Gas separation system

Abstract

This gas separation system (1) separates NH3 from a mixed gas containing NH3, CO2 and N2. The gas separation system (1) comprises a first separation membrane (10) and a second separation membrane (20) disposed downstream from the first separation membrane (10). The first separation membrane (10) selectively allows NH3 to pass therethrough, thereby producing a first enriched gas that is enriched in NH3 and a first poor gas that is poor in NH3 and enriched in CO2 and N2. The second separation membrane (20) separates out the CO2, thereby producing a second enriched gas that is enriched in CO2 and a second poor gas that is poor in CO2.

Description

Gas Separation Systems

[0001] The present invention relates to a gas separation system.

[0002] Conventionally, methods for separating a specific component contained in a mixed gas have been known that combine pressure swing adsorption (PSA), temperature swing adsorption (TSA), or absorption methods with a separator using a membrane separation method or the like (for example, Patent Document 1).

[0003] The technique described in Patent Document 1 involves separating a mixed gas into an exhaust gas (hydrogen sulfide, water vapor, and heavy hydrocarbons) and a concentrated gas (carbon dioxide and light hydrocarbons) in an adsorption tower, and then separating the concentrated gas into carbon dioxide and light hydrocarbons using a separation membrane.

[0004] According to the technique described in Patent Document 1, hydrogen sulfide and water vapor can be separated as exhaust gas (impurities). Hydrogen sulfide and water vapor are each a type of degradative gas. Degradative gas is a general term for gases that are corrosive to metals, gases that cause metal embrittlement, and gases that exhibit basicity when dissolved in water.

[0005] US Patent Application Publication No. 2009 / 0151562

[0006] However, since the pressure and temperature of the enriched gas flowing out of the adsorption tower or absorption tower are prone to fluctuations, it is necessary to constantly monitor and control the pressure and temperature of the enriched gas supplied to a separator such as a separation membrane, which is cumbersome.

[0007] An object of the present invention is to provide a gas separation system that can easily separate degrading gases.

[0008] A gas separation system according to a first aspect of the present invention is a gas separation system for separating a depleted gas from a mixed gas containing a depleted gas, a first non-depleted gas, and a second non-depleted gas. The gas separation system includes a first separation membrane and a separator disposed downstream of the first separation membrane. The first separation membrane selectively allows the depleted gas to permeate, thereby producing a first enriched gas enriched in the depleted gas, and a first depleted gas depleted in the depleted gas and enriched in the first and second non-depleted gases. The separator separates the first non-depleted gas, thereby producing a second enriched gas enriched in the first non-depleted gas, and a second depleted gas depleted in the first non-depleted gas.

[0009] A gas separation system according to a second aspect of the present invention is related to the first aspect, and the separator is a second separation membrane that selectively allows the first non-degrading gas to permeate.

[0010] A gas separation system according to a third aspect of the present invention is related to the second aspect, and the configuration of the second separation membrane is different from the configuration of the first separation membrane.

[0011] A gas separation system according to a fourth aspect of the present invention relates to any one of the first to third aspects, and the concentration of degrading gas in the gas supplied to the separator is lower than the concentration of degrading gas in the gas supplied to the first separation membrane.

[0012] A gas separation system according to a fifth aspect of the present invention is the gas separation system according to any one of the first to fourth aspects, wherein the degraded gas is NH ３ is.

[0013] A gas separation system according to a sixth aspect of the present invention is the gas separation system according to any one of the first to fourth aspects, wherein the degraded gas is H ２ and the first non-degrading gas is N ２ and the second non-depleting gas is CH ４ is.

[0014] A seventh aspect of the present invention relates to the gas separation system of any one of the first to fourth aspects, wherein the degraded gas is H ２ and the first non-depleting gas is CO ２ and the second non-degrading gas is N ２ is.

[0015] A gas separation system according to an eighth aspect of the present invention is the gas separation system according to any one of the first to fourth aspects, wherein the degraded gas is H ２ and the first non-depleting gas is CO ２ and the second non-depleting gas is CH ４ and each of the first separation membrane and the separator is a zeolite membrane.

[0016] A gas separation system according to a ninth aspect of the present invention relates to any one of the first to fourth aspects, wherein the degraded gas is H ２ O, and the first non-depleting gas is CO ２ and the second non-depleting gas is CH ４ is.

[0017] A gas separation system according to a tenth aspect of the present invention relates to any one of the first to fourth aspects, wherein the degraded gas is H ２ O, and the first non-degrading gas is N ２ and the second non-depleting gas is CH ４ is.

