Process and method for firing material

Abstract

To provide a direct separation reactor for treating a material for formation of a particle including CaO, especially a CaO particle, in the presence of CO2.SOLUTION: A direct separation reactor includes: a powder injector having a powder inlet that extends to an upper part of a vertical reactor pipe, the powder inlet supplying powder to a first vertical reactor pipe; a lower part of the vertical reactor pipe including an external heating wall for firing a powder feed material having been fallen and injected; a gas injector for injection of a gas flow to the powder feed material having been fallen and injected in the flow; and an exhaust manifold disposed in the vertical reactor pipe. The exhaust manifold includes an exhaust outlet in an upper part of the vertical reactor pipe and an exhaust inlet in the vertical reactor pipe, and the exhaust inlet enables the gas flow to change to a backward flow with respect to the fired powder having been fallen before the gas flow exits from the exhaust outlet.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] Broadly speaking, the present invention relates to means for firing materials in a continuous process, and the firing described herein is a reaction and / or phase change induced by heating the material, or both.

[0002] Numerous processes have been developed for firing materials, and they have been developed for treating specific materials with specific fuels. The disclosure of the present invention relates to a means of flash firing, known as flash sintering, which provides energy for the reaction of powder materials using indirect heating.

Background Art

[0003] Most of the prior art for firing uses direct heating of the material by combustion gases, while indirect heating generally transfers heat from the reactor wall by radiative heat transfer through steel pipes from an external combustor. Indirect heating processes generally have three applications, namely, (a) producing a fired material with higher reactivity than direct heating because internal sintering is reduced by short residence times and temperature control within the reactor, and / or (b) separating the combustion process from the reaction process so that the fired product is not contaminated by combustion impurities, and / or (c) separating gases from the combustion and reaction processes so that the reaction can be controlled, for example, by controlling the oxidation state, and / or (d) treating carbonate materials that release CO 2 during the firing reaction to produce oxides (thereby enabling the process CO 2 gas to be captured as a pure gas stream).

[0004] CO 2 Regarding the capture of CO 2 there are two sources of emissions from such firing processes. The first source is CO 2 released from the combustion of carbon-based fuels, which is referred to herein as "combustion CO 2」. The low-emission firing process aims to reduce both combustion CO 2 and process CO 2 . In life cycle analysis, using renewable power, i.e., power with a low emissions intensity, is a means to reduce CO 2 emissions on the fuel side. Global efforts to reduce emissions are expected to be judged by the emissions intensity, which is the number of tons of CO 2 emissions per ton of product that includes both combustion CO 2 and process CO 2 . It is necessary to reduce the emissions intensity of the products manufactured in the firing process.

[0005] Combustion CO 2 emissions can be reduced by many established methods. One way to reduce combustion emissions is to indirectly heat the firing furnace using "renewable power" generated from wind power, sunlight, or other processes. The cost of generating renewable power is rapidly decreasing and may become an affordable price as a commodity product. Other methods use low-emission gas combustion processes. One method is to use non-carbon-based fuels such as hydrogen, e.g., fuels derived from "electrolysis" of water or fuels derived from either the use of carbon-based fuels processed by "pre-combustion" capture to remove CO 2 . Another method is to use adsorbents such as amines, bicarbonates, metal oxides, hydrotalcite, etc. to treat flue gas from the combustion of carbon-based fuels in a process called "post-combustion" capture to remove CO 2 . Another method is to use CO 2In a process called "oxy-fuel combustion" for producing flue gas with a high proportion of [specific component], oxygen is used instead of air for the combustion of carbon-based fuels. It will be apparent to those skilled in the art that combustion emissions can be reduced by using renewable electricity, or electrolysis, or pre-combustion capture, or post-combustion capture, or oxy-fuel combustion, or combinations thereof. In most firing processes that use combustion gases, high-temperature flue gas is used to transfer energy directly to the material by direct heating. Therefore, process emissions are mixed with the flue gas, and the process CO 2 extraction increases the cost and complexity for reducing process emissions. On the other hand, indirect heating not only captures process CO 2 as a pure gas vapor, but also provides flexibility in reducing emissions because any of the above low-emission methods can be used to supply heat.

[0006] Materials that generate process emissions during firing are carbonate materials such as limestone CaCO 3 , dolomite MgCO 3 ·CaCO 3 , magnesite MgCO 3 , etc., and mixtures of minerals such as those required for raw cement powder for Portland cement production. Here, carbonate minerals include impure limestone such as marl and other mixed metal carbonates (including siderite FeCO 3 ), and synthetic carbonate compounds produced for the manufacture of certain oxide materials (for example, manganese carbonate MnCO 3 included as an intermediate in the manufacture of metals and battery materials), and organic materials that decompose to produce CO 2 . For various industrial purposes, there is a wide range of materials processed by firing, and these generate process CO 2 .

[0007] To mitigate climate change, to reduce emissions from the firing of materials, process CO 2 emissions and combustion CO 2Either or, preferably, both emissions need to be captured. For example, the cement industry has many ways and many CO 2 CO from limestone calcination through capture methods 2 The former methods include using biomass, waste, and renewable electricity as fuels, while the latter methods include the processes described herein as amine capture, oxyfuel combustion, calcium looping, and direct separation. The most desirable solution for reducing emissions is CO 2 Lowest cost of capture (avoided CO 2 Many of the proposed capture processes, such as the amine and oxyfuel processes, require novel chemical and physical processes, which means that CO 2 The cost of capture is significant. With calcium looping, the high mass flow rates and energy recovery are barriers to use. A common theme with each of these processes is the increased complexity and cost of their implementation. An alternative approach, direct separation, as described by Sceats et al. in WO 2015 / 077818 "Process and Apparatus for Manufacture of Portland Cement" and references therein, can be used to reduce process CO emissions without additional energy penalties or the use of new materials. 2 This approach uses indirect heating of the calciner, so that the process gas stream from the processing of carbonate minerals contains small amounts of process CO2 impurities due to volatilization of trace elements. 2 The general approach to calcining carbonate materials using indirect heating is described in WO 2016 / 077863, "Process and Apparatus for Manufacture of Calcined Compounds for Production of Calcined Products," by Sceats et al., and references therein, where the indirect heating process is extended to the use of multiple reactor segments containing different material and power segments.

[0008] The inventions related to direct separation reactors described in International Publication No. WO 2015 / 077818, International Publication No. WO 2016 / 077863, and the references therein are indirect heating flash firing processes, and it should be noted that the time scale of this firing process is generally in the range of 10 to 50 seconds. International Publication No. WO 2015 / 077818, International Publication No. WO 2016 / 077863, and the references therein generally include the general requirement that the input particle size is typically less than about 100 microns. Therefore, the degree of firing as defined herein, as the proportion of carbonate converted to oxide in the reactor within this residence time, is sufficient for the use of the fired product. One of the variables controlling the firing process in the direct separation reactor is the wall temperature distribution. Therefore, usually, the residence time and the average value of this wall temperature are referred to as important variables in reactor design. In the direct separation reactor, it is preferable that the particles flow downward under gravity. The residence time is related to the terminal velocity of the particle size distribution (PSD), and the acceleration of the particles falling under gravity is balanced by the gas-particle friction that depends on the direction of the gas flow.

[0009] Regarding the residence time and temperature of the reactor, generally, the degree of firing of the material is preferably at least 95%, most preferably at least 97% or more. However, in the case of cement powder, it is lower than that and can be about 85%. This is because a subsequent clinkering process may require an endothermic load, such as when a rotary kiln is used in clinker production. To achieve the desired degree of firing of the material, a direct separation process capable of controlling the residence time and temperature within the reactor segment is required. The invention of the present disclosure is, in part, directed to increasing the residence time and temperature of the direct separation reactor.

[0010] Regarding the PSD, three values from the measured cumulative volume distribution, namely, the diameter d as the diameter at which 10% by volume of the particles is less than d 10 less than, the diameter d as the diameter at which 50% by volume is less than d 10 and the diameter d as the diameter at which 50% by volume is less than d 50 less than, the diameter d as the diameter at which 50% by volume is less than d 50and 90% by volume is d 90 d as a diameter less than 90 It is useful to define. The calcined powder of the carbonate material has many uses, and the most preferred d 50 size exceeds about 100 microns, and this is described in the prior art mentioned above. Specifically, the product covers a range of about d 10 ~d 90 from 0.1 to 300 microns, and each product has a predetermined PSD within this range.

[0011] d 50 Powder materials with d exceeding 100 microns are easier to handle than materials with smaller d, and the products are commonly used in specific powder applications. It is necessary to expand the direct separation technology so that such powder raw materials can be produced within this range. 50 In other applications, materials in the form of millimeter-sized granules, preferably in the form of granules of a mixed material, are required, especially in applications in mineral processing (such as slagging for the production of metals such as iron, aluminum, and magnesium, when entrainment of such products in a gas stream is not desirable), and in applications in cement production (when clinker formation occurs by reaction between the bound particles in the granules in subsequent process steps for forming clinker), and in applications in refractory products (when briquettes are produced before sintering). It is necessary to expand the direct separation technology to enable the production of such granulated materials, which also includes integrating the direct separation technology into the production of granulated products.

[0012]

[0013] ​One skilled in the art would understand that the PSD of the fired material can vary considerably for many applications. Specifically, since it is necessary to reduce the emissions associated with the production of such products, it is necessary to apply a direct separation reactor to process carbonate materials with a wide range of particle size diameters. Larger particles fall through the direct separation reactor faster than smaller particles, so the residence time of larger particles is shorter compared to smaller particles. In some cases, it may be practical to extend the length of the direct separation reactor described in the prior art mentioned above to achieve this desired degree of firing. However, generally, it is preferred to use a more compact direct separation reactor. The invention of the present disclosure is directed to a firing process for a direct separation reactor that can process larger particles than those previously disclosed.

