JP2006305544A - Method of purifying gas, apparatus therefor, and acidic gas absorbing liquid used in the purification - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save circulation energy by separating and recovering acidic gas from mixed gas with high efficiency at low cost, increasing absorbing amount of the acidic gas per unit volume of an absorbing liquid, and reducing circulation amount of the absorbing liquid. <P>SOLUTION: The absorbing liquid having ionic liquid as a main component is supplied to the top of an absorption column 13 maintained at a given temperature and a pressure, and mixed gas containing acidic gas and non-acidic gas is supplied to the lower part of the column 13 to bring the mixed gas into contact with the absorbing liquid. Thus, the acidic gas is absorbed into the absorbing liquid to recover the non-acidic gas from the absorbing column 13 by separating it from the acidic gas. The absorbing liquid having absorbed the acidic gas is supplied to the top of a regeneration column 16 maintained at the same temperature of the absorbing column 13 or higher, and at a pressure lower than that of the absorbing column. Thus, the acidic gas is released, separated from the absorbing liquid, and recovered from the regeneration column 16 to regenerate the absorbing liquid. The regenerated liquid is supplied to the top of the absorbing column 13. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to an acidic gas such as CO ₂ , H ₂ S, COS, SO ₂ , SO ₃ , NO ₂ , CS ₂ , HCN, NH ₃ , mercaptan, and H ₂ , CH ₄ , CO, O ₂ , N _2. , A gas purification method and apparatus for separating and recovering the acidic gas from a mixed gas containing a non-acidic gas such as a hydrocarbon compound having 2 to 10 carbon atoms, and an acidic gas used for the separation and recovery of the acidic gas It relates to the absorption liquid. More specifically, acid gas contained in synthesis gas, natural gas, etc. by gasification, reforming or partial oxidation of fossil fuel, and acid gas contained in exhaust gas from thermal power plant, cement plant, steel plant, chemical plant, etc. The present invention relates to a gas purification method and apparatus for separating and recovering gas and an acid gas absorbing solution used therefor. Further, the present invention relates to a purification system for hydrogen gas supplied to a hydrogen station or a fuel cell vehicle, and a method and apparatus for separating and recovering an acidic gas such as CO ₂ directly in a liquid state.

Conventionally, when refining natural gas, refinery gas, ammonia synthesis gas, etc., acidic gas such as CO ₂ is separated and recovered, and this separation and recovery method includes a method of absorbing acidic gas, a method of distilling mixed gas And a method of adsorbing an acid gas, a method of separating a mixed gas by membrane separation, and a method of combining these methods. Of these, the lectizol process and the methyldiethylamine process (hereinafter referred to as MDEA process) are industrially frequently used methods (see, for example, Non-Patent Document 1).

The lectisol process is a physical absorption process, using methanol as an absorption liquid, such as CO ₂ contained in various gases such as synthesis gas by fossil fuel gasification, reforming or partial oxidation, ammonia synthesis gas, natural gas, etc. This is a method for absorbing and separating acidic gas. The absorption temperature of the acid gas is set in the range of −10 to −75 ° C., and the absorption pressure is set in the range of 7 to 8 MPa. This lectisol process (physical absorption process) has a feature that the regenerative energy of the absorbing solution is less than that of the MDEA process (chemical absorption process).
In this lectisol process, the absorption mechanism is based on the dissolution of the gas in the absorption liquid, so that the dissolved amount of the acidic gas is proportional to the acidic gas partial pressure in the absorption tower. For this reason, the acid gas in the mixed gas is separated by the difference in the partial pressure of the acid gas in the absorption tower and the regeneration tower. Further, methanol is inexpensive and the absorption capacity for acid gas is 3 to 6 times the absorption capacity for acid gas in other physical absorption processes, so that a large amount of acid gas can be treated under high pressure by physical absorption.

On the other hand, the MDEA process is a chemical absorption process, and an aqueous 30% by weight methylamine amine solution of tertiary amine is used alone or in combination with an activator, and is contained in various gases such as exhaust gas and natural gas by fossil fuel combustion. This is a method for absorbing and separating acidic gas. In addition, the absorption temperature of acidic gas is set to the range of 30-60 degreeC, and the absorption pressure is set to the range of 2-3 MPa.
In the MDEA process, the absorption mechanism is a reversible reaction between an acidic gas and an absorbing liquid, and a compound is formed at a low temperature and high pressure (the absorption liquid absorbs the acidic gas in the absorption tower). Decomposes into gas and absorption liquid (the absorption liquid proceeds in the direction of releasing acid gas in the regeneration tower). The MDEA process is characterized in that the regeneration energy of the absorbing solution is as low as 1/7 to 1/2 that of other chemical absorption processes, and the absorption capacity of acid gas is high.
Editor: Japan Petroleum Institute, edited by Kodansha Scientific Co., Ltd., “Oil Refinery Process”, Kodansha Co., Ltd., May 1998, p. 360-361)

However, in the conventional lectizol process and MDEA process shown in the above-mentioned Non-Patent Document 1, since the absorption amount of the acidic gas per unit volume of the absorption liquid is small, the circulation amount and the circulation energy of the absorption liquid are large, and the apparatus is Since the distillation tower is increased in size and the absorption liquid is regenerated, the regeneration process is complicated, and since the regeneration is performed at a higher temperature, there is a problem in that much regeneration energy is used.
Further, in the above-described conventional non-patent document 1, in the rectizol process, in order to suppress methanol loss and increase the amount of acid gas absorbed per unit volume of the absorbing solution, the absorption temperature must be set low. In addition, since a refrigerating machine is required and the absorption liquid has a vapor pressure, the absorption loss of the absorption liquid is large, and when the acidic gas is CO ₂ , the specific gravity of methanol (absorption liquid) is the specific gravity of the liquid CO ₂ . Since there was almost no change, phase separation / separation by specific gravity could not be performed, and CO ₂ could not be separated and recovered in a liquid state.
Moreover, in the lectizol process and MDEA process shown in the above-mentioned conventional non-patent document 1, a small amount of absorption liquid remains in the separated and collected acid gas. For example, the acid gas is CO ₂ used for food addition. In some cases, high-purity CO ₂ having a purity of 99.99% by volume or more cannot be obtained, and there is a problem that further purification is required.
Furthermore, in the MDEA process shown in the above-mentioned conventional Non-Patent Document 1, since it is chemical absorption, the absorption liquid may deteriorate, and the absorption liquid is regenerated under low pressure and high temperature conditions to separate and recover the acid gas. For this reason, there is a problem that the acidic gas cannot be separated and recovered in a liquid state.

The first object of the present invention is to separate and recover acidic gas from a mixed gas with high efficiency and low cost, to increase the amount of acidic gas absorbed per unit volume of the absorbing liquid, and to further reduce the circulating amount of the absorbing liquid. Another object is to provide a gas purification method and apparatus that can save circulating energy.
The second object of the present invention is to use an absorption liquid having no vapor pressure, so that the regeneration tower can be made relatively simple, and the absorption liquid can be regenerated relatively easily and at low cost. It is an object of the present invention to provide a gas purification method and apparatus capable of regenerating an absorbing solution at a temperature lower than that of the method and reducing the regeneration energy of the absorbing solution.
The third object of the present invention is to eliminate the evaporation loss of the absorbing liquid by using the absorbing liquid having no vapor pressure, and the absorbing liquid does not remain in the separated and recovered CO ₂ gas. It is an object of the present invention to provide a gas purification method and apparatus for easily producing CO ₂ gas.
The fourth object of the present invention is that CO ₂ can be efficiently recovered in a liquid state, the process can be simplified as compared with the conventional method, and the regenerated absorbent liquid is not greatly changed in temperature and pressure during the entire process. By returning to the absorption tower while maintaining a high pressure, the circulating energy of the absorbing liquid can be reduced, and the energy for regenerating the absorbing liquid is not required, so that energy can be saved, and a gas purification method and apparatus therefor Is to provide.
A fifth object of the present invention is to eliminate the need for a refrigerator or refrigeration energy by absorbing acidic gas at a temperature of room temperature or higher, thereby reducing costs, saving energy, and reducing the size of the gas. It is to provide a purification apparatus.

An ionic liquid is an organic salt that is melted without crystallization even at room temperature. In recent years, such a liquid salt at room temperature has attracted attention. An ionic liquid is a liquid but has no vapor pressure, high heat resistance (thermally stable at 400 ° C. or higher), a wide temperature range (−100 to 300 ° C.), and low viscosity. In addition, it has a unique property such as high polarity, chemical stability and nonflammability. The present inventors have absorbed more acidic gas such as CO ₂ per unit volume of the ionic liquid under pressure than methanol, methyldiethylamine, etc., and non-acidic gases (H ₂ , CH ₄ , CO, N _2). Etc.) and the present invention was made.

In the invention according to claim 1, as shown in FIG. 1, an absorption liquid mainly composed of an ionic liquid is supplied to the upper part of the absorption tower 13 maintained at a predetermined temperature and a predetermined pressure. A mixed gas containing an acidic gas and a non-acidic gas is supplied to the lower portion of the gas, and the mixed gas is brought into contact with the absorbing liquid, thereby absorbing the acidic gas into the absorbing liquid and separating the non-acidic gas from the acidic gas. The step of recovering the acid gas from the absorption tower 13 and the upper part of the regeneration tower 16 maintained at a temperature equal to or higher than the temperature in the absorption tower 13 and lower than the pressure in the absorption tower 13 absorb the acid gas. By supplying the absorbed liquid, the acid gas is diffused to be separated from the absorbent and recovered from the regeneration tower 16, and the absorbent is regenerated, and the regenerated absorbent is supplied to the upper portion of the absorber 13. Gas purification including process It is the law.
In the gas purification method described in claim 1, an absorption liquid mainly composed of an ionic liquid is supplied to the upper part of the absorption tower 13 maintained at a predetermined temperature and a predetermined pressure. When a mixed gas containing acidic gas and non-acidic gas is supplied to the lower part, the mixed gas comes into contact with the absorbing liquid and the acidic gas is absorbed by the absorbing liquid. Gas is recovered from the absorption tower 13. When the absorbing liquid that has absorbed the acidic gas is supplied to the upper part of the regeneration tower 16 that is maintained at the same temperature as or higher than the temperature in the absorption tower 13 and that is lower than the pressure in the absorption tower 13, the regeneration tower 16 Thus, the acid gas is diffused, so that the acid gas is separated from the absorption liquid and recovered from the regeneration tower 16, and the absorption liquid is regenerated and reused. In other words, the non-acid gas and the acid gas are efficiently separated and recovered from the mixed gas by utilizing the property that the solubility in the acid gas becomes very high under high pressure and the solubility in the acid gas becomes very low under low pressure. To do.

In the invention according to claim 2, as shown in FIG. 2, an absorption liquid 42 mainly composed of an ionic liquid is supplied to the upper part of the absorption tower 13 maintained at a predetermined temperature and a predetermined pressure. The mixed gas containing an acidic gas and a non-acidic gas is supplied to the lower part of 13, and the mixed gas is brought into contact with the absorbing liquid 42, so that the absorbing liquid 42 absorbs the acidic gas and the non-acidic gas and the acidic gas are mixed. The step of separating and recovering the non-acidic gas from the absorption tower 13 and the separation regenerator 46 maintained at a predetermined pressure and lower than the temperature in the absorption tower 13 are supplied with the absorbing liquid that has absorbed the acidic gas. As a result, the acidic gas is liquefied, and the liquid acidic gas 41 is separated from the absorbent 42 by the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbent 42 and recovered from the separation regenerator 46 and the absorbent 42 is removed. Process to regenerate A method for purifying a gas and a step for supplying the absorption liquid 42 which is the reproduction at the top of the absorption tower 13.
In the gas purification method described in claim 2, an absorption liquid 42 mainly composed of an ionic liquid is supplied to the upper part of the absorption tower 13 maintained at a predetermined temperature and a predetermined pressure, respectively. When a mixed gas containing an acidic gas and a non-acidic gas is supplied to the lower part of the gas, the mixed gas comes into contact with the absorbing liquid 42 and the acidic gas is absorbed by the absorbing liquid 42, so that it is separated into a non-acidic gas and an acidic gas. Non-acidic gas is recovered from the absorption tower 13. Maintain the same pressure as the pressure in the absorption tower 13, a pressure slightly higher than the pressure in the absorption tower 13, or a pressure slightly lower than the pressure in the absorption tower 13 and a temperature lower than the temperature in the absorption tower 13. When the absorbing liquid that has absorbed the acid gas is supplied to the maintained separator / regenerator 46, the acid gas is liquefied by the separator / regenerator 46. The liquid acidic gas 41 is separated from 42 and recovered from the separation regenerator 46, and the absorbing liquid 42 is regenerated and reused. That is, the solubility with respect to the acidic gas becomes very large under pressure and in a predetermined temperature range, and the acidic gas is liquefied under pressure and in a temperature range lower than the predetermined temperature range. By utilizing the property that the liquid acidic gas 41 is separated from the absorbing liquid 42 due to the insolubility and the specific gravity difference, the acidic gas is directly liquid instead of being recovered by pressurizing and cooling to a liquid after recovering the acidic gas as a gas. Since the recovery is performed in a state, the non-acidic gas and the liquid acidic gas 41 can be efficiently separated and recovered from the mixed gas.

