Plasma Gas Reactor

Abstract

The present invention relates to a plasma reactor comprising a reactor space, a cylindrical reactor vessel coaxial with an axial gas inlet suitable for axial fluid flow and surrounding said reactor space, said reactor vessel comprising outlet means. The present invention further relates to a multi-stage reactor. The present invention also relates to the use of said plasma reactor.

Description

[Technical Field]

[0001] FIELD OF THE INVENTION The present invention relates to a reactor suitable for chemical reactions and for generating a plasma within at least a portion of the reactor, in particular the reactor is suitable for gaseous reactants at elevated pressures. [Background technology]

[0002] (background) There are many methods and systems for cracking hydrocarbons into carbon fractions and hydrogen. The traditional method for producing hydrogen from hydrocarbons in industrial processes involves steam reforming of hydrocarbons. In many cases, air or oxygen is added to the steam-hydrocarbon mixture in a depleted state. This method is inefficient because a substantial portion of the converted hydrocarbons is used as an energy source for the process, resulting in low utilization. Furthermore, yields are further reduced due to the fact that the combustion process is not completed, thus producing carbon monoxide and carbon dioxide, as well as nitrogen oxides in the presence of nitrogen. These waste gases from the process cannot be used for any purpose other than as fuel gas, resulting in the release of polluting environmental gases. Furthermore, separating the hydrogen gas from the gaseous by-products can be difficult and incur additional costs.

[0003] Conventional pyrolysis of natural hydrocarbons is a thermally activated equilibrium reaction at temperatures ranging from 1200 to 2000 K. This process exhibits limited energy and conversion capacity. Some utilize catalysts to operate at low temperatures (~1000 K), but this results in limited yields and other problems, such as catalyst deactivation due to carbon deposition. Regeneration of such deactivated catalysts consumes energy and often produces large amounts of CO2.

[0004] In terms of hydrocarbon feedstock utilization, plasma pyrolysis has proven to be much more effective, and many experiments have been carried out using plasma torches. However, as mentioned in the introduction, this has not led to any continuous industrial production due to the low thermal efficiency required to obtain a stable plasma, the low methane inlet pressure, the low hydrogen outlet pressure requiring several compressor stages, and the high amount of energy required to store and transport the hydrogen in an industrially applicable manner.

[0005] EP 0 675 925 describes a method and apparatus for pyrolyzing hydrocarbons into carbon fractions and hydrogen. The problem with this apparatus is the use of standard reactor vessels. During operation, most of these reactor vessels do not reach conditions suitable for either decomposition or reaction. As a result, the reactor efficiency is extremely low. Furthermore, the reactor operates at pressures that are too low to be applicable on a large industrial scale.

[0006] U.S. Patent Application Publication No. 2003 / 0024806 describes a plasma swirl reactor. However, this plasma swirl reactor is designed for municipal waste as a carbon source, not gaseous hydrocarbons. Furthermore, the reactor has a small reactive plasma zone within the reactor volume. As a result, a large segment of the reactor is not fully utilized. Thermal and plasma reaction efficiencies are low. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention aims to solve at least some of the problems and drawbacks mentioned above. The object of the present invention is to provide a method that eliminates these drawbacks. The present invention aims to solve at least one of the drawbacks mentioned above. [Means for solving the problem]

[0008] (Summary of the Invention) The present invention and its embodiments serve to provide a solution to one or more of the above-mentioned drawbacks. To this end, the present invention relates to a plasma reactor as claimed in claim 1.

[0009] The reactor design aims to improve: - Strong plasma and reactive gas overlay to obtain both high power density and good plasma / gas overlay; - improved utilization of thermal plasmas, allowing the use of concentrated sources, which are generally associated with high radiation losses, large lethal energies, and expensive material costs due to very high temperatures; - Allows the use of high pressure (industrial) gases, e.g. 20 bar and above, in plasma reactor systems. The GLIDARC design can operate at pressures up to 10 bar. Thermal plasma torches typically operate below atmospheric pressure. - Avoiding thermal and chemical influences on the reactor allows for the use of cheaper materials. - Allows safe and reliable operation despite high temperatures, highly reactive plasma and ion species, and, depending on the plasma generation means, high voltages. - Easy scale-up from single-stage to multi-stage reactors without the need for redesign, allowing for easy increase in reactor throughput.

[0010] Preferred embodiments of the device are set forth in any of claims 2-11. A particularly preferred embodiment relates to the invention as defined in claim 3. Such a plasma reactor has a large overlap between the plasma and the reactive gas. Furthermore, the reactor favors the conversion of the inlet gas pressure into high temperatures in the reactor by kinetic heat dissipation. This is a result of the reactor's planar geometry. As a result, the plasma reaction efficiency and thermal efficiency are significantly improved.

[0011] In a second aspect, the present invention relates to a multi-stage plasma reactor as claimed in claim 12.

[0012] In a third aspect, the present invention relates to the use of a plasma reactor according to claim 13. In a preferred embodiment of the second aspect, the present invention relates to the use of a plasma reactor according to claim 14 for the hybrid plasma decomposition of methane to hydrogen.

[0013] Methane conversion to hydrogen is currently carried out industrially by steam reforming, forming a mixture of hydrogen, CO, and CO2. Hybrid plasma decomposition of methane into hydrogen and carbon black advantageously allows for easy separation between the hydrogen and carbon black. No CO or CO2 is produced, and more hydrogen is produced per unit of methane. This is ecologically desirable for reducing greenhouse gas emissions. Furthermore, the thermal energy required to dissociate CH4 in H2 and C (defined by the usual reaction enthalpy) is significantly lower per unit of H2 than steam reforming methane and water electrolysis.

