JPS6394963A - Continuous production of volatile fermentation product - Google Patents

Abstract

PURPOSE:To separate a volatile product from a fermentation liquid in high efficiency and to effectively utilize the heat of fermentation, by treating a fermentation liquid with an evaporator provided with a heat-exchanger and column plates. CONSTITUTION:In the production of a volatile substance such as alcohol, ether, ketone, etc, by fermentation, a fermentation liquid essentially free from microorganisms is extracted from a fermentation tank 1 and introduced into an evaporator 3 provided with a heat-exchanger 5 and column plates 2. The vapor of the evaporated volatile substance is adiabatically compressed with a compressor 4 to raise the temperature and introduced into the heat-exchanger 5. The heat-exchanger 5 is preferably a falling film evaporator and the column plate 2 is preferably perforated plate or bubble-cap tray.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a process for the efficient and continuous production of volatile fermentation products such as alcohols, ethers or ketones.

(Prior Art) In general, methods for producing volatile substances by fermentation have the advantage of being produced at room temperature and near normal pressure, or that production takes a long time and the concentration of the product is low. Moreover, there is a drawback that the production rate decreases rapidly as the concentration of volatile substances increases.

Furthermore, since the concentration of the target fermentation product is low, there is a drawback that a large amount of energy is required for concentration and separation.

On the other hand, at present, the fermentation heat in the fermenter is cooled and removed by various types of coolers such as shower coolers, flash coolers, or cooling coils, and is wasted.

In order to solve the first drawback, various methods and devices have been proposed so far.

For example, firstly, as described in U.S. Pat. -26041
As described in the above issue, there is a method of removing heat generated by fermentation production by circulating the fermentation liquor through a vacuum evaporative cooler.

Second, as an energy-saving ethanol fermentation production method, for example, a portion of the liquid extracted from the fermenter is heated through a heat exchanger, and then introduced into a vacuum flash fermenter to extract ethanol-rich vapor into the gas phase, which is then depressurized. A method in which the vapor at the top of the rectification column is adiabatically compressed using a compressor and used as a heat source for the rectification column and a heat source for the heat exchanger at the front stage of the vacuum flash evaporator (ATPA).
L method, Ches+1ca1. Age, Nov,
21. (1980) p. 11).

Thirdly, as a method for efficiently carrying out ethanol fermentation in a fermenter, for example, Japanese Patent Application Laid-Open No. 57-2685, Japanese Patent Publication No. 59-
43156 etc. In these methods, a portion of the fermentation liquid in the fermenter is extracted and guided to a vacuum flash evaporator, which is used to separate into ethanol-rich steam and ethanol-poor fermentation liquid. It will be sent back.

(Problems to be Solved by the Invention) However, in the first example, US Pat. No. 2,440.
In the method of No. 925, the extracted steam is cooled in a condenser, and the fermentation heat is discarded. Additionally, there are other problems, such as the need for power to compress the condenser to normal pressure during cooling, and the need for deep cooling to cool the condenser. In addition, the Tokuko Showa 3
The method of No. 9-26041 was intended to concentrate the fermentation liquid, and had the disadvantage that only the volatile fermentation product (and water) could be obtained in an amount corresponding to the calorific value of the fermentation reaction.

In the second ATPAL method mentioned above, the amount of heat for evaporating ethanol is transported in the form of m heat from the heat exchanger to the vacuum flash evaporator, so the amount of circulating fermentation liquid is large, and the required heat transfer area of the heat exchanger is also large. It has the following drawbacks.

Furthermore, in the case of the third example, when the fermented liquor from the fermenter is separated in the vacuum flash evaporator, there is a considerable amount of ethanol in the fermented liquor at the exit of the vacuum flash evaporator due to the relationship between the equilibrium solubility of ethanol in the gas phase and the liquid phase. of ethanol remains. When this fermentation liquid is returned to the fermenter, the ethanol concentration in the fermenter increases, and the fermentation rate inevitably decreases compared to the case where the fermentation liquid is not returned to the fermenter.

