Plasma cyclone calcination reactor design

Abstract

A cyclone reactor design is provided in which the reactor comprises: an upper portion having a first smaller diameter (D1) and a first height (L2); a middle portion having a second diameter (D2); and a lower portion having a third smaller diameter (D3) and a third height (L4), where the upper, middle and lower directions are all in relation to the direction of gravity, where the second diameter (D2) is at least 1.25 times as large as the first smaller diameter (D1), and where the second diameter (D2) is at least 1.25 times as large as the third smaller diameter (D3), where the angles [alpha] l and [alpha] 2 are in the interval of 20 DEG to 65 DEG, and where the second diameter (D2) is at least 1.25 times as large as the third smaller diameter (D3). And wherein the reactor comprises at least one plasma torch, at least one inlet and at least one outlet. Advantages include the reactor having efficient energy transfer to the particles and allowing a compact design.

Description

Technical Field

[0001] The present disclosure relates to a compact swirl reactor with a plasma torch and a design for maximizing radiative heat transfer, and to methods for heat treating various materials in such a reactor. Background Art

[0002] The calcination of limestone is a well-known process that has been known for thousands of years.

[0003] US2012 / 0141354 discloses a method for separating and recovering high-concentration CO2 gas generated in a cement manufacturing facility. The method includes feeding a cement material before calcination and a heat medium having a particle size larger than that of the cement material and having been heated to a calcination temperature or higher in a medium heating furnace to a mixing calcination furnace, and recovering the CO2 gas generated by the calcination of the cement material. The heat medium circulates between the medium heating furnace and the mixing calcination furnace. One aspect of the present invention includes: feeding the cement material to a regenerative calcination furnace before calcination, the regenerative calcination furnace having been heated to a calcination temperature or higher and having stored heat therein; and recovering the CO2 gas generated by the calcination of the cement material.

[0004] US2014 / 0334996 discloses a process for producing a useful product in a reactor, the process including introducing a co-reactant containing a fuel source and oxygen through an inlet into a first section, the fuel source including carbon; burning at least a portion of the fuel source and oxygen in an exothermic reaction in the first section using a burner; transferring the co-reactant through a second section including a throat having a size smaller than the size of the first section, thereby creating a vacuum and increasing the velocity of the co-reactant; transferring the co-reactant to a third section located downstream of the throat and including an inner wall having a size larger than the size of the throat; depositing at least a portion of unburned carbon and metal oxide along the inner wall, wherein the metal oxide is introduced into at least one section; and converting the deposited metal oxide into a useful product in a carbothermal reduction reaction in a molten slag along the inner wall at a temperature of at least 1600°C.

[0005] US 4,152,169 discloses calcination in a plasma, where the plasma torch rotates. A swirler is used for preheating and subsequent separation, but not for the calcination reactor.

[0006] WO 02 / 096821 discloses a method of calcination using carbon dioxide plasma. There is a plasma generator as a separation stage before the calcination reactor. The carbon dioxide gas plasma has a temperature of 3000 °C to 4000 °C at the outlet of the plasma generator. The lime raw material is mixed with the hot gas from the plasma generator, i.e., the heat transfer mainly comes from the hot gas leaving the plasma generator. A cyclone is shown in a subsequent step after the calcination reactor. The calcination does not take place in the cyclone reactor.

[0007] WO 2020 / 232091 discloses a calcination in which gas recirculation is used. A calcination cyclone stage is disclosed. Preheating and heating are envisaged. The carbon dioxide gas in the calcination loop can be heated to 2000 °C by an electric heater. The electric heater can generate heat via induction, resistance, infrared, microwave, plasma, or any electricity-based means. Apparently, the calcination furnace can provide a temperature of up to 2000 °C, and this temperature is the upper limit temperature.

[0008] US2012 / 0263640 discloses a cyclone reactor for producing an available by-product as part of a recyclable slag layer, the reactor comprising: a housing having an outer wall defining a combustion chamber; an inlet configured to introduce reactants into the reactor; a burner configured to burn the reactants in a flame zone near the central axis of the chamber; and an outlet configured to remove the available by-product from the housing; wherein the reactor is configured to burn a first portion of the reactants in an exothermic reaction in the flame zone; and wherein the reactor is configured to convert a second portion of the reactants in an endothermic reaction near the outer wall to produce a by-product as part of the slag layer.

[0009] US2010 / 314788 discloses a system and method for preparing ultrafine particles. A high-temperature plasma is generated at the inlet end where the precursor material is introduced into the plasma chamber. During operation, a substantially constant pressure and / or material flow pattern is maintained to reduce or eliminate fouling of the system.

[0010] US2010 / 044477 discloses an apparatus for synergistically combining a plasma with a comminution device, such as a fluid kinetic mill (jet mill), preferably in a single reactor and / or in a single process step. Inside the apparatus, potential energy is converted into kinetic energy and subsequently into angular momentum by means of wave energy for the comminution, reaction, and separation of the feed material.

[0011] US 6,358,375 discloses a method and apparatus for the continuous production of carbon black with a high fullerene content. The apparatus basically comprises: a plasma reactor (1); a downstream thermal separator (2) for separating non-volatile components; and a cold separator (3) attached to the downstream thermal separator (2).

[0012] EP 2931849 discloses an apparatus and method for treating a substance within a selected temperature range as the substance passes through a first central portion of a first swirling gas stream and exits a second end of a first cylindrical container and / or through a second central portion of a second swirl and exits a fourth end of a second cylindrical container.

[0013] WO 2014 / 055574 discloses a multi-mode plasma torch comprising: a cylindrical container having a first end and a second end; a first tangential inlet / outlet connected to or near the first end; a second tangential inlet / outlet connected to or near the second end; an electrode housing connected to the first end of the cylindrical container such that a first electrode (a) is aligned with the longitudinal axis of the cylindrical container and (b) extends into the cylindrical container; and a hollow electrode nozzle connected to the second end of the cylindrical container such that the centerline of the hollow electrode nozzle is aligned with the longitudinal axis of the cylindrical container.

[0014] Even if at least some of the calcination methods according to the prior art are currently used completely successfully, there is still room for improvement in terms of their efficiency and performance. In addition, optimization of the reactor is desired. Summary of the Invention

[0015] The object of the present disclosure is to alleviate at least some of the problems in the prior art and to provide an improved heat treatment method and an apparatus for implementing the method.

