Gas concentration apparatus

Abstract

To provide a gas concentration apparatus that improves gas concentration by shortening the time in which a target gas component is adsorbed to an adsorbent and by shortening the time in which the target gas component is released from the adsorbent.SOLUTION: The gas concentration apparatus includes: a cylindrical body filled with an adsorbent that adsorbs a target gas component contained in introduced gas and releases the target gas component by heating; an inlet formed in the cylindrical body, for allowing gas to flow into the upstream surface of the adsorbent; an outlet formed in the cylindrical body for discharging gas from the downstream surface of the adsorbent; and a gas introduction passage for introducing gas into the central portion of the adsorbent.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a gas concentrator. [Background technology]

[0002] As a gas concentrating device, for example, the gas concentrating devices described in Patent Documents 1 and 2 are known. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-146369 [Patent Document 2] Japanese Patent Application Publication No. 2022-146694 Summary of the Invention [Problem to be solved by the invention]

[0004] In the gas concentration devices of Patent Documents 1 and 2, an adsorbent is filled in a cylinder, and gas is introduced from one end of the cylinder. This limits the contact area between the gas and the adsorbent, and it takes time to adsorb the target gas components onto the adsorbent. It also takes time to desorb the target gas components from the adsorbent, leaving room for improvement.

[0005] Taking the above facts into consideration, the present disclosure aims to improve gas concentration by shortening the time it takes for the target gas components to be adsorbed onto the adsorbent and shortening the time it takes for the target gas components to be desorbed from the adsorbent. [Means for solving the problem]

[0006] The gas concentration device of the first aspect comprises a cylindrical body filled with an adsorbent that adsorbs target gas components contained in introduced gas and desorbs the target gas components when heated, an inlet formed in the cylindrical body for allowing the gas to flow into the upstream side of the adsorbent, an outlet formed in the cylindrical body for allowing the gas to flow out from the downstream side of the adsorbent, and a gas introduction passage for introducing the gas into the central portion of the adsorbent.

[0007] Regarding gas adsorption, in a conventional gas concentration device in which an adsorbent is filled in a cylinder and gas is introduced from one end of the cylinder, when gas is introduced from one end of the cylinder, the gas supplied to one end of the adsorbent flows gradually from one end to the other end inside the adsorbent, and the adsorbent gradually adsorbs the gas from one end to the other end.

[0008] In the gas concentration device according to the first aspect, gas is introduced from an inlet of a cylindrical body into the upstream side of the adsorbent, and the target gas components are adsorbed from the upstream side to the downstream side of the adsorbent. Also, a portion of the gas flowing into the upstream side of the adsorbent is introduced into the central part of the adsorbent through a gas introduction passage, and the target gas components are adsorbed by the adsorbent.

[0009] In this way, by providing a gas introduction passage, the area over which the target gas components come into contact with the adsorbent is increased, increasing the amount of adsorption of the target gas components, and shortening the adsorption time, compared to a configuration in which gas is simply introduced into the upstream side of the adsorbent.

[0010] Furthermore, when the target gas components are desorbed from the adsorbent by heating, the target gas components are adsorbed in the central part of the adsorbent close to the outlet, so the distance that the target gas components travel through the adsorbent to reach the outlet is shortened, i.e., the target gas components can be desorbed from the adsorbent in a short time.

[0011] A gas concentrating apparatus according to a second aspect is the gas concentrating apparatus according to the first aspect, wherein the gas introduction passage is an elongated hole provided in the center of a cross section of the adsorbent and formed in the inflow direction of the gas.

[0012] The gas concentrating device according to the second aspect can increase the area where the detection target gas component comes into contact with the adsorbent with a simple configuration in which an elongated hole is formed in the center of the cross section of the adsorbent.

[0013] A gas concentrating apparatus according to a third aspect is the gas concentrating apparatus according to the first aspect, wherein the gas introduction passages are a plurality of elongated holes provided in the adsorbent and formed in the gas inflow direction.

[0014] In the gas concentrating device according to the third aspect, the area over which the detection target gas component comes into contact with the adsorbent can be increased compared to when there is one elongated hole.

