Process and method for the calcination of materials

Abstract

A system for calcining powder materials includes multiple vertical reactor tubes, wherein falling powder is heated in and around a heating zone by radiation from the external heating walls of the reactor tubes, wherein the calcination process of the powder can be a gas-releasing reaction or a reaction that induces a phase change; wherein the average velocity of the falling powder particles during their passage through the reaction tubes is 1.0 m / s or less; and the powder material flow rate per tube is preferably 0.5–1 kg m³. ‑2 s ‑1 Within the range, and the length of the heating zone is in the range of 10-35m.

Description

[0001] This invention broadly relates to methods for calcining materials in a continuous process, wherein the calcination described herein is achieved through a reaction or phase transition induced by heating the material, or both.

[0002] Numerous methods for calcining materials have been developed, and these methods are designed to process specific materials using specific fuels. The disclosure of this invention relates to a rapid calcination method, known as flash calcination, which uses indirect heating to provide energy for the reaction of powdered materials.

[0003] Most existing technologies for calcination use combustion gases to directly heat the material, while indirect heating transfers heat from the reactor wall, typically through radiative heat transfer from steel pipes of an external burner. Indirect heating methods generally have three applications: (a) producing calcined materials with higher reactivity than direct heating due to shorter residence times and reduced internal sintering through reactor temperature control; and / or (b) separating the combustion and reaction processes to prevent contamination of the calcined products by combustion impurities; and / or (c) separating the gases from both the combustion and reaction processes to allow for controlled reactions, such as by controlling the oxidation state; and / or (d) treating carbonate materials that release CO2 during the calcination reaction to produce oxides, which enables the capture of process CO2 gases as a pure gas stream.

[0004] Regarding CO2 capture, such calcination processes have two emission sources. The first source is CO2 released from the combustion of carbon-based fuels, referred to here as "combustion CO2," and the second source is "process CO2" generated during the reaction, typically from carbonate materials. Low-emission calcination processes aim to reduce CO2 from both combustion and process. In life cycle analysis, using renewable energy or low-emission intensity electricity is one means of reducing fuel-end CO2 emissions. Global efforts to reduce emissions are expected to be such that calcined products can be judged by their emission intensity, measured in tons of CO2 emitted per tonne of product (including fuel and process CO2). There is a need to reduce the emission intensity of products produced through calcination processes.

[0005] There are many established methods for reducing CO2 emissions from combustion. One method is to use “renewable electricity” generated by wind, solar, or other processes to indirectly heat the calcining furnace. The cost of producing renewable energy is rapidly decreasing, and commodity products may become affordable. Other methods use low-emission combustion processes. One approach is to use non-carbon-based fuels, such as hydrogen, derived from the “electrolysis” of water, or from carbon-based fuels that have undergone “pre-combustion” capture treatment to remove CO2. Another approach is to treat the flue gas from the combustion of carbon-based fuels with adsorbents such as amines, carbonates, metal oxides, and hydrotalcite in a process called “post-combustion capture” to remove CO2. Yet another approach is to use oxygen instead of air to burn carbon-based fuels in a process called “oxygen-enriched combustion” to produce flue gas containing a large amount of easily captured CO2. It will be apparent to those skilled in the art that combustion emissions from calcination can be reduced by using renewable electricity, or electrolysis, or pre-combustion capture, or post-combustion capture, or oxy-enriched combustion, or a combination of these. In most calcination processes that use combustion gases, hot flue gas directly transfers energy to the materials through direct heating. Therefore, any process emissions are mixed with the flue gas, and any extraction of process CO2 increases the cost and complexity of reducing process emissions. Indirect heating, on the other hand, not only captures CO2 from the process as pure gaseous vapor, but also provides flexibility in emission reduction, as any of the aforementioned low-emission methods can be used to provide heat.

[0006] The substances emitted during calcination are carbonates, such as limestone (CaCO3), dolomite (MgCO3·CaCO3), and magnesite (MgCO3); mineral mixtures, such as raw cement powder used in the production of Portland cement, where the carbonate minerals may include impure limestone, such as marl, and other mixed metallic carbonates, including siderite, FeCO3, and synthetic carbonate compounds produced for the manufacture of specific oxide materials, including, for example, manganese carbonate (MnCO3) produced as an intermediate in the production of metals and battery materials; and organic matter that decomposes to produce CO2. Various materials undergo calcination for various industrial purposes, generating process CO2.

[0007] Capturing either process CO2 or combustion CO2 emissions is necessary, ideally both, to reduce emissions from material calcination and thus mitigate climate change. For example, the cement industry is seeking to reduce CO2 emissions from limestone calcination through a variety of methods, including using biomass, waste, and renewable electricity as fuel, and various CO2 capture methods, including amine capture, oxy-fuel combustion, calcium cycling, and the direct separation process described herein. The most ideal solution for emission reduction is to achieve CO2 capture at the lowest possible cost, measured in dollars per tonne of CO2 emissions avoided. In many proposed capture processes, CO2 capture is costly due to the need for novel chemical and physical processes, such as amine capture and oxy-fuel combustion. In calcium cycling, high-quality flow rates and energy recovery are obstacles to its use. A common theme of these processes is that their introduction increases complexity and cost. Another alternative approach, direct separation, provides process CO2 capture without additional energy loss or the use of new materials, as described by Sceats et al. in WO2015 / 077818 "Process and apparatus for the manufacture of Portland cement" and its references. In this approach, indirect heating of the calcining furnace is used to process the carbonate minerals, with the process gas stream being process CO2 and minor impurities arising from the volatilization of minor components. Sceats et al. in WO2016 / 077863 "Manufacturing process and apparatus for the production of calcined compounds of calcined products" and its references describe a general method for calcining carbonate materials using indirect heating, where the indirect heating process is extended to use different materials and multiple reactor sections, including an electric section.

[0008] It is worth noting that the inventions related to direct separation reactors described in WO2015 / 077818 and WO2016 / 0778633 and their references are indirect heating flash calcination processes, where the calcination time typically ranges from 10 to 50 seconds. WO2015 / 077818 and WO2016 / 077863 and their references generally include a requirement that the input particle size is typically less than about 100 micrometers so that the degree of calcination (defined herein as the proportion of carbonates converted to oxides in the reactor within this residence time) is sufficient for the application of the calcined product. In direct separation reactors, one variable controlling the calcination process is the wall temperature distribution; therefore, the residence time and the average wall temperature are typically considered key variables in reactor design. In direct separation reactors, particles preferably flow downwards under gravity, and the residence time is related to the terminal velocity of the particle size distribution (PSD), where the acceleration of the particles falling under gravity is balanced by gas-particle friction, which depends on the direction of the airflow.

[0009] Regarding the residence time and temperature of the reactor, generally speaking, the degree of calcination of the material is preferably at least 95%, or most preferably at least 97% or higher. However, in the case of cement powder, it may be lower, around 85%, because subsequent curing processes may require endothermic loads, for example, when a rotary kiln is used for clinker production. A direct separation method is needed where the residence time and temperature in the reactor section can be controlled to achieve the desired degree of calcination of the material. The invention disclosed herein relates in part to increasing the residence time and temperature of a direct separation reactor.

[0010] Regarding PSD, it is useful to define three numbers from the measured cumulative volume distribution, namely d 10 It is 10% by volume that the particles are smaller than d 10 The diameter, d 50 It is 50% less than d 50 The diameter, d 90 It is 90% less than d 90 The diameter. Calcined powders of carbonate materials have many applications, among which d is the most preferred. 50 Sizes larger than approximately 100 micrometers have been described in the prior art. Specifically, products cover sizes from approximately 0.1 to 300 micrometers. 10 to d 90 The scope, within which each product has a specified PSD.

[0011] d 50 Powder materials larger than 100 micrometers have a higher density than d. 50 Smaller, lower-grade materials are easier to handle, and these products are typically used in specific powder applications. It is necessary to expand direct separation technology to enable the production of such powder materials to reach this level.

[0012] In other applications, there is a need for materials in granular form with millimeter-sized dimensions, and preferably granular mixed materials, particularly in mineral processing where such products are not intended to be entrained in airflows. Examples include slag formation for the production of metals such as iron, aluminum, and magnesium; cement manufacturing, where clinker is formed through reaction between bound particles in subsequent clinker-forming steps; and applications in refractory products where agglomerates are formed before sintering. It is necessary to expand direct separation technologies to enable the production of such granular materials, including integrating direct separation technologies into the production of granular products.

[0013] Those skilled in the art will understand that the PSD of calcined materials varies considerably for many applications. Specifically, there is a need to reduce emissions from the production of such products, thus requiring the application of direct separation reactors to process carbonate materials of various particle sizes. Larger particles descend faster in direct separation reactors than smaller particles, resulting in a reduced residence time for larger particles compared to smaller particles. In some cases, extending the length of the direct separator reactor may be feasible, as described in the prior art cited above, to achieve the desired degree of calcination. However, a more compact direct separation reactor is generally preferred. The invention disclosed herein may relate to a calcination process capable of handling larger particles than those disclosed to date for use in direct separation reactors.