[0016] What the inventors have recognized is that advantages can be obtained by performing heat treatment in a swirl reactor and providing at least one high-temperature volume V h in the reactor, i.e., a plasma torch. The high-temperature volume V his a zone in the reactor where the temperature is very high due to the plasma torch, for example at least 3000 °C. In reactors according to the art, thermal energy is transferred to the material to be calcined by heat conduction (at least to some extent), heat convection, and thermal radiation. What the inventors have found is that for materials in the form of smaller particles, if the proportion of thermal energy transferred by thermal radiation is increased, more efficient heating can be obtained. In particular, this is true for a swirl reactor, which is compact and of small volume, which results in a short distance between the hot plasma torch in the high-temperature zone and the particles to be heat-treated. In addition, the swirl reactor can be designed to further enhance the energy transfer by thermal radiation, for example by extending the residence time of the particles at a suitable distance from the high-temperature volume Vh. The high-temperature zone with a high temperature provides a higher proportion of heat transfer by thermal radiation, which, combined with the compactness of the swirl reactor, provides very efficient heat transfer to the particles. In the cyclone, the particles swirl around at a suitable distance from the high-temperature volume V h h, i.e., the plasma torch, and are thus heated to a large extent by thermal radiation. If the time at a suitable distance from the high-temperature volume Vh is increased, the energy transfer by thermal radiation will be further improved.

[0017] An important advantage is that, as observed from above, by positioning the hot plasma torch in the center of the reactor, or at least approximately in the center, the particles swirling around near the reactor wall will protect the reactor wall from being exposed to excessive temperatures, which otherwise could damage the reactor wall. The calcination reaction occurring in the swirling particles is actually an endothermic heat sink, which further prevents the temperature at the wall from reaching excessive values. Therefore, the reactor wall can be made of a cheaper material.

[0018] The centrifugal force acting on the particles swirling in the swirl reactor combined with the reactor design also helps to extend the residence time, so that the calcination reaction of the particles is completed, while the residence time of the gas is relatively short. In fact, heat transfer is not the limiting factor; rather, the limiting factor is the reaction kinetics of the calcination reaction of the particles. While maintaining the temperature at a suitably high level, the calcination reaction requires a certain amount of time to be fully completed. This reactor design ensures that the residence time of the particles in the appropriate thermal radiation is long enough for the calcination reaction to be completed.

[0019] If the reactor is designed such that the particles will be dispersed over a larger volume at a suitable distance from the high-temperature volume Vh, the thermal radiation will reach all the particles more effectively, because there will be fewer particles blocked by other particles.

[0020] The result is faster heating and more uniform heat transfer to all the particles. The proportion of particles in the cyclone that are not immediately heated is minimized.

[0021] In addition, the temperature difference ΔT during the process increases, which also improves the efficiency of the process. Additionally, the elevated temperature of the material leaving the cyclone reactor minimizes the spontaneous recombination of the heat-treated product. As an example of calcining CaCO3, before the released CO2 is separated from the formed CaO, the newly formed CaO does not react with the released CO2 to any interfering extent to form CaCO3.

[0022] Therefore, the efficiency can be increased, the speed of calcination can be increased, and the reactor can be made compact.

[0023] In a first aspect, there is provided a reactor, wherein the reactor is a cyclone reactor, and wherein the reactor comprises: an upper portion having a first smaller diameter (D1) and a first height (L2); a middle portion having a second diameter (D2); and a lower portion having a third smaller diameter (D3) and a third height (L4), wherein the upper, middle, and lower directions are all relative to the direction of gravity, wherein the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), and wherein the first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2), and the third height (L4) are selected such that:

[0024]

[0025] And wherein the reactor comprises at least one plasma torch, at least one inlet, and at least one outlet.

[0026] In a second aspect, there is provided a heat treatment method, wherein a material is heat-treated in a cyclone reactor, and wherein the reactor comprises: an upper portion having a first smaller diameter (D1) and a first height (L2); a middle portion having a second diameter (D2); and a lower portion having a third smaller diameter (D3) and a third height (L4), wherein the upper, middle, and lower directions are all relative to the direction of gravity, wherein the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), and wherein the first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2), and the third height (L4) are selected such that:

[0027]

[0028] And wherein the reactor comprises at least one plasma torch, at least one inlet and at least one outlet, wherein the material is conveyed in a swirling gas flow, and wherein the material is heated at least by thermal radiation by at least one plasma torch.

[0029] Furthermore, embodiments are defined in the appended dependent claims.

[0030] Advantages include an increase in the radiant heat transferred to the material. This provides a very high heat transfer coefficient, thus allowing a large amount of heat to be rapidly transferred to the particles. The heat transfer is affected by the presence of a hot core, i.e., by the hot volume portion of the plasma torch, in which the radiant heat is proportional to T 4 is proportional to.

[0031] Furthermore, the advantage is that more energy can be transferred to the particles due to the extended residence time in the reactor.

[0032] The result is a compact reactor where the residence time of the gas is short, but the residence time of the particles is much longer. This provides a very efficient process and allows for the design of an efficient and compact reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Aspects and embodiments will be described with reference to the following drawings, in which:

[0034] Figure 1 Calcination is shown as a function of the peripheral temperature in a swirl reactor for Example 4.

[0035] Figure 2 Calcination is shown as a function of the peripheral temperature in a plasma swirl reactor for Example 5.

[0036] Figure 3 Calcination is shown as a function of the downstream temperature of a plasma swirl reactor for Example 6.

[0037] Figure 4 A simplified side view of a swirl reactor is shown. The material is fed pneumatically from the side through a tube (not shown) into the swirler. The diameter (D1) of the upper part, the diameter (D2) of the middle part, and the diameter (D3) of the lower part are shown. Furthermore, the diameter (D4) of the outlet is shown. In this embodiment, the outlet is located in the lowermost part of the swirl reactor. Additionally, the heights of the different sections are indicated by L1, L2, L3, L4, and L5. The total height of the reactor is L1 + L2 + L3 + L4 + L5. The angles of the tapered portions of the reactor are indicated by α1 and α2. These angles are between 20° and 65° with respect to a line in the direction of gravity that is parallel to the central axis of the swirl reactor. DETAILED DESCRIPTION

[0038] Before the present invention is disclosed and described in detail, it should be understood that the present invention is not limited to the specific compounds, configurations, method steps, substrates and materials disclosed herein, as such compounds, configurations, method steps, substrates and materials may vary. It should also be understood that the terms used herein are for the purpose of describing specific embodiments only and are not intended to be limiting, as the scope of the present invention is limited only by the appended claims and their equivalents.

[0039] It must be noted that, as used in this specification and the appended claims, unless the context clearly dictates otherwise, the singular forms "a", "an" and "the" include plural referents.

[0040] If not otherwise defined, any terms and scientific terms used herein are intended to have the meanings commonly understood by those skilled in the art to which the present invention pertains.