[0014] Although high temperatures are required to obtain the desired reaction equilibrium (shifted toward the dissociation products), the dissociation reaction itself absorbs significantly less energy from the environment compared to steam reforming or water dissociation (e.g., electrolysis). [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 shows a cross-sectional side view and a cross-sectional top view of one embodiment of a plasma reactor according to the present invention. [Figure 2] FIG. 2 shows cross-sectional side views of embodiments of single-stage and multi-stage plasma reactors according to the present invention. [Figure 3] FIG. 3 shows a cross-sectional side view of an embodiment of a plasma reactor with wave plasma generation. [Figure 4A] FIG. 4A shows a cross-sectional side view of an embodiment of a plasma reactor with dielectric barrier discharge (DBD) plasma generation. [Figure 4B] FIG. 4B shows a cross-sectional top view of an embodiment of a plasma reactor with dielectric barrier discharge (DBD) plasma generation. [Figure 4C]FIG. 4C shows a cross-sectional side view of a downstream gas expansion disk and an upstream gas expansion disk suitable for dielectric barrier discharge (DBD) plasma generation. [Figure 5A] FIG. 5A shows a cross-sectional top view of one embodiment of a plasma reactor having a gliding arc plasma generating means. [Figure 5B] FIG. 5B shows a cross-sectional top view of one embodiment of a plasma reactor having a gliding arc plasma generating means in operation. [Figure 5C] FIG. 5C shows a cross-sectional side view of a downstream gas expansion disk suitable for gliding arc plasma generation. [Figure 5D] FIG. 5D shows a cross-sectional side view of alternative downstream and upstream gas expansion disks suitable for gliding arc plasma generation. [Figure 6A] FIG. 6A shows a cross-sectional top view of an embodiment of a vaneless plasma reactor. [Figure 6B] FIG. 6B shows a cross-sectional top view of an embodiment of a vaned plasma reactor. [Figure 7A] FIG. 7A shows a graph representing the ratio of the dissipative force to the inertial force of the expanding gas in the reactor space as a function of the width H between the upstream and downstream expansion discs (m). [Figure 7B] FIG. 7B shows a graph representing the ratio of dissipative forces to inertial forces of expanding gas in the reactor space as a function of gas velocity (m / s). [Figure 8] FIG. 8 shows a cross-sectional side view of an embodiment of a plasma reactor in which the upstream expansion disk is a hollow cylinder according to the present invention. [Figure 9] FIG. 9 shows a cross-sectional side view of an embodiment of a plasma reactor in which the upstream expansion disk is a hollow cylinder and the downstream expansion disk comprises a planar heat exchanger according to the present invention. [Figure 10A] FIG. 10A shows a schematic cross-sectional side view of an embodiment of a plasma reactor having multiple point source microwave sources (12). [Figure 10B] FIG. 10B shows a schematic perspective view of an embodiment of a plasma reactor having multiple point source microwave sources (12). [Figure 10C] FIG. 10C shows a schematic diagram of power density for mono-source and multi-source microwave plasma generation. DETAILED DESCRIPTION OF THE INVENTION

[0016] (Detailed Description of the Invention) The present invention relates to a reactor suitable for chemical reactions, as well as a reactor that generates a plasma within at least a portion of the reactor.

[0017] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art to which this invention belongs. By way of further guidance, definitions of terms are included to better understand the teachings of the present invention.

[0018] As used herein, the following terms have the following meanings:

[0019] As used herein, "A," "an," and "the" refer to both singular and plural referents unless the context clearly dictates otherwise. By way of example, "a section" refers to one or more sections.

[0020] As used herein, "Comprise," "comprising," and "comprises" and "comprised of" are synonymous with "include," "including," "includes," or "contain," "containing," or "contains," and are inclusive or comprehensive. Open-ended terms specifying the presence of the following content. They do not exclude or preclude the presence of additional, unrecited components, features, elements, materials, or steps that are known in the art or disclosed therein.

[0021] Moreover, the terms first, second, third, etc. in this specification and claims are used to distinguish between like elements and are not necessarily used to describe a sequential or chronological order, unless specified. The terms so used are interchangeable under appropriate circumstances, and it is to be understood that the embodiments of the invention described herein are capable of operating in other arrangements than described or illustrated herein.

[0022] The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed within that range, as well as the recited endpoints.

[0023] The term "one or more" or "at least one," e.g., at least one member of one or more groups of members, will itself be apparent from further illustration, but the term specifically encompasses reference to any one of said members, or any two or more of said members, e.g., any >3, >4, >5, >6, or >7, etc., of said members, up to and including all of said members.

[0024] As used herein, "thermal plasma" refers to a plasma in which the electron temperature, ion temperature, and gas temperature are approximately equal. e , ION T i and Gas T g The absolute temperature of ion T is at most 20%. i and Electronic T e The absolute temperature difference between the ions and electrons is at most 15%, more preferably the absolute temperature difference between the ions and electrons is at most 10%, more preferably the absolute temperature difference between the ions and electrons is at most 5%, and most preferably the absolute temperature difference between the ions and electrons is at most 1%.

[0025] As used herein, a "non-thermal" or "low-temperature plasma" refers to a plasma with an electron temperature T e is much hotter than the temperature of the heavy species (ions and neutrals), and therefore is not in thermodynamic equilibrium. e The temperature of the ion T i and much higher than the temperature of the gas. 202305121011580110__________________________________________APH_0 202305121011580110__________________________________________APH_1

[0026] As used herein, "hybrid plasma" refers to the superposition of a thermal plasma and a non-thermal plasma. Preferably, the hybrid plasma has a zone that forms a thermal plasma, i.e., a zone where ions and electrons are in thermodynamic equilibrium, and a zone that forms a non-thermal plasma, i.e., a zone where electrons are at a substantially higher temperature than ions and neutrals.

