WO2019054671A1 - Separation method and separation apparatus for solvent - Google Patents

Abstract

The present invention relates to a separation method and a separation apparatus for a solvent extracted by supercritical extraction, and has an effect of increasing a solvent recovery rate by minimizing the amount of a solvent to be evaporated and lost since the pressure of a solvent is reduced in steps by arranging two or more separators in serial.

Description

Solvent Separation Method and Separation Device

Mutual citation with related application

This application claims the benefit of priority based on Korean Patent Application No. 10-2017-0116740 filed on September 12, 2017, and Korean Patent Application No. 10-2018-0100355 filed on August 27, 2018, The entire contents of which are incorporated herein by reference.

Technical field

The present invention relates to a solvent separation method and a solvent separation apparatus extracted through supercritical extraction.

Supercritical fluid refers to a fluid under temperature and pressure above a critical point. It is applied to various fields such as supercritical extraction, drying, polymerization, dyeing and the like because it possesses a viscosity similar to gas, a diffusion coefficient and a density close to that of a liquid and has a unique physical property between gas and liquid. Representative liquid mixtures that can be separated by supercritical extraction are water and ethanol. It is possible to selectively extract ethanol only because the solubility of CO ₂ is higher in ethanol than in water. Such supercritical extraction can replace conventional techniques such as distillation, liquid extraction and membrane separation, which were conventionally used for ethanol separation.

On the other hand, after the extraction of ethanol, the extracted phase leaving the upper part of the extracting column becomes a ternary mixture containing CO ₂ , ethanol and a small amount of water, which flows through a pressure drop valve into a flash vessel, And it is separated into CO ₂ in liquid state and ethanol in liquid state. CO ₂ recovered in the gas phase is subjected to a heat exchange / pressurization process and then used for supercritical extraction. Ethanol present in the liquid phase in the separator is recovered at normal pressure and room temperature by opening the lower valve of the separator. At this time, the liquid ethanol present in the separator under the high-pressure condition is discharged at normal pressure, and some ethanol is vaporized to generate a loss.

Accordingly, the inventors of the present invention have studied to recover as much ethanol as possible by minimizing the amount of vaporized and lost ethanol in the step of recovering ethanol from the separator, and as a result, the present invention has been completed.

[Prior Art Literature]

(Patent Document 1) Korean Published Patent Application No. 2000-0070518 (published Nov. 25, 2000)

DISCLOSURE Technical Problem Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method and apparatus for separating and purifying a solvent, Thereby increasing the recovery rate of the solvent.

The present invention has been made to solve the above problems,

1) introducing a fluid including carbon dioxide and a solvent through the supercritical extractor into a first separator;

2) flowing the fluid having passed through the first separator to the second separator; And

3) discharging and recovering the carbon dioxide and the solvent that have passed through the second separator, respectively,

Wherein the pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

Also, the present invention provides a method of producing a carbon nanotube, comprising: a) a first separator into which carbon dioxide and a solvent-containing fluid passed through a supercritical extractor are introduced;

b) a second separator into which the fluid having passed through the first separator flows; And

c) a solvent recovery tank connected to a lower portion of the second separator to store the discharged and recovered solvent,

Wherein the pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

The solvent separation method and the separation apparatus according to the present invention have an effect of increasing the solvent recovery rate by minimizing the amount of the solvent lost by vaporization by arranging two or more separators in series to reduce the pressure of the solvent step by step.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate exemplary embodiments of the invention and, together with the description of the invention, It should not be construed as limited.

1 is a schematic view schematically showing a solvent separation method and a separation apparatus of an embodiment of the present invention.

2 is a schematic diagram schematically showing a solvent separation method and a separation apparatus of a comparative example.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention. Herein, terms and words used in the present specification and claims should not be construed to be limited to ordinary or dictionary meanings, and the inventor may appropriately define the concept of the term to describe its own invention in the best way. It should be construed as meaning and concept consistent with the technical idea of the present invention.

1) introducing carbon dioxide and a solvent-containing fluid through a supercritical extractor into a first separator;

2) flowing the fluid having passed through the first separator to the second separator; And

3) discharging and recovering the carbon dioxide and the solvent that have passed through the second separator, respectively,

The pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

Hereinafter, the present invention will be described in more detail.

