JP7143999B2 - Acid gas separation device and acid gas separation method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act Taiwan-Japan International Conference on Magnetic Fluids 2017 (TJ-ICMF2017), December 15, 2017 Japan-Taiwan Joint Magnetics Taiwan-Japan International Conference on Magnetic Fluids 2017 (TJ-ICMF2017) Handbook, December 14, 2017

The present invention relates to an apparatus for separating acid gases from gas mixtures and a method for separating acid gases from gas mixtures.

Technologies for separating and recovering acid gases, especially carbon dioxide, are necessary for the production of hydrogen and methane from natural gas, and for the maintenance of closed living environments such as outer space and underwater. From the viewpoint of emission reduction, extensive research has been conducted on large emission sources such as thermal power plants and steelworks. In addition, the removal of acid gases other than carbon dioxide, such as nitrogen oxides, sulfur oxides, hydrogen sulfide, inorganic acids and organic acids, is also an industrially and socially important technology. Physical absorption methods, chemical absorption methods, membrane separation methods, adsorption methods, and the like are known as acid gas separation techniques.

Among them, the chemical absorption method is an acidic gas separation technology using an absorbent that chemically reacts with acidic gas. For example, a gas containing acid gas is brought into contact with the absorption liquid at around room temperature to chemically absorb the acid gas into the absorption liquid, thereby separating the gas in which the acid gas concentration has been reduced from the absorption liquid that has absorbed the acid gas. Then, by raising the temperature of the separated absorbent, the acidic gas is diffused from the absorbent and recovered. In addition, the absorbent that has diffused the acid gas is regenerated and used again for separating and recovering the acid gas.

As this chemical absorption method, a method of using an aqueous solution containing an amine compound or an alkali metal salt as a chemical absorption liquid for carbon dioxide has been proposed. For example, Patent Document 1 describes a method for separating carbon dioxide using a monoethanolamine aqueous solution as an absorption liquid.

JP-A-5-184865

However, the carbon dioxide separation method described in Patent Document 1 has a problem that the carbon dioxide absorption rate is low and carbon dioxide cannot be efficiently separated. This problem is particularly noticeable when the concentration of carbon dioxide is low. In addition, as a facility for separating carbon dioxide, an absorption tower with a height of several tens of meters is required, which imposes a large capital investment burden.

The present invention was invented in view of the above problems, and one of the objects thereof is to provide an acidic gas separation apparatus capable of separating an acidic gas from a mixed gas with high efficiency. In addition to this purpose, it is also possible to achieve actions and effects that are derived from each configuration shown in the "Mode for Carrying out the Invention" described later and that cannot be obtained with conventional techniques. It can be positioned as another purpose.

This case provides the following specific aspects.
[1] a gas supply unit for supplying a mixed gas containing an acid gas;
an electrostatic spraying unit that electrostatically sprays an ionic liquid toward the mixed gas and absorbs the acidic gas into the ionic liquid;
The electrostatic spraying part is
a liquid supply unit that supplies the ionic liquid;
a liquid jetting section for jetting the ionic liquid supplied from the liquid feeder into the mixed gas;
a counter electrode arranged to face the liquid ejection part;
a voltage applying unit that applies a voltage between the liquid ejecting unit and the counter electrode;
an ionic liquid regeneration unit that separates the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying by the electrostatic spraying unit;
a liquid sending unit for sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration unit to the liquid supply unit ;
The acidic gas separation device , wherein the liquid ejecting part ejects the ionic liquid, which has been miniaturized to a nano-size to form minute droplets, into the mixed gas .

[2] The ionic liquid regeneration unit separates the acidic gas from the ionic liquid by performing at least one of heating and depressurization of the ionic liquid that has absorbed the acidic gas. acid gas separator.

[3] The acidic gas separation device according to [1] or [2], which has a plurality of the liquid jetting sections connected in parallel to the voltage applying section.

[4] a gas supply unit for supplying a mixed gas containing an acid gas;
an electrostatic spraying unit that electrostatically sprays an ionic liquid toward the mixed gas and absorbs the acidic gas into the ionic liquid;
The electrostatic spraying part is
a liquid supply unit that supplies the ionic liquid;
a first liquid jetting section for jetting the ionic liquid supplied from the liquid feeder into the mixed gas;
a second liquid ejection section arranged opposite to the first liquid ejection section for ejecting the ionic liquid supplied from the liquid supply section into the mixed gas;
a voltage applying section that applies a voltage between the first liquid ejecting section and the second liquid ejecting section;
an ionic liquid regeneration unit that separates the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying by the electrostatic spraying unit;
a liquid sending unit for sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration unit to the liquid supply unit ;
The acidic gas separation device, wherein the first liquid jetting section and the second liquid jetting section each jet the ionic liquid that has been miniaturized to a nano-size to form minute droplets into the mixed gas .

[5] According to [4], the ionic liquid regeneration unit separates the acidic gas from the ionic liquid by performing at least one of heating and depressurization of the ionic liquid that has absorbed the acidic gas. acid gas separator.
[ 6 ] a plurality of the first liquid ejecting portions connected in parallel to the voltage applying portion;
The acidic gas separation device according to [4] or [5] , further comprising a plurality of the second liquid jetting sections connected in parallel to the voltage applying section.

[ 7 ] The liquid supply unit has a first liquid supply unit that supplies a first ionic liquid among the ionic liquids, and a second liquid supply unit that supplies a second ionic liquid among the ionic liquids,
the first liquid ejection section ejecting the first ionic liquid supplied from the first liquid supply section into the mixed gas;
The second liquid ejection unit ejects the second ionic liquid supplied from the second liquid supply unit into the mixed gas,
The acidic gas separation device according to [4].

[ 8 ] a plurality of the first liquid ejecting portions connected in parallel to the voltage applying portion;
The acidic gas separation device according to [ 7 ] , further comprising a plurality of said second liquid ejecting parts connected in parallel to said voltage applying part.

[ 9 ] The ionic liquid regeneration unit separates the acidic gas and the first ionic liquid from the first ionic liquid that has absorbed the acidic gas, and separates the acidic gas from the second ionic liquid that has absorbed the acidic gas. separating the acidic gas and the second ionic liquid, and recovering the first ionic liquid and the second ionic liquid without mixing the first ionic liquid and the second ionic liquid ; The acidic gas separation device according to [ 7 ] or [ 8 ].

[ 10 ] a first liquid sending unit that sends the first ionic liquid recovered in the ionic liquid regeneration unit to the electrostatic spraying unit;
The acidic gas separation device according to [ 9 ], further comprising a second liquid sending section that sends the second ionic liquid recovered in the ionic liquid regeneration section to the electrostatic spray section.

[ 11 ] the acidic gas is carbon dioxide,
The acidic gas separation device according to any one of [1] to [ 10 ], wherein the concentration of carbon dioxide contained in the mixed gas is 3% by volume or less.

[12] A gas supply step of supplying a mixed gas containing an acid gas into a space in which the end portion of the liquid ejection portion from which the liquid is ejected faces the counter electrode;
an electrostatic spraying step of applying a voltage between the liquid ejecting part and the counter electrode to electrostatically spray the ionic liquid from the end toward the mixed gas, thereby absorbing the acidic gas into the ionic liquid;
an ionic liquid regeneration step of separating the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying in the electrostatic spraying step;
a liquid sending step of sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration step to the electrostatic spraying step ;
In the electrostatic spraying step, the ionic liquid, which has been pulverized to nano-size and formed into microdroplets, is electrostatically sprayed from the end of the liquid ejection section toward the mixed gas . Acidic gas separation method. .

