Methane purification system

Abstract

The water adhering to the catalyst is removed while the methane and ozone react. [Solution] The methane purification device 1 includes a pipeline 10 through which a first gas containing methane flows, an ozone supply unit 22 that supplies ozone to the first gas, a catalyst 25 that decomposes methane contained in a second gas which includes the first gas flowing through the pipeline 10 and the ozone supplied by the ozone supply unit 22, and a microwave output unit 29 that outputs microwaves around the catalyst 25 in the pipeline 10.

Description

Technical Field

[0001] The present invention relates to a methane purification device.

Background Art

[0002] The method for treating pollutants in Patent Document 1 includes methane and ozone, and by bringing a gas having a temperature within a predetermined range into contact with a catalyst, the methane contained in the gas is oxidized and removed by ozone.

Prior Art Documents

Patent Documents

[0003] [[ID=2」

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When methane and ozone are reacted on a catalyst to decompose methane, water and carbon dioxide are generated. The generated water adheres to the catalyst and blocks the region where methane and ozone contact and react on the catalyst, making it difficult for methane and ozone to react on the catalyst.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to react methane and ozone while removing water adhering to the catalyst.

Means for Solving the Problems

[0006] The methane purification device according to an aspect of the present invention includes a pipeline through which a first gas containing methane flows, an ozone supply unit that supplies ozone to the first gas, a catalyst that decomposes the methane contained in a second gas including the first gas flowing through the pipeline and the ozone supplied by the ozone supply unit, and a microwave output unit that outputs microwaves around the catalyst in the pipeline.

[0007] The pipeline may further include a first shielding plate provided upstream of the catalyst and the microwave output section, having one or more first penetrations through which the second gas passes, and blocking the microwaves; and a second shielding plate provided downstream of the catalyst and the microwave output section, having one or more second penetrations through which the second gas passes, and blocking the microwaves.

[0008] The first shielding plate may have a first through-hole whose side length or diameter is less than or equal to half the wavelength of the microwaves output by the microwave output unit, and the second shielding plate may have a second through-hole whose side length or diameter is less than or equal to half the wavelength of the microwaves output by the microwave output unit.

[0009] The system may further include a purification control unit that controls the time for supplying ozone to the ozone supply unit and the time for outputting microwaves to the microwave output unit.

[0010] The purification control unit may, immediately after the methane purification device is started, cause the microwave output unit to output microwaves, and after a predetermined time has elapsed from the time the microwave output unit starts outputting microwaves, cause the ozone supply unit to supply ozone.

[0011] The purification control unit further includes a detection unit for detecting a first concentration of methane contained in the first gas at the inlet of the pipeline and a second concentration of methane contained in the second gas flowing downstream of the catalyst in the pipeline. The purification control unit may cause the microwave output unit to output microwaves on the condition that the purification rate of the methane based on the first and second concentrations is less than a predetermined purification rate, or that the second concentration is equal to or greater than a predetermined concentration.

[0012] The purification control unit further includes a detection unit for detecting the temperature of the catalyst, and after the microwave output unit has started outputting microwaves, the purification control unit may stop outputting microwaves when the temperature of the catalyst reaches a predetermined temperature.

[0013] The purification control unit may alternately perform the process of the ozone supply unit supplying ozone and the microwave output unit outputting microwaves.

[0014] If the purification control unit is supplying ozone to the ozone supply unit and is outputting microwaves to the microwave output unit, it may reduce the output of the microwaves. [Effects of the Invention]

[0015] According to the present invention, the effect of reacting methane and ozone while removing water adhering to the catalyst is achieved. [Brief explanation of the drawing]

[0016] [Figure 1] This diagram shows an overview of the methane purification device 1 according to this embodiment. [Figure 2] This diagram shows the operation of the ozone supply unit 22 and the microwave output unit 29. [Figure 3] This figure shows an example of the processing sequence in methane purification device 1. [Modes for carrying out the invention]

[0017] Figure 1 is a diagram showing an overview of the methane purification device 1 according to this embodiment. The methane purification device 1 shown in Figure 1 comprises a pipeline 10, an intake section 11, an ozone supply section 22, a methane decomposition section 24, a microwave output section 29, a first shutoff plate 30a, a second shutoff plate 30b, a temperature sensor 31, a methane concentration sensor 37, a methane concentration sensor 38, a memory section 41, and a control section 42. The methane purification device 1 is a device that has the function of decomposing methane contained in the air to produce water and carbon dioxide.

