Methane purification device
By using a honeycomb-structured silicon carbide catalytic heater in the methane purification device to heat the gas and ozone, the reaction between methane and ozone is promoted, solving the problem of low catalyst efficiency at low temperatures and achieving highly efficient methane purification.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-25
- Publication Date
- 2026-03-10
AI Technical Summary
In existing technologies, when the catalyst temperature is low, the reaction between methane and ozone on the catalyst is difficult to proceed effectively, resulting in low methane purification efficiency.
A catalytic heater made of silicon carbide with a honeycomb structure is placed downstream of the ozone supply unit to heat the gas and ozone, and to promote the reaction of methane and ozone by supporting the catalyst with non-metallic materials.
It effectively promotes the reaction of methane and ozone on the catalyst, improves the methane purification efficiency, and avoids ozone reduction and moisture residue, thus enhancing the purification effect.
Smart Images
Figure CN121623554A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a methane purification device for purifying methane in a gas. Background Technology
[0002] Japanese Unexamined Patent Application Publication No. 2021-505376 discloses a technology in which a gas containing methane and ozone is provided to a catalyst, and the methane and ozone react on the catalyst to purify the methane. Specifically, the methane is purified by reacting with ozone to decompose into carbon dioxide and water. Summary of the Invention
[0003] The problem to be solved by the present invention However, in the above-mentioned technologies, when the temperature of the catalyst is low, the reaction between methane and ozone on the catalyst is not easy to proceed, making it difficult to effectively purify methane.
[0004] This disclosure is primarily aimed at this point, and its purpose is to facilitate the reaction of methane and ozone on a catalyst.
[0005] Problem-solving methods One aspect of this disclosure provides a methane purification apparatus, including a flow path through which a methane-containing gas flows, an ozone supply unit for supplying ozone to the gas, and a non-metallic heater disposed downstream of the ozone supply unit in the flow path and heating the gas and ozone, wherein the heater supports a catalyst for purifying methane by reacting ozone with methane.
[0006] In addition, the heater may include a heating element with a honeycomb structure, on which the catalyst may be supported.
[0007] Furthermore, the heating element can be made of silicon carbide. Additionally, the heater may include a cylindrical support supporting the catalyst and a heating unit that generates heat when power is supplied to the interior of the support.
[0008] In addition, the heater may include a plurality of flat heating plates arranged at predetermined intervals along the axial direction of the flow path, each of which may support a catalyst on its surface.
[0009] In addition, the catalyst may include any one of zeolite, iron-exchange zeolite, and cobalt-exchange zeolite.
[0010] In addition, the methane purification device may further include a detection unit for detecting the temperature of the catalyst, and a temperature control unit for operating the heater to keep the temperature of the catalyst below the first temperature of ozone decomposition.
[0011] In addition, the temperature control unit can operate the heater to bring the temperature of the catalyst below the first temperature and to the second temperature at or above the temperature at which water evaporates.
[0012] In addition, the temperature control unit can alternately repeat low-temperature control and high-temperature control. Low-temperature control is performed by operating the heater to keep the temperature of the catalyst at a third temperature for a first time period, which is lower than the second temperature at which water evaporates. High-temperature control is performed by operating the heater to keep the temperature of the catalyst between the second temperature and the first temperature for a second time period, which is shorter than the first time period.
[0013] Effects of the present invention According to the present invention, the reaction of methane and ozone on a catalyst can be promoted. Attached Figure Description
[0014] Figure 1 The configuration of a methane purification device 1 according to one embodiment is shown schematically.
[0015] Figure 2 An example of the configuration of the catalytic heater 32 is shown schematically.
[0016] Figure 3 The first temperature control of the heater control unit 64 is schematically shown.
[0017] Figure 4 The second temperature control of the heater control unit 64 is schematically shown.
[0018] Figure 5 This is a schematic diagram illustrating the modifications.
[0019] [Explanation of reference numerals in the attached image] 1: Methane purification unit 10: Flow path 20: Ozone Supply Unit 32: Catalytic heater 33: Carrier 36: Heating plate 62: Detection Unit 64: Heater control unit Detailed Implementation
[0020] <Configuration of Methane Purification Unit> Figure 1 The configuration of a methane purification device 1 according to one embodiment is shown schematically.