[ 13 ] According to [12] , in the ionic liquid regeneration step, the ionic liquid that has absorbed the acidic gas is subjected to at least one of heating and decompression to separate the acidic gas and the ionic liquid. acid gas separation method.

According to the present invention, the ionic liquid is electrostatically sprayed into a mixed gas containing an acid gas, so that the ionic liquid is made into fine droplets and the specific surface area is increased. As a result, the contact area between the ionic liquid and the acid gas increases, and the acid gas is efficiently chemically absorbed by the ionic liquid, so that the acid gas can be separated from the mixed gas with high efficiency. In addition, according to the present invention, equipment for separating acid gas such as an absorption tower can be made smaller, and equipment investment can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the acidic gas separation apparatus which concerns on this embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the process flow of the acidic gas separation method which concerns on this embodiment. It is a schematic diagram which shows the principal part of the acidic gas separation apparatus regarding the 1st modification of this embodiment. It is a schematic diagram which shows the principal part of the acidic gas separation apparatus regarding the 2nd modification of this embodiment. It is a schematic diagram which shows the principal part of the acidic gas separation apparatus regarding the 3rd modification of this embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the structure of the acidic gas separation apparatus which concerns on 1st Example. 4 is a graph showing the droplet diameter distribution with respect to the applied voltage measured in the first example. 5 is a graph showing the droplet size distribution when 5.5 kV (DC) is applied in the first example. 4 is a graph showing changes in chamber internal pressure during ionic liquid electrostatic spraying in the first example. It is a graph which shows the time-dependent change of the amount of carbon dioxide removed by the ionic liquid electrostatic spray in 1st Example. It is a graph which shows the time-dependent change of the carbon dioxide absorption rate by the ionic liquid electrostatic spray in 1st Example. It is a schematic diagram which shows the structure of the acidic gas separation apparatus which concerns on a 2nd Example. It is a graph which shows the time-dependent change of the carbon dioxide concentration by the ionic liquid electrostatic spray in 2nd Example. It is a graph which shows the carbon dioxide concentration with respect to the applied voltage at the time of an ionic liquid electrostatic spray in a 2nd Example. 4 is a graph showing changes over time in the amount of carbon dioxide removed per 1 mol of ionic liquid.

The acidic gas separation apparatus according to the present embodiment is an apparatus for separating acidic gases contained in a mixed gas by electrostatically spraying an ionic liquid toward the mixed gas containing the acidic gas.
Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

[1. Constitution]
As shown in FIG. 1, the acidic gas separation apparatus 100 includes a gas supply unit 10 that supplies a mixed gas 50 containing an acidic gas 52, and an ionic liquid 60 that is electrostatically sprayed toward the mixed gas 50 to remove the acidic gas 52. Electrostatic spraying unit 20 for absorption in ionic liquid 60, ionic liquid regeneration unit 30 for separating acidic gas 52 and ionic liquid 60 (62) from ionic liquid 60 (61) absorbing acidic gas 52, and ionic liquid regeneration A liquid sending unit 40 for sending the ionic liquid 60 ( 62 ) separated by the unit 30 to the electrostatic spraying unit 20 is provided.
In the following, first, the mixed gas 50 and the ionic liquid 60 will be described, and then the gas supply unit 10, the electrostatic spraying unit 20, the ionic liquid regeneration unit 30, and the liquid feeding unit 40 that constitute the acidic gas separation device 100 will be described. I will explain in order.

<Mixed gas>
Mixed gas 50 is a gaseous mixture containing acid gas 52 , preferably a mixture of acid gas 52 and non-acid gas 51 . Moreover, the mixed gas 50 may contain components other than gases, such as water and dust.

Examples of the acid gas 52 include carbon dioxide; hydrogen sulfide; sulfur oxides such as sulfur monoxide, sulfur dioxide (sulfur dioxide), and sulfur trioxide; nitrogen monoxide, nitrogen dioxide, and nitrous oxide (dinitrogen monoxide) Nitrogen oxides such as , dinitrogen trioxide, dinitrogen tetroxide, and dinitrogen pentoxide; inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid, and sulfuric acid; organic acids such as carboxylic acid, sulfonic acid, and carbonic acid; . Among these acidic gases 52, the acidic gas separation device 100 according to the present embodiment is particularly excellent in separating carbon dioxide.
Examples of the non-acidic gas 51 include hydrogen, methane, nitrogen, oxygen, and carbon monoxide.
The types and compositions of the acidic gas 52, the non-acidic gas 51, and other components contained in the mixed gas 50 are not particularly limited.

<Ionic liquid>
The ionic liquid 60 is a molten salt formed by combining a cation and an anion, and refers to a salt having a melting point around room temperature or lower. The ionic liquid 60 has characteristics such as extremely low vapor pressure and non-volatility, excellent thermal and chemical stability, and high ionic conductivity. The ionic liquid 60 used in the present embodiment is not particularly limited as long as it is a liquid within the operating temperature range and has the ability to absorb the acid gas 52 .

As the ionic liquid 60, a known or commercially available one can be used. For example, the ionic liquid 60 consists of anions and cations shown below.
Anions include chloride ion (Cl ⁻ ), bromide ion (Br ⁻ ), iodide ion (I ⁻ ), hexafluorophosphate (PF ₆ ⁻ ), tetrafluoroborate (BF ₄ ⁻ ), p-toluenesulfonate (p-CH ₃ —C ₆ H ₄ SO ₃ ⁻ ), trifluoromethanesulfonate (CF ₃ SO ₃ ⁻ ), bis(trifluoromethanesulfonyl)imide [(CF ₃ SO ₂ ) ₂ N ⁻ ], dicyanamide [(NC ) ₂ N ⁻ ], tris(trifluoromethylsulfonyl)methide [(CF ₃ SO ₂ ) ₃ C ⁻ ], acetate ion (CH ₃ COO ⁻ ), trifluoroacetate ion (CF ₃ COO ⁻ ) and the like. is selected.

Examples of cations include nitrogen-containing cyclic cation compounds such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, imidazolium, and derivatives thereof; amine-based cations of tetraalkylammonium and derivatives thereof; phosphonium, trialkylsulfonium, tetraalkylphosphonium, etc. phosphine-based cations and derivatives thereof; lithium cations and derivatives thereof;

Furthermore, it is desirable that the ionic liquid 60 has a substituent that chemically reacts with carbon dioxide on either or both of the anion and the cation.
Examples of anions that chemically react with carbon dioxide include carboxylate anions such as acetate anion (CH ₃ COO ⁻ ), amino acid anions such as glycine anion (NH ₂ CH ₂ COO ⁻ ), alkoxides such as methoxide (CH ₃ O—), and the like. mentioned.
Examples of cations that chemically react with carbon dioxide include the above cations having primary, secondary and tertiary amino groups.

