JP2009073793A - System for separating and concentrating ethanol - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new and useful method for efficiently separating, purifying and concentrating alcohols produced by fermentation. <P>SOLUTION: This system for separating and concentrating the ethanol in the process of separating and concentrating the ethanol from the ethanol fermentation liquid is constituted by a vessel used for both of fermentation, and evaporation and vaporization to evaporate and vaporize the ethanol from the ethanol fermentation vessel directly under reduced pressure within a prescribed temperature range, and a dehydrating and concentrating device for removing water content from the vaporized gas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for separating, purifying, and concentrating fermented ethanol, and is a novel method for separating, concentrating, and dehydrating alcohol that can be fermented by using starch, sugar-containing agricultural products, etc. as raw materials. It is related with the processing method at the time of performing ethanol separation which used together the fermenter of a structure, and a gas separation membrane.

  In recent years, bioethanol production by fermentation has attracted attention as an important technique from the viewpoint of producing reproducible energy. However, ethanol in the fermentation broth has a low concentration, and it is necessary to provide a large-scale distillation-related facility by applying a great deal of heat energy to the separation and concentration. Traditionally, the technology has been centered on multistage distillation and azeotropic distillation, and the production cost is reduced by consuming more than half of the energy generated and retained by the large heat energy and equipment costs for the treatment. Making it difficult.

  In addition, from the perspective of energy production of ethanol, the conventional method consumes a lot of energy, which is far from the commonly called environment-friendly energy or regenerative energy. Is the situation.

  In view of these circumstances, the inventors have analyzed the production process of bioethanol and focused on the process of separating, concentrating, and dehydrating the production energy. Efficiently separate and concentrate ethanol with minimal heating. Furthermore, we aimed to simplify the equipment process.

  In other words, combining the fermentation apparatus that also serves to evaporate and separate ethanol and the membrane-type dehydration and concentration apparatus using an aromatic polyimide-based synthetic membrane that has recently been put into practical use reduces bioethanol production energy and costs. It came to devise the new technology which contributes to reduction.

  Concentration of ethanol from a fermentation broth has been performed for a long time in the manufacture of brandy and shochu, which are distilled spirits. The purpose is to drink after distillation, and since protection of fragrance components is also taken into consideration, concentration to a concentration as high as 90% or more is not necessary, and so-called simple distillation is mainly performed once.

  For further concentration, a multi-stage distillation process is used. However, there is a vapor-liquid equilibrium between ethanol and water, and the azeotropic point (about 95% by weight) of ethanol is reached at the point of 89 mol% (about 95% by weight). 78.2 ° C). This concentration of 89 mol% or more is impossible in an ethanol-water system.

  After that, it is necessary to further increase the concentration to 99.2% by weight or more in order to add fuel to automobile gasoline. Therefore, by adding benzene as the third component, the azeotropic point is lowered to 64.9 ° C., and the concentration up to 98% by weight can be finally achieved by the method of taking out ethanol. However, this method requires many evaporation, vaporization, cooling, and liquefaction steps for ethanol concentration and dehydration, and therefore, a large amount of heat energy and cooling energy are consumed there.

  This conventional method requires 11.30 MJ / Liter of heat to obtain 98% by weight ethanol from the alcohol fermentation broth. “The commercialization of nano-space materials and its technical and social background” The 67th annual meeting, which is estimated by Satoshi Nakane et al., Accounts for more than half of the 21.35 MJ / Liter of calorific value that ethanol can hold and generate.

  In addition, the raw materials for alcoholic fermentation are diverse, such as corn, wheat, rice, rice cake, sugarcane and sugar beet. However, energy is also consumed in the production of these raw materials. Even the energy is added to the actual manufacturing energy.

  Table 1. Fig. 5 shows the results of a trial calculation of the production energy of bioethanol by the present inventors using the conventional method and the trial calculation of Nakane Akira. In the conventional method, little effective energy is produced. Looking at the results of this analysis, there will be great doubts about promoting the use of bioethanol because it is environmentally friendly and reproductive. It is not meant to produce very environmentally friendly energy.