[0021] The methane purification device 1 is used to purify a gas containing methane. Here, the gas to be purified is air containing methane. The methane purification device 1 can be installed in factories, residences, and other locations. The methane purification device 1 includes a flow path 10, a fan 12, an ozone supply unit 20, a methane decomposition unit 30, a temperature sensor 40, a memory 50, and a control unit 60.
[0022] Flow path 10 forms a flow path through which the gas to be purified, containing methane, flows. For example, flow path 10 is a circular pipe. Flow path 10 is equipped with a fan 12, an ozone supply unit 20, a methane decomposition unit 30, and a temperature sensor 40.
[0023] Fan 12 draws the gas to be purified, containing methane, into flow path 10 by rotation. The gas to be purified drawn in by fan 12 flows to methane decomposition unit 30 located downstream of fan 12. Fan 12 is disposed in flow path 10, but this disclosure is not limited thereto, and fan 12 may also be disposed outside flow path 10.
[0024] An ozone supply unit 20 is located downstream of the fan 12 in the flow path 10, supplying ozone to the gas to be purified drawn in by the fan 12. The ozone supply unit 20 generates ozone and supplies it to the methane-containing gas to be purified. The ozone and the gas to be purified flow together to the methane decomposition unit 30. Specifically, the ozone flows to the methane decomposition unit 30 in a state of mixing with the gas to be purified.
[0025] For example, ozone supply unit 20 generates ozone by performing silent discharge treatment on the gas to be purified (i.e., the so-called silent discharge method). Specifically, ozone supply unit 20 generates ozone by applying an alternating voltage from power supply 23 to electrodes 22 covered with a dielectric material (such as glass). However, this disclosure is not limited to the above-described method; ozone supply unit 20 can also generate ozone by electrolyzing water (the so-called electrolysis method) or by irradiating the gas to be purified with ultraviolet light (the so-called ultraviolet lamp method).
[0026] The methane decomposition unit 30 is located downstream of the ozone supply unit 20 in the flow path 10, and its function is to decompose methane in the gas to be purified using ozone. The methane decomposition unit 30 includes a catalyst for decomposing methane, and decomposes methane into water and carbon dioxide by reacting ozone and methane on the catalyst.
[0027] Methane decomposes through a reaction with ozone on a catalyst, but when the catalyst temperature is low, the reaction between methane and ozone cannot proceed sufficiently, making methane difficult to decompose. This is because catalysts have the property of promoting the reaction between methane and ozone more effectively as the temperature increases.
[0028] Therefore, in this embodiment, to promote the reaction of methane and ozone on the catalyst, the methane decomposition unit 30 includes a catalytic heater 32, which serves as a heater for heating the gas to be purified and the ozone. The catalytic heater 32 supports the catalyst. In this case, the gas to be purified and the ozone, heated by the catalytic heater 32, come into contact with the catalyst, thereby increasing the temperature of the catalyst and promoting the reaction of methane and ozone on the catalyst.
[0029] Figure 2An example configuration of the catalytic heater 32 is schematically shown. The catalytic heater 32 is located downstream of the ozone supply unit 20 and is used to heat the gas to be purified passing through the ozone supply unit 20 and the ozone generated by the ozone supply unit 20. Figure 2 As shown, the catalytic heater 32 includes a carrier 33 with a honeycomb structure. The catalytic heater 32 includes a heating unit 34, which generates heat when power is supplied to the interior of the carrier 33. Therefore, the carrier 33 in this embodiment functions as a heating element.
[0030] For example, heating unit 34 includes a heating wire that converts electrical energy into heat energy. The heating wire exchanges heat with the gas to be purified and the ozone, heating the gas to be purified and the ozone, thereby increasing their temperature. Here, as... Figure 2 As shown, the carrier 33 is cylindrical, with a heating unit 34 located in its central part. However, this disclosure is not limited to this; the carrier 33 may be a rectangular parallelepiped.
[0031] The catalytic heater 32 is made of a non-metallic material. Specifically, the carrier 33 of the catalytic heater 32 is made of silicon carbide. Because silicon carbide is conductive, it generates heat when electricity is applied. Therefore, when the catalytic heater 32 is made of silicon carbide, it can easily and appropriately heat the gas to be purified and ozone in the flow path 10.