[0014] The direct separation reactors described in International Publication No. WO2015 / 077818 and International Publication No. WO2016 / 077863 are described as single-tube reactors, and the feed material is typically on the order of 8 to 10 tons per hour. For large-scale manufacturing processes such as cement, it is desirable to scale up the reactor to approximately 200 tons per hour. It is necessary to adapt the direct separation reactor to such a scale-up so that the advantages of the process can be provided for mass production.

[0015] The invention of the present disclosure is mainly directed to reducing CO 2 emissions in the firing of carbonate materials, particularly limestone and cement raw material powder. However, the invention can also be applied to firing reactions that are phase changes or other materials that emit gases other than CO 2 . Examples of such firing processes include the removal of moisture and water of hydration by steam generation, and the volatilization of acidic gases such as sulfur compounds, ammonia, and hydrochloric acid.

[0016] The project leading to this application has received funding from the European Union's research and innovation program "Horizon 2020" under grant agreements No. 654465 and No. 884170. (Background)

[0017] The invention described in the present disclosure is mainly obtained from observing and understanding the firing of a material containing calcium carbonate (CaCO 3 ) to produce lime (CaO) in a direct separation reactor. Such an invention described herein can be considered an improvement over International Publication No. WO 2015 / 077818, International Publication No. WO 2016 / 077863, and the documents therein. Further, the disclosed invention can be applied to a direct separation reactor to scale up the process, facilitate the integration of the direct separation reactor into an industrial process, or process other materials in the direct separation reactor for any purpose.

[0018] Those skilled in the art will understand that in the treatment of calcium carbonate-containing materials including limestone, dolomite, and cement powder, freshly fired lime particles are "sticky". The initial mention of this property is in the historical literature of lime burners, and the results have influenced the design of modern manufacturing processes for producing large quantities of CaO. There is a vast amount of literature on this theme, which is summarized below.

[0019] The stickiness of lime is related to the formation of particle aggregates, the formation of deposits on low-temperature surfaces, the sticking properties of the material bed, and the problems of product conveyance. The physical cause of stickiness is related to the high surface energy of the CaO particles generated by the firing reaction front moving within the particles. Without being limited to theory, the firing reaction produces CaO particles with a size of about 20 nm and a surface area of 100 m 2CaO particles exceeding / g are generated. These small particles have a high surface energy and naturally decrease during the sintering process at high temperatures. In this process, the particles grow to exceed 100 nm by a process known as Ostwald ripening, a neck is formed between adjacent CaO particles, and then the process is initiated by the diffusion of CaO through these necks, and the small particles are absorbed by the large particles. As the size of the particles increases due to this coarsening process, the surface energy decreases. From the perspective of the pores between the particles, the porosity is shifting from mesopores of 5 - 10 nm to macropores exceeding 100 nm. The literature states that such sintering occurs through various mechanisms in which the sintering rate increases not only with temperature but also with the partial pressures of CO 2 and H 2 O, because sintering is catalyzed by these gases. Due to this catalytic effect, CaO can move rapidly on the micron-length scale. The diffusion of CaO is important for processes such as ceramics and cement manufacturing, mineral slagging, and the impact on flash sintering described later.

[0020] The cause of such "adhesiveness" of lime particles is that necks grow between colliding particles, or between particles adhering to the surface, or between particles filled in the bed, resulting in a decrease in surface energy. The process of physical sintering of grains within a particle is indistinguishable from the adhesion of physically contacting particles. In the literature on ceramics, cement, and the slagging process, the term "sintering" is applied to processes both within and between particles. In the present invention, aspects related to adhesiveness are that the treatment of aggregates passing through the reactor is a process of "aggregation" in which particles adhere during the firing process to a significantly different extent than individual particles, and further, a process of "cascade aggregation" occurs in which aggregates adhere. Without being limited by theory, (a) aggregates are formed from particle-particle collisions within clusters of particles generated directly in the separation reactor to minimize the friction of gas particles, (b) aggregates are more easily formed under conditions where the gas-particle turbulence that increases the collision velocity between particles within the cluster is stronger, (c) the strength and persistence of adhesion are the result of the sintering process, and (d) it is understood that the influence of the persistence of aggregates on the firing process may be significant.

[0021] Regarding the direct separation reactor, prior art related to CaO sintering includes CO 2 catalytic sintering of CaO by, in which case the initial stage of sintering occurs within 30 seconds at a temperature exceeding about 800 °C and a CO 2 partial pressure exceeding about 5 kPa. This sintering time is comparable to the residence time of 10 - 50 seconds typically used in a direct separation reactor where the CO 2 partial pressure is about 100 kPa and the temperature is about 900 °C. Therefore, it is reasonable to expect that the CaO produced in such a direct separation reactor will be sintered to have a surface area of less than about 20 m 2 / g. This has been confirmed in a direct separation reactor. Since sintering occurs during the residence time of particles in the reactor, the influence of "adhesiveness" between particles is also clear, and it is expected that it may affect the performance of the direct separation reactor in the treatment of materials that produce CaO in the presence of CO 2 . This disclosure focuses on inventions that mitigate adverse effects or utilize those effects to produce new materials.

[0022] One object of the present invention is to provide one or more means for optimizing the design of a direct separation tube reactor in order to control the effect of the adhesiveness of lime.

[0023] Another object of the present invention is to provide means for scaling up a direct separation reactor to a larger production capacity.

[0024] Another object of the present invention is to describe the use of the present invention for integrating a direct separation reactor into industrial applications, and specific applications include the production of Portland cement, iron, aluminum, and magnesium metals.

[0025] Another object of the present invention is to apply these inventions to the treatment of other materials, and it is advantageous to simplify the process or improve the properties of the materials from the perspectives of operation and complexity.

[0026] No discussion of prior art throughout this specification should be construed as an admission that such prior art is widely known or forms part of the common general knowledge in the field. (Summary) The invention of this patent generally relates to improvements in direct separation technology. (a) Such an invention includes a system for firing a powder material that includes one or more reactor tubes in which the falling powder is heated mainly by radiation from an external heating wall of the tube. The powder firing process may be a reaction that releases gas, a reaction that induces a phase change, or both. The average velocity of the powder while passing through the reactor tube is 1.0 m / s or less, preferably 0.2 m / s or less. The powder material flux of each tube is preferably in the range of 0.5 - 1 kg·m -2 ·s -1 and the length of the heating zone is in the range of 10 - 35 m. (b) Means for treating large particles exceeding 100 μm using countercurrent flow of particles and gas; (c) Means for reducing agglomeration and clustering by reducing the turbulent flow of gas particles using co - current flow of particles and gas; (d) A means for injecting particles into a direct separation reactor using a counter - current tube system that cools the fired particle stream from the direct separation reactor and heats the ambient particle stream, and in the case of lime, partially calcines and passivates the particles using a pre - heating system to suppress agglomeration and fouling when the particles are injected into the direct separation reactor; (e) A means for efficiently externally heating the reactor wall using a closely integrated combustion furnace segment, a flameless combustor using various fuels, and electric heating, and in the case of carbon - based fuels, using a post - combustion process to capture CO 2 and minimize energy consumption and CO 2 emissions; (f) Using segmented tubes to enable (i) optimization of process energy consumption by switching process gas pressure, (ii) injection of high - temperature gas and fuel / air, and (iii) production of products (e.g., production of Ca(OH) 3 from CaCO 2 ) by an optimized sequence of chemical reactions; (g) A means for thermally granulating lime by utilizing the adhesiveness of CaO in CO 2 , including mixing lime with other minerals and making the granulated bodies (granules) usable in industrial processes where slagging or clinkering is important (such as the production of iron and aluminum using CaO, the production of magnesium metal from dolime MgO·CaO, etc.); (h) Means for scaling up the process using a large number of tubes.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0027] The first problem to be solved is particles containing CaO, especially CO 2To optimize a direct separation reactor for processing materials that produce CaO particles in the presence of

[0028] The second problem to be solved is to optimize the direct separation reactor to scale up the process to a larger throughput.

[0029] The third problem to be solved is to integrate the direct separation reactor into many industrial processes.

[0030] The fourth problem to be solved is the improvement of the direct separation reactor for firing a wide range of materials.

Means for Solving the Problems

[0031] In a first aspect of the present invention, several measures are described to reduce the formation of CaO-induced aggregates of particles injected into the direct separation reactor, reduce the fouling of the metal surface through which heat is transferred, and reduce the tendency of the bed of these particles to resist fluidization for transport. Three solutions are described. The first solution is to process larger CaO particles by taking advantage of the observation that aggregation decreases when firing larger particles. The second solution is to reduce the aggregation of CaO particles by minimizing the collision frequency between the particles. The third solution is to reduce the tendency of such CaO particles to adhere during collisions.

[0032] In a second aspect of the present invention, means are described to promote the aggregation of CaO particles produced from a direct separation reactor to produce products that require granules of the material for use in subsequent processes using the invention described in the first aspect. Such processes include the production of Portland cement from calcined cement powder produced in a direct separation reactor, the production of magnesium metal using the Pidgeon process from dry lime MgO·CaO produced in a direct separation reactor, and the production of low-emission lime granules produced in a direct separation reactor (for injection into a slagging process used in the production of steel and aluminum, for example, to remove impurities such as silicates).