[0041] As used herein, the term "calcination" particularly refers to the treatment of limestone (CaCO3) to produce calcium oxide (CaO). As used herein, the term calcination also includes the heat treatment of solids sometimes in the absence of air or oxygen or with a limited supply of air or oxygen. In addition, it includes the treatment of MgCO3 to produce MgO and the treatment of Ca(OH)2 to produce CaO.

[0042] As used herein, the term "cyclone" refers to a cyclone reactor in which a rotating gas flow is established inside the reactor known as the cyclone reactor. The gas including solid materials flows in a circulating mode and a spiral mode inside the cyclone reactor. Generally, the flow starts in the middle or at the top of the cyclone reactor and generally ends at the bottom of the cyclone reactor and exits therefrom.

[0043] As used herein, the term "heating" refers to the process of transferring energy to a material such that the temperature of the material increases.

[0044] As used herein, the term "sintering" refers to the process of forming a solid mass from solid material pieces by heating without melting the material to liquefy it. Atoms in the material diffuse across the boundaries of the particles, fusing the particles together and producing a solid piece. The sintering temperature generally does not reach the melting point of the material.

[0045] As used herein, the term "plasma" refers to the fundamental state of matter and is generally described as a gas composed of ions and free electrons.

[0046] In a first aspect, a reactor is provided, wherein the reactor is a cyclone reactor, and wherein the reactor comprises: an upper part having a first smaller diameter (D1) and a first height (L2); a middle part having a second diameter (D2); and a lower part having a third smaller diameter (D3) and a third height (L4), wherein the upper, middle, and lower directions are all with respect to the direction of gravity, wherein the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), and wherein the first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2), and the third height (L4) are selected such that:

[0047]

[0048] And wherein the reactor comprises at least one plasma torch, at least one inlet, and at least one outlet.

[0049] The cyclone reactor has a continuous feed of at least one gas and a continuous or intermittent feed of material in the form of particles to be treated. The interior of the cyclone reactor has a circular cross-section and generates a spiral eddy current similar to a tornado. In one embodiment, the gas inlet is designed to contribute to the generation of the spiral eddy current. The particles have a certain inertia and are affected by gravity and move downward to the opening.

[0050] Since the cyclone reactor is designed to have a spiral eddy current swirling inside, its cross-section is usually circular. The cross-section is taken in a plane perpendicular to the direction of gravity.

[0051] The upper part, middle part, and lower part of the reactor are defined in the direction of gravity, that is, the upward and downward directions are with respect to gravity. This is because the device is designed to work with gravity. The upper part, middle part, and lower part have different diameters, and the middle part has the largest diameter. This means that in one embodiment, the reactor walls are tapered so that they have a frustoconical shape. In addition, other forms such as ridged, stepped, or angled inner walls are also included.

[0052] The different parts of the reactor are as follows:

[0053] · The top of the reactor, the top of the reactor having a height L1. In one embodiment, the top of the reactor has a diameter D1, but the top can also have other shapes besides a cylindrical cross-section.

[0054] · The upper part, which has a height L2, also known as the first height L2. The upper part has a minimum diameter D1 and is connected to a middle part with a diameter D2. The minimum diameter D1 is also known as the first minimum diameter D1. The upper part is generally tapered and thus usually has many different diameters in different cross-sections. The term "smaller diameter" D1 refers to the minimum diameter of the upper part.

[0055] · The middle part, which has a height L3 and a diameter D3. If the middle part has a shape with several different diameters, the diameter D3 refers to the minimum diameter of the middle part.

[0056] · The lower part of the reactor, which has a smaller diameter D3 and is connected to the middle part with a diameter D2. The diameter D3 is also referred to as the third smaller diameter D3. The lower part has a height L4. The lower part is generally tapered and thus usually has many different diameters in different cross-sections. The term "smaller diameter" D3 refers to the minimum diameter of the lower part.

[0057] · The lowermost part, which has a height L5 and a diameter D3, and the opening has a diameter D4.

[0058] The swirl reactor includes at least one plasma torch. Finally, there is also at least one inlet for gases and materials in particulate form and at least one outlet for materials and gases.

[0059] Due to the larger diameter of the middle part, compared with a cylindrical reactor, the residence time of the particles in this section is prolonged and thus the time for the material to be exposed to thermal radiation is prolonged. The relative residence time of the particles at an appropriate distance from the plasma torch is also increased, minimizing the residence time in other parts where the heating of the particles in the reactor is not optimal.

[0060] Due to the larger diameter of the middle part, heat transfer by thermal radiation is facilitated because the particles in the middle part are dispersed at an appropriate distance from the plasma torch. When the particles are dispersed in the wider middle part, fewer particles will block the direct view of the plasma torch. This effect also facilitates heat transfer by thermal radiation.

[0061] The first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2) and the third height (L4) are selected such that the ratio of the upper half and the lower half of the reactor is within a certain range. When the tapered sections, i.e., the upper part and the lower part, are shaped as Figure 4When depicting the frustum cone, the angles α1 and α2 are defined and both independently lie within the range of 20° to 65°. The shapes of the upper and lower parts do not have to be frustum cones. For the general shape with diameters D1, D2, and D3 and heights L2 and L4, the above relationships define the ratios. Thus, the tapered part can have various shapes, such as a slightly concave or slightly convex shape. For a tapered part that is not a frustum cone shape, the angles αl and α2 may not be definable, but for such a shape, the diameters D1, D2, and D3 and the heights L2 and L4 define the ratios of these parts.

[0062] The relationship between the diameter and the height is important. For the lower part, it is important to obtain the correct balance among the forces including the frictional force against the inner wall of the reactor. In one embodiment, the angle α2 lies within the range of 20° to 65°. In an alternative embodiment, the angle α2 lies within the range of 30° to 60°. In one embodiment, the lower limit of the angle α2 is the same as the angle of repose of the particles. The angle of repose is measured according to ISO 4324:1977. The lower limit of α2 can be combined with any upper limit, such as 60° or 65°.

[0063] For the upper part, the design and the angle are important because it affects how the gas recirculates into and near the plasma torch. The design of the upper part affects the probability of the particles entering or getting too close to the plasma flame in the plasma torch. It is not desirable for the particles to enter the plasma flame because they may experience such high temperatures that they will melt or undergo unwanted side reactions. Therefore, a reactor design that minimizes the probability of the particles entering the plasma flame is desired. This is achieved by selecting D1, D2, and L2 such that they satisfy the above relationships. In one embodiment, the angle αl lies within the range of 20° to 65°. In an alternative embodiment, the angle αl lies within the range of 30° to 60°.