[0027] As used herein, "hybrid plasmalysis" refers to the decomposition of a substance under the influence of a hybrid plasma. It further includes the possible recombination of ionized species into generally non-ionized end products.

[0028] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meanings commonly understood by those skilled in the art to which the present invention belongs. By way of further guidance, definitions of terms used in the description are included to better understand the teachings of the present invention. The terms or definitions used herein are provided solely to aid in the understanding of the present invention.

[0029] References throughout this specification to "one embodiment" or "an embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrase "in one embodiment" or "in an embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may refer to the same embodiment. Furthermore, particular features, structures, or characteristics can be combined in any suitable manner in one or more embodiments, as would be apparent to one of ordinary skill in the art from this disclosure. Furthermore, although some embodiments described herein include some embodiments that do not include other features but are included in other embodiments, combinations of features from different embodiments are within the scope of the present invention and are meant to form different embodiments, as would be understood by one of ordinary skill in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0030] In a first aspect, the present invention relates to a plasma reactor comprising: - reactor space, - an axial gas inlet adapted for a fluid flow in the axial direction, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of the radial injection slit with respect to the axial direction; - plasma generating means suitable for ionizing the gaseous medium in said reactor space, and a cylindrical reaction vessel, coaxial with said gas inlet and surrounding said reaction space, said reaction vessel being provided with outlet means.

[0031] In a preferred embodiment of the present invention, the plasma reactor further comprises an upstream gas expansion disk extending radially from the coaxial inlet and positioned upstream of the radial injection slit with respect to the axial direction.

[0032] In a further preferred embodiment of the present invention, the width H between the downstream gas expansion disk and the upstream gas expansion disk is less than 100 cm, more preferably less than 75 cm, more preferably less than 50 cm, more preferably less than 25.00 cm, more preferably less than 20.00 cm, more preferably less than 10.00 cm, more preferably less than 8.00 cm, more preferably less than 6.00 cm, more preferably less than 5.00 cm, more preferably less than 4.00 cm, more preferably less than 3.00 cm, more preferably less than 2.00 cm, more preferably less than 1.00 cm, more preferably less than 0.80 cm, more preferably less than 0.60 cm, more preferably less than 0.50 cm, more preferably less than 0.40 cm, more preferably less than 0.30 cm, more preferably less than 0.25 cm, more preferably less than 0.20 cm.

[0033] In a preferred embodiment of the present invention, the upstream gas expansion disk is provided with a heat exchange means. In another preferred embodiment of the present invention, the downstream gas expansion disk is provided with a heat exchange means. In a more preferred embodiment, both the upstream gas expansion disk and the downstream gas expansion disk are provided with a heat exchange means. Heat exchange means are known in the art. In a preferred embodiment, the gas expansion disk comprises hollow fluid passages. These fluid passages can be used to heat a fluid, such as water. Cooling is advantageous because thermal management of the reactor space helps maintain its durability and reduce manufacturing costs. Furthermore, heat recovery improves the thermal efficiency of the plasma reactor, reducing its operating costs.

[0034] In a preferred embodiment of the present invention, the upstream injection disk is a hollow cylinder. More preferably, the hollow cylinder is provided with a tangential preheating gas inlet. The hollow cylinder further comprises an axial preheating gas outlet in fluid communication with the axial gas inlet of the first embodiment of the present invention. This preferred embodiment is shown in Figure 8. Pressurized reaction gas (1) is supplied tangentially to the outer part of the hollow cylinder, which doubles as an upstream gas expansion disk (4), where it forms a vortex and is preheated by heat exchange with the plasma reactor. From the hollow cylinder, the preheated gas flows radially toward the center through a first set of radial slits (3') and enters the axial gas inlet. From the axial gas inlet, the preheated gas flows radially through the radial injection slits (3) into the reactor space. In a further preferred embodiment, the hollow cylinder is provided with vanes suitable for initiating or improving vortex flow and / or promoting turbulence and / or improving heat exchange. This configuration allows the reactant gas to be supplied to the axial gas inlet and preheated before being injected radially into the reactor space. More preferably, the gas reactant may be preheated by supplying high-pressure gas into the hollow cylinder, whereby friction effects and vortices initiate a general vortex flow, converting pressure into heat. Additional heat is provided by the heat exchange effect with the plasma reactor. When multiple gas streams are utilized, this also improves mixing of the gas streams. This design advantageously provides thermal self-regulation, reducing operational difficulties and improving the safety of the plasma reactor.

[0035] In a more preferred embodiment, the downstream gas expansion disk and the upstream gas expansion disk are adapted to a thermal plasma (dissociation) zone and a high heat exchange (quenching, recombination, condensation) zone. Preferably, the thermal plasma zone is suitable for limited heat exchange, including materials and / or coatings with limited thermal conductivity. Preferably, the high heat exchange zone is suitable for high heat exchange, particularly materials suitable for thermal conductivity, but also suitable for heat exchange means. Preferably, the thermal plasma zone is radially closer to the axial gas inlet than the high heat exchange zone.

