. 5 shows an example in which a condenser is incorporated into a membrane separation tank. In this example, the permeable membrane 31 is arranged horizontally or almost horizontally in a membrane separation tank 32, and a refrigerant pipe 33 is arranged in the upper space of the tank, and the same space is used as a condenser 34. The flash vapor coming from the flash tank is introduced into the condenser 34 and condensed there, and the condensate collected on the permeable membrane 31 is subjected to membrane separation treatment by a pervaporation method. In this way, highly concentrated alcohol vapor is obtained from the secondary side.
By integrating the condenser and the membrane separation tank in this way, the device can be made more compact and equipment costs can be reduced.

Embodiment 4 FIG. 6 also shows an example in which a condenser is incorporated into a membrane separation tank. In this example, the permeable membrane 41 is the membrane separation tank 4
A liquid distributor 43 is disposed at the top of the tank on the primary side, and its slit 44 communicates with the upper end of the permeable membrane 41 on the primary side. A refrigerant pipe 45 is disposed above the liquid distributor 43, and the top of the tank serves as a condenser 46.

In the membrane separation tank 42 having this configuration, the flash vapor coming from the flash tank is condensed in the condenser 46,
The condensed liquid accumulated in the liquid distributor 43 is transferred to the permeable membrane 4 from here.
The liquid flows down the upper surface of the primary side of the liquid forming a thin falling liquid film, and membrane separation is performed by pervaporation method while flowing down. In this way, highly concentrated alcohol vapor is obtained from the secondary side, and the flowing liquid collects at the bottom of the primary side.

This embodiment aims to reduce the film resistance related to mass transfer on the liquid phase side near the permeable membrane and to prevent so-called concentration polarization by keeping the primary liquid phase in a fluid state.

Example 5 FIG. 7 shows an example in which a flash tank is incorporated into a membrane separation tank. In this example, the membrane separation tank 51 shown in FIG.
A flash tank 52 is provided on the primary side, and
The flash vapor that has passed through the demister 53 of No. 2 is condensed in the condenser 54, and the condensed liquid passes through the inclined permeable membrane 5.
5 so that it flows down. 56 is a liquid distributor, and 57 is a refrigerant pipe.

Example 6 This example uses an eighth distillation device instead of a flash distillation device.
This is an example using the small-sized distillation column 61 or evaporator shown in the figure. In this case, since there is a heater 62 at the bottom, there is no need to preheat the mash using a preheater. The alcohol/water vapor coming out of the top of the column is then supplied to the primary side of the membrane separation tank, and the distillation residue coming out of the bottom of the column is returned to the fermentation tank.

In the case of this embodiment as well, a permeable membrane may be provided at the top of the distillation column or evaporator, and a membrane separation tank may be incorporated therein.

Effects of the Invention As described above, according to the present invention, the mash extracted from the fermenter is subjected to evaporation treatment, and the generated vapor is subjected to membrane separation treatment by the pervaporation method. It is possible to separate and remove bacterial cells and solid components in the mash as a distillation residue, completely preventing them from going to the membrane separation process on the downstream side. can be supplied to the membrane separation process.

Thus, according to the alcohol concentration method of the present invention, productivity of highly concentrated alcohol can be greatly improved in the continuous production process of alcohol, and in addition, it is possible to reduce the consumption of a large amount of thermal energy as explained at the beginning of this specification. The problems of conventional methods such as the concentration limit due to boiling point can be completely solved.

[Brief explanation of the drawing]

Figures 1, 4, 5, 6, 7, and 8 are flow charts showing Examples 1, 2, 3, and 4 of the present invention; Figure 2 is a graph showing the vapor-liquid equilibrium relationship of alcohol/water systems; The figure is a graph showing the relationship between alcohol concentration and membrane separation coefficient, and FIG. 9 is a flow chart showing a conventional example.

Claims (1)

[Claims] 1. In the continuous production process of alcohol, the mash extracted from the fermenter is subjected to evaporation treatment, the resulting vapor is condensed, and then subjected to membrane separation treatment by pervaporation method to obtain a highly concentrated alcohol. Alcohol concentration method characterized by obtaining alcohol. 2. The above-mentioned mash is obtained by extracting a part of the mash inside the fermenter to the outside of the fermenter in order to adjust the alcohol concentration in the fermenter to prevent the death of bacterial cells and to speed up the fermentation rate. The method described in Scope 1. 3. The method according to claim 1 or 2, wherein flash distillation is applied as the evaporation means.