Gas separation device

Abstract

[Problem] To provide a gas separation device that separates a prescribed gas from a mixed gas more accurately and at lower cost. [Solution] A gas separation device 1 comprises a first electrode 20, a second electrode 22, and an AC voltage application unit 24 that applies an AC voltage between the first electrode 20 and the second electrode 22. The first electrode 20 and the second electrode 22 are disposed so as to have parts that are not parallel to each other. A distance T, which is the minimum distance among the distances between the first electrode 20 and the second electrode 22, is 1-100,000 nm. The product obtained by multiplying the pressure p of a mixed gas that is introduced between the first electrode 20 and the second electrode 22 and the distance T, which is the minimum distance among the distances between the first electrode 20 and the second electrode 22, is on the lower side of a Paschen curve. In addition, the product obtained by multiplying the pressure p and a distance U, which is the maximum distance among the inter-electrode distances, is on the lower side of the Paschen curve.

Description

Gas Separator

[0001] The present disclosure relates to a gas separation device that separates a predetermined gas from a mixed gas.

[0002] Carbon dioxide (CO) from the gas mixture ２ Known gas separation technologies for separating a specific gas such as the above include those that adsorb the specific gas from a compressed gas mixture and those that use a porous body. Known technologies using a porous body include those that form a silicone-based gas separation membrane on a porous body and those that combine a porous body with a carbonaceous layer. Development of new gas separation technologies that further improve separation performance and further reduce costs is anticipated.

[0003] On the other hand, a technology for separating bubbles from a liquid by dielectrophoresis is known, as described in Japanese Patent No. 4646125 (Patent Document 1). Also, a technology for capturing solids in a liquid by dielectrophoresis is known, as described in Japanese Patent Laid-Open No. 2023-73849 (Patent Document 2).

[0004] Japanese Patent No. 4646125 Japanese Patent Application Laid-Open No. 2023-73849

[0005] There is no known gas separation technology that separates a specific gas from a gas mixture by dielectrophoresis.

[0006] One of the main objects of the present disclosure is to provide a gas separation device that separates a predetermined gas from a mixed gas with higher accuracy, and another main object of the present disclosure is to provide a gas separation device that separates a predetermined gas from a mixed gas at lower cost.

[0007] A gas separation device according to one aspect of the present disclosure may include a first electrode. The gas separation device may include a second electrode. The gas separation device may include an AC voltage application unit that applies an AC voltage between the first electrode and the second electrode. The first electrode and the second electrode may be arranged in a state where they are not entirely parallel to each other or where they have a portion where they are not parallel to each other. The minimum distance between the first electrode and the second electrode may be 1 nm or more and 100,000 nm or less. The product of the pressure of the mixed gas introduced between the first electrode and the second electrode and the minimum distance between the first electrode and the second electrode may be below the Paschen curve. The product of the pressure of the mixed gas and the maximum distance between the first electrode and the second electrode may be below the Paschen curve.

[0008] One of the main advantages of the present disclosure is to provide a gas separation device that separates a predetermined gas from a mixed gas with higher accuracy. Another main advantage of the present disclosure is to provide a gas separation device that separates a predetermined gas from a mixed gas at lower cost.

[0009] 1 is a schematic perspective view of a gas separation device according to an embodiment; FIG. 2 is a schematic cross-sectional view of a separation section in the gas separation device; FIG. 3 is a graph showing the Paschen curve of a predetermined gas; FIG. 4 is an image showing the results of a simulation of Example 1; FIG. 5 is an image showing the results of a simulation of Example 2; and FIG. 6 is an image showing the results of a simulation of Example 3.

