Plasma apparatus and method for decomposing gases

Abstract

The present disclosure relates to a plasma device and method. The plasma device includes an inner electrode and an outer electrode. The inner electrode includes a wall defining a first cavity, the opening of the first cavity being configured to receive a first gas. The outer electrode surrounds the inner electrode. The inner electrode has a through-hole extending through the wall of the inner electrode, and the first cavity is in fluid communication with a plasma generation region between the inner electrode and the outer electrode via the through-hole. The inner electrode is rotatable about a first rotation axis, the first rotation axis extending through the first cavity. In particular, some embodiments of the present disclosure relate to a plasma device and method for decomposing gases.

Description

[Technical Field]

[0001] (Related Applications) This application claims priority to U.S. Provisional Patent Application No. 63 / 391,421, filed July 22, 2022, and entitled "Method for simultaneous production of carbon and hydrogen by plasma cracking of hydrocarbon gas," the entire contents of which are incorporated herein by reference.

[0002] (Technical field) FIELD OF THE DISCLOSURE The present disclosure relates to plasma devices and methods, and in particular, some embodiments of the present disclosure relate to plasma devices and methods for decomposing gases. [Background technology]

[0003] Plasma is considered the fourth state of matter beyond solids, liquids, and gases. Plasma is defined as a state of matter in which electrons, ions, and electrically neutral particles coexist in the same space. Plasma technology is widely used in many industries. Interacting with matter using high-energy particles in plasma can enhance reactions. Plasma is classified into vacuum plasma, atmospheric pressure plasma, and high-pressure plasma based on the operating environment and pressure, each of which has its own application area. For example, vacuum plasma is commonly used for coating. The material to be coated is targeted and placed on a cathode. An additional gas, such as argon, is used as a working gas (or carrier gas), and a voltage is applied to generate plasma from the working gas. By colliding the plasma with the target, material is sputtered onto the substrate to be coated, achieving a coating on the substrate. Atmospheric pressure plasma is commonly used for applications such as surface modification and cleaning. The working gas used in atmospheric pressure plasma processing can include nitrogen, oxygen, argon, air, or a combination of the aforementioned gases. The working gas is used to generate plasma at atmospheric pressure. The generated plasma is typically applied to the surface of an object for surface treatment applications.

[0004] When using plasma to decompose hydrocarbons into hydrogen and carbon, the carbon produced during the decomposition process coats the electrodes, stopping the generation of plasma and the plasma decomposition of hydrocarbons. To avoid this problem, nitrogen, oxygen, argon, air, or a combination of the aforementioned gases is used as the main working gas to generate the plasma. As a result, in some cases, only a small amount (e.g., less than 10%) of hydrocarbon gas enters the device, resulting in relatively low dissociation efficiency and product yield. Summary of the Invention

[0005] According to the present disclosure, a plasma device is provided. The plasma device includes an inner electrode and an outer electrode. The inner electrode includes a wall defining a first cavity, the opening of the first cavity being configured to receive a first gas. The outer electrode surrounds the inner electrode. The inner electrode has a through-hole extending through the wall of the inner electrode, and the first cavity is in fluid communication with a plasma generation region between the inner electrode and the outer electrode via the through-hole. The inner electrode is rotatable about a first rotation axis, the first rotation axis passing through the first cavity.

[0006] In one embodiment, both the inner and outer electrodes are substantially tubular.

[0007] In one embodiment, the outer electrode is positioned coaxially with the inner electrode.

[0008] In one embodiment, the plasma apparatus further comprises a rotating member mechanically coupled to the inner electrode such that the inner electrode can rotate about a first axis of rotation.

[0009] In one embodiment, the rotating member comprises a bearing or a rotor.

[0010] In one embodiment, the plasma apparatus further comprises a motor coupled to the inner electrode and configured to provide a rotational drive force to rotate the inner electrode about the first axis of rotation.

[0011] In one embodiment, the through-hole is configured to obtain a rotational driving force from a flow of the first gas from the first cavity through the through-hole to the plasma generation region, the rotational driving force rotating the inner electrode about the first axis of rotation.

[0012] In one embodiment, a first angle between the extension direction of the through hole and the radial direction of the through hole on a cross-sectional plane of the inner electrode is between about 5 degrees and about 85 degrees, and the cross-sectional plane is perpendicular to the longitudinal axis of the inner electrode.

[0013] In one embodiment, the second angle between the extension direction of the through hole and the axial direction is between about 5 degrees and about 85 degrees, and the axial direction is coincident with the longitudinal axis of the inner electrode and extends from a point within the first cavity toward the opening of the first cavity.

[0014] In one embodiment, the plasma apparatus further comprises a gas inlet configured to allow a flow of a first gas into the first cavity.

[0015] In one embodiment, the plasma apparatus further comprises a gas container coupled to the gas inlet, the gas container containing a first gas.

[0016] In one embodiment, the plasma device further comprises an insulating layer disposed annularly between the outer electrode and the inner electrode.

[0017] In one embodiment, the plasma apparatus further comprises a power supply electrically connected to both the inner electrode and the outer electrode, the power supply configured to provide a voltage between the inner electrode and the outer electrode.

[0018] In one embodiment, the plasma apparatus further comprises a scraping unit configured to move in contact with the outer surface of the inner electrode.

[0019] In one embodiment, the scraping unit surrounds the outer surface of the inner electrode and is configured to move in a first direction along a longitudinal axis of the inner electrode and in a second direction opposite the first direction.

[0020] In one embodiment, the scraping unit includes a first blade, a second blade, and a connector connecting the first blade and the second blade, wherein the first blade is configured to move in contact with an outer surface of the inner electrode, and the second blade is configured to move in contact with an inner surface of the outer electrode.

[0021] In one embodiment, the plasma device further comprises an outlet configured to exit the second gas and the solid product formed from the first gas.

[0022] In one embodiment, the plasma apparatus further comprises a separation device connected to the outlet, the separation device configured to separate the solid product from the second gas.

[0023] In one embodiment, the separation device comprises a dust collector and a filter screen connected to the dust collector.

