Smoke separation process

Abstract

The present invention relates to a process for separating a heterogeneous solid-gas mixture comprising a solid carbon fraction and a gas fraction, the process operating in a high temperature Top and low oxygen environment, the process comprising the steps of preparing a liquid metal, the liquid metal having a gas-liquid interface, and directing the solid-gas mixture to the gas-liquid interface of the liquid metal.

Description

[Technical field]

[0001] The present invention relates to a process for the separation of heterogeneous solid-gas mixtures or smoke. In certain embodiments, the present invention relates to a high temperature process operating in a low oxygen environment that is particularly suitable for capturing and concentrating the solid fraction from a solid-gas mixture. [Background technology]

[0002] In physical or chemical processing systems that produce gases and particulates, particulate filtration is accomplished using gas-solid separation systems. Gas-solid separation systems can include cyclone filters, back-pulse filters, or other filters. For example, it is difficult to filter carbon-containing particles from hydrogen gas generated in chemical processing systems. In some cases, the particles generated are very small (e.g., median particle size 100 nm or less), which exacerbates the particle filtration challenge. Some gas-solid separation systems for separating carbon-containing particles from gas streams use back-pulse filters. In some cases, the back-pulse filters employ heated filters (e.g., heated filter candles). In some of these systems, the back-pulse filters are periodically purged by blowing gas through the filter candles (i.e., using a back-pulse that flows gas in the opposite direction to the filtration direction) to remove the carbon-containing particles. Other gas-solid separation systems for separating carbon-containing particles from hydrogen gas use cyclone separators. In some cases, the cyclone separators are also heated.

[0003] US 10 781 103 discloses a microwave chemical processing system having a microwave plasma reactor and a multi-stage gas-solid separation system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Pat. No. 10,781,103 Summary of the Invention [Problem to be solved by the invention]

[0005] Chemical reactors that convert hydrocarbons into carbon particles commonly suffer from carbon deposits that foul and plug the equipment. The deposited carbon layer typically increases pressure drop and reduces the thermal efficiency of the equipment. In addition, fouling and plugging conditions change process parameters, making the process difficult to control. This is particularly problematic in plasma reactors, where process control is inherently complex. Finally, removal of carbon deposits typically requires equipment downtime. [Means for solving the problem]

[0006] The present invention and its embodiments contribute to providing a solution to one or more of the above-mentioned disadvantages. To this end, the present invention relates to a separation process as claimed in claim 1.

[0007] Preferred embodiments of the device are set forth in any of claims 2 to 14. A specific preferred embodiment relates to the invention as defined in claim 2. Tin, gallium, indium, bismuth, their alloys and their eutectics are particularly suitable for the separation of solid carbon. These metals do not readily form carbides and are therefore preferred in order to avoid reactions of solid carbon with liquid metals. Furthermore, these metals do not form stable hydrides at high temperatures and therefore allow the separation of solid carbon from gas mixtures containing hydrogen.

[0008] In a second aspect, the invention relates to a use according to claim 15. The use described herein advantageously allows an effective separation at high temperatures of a gaseous mixture of hydrocarbons, hydrogen, nitrogen or argon and solid carbon. This is particularly advantageous for separating solid carbon and gas after high-temperature conversion of hydrocarbons into a gaseous mixture of solid carbon and hydrogen.

[0009] In a third aspect, the present invention relates to a use as defined in claim 15. The kit / use as defined herein provides advantageous effects.

[0010] The following description of figures of specific embodiments of the invention are merely exemplary in nature and are not intended to limit the teachings of the invention, its application, or uses. Corresponding reference numerals indicate like or corresponding parts and features throughout the drawings. [Brief description of the drawings]

[0011] [Figure 1] (Left) shows a schematic cross-section of a separation process according to the invention, where the liquid metal has a linear flow pattern; (right) shows a schematic top view of a separation process according to the invention, where the liquid metal has a linear flow pattern. [Diagram 2] FIG. 1 shows a schematic cross-section of a separation process according to the invention, where the liquid metal has a low angular velocity (left side) and where the liquid metal has a high angular velocity (right side). [Diagram 3] (Left side) shows a schematic cross-section of a separation process according to the invention, where a solid-gas mixture is injected into a rotating liquid metal. (Right side) shows a schematic top view of a separation process according to the invention, where a solid-gas mixture is injected into a rotating liquid metal. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention relates to a process for the separation of a heterogeneous solid-gas mixture.

[0013] Unless otherwise defined, all terms used in disclosing the present invention, including technical and scientific terms, have the meaning commonly understood by one of ordinary skill in the art to which this invention belongs. As a further guide, definitions of terms are included to better understand the teachings of the present invention.

[0014] As used herein, the following terms have the following meanings.

[0015] As used herein, "A," "an," and "the" refer to singular and plural references unless the context clearly dictates otherwise. By way of example, "a compartment" refers to one or more compartments.