The present invention is characterized in that a solvent is extracted by a supercritical extraction method using carbon dioxide, and step 1) is characterized by introducing carbon dioxide and a solvent-containing fluid, which have passed through a supercritical extractor, into a first separator.

Carbon dioxide (CO ₂ ) is in a gaseous state at normal temperature and atmospheric pressure, but when it exceeds a certain temperature and high pressure limit, called a supercritical point, it becomes a critical state in which gas and liquid can not be distinguished. It is called supercritical carbon dioxide.

The supercritical extractor maintains the temperature and pressure above the critical temperature and the critical pressure of the carbon dioxide because the critical temperature of the carbon dioxide is 31.1 ° C and the critical pressure is 73.8 bar. bar and a temperature of 31.1 캜 to 80 캜.

The solvent used in the present invention is at least one selected from the group consisting of water, ethanol, methanol, propanol, ethyl acetate, acetone, and nucleic acid. Specifically, the solvent is separated from the solvent mixture by supercritical carbon dioxide .

 More specifically, it means a solvent having a higher solubility in carbon dioxide in the solvent mixture contained in the supercritical extractor. For example, when the solvent mixture is a mixture of water and ethanol, The solvent that is dissolved in carbon dioxide and discharged to the first separator is ethanol which has high solubility.

When the temperature of the supercritical extractor is less than 31.1 ° C, supercritical carbon dioxide may not be formed well. When the temperature exceeds 80 ° C, the temperature is increased unnecessarily regardless of the increase in the extraction yield, There may be a problem.

Likewise, when the pressure of the supercritical extractor is less than 73.8 bar, supercritical carbon dioxide may not be formed well. When the pressure exceeds 300 bar, the pressure is increased unnecessarily irrespective of the increase in the extraction yield, There may be an increasing problem.

It is preferable that the supercritical extractor maintains the temperature and the pressure for 6 hours to 9 hours, preferably 5 hours to 8 hours. If the supercritical water extractor is less than 6 hours, the solvent extraction effect may be insufficient, The solvent extraction effect does not increase so much, but the process time is prolonged, and the process efficiency may deteriorate.

Generally, after the supercritical extraction of the solvent, the CO ₂ is transferred to the separator, which is separated and reused as gaseous CO ₂ and liquid solvent through decompression. The CO ₂ recovered in the gas phase is subjected to a heat exchange / pressurization process and used again for the extraction. The solvent present in the liquid phase in the separator is recovered at normal pressure and room temperature by opening the lower valve of the separator and reused.

However, at this time, since the liquid solvent existing in the separator of high pressure condition is suddenly decompressed to normal pressure, some of the solvent is vaporized to generate loss, and as the pressure suddenly decreases, the temperature suddenly decreases, In this case, a problem of clogging the line occurs.

Accordingly, the present invention is characterized in that the pressure of the solvent extracted through the supercritical extraction is reduced stepwise. More specifically, the present invention relates to a method of separating a solvent by increasing the recovery rate of a solvent by connecting two or more separators in series to minimize the amount of a solvent lost by vaporization due to a sudden pressure change by gradually changing the temperature and pressure conditions of the carbon dioxide and the solvent, And the reuse ratio is increased.

In the present invention, a first separator and a second separator are terms used to distinguish two or more separators, the first separator being a separator directly connected to the supercritical extractor, and the second separator being a separator connected to the first separator And there may be third and fourth separators in addition to the second separator.

The carbon dioxide and the solvent-containing fluid passing through the supercritical extractor of the present invention may be introduced into a first separator for separation into carbon dioxide and a solvent, wherein the pressure of the first separator is 40 bar to 100 bar and the temperature is 10 Deg.] C to 30 [deg.] C, preferably 50 to 90 bar, and the temperature is maintained at 15 [deg.] C to 25 [deg.] C.

When the pressure of the first separator is less than 40 bar or the temperature is more than 30 ° C, there is a problem that the solvent evaporates and the recovery rate decreases. When the pressure exceeds 100 bar or the temperature is less than 10 ° C, There may be a problem that CO ₂ to be dissolved in the lower solvent of the separator is excessively dissolved.

The step 2) of the present invention is characterized in that the fluid having passed through the first separator is not directly discharged and recovered at normal temperature and normal pressure but is introduced into the second separator. As described above, in the solvent separation method of the present invention, two or more separators are connected in series to perform the separation of the carbon dioxide and the solvent stepwise.