[0018] The conduit 10 is a conduit through which methane-containing air (hereinafter referred to as "first gas") flows. The intake section 11 is, for example, an intake fan that draws the first gas into the conduit 10.

[0019] The ozone supply unit 22 is provided in the pipeline 10 downstream of the intake unit 11 and upstream of the methane decomposition unit 24, and supplies ozone to the first gas inhaled by the intake unit 11. The ozone supply unit 22 has, for example, an AC power supply 22a and an electrode 22b coated with a dielectric such as glass, and executes a process of generating ozone (so-called silent discharge method) by applying an AC voltage from the AC power supply 22a to the electrode 22b. The ozone supply unit 22 may generate ozone by executing a process of discharging on the surface of the dielectric covering the electrode (so-called surface discharge method), a process of electrolyzing water (so-called electrolysis method), or a process of irradiating ultraviolet rays to the first gas (so-called ultraviolet lamp method). The ozone supply unit 22 generates a second gas containing the first gas and ozone by supplying the generated ozone to the first gas.

[0020] The methane decomposition unit 24 is provided in the pipeline 10 downstream of the ozone supply unit 22 and houses a catalyst 25. The methane decomposition unit 24 decomposes methane to generate water and carbon dioxide, for example, by reacting ozone and methane contained in the second gas on the catalyst 25.

[0021] The catalyst 25 decomposes methane contained in the second gas including the first gas flowing through the pipeline 10 and the ozone supplied by the ozone supply unit 22. The catalyst 25 has a carrier with a predetermined structure and a coating layer supported on the surface of the carrier. The predetermined structure is, for example, a honeycomb structure, a corrugated structure, a mesh structure or a porous structure. The material of the carrier is, for example, cordierite, silicon carbide, glass wool or glass fiber. The material of the carrier preferably allows microwaves to pass through and is non-conductive, but is not limited thereto. The coating layer contains, for example, zeolite, iron ion-exchanged zeolite or cobalt ion-exchanged zeolite. Note that the region on the surface of the carrier may include a region that does not support the coating layer.

[0022] The microwave output unit 29 is provided downstream of the methane decomposition unit 24 in the pipeline 10 and outputs microwaves around the catalyst 25 in the pipeline 10. The frequency of the microwave is a frequency capable of raising the temperature of the water adhering to the catalyst 25, for example, 2.4 GHz. The microwave output unit 29 is, for example, a magnetron having a diode vacuum tube 29a and an antenna 29b, and outputs the energy generated by electrons orbiting while rotating around the cathode of the diode vacuum tube 29a as radio waves (microwaves) from the antenna 29b. By operating in this way, the microwave output unit 29 can raise the temperature of the water generated by decomposing methane and adhering to the catalyst 25 and vaporize the water. As a result, the water adhering to the catalyst 25 is removed.

[0023] The first shielding plate 30a is provided upstream of the catalyst 25 and the microwave output unit 29 in the pipeline 10, has one or more first through-holes through which the second gas passes, and shields microwaves. The first shielding plate 30a is, for example, expanded metal, art metal, punching metal or wire mesh, and has one or more first through-holes in a circular, elliptical or polygonal shape.

[0024] When the first through-hole of the first shielding plate 30a is circular, the first shielding plate 30a has a first through-hole having a diameter of a length L1 that is half or less of the wavelength λ of the microwave output by the microwave output unit 29. When the first through-hole of the first shielding plate 30a is elliptical, the first shielding plate 30a has a first through-hole having the length L1 as the major axis, and when the first through-hole is polygonal, the first shielding plate 30a has a first through-hole having the length L1 as one side. By being configured as described above, the first shielding plate 30a can allow the second gas to pass through and prevent microwaves from leaking upstream of the first shielding plate 30a in the pipeline 10.