[0015] A gas concentration device according to a fourth aspect is the gas concentration device according to the second or third aspect, wherein the long hole is formed by a pipe embedded in the adsorbent and having a closed downstream end, and a hole is formed in the outer periphery of the downstream end of the pipe.

[0016] In the gas concentration device according to the fourth aspect, the gas flow rate can be increased by ejecting the gas from holes formed on the outer periphery of the downstream end of the pipe, thereby shortening the adsorption time.

[0017] A gas concentration device according to a fifth aspect is the gas concentration device according to the first aspect, wherein the gas introduction passage is a bypass pipe that branches off from an inlet pipe that introduces the gas into the inlet and introduces the gas from the outer periphery of the cylindrical body to a central portion of the adsorbent.

[0018] In the gas concentration device according to the fifth aspect, the gas introduction passage is a bypass pipe that branches off from the inlet pipe that introduces gas into the inlet and introduces gas from the outer periphery of the cylindrical body to the central portion of the adsorbent, so that gas can be introduced into the central portion of the adsorbent without the need to process the axial center portion of the adsorbent.

[0019] A gas concentrating apparatus according to a sixth aspect is the gas concentrating apparatus according to any one of the first to fifth aspects, wherein two or more types of adsorbents are filled in the cylindrical body.

[0020] In the gas concentrating device according to the sixth aspect, the cylindrical body is filled with two or more types of adsorbents, so that the concentrations of different types of target gas components can be increased simultaneously.

[0021] A gas concentrating apparatus according to a seventh aspect is the gas concentrating apparatus according to any one of the first to sixth aspects, wherein the outer periphery of the cylindrical body is heated by a heating device that heats the outer periphery of the cylindrical body.

[0022] In the gas concentrating device according to the seventh aspect, a heating device for heating the cylindrical body is provided on the outer periphery of the cylindrical body, thereby enabling rapid switching between adsorption and desorption of the target gas component. Because the heating device is provided on the outer periphery of the cylindrical body, the adsorbent inside the cylindrical body can be quickly heated. Therefore, by heating the adsorbent with the heating device provided on the outer periphery of the cylindrical body, the adsorbed gas can be desorbed from the adsorbent, thereby increasing the concentration rate of the target gas component.

[0023] In the adsorbent, the distance from the longitudinal middle portion to the other end is shorter than the distance from one end to the other end, so gas desorbed from the adsorbent near the longitudinal middle portion can be discharged from the other end of the adsorbent more quickly than gas desorbed from the adsorbent near one end, thereby shortening the time from heating to discharging the adsorbed gas. [Effects of the Invention]

[0024] As described above, according to the gas concentrating device of the present disclosure, the detection target gas component is adsorbed to the adsorbent. This reduces the time required for the detection of target gas components to be separated from the adsorbent. It is possible to improve gas concentration. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a cross-sectional view taken along an axis illustrating a gas concentrating apparatus according to an embodiment of the present disclosure. [Figure 2]FIG. 2 is an enlarged cross-sectional view showing a main part of the gas concentrating device. [Figure 3] FIG. 2 is a schematic diagram showing the desorption of acetone from an adsorbent. [Figure 4] FIG. 10 is a diagram showing the set times and parameters for gas adsorption and desorption. [Figure 5] 1 is a graph showing calculation results (simulation results) of gas adsorption. [Figure 6] 1 is a graph showing calculation results (simulation results) of gas desorption. [Figure 7] 1 is a graph showing pressure distribution of an adsorbent. [Figure 8] 1 is a graph showing the velocity distribution of gas in the adsorbent. [Figure 9] 10(A) to 10(D) are cross-sectional views showing a gas concentrating device according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] A gas concentrating device 10 according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2, a gas concentrating device 10 of this embodiment includes a cylindrical body 12, which is shaped like a cylindrical pipe, and the inside of the cylindrical body 12 is filled with an adsorbent 14 that adsorbs gas and desorbs the adsorbed gas by heating. The adsorbent 14 may be porous or an aggregate of many particles, and the structure is not critical as long as it allows gas to pass through. In addition, the end of the cylindrical body 12 on the left side of the drawing is an inlet 12A, and the end on the right side of the drawing is an outlet 12B.

