JPS6232870A - Device for producing alcohol - Google Patents

Abstract

PURPOSE:To raise productivity by circulating a fermentation solution between a fermentation tank and a vacuum flash tank and to aim reduction in energy by condensing alcoholic vapor vaporized in the vacuum tank and concentrating it in a permeating vaporizer. CONSTITUTION:In a device for producing continuously an alcohol by the use of an alcohol-producing mold, the fermentation tank 2 is provided with a raw material and carries out alcohol fermentation and the vacuum flash tank 7 is provided with an alcohol-containing solution from the tank 2 and vaporizes and separates the alcohol component. The condenser 9 condenses alcohol- containing vapor from the tank 7 and the permeating vaporizer 17 is charged with a condensed solution from the condenser 9, permeates and vaporizes the condensed solution through the functional permeating membrane 18 so that the alcohol is concentrated and recovered. Further, the conduit 13 for circulating an unevaporated solution from the bottom of the tank 7 to the tank 2 is set and the alcohol concentration in the tank 2 can be adjusted to a low value. Consequently, improvement in productivity and reduction in energy can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an alcohol production apparatus that continuously produces alcohol using alcohol producing bacteria.

(Conventional technology) In conventional alcohol production systems, the raw material carbohydrates, such as blackstrap molasses, are diluted with water and used as a substrate, and the substrate and bacteria are grown in a fermenter containing sake mash in which alcohol-producing bacteria have been precultured. Fermentation and aging are carried out over a long period of time while controlling hydrogen ion concentration, temperature, etc. to optimal culture conditions using a batch method, converting sugar in the substrate into alcohol and carbon dioxide gas. After fermentation and aging, the fermented liquor is placed outside the moromi tower in a distillation process that consists of several distillation towers to separate and concentrate the dilute alcohol contained in the fermented liquor to produce alcoholic products.

Furthermore, substances that form an azeotropic compound with water, such as ethanol, are further dehydrated using benzene or the like in an azeotropic distillation column to produce anhydrous alcohol.

In this case, in the fermenter, the alcohol concentration increases over time, and the alcohol-producing bacteria, for example, about 8.01% for ethanol production and 2-6.01% for butanol production.
Since the alcohol concentration is inhibited and the activity of the bacteria decreases, alcohol has to be separated and concentrated from the low alcohol concentration, which consumes a lot of energy.

In addition to this, various fermentation methods have been researched and developed, but in all of these methods, alcohol-producing bacteria are inhibited when the alcohol concentration reaches a certain level, resulting in a reduction in the fermentation rate. Therefore, the alcohol concentration of the fermented liquid flowing out from the fermenter is low, and alcohol can be separated and removed using traditional distillation methods.
As far as enrichment goes, the equipment is complex and consumes a lot of energy.

(Problems to be Solved by the Invention) An object of the present invention is to provide an alcohol production apparatus that eliminates the drawbacks of the conventional alcohol production apparatus described above and achieves improved productivity and energy savings.

(Means for Solving the Problems) The present invention provides an apparatus for continuously producing alcohol using alcohol-producing bacteria, including a fermenter that supplies raw materials to ferment alcohol, and an alcohol-containing liquid from the fermenter. A vacuum flash tank is introduced to vaporize and separate the alcohol content, a condenser is used to condense alcohol-containing vapor from the vacuum flash tank, and a condensate from the condenser is introduced to permeate through a functional separation membrane. It consists of a pervaporator that concentrates and recovers dialcohol by vaporization, and by providing a conduit that circulates the unevaporated liquid from the bottom of the vacuum flash tank to the fermenter, the alcohol concentration in the fermenter can be adjusted to a low level. The present invention relates to an alcohol production device characterized by the following.

(Operation) In the present invention, a substrate with adjusted raw carbohydrates is circulated between a fermenter filled with alcohol-producing bacteria and a vacuum flash tank by connecting it with a pipe.The alcohol produced in the fermenter is continuously circulated in a vacuum flash tank. The alcohol concentration in the fermented liquid is controlled to be below the alcohol inhibition concentration shown by the bacteria, and the alcohol is circulated and fermented. Combines alcohol separation and concentration processes that send alcohol to a pervaporator equipped with a functional membrane and concentrate it to a predetermined concentration.
This is a rational alcohol production device that eliminates waste liquid by incorporating a closed cycle system in which the waste liquid is desalinated and circulated to the fermentation tank or substrate adjustment tank. The alcohol production apparatus of the present invention is a production apparatus common to alcohol production such as ethanol production and butanol production.