[0036] In preferred embodiments, the operation of these high heat exchange zones is switchable, i.e., they can be switched between quenching and slow cooling as needed. Advantageously, this allows for fine tuning of the selectivity of the recombination reaction. In certain embodiments, the high heat exchange zones may be switched between (slow) cooling mode and quench mode. This can make it possible, for example, to produce either solid forms of carbon (amorphous carbon black or crystallized forms (such as graphene or graphite)) or, conversely, non-solid carbonaceous forms such as C2-C5 hydrocarbons (e.g., acetylene) in a controlled cooling operation (e.g., slow cooling rate via a gas-liquid exchanger) in a quench operation (very rapid cooling rate via a gas-cooled vapor exchanger) from a hydrocarbon (preferably methane) feedstock.

[0037] Switchable operating modes for adjusting reaction selectivity can be achieved in various ways. In particular, the upper and / or lower expansion disks can serve as heat exchangers. Figure 9 shows a preferred reactor design in which the downward expansion disk is equipped with a planar heat exchanger. The planar heat exchanger (16) contains a refrigerant, preferably a cold evaporable liquid (17), more preferably water. The liquid refrigerant (17) evaporates on the planar heat exchanger (16), and the resulting gas phase (18) is regenerated for heat reuse. Such a planar heat exchanger can be operated in evaporative mode with fine refrigerant droplets to achieve highly efficient quenching. The planar heat exchanger can be operated in liquid / liquid or evaporative mode with a lower flow rate to achieve slow cooling. Preferably, the planar heat exchanger operates in liquid / liquid mode. Furthermore, the refrigerant flow and temperature can be adapted to switch between rapid and slow cooling modes. In a preferred embodiment, the thermal energy captured by the refrigerant is utilized. For example, the heat may be used directly, used as a heat exchanger, used to generate power, or used downstream to preheat additional catalytic reactor chambers. Another embodiment suitable for switchable operation utilizes adiabatic cooling: the reactor volume expands as the plasma passes radially through the reactor, resulting in divergent gas flow, thereby achieving adiabatic cooling.

[0038] In another embodiment suitable for switchable operation, an additional fluid (in the case of a liquid, preferably an aerosol) may be injected into the reactor space, in particular into the plasma zone or between the plasma zone and the recombination zone. It is clear that the injection of a fluid or aerosol is not limited to quenching, but may also be used to obtain other desired effects, such as dissociation of the aerosol, forming reactive species in the plasma after the discharge, or only gases such as hydrogen or nitrogen. This can further increase the power of the generated plasma. Alternatively, reactor inertization can be achieved, for example, with argon or nitrogen gas. This is useful for improving reactor safety when solid compounds explosive in air are produced and transported in downstream processes.

[0039] In a preferred embodiment of the present invention, the radial injection slits are provided with radially extending vanes. In a preferred embodiment of the present invention, the vanes are fixed vanes, i.e., the vanes do not rotate, adjust, or move during operation of the plasma reactor. Various types of vanes are known in the art and are suitable for use in the context of the present invention, including, but not limited to, linear vanes, airfoil vanes, and separation vanes. The purpose of the vanes is to direct the expanding airflow in a desired direction via the Young-Coanda effect. In particular, the vanes are suitable for creating vortex expansion within a cylindrical reactor space. This is beneficial for improving gas-plasma mixing, particularly micromixing, and increasing the residence time or contact time of gases within the plasma zone within the reactor space to improve physical conversion treatment efficiency.

[0040] The plasma generation means described herein are preferably selected from the list of wave source, dielectric barrier discharge, gliding arc or combinations thereof, each of these embodiments will now be described in more detail.

[0041] In a particular embodiment, the present invention relates to a plasma reactor according to the first aspect of the present invention, wherein the plasma generating means is a wave source. Plasma can be formed from one or more process gases or from a gas mixture by applying an electric field from a power source, thereby heating the mixture. Suitable wave sources include medium wave, radio frequency (RF) waves, or microwaves, which can be inductively or capacitively coupled. These techniques are known in the art. The plasma reactor according to the present invention can be used with wave sources in both pulsed and continuous modes. In a preferred embodiment, the plasma generating means is a microwave source. In a preferred embodiment, the plasma generating means is a wave source with a waveguide and an impedance matching device. In a more preferred embodiment, multiple wave sources, waveguides, and impedance matching devices are used. Preferably, these multiple waveguides and impedance matching devices are set up radially relative to the reactor. Microwaves are powerful point sources. Waveguides and impedance matching boxes can be used to inject power as needed without the need for electrodes within the reactor. Constructive interference can be used to obtain zones of plasma with high molecular weight dissociation. Destructive interference can be used to reduce the power density in other areas.

[0042] The waves generated by the wave source are preferably plane waves. The waves generated by the wave source are more preferably standing waves. Stationary waves are suitable for generating zones of maximum and minimum power density due to interference. This is particularly true when multiple wave sources are used. Stationary waves are easier to control with respect to interference, especially when considering forward injection / back reflection. This is beneficial for generating zones of high dissociation and zones that allow efficient recombination, thus improving the energy efficiency of the reactor.