(Means for Solving the Problems) As a result of various studies to overcome the drawbacks of the above-mentioned conventional methods, the inventors of the present invention have incorporated a tray into the evaporator which has a built-in heat exchanger. By treating the fermentation liquid, it is possible to significantly reduce the concentration of volatile substances remaining in the fermentation liquid, prevent a decrease in the activity of microorganisms, and increase the productivity of desired volatile substances. It was discovered that the required energy can be saved by using it effectively and stable operation can be continued. The present invention has been made based on this knowledge.

That is, the present invention provides for fermentation production of volatile substances,
The fermented liquor extracted from the fermenter and which does not substantially contain microorganisms is introduced into an evaporator device having a built-in heat exchanger and trays, and the volatile fermentation products in the fermented liquor are evaporated and recovered. The present invention provides a method for continuously producing a volatile fermentation product, characterized in that the fermented liquor after treatment is sent to a fermenter.

The invention will be described in detail below with reference to the drawings showing preferred embodiments of the invention.

FIG. 1 is a flow sheet showing the basic configuration of a fermentation apparatus used in the method of this invention. In the figure, 1 is a fermenter using immobilized microorganisms, and the fermentation raw material is supplied to the fermenter 1 through line 9 and fermented by the microorganisms. The fermentation liquor (mash) at any fermentation stage is taken out from the fermentation tank in which volatile substances and non-condensable gases are produced, and is transferred from the line 11 to the evaporator 3 with a built-in heat exchanger having a tray 2 inside. It is circulated to generate vapor of volatile fermentation products. In this case evaporation! As Jji3, a reduced pressure evaporation tank (flash tank) is preferably used. Further, this steam is extracted from the line 12 and adiabatically compressed by the compressor 4 to raise its temperature, and is used from the line 13 as a heating source for the evaporator 3 with a built-in heat exchanger 5. In addition, this evaporator 3 has two shelves.
The installation of the evaporator 3 improves the recovery rate of volatile fermentation products.
The concentration of volatile fermentation products in the fermentation liquor in the outlet line 14 is reduced. Therefore, this fermentation liquid is transferred to lines 14, 15.
When circulating to the fermenter 1 through 16, it is possible to prevent the concentration of volatile fermentation products in the fermenter 1 from increasing, thereby reducing inhibition of fermentation by fermentation products and improving fermentation productivity. Furthermore, this evaporator 3 is equipped with an auxiliary heating section 5a of a heat exchanger built into the evaporator to compensate for the insufficient heat source.
may be supplied with steam, hot water, etc., or may be directly blown with steam. Thereby, sufficient steam can be generated and the evaporator 3 can be operated stably regardless of fluctuations in fermentation.

Most of the non-awa gas produced by fermentation is in the line lO
is discharged through the Volatile substances, which are fermentation products, are
It is condensed and recovered via line 17.

On the other hand, the fermentation liquid after evaporation of volatile substances, which is a fermentation product, is returned to the fermenter 1 as described above, but some of it is also returned to the line 1.
8 and is discharged. If necessary, it is also possible to supply this fermentation liquid to the next fermenter.

FIG. 2 is a flow sheet of another embodiment of the method of the present invention, in which the evaporator 3 is a heating evaporation tank, and the volatile substances in the fermentation liquid are evaporated under reduced pressure in the downstream stage of the evaporator 3. A reduced-pressure evaporation tank (for example, a flash tank) 6 is provided which can lower the temperature of the fermented liquor (mash) to a temperature suitable for fermentation at the same time as recovery. Furthermore, a condenser 7 is provided to recover evaporated volatile substances. As a result, the pressure of the evaporator 3 is increased to enable operation, so the volume of gas to be evaporated is reduced, and the diameter of the evaporator 3 can be reduced. In this embodiment, the evaporator 3 is mainly used to separate volatile substances that are fermentation products, and the reduced pressure evaporator 6 is used mainly to lower the temperature of the fermented liquid to an appropriate temperature.

As the heat exchanger built into the evaporator 3, a falling thin film heat exchanger 8 is preferably used because it has less influence on the heat-unstable raw material components in the fermentation liquor. In this figure, the same reference numerals as in FIG. 1 indicate the same things.