Therefore, in view of the fact that the energy required for production and fermentation of raw materials is essential,
Focusing on the concentration and dehydration process in the bioethanol production process, we promoted research and development to simplify the process and reduce energy consumption in production. As a result, the present invention method has been devised.

  Especially in the process of evaporation and vaporization that requires a lot of heating energy, the method and conditions are devised to efficiently vaporize ethanol, and the film is made of an aromatic polyimide film that is optimally suited for separation and dehydration. We succeeded in establishing a new bioethanol separation / concentration method by applying a dehydrating concentration apparatus.

  In other words, the main issue of the present invention is to improve the effective production energy as ethanol by reducing the heating energy and devising a simple manufacturing process in the process of evaporation, vaporization separation and dehydration in the manufacturing process of bioethanol. At the same time, it is to provide technology that is truly good for the environment, and to reduce the production price of ethanol.

  By providing such a bioethanol production process, it is a goal of the present invention to increase the efficiency of energy production and contribute to the protection of the global environment and the prevention of global warming.

  In order to achieve the above-mentioned problems, the present invention according to claim 1 is a process for separating and concentrating ethanol from an ethanol fermentation solution, and evaporates and evaporates ethanol directly from an ethanol fermentation tank under a reduced pressure condition in a predetermined temperature range. It consists of a means composed of a fermenter / evaporator and a dehydrating and concentrating device for removing water from the evaporated gas.

  In order to achieve the above-mentioned problems, the present invention according to claim 2 is a fermentation tank that evaporates and evaporates as described in claim 1 and has a nozzle that sprinkles water in the upper part, and is stored in the lower part. It comprises means having a function of circulating the liquid by sending the liquid to the above nozzle by pump power or the like.

  In order to achieve the above object, the present invention according to claim 3 is the fermenter / evaporation tank according to claim 1 having a water-absorbing filling such as sponge balls inside. , Consisting of means for continuing fermentation of the fermented liquor in the filling and vaporizing and evaporating ethanol.

  In order to achieve the above object, the present invention according to claim 4 comprises a means for setting the internal temperature of the fermenter / evaporation tank according to claim 1 to 30 ° C. or more and 50 ° C. or less.

  In order to achieve the above object, the present invention according to claim 5 comprises a means for setting the internal pressure to 10.7 KPa or more and 29.3 KPa or less.

  In order to achieve the above object, the present invention according to claim 6 is the dehydration concentration apparatus according to claim 1, wherein the dehydrating and concentrating apparatus is an aromatic polyimide system having the ability to permeate and remove moisture mainly from water vapor. It consists of means which is a dehydration concentration apparatus using a synthetic membrane.

  As is clear from the above description, the effect of the present invention is to reduce the production energy, especially the process operation energy in the process of evaporating and evaporating ethanol directly from the ethanol fermenter under the depressurized condition in the predetermined temperature range. Shown in effect. In other words, in the method of the present invention, the energy required for the evaporation, concentration, and dehydration processes can be said to have reduced energy by more than half compared with the conventional method, as is apparent from Table 2 of [0049] described later. .

  From the aspect of effective production energy, as is clear from Table 1 of [0011] above, the conventional method produced only 1.26 MJ / Liter, for example. As can be seen from the above, in the present invention, for example, 7.32 MJ / Liter and ethanol capable of effectively producing a large amount of energy are obtained. It is shown that energy production more friendly to the environment is possible by devising the configuration and operating conditions of the ethanol production apparatus as in the present invention.

  The technical problem of the present invention relates to the concentration and dehydration of ethanol. How to evaporate ethanol is performed at a low temperature, preferably at a normal temperature, and the above-mentioned structure is not required without taking a complicated structure as in a multistage distillation apparatus. The purpose is to develop a method for simplifying the processing.

