JP4730312B2 - Separation and regeneration apparatus for absorbing liquid and liquid carbon dioxide, and gas purification apparatus using the separation and regeneration apparatus - Google Patents

Description

  The present invention relates to an apparatus that separates carbon dioxide gas as liquid carbon dioxide from an absorbing liquid that has absorbed carbon dioxide gas and regenerates the absorbing liquid, and a gas purification apparatus that uses the separating and reproducing apparatus.

Conventionally, as a gas purification apparatus, a mixed gas containing an acidic gas such as carbon dioxide gas compressed by a compressor and a non-acidic gas such as H ₂ is supplied to the lower part of the absorption tower, and an organic solvent is provided to the upper part of the absorption tower. Alternatively, an absorption liquid mainly composed of one or both of water is supplied, and the mixed gas is brought into contact with the absorption liquid, thereby absorbing the acidic gas into the absorption liquid and separating and recovering the non-acidic gas from the acidic gas. The absorption liquid that has absorbed the acid gas is cooled by the cooler and then supplied to the separation / regenerator, and the liquid acid gas is separated from the absorption liquid and recovered by the mutual insolubility and specific gravity difference between the liquid acid gas and the absorption liquid. In addition, a gas purification device that regenerates and reuses the absorbent is disclosed (for example, see Patent Document 1). This gas purification apparatus is configured such that the absorption liquid discharged from the separation regenerator is supplied to the upper part of the absorption tower with a high pressure by a circulation pump.
In the gas purification apparatus configured as described above, an absorption liquid mainly composed of one or both of an organic solvent and water is supplied to the upper part of the absorption tower maintained at a predetermined temperature and a predetermined pressure, When a mixed gas containing acidic gas and non-acidic gas is compressed and supplied to the lower part of the absorption tower, the mixed gas comes into contact with the absorbing liquid and the acidic gas is absorbed by the absorbing liquid. It is separated from the acid gas and recovered from the absorption tower. The absorption liquid that has absorbed the acid gas is cooled in a separation regenerator maintained at the same pressure as the pressure in the absorption tower, slightly lower than the pressure in the absorption tower, or slightly higher than the pressure in the absorption tower. When it is supplied after being cooled by the regenerator, the acidic gas is liquefied by the separation regenerator, and the liquid acidic gas is separated from the absorbing liquid due to the mutual insolubility and specific gravity difference between the liquid acidic gas and the absorbing liquid. To be recovered. The absorption liquid regenerated by removing the liquid acid gas is supplied to the upper part of the absorption tower by a circulation pump and reused.
WO 2006/103812 pamphlet (claim 19, paragraph [0015], FIG. 2)

However, in the conventional gas purification apparatus disclosed in Patent Document 1, the pressure fluctuates in a state where the separation regenerator is filled with an incompressible liquid acidic gas (such as liquid carbon dioxide) and an absorbing liquid. Then, the pressure fluctuation becomes extremely large, and there is a problem that the phase separation efficiency between the liquid acidic gas and the absorbing liquid in the separation regenerator is lowered.
Further, in the gas purification apparatus disclosed in the above-mentioned conventional patent document 1, the liquid acidity from the absorbing liquid is determined from the mutual insolubility and specific gravity difference between the liquid acidic gas (liquid carbon dioxide, etc.) and the absorbing liquid in the separation regenerator. Even if the gas is phase-separated, only the insolubility and the specific gravity difference between the liquid acid gas and the absorption liquid are required to separate the liquid acid gas from the absorption liquid without increasing the size of the separation regenerator. There were also problems that took time.
The first object of the present invention is to prevent a decrease in the phase separation efficiency of the absorption liquid and liquid carbon dioxide in the separation regenerator by absorbing the pressure fluctuation in the separation regenerator with the carbon dioxide gas in the buffer tank. An object of the present invention is to provide a separation / regeneration apparatus for absorbing liquid and liquid carbon dioxide and a gas purification apparatus using this separation / regeneration apparatus.
The second object of the present invention is to provide a separation / regeneration apparatus for absorbing liquid and liquid carbon dioxide that can reduce the size of the separation / regenerator and can efficiently separate liquid carbon dioxide from the absorption liquid in the separation / regenerator. Another object of the present invention is to provide a gas purification apparatus using this separation and regeneration apparatus.
The third object of the present invention is to provide an absorption liquid and liquid carbon dioxide separation / regeneration apparatus and a gas purification apparatus using the separation / regeneration apparatus, which can reliably prevent vaporization of liquid carbon dioxide in the separation / regeneration apparatus. There is.
The fourth object of the present invention is to separate the absorbing liquid from the liquid carbon dioxide, which can be configured relatively compactly and can efficiently separate the carbon dioxide gas from the mixed gas containing carbon dioxide gas and non-acidic gas as liquid carbon dioxide. An object of the present invention is to provide a gas purification apparatus using a regenerator.