[0010] Hereinafter, embodiments and their modifications will be described with reference to the accompanying drawings. The embodiments and modifications are intended to be comprehensive or specific examples. The numerical values, shapes, materials, the presence or absence of components, the content of components, the arrangement of components, the connection between components, the presence or absence of steps, the content of steps, and the order of steps in the embodiments and modifications are merely examples and do not limit the scope of the claims. Furthermore, the drawings are not necessarily drawn precisely. Substantially identical components may be assigned the same reference numerals, and redundant descriptions may be omitted or simplified. Furthermore, terms indicating the relationship between components, such as parallel and perpendicular, terms describing the shape of components, such as rectangular and disc-shaped, and numerical ranges do not only indicate the strict meaning, but also encompass substantially equivalent ranges. Examples of substantially equivalent ranges include differences of about 1%, 2%, or 5%.

[0011] 1 is a schematic perspective view of a gas separation device 1 according to an embodiment. The gas separation device 1 includes a separation section 4, a first gas recovery section 6, a second gas recovery section 7, and a third gas recovery section 8. For convenience, the various directions of the gas separation device 1 are as shown in each drawing. Note that the gas separation device 1 can be used in any orientation.

[0012] FIG. 2 is a schematic cross-sectional view of the separation unit 4. The separation unit 4 separates a specific gas from a gas mixture by dielectrophoresis. Dielectrophoresis is a phenomenon in which a force acts on dielectric particles exposed to a non-uniform electric field, causing the dielectric particles to migrate. The non-uniform electric field generates a polarization charge on the dielectric particles, inducing a dipole moment. The dielectric particles then migrate to the high electric field side, where the electric field is strong, or the low electric field side, where the electric field is weak, due to differences in their electrical properties. Charging of the dielectric particles is not essential for the generation of a dielectrophoretic force. The separation unit 4 includes an inlet 10, a first electrode 20, a second electrode 22, an AC voltage application unit 24, a first insulating unit 26, and a second insulating unit 28.

[0013] The inlet 10 receives the mixed gas. The mixed gas received in the separation unit 4 from the inlet 10 flows between the first electrode 20 and the second electrode 22, as indicated by arrow R in FIG. 1 . The space between the first electrode 20 and the second electrode 22 also serves as a flow path that guides the mixed gas from the inlet 10 side, i.e., the upstream side, to the opposite downstream side. Any means may be used to generate a flow of at least one of the mixed gas, the gas being separated, and the separated gas within the flow path, such as wind, a pressure difference, or an appropriate combination of these.

[0014] The first electrode 20 is a conductive plate-like member. The second electrode 22 is a conductive plate-like member. The first electrode 20 and the second electrode 22 are arranged so as not to be entirely parallel to each other or to have portions that are not parallel to each other in order to generate a non-uniform electric field. The lengths of the first electrode 20 and the second electrode 22 in the upstream and downstream directions may be any length, preferably a length that allows sufficient separation of the mixed gas as it flows downward. The lengths of the first electrode 20 and the second electrode 22 may be different. The thicknesses of the first electrode 20 and the second electrode 22 may be any thickness, preferably a thickness that can withstand the pressure difference between the inside and outside of the first electrode 20 and the second electrode 22 and seal gases including the mixed gas, and more preferably a thickness that can withstand mechanical shock. The thicknesses of the first electrode 20 and the second electrode 22 may be different. The first electrode 20 and the second electrode 22 are bilaterally symmetrical. The first electrode 20 and the second electrode 22 do not have to be bilaterally symmetrical.

[0015] The AC voltage application unit 24 applies an AC voltage to the first electrode 20 and the second electrode 22. In FIG. 2, the first electrode 20 is on the negative voltage side and the second electrode 22 is on the positive voltage side, but since the voltage is AC, the positive and negative sides change over time. The frequency of the AC voltage may be any, for example, between 50 Hz (Hertz) and 60 Hz. In FIG. 2, a voltage of −V is applied to the first electrode 20, and a voltage of +V is applied to the second electrode 22.

