JPS62135440A - Method for concentrating and purifying alcohol - Google Patents

Abstract

PURPOSE:To separate and to concentrate a high-purity alcohol in reduction of energy, by bringing a raw material consisting of an alcohol, a high-boiling impurity and water into contact with a solvent in a supercritical state in counter current, reducing pressure of the prepared extracted solution at two stages and successively separating the high- boiling impurity and the solvent. CONSTITUTION:A raw material mixture comprising an organic liquid solute consisting of an alcohol and a high-boiling impurity and water is fed from a top part 1 of a counter current contact extractor 3 and a solvent having a critical temperature lower than the boiling point of the alcohol from a bottom part 2. The raw material is brought into contact with the solvent in counter current in a state wherein the solvent is in a supercritical state or psudocritical state and a light solution containing the solvent and the alcohol and a small amount of the high-boiling impurity and water is taken out from a top part 6. The pressure of the light solution is reduced 7 to pressure required from phase separation of the high-boiling impurity, introduced to an impurity separating tank 9 and a separated heavy impurity solution is fed to a middle part 11 of the device 3. The pressure of the light purified solution is reduced 14 to pressure required for phase separation of the solvent and the alcohol, introduced to a solvent separating tank 16 and the concentrated alcohol is taken out from the bottom and partially fed to the device 3.

Description

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

[Conventional technology]

Fermented alcohol made from carbohydrates such as 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 10 to 10. Since it is as low as 20 wt%, it is necessary to concentrate it to about 95 to 100 wt%.

Conventionally, distillation has been used as this 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 is needed instead. We are hoping for the development of

Conventionally, an energy-saving 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 then kneaded. (Unexamined Japanese Patent Publication No. 56-56201 and No. 59-1415
(No. 28) However, this concentrated fermented alcohol contains by-products such as high-boiling point impurities (04-C5 fusel oil), and these also need to be separated and removed. Conventionally, a rectification column using a distillation method has been used as a removal method, but in this case, the entire concentrated alcohol must be heated again, which increases the heat load and has the disadvantage that it cannot be said to be an energy-saving method. t.

[Problem that the invention seeks to solve]

The present invention provides an energy-saving separation and recovery method when separating and recovering alcohol substantially free of water and high-boiling point impurities from a mixture of alcohol, water, high-boiling point impurities, etc. That is.

[Elaborate means to solve problems]

That is, in the present invention, a raw material mixture of an organic liquid solute consisting of alcohol and high-boiling point impurities and water is prepared from the upper part of a gold circulation contact extraction apparatus, and a bath agent whose critical temperature is lower than the S point of the alcohol is prepared by the self-flow contact extraction. The raw material mixture, the solvent gold, and the solvent are brought into contact with each other in the same flow under conditions that bring them into a supercritical or quasi-critical state. Remove the heavy liquid from the bottom,
Next, the nuclear light liquid is depressurized to the pressure required to substantially phase-separate impurities that may cause flat boiling, and then introduced into an impurity separation tank where it is separated into a heavy impurity liquid and a light top liquid. is introduced between the raw material mixture supply section and the solvent supply section of the countercurrent contact extraction device, and the light purified liquid is introduced into the solvent separation tank, and the pressure is increased to the level required for phase separation of the dissolved solvent and concentrated alcohol. This alcohol concentration and purification method is characterized in that after pressure reduction, a part of the alcohol is introduced into the upper part of the raw material mixture supply section.

The raw material mixture of the present invention is mainly fermented alcohol, and a typical composition is theal. Alcohols include methyl alcohol, ethyl alcohol, propatool, phthanol, and the like.

In addition, as a dissolving solvent, in addition to C02*C2H4*C2H4, etc., inorganic or organic solvents whose temperature is below the critical temperature or the boiling point of alcohol can be used, as seen in JP-A No. 56-56201. It is. Table 1 shows the main solvents.

Table 1 Solvent name Critical temperature (℃) CO□ 31.1 C2H49,7 0, H, 32,4 a3as l&8 C4HI0152.0 H2S 10I14 N20 36.5 In particular, the closer the critical temperature is to room temperature, the lower the affinity with alcohol. The larger the solvent, the greater the energy saving effect, and is therefore a preferable solvent. Also, these can be used in combination. Generally, the dissolving solvent is added in an amount of 2 to 10 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 state B under the condition of temperature and pressure that is higher than the critical temperature of the dissolving solvent and one level higher than the critical pressure, and the term "quasi-critical state" means the critical temperature Tc or lower of the dissolving solvent. Then, the critical temperature TR=T/TO (however, (190(Tr(1,
At a temperature T of 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.

The countercurrent contact device is preferably a packed column, a tray column, a multistage extraction column, or the like.

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

By supplying 1 part by weight of the raw material mixture from the upper part 1 of the countercurrent contactor 3 and 2 to 10 parts by weight of the dissolving solvent from the lower part 2, and bringing them into contact in the same flow in the critical state or quasi-critical state of the dissolving solvent. As the light dissolved solvent phase rises, alcohols are selectively extracted from the raw material mixture phase and taken out as a light liquid from the upper part 6. The amount of the dissolving solvent added can be reduced if the dissolving solvent has a high affinity with alcohols.

The raw material mixture phase descends to the lower part as a heavy liquid while extracting alcohol, and is extracted from the lower part 5.

The light liquid from the upper part 6 contains a small amount of high-boiling point impurities and water in addition to the dissolving solvent and alcohol, and the water and impurities do not meet the product specifications and must be separated and removed.

The solubility of water and impurities in a dissolving solvent is approximately proportional to the density of the dissolving solvent, and by lowering the pressure or increasing the temperature to reduce the density of the dissolving WIf6 agent, the solubility of water and impurities in the dissolving solvent can be reduced. , the high boiling point substance first phase separates from the dissolved solvent.