In the invention according to claim 3, as shown in FIG. 4, a liquid membrane 51 in which a porous membrane is impregnated with an absorption liquid mainly composed of an ionic liquid is stretched in a membrane separator 52 to form a membrane separator 52. Is divided into a first chamber 52a and a second chamber 52b, the first chamber 52a is set at a higher pressure than the second chamber 52b, and a mixed gas containing acidic gas and non-acidic gas is introduced into the first chamber 52a. Thus, while the non-acid gas remains in the first chamber 52a, the acid gas permeates the liquid film 51 and moves to the low-pressure second chamber 52b, and the non-acid gas is recovered from the first chamber 52a and the second chamber 52a. This is a gas purification method for recovering acid gas from the chamber 52b.
In the gas purification method described in claim 3, when a mixed gas containing acidic gas and non-acidic gas is introduced into the high-pressure first chamber 52 a of the membrane separator 52 in which the liquid membrane 51 is stretched, non-acidic gas is introduced. Remains in the first chamber 52a and the acidic gas permeates the liquid membrane 51 and flows into the low pressure second chamber 52b, so that the mixed gas is separated into acidic gas and non-acidic gas by the liquid membrane 51, and the membrane separator 52.

The invention according to claim 6 is the invention according to any one of claims 1 to 3, characterized in that the absorbing liquid mainly composed of an ionic liquid is neutral or alkaline.
In the gas purification method described in claim 6, since the absorbing solution is neutral or alkaline, the acidic gas is easily dissolved in the absorbing solution, and the solubility thereof is larger than that of the acidic absorbing solution.
The invention according to claim 7 is the invention according to claim 1 or 2, further comprising a step of dehumidifying the mixed gas before supplying the mixed gas to the absorption tower 13, as shown in FIG. Features.
The invention according to claim 8 is the invention according to claim 3, further comprising a step of dehumidifying the mixed gas before introducing the mixed gas into the membrane separator 52, as shown in FIG. And
In the gas purification method described in claim 7 or 8, the acid gas is obtained by removing in advance from the mixed gas moisture that decreases the solubility of the acid gas in the absorbing liquid or the permeability to the liquid film 51. The solubility in the absorbing solution or the transmittance to the liquid film 51 is increased. Further, in order to separate the acidic gas in the liquid state from the absorbing liquid that has absorbed the acidic gas, even if the temperature is lower than 0 ° C., the moisture is not frozen and the acidic gas is quickly separated from the absorbing liquid.

The invention according to claim 11 is the invention according to claim 2, further comprising an acidic gas discharged from the absorption tower 13 and cooled to a temperature lower than the temperature in the absorption tower 13, as shown in FIG. Before the absorption liquid 42 is supplied to the separation / regenerator 46, it further includes a step of centrifugal separation or stirring.
In the gas purification method according to the eleventh aspect, the acidic gas in the absorbing liquid 42 is liquefied by cooling the absorbing liquid 42 containing the acidic gas to a temperature lower than the temperature in the absorption tower 13. Since the liquid acidic gas 41 is dispersed in the absorption liquid 42, the absorption liquid 42 containing the liquid acidic gas 41 is quickly brought into the separation regenerator 46 by being centrifuged or stirred before being supplied to the separation regenerator 46. The liquid acid gas and the absorption liquid are phase-separated.
The invention according to claim 12 is the invention according to claim 2, and further, as shown in FIG. 5, the absorbing liquid 42 containing ionic liquid as a main component has magnetism, and is provided below the separation regenerator 46. A magnet 61 is provided.
In the gas purification method described in claim 12, the pressure almost the same as the pressure in the absorption tower 13, that is, the same pressure as the pressure in the absorption tower 13, a pressure slightly higher than the pressure in the absorption tower 13, Alternatively, when the absorption liquid 42 containing the liquid acidic gas 41 is supplied to the separation regenerator 46 maintained at a pressure slightly lower than the pressure in the absorption tower 13 and maintained at a temperature lower than the temperature in the absorption tower 13, Due to the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbing liquid 42 and the attractive force of the magnetic absorbing liquid 42 by the magnet 61, the absorbing liquid 42 and the liquid acidic gas 41 are quickly separated.

The invention according to claim 13 is the invention according to claim 1 or 2, and further, as shown in FIG. 6, one or two selected from the group consisting of water, alcohols, ethers and phenols The above additive 71 is added to the absorbent 42.
In the gas purification method according to the thirteenth aspect, the viscosity of the absorbing liquid 42 can be reduced by adding the additive 71 to the absorbing liquid 42. As a result, the additive-containing absorption liquid 75 is supplied to the absorption tower 13, so that the additive-containing absorption liquid 75 can absorb the acidic gas in the absorption tower 13 without substantially reducing the ability of the acidic gas to be absorbed. The contained absorbent 75 flows smoothly, and the additive-containing absorbent 75 can be handled easily.
The invention according to claim 14 is the invention according to claim 2, and further, as shown in FIG. 7, one or more additives 71 selected from the group consisting of water, alcohols and ethers. To the separation regenerator 46 and by adjusting the pressure and temperature in the separation regenerator 46 to separate the specific gravity difference into the liquid acidic gas 41 and the additive-containing absorbing liquid 75 in the separation regenerator 46; The additive-containing absorbent 75 discharged from the separator / regenerator 46 is supplied to the distillation separator 83 and the interior of the distillation separator 83 is heated to a predetermined temperature, whereby the additive in the additive-containing absorbent 75 is added. A step of distilling 71 from the absorbing liquid 42 by distillation.
In the gas purification method described in claim 14, the additive 71 is supplied to the separation regenerator 46 together with the absorbing liquid 42 containing the liquid acidic gas 41 in a state where the pressure and temperature in the separation regenerator 46 are adjusted. Then, the mutual insolubility and specific gravity difference between the liquid acid gas 41 and the absorbing liquid 42 and the additive 71 having the mutual solubility with respect to the absorbing liquid 42 and the mutual insolubility with respect to the liquid acidic gas 41. By replacing the liquid acidic gas 41 dispersed in the absorbing liquid 42 by the addition with the additive 71, the liquid acidic gas 41 and the additive-containing absorbing liquid 75 are quickly separated. Next, when the additive-containing absorption liquid 75 discharged from the separation regenerator 46 is supplied to the distillation separator 83 with the inside of the distillation separator 83 heated to a predetermined temperature, the additive in the additive-containing absorption liquid 75 is supplied. 71 is separated from the absorbent 42 by distillation. As a result, the absorption liquid 42 from which the additive 71 has been removed is supplied to the absorption tower 13, so that the absorption gas can be absorbed by the absorption tower 13 without reducing the ability of the absorption liquid 42 to absorb the acid gas.

The invention according to claim 15 is the invention according to claim 2, characterized in that a flocculant is further added to the absorbing liquid containing liquid acidic gas in the separation regenerator.
In the gas purification method described in claim 15, the liquid acidic gas (dispersed liquid) dispersed in the absorbing liquid by adding the flocculant to the absorbing liquid containing the liquid acidic gas in the separation regenerator. In the separation / regenerator, the flocculant-containing absorbing liquid and the liquid acidic gas are rapidly separated into the flocculant-containing absorbing liquid and the liquid acidic gas. Thereafter, if the flocculant-containing absorbing liquid is separated by distillation, the flocculant and the absorbing liquid are further separated.
The invention according to claim 16 is the invention according to claim 2, and further, as shown in FIG. 8, the liquid in the separation regenerator 46 in which the acidic gas is CO ₂ gas and is maintained at a pressure of 4 to 25 MPa. Water is supplied into the absorbing liquid 42 containing CO ₂ 41.
In the gas purification method according to the sixteenth aspect of the present invention, water is introduced into the absorbing liquid 42 containing the liquid CO ₂ 41 in the separation regenerator 46 while the separation regenerator 46 is kept at a high pressure of 4 to 25 MPa. When supplied, a part of the liquid CO ₂ 41 is hydrated (solidified into a snow shape or a sherbet shape), and thus is separated into the liquid CO ₂ 41, the CO ₂ hydrate, and the absorbing liquid 42 in the separation regenerator 46.

The invention according to claim 17 is, as shown in FIG. 2, a dehumidifier 11 for dehumidifying a mixed gas containing acidic gas and non-acidic gas, a compressor 12 for compressing the dehumidified mixed gas, and a lower part. The mixed gas is supplied, and the upper part is supplied with an absorbing liquid 42 mainly composed of an ionic liquid. By bringing the mixed gas into contact with the absorbing liquid 42, the absorbing gas 42 absorbs the acidic gas and the non-acidic gas becomes acidic. Absorption tower 13 that separates and recovers from gas, cooler 47 that cools absorption liquid that has absorbed acid gas, and mutual insolubility and specific gravity of liquid acid gas 41 and absorption liquid 42 that are supplied with cooled absorption liquid 42 Due to the difference, the liquid acid gas 41 is separated and recovered from the absorbing liquid 42, and the separating regenerator 46 that regenerates and reuses the absorbing liquid 42, and the absorbing liquid 42 discharged from the separating regenerator 46 remains at a high pressure in the absorption tower 13. Top of An apparatus for purifying gas and a supply circulation pump 17.
In the gas purifying apparatus according to the seventeenth aspect of the present invention, the absorption liquid 42 mainly composed of an ionic liquid is supplied to the upper part of the absorption tower 13 maintained at a predetermined temperature and a predetermined pressure, respectively. When a mixed gas containing an acidic gas and a non-acidic gas dehumidified by the dehumidifier 11 is compressed by the compressor 12 and supplied, the mixed gas comes into contact with the absorbent 42 and the acidic gas is absorbed by the absorbent 42. Therefore, the non-acid gas is separated from the acid gas and recovered from the absorption tower 13. Acid gas is absorbed in the separation regenerator 46 maintained at the same pressure as the pressure in the absorption tower 13 or slightly lower than the pressure in the absorption tower 13 or slightly higher than the pressure in the absorption tower 13. When the absorbed liquid is supplied after being cooled by the cooler 47, the acidic gas is liquefied by the separation / regenerator 46, and the liquid acidic gas from the absorbent 42 is determined by the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbent 42. 41 is separated and recovered from the separation regenerator 46. Further, the absorption liquid 42 regenerated by removing the liquid acid gas is supplied to the upper portion of the absorption tower 13 by the circulation pump 17 and reused.
The invention according to claim 18 is the invention according to claim 17, wherein the absorption tower 13, the cooler 47 and the separation / regenerator 46 are integrally provided as shown in FIG. 3. .
In the gas purification apparatus described in claim 18, since the absorption tower 13, the cooler 47, and the separation regenerator 46 are integrally provided, the apparatus can be miniaturized.

The invention according to claim 19 is the invention according to claim 17 or 18, wherein a centrifuge 48 or a stirrer is provided between the cooler 47 and the separation regenerator 46 as shown in FIG. It is characterized by that.
In the gas purifying apparatus according to the nineteenth aspect, by cooling the absorbing liquid 42 containing the acidic gas to a temperature lower than the temperature in the absorption tower 13 by the cooler 47, the acidic gas in the absorbing liquid 42 is reduced. Although the liquid acid gas 41 is liquefied, the liquid acid gas 41 is dispersed in the absorption liquid. Therefore, the liquid acid gas 41 is separated by being centrifuged or stirred by the centrifuge 48 or the stirrer before being supplied to the separation regenerator 46. The absorbing liquid 42 contained is quickly phase-separated into the liquid acidic gas 41 and the absorbing liquid 42 in the separation / regenerator 46.
The invention according to claim 20 is the invention according to any one of claims 17 to 19, and as shown in FIG. 5, the absorbing liquid 42 mainly composed of an ionic liquid has magnetism and is separated. A magnet 61 is provided below the regenerator 46.
In the gas purifying apparatus described in claim 20, the pressure is substantially the same as the pressure in the absorption tower 13, that is, the same pressure as the pressure in the absorption tower 13, a pressure slightly higher than the pressure in the absorption tower 13, Alternatively, when the absorption liquid 42 containing the liquid acidic gas 41 is supplied to the separation regenerator 46 maintained at a pressure slightly lower than the pressure in the absorption tower 13 and maintained at a temperature lower than the temperature in the absorption tower 13, Due to the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbing liquid 42 and the attractive force of the magnetic absorbing liquid 42 by the magnet 61, the absorbing liquid 42 and the liquid acidic gas 41 are quickly separated.