[0033] In a third aspect of the present invention, several measures for integrating a direct separation reactor into an industrial process are described. These measures include means for preheating the input powder using waste heat, means for injecting the powder into the reactor, means for supplying heat to the reactor wall, means for extracting the process gas stream from the reactor, means for minimizing the loss of solids in the exhaust gas, and means for cooling the product. The main requirement of this aspect is to minimize the energy required to process materials generally supplied under ambient conditions and, preferably, to provide means for supplying the powder product and the exhaust gas stream under the required conditions with minimal energy consumption.

[0034] In a fourth aspect of the present invention, several measures are described that enable the scaling up of the production capacity of a system using a direct separation reactor. There are reasonable limitations on the diameter of the direct separation reactor tubes in relation to the penetration depth of radiation into the particle-gas mixture. Therefore, the scaling up of production capacity is mainly carried out through an array of tubes. The measures for scaling up include means for distributing the preheated solids to a number of tubes, means for heating the powder in separate tubes in the furnace from a combustor, and means for collecting the powder stream and the gas stream from the reactor tubes for subsequent processing. The main requirement of this aspect is to minimize the energy required to process materials generally provided under ambient conditions and, preferably, to provide means for supplying the powder product and the exhaust gas stream under the required conditions with minimal energy consumption and to achieve economies of scale.

[0035] In a fifth aspect of the present invention, specific process steps are proposed that facilitate the integration of a direct separation reactor into a manufacturing process, with the main application being the production of cement clinker.

[0036] In a sixth aspect of the present invention, there is provided a system for firing a powder material comprising a plurality of vertical reactor tubes, wherein the falling powder is heated around the heating zone by radiation from an external heating wall of the reactor tube, and the firing process of the powder may be a reaction that releases a gas or a reaction that induces a phase change. The average velocity of the particles of the falling powder while passing through the reactor tube is 1.0 m / s or less, and the powder material flux of each tube is preferably in the range of 0.5 to 1 kg·m -2 ·s -1 range, and the length of the heating zone is in the range of 10 to 35 m. This relates to a system.

[0037] Preferably, the powder material contains a compound or mineral that releases a gas when heated, and the gas is at least one selected from the group consisting of acidic gases such as carbon dioxide, steam, hydrogen chloride, and alkaline gases such as ammonia.

[0038] Preferably, the mineral is limestone or dolomite.

[0039] Preferably, the compound contains silica and clay, and the powder material is raw cement powder for producing Portland cement.

[0040] Preferably, the particle volume distribution of the powder material is limited such that less than 90% has a diameter of less than 250 μm and more than 10% has a diameter of more than 0.1 μm.

[0041] Preferably, the released gas flows upward in the tube against the flow of the fired powder, and the gas is discharged at the upper part of the system.

[0042] Preferably, the released gas and the gas introduced into the system flow downward in the reactor tube together with the flow of the fired powder, and the gas is discharged at the bottom of the system.

[0043] Preferably, the inner tube is disposed in each tube, and the powder material flows downward in the reaction ring together with the released gas. At the bottom of the reactor, the gas flow is reversed and flows upward through the inner tube, and the released gas and the gas introduced into the system are discharged at the top of the system.

[0044] Preferably, the powder material entrained in the discharged gas is separated and reinjected into the system.

[0045] Preferably, the injected powder is preheated in a gas-powder preheater system before being injected into the system.

[0046] Preferably, the gas-powder preheater system is one or more refractory heating tubes in which the low-temperature powder material drops through the high-temperature rising gas and is heated by the rising gas, and the average velocity of the powder while passing through the preheating tube is 0.5 m / s or less.

[0047] Preferably, the powder discharged from the bottom of the system is cooled in a gas-powder cooling system.

[0048] Preferably, the gas-powder cooling system is one or more refractory cooling tubes in which the high-temperature powder material drops through the low-temperature rising gas, and the average velocity of the powder while passing through the cooling tube is 0.5 m / s or less.

[0049] Preferably, the external heating system for heating the tube wall from the outside is a system in which a combustor and a furnace are integrated, enabling control of the temperature profile below the heating zone of the system.

[0050] Preferably, the external heating system is a flameless combustion system that enables control of the temperature profile below the heating zone of the system.

[0051] Preferably, the fuel of the external heating system is at least one gas selected from the group consisting of natural gas, synthetic gas, city gas, producer gas, and hydrogen, and the combustion gas is air, oxygen, or a mixture thereof heated from the flue gas of the external heating system.

[0052] Preferably, CO in the flue gas 2 is extracted using a post-regenerative combustion CO 2 capture system, which system is at least one selected from the group consisting of an amine adsorbent system, a bicarbonate adsorbent system, and a calcium looping system.

[0053] Preferably, the external heating system is an electric furnace, and the power is generated from a high-temperature gas stream within the production plant of which the system is a part or extracted from the grid and is configured to enable control of the temperature profile below the heating zone of the system.

[0054] Preferably, the external heating system is any one combination of the external heating systems according to claims 14, 15, and 18, which can be applied to different segments of each tube or different tubes, and in the operation of the system, a variable combination of such external heating systems can be used while maintaining continuous production of the fired material.

[0055] Preferably, the powder material is injected into the reactor tube at several depths.

[0056] Preferably, each tube is divided into a plurality of segments attached in series, and the gas released or introduced in each segment is withdrawn from that segment using a gas block between the segments.

[0057] Preferably, the partial pressure of the gas released during firing in the upper segment can be reduced in the lower segment so that the reaction further proceeds by a partial pressure drop to achieve a new equilibrium at a low partial pressure, which includes a drop in the wall temperature of the lower segment so that the thermal energy accumulated in the partially fired powder from the upper segment is used for firing.

[0058] Preferably, the wall temperature of each segment increases sequentially from the upper segment in each segment so that the gas released from each segment becomes a specific gas of a desired purity, and other gases can be added to each segment to promote the catalytic reaction in the reaction step and / or the sintering of the material during the reaction step.

[0059] Preferably, the system produces sintered MgO for refractory blocks from magnesite.

[0060] Preferably, the system produces Ca(OH) 2 or Mg(OH) 2 from limestone or magnesite.

[0061] Preferably, the system controls the oxidation state of the battery precursor.

[0062] Preferably, each tube is divided into several segments, and the gas released or introduced in each segment is withdrawn from that segment using a gas block between the segments, and a high-temperature gas flow is introduced into the segment to increase the thermal energy of the gas and particles in that segment, enhancing the thermal energy provided by external heating.

[0063] Preferably, the gas flow includes a combustible fuel and oxygen or air for combustion, inducing combustion in that segment, increasing the thermal energy of the gas and particles in that segment, and enhancing the thermal energy provided by external heating in that segment or another segment.

[0064] Preferably, the temperature increase due to combustion is sufficient to induce particle-particle or interparticle reactions typical of the roasting or clinkering reactions that occur subsequently in the powder bed formed at the bottom of the segment, and the energy released from the exothermic reaction can maintain or increase the temperature of the powder bed, so that the induced reaction is completed sufficiently during the residence time in the powder bed.

[0065] Preferably, the preheating temperature of the gas-powder preheater system is in the range of 650 to 800 °C, and the partial pressure of the gas released during firing is less than 15 kPa, so that the powder material is partially fired and then sintered so that the surface energy of the particles is sufficiently reduced, whereby the tendency of the particles to bind and aggregate thereafter is reduced.

[0066] Preferably, the material is limestone, and the fired material, or a mixture of the fired material and other minerals, is introduced into the post-treatment system to produce granules of the material, the granules are formed by stirring the powder, the gas environment contains carbon dioxide, and the temperature of the granulator system is in the range of 650 to 800 °C where the recombination of lime and CO 2 is suppressed.

[0067] Preferably, the material is first fired in a first segment using a steel reactor wall to supply heat to the system, and the gas released or introduced in each segment is withdrawn from that segment using a gas block between this first segment and the lower segment, so that a second gas stream of a different gas is injected into the second segment, and heat transfer through the reactor wall of the second segment is controlled so that the fired powder from the first segment reacts with the gas to form a new material compound.

[0068] Preferably, the powder material is limestone CaCO 3 or dolomite CaCO 3 ·MgCO 3 and the fired product from the first segment is lime CaO or dolomite CaO·MgO, the discharged gas is CO 2 and the gas injected into the second segment is steam H 2 O, the temperature is controlled by removing heat through the wall so that slaked lime is discharged from the second segment, and the diameter of the pipes in the system is selected so that the heat transfer and reaction rate are balanced at the minimum segment length by the residence time.

[0069] Preferably, the slaked lime or dry lime product is CO in the ambient air2 It has high reactivity with CaCO 3 or MgCO 3 ·CaCO 3 This product is converted to CO from ambient air in a circulation system. 2 This product is then used along with renewable fuels to remove CO2 from the combustion 2 When combined with the capture of carbon dioxide, the system produces a carbon-negative emissions product.

[0070] Preferably, the reactor tube is vibrated to remove any buildup of solid material adhering to the walls of the system.

[0071] Preferably, heat from the external heating system to each tube is separated by a refractory wall so that the plant can operate efficiently with any number of tubes through the use of refractory materials and energy distribution, including gas and radiation, which controls the exposure of any tube to radiation and the convective transfer of heat so that the temperature profile is controlled within the desired ranges related to thermal stresses in the metal tubes and energy consumption by the system.

[0072] Preferably, the preheater segment and / or the cooling segment require distribution of preheated material from a central preheater to each tube, this distribution being achieved by at least one of the following groups: an L-valve, an assembly of L-valves designed to provide controlled distribution of powder to each tube, an agglomeration system that collects hot calcined material from each tube to a central cooling system, and a central downstream processing system such as a kiln, and the agglomeration is achieved by a system of gas slides where the flow of hot calcined powder is controlled to provide a continuous flow of material.