[0016] "About," as used herein to refer to a measurable value such as a parameter, amount, time duration, and the like, is meant to encompass a variation of no more than ±20%, preferably no more than ±10%, more preferably no more than ±5%, even more preferably no more than ±1%, and even more preferably no more than ±0.1% of the stated value, to the extent that such variations are appropriate for the practice of the disclosed invention, although it is to be understood that the value to which the modifier "about" refers is itself specifically disclosed.

[0017] As used herein, "comprise," "comprising," and "comprises," "comprising of" are synonymous with "include," {including}, "includes," or "contain," "containing," or "contains," and are inclusive or open-ended terms that specify the presence of what follows, e.g., components, and do not exclude or preclude the presence of additional, non-repetitive components, features, elements, materials, or steps that are known in the art or disclosed therein.

[0018] Moreover, the terms first, second, third, etc. in this specification and claims, unless specified otherwise, are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order. The terms so used are interchangeable under appropriate circumstances, with it being understood that the embodiments of the invention described herein are capable of operating in sequences other than those described or illustrated herein.

[0019] The recitation of numerical ranges by endpoints includes all values ​​and fractions subsumed within that range, as well as the recited endpoints.

[0020] The terms "% by weight," "weight percent," "% wt," or "wt%," unless otherwise defined, herein and throughout this specification refer to the relative weight of each component based on the total weight of the formulation.

[0021] While the term "one or more" or "at least one" is itself clear, e.g., one or more or at least one member(s) of a group of members, by way of further illustration, 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 of said members, etc., up to and including all of said members.

[0022] Unless otherwise defined, all terms used in the disclosure of the present invention, including technical and scientific terms, have the meaning commonly understood by those skilled in the art to which the present invention belongs. As a further guide, definitions of terms used herein 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.

[0023] 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, the appearance 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. 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 features but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the present invention and 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.

[0024] In a first aspect, the present invention relates to a process for the separation of a heterogeneous solid-gas mixture comprising a solid carbon fraction and a gas fraction, said process comprising the steps of: op and operating in a low oxygen environment, said process comprising: a step of preparing a liquid metal, the liquid metal having a gas-liquid interface; directing the solid-gas mixture to the gas-liquid interface of the liquid metal; Equipped with.

[0025] In a preferred embodiment, the liquid metal is selected from the group of tin, indium gallium, bismuth, their alloys and eutectics. Particularly preferred liquid metals are pure tin, pure gallium, pure indium, Galinstan alloy (67 wt.% Ga, 20.5 wt.% In, 12.5 wt.% Sn), Wood's metal also known as Lipowitz alloy (50 wt.% Bi, 26.7 wt.% Pb, 13.3 wt.% Sn, 10 wt.% Cd). Caution is advised as Lipowitz alloy is toxic. In a more preferred embodiment, the liquid metal is at least 30 wt.% tin, more preferably at least 40 wt.% tin, more preferably at least 50 wt.% tin, more preferably at least 60 wt.% tin, more preferably at least 70 wt.% tin, more preferably at least 80 wt.% tin, more preferably at least 90 wt.% tin, more preferably at least 95 wt.% tin, more preferably at least 97 wt.% tin, more preferably at least 98 wt.% tin, more preferably at least 99 wt.% tin, more preferably at least 99.5 wt.% tin. Suitable alloying materials with tin are gallium, indium, silver, copper, and lead. Tin is preferred because it is liquid at moderate temperatures (i.e., 232°C). Tin has limited interaction with hydrogen and hydrocarbons at high temperatures. Several hydrides are known, but these are thermodynamically unfavorable and require strong reducing agents. Hydrogen hardly diffuses or dissolves in liquid tin, allowing good separation of these gases from liquid metal mixtures. Furthermore, tin does not form carbides or hydrides at high temperatures. Liquid tin does not readily wet solid carbon, allowing efficient separation of solid and liquid metals. Liquid tin has a very low vapor pressure at high temperatures, reducing metal losses and contamination of the gas phase. Liquid metals, such as liquid tin, are generally denser. This increases buoyancy and facilitates the separation of solid particles, especially carbon particles. It also increases the heat capacity of the liquid, improving its function as a working fluid in heat exchangers.

[0026] An additional advantage of liquid metals such as tin is their high electrical and thermal conductivity, which allows them to fulfill additional functions beyond separation, such as heat exchange fluids and / or electrodes (e.g., the electrical resistivity of tin between 473 K and 1673 K is 40-80×10 -8 Ω.m).

[0027] In a preferred embodiment, the heterogeneous solid-gas mixture has a solid fraction of at least 1 wt.%, more preferably at least 5 wt.%, more preferably at least 10 wt.%, more preferably at least 15 wt.%, more preferably at least 20 wt.%, more preferably at least 25 wt.%, more preferably at least 30 wt.%, more preferably at least 40 wt.%, more preferably at least 50 wt.%. In a preferred embodiment, the solid fraction is 1-80 wt.%, more preferably 5-75 wt.%, more preferably 10-75 wt.%, more preferably 20-75 wt.%, more preferably 30-75 wt.%, and most preferably 50-75 wt.%. Complete conversion of the hydrocarbons to solid carbon and hydrogen gases results in a solid fraction of 50-75 wt.%, which is optimal. However, complete conversion is difficult. As the conversion rate decreases, the solid fraction in the mixture also decreases, since more gaseous hydrocarbons remain. Good separation is obtained over all ranges, but energy efficiency decreases as the solids fraction decreases.