  Therefore, basic investigations were made on the properties of ethanol, such as the relationship between temperature and pressure during vaporization, and the molar ratio of vaporized alcohol at each mixing ratio with water.

  Ethanol dissolves in water indefinitely. The boiling point is 78.4 ° C. At atmospheric pressure (100 KPa), the distillation separation in the ethanol-water binary system has an azeotropic point of 78.15 ° C and reaches vapor-liquid equilibrium at 89.4 mol% (95.6 wt%).

In order to vaporize ethanol at 30 ° C., the pressure is reduced to about 10.7 KPa. If it is 35 ℃, it is about 13.3KPa. If it is 40 ℃, it is about 17.3KPa. If it is 50 ℃, it is about 29.3KPa. Is the condition.
In addition, when mixed with water, the amount of ethanol in the gas at the time of vapor-liquid equilibrium at a normal pressure (100 KPa) of 10 mol% ethanol solution is about 45 mol%. About 53 mol% with 20 mol% ethanol solution. About 58 mol% with 30 mol% ethanol solution. It is.
Reference: Handbook of Distillation Engineering, Asakura Shoten Co., Ltd. Publishing

  In the conventional method, taking into account the various properties of these ethanols, we have obtained about 98% by weight of ethanol by applying approximately 11.30 MJ of energy to ethanol production of 1 Liter by multistage distillation and azeotropic distillation. is there.

  As a problem of the distillation method in the conventional method, the inventors are heating on the premise that the entire amount of the fermentation broth is vaporized. The fermentation liquid is mainly stored in the tank or agitated from the liquid surface while stirring. The total amount of ethanol in the fermentation broth has not been transferred to the concentrate side. As a result, it was found that the loss of energy was a big energy loss, and the specific goal was to solve these technical problems.

  First, the heating in the apparatus for evaporating and evaporating ethanol in the fermentation broth was 30 ° C. or more and 50 ° C. or less, preferably 35 ° C. or more and 40 ° C. or less. This is because the conditions within the range of 30 ° C. to 50 ° C. are within the range of the fermentation temperature of the ethanol-producing yeast in the ethanol fermenter, and the heating operation itself for distillation may be unnecessary. Therefore, the fermenter can be used as it is as an ethanol evaporating tank.

  Furthermore, in this fermenter and evaporative evaporation tank, the ethanol produced by fermentation is immediately removed, which leads to prevention of product fermentation inhibition in ethanol fermentation, and has the secondary effect of facilitating ethanol fermentation. It is believed that there is.

  Next, in the conventional method, the entire fermentation broth was heated and vaporized from the surface of the liquid, but with this, the efficiency of heat transfer and diffusion was extremely poor, and the conditions for heating at about 50 ° C and normal pressure operation were used. Underneath evaporation and vaporization is almost impossible. Therefore, as a condition for causing ethanol vaporization, the pressure was reduced to 10.7 KPa or more and 29.3 KPa or less, preferably 13.3 KPa or more and 17.3 KPa or less. This decompression condition is an operation condition necessary for vaporizing ethanol at 30 to 50 ° C. or 35 to 40 ° C. described in [0028].

  Further, the fermented liquid is sucked by a pump from the liquid storage part below the fermenter / evaporation tank, and dripped like a drizzle from above with a shower nozzle, and the tank has a water-absorbing filling such as a sponge ball. A mechanism to hold the

  In other words, during the fermentation period, the fermented liquid circulates through the fermenter / evaporation tank through the water-absorbing packing from the top to the bottom, while the fermentation liquid is adsorbed on the water-absorbing packing. By doing so, the vaporization of ethanol progresses as alcohol fermentation continues.

  From the fermented liquor that is drizzled from the upper shower nozzle and descends in the tank, ethanol is effectively vaporized and evaporated due to its large surface area effective for evaporation. In addition, even in water-absorbing packings such as sponge balls, the specific surface area for ethanol evaporation is increased due to the porous shape, and the most effective ethanol in low temperature and reduced pressure conditions. Evaporation will be promoted.

