Cleaning system

Abstract

A purification system S comprises: a flow path section 101 in which a gas to be purified, containing methane, flows; a supply section 110, which is arranged in the flow path section 101 and supplies ozone to the gas to be purified; and a cooler 120, which is arranged downstream of the supply section 110 in the flow path section 101 and carries out a heat exchange between the gas to be purified and a heat transfer medium that cools a heat source 130, wherein the cooler 120 has a catalyst 150 that purifies the methane in the gas under an ozone atmosphere.

Description

TECHNICAL AREA

[0001] The present invention relates to a purification system that purifies methane. BACKGROUND OF THE INVENTION

[0002] There is a known catalyst that decomposes methane, an air pollutant, under an ozone atmosphere. Japanese patent application (translation of PCT application) No. 2021-505376 discloses a technology for purifying methane by heating a gas containing methane and ozone to 100 °C or higher using a heating section and then contacting the gas with a catalyst in which iron is carried on silicon dioxide, zeolite, or the like. Brief description of the invention problems that the invention is intended to solve.

[0003] However, the technology described in Japanese patent application (translation of PCT application) No. 2021-505376 requires heating the methane- and ozone-containing gas to a predetermined temperature using the heating section. Consequently, energy is consumed to heat the methane- and ozone-containing gas.

[0004] The present invention was made in consideration of these things, and one of its objectives is to reduce the energy consumed during methane purification. MEANS TO SOLVENT THE PROBLEMS

[0005] One aspect of the present invention provides a purification system comprising: a flow path section in which a gas containing methane flows; a supply section arranged in the flow path section which supplies ozone to the gas; and a cooler arranged downstream of the supply section in the flow path section which performs heat exchange between the gas and a heat transfer medium which cools a heat source, wherein the cooler has a catalyst which purifies the methane in the gas under an ozone atmosphere.

[0006] The cooler can have the catalyst on a surface of a heat dissipation fin of the cooler and / or on a surface of a conduit in which the heat transfer medium flows.

[0007] The catalyst may contain a zeolite exchanged with cobalt ions.

[0008] The supply section can add ozone to the gas if the temperature of the heat transfer medium is equal to or higher than a specified temperature, and cannot add ozone to the gas if the temperature is lower than the specified temperature.

[0009] The supply section can add ozone to the gas if the concentration of methane in the gas is equal to or higher than a threshold value, and cannot add ozone to the gas if the concentration is lower than the threshold value.

[0010] The supply section can increase the amount of ozone supplied to the gas if the concentration of methane in the gas increases.

[0011] The supply section can begin adding ozone to the gas if the temperature of the heat transfer medium has become equal to or higher than a predetermined temperature after the start-up of an engine that is the heat source; and continue adding ozone to the gas until the temperature of the heat transfer medium has become lower than the predetermined temperature after the engine has been switched off. IMPACT OF THE INVENTION

[0012] According to the invention, the energy consumed during methane purification can be advantageously reduced. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a drawing to illustrate the design of a cleaning system. Fig. Figure 2 is a schematic representation of a cooler. Fig. Figure 3 is an enlarged schematic representation of part of the cooler. Fig. Figure 4 is a diagram to illustrate a methane purification rate. Fig. Figure 5 is a flowchart that illustrates an example of a methane purification process. DETAILED DESCRIPTION OF THE INVENTION<Ausgestaltung des Reinigungssystems S>

[0013] Fig. Figure 1 is a drawing illustrating the design of a cleaning system S. For example, the cleaning system S is arranged on a vehicle or ship to which a heat source 130, such as an engine, is mounted. The cleaning system S comprises a flow path section 101, a methane sensor 102, an inlet section 103, a supply section 110, a cooler 120, the heat source 130, a heat transfer circuit 131, a temperature sensor 132, and a supply control unit 200. The cleaning system S decomposes methane to produce water and nitrogen dioxide by adding ozone to a methane-containing gas and causing the ozone and methane to react over a catalyst. In the following explanation, the decomposition of methane to produce water and nitrogen dioxide is referred to in some cases as methane purification.