[0016] The gas mixture between the first electrode 20 and the second electrode 22 moves to the high electric field side above the separation section 4 or to the low electric field side below the separation section 4 depending on the relative dielectric constant of the gas molecules. The gas molecules G1 with a relatively large relative dielectric constant are attracted to the dielectrophoretic force F ＤＥＰ The gas molecules G1 move to the high electric field side due to the dielectrophoretic force F. The gas molecules G2, which have a relatively small relative dielectric constant, move to the low electric field side. The gas molecules G1 can be considered as solutes mixed in the gas molecules G2, which are the solvent. ＤＥＰ is given by the following equation (1): ｒｍｓ is the effective value of the electric field, π is the ratio of the circumference of a circle to its circumference, r is the radius of the gas molecule G1, and ε ０ is the dielectric constant of a vacuum, and ε １ is the relative dielectric constant of the gas molecule G1, and ε ２ is the relative dielectric constant of the gas molecule G2.

[0017]

[0018] For example, the gas molecule G1 is carbon dioxide (CO ２ ) molecule, and the gas molecule G2 is oxygen (O ２ ) molecule. Strictly speaking, CO ２ Molecules and O ２ Since molecules are not perfect spheres and are very small, the average radius can be used as r. Alternatively, the maximum radius or minimum radius can be used instead of the average radius. Alternatively, the gas molecule G1 is CO ２ The gas molecule G2 as the solvent is CO ２ It is air except for molecules. Air is N ２ molecule, O ２ molecule, CO ２ Since the gas mixture contains gas molecules such as CO molecules, it may be treated as a gas molecule G2 as a solvent by using the average calculated relative dielectric constant (1.000586). ２ The averaged state includes molecules, and it is approximately CO ２ It may be treated as the relative dielectric constant of the gas molecules G2 as a solvent excluding the molecules.

[0019] Dielectrophoretic force FＤＥＰ As the dielectrophoretic force F increases, the action of separating the gas molecules G1 and G2 from each other increases. ＤＥＰ The conditions for increasing are (A) the radius r of the solute gas molecule G1 is large, (B) the difference ε between the relative dielectric constants of the gas molecules G1 and G2 is large, １ -ε ２ is large, and (C) the gradient of the square of the electric field ∇E ｒｍｓ ２ Among these conditions, (A) is based on the radius r of the gas molecule G1, which is a predetermined size, and it is difficult to dramatically increase it. Also, the radius r of the gas molecule G1 is relatively small, for example, ２ The radius r of the molecule is 0.330 nm, and ２ The radius r of the molecule is 0.346 nm, and N ２ The radius r of the molecule is 0.364 nm. Regarding (B), the difference in relative dielectric constant ε １ -ε ２ Since the element is a predetermined size, it is difficult to dramatically increase it. In addition, the relative dielectric constants of the gas molecules G1 and G2 are close to each other, and the difference in the relative dielectric constants ε １ -ε ２ is a fairly small value. For example, CO ２ The relative dielectric constant of the molecule is 1.000985, and O ２ The relative dielectric constant of the molecule is 1.000547, and N ２ The relative dielectric constant of the molecule is 1.000606, and CO ２ From the relative permittivity of the molecule, O ２ The value obtained by subtracting the relative permittivity of the molecule is 0.000438, and CO ２ From the relative permittivity of the molecule, N ２ The value obtained by subtracting the relative permittivity of the molecule is 0.000379.

[0020] So, (C)∇E ｒｍｓ ２ It would be good if ∇E ｒｍｓ ２ The condition for increasing is (C-1) E ｒｍｓand (C-2) at least one of (C-1) increasing the distance between the first electrode 20 and the second electrode 22 and (C-2) decreasing the distance between the first electrode 20 and the second electrode 22. Here, (C-2) is more important, and the distance between the first electrode 20 and the second electrode 22 in the separation section 4, i.e., the inter-electrode distance, is set to approximately 1 nm or more and 10,000 nm or less, i.e., nano-sized. The inter-electrode distance takes on multiple values ​​because the first electrode 20 and the second electrode 22 have portions that are not entirely or partially parallel. Preferably, all inter-electrode distances are set to nano-sized. Note that the upper limit of the nano-sized order for the inter-electrode distance may be other than 10,000 nm, and may be, for example, 100,000 nm, 50,000 nm, 5,000 nm, 1,000 nm, or 500 nm.

