JPS6225985A - 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 low concentrated aqueous solution of an alcohol containing impurities from the top of a multi-stage extraction device of counter flow contact type, feeding a solvent from the bottom of the device and blending both in a supercritical state of the solvent. CONSTITUTION:A mixture consisting of 10-20% alcohol, a small amount of a high-boiling impurities and the rest of water is fed from the top of a multi- stage extraction device of counter flow contact type, a solvent (CO2, 2-4C hydrocarbon, etc.) for the alcohol is fed from the bottom of the device, the interior of the device 3 is made in a supercritical state of the solvent and both are brought into contact with eath other. A light solution is taken out from the top part 6 of the device 3, fed through the reducing valve 7 to the separating column 8, separated into the highly concentrated alcohol 10 with low impurity content and a heavy impurity solution, the latter is added to a mixture of the raw material and fed again to the multi-stage extraction device 3 of counter flow contact type.

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 vt%. 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 degrees Celsius, which is economically disadvantageous.Therefore, an alternative energy-saving concentration method has been developed. is desired.

Conventionally, as an energy-saving concentration method, a method has been proposed in which carbon dioxide, ethylene, or ethane in a supercritical or quasi-critical state is used to extract and separate alcohol from water and concentrate. (Unexamined Japanese Patent Publication No. 56-56201 and No. 59-1415
(No. 28) However, the fermented alcohol concentrated by this method contains by-products such as high-boiling point impurities (04-05 type 7-zel oil), 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 in this case, the concentrated alcohol must be reheated 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 is an energy-saving method for concentrating alcohol obtained by separating alcohol from water using carbon dioxide, ethylene, ethane, etc. in a supercritical or quasi-critical state, substantially free of water and high-boiling impurities. It seeks to provide a way to obtain alcohol.

[Means for solving problems]

That is, the present invention supplies a raw material mixture of an organic liquid solute consisting of alcohol and high-boiling impurities and water to the upper part of a multistage countercurrent catalytic extraction device, supplies a dissolving solvent from the bottom of the multistage countercurrent catalytic extraction device, The raw material mixture and the solvent are brought into countercurrent contact under conditions such that the solvent becomes a supercritical state or a quasi-critical state, and a light liquid is brought into contact with the solvent from the upper part of the multistage countercurrent contact extraction device.
The heavy liquid is taken out from the lower part, and then the light liquid is depressurized to the pressure necessary for substantially phase separation of high-boiling point impurities, and then introduced into an impurity separation tank and separated into a heavy impurity liquid and a light purified liquid, This method is characterized in that the heavy impurity liquid is introduced between the raw material mixture supply section and the solvent supply section of the multistage countercurrent catalytic extraction device.

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 q& and mixtures thereof, inorganic or organic solvents or mixed solvents thereof whose critical temperature is below the boiling point of alcohol can be used. The main solvents are shown in the table below. .

Solvent critical temperature Co, 3 t I C3tH,9,7 C2 speed 32.4 C3 horse 92.3 (HsH,,96,8 04 formula. 152.0 As a dissolving solvent, the closer the critical temperature is to room temperature, the more Also, 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; can be added in an amount 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, relative to the critical temperature Tr='r/'ro (however, 0.90<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.

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, which is a raw material, 2 is a supply line for a dissolving solvent, and 3 is a countercurrent contactor (
This is preferably a packed column, plate column or multi-stage extraction column. ) 4 is a shelf, 5 is a heavy liquid (water/high boiling point component) take-out line at the bottom of the counter-current contact device 3, 6 is a light liquid (alcohol component) take-out line at the top of the counter-current contact device 3,
7 is a pressure reducing valve, 8 is an impurity separation tank, 9 is a heavy impurity extraction line, 10 is a light purified liquid extraction line, 11 is a supply line for heavy impurities to the countercurrent contact device 3, and 12 is a heavy impurity discharge line. It's a line.

1 part by weight of the raw material mixture is supplied through the upper supply line 1 and 2 to 6 parts by weight of the dissolving solvent is supplied through the lower supply line 2 to the countercurrent contacting device 3, and the dissolving solvent is heated in a supercritical or pseudocritical state. By contacting with the flow, the light dissolved solvent phase rises and selectively extracts alcohols from the raw material mixture phase, and is taken out as a light liquid through the takeout line 6.

The amount of the dissolving solvent added can be reduced if the dissolving solvent has a high affinity with alcohols.

The countercurrent contact device 3 is preferably a packed column, a tray column, a multistage extraction device, or the like. By bringing the raw material mixture and the dissolving solvent into multistage countercurrent contact, the alcohol concentration in the raw material mixture becomes thinner at the bottom, but the alcohol concentration in the dissolving solvent is also zero at the bottom, so almost all of the alcohol is contained in the dissolving solvent. Extracted. Therefore, the alcohol concentration distribution becomes favorable. Co-current contact is not preferred because alcohol that is in equilibrium with the dissolving solvent alcohol remains in the extraction residue of the raw material mixture due to the concentration distribution.