[0025] The second shielding plate 30b is provided downstream of the catalyst 25 and the microwave output unit 29 in the pipeline 10, has one or more second through-holes through which the second gas passes, and shields microwaves. The second shielding plate 30b is, for example, expanded metal, art metal, punching metal or wire mesh, and has one or more second through-holes in a circular, elliptical or polygonal shape.

[0026] If the second penetration is circular, the second shielding plate 30b has a second penetration with a diameter of length L2 which is less than or equal to half the wavelength λ of the microwaves output by the microwave output unit 29. If the second penetration is elliptical, the second shielding plate 30b has a second penetration with a major axis which is the length L2, and if the second penetration is polygonal, the second shielding plate 30b has a second penetration with a side which is the length L2. With the above configuration, the second shielding plate 30b can allow the second gas to pass through and prevent microwaves from leaking downstream of the second shielding plate 30b in the pipeline 10. Note that the lengths L1 and L2 may be the same or different.

[0027] The temperature sensor 31 is a sensor installed on the inner wall of the methane decomposition section 24 for detecting the temperature of the second gas flowing through the methane decomposition section 24, and is, for example, a thermistor or a thermocouple. The methane concentration sensor 37 is a sensor installed upstream of the intake section 11 in the pipeline 10 for detecting the concentration of methane contained in the first gas, and the methane concentration sensor 38 is a sensor installed downstream of the catalyst 25 in the pipeline 10 for detecting the concentration of methane contained in the second gas. As an example, the methane concentration sensor 37 and the methane concentration sensor 38 detect the methane concentration by irradiating the pipeline 10 with light of a predetermined wavelength (for example, 1653 nm) and detecting the 1f (10 kHz) component and the 2f (20 kHz) component which are proportional to the light intensity.

[0028] The memory unit 41 has a storage medium such as ROM (Read Only Memory), RAM (Random Access Memory), HDD (Hard Disk Drive), or SSD (Solid State Drive). The memory unit 41 stores the program executed by the control unit 42 and various information for decomposing the methane contained in the second gas.

[0029] The control unit 42 includes a processor such as a CPU (Central Processing Unit). The control unit 42 supplies ozone to the ozone supply unit 22 by applying voltage to the AC power supply 22a. The control unit 42 raises the temperature of the water adhering to the catalyst 25 by outputting microwaves to the microwave output unit 29. The control unit 42 may consist of one processor, or it may consist of multiple processors or a combination of one or more processors and electronic circuits.

[0030] As described above, the control unit 42 operates so that the methane purification device 1 can vaporize the water adhering to the catalyst 25 by raising its temperature with microwaves output by the microwave output unit 29. As a result, the amount of water adhering to the catalyst 25 decreases, which prevents the water adhering to the catalyst 25 from blocking the areas where methane and ozone come into contact and react (so-called reaction sites), thus suppressing the difficulty of the reaction between methane and ozone on the catalyst 25. The configuration and operation of the control unit 42 will be described in detail below.

[0031] <Configuration of control unit 42> As shown in Figure 1, the control unit 42 includes a detection unit 421 and a purification control unit 424. The control unit 42 functions as the detection unit 421 and the purification control unit 424 by executing a program stored in the storage unit 41.

[0032] The detection unit 421 detects the temperature of the catalyst 25. For example, the detection unit 421 acquires the temperature of the second gas flowing through the methane decomposition unit 24, as detected by the temperature sensor 31, as the temperature of the catalyst 25. The detection unit 421 detects the first concentration of methane contained in the first gas at the inlet of the pipeline 10 and the second concentration of methane contained in the second gas flowing downstream of the catalyst 25 in the pipeline 10. For example, the detection unit 421 acquires the methane concentration detected by the methane concentration sensor 37 as the first concentration and the methane concentration detected by the methane concentration sensor 38 as the second concentration.

[0033] The purification control unit 424 controls the time for supplying ozone to the ozone supply unit 22 and the time for outputting microwaves to the microwave output unit 29. The purification control unit 424 supplies ozone to the ozone supply unit 22 by applying voltage to the AC power supply 22a, and stops supplying ozone to the ozone supply unit 22 by stopping the application of voltage to the AC power supply 22a. The purification control unit 424 outputs microwaves from the antenna 29b by applying voltage to the diode vacuum tube 29a, and stops the output of microwaves from the antenna 29b by stopping the application of voltage to the diode vacuum tube 29a.