[0018] A gas separation system according to an eleventh aspect of the present invention relates to any one of the first to fourth aspects, wherein the degraded gas is H ２ O, and the first non-depleting gas is CO ２ and the second non-degrading gas is N ２ and each of the first separation membrane and the separator is a zeolite membrane.

[0019] According to the present invention, a gas separation system capable of easily separating degrading gases can be provided.

[0020] Schematic diagram showing the configuration of a gas separation system according to an embodiment.

[0021] (Gas Separation System 1) FIG. 1 is a schematic diagram showing the configuration of a gas separation system 1. As shown in FIG.

[0022] The gas separation system 1 includes a first separation membrane 10 and a second separation membrane 20 .

[0023] The first separation membrane 10 is an example of the "first separation membrane" according to the present invention. The second separation membrane 20 is an example of the "separator" according to the present invention.

[0024] [First Separation Membrane 10] The first separation membrane 10 is disposed upstream of the second separation membrane 20. The first separation membrane 10 contains NH ３ , CO ２ and N ２ A mixed gas containing

[0025] NH ３ is an example of a "deteriorating gas" according to the present invention. ３ The kinetic diameter of CO is 0.265 nm. ２ is an example of the "first non-degrading gas" according to the present invention. ２ The kinetic molecular diameter of N is 0.33 nm. ２ is an example of the "second non-degrading gas" according to the present invention. ２ The kinetic molecular diameter of is 0.364 nm.

[0026] Deteriorating gases are a general term for gases that are corrosive to metals, gases that cause metal embrittlement, and gases that become basic when dissolved in water. ３ Gases that cause metal embrittlement include H ２ Examples of gases that show basicity when they become aqueous solutions include NH ３ In addition, from the viewpoint of being able to dissolve other components and produce an aqueous solution, H ２ O is also a degrading gas.

[0027] Non-degradable gas is a general term for gases other than degradable gases.

[0028] Although the mixed gas according to the present embodiment contains one degrading gas and two non-degrading gases, the present invention is not limited to this. The mixed gas may contain at least one degrading gas and at least two non-degrading gases. The mixing ratio of each gas in the mixed gas can be set as appropriate.

[0029] As described above, the mixed gas according to this embodiment contains NH ３and CO as a non-degrading gas. ２ and N ２ The mixed gas supplied to the first separation membrane 10 is preferably pressurized.

[0030] The first separation membrane 10 separates the degraded gas NH from the mixed gas. ３ The first separation membrane 10 separates NH from the mixed gas. ３ selectively permeable NH ３ The first separation membrane 10 is a separation membrane. ３ The constituent material of the first separation membrane 10 is not particularly limited as long as it is a membrane that can selectively permeate the above-mentioned components. For example, a zeolite membrane, a carbon membrane, a silica membrane, a synthetic resin membrane, or the like can be used as the first separation membrane 10. In particular, a zeolite membrane is preferred because it can exhibit high separation performance even under high-temperature conditions.

[0031] In this specification, selective permeation means that the desired component is enriched in the permeate side space of the separation membrane.

[0032] The first separation membrane 10 is formed by separating NH contained in the mixed gas. ３ By selectively permeating ３ a first enriched gas enriched in NH ３ is depleted and CO ２ and N ２ and a first depleted gas enriched with .

[0033] The first enriched gas is discharged to the outside from the permeate side space of the first separation membrane 10. NH ３ The concentration of the first enrichment gas is not particularly limited, but the first enrichment gas is mainly NH ３ It is preferable that the compound contains mainly NH ３ The term "containing" means that the maximum concentration component in the first enriched gas is NH ３ The first enriched gas contains CO ２ may be included.

[0034] The first lean gas flows out from the non-permeation side space of the first separation membrane 10 and is supplied to the second separation membrane 20. The first lean gas is CO ２ and N ２ The first depleted gas includes NH３ may be included.

[0035] [Second Separation Membrane 20] The second separation membrane 20 is disposed downstream of the first separation membrane 10. The second separation membrane 20 is provided with a ２ and N ２ A first depleted gas is supplied, the first gas comprising:

[0036] NH in the first depleted gas supplied to the second separation membrane 20 ３ The concentration of NH in the mixed gas supplied to the first separation membrane 10 is ３ Lower than the concentration of

[0037] The second separation membrane 20 separates the first depleted gas from the first non-depleted gas, CO ２ The second separation membrane 20 separates CO from the first depleted gas. ２ selectively permeable to CO ２ The second separation membrane 20 is a CO ２ The material of the second separation membrane 20 is not particularly limited as long as it is a membrane that can selectively permeate the above. As the second separation membrane 20, for example, a zeolite membrane, a carbon membrane, a silica membrane, a synthetic resin membrane, or the like can be used.