Note that 19 is a line for sending steam from the vacuum evaporator 6 to the condenser 7, 20 is a line for returning the fermented liquid taken out from the vacuum evaporator 6 to the fermenter l via line 15.16, and 21.22 is the condenser 7. is a discharge line for non-condensable gases and condensate from the

Fig. 3 is the same as Fig. 2 in terms of the U end, but is a flow sheet when flocculent microorganisms or planktonic microorganisms are used as microorganisms in the fermenter. Since the fermentation liquid taken out contains microorganisms, a separator 23 is provided to separate the microorganisms and return them to the fermenter l. Specific examples of this separator 23 include a centrifuge, a sedimentation separator, etc. , filters, etc. The fermented liquid from which microorganisms have been removed is sent to the evaporator 3 through line 27.Most of the separated microorganisms are returned to fermentation 461 through lines 24 and 25, but if necessary, they can be taken out from line 26 and used for recovery. It is also possible to do. The other configurations are the same as in Figure 1 or Figure 2,
The same reference numerals as in FIG. 1 or 2 indicate the same things.

In this invention, evaporators such as a reduced pressure evaporation tank and a heating evaporation tank are used in appropriate combinations as the evaporator device, and at least one of these evaporators is provided with a heat exchanger and a tray. In addition, when using a heating evaporation tank, as shown in Figure 2 or 3, a vacuum evaporation tank is connected to the subsequent stage, and the temperature of the fermented liquor after evaporation is lowered in the vacuum evaporation tank, and then the fermentation tank is heated. It is preferable to send it to

In the method of the present invention, in the embodiment shown in FIG. 1, a reduced pressure evaporation tank with a built-in heat exchanger is used as the evaporator 3 and is operated under reduced pressure, but the degree of reduced pressure depends on the type of fermentation reaction and the time. Although it varies depending on the fermentation temperature of the fermenter, it is usually 20 to 720 mmHg-abs, preferably 20 to 720 mmHg-abs.
It is in the range of 200I11g-abs.

In addition, in the case of the embodiment shown in FIG. 2 or 3, a heating evaporation tank is used as the evaporator 3, and the pressure is 0.8~
The most preferable pressure and temperature conditions for evaporation are a temperature of 75 to 105° C. at 1.2 atm or a temperature of 95 to 180° C. at a pressure of 1.2 to 10 aL+s. In this case, the remaining volatile substances are then evaporated and recovered in the reduced pressure evaporation tank 6, and the temperature thereof is lowered.

The degree of pressure reduction in the vacuum evaporator 6 at this time is related to the fermentation temperature, but is 20 to 720 mmHg-abs, preferably 20 to 720 mmHg-abs.
It is within the range of 200 mm/1 g/mm/1.

There is no particular restriction on the type of tray used in this invention, but it is one that reduces the concentration of volatile substances in the bottom liquid of a heating evaporation tank, a vacuum evaporation tank, etc., and this purpose is achieved. If so, it can be used without any particular restrictions.

Therefore, the shelf includes a perforated plate, a bubble cap tray, etc., and a packed column type having equivalent performance.

In this invention, the trays in the evaporator are preferably 4 to 15 theoretical plates, or in the case of a packed column type, a packed bed having a packing height corresponding to the theoretical plates. If the number of plates is less than four theoretical plates, it is not easy to sufficiently reduce the concentration of volatile substances.
Even if the number of theoretical plates exceeds 15, the effect does not particularly change, but the cost of the device increases. Volatile fermentation products in the fermentation liquid supplied to the evaporator are either evaporated to the gas phase side while flowing down the tray or packed bed, or passed through the heating section at the bottom of the evaporator to the bottom. When reaching , the concentration of volatile products in the fermentation liquor is preferably o, t-i.

wt%. This fermentation liquid is supplied directly or, if a vacuum evaporator (flash tank) is installed, via a vacuum evaporator, in whole or in part, to the original fermenter or another fermenter. In this way, the concentration of volatile products in the fermentation liquid supplied to the fermenter after completing the evaporation process in the evaporator is sufficiently low to reduce the influence of inhibition on the fermentation reaction in the destination fermenter.