[0024] In one embodiment, the plasma apparatus further comprises a bottom cover connected to the outer electrode at an end of the outer electrode, and the outlet is disposed in the bottom cover.

[0025] In one embodiment, the outer electrode includes gas piping embedded in a wall of the outer electrode, the gas piping configured to introduce a first gas into the plasma generating region.

[0026] In one embodiment, the first gas comprises a hydrocarbon gas.

[0027] According to the present disclosure, a method is provided. The method includes introducing a first gas into a first cavity defined by a wall of an inner electrode through an opening in the first cavity. The method includes flowing the first gas from the first cavity through a through-hole penetrating the wall of the inner electrode to a plasma generation region between the inner electrode and an outer electrode surrounding the inner electrode. The method includes generating plasma in the plasma generation region by applying a voltage between the inner electrode and the outer electrode. The method includes decomposing the first gas using the plasma. The method includes rotating the inner electrode about a first rotation axis, the first rotation axis penetrating the first cavity.

[0028] In one embodiment, generating the plasma comprises generating the plasma from a portion of the first gas.

[0029] In one embodiment, the first gas comprises a hydrocarbon gas.

[0030] In one embodiment, the method further comprises passing products produced from the decomposition of the first gas through the outlet.

[0031] In one embodiment, the products comprise a second gas and a solid product.

[0032] In one embodiment, the method further comprises separating the solid product from the second gas by a separation device.

[0033] In one embodiment, the method further comprises admitting the second gas to the generator.

[0034] In one embodiment, rotating the inner electrode comprises obtaining a rotational driving force from a flow of the first gas from the first cavity through the through-hole to the plasma generating region.

[0035] In one embodiment, rotating the inner electrode comprises providing a rotational drive force from a motor coupled to the inner electrode.

[0036] In one embodiment, the method further comprises removing the solid products adhering to the inner electrode with a scraping unit.

[0037] In one embodiment, the method further comprises cooling the inner electrode by flowing a first gas from the first cavity through the through-holes to the plasma generating region.

[0038] In one embodiment, introducing the first gas comprises introducing the first gas into the first cavity from a gas container.

[0039] In one embodiment, the method further comprises heating the first gas before the first gas is introduced into the first cavity.

[0040] In one embodiment, the method further comprises introducing a first gas into the plasma generating region through gas piping embedded in the wall of the outer electrode. [Brief explanation of the drawings]

[0041] [Figure 1A] 1 is a schematic diagram of a plasma device according to one embodiment of the present disclosure. [Figure 1B] 1 is a schematic diagram of a plasma device according to one embodiment of the present disclosure. [Figure 2] 1 is a schematic diagram of a plasma device according to one embodiment of the present disclosure. [Figure 3A] FIG. 2 is a schematic diagram of an inner electrode according to one embodiment of the present disclosure. [Figure 3B] FIG. 2 is a schematic diagram of an inner electrode according to one embodiment of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram of an inner electrode according to one embodiment of the present disclosure. [Figure 5A] FIG. 1 is a schematic diagram of a scraping unit according to one embodiment of the present disclosure. [Figure 5B] FIG. 1 is a schematic diagram of a scraping unit according to one embodiment of the present disclosure. [Figure 6] FIG. 1 is a schematic cross-sectional view of a scraping unit according to one embodiment of the present disclosure. [Figure 7] 1 is a schematic diagram of a plasma device according to one embodiment of the present disclosure. [Figure 8] 1 is a schematic diagram of a plasma device according to one embodiment of the present disclosure. [Figure 9] 1 is a flowchart illustrating a method according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0042] The terms used in the description provided below are intended to be interpreted in the broadest and most reasonable manner, even when used in conjunction with the detailed description of specific embodiments of the technology. Certain terms may be emphasized below, but any terms intended to be interpreted in a restrictive manner will also be specifically defined in this detailed description section. Components and results of the plasma device according to the present disclosure may be illustrated in the following drawings and embodiments. However, the size and shape of the plasma device illustrated in the drawings do not limit the features of the present disclosure.

[0043] The term "above," as used herein, can mean directly above or indirectly above via an intervening element or layer. For convenience, spatially relative terms such as "below," "below," "lower," "above," and "upper" may be used herein to describe the relationship of one element or feature to another, as illustrated in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were inverted, elements described as being "below" or "below" other elements or features would now be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. A device may be oriented differently (rotated 90 degrees or at another orientation), and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0044] 1A and 1B are schematic diagrams of a plasma device according to one embodiment of the present disclosure. FIG. 1B is a schematic cross-sectional view of the plasma device of FIG. 1A taken along line A-A'. As shown in FIGS. 1A and 1B, the plasma device 100 includes an inner electrode 104 and an outer electrode 105. The inner electrode 104 includes a wall 104a defining a first cavity 119, and an opening 104b of the first cavity 119 is configured to receive a first gas 109. The outer electrode 105 surrounds the inner electrode 104 and defines a plasma generation region 106 between the inner electrode 104 and the outer electrode 105. The inner electrode 104 may have a through-hole 118 penetrating the wall 104a of the inner electrode 104, thereby fluidly connecting the first cavity 119 to the plasma generation region 106 between the inner electrode 104 and the outer electrode 105 via the through-hole 118. Thus, the first gas 109 can flow through the opening 104b into the first cavity 119 and then into the plasma generation region 106 via the through-holes 118. In some embodiments, the inner electrode 104 can have multiple through-holes 118 that penetrate the wall 104a of the inner electrode 104.