[0027] The adsorbent 14 of this embodiment is formed in a cylindrical shape and is disposed in the middle of the cylindrical body 12. When the adsorbent 14 is an aggregate of many particles, mesh 16 or the like that blocks the particles but allows gas to pass through can be provided at both ends of the adsorbent 14 to prevent the particles from scattering, as shown in FIG.

[0028] Examples of the adsorbent 14 include UiO-66, MOF-5, Mg-MOF74, H-KUST1, ZIF7, ZIF8, ZIF90, MIL-101, synthetic zeolite, mesoporous silica, and glassy carbon, but other adsorbent materials may also be used as long as they are capable of adsorbing the target gas. The adsorbent 14 may be any one of the adsorbents described above, or may be a combination of two or more of the adsorbent materials described above.

[0029] Incidentally, MOF stands for Metal Organic Frameworks, and is known for its high degree of freedom in designing material structures. One MOF, UiO-66, has high acetone adsorption properties.

[0030] At the axial center of the adsorbent 14, for example, a gas introduction pipe 18 is provided, which is an example of a gas introduction passage in the form of a cylindrical pipe and has a diameter smaller than that of the cylindrical body 12.

[0031] The gas introduction pipe 18 extends from one end (the end on the left side of the drawing) of the adsorbent 14 to the other end (the right side of the drawing). For example, the other end of the gas introduction pipe 18 can be provided between the longitudinal center and the other end of the adsorbent 14. For example, the diameter of the gas introduction pipe 18 can be ⅔ or less of the diameter of the cylindrical body 12.

[0032] The opening on the other end of the gas introduction pipe 18 is blocked by a blocking member 18A, and a plurality of gas outlets 20 are formed on the side surface of the other end. The gas outlets 20 can be provided between the longitudinal center of the adsorbent 14 and the other end. In the gas introduction pipe 18 of this embodiment, two gas outlets 20 are formed on the side surface at the upper side in the drawing, spaced apart in the longitudinal direction of the cylinder, and two gas outlets 20 are formed on the side surface at the lower side in the drawing, spaced apart in the longitudinal direction of the cylinder. In this embodiment, the gas outlets 20 are round holes, but the gas outlets 20 may be other than round holes and may be elongated slits.

[0033] The diameter of the gas ejection holes 20 is smaller than the inner diameter of the gas introduction pipe 18. In this embodiment, as an example, the length of the cylindrical body 12 is 100 mm, the diameter of the adsorbent 14 (the inner diameter of the cylindrical body 12) is 8 mm, the length of the adsorbent 14 is 30 mm, and the diameter of the gas ejection holes 20 is 1 mm, but each dimension can be changed appropriately as needed, and the dimensions of each part are not limited to the above dimensions.

[0034] An electric heater 22 as an example of a heating device for heating the adsorbent 14 is provided on the outer periphery of the cylindrical body 12 .

[0035] (Action, effect) Next, the operation of the gas concentrating device 10 will be described. (gas adsorption) To adsorb a gas to the adsorbent 14 of the gas concentrating apparatus 10, the gas is introduced into the cylindrical body 12 from one end thereof as shown by the arrow IN in FIG. As shown by arrow IN in Figure 2, part of the gas introduced into the cylindrical body 12 is introduced into the gas introduction pipe 18 through the mesh 16, and another part is introduced through the mesh 16 from one end of the adsorbent 14 toward the adsorbent 14.

[0036] In the gas concentrating apparatus 10 of this embodiment, gas adsorption into the adsorbent 14 mainly begins near the tip of the gas inlet pipe 18 , and gradually progresses into the adsorbent 14 on one end side of the cylindrical body 12 .

[0037] Because the adsorbent 14 acts as a resistance to the passage of gas, the resistance to the passage of gas passing through the adsorbent 14 from one end to the other end is greater than the resistance to the passage from the longitudinal middle of the adsorbent 14 to the other end. Therefore, at one end that is far from the other end, the speed at which the gas passes through the adsorbent 14 is slow (i.e., gas adsorption is slow and the amount of gas adsorbed is small), and near the end of the gas inlet pipe 18 that is relatively close from the other end, the speed at which the gas is discharged from the gas inlet pipe 18 and passes through the adsorbent 14 is fast (i.e., gas adsorption is fast and the amount of gas adsorbed is large).