[0064] In one embodiment, the upper part includes the shape of a first frustum cone, and wherein the lower part includes the shape of a second frustum cone, and wherein the angles αl and α2 are the angles formed by the tapered parts of the first frustum cone and the second frustum cone respectively with respect to the line parallel to the central axis of the reactor, and wherein both αl and α2 lie within the range of 20° to 65°, where:

[0065]

[0066] In one embodiment, the plasma torch is located in the upper part. With this design, the thermal radiation from the plasma torch can heat the material swirling in the eddy current in the reactor. During the extended residence time in the middle part, the material will be exposed to the thermal radiation from the plasma torch in the upper part of the reactor.

[0067] In one embodiment, the reactor is equipped with at least one inlet in the middle part. Due to the inlet located in the middle part, the material will have a proper position inside the reactor when it has entered. Due to the tangential inlet in the middle part, the material will not only have a proper position in the reactor, but will also form the necessary swirl. The tangential inlet will form a swirl. The reactor is designed such that the residence time of the material in the middle is extended, and at this position, the material is highly heated by thermal radiation.

[0068] In one embodiment, the reactor is equipped with at least one inlet in the upper half of the reactor. In this embodiment, gravity will ensure that the particles move to a proper position for heat treatment and then leave the reactor.

[0069] In one embodiment, at least one inlet is tangentially guided in the circular cross-section of the reactor. This will help generate an eddy current inside the reactor.

[0070] In one embodiment, the second diameter (D2) is larger than the sum of the first smaller diameter (D1) and the third smaller diameter (D3).

[0071] In one embodiment, the second diameter (D2) is at least 2 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.5 times larger than the third smaller diameter (D3).

[0072] In one embodiment, the angle formed by the second diameter (D2) and the length L2 with respect to the line in the direction of gravity is at least 20°.

[0073] In one embodiment, the angle formed by the second diameter (D2) and the length L4 with respect to the line in the direction of gravity is at least 20°.

[0074] In one embodiment, at least one plasma torch is adapted to at least one volume part (V) inside the reactor h)Heat to a temperature of at least 3000 °C. The volume heated around the plasma torch is the volume part Vh. Commercially available plasma torches that can reach a sufficiently high temperature can be used. Many plasma torches can reach very high temperatures, such as at least 15000 °C, at least 20000 °C or at least 25000 °C or even higher, at least in a certain volume, that is, inside the plasma. However, for this application, the temperature at which the plasma flame enters the swirl reactor is crucial. The high temperature of the plasma torch is suitable for providing high energy transfer from the plasma torch to the material in the reactor through thermal radiation.

[0075] In one embodiment, the reactor is equipped with at least one outlet in the lower half of the reactor. Gravity will cause the material to be transported downward, and therefore it is advantageous to have an outlet in the lower half of the reactor. In one embodiment, the outlet is located at the bottom of the reactor.

[0076] In one embodiment, at least one inlet for the suspension gas is located in the lower part of the reactor. The suspension gas will help to lift the material upward, increasing the time the material spends in the middle of the reactor. The suspension gas flow will extend the time the particles are exposed to the effective thermal radiation from the plasma torch.

[0077] In one embodiment, at least one inlet for the suspension gas is located in the lower part of the reactor, and wherein at least one inlet for the suspension gas is directed upward relative to the direction of gravity. The suspension gas helps to lift the particles, especially when the flow is directed upward.

[0078] In one embodiment, at least one inlet for the suspension gas is located in the lower part of the reactor, and wherein, when viewed in cross-section along the reactor, at least one inlet for the suspension gas is directed towards the center of the reactor, where the cross-section is perpendicular to the direction of gravity.

[0079] In one embodiment, the height of the reactor has a certain relationship with the second diameter D2. In Figure 1 it, the height of the reactor is L1 + L2 + L3 + L4 + L5. In one embodiment, the height (L1 + L2 + L3 + L4 + L5) of the reactor is in the range D2 ≤ (L1 + L2 + L3 + L4 + L5) ≤ 20 * D2.

[0080] In one embodiment, the reactor is a calcination reactor. In the calcination reactor, solid materials are heated, thereby raising the temperature of the materials to a high temperature without melting the materials.

[0081] In one embodiment, a cooling cyclone is connected in series after at least one outlet of the reactor. Such a system will cause the temperature of the material to drop more quickly, which may be an advantage for some materials, and it can also help to utilize at least some of the heat discharged from the swirl reactor.

[0082] In one embodiment, the volume part (Vh) - the volume heated by the plasma torch - is centered in the swirl reactor. Since the swirl reactor has a circular cross-section in a plane perpendicular to the direction of gravity, being centered means being at the center of such a circle. In one embodiment, the volume part (Vh) is located in the center of the eddy current of the cyclone, which is intended to form during reactor operation. During operation, for a typical cyclone with a circular cross-section, the center of the eddy current is the same as the center of the cyclone.

[0083] In one embodiment, the material to be treated in the calciner is CaCO3. In another embodiment, the material is MgCO3. In another embodiment, the material is CaMg(CO3)2. In yet another embodiment, the material is Ca(OH)2. Alternatively, the material to be treated in the calciner is a mixture including at least one of CaCO3 and MgCO3. CaCO3 is usually in the form of calcite with a relatively low melting temperature (1339 °C). However, CaCO3 will decompose into CaO at a temperature lower than the melting temperature under normal pressure.

[0084] CaO has a much higher melting temperature (2613 °C). However, due to the phase changes of CaO and impurities, the structure of the particles will change at elevated temperatures. CaO can also react with various impurities in the raw materials. When the temperature is too high, this phenomenon is considered "dead burning". Therefore, unless these phase changes are required, generally too high temperatures should be avoided. If the particles enter the plasma flame in the reactor, too high temperatures may occur. This is not desirable, and the particles should instead vortex around at a suitable distance from the plasma flame.

[0085] In addition, the material to be treated in the reactor can be heated to a certain temperature to initiate melting, sintering, or other heat-induced reactions and / or phase changes.