[0043] In certain embodiments of the first aspect, the present invention provides a method for treating a cancer cell comprising: - reactor space, - an axial gas inlet adapted for a fluid flow in the axial direction, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of the radial injection slit with respect to the axial direction; a cylindrical reactor vessel coaxial with said gas inlet and surrounding said reactor space, said reactor vessel being provided with outlet means; - at least one wave source, and - at least one waveguide and an impedance matching box configured to generate at least partially a plane wave in the reactor volume; The present invention relates to a plasma reactor comprising:

[0044] In another specific embodiment, the present invention relates to a plasma reactor according to the first aspect of the present invention, in which the plasma generation means is a dielectric barrier discharge (DBD). In a preferred embodiment, the plasma reactor comprises both an upstream gas expansion disk and a downstream gas expansion disk having a conductive inner core or electrode and an outer dielectric coating suitable for generating DBD plasma. The DBD plasma is generated by connecting the first electrode to a high-voltage generator (AC mode and pulsed DC mode) and grounding the second electrode. Suitable materials for the electrodes can be selected from, but are not limited to, stainless steel, refractive metal alloys, and conductive carbides. Suitable materials for the dielectric coating can be selected from, but are not limited to, Al2O3, SiO2, and ZrO2. Advantageously, power is uniformly distributed between the electrodes, resulting in a large overlap of the expanding gas between the electrodes. Furthermore, a first zone with low-temperature plasma suitable for dissociation of reactants and a second zone without plasma suitable for condensation and recombination can be designated. These zones are tightly controlled by the geometry of the upstream and downstream gas expansion disks. Furthermore, the overlap between power distribution and expanding gas is large due to the reactor design.

[0045] In a particular embodiment of the first aspect, the present invention relates to a plasma reactor comprising: - reactor space, - an axial gas inlet adapted for a fluid flow in the axial direction, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of the radial injection slit with respect to the axial direction; - an upstream gas expansion disk extending radially from the coaxial inlet and positioned upstream of the radial injection slit with respect to the axial direction, the upstream gas expansion disk and the downstream gas expansion disk comprising a conductive inner core and an outer dielectric coating; and a cylindrical reaction vessel, coaxial with said gas inlet and surrounding said reaction space, said reaction vessel being provided with outlet means.

[0046] In another specific embodiment, the present invention relates to a plasma reactor according to the first aspect of the present invention, wherein the plasma generation means is gliding arc plasma generation. A gliding arc hybrid plasma is generated between a pair of electrodes. Preferably, multiple pairs of electrodes (i.e., an even number of electrodes) are used. In a preferred embodiment, these electrodes are provided on the downstream gas expansion disk or the upstream gas expansion disk. In one embodiment, an electrode pair may be provided on the downstream gas expansion disk. In another embodiment, an electrode pair may be provided on the upstream gas expansion disk. In another embodiment, a first electrode of the electrode pair may be provided on the upstream gas expansion disk, and a second electrode of the electrode pair may be provided on the downstream gas expansion disk. Preferably, the electrodes are wire-shaped and radially oriented. More preferably, the electrodes have a diameter of 0.05 mm to 2.00 mm, more preferably 0.10 mm to 1.00 mm. The number of electrode pairs, their geometry (localization within the reactor, length, etc.), and power (voltage and current) determine the power density in the expanding gas. The electrodes are made of a heat-resistant and electrically conductive material. Such materials may be selected from, but are not limited to, stainless steel, refractory metal alloys, conductive and ceramic (ie, carbon). Power distribution and voltage / current ratio control are essential. This can be achieved by connecting electrode pairs in parallel (high current divided among all electrode pairs) and in series (unique current and voltage drop across each electrode pair).

[0047] The gliding arc reactor can be operated with a variety of voltage sources, including but not limited to DC, pulsed DC, single-phase AC, three-phase, and polyphase current. The current is preferably at a high frequency to match the arc impedance and may be pulsed, e.g., pulsed DC, to increase peak power.

[0048] In another particular embodiment of the first aspect, the present invention provides a method for treating a cancer cell comprising: - reactor space, - an axial gas inlet adapted for a fluid flow in the axial direction, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; - a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of the radial injection slit with respect to the axial direction, at least one electrode pair being deposited on the downstream gas expansion disk; and a cylindrical reaction vessel, coaxial with said gas inlet and surrounding said reaction space, said reaction vessel being provided with outlet means; The present invention relates to a plasma reactor comprising:

[0049] In another particular embodiment of the first aspect, the present invention provides a method for treating a cancer cell comprising: - reactor space, - an axial gas inlet adapted for a fluid flow in the axial direction, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; - at least one electrode pair comprising a first and a second electrode; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of the radial injection slit with respect to the axial direction, the first electrode being deposited on the downstream gas expansion disk; an upstream gas expansion disk extending radially from the coaxial inlet and positioned upstream of the radial injection slit with respect to the axial direction, the second electrode being deposited on the upstream gas expansion disk; and a cylindrical reaction vessel, coaxial with said gas inlet and surrounding said reaction space, said reaction vessel being provided with outlet means; The present invention relates to a plasma reactor comprising:

[0050] In a second aspect, the present invention relates to a multi-stage plasma reactor comprising at least one plasma reactor cell according to the first aspect of the present invention. Preferably, the multi-stage plasma reactor comprises a stack of plasma reactors according to the first aspect of the present invention. In a preferred embodiment, the multi-stage plasma reactor utilizes a single common gas inlet. Planar reactors according to the present invention can be advantageously stacked around a single common gas inlet, allowing for convenient and easy upscaling. Upscaling can also be utilized in a modular manner, if desired. Furthermore, the multi-stage plasma reactor as a whole does not have a single-stage planar geometry and can be designed to better fit available space or design constraints, while retaining the benefits of improved thermal and plasma reaction efficiency associated with a single-stage planar geometry.

[0051] In a third aspect, the present invention relates to the use of a plasma reactor according to the first aspect of the invention or a multi-stage reactor according to the second aspect of the invention.

[0052] In a preferred embodiment of the third aspect, the plasma reactor uses thermal gas dissociation reactions, suitable examples of which include, but are not limited to, thermal dissociation of hydrocarbons, H2S, H2Se, etc.