The invention according to claim 21 is the invention according to any one of claims 17 to 20, further comprising 1 selected from the group consisting of water, alcohols, ethers and phenols, as shown in FIG. The absorption liquid 42 which added the seed | species or the 2 or more types of additive 71 was stored, and the absorption liquid storage tank 72 for supplying this additive containing absorption liquid 75 to the absorption tower 13 was provided.
In the gas purification apparatus according to the twenty-first aspect, when the additive 71 is added to the absorbent 42 in the absorbent reservoir 72, the viscosity of the absorbent 42 can be lowered. As a result, the additive-containing absorption liquid 75 is supplied to the absorption tower 13, so that the additive-containing absorption liquid 75 can absorb the acidic gas in the absorption tower 13 without substantially reducing the ability of the acidic gas to be absorbed. The contained absorbent 75 flows smoothly, and the additive-containing absorbent 75 can be handled easily.
The invention according to claim 22 is the invention according to any one of claims 17 to 20, further comprising one or two selected from the group consisting of water, alcohols and ethers, as shown in FIG. An additive storage tank 81 in which more than one type of additive 71 is stored and connected to the upper part of the separation regenerator 46, a pressure adjusting means 82 provided in the separation regenerator 46 for adjusting the pressure in the separation regenerator 46, and a separation A distillation separator 83 that stores the additive-containing absorbing liquid 75 that is connected to the lower part of the regenerator 46 and is separated in specific gravity by the separation regenerator 46 and moves to its lower phase, and the distillation separator 83 provided in the distillation separator 83. It further comprises heating means 84 for heating the inside to a predetermined temperature.
In the gas purifying apparatus according to the twenty-second aspect of the present invention, the additive together with the absorbing liquid 42 containing the liquid acidic gas 41 in a state where the temperature and pressure in the separation regenerator 46 are adjusted by the cooler 47 and the pressure adjusting means 82. When 71 is supplied to the separation regenerator 46, the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbent 42, the mutual solubility with respect to the absorbent 42, and the mutual insolubility with respect to the liquid acidic gas 41 are obtained. By replacing the liquid acid gas 41 dispersed in the absorbing liquid 42 by the addition of the additive 71 having solubility with the additive 71, the liquid acid gas 41 in the upper phase of the separation regenerator 46 is transferred, and the separation regenerator The additive-containing absorbing liquid 75 moves to the lower phase of 46, and the liquid acidic gas 41 and the additive-containing absorbing liquid 75 are quickly separated. Next, when the additive-containing absorption liquid 75 discharged from the lower part of the separation regenerator 46 is supplied to the distillation separator 83 in a state where the inside of the distillation separator 83 is heated to a predetermined temperature by the heating means 84, the additive-containing absorption is obtained. The additive 71 in the liquid 75 is distilled and separated from the absorbing liquid 42. As a result, the absorption liquid 42 from which the additive 71 has been removed is supplied to the absorption tower 13, so that the absorption gas can be absorbed by the absorption tower 13 without reducing the ability of the absorption liquid 42 to absorb the acid gas.

The invention according to claim 23 is the invention according to any one of claims 17 to 20, wherein a flocculant tank for storing the flocculant is further connected to the separation regenerator.
In the gas purification apparatus according to claim 23, the flocculant stored in the flocculant tank is dispersed in the absorbent by adding it to the absorbent containing the liquid acidic gas in the separation regenerator. Since liquid acidic gas (dispersed liquid) can be agglomerated, it is quickly separated into a flocculant-containing absorbing liquid and liquid acidic gas due to the difference in specific gravity between the flocculant-containing absorbing liquid and liquid acidic gas in the separation regenerator. . Thereafter, if the flocculant-containing absorbing liquid is separated by distillation, the flocculant and the absorbing liquid are further separated.
The invention according to claim 24 is the invention according to any one of claims 17 to 20, wherein the acidic gas is CO ₂ gas and the pressure in the separation regenerator 46 is 4 as shown in FIG. A pressure adjusting means 82 for maintaining at ˜25 MPa is provided in the separation regenerator 46, and a water storage tank 91 in which water is stored is connected to the lower part of the separation regenerator 46.
In the gas purifying apparatus according to the twenty-fourth aspect, the water in the separation / regenerator 46 is separated from the water storage tank 91 in a state where the pressure in the separation / regenerator 46 is maintained at a high pressure of 4 to 25 MPa by the pressure adjusting means 82. When fed into the absorbing solution 42 containing CO ₂ 41, since a part of the liquid CO ₂ 41 is hydrate of (solidified Yukijo or sherbet), liquid CO ₂ 41 and CO ₂ Hyde in the separator regenerator 46 Separated into rate and absorbent 42.

The invention according to claim 26 reforms one or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas and natural gas, as shown in FIG. After the CO conversion and CO removal to form a mixed gas of H ₂ and CO ₂ , this mixed gas is used by the gas purification method described in any one of claims 1 to 16 or in claims 17 to 24. Using the gas purifier described in any one of the above, the gas is separated and collected into H ₂ and CO _2, and the separated and collected H ₂ is supplied to the hydrogen station and the separated and collected CO ₂ is adiabatically expanded. This is a system for producing dry ice.
In the system described in claim 26, CO ₂ can be efficiently recovered while producing high-pressure H ₂ from various fuels.

As shown in FIG. 10, the invention according to claim 27 is mounted on an on-vehicle reforming type vehicle having a fuel cell as a drive source, and includes desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas. Claims 2, 4 and 4, wherein one or more fuels selected from the group consisting of: reforming, CO conversion and CO removal on a vehicle to form a mixed gas of H ₂ and CO ₂ ; Separation into H ₂ and liquid CO ₂ using the gas purification method according to any one of 5, 6, 7, 10 to 16, or the gas purification device according to any one of claims 17 to 24. This is a system for recovering and supplying the separated and recovered H ₂ to the fuel cell, and temporarily storing the liquid CO ₂ in the vehicle and then dropping it together.
In the system described in claim 27, the size can be reduced to such an extent that it can be mounted on a vehicle, and liquid CO ₂ can be efficiently recovered while producing high-pressure H ₂ from various fuels. That is, a CO ₂ zero emission vehicle can be realized by collecting CO ₂ in liquid form and temporarily storing it on the vehicle.

As described above, according to the present invention, an absorption liquid mainly composed of an ionic liquid is supplied to an upper part of an absorption tower maintained at a predetermined temperature and a predetermined pressure, and an acidic liquid is supplied to the lower part of the absorption tower. Supply a mixed gas containing a gas and a non-acidic gas, bring the mixed gas into contact with the absorption liquid to absorb the acidic gas into the absorption liquid, and maintain the temperature within the absorption tower at the same or higher temperature. Since the absorption liquid that has absorbed the acid gas is supplied to the upper part of the regeneration tower maintained at a pressure lower than the pressure of the non-acid gas, the non-acid gas can be separated from the acid gas by the absorption tower and recovered from the absorption tower. The gas can be diffused and separated from the absorption liquid and recovered from the regeneration tower. The absorption liquid can be regenerated, and the regenerated absorption liquid can be reused by supplying it to the upper part of the absorption tower. That is, by utilizing the characteristics that the solubility in acidic gas becomes very high under high pressure and the solubility in acidic gas becomes very low under low pressure, non-acidic gas and acidic gas can be efficiently and lowly reduced from the mixed gas. In addition to being able to be separated and recovered at a cost, the absorption amount of the acidic gas per unit volume of the absorption liquid can be increased, the circulation amount of the absorption liquid can be reduced, and the circulation energy can be saved. In addition, by using an absorption liquid with no vapor pressure, the regeneration tower can be made relatively simple, and the absorption liquid can be regenerated relatively easily and at a low cost. The regeneration energy of the absorbing liquid can be reduced. In addition, by using an absorption liquid with no vapor pressure, the evaporation loss of the absorption liquid can be eliminated, and the absorption liquid does not remain in the separated and collected acidic gas, and a high-purity acidic gas can be easily produced. If the gas is CO _2, it can be used as it is as a food additive gas.

  Also, an absorption liquid mainly composed of an ionic liquid is supplied to the upper part of the absorption tower maintained at a predetermined temperature and a predetermined pressure, and a mixed gas containing acidic gas and non-acidic gas is supplied to the lower part of the absorption tower. Then, the mixed gas is brought into contact with the absorbing liquid so that the acidic gas is absorbed into the absorbing liquid, and the absorption gas that has absorbed the acidic gas is absorbed in the separation regenerator that is maintained at a predetermined pressure and lower than the temperature in the absorption tower. If the liquid is supplied, the non-acid gas can be separated from the acid gas by the absorption tower and recovered from the absorption tower. Can be recovered from the separator / regenerator, and the absorption liquid can be regenerated. By supplying the regenerated absorption liquid to the upper part of the absorption tower with high pressure, the absorption liquid can be reused. That is, the solubility in acidic gas becomes very large under pressure and in a predetermined temperature range, and the acidic gas is liquefied under pressure and in a temperature range lower than the predetermined temperature range. By utilizing the property that liquid acidic gas is separated from the absorbing liquid due to the difference in properties and specific gravity, the acidic gas is recovered directly in the liquid state rather than being pressurized and cooled to liquid after recovering the acidic gas as a gas. Therefore, the non-acid gas and the liquid acid gas can be efficiently separated and recovered from the mixed gas at a low cost. In addition, the process can be simplified compared to the prior art, there is no large fluctuation in temperature and pressure during the entire process, and the regeneration energy of the absorbent and the recompression energy when returning the regenerated absorbent to the absorption tower are unnecessary. Energy saving can be achieved.

Further, a liquid membrane impregnated with an absorbent containing an ionic liquid as a main component in a porous membrane is stretched in the membrane separator to partition the membrane separator into a first chamber and a second chamber, If the mixed gas containing acidic gas and non-acidic gas is introduced into the first chamber by setting the pressure higher than that of the second chamber, the acidic gas permeates the liquid film while the non-acidic gas remains in the first chamber. Since it flows into the low-pressure second chamber, the mixed gas can be separated into acidic gas and non-acidic gas and recovered from the membrane separator.
Moreover, if the absorption liquid which has an ionic liquid as a main component is neutral or alkaline, acidic gas will become easy to melt | dissolve in an absorption liquid, and the solubility will also become larger than an acidic absorption liquid.
If the mixed gas is dehumidified before the mixed gas is supplied to the absorption tower, the solubility of the acidic gas in the absorbing liquid can be increased, and the mixed gas is dehumidified before being introduced into the membrane separator. If so, the permeability of the acid gas to the liquid film can be increased.
In addition, if the absorption liquid containing acidic gas discharged from the absorption tower and cooled to a temperature lower than the temperature in the absorption tower is centrifuged or stirred before being supplied to the separation / regenerator, it is dispersed in the absorption liquid. Since the liquid acid gas that is present is substantially separated into the liquid acid gas and the absorption liquid before being supplied to the separation regenerator, the liquid acid gas and the absorption liquid can be quickly separated into phases in the separation regenerator. As a result, the phase separation time between the liquid acidic gas and the absorbing liquid can be shortened, and the liquid acidic gas can be efficiently recovered.

Moreover, if the absorption liquid mainly composed of an ionic liquid has magnetism and a magnet is provided at the lower part of the separation / regenerator, the pressure in the absorption tower can be maintained at substantially the same pressure and lower than the temperature in the absorption tower. When an absorption liquid containing a liquid acidic gas is supplied to a separation regenerator maintained at a temperature, absorption occurs due to the mutual insolubility and specific gravity difference between the liquid acidic gas and the absorption liquid, and the suction force of the magnetic absorption liquid by a magnet. Quick separation into liquid and liquid acid gas. As a result, the liquid acidic gas can be quickly recovered from the separation regenerator, and the absorbing liquid can be quickly regenerated and reused.
Moreover, if the 1 type (s) or 2 or more types of additive chosen from the group which consists of water, alcohol, ethers, and phenols is added to an absorption liquid, the viscosity of an absorption liquid can be reduced. As a result, since the additive-containing absorption liquid is supplied to the absorption tower, the additive-containing absorption liquid can absorb the acid gas in the absorption tower without substantially reducing the ability to absorb the acid gas, and the additive-containing absorption liquid Flows smoothly and the handling of the additive-containing absorbent is facilitated.

In addition to supplying the above additives to the separation regenerator and adjusting the pressure and temperature in the separation regenerator, if the specific gravity difference separation between the liquid acid gas and the additive-containing absorbing liquid is performed in the separation regenerator, the absorption is achieved. By replacing the liquid acid gas dispersed in the absorbing liquid with an additive that is mutually soluble in the liquid and mutually insoluble in the liquid acid gas, The liquid acidic gas is transferred to the phase and the additive-containing absorbent is transferred to the lower phase of the separation regenerator, so that the liquid acidic gas and the additive-containing absorbent are rapidly separated. Then, with the inside of the distillation separator heated to a predetermined temperature, the additive-containing absorbent discharged from the separator / regenerator is supplied to the distillation separator to remove the additive in the additive-containing absorbent from the absorbent. If it separates by distillation, it can collect | recover in the state which isolate | separated the additive and the absorption liquid. As a result, the absorption liquid from which the additive has been removed is supplied to the absorption tower, and the additive from which the absorption liquid has been removed is supplied to the additive storage tank, so that the absorption liquid and the additive can be reused immediately, The absorbing gas can be absorbed by the absorption tower without reducing the ability of the absorbing solution to absorb the acid gas at all.
Moreover, if a flocculant is added to the absorption liquid containing the liquid acidic gas in the separation / regenerator, the liquid acidic gas (dispersed liquid) dispersed in the absorption liquid can be aggregated. As a result, the specific gravity difference separation between the liquid acidic gas and the flocculant-containing absorbing liquid can proceed promptly in the separation / regenerator, and then the flocculant-containing absorbing liquid can be separated by distillation. Can be further separated.
The acidic gas is CO ₂ gas, if supply water to the absorption solution containing liquid CO ₂ in the separator regenerator maintained at a pressure of 4～25MPa, part of the liquid CO ₂ is hydrate of (snow Therefore, the liquid is separated into liquid CO ₂ , CO ₂ hydrate, and absorbent in the separation / regenerator. As a result, the liquid CO ₂ , CO ₂ hydrate, and absorption liquid can be separated and recovered by operations of solid-liquid separation and specific gravity difference separation. Therefore, liquid CO ₂ can be separated from the absorbing liquid more quickly.

