Purification system

Abstract

To improve the efficiency of pollutant purification. [Solution] The purification system S is provided in a pipeline 101 through which a gas to be purified containing methane and oxygen flows, and includes a supply unit 110 that supplies ozone to the gas to be purified by generating ozone from the oxygen contained in the gas, a compression unit 120 provided downstream of the supply unit 110 in the pipeline 101 that adiabatically compresses the gas to be purified to which ozone has been supplied, and a catalyst 141 provided downstream of the compression unit 120 in the pipeline 101 that purifies the methane in the gas to be purified under an ozone atmosphere, and the compression unit 120 raises the temperature of the gas to be purified by adiabatically compressing it.

Description

Technical Field

[0001] The present invention relates to a purification system for purifying pollutants.

Background Art

[0002] Catalysts for decomposing pollutants in an ozone atmosphere are known. Patent Document 1 discloses a technique for purification by bringing a gas containing ozone generated from compressed air after compressing air with a compressor into contact with a catalyst.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, the higher the temperature of the gas containing ozone and pollutants, the easier it is for methane and ozone to react on the catalyst and the purification rate is improved. However, ozone is less likely to be generated as the temperature of the air serving as the generation source is higher. Therefore, when ozone is generated using compressed air compressed by a compressor and having a high temperature, the amount of ozone generated decreases compared to the case of generating ozone from low-temperature air. As a result, the ozone contacting the catalyst decreases, so that the pollutants cannot be purified and the purification rate of the pollutants decreases.

[0005] Therefore, the present invention has been made in view of these points, and an object thereof is to improve the purification rate of pollutants. [[ID=4']]]

Means for Solving the Problems

[0006] In one embodiment of the present invention, a purification system is provided comprising: a supply unit provided in a pipeline through which a gas containing methane and oxygen flows, which supplies ozone to the gas by generating ozone from the oxygen contained in the gas; a compression unit provided downstream of the supply unit in the pipeline, which adiabatically compresses the gas to which the ozone has been supplied; and a catalyst provided downstream of the compression unit in the pipeline, which purifies the methane in the gas under an ozone atmosphere, wherein the compression unit raises the temperature of the gas by adiabatically compressing it.

[0007] The pipeline includes a control valve provided downstream of the catalyst and capable of adjusting the pressure of the gas in the pipeline, and a valve control unit that can adjust the pressure of the gas by adjusting the opening degree of the control valve and thereby control the temperature of the gas after it has passed through the compression section. The valve control unit may adjust the opening degree of the control valve so that the temperature of the gas is above a predetermined temperature and below an upper limit temperature higher than the predetermined temperature.

[0008] The predetermined temperature may be a temperature at which the purification rate, which indicates the amount of methane that the catalyst can purify, becomes equal to or greater than a predetermined value.

[0009] The valve control unit may, if the temperature of the compressed gas is below the predetermined temperature, reduce the opening of the control valve to increase the pressure of the gas and thereby raise the temperature of the gas.

[0010] The valve control unit may lower the temperature of the gas by increasing the opening of the control valve to reduce the pressure of the gas if the temperature of the compressed gas is higher than the upper limit temperature.

[0011] The compression unit may increase the amount of gas drawn in per unit time as the concentration of methane in the gas increases.

[0012] The pipeline may include a removal section provided between the compression section and the catalyst, which removes at least some of the water contained in the adiabatically compressed gas.

[0013] The removal section has a water-permeable hollow fiber membrane, and when the gas, compressed in the compression section, reaches a pressure higher than the gas pressure outside the hollow fiber membrane, some of the water may be discharged to the outside of the hollow fiber membrane as the gas flows inside the hollow fiber membrane. [Effects of the Invention]

[0014] The present invention has the effect of improving the purification rate of pollutants. [Brief explanation of the drawing]

[0015] [Figure 1] This is a diagram illustrating the configuration of the purification system. [Figure 2] This is a diagram illustrating the removal process. [Figure 3] This is a diagram to explain the methane purification rate. [Figure 4] This is a flowchart illustrating an example of a methane purification process. [Modes for carrying out the invention]