  The technical background of the invention is based on the physicochemical separation of solvents, etc. by a combination of gas-liquid separation and vacuum degassing in a packed tower, and biochemically by product removal. This method is supported by practical technology based on the effects of reducing fermentation inhibition and providing a place for growing microorganisms.

As a best mode for carrying out the present invention, a process flow is shown in FIG. Boil and ripen fermentation raw materials rich in carbohydrates and put them into the fermenter. The concentration of saccharide is generally preferably 10 to 20% by weight, and liquefaction / saccharifying enzyme is added to 0.05 to 0.1% by weight of the amount of saccharide, and the ethanol yeast culture solution is added to 2 to 5% of the total fermentation solution. Add weight percent. The temperature of the fermenter is adjusted so that the fermentation proceeds in the range of 30 to 50 ° C. with a warmer / heater. Furthermore, in this fermenter, the fermented liquor stored below is sent upwards by pump power and is always circulated. This function will be described in more detail in FIG. Along with the circulation of the fermentation broth, the operation of the membrane dehydrator is started, and the vacuum pump as the driving force is operated to reduce the pressure inside the fermenter / vaporizer and maintain it at 10.7 KPa or more and 29.3 KPa or less. In this way, in the membrane type dehydrating concentration apparatus, concentrated ethanol is obtained on the non-permeating side, and moisture is discharged on the permeating side. The detailed configuration of this membrane-type dehydration concentration apparatus will be further described with reference to FIG.
As the post-treatment, the dehydration method for obtaining almost 100% anhydrous ethanol is the same as in the conventional method, but the molecular sieve 3A, which is generally a zeolitic water-absorbing agent, or its equivalent is used as a filler. The dehydration adsorption device used in the above is installed.

  FIG. 2 shows the configuration of the best mode of the fermenter / evaporator according to the present invention. The fermenter and evaporative vaporizer that has received fermentation material containing saccharide-rich fermentation materials, saccharifying enzymes, and yeast culture solution has an external circulation pump, and inside has a nozzle for sprinkling water. Has a layer of water-absorbing filler such as sponge balls. The inside of the tank is maintained at 30 to 50 ° C by a warmer / heater, and ethanol fermentation proceeds. Therefore, the fermentation liquor stored in the lower layer part passes through the circulation pump to the upper nozzle and is sprinkled and adsorbed to the water-absorbing filler, and then moves downward, during which ethanol fermentation and evaporation evaporate. Evaporation and vaporization are performed when the inside of the tank is depressurized to 10.7 KPa or more and 29.3 KPa or less by operating a vacuum pump attached to the latter stage of the membrane type dehydrating and concentrating apparatus.

  FIG. 3 shows a flow chart of the best mode of the membrane type dehydrating and concentrating apparatus in the present invention. The vaporized gas obtained from the fermenter / evaporator through ethanol fermentation contains water vapor along with ethanol vapor. The membrane-type dehydration concentration apparatus is an apparatus for dehydrating and concentrating ethanol using an aromatic polyimide membrane having a function of selectively permeating water vapor. First, the temperature is maintained at 110 ° C. or higher by the heater at the entrance, and both ethanol and moisture are completely vaporized. Then, a vacuum pump is provided in the permeation direction of the membrane, and the pressure is generally adjusted to about 12 KPa. On the non-permeate side of the membrane, the ethanol vapor is cooled to below normal temperature by the cooler A, becomes an ethanol liquid, and accumulates in the storage tank. Water vapor is obtained on the permeate side of the membrane, and the water vapor is cooled to below normal temperature by the cooler B to become water (liquid) and accumulate in the storage tank. The flow path to the vacuum pump also passes through the cooler B in order to suppress vaporization from the water receiving tank. Although there is no technically advanced structure for the membrane type dehydrating and concentrating device, it can be said that the performance of the aromatic polyimide membrane in the membrane unit dominates the function of this device.