The mixed gas is dehumidified with a dehumidifier and compressed with a compressor and supplied to the lower part of the absorption tower, and an absorption liquid mainly composed of an ionic liquid is supplied from the upper part of the absorption tower and mixed with the absorption liquid. When the gas is brought into contact with the acid gas, the absorption liquid absorbs the acid gas, and the absorption liquid that has absorbed the acid gas is cooled by a cooler and supplied to the separation / regenerator. Then, the non-acid gas is separated from the acid gas by the absorption tower. It can be recovered from the absorption tower, separated from the absorption liquid in a state where the acid gas is liquefied by the separation / regenerator and recovered from the separation / regenerator, and the absorption liquid can be regenerated and reused. If absorbed, the refrigerator can be dispensed with.
If the absorption tower, the cooler, and the separation / regenerator are integrally provided, the apparatus can be reduced in size.
In addition, if a centrifuge or a stirrer is provided between the cooler and the separation regenerator, the absorption liquid containing the acidic gas is cooled to a temperature lower than the temperature in the absorption tower by the cooler. Since the acidic gas of the liquid is liquefied and dispersed in the absorbing liquid, the absorbing liquid containing the liquid acidic gas is centrifuged or stirred by a centrifuge or a stirrer, so that the liquid acidic gas is supplied before being supplied to the separation regenerator. It is almost separated into gas and absorbing liquid. As a result, phase separation between the liquid acidic gas and the absorbing liquid can be quickly performed in the separation / regenerator, so that the phase separation time between the liquid acidic gas and the absorbing liquid can be shortened and the liquid acidic gas can be efficiently recovered.

Moreover, if the absorption liquid mainly composed of an ionic liquid has magnetism and a magnet is provided at the lower part of the separation / regenerator, the pressure in the absorption tower can be maintained at substantially the same pressure and lower than the temperature in the absorption tower. When an absorption liquid containing a liquid acidic gas is supplied to a separation regenerator maintained at a temperature, absorption occurs due to the mutual insolubility and specific gravity difference between the liquid acidic gas and the absorption liquid, and the suction force of the magnetic absorption liquid by a magnet. Quick separation into liquid and liquid acid gas. As a result, the liquid acid gas can be quickly recovered from the separation regenerator, and the regenerated absorption liquid removed from the liquid acid gas is supplied to the upper part of the absorption tower by the circulation pump and can be quickly reused.
Absorption for storing one or two or more additives selected from the group consisting of water, alcohols, ethers and phenols is stored, and the additive-containing absorption liquid is supplied to the absorption tower. If a liquid tank is provided, the viscosity of the absorbent can be reduced by adding an additive to the absorbent in the absorbent tank. As a result, it is possible to absorb the acid gas in the absorption tower with almost no decrease in the ability of the additive-containing absorbing liquid to absorb the acid gas, and the additive-containing absorbing liquid flows smoothly and the additive-containing absorbing liquid is easy to handle. become.

  Further, the additive storage tank in which the additive is stored is connected to the upper part of the separation regenerator, and a pressure adjusting means for adjusting the pressure in the separation regenerator is provided in the separation regenerator, and the specific gravity difference is separated by the separation regenerator. If the distillation separator storing the liquid transferred to the lower phase is connected to the lower part of the separation regenerator and the heating means for heating the inside of the distillation separator to a predetermined temperature is provided in the distillation separator, the condenser and the pressure adjustment When the additive is supplied to the separation regenerator together with the absorbing liquid containing the liquid acidic gas with the temperature and pressure in the separation regenerator adjusted by the means, the mutual insolubility and the specific gravity difference between the liquid acidic gas and the absorbing liquid, Separation and regenerator by replacing the liquid acid gas dispersed in the absorption liquid with an additive by adding an additive that is mutually soluble in the absorption liquid and mutually insoluble in the liquid acid gas Liquid acid gas migrates into the upper phase And migration additive-containing absorbing solution in the lower phase of the regenerator, a liquid acid gas and additive-containing absorption liquid is quickly separated. Then, when the additive-containing absorption liquid discharged from the lower part of the separation regenerator is supplied to the distillation separator with the inside of the distillation separator heated to a predetermined temperature by the heating means, the additive in the additive-containing absorption liquid is Distilled from the absorbent. As a result, since the additive and the absorption liquid can be recovered in a separated state, the absorption liquid from which the additive has been removed is supplied to the absorption tower, and the additive from which the absorption liquid has been removed is supplied to the additive storage tank Thus, the absorption liquid and the additive can be reused immediately, and the absorption gas can be absorbed in the absorption tower without reducing the ability of the absorption liquid to absorb the acid gas at all.

If the flocculant tank storing the flocculant is connected to the separation regenerator, the flocculant stored in the flocculant tank is added to the absorption liquid containing the liquid acidic gas in the separation regenerator, thereby Dispersed liquid acidic gas (dispersed liquid) can be aggregated. As a result, the specific gravity difference separation between the liquid acidic gas and the flocculant-containing absorbing liquid can proceed promptly in the separation / regenerator, and then the flocculant-containing absorbing liquid can be separated by distillation. Can be further separated.
If the acidic gas is CO ₂ gas, pressure adjusting means for maintaining the pressure in the separation regenerator at 4 to 25 MPa is provided in the separation regenerator, and the water storage tank in which water is stored is connected to the lower part of the separation regenerator. When water is supplied from the water storage tank into the absorption liquid containing liquid CO ₂ in the separation regenerator while the pressure in the separation regenerator is maintained at a high pressure of 4 to 25 MPa by the pressure adjusting means, part of the liquid CO ₂ Hydrates (solidifies into snow or sherbet). As a result, the liquid CO ₂ , CO ₂ hydrate, and absorption liquid can be separated and recovered by operations of solid-liquid separation and specific gravity difference separation. Therefore, liquid CO ₂ can be separated from the absorbing liquid more quickly.

The fuel is reformed, CO transformed and removed to form a mixed gas of H ₂ and CO ₂ , and then this mixed gas is separated and recovered into H ₂ and CO ₂ using the above gas purification method or gas purification device. If the separated and collected H ₂ is supplied to the hydrogen station and the separated and collected CO ₂ is adiabatically expanded to produce dry ice, high-pressure H ₂ is produced from various fuels, while CO ₂ is produced. ₂ can be recovered efficiently.
Further, the system is mounted on an on-vehicle reforming type vehicle using a fuel cell as a driving source, and after reforming the fuel on the vehicle, CO conversion and CO removal to form a mixed gas of H ₂ and CO ₂ , The mixed gas is separated and recovered into H ₂ and liquid CO ₂ by using the above gas purification method or gas purification apparatus, and the separated and recovered H ₂ is supplied to the fuel cell, and the liquid CO ₂ is temporarily recovered. If they are stored in the vehicle and then lowered together, they can be made small enough to be mounted on the vehicle, and CO ₂ can be efficiently recovered while producing high-pressure H ₂ from various fuels. That is, a CO ₂ zero emission vehicle can be realized by collecting CO ₂ in liquid form and temporarily storing it on the vehicle.

Next, the best mode for carrying out the present invention will be described with reference to the drawings.
<First Embodiment>
As shown in FIG. 1, the refining device includes a dehumidifier 11 that dehumidifies a mixed gas containing acidic gas and non-acidic gas, a compressor 12 that compresses the dehumidified mixed gas, and a vertically extending lower part. An absorption tower that is supplied with a gas mixture compressed into the upper part and is supplied with an absorption liquid at the top so that the mixed gas is brought into contact with the absorption liquid to absorb the acidic gas into the absorption liquid and separate and recover the non-acidic gas from the acidic gas. 13, an expansion turbine 14 that expands and depressurizes the absorbing liquid that has absorbed the acid gas, and the expanded and depressurized absorbing liquid is supplied to dissipate the acidic gas from the absorbing liquid to separate and recover from the absorbing liquid and absorb A regeneration tower 16 for regenerating the liquid and a circulation pump 17 for supplying the regenerated absorption liquid to the upper part of the absorption tower 13 are provided.

The mixed gas is a fuel gas such as a synthetic gas obtained by gasification, reforming or partial oxidation of fossil fuel, natural gas, or exhaust gas discharged from a thermal power plant, a cement plant, a steel plant, a chemical plant, or the like. The acid gas is one or more gases selected from the group consisting of CO ₂ , H ₂ S, COS, SO ₂ , SO ₃ , NO ₂ , CS ₂ , HCN, NH ₃ and mercaptan, and is non-acidic gas is _{H 2, CH 4, CO,} O 2, N 2 and one or more gases selected from the group consisting of hydrocarbon compounds to 10 carbon atoms. Here, examples of the hydrocarbon compound having 2 to 10 carbon atoms include C ₂ H ₄ , C ₂ H ₆ , C ₃ H ₆ , C ₃ H ₈ , C ₄ H ₈ , and C ₄ H ₁₀ . The absorbing liquid is a composition containing an ionic liquid as a main component, and the ionic liquid has a cation and an anion. The cations are [R, R′-N ₂ C ₃ H ₃ ] ⁺ (N, N′-dialkylimidazolium), [NR _X H _4-X ] ⁺ (alkylammonium), [R-NC ₅ H ₅ ]. One selected from the group consisting of ⁺ (N-alkylpyridinium), [R-NC ₄ H ₈ ] ⁺ (N-alkylpyrrolidinium) and [PR _X H _4-X ] ⁺ (alkylphosphonium) Or two or more cations (R and R ′ in the cation are alkyl groups having 1 to 18 carbon atoms or hydrogen, and X in the cation is 1 to 3), preferably [R, R ′ —N ₂ C ₃ H ₃ ] ⁺ (N, N′-alkylimidazolium having 1 to 10 alkyl groups) or [R—NC ₅ H ₅ ] ⁺ (N-alkylpyridinium) or both is there. The anion is one or more anions selected from the group consisting of PF ₆ ⁻ , BF ₄ ⁻ , NO ₃ ⁻ , EtSO ₄ ⁻ , AlCl ₄ ⁻ and AlBr ₄ ⁻ , preferably PF ₆ ^−. or BF ₄ ^- is either or both of the.

  The gas supply pipe 18 that connects the compressor 12 and the absorption tower 13 in communication is provided with a precooler 19, and the mixed gas is maintained at a predetermined temperature and a predetermined pressure by the compressor 12 and the precooler 19. In this state, it is supplied to the lower part of the absorption tower 13. Specifically, the temperature of the mixed gas supplied to the absorption tower 13, that is, the temperature in the absorption tower 13 is set to 0 to 100 ° C., preferably 30 to 50 ° C., and the mixed gas supplied to the absorption tower 13 The pressure, that is, the pressure in the absorption tower 13 is set to 1 to 25 MPa, preferably 4 to 10 MPa. Here, the temperature in the absorption tower 13 is limited to the range of 0 to 100 ° C. The reason is that a refrigerator is required if the temperature is less than 0 ° C., and if the temperature exceeds 100 ° C., the energy required for temperature increase increases and the acid gas This is because the amount absorbed by the absorbing liquid is reduced. Further, the pressure in the absorption tower 13 is limited to the range of 1 to 25 MPa. If the pressure is less than 1 MPa, the absorption amount of the acidic gas by the absorption liquid decreases, and if it exceeds 25 MPa, the absorption tower 13 having high pressure resistance is required. This is because the cost increases. Although the absorption tower 13 may be an absorption drum, it is desirable to use a multistage absorption tower 13 in order to improve the absorption efficiency of acid gas, and the regeneration tower 16 may be a regeneration drum, but it improves the regeneration efficiency of the absorbing liquid. Therefore, it is desirable to use a multistage regeneration tower 16.

The first communication pipe 21 that connects the lower end of the absorption tower 13 and the expansion turbine 14 is provided with a pressure reducing valve 23, a flash drum 24, and a heat exchanger 26 in order from the absorption tower 13 side. The absorbing liquid containing acidic gas discharged from the lower end of the absorption tower 13 by the pressure reducing valve 23 and the flash drum 24 is depressurized by a predetermined pressure, for example, 0.1 to 0.5 MPa from the pressure in the absorption tower 13. This is because only non-acidic gases such as H ₂ , CH ₄ , CO, O ₂ , and N ₂ contained in the absorption liquid are diffused and returned to the absorption tower 13. The upper end of the flash drum 24 and the lower part of the absorption tower 13 are connected in communication by a first return pipe 31, and an auxiliary compressor 27 is provided in the first return pipe 31. The heat exchanger 26 is configured such that the high-temperature absorption liquid discharged from the lower end of the regeneration tower 16 gives heat to the low-temperature absorption liquid containing the acid gas discharged from the lower end of the flash drum 24. That is, the heat exchanger 26 is configured to heat the absorption liquid containing the acid gas discharged from the lower end of the flash drum 24 and to cool the high-temperature absorption liquid discharged from the lower end of the regeneration tower 16. .