[0021] The first electrode 20 and the second electrode 22 of the separation section 4 have a parallel portion L and a tapered portion H. The parallel portion L is located on the low electric field side of the separation section 4. The first electrode 20 and the second electrode 22 in the parallel portion L are parallel. The distance U between the first electrode 20 and the second electrode 22 in the parallel portion L is constant. On the other hand, the tapered portion H is located on the high electric field side of the separation section 4. In the tapered portion H, the distance between the first electrode 20 and the second electrode 22 gradually decreases in a tapered manner. The tapered shape here follows a cubic curve that is convex in the radial direction. The first electrode 20 and the second electrode 22 in the tapered portion H are not parallel to each other. Note that the separation section 4 does not have to have the parallel portion L. That is, the first electrode 20 and the second electrode 22 may be arranged in a state where they are not generally parallel to each other. Furthermore, the non-parallel portions of the first electrode 20 and the second electrode 22 may be formed with a structure other than a tapered shape. The distance U between the first electrode 20 and the second electrode 22 in the parallel portion L is, for example, 200 nm. The distance U is the longest distance between the first electrode 20 and the second electrode 22 in the separation portion 4. On the other hand, the vertical dimension F of the tapered portion H is, for example, 200 nm. Furthermore, the distance T between the first electrode 20 and the second electrode 22 at the tip portion of the tapered portion H, i.e., the upper end portion in FIG. 2 , which is the smallest value as the distance between the first electrode 20 and the second electrode 22, is, for example, 20 nm. The tapered shape of the tapered portion H may be other than that described above. In the separation section 4 having the size exemplified above, when an AC voltage of V=100 V (volts) is applied, the electric field of the parallel portion L is 100 V / 200 nm=500 kV / mm (kilovolts per millimeter), and the electric field at the tip of the tapered portion H is 100 V / 20 nm=5000 kV / mm, resulting in a sufficiently large ∇E ｒｍｓ ２ is obtained.

[0022] In particular, in the nano-sized separation section 4, consideration must be given to suppressing discharge, i.e., short circuits. Since gas molecules G1 and G2 are introduced between the first electrode 20 and the second electrode 22, it is sufficient to suppress discharge related to the gas. Paschen's law exists as a law related to discharge related to gas. Paschen's law is a law related to the voltage at which spark discharge occurs. When a strong electric field is applied to a gas, it eventually leads to dielectric breakdown and spark discharge occurs. The voltage V at which spark discharge occurs between parallel electrodes is ｓ is a function V of the product of the gas pressure p and the distance d between the electrodes ｓ = f(pd), which is more specifically expressed by the following equation (2): The gas pressure p is expressed in units of, for example, Pa (Pascal), and the distance d between the electrodes is expressed in units of, for example, m (meter). ｓ The unit of is, for example, V. Furthermore, A and B are constants determined depending on the type of gas molecule, and γ is the secondary electron emission coefficient.

[0023]

[0024] Then, pd is the horizontal axis, and V ｓ On the graph with V as the vertical axis ｓ The curve that shows the relationship between the temperature and humidity is called the Paschen curve. ２ Molecule (Nitrogen), H ２ Molecules (Hydrogen), Argon, CO ２ A graph of the Paschen curve for a molecule (carbon dioxide) is shown. ２ The Paschen curve of the molecule (oxygen) has not been measured due to the risk of explosion. ２ The Paschen curve of a molecule is ２ Molecules and CO ２It is considered to be on the same level as molecules. If the gas pressure p and the electrode distance d are selected so that they fall below the Paschen curve, no discharge will occur between the first electrode 20 and the second electrode 22, even in a separation unit 4 on the nano-scale. The first electrode 20 and the second electrode 22 are arranged so that they are not entirely parallel to each other, or so that they have portions that are not parallel to each other. Therefore, multiple types of electrode distance d are understood, at least in the non-parallel portions, and pd should be below the Paschen curve for all types of electrode distance d. In other words, it is sufficient that all products of the electrode distance d and the gas pressure p for the first electrode 20 and the second electrode 22 fall below the Paschen curve. That is, it is sufficient that the product of the distance d between the first electrode 20 and the second electrode 22 and the gas pressure p falls below the Paschen curve as a whole. Strictly speaking, the Paschen curve differs for each gas, but the Paschen curve for all gases contained in the mixed gas to be separated is taken into consideration. While whether or not the gas mixture is below the Paschen curve is determined based on the pressure p of the gas mixture, it may also be determined based on the Paschen curve of the gas in the gas mixture and the partial pressure of the gas.