[0028] In another embodiment, the liquid metal can be utilized as a working fluid for heat exchange. In a more preferred embodiment, heat exchange takes place between the gas-solid mixture to be separated and a fluid reactant, preferably a hydrocarbon, convertible to hydrogen and solid carbon. In a preferred embodiment, the process further comprises the step of preheating a fluid (i.e. liquid or gas) by injecting said fluid into the liquid metal. In a preferred embodiment, said fluid is a reactant (herein "fluid reactant"), more preferably said fluid consists of a hydrocarbon mixture. In an embodiment where a reactor and a separator are combined, this preheating can take place in the same vessel forming a separate gas-liquid interface. In a further embodiment, the fluid is injected at one injection point, for example in a pipe perforated with a hole size of less than 1 mm, while in a more preferred embodiment, the fluid is injected at two or more injection points, preferably spaced apart at an angle of up to 180°, using a diffuser, for example a sintered ceramic with a controlled degree of porosity. This allows a better distribution of the gas bubbles and avoids them rising too quickly to the surface. In further preferred embodiments, the fluid is injected tangentially to obtain a helical flow pattern. More preferably, the liquid metal is forced into a helical vortex about an axis and the fluid reactants are injected such that a counterflow to the helical vortex is achieved. These preferred embodiments improve micromixing and heat exchange between the liquid metal and the fluid reactants.

[0029] The process or operating temperature T as defined herein op refers to an operating temperature measured in the gas phase at the gas-liquid interface of at least 250° C. As defined herein, “high temperature” refers to a temperature of at least 250° C. In a preferred embodiment, the operating temperature T op is at least 300° C., and more preferably T op is at least 400°C, more preferably T op is at least 500°C, more preferably T op is at least 600°C, more preferably T opis at least 700°C, more preferably T op is at least 800°C, more preferably T op is at least 900°C, more preferably T op is at least 1000°C, more preferably T op is at least 1100°C, more preferably T op is at least 1200°C. The separation process defined herein is suitable for separation of reaction mixtures from pyrolysis, reductive gasification, low temperature, hybrid (such as positive or energetic or microwave discharge) and high temperature plasma reactors (such as tri-arc plasma reactors). The separation process of the present invention is particularly suitable for plasma reactors, since liquid metal can be utilized as a self-healing electrode and heat exchange fluid. Furthermore, plasma reactors are suitable for converting hydrocarbons to solid carbon and hydrogen in low oxygen environments.

[0030] The separation process defined herein is designed for high temperature processing of solid carbon and preferably further comprises gaseous hydrogen. As a result, the process requires a low oxygen environment to prevent oxidation of the solid carbon to gaseous CO and / or CO2 and oxidation of hydrogen gas to water vapor. As a further advantage, this prevents the formation of significant amounts of metal oxides. As used herein, a low oxygen environment refers to an oxygen concentration in the gas mixture of up to 5v.%, preferably less than 3v.%, more preferably less than 1v.%, even more preferably less than 0.5v.%, more preferably less than 0.1v.%. More preferably, less than 0.05v.% oxygen, more preferably less than 0.01v.% oxygen, more preferably less than 50ppm oxygen, more preferably less than 25ppm oxygen, more preferably less than 10ppm oxygen, more preferably less than 5ppm oxygen, more preferably less than 1ppm oxygen.

[0031] In some embodiments, the input material and / or gas fraction is at most 10 v.%, preferably less than 5 v.% CO2, more preferably less than 3 v.% CO2, more preferably less than 1 v.% CO2, more preferably less than 0.5 v.% CO2, more preferably less than 0.1 v.% CO2, more preferably less than 0.05 v.% CO2, more preferably less than 0.01 v.% CO2, more preferably less than 50 ppm CO2, more preferably less than 25 ppm CO2, more preferably less than 10 ppm CO2, more preferably less than 5 ppm CO2, more preferably less than 1 ppm CO2. In some embodiments, the input material and / or gas fraction is at most 10 v.%, preferably less than 5 v.%, more preferably less than 3 v.%, more preferably less than 1 v.%, more preferably less than 0.5 v.%, more preferably less than 0.1 v.% water, more preferably less than 0.05 v.% water, more preferably less than 0.01 v.% water, more preferably less than 50 ppm water, more preferably less than 25 ppm water, more preferably less than 10 ppm water, more preferably less than 5 ppm water, more preferably less than 1 ppm water.

[0032] In some embodiments, the input material and / or gas fraction comprises water (H2O) in an amount of at most 5 v.% H2S, more preferably less than 3 v.% H2S, more preferably less than 1 v.% H2S, more preferably less than 0.5 v.% H2S, more preferably less than 0.1 v.% H2S, more preferably less than 0.05 v.% H2S, more preferably less than 0.01 v.% H2S, more preferably less than 50 ppm H2S, more preferably less than 25 ppm H2S, more preferably less than 10 ppm H2S, more preferably less than 5 ppm H2S, more preferably less than 1 ppm H2S. The sulfur content of the gas-solid mixture should be minimized to avoid excessive reaction with the liquid metal, since metals generally form sulfides.