  The second communication pipe 22 that connects the expansion turbine 14 and the regeneration tower 16 to each other is provided with a heater 28. By the expansion turbine 14 and the heater 28, the absorption liquid containing the acid gas has the same temperature as the absorption tower 13. Alternatively, it is supplied to the upper part of the regeneration tower 16 while being maintained at a temperature higher than the temperature in the absorption tower 13 and maintained at a pressure lower than the pressure in the absorption tower 13. Specifically, the temperature of the absorption liquid supplied to the regeneration tower 16, that is, the temperature in the regeneration tower 16 is set to 30 to 200 ° C., preferably 30 to 100 ° C. The pressure, that is, the pressure in the regeneration tower 16 is set to 0.1 to 5 MPa, preferably 0.1 to 3 MPa. Here, the reason why the temperature in the regeneration tower 16 is limited to the range of 30 to 200 ° C. is that if it is less than 30 ° C., it is disadvantageous for acid gas diffusion, and if it exceeds 200 ° C., the temperature rise energy increases. The reason why the pressure in the regeneration tower 16 is limited to the range of 0.1 to 5 MPa is that if it is less than 0.1 MPa, the pressure in the regeneration tower 16 becomes negative and the apparatus becomes complicated, and the cost increases. This is because it is disadvantageous for acid gas emission.

  The lower end of the regeneration tower 16 is connected to the upper part of the absorption tower 13 by a second return pipe 32, and the circulation pump 17 is provided in the second return pipe 32. An after cooler 29 is provided in the second return pipe 32 that connects the discharge port of the circulation pump 17 and the upper part of the absorption tower 13 so that the temperature of the absorbing liquid becomes a predetermined temperature. Adjusted. The absorbing solution is preferably neutral or alkaline. This is because if the absorbing liquid is acidic, the amount of acidic gas absorbed per unit volume, that is, the solubility of the acidic gas is reduced. In order to make the absorbent liquid alkaline, an alkaline ionic liquid is used, or an alkali is added to the absorbent liquid.

A method for purifying a gas using the purification apparatus configured as described above will be described.
Before supplying the mixed gas to the absorption tower 13, the circulation pump 17 and the auxiliary compressor 27 are operated in advance, and a coolant such as water, air, or ammonia is supplied to the precooler 19 and the aftercooler 29. The heater is energized to circulate the absorption liquid, and the temperature of the absorption liquid supplied to the absorption tower 13 and the regeneration tower 16 is set to a predetermined temperature. First, the mixed gas is dehumidified by the dehumidifier 11. As a result, moisture that decreases the solubility of the acidic gas in the absorbing liquid can be removed in advance from the mixed gas, and the solubility of the acidic gas in the absorbing liquid can be increased. The dehumidified mixed gas is heated or cooled to a predetermined temperature by the compressor 12 and the precooler 19 and is supplied to the lower portion of the absorption tower 13 in a state where the pressure is increased to a predetermined pressure. As a result, the mixed gas comes into contact with the absorbing liquid and the acidic gas is absorbed by the absorbing liquid, so that the non-acidic gas is separated from the acidic gas and recovered from the upper end of the absorption tower 13. When the pressure of the recovered non-acid gas is higher than the pressure required on the user side, for example, when the non-acid gas (mixed gas of H ₂ , CH ₄ , CO, O ₂ , N _2, etc.) is used for a gas turbine. At present, since the pressure is about 3 MPa, the non-acidic gas is once decompressed using an expansion turbine or an adiabatic expansion valve. At this time, since the temperature of the non-acidic gas after decompression is lowered, this low-temperature non-acidic gas can be used as a refrigerant for the precooler 19 or the aftercooler 29. In addition, when an expansion turbine is used for decompression of the non-acidic gas, power can be generated by the expansion turbine, so that the electric power can be used for consumption in the place where the purification apparatus of this embodiment is installed.

On the other hand, the absorbing liquid containing a large amount of acidic gas and a small amount of non-acidic gas discharged from the lower end of the absorption tower 13 is decompressed by a predetermined pressure by the pressure reducing valve 23 and the flash drum 24. As a result, only non-acidic gases such as H ₂ , CH ₄ , CO, O ₂ , and N ₂ contained in the absorbing liquid are diffused and separated from the absorbing liquid containing acidic gas. The dissipated non-acid gas is discharged from the upper end of the flash drum 24, further pressurized by the auxiliary compressor 27, and returned to the absorption tower 13 again. The absorbing liquid containing acid gas discharged from the lower end of the flash drum 24 is heated by the regenerated absorbing liquid in the heat exchanger 26, then expanded and depressurized by the expansion turbine 14, and further heated to a predetermined temperature by the heater 28. And supplied to the upper part of the regeneration tower 16. That is, the absorption liquid heated by the heat exchanger 26 is maintained at a temperature equal to or higher than the temperature in the absorption tower 13 by the expansion turbine 14 and the heater 28 and higher than the pressure in the absorption tower 13. It is supplied to the upper part of the regeneration tower 16 while maintaining a low pressure. When the absorption liquid is set to such a pressure and temperature, the acid gas contained in the absorption liquid is dissipated in the second communication pipe 22 or the regeneration tower 16, so that the acid gas is separated from the absorption liquid and the regeneration tower 16 Recovered from the top. On the other hand, the regenerated absorption liquid that does not contain the acid gas discharged from the lower end of the regeneration tower 16 is conveyed by the circulation pump 17 and cooled to a predetermined temperature by the heat exchanger 26 and the after cooler 29, and then absorbed. It is supplied to the upper part of the tower 13 and reused. When the acidic gas is CO ₂ gas, the recovered CO ₂ gas is pressurized to liquid CO ₂ , and then a part or all of the liquid CO ₂ is adiabatically expanded by opening the pressure reducing valve. Dry ice (solid CO ₂ ) that can be sold as a product can be manufactured.

<Second Embodiment>
FIG. 2 shows a second embodiment. 2, the same reference numerals as those in FIG. 1 denote the same components.
In this embodiment, a separation regenerator 46 is provided instead of the regeneration tower of the first embodiment, and a cooler 47 is provided instead of the expansion turbine and the heater of the first embodiment. The second return pipe 32 is not provided with the aftercooler of the first embodiment. The mixed gas is heated or cooled to a predetermined temperature by the compressor 12 and the precooler 19 and is supplied to the lower portion of the absorption tower 13 in a state where the pressure is increased to a predetermined pressure. Specifically, the temperature of the mixed gas supplied to the absorption tower 13, that is, the temperature in the absorption tower 13 is set to 0 to 100 ° C., preferably 30 to 50 ° C., and the mixed gas supplied to the absorption tower 13 The pressure, that is, the pressure in the absorption tower 13 is set to 4 to 25 MPa, preferably 6 to 10 MPa. Here, the temperature in the absorption tower 13 is limited to the range of 0 to 100 ° C. The reason is that if the temperature is lower than 0 ° C., a refrigerator is required. This is because the amount absorbed by the absorbent 42 is reduced. Further, the pressure in the absorption tower 13 is limited to the range of 4 to 25 MPa. If the pressure is less than 4 MPa, the absorption amount of the acidic gas by the absorbing liquid 42 is small. This is because the cost increases.

On the other hand, the cooler 47 supplies the absorption liquid 42 containing the acidic gas to the separation / regenerator 46 in a state where it is kept substantially the same as the pressure in the absorption tower 13 and cooled to a temperature lower than the temperature in the absorption tower 13. Specifically, the pressure of the absorbing liquid 42 supplied to the separation regenerator 46, that is, the pressure in the separation regenerator 46 is the same pressure as the pressure in the absorption tower 13, and a pressure slightly higher than the pressure in the absorption tower 13. Alternatively, the pressure is set to 4 to 25 MPa, preferably 6 to 10 MPa, which is slightly lower than the pressure in the absorption tower 13, and the temperature of the absorbing liquid 42 supplied to the separation regenerator 46, that is, the temperature in the separation regenerator 46 is It is set to −30 to 30 ° C., preferably 0 to 20 ° C., lower than the temperature in the absorption tower 13. Here, the pressure in the separation regenerator 46 is the same pressure as the pressure in the absorption tower 13, a pressure slightly higher than the pressure in the absorption tower 13, or a pressure slightly lower than the pressure in the absorption tower 13. The reason for limiting to this range is to liquefy the acidic gas and to reduce the consumption of circulating energy of the absorbing liquid 42. The reason why the temperature in the separation regenerator 46 is limited to the range of −30 to 30 ° C. is that the cooling energy increases when the temperature is lower than −30 ° C., and the acidic gas such as CO ₂ becomes difficult to be liquefied when the temperature exceeds 30 ° C. It is. In addition, when making the pressure in the separation regenerator 46 higher than the pressure in the absorption tower 13, the pressure difference is preferably within a range of 0.1 to 3 MPa where the acidic gas can be liquefied by the temperature decrease. When making the pressure in the vessel 46 lower than the pressure in the absorption tower 13, the pressure difference is preferably within a range of 0.1 to 3 MPa which can liquefy the acidic gas due to the temperature decrease.

By adjusting the pressure and temperature in the separation / regenerator 46 in this way, the liquid acid gas 41 is absorbed from the absorbent 42 by the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the absorbent 42 in the separation / regenerator 46. To be separated. Specifically, when the liquid acidic gas is liquid CO ₂ and the pressure in the separation regenerator 46 is 8 MPa, the liquid CO ₂ becomes insoluble in the absorbent and the specific gravity of the absorbent is 1.2. Since the specific gravity of liquid CO ₂ is 0.8, the absorption liquid sinks due to the mutual insolubility and specific gravity difference between the liquid CO ₂ and the absorption liquid, and the liquid CO ₂ floats and is separated. In addition, the heat exchanger 26 is configured such that the cooler absorbing liquid 42 discharged from the lower end of the separation regenerator 46 takes heat away from the lower temperature absorbing liquid containing the acidic gas discharged from the lower end of the flash drum 24. The That is, the heat exchanger 26 further cools the absorbing liquid 42 containing the acidic gas discharged from the lower end of the flash drum 24 and heats the lower-temperature absorbing liquid 42 discharged from the lower end of the separation / regenerator 46. Configured as follows. Further, a centrifuge 48 is provided in the second communication pipe 22 between the cooler 47 and the separation regenerator 46. Note that a stirrer may be provided instead of the centrifuge. The configuration other than the above is the same as that of the first embodiment.

A method for purifying a gas using the purification apparatus configured as described above will be described.
Since the operation in the absorption tower 13 is substantially the same as that of the first embodiment, repeated description is omitted. The absorption liquid containing the acid gas discharged from the lower end of the flash drum 24 is cooled by the regenerated absorption liquid in the heat exchanger 26 and further cooled by the cooler 47. At this time, the acidic gas in the absorption liquid is liquefied and dispersed in the absorption liquid 42. The absorbing liquid 42 containing the liquid acidic gas 41 is substantially separated into the liquid acidic gas 41 and the absorbing liquid 42 by the centrifugal separator 48 due to the specific gravity difference between the liquid acidic gas 41 and the absorbing liquid 42, and then supplied to the separation regenerator 46. Is done. Normally, the liquid acid gas 41 has a smaller specific gravity than the absorbing liquid 42, so that the liquid acid gas 41 moves away from the rotation center of the centrifuge 48, and the absorbing liquid 42 approaches the rotation center of the centrifuge 48. Move in the direction. That is, the absorption liquid 42 is kept almost the same as the pressure in the absorption tower 13 by the heat exchanger 26 and the cooler 47 and is made lower than the temperature in the absorption tower 13, whereby the gas in the absorption liquid 42 is liquefied. Further, it is supplied to the separation regenerator 46 in a state of being substantially separated into the liquid acidic gas 41 and the absorbing liquid 42 by the centrifugal separator 48. The absorbing liquid 42 containing the liquid acidic gas 41 supplied to the separation regenerator 46 in a state of being substantially separated into the liquid acidic gas 41 and the absorbing liquid 42 is the mutual insolubility and specific gravity of the liquid acidic gas 41 and the absorbing liquid 42. Due to the difference, the liquid acid gas 41 and the absorbing liquid 42 are quickly phase-separated. Usually, since the liquid acid gas 41 has a lower specific gravity than the absorbing liquid 42, the liquid acid gas 41 quickly floats and shifts to the upper phase, and the absorbing liquid 42 quickly sinks and shifts to the lower phase. As a result, the liquid acidic gas 41 is separated from the absorbing liquid 42 and efficiently recovered from the upper part of the separation regenerator 46 in a relatively short time. Further, the regenerated absorption liquid 42 that does not contain the acid gas discharged from the lower end of the separation regenerator 46 is conveyed by the circulation pump 17 and heated to a predetermined temperature by the heat exchanger 26, and then the upper part of the absorption tower 13. To be reused. When the liquid acidic gas 41 is liquid CO ₂ , dry ice (solid CO ₂ ) that can be sold as a product by adiabatically expanding a part or all of the recovered liquid CO ₂ by opening the pressure reducing valve. Can be manufactured.