[0073] Solutions to the problem can be derived from many of these aspects.

[0074] Further aspects of the invention will become apparent from the description and drawings.

[0075] Embodiments of the present invention will be better understood and readily apparent to those skilled in the art from the following description taken in conjunction with the drawings, which are given by way of example only:

Brief Description of the Drawings

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DETAILED DESCRIPTION OF THE INVENTION

[0087] Next, preferred embodiments of the present invention will be described with reference to the accompanying drawings and non-limiting examples.

[0088] Regarding the first aspect related to the reduction of CaO aggregates, based on the knowledge of gas-particle hydrodynamics considered below, its principle has been developed. In all embodiments described below, the particles flow down the direct separation reactor against gravity.

[0089] A preferred approach to suppressing aggregate formation is to increase the average particle size at a constant mass flow rate. The basic theoretical basis is that since the number density of particles decreases significantly, the collision rate between particles decreases. Moreover, since the momentum due to particle-particle collisions is large enough, the strength of the neck of CaO generated during the collision is insufficient and is destroyed, and the colliding particles repel each other without sticking. In the prior art regarding direct separation reactors, generally, the particles are considered to be about 20 μm, generally less than 100 μm. The object of the invention disclosed in this specification is to increase the particle size up to about 250 μm. There are three factors that can reduce the degree of calcination and can be achieved with such large particles. First, since the mass of the particles is large, the terminal velocity becomes high, and the residence time of the particles is shortened; second, since the average surface area decreases, the absorption of radiation by the particles from the high-temperature wall decreases; third, in many materials with low porosity, the time it takes for the reaction front to move from the surface to the center of the particle becomes longer as the particle is larger. One solution is to simply increase the length of the reactor to increase the residence time. However, in many cases, this solution is not practical. Another solution is to increase the wall temperature of the reactor to increase the heat transfer rate. However, in many cases, the steel of the reactor tube cannot withstand high temperatures. This is because the strength of the steel is lost and the corrosion mechanism is accelerated. New steel may have the potential to mitigate such effects.

[0090] Another solution is shown in Figure 1. The residence time can be shortened by using a countercurrent configuration in which the terminal velocity of the particles is reduced by the friction of the gas particles against the rising gas generated by the reaction. Figure 1 depicts a direct separation reactor with countercurrent flow, where a powder feed 101 is injected into the reactor system by a rotary valve 102 and enters the reactor tube 104 from the injection tube 103. The falling powder 105 is in a plume shape and is heated towards the reaction temperature by the hot rising process gas stream 106 rising from the reaction zone 107 by gas-particle heat transfer by countercurrent flow. The cooled gas is separated from the entrained powder by a system including a separation plate 108 and a tangential gas ejector tube 109, and a cooled process gas stream 110 is obtained. The powder in this gas stream is extracted by a cyclone / filter system (not shown) and reinjected into the reactor. The powder 111 heated in the reactor slowly falls against the rising gas, enters the reaction zone 107, and is heated there by radiation from the reactor wall. Heat is generated in the furnace 112, the steel wall 113 is heated, and the heat flows to the gas and particles in the reactor, inducing the desired reaction. The length of the heating zone is sufficient for the reaction to be completed to the desired extent. The hot calcined powder falling is collected in the reactor cone 114, forming a hot calcined powder bed 115, which is extracted from the reactor by an exhaust valve 116, which may be a system of flap valves, and a calcined powder stream 117 is obtained. The advantage of this configuration is that the process can achieve high thermal efficiency with less dependence on an external heat exchanger because the particles are heated by heat transfer between the falling particles and the rising hot gas. It should be noted that such particles of mass and size can in principle be easily discharged from the reactor, so in many cases this approach may not seem effective. However, in the wake of large particles, it is known to exhibit strong gas vortices behind the falling particles, and the particles tend to form clusters, which minimizes gas-particle friction, and the clusters flow down the tube against the rising gas.Furthermore, by reinjecting the entrained particles into the reactor, the mass of the particles accumulated in the reactor grows to the point where the particles are organized as clusters and have a mass density sufficient to break through the rising gas. At high mass flow rates, the clustering of the particles is sufficient, and the high-speed exchange of particles between the clusters can result in a more laminar momentum of the clusters, potentially suppressing large-scale turbulence. Additionally, the growth of fouling is suppressed by the tendency of the particles to flow towards the walls, and there is also the advantage that the gas-particle friction is minimized. It should be noted that if the particles are not injected into the heating zone of the reactor, no process gas is generated. Therefore, conditions are always formed where the particles must flow down through the reactor. One effect of the configuration of FIG. 1 is that pulsations can occur in the mass flow through the reactor, and such effects can be controlled by the settings of the reactor and the cyclone / filter. Another advantage of the configuration of FIG. 1 is that the particle flow to the bottom of the reactor is not affected by the gas flow, and large particles in the reactor bed do not undergo significant agglomeration like small particles, so the conveyance and transport of particles from the reactor are not hindered. To suppress such agglomeration, it has been found that preferably a small amount of high-temperature steam or air can be injected into the bottom. CO. 2 The steam or air in the gas stream is condensed or removed during the compression process using standard processes. These gases are preferably less than 10% of the process gas stream and most preferably less than 5%. Such high-temperature gases can also adjust the residence time of the powder, and when the gas is preferably steam or air, the decrease in partial pressure can potentially increase the degree of calcination due to the decrease in the equilibrium pressure of the calcination reaction. Furthermore, in the case of calcination of carbonates, the replacement of CO 2 at the bottom of the reactor can reduce the agglomeration of the particles remaining in the reactor bottom bed, promote fluidization, and reduce effects such as rat-holing.

[0091] Another advantage of the configuration of FIG. 1 is that, due to the low strength of particle-particle bonding between large particles, fouling of the tube surface that limits heat transfer is less than that observed with small particles. According to experiments, the vertical surface of the tube has a self-cleaning effect on both small and large particles, and since a part of the coated surface peels off at high temperatures, the strength of the particle bonding is weak enough not to support a thick coating, suggesting that the fouling thickness is typically less than 1 mm. The coating thickness (measured by the temperature drop between the inner steel wall and the exposed coating surface) is found to decrease as the particle flux increases, which is expected from the increased shear force caused by the high momentum of the solids removing the coating. This is a feature of all the configurations disclosed below. However, its thickness depends on the embodiments described herein, and it can be seen that the suppression of aggregation correlates with reducing the coating thickness.

[0092] It should be noted that this configuration of FIG. 1 is generally applicable to the firing of materials with little tendency for large particles to aggregate. The longer residence time and less powder loss due to countercurrent clustering are generally advantages. In applications where the process is a phase change in pyroprocessing, injecting gas at the bottom can increase the residence time, and the gas can be selected to catalyze the phase change. An example is the treatment from α-spodumene to β-spodumene for lithium extraction, and the catalyst is steam.

[0093] Often, the particle size of the powder being fed cannot be increased, and thus the approach of the embodiment of FIG. 1 is not possible. It has been observed that when small particles are directly injected into the separation reactor, several effects can occur when CaO is formed by firing. These include an increase in fouling of the high-temperature steel reactor surface, resulting in resistance to radiative heat transfer from the walls to most of the reactor, an increase in resistance to the flow of powder collected at the bottom of the reactor, and large aggregates formed within the reactor falling through the reactor at a sufficient rate, resulting in a decrease in the degree of firing. As described above, all of these effects are thought to be due to the stickiness of the lime that occurs during firing. Large granules of lime with a size of up to several millimeters may be formed, in which case large aggregates of this size are formed by the aggregation of the aggregates, which is called "cascade aggregation". Under other conditions, the size of the aggregates is smaller, for example, about 100 - 150 μm. Although such conditions may be found and it is possible to achieve the desired degree of firing by firing such aggregates, it is difficult to control the occurrence of cascade aggregation from limited aggregation, which is undesirable for quality control.

[0094] The principle for reducing aggregation is to minimize the turbulence of the gas-particle flow at all length scales. This is because high turbulence maximizes the particle-particle and particle-wall collision frequencies, and suppressing turbulence limits the formation of aggregates. The embodiments of FIGS. 2 and 3 show examples of how aggregation can be controlled by minimizing turbulence. FIG. 2 shows a co-current system in which the process gas flow is discharged at the bottom of the reactor, and FIG. 3 shows a system in which the process gas flow is discharged through a central tube, whereby the gas flow is discharged at the top of the reactor.

[0095] Figure 2 depicts a direct separation reactor having co-current flow, where a powder feed 201 is injected into an injection tube 203 by a rotary valve 202 and enters a reactor tube 204. The falling powder 205 is in a plume shape and is heated towards the reaction temperature by radiation from a steel reactor wall 206 that heats the gas and particles. The heat is generated within an external furnace 207 and the steel wall is heated. The heated powder 208 falls deeper into the reactor and enters a reaction zone 209 where the radiant heat from the wall is absorbed to induce the desired reaction. As the reaction progresses, a high-temperature process gas 210 accelerates the particles through the reactor by co-current flow. The length of the heating zone is sufficient for the reaction to be completed to the desired extent. The fired powder 211 and the high-temperature process gas 212 are discharged from the bottom of the reactor. These gas and particle flows are separated by a reactor cone 213, a gas ejector tube 214, and a powder bed 215, acting as an inertial separator that discharges the high-temperature process gas vapor 216 from the reactor and deposits the powder on the powder bed. The high-temperature powder stream 217 is discharged from the reactor by an exhaust valve 218 which may be a flap valve system. The powder in this gas stream is extracted by a cyclone / filter system (not shown) and reinjected into the reactor.