[0033] In a preferred embodiment, the solid-gas mixture to be separated is produced by a plasma reactor or plasma chemical reactor. A plasma reactor or plasma chemical reactor uses a plasma source to generate a plasma, which is used to convert an input material into separated components, i.e., "pyrolysis" or "plasmolysis" or "plasmalysis". In some cases, the separated components include a mixture of solid particles and gaseous products. In such systems, the plasma chemical reactor can be designed to produce gases and particles with desired properties (e.g., product gas species, product gas purity, particle composition and crystal structure, particle size, surface area, mass density, electrical conductivity, etc.) from a particular input material. The input material properties (e.g., input material species, input material purity, etc.) can also affect the properties of the heterogeneous solid-gas mixture (e.g., product gas species, product gas purity, particle composition and crystal structure, particle size, surface area, mass density, electrical conductivity, etc.). Additionally, in plasma chemical processing systems that produce a mixture of solid particles and gaseous products, a gas-solid separation system is important. In a preferred embodiment, the input material of said plasma reactor consists of a hydrocarbon fluid, preferably a hydrocarbon gas. In some embodiments, the plasma reactor also includes an inlet configured to receive the input material, through which the input material flows into the reaction zone, where the input material is separated into a heterogeneous solid-gas mixture (e.g., hydrogen gas and carbon particles) by the plasma. The heterogeneous gas-solid mixture thus obtained can be advantageously separated by the separation process according to the invention. Compared to conventional separation techniques, the invention is much better able to separate very small particle sizes, such as in the nm range. Furthermore, the high temperatures required to obtain the plasma are well combined with the temperatures required for liquid metal. In a preferred embodiment, the input material is a hydrocarbon gas, such as CH4, C2H2, C2H4, C2H6, etc. In some embodiments, the input material is an industrial gas, such as natural gas, biogas, etc. In some embodiments, the input material is a mixture of natural gas and hydrogen gas, or a mixture of biogas and hydrogen gas.In some embodiments, the process material is methane, ethane, ethylene, acetylene, propane, propylene, butane, butylene, butadiene, or mixtures thereof, and the output of the plasma chemical reactor is hydrogen, hydrocarbons, and particulate carbon, preferably nanoparticulate carbon. The particulate carbon can be advantageously separated from the hydrogen and hydrocarbon fluids using the separation process of the present invention. Natural gas (NG) feedstocks generally include methane and ethane.

[0034] In a preferred embodiment, a transducer (or sonotrode) is used to inject a well-controlled ultrasonic flux into the liquid metal at at least one point: i) the cavitation effect induced by the relaxed ultrasound allows firstly to generate a larger number of smaller bubbles, thus increasing the gas-liquid exchange surface, ii) the ultrasound can cause bubble coalescence leading to larger bubbles that move slower in the liquid metal (Stokes' law), iii) the chock waves induce locally high temperatures and pressures that favor the crystallized carbon form at a reasonable average temperature of the liquid metal, iv) the power of the acoustic waves used and their distribution in the liquid also strongly influence the number of nucleation sites of carbon particles and their further coalescence, modulating their physical and chemical properties.

[0035] In another preferred embodiment, the plasma reactor can also be combined with an ultrasonic source in the gas phase and with a liquid metal separator.

[0036] NG may also contain other hydrocarbons such as propane, butane, pentane, etc. NG may also contain lower concentrations of other species such as nitrogen and carbon dioxide. In general, the composition of chemical species in natural gas varies depending on the source.

[0037] In a further embodiment, the liquid metal may further be utilized as a self-healing electrode for the plasma generating means. In another further embodiment, the liquid metal may be utilized as a heat exchange fluid to pre-heat the hydrocarbon inlet of said plasma reactor. In a more preferred embodiment, the separation system and the plasma reactor may be combined into a single process step rather than as subsequent process steps.

[0038] In a particularly preferred embodiment, the input material (preferably a fluid) of a chemical or plasma reactor can be passed through said liquid metal. This allows for very efficient heat exchange between the input material and the liquid metal without the need for additional equipment heating and pumping both fluids through said equipment designed to keep them separated. Advantageously, tin interacts very little with both the input and output materials in hydrocarbon to solid carbon and hydrogen type reactions.