<Third Embodiment>
FIG. 3 shows a third embodiment. 3, the same reference numerals as those in FIG. 2 denote the same components.
In this embodiment, the pressure reducing valve, the flash drum, the auxiliary compressor, and the heat exchanger of the second embodiment are not used, and the absorption tower 13, the cooler 47, the centrifuge 48, and the separation regenerator 46 are not used. They are integrally provided in a state of being arranged in the vertical direction from the top to the bottom in order. The configuration other than the above is the same as that of the second embodiment.
In the purification apparatus configured as described above, the absorption tower 13, the cooler 47, the centrifuge 48, and the separation regenerator 46 are integrally provided. Therefore, the operation is the second implementation except that the apparatus can be reduced in size. Since it is substantially the same as the embodiment of FIG. When the liquid acidic gas 41 is liquid CO ₂ , dry ice (solid CO ₂ ) that can be sold as a product by adiabatically expanding a part or all of the recovered liquid CO ₂ by opening the pressure reducing valve. Can be manufactured.

<Fourth embodiment>
FIG. 4 shows a fourth embodiment. 4, the same reference numerals as those in FIG. 1 denote the same components.
In this embodiment, a porous membrane is impregnated with an absorbing liquid containing an ionic liquid as a main component to form a liquid membrane 51, and the liquid membrane 51 is stretched in the membrane separator 52 to form a membrane separator 52. Is divided into a first chamber 52a and a second chamber 52b, the first chamber 52a is set at a higher pressure than the second chamber 52b, and a mixed gas containing acidic gas and non-acidic gas is further introduced into the first chamber 52a. Configured as follows. The gas supply pipe 18 is provided with a compressor 12 and a precooler 19.
A method for purifying a gas using the purification apparatus configured as described above will be described.
First, the mixed gas is introduced into the first chamber 52 a of the membrane separator 52 in a state where the pressure is increased to a predetermined pressure by the compressor 12 and the precooler 19. At this time, the non-acidic gas remains in the first chamber 52a, and the acidic gas passes through the liquid film 51 and flows into the second chamber 52b, so that the mixed gas is separated into acidic gas and non-acidic gas.

<Fifth embodiment>
FIG. 5 shows a fifth embodiment. 5, the same reference numerals as those in FIG. 2 denote the same components.
In this embodiment, the absorbing liquid 42 mainly composed of an ionic liquid has magnetism, and a magnet 61 is provided below the separation / regenerator 46. Examples of the absorbing liquid 42 having magnetism include an ionic liquid composed of a low-temperature molten salt or a normal-temperature molten salt containing an Fe element in an anion. The magnet 61 is preferably provided on the lower inner surface of the separation regenerator 46, and the separation regenerator 46 is preferably formed of a nonmagnetic material so as not to be affected by the magnet 61. The configuration other than the above is the same as that of the second embodiment.
A method for purifying a gas using the purification apparatus configured as described above will be described.
Since the operation in the absorption tower 13 is substantially the same as that of the first embodiment, repeated description is omitted. Further, the operation until the absorbing liquid 42 containing the liquid acidic gas 41 is supplied from the absorption tower 13 to the separation regenerator 46 is substantially the same as that of the second embodiment, and thus the repeated description is omitted. When the absorption liquid 42 containing the liquid acidic gas 41 is supplied to the separation regenerator 46 that is maintained at a pressure that is substantially the same as the pressure in the absorption tower 13 and that is lower than the temperature in the absorption tower 13, the absorption liquid Since the liquid acid gas 41 has a lower specific gravity than the liquid acid gas 42, the absorption liquid 42 is caused by the mutual insolubility and specific gravity difference between the liquid acid gas 41 and the absorption liquid 42 and the attractive force of the magnet 61 of the magnetic absorption liquid 42. And liquid acidic gas 41 are quickly separated. That is, the liquid acidic gas 41 quickly moves to the upper phase, and the absorbing liquid 42 quickly moves to the lower phase. As a result, the liquid acid gas 41 can be quickly recovered from the separation regenerator 46, and the absorption liquid 42 regenerated by removing the liquid acid gas 41 is supplied to the upper portion of the absorption tower 13 by the circulation pump 17 and quickly. Can be reused.

<Sixth Embodiment>
FIG. 6 shows a sixth embodiment. 6, the same reference numerals as those in FIG. 2 denote the same components.
In this embodiment, an absorption liquid storage tank 72 in which the absorption liquid 42 to which the additive 71 is added is stored. Examples of the additive 71 include polar solvents, that is, one or more additives selected from the group consisting of water, alcohols, ethers, and phenols. Specifically, examples of alcohols include methanol and ethanol, examples of ethers include dimethyl ether and ethyl ether, and examples of phenols include phenol and the like. These additives 71 hardly interfere with the ability of the absorbing liquid 42 to absorb the acidic gas. Moreover, 1 to 50 weight% of an additive is added to the absorption liquid 42 in the absorption liquid storage tank 72 with respect to 100 weight% of absorption liquid, Preferably 5 to 10 weight% is added. Here, the additive is limited to the range of 1 to 50% by weight. If the amount is less than 1% by weight, the effect of reducing the viscosity of the absorbing liquid 42 cannot be obtained so much. This is because it has an adverse effect on the absorption performance. In the absorption liquid storage tank 72, a stirrer 73 is provided in order to disperse the additive 71 uniformly in the absorption liquid 42. The lower part of the absorption liquid storage tank 72 is connected to the upper part of the absorption tower 13 by an absorption liquid supply pipe 74. Further, the absorption liquid supply pipe 74 includes an absorption liquid supply pump 76 that supplies the additive-containing absorption liquid 75 in the absorption liquid storage tank 72 to the upper part of the absorption tower 13, and an on-off valve 77 that opens and closes the absorption liquid supply pipe 74. Is provided. The configuration other than the above is the same as that of the second embodiment.

A method for purifying a gas using the purification apparatus configured as described above will be described.
First, when the additive 71 is added to the absorbent 42 in the absorbent reservoir 72 and mixed by the stirrer 73, the additive 71 is dispersed in the absorbent 42 and the viscosity of the absorbent 42 decreases. Next, the opening / closing valve 77 is opened, and the additive-containing absorbing liquid 75 is supplied to the upper portion of the absorption tower 13 by the absorbing liquid supply pump 76, and then the opening / closing valve 77 is closed. Further, the additive-containing absorption liquid 75 is circulated between the absorption tower 13 and the separation regenerator 46 by the circulation pump 17 instead of the absorption liquid of the second embodiment. As a result, it is possible to absorb the acidic gas in the absorption tower 13 without substantially reducing the ability of the additive-containing absorbent 75 to absorb the acidic gas. Further, since the additive-containing absorbing liquid 75 having a low viscosity circulates smoothly between the absorption tower 13 and the separation regenerator 46, the handling of the absorbing liquid becomes easy. When water is used as the additive 71, water as the additive 71 is circulated in the absorption tower 13. Therefore, before supplying the absorption tower 13, acidic gas containing CO ₂ gas is removed by the dehumidifier 11. It is not necessary to dehumidify. However, if the dehumidifier 11 is not provided, if the amount of water in the absorbent 42 circulated to the absorption tower 13 increases beyond the range of the amount of additive added, the dehumidifier 11 is provided. Is good. Thereby preventing a significant reduction in absorption capacity of the CO ₂ by the absorbing liquid 42. Since the operation other than the above is substantially the same as the operation of the second embodiment, repeated description will be omitted.

<Seventh embodiment>
FIG. 7 shows a seventh embodiment. 7, the same reference numerals as those in FIG. 6 denote the same components.
In this embodiment, an additive storage tank 81 in which one or two or more additives 71 selected from the group consisting of polar solvents, that is, water, alcohols and ethers, is stored in the separation regenerator 46. Connected to the upper part, the pressure adjusting means 82 is provided in the separation regenerator 46, the distillation separator 83 is connected to the lower part of the separation regenerator 82, and the heating means 84 is provided on the lower surface of the distillation separator 83. The lower part of the distillation separator 83 is connected to the suction port of the circulation pump 17 by the second return pipe 32. The pressure in the separation regenerator 46 is adjusted to 4 to 25 MPa, preferably 6 to 10 MPa by the pressure adjusting means 82. The temperature in the distillation separator 83 is adjusted to 50 to 250 ° C., preferably 100 to 150 ° C. by the heating means 84. Here, the reason why the pressure in the separation regenerator 46 adjusted by the pressure adjusting means 82 is limited to the range of 4 to 25 MPa is that a gas phase may be generated if the pressure is less than 4 MPa. This is because the density of the liquid acidic gas 41 becomes higher and the density of the absorbing liquid 42 approaches. Further, the temperature in the distillation separator 83 adjusted by the heating means 84 is limited to the range of 50 to 250 ° C. The complete separation of the additive 71 is difficult when the temperature is less than 50 ° C., and much energy is obtained when the temperature exceeds 250 ° C. It is necessary. Further, a check valve 86 is provided in the second communication pipe 22 between the centrifuge 48 and the separation regenerator 46. The check valve 86 allows the flow of the additive-containing absorption liquid 75 from the centrifuge 48 to the separation regenerator 46 and allows the flow of the additive-containing absorption liquid 75 from the separation regenerator 46 to the centrifuge 48. Configured to block. The phenols of the sixth embodiment are excluded from the additive of the seventh embodiment because the boiling points of the phenols are high, and when they are separated by distillation operation, they are considerably heated (250 ° C. This is because complete separation cannot be achieved without heating. The configuration other than the above is the same as that of the sixth embodiment.
A method for purifying a gas using the purification apparatus configured as described above will be described.
Liquid acid gas in a state where the temperature in the separation regenerator 46 is adjusted to a range of 0 to 30 ° C. by the cooler 47 and the pressure in the separation regenerator 46 is adjusted to a range of 4 to 25 MPa by the pressure force adjusting means 82. When the additive 71 is supplied to the separator / regenerator 46 together with the absorbent 42 containing 41, the mutual insolubility and specific gravity difference between the liquid acidic gas 41 and the additive-containing absorbent 75 and the mutual solubility with respect to the absorbent 42 are obtained. The upper phase of the separator / regenerator 46 is obtained by replacing the liquid acid gas 41 dispersed in the absorption liquid 42 with the additive 71 by the addition of the additive 71 having the mutual insolubility with the liquid acid gas 41. Thus, the liquid acidic gas 41 moves to the lower phase and the additive-containing absorbing liquid 75 moves to the lower phase of the separation regenerator 46, so that the liquid acidic gas 41 and the additive-containing absorbing liquid 75 are quickly separated. Next, the additive-containing absorbing liquid 75 discharged from the lower part of the separation / regenerator 46 is distilled and separated while the distillation separator 83 is heated to a temperature of 50 to 250 ° C., preferably 100 to 150 ° C. by the heating means 84. When supplied to the vessel 83, the additive 71 in the additive-containing absorbent 75 is distilled and separated from the absorbent 42. As a result, since the additive 71 and the absorbing liquid 42 can be recovered in a separated state, the absorbing liquid 42 from which the additive 71 has been removed is supplied to the absorption tower 13, and the additive 71 from which the absorbing liquid 42 has been removed is the additive. The absorption liquid 42 and the additive 71 can be reused immediately after being supplied to the storage tank 81, and the absorption tower 13 can absorb the acid gas without reducing the ability of the absorption liquid 42 to absorb the acid gas at all. it can. Since the operation other than the above is substantially the same as the operation of the second embodiment, repeated description will be omitted.

<Eighth Embodiment>
FIG. 8 shows an eighth embodiment. 8, the same reference numerals as those in FIG. 7 denote the same components.
In this embodiment, the acidic gas is CO ₂ gas, and the pressure adjusting means 82 for maintaining the pressure in the separation regenerator 46 at 4 to 25 MPa, preferably 6 to 10 MPa is provided in the separation regenerator 46 to store water. The water storage tank 91 is connected to the lower part of the separation regenerator 46. In addition, a solid-liquid separator 92 is connected to the separation regenerator 46, and a sub-separation regenerator 93 is connected to the upper part of the solid-liquid separator 92. The lower part of the sub separation regenerator 93 is connected to the suction port of the circulation pump 17 by the second return pipe 32. Here, the reason why the pressure in the separation regenerator 46 adjusted by the pressure adjusting means 82 is limited to the range of 4 to 25 MPa is that if it is less than 4 MPa, it is difficult to generate CO ₂ hydrate, and if it exceeds 25 MPa, the equipment cost is high. This is because the density of the liquid CO ₂ 41 approaches the density of the absorbing liquid 42. Examples of the solid-liquid separator 92 include a filter and a centrifuge. The configuration other than the above is the same as that of the seventh embodiment.
A method for purifying a gas using the purification apparatus configured as described above will be described.
The inside of the separation regenerator 46 while maintaining the pressure of 4~25MPa by the pressure regulating means 82, is supplied from the water storage tank 91 the water absorbing solution containing liquid CO ₂ in the separator regenerator 46, the liquid CO ₂ A part of hydrates, that is, solidifies in the shape of snow or sherbet. When the absorption liquid containing this CO ₂ hydrate and liquid CO ₂ is supplied to the solid-liquid separator 92, it is separated into CO ₂ hydrate, liquid CO ₂ and absorption liquid, and the CO ₂ hydrate is separated from the solid-liquid separator 92. It is discharged from the bottom. On the other hand, the solid-liquid is supplied and the separator liquid CO ₂ in 92 absorption liquid to the sub separation regenerator 93, by mutual insolubility and the difference in specific gravity liquid CO ₂ 41 and the absorption liquid 42, the liquid CO ₂ 41 and absorbing solution 42. By generating the CO ₂ hydrate in this way, the liquid CO ₂ 41 can be separated from the absorbing liquid 42 more quickly. Since the operation other than the above is substantially the same as the operation of the second embodiment, repeated description will be omitted.