[0016] <Configuration of the purification system S> Figure 1 is a diagram illustrating the configuration of the purification system S. The purification system S includes a pipeline 101, a methane sensor 102, a supply unit 110, a compression unit 120, a removal unit 130, a decomposition unit 140, a catalyst 141, a temperature sensor 150, a control valve 160, and a purification control device 200. The purification system S adds ozone to a gas containing methane and reacts the ozone and methane on a catalyst to decompose the methane and produce water and nitrogen dioxide. In the following description, the process of decomposing methane to produce water and nitrogen dioxide is sometimes referred to as "purifying methane."

[0017] A gas to be purified containing methane, which is an air pollutant showing the greenhouse effect, flows through the pipeline 101. The gas to be purified containing methane is, for example, air containing oxygen. The methane sensor 102 is provided in the pipeline 101. The methane sensor 102 detects the amount of methane in the gas to be purified. The methane sensor 102 detects, for example, the methane concentration in the gas to be purified as the amount of methane. The methane sensor 102 outputs the detected methane concentration to the purification control device 200.

[0018] The supply unit 110 is provided on the downstream side of the methane sensor 102 in the pipeline 101. The supply unit 110 supplies ozone to the gas to be purified by generating ozone from the oxygen contained in the gas to be purified. The supply unit 110 has, for example, an AC power source 111 and an electrode 112 coated with a dielectric such as glass.

[0019] The AC power source 111 applies an AC voltage to the electrode 112. For example, the AC power source 111 applies an AC power source capable of causing discharge at the electrode 112. Specifically, the AC power source 111 applies an AC voltage of 1 kV or more and 1 kHz or more to the electrode 112. More specifically, when silent discharge occurs between the electrodes 112, the AC power source 111 applies an AC voltage with a voltage of 10 kV or more and a frequency of 1 kHz or more and 100 kHz or less to the electrode 112. Also, when creeping discharge occurs on the surface of the electrode 112, the AC power source 111 applies an AC voltage with a voltage of 1kV or more and 10 kV or less and a frequency of 1 kHz or more and 10 kHz or less to the electrode 112.

[0020] When discharge occurs at the electrode 112, the electrons generated by the discharge collide with the oxygen molecules contained in the gas to be purified flowing between and around the electrodes 112. One oxygen molecule that has been collided by an electron separates into two oxygen atoms. Then, ozone is generated by the combination of the oxygen atom and the oxygen molecule. In this way, the supply unit 110 supplies ozone generated by the discharge to the gas to be purified flowing between and around the electrodes 112.

[0021] The supply unit 110 may generate ozone by irradiating the gas to be purified with ultraviolet light. In this case, the supply unit 110 has an ultraviolet lamp. When ultraviolet light irradiated from the ultraviolet lamp collides with one oxygen molecule contained in the gas to be purified, the one oxygen molecule separates into two oxygen atoms. Then, ozone is generated when the oxygen atoms and oxygen molecule combine.

[0022] The compression unit 120 is located downstream of the supply unit 110 in the pipeline 101. The compression unit 120 is a compressor that adiabatically compresses gas, and is, for example, a scroll compressor or a screw compressor, but is not limited to these. It is desirable that the compressor be capable of changing the amount of gas drawn in and discharged by changing the rotational speed.

[0023] The compression unit 120 draws in the gas to be purified to which ozone has been supplied and adiabatically compresses the drawn-in gas. By adiabatically compressing the gas to be purified, the compression unit 120 raises the pressure of the gas to be purified to a higher pressure than the pressure of the gas to be purified (atmosphere) before it was drawn in. By adiabatically compressing the gas to be purified and increasing its pressure, the compression unit 120 can raise the temperature of the gas to be purified.