Raising the temperature is undesirable as it results in a decrease in thermal efficiency.
Therefore, it is preferable to lower the ff1ll of the dissolving solvent by lowering the pressure. However, if the pressure is lowered too much, the strength of the dissolving solvent bath will decrease significantly and a large amount of alcohol will phase separate, so it is necessary to control the pressure by controlling the amount.

The present invention utilizes this phenomenon to improve the purity of concentrated alcohol.

That is, the light liquid is depressurized by a pressure reducing valve 7 so as to selectively phase-separate high-boiling point impurities, and is introduced into an impurity separation tank 9 through a line 8, where it is separated into light fine flour and heavy impurity liquid. Separate. The light Tft liquid is a mixture of alcohol, a very small amount of water, and high-boiling point impurities in addition to the dissolving solvent.

The heavy impurity liquid is a mixture of water, high boiling point impurities, a very small amount of alcohol, and a dissolving solvent.

The light purified liquid is extracted from +3, reduced in pressure by a pressure reducing valve 14 to a pressure necessary for phase separation of the solvent M and the alcohol, and then introduced into the dissolved solvent separation tank 16 through a line 15.

The alcohol taken out from the dissolved solvent separation tank 16 via the line 17t contains trace amounts of water and high boiling point impurities, but a portion of the alcohol is taken out via the line 20 to the cocurrent contactor. Circulate to the top of 4. This reflux effect greatly improves the purity of the alcohol. Also, the purity of the alcohol increases as the circulating flow order increases.

From the upper part of the dissolving solvent separation P/J 16, the dissolving bath agent is recovered through a line 18, a pressure reducing valve 19, and a line 22 to be reused.

A small amount of alcohol is dissolved in the heavy impurities taken out from the bottom of the impurity tank 9 via the line 10, so it must be recovered to prevent loss of product alcohol. There is.

In the present invention, the heavy impurities are moved in the direction θ1f.

By reintroducing the alcohol into the contacting device 5 via the line 11, loss of alcohol is prevented, and heavy impurities with high stains are separated and removed. The introduction section for the heavy impurities is determined depending on the composition thereof, but is preferably between the raw material mixture introduction section 1 and the dissolving solvent introduction section 2.

In Figure 1, 21 is the product alcohol removal line; 1
2 is a heavy impurity discharge line.

Hereinafter, the present invention will be explained in detail by giving examples of the present invention.

Example: 1 part by weight of a raw material mixture of 10 wt% ethyl alcohol, 1 wt% 04-Os fusel oil, 89.9 wt% water, a total of 6 parts by weight of carbon dioxide and 5 parts by weight of ethane as a dissolving solvent, an inner diameter of 50 wm. , was supplied to a part 1 m from the top and 50 cm from the bottom of a 3 m long optical packed column, and brought into countercurrent contact at a pressure of 150 atm and a temperature of 40°C, with light liquid coming from the top of the column and heavy liquid coming from the bottom of the column. The light liquid is depressurized to 90 atm in an impurity separation tank and separated into a light purified liquid and a heavy impurity liquid.
．． The entire amount was returned to the 5 m site.

In addition, the light purified liquid is reduced to a pressure of 30 atm in a dissolution solvent separation tank, and phase-separated into a dissolution solvent and concentrated ethyl alcohol.
90 g of the concentrated ethyl alcohol was circulated to the upper part of the packed column.

Then, the operation was continued until the whole became steady, and as a result, the raw material ethyl alcohol reached 99%. Owt% was recovered, in which the concentrations of water and high-boiling impurities were 5.1 wt% and 9%, respectively.
Next at 8 ppm.

Comparative Example 1 In Example 1, when the heavy impurity liquid and concentrated ethyl alcohol were operated without returning to the packed column, only 9αOwt% of the raw material ethyl alcohol was recovered, and the concentrations of water and high boiling point impurities were respectively 10 wt%, 100
Atsushi at 0 ppm.

Comparative Example 2 In Example 1, when only the heavy impurity liquid was operated without returning to the packed column, 97% of the raw material ethyl alcohol was reduced. Q
The concentration of water and high boiling point impurities was 9 wt% each. It was 800 ppm.

[Effects of the present invention J As detailed above, the present invention relates to alcohol.

This method completely separates a mixture of water and high-boiling point impurities by controlling the pressure in three stages at room temperature using a near-critical dissolving solvent, resulting in a fast separation speed and compact equipment. In addition, 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 1. Sub-Agents 1) Meifuku Agent Ryo Hagiwara − Sub-Agent Atsuo Anzai

Claims (1)

[Claims] A raw material mixture of an organic liquid solute consisting of alcohol and high-boiling point impurities and water is supplied from the top of a countercurrent contact extraction device,
Further, a solvent whose critical temperature is lower than the boiling point of the alcohol is supplied from the lower part of the countercurrent contact extraction device, and the raw material mixture and the solvent are oriented under conditions that bring the solvent into a supercritical or pseudocritical state. A light liquid is taken out from the upper part of the countercurrent contact extraction device and a heavy liquid is taken out from the lower part.The light liquid is then depressurized to a pressure necessary for substantially phase separation of high-boiling point impurities.
Introducing into an impurity separation tank to separate into a heavy impurity liquid and a light purified liquid, and introducing the heavy impurity liquid between the raw material mixture supply part and the solvent supply part of the countercurrent contact extraction device,
The light purified liquid is introduced into a solvent separation tank, and after the pressure is reduced to the pressure necessary for phase separation of the dissolved solvent and the concentrated alcohol, a portion of the concentrated alcohol is transferred to the upper part of the raw material mixture supply section of the countercurrent catalytic extraction device. An alcohol concentration and purification method characterized by the introduction of