[0014] A gas containing methane, to be cleaned, flows in flow path section 101. For example, the gas to be cleaned is atmospheric air. In a case where the cleaning system S is arranged on a vehicle, flow path section 101 is surrounded by other devices located in an engine compartment. In other words, flow path section 101 is a gap formed by other devices located in the engine compartment.

[0015] The methane sensor 102 is located in the flow path section 101. The methane sensor 102 detects the amount of methane in the gas to be purified at predefined time intervals. For example, the predefined time intervals are 100 milliseconds, but are not limited to this. For example, the methane sensor 102 detects the methane concentration of the gas to be purified as the amount of methane. Each time the methane sensor 102 detects the methane concentration, it outputs the detected methane concentration to the supply control unit 200.

[0016] The inlet section 103 is located within the flow path section 101. For example, the inlet section 103 is an inlet air blower. The inlet section 103 draws the gas to be cleaned into the flow path section 101. The inlet section 103 is located downstream of the methane sensor 102 within the flow path section 101. Fig. 1. The inlet section 103 draws in the gas to be cleaned in such a way that the gas to be cleaned flows in the flow path section 101 in the z-direction from the left side to the right side on the paper surface.

[0017] The supply section 110 is located between the methane sensor 102 and the inlet section 103 in the flow path section 101. The supply section 110 supplies ozone to the gas to be purified. For example, the supply section 110 has an AC power supply 111 and electrodes 112 covered with a dielectric such as glass. The supply section 110 carries out a process to generate ozone by causing the AC power supply 111 to apply an alternating voltage to the electrodes 112 (so-called silent discharge process).The supply section 110 can generate ozone by carrying out a process to cause a discharge on the surface of a dielectric covering the electrodes 112 (so-called creep discharge process), a process to electrolyze water (so-called electrolysis process), or a process to emit ultraviolet rays onto the gas to be purified (so-called ultraviolet lamp process).

[0018] The cooler 120 is located downstream of the supply section 110 in the flow path section 101. The cooler 120 is located between the supply section 110 and the inlet section 103 in the flow path section 101. The cooler 120 is located downstream of the heat source 130 in the heat transfer circuit 131, in which a heat transfer medium flows that cools the heat source 130. The cooler 120 facilitates heat exchange between the heat transfer medium and the gas to be cleaned. The cooler 120 cools the heat source 130 by supplying the heat transfer medium to the heat source 130, which has been cooled by heat exchange with the gas to be cleaned. For example, the heat transfer medium is water or ethylene glycol, but is not limited to these.

[0019] Fig. Figure 2 is a schematic representation of the cooler 120. The cooler 120 has several tubes 121 and several heat dissipation fins 122. The tubes 121 are conduits through which the heat transfer medium flows. The tubes 121 are connected to the heat transfer circuit 131 at connection point 133 and connection point 134. Specifically, the tubes 121 are connected via connection point 133 to the heat transfer circuit 131 located downstream of the heat source 130, and via connection point 134 to the heat transfer circuit 131 located upstream of the heat source 130.

[0020] The tubes 121 are arranged such that the heat transfer medium flows in the horizontal (x-direction) and vertical (y-direction) directions. The heat transfer medium supplied by the heat source 130 enters the tube 121 at the connection point 133, flows in the horizontal (x-direction), and enters the multiple tubes 121. In each tube 121, the heat transfer medium flows in the y-direction from the top to the bottom. While in the present embodiment there are five tubes 121 in which the heat transfer medium flows in the y-direction from the top to the bottom, the number of tubes can be equal to or greater than six, or equal to or less than four. The heat transfer medium exits the tubes 121 at the connection point 134, passes through the heat transfer circuit 131, and enters the heat source 130.

[0021] Each of the multiple heat dissipation fins 122 is connected to the tubes 121. Each heat dissipation fin 122 is arranged to connect two tubes 121. The respective heat dissipation fins 122 are arranged so that the gas to be cleaned can pass between each pair of heat dissipation fins 122. Gaps are arranged between the respective heat dissipation fins 122 and the respective tubes 121. The gaps are areas surrounded by the heat dissipation fins 122 and the tubes 121. When the heat transfer medium flows through the tubes 121, heat from the heat transfer medium moves to the heat dissipation fins 122, and heat exchange takes place between the gas to be cleaned, which flows through the gap, and the heat dissipation fins 122. The cooler 120 is a so-called finned cooler, but it can also be another type of cooler.