[0039] In a preferred embodiment, the heterogeneous solid-gas mixture consists of hydrogen gas and carbon particles, and the solids loading, in terms of mass of solids per volume of gas, is greater than 0.001 g / L, preferably greater than 0.01 g / L, more preferably greater than 0.05 g / L, more preferably greater than 0.1 g / L, more preferably 0.15 g / L or more, more preferably 0.2 g / L or more, more preferably 0.25 g / L or more, more preferably 1 g / L or more, more preferably 2 g / L or more, more preferably 5 g / L or more, more preferably 0.001 g / L to 5 g / L, more preferably 0.001 g / L to 2.5 g / L, more preferably 0.001 g / L to 1 g / L, more preferably 0.001 g / L to 0.5 g / L, more preferably 0.001 g / L to 0.001 g / L. More preferably, the range is 0.01g / L to 0.1g / L, more preferably 0.01g / L to 5g / L, more preferably 0.01g / L to 2.5g / L, more preferably 0.01g / L to 1g / L, more preferably 0.01g / L to 0.5g / L, more preferably 0.01g / L to 0.4g / L, more preferably 0.01g / L to 0.3g / L, more preferably 0.01g / L to 0.2g / L, more preferably 0.01g / L to 0.1g / L, more preferably 0.1g / L to 5g / L, more preferably 0.1g / L to 2.5g / L, more preferably 0.1g / L to 1g / L, more preferably 0.1g / L to 0.5g / L, more preferably 0.1g / L to 0.4g / L, more preferably 0.1g / L to 0.3g / L, and more preferably 0.1g / L to 0.2g / L.

[0040] In a preferred embodiment, a "solid carbon fraction" or "carbon material" has a ratio of carbon to other elements, excluding hydrogen, greater than 60%, preferably greater than 70%, more preferably greater than 80%, more preferably greater than 90%, more preferably or greater than 99%, more preferably greater than 99.5%, more preferably greater than 99.7%, more preferably greater than 99.9%, more preferably greater than 99.95%.

[0041] Throughout this application, the term "particle" or "particles" is a general term that can include particles of any size, including nanoparticles and aggregates. The solid carbon fraction or carbon material as defined herein consists of carbon particles. In a preferred embodiment, the solid carbon fraction consists of carbon aggregates, more preferably at least 50%, more preferably 70%, more preferably 80%, more preferably 90%, and most preferably 95%. In another preferred embodiment, the solid carbon fraction consists of carbon nanoparticles, more preferably at least 50%, more preferably 70%, more preferably 80%, more preferably 90%, and most preferably 95%. The carbon aggregates typically have a size of 1 micron to 50 microns, or 2 microns to 20 microns, or 5 microns to 40 microns, or 5 microns to 30 microns, or 10 microns to 30 microns, or 10 microns to 25 microns, or 10 microns to 20 microns. In some embodiments, the size distribution of the carbon aggregates has a 10th percentile of 1 micron to 10 microns, or 1 micron to 5 microns, or 2 microns to 6 microns, or 2 microns to 5 microns. The size of the particles that make up the aggregates can vary and can be smaller than 10 nm or up to hundreds of nanometers in size. In some embodiments, the aggregates are comprised of nanoparticles. The nanoparticles have an average diameter in the range of 5 to 500 nm, or 5 to 250 nm, or 5 to 100 nm, or 5 to 50 nm, or 10 to 500 nm, or 10 to 250 nm, or 10 to 100 nm, or 10 to 50 nm, or 40 to 500 nm, or 40 to 250 nm, or 40 to 100 nm, or 50 to 500 nm, or 50 to 250 nm, or 50 to 100 nm. In some embodiments, the size of the aggregates is measured using TEM images. In some embodiments, the size of the aggregates is measured using a laser particle size analyzer. In a further preferred embodiment, the carbon particles have a specific surface area, measured according to ASTM D6556, of 25 to 125 m 2 / g, more preferably 50 to 125m 2 / g, more preferably 75 to 125 m2 / g, most preferably 100 to 125 m 2 / g.

[0042] In a preferred embodiment, the process comprises: forming a predictable flow of the liquid metal at the gas-liquid interface; Equipped with. Buoyancy and other forces cause the solid fraction to rise to the gas-liquid surface. Advantageously, the flow of liquid metal at the gas-liquid interface carries the solid fraction to a desired location suitable for separation of the liquid metal and the solid fraction. The predictable flow of the liquid metal also allows for heat transport, which is advantageous considering that liquid metals generally have high heat capacity and high density.

[0043] In one embodiment, the gas-liquid interface is substantially horizontal. A horizontal gas-liquid interface allows operation at a predictable low flow rate, reducing operational costs. It also simplifies operation with fewer design constraints. This is desirable, for example, when the heterogeneous solid-gas mixture to be separated contains relatively large amounts of species that affect or react with the liquid metal, such as sulfur- or oxygen-containing species, or species that are not easily separated from the liquid metal. These species affect the physical properties of the liquid metal, and a setup that is less constrained by said physical properties may be desirable. In a preferred embodiment, the liquid metal flows with a linear flow velocity of less than 2.0 m / s, more preferably less than 1.5 m / s, and even more preferably less than 1.0 m / s.

[0044] In a preferred embodiment, the solid-gas mixture is directed towards the gas-liquid interface with a velocity v0 between 0.01 and 50 m / s, more preferably v0 between 0.05 and 25 m / s, more preferably v0 between 0.10 and 20 m / s, more preferably v0 between 0.50 and 15 m / s, more preferably v0 between 1.00 and 10 m / s, and most preferably about 5 m / s.