[0014] The direct separation reactors described in WO2015 / 077818 and WO2016 / 077863 are described as single-tube reactors, with input materials typically at 8-10 tons per hour. For large-scale manufacturing processes such as cement, scaling up the reactor to approximately 200 tons per hour is desirable. It is necessary to adapt the direct separation reactor to this scale in order to provide the benefits of the process for batch production.

[0015] While the present invention is primarily aimed at reducing CO2 emissions during the calcination of carbonate materials, particularly limestone and cement raw materials, it can be applied to the calcination of other materials where the reaction may involve a phase change or the release of gases other than CO2. Examples of such calcination processes include the removal of moisture, the volatilization of sulfur compounds, ammonia, and acidic gases such as HCl via the generation of steam.

[0016] The project for which this application was submitted has been funded by the EU Horizon 2020 Research and Innovation Programme, pursuant to funding agreements Nos. 654465 and 884170. Background Technology

[0017] The invention described herein is primarily derived from observation and understanding of calcining materials containing calcium carbonate (CaCO3) in a direct separation reactor to produce lime (CaO). The invention described herein can be considered an improvement upon WO2015 / 077818 and WO2016 / 077863 and their references for processing such materials. Furthermore, the disclosed invention can be applied to direct separation reactors to scale up processes, facilitate the integration of direct separation reactors into industrial processes, and process other materials in direct separation reactors for any purpose.

[0018] Those skilled in the art will understand that the treatment of calcium carbonate-containing materials, including limestone, dolomite, and cement powder, imparts a "sticky" quality to freshly calcined lime particles. Early literature on this property comes from historical documents on lime burners, the consequences of which have influenced the design of modern production processes for large-scale CaO production. A wealth of literature exists on this subject, summarized below.

[0019] The viscosity of lime is related to the formation of particle agglomerates, the formation of cold surface deposits, the viscosity of the material bed, and the challenges of product transport. The physical source of this viscosity is related to the high surface energy of CaO produced in the calcination reaction front that penetrates the particles. Without theoretical constraints, the CaO particles produced by the calcination reaction have a size of 20 nm and a surface area greater than 100 m². 2 / g. These small grains possess high surface energy, which spontaneously decreases during the high-temperature sintering process. The grains grow to greater than 100 nm through a process called Ostwald ripening, caused by the formation of sintering necks between adjacent CaO grains. CaO then diffuses through these sintering necks, thus smaller grains are absorbed into larger grains. As the grain size increases, the grain coarsening process reduces the surface energy. From the perspective of intergranular porosity, there is a transfer of pores from mesopores of 5-10 nm to macropores greater than 100 nm. The literature describes this sintering through a series of mechanisms by which the sintering rate increases not only with increasing temperature but also with increasing partial pressures of CO2 and H2O, as sintering is catalyzed by these gases. Catalysis allows CaO to migrate rapidly on a micrometer-scale. CaO diffusion is important for processes such as ceramics and cement manufacturing, mineral slagging, and its impact on flash calcination, as described below.

[0020] The source of this type of "stickiness" in lime particles is that sintering necks also grow between colliding particles, or particles adhere to surfaces, or accumulate in the bed to reduce surface energy. The physical sintering process of intragranular grains is no different from the adhesion of particles in physical contact. In the literature on ceramics, cement, and slagging processes, the term "sintering" applies to processes both within and between particles. In this invention, a related aspect of stickiness is the "agglomeration" process, in which particles adhere to a significantly different degree during calcination than to individual particles through agglomerate treatment in the reactor, and further, a "cascade agglomeration" process of agglomerate adhesion occurs. Without being theoretically limited, it can be understood that (a) agglomerates are formed by particle-particle collisions within particle clusters generated in a direct separation reactor to minimize gas-particle friction, and (b) agglomerates are more likely to form when there is stronger gas-particle turbulence, which increases the collision rate between particles within the cluster, (c) the adhesion strength and its persistence are a result of the sintering process, and (d) the persistence of agglomerates can have a significant impact on the calcination process.

[0021] In relation to direct separation reactors, existing techniques for CaO sintering also describe catalytic sintering of CaO via CO2, where the initial sintering phase occurs within 30 seconds at temperatures above approximately 800°C and CO2 partial pressures above approximately 5 kPa. Since this sintering time is comparable to the 10–50 seconds residence time typically used in direct separation reactors, where CO2 partial pressures are approximately 100 kPa and temperatures are approximately 900°C, it is reasonable to expect that any CaO produced in such direct separation reactors will be sintered to achieve a concentration below approximately 20 m³. 2 / g surface area. This has been confirmed in direct separation reactors. Since sintering occurs during the residence time of particles in the reactor, the "stickiness" effect between particles can be expected to be significant and may affect the performance of the direct separation reactor when processing materials that produce CaO in the presence of CO2. The focus of this disclosure is an invention that mitigates adverse effects or utilizes these effects to produce new materials.

[0022] One object of the present invention may be to provide one or more methods for optimizing the design of a direct separator tubular reactor to control the effect of lime viscosity.

[0023] Another object of the present invention may be to provide a method for scaling up a direct separation reactor to a greater production capacity.

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

[0025] Another object of the present invention is to apply these inventions to the processing of other materials, in which the benefits are to simplify the process in terms of operation and complexity, or to improve the properties of the materials.

[0026] Any discussion of prior art throughout the specification should not be construed as an admission that such prior art is widely known or constitutes part of common general knowledge in the art. Invention Overview

[0028] The invention in this patent is generally related to improvements in direct separation technology.

[0029] (a) Such inventions include systems for calcining powdered materials, said systems comprising one or more reactor tubes, wherein falling powder is primarily heated by radiation from external heated walls of the reactor tubes, wherein the calcination process of the powder can be a reaction that releases gases or induces a phase change or both; the average velocity of the powder through the reactor is 1.0 m / s or less; preferably less than 0.2 m / s; the powder material flow rate per tube is preferably 0.5-1 kg m³. -2 s -1Within the range, and the length of the heating zone is in the range of 10-35m.

[0030] (b) A method for treating larger particles larger than 100 pm using a countercurrent process of particles and gas;

[0031] (c) A method of reducing agglomeration and aggregation by using the co-flow of particles and gas to reduce gas particle turbulence;

[0032] (d) A method for cooling the calcined particle stream from a direct separation reactor and heating the surrounding particle stream, for injecting particles into the direct separation reactor using a countercurrent pipe system, wherein, for lime, when the particles are injected into the direct separation reactor, a preheating system is used to partially calcine and passivate the particles to inhibit particle agglomeration and scaling.

[0033] (e) Effective methods for externally heating reactor walls, using tightly integrated burner sections, flameless burners using various fuels, and electric heating, and in the case of carbon-based fuels, using post-combustion processes to capture CO2 to minimize energy consumption and CO2 emissions.

[0034] (f) Using segmented pipes to achieve (i) optimizing process energy consumption by switching process gas pressures, (ii) injecting hot gas and fuel / air, and (iii) producing products by an optimized chemical reaction sequence, such as producing Ca(OH)2 from CaCO3.

[0035] (g) A method for thermally granulating lime using the adhesive force of CaO in CO2, including mixing lime with other minerals so that the granules can be used in industrial processes that require slagging or slagging, such as the production of iron and aluminum from CaO and the production of magnesium metal from dolomite MgO·CaO.

[0036] (h) A method for expanding the process using multiple tubes.

[0037] Problems to be solved

[0038] The first problem to be solved is optimizing the direct separation reactor for processing materials that produce CaO particles, especially CaO particles produced in the presence of CO2.

[0039] The second problem to be solved is optimizing the direct separation reactor to scale up the process to a larger production volume.

[0040] The third problem to be solved is integrating direct separation reactors into many industrial processes.

[0041] The fourth problem to be solved is to improve the direct separation reactor for calcining various materials.

[0042] Problem Solving Methods

[0043] In a first aspect of the invention, various measures are described to reduce the formation of CaO-induced particle agglomerates in a direct separation reactor, reduce fouling on metal surfaces through which heat transfer occurs, and reduce the tendency of the particle bed to resist fluidized transport. Three solutions are described: the first solution is capable of handling larger CaO particles to take advantage of the observation that agglomerates are reduced when larger particles are calcined; the second solution reduces CaO particle agglomeration by minimizing the collision frequency between particles; and the third solution reduces the tendency of such CaO particles to adhere during collisions.

[0044] In a second aspect of the invention, a method for promoting the agglomeration of CaO particles produced in a direct separation reactor is described, the direct separation reactor using the invention described in the first aspect to manufacture products requiring granular materials for subsequent processes, including the production of Portland cement from calcined cement powder produced in the direct separation reactor; the production of magnesium metal from dolomite MgO·CaO produced from the direct separation reactor using the Pidgeon process; and the production of low-emission lime particles produced in the direct separation reactor for injection into slagging processes used in steel and aluminum production to remove impurities such as silicates.

[0045] In a third aspect of the invention, various measures for integrating a direct separation reactor into an industrial process are described. These measures include using waste heat to preheat the input powder, injecting the powder into the reactor, providing heat to the reactor walls, extracting the process gas stream from the reactor, minimizing the loss of solids in the exhaust gas, and cooling the product. A key requirement in this aspect is to provide measures that minimize the energy required to process the material, typically provided under ambient conditions, and to deliver the powder product and exhaust gas stream with preferably minimal energy consumption under desired conditions.