[0025] Because the separation unit 4 is on the nano-size order, it may be relatively inferior in terms of the throughput related to separation compared to larger separation units 4. From the viewpoint of ensuring a sufficient throughput even for separation units 4 on the nano-size order, it is preferable to provide a plurality of separation units 4, and more preferably, a predetermined number or more. Here, the predetermined number may be, for example, 10, 50, or 100.

[0026] The first insulating portion 26 is a plate-shaped insulator. The first insulating portion 26 is disposed within the tip of the tapered portion H. The first insulating portion 26 holds the first electrode 20 and the second electrode 22. The second insulating portion 28 is a plate-shaped insulator. The second insulating portion 28 is disposed within the lower end of the parallel portion L. The second insulating portion 28 holds the first electrode 20 and the second electrode 22. The first insulating portion 26 and the second insulating portion 28 may have any thickness. Preferably, the thickness is sufficient to withstand the pressure difference between the inside and outside of the first insulating portion 26 and the second insulating portion 28 and to seal gases, including mixed gases, and more preferably, sufficient to withstand mechanical shock. The first electrode 20 and the second electrode 22 may be held by something other than the first insulating portion 26 and the second insulating portion 28. Furthermore, the first insulating portion 26 and the second insulating portion 28 may have different thicknesses.

[0027] The first gas recovery unit 6 recovers a separated first gas from the gases constituting the mixed gas. The first gas recovery unit 6 is fixed to the second insulating unit 28. The first gas recovery unit 6 is, for example, a pump. The second gas recovery unit 7 recovers a separated second gas from the gases constituting the mixed gas. The second gas recovery unit 7 is fixed to the second insulating unit 28. The second gas recovery unit 7 is disposed downstream of the first gas recovery unit 6. The second gas recovery unit 7 is, for example, a pump. The third gas recovery unit 8 recovers a separated third gas from the gases constituting the mixed gas. The third gas recovery unit 8 is fixed to the first insulating unit 26. The third gas recovery unit 8 is, for example, a pump. The mixed gas may contain two types of gases or may contain four or more types of gases. The number of gas recovery units does not have to match the number of gases in the mixed gas. One or more gas recovery units may recover gas that is not completely separated. At least one of the gas recovery sections may be at least one of a nano-sized nozzle and a gas adsorbent.

[0028] For example, if N is added to the gas mixture, ２ , O ２ , CO ２ When the mixed gas contains O, the O is introduced into the parallel portion L on the low electric field side before the mixed gas reaches the first gas recovery unit 6. ２is separated, and N ２ , CO ２ The first gas recovery section 6 separates O ２ Collect. ２ is separated and N ２ , CO ２ The mixed gas containing N ２ (low electric field side) and CO ２ The second gas recovery section 7 is separated into the N ２ The third gas recovery unit 8 recovers CO ２ Collect.