<Gas supply section>
The gas supply unit 10 supplies the mixed gas 50 to the internal space of the acidic gas separation device 100 . The gas supply unit 10 has a gas supply channel 10a. The gas supply flow path 10a includes a mass flow controller (MFC) as a flow rate controller (flow rate control unit), a vent (VENT) for discharging the mixed gas 50, a valve for adjusting the flow direction of the mixed gas 50, a compressor, and the like. A precooler or the like can be provided. In this embodiment, the gas supply channel 10a is connected to a chamber 100a forming part of the acidic gas separation device 100, and the mixed gas 50 is guided into the internal space of the acid gas separation device 100 by the gas supply channel 10a. be.

The gas supply unit 10 is configured as a container filled in advance with a mixed gas 50 in which an acid gas 52 and a non-acid gas 51 are mixed. A container filled with the acid gas 52 and a container filled with the non-acid gas 51 constitute the gas supply unit 10, and the gases 51 and 52 introduced from the respective containers are supplied to the internal space of the acid gas separation device 100. can also be mixed with

<Electrostatic spraying part>
The electrostatic spraying unit 20 electrostatically sprays the ionic liquid 60 toward the mixed gas 50 . That is, in the electrostatic spraying unit 20, the charged and finely divided ionic liquid 60 (hereinafter sometimes referred to as “microdroplets”) is directed toward the mixed gas 50 filled in the internal space of the acidic gas separation device 100. It is sprayed out and absorbs the acid gas 52 . Therefore, in the electrostatic spraying unit 20, the acidic gas 52 is separated from the mixed gas 50, and the ionic liquid 60 (hereinafter referred to as "rich absorbing liquid 61") that has absorbed the acidic gas 52 and the acidic gas 52 are removed or reduced. A processed gas (hereinafter sometimes referred to as “processing gas”) 53 is obtained.

Here, the processing gas 53 from which the acid gas 52 has been removed refers to a gas that does not substantially contain the acid gas 52. Specifically, the concentration of the acid gas 52 contained in the processing gas 53 is It is preferably 1% by volume or less, more preferably 0.1% by volume or less. When the mixed gas 50 is composed of the acid gas 52 and the non-acid gas 51 , the processed gas 53 from which the acid gas 52 has been removed is substantially the same as the non-acid gas 51 .
In addition, the processing gas 53 in which the acid gas 52 is reduced means that the concentration of the acid gas 52 is reduced below the concentration of the acid gas 52 contained in the mixed gas 50 guided from the gas supply unit 10 to the electrostatic spray unit 20. say gas.

A method for separating the processing gas 53 and the rich absorbent 61 is not particularly limited. For example, a classifier and a gas-liquid separator can be used.

The particle size of the electrostatically sprayed fine droplets is not particularly limited, and is, for example, 0.15 to 5 μm. The particle size (droplet diameter) of microdroplets can be measured using a particle size measuring device such as a particle analyzer by a dynamic light scattering method.

Further, the electrostatic spraying unit 20 specifically includes a liquid supply unit 21 that supplies the ionic liquid 60, a liquid ejection unit 22 that ejects the ionic liquid 60 supplied from the liquid supply unit 21 into the mixed gas 50, A counter electrode 23 arranged to face the liquid ejecting portion 22 and a voltage applying portion 24 for applying a voltage between the liquid ejecting portion 22 and the counter electrode 23 are provided.
When a voltage is applied between the liquid ejection part 22 and the counter electrode 23 , the liquid facing the counter electrode 23 is released when the electrostatic force acting on the interface exceeds the surface tension of the ionic liquid 60 at the end of the liquid ejection part 22 . A Taylor cone T is formed by the ionic liquid 60 at the end of the ejection part 22, and an electrostatic atomization phenomenon occurs. This electrostatic atomization phenomenon is a phenomenon in which the electrostatic force generated by the electric field generates liquid threads from the tip of the Taylor cone, and the liquid threads split to spray and discharge the ionic liquid 60 in the form of fine droplets. When the Coulomb force acting between the ions in the ejected droplet becomes larger than the surface tension of the droplet, Rayleigh splitting occurs, splitting the droplet and further promoting the miniaturization. In other words, at the end of the liquid ejection part 22, the charged ionic liquid 60 becomes charged microparticles that are miniaturized to nano-size, that is, microdroplets, and is attracted by the Coulomb force from the counter electrode 23, and the acidic gas separation device It is sprayed out into the interior space of 100 . These fine droplets have a larger specific surface area than before becoming fine particles, and easily come into contact with the mixed gas 50 filled in the internal space of the acidic gas separation device 100, so that the acid contained in the mixed gas 50 The gas 52 can be efficiently chemically absorbed.

When the processing gas 53 contains the acid gas 52, that is, when the gas 53 has a reduced content of the acid gas 52, the gas 53 is introduced into the gas supply unit 10, and the acid gas is supplied again. The separation device 100 may be used to separate the acid gas 52 . In order to introduce the processing gas 53 into the gas supply unit 10 , a channel for guiding the processing gas 53 to the gas supply unit 10 may be provided.

(liquid supply unit)
The liquid supply section 21 supplies the ionic liquid 60 to the liquid ejection section 22 via the liquid supply channel 21a. The liquid supply unit 21 includes a tank that stores the ionic liquid 60 and a pump that supplies the ionic liquid 60 from the tank to the liquid ejection unit 22 . For example, the ionic liquid 60 is pushed out to the liquid ejecting part 22 by supplying air to the bath in a closed state with a pump.
Note that the liquid supply unit 21 does not necessarily have to supply the ionic liquid 60 by a pump. For example, the liquid supply unit 21 can be configured by an air pulse type dispenser. The air pulse dispenser is a device that opens and closes a solenoid valve at a certain time to introduce a gas such as nitrogen at a constant pressure reduced through a regulator into a container such as a syringe containing the ionic liquid 60 and push out the ionic liquid 60. be.

Depending on the amount of the ionic liquid 60 supplied from the liquid supply part 21 to the liquid ejection part 22 (hereinafter also referred to as "ionic liquid flow rate"), the liquid ejection part 22 is electrostatically sprayed into the internal space of the acidic gas separation device 100. The amount of ionic liquid 60 is adjusted. The flow rate of the ionic liquid is appropriately adjusted according to the inner diameter of the nozzle 22a in the liquid ejecting portion 22, which will be described later, and the distance between the nozzle 22a and the counter electrode 23, and is not particularly limited. 0 to 10.0 mL/h.

(liquid ejection part)
The liquid ejection part 22 ejects the ionic liquid 60 supplied from the liquid supply part 21 toward the mixed gas 50 introduced into the internal space of the acidic gas separation device 100 . The liquid ejection part 22 has a nozzle 22a at the end on the side from which the ionic liquid 60 is ejected.

The nozzle 22a is connected to the voltage application section 24, and the ionic liquid 60 sent from the liquid supply section 21 is charged by the nozzle 22a. The nozzle 22a is connected to the liquid supply channel 21a at the other end (the end opposite to the end on the side from which the ionic liquid 60 is ejected). Although the material of the nozzle 22a is not particularly limited, it is configured using, for example, fused silica, polymer resin, metal such as SUS, and the like.

Although the shape of the nozzle 22a is not particularly limited, a cylindrical nozzle 22a is used in this embodiment. Although the inner diameter of the nozzle 22a is not particularly limited, it is, for example, 10 to 1000 μm. Also, the outer diameter of the nozzle 22a is not particularly limited, but is, for example, 30 to 3000 μm.