[0038] In the adsorbent 14 equipped with the gas introduction pipe 18, gas is introduced at two locations, one end and the middle portion in the longitudinal direction, which increases the contact area between the gas and the adsorbent 14 and increases the gas flow rate in the middle portion in the longitudinal direction. As a result, a large amount of gas can be adsorbed earlier than in the case where the gas introduction pipe 18 is not equipped, and the gas adsorption time can be shortened.

[0039] In addition, since multiple gas outlet holes 20 are formed on the side of the other end of the gas introduction pipe 18, a large amount of gas can be supplied to and adsorbed over a wide area of ​​the adsorbent 14 compared to when there is only one gas outlet hole 20.

[0040] (Desorption of adsorbed gas) In the gas concentrating device 10, the adsorbent 14 is heated by the electric heater 22, thereby allowing the gas adsorbed in the adsorbent 14 to be desorbed from the adsorbent 14. At this time, a carrier gas (inert gas) is supplied from one end of the cylindrical body 12, and the gas desorbed from the adsorbent 14 is pushed downstream.

[0041] In the adsorbent 14, the distance from the longitudinal center to the other end is shorter than the distance from one end to the other end, so the gas desorbed from the adsorbent 14 near the longitudinal center can be discharged from the other end of the cylindrical body 12 more quickly than the gas desorbed from the adsorbent 14 near one end. As shown in FIG. 1, a gas detector 26 can be connected downstream of the cylindrical body 12 to detect the concentrated target gas component discharged from the gas concentrating device 10.

[0042] 3 schematically illustrates the desorption of acetone, an example of a gas, from the adsorbent 14. In FIG. 3, the upper part shows a gas concentrating apparatus according to a conventional example, the left side shows a case where the adsorbent packing rate is low, and the right side shows a case where the adsorbent packing rate is high. In addition, in FIG. 3, the lower part shows a gas concentrating apparatus according to an embodiment to which the present disclosure is applied, the left side shows a case where the adsorbent packing rate is low, and the right side shows a case where the adsorbent packing rate is high. For the calculations, adsorbents with three different filling rates were set. The upper limit of 70% was based on a filling rate of 68% for body-centered cubic lattice structure (BCC) and 74% for face-centered cubic lattice structure (FCC). In this state, a low concentration of target gas was introduced from the inlet (a low concentration of target gas was introduced into the carrier gas), with the target gas concentration equivalent to 0.1 ppm (= 100 ppb). This was introduced for the time shown in Figure 4. After four minutes had passed, the temperature was increased and the gas adsorbed on the adsorbent was desorbed.

[0043] Figure 4 shows an example of the set time and parameters for gas adsorption and desorption. Here, a constant pressure (1.5 MPa) is applied to the adsorbent to release a gas at a predetermined concentration (1 mol / m 3 ) is supplied for 4 minutes, and then the adsorbent 14 is heated to 300°C to desorb the gas adsorbed in the adsorbent. The pressure, concentration, and temperature are appropriately changed as necessary.

[0044] Next, the results of a simulation of gas adsorption into an adsorbent are shown in the figure below. (Gas adsorption calculation) Figure 5 shows the calculation results for the total amount of gas adsorbed by the adsorbent. This is the result of integrating the number of moles of target gas adsorbed throughout the adsorbent. It can be seen that the structure of this example adsorbs the target gas more quickly than the comparative example for all adsorbents with filling rates of 40, 60, and 70% (the slope of the graph line is steeper). This is thought to be due to the increased contact area and high pressure near the tip of the gas inlet tube (the gas outlet holes are small, 1 mm in diameter, in four locations), which allowed the target gas to be efficiently adsorbed into the adsorbent. After 4 minutes, heat was applied to the adsorbent, causing the target gas adsorbed by the adsorbent to desorb. As a result, the amount of gas adsorbed by the adsorbent was significantly reduced (molar amount). Note that the vertical axis of the figure represents the amount of gas adsorbed by the adsorbent, not its movement to the outside (rearward) (the results are shown in Figure 6).