[0086] The material to be heat-treated is provided in the form of particles. The particulate form ensures that the material can vortex in the swirl reactor. If the heat transfer into the particles and the diffusion resistance of CO2 leaving the particles are far less important than the rate of the calcination reaction, the overall reaction is considered to be kinetically controlled. The particles should not be too large and should be small enough to kinetically control the reaction rate. Additionally, for smaller particles, heat transfer by radiation is faster and more efficient. Further, in the case of large particle sizes or large material aggregates and agglomerates, sufficient particle transport and residence time in the swirl reactor become difficult. A particle size in the range of 10 μm to 1000 μm is suitable, although 5 μm to 2000 μm is also possible. If the particles are too large, it is difficult to establish and maintain the desired particle vortex flow in the reactor. Thus, in one embodiment, the average particle size is below 2000 μm, and in another embodiment, the average particle size is below 1000 μm. The average particle size is determined as follows. The particle size distribution is measured by laser diffraction according to ISO 13320:2020. Then, the average particle size is calculated from the measured particle size distribution using the moment method as described in ISO 9276-2:2014. Thus, in one embodiment, the material to be heat-treated is provided as particles having an average size in the range of 10 μm to 1000 μm, wherein the average particle size is calculated using the moment method from the particle size distribution measured according to ISO 13320:2020 in accordance with ISO 9276-2:2014. In one embodiment, the material to be heat-treated is provided as particles having an average size in the range of 5 μm to 2000 μm, wherein the average particle size is calculated using the moment method from the particle size distribution measured according to ISO 13320:2020 in accordance with ISO 9276-2:2014.

[0087] When the particles enter the reactor, they are typically carried in a gas stream. In one embodiment, the gas is a gas mixture. In one embodiment, the gas mixture includes CO2. In one embodiment, the gas mixture includes air. In one embodiment, the gas is superheated steam. In one embodiment, an inert gas is added in the swirl reactor. In one embodiment, the swirl reactor includes nitrogen.

[0088] In one embodiment, the plasma includes at least one selected from the group consisting of carbon dioxide, air, superheated steam, argon, and nitrogen.

[0089] The residence time of the particles in the cyclone reactor is typically in the range of 0.2 seconds to 60 seconds, depending on the desired particle temperature, particle size, particle density, and other factors. The residence time of the gas is much shorter. The typical temperature for the particles in the cyclone reactor is in the range of 500 °C to 1450 °C. That is, the particles reach this temperature after heating. In one embodiment, a particle temperature of about 1000 °C is used. In the reactor, in the volume V with a high temperature h The short residence time near the plasma torch with a high temperature enables heating to a suitable temperature mainly by radiative heat transfer from the plasma torch with a high temperature. The residence time in the cyclone reactor is adjusted so that the particles are heated to a temperature suitable for the calcination reaction to occur. The residence time and temperature of the particles leaving the calcination furnace are such that the heat-treated material does not chemically recombine with the gas, at least not to any extent that negatively affects the process. In the prior art, there may be a problem of recombination of the new heat-treated material with the released gas. This problem is minimized by maintaining a sufficiently high temperature until the reaction products - namely, the heat-treated material and the released gas - are separated from each other. In addition, a short processing time that allows for rapid separation of the released gas after the calcination reaction will reduce the problem of recombination.

[0090] In one embodiment, the particles are preheated before they are fed into the cyclone reactor.

[0091] The volume V with a high temperature in the cyclone reactor is heated by a plasma torch h In one embodiment, the plasma torch includes an internal electrode, an output electrode, and an insulator located between the electrodes, and the working gas enters the plasma torch through the insulator. An arc is ignited between the two electrodes. Some of the working gas in the working gas penetrates the arc column, while the remaining gas flows between the arc and the wall. The working gas flow that penetrates the arc column reaches the temperature of the arc through Joule heating. Joule heating, also known as Ohmic or resistive heating, is described as generating heat when an electric current passes through a resistor. The gas is ionized and becomes conductive. The remaining gas in the working gas is not heated much because there is no convective heat transfer with the arc due to the "blocking" of heat exchange by the thermal boundary layer. The place where the wall and the thermal boundary layer are combined is called the diversion zone, where the arc and the main gas flow begin to interact, resulting in a strong mixing of hot and cold gas flows. This results in a plasma flow having a high-temperature core and a temperature distribution that rapidly decreases in the radial direction at the exit of the plasma torch. Generally, less than half of the flow participates in the arc discharge and reaches the plasma state, but this is sufficient to generate and maintain the heating element. The remaining part of the gas is heated by the plasma via all three heat transfer mechanisms (conduction, convection, and radiation). In one embodiment, water cooling of the output electrode is used to minimize the evaporation rate of the electrode material due to the very high temperature.

[0092] The plasma temperature is maintained at a temperature of 3000 °C or higher. This temperature is the peak temperature measured at the outlet of the plasma torch entering the reactor. As the flame expands, the temperature in the flame will gradually decrease because cooler gases are mixed into the flame.

[0093] The temperature inside the plasma torch is higher compared to the temperature at the outlet of the plasma torch. Inside the plasma, the temperature can be quite high, but the relevant temperature is the temperature at the outlet of the plasma torch, which is the temperature when the flame enters the swirl reactor.

[0094] In one embodiment, the working gas temperature at the plasma torch inlet is restricted to 20 °C to 150 °C, but it can also be a higher temperature.

[0095] In embodiments where there is CO2 in the plasma torch, a hot gas with a high energy density is generated by the CO2 - plasma torch. In a torch at 3000 °C to 3500 °C, the energy density in this CO2 - plasma torch is about 4 MJ / kg to 7.5 MJ / kg (with partially dissociated CO2). In one embodiment, the plasma torch is introduced vertically at the top of the calciner, and as seen from the top of the calciner, the plasma torch is oriented towards the center of the swirl calciner.

[0096] In one embodiment, the material to be heat - treated is pneumatically conveyed and tangentially introduced to the periphery of the plasma calciner. This helps to generate a vortex inside the swirl reactor. In one embodiment, the material to be heat - treated is fed together with additional CO2. In one embodiment, the CO2 stream is pre - heated. In one embodiment, the material to be heat - treated is pre - heated. In one embodiment, the material to be heat - treated is pre - heated to a temperature within the range of 750 °C to 1500 °C. In another embodiment, the material to be heat - treated is pre - heated to a temperature within the range of 450 °C to 1200 °C. In yet another embodiment, the material to be heat - treated is pre - heated to a temperature within the range of 450 °C to 1500 °C.

[0097] When the material to be heat - treated in particulate form enters the swirl calciner, heat is rapidly transferred to the particles. The heat is transferred partially by thermal radiation, but also by mixing and convection. Compared with the prior art, the portion of heat transferred by thermal radiation increases. This results in effective and rapid calcination and the release of additional CO2.

[0098] This reaction is strongly endothermic and causes the average temperature of the particles to rapidly decrease as the material flows through the calciner. This lower average temperature of the particles also reduces the exposure of the calciner walls to very high temperatures, thus allowing the use of cost-effective construction materials in the design of the swirl reactor. In one embodiment, at the outlet where both the gas and the particles are well mixed, the average temperature is about 900 °C to 1300 °C. In another embodiment, the average temperature at the outlet is even lower.