(Counter electrode)
The counter electrode 23 is arranged to face the liquid ejector 22 . That is, the counter electrode 23 is arranged on an extension line of the axis of the nozzle 22a and is separated from the nozzle 22a.

The material of the counter electrode 23 is not particularly limited. From the viewpoint of forming an electric field between the liquid ejection part 22 (nozzle 22a) and spraying and discharging the ionic liquid 60 from the end of the nozzle 22a into the internal space of the acidic gas separation device 100 by the electric field, the counter electrode 23 is made of metal. Alternatively, it is preferably formed of a conductive resin or the like. Moreover, in order to efficiently spray and discharge the ionic liquid 60, it is more preferable to form the counter electrode 23 with a metal or a conductive resin having a low electric resistance. Furthermore, since the ionic liquid 60 sprayed and discharged from the nozzle 22a may adhere to the counter electrode 23, the counter electrode 23 is formed of tungsten, molybdenum, aluminum, stainless steel, nickel alloy, etc., which have excellent corrosion resistance to the ionic liquid 60. is particularly preferred.

The distance between the end of the nozzle 22a and the counter electrode 23 greatly affects the intensity of the electric field formed between them. Moreover, it is presumed that the distance between the two also affects the residence time of the microdroplets in the internal space of the acidic gas separation device 100 . For example, if the distance between the two is reduced, the voltage applied to the nozzle 22a can be reduced. On the other hand, if the distance between the two is too small, corona discharge or arc discharge to the opposing electrode 23 is likely to be induced, and residence time of the fine droplets is shortened, so the removal amount of the acid gas 52 tends to decrease. Therefore, in order to optimize these conflicting characteristics, it is necessary to appropriately adjust the materials of the nozzle 22a and the counter electrode 23 to be used, the inner and outer diameters of the nozzle 22a, and the flow rate of the ionic liquid. In this embodiment, the distance between the end of the nozzle 22a and the counter electrode 23 is preferably 1 to 10 mm. If the distance is within this range, corona discharge and arc discharge are suppressed, the removal amount of the acid gas 52 is excellent, and the voltage applied to the nozzle 22a can be reduced.

Further, the counter electrode 23 has an opening 23a so that the electric field intensity with the end of the nozzle 22a is increased and droplets are sprayed and discharged into the internal space without adhering to the counter electrode 23. FIG. From the viewpoint of preventing the bias of the electric field, it is preferable that the center of the opening 23a be arranged on the extension line of the axis of the nozzle 22a.

The shapes of the counter electrode 23 and the opening 23a are not particularly limited. In the present embodiment, a plate-shaped counter electrode 23 is used, and a circular opening 23a is formed in the counter electrode 23 . The diameter of the opening 23a is related to the inner and outer diameters of the nozzle 22a, the distance between the nozzle 22a and the counter electrode 23, and the flow rate of the ionic liquid, so it is appropriately adjusted according to these conditions. In this embodiment, the diameter of the opening 23a is preferably 5 to 30 mm.

(Voltage application part)
The voltage applying section 24 applies a voltage between the liquid ejecting section 22 and the counter electrode 23 . Typically, the voltage is direct current and can be 4-10 kV in this embodiment. It is preferable that the voltage be applied to the counter electrode 23 so that the nozzle 22a side is positive. If a voltage is applied so that the nozzle 22a side becomes positive, the counter electrode 23 will have the opposite charge. Therefore, even if the positional relationship between the nozzle 22a and the counter electrode 23 in FIG. 22 toward the counter electrode 23 into the internal space of the chamber 100a.

Further, when a voltage is continuously applied between the liquid ejecting portion 22 and the counter electrode 23, minute droplets are deposited on the counter electrode 23, which may easily induce corona discharge or arc discharge. Therefore, the opposed electrode 23 may be cleaned after a predetermined time has elapsed from the start of the electrostatic spraying to remove the deposited minute droplets. Further, the voltages applied to the liquid ejecting portion 22 and the counter electrode 23 may be reversed after a predetermined time has elapsed from the start of electrostatic spraying.

When a voltage is supplied from the voltage application unit 24, a Taylor cone T of the ionic liquid 60 is formed at the end of the nozzle 22a, and an electrostatic atomization phenomenon occurs. A known unit can be used as the voltage applying unit 24 .

<Ionic liquid regeneration unit>
The ionic liquid regeneration unit 30 removes the acidic gas 52 and part or all of the acidic gas 52 from the rich absorbent 61 and regenerates the ionic liquid 60 (hereinafter sometimes referred to as "lean absorbent 62"). separate. In this embodiment, the recovery channel 30a connected to the chamber 100a guides the rich absorbent 61 to the ionic liquid regeneration unit 30, where the acidic gas 52 and the lean absorbent 62 are separated. be done. That is, in the ionic liquid regeneration unit 30 , the acidic gas 52 is diffused from the rich absorbent 61 to recover the acidic gas 52 , and the ionic liquid 60 is regenerated as the lean absorbent 62 . The lean absorbent 62 is introduced into the liquid supply 21 and can be reused for separation of the mixed gas 50 containing the acid gas 52 .

A method for diffusing the acid gas 52 from the rich absorbing liquid 61 is not particularly limited. For example, a method of heating and/or reducing the pressure of the rich absorbing liquid 61 may be used.

When the rich absorbent 61 is heated, the acid gas 52 can be diffused by setting the temperature to be 5 to 100° C. higher than the temperature of the internal space of the chamber 100a where the acid gas 52 is absorbed. More preferably, the acid gas 52 is diffused under a temperature condition of 100° C. or less, particularly preferably 40 to 80° C., so that the regeneration energy of the ionic liquid 60 can be reduced. It saves energy compared to the conventional technology that requires conditions.

Further, when the rich absorbing liquid 61 is decompressed, the acid gas 52 can be diffused by setting the pressure to be lower than the pressure of the internal space of the chamber 100a where the acid gas 52 is absorbed. The temperature at which the rich absorbing liquid 61 is depressurized is not particularly limited, but it is preferably the temperature of the internal space of the chamber 100a, that is, near room temperature (25° C.±10° C.) or above room temperature (25° C.).

A device constituting the ionic liquid regeneration unit 30 is not particularly limited as long as the absorbed acidic gas 52 is diffused and the ionic liquid 60 is regenerated. Note that a preheater or the like can be arranged in the recovery channel 30a in order to facilitate the separation of the acid gas 52 and the lean absorbent 62 .

<Liquid sending unit>
The liquid feeding section 40 guides the lean absorption liquid 62 separated by the ionic liquid regeneration section 30 to the electrostatic spraying section 20 , specifically the liquid supply section 21 . The lean absorption liquid 62 , that is, the ionic liquid 60 introduced into the electrostatic spraying section 20 is reused for separation of the mixed gas 50 containing the acid gas 52 . Since the ionic liquid 60 is nonvolatile and chemically stable, it is suitable for reuse. By reusing the ionic liquid 60, an economically excellent separation cycle for the acid gas 52 can be formed.

In addition, a pump, a heat exchanger, a precooler, and the like may be arranged in the liquid sending section 40 . A known device can be used as the liquid sending unit 40 .