[0045] In another embodiment, the liquid metal is moved at an angular velocity ω L In a preferred embodiment, Lis sufficiently low to maintain a nearly horizontal gas-liquid interface. L is sufficiently high to form a two-dimensional helical or three-dimensional helical flow pattern and a conical gas-liquid interface. In one embodiment, the solid fraction may be separated from the liquid metal at the center of the conical gas-liquid interface. In another embodiment, the solid fraction may be collected at the tangential edge of the conical gas-liquid interface. The low angular velocity ω L At high angular velocities, the solid fraction is collected at the edge of the conical gas-liquid interface, i.e., the tangential edge of the bowl. L In this design, solids accumulate near the center of the conical gas-liquid interface. The difficulty with this design is that the depth of the vortex and the height of the cone increase with the angular velocity ω L and the physical properties of the liquid metal. In a further preferred embodiment, the collection mechanism at the center of the cone-shaped gas-liquid interface is adjustable in height. The adjustable collection mechanism can be adjusted via a control mechanism or can be self-adjusting, for example by utilizing buoyancy effects. In general, low angular velocities are required for ω L is substantially below 1 rad / s, and high angular velocities are observed above 1 rad / s, preferably above 1.3 rad / s. The angular velocities mentioned herein are the angular velocities of the liquid measured at the liquid-gas interface. Rotation of the liquid metal can be achieved by different means, as known in the art. For example, a pump suitable for liquid metals would suffice. In particular, if the liquid metal is used as the heat transfer fluid in an external heat exchanger, a pump will be needed regardless to move the liquid metal to the external heat exchanger. In such cases, a pump would be preferred. Alternatively, direct liquid movement by propellers, electric currents and / or magnetic fields, or a rotating drum with internal fins are also viable.

[0046] In a preferred embodiment, the rotation of the liquid metal is achieved by an impeller. Generally, a higher impeller rotation speed is required to obtain these angular velocities at the liquid-gas interface. Depending on the propeller design and the liquid used, these rotation speeds may be significantly higher. In a particular preferred embodiment, the propeller has vertical blades. The vertical blades have a surface that defines a plane, with the axis of rotation being parallel to said plane, and preferably the axis of rotation being within said plane. The vertical blades have been found to be very beneficial in increasing the angular velocity of the liquid itself, especially when compared to inclined blades and / or vanes that are common in the art. As a result, a helical or conical gas-liquid interface is obtained at a lower impeller rotation speed.

[0047] In a further preferred embodiment, the impeller has substantially vertical blades, preferably vertical blades, and the impeller rotates at a speed of at least 50 rpm, more preferably at least 100 rpm, more preferably 150 rpm, more preferably 200 rpm, more preferably 250 rpm, more preferably 300 rpm, more preferably 350 rpm, more preferably 400 rpm. The applicant has found that starting at 50 rpm using vertical blades, the liquid tin begins to exhibit a conical gas-liquid interface. This conical gas-liquid interface still has a low curvature, which is maintained up to an impeller rotation speed of approximately 100 rpm. When the rotation speed is further increased above 100 rpm, the curvature of the gas-liquid interface increases significantly. At 300 rpm, a very high curvature is observed. As a result, by using vertical blades, a gas-liquid interface with a high curvature can be obtained at a relatively low impeller rotation speed. Furthermore, this limits the energy used for diffusive mixing.

[0048] In another further preferred embodiment, the impeller has inclined blades and / or vanes and the impeller rotates at a speed of at least 50 rpm, more preferably at least 100 rpm, more preferably 150 rpm, more preferably 200 rpm, more preferably 250 rpm, more preferably 300 rpm, more preferably 350 rpm, more preferably 400 rpm. The applicant has found that starting at 200 rpm using inclined blades or vanes, the liquid tin begins to exhibit a conical gas-liquid interface. This conical gas-liquid interface still has a low curvature, even at impeller rotation speeds of approximately 400 rpm. As a result, by using inclined blades and / or vanes, high mixing energy and high impeller RPM can be obtained while maintaining a low curvature of the gas-liquid interface.

[0049] The impeller design, vessel design, their relative positions, and the liquid chosen all influence the resulting hydrodynamic regime. However, the above examples show that high mixing can be achieved with low gas-liquid interfacial curvatures. Similarly, high gas-liquid interfacial curvatures can be achieved with relatively low impeller RPMs. In a further embodiment, the solid-gas mixture is directed towards the gas-liquid interface under a grazing angle a, where the grazing angle a is measured with respect to an axis parallel to gravity. Preferably, a is between 5° and 85°, more preferably between 15° and 80°, more preferably between 30° and 80°, more preferably between 45° and 80°, and most preferably between 55° and 80°.