As shown in FIGS. 1 and 2, the invention according to claim 1 cools the absorption liquid 11 that has absorbed carbon dioxide gas to form an absorption liquid 11 in which liquid carbon dioxide 13 in the form of free droplets is dispersed. 26, a separation regenerator 23 that separates the liquid carbon dioxide 13 from the absorption liquid 11 cooled by the cooler 26 and regenerates the absorption liquid 11, and a separation regenerator 23 that is connected to the top of the separation regenerator 23 and is separated in the separation regenerator 23 The separation / regeneration apparatus includes a buffer tank 27 that vaporizes a part or all of the liquid carbon dioxide 13 that has entered, and extends in the vertical direction in the separation / regenerator 23 and separates the separation / regeneration unit 23. A separation plate 23a having an upper communication hole 23d and a lower communication hole 23e that are divided into a chamber 23b and a stationary chamber 23c and communicate with the separation chamber 23b and the stationary chamber 23c at the upper and lower portions, respectively. Characterized by comprising a separation promotion portion 23f which is provided at the center to capture the free drop-shaped liquid carbon dioxide 13 dispersed in the absorption liquid 11 aggregated coarsened of Hanareshitsu 23b.
In the separation / regeneration apparatus for absorbing liquid and liquid carbon dioxide described in claim 1, even if pressure fluctuation occurs in the state where the separation / regenerator 23 is filled with the absorbing liquid 11 and liquid carbon dioxide 13, the buffer tank 27 Since the carbon dioxide gas in the absorber absorbs and reduces the pressure fluctuations of the absorption liquid 11 and the liquid carbon dioxide 13 filled in the separation regenerator 23, the absorption liquid 11 and the liquid carbon dioxide 13 in the separation regenerator 23 are reduced. The pressure can be stably maintained. As a result, it is possible to prevent a decrease in the phase separation efficiency of the absorbing liquid 11 and the liquid carbon dioxide 13 due to the pressure fluctuation in the separation / regenerator 23.
Further, since the liquid carbon dioxide 13 in the form of free droplets dispersed in the absorbing liquid 11 is captured by the separation promoting unit 23f and aggregated to be coarsened, the liquid carbon dioxide 13 can be rapidly phase-separated from the absorbing liquid 11, and the separator Even if the phase-separated absorbing liquid 11 and liquid carbon dioxide 13 flow into the stationary chamber 23c into the stationary chamber 23c partitioned by 23a, almost no convection occurs in the absorbing liquid 11 and liquid carbon dioxide 13, The absorbing liquid 11 and the liquid carbon dioxide 13 are not remixed in the stationary chamber 23c, and the absorbing liquid 11 and the liquid carbon dioxide 13 in the stationary chamber 23c are not refluxed to the separation chamber 23b. As a result, even if the separation regenerator 23 is relatively small, the liquid carbon dioxide 13 can be efficiently separated from the absorbent 11 in the separation regenerator 23.

The invention according to claim 2 is the invention according to claim 1, and further, as shown in FIG. 1, from the cooler 26 inside the jacket tank 31 provided so as to surround the outer peripheral surface of the separation regenerator 23. A feature is that the discharged coolant flows.
In the separation / regeneration apparatus for absorbing liquid and liquid carbon dioxide described in claim 2, when the cooling liquid discharged from the cooler 26 is circulated in the jacket tank 31, the absorbing liquid 11 in the separation / regenerator 23 and Since the liquid carbon dioxide 13 can be maintained at a predetermined temperature, vaporization of the liquid carbon dioxide 13 can be reliably prevented, and the separation regenerator 23 does not need to be enlarged.

The invention according to claim 3 is the invention according to claim 1, and further, as shown in FIG. 4, the cooler 26 is provided inside the cooling coil 61 spirally provided in the separation chamber 23 b of the separation regenerator 23. The cooling liquid discharged from the tank is configured to circulate.
In the separation / regeneration apparatus for absorbing liquid and liquid carbon dioxide described in claim 3, when the cooling liquid discharged from the cooler 26 is circulated inside the cooling coil 61, the absorbing liquid 11 in the separation / regenerator 23 and Since the liquid carbon dioxide 13 can be maintained at a predetermined temperature more efficiently than the jacket tank of the second aspect, vaporization of the liquid carbon dioxide 13 can be prevented more reliably.

As shown in FIGS. 1 and 3, the invention according to claim 6 compresses a mixed gas containing carbon dioxide gas and a non-acidic gas so as to contact the absorbing liquid 11, thereby converting the carbon dioxide gas into the absorbing liquid 11. The absorption device 12 to be absorbed and the absorption liquid 11 discharged from the absorption device 12 and absorbing the carbon dioxide gas are cooled to separate the carbon dioxide gas as liquid carbon dioxide 13 and to regenerate the absorption liquid 11. A gas purification device comprising the separation and regeneration device 14 according to any one of the above items.
In the gas purification apparatus according to the sixth aspect, since the separation and regeneration apparatus 14 according to any one of the first to fifth aspects can be reduced in size, the gas purification apparatus 10 can also be configured to be relatively compact. Further, since the carbon dioxide gas absorbed in the absorbing liquid 11 by the separation / regeneration device 14 can be efficiently separated as the liquid carbon dioxide 13, the gas purification device 10 is used to remove carbon dioxide from a mixed gas containing carbon dioxide gas and non-acidic gas. Carbon gas can be efficiently separated as liquid carbon dioxide 13.

As shown in FIG. 5, the invention according to claim 7 reforms one or more fuels selected from the group consisting of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas. After CO modification and CO removal to obtain a mixed gas of H ₂ and CO ₂ , this mixed gas is separated and recovered into H ₂ and liquid CO ₂ using the purifier according to claim 6, and further separated. This is a system for supplying recovered H ₂ to a hydrogen station.
In the system according to the seventh aspect, CO ₂ can be efficiently recovered while producing high-pressure H ₂ from various fuels.