[0045] The inner electrode 104 may comprise stainless steel, copper, graphite, molybdenum, aluminum, any suitable conductive material, or a combination thereof. The outer electrode 105 may comprise stainless steel, aluminum, any suitable conductive material, or a combination thereof. In the embodiment illustrated in FIGS. 1A and 1B , the inner electrode 104 is substantially tubular, and the opening 104b of the first cavity 119 is located at a first end 104e of the inner electrode 104. A second end 104f of the inner electrode 104 opposite the first end 104e may be closed. However, the present disclosure is not limited thereto. The outer electrode 105 may also be substantially tubular. In some embodiments, the outer electrode 105 is disposed coaxially with the inner electrode 104. In some embodiments, the gap between the inner electrode 104 and the outer electrode 105 is constant. Although the inner electrode 104 and the outer electrode 105 are illustrated as having a constant radius along their longitudinal axes, in some embodiments, the radius of the inner electrode 104 and the outer electrode 105 may vary along their longitudinal axes. For example, the inner electrode 104 and / or the outer electrode 105 may be hollow cone-shaped.

[0046] As shown in FIGS. 1A and 1B , the outer electrode 105 surrounds the second end 104f of the inner electrode 104. In some embodiments, the length of the inner electrode 104 is shorter than the length of the outer electrode 105. In some embodiments, the inner electrode 104 may have a length of about 20 mm to about 300 mm. In some embodiments, the outer electrode 105 may have a length of about 30 mm to about 500 mm. The inner electrode 104 may have an inner diameter 104i of about 5 mm to about 50 mm and an outer diameter 104o of about 20 mm to about 70 mm. The wall 104a of the inner electrode 104 may have a thickness of about 7.5 mm to about 10 mm. The outer electrode 105 may have an inner diameter 105i of about 25 mm to about 100 mm and an outer diameter 105o of about 30 mm to about 110 mm. The wall 105a of the outer electrode 105 may have a thickness of about 2.5 mm to about 5 mm. These values are merely examples and are not intended to be limiting.

[0047] The inner electrode 104 is rotatable about a first rotation axis 104c, which passes through the first cavity 119 of the inner electrode 104. In some embodiments, the first rotation axis 104c may coincide with the longitudinal axis of the inner electrode 104 (e.g., the longitudinal axis 104n illustrated in FIGS. 3A, 3B, and 4). In other words, the inner electrode 104 may be rotatable about its longitudinal axis. As used herein, the longitudinal axis may refer to an axis that passes through the center of gravity of the inner electrode 104 along its length, for example, from the first end 104e to the second end 104f of the inner electrode 104. Specifically, the plasma device 100 is configured such that the inner electrode 104 can be rotationally driven, particularly during operation of the plasma device 100. In some embodiments, the plasma device further includes a device, such as a motor, for providing a rotational driving force to rotate the inner electrode (as described in more detail below with respect to FIG. 7). In some embodiments, the inner electrode can be configured to be driven to rotate by a flow of the first gas through the wall of the inner electrode (as described in more detail below with respect to FIGS. 3A and 3B). This can mitigate the problem of solid product buildup on the outer surface of the inner electrode 104 during plasma decomposition, allowing the plasma device 100 to continue operating for a reasonable period of time without introducing additional working gas. Therefore, dissociation efficiency and product yield can be improved, and undesirable by-products formed by reaction with the additional working gas can be avoided. Furthermore, maintenance frequency and downtime of the plasma device due to solid product buildup can be reduced.

[0048] 1A and 1B, the plasma device 100 further includes a gas inlet 102. The gas inlet 102 may be coupled to the inner electrode 104 at an opening 104b of the first cavity 119 and may be configured to allow a first gas 109 to flow into the first cavity 119.

[0049] In some embodiments, the plasma device 100 further comprises a gas container 108. The gas container 108 may contain a first gas 109 and may be coupled to a gas inlet 102 that provides the first gas 109 to the first cavity 119 for plasma decomposition. In some embodiments, the gas container 108 may be a pressurized gas container. In one embodiment, the plasma device 100 may further comprise a gas inlet valve 101 configured to control the flow rate of the first gas 109 to the first cavity 119. In some embodiments, the first gas 109 comprises a hydrocarbon gas such as an alkane, an alkene, a cycloalkane, or an aromatic hydrocarbon, including but not limited to, methane, ethane, propane, butane, ethylene, natural gas, compressed natural gas (CNG), petroleum gas, and combinations thereof. In some embodiments, the first gas 109 may comprise a gas vaporized from a hydrocarbon liquid, such as an alkane, an alkene, a cycloalkane, or an aromatic hydrocarbon, including but not limited to, hexane, diesel, gasoline, kerosene, and combinations thereof. The hydrocarbon liquid may be vaporized to a gaseous state by heating in a vaporizer. In some embodiments, the first gas 109 is a pure or substantially pure hydrocarbon, and impurities may need to be filtered to provide a substantially pure hydrocarbon. In some embodiments, the first gas 109 may be filtered through a filter before entering the first cavity 119. In some embodiments, the first gas 109 may be preheated before entering the first cavity 119, thereby increasing the dissociation efficiency of the first gas 109. For example, the first gas 109 may flow through a waste heat recycling system and be heated by recycled waste heat from a power plant.

[0050] 1A, the plasma device 100 further includes a power supply 107. The power supply 107 is electrically connected to both the inner electrode 104 and the outer electrode 105 and configured to provide a voltage between the inner electrode 104 and the outer electrode 105 to generate plasma in the plasma generation region 106. In some embodiments, the plasma is generated from a portion of the first gas 109. The plasma may decompose molecules of the first gas 109 and break chemical bonds therein. As a result, the first gas 109 may be dissociated, and products such as a second gas 125 and a solid product 124 may be generated. In situations where the first gas includes a hydrocarbon, the hydrocarbon molecules may be dissociated, and carbon and hydrogen may be generated.

[0051] In some embodiments, the power supply 107 comprises a direct current (DC) power supply and / or an alternating current (AC) power supply. In the embodiment illustrated in FIG. 1A, the outer electrode 105 may be grounded. In some embodiments, the magnitude of the voltage and / or frequency of the power supply may be adjusted to achieve higher conversion rates and / or higher energy efficiency.

[0052] 1A, the plasma apparatus 100 may further include an insulating layer 103 between the outer electrode 105 and the inner electrode 104. The insulating layer 103 may be annularly disposed and may encase a portion of the inner electrode 104, thereby electrically insulating the inner electrode 104 from the outer electrode 105. The insulating layer 103 may comprise Teflon, ceramic, any suitable insulating material, or a combination thereof. In some embodiments, the insulating layer 103 provides an airtight seal to prevent gases (e.g., the first gas 109 and the second gas 125) from leaking from a gap between the inner electrode 104 and the outer electrode 105.