[0022] For example, heat source 130 is an engine. The engine burns and expands an air-fuel mixture of fuel and intake air (air) to generate power. For example, the engine is a diesel engine mounted on an automobile, but it could also be a gasoline engine. It should be noted that heat source 130 only needs to be a device that requires cooling and is not necessarily an engine. For example, heat source 130 could be an engine, a fuel cell, or a storage battery, and it is sufficient if heat source 130 is a device that is cooled using cooler 120.

[0023] The temperature sensor 132 is a sensor that detects the temperature of the heat transfer medium. The front end of the temperature sensor 132 is inserted into the heat transfer circuit 131 and detects the temperature of the heat transfer medium flowing through the circuit. The temperature sensor 132 outputs the detected temperature of the heat transfer medium to the supply control unit 200.

[0024] A catalyst 150 is arranged in the cooler 120. For example, the catalyst 150 is arranged on the surfaces of the tubes 121 of the cooler 120 and / or the surfaces of the heat dissipation fins 122 of the cooler 120. Fig. Figure 3 is an enlarged schematic representation of part of the cooler 120. Fig. Figure 3 shows the catalyst 150 in dark gray. The catalyst 150 is arranged on the surfaces of the heat dissipation fins 122. In particular, the catalyst 150 is arranged on both surfaces of the heat dissipation fins 122 to cover the surfaces of the heat dissipation fins 122. It should be noted that the surfaces of the heat dissipation fins 122 may have areas that are not covered by the catalyst 150.

[0025] Catalyst 150 purifies methane in the gas to be cleaned under an ozone atmosphere. Catalyst 150 purifies methane by promoting a reaction between ozone and methane on its surface, thereby decomposing methane into water and carbon dioxide. For example, Catalyst 150 contains a zeolite, an iron-ion-exchanged zeolite, and / or a cobalt-ion-exchanged zeolite. Catalyst 150 is not limited to these components; it simply needs to be a catalyst capable of purifying methane under an ozone atmosphere.

[0026] The methane purification rate of catalyst 150 changes according to the temperature. Fig. Figure 4 is a diagram illustrating the methane purification rate. The horizontal axis of Fig. Figure 4 represents the temperature of catalyst 150 (corresponding to the temperature of the heat transfer medium), and the vertical axis of Fig. 4 represents the methane purification rate. Fig. Figure 4 presents catalyst M1, catalyst M2, and catalyst M3 as types of catalyst 150. Catalyst M1 is a cobalt ion-exchanged zeolite (Co-BEA) in which cobalt is supported on a β-type framework zeolite. Catalyst M2 is an iron ion-exchanged zeolite (Fe-BEA) in which iron is supported on a β-type framework zeolite. Catalyst M3 is a β-type framework zeolite (BEA). As in Fig. As shown in Figure 4, regardless of whether the type of catalyst 150 is one of catalyst M1, catalyst M2 and catalyst M3, the methane purification rate increases with increasing temperature in a case where the temperature is lower than 150 °C.

[0027] Since the catalyst 150 is located in the cooler 120, it is heated by the heat from the cooler 120. In other words, because heat has moved from the heat source 130 to the cooler 120 via the heat transfer medium, the cleaning system S can heat the catalyst 150 to the same temperature as the heat transfer medium. This allows the cleaning system S to heat the catalyst 150 using heat from the heat source 130, without having to use a heater or similar device. Consequently, the cleaning system S can reduce the energy consumed during methane purification compared to a case where the catalyst 150 is heated using a heater or similar device.

[0028] It should be noted that, as in Fig. As shown in Figure 4, the cleaning rate of catalyst 150 decreases if its temperature rises excessively. However, in a case where the heat transfer medium is water or ethylene glycol, the temperature of the heat transfer medium does not exceed 120 °C. Accordingly, the cleaning rate of catalyst 150 is not reduced by an excessive increase in the catalyst's temperature.

[0029] Meanwhile, if the amount of methane in the gas to be purified is high, a larger amount of ozone must be added. Furthermore, adding ozone when the gas to be purified does not contain methane results in undesirable energy waste.