As shown in FIG. 6, the invention according to claim 8 is mounted on an on-vehicle reforming type vehicle using a fuel cell as a driving source, and is made of desulfurized gasoline, naphtha, kerosene, methanol, dimethyl ether, liquefied petroleum gas, and natural gas. 7. One or more kinds of fuel selected from the group consisting of reforming, CO modification and CO removal on a vehicle to form a mixed gas of H ₂ and CO ₂ , and then the mixed gas is described in claim 6. This is a system that separates and collects H ₂ and liquid CO ₂ using a purification apparatus, supplies the separated and collected H ₂ to the fuel cell, and stores the liquid CO ₂ in a storage container.
In the system according to the eighth aspect of the present invention, the system can be miniaturized to the 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.

According to the present invention, the cooler absorbs the carbon dioxide gas-absorbed absorption liquid to form a liquid liquid dispersion in which the liquid carbon dioxide is dispersed in the form of free droplets, and the separation / regenerator is liquidized from the absorption liquid cooled by the cooler. Since the carbon dioxide is separated and the absorbing liquid is regenerated, the buffer tank connected to the upper part of the separation regenerator is separated in the separation regenerator and vaporizes part or all of the liquid carbon dioxide entering the tank. Even if pressure fluctuation occurs in the state where the separation regenerator is filled with the absorption liquid and liquid carbon dioxide, the pressure of the absorption liquid and liquid carbon dioxide in which the carbon dioxide gas in the buffer tank is filled in the separation regenerator Absorb fluctuations and reduce. As a result, the pressure of the absorption liquid and the liquid carbon dioxide in the separation / regenerator can be stably maintained, so that a decrease in the phase separation efficiency of the absorption liquid and the liquid carbon dioxide due to the pressure fluctuation in the separation / regeneration unit can be prevented.
In addition, a separator plate extending in the vertical direction in the separation regenerator divides the separation regenerator into a separation chamber and a stationary chamber, and an upper communication hole and a lower communication hole formed in the separation plate are provided in the separation chamber. And the stationary chamber communicate with each other at the top and bottom, and the separation promoting part provided in the center of the separation chamber captures and aggregates the liquid carbon dioxide in the form of free droplets dispersed in the absorption liquid, so that absorption Liquid carbon dioxide can be rapidly phase-separated from the liquid. Further, even if the phase-separated absorption liquid and liquid carbon dioxide flow into the stationary chamber partitioned by the separator, almost no convection occurs in the absorption liquid and liquid carbon dioxide. Carbon dioxide is not remixed in the stationary chamber, and the absorbing liquid and liquid carbon dioxide in the stationary chamber are not refluxed to the separation chamber. As a result, even if the separation / regenerator is relatively small, liquid carbon dioxide can be efficiently separated from the absorbent in the separation / regeneration unit.

Further, if the cooling liquid is configured to flow inside the jacket tank provided so as to surround the outer peripheral surface of the separation regenerator, the absorption liquid and liquid carbon dioxide in the separation regenerator can be maintained at a predetermined temperature. Liquid carbon dioxide can be reliably prevented from being vaporized, and the separation regenerator does not need to be enlarged.
Further, if the cooling liquid is configured to circulate inside the cooling coil spirally provided in the separation chamber of the separation regenerator, the absorption liquid and the liquid carbon dioxide in the separation regenerator are more efficiently given to the predetermined tank tank than the jacket tank. Since the temperature can be maintained, vaporization of liquid carbon dioxide can be more reliably prevented.
In addition, the gas purification device compresses the mixed gas containing carbon dioxide gas and non-acidic gas and contacts the absorption liquid to absorb the carbon dioxide gas into the absorption liquid, and the carbon dioxide discharged from the absorption apparatus Since the separation / regeneration device can be miniaturized by cooling the absorption liquid that has absorbed the gas and separating the carbon dioxide gas as liquid carbon dioxide and regenerating the absorption liquid, the gas purification apparatus can be reduced in size. Since the carbon dioxide gas absorbed in the absorption liquid by the separation / regeneration device can be efficiently separated as liquid carbon dioxide while being able to be configured relatively compactly, mixing containing carbon dioxide gas and non-acidic gas using a gas purification device Carbon dioxide gas can be efficiently separated from gas as liquid carbon dioxide.

The fuel is reformed, CO converted and CO removed to form a mixed gas of H ₂ and CO ₂ , and then the mixed gas is separated and recovered into H ₂ and liquid CO ₂ using the above-described gas purification apparatus. By supplying the separated and recovered H ₂ to the hydrogen station and producing dry ice by adiabatic expansion of the separated and collected liquid CO ₂ , CO ₂ is efficiently produced while producing high-pressure H ₂ from various fuels. It can be recovered well.
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 , If this mixed gas is separated and recovered into H ₂ and liquid CO ₂ using the above gas purification apparatus, and further, the separated and recovered H ₂ is supplied to the fuel cell and the liquid CO ₂ is accommodated in a storage container, It can be made small enough to be mounted on a 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. 3, the gas purification device 10 includes an absorption device 12 that absorbs carbon dioxide gas into the absorption liquid by compressing a mixed gas containing carbon dioxide gas and a non-acidic gas and bringing the mixed gas into contact with the absorption liquid. And a separation / regeneration device 14 for cooling the absorption liquid discharged from the absorption device 12 and absorbing the carbon dioxide gas to separate the carbon dioxide gas as liquid carbon dioxide and regenerating the absorption liquid. The absorption device 12 includes a compressor 16 that compresses a mixed gas containing carbon dioxide gas and non-acidic gas, a vertically extending mixed gas supplied to the lower portion, and an upper portion supplied with an absorbing liquid. An absorption tower 17 is provided that absorbs carbon dioxide gas into the absorption liquid by bringing the mixed gas into contact with the absorption liquid and separates and recovers the non-acidic gas from the carbon dioxide gas. 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 .