  In the apparatus configuration shown in FIGS. 1 to 3, a system for obtaining 20 Liter of absolute ethanol was assembled, and the energy required for the evaporation, concentration, and dehydration processes was calculated. As the basic properties of ethanol, molecular weight 46.08, density weight 0.785g / ml at 25 ℃, evaporation enthalpy 38.6KJ / mol, and 22.4Liter / mol and 1MJ = 0.278Kw = 239Kcal in the calculation process Used for system conversion.

  Therefore, the process that requires energy for operation is mainly the operation of the heater and the vacuum pump in FIG. The energy required for processing 20 Liter, 75 wt% ethanol vapor in a membrane dehydration concentrator was calculated.

  The ethanol weight is 15.7 kg, which corresponds to 0.341 Kmol. The water weight is 6.37 Kg, which corresponds to 0.354 Kmol. Water takes 1.60 MJ of heat, assuming that it is warmed and evaporated from 50 ° C to 110 ° C. The amount of heat required for heating and evaporating ethanol based on the enthalpy of evaporation is 13.2 MJ. Therefore, the energy required for vaporization here was 14.8 MJ.

Next, in order to create a vacuum / depressurized state, the total amount of ethanol vapor and water vapor is 15.6 m ³ for the energy to operate the vacuum pump. The capacity specification of the vacuum pump here is 2m ³ /h×10KPa×2.2Kw, so it takes 7.8 hours to discharge the whole amount up to 10KPa. In other words, the energy required to operate the vacuum pump to increase the vacuum is 61.7MJ It is. Furthermore, since ethanol fermentation continues for 72 hours, the remaining 64.2 hours will be used to maintain a vacuum of 10 KPa, and its operation is expected to be 20%. In other words, the energy required to operate the vacuum pump that maintains the vacuum is 28.2 MJ. is there. Therefore, the energy required to operate the vacuum pump was 89.9MJ.

  Therefore, in the best mode of the present invention, the energy required for the evaporation, concentration and dehydration process is 104.7 MJ, that is, 5.24 MJ / Liter per 20 Liter of ethanol production. This is more than half the energy saving effect compared to the conventional method. The results are shown in Table 2.

1 is a schematic configuration diagram illustrating a best mode for carrying out the present invention. [BRIEF DESCRIPTION OF THE DRAWINGS] It is a schematic block diagram of the ethanol fermenter and evaporating tank which showed the best form for implementing this invention. 1 is a schematic configuration diagram of a membrane dehydration concentration apparatus showing the best mode for carrying out the present invention.

Claims (6)

In the process of separating and concentrating ethanol from the ethanol fermentation liquor, a dehydrating and concentrating device that removes water from the evaporated gas and a fermenter / evaporator that evaporates and evaporates ethanol directly from the ethanol fermenter under reduced pressure conditions within a predetermined temperature range. Ethanol separation and concentration system characterized by comprising The fermenter / evaporation tank according to claim 1 has a nozzle that sprinkles water on the inside, and feeds the fermentation liquid stored below to the nozzle above by pump power or the like to circulate the liquid. The ethanol separation / concentration system according to claim 1, which has a function of The fermenter / evaporation / vaporization tank according to claim 1 has a water-absorbing filler inside, and continues fermentation of the fermentation liquid in the filler, and vaporization and evaporation of ethanol. The ethanol separation and concentration system according to claim 1. The ethanol separation / concentration system according to claim 1, wherein the fermenter / evaporation tank according to claim 1 has an internal temperature of 30 ° C. or more and 50 ° C. or less. The ethanol separation / concentration system according to claim 1, wherein the fermenter / evaporation tank according to claim 1 has an internal pressure of 10.7 KPa or more and 29.3 KPa or less. The dehydrating and concentrating device according to claim 1 is a dehydrating and concentrating device using an aromatic polyimide-based synthetic membrane having a performance of permeating and removing mainly moisture from gas with water vapor. Ethanol separation and concentration system as described.

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