[0030] In light of this, the supply control unit 200 controls the amount of ozone to be supplied to the gas to be purified, according to the amount of methane contained in the gas to be purified. The design of the supply control unit 200 is explained below. The supply control unit 200 has a memory section 210 and a control section 220. The memory section 210 is a storage medium that includes a ROM (read-only memory), a RAM (random access memory), a hard disk, and the like. The memory section 210 stores programs to be executed by the control section 220.

[0031] For example, the control section 220 is a computing resource that includes a processor such as a CPU (central processing unit). By executing programs stored on the memory section 210, the control section 220 performs functions as a data acquisition section 221 and a supply control section 222.

[0032] The sensing section 221 detects the methane concentration, which is measured by the methane sensor 102. Each time the methane sensor 102 detects the methane concentration, the sensing section 221 detects the methane concentration from the methane sensor 102. The sensing section 221 also detects the temperature of the catalyst 150. Since the temperature of the catalyst 150 is approximately the same as the temperature of the heat transfer medium, the sensing section 221 can interpret the temperature of the heat transfer medium, as measured by the temperature sensor 132, as the temperature of the catalyst 150. The sensing section 221 outputs the detected methane concentration and the detected temperature of the heat transfer medium to the supply control section 222.

[0033] The supply control section 222 controls the amount of ozone to be supplied to the gas being purified. In a case where the supply section 110 supplies ozone to the gas being purified by discharge, the supply control section 222 changes the voltage and / or frequency of an alternating voltage that the AC power supply 111 applies to the electrodes 112 of the supply section 110. In particular, if the methane concentration increases, the supply control section 222 increases the amount of ozone to be supplied to the gas being purified by increasing the voltage and / or frequency of the alternating voltage that the AC power supply 111 applies to the electrodes 112.

[0034] In a case where the temperature of catalyst 150 is equal to or higher than a predetermined temperature, the supply control section 222 adds ozone to the gas to be purified. Specifically, the supply control section 222 adds ozone to the gas to be purified if the temperature of the heat transfer medium, which is detected by the detection section 221 as the temperature of catalyst 150, is equal to or higher than the predetermined temperature. The predetermined temperature is a temperature at which the methane purification rate, which indicates the amount of methane that catalyst 150 can purify, becomes equal to or higher than a predetermined value. For example, the predetermined value is 50%, and ideally, it is 80%. In a case where the catalyst is a cobalt ion-exchanged zeolite (see M1 in Fig. 4) The temperature at which the methane purification rate reaches 50% is 60°C, and the temperature at which the methane purification rate reaches 80% is 75°C. This means that if catalyst 150 is catalyst M1, the supply control section 222 will begin supplying ozone to the gas being purified when the temperature of the heat transfer medium reaches or exceeds 75°C. This allows the supply control section 222 to supply ozone if catalyst 150 is capable of sufficiently purifying the methane. Consequently, the supply control section 222 can utilize energy efficiently.

[0035] In a case where the temperature of the heat transfer medium is lower than the set temperature, the supply control section 222 does not add ozone to the gas being purified. In other words, if the methane purification rate of catalyst 150 is lower than the set value because the temperature of the heat transfer medium is low and catalyst 150 has not been heated, the supply control section 222 does not add ozone to the gas being purified. Specifically, if catalyst 150 is catalyst M1, the supply control section 222 does not add ozone to the gas being purified when the temperature of the heat transfer medium is lower than 75 °C. This allows the supply control section 222 to reduce energy waste, as it does not add ozone if the methane purification rate of catalyst 150 is low.

[0036] In a case where the methane concentration of the gas to be purified is equal to or higher than a threshold value, the supply control section 222 supplies ozone to the gas to be purified. For example, the threshold value is a lower limit at which the methane sensor 102 can detect methane. In a case where the methane concentration is equal to or higher than the threshold value, the supply control section 222 increases the amount of ozone supplied to the gas to be purified as the methane concentration increases. Specifically, as the methane concentration increases, the supply control section 222 increases the amount of ozone supplied to the gas to be purified by increasing the frequency and / or voltage value of an alternating voltage to be applied to the electrodes 112 of the supply section 110.This allows the supply control section 222 to increase the amount of ozone supplied to the gas being cleaned as the amount of methane in the gas being cleaned increases. This makes it easier for the ozone and methane to react at the catalyst 150, and the methane purification rate is increased.