[0034] Figure 2 shows the operation of the ozone supply unit 22 and the microwave output unit 29. The horizontal axis of Figure 2 represents time, and the vertical axis of Figure 2 represents "power supply," "intake unit 11," "ozone supply unit 22," "microwave output unit 29," and "second concentration." "Power supply" indicates whether the methane purification device 1 is powered on or not. "Intake unit 11," "ozone supply unit 22," and "microwave output unit 29" indicate whether they are operating or not. "Second concentration" indicates the second concentration of methane detected by the detection unit 421. For "power supply," "OFF" indicates the power is off and "ON" indicates the power is on. For "intake unit 11," "ozone supply unit 22," and "microwave output unit 29," "OFF" indicates the stopped state and "ON" indicates the operating state.

[0035] At time T0 shown in Figure 2, the methane purification device 1 changes from a powered-off state to a powered-on state, causing the intake unit 11 to change from a stopped state to an operating state, and to begin drawing in the first gas into the pipeline 10. Immediately after the methane purification device 1 starts up (immediately after time T0), the purification control unit 424 causes the microwave output unit 29 to output microwaves. By operating in this way, the purification control unit 424 can raise the temperature and remove (vaporize) the moisture contained in the air that has adhered to the catalyst 25 while the methane purification device 1 was powered off by outputting microwaves to the catalyst 25. After removing the moisture from the catalyst 25, the purification control unit 424 can then react methane and ozone on the catalyst 25.

[0036] Next, the purification control unit 424 stops the microwave output from the microwave output unit 29 and supplies ozone to the ozone supply unit 22 after a predetermined time has elapsed (time T1) since the microwave output unit 29 started outputting microwaves. Then, from time T1 onward, the purification control unit 424 alternately executes the process of the ozone supply unit 22 supplying ozone and the process of the microwave output unit 29 outputting microwaves.

[0037] By operating as described above, the purification control unit 424 can supply power to either the ozone supply unit 22 or the microwave output unit 29. As a result, the methane purification device 1 can reduce its power consumption. Furthermore, the purification control unit 424 can start supplying ozone to the ozone supply unit 22 immediately after the microwave output unit 29 removes the water adhering to the catalyst 25, thereby facilitating the reaction between methane and ozone on the catalyst 25.

[0038] The purification control unit 424, for example, causes the ozone supply unit 22 to supply ozone for a predetermined time P1 at a predetermined cycle P from time T1 onward. The predetermined cycle P and time P1 are values ​​corresponding to the amount of water that may adhere to the catalyst 25, calculated based on, for example, the volume of the pipeline 10, the volume of the catalyst 25, and target values ​​of the amount of methane to be purified by the methane purification device 1, and are stored in the storage unit 41. As shown in Figure 2, the purification control unit 424 causes the ozone supply unit 22 to supply ozone for a time P1 from time T1 to time T2. Subsequently, the purification control unit 424 causes the ozone supply unit 22 to supply ozone for a time P1 from time T3 to time T5, after the predetermined cycle P has elapsed from time T1.

[0039] By operating as described above, the purification control unit 424 can cause the microwave output unit 29 to output microwaves during the time P2 when the ozone supply unit 22 has stopped supplying ozone. As a result, the purification control unit 424 can vaporize the water produced by the decomposition of methane attached to the catalyst 25.

[0040] The purification control unit 424, for example, causes the microwave output unit 29 to output microwaves for a predetermined time P2 at a predetermined period P. The predetermined time P2 is a value that corresponds to the amount of water that may adhere to the catalyst 25, calculated based on, for example, the volume of the pipeline 10, the volume of the catalyst 25, and target values ​​for the amount of methane to be purified by the methane purification device 1, and is stored in the storage unit 41. As shown in Figure 2, the purification control unit 424 causes the microwave output unit 29 to output microwaves for a time P2 from time T2 to time T3. Subsequently, the purification control unit 424 causes the microwave output unit 29 to output microwaves for a time P2 from time T5 to time T6, after a predetermined period P has elapsed from time T2.