The second separator of the present invention is characterized in that the pressure is maintained at 1 to 30 bar and the temperature is maintained at 10 to 30 ° C, preferably 10 to 20 bar, and the temperature is maintained at 15 to 25 ° C.

When the pressure of the second separator is less than 1 bar or the temperature is more than 30 ° C as in the first separator, there is a problem that the solvent evaporates and the recovery rate decreases. When the pressure exceeds 30 bar or the temperature is less than 10 ° C There may be a problem that CO ₂ to be recovered to the upper portion is excessively dissolved in the lower solvent of the separator. In this case, when the solvent is recovered under atmospheric pressure, there is a fear that CO ₂ dissolved in the solvent vaporizes and the solvent is lost.

Step 3) of the present invention is characterized in that the carbon dioxide and the solvent which have passed through the supercritical extractor, the first separator and the second separator are finally recovered.

Specifically, the solvent allows the solvent discharged from the second separator to be recovered at normal temperature and atmospheric pressure through a decompression valve disposed under the second separator of the present invention.

The carbon dioxide is pressurized and cooled through a heat exchanger connected to the upper portion of the second separator, which is present as a gas in the second separator operating condition, and is recovered in a liquid state in the carbon dioxide recovery tank. The solvent is connected to the lower portion of the second separator And recovered in a liquid state in a solvent recovery tank.

The recovered carbon dioxide and the solvent can be reused in a supercritical extractor, respectively, by recycling.

In the meantime, the present invention is characterized in that the supercritical extraction solvent is stepwise depressurized to minimize the amount of solvent lost by vaporization to increase the recovery rate of the solvent. The solvent recovery rate is 95% or more, specifically 96% or more , More specifically 96.5% or more, and even more specifically 97% or more.

The solvent recovery percentage (%) can be calculated as (the total amount of the solvent recovered in the liquid state in the recovery tank / the total amount of the supercritically extracted solvent) x 100%.

The present invention also provides a solvent separation apparatus based on the solvent separation method.

Specifically, the solvent separation apparatus of the present invention comprises:

a) a first separator into which a fluid including carbon dioxide and a solvent having passed through the supercritical extractor flows;

b) a second separator into which the fluid having passed through the first separator flows; And

c) a solvent recovery tank connected to a lower portion of the second separator to store the discharged and recovered solvent,

The pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

The solvent separating apparatus of the present invention may further include a carbon dioxide recovery tank connected to the upper portion of the second separator to store carbon dioxide discharged and recovered.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  One

In order to extract and separate ethanol from a mixture of water and ethanol through supercritical carbon dioxide, a supercritical fluid containing carbon dioxide and ethanol, passed through a supercritical extractor operating at 150 bar and 70 ° C, Into a first separator to be operated and into a second separator operated at 10 bar and 20 ° C, the carbon dioxide is pressurized and cooled through a compressor and heat exchanger connected to the top of the second separator, And ethanol was recovered in a liquid state at normal temperature and atmospheric pressure through a pressure reducing valve existing under the second separator.

Example  2

Ethanol was recovered in the same manner as in Example 1, except that the first separator was operated at 50 bar and 30 ° C in the first embodiment, and the second separator was operated at 30 bar and 30 ° C.

Example  3

Ethanol was recovered in the same manner as in Example 1, except that the first separator was operated at 70 bar and 15 ° C in the first embodiment, and the second separator was operated at 30 bar and 20 ° C.

Comparative Example  One

Ethanol was recovered in the same manner as in Example 1, except that only the first separator operated at 50 bar and 20 ° C was discharged and recovered at 50 bar and 20 ° C at room temperature and normal pressure.

Comparative Example  2

Ethanol was recovered in the same manner as in Example 1 except that the first separator was operated at 120 bar and 20 캜.

Comparative Example  3

Ethanol was recovered in the same manner as in Example 1, except that the first separator was operated at 120 bar and the second separator was operated at 50 bar and 20 ° C in Example 1.

Experimental Example : Measurement of ethanol recovery

In order to calculate the recovery rate of ethanol recovered in the above Examples and Comparative Examples, the flow rate of carbon dioxide, water and ethanol extracted from the supercritical water extractor and introduced into the first separator, and the flow rate of carbon dioxide, water and liquid ethanol recovered in the recovery tank The results of the measurement and the solvent recovery are shown in Table 1 below.