[0050] In a further embodiment, the solid-gas mixture is directed to the gas-liquid interface as a vortex flow, which is understood as a flow rotating around an axis, the flow having a translational component parallel to said axis, said axis being directed to the gas-liquid interface. In a preferred embodiment, the vortex flow has an angular component ω g wherein said angular component ω ghave an opposite direction to the angular velocity of the liquid metal. That is, these vortices of the liquid metal and the heterogeneous solid-gas mixture have opposing angular components (counterflow). This counterflow improves separation at the tradeoff of energy efficiency. In another embodiment, the vortices of the liquid metal and the heterogeneous solid-gas mixture have angular components in the same direction (parallel flow). These embodiments improve energy efficiency at the tradeoff of separation effectiveness.

[0051] In a further embodiment, the solid fraction may comprise a catalyst. The separation process according to the invention allows for separation of said catalyst from the gas, which can then be further separated from the remaining solid fraction and, if necessary, regenerated, and the regenerated catalyst recycled.

[0052] In another embodiment, the liquid metal may contain a catalyst. More preferably, the liquid metal may be utilized as a transport medium for said catalyst. Active catalysts are transition metals such as nickel, iron, copper, silver, cobalt, palladium, platinum, rhenium, etc., that can be solubilized and / or form eutectic with low-temperature molten metals (Sn, Ga, Bi, In). These catalytic liquid alloys modify the morphology and crystallographic properties of the formed carbon species (carbon black, nanotubes, nanofibers, graphene and graphite).

[0053] In a preferred embodiment, the liquid metal is held in a vessel or bowl made from graphite, carbon composite, ceramic, ceramic composite, aluminosilicate, glass, quartz, or mixtures thereof, which are materials that can be used at high temperatures and do not interact with the liquid metal.

[0054] In a preferred embodiment, the liquid metal bath has a depth of at least 0.001 m, more preferably at least 0.03 m, more preferably at least 0.05 m, more preferably at least 0.10 m. Preferably, the liquid metal bath has a depth of at most 1.0 m, more preferably at most 0.5 m, more preferably at most 0.3 m, more preferably at most 0.25 m.

[0055] In a preferred embodiment, the liquid metal bath has a width of at least 0.10 m, more preferably at least 0.15 m, more preferably at least 0.20 m, more preferably at least 0.25 m. Preferably, the liquid metal bath has a width of at most 0.50 m, more preferably at most 0.40 m, more preferably at most 0.30 m, more preferably at most 0.25 m.

[0056] In a preferred embodiment, the liquid metal can further be used as an electrode. In a further preferred embodiment, the liquid metal can be used as a self-healing electrode (e.g. for an arc plasma reactor). Liquid metals can be advantageously used as self-healing electrodes since they can be trivially replenished and the liquid-gas interface does not degrade even when bombarded by solid particles. Furthermore, liquid metals can also be used as radiation reflectors (e.g. ultraviolet, infrared or microwave guides).

[0057] In a second aspect, the present invention relates to the use of the process according to the first aspect for separating solid carbon from a gaseous mixture, preferably said gaseous mixture comprising a hydrocarbon, hydrogen, nitrogen or argon.

[0058] In a preferred embodiment, the process is used in combination with exhaust gases leaving a pyrolysis reactor, a gasification reactor (especially in reduction mode), a cold plasma reactor, a hybrid plasma reactor or a hot plasma reactor.

[0059] However, it is clear that the invention is not limited to this application: the method according to the invention can be applied to any kind of separation process.

[0060] The present invention is illustrated by the following non-limiting examples which further illustrate the invention but are not intended, and should not be construed, as limiting the scope of the invention.

[0061] The invention will now be described in more detail with reference to the following non-limiting examples.

[0062] Description of the drawings In order to better explain the properties of the present invention, the following presents, by way of example and without any limitation to other potential applications, a description of some preferred applications of the method for checking the condition of grouts used in mechanical connections according to the present invention. FIG. 1 (left side) shows a schematic cross-section of a separation process according to the invention, where the liquid metal has a linear flow pattern. FIG. 1 (right side) shows a schematic top view of a separation process according to the invention, in which the liquid metal has a linear flow pattern. FIG. 2 (left side) shows a schematic cross-section of a separation process according to the invention, where the liquid metal has a low angular velocity. FIG. 2 (right side) shows a schematic cross-section of the separation process according to the invention, where the liquid metal has a high angular velocity. FIG. 3 (left side) shows a schematic cross-section of a separation process according to the invention, where a solid-gas mixture is injected into a rotating liquid metal. FIG. 3 (right side) shows a schematic top view of the separation process according to the invention, where a solid-gas mixture is injected into a rotating liquid metal.

[0063] FIG. 1 shows a liquid metal vessel (1) separating a liquid-gas mixture (2) consisting of gas (3) and solids (4). The solid particles are pushed to the gas-liquid interface and float there due to buoyancy. A collector (8) is used to pick up the suspended (and agglomerated) solid particles while the gas fraction is released or removed. Various embodiments of the collector (8) are suitable, for example a filter with holes or slits. The liquid metal is separated into a channel and pumped back to the liquid metal vessel (1) at the liquid metal inlet (7) through the channel (5) by a pump (6), resulting in a steady linear flow at the gas-solid interface.