[0037] In a case where the methane concentration is lower than the threshold, the supply control section 222 does not add ozone to the gas being cleaned. This allows the supply control section 222 to reduce energy waste, as it does not add ozone to the gas being cleaned if the amount of methane in the gas being cleaned is so small that the methane sensor 102 cannot detect it.

[0038] The supply control section 222 can supply ozone to the gas to be cleaned, depending on the operating state of the heat source 130. For example, the supply control section 222 begins supplying ozone after the engine, which is the heat source 130, has started up. Specifically, the supply control section 222 does not supply ozone to the gas to be cleaned while the temperature of the heat transfer medium is lower than the set temperature after the engine has started up. If the temperature of the heat transfer medium becomes equal to or higher than the set temperature after the engine has started up, the supply control section 222 begins supplying ozone to the gas to be cleaned. Thus, if the catalyst 150 has been heated and is in a state where it can sufficiently clean methane, the supply control section 222 can supply ozone to the gas to be cleaned.As a result, the supply control section 222 can efficiently use energy for methane purification.

[0039] Meanwhile, the high temperatures of the engine (heat source 130), the heat transfer medium, and the catalyst 150 persist for a while even after the engine is switched off. Therefore, the supply control section 222 continues to supply the gas to be cleaned (ozone) until the temperature of the heat transfer medium has dropped below the set temperature after the engine has been switched off. At this point, the inlet section 103 continues to draw in the gas to be cleaned. This allows the catalyst 150 to continue cleaning methane even after the engine has been switched off.

[0040] In a case where the temperature of the heat transfer medium has fallen below the specified temperature after the engine has been shut down, the supply control section 222 stops supplying ozone to the gas being cleaned. The supply control section 222 also stops the inlet section 103 after the ozone supply to the gas being cleaned has ceased. This allows the supply control section 222 to reduce energy waste, as it can prevent ozone from being supplied if the temperature of the catalyst 150 has been reduced and the methane purification rate has decreased. [Methane purification process]

[0041] Fig. Figure 5 is a flowchart illustrating an example of a methane purification process. For instance, the methane purification process is carried out after the engine, which is the heat source 130, is started.

[0042] The sensing section 221 detects the temperature of the heat transfer medium (step S1). Specifically, the sensing section 221 detects the temperature of the heat transfer medium as measured by the temperature sensor 132. The supply control section 222 determines whether the temperature of the heat transfer medium is equal to or higher than the preset temperature (step S2). If the temperature of the heat transfer medium is lower than the preset temperature (no in step S2), the supply control section 222 returns to step S1 and waits until the temperature of the heat transfer medium is equal to or higher than the preset temperature.

[0043] In a case where the temperature of the heat transfer medium is equal to or higher than the specified temperature (Yes in step S2), the detection section 221 detects the methane concentration (step S3). In particular, the detection section 221 detects the methane concentration measured by the methane sensor 102.

[0044] Supply control section 222 determines whether the methane concentration is equal to or higher than the threshold (step S4). If the methane concentration is lower than the threshold (no at step S4), supply control section 222 returns to step S3 and waits until the methane concentration is equal to or higher than the threshold.

[0045] In a case where the methane concentration is equal to or higher than the threshold (yes at step S4), the supply control section 222 adds ozone to the gas being cleaned (step S5). For example, if the methane concentration increases, the supply control section 222 increases the amount of ozone to be added to the gas being cleaned. The supply control section 222 of the supply control unit 200 repeats the processes from step S1 to step S5 until the engine is stopped.

[0046] In the event that the engine has stopped running, the supply control section 222 supplies ozone to the gas being cleaned until the temperature of the heat transfer medium falls below the set temperature. If the temperature of the heat transfer medium falls below the set temperature, the supply control section 222 stops supplying ozone to the gas being cleaned. [Effects of the cleaning system S]

[0047] As explained above, the purification system S comprises: the flow path section 101, in which the gas to be purified, containing methane, flows; the supply section 110, which is arranged in the flow path section 101 and supplies ozone to the gas to be purified; and the cooler 120, which is arranged downstream of the supply section 110 in the flow path section 101 and facilitates heat exchange between the heat transfer medium, which cools the heat source 130, and the gas to be purified. The cooler 120 includes the catalyst 150, which purifies the methane in the gas to be purified under an ozone atmosphere.