[0032] Unlike this embodiment, if the support 33 of the catalytic heater 32 is made of metal, ozone tends to react with the metal of the support 33, causing the metal to oxidize and converting the ozone into oxygen. In this case, the amount of ozone that can react with methane will be reduced. Therefore, in this embodiment, the catalytic heater 32 is made of a non-metallic material to prevent ozone reduction.
[0033] While ceramic heating elements can be used as the catalytic heater 32, the silicon carbide catalytic heater 32 heats the gas to be purified and ozone faster than the ceramic catalytic heater. Furthermore, by using silicon carbide to form a honeycomb structure, the surface area of the heating portion of the catalytic heater 32 can be increased, thereby heating the gas to be purified and ozone more effectively.
[0034] The catalytic heater 32 supports a catalyst for purifying methane by reacting ozone with methane. Specifically, the catalyst is supported by a carrier 33 of the catalytic heater 32. In other words, a catalyst layer to which the catalyst is attached is formed on the surface of the carrier 33. The catalyst in the catalyst layer includes any one of zeolite, iron-exchange zeolite, and cobalt-exchange zeolite. With this type of catalyst, ozone and methane react readily even at relatively low temperatures.
[0035] Ozone and methane come into contact with the catalyst layer of the catalytic heater 32 and react on the catalyst layer. When the catalytic heater 32 heats the gas to be purified and the ozone, the heated gas and ozone come into contact with the catalyst layer, causing the temperature of the catalyst layer to rise. Therefore, the reaction of ozone and methane on the catalyst layer is promoted.
[0036] It should be noted that in the above description, the catalytic heater 32 (specifically, the support 33) is made of silicon carbide, but this disclosure is not limited thereto. For example, the catalytic heater 32 can be made primarily of barium titanate, as long as it is made of a non-metallic material. Even in this case, it is possible to appropriately heat the gas to be purified and the ozone while preventing ozone depletion.
[0037] Furthermore, in the above description, it is assumed that the support 33 has a honeycomb structure, but this disclosure is not limited to this. As long as the catalyst can be supported on the surface of the support 33, the support 33 may also have a corrugated or mesh structure.
[0038] Back Figure 1 The configuration of the methane purification unit 1 will be described below.
[0039] Temperature sensor 40 is disposed in methane decomposition unit 30 and is used to detect the temperature around catalytic heater 32. Specifically, temperature sensor 40 detects the temperature of the gas to be purified and ozone flowing through methane decomposition unit 30. For example, temperature sensor 40 is a thermistor or thermocouple.
[0040] The memory 50 includes a storage medium such as a read-only memory (ROM), random access memory (RAM), hard disk drive (HDD), or solid-state drive (SSD). The memory 50 stores the program executed by the control unit 60 and various information used to decompose methane.
[0041] Control unit 60 includes a processor, such as a central processing unit (CPU). Control unit 60 supplies power to catalytic heater 32, causing catalytic heater 32 to heat the gas to be purified and ozone. As a result, methane and ozone react on the heated catalyst. Control unit 60 can be configured with a single processor, or with multiple processors, or a combination of one or more processors and electronic circuitry. Control unit 60 operates as both detection unit 62 and heater control unit 64 by executing programs stored in memory 50. In this embodiment, heater control unit 64 corresponds to temperature control unit 64.
[0042] The detection unit 62 detects the temperature of the catalyst in the catalytic heater 32. For example, the detection unit 62 detects the temperature of the catalyst in the catalytic heater 32 by acquiring the temperature detected by the temperature sensor 40. For example, the detection unit 62 uses the temperature detected by the temperature sensor 40 as the temperature of the catalyst. However, this disclosure is not limited to this; the detection unit 62 may also use the value obtained by multiplying the temperature detected by the temperature sensor 40 by a predetermined coefficient as the temperature of the catalyst.
[0043] The heater control unit 64 controls the operation of the catalytic heater 32, which heats the gas to be purified and the ozone. For example, when the ozone supply unit 20 begins to supply ozone to the gas to be purified, the heater control unit 64 operates the catalytic heater 32 to heat the gas to be purified and the ozone. The heater control unit 64 controls the operation of the catalytic heater 32 based on the temperature detected by the detection unit 62.