In this invention, the fermented liquid from which volatile substances have been removed, which is a fermentation product, is sent to a fermenter, and this fermenter may be an original fermenter or another fermenter. Also, combinations of fermenters and evaporators may be assembled in 28A or more in series or in parallel.

In this invention, there is no particular restriction on the type of heat exchanger built into the evaporator used, and an ordinary multi-tube type may be used. An efficient heat exchanger that is less affected by this is also selected as appropriate. For example, a structure such as a falling thin film type or a thin film type (horizontal tube type) is preferable.

In this invention, changes in the concentration of volatile substances that are fermentation products in the fermentation liquid in the fermenter cause changes in the concentration of volatile substances in the vapor evaporated from the evaporator, and the temperature at which this vapor condenses changes. It may change from the original design value. Here, if the temperature difference required for heat transfer in the heat exchanger becomes small, there is a possibility that heating of the fermented liquid in the evaporator and condensation of vapor containing volatile substances may not be performed sufficiently.

To compensate for the insufficient heating source, an auxiliary heating section is installed in the heat exchanger built into the evaporator, and/or steam is directly blown into the evaporator to supply an auxiliary heat source, thereby ensuring sufficient evaporation and stable evaporator operation. Able to drive. Particularly when returning the fermented liquor to the fermenter, it is important to operate stably so that no volatile substances remain in the fermented liquor at the evaporator outlet in order to prevent a decrease in the fermentation rate in the destination fermenter.

In the method of this invention, the fermentation process using the above-mentioned evaporator device can be carried out in accordance with a conventional fermentation method. That is, when producing volatile substances such as alcohols, ethers, and ketones, immobilized microorganisms, flocculent microorganisms, or planktonic microorganisms are used as microorganisms to ferment raw materials, and the microorganisms are fermented at the desired fermentation stage. Separated from the fermentation liquid.

The microorganisms used in this invention include various yeasts such as Saccharomyces cerevisiae.
omyces cerevisiae), Saccharomyces lavarum (Saccharomyces uvar)
am), or bacteria such as Zysomonas mobilis.

When flocculent microorganisms or planktonic microorganisms are used as microorganisms, they are separated by separation means such as centrifugation, filtration, or sedimentation.The separated microorganisms are returned to the fermenter and the microorganisms are separated. The fermented liquor after fermentation is supplied to each tray and an evaporator with a built-in heat exchanger, where it is heated or depressurized to evaporate volatile substances and non-condensable gases, which are fermentation products. It will be collected. In this evaporation means, since microorganisms are not contained in the fermentation liquid during heating, the heating pressure and temperature conditions can be set arbitrarily.

(Effects of the Invention) Conventionally, the amount of evaporation of volatile substances in a fermentation liquor is determined by the relationship of vapor-liquid equilibrium, and the concentration of volatile substances remaining in the fermentation liquor is high. Therefore, as this fermentation liquid is fed to the original fermenter or to other fermenters, the concentration of volatile products in this fermenter increases and has an inhibiting effect on the fermentation, reducing the productivity (efficiency) of the fermenter. This will lead to a decrease in

On the other hand, according to the method of the present invention, it is possible to increase the concentration of the fermentation raw material supplied to the original fermenter by returning it within a range that does not cause a decrease in the productivity of the fermenter. This ultimately leads to a reduction in the amount of waste liquid from the entire fermentation process,
It is difficult to achieve a significant reduction in waste liquid treatment costs.

According to the method of the present invention, the required energy is saved by effectively utilizing the fermentation heat, and stable operating conditions can be maintained.

In this invention, the volatile fermentation-rich steam removed by evaporation in the evaporator with a built-in tray and heat exchanger is adiabatically compressed and raised in temperature and pressure, and then heated by the built-in heat of the evaporator. It is used as a heating source for the exchanger and is cooled and liquefied in its evaporator. That is, the fermentation heat is completely utilized for evaporation of the fermentation product. After adiabatic compression, the vapor rich in volatile fermentation products is
The temperature has increased by ~20℃. With this method, an additional heat source for evaporation in the evaporator is hardly required. In other words, volatile fermentation products can be evaporated and recovered using less heat than in the past. On the other hand, it does not require a cooling source such as cooling water to cool and liquefy the volatile substance-rich steam that is a fermentation product, so it has great advantages such as saving on the cooling system.