[0038] The configuration of the second separation membrane 20 is preferably different from the configuration of the first separation membrane 10. The second separation membrane 20 is ２ For example, the pore size of the second separation membrane 20 is ２ and N ２ It is preferable that the kinetic diameter is smaller than that of the molecular weight of the polymer.

[0039] The second separation membrane 20 separates the CO contained in the first depleted gas. ２ By selectively permeating ２ a second enriched gas enriched in CO; ２ is impoverished and N ２ and a second depleted gas enriched with .

[0040] The second enriched gas is discharged to the outside from the permeate side space of the second separation membrane 20. ２ The concentration of the second enriched gas is not particularly limited, but the second enriched gas is mainly CO ２It is preferable that the mixture contains mainly CO. ２ The term "containing" means that the maximum concentration component in the second enriched gas is CO ２ This means that

[0041] The second depleted gas is discharged to the outside from the non-permeation side space of the second separation membrane 20. ２ The concentration of the second impoverished gas is not particularly limited, but the second impoverished gas is mainly N ２ It is preferable that the compound contains mainly N. ２ The term "contains" means that the maximum concentration component in the second depleted gas is N. ２ This means that the first depleted gas is NH ３ If the second depleted gas also contains NH ３ may also include:

[0042] (Features) (1) The gas separation system 1 is ３ (first deteriorating gas), CO ２ (first non-degrading gas) and N ２ (second deteriorating gas) from a mixed gas containing NH ３ The gas separation system 1 includes a first separation membrane 10 (first separation membrane) and a second separation membrane 20 (separator) disposed downstream of the first separation membrane 10. The first separation membrane 10 separates NH ３ By selectively permeating ３ a first enriched gas enriched in NH ３ is depleted and CO ２ and N ２ The second separation membrane 20 generates a first depleted gas enriched with CO ２ By separating CO ２ a second enriched gas enriched in CO; ２ and a second depleted gas in which the first depleted gas is depleted.

[0043] In this way, according to the gas separation system 1, NH ３ is separated by a separation membrane in advance, and then CO ２ and N ２ Therefore, since the degraded gases can be separated by the separation membrane before the non-degraded gases are separated, the PSA method can separate NH ３Compared to when separating NH by temperature swing adsorption (TSA) or absorption, the gas separation system 1 can suppress pressure fluctuations in the first depleted gas supplied to the second separation membrane 20. Therefore, there is no need to perform complicated control of the pressure and temperature of the first depleted gas. In addition, it is possible to reduce the energy required to increase the pressure of the first depleted gas by the amount of pressure reduction. Furthermore, when the gas separation system 1 separates NH by temperature swing adsorption (TSA) or absorption, ３ In comparison with the case of separating the first lean gas, there is no need for complicated temperature control of the first lean gas. Furthermore, in the case of the TSA method or the absorption method, the gas temperature may be lowered to more effectively perform adsorption or absorption. Therefore, the energy required to heat the first lean gas can be reduced.

[0044] (2) The gas separation system 1 is ２ Therefore, the gas separation system 1 is provided with a second separation membrane 20 as a "separator" that selectively allows the permeation of CO ２ Compared to the case where an adsorption tower or absorption tower is provided as a separator, it is possible to accurately separate CO with a simple configuration. ２ Furthermore, since the membrane separation method is a continuous process, it is more susceptible to pressure and temperature fluctuations than the adsorption and absorption methods, which are batch processes. Therefore, when a separation membrane is used as the "separator," the effect of the present invention, which can suppress pressure and temperature fluctuations in the first depleted gas, becomes more pronounced.

[0045] The "separator" is preferably configured to be degraded by degradative gases. For example, in this embodiment, the second separation membrane 20 is NH ３ That is, the second separation membrane 20 is preferably resistant to deterioration due to NH ３ Compared to the absence of NH ３ It is preferable that the life of the catalyst be shortened in the presence of a degrading gas, and with such a configuration, the feature of the present invention of easily removing the degrading gas becomes more effective.

[0046] (3) The second separation membrane 20 preferably has a different configuration from the first separation membrane 10. This allows the first non-degrading gas, CO ２ A separation membrane suitable for separating the above can be used as the second separation membrane 20.