[0045] (Gas release calculation) FIG. 6 also shows the results of calculating the amount of gas passing through (reaching) the other end of the adsorbent (the vertical axis of the results is the cumulative amount of gas passing through). It can be seen that, at all packing rates of 40, 60, and 70%, the target gas reaches the other end of the adsorbent faster in this example than in the comparative example. This is due to the effect of the target gas being adsorbed at the rear of the adsorbent in the structure of this example equipped with a gas inlet tube. Therefore, at a packing rate of 40%, it takes 5 minutes for the gas to begin escaping to the outside in the comparative example, whereas in this example, the time required for gas to begin escaping is reduced to about 2.5 minutes. It can be seen that providing a gas inlet tube speeds up gas desorption, shortening the concentration and desorption process.

[0046] (Pressure distribution of adsorbent) Due to the performance of the gas supply pump, the pressure is set at 1.5 MPa (installed upstream of the gas). Therefore, the pressure upstream of the adsorbent is 1.5 MPa, and 0 Pa downstream (because the downstream outlet is open to the atmosphere). In the comparative example, the pressure inside the adsorbent decreases at a constant rate from upstream to downstream. This is because the adsorbent is uniformly filled. Therefore, there is no point where the pressure is concentrated (no weak spots), and pressure is applied to the entire adsorbent, so the gas flowing through the adsorbent is at a constant rate.

[0047] On the other hand, in the structure of this example equipped with a gas inlet tube, there is a large bias in the pressure. For example, the pressure at the tip of the gas inlet tube is about 1 MPa (compared to approximately 0.6 MPa at that position in the comparative example). In other words, the pressure does not decrease at a constant rate depending on the distance from the adsorbent. The key point is the pressure of 1 MPa at the tip of the gas inlet tube. Since 1 MPa of pressure is generated over distance X (1 cm), a large amount of pressure is applied at this point (0.6 MPa in the comparative example). Therefore, at position X (1 cm), the pressure is high in the structure of this example equipped with a gas inlet tube, and the gas flows quickly. No difference in pressure was observed depending on the filling rate.

[0048] (Pressure distribution inside the adsorption chamber) To compare the Example and Comparative Example, the pressure distribution within the adsorbent is shown in Figure 7. The structure of this Example, equipped with a gas inlet tube, exhibits a distinctive pressure distribution. While the amount of change in pressure from the inlet to the tip of the gas inlet tube is relatively small, the pressure changes significantly from the tip of the gas inlet tube to the outlet, with a large gradient. No difference in pressure was observed depending on the filling rate.

[0049] (Velocity distribution of adsorbent) In the comparative adsorbent, the desorbed gas velocity is constant because of the constant pressure gradient from upstream to downstream, which is related to the pressure in Figure 7.

[0050] As shown in Figure 8, in the structure of this embodiment equipped with a gas inlet pipe, the velocity is high near the tip of the gas inlet pipe. Therefore, a faster gas flow means that the molecular weight of the gas adsorbed by the adsorbent increases. Furthermore, desorption of the adsorbed gas is also promoted while the purge gas is flowing.

[0051] Regarding speed, the higher the packing rate, the slower it is for both the comparative example and the present example. This is because a higher packing rate means less open space, so the speed inevitably decreases. However, the gas flow of the adsorbent with a packing rate of 70% in the comparative example is 3 x 10 -5 m / s, but in the structure of this example, due to the effect of pressure distribution, the gas flow rate is 10 × 10 -5 m / s, which indicates that the gas flows easily.

[0052] In conclusion, the structure of the comparative example had the problem that it took a long time to adsorb and desorb gas. As a result, it was disadvantageous to the system in terms of responsiveness. Therefore, the results of the simulation show that using the structure of this embodiment has the following advantages. 1) Gas adsorption can be accelerated. 2) Gas desorption can be accelerated.

[0053] The gas concentrating device 10 of this embodiment can be used, for example, to concentrate gases such as acetone contained in human breath.