More specifically, in order to control the alcohol concentration in the fermentation liquor in the fermenter to a concentration range that has less influence of inhibiting alcohol-producing bacteria, the fermentation liquor is continuously passed through a pressure reducing valve and transferred to a reduced pressure flash tank. The alcohol concentration in the fermented liquid is lowered by circulating and separating the alcohol content in the fermented liquid using the fermentation heat stored during the fermentation process, or the heat slightly heated if necessary. , it is possible to maintain high bacterial activity. In addition, the fermentation liquid that has not been vaporized in the vacuum flash tank contains salts contained in the raw material waste molasses, salts derived from nutrients, and impurities in addition to unfermented carbohydrates, so it is necessary to remove and adjust them. .

In this case, a part of the fermentation liquid that is circulated in the fermenter is introduced into a p filter and an electrodialysis desalter that has a built-in cation and anion exchange membrane, and after adjustment, it is circulated to the fermenter or used for substrate adjustment. Reuse as liquid. Therefore, the amount of waste liquid is very small. Further, the fermenter may be either a single stage or a series multi-stage, and the format may be either a method in which alcohol-producing bacteria are suspended or a so-called immobilized cell method, but preferably, the liquid flow within the tank is Good structure for forming extrusion flow. Furthermore, when fermenters are used in multiple stages in series, it is desirable that the fermentation liquor circulated through the vacuum flash tank be returned to the second membrane type or later.

The alcohol vaporized and separated in the vacuum flash tank is clean and does not contain any impurities from the fermentation liquid, and the alcohol concentration depends on the operating pressure of the vacuum flash tank and the temperature of the feed liquid, which is theoretically easy to achieve according to Raoult's law. It is assumed that For example, in the case of ethanol production, alcohol-producing bacteria control the concentration range of 1.5 to 3 mole fraction, which has little influence on alcohol concentration inhibition, to a fermented liquid at a liquid temperature of 30 to 50°C and an operating pressure of 30 to 1.
When processed in a vacuum flash tank at 50 Torr, alcohol concentrations of about 15-25 mole fraction can be recovered. this is,
It corresponds to the "mash tower" fraction of conventional ethanol production equipment, but at a slightly lower concentration.

The alcohol-containing vapor recovered in the vacuum flash tank is condensed in a condenser and then separated and concentrated to a predetermined concentration of alcohol in a pervaporator.

Since the pervaporator handles clean alcohol, there is no fear of membrane clogging, the membrane has a long life, and operational stability is ensured. In addition, the structure of a pervaporator is divided into an upstream side and a downstream side by a highly functional membrane, and the downstream side is separated by a pressure reducing pump so that the pressure is lower than the upstream side, or the downstream side is separated from the upstream side. It is designed to flow inert gas at a high temperature. The highly functional membrane used is a hydrophobic membrane that selectively allows alcohol to pass through, such as a silicone rubber membrane, an alumina membrane that has undergone hydrophobic treatment, or a hydrophilic membrane that selectively allows water to pass through. For example, so-called pervaporation membranes include various reverse osmosis membranes, grafted synthetic membranes of polyvinyl alcohol, polytetrafluoroethylene, etc., and alumina membranes subjected to hydrophilic treatment.

The alcohol-containing vapor separated by vaporization in the vacuum flash tank is condensed in a condenser, and then pumped into the upstream side of the pervaporator. In the case of a hydrophobic membrane, alcohol is selectively transferred to the downstream side of the membrane rather than the upstream side. It is vaporized as concentrated vapor, condensed and cooled in a cooler, and recovered as a predetermined alcohol concentration, leaving water on the upstream side. Therefore, compared to conventional distillation methods, separation and concentration equipment can be made more compact and energy consumption can be reduced.