[0053] In the embodiment illustrated in FIG. 1A, the plasma device 100 further includes a bottom cover 111 connected to the outer electrode 105. Specifically, as illustrated in FIG. 1A, the insulating layer 103 is coupled to the outer electrode 105 at a first end 105e of the outer electrode 105, and the bottom cover 111 is connected to the outer electrode 105 at a second end 105f opposite the first end 105e of the outer electrode 105. In some embodiments, the bottom cover 111 may comprise a non-conductive material such as quartz, glass, plastic, any suitable insulating material, and combinations thereof. In some embodiments, the bottom cover 111 may comprise a conductive material such as stainless steel, any suitable conductive material, and combinations thereof. The bottom cover 111 may be connected to the outer electrode 105 by a gasket, adhesive, welding, and / or other suitable methods. The connection between the bottom cover 111 and the outer electrode 105 may be airtight. The airtight configuration allows the plasma device to function without an additional outer casing, enhances the dissociation efficiency of the first gas, and allows the gas pressure inside the outer electrode to be set to a higher pressure (e.g., 100 bar, depending on the airtightness of the plasma device) and be easier to control. By using a gasket or welding, the connection between the bottom cover 111 and the outer electrode 105 can form a stronger airtight seal. As shown in FIG. 1A , the plasma device 100 further includes an outlet 116. The outlet 116 is configured to discharge the second gas 125 and the solid product 124 generated from the first gas 109. In the embodiment shown in FIG. 1A , the outlet 116 is disposed in the bottom cover 111. However, the present disclosure is not limited thereto.

[0054] In the embodiment illustrated in FIG. 1A, the plasma apparatus 100 further includes a separation device 117 connected to the outlet 116. The separation device 117 is configured to separate the solid product 124 from the second gas 125. As illustrated in FIG. 1A, the separation device 117 may include a precipitator 120 and a filter screen 121 connected to the precipitator 120. In embodiments in which the first gas 109 includes a hydrocarbon gas, the separation device 117 may separate the solid carbon from the hydrogen gas for subsequent use. For example, the separated solid carbon can be used as an industrial feedstock, and the hydrogen gas can be used to generate low-carbon electricity. In some embodiments, the precipitator 120 is configured to collect larger-sized solid carbon, and the filter screen 121 is configured to block fine carbon powder that is not collected by the precipitator 120. The second gas 125 (e.g., hydrogen gas) that passes through the separation device 117 may be discharged through a gas outlet 122. In some embodiments, the dust collector 120 and filter screen 121 can be selected to collect solid carbon of desired particle sizes for various applications.

[0055] 1A, the separation device 117 may be connected to the outlet 116 through a four-way pipe 113. An outlet pressure meter 115 may be connected to the four-way pipe 113 to detect the output pressure of the outlet gas from the outlet 116. In some embodiments, a sampling port 114 may be connected to the outlet 116 through the four-way pipe 113. The sampling port 114 may be used to monitor the composition, dissociation efficiency, etc. of the outlet gas and provide feedback to the plasma apparatus 100.

[0056] As shown in FIG. 1A , the plasma device 100 is oriented vertically. In some embodiments, vertical orientation of the plasma device 100 can improve the efficiency of separating the solid product 124 (e.g., solid carbon) from the second gas 125 (e.g., hydrogen gas) by, for example, assisting in the separation of the heavy solid product 124 from the lighter second gas 125 by gravity. For example, as shown in FIG. 1A , the plasma device 100 can further include a reactant collection region 112 directly below the plasma generation region 106. The solid product 124 can fall in the reactant collection region 112 by gravity. Other orientations of the plasma device 100 (e.g., horizontal orientation) are also possible.

[0057] FIG. 2 is a schematic diagram of a plasma apparatus according to one embodiment of the present disclosure. The plasma apparatus 200 in FIG. 2 may be substantially similar to the plasma apparatus 100 in FIGS. 1A and 1B, with like reference numerals indicating like elements. As shown in FIG. 2, the plasma apparatus 200 further includes a rotating member 203. The rotating member 203 is mechanically coupled to the inner electrode 104, such that the inner electrode 104 is rotatable about a first rotation axis 104c. The rotating member 203 is a mechanical element that limits the movement of the inner electrode 104 to a desired rotation. The rotating member 203 may also provide mechanical support for the inner electrode 104. In some embodiments, the rotating member 203 includes a bearing. In some embodiments, the rotating member 203 includes a rotor. The rotor may be driven to rotate by interaction between the rotor and a respective stator. However, the present disclosure is not limited thereto.

[0058] In the embodiment illustrated in FIG. 2 , the rotating member 203 is fixed to the gas inlet 102, and the insulating layer 103 seals the gap between the gas inlet 102 and the outer electrode 105. However, in other embodiments, the rotating member 203 may be fixed to the insulating layer 103, the outer electrode 105, or the outer casing, if present. The present disclosure is not limited thereto. As illustrated in FIG. 2 , the rotating member 203 may wrap around the inner electrode 104. The rotating member 203 may be disposed between the inner electrode 104 and the outer electrode 105. In some embodiments, the rotating member 203 is disposed in an annular shape. In some embodiments, the rotating member 203 may be configured to receive a rotational driving force that rotates the inner electrode 104 about the first rotation axis 104c.