[0064] FIG. 2 shows two embodiments, one for low angular velocity ω1 (left) and one for high angular velocity ω2 (right). At low angular velocities, the particles agglomerate at the tangential end of the bowl. For this, a collector as described for FIG. 1 can be used and placed at the tangential end of the vessel. The collector can also be a sieve, especially if the liquid metal does not wet the solid particles and the separation of the liquid metal and the solid particles is easily obtained. The solid particles are removed from the collector 8 towards the storage chamber 10. The gas 9' is totally or partially removed and released again. At high angular velocities, the solid particles agglomerate in the center of the cone-shaped liquid-gas interface. The collector must therefore be installed with a well-defined shape in the vicinity of the axis of rotation so as not to disturb the formation of the vortex. For example, an overflow-collector can be used, such as a collecting cone 17. The collecting cone 17 is connected to a conveying means 18, which is then separated from the remaining liquid metal in a sieve 8. The agglomerated solids can then be removed and stored (10). As in the previous embodiment, the gas 9' is completely or partially removed and released.

[0065] Figure 3 shows a side view (left) and a top view (right) of an embodiment with an angled flow regime. The reactive gas is introduced into the rotating liquid metal through a submerged reactive gas injector 21 at a pressure greater than the pressure corresponding to the liquid metal height 11. To ensure a uniform gas distribution of the reactive gas into the liquid metal, in a preferred embodiment, multiple injectors (20 or 21) are used, which transform the liquid metal into a well-controlled liquid foam that allows a proper heat exchange between the reactive gas and the liquid metal. The ducts and injectors are made of materials that can operate at high temperatures and do not interact with the considered liquid metal. At least one annular duct 20 is used for reactive gas injection, drilled with multiple appropriately oriented holes / slits of suitable size (usually 0.1-10 mm). In an embodiment, a special porous part 21 is used to introduce the particle-free gas. The statistical distribution of the size of the gas bubbles and their spatial distribution in the foam are important factors. In a preferred embodiment, a transducer (or sonotrode) 22 allows a controlled ultrasonic flux to be injected into the liquid metal at at least one point.

[0066] The invention is in no way limited to the embodiments described in the examples and / or shown in the figures: on the contrary, the method according to the invention can be realized in many different ways without departing from the scope of the invention.

Claims

1. For the separation of a heterogeneous solid-gas mixture containing a solid carbon fraction and a gas fraction, a high temperature T ｏｐ and a process operating in a low oxygen environment, the process comprising: - preparing a liquid metal, the liquid metal having a gas-liquid interface; directing the solid-gas mixture to the gas-liquid interface of the liquid metal; A process comprising:

2. 2. The process of claim 1, wherein the liquid metal is selected from the group of tin, gallium, bismuth, alloys and eutectics thereof, preferably the liquid metal is tin.

3. 3. The process of claim 2, wherein the liquid metal is a eutectic of tin or bismuth and indium.

4. In the process according to any one of claims 1 to 3, the operating temperature T ｏｐ is at least 300°C, preferably at least 600°C.

5. The process according to any one of claims 1 to 4, wherein the gas fraction comprises a hydrocarbon, hydrogen, nitrogen or argon, preferably a hydrocarbon and hydrogen.

6. The process according to any one of claims 1 to 5, further comprising: - Producing a predictable flow of the liquid metal at the gas-liquid interface A process comprising:

7. The process according to any one of claims 1 to 6, wherein the gas-liquid interface is substantially horizontal.

8. In the process according to any one of claims 1 to 7, the liquid metal is moved at an angular velocity ω Ｌ Rotate with ω Ｌ is high enough to form a two-dimensional helical or three-dimensional helical liquid metal flow pattern and a conical gas-liquid interface, the process.

9. 9. The process of claim 8, wherein a solid fraction is collected at a tangential end of the conical gas-liquid interface.

10. 9. The process of claim 8, wherein the solid fraction is collected at the center of the conical gas-liquid interface.

11. 11. The process according to any one of claims 1 to 10, wherein the solid-gas mixture is directed towards the gas-liquid interface under a grazing angle a, the grazing angle a being measured with respect to an axis parallel to gravity.

12. The process according to any one of claims 1 to 11, wherein the solid-gas mixture is oriented as a vortex.

13. 9. The process of claim 8, wherein the solid-gas mixture is axially oriented with an angular component ω ｇ and said angular component ω ｇ is the angular velocity ω of the liquid metal Ｌ A process that has an opposite direction to that of

14. 12. The process of any one of claims 1 to 11, wherein the liquid metal is held in a vessel, the vessel being fabricated from graphite, carbon composite, ceramic, ceramic composite, aluminosilicate, glass, quartz or mixtures thereof.

15. The process according to any one of claims 1 to 12, wherein the liquid metal is further used as an electrode.

16. The process according to any one of claims 1 to 13, wherein the liquid metal is further used as a working fluid in a heat exchanger.

17. Use of the process according to any one of claims 1 to 14 for separating solid carbon from a gas mixture consisting of hydrocarbons, hydrogen, nitrogen or argon.

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