[0053] In another preferred embodiment of the third aspect, the plasma reactor is used for gas chemical reactions. In a more preferred embodiment, the reaction may be used to enable Sabatier-type reactions in the absence of a catalyst, i.e., reforming of CO and hydrogen into hydrocarbons and / or reforming of nitrogen gas and hydrogen gas into ammonia.

[0054] In a preferred embodiment, the present invention relates to the use of a plasma reactor according to the first aspect of the present invention or a multi-stage reactor according to the second aspect of the present invention for the hybrid plasma decomposition of hydrocarbons, preferably methane, to hydrogen and carbon black. Pyrolytic plasma decomposition of hydrocarbons, such as methane, to carbon black and hydrogen is known. However, many problems remain with this technology. As a result, industrial-scale gray hydrogen is generally produced by steam reforming of hydrocarbons, rather than by hybrid plasma decomposition of hydrocarbons, with significant CO2 as a by-product. In particular, plasma reactors known in the art require low hydrocarbon inlet pressures and provide hydrogen at low outlet pressures, neither of which is suitable for industrial applications. Furthermore, the thermal efficiency of the reactor is generally low. Generally, conditions suitable for the decomposition of hydrocarbons and the formation of hydrogen and carbon black occur only in a small segment of the reactor volume, resulting in low efficiency. The plasma reactor of the present invention overcomes or ameliorates some of these issues. However, it is clear that the present invention is not limited to this application.

[0055] The reactor according to the present invention can be used for any type of high-temperature reaction, particularly plasma and gas reactions. As used herein, "reactant gas" includes homogeneous gas mixtures as well as dispersions in which the continuous medium is a gas. In particular, liquid-gas dispersions (aerosols) and solid-gas dispersions (solid aerosols) can also be used within the scope of the present invention as reactant gases and as intermediates formed at any stage in the reactor. Such intermediates can be formed due to chemical and plasma reactions occurring within the plasma reactor, but can also be formed by intentionally dispersing solids or liquids at any point within the reactor space. The present invention is further illustrated by the following non-limiting examples, which further illustrate the present invention and are not intended to, and should not be construed as, limiting the scope of the present invention.

[0056] The invention will now be explained in more detail with reference to non-limiting examples. [Example]

[0057] EXAMPLES AND / OR FIGURE DESCRIPTIONS In order to better illustrate the properties of the present invention, the following provides a description of some preferred applications of the method for inspecting the condition of grout used in mechanical connections according to the present invention, by way of example and in no way limiting other potential applications:

[0058] A cross-sectional side view and a cross-sectional top view of one embodiment of a plasma reactor are shown in FIG. 1. A high-pressure tank 1 supplies gaseous or vaporized reactants to an axial gas inlet 2. The pressure in the axial gas inlet can be up to 20-50 bar. This is advantageous because higher pressures allow for higher gas throughput. Furthermore, gases in industry are generally stored and transported at high pressure. It is beneficial to at least utilize the potential energy of the pressurized gas.

[0059] Pressurized gas enters the reactor chamber through a radial injection slit 3. The expanding gas stream 5 expands radially within the reactor chamber. A downstream gas expansion disk 6 supports the expansion of the gas film due to the Young-Coanda effect. The diameter of this disk can be adjusted to achieve the desired pressure and radial velocity of the expanding gas. It can also be used to fine-tune the plasma power distribution within the reactor. An optional upstream gas expansion disk also serves to shape the gas expansion stream and adjust the gas pressure and radial velocity. Gas characteristics can be further adjusted by varying the diameter of the upstream gas expansion disk and the width H between the upstream and downstream gas expansion disks. The reactor chamber is surrounded by a reactor chamber outer box 7 equipped with a gas outlet means (not shown).

[0060] 2 shows a cross-sectional side view of one embodiment of a single-stage and multi-stage plasma reactor according to the present invention. Several stages of plasma reactors can be stacked around an extended axial gas inlet.

[0061] FIG. 3 shows an embodiment of a plasma reactor with wave plasma generation. A wave source or magnetron 8 is used to generate waves. These waves are guided and tuned using a waveguide and impedance matching box 9. Multiple magnetrons and waveguides and impedance boxes can be utilized, preferably in a radial arrangement, to obtain high power transmission toward the gas extending through the waves. Furthermore, the waveguides and impedance matching boxes can be configured for zones of constructive interference to obtain areas within the reactor volume with high power input.

[0062] In a further preferred embodiment, the plasma is generated by a series of multiple wave sources, particularly evanescent point sources (19). Figures 10A, 10B, and 10C show schematic diagrams of such a preferred embodiment. The use of evanescent point sources allows for an increase in plasma power density near the upstream region of the reactor. The distance between the multiple wave sources adjusts the power density. Preferably, a toroidal plasma with a relatively uniform energy density is generated. In particular, the use of an antenna that allows for the generation of microwave-sustained plasma allows for the generation of a toroidal plasma zone around the gas injection point. These high-density sources provide a high concentration of reactive species and electrons. These species are the energy vector of the plasma that allows for molecular dissociation, which always occurs via a collisional process involving electrons. In general, the production of excited species is more efficient in the continuous case than in the high-frequency case where the electron density is constant. However, when evaluating the efficiency of different plasmas from a practical perspective, it is important to consider the production of species at a constant absorbed power density. Modeling of the density of excited states as a function of excitation energy for a constant power density shows that the continuous case is by no means the most advantageous, but that working at higher frequencies is preferable. Dissociative reactions, on the other hand, have the largest cross section for low energy electrons.