[0024] Incidentally, more ozone is generated when ozone is generated from a lower temperature gas than when ozone is generated from a higher temperature gas. As described above, the purification system S adiabatically compresses the gas to be purified to which ozone is supplied. In other words, since the purification system S generates ozone from the lower temperature gas to be purified before adiabatical compression, it can generate more ozone than when ozone is generated using compressed air at a higher temperature.

[0025] The compression unit 120 sends the gas to be purified, whose temperature has been raised by adiabatic compression, to the downstream side of the compression unit 120 in the pipeline 101. In the following description, the gas to be purified that has been adiabatically compressed may be referred to as the post-compression gas.

[0026] The removal section 130 is located downstream of the compression section 120 in the pipeline 101. The removal section 130 removes at least some of the water contained in the compressed gas. Figure 2 is a diagram illustrating the removal section 130. The removal section 130 has a housing 131 and a hollow fiber membrane 132 that is permeable to water.

[0027] The housing 131 is penetrated by the conduit 101. In other words, the housing 131 contains the conduit 101. The hollow fiber membrane 132 is installed inside the housing 131. The hollow fiber membrane 132 is installed inside the housing 131 with a gap 133 between it and the wall of the housing 131. Drying gas flows through the gap 133. The drying gas is, for example, air from which water has been removed beforehand, but any gas that does not contain water will do.

[0028] The hollow fiber membrane 132 is connected to the conduit 101 at both ends. In other words, the hollow fiber membrane 132 is connected to the conduit 101a upstream of the hollow fiber membrane 132 and the conduit 101b downstream of the hollow fiber membrane 132. The hollow fiber membrane 132 is exposed to the gap 133.

[0029] The hollow fiber membrane 132 is cylindrical in shape and has through-holes 134 that penetrate in the axial direction of the hollow fiber membrane 132. The compressed gas containing water passes through the through-holes 134. The hollow fiber membrane 132 can discharge at least some of the water contained in the compressed gas containing water to the outside of the hollow fiber membrane 132. Specifically, when the compressed gas, which is at a higher pressure than the drying gas flowing outside the hollow fiber membrane 132, flows through the through-holes 134 on the inside of the hollow fiber membrane 132, the hollow fiber membrane 132 discharges some of the water from the compressed gas to the drying gas flowing through the gaps 133. In this way, the water is removed from the compressed gas containing water as it passes through the through-holes 134 of the hollow fiber membrane 132, and it is discharged from the through-holes 134 of the hollow fiber membrane 132 in a dry state.

[0030] The removal unit 130 is not limited to the hollow fiber membrane 132; water may be removed from the compressed gas using other methods. For example, the removal unit 130 may have a centrifugal water separator, which can remove some of the water contained in the compressed gas by separating it with centrifugal force.

[0031] The decomposition section 140 is located downstream of the removal section 130 in the pipeline 101. The decomposition section 140 includes a catalyst 141. The catalyst 141 has a carrier of 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, aluminum titanate, stainless steel, iron-chromium-aluminum alloy, glass wool, glass fiber, or titanium.

[0032] The coating layer purifies methane under an ozone atmosphere. The coating layer includes, for example, a zeolite that purifies methane under an ozone atmosphere, an iron ion exchange zeolite, or a cobalt ion exchange zeolite. The surface area of ​​the support may include areas that do not support the coating layer. The coating layer decomposes methane by reacting ozone and methane on its surface, producing water and carbon dioxide. As the compressed gas passes through the catalyst 141, the methane is purified, resulting in a purified gas with a lower methane content than the compressed gas.

[0033] The methane purification rate of catalyst 141 changes with temperature. Figure 3 is a diagram illustrating the methane purification rate. The horizontal axis of Figure 3 shows the temperature of catalyst 141 (corresponding to the temperature of the compressed gas), and the vertical axis shows the methane purification rate. In Figure 3, catalysts M1, M2, and M3 are shown as types of coating layers for catalyst 141. Catalyst M1 is a cobalt ion exchange zeolite (Co-BEA) in which cobalt is supported on a β-type skeletal structure zeolite. Catalyst M2 is an iron ion exchange zeolite (Fe-BEA) in which iron is supported on a β-type skeletal structure zeolite. Catalyst M3 is a β-type skeletal structure zeolite (BEA). As shown in Figure 3, for catalysts M1 and M2, when the temperature is below 150°C, the methane purification rate increases with increasing temperature. For catalyst M3, when the temperature is below 200°C, the methane purification rate increases with increasing temperature.