[2. process flow]
Next, a method for separating the acid gas 52 (acid gas separation method) will be described with reference to FIG. This separation method is a method of separating the acid gas 52 from the mixed gas 50 by an acid gas separation device 100A having the same configuration as the acid gas separation device 100 described above.
As shown in FIG. 2, this acidic gas separation apparatus 100A includes an absorption tower and a diffusion tower. In the separation method using the acidic gas separation device 100A, each step is carried out in the order of a gas supply step, an electrostatic spraying step, an ionic liquid regeneration step, and a liquid transfer step.

In the gas supply step, a mixed gas 50 is supplied from a gas supply section (not shown) to the absorption tower. The mixed gas 50 is guided to the gas supply channel 10a and introduced into the internal space from the sidewall at the bottom of the absorption tower. A compressor or a precooler can be arranged in the gas supply flow path 10 a according to the type of the mixed gas 50 .

In the absorption tower, an electrostatic spraying process is performed to separate the acid gases 52 contained in the mixed gas 50 . Specifically, a liquid supply unit for supplying the ionic liquid 60 and a liquid ejection unit for ejecting the ionic liquid are provided above the absorption tower, and a counter electrode is provided below the absorption tower. . Then, by applying a voltage between the liquid ejection part and the counter electrode, the ionic liquid is electrostatically sprayed toward the mixed gas 50 introduced from the lower part of the absorption tower, and the acid contained in the mixed gas 50 The gas 52 is selectively absorbed by the ionic liquid formed into microdroplets. As a result, a rich absorbent 61 is obtained as an ionic liquid that has absorbed the acid gas 52 . On the other hand, the gas from which the acid gas 52 has been removed or reduced is discharged outside from the upper part of the absorption tower as the treated gas 53 . That is, gas-liquid separation between the rich absorbent 61 and the treated gas 53 is performed in the absorption tower.

Also, the rich absorbent 61 is guided to the diffusion tower by the recovery channel 30a, and the ionic liquid regeneration step is performed. Specifically, by heating the rich absorbent 61 in the stripping tower, the acidic gas 52 contained in the rich absorbent 61 is diffused and discharged to the outside from the top of the stripping tower. Then, a lean absorbent 62 is obtained as an ionic liquid from which a part or all of the acid gas 52 has been removed and regenerated. As a heating method, in addition to a method of circulating steam or high-temperature water inside the diffusion tower, heating means such as a heater can be used.

In the liquid transfer step, the lean absorbent 62 is guided to a liquid supply section provided above the absorption tower and reused as an ionic liquid that is electrostatically sprayed toward the mixed gas 50 . That is, the ionic liquid circulates between the absorption tower and the stripping tower. A pump, a heat exchanger, a precooler, or the like can be arranged in the flow path 40a through which the lean absorbent 62 is guided.

[3. Action and effect]
Since the acidic gas separation apparatuses 100 and 100A according to the present embodiment are configured as described above, the following functions and effects can be obtained.
(1) By electrostatically spraying the ionic liquid 60, the ionic liquid 60 can be formed into fine droplets. Since such fine droplets have a large specific surface area and can increase the contact area with the acid gas 52 contained in the mixed gas 50, they are excellent in absorption speed of the acid gas 52. That is, by using the acidic gas separation device 100, the acidic gas 52 can be selectively and efficiently separated from the mixed gas 50 by a simple process.
Therefore, a small amount of the ionic liquid 60 can absorb and separate a large amount of the acid gas 52 from the mixed gas 50 . In addition, since the absorption tower, which is several tens of meters high, which is required in the conventional acid gas separation apparatus, can be made smaller, it is possible to reduce the cost of equipment investment and save space.

(2) The ionic liquid 60 that has absorbed the acidic gas 52, that is, the rich absorbent 61 can diffuse the acidic gas 52 only by heating to less than 100°C. Therefore, recovery of the acid gas 52 from the mixed gas 50 can be performed with energy saving as compared with the conventional technology.

(3) In addition, the ionic liquid 60 from which the acid gas 52 has been diffused, that is, the lean absorbent 62 can be reused for separating the acid gas 52, which is economical.

(4) Furthermore, according to the acidic gas separation apparatuses 100 and 100A according to the present embodiment, for example, even when the concentration of the acidic gas 52 contained in the mixed gas 50 is 3% by volume or less, the fine droplets The acid gas 52 can be efficiently separated from the mixed gas 50 by selectively chemically absorbing the acid gas 52 by the ionic liquid 60 thus formed. An environment in which the acid gas 52, particularly carbon dioxide, has a concentration of 3% by volume or less includes a closed living environment such as outer space. That is, the acidic gas separation apparatuses 100 and 100A according to this embodiment can be suitably used in such a living environment. Conventional absorption methods for acid gas separation are generally intended to be applied to gas mixtures 50 with carbon dioxide gas concentrations greater than 3%, and to remove carbon dioxide gas from gas mixtures 50 containing low concentrations of carbon dioxide gas. Not intended to be separated.

[4. Modification]
The above-described embodiments are merely examples, and there is no intention to exclude various modifications and application of techniques not explicitly stated in the above-described embodiments. Each configuration of the above-described embodiments can be modified in various ways without departing from the spirit thereof. Also, they can be selected or combined as needed. Below, the modification of the acidic gas separation apparatus 100 which concerns on said embodiment is demonstrated. The configuration is the same as that of the above-described embodiment except for the points described here. These configurations are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

(1) For example, as shown in FIG. 3, in the acidic gas separation device 100B, instead of the counter electrode 23 in the acidic gas separation device 100, the , the second liquid ejection part 22' is arranged. The first ionic liquid 60 supplied by the first liquid supply section 21 is ejected from the first liquid ejection section 22, and the second ion supplied by the second liquid supply section 21' is ejected from the second liquid ejection section 22'. Liquid 60' is ejected. The first ionic liquid 60 and the second ionic liquid 60' may be the same or different.
In addition, the second liquid ejecting part 22' has a nozzle 22a' at the end on the side of ejecting the second ionic liquid 60'. The other end of the second liquid ejection section 22' is connected to the second liquid supply section 21' through the liquid supply channel 21a'. Then, the voltage applying section 24 applies a voltage between the first liquid ejecting section 22 and the second liquid ejecting section 22'.

That is, the electrostatic spraying section 20B in the acidic gas separation device 100B includes a first liquid supply section 21, a second liquid supply section 21', a first liquid ejection section 22, a second liquid ejection section 22', and a voltage application section 24. have In the electrostatic spraying section 20B, the ionic liquids 60, 60' formed into fine droplets are electrostatically sprayed from the pair of liquid ejection sections 22, 22', so that the removal amount of the acid gas 52 can be increased. , the separation of the acid gas 52 contained in the mixed gas 50 can be performed more efficiently.

In the acidic gas separation device 100B, a first ionic liquid 60 (first rich absorbing liquid 61) that has absorbed the acidic gas 52 and a second ionic liquid 60' that has absorbed the acidic gas 52 (second rich absorbing liquid 61'). is guided to the ionic liquid regeneration unit 30 . In the ionic liquid regeneration section 30 , the acidic gas 52 is diffused from the first rich absorbent 61 to regenerate the first ionic liquid 60 as the first lean absorbent 62 . Also, the acid gas 52 is diffused from the second rich absorbing liquid 61' to regenerate the second ionic liquid 60' as the second lean absorbing liquid 62'.