[0099] The particles in the swirl reactor can be regarded as a particle film in the gas stream, and these particles absorb heat from the plasma torch and allow the use of cheaper materials with slightly lower tolerance to high temperatures.

[0100] In one embodiment, the reactor is equipped with at least one outlet in the lower half of the reactor, and the reactor is adapted such that the average temperature of the mixture of gas and particles at the outlet does not exceed 1300 °C. In one embodiment, the outlet is located at the bottom of the reactor. In one embodiment of the heat treatment method, the material is allowed to cool to a temperature not exceeding 1000 °C at the outlet of the reactor. The flow of the particles is designed such that most of the residence time is in the middle and lower parts of the swirl reactor. In the lower part of the reactor, the heating is less intense because the lower part is at a greater distance from at least one volume (V h ), such that the material is not heated to such a great extent. Due to the longer residence time in the lower part of the reactor, the temperature at the outlet of the reactor decreases, and this has been found to have a positive effect on calcination.

[0101] In one embodiment, at least one volume (V h ) is located in the uppermost part of the reactor, where the uppermost part is with respect to the direction of gravity. In a typical embodiment, the material to be heat-treated enters the reactor from the top or at least from the uppermost part. The material then follows the vortex formed inside the swirl reactor. When the material is in the uppermost part, the material will approach at least one volume (V h ), where the temperature is high at the at least one volume (V h ) and the material will be effectively exposed to thermal radiation. The temperature is so high, and due to the selection of the swirl reactor, the material to be heat-treated will be close to the volume (V h ) in a short time sufficient for calcination, thus ensuring effective calcination. The particles to be heat-treated are close to the volume V hFor a period of time to reach a temperature suitable for the calcination reaction to occur. The material to be heat-treated will flow in from one or several inlets along the periphery of the cyclone. The flow of particles in the gas stream will form a spiral and / or circular gas film in the cyclone. The spiral and / or circular flow will allow better control of the process. In one embodiment, the cyclone reactor includes means for guiding the flow of gas and particles. Examples of such means include, but are not limited to, flanges and vanes inside the cyclone reactor.

[0102] In one embodiment, when viewed from above, the volume portion (V h ) is centered in the cyclone reactor, and as observed from above, the vortex formed in the cyclone reactor is also centered in the cyclone reactor.

[0103] All directions, such as upward, downward, side, top, bottom, etc., are relative to the expected position of the calciner during operation and relative to gravity, such that downward has the same direction as the direction of gravity.

[0104] In one embodiment, at least one volume portion (V h ) inside the reactor is adapted to be heated to a temperature of at least 3000 °C by a plasma torch. In another embodiment, at least one volume portion (V h ) inside the reactor is adapted to be heated to a temperature of at least 3500 °C by a plasma torch.

[0105] It should be noted that the high temperature of at least 3000 °C only applies to at least one volume portion (V h ) inside the reactor, and this does not mean that all the materials inside the reactor are heated to this temperature. Generally, the residence time of the material to be heat-treated inside the reactor is too short to reach the high temperature of 3000 °C, but reaches a temperature sufficient for effective calcination without overheating the particles. In fact, the endothermic calcination reaction that reduces the temperature of the surrounding environment reduces the risk of overheating.

[0106] In one embodiment, at least one volume portion (V h ) inside the reactor is heated to a temperature of at least 3250 °C by a plasma torch. In one embodiment, at least one volume portion (V h ) inside the reactor is heated to a temperature in the range of 3000 °C to 4000 °C by a plasma torch. In another embodiment, at least one volume portion (V h ) inside the reactor is heated to a temperature in the range of 3500 °C to 4500 °C by a plasma torch.

[0107] When designing a reactor, it should be taken into account that usually due to the release of gases during calcination, the volume of the vessel usually increases. For the two examples of calcining limestone (CaCO3) to produce calcium oxide (CaO) and calcining MgCO3 to produce MgO, CO2 is released. The design of the reactor and the surrounding equipment should take into account the volume expansion. The design of a reactor with a swirler near and / or around the plasma torch can rapidly heat the material to be heat-treated, thereby enabling the reaction to proceed rapidly and causing the volume to expand rapidly. The designer of the swirl reactor should take this volume expansion into account by selecting a sufficiently wide diameter of the swirl reactor.

[0108] In one embodiment, the reactor is a calcination reactor. This reactor can be used for heat-treating many different materials. The heat treatment can be for the purpose of, for example, calcining, sintering, or heating the material.

[0109] In a second aspect, a heat treatment method is provided, in which a material is heat-treated in a reactor, where the reactor is a swirl reactor, and where the reactor comprises: an upper part having a first smaller diameter (D1); a middle part having a second diameter (D2); and a lower part having a third smaller diameter (D3), where the directions of the upper, middle, and lower parts are all relative to the direction of gravity, where the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and where the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), where the material is transported in a swirling gas flow, and where the material is heated at least by thermal radiation using at least a plasma torch.

[0110] The above swirl reactor is used to carry out this method.

[0111] In one embodiment, the swirling gas flow is formed due to the orientation of at least one inlet in the reactor. The inlet can be tangentially positioned, for example, and fairly close to the outer wall of the swirl reactor to form a vortex inside the swirl reactor. Other positions of the inlet are also possible.

[0112] In one embodiment, the plasma torch heats at least one volume portion (Vh) in the reactor to at least 3000 °C.

[0113] In one embodiment, the material comprises at least one selected from the group consisting of CaCO3, MgCO3, and CaMg(CO3)2. In one embodiment, the material comprises Ca(OH)2. In one embodiment, the material to be heat-treated comprises CaCO3. In another embodiment, the material to be heat-treated comprises MgCO3. In another embodiment, the material to be heat-treated comprises Ca(OH)2. In other embodiments, the material to be heat-treated comprises at least one of CaCO3, MgCO3, Ca(OH)2, metal oxides, lithium metal oxides, dolomite, kaolinite, clay minerals, clay, minerals, spodumene, iron, nickel, zeolites, cementitious materials, cement raw materials, cement, sand, gravel, silicon carbide, silicon-based materials, or mixtures thereof.

[0114] In one embodiment, the plasma comprises carbon dioxide. Using carbon dioxide in a plasma torch has advantages. The CO2 in the plasma torch decomposes into CO, O2, and O at a high temperature such as 2000 °C. When the temperature drops, the atoms and molecules recombine. This produces a high-energy gas flow in the range of 4 MJ / kg to 14 MJ / kg.