[0044] As is well known, ozone undergoes thermal decomposition when the temperature exceeds a predetermined first temperature (e.g., 150°C). When ozone undergoes thermal decomposition, the amount of ozone available to react with methane decreases. Therefore, the heater control unit 64 operates the catalytic heater 32 to keep the catalyst temperature below the first temperature for ozone decomposition. Specifically, the heater control unit 64 controls the power supply to the catalytic heater 32 so that the temperature of the catalyst detected by the detection unit 62 is below the first temperature. Therefore, during the operation of the catalytic heater 32, the thermal decomposition of ozone can be suppressed.
[0045] When ozone reacts with methane on a catalyst, carbon dioxide and water are produced as described above, and the water produced may remain on the catalyst. If water remains on the catalyst, the contact area between the catalyst and ozone and methane is reduced, thereby inhibiting the reaction between ozone and methane.
[0046] Therefore, in this embodiment, in order to suppress the state of water remaining on the catalyst, the heater control unit 64 operates the catalytic heater 32 so that the temperature of the catalyst detected by the detection unit 62 is lower than the first temperature and reaches or exceeds the second temperature of water evaporation (e.g., 100°C).
[0047] Figure 3 The first temperature control of the heater control unit 64 is schematically shown. The heater control unit 64 operates the catalytic heater 32 to bring the catalyst temperature below a first temperature E1 (150°C) and to a second temperature E2 (100°C). Here, the heater control unit 64 operates the catalytic heater 32 to bring the catalyst temperature to approximately 130°C. In this case, the state of moisture remaining on the catalyst can be suppressed while suppressing the thermal decomposition of ozone. Therefore, the reaction between ozone and methane is promoted, thereby improving the methane purification rate.
[0048] In the first temperature control described above, the heater control unit 64 operates the catalytic heater 32 to maintain a constant temperature for the catalyst, but this disclosure is not limited thereto. For example, as... Figure 4 As shown, the heater control unit 64 can alternately repeat low temperature control and high temperature control.
[0049] Figure 4 The second temperature control of the heater control unit 64 is schematically illustrated. The heater control unit 64 performs low-temperature control by operating the catalytic heater 32, maintaining the catalyst temperature detected by the detection unit 62 at a third temperature E3 (approximately 60°C) during a first time period T1, which is lower than the second temperature E2 (100°C). Furthermore, the heater control unit 64 performs high-temperature control by operating the catalytic heater 32, maintaining the catalyst temperature between the second temperature E2 and the first temperature E1 (150°C) during a second time period T2 (shorter than the first time period T1). It should be noted that the second time period T2 is shorter than the first time period T1 (e.g., 10 minutes), for example, it could be 1 minute. Furthermore, the third temperature E3 is greater than 50°C and less than 100°C.
[0050] Then, the heater control unit 64 alternately repeats the low-temperature control and high-temperature control. Specifically, the heater control unit 64 intermittently performs high-temperature control during the low-temperature control period. When the catalyst in the catalytic heater 32 is cobalt ion-exchange zeolite, the second temperature control is performed because cobalt ion-exchange zeolite has the property of promoting the reaction of methane and ozone at the third temperature (low temperature). It should be noted that, for example, the catalyst can be iron ion-exchange zeolite during the first temperature control.
[0051] By implementing a second temperature control, the reaction between methane and ozone can be promoted through low-temperature control, while moisture residue on the catalyst can be suppressed through high-temperature control.
[0052] When the catalyst is an iron-exchange zeolite or a cobalt-exchange zeolite, if the catalyst temperature exceeds 150°C, ozone can oxidize the metal components in the catalyst, resulting in ozone reduction. Conversely, in the first temperature control and the second temperature control, the heater control unit 64 can suppress ozone reduction by setting the catalyst temperature below 150°C (the first temperature).
[0053] (Revise) In the above description, the catalytic heater 32 has a honeycomb structure, but this disclosure is not limited thereto. For example, the catalytic heater 32 may have, for example, a honeycomb structure. Figure 5 The structure shown.
[0054] Figure 5 This is a schematic diagram illustrating a modified example. In Figure 5 In the middle, only the structure of the catalytic heater 32 is the same as Figure 1 The difference shown is due to the other components and Figure 1 The components are the same, so their detailed descriptions are omitted.