Here, when the first ionic liquid 60 and the second ionic liquid 60' are the same, depending on the flow rate of the ionic liquid supplied from each liquid supply part 21, 21' to each liquid ejection part 22, 22' , the first lean absorbing liquid 62 and the second lean absorbing liquid 62' are guided to the first liquid supply section 21 or the second liquid supply section 21' by the liquid feeding sections 40 and 40'.
On the other hand, when the first ionic liquid 60 and the second ionic liquid 60' are different, the first rich absorbing liquid 61 and the second rich absorbing liquid 61' are normally mixed in the ionic liquid regeneration section 30 without being mixed. be guided to Then, the acid gas 52 is diffused from each of the rich absorbents 61 and 61', and the first ionic liquid 60 as the first lean absorbent 62 and the second ionic liquid 60' as the second lean absorbent 62' are regenerated/regenerated. be recovered. The first lean absorbent 62 and the second lean absorbent 62′ are not mixed in the ionic liquid regeneration section 30, and the first lean absorbent 62 is introduced into the first liquid supply section 21 by the first liquid feeding section 40. and the second lean absorbing liquid 62' is introduced into the second liquid supply section 21' by the second liquid feeding section 40'. Note that when the first rich absorbing liquid 61 and the second rich absorbing liquid 61' are guided to the ionic liquid regeneration unit 30 in a mixed state, the rich absorbing liquids 61 and 61' in the ionic liquid regeneration unit 30 The acidic gas 52 is diffused from the first lean absorbent 62 and the second lean absorbent 62' to obtain a mixed liquid. Then, this mixed liquid is guided from the ionic liquid regeneration section 30 to an ionic liquid recovery section (not shown), and in the ionic liquid recovery section, the respective lean absorbents 62 and 62' may be separated by known means such as extraction. .

Further, when the first ionic liquid 60 and the second ionic liquid 60' are the same, the first liquid supply section 21 and the second liquid supply section 21' are combined into one to simplify the device. good too.

Moreover, in the acidic gas separation device 100B, a counter electrode may be arranged between the first liquid ejection part 22 and the second liquid ejection part 22'. In this case, the same voltage is applied to the first liquid ejection part 22 and the second liquid ejection part 22', and the voltage is applied between the first liquid ejection part 22 and the counter electrode, and between the second liquid ejection part 22' and the counter electrode. An electric field is formed between This counter electrode is the same as the counter electrode detailed in the above embodiment.
The distances between the counter electrode and the respective liquid ejecting portions 22, 22' may be the same or different. The distance between the counter electrode and each liquid ejection part 22, 22' depends on the material of the nozzles 22a, 22a' to be used and the counter electrode, the inner and outer diameters of the nozzles 22a, 22a', and the liquid ejected from each liquid ejection part 22, 22'. It can be appropriately adjusted according to the ionic liquid flow rate to be used.

(2) In addition, a plurality of nozzles 22a in the acidic gas separation device 100 can be arranged and connected in parallel to the voltage applying section 24 . In this case, a plurality of counter electrodes 23 may be arranged to face each nozzle 22a, or one counter electrode 23 may be arranged to face each nozzle 22a. In FIG. 4, four nozzles 22a ₁ to 22a ₄ connected in parallel to the voltage application unit 24 and one counter electrode 23 facing these nozzles 22a ₁ to 22a ₄ are arranged for acidic gas separation. The main part of the device 100C is shown. The counter electrode 23 is formed with openings 23a ₁ to 23a ₄ on extensions of the axes of the nozzles 22a ₁ to 22a ₄ . According to the acidic gas separation device 100C, one voltage applying unit 24 can apply a voltage to a plurality of nozzles at once, so the removal amount of the acidic gas 52 can be increased. Separation of the acid gas 52 can be efficiently performed.

(3) Alternatively, a plurality of pairs of opposing nozzles 22a, 22a' may be arranged in the acidic gas separation device 100B, and the respective nozzles 22a, 22a' may be connected in parallel to the voltage application section. FIG. 5 shows four nozzles 22a 1 to 22a 4 connected in parallel to the voltage application section 24, and four nozzles 22a ₁ to 22a ₄ connected in parallel to the voltage application section 23 while facing the nozzles 22a ₁ to 22a ₄ . The main part of the acidic gas separation device 100D having four nozzles 22a ₁ ′ to 22a ₄ ′ is shown. According to the acidic gas separation device 100D, a single voltage application unit 24 can apply a voltage to a plurality of opposing nozzles at once. The separation of the acid gas 52 contained in can be performed more efficiently. Also in the acidic gas separation device 100D, as in the acidic gas separation device 100B, counter electrodes can be arranged between a plurality of opposing nozzles.

Further, the acidic gas separators 100, 100A to 100D can be used for separating the acidic gas 52 from the mixed gas 50 as well as for removing/adsorbing dust, viruses, and the like.

Examples of the present invention will be described below, but the scope of the present invention is not limited to the following examples as long as the scope of the present invention is not exceeded.

<First embodiment>
In the first example, an acidic gas separation device 100E shown in FIG. 6 was used. This device 100E includes a nozzle 22a made of fused silica (cylindrical shape, inner diameter: 100 μm, outer diameter: 375 μm), and a counter electrode 23 made of SUS arranged on the axis of the nozzle 22a (the diameter of the circular opening 23a: 10 mm). Using this device 100E, the ionic liquid 60 was electrostatically sprayed under the following conditions onto the carbon dioxide filled in advance in the internal space of the chamber 100a.

(conditions)
・ Ion liquid flow rate: 3.0 mL / h
・Distance between the end of the nozzle 22a and the counter electrode 23: 6 mm

As the ionic liquid 60, 1-ethyl-3-methylimidazolium acetate was used. The physical properties of the ionic liquid 60 are shown in Table 1 below.

The applied voltage was set to 2.5 kV, 3 kV, 3.5 kV, 4 kV, 4.5 kV, 5 kV, 5.5 kV, 6 kV, and 6.5 kV, and the droplet diameter distribution for each applied voltage was measured by the dynamic light scattering method. did. Specifically, the droplet diameter distribution was measured using a particle analyzer (WELAS2070, PALAS) placed at the discharge port 100b provided at the bottom of the chamber 100a. The results are shown in FIG.

From FIG. 7, it can be seen that the distribution of droplet diameters hardly changes when the applied voltage is 4 kV or less. That is, when the applied voltage is 4 kV or less, the ionic liquid 60 formed into fine droplets by electrostatic spraying is not obtained.
On the other hand, when the applied voltage exceeds 4 kV, a change in the droplet diameter distribution is observed. That is, when the applied voltage exceeds 4 kV, the ionic liquid 60 can be formed into fine droplets by electrostatic spraying.
Note that when the applied voltage exceeds 5.5 kV, the number of minute droplets to be measured decreases. This is because when the applied voltage is increased, the micro droplets are sprayed over a wide range in the internal space of the device 100E, so the number of micro droplets that can be measured by the particle analyzer arranged at the discharge port 100b is reduced. guessed.

That is, the acidic gas separation device 100E can stably measure minute droplets when the applied voltage is 5.5 kV or less.
Therefore, in the evaluation below, the upper limit of the applied voltage was set to 5.5 kV.
FIG. 8 shows the droplet diameter distribution when the applied voltage is 5.5 kV. From FIG. 8, it can be seen that when the applied voltage is 5.5 kV, many fine droplets with a particle diameter of about 280 nm can be obtained.