[0048] In purification system S, the catalyst 150 is heated when the temperature of the cooler 120 rises due to heat from the heat source 130, and the temperature of the catalyst 150 also rises. In this way, purification system S can heat the catalyst 150 without using a heater or similar device. Since the methane purification rate increases when the temperature of the catalyst 150 rises, purification system S can purify methane more efficiently. Furthermore, because purification system S heats the catalyst 150 using heat from the heat source 130, it can reduce the energy consumed during methane purification in atmospheric air compared to a case where a heater is used to heat the catalyst 150.

[0049] While the present invention has so far been explained using embodiments, the technical scope of the present invention is not limited to that described in the embodiments described above, but rather various modifications and alterations within the scope of a core of the present invention are possible. For example, all or some of the devices can be functionally or physically distributed or integrated into any units. Furthermore, new embodiments generated by any combination of several embodiments are also included in embodiments of the present invention. The effects of the new embodiments generated by the combination combine effects of the original embodiments. REFERENCE MARK LIST S cleaning system 101 Flow path section 102 Methane sensor 103 Entrance section 110 Supply section 120 coolers 121 pipe 122 Heat dissipation fin 130 Heat source 131 Heat transfer fluid circuit 132 Temperature sensor 150 catalyst 200 Supply tax unit 210 storage section 220 Tax Section 221 Recording section 222 Supply tax section QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2021-505376 [0002, 0003]

Claims

[1] Cleaning system (S), comprising: a flow path section (101) in which a gas containing methane flows; a supply section (110) which is arranged in the flow path section (101) and supplies the gas ozone; and a cooler (120) which is arranged downstream of the supply section (110) in the flow path section (101) and which performs a heat exchange between the gas and a heat transfer medium which cools a heat source (130), wherein The cooler (120) has a catalyst (150) that cleans the methane in the gas under an ozone atmosphere. [2] Cleaning system (S) according to claim 1, wherein the cooler (120) has the catalyst (150) on a surface of a heat dissipation fin (122) of the cooler (120) and / or a surface of a conduit in which the heat transfer medium flows. [3] Cleaning system (S) according to claim 1 or 2, wherein the catalyst (150) contains a zeolite exchanged with cobalt ions. [4] Cleaning system (S) according to one of claims 1 to 3, wherein the supply section (110) supplies the ozone to the gas if the temperature of the heat transfer medium is equal to or higher than a predetermined temperature, and does not supply the ozone to the gas if the temperature is lower than the predetermined temperature. [5] Cleaning system (S) according to any one of claims 1 to 4, wherein the supply section (110) supplies the ozone to the gas if the concentration of methane in the gas is equal to or higher than a threshold value, and does not supply the ozone to the gas if the concentration is lower than the threshold value. [6] Cleaning system (S) according to any one of claims 1 to 5, wherein the supply section (110) increases the amount of ozone supplied to the gas when the concentration of methane in the gas increases. [7] Cleaning system (S) according to any one of claims 1 to 6, wherein the supply section (110) The introduction of ozone into the gas begins if the temperature of the heat transfer medium, after starting up an engine which is the heat source (130), has become equal to or higher than a predetermined temperature; and The supply of ozone to the gas continues until the temperature of the heat transfer medium has become lower than the specified temperature after the engine has been shut down. [8] Cleaning system (S) according to any one of claims 1 to 6, wherein the flow path section (101) is surrounded by another device which is arranged in an engine compartment of a vehicle on which an engine is mounted which is the heat source (130). [9] Cleaning system (S) according to any one of claims 1 to 8, comprising: an inlet section (103) that draws the gas into the flow path section (101), wherein the inlet section (103) is located downstream of the cooler (120) in the flow path section (101). [10] Purification system (S) according to claim 4 or 7, wherein the predetermined temperature is a temperature at which an amount of the methane that the catalyst (150) can purify becomes equal to or greater than a predetermined value.

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