[0055] like Figure 5 As shown, the catalytic heater 32 according to the modified example includes a plurality of flat heating plates 36 arranged at predetermined intervals along the axial direction of the flow path 10. The heating plates 36 are made of non-metals (such as silicon carbide) and generate heat when energized. A plurality of through holes are formed on the heating plates 36 at predetermined intervals, through which the gas to be purified and ozone pass. A catalyst is supported on the surface of each heating plate 36.
[0056] Similarly, in this modification, when the gas to be purified and ozone, heated by the heating plate 36, come into contact with the catalyst, the catalyst temperature rises, thereby promoting the reaction of methane and ozone on the catalyst. Furthermore, since the heating plate 36 is made of a non-metallic material, it can suppress ozone reduction caused by reactions with metals.
[0057] It should be noted that in the above description, the methane purification device 1 purifies methane contained in the air, but this disclosure is not limited thereto. For example, the methane purification device 1 can purify methane contained in the exhaust gas emitted from an internal combustion engine such as a vehicle. In this case, the methane purification device 1 is installed in the exhaust passage of the internal combustion engine to purify the methane in the exhaust gas flowing through the exhaust passage.
[0058] <Effects of this embodiment> The methane purification device 1 in the above embodiment includes a non-metallic catalytic heater 32, which is disposed downstream of the ozone supply unit 20 in the flow path 10. The gas to be purified, containing methane, flows through the flow path, and the heater heats the gas to be purified and the ozone. The catalytic heater 32 supports the catalyst and promotes the reaction between methane and ozone to purify the methane.
[0059] When the catalytic heater 32 heats the gas to be purified and ozone, the temperature of the catalyst in the catalytic heater 32 increases. This promotes the reaction of methane and ozone on the catalyst. Furthermore, since the catalytic heater 32 is made of a non-metallic material, ozone reduction due to reactions with metals can be suppressed.
[0060] This disclosure has been described based on exemplary embodiments. The technical scope of this disclosure is not limited to the scope explained by the above embodiments, and various changes and modifications can be made within the scope of this disclosure. For example, all or part of the apparatus can be configured with any functionally or physically distributed or integrated units. Furthermore, new exemplary embodiments resulting from any combination of these are also included in the exemplary embodiments of this disclosure. Moreover, the effects of the new exemplary embodiments resulting from the combination also have the effects of the original exemplary embodiments.
Claims
1. A methane purification device comprising: a flow path through which a gas containing methane flows; an ozone supply unit that supplies ozone to the gas; and a nonmetallic heater provided in the flow path downstream of the ozone supply unit and heating the gas and ozone, wherein the heater supports a catalyst that purifies methane by reacting ozone with methane.
2. The methane purification device according to claim 1, wherein the heater includes a heating element having a honeycomb structure, and a surface of the heating element supports the catalyst.
3. The methane purification device according to claim 2, wherein the heating element is made of silicon carbide.
4. The methane purification device according to claim 1, wherein the heater includes a cylindrical carrier that supports the catalyst, and a heat generating unit that generates heat when power is supplied to the inside of the carrier.
5. The methane purification device according to claim 1, wherein the heater includes a plurality of flat plate-shaped heat generating plates arranged at predetermined intervals in the axial direction of the flow path, and a surface of each of the plurality of heat generating plates supports the catalyst.
6. The methane purification device according to claim 1, wherein the catalyst includes any one of a zeolite, an iron ion-exchanged zeolite, and a cobalt ion-exchanged zeolite.
7. The methane purification device according to claim 1, further comprising: a detection unit that detects the temperature of the catalyst; and a temperature control unit that operates the heater so that the temperature of the catalyst is lower than a first temperature at which ozone decomposes.
8. The methane purification device according to claim 7, wherein the temperature control unit operates the heater so that the temperature of the catalyst is lower than the first temperature and reaches or is higher than a second temperature at which moisture evaporates.
9. The methane purification device according to claim 7, wherein the temperature control unit alternately repeats low temperature control and high temperature control, the low temperature control being performed by operating the heater so that the temperature of the catalyst is maintained at a third temperature lower than the second temperature at which moisture evaporates for a first period of time, the high temperature control being performed by operating the heater so that the temperature of the catalyst is maintained between the second temperature and the first temperature for a second period of time shorter than the first period of time.