[0047] (4) NH in the first depleted gas (an example of the "gas supplied to the separator") ３ The concentration of NH in the mixed gas (an example of the "gas supplied to the first separation membrane") ３ This is because the concentration of CO, a non-depleted gas contained in the first depleted gas, is lower than that of CO. ２ and N ２ Before separating the degraded gas NH ３ This means that CO is removed from the first depleted gas. ２ can be separated with high accuracy.

[0048] (Modifications of the embodiment) Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.

[0049] [Modification 1] In the above embodiment, NH is used as an example of a degrading gas. ３ However, the present invention is not limited to these examples. Examples of degrading gases include NH ３ , H ２ , H ２ O and the like can be used.

[0050] Furthermore, in the above embodiment, CO is used as an example of the first non-deteriorating gas. ２ and N as an example of the second non-degrading gas. ２ However, the first and second non-degrading gases are not limited to these. ２ , N ２ , C.H. ４ etc. can be used.

[0051] Table 1 shows typical examples of combinations of the degrading gas, the first non-degrading gas, and the second non-degrading gas contained in the mixed gas.

[0052]

[0053] The combination of gases is determined depending on the composition of the mixed gas to be treated, but the gas separation system according to the present invention can be particularly effectively used in the following cases.

[0054] First, the mixed gas contains NH ３ In this case, it is preferable to include NH ３ Since the concentration of can be preferentially reduced, deterioration of the separation membrane and the device can be suppressed.

[0055] The mixed gas contains H as a degrading gas. ２ In this case, the first enriched gas preferably contains H ２ Therefore, the first enrichment gas is H ２ This makes it easier to utilize as a source of methyl methyl ether (e.g., a raw material for synthesizing MeOH).

[0056] The mixed gas contains H as a degrading gas. ２ When the first non-degrading gas contains N ２ and CH as the second non-degrading gas. ４ It is more preferable that the molecular diameter of the H ２ By first removing H, each gas separated in the latter stage ２ Since the mixing of H is suppressed, a high purity gas can be obtained. ２ Next is the inert gas N ２ By removing the non-permeable gas CH ４ The purity of CH ４ This reduces the risk of explosion.

[0057] The mixed gas contains H as a degrading gas. ２ When the first non-degrading gas contains CO ２ and N as the second non-degrading gas. ２ This allows molecules with smaller kinetic molecular diameters to be removed in order, thereby preventing these molecules from mixing with the gases separated in the subsequent stage, thereby enabling the production of high-purity gases.

[0058] Furthermore, the mixed gas contains H as a degrading gas. ２ When the first non-degrading gas contains CO ２ and CH as the second non-degrading gas. ４It is particularly preferable that the first and second separation membranes 10 and 20 each be a zeolite membrane. ２ By first removing H, each gas separated in the latter stage can be ２ Since the mixing of H is suppressed, a high purity gas can be obtained. ２ Next to CO ２ When separating CO ２ This allows for effective separation because the affinity between the catalyst and zeolite can be effectively utilized.

[0059] The mixed gas preferably contains HO as a degrading gas. In this case, by separating HO first, which has a low vapor pressure and is easily condensed, it is possible to prevent HO from condensing on the separation membrane in the subsequent stage and thereby prevent the membrane performance from deteriorating.

[0060] The mixed gas contains H as a degrading gas. ２ When O is contained, CO is used as the first non-degrading gas. ２ and CH as the second non-degrading gas. ４ It is more preferable to include H ２ By removing O, the performance of the separator in the subsequent stage is improved. ２ This can prevent the decrease due to swelling or blockage caused by O. ２ CO, the second most inert gas after O ２ By removing the non-permeable gas CH ４ The purity of CH ４ This reduces the risk of explosion.

[0061] The mixed gas contains H as a degrading gas. ２ When O is contained, N is used as the first non-degrading gas. ２ and CH as the second non-degrading gas. ４ It is more preferable to include H ２ By removing O, the performance of the separator in the subsequent stage is improved. ２ This can prevent the decrease due to swelling or blockage caused by O. ２ N, the second most inert gas after O ２ By removing the non-permeable gas CH ４The purity of CH ４ This reduces the risk of explosion.

[0062] Furthermore, the mixed gas contains H as a degrading gas. ２ When O is contained, CO is used as the first non-degrading gas. ２ and N as the second non-degrading gas. ２ It is particularly preferable that the first and second separation membranes 10 and 20 each contain a zeolite membrane. ２ By first removing O, H ２ O followed by CO ２ When separating CO ２ This allows for effective separation because the affinity between the catalyst and zeolite can be effectively utilized.