[0029] The gas separation device 1 described above includes a first electrode 20, a second electrode 22, and an AC voltage application unit 24 that applies an AC voltage between the first electrode 20 and the second electrode 22. The first electrode 20 and the second electrode 22 are arranged with a portion that is not parallel to each other. The minimum distance T between the first electrode 20 and the second electrode 22 is 1 nm or more and 100,000 nm or less. The product of the pressure p of the mixed gas introduced between the first electrode 20 and the second electrode 22 and the minimum distance T between the first electrode 20 and the second electrode 22 lies below the Paschen curve. Furthermore, the product of the pressure p of the mixed gas and the maximum distance U between the first electrode 20 and the second electrode 22 lies below the Paschen curve. If the minimum distance T between the electrodes and the maximum distance U between the electrodes are both below the Paschen curve, then the product of the pressure of the mixed gas will be below the Paschen curve for any inter-electrode distance greater than distance T and less than distance U. Thus, a gas separation device 1 is provided that separates a predetermined gas from a mixed gas with higher accuracy by dielectrophoretic force. Furthermore, in the gas separation device 1, once a separation section 4 on the nano-size order is formed, separation of the predetermined gas from the mixed gas can be performed simply by applying an AC voltage, allowing gas separation to be performed at lower cost.

[0030] Furthermore, the smallest distance T between the first electrode 20 and the second electrode 22 is 1 nm or more and less than 100,000 nm, and the largest distance U is more than 1 nm and not more than 100,000 nm. Therefore, all distances between the first electrode 20 and the second electrode 22 are 1 nm or more and not more than 100,000 nm. Therefore, the gas separation device 1 is provided, which separates a predetermined gas from a mixed gas with higher accuracy and at lower cost. The mixed gas also contains CO ２ , O ２ , N ２ Therefore, the separation of these gases, which has conventionally been performed at high cost and with low accuracy, can be performed at lower cost and with higher accuracy. ２ If separated from other gases, CO as a greenhouse gas ２ This suppresses direct emissions of CO₂, thereby suppressing global warming. Therefore, the gas separation device 1 contributes to preserving or further improving the environment. Furthermore, the shapes of the non-parallel portions of the first electrode 20 and the second electrode 22 are tapered. Therefore, the non-parallel portions can be formed more easily.

[0031] Several computer simulations were carried out for examples based on the above-described embodiment.

[0032] Example 1 As Example 1, a simulation was performed for the above-described example of the separation unit 4 in FIG. 2 , i.e., the inter-electrode distance U of the parallel portion L was U = 200 nm, the vertical dimension F of the tapered portion H was F = 200 nm, and the inter-electrode distance T at the tip of the tapered portion H was T = 20 nm. The thicknesses of the first electrode 20 and the second electrode 22 were set to approximately zero in the simulation. In practice, a thickness of several nanometers or more, more preferably approximately 1000 nm or more, depending on the rigidity of the material, can generate an electric field similar to that in the simulation and encapsulate a mixed gas or the like within the first electrode 20 and the second electrode 22. The effective value of the applied AC voltage was 100 V. In the simulation, the low electric field side portion of the separation unit 4 was assumed to continue infinitely downward to facilitate calculations, but in practice, similar results can be obtained if the thickness is approximately 1 mm or more. In the simulation, the first electrode 20 and the second electrode 22 are assumed to continue infinitely in the direction perpendicular to the paper surface of FIG. 2, i.e., in the upstream and downstream directions, in order to simplify the calculations. However, in reality, similar results can be obtained if the distance between the electrodes is about 1 mm or more. ２ molecule, O ２ molecule, and CO ２ The molecules are contained in the separation unit 4 at a molar ratio similar to that of the molecules in air. In addition, the simulation was performed for one minute after the start of the separation process, i.e., after the start of the application of the AC voltage. The pressure of the mixed gas in the separation unit 4 was 1 atmosphere, i.e., p = 10 ３ pd is located below the Paschen curve for all inter-electrode distances d, including the maximum inter-electrode distance U (inter-electrode distance d = 200 nm) and the minimum inter-electrode distance T (inter-electrode distance d = 20 nm) in the separation section 4. Therefore, in Example 1, no discharge occurs between the electrodes.