[0115] In one embodiment, the plasma in the plasma torch comprises at least one selected from the group consisting of carbon dioxide, air, superheated steam, argon, and nitrogen.

[0116] In one embodiment, the material is provided as particles having an average particle size in the range from 5 μm to 2000 μm, preferably in the range from 10 μm to 1000 μm, wherein the average particle size is calculated starting from the particle size distribution measured according to ISO 13320:2020 using the moment method according to ISO 9276-2:2014.

[0117] In one embodiment, the material is provided in the form of particles comprising a core, the core comprising the material, the core being coated with an outer layer comprising smaller particles (P 小 )), wherein the smaller particles (P 小 ) have an average particle size in the range from 1 μm to 500 μm, wherein the average particle size is calculated starting from the particle size distribution measured according to ISO 13320:2020 using the moment method according to ISO 9276-2:2014. These coated particles have the advantage of reducing friction when they are processed. The heat transfer to the core can be adjusted by selecting a coating material with good thermal conductivity, such as graphene, or a material with low thermal conductivity, such as SiO2.

[0118] In one embodiment, the smaller particles (P 小)comprising at least one material selected from the group consisting of SiO2, SiO2 modified with at least one hydrophobic compound, graphite, graphite oxide, graphene oxide, and graphene.

[0119] In one embodiment, the material is fed from an inlet into a swirling gas stream and is conveyed in the reactor in a downward direction to a point where the swirling flow turns upward before turning downward again towards the outlet. Since the material moves downward first, then turns upward, and then turns downward again, this embodiment enables the material to be at an appropriate distance from the plasma torch for a longer period of time. This embodiment further increases the residence time at an appropriate distance from the plasma torch to maximize heat transfer by radiation.

[0120] In one embodiment, a suspension gas is added in the lower part of the reactor to control the residence time of the particles.

[0121] In one embodiment, the material is allowed to cool at the outlet of the reactor to a temperature not exceeding 1400 °C. In one embodiment, the material is allowed to cool at the outlet of the reactor to a temperature not exceeding 1200 °C.

[0122] In one embodiment, the material is allowed to cool at the outlet of the reactor to a temperature not exceeding 1000 °C. In one embodiment, the material is allowed to cool at the outlet of the reactor to a temperature not exceeding 800 °C.

[0123] In one embodiment, water, preferably in the gaseous phase, is added to the reactor. Additionally, water can improve the emissivity of various plasma gases, such as nitrogen, which has a lower emissivity compared to many other gases, and thus improve the heat transfer efficiency. Therefore, the plasma torch radiates heat more effectively by adding water.

[0124] In one embodiment, the heat treatment is at least one selected from calcination, sintering, and heating.

[0125] In one embodiment, the material is cooled directly by a cooling gas in a cooling cyclone after leaving the reactor. This has the advantage that heat can be recovered from the process. Additionally, rapid cooling is sometimes beneficial for the material being processed. In one embodiment, the particles are rapidly cooled by a cooling gas in a separate mixing chamber after the cyclone reactor.

[0126] All embodiments disclosed herein can be freely combined with each other as long as these embodiments are not clearly contradictory.

[0127] Each example

[0128] Example 1

[0129] Calcination tests were carried out in a plasma swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a net power of 200 kW was vertically installed in the center of the upper section of the reactor. The temperature in the plasma generator was at least 3000 °C. The plasma included CO2. CaCO3 with an average diameter of 200 μm was tangentially fed into the plasma swirl reactor. The calcination degree of the material was measured for different material outlet temperatures as follows:

[0130] Reactor outlet temperature Calcination degree 1000℃ 82.1％ 1050℃ 86.7％ 1100℃ 96.2％

[0131] Example 2

[0132] Tests were carried out in a plasma swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a total power of 350 kW was vertically installed in the center of the reactor. Cement raw materials including silica, iron oxide and CaCO3 with an average diameter of 8 μm were tangentially fed into the plasma swirl reactor. The temperature and yield of the material were measured as follows:

[0133] Reactor outlet temperature Output of the material 1126℃ 165 kg / h 1212℃ 50 kg / h

[0134] Example 3

[0135] Tests were carried out in a plasma swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a net power of 250 kW was vertically installed in the center of the reactor. Particles including magnesium silicate with an average diameter of 310 μm were tangentially fed into the plasma swirl reactor. The temperature and yield of the material were measured as follows:

[0136] Reactor outlet temperature Output of the material 1040℃ 113 kg / h 1068℃ 159 kg / h

[0137] Example 4

[0138] Calcination tests were carried out in a swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a net power of 265 kW (total power of 330 kW) was vertically installed in the center of the upper section of the reactor. The temperature in the plasma generator was at least 3000 °C. The energy density of the plasma flame was about 6.2 MJ 总 / kg. In a pure CO2 atmosphere, limestone particles with a median diameter of 156 μm were tangentially fed into the plasma swirl reactor.

[0139] Tests were carried out under different test conditions. The calcination degree was plotted in the following figure as a function of the peripheral temperature measured in the plasma swirl reactor. At temperatures above about 940 °C, the calcination degree was found to be about 97.5%. Please refer to Figure 1 .

[0140] Example 5

[0141] Calcination tests were carried out in a swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a net power of 275 kW (total power of 340 kW) was vertically installed in the center of the upper section of the reactor. The temperature in the plasma generator was at least 3000 °C. The energy density of the plasma flame was approximately 6.3 MJ 总 / kg. Limestone particles with a median diameter of 198 μm were tangentially fed into the plasma swirl reactor in a pure CO2 atmosphere.

[0142] Tests were carried out under different test conditions. The calcination level was plotted in the following figure as a function of the peripheral temperature measured in the plasma swirl reactor. The calcination level increased gradually over the entire temperature range. Please refer to Figure 2 .

[0143] Example 6

[0144] Calcination tests were carried out in a swirl reactor with a diameter of 1.25 m and a height of 1.45 m. A plasma generator with a net power of 275 kW (total power of 340 kW) was vertically installed in the center of the upper section of the reactor. The temperature in the plasma generator was at least 3000 °C. The energy density of the plasma flame was approximately 6.3 MJ total / kg. Cement raw materials including silica, iron oxide and CaCO3 with an average diameter of 8 μm were tangentially fed into the plasma swirl reactor in a pure CO2 atmosphere. Tests were carried out under different test conditions. The calcination level was plotted in the following figure as a function of the temperature measured downstream of the plasma swirl reactor. As the temperature increased, the calcination level increased gradually. Please refer to Figure 3 .