(Examples) Next, the method of the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 Ethanol fermentation was carried out according to FIG. A fermenter was filled with 400 pieces of immobilized yeast, which was made into a spherical gel by enveloping the yeast in calcium alginate.

Raw material with a total sugar concentration of 35.3 wL% was supplied through line 9.16 at a rate of 114.4 kg/h. The fermentation temperature was 32°C. Carbon dioxide gas generated during fermentation is passed through line 10.
It was discharged at a rate of 14.4 kg/h.

On the other hand, the fermentation liquid containing 5.1 wt% ethanol was 299
, is pulled out at 5 kg/h and passes through the line 11 to protrude 1.
It was placed in an evaporator (flash tank) 3 having a height of 6 m and a diameter of 700 mm and having 0 stages. In order to evaporate and separate ethanol from the fermentation liquid, steam was first supplied at a rate of 5 kg/h to the auxiliary heating section of the heat exchanger with a built-in evaporator. The ethanol-containing vapor evaporated from the evaporator 3 was adiabatically compressed by the compressor 4, returned to the evaporator 3, and used as a heating source, so the amount of evaporation gradually increased and became constant at 52.5 kg/h.

At this time, the ethanol concentration was 28.5 wt%. The temperature inside the evaporator is 32℃ to 34℃ 1 pressure is 40mm
Stable operation was achieved by maintaining l1g-abs.

The temperature of the steam at the 4th outlet of the compressor is 60℃, and the pressure per pressure is 72ml.
1 g-abs, which is led to the evaporator 3 and condensed 35
It became an ethanol aqueous solution at ℃ and was recovered at a rate of 52.5 kg/h.

On the other hand, the fermented liquor at the outlet of evaporator 3 is withdrawn through line 14 at a rate of 247 kg/h, returned to the fermenter through line 15.16 at 199.5 kg/+1, and the remainder is withdrawn through line 18. It was discharged at a rate of 47.5 kg/h. The ethanol concentration contained in this fermentation liquid was 0.16 wt%. In this way, the fermentation liquid with low ethanol concentration is returned to the fermenter, so the ethanol concentration in the fermenter is kept low.
The ethanol fermentation rate was 35g/15L-fermenter/h, and the fermentation productivity was improved.

Comparative Example 1 Ethanol fermentation was carried out under the same operating conditions as in Example 1 by wiping the shelf 2 built into the evaporator 3 using a device similar to that shown in FIG. is 2
．． Since this fermentation liquor is returned to the fermenter, the ethanol concentration at the exit of the fermenter l is 5.1% as in Example 1.
The fermentation productivity decreased from 6.3 wt% to 6.3 wt% compared to Example 1, resulting in a decrease of about 40% in fermentation productivity. In order to produce the same amount of ethanol as in Example 1, 700 ml of immobilized yeast was required. In addition, the recovered ethanol concentration was 27.1wt.
%, which was a low value when compared with Example 1. In this way, if the trays are not provided, there is a drawback that fermentation productivity may be reduced.

Comparative Example 2 Same as Example 1 except that the same device as Example 1 was used, the steam compressed by the compressor 4 was not used as the heat source for the evaporator 3, and only the steam was used as the heat source for the auxiliary heater 5a. 52.
Approximately 50 kg/h of steam was required to obtain a evaporation rate of 5 kg/h. The operating conditions of the fermenter 1 and the evaporator 3 were the same as in Example 1, and the inside of the evaporator was maintained at reduced pressure by a vacuum pump. As a result, when comparing the total amount of steam for auxiliary heating and the required power for the compressor, Example 1 consumed 30% of the energy compared to Comparative Example 2.

Furthermore, in Comparative Example 2, a new condenser and cooling utility are required to recover ethanol from the vapor at the vacuum pump inlet or outlet, resulting in lower equipment costs.
The disadvantage is that energy costs also increase.

Example 2 Ethanol fermentation was carried out as shown in Figure 2.