[0046] In a fourth aspect of the invention, various measures are described that enable the scaling up of production capacity using a direct separation reactor. The diameter of the tubes in a direct separation reactor is reasonably limited due to the penetration depth of radiation into the particle and gas mixture. Therefore, scaling up production capacity is primarily achieved through tube arrays. Measures for scaling up include devices for distributing preheated solids into multiple tubes, devices for heating powders in separate tubes within a furnace from the burner, and devices for concentrating the powder and gas streams from the reactor tubes for subsequent processing. A primary need in this regard is to provide measures that minimize the energy required to process the material, typically under ambient conditions, and, under desired conditions, to deliver the powder product and exhaust gas streams with preferably minimal energy consumption to achieve economies of scale.

[0047] In a fifth aspect of the invention, specific process steps are proposed to facilitate the integration of direct separation reactors into the manufacturing process, primarily for the production of cement clinker.

[0048] In a sixth aspect of the invention, a system for calcining powder materials may be provided, the system comprising a plurality of vertical reactor tubes, wherein falling powder is heated in and around a heating zone by radiation from an external heating wall of the reactor tubes, wherein the calcination process of the powder may be a reaction that releases gases or induces a phase change; wherein the average velocity of the falling powder particles during their passage through the reactor tubes is 1.0 m / s or less; and the powder material flow rate per tube is preferably 0.5-1 kg m³. -2 s -1 Within the range, and the length of the heating zone is in the range of 10-35m.

[0049] Preferably, the powder material includes a compound or mineral that releases gas when heated, wherein the gas is at least one selected from the group consisting of carbon dioxide, vapor, acidic gases such as hydrogen chloride, and alkaline gases such as ammonia.

[0050] Preferably, the mineral is limestone or dolomite.

[0051] Preferably, the compound comprises silica and clay, such that the powder material is raw cement powder used to manufacture silicate cement.

[0052] Preferably, the particle volume distribution of the powder material is limited to 90% having a diameter less than 250 μm and 10% having a diameter greater than 0.1 μm.

[0053] Preferably, the released gas flows upward in the tube against the flow of the calcined powder, and the gas is discharged at the top of the system.

[0054] Preferably, the released gas and any gas introduced into the system flow downward in the reactor tube along with the flow of the calcined powder, and the gas is discharged at the bottom of the system.

[0055] Preferably, each tube is provided with an inner tube, and the powder material flows downward in the reaction ring with the released gas; and wherein, at the bottom of the reactor, the gas flow flows upward in the opposite direction through the inner tube, and the released gas and any gas introduced into the system are discharged at the top of the system.

[0056] Preferably, the powder material entrained in the exhaust gas is separated and reinjected into the system.

[0057] Preferably, the injected powder is preheated in a gas-powder preheater system before being injected into the injection system.

[0058] Preferably, the gas-powder preheater system consists of one or more refractory heating tubes in which cold powder material falls through hot rising gas and is heated by the rising gas, wherein the average velocity of the powder during its passage through the preheater tube is 0.5 m / s or less.

[0059] Preferably, the powder discharged from the bottom of the system is cooled in a gas-powder cooling system.

[0060] Preferably, the gas-powder cooling system is one or more refractory cooling tubes in which hot powder material falls through cooled rising gas, wherein the average velocity of the powder during its passage through the cooling tube is 0.5 m / s or less.

[0061] Preferably, the external heating system for externally heating the wall of the tube is an integrated burner and furnace system that can control the temperature profile below the heating zone of the system.

[0062] Preferably, the external heating system is a flameless combustion system, which can control the temperature distribution below the heating zone of the system.

[0063] Preferably, the fuel for the external heating system is at least one gas selected from the group consisting of natural gas, syngas, town gas, producer gas, and hydrogen; wherein the combustion gas is air, oxygen, or a mixture thereof obtained by heating the flue gas from the external heating system.

[0064] Preferably, a regenerative post-combustion CO2 capture system is used to extract CO2 from the flue gas, the regenerative post-combustion CO2 capture system being selected from at least one of the following: amine adsorbent system, bicarbonate adsorbent system, and calcium recycling system.

[0065] Preferably, the external heating system is an electric furnace, wherein the electricity is generated by hot gas flow in the production apparatus (of which the system is part) or drawn from the power grid, and is configured to control the temperature distribution of the system heating zone.

[0066] Preferably, the external heating system is a combination of the external heating systems of any one of claims 14, 15 or 18, which can be applied to different sections of each tube or different tubes, and the system can be operated using variable combinations of such external heating systems while maintaining continuous production of calcined materials.

[0067] Preferably, the powder material is injected into the reactor tube at multiple depths.

[0068] Preferably, each pipe is divided into multiple segments installed in series, wherein the gas released or introduced in each segment is extracted from that segment using a gas block between the segments.

[0069] Preferably, the partial pressure of the gas released during the higher-stage calcination process can be reduced in the lower stage, allowing the reaction to proceed further by the decrease in partial pressure, thereby reaching a new equilibrium at a lower partial pressure. This includes reducing the wall temperature of the lower stage so that any thermal energy stored in the powder partially calcined from the higher stage can be used for calcination.

[0070] Preferably, the wall temperature of each segment increases sequentially from the top segment in each segment, such that the gas released from each segment can be a specific gas of the desired purity, and other gases can be added to each segment to promote the catalysis of the reaction steps and / or the sintering of the material during the reaction steps.

[0071] Preferably, the system prepares sintered MgO for refractory bricks from magnesite.

[0072] Preferably, the system produces Ca(OH)2 or Mg(OH)2 from limestone or magnesite.

[0073] Preferably, the system controls the oxidation state of the battery precursor.

[0074] Preferably, each pipe is divided into multiple sections, wherein the gas released or introduced in each section is extracted from the section using a gas block between the sections, and a hot gas flow is introduced into the section to increase the thermal energy of the gas and particles in the section, thereby increasing the thermal energy provided by external heating.

[0075] Preferably, the airflow contains combustible fuel and oxygen or air for combustion to initiate combustion in the section, thereby increasing the thermal energy of the gas and particles in the section, and thus increasing the thermal energy provided by external heating in the section or other sections.

[0076] Preferably, the temperature rise caused by combustion is sufficient to initiate particle-particle or intraparticle reactions, typically roasting or aging reactions, which subsequently occur in the powder bed formed at the bottom of the section, wherein the energy released from the exothermic reaction can maintain or increase the temperature of the powder bed, allowing the initiated reaction to be fully completed within the residence time in the powder bed.

[0077] Preferably, the preheating temperature of the gas-powder preheater system is 650-800℃, and the partial pressure of the gas released during calcination is below 15kPa, so that the powder material is partially calcined and then sintered, which fully reduces the surface energy of the particles and reduces the tendency of the particles to subsequently combine and agglomerate.

[0078] Preferably, the material is limestone, wherein the calcined material or a mixture of calcined material and other minerals is introduced into a post-processing system to produce granules of the material, wherein the granules are formed by stirring powder, wherein the gaseous environment contains carbon dioxide, and wherein the temperature of the granulator system is 650-800°C, and the recombination of lime with CO2 is inhibited.

[0079] Preferably, the material is first calcined in a first section using a steel reactor wall to provide heat to the system, and a gas block between the first and lower sections is used to extract the gas released or introduced from each section so that a second gas flow of different gases can be injected into the second section, and heat transfer through the reactor wall in the second section is controlled, thereby causing the calcined powder from the first section to react with the gas to produce new material compounds.

[0080] Preferably, the powder material is limestone, CaCO3, or dolomite CaCO3·MgCO3, wherein the calcination product of the first stage is lime CaO or calcined dolomite CaO·MgO, the exhaust gas is CO2, the gas injected into the second stage is steam H2O, the temperature is controlled by heat dissipation through the wall, so that the quicklime is discharged from the second stage, and the diameter of the pipe in the system is selected so that the residence time allows heat transfer and reaction kinetics to be balanced with the minimum section length.

[0081] Preferably, the quicklime or calcined dolomite product is highly reactive with CO2 in ambient air to reform CaCO3 or MgCO3, and wherein the product is reintroduced into the system to remove CO2 from ambient air in a circulating system, wherein the system produces carbon-negative emission products when the product is used with renewable fuels and in conjunction with combustion CO2 capture.

[0082] Preferably, the reactor tube is vibrated to remove the buildup of solid material adhering to the system wall.

[0083] Preferably, the heat from the external heating system to each tube is separated by a refractory wall, allowing the equipment to operate efficiently with any number of tubes by using refractory materials and energy distribution (including gas and radiation), which controls the exposure of any tube to radiation and the transfer of heat to keep the temperature distribution within an ideal range related to the thermal stress of the metal tubes and the energy consumption of the system.

[0084] Preferably, the preheater section and / or cooling section require the distribution of preheated material from the central preheater to each tube, which is achieved by at least one of the following: L-valve, L-valve assembly designed to provide controlled powder distribution to each tube, a polymerizer system for the thermally calcined material from each tube to the central cooling system, and a central post-processing system, such as a kiln, wherein agglomeration is accomplished via an air chute system, wherein the flow of the thermally calcined powder is controlled to provide a continuous flow of material.