[0034] The catalyst 141 is heated by the heat of the compressed gas. In other words, the purification system S can heat the catalyst 141 to the same temperature as the compressed gas using the heat of the compressed gas. As a result, the purification system S can heat the catalyst 141 using the heat of the compressed gas without using a heater or the like. Consequently, the temperature of the catalyst 141 rises, increasing the methane purification rate of the catalyst 141.

[0035] However, if water adheres to the catalyst layer, the contact area between methane and ozone on the catalyst layer decreases, making it more difficult for the catalyst 141 to purify methane. In response to this, the purification system S removes some of the water contained in the gas to be purified in the removal unit 130. This makes it more difficult for water to adhere to the catalyst layer, so the purification system S can suppress the difficulty for the catalyst 141 to purify methane.

[0036] The temperature sensor 150 is a sensor that detects the temperature of the compressed gas inside the decomposition unit 140. The tip of the temperature sensor 150 is inserted into the decomposition unit 140 to detect the temperature of the compressed gas inside the decomposition unit 140. The temperature sensor 150 outputs the detected temperature of the compressed gas to the purification control device 200.

[0037] The control valve 160 is located downstream of the decomposition section 140 in the pipeline 101. The control valve 160 is a valve that can adjust the pressure of the compressed gas in the pipeline 101 by adjusting the amount of compressed gas that can pass through the control valve 160. When the opening of the control valve 160 increases, the amount of compressed gas that can pass through increases, so the pressure of the compressed gas decreases as the opening of the control valve 160 increases. When the pressure of the compressed gas decreases, the temperature of the compressed gas in the decomposition section 140 decreases. When the opening of the control valve 160 decreases, the pressure of the compressed gas in the decomposition section 140 increases, and the temperature of the compressed gas in the decomposition section 140 increases.

[0038] Incidentally, as shown in Figure 3, the methane purification rate is represented by an upward-curving graph. In other words, the methane purification rate is above a predetermined value when the temperature of the catalyst 141 is within a predetermined temperature range, and below a predetermined value when the temperature of the catalyst 141 is outside that range. Thus, in order to achieve a methane purification rate above a predetermined value, the temperature of the catalyst 141 must be within a predetermined temperature range.

[0039] Therefore, the purification control device 200 sets the temperature of the catalyst 141 within a predetermined range. The configuration of the purification control device 200 will be described below. The purification control device 200 has a storage unit 210 and a control unit 220. The storage unit 210 is a storage medium including ROM (Read Only Memory), RAM (Random Access Memory), and hard disk. The storage unit 210 stores the program to be executed by the control unit 220.

[0040] The control unit 220 is a computing resource that includes a processor such as a CPU (Central Processing Unit). The control unit 220 performs the functions of the acquisition unit 221, valve control unit 222, and supply control unit 223 by executing a program stored in the storage unit 210.

[0041] The acquisition unit 221 acquires the temperature of the catalyst 141. Since the temperature of the catalyst 141 is approximately the same as the temperature of the compressed gas, the acquisition unit 221 may acquire the temperature of the compressed gas detected by the temperature sensor 150 as the temperature of the catalyst 141. The acquisition unit 221 outputs the acquired temperature of the compressed gas to the valve control unit 222. The acquisition unit 221 also acquires the methane concentration detected by the methane sensor 102. The acquisition unit 221 outputs the acquired methane concentration to the supply control unit 223.