[0063] Considering the effect of the electric field excitation frequency on the density and energy distribution in the plasma, it appears that as frequency increases, the electron density increases and the average electron energy decreases. Therefore, the choice of microwave frequency is fully justified in the use of this type of plasma for dissociating hydrocarbon molecules. Microwave plasma sources are well known for their ability to generate high densities of reactive species, but they are often considered difficult to obtain in industrial systems where large volumes of plasma are required. As a result, to generate large volumes of plasma, it is important to overcome the critical density that limits wave propagation. The critical density is the density of charged species in the plasma above which waves are reflected. This limits the long-distance propagation of the excitation wave and, therefore, the propagation of the plasma itself. Plasma causes a self-screening effect. To overcome this limitation, it is necessary to distribute the plasma source in an intelligent manner to generate a uniform plasma annular zone with a high energy content.

[0064] A schematic diagram of a preferred embodiment is shown in Figure 10B. In this embodiment, antennas (12) are arranged around the circumference to create a plasma torus that allows the gas exiting the nozzle (3) to be uniformly treated with high-density microwave plasma to maximize conversion.

[0065] By placing the antennas at equal but well-selected mutual distances, as shown schematically in Figure 10C, it is possible to generate an axially symmetric, intense plasma located at a distance R from the reactor center. The optimal distance produces a uniform resultant power density along the axis by superimposing the evanescent waves from each antenna. This allows the generation of a uniform plasma torus distributed over a circle joining the antenna centers.

[0066] Figures 4A, 4B, and 4C illustrate an embodiment of a plasma reactor with dielectric barrier discharge (DBD) plasma generation. DBD requires two electrodes coated with a dielectric material. In a preferred embodiment, the electrodes are upstream and downstream gas expansion disks, as shown in Figure 4C. The cores of the upstream and downstream gas expansion disks 10 and 12 are made of conductive materials, such as stainless steel, refractive metal alloys, conductive carbides, and conductive metal oxides. The outer surfaces of the upstream and downstream gas expansion disks are coated or covered with a dielectric material, such as Al2O3, SiO2, or ZrO2. A dielectric barrier discharge is generated by applying a high-voltage generator to one electrode 10 or 12 and grounding the other electrode. This configuration is advantageous because plasma power is generated uniformly within the space between the downward-facing and upward-facing gas expansion disks. Furthermore, there is complete overlap with the expanding gas layer. By limiting the length of the gas expansion disk or the electrode core within the gas expansion disk, a first well-controlled plasma dissociation zone can be created within the reactor volume, followed by a second condensation and recombination zone. For example, methane can be dissociated into atomic hydrogen, carbon, and their ions in the dissociation zone, and then condensed to form hydrogen gas, H2, and carbon nanopowder in the condensation zone.

[0067] 5A and 5B show an embodiment of a plasma reactor with a gliding arc plasma generation means. A gliding arc hybrid plasma is generated between a pair of electrodes 15.I and 15.II. An electric arc can be ignited inside the gas layer in the reactor space, preferably near the gas injection slit. This creates a hot plasma zone (dissociation zone) that promotes strong dissociation of the reactant gases. As the gas expands radially, the power density decreases, generating zones with cooler plasma and / or no plasma at all, which allows for the condensation process.

[0068] The downstream gas expansion disk and any upstream gas expansion disk can be advantageously used to support electrodes 15.I and 15.II. FIG. 5C illustrates an embodiment of the gliding arc plasma generating means in which both electrodes 15.I and 15.II are disposed on the upstream gas expansion disk 4. In another embodiment, both electrodes 15.I and 15.II can be disposed on the downstream gas expansion disk 6. FIG. 5D illustrates an embodiment of the gliding arc plasma generating means in which a first electrode 15.I is disposed on the upstream gas expansion disk 4 and a second electrode 15.II is disposed on the downstream gas expansion disk. The electrodes are made from conductive materials capable of withstanding high temperatures, such as stainless steel wire, various high-temperature alloys, conductive ceramics, etc. Suitable deposition techniques are known in the art. The electrodes are preferably wire-shaped and radially disposed. The electrodes preferably have a thickness of 0.05 to 2 mm, more preferably 0.1 to 1 mm.

[0069] A cross-sectional top view of an embodiment of a plasma reactor without vanes is shown in FIG. 6A. A cross-sectional top view of an embodiment of a plasma reactor with vanes is shown in FIG. 6B. Stator vanes are preferably mounted near the gas injection slits on the side of the reactor space and can be used to adjust the injection angle and flow of gaseous reactants into the reactor space through the Young-Coanda effect. In particular, vortices or turbulence can be generated, which can improve the mixing of gas and plasma in the reactor. The vortices have a significantly increased flow path within the reactor, which is associated with a greater reduction in gas velocity within the reactor. This is beneficial because it allows the axial gas inlet to operate at higher pressures.

[0070] FIG. 7A shows the inertial force P in the reactor space as a function of the width H [m] between the upstream expansion disc and the downstream expansion disc. P / P K A graph showing the ratio of dissipation forces to [-] is shown. As a result, kinetic heat dissipation is high at low widths H. In particular, when H is less than 0.01 cm, kinetic forces are larger than inertial forces. This graph shows the maximum gas velocity v maxThe flow rate is assumed to be 340 m / s and the reactor diameter L is assumed to be 0.5 m.

[0071] FIG. 7B shows the inertial force P of the expanding gas in the reactor space as a function of the gas velocity (m / s). P / P K A graph showing the ratio of dissipation force to [-] is shown. This graph shows the case of widths H [m] between the upstream and downstream expansion disks of 1 cm and 0.25 cm, respectively. At sufficiently low gas velocities, a width H of 1 cm is sufficient for high kinetic heat dissipation. At high gas velocities, a width H of 0.25 cm can maintain high kinetic heat dissipation relative to inertial forces.