[0085] Solutions to these problems can be derived from these aspects.

[0086] Other forms of the invention will be apparent from the description and drawings.

[0087] Brief description of the attached figures

[0088] Embodiments of the invention will be better understood from the following written description, which is also apparent to those skilled in the art, by way of example only and in conjunction with the accompanying drawings, wherein:

[0089] Figure 1 This is a schematic diagram of an exemplary embodiment, in which the terminal velocity of the particles is reduced by counter-current flow of the process gas, thereby extending the residence time of large particles in the direct separation reactor. By using sufficiently large particles with low binding tendency, any adverse effects of CaO-induced particle-particle bonding can be reduced.

[0090] Figure 2 This is a schematic diagram of an exemplary embodiment of preferred calcined small particles, wherein CaO-induced particle-particle bonding is limited by using the co-flow of particles and process gas, wherein gas-particle separation occurs at the bottom of the reactor via a separator.

[0091] Figure 3 This is a schematic diagram of an exemplary embodiment of preferred calcined small particles, wherein CaO-induced particle-particle bonding is limited by the design of a direct separation reactor with a central tube, wherein the reaction occurs in a low-turbulent co-current flow of particles and gas along an annulus, the process gas is discharged through the central tube, and gas-particle separation occurs at the bottom of the reactor by reversing the gas flow direction.

[0092] Figure 4 This is a schematic diagram of an exemplary embodiment for selecting preferred calcined small particles, wherein CaO-induced particle-particle bonding ratio Figure 1-3 The design described in the paper further reduces this by performing partial pre-calcination before injection into the reactor to control agglomeration and sintering.

[0093] Figure 5 Medium powder is injected into the reactor region at multiple depths to mitigate the effects of agglomeration.

[0094] Figure 6 This is an illustrative implementation plan, in which, for Figure 1-5 In any of the direct separation reactor configurations, the discharged powder is agitated to produce agglomerates of the desired size, wherein the particles have sufficient compressive strength for a specific application.

[0095] Figure 7 This is a schematic diagram of an exemplary embodiment, in which partially calcined powder from a first reactor section is injected into a second reactor section, wherein a gas flow is injected into the second reactor section.

[0096] Figure 8 This is a schematic diagram of an exemplary embodiment for a specific application in cement clinker production, wherein powder discharged from a direct separation reactor undergoes several steps of processing, including flash heating of the powder to directly heat the falling powder and provide sufficient energy to initiate a clinker reaction for cement clinker production. The heated material at the bottom of the reactor falls into a moving bed, where an exothermic maturation reaction takes place and the bed is further heated, causing clinker to form rapidly within the bed. Other industrial applications of this general process are described.

[0097] Figure 9 yes Figure 1 An exemplary embodiment of a countercurrent direct separation reactor for limestone treatment is provided with furnace heat by a flameless regenerative combustion process; the fuel is syngas produced from biomass; CO2 is extracted from the flue gas; and heat from the product solids and process gas stream is used to preheat the powder input using a countercurrent heat exchanger. The purpose of this embodiment is to illustrate that the system can provide a high thermal efficiency with a complete process and CO2 capture during combustion, thereby providing a product with overall carbon negative emissions.

[0098] Figure 10 This is a schematic diagram of an exemplary embodiment of the direct separation reactor module, wherein... Figure 1-10 Each of the reactors is housed in a single furnace, where the radiation and convection coupling of the tubes is controlled by the use of refractory elements within the furnace, and most of the product is produced using... Figure 10 The auxiliary equipment described herein preheats and cools most of the products in each pipe.

[0099] Figure 11 This is a schematic diagram of an exemplary embodiment of the direct separation reactor module, wherein... Figure 1-11 The reactors in each of the tubes are housed in a single furnace, where the radiation and convection coupling of the tubes is controlled by the use of refractory elements within the furnace. The preheating and post-treatment of the materials are carried out using a modular-scale system, which requires the distribution of preheated and calcined powders from this modular-scale system into the tubes. Invention Details

[0101] Preferred embodiments of the invention will now be described with reference to the accompanying drawings and non-limiting examples.

[0102] Regarding the first aspect related to the reduction of CaO agglomerates, these principles have been developed based on knowledge of gas-particle hydrodynamics. In all the embodiments described below, the particles overcome gravity and flow down the direct separation reactor.

[0103] To suppress agglomerate formation, a preferred method is to increase the average particle size at a constant mass flow rate. The basic principle is that the number density of particles is significantly reduced, thus decreasing the particle-to-particle collision rate. Furthermore, the momentum of particle-to-particle collisions is sufficiently large that the resulting CaO sintering necks are not strong enough to break, causing the colliding particles to bounce rather than adhere together. Existing direct separation reactors typically assume particle sizes on the order of 20 μm, and often less than 100 μm. One objective of the invention disclosed herein is to increase the particle size to approximately 250 μm. Three factors reduce the degree of calcination achievable with such large particles. First, the residence time of the particles decreases because larger particles have higher terminal velocities; second, the adsorption of radiation by particles on the hot walls decreases due to the reduced average surface area; and third, for many low-porosity materials, the reaction front takes longer to move from the particle surface to the particle center for larger particles. One solution is to simply increase the length of the reactor, thereby increasing the residence time. However, this solution is impractical in many cases. Another solution is to increase the reactor wall temperature, resulting in a faster heat transfer rate. However, in many cases, the steel used in reactor tubes cannot withstand higher temperatures due to strength loss and accelerated corrosion mechanisms. New types of steel may mitigate this effect.

[0104] Another solution is as follows Figure 1 As shown, residence time can be reduced by using a countercurrent configuration, in which the particle terminal velocity is reduced through friction between the gas particles and the rising gas generated by the reaction. Figure 1The diagram describes a direct separator reactor with countercurrent flow, wherein powder feed 101 is injected into the reactor system via a rotary valve 102 into an injection pipe 103 and then into a reactor pipe 104. Powder 105 falling in a plume is heated to the reaction temperature by a hot rising process gas stream 106 rising from the reaction zone 107 through countercurrent gas-particle heat transfer. Cooled gas is separated from any entrained powder by a system including a separation plate 108 and tangential gas jets 109 to provide a cooled process gas stream 110. Any powder in this gas stream is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor. The heated powder 111 in the reactor falls slowly against the rising gas and enters the reaction zone 107, where it is radiated and heated by the reactor walls, generating heat within a furnace 112. This heat is generated within the furnace, which heats the steel walls 113, and flows to the gas and particles in the reactor to initiate the desired reaction. The length of the heating zone is sufficient to allow the reaction to proceed to the desired extent. The falling, calcined powder is collected in the reactor cone 114 and forms a calcined powder bed 115, which is extracted from the reactor through an exhaust valve 116, which can be a flap valve system to provide a flow 117 of calcined powder. One advantage of this configuration is that the heat transfer between the falling particles and the rising hot gas is for heating the particles, thus the process does not rely on an external heat exchanger to achieve high thermal efficiency. It is worth noting that in many cases this method may not be effective because, in principle, particles of this mass and size can easily be ejected from the reactor. However, it is well known that the slipstream of large particles exhibits strong gas vortices behind the falling particles, thus the particles tend to form clusters, thereby minimizing friction between gas particles, and thus the clusters flow downwards along the pipe against the rising gas. Furthermore, any entrained particles are reinjected into the reactor, increasing the mass of the particles accumulated in the reactor to a sufficient mass density to organize into clusters to overcome the upward-flowing gas. At high mass flow rates, particle aggregation is sufficient to allow the momentum of the clusters to be rapidly exchanged between particles, resulting in a more laminar flow state. This suppresses large-scale turbulence. An additional advantage is that fouling growth may be inhibited by the momentum of particles flowing towards the wall, thus minimizing gas-particle friction. Furthermore, it is noteworthy that no process gas is generated if no particles are injected into the reactor's heating zone. Therefore, a condition is always created where particles must flow downwards along the reactor walls. Figure 1 One effect of the configuration is that the mass flow through the reactor may pulsate, and any such effect can be controlled by the reactor and cyclone / filter settings. Figure 1Another advantage of this configuration is that the particle flow entering the bottom of the reactor is unaffected by the gas flow, and because larger particles in the reactor bed do not agglomerate as significantly as smaller particles, particle transport and conveyance from the reactor are unimpeded. It has been found that a small injection of preferably hot steam or air at the bottom can be used to control any such agglomeration. During compression using standard processes, the steam or air in the gas is condensed or removed. Preferably, these gases are less than 10% of the process gas flow, and most preferably less than 5%. This hot gas can also regulate the residence time of the powder, and if the gas is preferably steam or air, the reduction in partial pressure can increase the degree of calcination by lowering the equilibrium pressure of the calcination reaction. Furthermore, in the case of calcining carbonates, CO2 replacement at the bottom of the reactor can reduce residual particle agglomeration in the bottom bed of the reactor, promoting fluidization and reducing effects such as rat-holing.