Moreover, an absorption liquid is an ionic liquid or a composition which has this as a main component, and an 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. In addition, as an absorption liquid, you may use the liquid which consists of any one or both of an organic solvent or water, or the liquid which has any one or both of an organic solvent or water as a main component. As the organic solvent, it is preferable to use a polar organic solvent that has a large absorption capacity for carbon dioxide gas, has a large density difference from liquid carbon dioxide, has a low vapor pressure, and does not mutually dissolve in liquid carbon dioxide. Specifically, the organic solvent is preferably one or more polymers selected from the group consisting of polyethylene glycol, polyvinyl alcohol, polyether, polyester, polyalkane and polyolefin ion. On the other hand, water has a relatively large absorption capacity for carbon dioxide gas, has a relatively large density difference from liquid carbon dioxide, has a relatively low vapor pressure, and does not dissolve much with liquid carbon dioxide.

  The compressor 16 is provided in a gas supply pipe 18 connected to the lower side surface of the absorption tower 17, and a precooler 19 is provided in the gas supply pipe 18 between the compressor 16 and the absorption tower 17 (FIG. 3). . The mixed gas is supplied to the lower part of the absorption tower 17 by the compressor 16 and the precooler 19 while being maintained at a predetermined temperature and a predetermined pressure, respectively. Specifically, the temperature of the mixed gas supplied to the absorption tower 17, that is, the temperature in the absorption tower 17 is set to 0 to 100 ° C., preferably 30 to 50 ° C. The pressure, that is, the pressure in the absorption tower 17 is set to 4 to 25 MPa, preferably 6 to 10 MPa. Although the absorption tower 17 may be an absorption drum, it is desirable to use a multistage absorption tower 17 in order to improve the absorption efficiency of carbon dioxide gas. One end of a non-acidic gas discharge pipe 21 is connected to the upper end of the absorption tower 17, and one end of a communication pipe 22 is connected to the lower end of the absorption tower 17. The other end of the communication pipe 22 is connected to a separation regenerator 23 described later, and a heat exchanger 24 is provided in the communication pipe 22. The heat exchanger 24 accommodates the first circulation part 24a formed in a meandering tubular shape through which the absorption liquid discharged from the absorption tower 17 and absorbing the carbon dioxide gas flows, and the first circulation part 24a in a liquid-tight state. And a second distribution part 24b. In this heat exchanger 24, the absorption liquid discharged from the absorption tower 17 and absorbing the carbon dioxide gas passes through the first circulation part 24a, and the absorption liquid discharged from the lower end of the separation regenerator 23 passes through the second circulation part 24b. By passing, the absorption liquid discharged from the absorption tower 17 and absorbing the carbon dioxide gas is cooled, and the absorption liquid discharged from the lower end of the separation regenerator 23 is heated.

  On the other hand, as shown in FIGS. 1 and 2, the separation / regeneration device 14 cools the absorption liquid 11 that has absorbed the carbon dioxide gas to form the absorption liquid 11 in which the liquid carbon dioxide 13 in the form of free droplets is dispersed. 26, a separation regenerator 23 that separates the liquid carbon dioxide 13 from the absorption liquid 11 cooled by the cooler 26 and regenerates the absorption liquid 11, and a separation regenerator 23 that is connected to the upper part of the separation regenerator 23. A buffer tank 27 that vaporizes a part or all of the liquid carbon dioxide 13 that has entered after being separated. The cooler 26 is provided in the communication pipe 22 between the first circulation part 24 a of the heat exchanger 24 and the separation regenerator 23. The cooler 26 includes a meandering-tube cooled liquid circulation part 26a through which the absorption liquid 11 that has absorbed carbon dioxide gas flows, and a refrigerant circulation part that accommodates the cooled liquid circulation part 26a in a liquid-tight state and through which refrigerant flows. 26b. One end of the refrigerant supply pipe 28 is connected to the upper part on one end side of the refrigerant circulation portion 26b, and the other end of the refrigerant supply pipe 28 is connected to a refrigerant tank (not shown). One end of the refrigerant communication pipe 29 is connected to the lower part on the other end side of the refrigerant circulation portion 26b. Examples of the refrigerant include water, alcohol, ethylene glycol aqueous solution, and the like. The cooler 26 absorbs the carbon dioxide gas by indirectly contacting the coolant with the absorbent 11 that has been discharged from the first flow part 24a of the heat exchanger 24 and absorbed the carbon dioxide gas. 11 is configured to cool. A jacket tank 31 is provided on the outer peripheral surface of the separation / regenerator 23 so as to surround the outer peripheral surface. The other end of the refrigerant communication pipe 29 is connected to the lower part of the jacket tank 31, and one end of the refrigerant discharge pipe 32 is connected to the upper part of the jacket tank 31. The refrigerant that has flowed through the refrigerant flow portion 26 b of the cooler 26 is configured to be discharged from the refrigerant discharge pipe 32 after flowing through the inside of the jacket tank 31 through the cooling communication pipe 29.