Furthermore, when a hydrophilic membrane is used, water is separated on the downstream side and alcohol is concentrated on the upstream side, contrary to the above.

In addition, the separated water is used as a substrate in a regulating tank. 11! It is reused as a liquid for I, and is not disposed of as waste water outside the system.

When alcohol vaporized in a reduced-pressure flash tank is concentrated using a pervaporator, a difference in concentrated concentration occurs due to the separation coefficient of the membrane used, the pressure difference between the upstream and downstream sides, or the temperature difference.

In order to achieve the desired concentration, a pervaporator with a built-in hydrophobic or hydrophilic membrane is used in a single stage, multiple stages, or a combination of multiple stages, and in some cases, reverse osmosis membrane treatment is also performed for preliminary dehydration. However, the separation/concentration technology for the purpose of the present invention is common.

In accordance with the present invention, an example of a liquid-free alcohol production system in which an immobilized bacterial cell continuous fermenter, a vacuum flash tank, and a pervaporator composed of a hydrophilic functional membrane are systematically combined and waste liquid is treated. will be explained with reference to FIG.

Immobilized bacterial cells 1 with alcohol-producing bacteria immobilized on an insoluble carrier
A substrate in which raw carbohydrates, nutrients, etc. have been adjusted in advance in the adjustment tank 3 is supplied to the T-filled continuous fermentation tank 2. The supplied substrate comes into contact with alcohol-producing bacteria and ascends through the continuous fermentation tank 2 while being denatured into carbohydrate t-alcohol and carbon dioxide gas, and carbon dioxide gas is released to the top of the tank. On the other hand, the fermentation liquid is passed through the piping 4, the heater 5 and the pressure reducing valve 6 as necessary.
It is discharged into a vacuum flush tank 7 whose pressure is reduced by a vacuum pump 11 .

A part of the discharged fermentation liquid is vaporized and separated as alcohol-water vapor with an equilibrium concentration corresponding to the liquid temperature and operating pressure, and is condensed and cooled in a condenser 9, and is received as coarse and fine alcohol in a tank 10, and then pumped. At 12, it is further pumped to a pervaporator 17 for compression. On the other hand, the fermented liquid containing unfermented carbohydrates, which vaporizes the alcohol content in the vacuum flash tank and has a lower alcohol mff, passes through the pipe 13 from the lower part of the vacuum flash tank and is circulated to the continuous fermenter 2 again.

Here, in the adjustment tank 3, the carbohydrate equivalent to the alcohol vaporized and separated in the vacuum flash tank 7 is adjusted with water equal to the reduced volume, mixed with the newly supplied substrate, and fermentation is continuously repeated. However, the alcohol concentration in the substrate is lower than the alcohol inhibition concentration of the bacteria, and the activity of the bacteria is high. Therefore, the alcohol production rate is fast, and the productivity per volume of the continuous fermenter 2 is very good. .

Note that the fermentation liquor circulated from the lower part of the vacuum flash tank 7 to the continuous fermentation tank 2 may need to be adjusted to remove salts contained in the raw material waste molasses, salts derived from nutrients, impurities, etc.

At this time, a part of the fermentation liquid is sent from the pipe 13 to a filter 14 and an electrodialysis demineralizer 16 which has a built-in cation and anion exchange membrane 15, and after removing salts etc., it is sent to a continuous fermentation tank. 2 or used as a substrate conditioning liquid in the conditioning tank 3. Therefore, the amount of waste liquid discharged outside the system is very small.

The alcohol-water mixed vapor vaporized and separated in the vacuum flash tank 7 is passed through a pipe 8 and condensed and cooled in a condenser 9.
The alcohol is received in the tank 10 as coarse and dense alcohol, and is further pressurized into the upstream side of the functional membrane of the pervaporator 17 by the pump 12.