[0042] The valve control unit 222 can control the temperature of the compressed gas by controlling the opening degree of the control valve 160. For example, the valve control unit 222 controls the temperature of the compressed gas by adjusting the pressure of the compressed gas by adjusting the opening degree of the control valve 160. Specifically, the valve control unit 222 adjusts the opening degree of the control valve 160 so that the temperature of the compressed gas is above a predetermined temperature and below an upper limit temperature that is higher than the predetermined temperature. More specifically, the valve control unit 222 uses the following equations (1) and (2) to adjust the pressure of the compressed gas so that the temperature of the compressed gas is within a predetermined temperature range. P0V0 Κ =P1V1 Κ … (1) T0V0 Κ-1 =T1V1 Κ-1 … (2)

[0043] In equation (1), P0 is the pressure of the compressed gas before adjustment. In equation (1), P1 is the pressure of the compressed gas after adjustment. In equations (1) and (2), V0 is the volume of the compressed gas before adjustment. In equations (1) and (2), V1 is the volume of the compressed gas after adjustment. In equation (2), T0 is the temperature of the compressed gas before adjustment. In equation (2), T0 is the temperature of the compressed gas after adjustment. K is the specific heat ratio. The specific heat ratio is the ratio of the specific heat capacity at constant pressure to the specific heat capacity at constant volume, and in the case of air, it is approximately 1.4. Note that the volume of the gas to be purified in the decomposition section 140 of this embodiment does not change even when the opening of the control valve 160 is adjusted, so it remains constant. When the volume of the compressed gas is constant, the temperature and pressure of the compressed gas are proportional.

[0044] The valve control unit 222 raises the temperature of the post-compressed gas by reducing the opening of the control valve 160 to increase the pressure of the post-compressed gas when the temperature of the compressed gas is below a predetermined temperature. The predetermined temperature is the temperature at which the purification rate, which indicates the amount of methane that the catalyst 141 can purify, becomes equal to or greater than a predetermined value. The predetermined value is, for example, 50%, and preferably 80%. When the catalyst 141 is a cobalt ion exchange zeolite, the temperature at which the methane purification rate becomes 50% is 60°C, and the temperature at which the methane purification rate becomes 80% is 75°C. If the temperature of the post-compressed gas is below 60°C, which is the temperature at which the methane purification rate becomes 50%, the valve control unit 222 raises the temperature of the post-compressed gas to 60°C or higher by reducing the opening of the control valve 160 from the current opening. As a result, the valve control unit 222 can make the methane purification rate of the catalyst 141 50% or higher.

[0045] The valve control unit 222 lowers the temperature of the compressed gas by increasing the opening of the control valve 160 to reduce the pressure of the compressed gas when the temperature of the compressed gas is higher than the upper limit temperature. The upper limit temperature is the temperature at which the purification rate falls below a predetermined value as the temperature of the catalyst 141 rises. When the catalyst 141 is a cobalt ion exchange zeolite, the temperature at which the methane purification rate becomes 80% as the temperature of the catalyst 141 rises is 160°C, and the temperature at which the methane purification rate becomes 50% is 175°C. If the temperature of the compressed gas is higher than 175°C, at which the purification rate becomes 50%, the valve control unit 222 increases the opening of the control valve 160 beyond its current opening to lower the temperature of the compressed gas to 175°C or lower. As a result, the valve control unit 222 can make the methane purification rate of the catalyst 141 50% or higher.

[0046] In this way, the valve control unit 222 can adjust the temperature of the compressed gas by adjusting the opening degree of the control valve 160, thereby making it possible to set the temperature of the compressed gas above a predetermined temperature and below an upper limit temperature. Specifically, when the catalyst 141 is cobalt ion exchange zeolite, the valve control unit 222 sets the temperature of the compressed gas between 60°C and 175°C. As a result, the valve control unit 222 can achieve a methane purification rate of 50% or more. In this way, the valve control unit 222 can improve the methane purification rate compared to when the temperature of the compressed gas is not adjusted.