[0096] Figure 3 depicts a direct separation reactor with co-current flow. A powder feed 301 is injected into an injection tube 303 by a rotary valve 302 and enters a reactor tube 304. The falling powder 305 is in a plume shape and is deflected by a deflection cap 306 and enters a reaction ring formed by a suspended central tube 307 (its suspension is not specified). The falling powder 308 is heated towards the reaction temperature inside the annulus by radiation from a steel wall 309 heated by a furnace 310. The heated powder 311 falls deeper into the reactor and enters a reaction zone 312 where radiant heat from the wall is absorbed to induce the desired reaction. As the reaction progresses, a high-temperature process gas 313 accelerates the particles through the reactor by co-current flow. The length of the heating zone is sufficient for the reaction to be completed to the desired extent inside the annulus. The gas and particle flows are separated by a reactor cone 314, and a powder bed 315 forces high-temperature process gas vapor 316 into the central tube 307 and discharges it from the reactor through a gas ejector tube 317, and the powder is deposited on a fired powder bed. The high-temperature powder stream 317 is discharged from the reactor by an exhaust valve 319 which may be a flap valve system. The powder in the gas stream 317 is extracted by a cyclone / filter system (not shown) and re-injected into the reactor.

[0097] The essential difference between FIGS. 1 and 3 is that in FIG. 3 there is a physical barrier for separating the gas flow and the powder flow. It should be noted that in FIG. 1, the powder tends to preferably flow down near the outer wall of the reactor. This is because it is known from the basic principle that the friction between gas particles is the lowest in that region.

[0098] One relative advantage of the central tube in FIG. 3 is that since the velocity of the rising gas flow is high, the size of the cyclone at the upper part of the reactor for separating fine powder is smaller than that of the inertial separator, and particles are re-injected into the upper reactor. However, the efficiency of the large inertial separator at the bottom of the reactor is low, and a cyclone / filter is required to separate fine powder. Another advantage is that the central tube can absorb radiation from the high-temperature outer tube, and this tube can re-radiate its energy to the gas-particle flow, so that the net heat transfer rate can be optimized. Another advantage is that the high-temperature CO 2 flow discharged from the upper part of the reactor can be used to partially preheat the flow of the input powder, for example, by a cyclone. This aspect will be separately considered below regarding the optimization of integration. Another advantage of the central tube is that the extraction efficiency at the bottom can be increased by adding a swirling element near the end of the annular tube and adding a swirling element of blades near the inlet of the inner tube. Both of these elements form an additional flow pattern in the gas above the cone at the bottom of the reactor, enhancing the separation efficiency of particles and gas in the region below the central tube. Nevertheless, the separation of gas particles at the bottom is sufficiently effective without using any of these options. The central tube in FIG. 3 may be perforated or may be composed of suspended segments. Also, inside the tube, blades may be used to swirl the gas so that entrained powder can be extracted from the gas flow into the annular part by an in-line ejector. The embodiment of FIG. 3 is preferred because it can provide such options. There are also additional options for mitigating agglomeration and its associated effects. The sintering of the particle reaction surface is as described above. One such surface is the outer surface of the particle. First, the reaction front develops on this surface, and as the firing starts, this surface begins to sinter, so that from that point on, the tendency to bind the particles weakens. In many configurations of the direct separation reactor, the particles are preheated before being injected into the reactor. FIG. 4 shows an exemplary embodiment in which the external particle surface can be passivated to some extent by using a preheating process to partially sinter and sinter the surface.

[0099] Those skilled in the art will understand that CO 2It will be understood that by lowering the partial pressure, the temperature at which firing is initiated can be lowered. Also, those skilled in the art will understand that the preheating of the powder can be controlled using a low CO 2 gas flow so that surface firing is initiated to a controlled extent within the preheater. FIG. 4 depicts the preheating segment of a preheating / firing / sintering system. As will be described later, a powder feed 401 at a temperature below the firing temperature is injected into an injection tube 403 by a rotary valve 402, and this injection tube 403 feeds the particles into a refractory-lined heat exchange reactor tube 404, resulting in a plume of injected falling powder 405. A high-temperature steam / air stream 406, as will be described later, has a temperature high enough to preheat the powder, induce solid firing to a limited extent, and sinter the fired particles, and is injected into the bottom of the system using a tangential gas injection tube 407 and flows upward as a swirling gas flow 408. When the upward gas flow and the powder flow move in countercurrent, heat exchange occurs between the two, and the injection conditions of the system are designed to reduce large-scale turbulence, enabling optimization of heat transfer between the particles and the gas. The upward gas flow is discharged to a gas exhaust 411 through a system of a separation plate 409 and a tangential gas ejector tube 410. The powder in the cooled gas flow 411 is extracted by a cyclone / filter system (not shown) and reinjected into the reactor. The falling heated powder 412 forms a bed 413 within a cone 414. The high-temperature powder exhaust 415 is discharged from the system using an exhaust valve 416, which may be a system of flap valves. The input temperature and mass flow rate are such that the degree of firing of the CaO material is preferably less than 10%, most preferably less than 5%, and the residence time of the powder in the bed is the time at which sintering of the powder in the powder stream 415 reduces the tendency of the particles to agglomerate when introduced into the firing furnace due to the adhesiveness of the surface layer.

[0100] Sintering of CaO on the surface is achieved by exposing the preheated powder to high-temperature CO 2It can be accelerated by transferring a part of the gas, and the aforementioned catalyst sintering can be accelerated. The powder is passivated to some extent by the residence time of the powder in the supply hopper. As another option, a small amount of steam can also be injected into the bed of pre-fired particles preheated to passivate the powder. Without being limited by theory, the sintering of CaO occurs faster in steam than CO 2 and occurs faster than Ca(OH) 2The reaction of the vapor that forms can be suppressed by maintaining the temperature of the material at about 580 °C or higher. In most cases, this condition can be met because the preheating of the powder is limited to about 720 °C by the available energy. A second feature of this embodiment is injecting the preheated powder into the reactor at several points below the reactor. The intent of this approach is to reduce the particle density at high positions within the reactor and lower the agglomeration rate at those positions. Such an embodiment is shown in FIG. 5, in which a direct separation reactor with a countercurrent flow similar to that of FIG. 1 is described, and a powder feed 501 is injected into an injection tube system 503 by a rotary valve 502 and enters a reactor tube 504. The reactor tube system of this embodiment is composed of three concentric tubes as compared with FIG. 1 having one tube. Since the lengths of the tubes are different, the powder is discharged into the reactor at different heights. The powder 505 falling from each such tube is heated towards the reaction temperature by the hot upward process gas stream 506 rising from the reaction zone 507 by countercurrent gas-particle heat transfer. The cooled gas is separated from the entrained powder by a system including a separation plate 508 and a tangential gas ejector tube 509, and a cooled process gas stream 510 is obtained. The powder in this gas stream is extracted by a cyclone / filter system (not shown) and reinjected into the reactor. The heated powder vapor 511 from each tube in the reactor accumulates and slowly falls against the rising gas, enters the reaction zone 507, where it is heated by radiation from the reactor wall, heat is generated in a furnace 512 that heats a steel wall 513, and that heat flows to the gas and particles in the reactor to induce the desired reaction. The length of the heating zone is sufficient for the reaction to be completed to the desired extent. The falling hot sintered powder is collected in a reactor cone 514 to form a hot sintered powder bed 515, which is extracted from the reactor by an exhaust valve 516, which may be a system of flap valves, and a sintered powder stream 517 is obtained.