[0105] Figure 1 Another advantage of this configuration is the lower particle-particle bond strength between larger particles, resulting in less fouling on the tube surface that limits heat transfer compared to smaller particles. Experiments show that the vertical surfaces of the tube are self-cleaning for both small and large particles, and the partial detachment of the coating surface at high temperatures indicates that the interparticle bonds are weak enough to support a thick coating; therefore, the fouling thickness is typically less than 1 mm. It was found that as the particle flux increases, the coating thickness, measured by the temperature drop between the inner steel wall and the exposed coating surface, decreases, which can be expected from the increased shear forces generated by the high momentum of the solids, leading to coating detachment. This is characteristic of all the configurations disclosed below. However, the thickness depends on the embodiment described herein, and it is understood that suppression of agglomeration is associated with a lower coating thickness.

[0106] It is worth noting that, Figure 1 This configuration is typically applicable to the calcination of materials with large particles that have little tendency to agglomerate. The longer residence time and lower powder loss due to aggregation in countercurrent flow are generally advantages. In applications where the process involves high-temperature phase change treatment, bottom gas injection can increase the residence time, and this gas can be selected as the catalytic phase change gas. An example is the processing of α-spodumene into β-spodumene for lithium extraction, where the catalyst is steam.

[0107] In many cases, it is not possible to increase the particle size of the powder input, therefore it is not possible to adopt... Figure 1The method of the illustrated embodiment. It has been observed that when small particles are injected into a direct separation reactor, the formation of CaO through calcination can be affected by several factors. These factors include increased scaling on the hot steel reactor surface, which hinders the transfer of radiative heat from the wall to the reactor body; increased flow resistance of the powder collected at the bottom of the reactor; and the formation of large agglomerates in the reactor that fall through the reactor quickly enough, thus reducing the degree of calcination. As mentioned above, all of these effects can be attributed to the stickiness of the lime produced during calcination. Large lime particles up to several millimeters in size may form; in this case, the process is called “cascading agglomeration” because agglomerates of this size are formed by the aggregation of smaller agglomerates. Under other conditions, the agglomerate size is smaller, for example, about 100-150 pm. While such conditions can be found and calcination of such agglomerates can achieve the desired degree of calcination, it is difficult to control cascading agglomeration starting from a limited number of agglomerates, and this is undesirable for quality control.

[0108] The principle of reducing agglomeration is to minimize the turbulence of gas particle flow across all length scales, because high turbulence maximizes the collision frequency between particles and particle walls, and suppressing turbulence limits the formation of agglomerates. Figure 2 and Figure 3 The implementation scheme provides an example of how aggregation can be controlled by minimizing turbulence. Figure 2 A co-current system is described, in which the process gas stream is discharged from the bottom of the reactor. Figure 3 A system is described that discharges process gas streams through a central tube, with the gas streams exiting at the top of the reactor.

[0109] exist Figure 2The diagram describes a direct separator reactor with co-current flow, in which powder feed 201 is injected into reactor tube 204 via injection pipe 203 through rotary valve 202. In a plume, falling powder 205 is heated to reaction temperature by radiation from the steel reactor wall 206 of the heated gas and particles, where heat is generated within an external furnace 207 that heats the steel wall. The heated powder 208 falls deeper into the reactor, into reaction zone 209, where it absorbs radiant heat from the wall and initiates the desired reaction. As the reaction proceeds, hot process gas 210 accelerates the particles through the reactor via co-current flow. The length of the heating zone is sufficient to allow the reaction to proceed to the desired extent. Calcinated powder 211 and hot process gas 212 are discharged from the bottom of the reactor. These gas and particle streams are separated by reactor cone 213, gas injection pipe 214, and powder bed 215, which acts as an inertial separator, forcing hot process gas vapor 216 out of the reactor and depositing powder in the powder bed. The hot powder stream 217 is discharged from the reactor by an exhaust valve 218, which may be a flap valve system. Any powder in the airflow is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor.

[0110] exist Figure 3 The diagram describes a direct separator reactor with co-current flow, wherein powder feed 301 is injected into injection pipe 303 of reactor tube 304 via rotary valve 302. In a plume, falling powder 305 enters the reaction ring through a notched cap 306, which is formed by a suspended central tube 307 (whose suspended matter is not specified). Falling powder 308 is heated to the reaction temperature in the ring by radiation from the steel wall 309 heated by furnace 310. The heated powder 311 falls deeper into the reactor, into reaction zone 312, where it absorbs radiant heat from the wall and initiates the desired reaction. As the reaction proceeds, hot process gas 313 accelerates the particles through the reactor via co-current flow. The length of the heating zone is sufficient to allow the reaction to proceed to the desired extent within the ring. The gas and particulate streams are separated by the reactor cone 314 and the powder bed 315. The powder bed 315 forces hot process gas vapor 316 into the central tube 307, which is then ejected from the reactor through the gas injection pipe 320 to obtain cooled process gas 317. The powder is deposited in the calcined powder bed. The hot powder stream 318 is discharged from the reactor through an exhaust valve 319, which may be a flap valve system. Any powder in the hot powder stream 318 is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor.

[0111] Figure 1 and Figure 3 The essential difference between them lies in... Figure 3 There is a physical barrier separating the airflow and the powder flow. It is worth noting that... Figure 1In this process, the powder tends to flow downwards near the outer wall of the reactor because, according to basic principles, the frictional force of the gas particles is minimal in this region.

[0112] Figure 3 One relative advantage of the central tube is that the updraft velocity can be very high, thus the size of the cyclone at the top of the reactor for separating fine powders is smaller than that of the inertial separator; particles are reinjected into the reactor at the top, while the large inertial separator at the bottom of the reactor is inefficient, requiring a cyclone / filter to separate the fine powder. Another advantage is that the central tube can absorb radiation from the heated outer tube, and this tube can re-radiate energy to the gas-particle flow, thus optimizing the net heat transfer rate. Another advantage is that the hot CO2 flow discharged from the top of the reactor can be used to partially preheat the input powder flow, such as the cyclone. This aspect will be considered separately below regarding integrated optimization. Another advantage of the central tube is that the separation efficiency of particles and gas in the region below the central tube is improved by adding swirling elements near the tube tail in the annulus and adding swirling elements to the blades near the inlet of the inner tube, both of which produce additional flow patterns for the gas above the cone at the bottom of the reactor. However, without these options, the gas-particle separation at the bottom is sufficiently effective. It is worth noting that... Figure 3 The central tube may be perforated or consist of a suspension section, and within this tube, blades may be used to swirl the gas so that any entrained powder can pass through the inline injector into the annular belt. Figure 3 The proposed implementation may be preferred because it provides such an option. Other options exist for mitigating agglomeration and its associated effects. The sintering of the particle reaction surface has been considered above. Such a surface is the outer surface of the particle, where the reaction front initially forms, causing the surface to begin sintering at the start of calcination, thus reducing the tendency for particle agglomeration from that point onward. In many direct separation reactor configurations, the particles are preheated before being injected into these reactors. Figure 4 An exemplary embodiment is shown, wherein the preheating process can be used to passivate the surface of external particles to a certain extent by partially calcining and sintering the surface.

[0113] Those skilled in the art will understand that the initial calcination temperature can be lowered by reducing the partial pressure of CO2, and that a low CO2 gas flow can be used to manage the preheating of the powder, thus initiating surface calcination to a controlled degree in the preheater. Figure 4The preheating section of the preheating / calcining / sintering system is described below. As described below, powder feed 401, at a temperature below the calcination temperature, is injected into injection pipe 403 via rotary valve 402. Injection pipe 403 conveys the particles to heat exchange reactor pipe 404 in a refractory lining, injecting falling powder 405 in the form of a plume. Hot steam / air flow 406, with a sufficiently high temperature, preheats the powder, calcining the solid to a limited extent and sintering it, as described below. The calcined particles, along with tangential gas, are injected into the bottom injector pipe 407 of the system and flow upwards as a vortex airflow 408. Heat exchange occurs between the rising gas and powder flows as they move in countercurrents. The system injection conditions are designed to reduce large-scale turbulence, which optimizes heat transfer between the particles and the gas. The rising airflow is discharged to gas outlet 411 via a system of separation plate 409 and tangential gas injection pipe 410. Any powder in the cooling airflow 411 is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor. The falling heated powder 412 forms a bed 413 in the cone 414. Hot powder exhaust gas 415 is discharged from the system using an exhaust valve 416, which may be a flap valve system. The input temperature and mass flow rate are such that the degree of calcination of the CaO material is preferably less than 10%, most preferably less than 5%, and the residence time of the powder in the bed allows for sintering of the powder in the powder flow 415, resulting in a viscous surface layer that reduces the tendency for particle agglomeration when injected into the calcining furnace.

