JPS6225984A - Method of concentrating and purifying alcohol - Google Patents

Abstract

PURPOSE:To obtain a highly concentrated alcohol having low content of impurities with reduced energy, by adding a solvent for alcohol to a mixed solution of water, an alcohol and impurities and blending them in a supercritical state of the solvent. CONSTITUTION:A mixture of 10-20% alcohol, a small amount of a high-boiling impurities and the rest of water is mixed with a solvent (CO2 and 2-4C hydrocarbon) to dissolve only the alcohol and fed to the blender 4, where they are well blended in a supercritical (pseudo critical) state of the solvent and sent to the first extracting and separating column 5. In the tank, they are separated into a heavy solution consisting of water, the impurities and part of the alcohol and a light solution consisting of the solvent, the alcohol and part of the impurities. The light solution is fed to the impurity separating tank 9, the pressure of the tank is reduced and the solution is separated tank 9, the pressure of the tank is reduced and the solution is separated into the concentrated and purified alcohol and a solution containing the impurities, water and a small amount of the alcohol. The latter is blended with the heavy solution extracted from the tank 5, incorporated with a solvent, sent to the second extracting and separating tank 17, similarly separated into a heavy solution and a light solution and the light solution is returned to the first blending tank 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for concentrating and purifying highly pure alcohol from fermented alcohol and the like in an energy-saving manner.

[Conventional technology]

Fermented alcohol made from carbohydrates such as amashiyo, sweet potato, and corn is an important starting material for beverages and industrial use, but the alcohol concentration of the alcohol aqueous solution obtained by the fermentation method is as low as 10 to 20 yt%. For,
It is necessary to concentrate to about 95-100 vt%.

Conventionally, distillation has been used as a concentration method, but water, which makes up most of the water, must be heated to 80 to 100°C, which is economically disadvantageous, and an energy-saving concentration method has been proposed instead. Development is desired.

BACKGROUND ART Conventionally, as an energy-saving concentration method, a method has been proposed in which alcohol is extracted and separated from water using carbon dioxide, ethylene, or ethane in a supercritical or quasi-critical state and concentrated. (Unexamined Japanese Patent Publication No. 56-56201 and No. 59-1415
However, the fermented alcohol concentrated by this method contains high boiling point impurities (04~(:!5 series 7-
If by-products such as zel oil are mixed in, these also need to be separated and removed. Conventionally, a rectification column using a distillation method has been used to separate and remove them. This method has the disadvantage that the alcohol has to be heated again and evaporated and condensed, increasing the heat load, and that it cannot be said to be an energy-saving method as a whole.

[Problem that the invention seeks to solve]

The present invention uses concentrated alcohol obtained by separating alcohol from water using supercritical or quasi-critical carbon dioxide, ethylene, ethane, etc. in an energy-saving manner and substantially contains no water or high-boiling point impurities. It is intended to provide a method for obtaining concentrated alcohol.

[Failure to solve the problem]

That is, the present invention adds a dissolving solvent to a mixture of alcohol, an organic liquid solute consisting of high-boiling point impurities, and water, and forms a mixture by contacting the dissolving solvent under conditions that bring the dissolving solvent into a supercritical or quasi-critical state. The mixture is led to a first extraction separation tank, and a heavy liquid containing water as the main component and most of the high-boiling point impurities, some alcohol, and a dissolving solvent, and a heavy liquid that is mainly composed of water and containing most of the alcohol and a dissolving solvent are separated. The light liquid is extracted from the first extraction separation tank and introduced into the impurity separation tank, and the impurity separation tank is depressurized to substantially contain the high-boiling impurities. The alcohol from which water has been removed is separated into a liquid containing substantially water, high-boiling point impurities, and a small amount of alcohol, the former is recovered as concentrated purified alcohol, and the latter is collected as a heavy liquid from the first extraction separation tank. The mixture is again brought into contact with the dissolving solvent under conditions of a supercritical state or a quasi-critical state to form a mixture, and the mixture is substantially separated from water and high-boiling point impurities in a second extraction separation tank. This alcohol concentration and purification method is characterized in that the alcohol is separated into a heavy liquid consisting of a dissolving solvent and a light liquid consisting essentially of a dissolving solvent and alcohol, and the latter light liquid is circulated to the first extraction separation tank.