[0041] By operating as described above, the purification control unit 424 can vaporize the water adhering to the catalyst 25 at time P2 shown in Figure 2. As a result, immediately after time P2 has elapsed, the water adhering to the reaction site has been removed, making it easier for methane and ozone to react. Therefore, the purification control unit 424 can reduce the elevated second concentration at regular intervals. Specifically, the second concentration, which shows a concentration M2 at times T2 and T5, can be reduced to a concentration M1 at times T4 and T7.

[0042] The amount of water adhering to the catalyst 25 increases in a shorter time as the amount of methane in the second gas increases. Therefore, the more methane in the second gas, the less likely it is that methane and ozone will react on the catalyst 25 in a shorter time, and the second concentration will rise. Consequently, when the purification control unit 424 outputs microwaves to the microwave output unit 29 at a predetermined period P, the more methane in the second gas, the higher the probability that the timing of the microwave output is inappropriate, and the more likely the second concentration is to rise.

[0043] Therefore, the purification control unit 424 may cause the microwave output unit 29 to output microwaves on the condition that the methane purification rate based on the first concentration and second concentration detected by the detection unit 421 is less than a predetermined purification rate, or that the second concentration is equal to or greater than a predetermined concentration. The predetermined purification rate is, for example, a purification rate corresponding to a target value for the amount of methane purified by the methane purification device 1, and is stored in the storage unit 41. The predetermined concentration is, for example, a concentration corresponding to a target value for the amount of methane purified by the methane purification device 1, and is stored in the storage unit 41.

[0044] The purification control unit 424, for example, causes the microwave output unit 29 to output microwaves when the second concentration is equal to or greater than the concentration M2 shown in Figure 2. The purification control unit 424, for example, calculates the methane purification rate by dividing the second concentration by the first concentration, and if the division value is less than a predetermined purification rate, causes the microwave output unit 29 to output microwaves. By operating in this manner, the purification control unit 424 outputs microwaves when the methane concentration rises to remove (vaporize) the water adhering to the catalyst 25, making it easier for methane and ozone to react on the catalyst 25. As a result, the purification control unit 424 can output microwaves at an appropriate timing and suppress the rise in the second concentration.

[0045] Since water vaporizes at approximately 100°C (99.974°C) at 1 atmosphere, even if microwaves corresponding to temperatures above 100°C are output, the amount of water vaporized will not increase significantly. Therefore, the purification control unit 424 may, after starting the microwave output from the microwave output unit 29, stop the microwave output from the microwave output unit 29 if the temperature of the catalyst 25 detected by the detection unit 421 reaches a predetermined temperature. The predetermined temperature is, for example, 100°C. By operating in this manner, the purification control unit 424 can control the time for which the microwave output unit 29 outputs microwaves to an appropriate time.

[0046] Furthermore, the purification control unit 424 may determine a predetermined temperature based on the atmospheric pressure in the pipeline 10. For example, the purification control unit 424 acquires the atmospheric pressure detected by a pressure sensor (not shown) installed inside the pipeline 10. By referring to a table stored in the memory unit 41 that shows atmospheric pressure (vapor pressure) corresponding to temperature, the purification control unit 424 identifies the temperature corresponding to the atmospheric pressure acquired from the pressure sensor and determines that temperature to a predetermined temperature. By operating in this manner, the purification control unit 424 can improve the accuracy of the predetermined temperature, and thus can control the time for which the microwave output unit 29 outputs microwaves to a more appropriate time.

[0047] When the purification control unit 424 determines the microwave output timing based on the methane concentration or the microwave output duration based on the temperature of the catalyst 25, there may be times when both the ozone supply unit 22 and the microwave output unit 29 are operating. In this case, the methane purification device 1 consumes more power during the time when both the ozone supply unit 22 and the microwave output unit 29 are operating. Therefore, when the purification control unit 424 has the microwave output unit 29 output microwaves while the ozone supply unit 22 is supplying ozone, it may reduce the microwave output.