[0059] As shown in FIG. 2 , the inner electrode 104 has a plurality of through-holes 118 penetrating the wall 104a of the inner electrode 104. In some embodiments, the through-holes 118 of the inner electrode 104 are configured to obtain a rotational driving force from the flow of the first gas 109, which rotates the inner electrode 104 about the first rotation axis 104c. Specifically, one or more of the through-holes 118 may be configured to have an extension direction (as described in more detail below with respect to FIGS. 3A and 3B ), such that when the first gas 109 flows from the first cavity 119 to the plasma generation region 106 through the through-holes 118, the flow provides a rotational driving force to rotate the inner electrode 104 about the first rotation axis 104c. Thus, the inner electrode 104 can be rotationally driven by the flow of the first gas 109 (e.g., a hydrocarbon gas). In this manner, the rotation of the inner electrode and / or the flow of the first gas ejected from the through-holes can alleviate the problem of solid products (e.g., carbon) accumulating on the outer surface of the inner electrode, allowing the plasma apparatus to continue operating for a reasonable period of time without introducing additional working gas and reducing downtime of the plasma apparatus. The flow of the first gas ejected from the through-holes can also alleviate the problem of solid products (e.g., carbon) accumulating on the inner surface of the outer electrode. The flow of the first gas 109 can remove heat from the inner electrode 104, cooling it and similarly cooling the outer electrode 105. This can extend the service life of the inner electrode 104 and / or the outer electrode 105.

[0060] In some embodiments, the rotation speed of the inner electrode 104 can be between about 30 revolutions per minute (rpm) and about 180 rpm. However, the present disclosure is not limited thereto. In some embodiments, the rotation speed of the inner electrode 104 can be less than 30 rpm or greater than 180 rpm. The rotation speed of the inner electrode 104 can be varied depending on its size, material, the arrangement and configuration of the through-holes 118, etc. The rotation speed can be controlled by the flow rate of the first gas 109 and adjusted to achieve higher conversion rates and / or higher energy efficiency. In some cases, such rotation can extend the operation duration of the plasma device from 1 minute to about 7 days, or even about 1 month. These values are merely examples and are not intended to be limiting.

[0061] FIG. 3A is a schematic diagram of an inner electrode according to one embodiment of the present disclosure. FIG. 3B is a schematic cross-sectional view of the inner electrode in FIG. 3A along a cross-sectional plane 104h, which is perpendicular to the longitudinal axis 104n of the inner electrode 104. The inner electrode 104 in FIGS. 3A and 3B may be substantially similar to the inner electrode 104 in FIGS. 1A, 1B, and 2, and like reference numerals indicate like elements. In the embodiment illustrated in FIG. 3A, the inner electrode 104 has 12 through-holes 118 arranged in three rows of four through-holes 118 evenly distributed around the circumference (as illustrated in FIG. 3B, the angle between adjacent through-holes 118 is substantially 90 degrees). In some embodiments, the rows of through-holes 118 may include 1 to 12 through-holes 118 evenly or unevenly distributed around the circumference. The number and distribution of the through-holes 118 may be changed according to actual needs. In some embodiments, the distance 118d between adjacent rows of through-holes 118 can be from about 5 mm to about 50 mm. In some embodiments, the shape of the openings of through-holes 118 on wall 104a can be circular. In some embodiments, the diameter of the openings of through-holes 118 on wall 104a can be from about 0.5 mm to about 25 mm. These values are merely examples and are not intended to be limiting.

[0062] In some embodiments, the through-holes 118 may be positioned to increase the residence time of the first gas 109 within the plasma generating region 106. A longer residence time may increase the dissociation efficiency of the first gas 109. For example, near the opening 104b, the through-holes 118 may be more densely distributed (e.g., a greater number of through-holes may be included in a row and / or the distance between adjacent rows may be shorter), which may increase the residence time and resulting dissociation efficiency of the first gas 109.

[0063] 3B , the projection of the extension direction 118f and the radial direction 118r of the through-hole 118 onto the cross-sectional plane 104h forms an angle, where the radial direction 118r of the through-hole 118 extends from a point on the longitudinal axis 104n of the inner electrode 104 to the through-hole 118, the extension direction 118f of the through-hole 118 extends from the first cavity 119 toward the plasma generation region 106, and the cross-sectional plane 104h refers to a plane perpendicular to the longitudinal axis 104n of the inner electrode 104. In this manner, when the first gas 109 flows from the first cavity 119 through the through-hole 118 into the plasma generation region 106, this flow can provide a rotational driving force that rotates the inner electrode 104 about the first rotation axis 104c, and the inner electrode 104 can rotate without an additional driving device.

[0064] In some embodiments, the first angle θ1 between the extension direction 118f of the through-hole 118 and the radial direction 118r of the through-hole 118 in the cross-sectional plane 104h of the inner electrode 104 is between about 5 degrees and about 85 degrees. However, the present disclosure is not limited thereto. In some embodiments, the first angle θ1 can be less than 5 degrees or greater than 85 degrees. The first angle θ1 can be adjusted to enable a desired rotation speed of the inner electrode 104. In some embodiments, the first angle θ1 is between about 45 degrees and about 90 degrees. These values are merely examples and are not intended to be limiting.

[0065] FIG. 4 is a schematic diagram of an inner electrode according to one embodiment of the present disclosure. The inner electrode 204 in FIG. 4 may be substantially similar to the inner electrode 104 in FIGS. 1A-3B, with like reference numerals indicating like elements. As shown in FIG. 4, the through-holes 118 may be configured to extend "upward" to extend the residence time of the first gas 109 within the plasma generation region 106. Extended residence time may increase the dissociation efficiency of the first gas 109. In some embodiments, the second angle θ2 between the extension direction 118f of the through-holes 118 and the axial direction 104x is between about 5 degrees and about 85 degrees, and the axial direction 104x coincides with the longitudinal axis 104n of the inner electrode 104 and extends from a point 104p in the first cavity 119 toward the opening 104b of the first cavity 119. In some embodiments, the second angle θ2 may be less than 5 degrees or greater than 85 degrees. The second angle θ2 can be adjusted to achieve higher dissociation efficiency. In some embodiments, the second angle θ2 is between about 0 degrees and about 45 degrees. These values are merely examples and are not intended to be limiting.