<Ninth embodiment>
FIG. 9 shows a ninth embodiment.
In this embodiment, after reforming, converting CO and removing CO to form a mixed gas of H ₂ and CO ₂ , this mixed gas is used as the gas purification method of the first to eighth embodiments or Using one of the gas purifiers, H ₂ and CO ₂ are separated and recovered, and the separated and recovered H ₂ is supplied to the hydrogen station, and the separated and recovered CO ₂ is adiabatically expanded to dry ice ( Configured to produce solid CO ₂ ). Examples of the fuel include one or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas. The reforming of the fuel is steam reforming, partial oxidation, or supercritical water reforming, and the fuel is reformed into H ₂ and CO by the reforming. Also, most of CO is converted to CO ₂ by CO conversion, and a little remaining CO is removed by CO removal. The remaining mixed gas of H ₂ and CO ₂ is high pressure H ₂ and CO _{2 in a} gaseous state or a liquid state using either the gas purification method or the gas purifying apparatus of the first to eighth embodiments. Separated. Further, the high pressure H ₂ is supplied to the hydrogen station and becomes a fuel for a hydrogen fuel cell vehicle. On the other hand, when CO ₂ is recovered in a liquid state, dry ice that can be sold as a product can be manufactured by adiabatically expanding a part or all of the recovered liquid CO ₂ by opening the pressure reducing valve. When CO ₂ is recovered in a gaseous state, the recovered CO ₂ gas is pressurized to liquid CO ₂ , and then a part or all of the liquid CO ₂ is adiabatically expanded by opening the pressure reducing valve. Dry ice (solid CO ₂ ) that can be sold as a product can be manufactured.

<Tenth Embodiment>
FIG. 10 shows a tenth embodiment.
In this embodiment, after the fuel is reformed on the vehicle, CO conversion and CO removal are made into a mixed gas of H ₂ and CO ₂ , this mixed gas is used as the gas of the second to eighth embodiments. A system that separates and recovers H ₂ and CO ₂ using either a purification method or a gas purifier and supplies the separated and recovered H ₂ to the fuel cell, Installed in quality vehicles. Examples of the fuel include one or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas. The reforming of the fuel is steam reforming, and the fuel is reformed into H ₂ and CO by the steam reforming. Also, most of CO is converted to CO ₂ by CO conversion, and a little remaining CO is removed by CO removal. And the remaining mixed gas of H ₂ and CO ₂ is separated into the high pressure H ₂ and liquid CO ₂ using any of the purification device purifying method or gas in the gas of the embodiment of the second to eighth. Further, the high pressure H ₂ is supplied to the fuel cell, and the liquid CO ₂ is temporarily stored in the vehicle and later lowered together. As a result, liquid CO ₂ can be efficiently recovered while producing high-pressure H ₂ from various fuels. That is, a CO ₂ zero emission vehicle can be realized by collecting CO ₂ in liquid form and temporarily storing it on the vehicle.

One or more additives selected from the group consisting of water, alcohols, ethers and phenols may be added to the absorbent of the purification apparatus shown in the first embodiment. In this case, without reducing the ability of the absorbing liquid to absorb the acidic gas, the absorbing liquid flows smoothly and handling of the absorbing liquid is facilitated, and the acidic gas is smoothly removed from the absorbing liquid whose viscosity has been reduced by the additive. Can be separated by distillation.
Moreover, you may add a flocculant to the absorption liquid containing the liquid acidic gas in a separation regenerator. In this case, a flocculant tank storing the flocculant is connected to the separation regenerator. By adding the flocculant stored in the flocculant tank to the absorbing liquid containing the liquid acidic gas in the separation / regenerator, the liquid acidic gas dispersed in the absorbing liquid can be made into a fine liquid. Therefore, if the lower part of the separation regenerator is connected to the suction port of the circulation pump, the pressure in the separation regenerator is set to 4 to 25 MPa and the temperature is set to 0 to 30 ° C., the liquid acidity in the separation regenerator Since the specific gravity difference separation between the gas and the flocculant-containing absorbing liquid proceeds promptly, the gas is quickly separated into the liquid acidic gas and the flocculant-containing absorbing liquid, and the flocculant-containing absorbing liquid is supplied to the distillation separator. On the other hand, the lower part of the separation regenerator is connected to a distillation separator with a heating means, the lower part of the distillation separator is connected to the inlet of the circulation pump, and the upper part of the distillation separator is connected to the flocculant tank. The specific gravity difference between the liquid acid gas and the flocculant-containing absorbing liquid proceeds quickly in the regenerator, and the flocculant is distilled and separated from the absorbing liquid in the distillation separator. The liquid is quickly separated from the liquid, and only the absorption liquid is supplied to the absorption tower.
Furthermore, the purification method or purification apparatus according to an embodiment of the 2,3,5～8, high-pressure gas source which is discharged from oil refineries and ammonia plants, high CO ₂ Steel exhaust gas (CO ₂ concentration: about 27 %) And fermentation gas (CO ₂ concentration: about 30 to 40%) or the like, that is, these gas sources are used in the purification methods of the second, third, and fifth to eighth embodiments or is supplied to the absorption tower purification device, the liquid CO ₂ or dry ice may be produced. Since the purification method or the purification apparatus of the second, third, and fifth to eighth embodiments basically uses the physical absorption method, the running cost of the conventional (existing) liquid CO ₂ production plant is 70 to 70. Renewable energy costs accounting for 80%, regenerative gas (CO ₂ ) compression costs, regenerative gas (CO ₂ ) refrigeration costs, recompression absorbent recompression costs, and the like can be made almost unnecessary. As a result, for the liquid CO ₂ production facility that has been depreciated to some extent, the refining method or apparatus of the second, third, and fifth to eighth embodiments is employed rather than continuing to operate the existing facility. There is a merit in terms of cost to replace it with equipment.

Next, embodiments of the present invention will be described in detail.
<Example 1>
An absorbing solution consisting only of an ionic liquid was used. Specifically, 1-n-decyl-3-methylimidazolium hexafluorophosphate [DMIM] [PF ₆ ] was used as the ionic liquid. The absorbent was heated to 70 ° C. in a vacuum of 1 × 10 ⁻⁴ Pa, dried and degassed. The water content in the absorbent after deaeration was 0.2% by weight or less. This absorbent was designated as Example 1.
<Example 2>
An absorbing solution consisting only of an ionic liquid was used. Specifically, 1-n-decyl-3-methylimidazolium tetrafluoroborate (DMIM) [BF ₄ ] was used as the ionic liquid. This absorbing solution was dried and degassed by heating to 70 ° C. in a vacuum of 1 × 10 ⁻⁴ Pa. The water content in the absorbing solution after degassing was 0.2% by weight or less. The liquid was designated as Example 2.

<Example 3>
An absorbing solution consisting only of an ionic liquid was used. Specifically, (1-n-octyl-3-methylimidazolium nitrate [OMIM] [NO ₃ ]) was used as the ionic liquid. This was dried and degassed by heating to 70 ° C. in a vacuum of 1 × 10 ⁻⁴ Pa. The water content in the absorbent after degassing was 0.2% by weight or less. It was.
<Example 4>
An absorbing solution consisting only of an ionic liquid was used. Specifically, N-ethyl-pyridinium tetrafluoroborate [N-ETPY] [PF6] was used as the ionic liquid. The absorbent was heated to 70 ° C. in a vacuum of 1 × 10 ⁻⁴ Pa, dried and degassed. The water content in the absorbent after deaeration was 0.2% by weight or less. This absorbing solution was referred to as Example 4.

<Test 1 and evaluation>
The absorption liquids of Examples 1 to 4 were brought into contact with high purity CO ₂ gas (acid gas) having a purity of 99.99% by volume. Specifically, the solubility of the CO ₂ gas in the absorbing solution was measured using a high-pressure gas-liquid equilibrium measuring device. The measurement temperature was kept constant at 35 ° C., 45 ° C. and 55 ° C., and the pressure was changed stepwise from atmospheric pressure to 10 MPa. From the amount of CO ₂ gas which has not been total and the absorption of CO ₂ gas as a source gas, to calculate the solubility of the absorption liquid CO ₂ gas in a molar fraction, and the results are shown in FIGS. 11 to 13.
By recovered by the CO ₂ that melted into the absorption liquid depressurization, the CO ₂ gas recovered absorbing liquid was not detected, it was confirmed that a pure CO ₂ gas. Further, as apparent from FIGS. 11 to 13, it was found that the solubility of the CO ₂ gas in the absorbing liquid increases as the pressure increases.

<Test 2 and evaluation>
Using the absorption liquid of Example 1, a gas-liquid equilibrium test with various gases (non-acid gases) of H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas was performed separately for each type of gas. It was. The purity of the H ₂ gas, CH ₄ gas, CO gas and N ₂ gas was 99.99% by volume, 99.97% by volume, 99.97% by volume and 99.999% by volume, respectively. Specifically, using a high-pressure gas-liquid equilibrium measuring device, the solubility of the various gases of H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas in the absorbing solution was measured. The measurement temperature was kept constant at 35 ° C., and the pressure was changed stepwise from atmospheric pressure to 10 MPa. From the amount of various gases and the amount of various gases that were not absorbed, the solubility of H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas in the absorbing solution was calculated in mole fractions, and the results were calculated as follows. As shown in FIG.
In the recovered H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas by recovering various gases of H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas dissolved in the absorbing solution by decompression operation, respectively. Thus, no absorption liquid was detected, and it was confirmed that it was pure H ₂ gas, CH ₄ gas, CO gas, and N ₂ gas. Further, as is apparent from FIG. 14, it was found that the absorbing liquid hardly absorbs H ₂ gas, CH ₄ gas, CO gas and N ₂ gas.

<Test 3 and evaluation>
Using the absorption liquid of Example 1, a gas-liquid equilibrium test with various gases (acid gases) of CO ₂ gas, H ₂ S gas, and COS gas was performed separately for each type of gas. The purity of the CO ₂ gas, H ₂ S gas, and COS gas was as high as 99.9% by volume or more. Specifically, the solubility of each gas of the CO ₂ gas, H ₂ S gas, and COS gas in the absorbing solution was measured using a high-pressure gas-liquid equilibrium measuring device. The measurement temperature was kept constant at 35 ° C., and the pressure was changed stepwise from atmospheric pressure to 10 MPa. From the amount of various gases and the amount of various gases that have not been absorbed, the solubility of each gas in the absorbing solution of CO ₂ gas, H ₂ S gas and COS gas is expressed as solubility per unit volume (Nm ³ / m ³ ). The results are shown in FIG.
As apparent from FIG. 15, the solubility per unit volume of various gases of CO ₂ gas, H ₂ S gas, and COS gas in the absorption liquid increases as the pressure increases, and the solubility of H ₂ S gas is the largest. It was found that the solubility of COS gas was the next highest and the solubility of CO ₂ gas was the lowest.

<Test 4 and evaluation>
In order to confirm the degree of phase separation due to the mutual insolubility with liquid CO ₂ and the difference in specific gravity using the absorbing liquid (ionic liquid) of Example 1, a high-pressure vessel (set at a pressure of 7 MPa at a temperature of 20 ° C.) The absorption liquid and the liquid CO ₂ were respectively injected into the transparent member visible from the outside. The injected absorption liquid (specific gravity 1.37) and liquid CO ₂ (specific gravity 0.81) were in two liquid phases due to mutual insolubility and specific gravity difference. Next, the absorbing liquid and liquid CO ₂ in the high-pressure vessel were stirred for 5 minutes with a stirrer to become a homogeneous phase, and then the stirrer was stopped and allowed to stand for 10 minutes. FIG. 16 shows the state of the absorbing liquid and the liquid CO ₂ in the high-pressure vessel after standing still.
As is clear from FIG. 16, it was found that the absorption liquid and the liquid CO ₂ were separated again by allowing to stand after stirring. This is considered that the absorption liquid and the liquid CO ₂ were insoluble in each other and the specific gravity difference was large, so that they were quickly separated into two liquid phases. Moreover, the liquid surface of the two liquid phases before stirring and the liquid surface of the two liquid phases after stirring and allowing to stand were at the same level.