[0033] FIG. 4 shows the results of the simulation. ２ molecule, O ２ molecule, and CO ２ This is a three-part image showing the concentration distribution of CO molecules between the electrodes. ２ Molecules and N２ The relative dielectric constant of the molecule is O ２ It is larger than the relative dielectric constant of the molecule. ２ Molecules and N ２ The molecules are attracted to the dielectrophoretic force F ＤＥＰ On the other hand, O ２ The molecules are retained on the low electric field side of the separation unit 4 due to the dielectrophoretic force that moves them toward the low electric field side. ２ The molecule is CO ２ Molecules and N ２ More specifically, CO ２ Molecules and N ２ The molecules are concentrated in the tapered portion H of the separation section 4 and in the radially inner portion away from the first electrode 20 and the second electrode 22 in the portion of the parallel portion L of the separation section 4 adjacent to the tapered portion H in the vertical direction. ２ The molecules gather in the radially outer portion of the parallel portion L of the separation section 4, adjacent to the boundary with the tapered portion H, and close to the first electrode 20 and the second electrode 22. ２ The molecule is CO ２ Molecules and N ２ It should be noted that, one second after the AC voltage application started, all of the O molecules in the mixed gas were collected. ２ More than 80% of the molecules reach the parallel part L. In addition, after 1 minute from the start of AC voltage application, all of the O molecules in the mixed gas ２ More than 90% of the molecules reach the parallel portion L.

[0034] O ２ Once the molecules are collected by the first gas collection unit 6, O ２ The molecules are separated from the gas mixture and CO ２ Molecules and N ２ The CO molecule remains. ２ Molecules and N ２ If separation of the molecule is required, the separation can be carried out by CO ２ Molecules and N ２ The new gas mixture containing the CO molecules is then separated in the same manner as described above. ２ The relative permittivity of the molecule is N ２ Because the relative permittivity of the molecule is larger than that of CO２ Molecules gather on the high electric field side, while N ２ Molecules stay on the low electric field side. ２ The molecules are collected by the second gas collection unit 7. ２ The molecules are collected by the third gas collection section 8 .

[0035] Example 2: Example 2 was simulated in the same manner as Example 1, except for the following change: the pressure p of the gas mixture in Example 2 was changed to p = 10 atmospheres, i.e., p = 10 ４ The pressure p in Example 2 was 1000 hPa, which was 10 times the pressure p in Example 1. The effective value of the applied voltage in Example 2 was 1000 V, which was 10 times the effective value of the applied voltage in Example 1. The pressure p can be increased by, for example, increasing the gas flow rate and / or placing the gas separation device 1 in a pressure chamber. The pressure p in Example 2 is located below the Paschen curve at any distance d between the electrodes. Therefore, no discharge occurs between the electrodes in Example 2.

[0036] FIG. 5 shows the results of the simulation. ２ molecule, O ２ molecule, and CO ２ The image is divided into three parts, each showing the concentration distribution of CO molecules between the electrodes. ２ Molecules and N ２ Molecules gather on the high electric field side, and O ２ The molecule is CO ２ Molecules and N ２ They gather on the low electric field side to avoid the CO molecules. ２ Molecules and N ２ The molecules are concentrated in the tapered portion H of the separation section 4 and in the radially inner portion of the parallel portion L of the separation section 4 that is connected to the tapered portion H in the vertical direction. ２ Molecules and N ２ The vertical length of the radially inner portion of the parallel portion L where the molecules gather is longer than that in Example 1. ２The molecules gather in the parallel portion L of the separation section 4 at a portion adjacent to the boundary with the tapered portion H, in the radially outer portion close to each electrode. ２ The vertical length of the radially outer portion of the parallel portion L where the molecules gather is longer than that in the first embodiment.

[0037] In Example 2, the gas pressure p is 10 times higher and the applied voltage is 10 times higher than in Example 1, so although a mechanism for increasing the pressure p and the voltage is required, the amount of gas molecules separated is greater.