[0047] The valve control unit 222 may adjust the temperature of the compressed gas to remove water adhering to the catalyst 141. For example, the valve control unit 222 may raise the temperature of the compressed gas to 80°C or higher. In this way, the heat from the compressed gas heats the catalyst 141, raising its temperature and making it easier for the water adhering to the catalyst 141 to evaporate. In other words, by raising the temperature of the compressed gas to 80°C or higher, the valve control unit 222 can remove the water adhering to the catalyst 141, thereby suppressing a decrease in the methane purification rate.

[0048] The supply control unit 223 controls the operation of the compression unit 120 according to the methane concentration of the gas to be purified. For example, the supply control unit 223 causes the compression unit 120 to draw in the gas to be purified when the methane concentration of the gas to be purified is above a threshold. The threshold is, for example, the lower limit at which the methane sensor 102 can detect methane. When the methane concentration is above the threshold, the supply control unit 223 increases the amount of gas to be purified drawn in by the compression unit 120 per unit time as the methane concentration increases. Specifically, the supply control unit 223 increases the amount of gas drawn in by the compression unit 120 by increasing the rotation speed of the compression unit 120 as the methane concentration increases. As a result, the purification system S can purify a larger amount of gas because it draws in more gas when the methane concentration is high.

[0049] The supply control unit 223 supplies ozone to the gas to be purified after the compression unit 120 starts operating. For example, while the compression unit 120 is operating, the supply control unit 223 increases the amount of ozone supplied to the gas to be purified as the amount of suction of the compression unit 120 increases. Specifically, when the supply unit 110 supplies ozone to the gas to be purified by discharge, the supply control unit 223 increases the amount of ozone supplied to the gas to be purified by increasing at least one of the voltage and frequency of the AC voltage applied by the AC power supply 111 to the electrode 112 of the supply unit 110. As a result, more ozone is supplied the greater the amount of gas to be purified, making it easier for ozone and methane to react on the catalyst 141.

[0050] The supply control unit 223 prevents the compression unit 120 from drawing in the gas to be purified if the methane concentration is below a threshold. In other words, the supply control unit 223 stops the operation of the compression unit 120. When the compression unit 120 is stopped, the supply control unit 223 does not supply ozone to the gas to be purified. As a result, when the amount of methane in the gas to be purified is so low that the methane sensor 102 cannot detect it, the purification system S does not draw in the gas to be purified by the compression unit 120 and does not generate ozone, thus suppressing energy waste.

[0051] [Process to purify methane] Figure 4 is a flowchart showing an example of a methane purification process. The methane purification process is performed after the compression unit 120 starts sucking in the gas to be purified and the supply unit 110 starts supplying ozone to the gas to be purified.

[0052] The acquisition unit 221 acquires the temperature of the compressed gas (step S1). For example, the acquisition unit 221 acquires the temperature of the compressed gas detected by the temperature sensor 150.

[0053] The valve control unit 222 determines whether the temperature of the compressed gas is below a predetermined temperature (step S2). If the temperature of the compressed gas is below the predetermined temperature (Yes in step S2), the valve control unit 222 closes the control valve 160 (step S3). Specifically, the valve control unit 222 increases the pressure of the compressed gas by closing the control valve 160 and reducing the opening of the control valve 160. As the pressure of the compressed gas increases, the temperature of the compressed gas also increases. By closing the control valve 160, the valve control unit 222 raises the temperature of the compressed gas to above the predetermined temperature.

[0054] If the temperature of the compressed gas is above a predetermined temperature (No in step S2), the valve control unit 222 determines whether the temperature of the compressed gas is above the upper limit temperature (step S4). If the temperature of the compressed gas is above the upper limit temperature (Yes in step S4), the valve control unit 222 opens the control valve 160 (step S5). Specifically, the valve control unit 222 lowers the pressure of the compressed gas by opening the control valve 160 and increasing the opening degree of the control valve 160. As the pressure of the compressed gas decreases, the temperature of the compressed gas decreases. By opening the control valve 160, the valve control unit 222 lowers the temperature of the compressed gas to below the upper limit temperature. If the temperature of the compressed gas is below the upper limit temperature (No in step S4), the valve control unit 222 maintains the opening degree of the control valve 160 and returns to step S1.