  The absorption liquid 11 that has absorbed the carbon dioxide gas is supplied to the separation regenerator 23 in a state where the absorption liquid 11 that has absorbed the carbon dioxide gas is kept substantially the same as the pressure in the absorption tower 17 and cooled to a temperature lower than the temperature in the absorption tower 17. (FIGS. 1-3). Specifically, the pressure of the absorption liquid 11 supplied to the separation regenerator 23, that is, the pressure in the separation regenerator 23 is the same as the pressure in the absorption tower 17, and a pressure slightly higher than the pressure in the absorption tower 17. Alternatively, the pressure of 4 to 25 MPa, preferably 6 to 10 MPa, which is slightly lower than the pressure in the absorption tower 17, and the temperature of the absorption liquid 11 supplied to the separation regenerator 23, that is, the temperature in the separation regenerator 23 is It is set to −30 to 30 ° C., preferably 0 to 20 ° C., more preferably 0 to 10 ° C., which is lower than the temperature in the absorption tower 17. Further, by circulating the refrigerant in the jacket tank 31, the temperature in the separation regenerator 23 is reliably maintained at the above-described -30 to 30 ° C, preferably 0 to 20 ° C. Here, the pressure in the separation regenerator 23 is 4 to 25 MPa, which is the same pressure as the pressure in the absorption tower 17, a pressure slightly higher than the pressure in the absorption tower 17, or a pressure slightly lower than the pressure in the absorption tower 17. The reason for limiting to this range is to liquefy the carbon dioxide gas and to reduce the consumption of circulating energy of the absorbing liquid 11. Further, the temperature in the separation / regenerator 23 is limited to the range of -30 to 30 ° C because the cooling energy increases and the fluidity of the absorbing solution decreases when the temperature is lower than -30 ° C. This is because it becomes difficult for the carbon gas to become liquid carbon dioxide 13 in the form of free droplets. Note that when the pressure in the separation regenerator 23 is made higher than the pressure in the absorption tower 17, the pressure difference is 0.1. It is preferable that the pressure in the separation regenerator 23 is lower than the pressure in the absorption tower 17, and the pressure difference causes the carbon dioxide gas to be converted into free liquid droplets of liquid carbon dioxide due to the temperature drop. It is preferable to be within a range of 0.1 to 3 MPa, which can be 13.

The separation regenerator 23 is formed in a cylindrical shape extending in the vertical direction, and a separating plate 23 a is provided in the separation regenerator 23 so as to extend in the vertical direction. The separation plate 23a partitions the separation / regenerator 23 into a separation chamber 23b and a stationary chamber 23c. An upper communication hole 23d is formed in the upper part of the separator plate 23a, and a lower communication hole 23e is formed in the lower part of the separator plate 23a. The upper communication hole 23d allows the separation chamber 23b and the stationary chamber 23c to communicate with each other in the upper part of the separation / regenerator 23, and the lower communication hole 23e allows the separation chamber 23b and the stationary chamber 23c to communicate with each other at the lower part of the separation / regenerator 23. Configured as follows. Further, a separation promoting portion 23f is provided in the center of the separation chamber 23b. The separation accelerating portion 23f includes a pair of partition plates 23g and 23g formed by a predetermined mesh wire netting, a punching metal plate or the like and fixed to the separator plate 23a with a predetermined interval in the vertical direction, and these partition plates. The separation promoting chamber 23h divides the separation chamber 23b by 23g and 23g, and a filler 23i made of resin fiber or stainless wool filled in the separation promoting chamber 23h. The pair of partition plates 23g and 23g are configured such that the absorbing liquid 11 and the liquid carbon dioxide 13 can pass therethrough and the filling material 23i cannot pass through. Here, when the height of the separator 23a and H, the height H ₁ of the upper hole 23d is (0.05 to 0.3) H, set to preferably (0.1 to 0.2) H The height H ₂ of the lower communication hole 23e is set to (0.05 to 0.3) H, preferably (0.1 to 0.2) H, and the distance H between the pair of partition plates 23g and 23g. ₃ is set to (0.1 to 0.4) H, preferably (0.2 to 0.3) H. Here, the reason why the height H ₁ of the upper communication hole 23d is limited to the range of (0.05 to 0.3) H is that if it is less than 0.05H, the flowability of the liquid carbon dioxide is reduced. This is because the isolation effect between the separation chamber 23b and the stationary chamber 23c is lowered when the temperature exceeds 3H. Further, the reason why the height H ₂ of the lower communication hole 23e is limited to the range of (0.05 to 0.3) H is that if it is less than 0.05H, the flowability of liquid carbon dioxide decreases, and 0.3H This is because the separation effect between the separation chamber 23b and the stationary chamber 23c is reduced. Further, the distance H ₃ between the pair of partition plates 23g and 23g is limited to the range of (0.1 to 0.4) H. If the distance H is less than 0.1H, the separation promotion is insufficient. This is because the extra volume increases.

  Examples of the filling material 23i include hydroxyl group, carboxyl group, oxy group, epoxy group, glycidyl group, oxycarbonyl group, carbonyloxy group, carbonyl group, amino group, ester group, halogen group, cyano group, amide group, imide group, Examples thereof include resin fibers having a polarity such as a sulfonyl group, resin fibers having no polarity such as styrene and olefin, and stainless wool. The filling 23i has an average diameter of 100 to 1000 μm, preferably 200 to 500 μm, and the filling 23i is filled so as to have a large number of communicating gaps throughout the separation promoting chamber 23h. Here, the reason why the average diameter of the packing material 23i is limited to the range of 100 to 1000 μm is that if it is less than 100 μm, the pressure loss during distribution increases, and if it exceeds 1000 μm, the effect of promoting separation is reduced.