The pervaporation membrane of the pervaporation device 17 is partitioned into an upstream side and a downstream side by a hydrophilic high-performance membrane 18, and the pressure on the downstream side is reduced by a pressure reducing pump 21, so that the pressure is lower than that on the upstream side. The coarse alcohol supplied to the upstream side of the pervaporation membrane is
Water selectively permeates the upstream surface of the functional membrane to the downstream side and vaporizes on the downstream surface, and alcohol on the upstream side is concentrated and received in the alcohol tank 19. On the other hand, the water permeated to the downstream side is condensed and cooled in the condenser 20, sent to the substrate conditioning tank 3, and reused as a substrate conditioning liquid. Therefore, there is no waste liquid to be discharged outside the system.

Although FIG. 1 shows an example in which a single-stage pervaporator composed of a hydrophilic functional membrane is used, it may not be possible to concentrate alcohol to a predetermined concentration depending on the separation coefficient of the membrane. In such a case, the pervaporators 17 may be used in multiple stages in series.

Further, an example in which the hydrophilic functional membrane of the pervaporator shown in FIG. 1 is replaced with a hydrophobic functional membrane will be explained based on FIG. 2. The alcohol-containing vapor from the vacuum flash tank 7 is
M device? The steps up to the step of receiving the condensed liquid in the tank 10 are the same as in FIG. Thereafter, the condensate is pumped by a pump 12 to a pervaporator 17 having a hydrophobic functional membrane 18,
The membrane is permeated to recover concentrated alcohol vapor, which is condensed in a condenser 20 and product alcohol is received in a tank 19.

(Example) A basic fermenter is filled with immobilized yeast, a substrate is supplied from the lower part, the fermented liquid from the upper part is transferred to a vacuum flux tank, and unevaporated liquid is transferred from the bottom of the vacuum flash tank. Continuous fermentation was carried out by circulating the mixture into the fermenter.

When fermentation was carried out with a substrate sugar concentration of 20% and a residence time of about 6 hours, the alcohol concentration of the fermented liquid was approximately uniform at a mole fraction of about 2.5. This fermentation liquid is heated to about 50℃.
and discharged into a vacuum flux tank. The vacuum flash tank was evacuated to about 70 to 100 torr using a vacuum pump to obtain alcohol vapor with a mole fraction of about 20. After condensing this vapor in a condenser, it is pumped into a membrane separator at a temperature of 20 to 5
It was supplied at 0°C and at a pressure of 1 to 5 klil/cm. The separation membrane at this time was a silicone rubber-based hydrophilic membrane. Water in the condensate was permeated through the membrane of the Fi membrane separator, and the upstream side More than 90 mole fraction of alcohol could be recovered from the outlet.

(Effects of the invention) (1) Fermentation liquid is circulated between the fermentation tank and the vacuum flash tank, and the alcohol content in the circulating fermentation liquid is heated to the vaporizer temperature in the vacuum flash tank, reducing the alcohol concentration and maintaining the activity of bacteria. This made it possible to speed up the fermentation rate and increase productivity per fermenter volume.

(2) A method of condensing vaporized alcohol in a vacuum flash tank and concentrating the alcohol in a pervaporator with a built-in selective functional membrane is systematically connected, eliminating the distillation process and simplifying equipment and saving energy. make it possible to

(3) The waste liquid can be treated in the system 14 to reduce the amount of waste liquid.

[Brief explanation of the drawing]

Figure 1 is an example of an alcohol production apparatus according to the present invention. Is there a flow diagram showing a hydrophilic functional membrane in a pervaporator? This is an example using Figure 2 is an example of using a hydrophobic functional membrane in an osmotic vaporizer, and is a diagram showing the flow around the osmotic vaporizer. Atsuo Anzai

Claims (1)

[Claims] An apparatus that continuously produces alcohol using alcohol-producing bacteria includes a fermenter that supplies raw materials and ferments alcohol, and a vacuum flash tank that introduces an alcohol-containing liquid from the fermenter and vaporizes and separates the alcohol content. , a condenser that condenses alcohol-containing vapor from the vacuum flash tank, and a pervaporator that concentrates and recovers alcohol by introducing the condensate from the condenser and pervaporating it through a functional separation membrane. An alcohol production apparatus characterized in that the alcohol concentration in the fermenter can be adjusted to a low level by providing a conduit for circulating unevaporated liquid from the bottom of the vacuum flash tank to the fermenter.