[0038] Example 3 Example 3 was simulated in the same manner as Example 1, except for the following change: the pressure p of the gas mixture in Example 3 was changed to p=10 ３ Atmospheric pressure, i.e. p = 10 ６ The pressure p in Example 3 was 1000 hPa, which was 1000 times the pressure p in Example 1 and 100 times the pressure p in Example 2. The effective value of the applied voltage in Example 3 was 1000 V, which was 10 times the effective value of the applied voltage in Example 1 and was equivalent to that in Example 2. Furthermore, all dimensions of the separation section 4 in Example 3 were 10 times those in Example 1. That is, the distance U was set to U = 2000 nm, the distance T was set to T = 200 nm, and the size F of the parallel portion L was set to F = 2000 nm. pd in Example 3 was located below the Paschen curve at any distance d between the electrodes. Therefore, no discharge occurs between the electrodes in Example 3.

[0039] FIG. 6 shows the results of the simulation. ２ molecule, O ２ molecule, and CO ２ The image is divided into three parts, each showing the concentration distribution of CO molecules between the electrodes. ２ Molecules and N ２ Molecules gather on the high electric field side, and O ２ The molecule is CO ２ Molecules and N ２ They gather on the low electric field side to avoid the CO molecules. ２ Molecules and N ２The molecules are concentrated in the tapered portion H of the separation section 4 and in the radially inner portion of the parallel portion L of the separation section 4 that is connected to the tapered portion H. ２ Molecules and N ２ The vertical length of the radially inner portion of the parallel portion L where the molecules gather is shorter than that in Examples 1 and 2. ２ The molecules gather in the parallel portion L of the separation section 4, in a portion adjacent to the boundary with the tapered portion H and close to each electrode. ２ The vertical length of the radially outer portion of the parallel portion L where the molecules gather is shorter than that in the first embodiment.

[0040] In Example 3, the gas pressure p is 1000 times higher and the applied voltage is 10 times higher than in Example 1, while the size of each electrode is 10 times larger. Therefore, although a mechanism for increasing the pressure p and voltage is required, the amount of gas molecules separated increases and the separation unit 4 becomes easier to form. Furthermore, a number of other similar simulations performed by changing various values ​​have shown that if the distance T, which is the smallest of at least the inter-electrode distances, is 100,000 nm or less, separation is possible even if the object to be separated is a gas, and if the distance T is 10,000 nm or less, separation is sufficiently possible even if the object to be separated is a gas, and if the distance T is even smaller, ∇E ｒｍｓ ２ It was also found that if the distance U, which is the maximum distance between the electrodes, is greater than the minimum distance T, and is 100,000 nm or less, the distance T becomes less than 100,000 nm, and the mixed gas can be separated; if the distance U is 10,000 nm or less, the distance T becomes smaller, and the mixed gas can be separated sufficiently; and if the distance U is even smaller, the distance T becomes even smaller, and the gas can be separated more sufficiently.

[0041] 1: Gas separation device, 4: Separation section, 20: First electrode, 22: Second electrode, 24: AC voltage application section, T: Minimum distance between electrodes, U: Maximum distance between electrodes.

Claims

1. A gas separation device comprising: a first electrode; a second electrode; and an AC voltage application unit that applies an AC voltage between the first electrode and the second electrode; the first electrode and the second electrode are arranged in a state where they are not entirely parallel to each other or where there are portions where they are not parallel to each other; the smallest distance between the first electrode and the second electrode is between 1 nm and 100,000 nm; the product of the pressure of a mixed gas introduced between the first electrode and the second electrode and the smallest of the distances lies below the Paschen curve; and the product of the pressure and the largest of the distances lies below the Paschen curve.

2. The gas separation device according to claim 1, wherein the smallest of the distances is equal to or greater than 1 nm and less than 100,000 nm, and the largest of the distances is greater than 1 nm and equal to or less than 100,000 nm.

3. The mixed gas is CO ２ , O ２ , N ２ The gas separation device according to claim 1, wherein at least any two of the gases include a selected gas.

4. The gas separation device according to claim 1, wherein the portions of the first electrode and the second electrode that are not parallel to each other have a tapered shape.

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