  On the other hand, the buffer tank 27 is connected to the upper surface on the separation chamber 23 b side of the separation regenerator 23 through a short tube 34, and a part or all of the liquid carbon dioxide 13 in the buffer tank 27 is vaporized on the outer peripheral surface of the buffer tank 27. Heating means 36 are provided. The heating means 36 is a heater in this embodiment. The volume of the buffer tank 27 is set to 5 to 50% by volume, preferably 10 to 30% by volume, of the separation regenerator 23. Here, the volume of the buffer tank 27 is limited to the range of 5 to 50% by volume of the separation regenerator 23. If the volume is less than 5% by volume, the pressure fluctuation in the separation regenerator 23 cannot be sufficiently suppressed. This is because if the volume exceeds 50% by volume, the buffer tank 27 will be unnecessarily large and the manufacturing cost will increase. The temperature inside the buffer tank 27 is a temperature at which the inside of the buffer tank 27 is maintained in a low-density carbon dioxide gas phase by the heater 36, that is, a temperature higher than the critical temperature of carbon dioxide, specifically 35-100 ° C., preferably Maintained at 40-80 ° C.

  One end of a carbon dioxide discharge pipe 37 for discharging the liquid carbon dioxide 13 separated from the absorbing liquid 11 is connected to the upper surface of the separation regenerator 23 on the stationary chamber 23c side, and the separation regenerator 23 on the stationary chamber 23c side is connected. One end of an absorption liquid return pipe 38 for returning the regenerated absorption liquid 11 from the liquid carbon dioxide 13 to the absorption tower 17 is connected to the lower surface, and absorption is performed on the lower side surface of the separation regenerator 23 on the stationary chamber 23c side. One end of an absorption liquid supply pipe 39 for supplying the liquid 11 into the stationary chamber 23c is connected. The other end of the absorption liquid return pipe 38 is connected to the upper side surface of the absorption tower 17, and the second flow part 24 b of the heat exchanger 24 is connected to the absorption liquid return pipe 38. The carbon dioxide discharge pipe 37 is provided with an upper flow rate adjustment valve 41, and a pressure sensor 42 is connected to the upper surface of the buffer tank 27. The detection output of the pressure sensor 42 is connected to the control input of the pressure controller 43, and the control output of the pressure controller 43 is connected to the upper flow rate adjustment valve 41. Further, the absorbent replenishment pipe 39 is provided with a lower flow rate adjustment valve 44, and a liquid level sensor 46 is connected to the center of the separation regenerator 23 on the stationary chamber 23c side. The detection output of the liquid level sensor 46 is connected to the control input of the liquid level controller 47, and the control output of the liquid level controller 47 is connected to the lower flow rate adjustment valve 44. 3 is a circulation pump that circulates the absorption liquid to the absorption tower 17, the heat exchanger 24, and the separation regenerator 23.

A method for purifying a gas using the purification apparatus 10 and the separation / regeneration apparatus 14 configured as described above will be described.
Before supplying the mixed gas to the absorption tower 17, the circulation pump 48 is operated in advance, and a refrigerant such as water, alcohol, ethylene glycol aqueous solution is passed through the precooler 19 and the cooler 26 to circulate the absorption liquid, The temperature of the absorption liquid supplied to the absorption tower 17 and the separation regenerator 23 is set to a predetermined temperature. First, the mixed gas is heated or cooled to a predetermined temperature by the compressor 16 and the precooler 19 and is supplied to the lower part of the absorption tower 17 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 carbon dioxide gas is absorbed by the absorbing liquid, so that the non-acidic gas is separated from the carbon dioxide gas and recovered from the upper end of the absorption tower 17 through the non-acidic gas discharge pipe 21. Is done. When the pressure of the recovered non-acid gas is higher than the pressure required on the user side, for example, the non-acid gas (H ₂ , CH ₄ , CO, O ₂ , N ₂ , hydrocarbon compound having 2 to 10 carbon atoms) When the gas mixture is used in a gas turbine, the non-acid gas is once decompressed using an expansion turbine or an adiabatic expansion valve.

  On the other hand, the absorption liquid discharged from the lower end of the absorption tower 17 and absorbing the carbon dioxide gas is cooled by the regenerated absorption liquid 11 by the heat exchanger 24 and further cooled by the cooler 26. At this time, the carbon dioxide gas in the absorbing liquid becomes free droplet-like liquid carbon dioxide and is dispersed in the absorbing liquid. The absorbing liquid containing the liquid carbon dioxide in the form of free droplets is supplied into the separation promoting chamber 23h of the separation regenerator 23. At this time, the filling material 23i in the separation promoting chamber 23h captures and aggregates the liquid droplets of the liquid droplets dispersed in the absorption liquid so that the liquid carbon dioxide 13 is rapidly separated from the absorption liquid 11. it can. The liquid carbon dioxide 13 passes through the pores of the upper partition plate 23g, rises in the separation chamber 23b, and flows into the stationary chamber 23c through the upper communication hole 23d. The absorbing liquid 11 passes through the pores of the lower partition plate 23g, descends in the separation chamber 23b, and flows into the stationary chamber 23c through the lower communication hole 23e. Since almost no convection occurs in the absorbing liquid 11 and the liquid carbon dioxide 13 in the stationary chamber 23c, the absorbing liquid 11 and the liquid carbon dioxide 13 are not remixed in the stationary chamber 23c, and the stationary chamber 23c. The absorption liquid 11 and the liquid carbon dioxide 13 inside are not refluxed to the separation chamber. As a result, the liquid carbon dioxide 13 can be separated efficiently from the absorbent 11 in the separation / regenerator 23.