[0066] 5A and 5B are schematic diagrams of a scraping unit according to one embodiment of the present disclosure. The plasma apparatus 500 in FIGS. 5A and 5B is substantially similar to the plasma apparatus 100 in FIGS. 1A and 1B, and like reference numerals indicate like elements. In the embodiment illustrated in FIGS. 5A and 5B, the plasma apparatus 500 further includes a scraping unit 123. The scraping unit 123 is also configured to move in contact with the outer surface 104d of the inner electrode 104. The scraping unit 123 may be configured to move in contact with the inner surface 105d of the outer electrode 105. In some embodiments, the scraping unit 123 surrounds the outer surface 104d of the inner electrode 104 and is configured to move in a first direction 126 along the longitudinal axis 104n of the inner electrode 104 and a second direction 127 opposite the first direction 126. In some embodiments, the accumulation of solid products 124 deposited on the outer surface 104d of the inner electrode 104 and / or the inner surface 105d of the outer electrode 105 may cause the plasma device 500 to stop generating plasma. The scraping unit 123 may be used to remove the solid products 124 attached to the inner electrode 104 and / or the outer electrode 105, thereby maintaining operation of the plasma device 500 and the plasma decomposition of the first gas 109.

[0067] As shown in FIGS. 5A and 5B , the scraping unit 123 surrounding the outer surface 104d of the inner electrode 104 can move in a first direction 126 to remove a portion of the solid product 124 deposited on the outer surface 104d of the inner electrode 104 and / or the inner surface 105d of the outer electrode 105. The scraping unit 123 can move in a second direction 127 opposite to the first direction 126 and return to its initial position. In some embodiments, the scraping unit 123 can be moved by a control rod (not shown) or a magnet assembly (not shown) connected to the scraping unit 123. The scraping unit 123 can be moved by a drive device or manually. In some embodiments, the scraping unit 123 can be used throughout the operation of the plasma apparatus 500. This can further reduce the maintenance frequency and downtime of the plasma apparatus.

[0068] FIG. 6 is a schematic cross-sectional view of a scraping unit according to one embodiment of the present disclosure. In the embodiment illustrated in FIG. 6, the scraping unit 123 includes a first blade 123a, a second blade 123b, and a connector 123c connecting the first blade 123a and the second blade 123b. The first blade 123a may be configured to move in contact with the outer surface 104d of the inner electrode 104, and the second blade 123b may be configured to move in contact with the inner surface 105d of the outer electrode 105. The first blade 123a and the second blade 123b may comprise Teflon, metal, ceramic, any suitable insulating material, or a combination thereof. In some embodiments, the second blade 123b and / or the first blade 123a may comprise iron, any suitable ferromagnetic material, or a combination thereof, allowing the movement of the scraping unit 123 to be controlled by a magnetic element. In some embodiments, connector 123c may comprise Teflon, ceramic, any suitable insulating material, or a combination thereof to avoid short circuits between electrodes.

[0069] FIG. 7 is a schematic diagram of a plasma apparatus according to one embodiment of the present disclosure. The plasma apparatus 701 in FIG. 7 may be substantially similar to the plasma apparatus 100 in FIGS. 1A and 1B, with like reference numerals indicating like elements. As shown in FIG. 7, the plasma apparatus 701 further includes a motor 129. The motor 129 may be coupled to the inner electrode 104 and configured to provide a rotational driving force for rotating the inner electrode 104 about the first rotation axis 104c. The motor 129 may be directly or indirectly coupled to the inner electrode 104, thereby allowing the inner electrode 104 to be rotationally driven by the motor 129. In this manner, the rotation of the inner electrode 104 can alleviate the problem of solid product (e.g., carbon) accumulation on the outer surface of the inner electrode, reducing downtime of the plasma apparatus as described above. The rotation speed of the inner electrode 104 may be controlled by the rotation speed of the motor 129 and adjusted to achieve a higher conversion rate and / or higher energy efficiency. All other discussion of the plasma apparatus and inner electrode discussed above with respect to Figures 1A through 6 may also apply here, where applicable.

[0070] FIG. 8 is a schematic diagram of a plasma apparatus according to one embodiment of the present disclosure. The plasma apparatus 801 in FIG. 8 may be substantially similar to the plasma apparatus 100 in FIGS. 1A and 1B, with like reference numerals indicating like elements. As shown in FIG. 8, the outer electrode 105 of the plasma apparatus 801 further includes a gas pipe 130. The gas pipe 130 may be embedded in the wall 105a of the outer electrode 105. In some embodiments, the outer electrode 105 may have multiple gas pipes 130. In one embodiment, the plasma apparatus 801 may further include a gas inlet valve 101 configured to control the flow rate of the first gas 109 into the plasma generation region 106. In some embodiments, the gas pipe 130 is configured to introduce the first gas 109 into the plasma generation region 106. In other words, the first gas 109 may flow into the plasma generation region 106 through the gas pipe 130. In this way, the flow of the first gas ejected from the gas pipe can alleviate the problem of solid products (e.g., carbon) accumulating on the outer surface of the inner electrode and / or the inner surface of the outer electrode, further reducing downtime of the plasma device 801. The flow of the first gas 109 can remove heat from the outer electrode 105 to cool the outer electrode 105 and can also cool the inner electrode 104. This can extend the service life of the outer electrode 105 and / or the inner electrode 104.

[0071] 9 is a flowchart illustrating a method according to one embodiment of the present disclosure. Method 900 may be operable in the plasma devices discussed above, such as plasma device 100, plasma device 200, plasma device 500, plasma device 701, and plasma device 801. In some embodiments, the inner electrode of the plasma device may include any or all of the features, characteristics, and parameters discussed above with respect to FIGS. 2 through 4.

[0072] 9 and 1A-1B, the method 900 includes introducing a first gas 109 into the first cavity 119 through the opening 104b of the first cavity 119 (step 910). The first cavity 119 may be defined by the wall 104a of the inner electrode 104. In some embodiments, the first gas 109 comprises a hydrocarbon gas. In some embodiments, step 910 may include introducing the first gas 109 into the first cavity 119 from a gas reservoir 108. In some embodiments, the method 900 may include heating the first gas 109 before the first gas 109 is introduced into the first cavity 119. All other descriptions regarding the plasma apparatus described above with respect to FIGS. 1A-8 may also apply here, if applicable.