(Pressure change in chamber during electrostatic spraying)
In the acidic gas separation device 100E shown in FIG. 6, the pressure sensor (AP-44, KEYENCE ) and a thermocouple thermometer (K thermocouple, AS ONE). The results are shown in FIG.

From FIG. 9, it can be seen that when the ionic liquid 60 comes into contact with the carbon dioxide filled in the internal space of the chamber 100a, the carbon dioxide is absorbed and removed by the ionic liquid 60, and the pressure in the internal space is reduced (applied voltage 0.0 kV). In addition, when the applied voltage is increased, the ionic liquid 60 is made into fine droplets and the specific surface area is increased, so that the absorption rate of carbon dioxide is improved. The pressure in the space decreases over time (see applied voltages of 3.5 kV and 5.5 kV).

The reason why the pressure in the internal space of the chamber 100a decreases over time when the applied voltage is 3.5 kV compared to when the applied voltage is 0 kV is as follows.
When the applied voltage is 0 kV, the ionic liquid 60 becomes large-diameter droplets (particle diameter: about 2 mm) and is dropped from the nozzle 22a. On the other hand, when the applied voltage is 3.5 kV, the ionic liquid 60 linearly extends from the nozzle 22a toward the counter electrode 23 without forming fine droplets. That is, liquid threads are generated. The ionic liquid 60 linearly extending from the nozzle 22a toward the counter electrode 23 (liquid string-like ionic liquid 60) has a larger specific surface area than the large-diameter droplet-like ionic liquid 60, and comes into contact with carbon dioxide. Due to the increased area, the carbon dioxide absorption rate is increased, resulting in increased carbon dioxide removal.
Also, when the applied voltage is 5.5 kV, the ionic liquid 60 is formed into fine droplets, so that the area in contact with carbon dioxide increases compared to when the applied voltage is 3.5 kV. Therefore, the absorption rate of carbon dioxide is further improved, and as a result, the amount of carbon dioxide removed is further improved.

(Change over time in the amount of carbon dioxide removed in the chamber during electrostatic spraying)
A temporal change in the amount of carbon dioxide removed by the ionic liquid 60 was calculated from the pressure change in the internal space of the chamber 100a. The results are shown in FIG.

From FIG. 10, it can be seen that as the applied voltage increases, the number of ionic liquids 60 formed into microdroplets increases, and the absorption rate of carbon dioxide increases, thereby improving the amount of carbon dioxide removed. When the applied voltage is 5.5 kV, the amount of carbon dioxide removed is approximately three times higher than when the applied voltage is 0 kV.

(Change over time in carbon dioxide absorption rate during electrostatic spraying)
From the change over time in the amount of carbon dioxide removed by the ionic liquid 60, the change over time in the absorption rate of carbon dioxide was calculated. The results are shown in FIG.

From FIG. 11, it can be seen that the higher the applied voltage, the higher the carbon dioxide absorption rate. The reason why the absorption rate decreases over time is thought to be that the pressure in the internal space of the chamber 100a decreases as the carbon dioxide is removed, so the amount of carbon dioxide physically absorbed by the ionic liquid 60 decreases.

<Second embodiment>
In the second example, an acidic gas separation device 100F shown in FIG. 12 was used. This device 100F includes gas supply units 10A and 10B. The apparatus 100F also includes a gas supply channel 10a for guiding the mixed gas 50 from the gas supply units 10A and 10B into the internal space of the chamber 100a, and a gas supply channel 10a for discharging the processing gas 53 from the internal space of the chamber 100a. and a gas discharge channel 10b connected to 10a. A spacer is arranged in the chamber 100a for the purpose of adjusting the volume of the internal space.

The gas supply section 10A is filled with nitrogen and carbon dioxide, and the gas supply section 10B is filled with nitrogen. A mixed gas 50 containing carbon dioxide with a concentration of 0.996% by volume was supplied to the internal space of the chamber 100a by adjusting the amount of gas supplied from these gas supply units 10A and 10B. The nozzle 22a, counter electrode 23, ionic liquid 60 and electrostatic spray conditions are the same as in the first embodiment.

(Change over time in carbon dioxide concentration in chamber during electrostatic spraying)
Using this acidic gas separation device 100F, changes in carbon dioxide concentration over time were measured under an atmosphere in which the mixed gas 50 was flowing inside the device 100F.

FIG. 13 shows changes over time in the concentration of carbon dioxide at the chamber outlet when carbon dioxide having a concentration of 0.996% by volume is fed into a chamber filled with nitrogen while the ionic liquid 60 is not jetted from the nozzle 22a. Shown as Batch. In addition, FIG. 13 shows the carbon dioxide concentration at the chamber outlet when the applied voltage is 0 kV, 3.5 kV, 4.5 kV, and 5.5 kV while flowing carbon dioxide with a concentration of 0.996% by volume at a predetermined flow rate. showed a change over time. The concentration of carbon dioxide was measured using an infrared CO ₂ analyzer (IR200, Yokogawa Electric Corporation) placed in the gas discharge channel 10b.

Looking at the change over time (Batch) of the carbon dioxide concentration in the chamber in a state where the ionic liquid 60 is not jetted from the nozzle 22a, the carbon dioxide concentration becomes substantially constant after about 20 minutes from the start of the supply of the mixed gas 50. Become. That is, it can be seen that the internal space of the chamber 100a was filled with the mixed gas 50 containing carbon dioxide having a concentration of 0.996% by volume about 20 minutes after the supply of the mixed gas 50 was started.
Further, in FIG. 13, the concentration of carbon dioxide becomes substantially constant after about 20 minutes from the start of electrostatic spraying. The reason for this is that the amount (removal amount) of carbon dioxide that can be removed from the mixed gas 50, which is continuously supplied at a constant carbon dioxide concentration, by electrostatic spraying of the ionic liquid 60 using the device 100F becomes constant. be.

(Carbon dioxide concentration for applied voltage)
FIG. 14 shows the concentration of carbon dioxide with respect to the applied voltage. This concentration is the average value of the concentration of carbon dioxide after about 20 minutes have passed since the start of supply of the mixed gas, when the concentration of carbon dioxide in the internal space of the chamber 100a stabilizes.

13 and 14, the higher the applied voltage, the lower the concentration of carbon dioxide contained in the mixed gas 50. Therefore, it can be seen that the electrostatic spraying of the ionic liquid 60 improves the amount of carbon dioxide removed. .

<Discussion>
In the first example, the carbon dioxide absorption capacity in the sealed container was evaluated. The amount of carbon dioxide removed by electrostatic spraying is greater than when no voltage is applied, and the ionic liquid flow rate is 3.0 mL / h, and a voltage of 5.5 kV is applied between the nozzle and the counter electrode (distance 6 mm). In the case of applying voltage, the improvement was about 3 times. This is because the carbon dioxide absorption reaction (chemical absorption) on the surface of the ionic liquid was promoted by the micro droplets with a large specific surface area generated by electrostatic spraying of the ionic liquid. Efficacy was shown.