The dissolving solvent used in the present invention is a solvent that dissolves alcohol well but does not easily dissolve water and heavy impurities. In addition to hydrocarbons such as Vllk, 02B6, and mixtures thereof, inorganic or organic solvents having a critical temperature below the boiling point of alcohol, or mixed solvents thereof can be used. The table below shows the main solvents.

Solvent base Critical temperature Co231. I C, H, 9, 7 02 horses 514 0sH692, 3 03H896, 8 04HI0 152.0 As a dissolving solvent, the closer the critical temperature is to room temperature and the greater the affinity with alcohol, the greater the energy saving effect, so it is preferable. . Generally, 2 to 6 parts by weight of the dissolving solvent is added to 1 part by weight of the raw material alcohol, but in the case of a dissolving solvent having a high affinity with alcohol, the amount added can be smaller than the above range.

The supercritical state as used in the present invention refers to a state under temperature and pressure conditions that are higher than the critical temperature and critical pressure of the dissolving solvent,
The quasi-critical state is below the critical temperature Tc of the dissolving solvent, with respect to the critical temperature Tr = T/Tc (however, 0.90 < Tr
At a temperature T of <1.0), the pressure means a state equal to or higher than the saturated vapor pressure of the dissolving solvent at that temperature. Although the solubility of the dissolving solvent may increase in the quasi-critical state compared to the supercritical state, the dissolution rate tends to decrease.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIG.

In FIG. 1, 1 is a supply line for fermentation alcohol as a raw material, 2 is a supply line for dissolving solvent, 3 is a mixing line for fermentation alcohol and dissolving solvent, 4 is a mixer, 5 is a first extraction separator, and 6 is a Heavy liquid extraction line, 7 is a light liquid extraction line, 8 is a pressure reducing valve, 9 is an impurity separation tank, 10 is a high boiling point impurity extraction line, 11 is a low boiling point component (alcohol) extraction line, 12 is a high pressure metering pump, 13 is Heavy liquid supply line, 14 is a dissolving solvent supply line, 15 is a high boiling point impurity supply line, 16 is a mixer, 17 is a second extraction separator, 18 is a high boiling point impurity extraction line, 19 is a low boiling point component (alcohol) extraction The circulation line 20 is a high pressure metering pump.

Alcohol supplied from supply line 1 (e.g. water stem 8
0-90 vt%, alcohol: 10-20 wt%
, high boiling point impurities such as C4-05 fusel oil: 11
j wt%) and the dissolving solvent supplied from the supply line 2 are pumped by a high-pressure pump (not shown) to the mixing line 3.
The mixture is mixed in the mixer 4, and the temperature is adjusted by a heat exchanger (not shown) to reach a supercritical or quasi-critical state, and the mixture is further thoroughly mixed in the mixer 4. The mixer 4 is preferably a line mixer or a static mixer, but the mixer 4 is not necessarily required if sufficient mixing is achieved in the mixing line 3.

The sufficiently mixed liquid is sent to the first extraction separation tank 5, where it is sufficiently contacted and mixed under conditions where the dissolving solvent becomes supercritical or quasi-critical, and most of the concentrated alcohol containing the dissolving solvent as the main component is removed. , a light liquid containing some high-boiling point impurities,
It is separated into a heavy liquid, which is mainly composed of water and contains most high-boiling point impurities, some alcohol, and a dissolving solvent.

This first extraction and separation tank 5 is preferably a gravity settling tank, but countercurrent extraction and separation using a packed column or plate column in which mixing and extraction are carried out simultaneously can also be advantageously used.

The downstream stream including the mixer 4 is at least in a supercritical or quasi-critical state of the dissolving solvent.

That is, in the mixer 4, the raw material and the dissolving solvent are sufficiently mixed and contacted to extract the alcohol in the raw material into the dissolving solvent, but the extraction rate is increased by decreasing the viscosity and surface tension of the dissolving solvent and increasing the diffusion coefficient. Preferably, this is achieved by bringing the dissolving solvent into a quasi- or supercritical state. Since the extraction rate is faster in the supercritical state than in the quasi-critical state, the former state is preferable in terms of extraction rate.