[0073] 9 and 1A-1B, the method 900 includes flowing a first gas 109 from a first cavity 119 through the through-hole 118 into a plasma generation region 106 and rotating the inner electrode 104 about a first rotation axis 104c (step 920). As described above, the plasma generation region 106 is the region between the inner electrode 104 and the outer electrode 105 surrounding the inner electrode 104. The through-hole 118 penetrates the wall 104a of the inner electrode 104. The first rotation axis 104c penetrates the first cavity 119 of the inner electrode 104. 2, 3A, and 3B, in some embodiments, rotating the inner electrode 104 comprises obtaining rotational driving force from a flow of the first gas 109 from the first cavity 119 to the plasma generating region 106 via the through-holes 118, as described above. As further shown with reference to FIG. 7, in some embodiments, rotating the inner electrode 104 comprises providing rotational driving force from a motor 129 coupled to the inner electrode 104, as described above. All other descriptions regarding the plasma apparatus and inner electrode described above with respect to FIGS. 1A through 8 may also apply here, if applicable.

[0074] As shown with reference to FIG. 9 and FIGS. 1A-1B, the method 900 includes generating a plasma in the plasma generation region 106 by applying a voltage between the inner electrode 104 and the outer electrode 105 (step 930). In some embodiments, generating the plasma includes generating the plasma from a portion of the first gas 109. In other words, the method can be performed without introducing an additional working gas (e.g., nitrogen, oxygen, argon, and air). This can enhance the dissociation efficiency and product yield of the method and avoid undesirable by-products formed by reaction with the additional working gas. The plasma can be a low-temperature, i.e., non-thermal, plasma, and the plasma device can maintain a relatively low temperature. For example, the plasma can be generated under non-thermodynamic conditions, achieving an effective electron temperature of about 1000° C. to about 2000° C. or higher while maintaining a bulk gas temperature below about 500° C. This can avoid the problem that when high-temperature, i.e., thermal plasmas (e.g., plasmas with bulk gas temperatures of about 2000°C) are used to crack hydrocarbons, undesirable high-molecular-weight by-products (e.g., higher hydrocarbons, polycyclic compounds) are formed, reducing the purity of the resulting products.

[0075] As shown with reference to FIG. 9 and FIGS. 1A-1B, method 900 includes decomposing first gas 109 using plasma (step 940). The plasma may decompose molecules of first gas 109 and break chemical bonds therein, as described above. In some embodiments, the decomposition process occurs in plasma generation region 106. In some embodiments, method 900 may include outputting products generated from the decomposition of first gas 109 through outlet 116. In some embodiments, the products may comprise second gas 125 and solid products 124. In situations where first gas 109 includes hydrocarbons, second gas 125 may comprise hydrogen gas, and solid products 124 may comprise solid carbon. In some embodiments, a portion of first gas 109 that is not decomposed and / or other impurities may be output through outlet 116. In some embodiments, second gas 125 may comprise a decarbonized hydrocarbon gas (e.g., a mixture of hydrogen gas and hydrocarbon gas).

[0076] As shown with reference to FIG. 9 and FIGS. 1A-1B, in some embodiments, the method 900 may further include separating the solid product 124 from the second gas 125 by a separation device 117, as described above. In situations where the first gas 109 contains hydrocarbons, the separation device 117 may separate the solid carbon from the hydrogen gas (or decarbonized hydrocarbon gas). The solid carbon can be used as an industrial raw material, such as carbon black. Furthermore, the production and separation of carbon black can be performed without additional energy. The hydrogen gas or decarbonized hydrocarbon gas can be used for low-carbon emission power generation. In some embodiments, the hydrogen gas can be stored in the form of liquid hydrogen, compressed hydrogen, or metal hydrides.

[0077] As shown with reference to FIGS. 9 and 1A-1B, in some embodiments, the method 900 may further include inputting the second gas 125 into the generator 110. As illustrated in FIG. 1A, the generator 110 may be coupled to the gas outlet 122 of the separation device 117. Thus, the second gas 125 (e.g., hydrogen gas or decarbonized hydrocarbon gas) that has passed through the separation device 117 may be discharged from the gas outlet 122 and input into the generator 110. In one embodiment, the generator 110 may comprise a fuel cell. In one embodiment, the generator 110 may comprise a turbine or engine. In some embodiments, as described above, due to the airtight design of the insulating layer 103 and / or the bottom cover 111, the second gas 125 may be input into the generator 110 at a required gas pressure (e.g., atmospheric pressure or a higher pressure, such as 100 bar) without passing through a pump or compressor. The input pressure of the second gas 125 may be controlled, for example, by the gas inlet valve 101.

[0078] 9 and 1A-1B, and further with reference to FIG. 2, in some embodiments, the method 900 may further include cooling the inner electrode 104 by flowing the first gas 109 from the first cavity 119 to the plasma generation region 106 through the through-holes 118, as described above, although related description is omitted for brevity. In some embodiments, the plasma apparatus may function without an additional cooling system. All other descriptions regarding the plasma apparatus described above with respect to FIGS. 1A-8 may also apply here, if applicable.

[0079] 9 and 1A-1B, and further with reference to 5A-6, in some embodiments, the method 900 may further include removing the solid product 124 adhered to the inner electrode 104 by a scraping unit 123, as described above, although the related description will be omitted for brevity. All other descriptions regarding the plasma apparatus described above with respect to FIGS. 1A-8 may also apply here, if applicable.

[0080] 9 and 1A-1B, and further with reference to FIG. 8, in some embodiments, the method 900 may further include introducing the first gas 109 into the plasma generation region 106 through gas piping 130 embedded in the wall 105a of the outer electrode 105, as described above, although for the sake of brevity, the related description will be omitted. All other descriptions regarding the plasma apparatus described above with respect to FIGS. 1A-8 may also apply here, if applicable.