[0114] By transferring preheated powder into a portion of hot CO2 gas, the sintering of CaO on the surface can be accelerated, thereby accelerating the aforementioned catalytic sintering, and the powder can be passivated to a certain extent by the holding time of the powder in the feed hopper. Alternatively, a small amount of steam can be injected into the preheated, pre-calcined particle bed to passivate the powder. Theoretically, CaO sintersects faster in steam than in CO2, and the formation of Ca(OH)2 by steam reaction can be suppressed by maintaining the material temperature above approximately 580°C. In most cases, the preheating of the powder is limited by available energy to around 720°C, thus satisfying this condition. A second feature of this embodiment is the injection of preheated powder into the reactor at multiple points below the reactor. The purpose of this method is to reduce the particle density at higher points in the reactor, thereby reducing the agglomeration rate at these points. This embodiment is as follows... Figure 5 As shown, it describes something similar to Figure 1 A direct separator reactor with countercurrent flow, wherein powder feed 501 is injected through a rotary valve 502 into a syringe tubing system 503, and then into a reactor tubing 504. (This is in contrast to a reactor with a single tubing.) Figure 1In contrast, the reactor tube system in this embodiment comprises three concentric tubes. These tubes have different lengths, allowing the powder to be released into the reactor at different heights. Powder 505 falling from each such tube is heated to the reaction temperature by a hot rising process gas stream 506 rising from the reaction zone 507 via counter-current gas-particle heat transfer. Cooled gas is separated from any entrained powder by a system including a separation plate system 508 and tangential gas jets 509 to provide a cooled process gas stream 510. Any powder in this gas stream is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor. Heated powder vapor 511 from each tube in the reactor accumulates and slowly descends against the rising gas stream into the reaction zone 507, where it is radiated from the reactor walls, generating heat within a furnace 512 that heats the steel walls 513. This heat flows to the gas and particles in the reactor to initiate the desired reaction. The length of the heating zone is sufficient to allow the reaction to proceed to the desired extent. The falling, calcined powder is collected in the reactor cone 514 and forms a calcined powder bed 515, which is extracted from the reactor through an exhaust valve 516, which may be a flap valve system to provide a flow of calcined powder 517.

[0115] It is worth noting that the degree of suppression of agglomeration achieved through sintering may be limited, as CO2 or H2O binds to the surface and promotes rapid surface migration of CaO at sufficiently high temperatures. This property can be used in the manufacture and application of new materials for producing low-emission lime using direct separation reactors. It is noteworthy that limestone particles, or lime, are currently widely used as slagging agents in high-temperature pyrolytic metallurgical processes to remove silica and other impurities. While ground limestone is often used in these processes, the endothermic load of calcining limestone into CaO is very high, so lime is typically used instead. Fine lime powder is not used in these processes because lime particles are entrained by the gas flow in such high-temperature processes, and millimeter-sized lime particles are preferred. The ability of direct separation reactors to produce low-emission lime is of interest, but as mentioned above, particle size is limited. However, experimental observations suggest that fresh lime produced from these reactors can be readily geogenerated into granules, which can then be heat-treated to produce granules with the strength required for such processes. Figure 6 The example implementation shows how such a process can produce such particles. Figure 6 This is a granulation system in which powder 601 and CO2-containing gas 602 are injected into a heated rotating drum 603, which is heated by a heating element 604, producing particles 605 at a sufficiently high temperature without recarbonizing CaO. One characteristic of these particles is that they are porous. Therefore, a second application is using these particles to capture SO2 in a fixed bed. xThese particles can absorb gases such as CO2, and their performance is enhanced because the reactivity of CaO inside the particles is higher than that of lime produced using traditional processes that use high-emission lime. Furthermore, CaO materials have high particle strength, are porous, and permeable, making them suitable for absorbing H2O and SO2. X It can dissolve gases such as CO2, O2, and H2S, as well as metal vapors, without cracking. In another embodiment, the high surface reactivity of CaO can be used to produce granules of powder mixtures. For example, the granules can consist of silicate-containing minerals, such as iron ore used in steel production, or kaolin used in alumina production, where the CaO in the granules can be used in subsequent processes to form calcium silicate through a slagging process under appropriate conditions. For metallic magnesium, the CaO-containing material can be dolomite, mixed with a reducing agent such as ferrosilicon, which, when heated, forms magnesium vapor and calcium-iron silicate slag. In all these cases, the granules provide close contact, where the migration of CaO promotes slagging formation.

[0116] The aforementioned prior art acknowledges that the direct separation reactor can be divided into different zones. One example is the post-processing section, where powder from the direct separation reactor is processed to complete the reaction process. It should be understood that the residence time to complete the calcination reaction can be long because the reaction rate slows down as the reaction nears completion. For different products and applications, very high degrees of calcination may be required. Figure 7 An implementation scheme for achieving calcination objectives in a separation reactor is described, wherein the first reactor section is analogous to a first reactor section with an extended reactor length. Figure 7 The text describes a common two-stage direct separation reactor, where the first reactor stage is... Figure 1Similarly, the second reactor section is lower than the first reactor section, and the calcination reaction is accomplished through a number of different designs described below, with the two sections separated by a gas block. The gas block is operated by a high-quality powder stream that substantially inhibits gas flow from the second section to the first section due to gas-particle friction. Powder 701 is injected into injection tube 703 via rotary valve 702, entering reactor tube 704. Powder 705 falling in the plume is heated to the reaction temperature by a hot rising process gas stream 706 rising from the first reaction section 707 through counter-flowing gas-particle heat transfer. Cooled gas is separated from any entrained powder by a system including separation plate 708 and tangential gas injection pipe 709 to provide a cooled process gas stream 710. Any powder in the gas stream is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor. In the reactor, heated powder 711 slowly descends against rising gas and enters the reaction zone, where it is radiated from the reactor wall. Heat is generated within a furnace 712 that heats the steel wall 713, and flows to the gas and particles in the reactor to initiate the desired reaction. The heating zone is long enough to allow the reaction to complete to the desired intermediate stage. The calcined intermediate powder 714 falls into a conical tube 715, where it is concentrated and flows into a gas block 716 that falls into a second reactor section 717. A gas stream 718, having a composition depending on the materials and the operating mode of this embodiment, is injected into this reactor section, where it interacts with the powder and exits as a gas stream 719. The efficiency of the gas block is determined by the pressure drop between the two reactor sections. If required by the application, the temperature of the reactor section walls can be controlled by an externally heated furnace or cooling section 720. The required reaction is completed in this section to generate calcination power 721, which is collected in the reactor cone 722 and forms a thermally calcined powder bed 723, which is removed from the reactor through an exhaust valve 724, which may be a baffle valve system, to generate a calcined powder stream 725.

[0117] In the production of CaO, the reaction is incomplete, and the temperature of the partially calcined powder 714 will be slightly higher than approximately 895°C. Figure 7 In one implementation, the CO2 partial pressure in the first stage is approximately 103 kPa, and is reduced to approximately 10 kPa by injecting air or steam 718, so that the reaction restarts when the powder is transferred to the second stage. Calcination can be accomplished by consuming the heat in the powder or by applying additional heat from furnace 720 as needed. The same considerations apply to the production of MgO. If steam is used, the temperature must be maintained above the relevant hydration temperature.

[0118] exist Figure 7In another embodiment of the system implementation, the second stage is used for sintering intermediate material 714. In a specific embodiment, the intermediate is MgO produced by calcining MgCO3 as feed 701, and the gas 718 is vapor used to catalyze MgO to obtain the MgO surface area required for industrial applications. Without vapor, the specific surface area can be greater than approximately 250-350 m². 2 / g, can be reduced to less than about 10m in the presence of steam. 2 / g.

[0119] exist Figure 7 In another embodiment of the system implementation, gas 718 may be a mixture of air or oxygen and a combustible material, typically a gas that generates heat for the reaction through a flameless combustion reaction, such as syngas. This mode of operation is facilitated by the high temperature of the powder feed 714, preferably above the auto-ignition temperature of the combustible material.

[0120] It is worth noting that by injecting air and fuel into the bottom of a single-stage reactor, the second stage can be directly integrated into the first stage of the reactor. In this case, the calcination reaction caused by the partial pressure drop leads to an increase in the gas concentration distribution in the reactor, which is mitigated by the mutual diffusion of the gases.

[0121] exist Figure 7 In another exemplary embodiment, the gas 718 injected into the second stage has components that react with the calcined intermediate powder 714 produced in the first stage. In this method, the first stage is preferably operated to achieve a sufficiently high degree of calcination such that the reaction between the gas and powder in the second stage produces the desired calcined product 725. Furthermore, the furnace / cooler 720 is configured to establish the desired reaction conditions, such as providing heat for an endothermic reaction or removing heat for an exothermic reaction. One specific embodiment is where the calcined intermediate 714 is CaO from a limestone precursor 701, the injected gas 718 is steam, and the furnace / cooling system 720 operates in cooling mode such that the product 725 is slaked lime, Ca(OH)₂. The heat recovered in 720 can be used throughout the process to reduce the overall energy requirements. The same considerations apply to the production of Mg(OH)₂ from MgO.

[0122] A typical implementation for the production of battery and catalyst materials is a process in which the desired reaction is a reduction or oxidation of intermediate 718 produced by precursor 710, and is accomplished by using a suitable reducing or oxidizing gas 718 and setting a temperature to initiate the desired reaction of desired product 725.

[0123] Those skilled in the art should understand that Figure 7The principles described in the multi-stage exemplary embodiments can be applied to any calcination reaction, or a pair of reactions, or a sintering reaction, in which the gas has a composition suitable for the desired process.