  Further, even if pressure fluctuation occurs in the absorption liquid 11 and the liquid carbon dioxide 13 in the separation regenerator 23, the absorption liquid 11 and the liquid carbon dioxide 13 in which the carbon dioxide gas in the buffer tank 27 is filled in the separation regenerator 23. Absorbs and reduces pressure fluctuations. As a result, the pressures of the absorption liquid 11 and the liquid carbon dioxide 13 in the separation / regenerator 23 can be stably maintained. Can be prevented. Moreover, since the refrigerant | coolant discharged | emitted from the refrigerant | coolant distribution part 26b of the cooler 26 distribute | circulates the inside of the jacket tank 31, the absorption liquid 11 and the liquid carbon dioxide 13 in the separation regenerator 23 are further -30-30 degreeC, Preferably it is 0 It can be maintained at -20 ° C, more preferably 0-10 ° C, and the vaporization of the liquid carbon dioxide 13 in the separation regenerator 23 can be reliably prevented. In addition, since the thickness of the jacket tank 31 is relatively thin, it is not necessary to increase the size of the separation / regenerator 23.

  The liquid carbon dioxide 13 in the stationary chamber 23 c is exhausted through the carbon dioxide exhaust pipe 37. Specifically, although the pressure fluctuation in the separation regenerator 23 is absorbed by the buffer tank 27, the pressure controller 43 performs pressure adjustment while maintaining the pressure in the separation regenerator 23 and the buffer tank 27 at a predetermined pressure. The liquid carbon dioxide 13 is discharged from the stationary chamber 23 c through the carbon dioxide discharge pipe 37 by adjusting the opening of the upper flow rate adjustment valve 41 based on the detection output of the sensor 42. The absorbent 11 in the stationary chamber 23 c is returned to the absorption tower 17 by the circulation pump 48 through the absorbent return pipe 38 and the second circulation part 24 b of the heat exchanger 24. Since the liquid carbon dioxide 13 discharged from the stationary chamber 23c through the carbon dioxide discharge pipe 37 contains a slight amount of the absorbing liquid 11, the liquid level of the absorbing liquid 11 in the stationary chamber 23c gradually decreases. . For this reason, when the liquid level sensor 46 detects that the liquid level of the absorbing liquid 11 has decreased by a predetermined amount from the set liquid level, the liquid level controller 47 sets the lower flow rate adjustment valve 44 to a predetermined level based on the detection output of the liquid level sensor 46. It opens at the opening and replenishes the absorbing liquid 11 to the stationary chamber 23c. When the liquid level sensor 46 detects that the liquid level of the absorbing liquid 11 in the stationary chamber 23c has risen to the set liquid level, the liquid level controller 47 controls the lower flow rate adjustment valve based on the detection output of the liquid level sensor 46. 44 is closed.

<Second Embodiment>
FIG. 4 shows a second embodiment of the present invention. 4, the same reference numerals as those in FIG. 1 denote the same components.
In this embodiment, a cooling coil 61 is provided in the separation chamber 23b of the separation regenerator 23 in place of the jacket tank of the first embodiment. The lower end of the cooling coil 61 is connected to the other end of the refrigerant communication pipe 29, and the upper end of the cooling coil 61 is connected to one end of the refrigerant discharge pipe 32. The configuration other than the above is the same as that of the first embodiment.
In the purification apparatus and the separation / regeneration apparatus configured as described above, the absorption liquid 11 and the liquid carbon dioxide 13 in the separation / regenerator 23 are more efficiently heated to a predetermined temperature, that is, −30 to 30 than the jacket tank of the first embodiment. Since it can maintain at 0 degreeC, Preferably it is 0-20 degreeC, More preferably, it is 0-10 degreeC, Therefore The vaporization of the liquid carbon dioxide 13 can be prevented further reliably. Since the operation other than the above is substantially the same as the operation of the first embodiment, repeated description will be omitted.

<Third Embodiment>
FIG. 5 shows a third embodiment of the present invention.
In this embodiment, after the fuel is reformed, CO-modified, and CO removed to form a mixed gas of H ₂ and CO ₂ , this mixed gas is used in the gas purification apparatus of the first and second embodiments. The H ₂ and liquid CO ₂ are separated and recovered, and the separated and recovered H ₂ is supplied to the hydrogen station, and the separated and recovered liquid CO ₂ is adiabatically expanded to produce dry ice (solid CO ₂ ). Configured as follows. 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. And the remaining mixed gas of H ₂ and CO ₂ is separated into the high pressure H ₂ and liquid CO ₂ using the apparatus for purifying gas in the first and second embodiments. 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 the recovery of liquid CO _2, by adiabatic expansion of part or all of the recovered liquid CO ₂ at the opening of the pressure reducing valve can be produced salable dry ice as a product.

<Fourth embodiment>
FIG. 6 shows a fourth embodiment of the present invention.
In this embodiment, after reforming the fuel on the vehicle, CO conversion and CO removal to obtain a mixed gas of H ₂ and CO ₂ , this mixed gas is used for the gas of the first and second embodiments. A system that separates and collects H ₂ and liquid CO ₂ using a refining device and supplies the separated and collected H ₂ to the fuel cell is mounted on an on-vehicle reforming vehicle that uses the fuel cell as a drive source. . 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 the apparatus for purifying gas in the first and second embodiments. Further, the high pressure H ₂ is supplied to the fuel cell, and the liquid CO ₂ is stored in the storage container. 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.