[0101] The degree of suppression of agglomeration achieved by sintering is CO 2 or H 2It should be noted that there may be limitations because O binds to the surface and promotes rapid surface movement of CaO at a sufficiently high temperature. This property may be exploitable in the manufacture of new materials and applications in the case of low-emission lime produced in a direct separation reactor. Note that limestone granules (lime) are currently used in a wide range of high-temperature pyrolysis metallurgical processes as slagging agents to remove silica and other impurities. In these processes, ground limestone was often used, but lime is generally used because the endothermic load due to firing limestone to CaO is very large. In these processes, fine lime powder is not used. This is because in such pyrolysis processes, lime particles are entrained in the gas stream, and mm-sized lime granules are preferably used. Although it is interesting that a direct separation reactor can produce low-emission lime, there are limitations to the particle size as described above. However, experimental observations show that the quicklime produced from these reactors can be easily made spherical and granulated, and heat treatment can produce granules with the strength required for use in such processes. The embodiment of FIG. 6 shows how such a process can produce such granules. FIG. 6 is a granulation system in which powder 601 and a CO 2 -containing gas 602 are injected into a heated rotating drum 603, which is heated by a heating element 604 to produce granules 605 at a sufficiently high temperature to prevent the re-carbonation of CaO. The properties of these granules are essentially porous. Thus, a second use is to use such granules to capture gases such as SO x and CO 2 in a fixed bed, and the performance of these granules in such processes is enhanced by the fact that the reactivity of CaO inside the particles is higher than that of lime produced by conventional processes using high-emission lime. In another example, the granules of the CaO material are strong, porous and permeable, and H 2 O, SO x CO 2 Cl 2 H 2S and other gases or metal vapors can be used to absorb without causing cracks. In a further example, the high surface reactivity of CaO can be utilized to produce granules of the powder mixture. For example, the granules can be composed of silicate-containing minerals such as iron ore for steel production or kaolin for alumina production, and the CaO in the granules can be used in a subsequent process to form calcium silicate by a slagging process under appropriate conditions. In the case of magnesium metal, the CaO-containing material may be dry lime mixed with a reducing agent such as ferrosilicon, which forms magnesium vapor and calcium-iron silicate slag when heated. In all such cases, the granules provide a close contact that promotes the movement of CaO to facilitate slag formation. The prior art mentioned above recognizes that the direct separation reactor may be segmented into different zones. As an example, there is a post-treatment segment that processes the powder from the direct separation reactor to complete the reaction process. It is understood that as the reaction approaches completion, the reaction rate slows down, and the residence time until the firing reaction is completed may become very long. Depending on the product and application, a very high degree of firing may also be required. Figure 7 shows an embodiment that can be used to achieve the firing goal instead of extending the length of the reactor. In Figure 7, a general two-segment direct separation reactor is described, in which the first reactor segment is the same as that in Figure 1, and the second reactor segment below the first reactor segment is used to complete the firing reaction by several different designs described below, and the two segments are separated by a gas block. The gas block is actuated by a high mass flow of powder and substantially suppresses the flow of gas from the second segment to the first segment by gas-particle friction. The powder feed 701 is injected from the injection pipe 703 into the reactor pipe 704 by the rotary valve 702. The falling powder 705 is in a plume shape and is heated towards the reaction temperature by the high-temperature rising process gas flow 706 rising from the first reaction zone segment 707 by countercurrent gas-particle heat transfer.The cooled gas is separated from the entrained powder by a system including a separator plate 708 and a tangential gas ejector tube 709, resulting in a cooled process gas stream 710. The powder in this gas stream is extracted by a cyclone / filter system (not shown) and reinjected into the reactor. The heated powder 711 in the reactor slowly falls against the rising gas, enters the reaction zone, where it is heated by radiation from the reactor wall, generating heat in a furnace 712 that heats the steel wall 713, and this heat flows to the gas and particles in the reactor, inducing the desired reaction. The length of the heating zone is sufficient for the reaction to be completed to the desired intermediate extent, and the calcined intermediate powder 714 falls into a cone 715 where the powder is concentrated, flows into a gas block 716, and falls into a second reactor segment 717. A gas stream 718 having a composition according to the materials and operating mode of this embodiment is injected into this reactor segment, where it interacts with the powder and is discharged from the reactor segment as a stream 719. The efficiency of the gas block is set by the pressure drop of the gas across the two reactor segments. The wall temperature of the reactor segment can be controlled by an external heating furnace or a cooling segment 720 if required by the application. The desired reaction is completed in this segment, obtaining a calcined powder 721. This is collected in a reactor cone 722, forming a hot calcined powder bed 723, which is extracted from the reactor by an exhaust valve 724, which may be a system of flap valves, obtaining a calcined powder stream 725.

[0102] In the case of the formation of CaO where the reaction is incomplete, the temperature of the partially calcined powder 714 is slightly above about 895 °C. In one usage of the embodiment of FIG. 7, the CO 2 partial pressure is about 103 kPa and is reduced to about 10 kPa by injecting air or steam 718, whereby the reaction starts when the powder is transferred to the second segment. Calcination can be completed by consuming the heat in the powder or by adding additional heat from the furnace 720 as required. The same considerations apply to the formation of MgO. When using steam, the temperature must be maintained above the relevant hydration temperature.

[0103] In another example of the system embodiment of FIG. 7, the second segment is used to sinter the intermediate material 714. In a specific example, the intermediate is MgO produced by the calcination of MgCO as feed 701, and the gas 718 is steam, which is used to catalyze the MgO and give the surface area of MgO desirable for industrial applications. Without steam, the specific surface area may be greater than about 250 - 350 m 3 / g, and with steam, the specific surface area may decrease to less than about 10 m 2 / g. 2 / g.

[0104] In another example of the system embodiment of FIG. 7, the gas 718 may be a mixture of air or oxygen and a combustible material, and the combustible material is generally a gas such as syngas that reacts by flameless combustion to generate heat for the reaction. This mode of operation is preferably facilitated by the high temperature of the powder feed 714 that exceeds the autoignition temperature of the combustible material.

[0105] Note that the second segment can be directly integrated into the first stage of the reactor by injecting air and fuel at the bottom of a single-segment reactor. In this case, the concentration profile of the process gas is moderated by the mutual diffusion of the gases and increases as the gas rises in the reactor due to the firing reaction induced by the partial pressure drop.

[0106] In another exemplary embodiment of FIG. 7, the gas 718 injected into the second segment has components that react with the calcined intermediate powder 714 produced in the first segment. In this approach, the first segment is preferably operated to achieve a sufficiently high degree of calcination such that the reaction of the gas and the powder in the second segment can produce the desired calcined product 725. Further, the operating mode of the furnace / cooler 720 is set to establish the necessary reaction conditions, such as heat supply for an endothermic reaction or heat removal for an exothermic reaction. As a specific example, the calcined intermediate 714 is CaO from the limestone precursor 701, the injected gas 718 is steam, the furnace / cooling system 720 operates in the cooling mode, and the product 725 is slaked lime Ca(OH) 2 In the case of. The heat recovered at 720 can be utilized throughout the process flow to reduce the overall energy demand required for the process. The same considerations apply to the production of Mg(OH) from MgO 2 .

[0107] A general example for the manufacture of battery and catalyst materials is that the desired reaction is either a reduction process or an oxidation process of the intermediate 718 produced from the precursor 710, using an appropriate reducing gas or oxidizing gas 718 and setting the temperature to induce the desired reaction for the desired product 725.

[0108] Those skilled in the art will understand that the principles illustrated by the exemplary multi-segment embodiment of FIG. 7 can be applied to any calcination reaction, or pair of reactions, or sintering reaction where the gas has a composition appropriate for the desired process.

[0109] The manufacturing process of Portland cement is carried out in several stages. The prior art described for direct separation reactors includes processes where the initial stage of the process, i.e., the firing of cement raw material powder, is carried out within the direct separation reactor, and the performance of that stage may be improved by the invention described in this disclosure. The second stage is carried out in a rotary kiln where the fired powder is injected into the kiln and heated to about 1450 °C by a flame, activating the clinkering reaction that forms belite and alite, the main cementitious materials. It should be noted that the thermal efficiency of cement plants is typically about 60% or less because of the large heat loss from the rotary kiln and the ineffective utilization of the exothermic energy of the clinkering reaction. The embodiment of FIG. 8 is directed to an improvement of this process. In this embodiment, it describes how the injection of combustion gas and air / oxygen is used to raise the temperature of the powder discharged from the direct separation reactor by a homogeneous combustion reaction. In the application of the embodiment of FIG. 8, a process within a refractory-lined segment is shown that uses the rising countercurrent of reaction air and fuel to heat the powder to a temperature of about 1260 °C or higher. FIG. 8 describes a specific two-segment direct separation reactor for producing clinker from preheated cement powder, and an approach is adopted to form clinker within the direct separation reactor segment. In this approach, an option of using a flap valve to separate gas vapor is used. Cement powder 801 preheated to about 720 °C is injected into injection tube 803 using rotary valve 802 and supplied to reactor tube 804. The falling preheated powder 805 is in a plume shape, and the high-temperature rising CO rising from the first reaction zone segment 807 by gas-particle heat transfer by countercurrent 2It is heated towards the reaction temperature by the process gas stream 806. The cooled gas is separated from the entrained powder by a system including a separation plate 808 and a tangential gas ejector tube 809, and a cooled process gas stream 810 at approximately the same temperature as 801 is obtained. The powder in this gas stream is extracted by a cyclone / filter system (not shown) and reinjected into the reactor. The powder 811 heated in the reactor slowly falls against the rising gas, enters the reaction zone, and is heated there by radiation from the reactor wall. Heat is generated in the furnace 812, the steel wall 813 is heated, and the heat flows to the gas and particles in the reactor, inducing the desired reaction. The length of the heating zone is sufficient for the reaction to be completed to the desired intermediate degree, and the powder 814 of the calcined cement powder falls into a cone 815 where the powder is concentrated and is supplied by a flap valve 816 and falls into a second reactor segment 817. A fuel stream 818 and an oxygen / air stream 819 are injected into this reactor segment, where flameless combustion takes place to heat the powder 820. The reactor wall 821 is a refractory tube. In the combustion process, the powder 822 is heated to a temperature of about 1260 °C, indicating the start of the clinkering reaction to form belite. The hot particles fall into a vertical kiln segment 823 in a slowly moving bed. Here, an exothermic clinkering reaction proceeds by particle-particle contact, the temperature rises to about 1450 °C or higher due to the released heat, and alite is formed when the residence time of the bed is about 30 minutes or less. The heat release is completed in this segment, and clinker granules are obtained. The exhaust valve 824 discharges the hot clinker granules 825 from the vertical kiln, where they are cooled with air using a conventional grate cooler (not shown). Those skilled in the art will understand that, unlike the conventional kiln process with high heat loss, Figure 8 shows a highly energy-efficient process because the powder is heated by the exothermic reaction.