[0048] For example, when the purification control unit 424 is outputting microwaves from the microwave output unit 29 while ozone is not being supplied to the ozone supply unit 22 (i.e., no voltage is being applied to the AC power supply 22a), it applies a first voltage to the diode vacuum tube 29a. On the other hand, when the purification control unit 424 is outputting microwaves from the microwave output unit 29 while ozone is being supplied to the ozone supply unit 22 (i.e., voltage is being applied to the AC power supply 22a), it applies a second voltage, lower than the first voltage, to the diode vacuum tube 29a. By operating in this manner, the purification control unit 424 can suppress an increase in the power consumption of the methane purification device 1.

[0049] <Processing sequence in methane purification device 1> Figure 3 shows an example of a processing sequence in the methane purification device 1. The processing sequence shown in Figure 3 determines the timing and duration for outputting microwaves from the microwave output unit 29 based on the methane concentration and the temperature of the catalyst 25. The processing sequence shown in Figure 3 starts from the time when the power to the methane purification device 1 changes from being off to being on (for example, time T0 shown in Figure 2).

[0050] The purification control unit 424 starts the microwave output unit 29 and begins outputting microwaves in order to remove water adhering to the catalyst 25 while the methane purification device 1 is stopped (step S11). If a predetermined time has not elapsed (NO in step S12), the purification control unit 424 maintains the microwave output unit 29 in the activated state. If a predetermined time has elapsed (YES in step S12), the purification control unit 424 stops the microwave output unit 29 and stops the microwave output, and also starts the ozone supply unit 22 and begins supplying ozone (step S13).

[0051] The purification control unit 424 acquires the first concentration and the second concentration detected by the detection unit 421, and calculates the methane purification rate R by dividing the second concentration by the first concentration (step S14). If the methane purification rate R is equal to or greater than a predetermined purification rate (NO in step S15), the purification control unit 424 returns to the process in step S14. If the methane purification rate R is less than a predetermined purification rate (YES in step S15), the purification control unit 424 activates the microwave output unit 29 to start microwave output and stops the ozone supply unit 22 to stop the supply of ozone (step S16).

[0052] The detection unit 421 detects the temperature E of the catalyst 25 (step S17). If the temperature E is below a predetermined temperature (NO in step S18), the purification control unit 424 returns to the process in step S17. If the temperature E is above a predetermined temperature (YES in step S18), the purification control unit 424 stops the microwave output unit 29 to stop the microwave output and starts the ozone supply unit 22 to start supplying ozone (step S19). If the methane purification device 1 has not received an operation to terminate the process (NO in step S20), it repeats the process from steps S14 to S19. If the methane purification device 1 has received an operation to terminate the process (YES in step S20), it instructs the purification control unit 424 to stop the ozone supply unit 22 to terminate the process.

[0053] <First variation> In the above description, the operation of the methane purification device 1 in which it decomposes methane contained in air has been illustrated, but it is not limited to this. The methane purification device 1 may also decompose methane contained in exhaust gas emitted by equipment or vehicles installed in the plant. For example, the methane purification device 1 may be installed in the exhaust passage downstream of the engine of a vehicle and decompose methane contained in the engine's exhaust gas.

[0054] <Second variation> In the above description, a configuration in which the microwave output unit 29 is located downstream of the methane decomposition unit 24 in the pipeline 10 has been illustrated, but the explanation is not limited to this configuration. The microwave output unit 29 may also be located downstream of the first barrier plate 30a and upstream of the methane decomposition unit 24 in the pipeline 10.

[0055] <Third variation> In the above explanation, the operation of the intake unit 11 to begin drawing in the first gas into the pipeline 10 at the time when the methane purification device 1 is powered on (for example, time T0 shown in Figure 2) is illustrated, but the operation is not limited to this. The intake unit 11 may also begin drawing in the first gas into the pipeline 10 at the time when the microwave output unit 29, which started outputting microwaves immediately after the methane purification device 1 was powered on, stops outputting microwaves (time T1 shown in Figure 2). By operating in this manner, the methane purification device 1 can prevent the output of gas with a high concentration of methane during the time from time T0 to time T1 shown in Figure 2.