[0054] [Other embodiments] Although one embodiment of the present disclosure has been described above, examples of gases to be inspected include exhaled gases, body odor and skin gases, exhaust gases from factories, sewage, atmospheric gases from hot spring facilities, gases for managing the freshness of food, plant scents, etc. The present disclosure is not limited to the above, and of course can be implemented in various modifications within the scope of the present disclosure.

[0055] In the above embodiment, one gas introduction pipe 18 is embedded in the adsorbent 14, but multiple gas introduction pipes 18 may be embedded, and in that case, the lengths of the gas introduction pipes 18 may be the same or different.

[0056] 9(A) to 9(D), the tip of one or more bypass pipes 18B (branching from the inlet pipe 24 that introduces gas into the cylindrical body 12) can be inserted into the adsorbent 14 from the outside of the cylindrical body 12 to introduce gas into the longitudinal middle portion of the adsorbent 14. This allows a larger amount of gas to be adsorbed by the adsorbent 14 near the longitudinal middle portion in a shorter time.

[0057] In the above embodiment, the gas injection holes 20 are provided on the side surface of the gas introduction pipe 18, but the gas injection holes 20 may be added to the closing member 18A as needed.

[0058] In the above embodiment, the gas introduction pipe 18 has gas outlet holes 20 formed on its side surface, and the gas is ejected from the gas outlet holes 20. However, the gas introduction pipe 18 may be formed of a mesh, and the gas may be ejected from the holes in the mesh. Even in this case, the gas can be introduced into the longitudinal middle of the adsorbent 14.

[0059] When the adsorbent 14 is formed not of granules (powder) but of a porous material (sponge-like material) through which gas can pass, a long slot may be formed in the axial direction instead of providing the gas inlet pipe 18. Note that multiple slots may be formed. Even in this case, gas can be introduced into the longitudinal middle of the adsorbent 14.

[0060] Note that the type of gas that can be easily adsorbed varies depending on the type of adsorbent. Therefore, the cylindrical body 12 is not limited to being filled with one of the various adsorbents described above, but may be filled with multiple types of adsorbents that can easily adsorb different types of gas. This makes it possible to adsorb multiple types of gas. For example, when it is desired to adsorb two types of gas, two different types of adsorbents can be filled separately in the upper half and lower half of the cylindrical body 12 across the axis. Furthermore, when it is desired to adsorb three or more types of gas, it is sufficient to configure three or more types of adsorbents in a three-layer structure. [Explanation of symbols]

[0061] 10 Gas concentrator 12 Cylinder 12A inlet 12B Outlet 14 Adsorbent 18 Gas inlet pipe (gas inlet passage, slot, pipe) 18a Closure member 20 Gas vents (holes) 22 Heating device

Claims

1. a cylindrical body filled with an adsorbent that adsorbs target gas components contained in introduced gas and desorbs the target gas components when heated; an inlet formed in the cylindrical body for allowing the gas to flow into the upstream side surface of the adsorbent; an outlet formed in the cylindrical body and allowing the adsorbent to flow out from a downstream side surface; a gas introduction passage for introducing the gas into a central portion of the adsorbent; A gas concentrator having:

2. the gas introduction passage is an elongated hole provided in the center of a cross section of the adsorbent and formed in the inflow direction of the gas; The gas concentrating device according to claim 1 .

3. the gas introduction passages are a plurality of elongated holes provided in the adsorbent and formed in the gas inflow direction; The gas concentrating device according to claim 1 .

4. the long hole is formed by a pipe that is embedded in the adsorbent and has a closed downstream end, The pipe has a hole formed in the outer periphery of the downstream end. The gas concentrating device according to claim 2 or 3.

5. the gas introduction passage is a bypass pipe that branches off from an inlet pipe that introduces the gas into the inlet and introduces the gas from the outer periphery of the cylindrical body to a central portion of the adsorbent. The gas concentrating device according to claim 1 .

6. Two or more types of adsorbents are filled in the cylindrical body. The gas concentrating device according to claim 1 .

7. The adsorbent is heated by a heating device that heats the outer periphery of the cylindrical body. The gas concentrating device according to claim 1 .

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