The conditions of the fermenter I were the same as in Example 1. Line 9.
molasses with a total sugar concentration of 35-3 wt% through 114
, 4 kg/h. Carbon dioxide gas generated during fermentation was discharged from line 10 at a rate of 14.4 kg/h. On the other hand, the fermentation liquid containing 5.2 wt% of ethanol was 299.
It was extracted at a rate of 7 kg/h and sent through a line 11 to an evaporator 3 having 10 protruding stages. Steam was supplied at a rate of 3.5 kg/h to the auxiliary heating section of the heat exchanger with a built-in evaporator, and the generated steam was compressed by Itrr8 with a compression ja4 to recover heat. As a result, the amount of evaporation was 35.3 kg/h. Moreover, the ethanol concentration was 40.3 wt%. The temperature inside the evaporator is 88℃ to 93℃, and the pressure is 60℃.
It was maintained at 0 mm + t1g abs. Under these operating conditions, the evaporator 3 has the same height I as in Example 1 and a diameter of about 1
It became 15. The temperature at the outlet of the compressor 4 was 120° C. and the pressure was 1015 msllg-abs, and the ethanol aqueous solution at 95° C. was recovered at a rate of 35.3 kg/h through the evaporator 3. The fermented liquor at the outlet of the evaporator is extracted through line 14 at a rate of 264,4 kg/h, and pumped by a vacuum pump at 940 kg/h.
It was led to a vacuum evaporation tank (flash tank) 6 leaning against mm1g-abs, and was flushed under reduced pressure to evaporate the remaining ethanol and at the same time lower the temperature to 34°C. The flash vapor was cooled in a condenser 7 and then recovered as an ethanol aqueous solution at a rate of 24.6 kg/h. Further, the ethanol concentration was 2.6 wt%.

On the other hand, the fermented liquor after flash evaporation is returned to the fermenter l from line 20 through line 15 at a rate of 199.7 kg/h, and the remaining fermented liquor passes through line 18 at a rate of 40.1 kg/h.
It was discharged at h. Moreover, the ethanol concentration of the fermentation liquid was 0.5 wt%.

[Brief explanation of the drawing]

FIG. 1 is a flow sheet showing the basic configuration of a fermentation apparatus used in the method of the present invention, and FIGS. 2 and 3 are flow sheets of the other embodiments, respectively. Explanation of symbols

Claims (10)

[Claims] (1) When producing volatile substances by fermentation, the fermented liquor extracted from the fermenter and which does not substantially contain microorganisms is introduced into an evaporator that has a built-in heat exchanger and trays, and the fermented liquor is A method for continuous production of volatile fermentation products, characterized by evaporating and recovering the volatile fermentation products therein, and sending the treated fermentation liquid to a fermentation tank. (2) The method according to claim 1, wherein the vapor of the volatile fermentation product is adiabatically compressed to raise its temperature and is used as a heating source for a heat exchanger built into the evaporator. (3) The built-in heat exchanger of the evaporator is divided into two or more parts, and one side uses adiabatically compressed steam containing volatile fermentation products evaporated in the evaporator as a heat source for each. ,
3. The method according to claim 2, on the other hand, hot water and/or steam or the like is used as an auxiliary heat source. (4) The method according to claim 1, wherein the evaporator comprises (a) a reduced pressure evaporation tank or (b) a combination of a heated evaporation tank and a reduced pressure evaporation tank connected downstream. (5) The method according to claim 4, wherein the reduced pressure evaporation tank (a) or the heated evaporation tank (b) has a built-in heat exchanger and trays. (6) The vacuum evaporation tank in (a) is 20 to 200 mmHg・a
6. The method according to claim 5, wherein the temperature is maintained at 25-65°C. (7) The heating evaporation tank in (b) is 0.8 to 1.2 atm, 7
5-105℃ or 1.2-10 atm, 95-180℃
20 to 200 mmHg in the downstream vacuum evaporator
- abs, the method according to claim 5, wherein the temperature is maintained at 25-65°C. (8) The method according to claim 1, wherein the heat exchanger built into the evaporator is of a falling film type. (9) Claim 1, wherein the trays built into the evaporator are of a perforated plate type, a bubble cap tray type, or a packed column type.
The method described in section. (10) The method according to claim 1, wherein the evaporator has 4 to 15 theoretical plates.