[0055] The valve control unit 222 repeats the process from step S1 to step S5 while the compression unit 120 is operating. The purification control device 200 terminates the methane purification process when the compression unit 120 stops operating or when it receives an instruction to stop the methane purification process.

[0056] [Effects of the Purification System S] As described above, the purification system S is installed in a pipeline 101 through which a gas to be purified containing methane and oxygen flows, and includes a supply unit 110 that supplies ozone to the gas by generating ozone from the oxygen contained in the gas to be purified, a compression unit 120 installed downstream of the supply unit 110 that adiabatically compresses the gas to be purified to which ozone has been supplied, and a catalyst 141 installed downstream of the compression unit 120 that purifies the methane in the gas to be purified under an ozone atmosphere. The compression unit 120 raises the temperature of the gas to be purified by adiabatically compressing it.

[0057] As described above, the purification system S generates ozone from oxygen contained in the gas to be purified at a low temperature before adiabatic compression, and raises the temperature of the gas to be purified by adiabatic compression. Since more ozone is generated when generating ozone from a low-temperature gas than when generating ozone from a high-temperature gas, the purification system S can generate more ozone than when generating ozone using high-temperature compressed air. As a result, the purification system S can increase the amount of ozone that comes into contact with the catalyst 141. Consequently, the purification system S can increase the probability that methane and ozone react on the catalyst 141, thereby improving the purification rate of methane, an air pollutant that exhibits a greenhouse effect.

[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] S Purification System 101 Pipeline 102 Methane Sensor 110 Supply section 120 Compression section 130 Removal section 131 cabinets 132 Hollow fiber membrane 134 Through hole 140 Disassembly section 141 Catalyst 150 Temperature Sensor 160 Control valve 200 Purification control device 210 Storage section 220 Control Unit 221 Acquisition Department 222 Valve control unit 223 Supply Control Unit

Claims

1. A supply unit is provided in a pipeline through which a gas containing methane and oxygen flows, and supplies ozone to the gas by generating ozone from the oxygen contained in the gas, A compression section is provided downstream of the supply section in the pipeline and adiabatically compresses the gas to which the ozone has been supplied, A catalyst is provided in the pipeline downstream of the compression section to purify the methane in the gas under an ozone atmosphere, It has, The compression unit raises the temperature of the gas by adiabatically compressing it. Purification system.

2. A control valve is provided downstream of the catalyst in the pipeline and capable of adjusting the pressure of the gas in the pipeline, The system includes a valve control unit capable of controlling the temperature of the gas after it has passed through the compression section by adjusting the opening degree of the control valve, The valve control unit adjusts the opening degree of the control valve so that the temperature of the gas is above a predetermined temperature and below an upper limit temperature higher than the predetermined temperature. The purification system according to claim 1.

3. The predetermined temperature is the temperature at which the purification rate, which indicates the amount of methane that the catalyst can purify, becomes equal to or greater than a predetermined value. The purification system according to claim 2.

4. The valve control unit, when the temperature of the compressed gas is below the predetermined temperature, reduces the opening of the control valve to increase the pressure of the gas and thereby raise the temperature of the gas. The purification system according to claim 2.

5. The valve control unit, when the temperature of the compressed gas is higher than the upper limit temperature, increases the opening of the control valve to lower the pressure of the gas and thereby lower the temperature of the gas. The purification system according to claim 2.

6. The compression unit increases the amount of gas drawn in per unit time as the concentration of methane in the gas increases. The purification system according to claim 5.

7. The pipeline is provided between the compression section and the catalyst and has a removal section that removes at least some of the water contained in the adiabatically compressed gas, A purification system according to any one of claims 1 to 6.

8. The removal section has a water-permeable hollow fiber membrane, and when the gas, which has become more pressure than the gas outside the hollow fiber membrane due to compression in the compression section, flows inside the hollow fiber membrane, a portion of the water is discharged to the outside of the hollow fiber membrane. The purification system according to claim 7.

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