Next, examples of the present invention will be described in detail together with comparative examples.
<Example 1>
As shown in FIGS. 1 and 2, a separation / regeneration device 14 including a cooler 26, a separation / regeneration unit 23 having a capacity of 5 liters, and a buffer tank 27 having a capacity of 0.5 liters was used. Further, 1-butyl-3-methylimidazolium hexafluorophosphate was used as the absorbing liquid 11, and the separation promoting chamber 23f of the separation regenerator 23 was filled with a packing material 23i made of stainless wool having an average diameter of 300 μm. Further, the height H of the separator plate 23a is 1000 mm, the height of the upper communication hole 23d is 150 mm (0.15H), the height of the lower communication hole 23e is 150 mm (0.15H), and a pair of partitions The distance between the plates 23g and 23g was 200 mm (0.2H). The absorbing liquid return pipe 38 was connected to the communication pipe 22 through a circulation pump (not shown), and the absorbing liquid 11 was circulated. This separation / reproduction device 14 was referred to as Example 1.
<Comparative Example 1>
The same separation and regeneration apparatus as in Example 1 was used except that the separation promoting chamber of the separation and regenerator was not filled with a filler. This separation and regeneration apparatus was designated as Comparative Example 1.

<Comparative test 1 and evaluation>
After absorbing 0.3 mol of carbon dioxide gas with respect to 1 mol of the absorbing solution, the absorbing solution that absorbed the carbon dioxide gas was supplied to the coolers of Example 1 and Comparative Example 1. Moreover, the cooling liquid which absorbed the carbon dioxide gas by these cooling was cooled to 10 degreeC, and each was supplied to the separation regenerator.
As a result, in the apparatus of Comparative Example 1, it took a relatively long time of 10 minutes to separate the absorbing liquid and the liquid carbon dioxide, but in the apparatus of Example 1, the absorbing liquid and the liquid carbon dioxide were reduced to 0. Separation was possible in an extremely short time of 5 minutes.

1 is a configuration diagram of an absorption liquid and liquid carbon dioxide separation / regeneration apparatus according to a first embodiment of the present invention. FIG. It is a principal part perspective view which shows the state in the separation regenerator of the separation reproduction | regeneration apparatus. It is a block diagram of the refiner | purifier of the gas using the separation / regeneration apparatus. It is a block diagram of the separation / regeneration apparatus of the absorption liquid and liquid carbon dioxide of 2nd Embodiment of this invention. It is a block diagram which shows the system using the refiner | purifier of the gas of 3rd Embodiment of this invention. It is a block diagram which shows the system using the refiner | purifier of the gas of 4th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Gas purification apparatus 11 Absorption liquid 12 Absorption apparatus 13 Liquid carbon dioxide 14 Separation / regeneration apparatus 23 Separation / regeneration unit 23a Separating plate 23b Separation chamber 23c Standing chamber 23d Upper communication hole 23e Lower communication hole 23f Separation promotion part 23i Filler 26 Cooling Equipment 27 Buffer tank 31 Jacket tank 61 Cooling coil

Claims (8)

A cooler that cools the absorption liquid that has absorbed carbon dioxide gas to form an absorption liquid in which liquid carbon dioxide in the form of free droplets is dispersed;
A separation regenerator for separating the liquid carbon dioxide from the absorption liquid cooled by the cooler and regenerating the absorption liquid;
A separation / regeneration apparatus comprising a buffer tank connected to an upper part of the separation / regenerator and vaporizing part or all of the liquid carbon dioxide separated and entered in the separation / regenerator,
An upper communication hole which extends in the vertical direction in the separation regenerator, divides the inside of the separation regenerator into a separation chamber and a stationary chamber, and communicates the separation chamber and the stationary chamber with an upper portion and a lower portion, respectively; A separator formed with a lower communication hole;
An absorption liquid and liquid carbon dioxide, comprising: a separation promoting part that is provided in the center of the separation chamber and captures, aggregates, and coarsens the liquid carbon dioxide in the form of free droplets dispersed in the absorption liquid Separation and regeneration device.   The apparatus for separating and regenerating an absorbing liquid and liquid carbon dioxide according to claim 1, wherein the cooling liquid discharged from the cooler is circulated in a jacket tank provided so as to surround the outer peripheral surface of the separating and regenerator.   The apparatus for separating and regenerating an absorbing liquid and liquid carbon dioxide according to claim 1, wherein the cooling liquid discharged from the cooler circulates inside a cooling coil spirally provided in the separation chamber of the separation regenerator. The apparatus for separating and regenerating an absorbent and liquid carbon dioxide according to claim 1, wherein the separation promoting part is filled with a filler made of resin fibers or stainless wool having an average diameter of 100 to 1000 µm.
  The apparatus for separating and regenerating an absorbent and liquid carbon dioxide according to claim 1, wherein the absorbent is one of an ionic liquid, an organic solvent, and water.   An absorption device that absorbs carbon dioxide gas into the absorption liquid by compressing a mixed gas containing carbon dioxide gas and a non-acidic gas and bringing it into contact with the absorption liquid, and absorption that absorbs the carbon dioxide gas discharged from the absorption apparatus A gas purification apparatus comprising the separation and regeneration device according to any one of claims 1 to 5, wherein a liquid is cooled to separate the carbon dioxide gas into liquid carbon dioxide and the absorbent is regenerated. One 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 modified and CO removed to mix H ₂ and CO ₂ A system in which the mixed gas is separated and recovered into H ₂ and liquid CO ₂ by using the purifier described in claim 6 after the gas is formed, and the separated and recovered H ₂ is supplied to the hydrogen station. 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. After reforming, CO modification and CO removal on the vehicle to form a mixed gas of H ₂ and CO ₂ , this mixed gas is separated and recovered into H ₂ and liquid CO ₂ using the purifier described in claim 6. Further, a system for supplying the separated and recovered H ₂ to the fuel cell and storing the liquid CO ₂ in a storage container.

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