Next, the light liquid is extracted from 7, the pressure is lowered by a pressure reducing valve 8, and the light liquid is introduced into an impurity separation tank 9.

The solubility of a dissolving solvent is approximately proportional to the density of the dissolving solvent, and lowering the pressure or increasing the temperature lowers the density of the dissolving solvent and decreases the solubility.On the other hand, the solubility of substances with higher boiling points decreases. Since the ratio is large, the present inventor has obtained the knowledge that υ high boiling point components undergo selective phase separation due to a slight decrease in the density of the dissolving solvent.

Therefore, in the impurity separation tank 9, high boiling point impurities (C'4~
The alcohol-based fusel oil undergoes phase separation first and is separated from the alcohol. Therefore, from the upper part 11 of the impurity separation tank 9, concentrated alcohol from which high-boiling point impurities have been separated is recovered.

The pressure of the impurity separation tank 9 should be equal to or higher than the saturation pressure. If the pressure is reduced below that level, heat of vaporization of the dissolving solvent is required, which is not economical.

The high boiling point impurity mixture phase-separated in the impurity separation tank 9 and taken out from the high boiling point impurity counting line 10 contains some water and alcohol, and the alcohol needs to be recovered to prevent loss. There is. Therefore, this high-boiling point impurity mixture is mixed in the mixer 16 with the heavy liquid taken out from the heavy liquid take-out line 6 of the first extraction separator 5 and a new dissolving solvent sent from the dissolving solvent supply line 14. It is introduced into the second extraction separator 17.

The operating conditions of the second extraction separation tank 17 may be the same as those of the first extraction separation tank 5, but preferably the operating conditions are in a supercritical state of a dissolving solvent in which water and high-boiling impurities selectively phase separate from alcohols. It's better to manipulate. Through this operation, alcohol free of water and high-boiling point impurities is recovered from the second extraction separation tank 17 through the circulation line 19 for taking out the low-boiling point component (alcohol). However, since the alcohol recovered from this line 19 has a concentration of about 70% or less, it is insufficient as concentrated alcohol. Therefore, as shown in the figure, the alcohol recovered from this line 19 is returned to the first extraction separation tank 5 again and recovered as highly concentrated alcohol through the line 11.

In the above operation, the liquid at the intersection of the heavy liquid supply line 13, the dissolving solvent supply line 14, and the high boiling point impurity supply line 15 should be brought into a super(pseudo)critical state. Therefore, the heavy liquid extraction line 6 from the first extraction separator 5
and high boiling point impurity extraction line 1 from impurity separation tank 9
0 are provided with high pressure metering pumps 12 and 20, respectively.

Example 1 Using the flow shown in Figure 1, ethanol 10wt, %, 0
4~He series fusel oil Q, 1 wt%, H,089,9
Co as a dissolving solvent to 1 part by weight of the raw material mixture of wt.
2 was added thereto and brought into contact for 30 minutes in a supercritical state at a pressure of 110 atm and a temperature of 40° C., and separated into a light liquid and a heavy liquid in a gravity settling tank 5.

Next, the light liquid is extracted from the upper part of the gravity settling tank 5 and introduced into the impurity separation tank 9, and the pressure is increased to 110°C while keeping the temperature at 40°C.
The pressure was reduced from ATM to 80 ATM, and an impurity mixture containing 04 to C5 fusel oil, water, and ethanol was taken out from the upper part of the phase separation tank 9.

Analysis of the residue in the phase separation tank revealed that the composition other than aO was 80% ethanol, 20% water, and C4-C.

System 7 - Ethanol was concentrated below the detection limit of zel oil.

Next, the impurity mixture and heavy liquid were mixed, 6 parts by weight of C02 was added as a dissolving solvent to 1 part by weight of the mixture, and the pressure was 9.
They were brought into contact at 0 atm and a temperature of 40° C. and separated into a light liquid and a heavy liquid in a gravity settling tank 17.

Next, the entire amount of the light liquid and the raw material mixture 1 mentioned above were mixed and brought into contact at a pressure of 110 atm and a temperature of 40° C. for 30 minutes, separated into a light liquid and a heavy liquid in a gravity settling tank 5, and the same method as above was carried out. Processed.