Claims

1. A reactor, wherein, The reactor is a cyclone reactor, wherein the reactor comprises: an upper part having a first smaller diameter (D1) and a first height (L2); a middle part having a second diameter (D2); and a lower part having a third smaller diameter (D3) and a third height (L4), wherein the upper, middle and lower directions are all with respect to the direction of gravity, wherein the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), wherein the first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2) and the third height (L4) are selected such that: And wherein the reactor comprises at least one plasma torch, at least one inlet and at least one outlet.

2. The reactor according to claim 1, wherein, The upper part has the shape of a first frustum of a cone, and wherein the lower part has the shape of a second frustum of a cone, and wherein the angles αl and α2 are the angles formed by the tapered portions of the first frustum of a cone and the second frustum of a cone respectively with a line parallel to the central axis of the reactor, and wherein both αl and α2 are in the range of 20° to 65°, wherein:

3. The reactor according to any one of claims 1 to 2, wherein, The plasma torch is located in the upper part.

4. The reactor according to any one of claims 1 to 3, wherein, The reactor is equipped with at least one inlet in the middle part, wherein the at least one inlet is guided tangentially to the circular cross-section of the reactor.

5. The reactor according to any one of claims 1 to 4, wherein, The reactor is equipped with at least one inlet in the upper half of the reactor, wherein the at least one inlet is guided tangentially to the circular cross-section of the reactor.

6. The reactor according to any one of claims 1 to 5, wherein, The second diameter (D2) is larger than the sum of the first smaller diameter (D1) and the third smaller diameter (D3).

7. The reactor according to any one of claims 1 to 6, wherein, The second diameter (D2) is at least 2 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.5 times larger than the third smaller diameter (D3).

8. The reactor according to any one of claims 1 to 7, wherein, The at least one plasma torch is adapted to heat at least one volume portion (V h ) inside the reactor to a temperature of at least 3000 °C.

9. The reactor according to any one of claims 1 to 8, wherein, The reactor is equipped with at least one outlet in the lower half of the reactor.

10. The reactor according to any one of claims 1 to 9, wherein, At least one inlet for the suspension gas is located in the lower part of the reactor.

11. The reactor according to any one of claims 1 to 10, wherein, At least one inlet for the suspension gas is located in the lower part of the reactor, and wherein the at least one inlet for the suspension gas is guided upward with respect to the direction of gravity.

12. The reactor according to any one of claims 1 to 11, wherein, At least one inlet for the suspension gas is located in the lower part of the reactor, and wherein, when observed along the cross-section of the reactor, the at least one inlet for the suspension gas is guided towards the center of the reactor, wherein the cross-section is perpendicular to the direction of gravity.

13. The reactor according to any one of claims 1 to 12, wherein, The height (L1 + L2 + L3 + L4 + L5) of the reactor is in the range D2 ≤ (L1 + L2 + L3 + L4 + L5) ≤ 20 * D2.

14. The reactor according to any one of claims 1 to 13, wherein, The reactor is a calcination reactor.

15. The reactor according to any one of claims 1 to 14, wherein, A cooling cyclone is connected in series after at least one outlet of the reactor.

16. A heat treatment method, wherein, Heat-treating a material in a cyclone reactor, wherein the reactor comprises: an upper part having a first smaller diameter (D1) and a first height (L2); a middle part having a second diameter (D2); and a lower part having a third smaller diameter (D3) and a third height (L4), wherein the upper, middle, and lower directions are all relative to the direction of gravity, wherein the second diameter (D2) is at least 1.25 times larger than the first smaller diameter (D1), and wherein the second diameter (D2) is at least 1.25 times larger than the third smaller diameter (D3), wherein the first smaller diameter (D1), the second diameter (D2), the third smaller diameter (D3), the first height (L2), and the third height (L4) are selected such that: And wherein the reactor comprises at least one plasma torch, at least one inlet, and at least one outlet, wherein the material is conveyed in a swirling gas flow, and wherein the material is heated by at least one plasma torch at least by thermal radiation.

17. The heat treatment method according to claim 16, wherein The swirling gas flow is formed due to the orientation of the at least one inlet in the reactor.

18. The heat treatment method according to any one of claims 16 to 17, wherein, The plasma torch heats at least one volume portion (Vh) in the reactor to at least 3000 °C.

19. The heat treatment method according to any one of claims 16 to 18, wherein, The material comprises at least one selected from the group consisting of CaCO3, MgCO3, and CaMg(CO3)2.

20. The heat treatment method according to any one of claims 16 to 19, wherein The material comprises Ca(OH)2.

21. The heat treatment method according to any one of claims 16 to 20, wherein, The plasma in the plasma torch comprises at least one selected from the group consisting of carbon dioxide, air, superheated steam, nitrogen, and argon.

22. The heat treatment method according to any one of claims 16 to 21, wherein, The material is provided as particles having an average particle size in the range from 5 μm to 2000 μm, preferably in the range from 10 μm to 1000 μm, wherein the average particle size is calculated starting from the particle size distribution measured according to ISO 13320:2020 using the notation according to ISO 9276-2:2014.

23. The heat treatment method according to any one of claims 16 to 22, wherein, The material is provided in the form of particles comprising a core, said core comprising the material, the core being coated with an outer layer comprising smaller particles (P 小 ), wherein said smaller particles (P 小 ) have an average particle size in the range of 1 μm to 500 μm, wherein the average particle size is calculated starting from the particle size distribution measured according to ISO 13320:2020 using the distance notation according to ISO 9276-2:2014.

24. The heat treatment method according to claim 23, wherein, The smaller particles (P 小 ) include at least one material selected from the group consisting of SiO2, SiO2 modified with at least one hydrophobic compound, graphite, graphite oxide, graphene oxide, and graphene.

25. The heat treatment method according to any one of claims 16 to 24, wherein, The material is conveyed from the inlet into the swirling gas flow and is conveyed in the reactor in a downward direction to a point where the swirling flow turns upward before turning downward again towards the outlet.

26. The heat treatment method according to any one of claims 16 to 25, wherein, A suspension gas is added in the lower part of the reactor.

27. The heat treatment method according to any one of claims 16 to 26, wherein, The material is allowed to cool at the outlet of the reactor to a temperature not exceeding 1400 °C.

28. The heat treatment method according to any one of claims 16 to 27, wherein, Water, preferably in gaseous phase, is added in the reactor.

29. The heat treatment method according to any one of claims 16 to 28, wherein, The heat treatment is at least one selected from calcination, sintering, and heating.

30. The heat treatment method according to any one of claims 16 to 29, wherein, The material is cooled directly in a cooling cyclone after leaving the reactor.

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