[0110] High energy efficiency of industrial processes is an important factor. Regarding the reactor, by using a direct separation reactor, the thermal energy efficiency for a given degree of calcination is not affected. Heat loss is related to the heat loss through the refractory skin surrounding the reactor furnace and combustor segments. In this embodiment, the present invention is extended to the consideration of the combustor-furnace configuration. Important factors for heat transfer are the temperature and the convective heat exchange to the steel reactor wall and the furnace refractory, and the optimization of the radiative heat transfer through the steel reactor wall. Generally, this is optimized by known techniques using high gas flow rates and gas vortices. The direct separation reactor can be operated by using a separate combustor box and piping the high-temperature flue gas to the furnace surrounding the reactor tubes in a way that gives these desirable characteristics, and the high-temperature flue gas exhaust can be used to preheat the combustion air. However, the duct connection and distribution of the high-temperature gas are not desirable. In FIG. 9, an exemplary embodiment for treating limestone shows a different approach. The selected fuel is syngas from biomass, and after combustion, CO 2 A capture system is used to show the carbon-negative product when the CO 2 stream is isolated (not shown). Generally speaking, it is desirable to closely integrate the combustor, furnace, and air recovery process to reduce the required amount of air. The embodiment of FIG. 9 shows that an array of recuperative flameless systems can be applied to reduce the flue gas volumetric flow rate. In such a system, the combustor and furnace are integrated, there is no flame, and due to the high flow rate of the mixed gas, the gas temperature is uniform. The thermal efficiency of the regenerative flameless combustor is very high, and since there is no flame, the generation of NOx is minimized. Using such systems in a distributed manner enables temperature control along the tubes and optimization of the calcination process inside the tubes. In the embodiment of FIG. 9, a system using a direct separation reactor is described, with a d of about 125 μm 50Process the limestone feed 901 crushed therein to lime 902. The reactor system has three segments: a first powder preheater segment 903, a second powder preheater segment 904, a direct separation reactor segment 905, and a powder cooler segment 906. In the first powder preheater segment, the high-temperature CO 2 gas stream 907 is injected into the bottom of the countercurrent heat exchange refractory-lined tube of the first powder preheater segment 903, into which the limestone powder 901 at ambient temperature is injected, and a cooled CO 2 gas stream 910 and partially heated limestone 911 formed on the bed are obtained. The partially heated limestone 911 from the bed is injected into the upper part of the heat exchange refractory-lined tube of the second powder preheater segment 904, where it is heated by the hot air stream 912 from the powder cooler segment 906 described later, and preheated limestone 913 is formed on the bed. If necessary, the temperature of this air stream can be raised by a duct heater (not shown) to bring the temperature of the preheated limestone to the limestone calcination start temperature of about 930 °C or in the vicinity thereof. The cooled air stream 914 is exhausted, but can also be used (not shown) to supply low-grade heat to the post-combustion CO 2 capture system 915 for flue gas described below. The preheated limestone 913 is injected into the direct separation reactor segment 905 shown here as the countercurrent system of FIG. 1, and a pure stream of treated CO 2 907 of approximately the same degree as the preheated limestone and hot lime powder 916 are obtained. The direct separation reactor is heated by the combustion of the high-temperature synthesis gas stream 917 formed from biomass 918 and air 919 in the gasifier 920. In the gasifier, the synthesis gas and ash 921 are separated. The tar generated in the gasification process can be reinjected into the high-temperature synthesis gas vapor. The steel pipe 922 of the direct separation reactor segment 903 is heated by the combustion of the high-temperature synthesis gas by a number of regenerative flame combustion systems, and one of the steel pipes 922 injects the air 923 preheated by the high-temperature flue gas from the combustor in the heat exchanger 924 to cool the flue gas vapor 925 to achieve a highly efficient combustion process. The CO 2 from that gas stream is post-combustion CO2 is injected into the capture system 915 where CO 2 926 is extracted and mixed directly with the separated gas vapor 910 to produce CO for compression and liquefaction. 2 Vapor 927 is obtained (not shown).

[0111] CO from fossil fuel combustion gases 2 Emissions are CO from the calcination product 2 It is a major contributor to emissions intensity. For lime and cement, combustion emissions are about 35% of the total emissions when using typical solid fossil fuels like coal. One approach to reduce combustion emissions is to use biofuels and use them in combination with a direct separation reactor. Biofuels are solid fuels, commonly called biomass, that can be gasified to syngas using known techniques and can be used in the configuration of Figure 9. Integrated Gasification Process The gasification process is carried out using known techniques where biomass is heated in steam / air to release combustible volatiles, the ash, including fly ash, with its carbon residue is separated and burned, and an indirect heating process provides the heat for volatilization. The hot volatiles are burned in a flameless combustor using preheated air. In this process, the gas may contain not only syngas but also tar precursors. This is because the tar precursors are burned. This means that the gas is kept above the tar condensation process, eliminating the need for costly processes to remove the tar precursors, and the fuel is not only preheated but also has a high LHV for combustion. Fly ash is removed from the gas stream to minimize the formation of silica glassy deposits on the steel walls of the furnace. The post-combustion capture process of Figure 9 can use either amines, bicarbonates, or hydrotalcites.

[0112] The above-described embodiments, and the embodiments exemplified by the examples of FIGS. 1 to 9, relate to a reactor based on a single tube. The scale-up of the process by increasing the diameter of the reactor is limited by the absorption of heat from the high-temperature wall by the particles and the process gas, and the mass flow rate is limited by the heat transfer capacity of the wall and the involvement of the particles in the process gas that affects the residence time of the particles in the reactor tube. Generally, the mass flow rate passing through a reactor with a diameter of about 2 m is in the range of 5 to 10 tons / hour. The height of the reactor depends on the reaction rate of the process and the heat transfer rate from the wall, and is usually 10 to 30 m. Therefore, the scale-up of the process is to increase the number of tubes. However, there are ingenuities in the design of the array of reactor tubes, and they will be described herein. FIG. 10 is an exemplary embodiment of a scaled-up system, in which four tubes shown as such are incorporated into the furnace, and the amount of refractory between the tubes is minimized so that each tube can be stopped with minimal influence on the adjacent tubes. The temperature of the inoperative tube is low enough that there is no concern about distortion in that tube, and the set point of the operating tube can be adjusted to maintain the degree of firing of the product and other process variables. This condition is achieved within the module, each tube is operable, and the process flow in each tube can be varied with an acceptable known thermal coupling between the tubes. In the embodiment of FIG. 10, the refractory can be constructed from laminated cast blocks provided to integrate the input fuel gas and flue gas distribution systems of the module, and a flameless burner is shown. The cast blocks are designed to minimize the mass of the refractory and the cost of construction and replacement. In this embodiment, each tube is equipped with its own preheating and post-treatment system to minimize the transport of high-temperature gases and powders. The embodiment of FIG. 10 is a schematic diagram of a reactor module 102 of four direct separation reactors 1, 2, 3, 4 integrated with a refractory 103. This system is based on the concept that the transport of low-temperature powders and low-temperature gas vapors is a known technology, and the cost and challenges can be reduced by minimizing these process flows to the lowest temperature. In this embodiment, ambient powder 104, a gaseous fuel source 105, and ambient air 106 are introduced.The direct separation reactor is based on the embodiment of FIG. 1 and the combustor of FIG. 9. Thus, the input powder is conveyed by the low-temperature powder conveyor 107 from the hopper 104 to each reactor through separate lines to each stage 1 preheater PH1-1,2,3,4, and from each direct separation reactor segment DS-1,2,3,4 to the process CO. 2 108 is cooled, and the central CO 2 is sent to the clean-up / compression system 109. The flue gas 110 from the reactor combustor is recovered with the inflowing air stream and then led to the post-combustion capture plant 111 to produce the combustion CO 2 stream 112 (which is then compressed), and the flue gas. In the case of the production of cement powder, the high-temperature powder stream from each reactor can be transferred to the rotary kiln by the air slide described in the embodiment of FIG. 11 below.

[0113] Using several modules as shown in FIG. 10, further scale-up can be achieved. The advantage of this approach is that tubes that may become inoperable can be replaced while other tubes can continue to operate, and such tubes can be test-run and their operation optimized at each stage of preheating, firing, and cooling to supply a fired product that meets the specifications.

[0114] Auxiliary devices used for preheating and post-treatment of powders and gas vapors may gain the advantages of scale-up by scaling up to a single module. Such an approach requires the distribution of high-temperature gases and powders, and there are numerous approaches that can be used to achieve the advantages of such scaling. Such a system is shown in FIG. 11. The four-tube module has a single preheater stack and uses a 1:4 L-valve distribution system with a control function that can supply any number of tubes, so that the preheated powder is evenly distributed to the tubes; the fired powder stream is collected using a 4:1 heated air slide system with a similar control; the high-temperature CO 2 stream is for post-treatment and compression to a single CO 2are combined to obtain steam. Such heat recovery systems are known to scale up from the use of suspension cyclones in cement factories. In this embodiment, the combined CO 2 flow is used to preheat the powder in the first stage of the cyclone stack. When manufacturing cement, a hot air slide supplies the high-temperature calcined powder to a single rotary kiln (not shown). The embodiment of FIG. 11 is a schematic diagram of a system using a reactor module 111 of four direct separation reactors 1, 2, 3, 4 integrated into a refractory 113. The transportation of high-temperature powder and high-temperature gas steam in this system is a known technology, and the high costs and challenges associated with these elements are offset by using large-scale preheaters and coolers, rather than the embodiment of FIG. 10 where each reactor requires a separate system, based on the concept. In this embodiment, preheated powder 114, a gaseous fuel source 115, and ambient air 116 are introduced. The direct separation reactor is based on the embodiment of FIG. 1 and the combustor of FIG. 9. In the case of high-temperature powder, the means for controlling the flow rate to each tube is to use an L-valve fluidized bed 117 fluidized by hot air 118, and each heat loss in each conveyor tube is minimized by the refractory tube. The conveyor system for the preheated powder for each tube is steeply inclined in the case of air to avoid salting out. Each reactor DS1, DS2, DS3, DS4 generates a high-temperature process CO 2 flow, which is the high-temperature CO 2 flow 119 and the high-temperature flue gas flow 120 are aggregated and transported through a pipe (not shown) coated with refractory to a central preheater for the powder. The calcined powder flows Cal1, Cal2, Cal3, Cal4 from each tube are transported by a system of tubes, and as an example, the transportation is achieved by an inclined hot air slide 121 surrounded by refractory. The aggregated high-temperature calcined material 122 is generally injected into a powder cooling system (not shown) or, in the case of cement production, into a rotary kiln system.