[0072] The present invention is not limited in any way to the embodiments described in the examples and / or shown in the drawings, but rather the method according to the invention can be implemented in many different ways without departing from the scope of the invention. [Explanation of symbols]

[0073] 1. High pressure gas source 2 Axial gas inlet 3 Radial exit slit 4 Upstream gas expansion disc (optional) 5. Description of possible gas expansion in the reactor space 6 Downstream gas expansion disc 7 Cylindrical reactor vessel 8 Wave Source 9 Waveguides and impedance matching devices are suitable for conditioning and directing waves. 10 Inner core of upstream gas expansion disk (electrode) 11 Outer cladding or coating of upstream gas expansion disk (dielectric) 12 Inner core of downstream gas expansion disk (electrode) 13 Outer cladding or coating of downstream gas expansion disk (dielectric) 14 Gliding Arc Hybrid Plasma Description 15 15.I and 15.II are a pair of electrodes between which a gliding arc hybrid plasma is generated. 16 Heat exchanger 17 Liquid Refrigerants 18 Refrigerant vapor 19 Evanescent point source

Claims

1. A plasma reactor comprising: - reactor space, an axial gas inlet adapted for axial fluid flow, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of said radial injection slit in relation to said axial direction; - plasma generating means suitable for ionizing the gaseous medium in said reactor space, and a cylindrical reactor vessel, coaxial with said gas inlet and surrounding said reactor space, said reactor vessel being provided with outlet means.

2. 10. The plasma reactor of claim 1, wherein said plasma reactor further comprises an upstream gas expansion disk extending radially from said coaxial inlet and positioned upstream of said radial injection slit relative to said axial direction.

3. 3. The plasma reactor of claim 2, wherein a width H between the downstream gas expansion disk and the upstream gas expansion disk is less than 10 cm.

4. 4. The plasma reactor of claim 1, further comprising a hollow upstream gas expansion disk, the upstream gas expansion disk being a hollow cylinder, the hollow upstream gas expansion disk comprising a tangential preheating gas inlet and an axial preheating gas outlet, the axial preheating gas outlet being in fluid communication with the axial gas inlet.

5. The plasma reactor of any one of claims 1 to 4, wherein the downstream gas expansion disk comprises a heat exchange means.

6. The plasma reactor of any one of claims 1 to 5, wherein the radial injection slits comprise radially extending vanes.

7. 7. The plasma reactor of any one of claims 1 to 6, wherein said plasma generating means is selected from the list of a wave source, a dielectric barrier discharge (DBD), a gliding arc or a combination thereof.

8. below: - reactor space, an axial gas inlet adapted for axial fluid flow, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of said radial injection slit in relation to said axial direction; a cylindrical reactor vessel coaxial with said gas inlet and surrounding said reactor space, wherein said cylindrical reactor vessel is provided with outlet means; at least one wave source, and at least one waveguide configured to generate at least partially plane waves in the reactor volume; The plasma reactor of any one of claims 1 to 7, comprising:

9. below: - reactor space, an axial gas inlet adapted for axial fluid flow, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of said radial injection slit in relation to said axial direction; an upstream gas expansion disk extending radially from the coaxial inlet and located upstream of the radial injection slit with respect to the axial direction, the upstream gas expansion disk and the downstream gas expansion disk comprising an electrically conductive inner core and an outer dielectric coating; and a cylindrical reactor vessel, coaxial with said gas inlet and surrounding said reactor space, said reactor vessel being provided with outlet means; The plasma reactor of any one of claims 1 to 7, comprising:

10. below: - reactor space, an axial gas inlet adapted for axial fluid flow, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; a downstream gas expansion disk extending radially from the coaxial inlet and located downstream of the radial injection slit with respect to the axial direction, at least one electrode pair being deposited on the downstream gas expansion disk; and a cylindrical reactor vessel, coaxial with said gas inlet and surrounding said reactor space, said reactor vessel being provided with outlet means; The plasma reactor of any one of claims 1 to 7, comprising:

11. below: - reactor space, an axial gas inlet adapted for axial fluid flow, said axial inlet comprising a radial injection slit for discharging a jet of gaseous mixture into said reactor space; at least one electrode pair comprising a first and a second electrode; a downstream gas expansion disk extending radially from the coaxial inlet and positioned downstream of said radial injection slit with respect to said axial direction, said first electrode being deposited on said downstream gas expansion disk; an upstream gas expansion disk extending radially from the coaxial inlet and located upstream of the radial injection slit in relation to the axial direction, the second electrode being deposited on the upstream gas expansion disk; and a cylindrical reactor vessel, coaxial with said gas inlet and surrounding said reactor space, said reactor vessel being provided with outlet means; The plasma reactor of any one of claims 1 to 7, comprising:

12. 6. The plasma reactor of claim 5, wherein the heat exchange means is suitable for a liquid-liquid cooling mode and an evaporative cooling mode, and the heat exchange means is suitable for switching between the liquid-liquid cooling mode and the evaporative cooling mode.

13. A multi-stage plasma reactor comprising a stack of plasma reactors according to any one of claims 1 to 12.

14. Use of a plasma reactor or a multi-stage plasma reactor according to any one of claims 1 to 13.

15. Use of a plasma reactor or a multi-stage plasma reactor according to any one of claims 1 to 14 for hybrid plasma decomposition of methane to hydrogen.

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