[0124] The Portland cement production process is divided into several stages. Existing technology for direct separation reactors describes a method in which the initial stage of the process, namely the calcination of the cement raw meal, takes place in a direct separation reactor, and the performance of this stage can be improved by the invention described in this disclosure. The second stage takes place in a rotary kiln, where the calcined coarse powder is injected into the kiln and heated by a flame to approximately 1450°C, where a aging reaction is activated to form belite and allite as the main binders. It is noteworthy that the thermal efficiency of cement plants is typically around 60% or lower because of the high heat loss in the rotary kiln and the underutilization of the exothermic energy of the aging reaction. Figure 8 The proposed implementation is an improvement to this process. This implementation describes how to use combustion gases and the injection of air / oxygen to increase the temperature of the powder discharged from the direct separation reactor via homogeneous combustion reaction. This application Figure 8 The implementation scheme describes the process within the refractory lining section, where a countercurrent of rising reactive air and fuel is used to heat the powder to approximately 1260°C or higher. Figure 8The present invention describes a specific two-stage direct separation reactor for producing clinker from preheated cement powder, wherein a method is employed to form clinker in the direct separation reactor stage. In this method, a flap valve may be optionally used to separate gas vapors. At approximately 720°C, preheated cement powder 801 is injected into injection pipe 803 via rotary valve 802 to enter reactor pipe 804. Falling preheated powder 805 in the plume is heated to the reaction temperature by a hot rising CO2 process gas stream 806 rising from the first reaction section 807 via countercurrent gas-particle heat transfer. Cooled gas is separated from any entrained powder by a system including separation plate 808 and tangential gas injection pipe 809 to provide a cooled process gas stream 810 at approximately the same temperature as 801. Any powder in this gas stream is extracted by a cyclone / filtration system (not shown) and reinjected into the reactor. In the reactor, heated powder 811 slowly falls against the rising gas and enters the reaction zone, where it is radiantly heated from the reactor wall. Heat is generated within a furnace 812 that heats the steel wall 813, and flows to the gas and particles in the reactor to initiate the desired reaction. The length of the heating zone is sufficient to allow the reaction to complete to the desired intermediate stage. Calcined cement powder 814 falls into a conical cylinder 815, where the powder is concentrated and fed into a second reactor section 817 by a baffle valve 816. A fuel stream 818 and an oxygen / air stream 819 are injected into this reactor section, where it undergoes flameless combustion and heats the powder 820. The reactor wall 821 is a refractory tube. The combustion process heats the powder 822 to a temperature of approximately 1260°C, marking the start of the curing reaction that forms belite. Hot clinker particles fall into vertical kiln section 823. In the slowly moving bed, particle-to-particle contact allows these exothermic clinker reactions to take place, releasing heat that drives the temperature to approximately 1450°C or higher. When the bed residence time is approximately 30 minutes or less, allit is formed there. The exothermic process is completed in this section to produce clinker particles. Exhaust valve 824 discharges the hot clinker particles 825 from the vertical kiln, where they are air-cooled using a conventional grating cooler (not shown). Figure 8 An energy-saving process is described because the exothermic reaction heats the raw materials, unlike traditional kiln processes which have high heat loss, a feature that will be appreciated by those skilled in the art.

[0125] High energy efficiency is a crucial factor in industrial processes. Regarding reactors, the thermal efficiency of a given degree of calcination is unaffected by the use of a direct separation reactor. Any heat loss is related to the heat loss through the refractory surface surrounding the furnace and burner sections of the reactor. In this embodiment, the invention extends to considerations of the burner-furnace construction. Important factors in heat transfer are temperature and convective heat exchange in the steel reactor walls and furnace refractory material, thereby optimizing radiative heat transfer through the steel walls. Typically, this is optimized using known techniques employing high gas velocities and gas vortices. Direct separation reactors can be operated by using separate burner boxes and piping the hot flue gas to provide these desired characteristics to the furnace surrounding the reactor tubes, and the hot flue gas exhaust can be used to preheat air for combustion. However, the piping and distribution of high-temperature gases are not ideal. Figure 9 The example embodiment for treating limestone illustrates different methods. The selected fuel is syngas from biomass, and a post-combustion CO2 capture system is used to illustrate the carbon-negative products (not shown) when the CO2 stream is isolated. Generally, it is desirable to tightly integrate the burner, furnace, and air recovery process to reduce the required air volume. Figure 9 As shown in the implementation plan, a regenerative flameless system array can be applied to reduce flue gas volumetric flow rate. In such a system, the burner and furnace are integrated, and due to the absence of a flame, the gas temperature is uniform, and the gas-mixing velocity is high. The regenerative flameless burner has very high thermal efficiency, and the absence of a flame minimizes NO₂. x The generation of [something]. The distribution using this system allows for temperature control along the tube, which allows for optimization of the calcination process within the tube. Figure 9In one embodiment, a system using a direct separation reactor is described, which processes limestone feed 901, grinds it to approximately 125 μm, and then processes it into lime 902. The reactor system has three sections—a first powder preheater section 903, a second powder preheater section 904, a direct separation reactor section 905, and a powder cooler section 906. In the first powder preheater section, a limestone process hot CO2 stream 907 is injected into the bottom of the counter-current heat exchange refractory liner tube of the first powder preheater section 903, where ambient temperature limestone powder 901 is injected to provide cooling for the CO2 stream 910 and to form a bed of partially heated limestone 911. The partially heated limestone 911 from the bed is injected into the top of the heat exchange refractory liner tube of the second powder preheater section 904, which is heated by a hot stream 912 from the powder cooler section 906 described below, and the preheated limestone 913 forms a bed. If necessary, the temperature of this airflow can be increased by a pipe heater (not shown), since the temperature of the preheated limestone is approximately 930°C at or near the start of limestone calcination. The cooled airflow 914 is discharged but can be used (not shown) to provide low-grade heat to the post-combustion CO2 capture system 915 for use with the flue gas described below. The preheated limestone 913 is injected into the direct separation reactor section 905, shown here. Figure 1 The countercurrent system provides a pure stream 907 of treated CO2, injected at approximately the temperature of preheated limestone, along with hot lime powder 916. The direct separation reactor is heated by burning a thermal syngas stream 917 formed by burning biomass 918 and air 919 from a gasifier 920. In the gasifier, syngas and ash 921 are separated. Tar formed during gasification can be reinjected into the thermal syngas vapor. The steel pipe 922 of the direct separation reactor section 903 is heated by multiple regenerative flameless combustion systems for the combustion of the thermal syngas, wherein regenerative flameless combustion system 928 injects air 923, which is preheated by the hot exhaust gas from the combustion chamber in heat exchanger 924, thereby cooling the flue gas vapor 925, thus achieving a highly thermally efficient combustion process. CO2 from the gas stream is injected into a post-combustion CO2 capture system 915, where CO2 926 is extracted and mixed with direct separation gas vapor 910 to produce CO2 vapor 927 for compression and liquefaction (not shown).

[0126] CO2 emissions from fossil fuel combustion gases make a significant contribution to the CO2 emission intensity of calcined products. For lime and cement, as well as typical solid fossil fuels such as coal, combustion emissions account for approximately 35% of total emissions. One approach to reducing combustion emissions is the use of biofuels in conjunction with direct separation reactors. Biofuels are typically solid fuels called biomass, which can be gasified into syngas using known technologies and can be used for… Figure 9In this configuration, the integrated gasification process uses known technologies to heat biomass in steam / air to release combustible volatiles and separate and burn ash, including fly ash and its residual carbon, to provide heat for volatilization in the indirect heating process. The hot volatiles are collected using a flameless burner with preheated air. In this process, the gas can include syngas as well as tar precursors, as they are burned. That is, there is no need for expensive tar precursor removal processes because the gas remains above the tar condensation process, so the fuel is not only preheated but also has a higher combustion LHV. Removing fly ash from the gas stream is to minimize the formation of silica glassy deposits on the furnace steel walls. Figure 9 The post-combustion capture process can use amines, bicarbonates, or hydrotalcites.

[0127] The above implementation plan and by Figure 1-9 The example implementation is associated with a single-tube-based reactor. Scaling up the process by increasing the reactor diameter is limited by the absorption of heat from the hot walls by the particles and process gas. The mass flow rate is limited by the wall's heat transfer capacity and the contact between the particles and the process gas, which affects the residence time of the particles in the reactor tubes. Typically, the mass flow rate through a reactor with a diameter of approximately 2 m is in the range of 5-10 tons / hour. The reactor height depends on the process kinetics and the wall's heat transfer rate, and is typically 10-30 meters. Thus, scaling up the process is often achieved by increasing the number of tubes. However, there are some innovations related to reactor tube array design, which are described here. Figure 10 This is an example implementation of an expanded system where tubes (shown as four in this implementation) are assembled into the furnace, with the amount of refractory material between the tubes minimized so that any tube can be shut down with minimal impact on adjacent tubes. The temperature of the non-operating tube is low enough that there is no risk of deformation, and the setpoint of the operating tube can be adjusted to maintain the degree of calcination of the product and other process variables. This condition can be implemented in the module so that any tube can be operated, and the process flow in each tube can be varied according to the known thermal coupling that can be tolerated between the tubes. Figure 10 In one implementation, the refractory material can be composed of stacked ingots that provide an integrated input gas and flue gas distribution system to the module, and a flameless burner is shown. The ingots are designed to minimize the mass of the refractory material, as well as the cost of construction and replacement. In this implementation, each tube has its own preheating and post-treatment system to minimize the transport of hot gases and powders. Figure 10The implementation scheme is a schematic diagram of reactor module 1001 comprising four direct separation reactors 1, 2, 3, and 4 integrated into refractory material 1003. The system is based on the concept that conveying cold powder and cold gas vapor is a known technology, and that minimizing the temperature of these processes can reduce costs and challenges. The implementation scheme shows the input of ambient powder 1004, gaseous fuel source 1005, and ambient air 1006. The direct separation reactors are based on... Figure 1 Implementation plan and Figure 9 The burners. Therefore, the input powder is conveyed from the hopper to each reactor by a cold powder conveyor 1007, and via separate pipelines to the corresponding first-stage preheaters PHI-1, 2, 3, 4. These preheaters cool the process CO2 1008 from each direct separator reactor section DS-1, 2, 3, 4, and are then directed to the central CO2 cleaning / purification compressor system 1009. The flue gas 1010 from the reactor burners, after being recovered with the incoming air stream, is directed to the post-combustion capture device 1011 to generate a combustion CO2 stream 1012, which is then compressed, and the flue gas... In the case of cement powder production, the hot powder stream from each reactor can be... Figure 11 The air chute described in the implementation scheme is used to deliver the air to the rotary kiln.