[0081] The description of the foregoing embodiments is provided to enable those skilled in the art to make and use the subject matter. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the novel principles and subject matter disclosed herein may be applied to other embodiments without the use of innovative features. The claimed subject matter is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. Additional embodiments are contemplated within the spirit and true scope of the disclosed subject matter. Thus, it is intended that the present invention cover modifications and variations that come within the scope of the appended claims and their equivalents.

Claims

1. A plasma device, comprising: an inner electrode having a wall defining a first cavity, an opening of the first cavity configured to receive a first gas, the inner electrode being rotatable about a first axis of rotation, the first axis of rotation passing through the first cavity; an outer electrode surrounding the inner electrode; The plasma device is characterized in that the inner electrode has a through hole penetrating the wall of the inner electrode, and the first cavity is in fluid communication with a plasma generation region between the inner electrode and the outer electrode via the through hole.

2. 2. The plasma device of claim 1, wherein both the inner electrode and the outer electrode are substantially tubular.

3. 2. The plasma device according to claim 1, wherein the outer electrode is disposed coaxially with the inner electrode.

4. The plasma device of claim 1 , further comprising a rotating member mechanically coupled to the inner electrode such that the inner electrode can rotate about the first axis of rotation.

5. The plasma device according to claim 4, wherein the rotating member comprises a bearing or a rotor.

6. The plasma device of claim 1 , further comprising a motor coupled to the inner electrode and configured to provide a rotational drive force to rotate the inner electrode about the first axis of rotation.

7. 2. The plasma device according to claim 1, wherein the through hole is configured to obtain a rotational driving force from a flow of the first gas from the first cavity to the plasma generation region through the through hole, and the rotational driving force rotates the inner electrode about the first rotation axis.

8. 2. The plasma device of claim 1, wherein a first angle between an extension direction of the through hole on a cross-sectional plane of the inner electrode and a radial direction of the through hole is between about 5 degrees and about 85 degrees, and the cross-sectional plane is perpendicular to a longitudinal axis of the inner electrode.

9. 2. The plasma device of claim 1, wherein a second angle between the extension direction of the through hole and an axial direction is between about 5 degrees and about 85 degrees, and the axial direction coincides with a longitudinal axis of the inner electrode and extends from a point within the first cavity toward the opening of the first cavity.

10. The plasma apparatus of claim 1 , further comprising a gas inlet configured to allow a flow of the first gas into the first cavity.

11. 11. The plasma device of claim 10, further comprising a gas container coupled to the gas inlet, the gas container containing the first gas.

12. The plasma device according to claim 1 , further comprising an insulating layer disposed annularly between the outer electrode and the inner electrode.

13. 10. The plasma device of claim 1, further comprising a power supply electrically connected to both the inner electrode and the outer electrode, the power supply configured to provide a voltage between the inner electrode and the outer electrode.

14. The plasma device of claim 1 , further comprising a scraping unit configured to move in contact with the outer surface of the inner electrode.

15. 15. The plasma device of claim 14, wherein the scraping unit surrounds the outer surface of the inner electrode and is configured to move in a first direction along a longitudinal axis of the inner electrode and in a second direction opposite to the first direction.

16. 16. The plasma device according to claim 15, wherein the scraping unit comprises a first blade, a second blade, and a connector connecting the first blade and the second blade, wherein the first blade is configured to move in contact with the outer surface of the inner electrode, and the second blade is configured to move in contact with the inner surface of the outer electrode.

17. 10. The plasma device of claim 1, further comprising an outlet configured to discharge a second gas and a solid product formed from the first gas.

18. 20. The plasma apparatus of claim 17, further comprising a separation device connected to the outlet, the separation device configured to separate the solid product from the second gas.

19. 20. The plasma apparatus of claim 18, wherein the separation device comprises a dust collector and a filter screen connected to the dust collector.

20. 18. The plasma device of claim 17, further comprising a bottom cover connected to the outer electrode at an end of the outer electrode, the outlet being disposed in the bottom cover.

21. 2. The plasma device according to claim 1, wherein the outer electrode comprises a gas pipe embedded in a wall of the outer electrode, the gas pipe being configured to introduce the first gas into the plasma generation region.

22. 10. The plasma device of claim 1, wherein the first gas comprises a hydrocarbon gas.

23. 1. A method comprising: introducing a first gas into a first cavity defined by a wall of the inner electrode through an opening in the first cavity; flowing the first gas from the first cavity through a through hole penetrating the wall of the inner electrode into a plasma generation region between the inner electrode and an outer electrode surrounding the inner electrode; generating plasma in the plasma generation region by applying a voltage between the inner electrode and the outer electrode; decomposing the first gas using the plasma; and rotating the inner electrode about a first axis of rotation, the first axis of rotation passing through the first cavity.

24. 24. The method of claim 23, wherein generating the plasma comprises generating the plasma from a portion of the first gas.

25. 24. The method of claim 23, wherein the first gas comprises a hydrocarbon gas.

26. 24. The method of claim 23, further comprising passing products produced from the decomposition of the first gas through an outlet.

27. 27. The method of claim 26, wherein the products comprise a second gas and a solid product.

28. 28. The method of claim 27, further comprising separating the solid product from the second gas by a separation device.

29. 28. The method of claim 27, further comprising: admitting the second gas to an electrical generator.

30. 24. The method of claim 23, wherein rotating the inner electrode comprises obtaining a rotational driving force from a flow of the first gas from the first cavity through the through-hole to the plasma generation region.

31. 24. The method of claim 23, wherein rotating the inner electrode comprises providing a rotational drive force from a motor coupled to the inner electrode.

32. 24. The method of claim 23, further comprising removing solid products adhering to the inner electrode with a scraping unit.

33. 24. The method of claim 23, further comprising cooling the inner electrode by flowing the first gas from the first cavity through the through-holes to the plasma generating region.

34. 24. The method of claim 23, wherein introducing the first gas comprises introducing the first gas into the first cavity from a gas container.

35. 24. The method of claim 23, further comprising heating the first gas before the first gas is introduced into the first cavity.

36. 24. The method of claim 23, further comprising introducing the first gas into the plasma generating region through gas piping embedded in a wall of the outer electrode.

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