It is a section lineblock diagram of a gas refining method and its device of a 1st embodiment of the present invention. It is a section lineblock diagram corresponding to Drawing 1 showing a 2nd embodiment of the present invention. It is a cross-sectional block diagram corresponding to FIG. 1 which shows 3rd Embodiment of this invention. It is a section lineblock diagram corresponding to Drawing 1 showing a 4th embodiment of the present invention. It is a section lineblock diagram corresponding to Drawing 1 showing a 5th embodiment of the present invention. It is a cross-sectional block diagram corresponding to FIG. 1 which shows 6th Embodiment of this invention. It is a section lineblock diagram corresponding to Drawing 1 showing a 7th embodiment of the present invention. It is a section lineblock diagram corresponding to Drawing 1 showing an 8th embodiment of the present invention. It is a block diagram which shows the system of 9th Embodiment of this invention. It is a block diagram which shows the system of 10th Embodiment of this invention. It is a diagram showing the changes associated with pressure change in the solubility of CO ₂ into the absorbing solution in Examples 1 to 4 at a measurement temperature of 35 ° C.. It is a diagram showing the changes associated with pressure change in the solubility of CO ₂ into the absorbing solution in Examples 1 to 4 at a measurement temperature of 45 ° C.. It is a diagram showing the changes associated with pressure change in the solubility of CO ₂ into the absorbing solution in Examples 1 to 4 at a measurement temperature of 55 ° C.. It is a figure which shows the change accompanying the pressure change of the solubility of the non-acidic gas in the absorption liquid of Example 1 in the measurement temperature of 35 degreeC. It is a diagram showing a CO _2, H ₂ S and solubility change caused by pressure changes in the COS to the absorption solution of Example 1 at a measurement temperature of 35 ° C.. Absorbing liquid is a photographic view showing the state of phase separation (ionic liquid) and the liquid CO _2.

Explanation of symbols

11 dehumidifier 12 compressor 13 absorber 16 regenerator 17 circulation pump 41 liquid acid gas, liquid CO ₂
42 Absorbing liquid 46 Separator / Regenerator 47 Cooler 48 Centrifugal separator 51 Liquid membrane 52 Membrane separator 52a First chamber 52b Second chamber 61 Magnet 71 Additive 72 Absorbing liquid reservoir 75 Additive-containing absorbing liquid 81 Additive reservoir 82 Pressure adjusting means 83 Distillation separator 84 Heating means 91 Water storage tank

Claims (27)

An absorption liquid mainly composed of an ionic liquid is supplied to the upper part of the absorption tower (13) maintained at a predetermined temperature and a predetermined pressure, and an acidic gas and a non-acidic gas are supplied to the lower part of the absorption tower (13). The mixed gas is supplied, and the mixed gas is brought into contact with the absorbing liquid, whereby the acidic gas is absorbed into the absorbing liquid to separate the non-acidic gas and the acidic gas, Recovering from the absorption tower (13);
Absorbing liquid that has absorbed the acidic gas in the upper part of the regeneration tower (16) maintained at a temperature equal to or higher than the temperature in the absorption tower (13) and maintained at a pressure lower than the pressure in the absorption tower (13). To recycle the absorption liquid while dissipating the acidic gas and separating it from the absorption liquid and recovering from the regeneration tower (16),
Supplying the regenerated absorption liquid to the upper part of the absorption tower (13). An absorption liquid (42) mainly composed of an ionic liquid is supplied to the upper part of the absorption tower (13) maintained at a predetermined temperature and a predetermined pressure, respectively, and an acid gas and a lower part of the absorption tower (13) are supplied. By supplying a mixed gas containing a non-acidic gas and bringing the mixed gas into contact with the absorbing liquid (42), the acidic gas is absorbed into the absorbing liquid (42), and the non-acidic gas and the acidic gas are absorbed. And recovering the non-acidic gas from the absorption tower (13);
The acidic gas is liquefied by supplying the absorbing liquid that has absorbed the acidic gas to the separation regenerator (46) maintained at a predetermined pressure and maintained at a temperature lower than the temperature in the absorption tower (13). The liquid acid gas (41) is separated from the absorption liquid (42) by the mutual insolubility and specific gravity difference between the liquid acid gas (41) and the absorption liquid (42) and recovered from the separation regenerator (46). And regenerating the absorbing liquid (42),
Supplying the regenerated absorption liquid to the upper part of the absorption tower (13).   A liquid membrane (51) in which a porous membrane is impregnated with an absorption liquid mainly composed of an ionic liquid is stretched in a membrane separator (52), and the membrane separator (52) is connected to the first chamber (52a). A second chamber (52b) is partitioned, the first chamber (52a) is set at a higher pressure than the second chamber (52b), and the first chamber (52a) is mixed with acidic gas and non-acidic gas. By introducing gas, the acidic gas passes through the liquid film (51) while the non-acidic gas remains in the first chamber (51a) and moves to the low pressure second chamber (52b). And refining the non-acid gas from the first chamber (52a) and the acid gas from the second chamber (52b). The acidic gas is one or more gases selected from the group consisting of CO ₂ , H ₂ S, COS, SO ₂ , SO ₃ , NO ₂ , CS ₂ , HCN, NH ₃ and mercaptans, and is non-acidic The gas is one or more gases selected from the group consisting of H ₂ , CH ₄ , CO, O ₂ , N ₂ and a hydrocarbon compound having 2 to 10 carbon atoms. 2. A gas purification method according to item 1. The ionic liquid has a cation and an anion,
The cation is [R, R′—N ₂ C ₃ H ₃ ] ⁺ (N, N′-dialkylimidazolium), [NR _X H _4−X ] ⁺ (alkylammonium), [R—NC ₅ H _5. ] ⁺ (N-alkylpyridinium), [R-NC ₄ H ₈ ] ⁺ (N-alkylpyrrolidinium) and 1 selected from the group consisting of [PR _X H _4-X ] ⁺ (alkylphosphonium) A species or two or more cations,
The anion is one or more anions selected from the group consisting of PF ₆ ⁻ , BF ₄ ⁻ , NO ₃ ⁻ , EtSO ₄ ⁻ , AlCl ₄ ⁻ and AlBr ₄ ⁻ ;
R and R ′ in the cation are an alkyl group having 1 to 18 carbon atoms or hydrogen,
The gas purification method according to any one of claims 1 to 3, wherein X in the cation is 1 to 3.   The gas purification method according to any one of claims 1 to 3, wherein the absorbing liquid (42) containing an ionic liquid as a main component is neutral or alkaline.   The gas purification method according to claim 1 or 2, further comprising a step of dehumidifying the mixed gas before supplying the mixed gas to the absorption tower (13).   The gas purification method according to claim 3, further comprising the step of dehumidifying the mixed gas before introducing the mixed gas into the membrane separator (52).   The temperature in the absorption tower (13) is maintained at 0 to 100 ° C. and the pressure is maintained at 1 to 25 MPa, and the temperature in the regeneration tower (16) is the same as the temperature in the absorption tower (13) or the absorption tower The gas purification method according to claim 1, wherein the pressure is maintained at 0.1 to 5 MPa lower than the pressure in the absorption tower (13) while being maintained at 30 to 200 ° C higher than the temperature in (13).   The pressure in the absorption tower (13) is maintained at 4 to 25 MPa, the temperature is maintained at 0 to 100 ° C., and the pressure in the separation regenerator (46) is maintained at 4 to 25 MPa. The gas purification method according to claim 2, wherein the gas is maintained at -30 to 30 ° C lower than the temperature in 13).   Before supplying to the separation regenerator (46), the absorption liquid containing acid gas discharged from the absorption tower (13) and cooled to a temperature lower than the temperature in the absorption tower (13) is centrifuged or stirred. The gas purification method according to claim 2, further comprising a step.   The gas purification method according to claim 2, wherein the absorbing liquid (42) containing an ionic liquid as a main component has magnetism, and a magnet (61) is provided at a lower portion of the separation regenerator (46).   The gas purification method according to claim 1 or 2, wherein one or more additives (71) selected from the group consisting of water, alcohols, ethers and phenols are added to the absorbent (42).   One or more additives (71) selected from the group consisting of water, alcohols and ethers are supplied to the separation regenerator (46), and the pressure and temperature in the separation regenerator (46). By adjusting the specific gravity difference between the liquid acid gas (41) and the additive-containing absorbent (75) in the separation regenerator (46), and the separation regenerator (46) discharged from the separation regenerator (46). The additive-containing absorbing liquid (75) is supplied to the distillation separator (83), and the inside of the distillation separator (83) is heated to a predetermined temperature, whereby the additive-containing absorbing liquid (75) is added. The method for purifying a gas according to claim 2, further comprising a step of distilling and separating the agent (71) from the absorbing liquid (42).   The method for purifying a gas according to claim 2, wherein the flocculant is added to the absorbing liquid containing the liquid acidic gas in the separation regenerator. The gas according to claim ₂ , wherein the acid gas is CO ₂ gas, and water is supplied into the absorption liquid (42) containing liquid CO ₂ (41) in the separation regenerator (46) maintained at a pressure of 4 to 25 MPa. Purification method. A dehumidifier (11) for dehumidifying a mixed gas containing acidic gas and non-acidic gas;
A compressor (12) for compressing the dehumidified mixed gas;
The compressed gas mixture is supplied to the lower part, and the upper part is supplied with an absorbing liquid (42) mainly composed of an ionic liquid, and the mixed gas is brought into contact with the absorbing liquid (42), thereby allowing the acidic gas to flow. An absorption tower (13) that absorbs the absorbing liquid (42) to separate and recover the non-acidic gas from the acidic gas;
A cooler (47) for cooling the absorbing liquid (42) that has absorbed the acid gas;
The cooled absorption liquid (42) is supplied, and the liquid acid gas (41) is separated from the absorption liquid (42) by the mutual insolubility and specific gravity difference between the liquid acid gas (41) and the absorption liquid (42). Separating and regenerator (46) to recover and reuse the absorption liquid (42),
A gas purification apparatus comprising: a circulation pump (17) for supplying the absorption liquid (42) discharged from the separation / regenerator (46) to the upper part of the absorption tower (13) with a high pressure.   The gas purifier according to claim 17, wherein the absorption tower (13), the cooler (47), and the separation regenerator (46) are integrally provided.   The gas purifier according to claim 17 or 18, wherein a centrifuge (48) or a stirrer is provided between the cooler (47) and the separation regenerator (46).   20. The gas according to any one of claims 17 to 19, wherein the absorbing liquid (42) mainly composed of an ionic liquid has magnetism, and a magnet (61) is provided at a lower part of the separation regenerator (46). Purification equipment.   Absorption liquid (42) added with one or more additives (71) selected from the group consisting of water, alcohols, ethers and phenols is stored, and this additive-containing absorption liquid (75) is stored. 21. The gas purifier according to any one of claims 17 to 20, further comprising an absorption liquid storage tank (72) for supplying the absorption tower (13).   An additive storage tank (81) in which one or more additives (71) selected from the group consisting of water, alcohols and ethers are stored and connected to the upper part of the separation regenerator (46); Pressure adjusting means (82) for adjusting the pressure in the separation regenerator (46) provided in the separation regenerator (46), and the separation regenerator (46) connected to the lower part of the separation regenerator (46) The distillation separator (83) for storing the additive-containing absorption liquid (75) separated in specific gravity and transferred to the lower phase thereof, and the inside of the distillation separator (83) provided in the distillation separator (83) 21. The gas purifier according to any one of claims 17 to 20, further comprising a heating means (84) for heating to a predetermined temperature.   The gas purifier according to any one of claims 17 to 20, wherein a flocculant tank for storing the flocculant is connected to a separation regenerator. A water storage tank in which the acidic gas is CO ₂ gas, pressure adjusting means (82) for maintaining the pressure in the separation regenerator (46) at 4 to 25 MPa is provided in the separation regenerator (46), and water is stored 21. The gas purifier according to any one of claims 17 to 20, wherein (91) is connected to a lower portion of the separation regenerator (46).   25. An acidic gas absorbing solution used in the gas purification method according to any one of claims 1 to 16 or used in the gas purification device according to any one of claims 17 to 24. One or two or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas and natural gas are reformed, CO converted and CO removed to mix H ₂ and CO ₂ After the gas is formed, the mixed gas is used by using the gas purification method described in any one of claims 1 to 16 or using the gas purification device described in any one of claims 17 to 24. A system that separates and collects H ₂ and CO ₂ , supplies the separated and collected H ₂ to a hydrogen station, and adiabatically expands the separated and collected CO ₂ to produce dry ice. One or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas are installed in an on-vehicle reforming vehicle that uses a fuel cell as a drive source. The mixed gas according to any one of claims 2, 4, 5, 6, 7, 10 to 16, after reforming, CO conversion and CO removal on a vehicle to form a mixed gas of H ₂ and CO _2. 25. Using the purified gas purification method or using the gas purification apparatus according to any one of claims 17 to 24, the gas is separated and recovered into H ₂ and liquid CO _2, and the separated and recovered H ₂ is further recovered. A system that supplies the fuel cell and temporarily stores the liquid CO ₂ in the vehicle and collects it later.