[0128] The multiple modules shown in Figure 10 can be further scaled up. The advantage of this approach is that any tubes that might become inoperable can be replaced while others continue to operate, and these tubes can be tuned and their operation optimized at each stage of preheating, calcination, and cooling to deliver a calcined product 1017 that meets specifications.

[0129] Auxiliary equipment used for preheating and post-processing powders and gas vapors can be scaled up into a single module. While this method requires the distribution of hot gases and powders, many methods are available to achieve the benefits of this scaling. Such systems include... Figure 11 As shown, the module consisting of four tubes has a single preheater stack to uniformly distribute the preheated powder into the tubes using a 1:4 L valve distribution system with controls that allow any number of tubes to be fed in; the calcined powder stream is collected using a 4:1 heated air slider system with similar controls, and the hot CO2 stream is combined into a single CO2 vapor for post-processing and compression. It is well known that such heat recovery systems can be scaled up using suspended cyclones in cement plants. In this embodiment, the heat from the combined CO2 stream is used to preheat the powder in the first stage of the cyclone stack. For cement production, a hot air slider will convey the hot calcined powder to a single rotary kiln (not shown). Figure 11The implementation scheme is a schematic diagram of a system using reactor modules 1111 integrated into four direct separation reactors 1, 2, 3, and 4 within the refractory material 1113. This system is based on the concept that conveying hot powders and hot gas vapors is a known technology, and the higher cost and challenges of these components are offset by using large preheaters and coolers, rather than... Figure 10 As shown, each reactor requires a separate system. This embodiment illustrates the input of preheated powder 1114, gaseous fuel source 1115, and ambient air 1116. The direct separation reactor is based on... Figure 1 Implementation plan and Figure 9 The combustion chamber. In the case of hot powder, the flow rate into each tube is controlled by fluidizing hot air 1118 using an L-valve fluidized bed 1117, and heat loss in each delivery tube 1107 is minimized by refractory tubes. The preheated powder in each tube of the delivery system, if pneumatic, is steeply inclined to avoid jumping. Each reactor DS1, DS2, DS3, DS4 generates a hot process CO2 stream, which polymerizes into a hot CO2 stream 1119 and a hot flue gas stream 1120, which are conveyed through refractory-coated pipes (not shown) to a central preheater for the powder. Calcinated powder streams Call, Cal2, Cal3, and Cal4 are conveyed from each tube by the piping system, and in one example, conveying is achieved by a refractory-enclosed, inclined hot air chute 1121. The polymerized, hot-calcined material 1112 is typically injected into a powder cooling system (not shown), or, in the case of cement production, into a rotary kiln system.

[0130] Although the invention has been described with reference to specific embodiments, those skilled in the art will understand that the invention may be embodied in many other forms in accordance with the broad principles and spirit of the invention as set forth herein.

[0131] The present invention and the described preferred embodiments specifically include at least one feature for industrial applications.

Claims

1. Direct separation reactor, including: A powder feeder having an injection pipe extending to the top of a single vertical reactor tube, wherein the injection pipe feeds powder into the single vertical reactor tube such that the powder falls downward through the single vertical reactor tube, wherein the powder includes minerals that release process gas flow upon heating, the process gas flow and the falling powder flow downward through the vertical reactor tube in parallel. The lower part of the single vertical reactor tube includes an external heating wall for calcining downward-falling powder to release the process gas flow. An exhaust device located within the single vertical reactor tube, wherein the exhaust device includes a suspended central tube extending within the reactor tube, the suspended central tube including an exhaust outlet located at the upper part of the single vertical reactor tube and an exhaust inlet located at the lower part of the single vertical reactor tube, wherein the process gas flow is forced to flow upward through the suspended central tube, such that the process gas flow changes to a countercurrent flow relative to the downward falling calcined powder before exiting from the exhaust outlet. as well as A reactor cone located at the bottom of the vertical reactor tube, wherein the reactor cone, together with a powder bed formed within the reactor cone, separates the process gas flow from the downward falling powder, and the powder bed forces the process gas flow into the exhaust inlet.

2. The direct separation reactor according to claim 1, wherein: The exhaust outlet allows the process gas flow to exit the vertical reactor tube.

3. Direct separation reactor, including: A powder feeder having an injection pipe system extending to the upper part of a single vertical reactor tube, wherein the injection pipe feeds powder into the single vertical reactor tube such that the powder falls downward through the single vertical reactor tube, wherein the powder includes minerals that release process gas flow upon heating; the lower part of the single vertical reactor tube includes an external heating wall for calcining the falling powder to cause the powder to release process gas flow that rises countercurrently to the falling powder, and wherein the injection pipe system includes concentric tubes of different lengths such that the powder is injected into the vertical reactor tube at different heights. An exhaust device located at the top of the single vertical reactor tube; and A particle separation plate array is used to separate particles from the rising gas flow before the process gas flow leaves the exhaust outlet.

4. The direct separation reactor of claim 1 or 3, wherein the released process gas is selected from at least one of the group consisting of carbon dioxide, steam, acidic gas and alkaline gas.

5. The direct separation reactor according to claim 4, wherein the acidic gas is hydrogen chloride.

6. The direct separation reactor according to claim 4, wherein the alkaline gas is ammonia.

7. The direct separation reactor according to claim 1 or 3, wherein the powder is preheated in a gas-powder preheater system and the preheated powder is fed into the vertical reactor tube.

8. The direct separation reactor according to claim 1 or 3 further includes an external heating system configured to heat an external heating wall such that the external heating wall forms a heating zone of the vertical reactor tube; wherein the external heating system is an integrated burner and furnace system capable of controlling the temperature distribution along the heating zone.

9. The direct separation reactor according to claim 8, wherein the integrated burner and furnace system is a flameless combustion system.

10. The direct separation reactor according to claim 8, wherein the fuel for the external heating system is at least one gas selected from the group consisting of natural gas, syngas, town gas, producer gas, and hydrogen; wherein the combustion gas is air, oxygen, or a mixture thereof obtained by heating the flue gas from the external heating system.

11. The direct separation reactor of claim 10, wherein combustion of fuel for an external heating system forms flue gas, and wherein CO2 in the flue gas is extracted using a regenerative post-combustion CO2 capture system, said regenerative post-combustion CO2 capture system being at least one of the following: an amine adsorbent system, a bicarbonate adsorbent system, and a calcium recycling system.

12. The direct separation reactor of claim 3, wherein the vertical reactor tube is divided into multiple sections installed in series, wherein gas released or introduced in a respective section is extracted from the respective section using a gas block between the respective sections.

13. The direct separation reactor according to claim 12, wherein the partial pressure of the gas released during the higher-stage calcination process decreases in the lower stage, and wherein the thermal energy stored in the downward-falling calcined powder from the higher stage is used for calcination.

14. The direct separation reactor of claim 13, wherein the wall temperature of each section increases sequentially from the higher section in each section.

15. The direct separation reactor according to claim 1 or 3, wherein the vertical reactor tube is segmented into multiple sections, wherein gas released or introduced in a respective section is extracted from the respective section using a gas block between the sections, and wherein a hot gas flow is introduced into at least one section to enhance the thermal energy provided by the external heating wall.

16. The direct separation reactor of claim 15, wherein the hot gas stream comprises combustible fuel, and wherein the fuel is burned in the at least one section to provide additional thermal energy.

17. The direct separation reactor according to claim 7, wherein the preheating temperature of the gas-powder preheater system is 650-800°C, and the partial pressure of the gas released during calcination is below 15 kPa.

18. The direct separation reactor according to claim 1 or 3, wherein the vertical reactor tube is configured to vibrate.

19. A system for calcining powder materials, the system comprising: The preheating reactor section is used to preheat the powder material to a temperature suitable for partial calcination, thereby forming partially calcined powder; and The direct separator reactor section is configured to receive partially calcined powder and further calcine the partially calcined powder. The direct separator reactor section comprises the direct separator reactor according to any one of claims 1 to 18.

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