[0056] <Effects of Methane Purification Device 1> As described above, the methane purification device 1 includes a pipeline 10 through which a first gas containing methane flows, an ozone supply unit 22 that supplies ozone to the first gas, a catalyst 25 that decomposes methane contained in a second gas which includes the first gas flowing through the pipeline 10 and the ozone supplied by the ozone supply unit 22, and a microwave output unit 29 that outputs microwaves around the catalyst 25 in the pipeline 10.

[0057] With the methane purification device 1 configured in this way, the methane purification device 1 can vaporize the water produced by the decomposition of methane that adheres to the catalyst 25 by heating it with microwaves output by the microwave output unit 29. As a result, the methane purification device 1 can decompose methane by reacting methane and ozone on the catalyst 25, while suppressing the blockage of reaction sites on the catalyst 25 by the water adhering to the catalyst 25, which would hinder the reaction between methane and ozone.

[0058] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of its gist. For example, all or part of the apparatus can be configured by functionally or physically distributing and integrating in any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combinations are combined with the effects of the original embodiments. [Explanation of Symbols]

[0059] 1. Methane purification system 10 conduit 11 Intake section 22 Ozone Supply Department 22a AC power supply 22b electrode 24 Methane decomposition section 25 Catalyst 29 Microwave output section 29a diode vacuum tube 29b Antenna 30a First barrier plate 30b Second barrier plate 31 Temperature sensor 37 Methane concentration sensor 38 Methane concentration sensor 41 Storage section 42 Control Unit 421 Detection Unit 424 Purification Control Unit

Claims

1. A pipeline through which the first gas containing methane flows, An ozone supply unit that supplies ozone to the first gas, A catalyst for decomposing methane contained in a second gas which includes the first gas flowing through the pipeline and the ozone supplied by the ozone supply unit, A microwave output unit that outputs microwaves around the catalyst in the aforementioned pipeline, A methane purification device having the following features.

2. The pipeline is provided upstream of the catalyst and the microwave output section, and has one or more first penetrations through which the second gas passes, and includes a first shielding plate that blocks the microwaves, The pipeline is provided downstream of the catalyst and the microwave output section, and further comprises a second shielding plate that has one or more second penetrations through which the second gas passes and that blocks the microwaves, The methane purification apparatus according to claim 1.

3. The first shielding plate has a first through-hole whose side length or diameter is less than or equal to half the wavelength of the microwaves output by the microwave output unit. The second shielding plate has a second through-hole whose side length or diameter is less than or equal to half the wavelength of the microwaves output by the microwave output unit. The methane purification apparatus according to claim 2.

4. The system further includes a purification control unit that controls the time for supplying ozone to the ozone supply unit and the time for outputting microwaves to the microwave output unit. The methane purification apparatus according to claim 1.

5. The purification control unit causes the microwave output unit to output microwaves immediately after the methane purification device is started, and supplies ozone to the ozone supply unit after a predetermined time has elapsed from the time the microwave output unit starts outputting microwaves. The methane purification apparatus according to claim 4.

6. The system further includes a detection unit for detecting a first concentration of methane contained in the first gas at the inlet of the pipeline and a second concentration of methane contained in the second gas flowing downstream of the catalyst in the pipeline. The purification control unit causes the microwave output unit to output microwaves on the condition that the purification rate of methane based on the first concentration and the second concentration is less than a predetermined purification rate, or that the second concentration is equal to or greater than a predetermined concentration. The methane purification apparatus according to claim 4.

7. The system further includes a detection unit for detecting the temperature of the catalyst, The purification control unit, after starting the microwave output to the microwave output unit, stops the microwave output when the temperature of the catalyst reaches a predetermined temperature. The methane purification apparatus according to claim 4.

8. The purification control unit alternately executes the process of the ozone supply unit supplying the ozone and the microwave output unit outputting the microwaves. The methane purification apparatus according to claim 4.

9. When the purification control unit supplies ozone to the ozone supply unit and the microwave output unit outputs microwaves, it reduces the output of the microwaves. The methane purification apparatus according to claim 4.

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