		The first separator	Recovery tank	Solvent recovery rate
Example 1	CO 2 (kg / hr)	40.9	0.031	97.2%
	H 2 O (kg / hr)	0.4	0.389
	EtOH (kg / hr)	2.88	2.8
Example 2	CO 2 (kg / hr)	40.9	0.037	96.1%
	H 2 O (kg / hr)	0.4	0.385
	EtOH (kg / hr)	2.88	2.77
Example 3	CO 2 (kg / hr)	40.9	0.06	96.5%
	H 2 O (kg / hr)	0.4	0.388
	EtOH (kg / hr)	2.88	2.77
Comparative Example 1	CO 2 (kg / hr)	40.9	0.021	90.2%
	H 2 O (kg / hr)	0.4	0.359
	EtOH (kg / hr)	2.88	2.6
Comparative Example 2	CO 2 (kg / hr)	40.9	0.02	92.0%
	H 2 O (kg / hr)	0.4	0.37
	EtOH (kg / hr)	2.88	2.65
Comparative Example 3	CO 2 (kg / hr)	40.9	0.02	89.9%
	H 2 O (kg / hr)	0.4	0.36
	EtOH (kg / hr)	2.88	2.59

* Solvent recovery (%) = (total amount of solvent recovered in liquid form in the recovery tank / total amount of supercritical solvent extracted) x 100%

As shown in Table 1, it can be seen that the embodiment of the present invention improves the solvent recovery rate by stepwise reducing the pressure of the ethanol by arranging the first separator and the second separator in series. In Comparative Example 1, The pressure was suddenly reduced from high pressure to normal pressure at a time, and it was confirmed that the solvent recovery rate was poor compared with the examples.

In Comparative Example 2, as a result of the pressure range of the first separator being out of the pressure range of the first separator of the present invention, it was confirmed that the solvent recovery rate was poorer than that of the Example due to the abrupt pressure difference between the first separator and the second separator And Comparative Example 3 shows a case where the pressure range of the first separator and the second separator is out of the pressure range of the first separator and the second separator of the present invention and the pressure difference between the first separator and the second separator and between the second separator and the recovery tank It was confirmed that the recovery rate of the solvent was inferior to that of the Example due to the sudden pressure difference.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

Claims (12)

1) introducing a fluid including carbon dioxide and a solvent through the supercritical extractor into a first separator;

2) flowing the fluid having passed through the first separator to the second separator; And

3) discharging and recovering the carbon dioxide and the solvent that have passed through the second separator, respectively,

Wherein the pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

The method according to claim 1,

Wherein the temperature of the first separator and the second separator is maintained at 10 占 폚 to 30 占 폚.

The method according to claim 1,

Wherein the solvent of step 3) is discharged and recovered under normal pressure and normal temperature conditions.

The method according to claim 1,

Wherein the supercritical extractor is maintained at a pressure of 73.8 bar to 300 bar and a temperature of 31.1 < 0 > C to 80 < 0 > C.

The method according to claim 1,

Characterized in that the carbon dioxide is pressurized and liquefied through a compressor and a heat exchanger connected to the upper part of the second separator and recovered in a liquid state in a carbon dioxide recovery tank and the solvent is recovered in a liquid recovery tank connected to the lower part of the second separator Solvent separation method.

The method according to claim 1,

Wherein the recovered carbon dioxide is recycled to the supercritical extractor.

The method according to claim 1,

Wherein the solvent is at least one selected from the group consisting of water, ethanol, methanol, propanol, ethyl acetate, acetone, and nucleic acid.

The method according to claim 1,

Wherein the recovery rate of the solvent is 95% or more.

a) a first separator into which a fluid including carbon dioxide and a solvent having passed through the supercritical extractor flows;

b) a second separator into which the fluid having passed through the first separator flows; And

c) a solvent recovery tank connected to a lower portion of the second separator to store the discharged and recovered solvent,

Wherein the pressure of the first separator is between 40 bar and 100 bar and the pressure of the second separator is between 1 bar and 30 bar.

10. The method of claim 9,

Wherein the temperature of the first separator and the second separator is maintained at 10 占 폚 to 30 占 폚.

10. The method of claim 9,

Wherein the solvent separator further comprises a carbon dioxide recovery tank connected to an upper portion of the second separator to store carbon dioxide discharged and recovered.

10. The method of claim 9,

Wherein the recovery rate of the solvent is 95% or more.

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