In the second example, a carbon dioxide/nitrogen mixture with a carbon dioxide concentration of 0.996% by volume was used to evaluate the ability to absorb carbon dioxide under flow. When the ionic liquid flow rate is 3 mL/h and no voltage is applied, the carbon dioxide concentration decreases from 0.996% by volume to 0.80% by volume. On the other hand, when a voltage of 5.5 kV was applied between the nozzle and the counter electrode (distance of 6 mm), the carbon dioxide concentration decreased from 0.996% by volume to 0.51% by volume, and the static electricity of the ionic liquid A significant carbon dioxide separation and absorption effect was obtained by spraying. This experiment demonstrated the effectiveness of ionic liquid electrostatic spraying in the chemical absorption method.

<Third embodiment>
Using 1-ethyl-3-methylimidazolium acetate shown in Table 1 as the ionic liquid 60, the acidic gas separation device 100E shown in FIG. The change over time in the amount of carbon dioxide absorbed per unit (carbon dioxide loading rate) was measured. The results are shown in FIG.
The amount of carbon dioxide removed was calculated from the pressure change in the internal space of the chamber 100a, as in the first embodiment. The conditions for electrostatic spraying were as follows, and the atmosphere in the chamber was 20° C. and 0.1 MPa.
(conditions)
・ Ionic liquid flow rate: 2.0 mL / h
・Distance between the end of the nozzle 22a and the counter electrode 23: 6 mm

At an applied voltage of 6.2 kV, the carbon dioxide loading rate 60 minutes after the start of electrostatic spraying was 0.277. Note that the dotted line in FIG. 15 is the equilibrium value (0.28) of the carbon dioxide loading rate under the same conditions obtained by a separate experiment.
That is, it can be seen that the carbon dioxide loading rate approaches the equilibrium value when the applied voltage is increased.

REFERENCE SIGNS LIST 10 gas supply unit 20 electrostatic spray unit 21 liquid supply unit 22 liquid ejection unit 23 counter electrode 24 voltage application unit 30 ionic liquid regeneration unit 40 liquid supply unit 50 mixed gas 51 non-acidic gas 52 acidic gas 53 treated gas 60 ionic liquid 61 Rich absorbing liquid 62 Lean absorbing liquid 100 Acidic gas separator

Claims (13)

a gas supply unit that supplies a mixed gas containing an acid gas;
an electrostatic spraying unit that electrostatically sprays an ionic liquid toward the mixed gas and absorbs the acidic gas into the ionic liquid;
The electrostatic spraying part is
a liquid supply unit that supplies the ionic liquid;
a liquid jetting section for jetting the ionic liquid supplied from the liquid feeder into the mixed gas;
a counter electrode arranged to face the liquid ejection part;
a voltage applying unit that applies a voltage between the liquid ejecting unit and the counter electrode;
an ionic liquid regeneration unit that separates the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying by the electrostatic spraying unit;
a liquid sending unit for sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration unit to the liquid supply unit ;
The liquid ejecting part ejects the ionic liquid that has been miniaturized to a nano-size to form minute droplets into the mixed gas .
Acid gas separator. The ionic liquid regeneration unit separates the acidic gas and the ionic liquid by performing at least one of heating and depressurization of the ionic liquid that has absorbed the acidic gas.
The acid gas separation device according to claim 1. Having a plurality of liquid ejecting units connected in parallel to the voltage applying unit,
The acidic gas separation device according to claim 1 or 2. a gas supply unit that supplies a mixed gas containing an acid gas;
an electrostatic spraying unit that electrostatically sprays an ionic liquid toward the mixed gas and absorbs the acidic gas into the ionic liquid;
The electrostatic spraying part is
a liquid supply unit that supplies the ionic liquid;
a first liquid jetting section for jetting the ionic liquid supplied from the liquid feeder into the mixed gas;
a second liquid ejection section arranged opposite to the first liquid ejection section for ejecting the ionic liquid supplied from the liquid supply section into the mixed gas;
a voltage applying section that applies a voltage between the first liquid ejecting section and the second liquid ejecting section;
an ionic liquid regeneration unit that separates the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying by the electrostatic spraying unit;
a liquid sending unit for sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration unit to the liquid supply unit ;
Each of the first liquid ejection part and the second liquid ejection part ejects the ionic liquid that has been miniaturized to nano-size and formed into minute droplets into the mixed gas ,
Acid gas separator. The ionic liquid regeneration unit separates the acidic gas and the ionic liquid by performing at least one of heating and depressurization of the ionic liquid that has absorbed the acidic gas.
The acid gas separation device according to claim 4. a plurality of the first liquid ejecting units connected in parallel to the voltage applying unit;
The acidic gas separation device according to claim 4 or 5, further comprising a plurality of said second liquid ejecting parts connected in parallel with said voltage applying part. The liquid supply unit has a first liquid supply unit that supplies a first ionic liquid among the ionic liquids, and a second liquid supply unit that supplies a second ionic liquid among the ionic liquids,
the first liquid ejection section ejecting the first ionic liquid supplied from the first liquid supply section into the mixed gas;
The second liquid ejection unit ejects the second ionic liquid supplied from the second liquid supply unit into the mixed gas,
The acid gas separation device according to claim 4. a plurality of the first liquid ejecting units connected in parallel to the voltage applying unit;
The acidic gas separation device according to claim 7, comprising a plurality of said second liquid ejecting parts connected in parallel with said voltage applying part. The ionic liquid regeneration unit separates the acidic gas and the first ionic liquid from the first ionic liquid that has absorbed the acidic gas, and separates the acidic gas from the second ionic liquid that has absorbed the acidic gas. separating the gas and the second ionic liquid, and recovering the first ionic liquid and the second ionic liquid without mixing the first ionic liquid and the second ionic liquid;
The acidic gas separation device according to claim 7 or 8. a first liquid sending unit that sends the first ionic liquid recovered by the ionic liquid regeneration unit to the electrostatic spraying unit;
a second liquid sending unit that sends the second ionic liquid recovered by the ionic liquid regeneration unit to the electrostatic spraying unit;
The acid gas separation device according to claim 9. the acid gas is carbon dioxide,
The concentration of the carbon dioxide contained in the mixed gas is 3% by volume or less,
The acid gas separation device according to any one of claims 1-10. a gas supply step of supplying a mixed gas containing an acid gas into a space in which the liquid ejection end of the liquid ejection part and the counter electrode are arranged to face each other;
an electrostatic spraying step of applying a voltage between the liquid ejecting part and the counter electrode to electrostatically spray the ionic liquid from the end toward the mixed gas, thereby absorbing the acidic gas into the ionic liquid;
an ionic liquid regeneration step of separating the acidic gas and the ionic liquid from the ionic liquid that has absorbed the acidic gas by the electrostatic spraying in the electrostatic spraying step;
a liquid sending step of sending the ionic liquid separated from the acidic gas in the ionic liquid regeneration step to the electrostatic spraying step ;
In the electrostatic spraying step, the ionic liquid that has been pulverized to a nano-size and formed into fine droplets is electrostatically sprayed from the end of the liquid ejection unit toward the mixed gas ,
Acid gas separation method. In the ionic liquid regeneration step, the ionic liquid that has absorbed the acidic gas is subjected to at least one of heating and depressurization to separate the acidic gas and the ionic liquid.
The acid gas separation method according to claim 12.

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