[0115] Although the present invention has been described with reference to specific examples, it will be understood by those skilled in the art that the present invention can be embodied in many other forms while following the broad principles and spirit of the invention described herein.

[0116] The present invention and the described preferred embodiments specifically include at least one feature that is industrially applicable.

Claims

1. 1. A system for sintering powdered materials comprising a plurality of vertical reactor tubes, The falling powder is heated around the heating zone by radiation from the external heating wall of the reactor tube, the calcination process of the powder can be a reaction that releases gas or induces a phase change, the average velocity of the falling powder particles while passing through the reactor tube is less than or equal to 1.0 m / s, and the powder material flux in each tube is preferably 0.5-1 kg m －２ ・s －１ and the length of the heating zone ranges from 10 to 35 m.

2. 2. The system of claim 1, wherein the powder material comprises a compound or mineral that releases a gas when heated, the gas being at least one selected from the group of carbon dioxide, steam, an acid gas such as hydrogen chloride, and an alkaline gas such as ammonia.

3. The system of claim 2 , wherein the mineral is limestone or dolomite.

4. 4. The system of claim 3, wherein the compound comprises silica and clay and the powder material is raw cement powder for the production of Portland cement.

5. 10. The system of claim 1, wherein the particle volume distribution of the powder material is limited to 90% less than 250 μm in diameter and 10% greater than 0.1 μm.

6. 10. The system of claim 1, wherein the evolved gas flows upwardly in the tube against the flow of the calcined powder, the gas being exhausted at the top of the system.

7. 10. The system of claim 1, wherein the released gases and the gases introduced into the system flow downwardly within the reactor tube along with the flow of calcined powder, and the gases are exhausted at the bottom of the system.

8. 2. The system of claim 1, wherein an inner tube is disposed within each tube, the powdered material flows downwards in the reaction ring together with the discharged gas, and at the bottom of the reactor, the gas flow reverses and flows upwards through the inner tube, and the discharged gas and the gas introduced into the system are discharged at the top of the system.

9. A system according to any one of claims 6 to 8, wherein powdered material entrained in the exhausted gas is separated and re-injected into the system.

10. A system according to any one of claims 6 to 9, wherein the injected powder is preheated in a gas-powder preheater system before being injected into the system.

11. 11. The system of claim 10, wherein the gas-powder preheater system is one or more refractory heating tubes through which the cold powder material falls through and is heated by the hot ascending gas, and the average velocity of the powder while passing through the preheat tubes is 0.5 m / sec or less.

12. A system according to any one of claims 6 to 9, wherein the powder discharged from the bottom of the system is cooled in a gas-powder cooling system.

13. 13. The system of claim 12, wherein the gas-powder cooling system is one or more refractory cooling tubes through which the hot powder material falls through a cooler rising gas, and the average velocity of the powder while passing through the cooling tubes is 0.5 m / sec or less.

14. 10. The system of claim 1, wherein the external heating system for externally heating the walls of the tubes is an integrated combustor and furnace system that allows for control of the temperature profile below the heating zone of the system.

15. 15. The system of claim 14, wherein the external heating system is a flameless combustion system that allows for control of the temperature profile below the heating zone of the system.

16. 16. The system of claim 14 or 15, wherein the fuel of the external heating system is at least one gas selected from the group of natural gas, syngas, town gas, producer gas, and hydrogen, and the combustion gas is air, oxygen, or a mixture thereof heated from a flue gas of the external heating system.

17. CO in flue gas ２ However, after regeneration combustion, ２ 17. The system of any one of claims 14 to 16, wherein the extraction is performed using a capture system, the system being at least one selected from the group consisting of an amine sorbent system, a bicarbonate sorbent system, and a calcium looping system.

18. 10. The system of claim 1, wherein the external heating system is an electric furnace and power is generated from a hot gas stream or extracted from a grid within a production plant of which the system is a part, and configured to enable control of a temperature profile below a heating zone of the system.

19. 20. The system of claim 1, wherein the external heating system is a combination of any one of the external heating systems of claims 14, 15 and 18, which may be applied to different segments of each tube or to different tubes, and operation of the system allows for the use of variable combinations of such external heating systems while maintaining continuous production of fired material.

20. 10. The system of claim 1, wherein the powdered material is injected into the reactor tube at several depths.

21. 10. The system of claim 1, wherein each tube is divided into a plurality of segments mounted in series, and gas released or introduced at each segment is withdrawn from that segment using a gas block between the segments.

22. 22. The system of claim 21, wherein the partial pressure of the gas released during firing in the upper segment can be lowered in the lower segment such that the reaction proceeds further by partial pressure drop to achieve a new equilibrium at a lower partial pressure, which includes a drop in the wall temperature of the lower segment such that thermal energy stored in the partially fired powder from the upper segment is used for firing.

23. 22. The system of claim 21, wherein the wall temperature of each segment is increased in each segment starting from the top segment so that the gas released from each segment is a specific gas of a desired purity, and other gases may be added to each segment to promote catalytic reactions of the reaction process and / or sintering of materials during the reaction process.

24. 24. The system of claim 23, wherein the system produces sintered MgO for refractory blocks from magnesite.

25. The system converts limestone or magnesite into Ca(OH) ２ , or Mg(OH) ２ The system of claim 23,

26. 24. The system of claim 23, wherein the system controls the oxidation state of the battery precursor.

27. 2. The system of claim 1, wherein each tube is divided into several segments, the gas discharged or introduced in each segment is extracted from that segment using gas blocks between the segments, and a hot gas flow is introduced into the segment to increase the thermal energy of the gas and particles in that segment to augment the thermal energy provided by the external heating.

28. 28. The system of claim 27, wherein the gas flow includes a combustible fuel and oxygen or air for combustion to induce combustion in that segment and increase the thermal energy of the gases and particles in that segment to augment the thermal energy provided by external heating in that segment or other segments.

29. 28. The system of claim 27, wherein the temperature increase from the combustion is sufficient to induce particle-particle or interparticle reactions typical of torrefaction or clinkering reactions that occur subsequently in a powder bed formed at the bottom of the segment, and the energy released from the exothermic reaction is capable of maintaining or increasing the temperature of the powder bed such that the induced reactions are fully completed during the residence time in the powder bed.

30. 11. The system of claim 10, wherein the preheat temperature of the gas-powder preheater system is in the range of 650-800°C and the partial pressure of the gas released during calcination is less than 15 kPa, so that the powder material is partially calcined and then sintered such that the surface energy of the particles is sufficiently reduced, thereby reducing the tendency of the particles to subsequently bond and agglomerate.

31. The material is limestone, the calcined material or a mixture of the calcined material and other minerals is introduced into a post-processing system to produce granules of the material, the granules are formed by agitating the powder, the gas environment includes carbon dioxide, and the temperature of the granulator system is adjusted to a temperature below that of the limestone and CO ２ The system of claim 1, wherein the temperature is in the range of 650 to 800°C at which recombination with the metal is suppressed.

32. 10. The system of claim 1, wherein the material is first calcined in a first segment using a steel reactor wall to supply heat to the system, and gases released or introduced in each segment are extracted from that segment using a gas block between the first segment and the lower segment, so that a second gas flow of a different gas is injected into the second segment and heat transfer through the reactor wall of the second segment is controlled so that the calcined powder from the first segment reacts with the gas to produce new material compounds.

33. The powder material is limestone CaCO ３ , or dolomite CaCO ３ MgCO ３ and the calcination product from the first segment is lime CaO or dolomite CaO.MgO, and the exhaust gas is CO ２ and the gas injected into the second segment is steam H ２ 33. The system of claim 32, wherein the temperature is controlled by removing heat through the wall as slaked lime is discharged from the second segment, and the diameter of the tubes in the system is selected to balance heat transfer and reaction rate with residence time at the minimum segment length.

34. The slaked lime or dry lime product is CO in the ambient air. ２ It has high reactivity with CaCO ３ Or MgCO ３ CaCO ３ and this product is converted to CO from ambient air in a circulation system. ２ This product is then reintroduced into the system to remove CO2 from the combustion ２ 34. The system of claim 33, wherein when involving capture of carbon dioxide, the system produces carbon negative emissions products.

35. 10. The system of claim 1, wherein the reactor tube is vibrated to remove buildup of solid material adhering to the walls of the system.

36. 13. The system of claim 1, wherein heat from an external heating system to each tube is isolated by a refractory wall so that the plant can efficiently operate with any number of tubes through the use of refractory materials and energy distribution including gas and radiation, whereby exposure of any tube to radiation and convective transfer of heat is controlled such that the temperature profile is controlled within a desired range related to thermal stresses in the metal tubes and energy consumption by the system.

37. 37. The system of claim 36, wherein the preheater segment and / or the cooler segment require distribution of preheated material from a central preheater to each tube, the distribution being achieved by at least one of the group consisting of L-valves, an assembly of L-valves designed to provide controlled distribution of powder to each tube, an agglomeration system that collects hot calcined material from each tube to a central cooling system, and a central downstream processing system such as a kiln, and the agglomeration is achieved by a system of gas slides where the flow of hot calcined powder is controlled to provide a continuous flow of material.

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