On the other hand, the raw material mixture phase descends to the bottom as a heavy liquid while the alcohols are extracted, and is extracted from the extraction line 5.

The light liquid from the take-out line 6 contains, in addition to alcohol, a small amount of high-boiling point impurities and water, which are undesirable in terms of product specifications and must be separated and removed.

The dissolving power of the dissolving solvent is approximately proportional to the density of the dissolving solvent, and by lowering the pressure or increasing the temperature to lower the density of the dissolving solvent, the substance with a high boiling point will first phase separate from the dissolving solvent. The present inventors found this.

However, increasing the temperature is not preferable because it causes a decrease in thermal efficiency. It is therefore preferable to reduce the density of the dissolving solvent by reducing the pressure. However, if the pressure is lowered too much, the solubility of the dissolving solvent will decrease significantly,
Since a large amount of allols also undergo phase separation, it is necessary to grasp the amount and control the pressure. The present invention utilizes this phenomenon to improve the purity of concentrated alcohol.

That is, the light liquid is depressurized by the pressure reducing valve 7 to selectively phase-separate high-boiling point impurities, is introduced into the impurity separation tank 8, and is separated into a light purified liquid and a heavy impurity liquid. The light purified 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 taken out from the take-out line 10 and is usually further reduced in pressure to be separated into a dissolving solvent and concentrated purified alcohol, and the dissolving solvent is recycled and used.

On the other hand, a small amount of alcohol is dissolved in the heavy impurities extracted from the take-out line 9, and needs to be recovered to prevent loss of product alcohol.

In the present invention, the heavy impurities are removed from the countercurrent contactor 3.
By reintroducing the alcohol into the alcohol, loss of alcohol is prevented, and heavy impurities with a higher boiling point are separated and removed from the heavier impurities.

The installation position of the supply line 11 for the heavy impurities to the countercurrent contacting device 5 is determined depending on its composition, but is preferably between the supply line 1 for the raw material mixture and the supply line 2 for the dissolving solvent. .

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

Example 1 1 part by weight of a raw material mixture of 10 vt% ethyl alcohol, 0.1 wt% C4-C6 fusel oil, and 89.9 vt% water, 6 parts by weight of carbon dioxide as a dissolving solvent, an inner diameter of 50 squares, a long tube. From the top to the bottom of a 3m packed tower
50an, pressure 110atm, temperature 40
Countercurrent contact is carried out in a supercritical state at ℃, and a light liquid is taken out from the top of the column and a heavy liquid is taken out from the bottom of the column.
The pressure was reduced to ATM and separated into a light purified liquid and a heavy impurity liquid, and the heavy impurity liquid was returned in its entirety to a portion 1.5 m from the bottom 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%. The concentration of water and high boiling point impurities in it was 11% each. Owt%,
It was 80 ppm.

Example 2 Raw material mixture 1 of 10 wt% ethyl alcohol, C4-C3 fusel oil [L 1 vt%, and 89.9 it% water
parts by weight, 6 parts by weight of carbon dioxide as a dissolving solvent, and an inner diameter of 50 m111. 19n from the top and 1) 30σ from the bottom of a packed column with a length of 3, and the pressure is 110 atm.
, countercurrent contact was carried out in a quasi-critical state at a temperature of 20° C., a light liquid was taken out from the top of the column and a heavy liquid was taken out from the bottom of the column, and the light liquid was transferred to an impurity separation tank at a pressure of 80 atm.

The pressure was reduced to 40℃, and the liquid was separated into a light purified liquid and a heavy impurity liquid.The heavy impurity liquid was separated from the bottom of the packed column by 1.5 m.
The entire amount was returned to the section.

Then, the operation was continued until the whole became steady, and as a result, 99.2 wt% of the raw material ethyl alcohol was recovered, and the concentrations of water and high boiling point impurities in it were each 5.5 wt%. Owt%, 1
00 ppm.

Comparative Example 1 In Example 1, when the operation was carried out without returning the heavy impurity liquid to the packed column, 90% of the raw material ethyl alcohol was reduced. Owt
Only % was recovered. The concentrations of water and high boiling point impurities were 4.9 wt% and 95 ppm, respectively.

[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. Furthermore, 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 drawings]

FIG. 1 is a 70-sheet for practicing the invention. 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 upper part of the multistage countercurrent catalytic extraction apparatus, a dissolving solvent is supplied from the lower part of the multistage countercurrent catalytic extraction apparatus, and the raw material mixture and the The solvent is brought into countercurrent contact under conditions such that the solvent becomes a supercritical state or a quasi-critical state, a light liquid is taken out from the upper part of the multistage countercurrent contact extraction apparatus, a heavy liquid is taken out from the lower part, and then the After the light liquid is depressurized to the pressure necessary for substantially phase separation of high-boiling point impurities, it is introduced into an impurity separation tank and separated into a heavy impurity liquid and a light purified liquid, and the heavy impurity liquid is subjected to the multistage countercurrent contact. 1. A method for concentrating and purifying alcohol, which is introduced between a raw material mixture supplying section and a solvent supplying section of an extraction device.