[0063] [Modification 2] In the above embodiment, the mixed gas contains one type of degrading gas and two types of non-degrading gas, but this is not limiting. The mixed gas may contain at least one type of degrading gas and at least two types of non-degrading gas.

[0064] [Modification 3] In the above embodiment, the second separation membrane 20, which is an example of a separator, is configured to separate CO 2 , which is an example of a first non-degrading gas contained in the first depleted gas. ２ However, the separator may be capable of separating the degrading gas together with the first non-degrading gas.

[0065] For example, if the mixed gas supplied to the first separation membrane 10 is NH ３ , CO ２ , N ２ and H ２ When the first depleted gas supplied to the second separation membrane 20 contains CO ２ , N ２ and H ２ will be included.

[0066] In this case, the second separation membrane 20 is formed to separate the CO contained in the first depleted gas. ２ and H ２ It may be possible to separate the CO ２ and H ２a first enrichment gas containing N ２ and a second depleted gas containing

[0067] [Modification 4] The first separation membrane 10 may separate a plurality of types of deteriorating gases. For example, in the above modification 2, the first separation membrane 10 may separate NH ３ and H ２ a first enriched gas enriched in NH ３ and H ２ is depleted and CO ２ and N ２ and a first depleted gas enriched with the fluorine-containing compound.

[0068] [Variation 5] In the above embodiment, the gas separation system 1 includes the second separation membrane 20 as an example of a separator, but the separator is not limited to a separation membrane. The separator may be any structure capable of separating the first non-degrading gas. For example, a structure that separates the first non-degrading gas by a PSA method, a TSA method, or an absorption method may be used as the separator.

[0069] [Modification 6] In the above embodiment, the first enriched gas containing the degrading gas separated by the first separation membrane 10 is discharged to the outside from the permeate side space of the first separation membrane 10. However, the degrading gas may be reused for synthesis of a desired substance or as a fuel. ２ may be reused.

[0070] [Variation 7] In the above embodiment, the non-degrading gas is separated after the degrading gas is separated from the mixed gas, but some of the non-degrading gas may be separated before the degrading gas is separated from the mixed gas.

[0071] For example, a CO ２ CO ２ A part of the above may be separated in advance.

[0072] 1 Gas separation system 10 First separation membrane 20 Second separation membrane

Claims

1. A gas separation system for separating a degraded gas from a mixed gas containing the degraded gas, a first non-degraded gas, and a second non-degraded gas, comprising: a first separation membrane; and a separator arranged downstream of the first separation membrane, wherein the first separation membrane selectively allows the degraded gas to permeate, thereby producing a first enriched gas enriched in the degraded gas, and a first depleted gas depleted in the degraded gas and enriched in the first non-degraded gas and the second non-degraded gas; and the separator separates the first non-degraded gas, thereby producing a second enriched gas enriched in the first non-degraded gas, and a second depleted gas depleted in the first non-degraded gas.

2. The gas separation system according to claim 1, wherein the separator is a second separation membrane that selectively allows the first non-degrading gas to permeate.

3. The gas separation system according to claim 2, wherein the second separation membrane has a different configuration from the first separation membrane.

4. A gas separation system according to any one of claims 1 to 3, wherein the concentration of the degrading gas in the gas supplied to the separator is lower than the concentration of the degrading gas in the gas supplied to the first separation membrane.

5. The degrading gas is NH ３ The gas separation system according to any one of claims 1 to 3, wherein 6. The degrading gas is H ２ and the first non-degrading gas is N ２ and the second non-depleting gas is CH ４ The gas separation system according to any one of claims 1 to 3, wherein 7. The degrading gas is H ２ and the first non-depleting gas is CO ２ and the second non-degrading gas is N ２ The gas separation system according to any one of claims 1 to 3, wherein 8. The degrading gas is H ２ and the first non-depleting gas is CO ２ and the second non-depleting gas is CH ４ The gas separation system according to claim 1 , wherein each of the first separation membrane and the separator is a zeolite membrane.

9. The degrading gas is H ２ O, and the first non-depleting gas is CO ２ and the second non-depleting gas is CH ４ The gas separation system according to any one of claims 1 to 3, wherein 10. The degrading gas is H ２ O, and the first non-degrading gas is N ２ and the second non-depleting gas is CH ４ The gas separation system according to any one of claims 1 to 3, wherein 11. The degrading gas is H ２ O, and the first non-depleting gas is CO ２ and the second non-degrading gas is N ２ The gas separation system according to claim 1 , wherein each of the first separation membrane and the separator is a zeolite membrane.

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