As a result, concentrated and purified ethanol with a composition other than co such as 85% ethanol, 17% water, and below the detection limit of 04-Os type 7-zel oil was recovered from line 11.

Also, a heavy liquid substantially free of ethanol was taken out from line 18.

As a result, it is clear that the entire amount of ethanol in the raw material mixture was recovered.

Example 2 Ethanol 10 wt%, 04-C6 fusel oil I]
, 1 vt%, 089.9 wt% of the raw material mixture was added 6 parts by weight of CO as a dissolving solvent, and the pressure was 1.
The mixture was brought into contact for 30 minutes in a quasi-critical state at 10 atm and a temperature of 20° C., and separated into a light liquid and a heavy liquid in a gravity settling tank 5.

Next, the light liquid is extracted from the upper part of the gravity settling tank 5 and introduced into the impurity separation tank 9, where the temperature is heated to 40°C and the pressure is increased to 11°C.
The pressure was reduced from 0 atm to 80 atm, and an impurity mixture containing C, - C fusel oil, water, and ethanol was taken out from the upper part of the phase separation tank 9. Analysis of the residue in the phase separation tank revealed that the composition other than 002 was 80% ethanol and 22% water.
0%, C.

The ethanol concentration was below the detection limit for fusel oil.

Next, the impurity mixture and heavy liquid were mixed, 6 parts by weight of aO, as a dissolving solvent was added to 1 part by weight of the mixture, and the pressure was 9
They were brought into contact at 0 atm and a temperature of 40° C. and separated into a light liquid and a heavy liquid in a gravity settling tank 17.

Next, the entire amount of the light liquid and the raw material mixture 1 mentioned above were mixed and brought into contact at a pressure of 110 atm and a temperature of 40° C. for 30 minutes, separated into a light liquid and a heavy liquid in a gravity settling tank 5, and the same method as above was carried out. Processed.

As a result, concentrated and purified ethanol with a composition other than lines 11 to 6co, consisting of 84% ethanol, 16% water, and below the detection limit of 7-zel oil in lines 04 to 6co, was recovered.

Also, a heavy liquid substantially free of ethanol was taken out from line 18.

As a result, it is clear that the entire amount of ethanol in the raw material mixture was recovered.

[Effects of the present invention]

The present invention, as detailed above, separates a mixture of alcohol, water, and high-boiling point impurities by controlling the pressure in two stages at around room temperature using a near-critical dissolving solvent. Furthermore, the separation speed is high, the apparatus can be made compact, and the thermal load is reduced, resulting in an energy-saving effect.

[Brief explanation of drawings]

FIG. 1 is a flow sheet for implementing the present invention. Sub-Agents 1) Meifuku Agent Ryo Hagiwara − Sub-Agent Atsuo Anzai

Claims (1)

[Claims] A dissolving solvent is added to a mixture consisting of alcohol, an organic liquid solute consisting of a high-boiling point impurity, and water, and the dissolving solvent is brought into contact with the mixture in a supercritical or quasi-critical state to form a mixture. 1. The main component is water, most of the high boiling point impurities, some alcohol,
Separate into a heavy liquid containing the dissolving solvent and a light liquid containing the dissolving solvent as the main component, most of the alcohol, and some high-boiling point impurities, and extract the light liquid from the first extraction separation tank to separate impurities. The alcohol is introduced into a tank, and the impurity separation tank is depressurized to separate alcohol from which water is removed and which does not substantially contain high-boiling impurities, and a liquid containing substantially water, high-boiling impurities, and a small amount of alcohol; The former is recovered as concentrated purified alcohol, the latter is mixed with the heavy liquid from the first extraction and separation tank, and the dissolving solvent is brought into contact with the mixed liquid again under conditions to reach a supercritical state or a quasi-critical state to form a mixture. The mixture is separated into a heavy liquid consisting essentially of water and high-boiling point impurities and a light liquid consisting essentially of a dissolving solvent and alcohol in a second extraction separation tank, and the latter light liquid is subjected to the first extraction separation. An alcohol concentration and purification method characterized by circulation in a tank.