JPS6225983A - 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 mixture of water, an alcohol and impurities and blending them in a supercritical state of the solvent. CONSTITUTION:A mixture comprising 10-20% alcohol, a small amount of high-boiling impurities and the rest of water is blended with a solvent (CO2 or 2-4C hydrocarbon) to dissolve only the alcohol, fed to the blender 4 and well blended in the supercritical (pseudo critical) state of the solvent and introduced to the first extracting and separating tank 5. 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 into the concentrated and purified alcohol and a solution containing the impurities, water and a small of the alchool. The latter is mixed with the heavy solution extracted from the tank 5, they are blended with a solvent, fed to the second extracting and separating tank 17, separated similarly into a heavy solution and a light solution and the light solution is collected as the concentrated and purified alcohol.

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 wt%. For,
It is necessary to concentrate to about 95-100 wt%.

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, so there is a need to develop an energy-saving concentration method instead. 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 Publications No. 56-56201 and No. 59-I A
(No. 1528) However, by-products such as high-boiling impurities (04-C5 fusel oil) are mixed into the fermented alcohol concentrated by the method, and these also need to be separated and removed. Conventionally, a rectification column using a distillation method has been used for this separation and removal method, but at this time, the concentrated alcohol has to be heated again and evaporated and condensed, increasing the heat load and reducing overall energy savings. The drawback was that it could not be called a standard method.

[Problem that the invention seeks to solve]

The present invention uses concentrated alcohol obtained by separating alcohol from water using carbon dioxide gas, ethylene, ethane, etc. in a supercritical or quasi-critical state, which is substantially free of water and high-boiling point impurities in terms of energy saving. It is intended to provide a method for obtaining concentrated alcohol.

[Means for solving problems]

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 pressure of the impurity separation tank is reduced 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 extracted from the first extraction and separation tank. The dissolving solvent is brought into contact with the mixed liquid again 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 impurities in a second extraction separation tank. This is a method for concentrating and purifying alcohol, which is characterized by separating into a heavy liquid consisting of a dissolving solvent and a light liquid consisting essentially of a dissolving solvent and alcohol, and further recovering the latter as concentrated purified alcohol.

The dissolving solvent used in the present invention is a K solvent that dissolves alcohol well and dissolves water and heavy impurities. In addition to hydrocarbons such as 02H4,4 having 2 to 4 carbon atoms, 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 name Critical temperature Co, 31.1 C, H, 9,7 C! , HL13Z4 0, Fi692.3 (1, H896,8 0, H,. 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, the dissolving solvent is added in an amount of 2 to 6 parts by weight per 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,
A quasi-critical state is a temperature below the critical temperature Tc of the dissolving solvent, with respect to the critical temperature Tr-T/To (however, 0.90 (Tr(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 dissolution solvent supply line, 3 is a mixing fin for fermentation alcohol and dissolution 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 Line 20 is a high pressure metering pump.

Alcohol supplied from supply line 1 (e.g. water: 8
0-90 vt%, alcohol; 10-20 wt%
, high boiling point impurities such as 04-G5 fusel oil: Q,
1 vrt%) and the dissolving solvent supplied from the supply line 2 are pumped by a high-pressure pump (not shown) and mixed in the mixing line 3, and the temperature is adjusted by a heat exchanger (not shown) to reach a supercritical or pseudo-critical state. The mixture reaches a critical state and 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.

The first extraction separation tank 5 is preferably a gravity settling tank, but countercurrent extraction and separation using a packed column or plate column that performs mixing and extraction at the same time 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 by lowering the pressure or increasing the temperature, the density of the dissolving solvent decreases and the solubility decreases.On the other hand, the rate of decrease in solubility of substances with high boiling points decreases. The present inventors have obtained the knowledge that the high boiling point component selectively undergoes phase separation due to a slight decrease in the density of the dissolving solvent because of the large .

Therefore, an impurity separation tank? Then, high boiling point impurities (C'4~
C6 type fusel oil) undergoes phase separation first and is separated from alcohol. Therefore, from the upper part 11 of the impurity separation tank 9,
Concentrated alcohol from which high-boiling 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 impurity mixture phase-separated in the impurity separation tank 9 and taken out from the high-boiling impurity extraction line 10 contains some water and alcohol, and the alcohol needs to be recovered to prevent loss. . 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 it is preferably operated in a supercritical state of a dissolving solvent in which water and high-boiling impurities selectively phase separate from alcohols. It is better to do so. Through this operation, alcohol substantially free of water and high-boiling point impurities is recovered from the second extraction separation tank 17 through the low-boiling point component extraction line 19,
It has been found that losses can be prevented.

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゜Ethanol 10 wt%, 04~he system fusel oil α1v
6 parts by weight of CO as a dissolving solvent was added to 1 part by weight of a mixture of 9 wt % and 9 wt % of H, and the pressure was 110 atm.
The liquid was brought into contact for 40 minutes in a supercritical state at a temperature of 40°C, and separated into a light liquid and a heavy liquid in a gravity settling tank.

Next, the light liquid was extracted from the upper part of the gravity settling tank and introduced into the impurity separation tank, and the pressure was increased to 110 at while keeping the temperature at 40°C.
The pressure was reduced from m to 80 atm, and an impurity mixture containing fusel oil, water, and ethanol was taken out from the lower part of the phase separation tank. Analysis of the residue in the phase separation tank revealed that
The composition other than CO is 80% ethanol, 20% water, "L"
~(1 below the fusel oil detection limit) Ethanol was concentrated.

Next, the impurity mixture and the heavy liquid were mixed, 6 parts by weight of CO, as a dissolving solvent was added to 1 part by weight of the mixture, and the pressure was 9 parts by weight.
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. When the light liquid was analyzed, it was found that the composition other than CO was 70% ethanol, 30% water, and that it could be recovered as a product under the detection limit of 04-C5 fusel oil.

Example Z 10 wt% ethanol, C4-C2 fusel oil Q,
1 vt%, %00.00 as 1 part by weight of a mixture of 89.9 wt% as a dissolving solvent. Add 6 parts by weight of
tm 1 in a quasi-critical state at a temperature of 20°C for 40 minutes,
It was separated into light liquid and heavy liquid in a gravity settling tank.

Next, the light liquid is extracted from the upper part of the gravity settling tank and introduced into the impurity separation tank, where it is heated to a temperature of 40°C and a pressure of 110 at.
The pressure was reduced from m to 80 atm, and an impurity mixture containing 7-gel oil, water, and ethanol was taken out from the bottom of the phase separation tank. Analysis of the residue in the phase separation tank revealed that
Composition other than CO: 80% ethanol, 20% water, 04
~ C6 fusel oil detection limit or below, ethanol was concentrated.

Next, mix the impure physical compound and heavy liquid 1, add 6 parts by weight of CO as a dissolving solvent to 1 part by weight of the mixture, and press 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. When the light liquid was analyzed, CO! It was found that the remaining composition was 68% ethanol, 32% water, and below the detection limit for C, ~, -based fusel oil, and could be recovered as a product.

[Effects of the present invention]

As detailed above, the present invention 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. Second, the separation speed is fast, the device can be made more compact, and the thermal load is reduced, resulting in an energy-saving effect.

[Brief explanation of the drawing]

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. and separating the mixture into a heavy liquid consisting essentially of water and high-boiling impurities and a light liquid consisting essentially of a dissolving solvent and alcohol in a second extraction separation tank, and further recovering the latter as concentrated purified alcohol. A method for concentrating and purifying alcohol, which is characterized by: