Hybrid heating systems and processes

Abstract

Disclosed herein is a vertically oriented reactor, the reactor comprising: a vertically oriented reactor tube; a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube; and a heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur; wherein the heating system is configured to operate using combustion heating and electricity. Also disclosed herein are systems for reacting a powder.

Description

Hybrid Heating Systems and ProcessesPriority

[0001] This application claims priority from Australian Provisional Application Nos.2025900030 and 2025900691, the entire contents of the specifications of which are incorporated herein by way of cross-reference.Technical Field

[0002] This disclosure relates to reactors and systems that can operate using energy from combustion and / or electricity. This disclosure also relates to reactors and systems that can operate using AC and / or DC electricity.Background art

[0003] Historically, energy generation has been the largest anthropogenic source of carbon dioxide (CO2). As the world looks to decarbonise, Variable Renewable Energy (VRE) grids are increasing in popularity. The costs of both solar and wind generation are being lowered by innovations of both these technologies. However, there are issues associated with the use of VRE grids in which a large fraction of the energy is generated from renewable sources such as solar and wind due to the intermittent nature of these energy sources. Accordingly, difficulties with managing high VRE grids arise from the very large variations of renewable energy on both daily to seasonal changes of sun and wind energy variations.

[0004] The International Energy Authority (TEA), has reported the challenges of operating high VRE grids for many years. In its report IEA (2024), “Integrating Solar and Wind, IEA, Paris https: / / www.iea.org / reports / integrating-solar-and-wind”, the IEA validated its concerns of commercial viability of high VRE grids from operators experienced in managing these grids. The recent report not only considers the rapid uptake of VRE based on the low costs of renewable energy generation from solar and wind, but also describes the challenges that arise from the high variability of these grids from weather changes. The IEA warns that the cost and complexity of implementation of its solutions to managevariability may decrease investment for VRE grids, so investment in renewable energy generation may fail to meet targets of C02 emissions reduction.

[0005] The use of grid power by consumers is generally divided between domestic / small business users, and large manufacturing industries. The domestic / small industry sectors are most likely to exacerbate the variability issues through their own generation of behind-the-grid renewable electricity, and they often have an incentive to provide excess energy to the grid.

[0006] It may be seen as desirable to provide systems that are able to make use of electricity from VRE grids in a cost-effective manner.

[0007] It is to be understood that, for any prior art referred to herein, such reference does not constitute an admission that the prior art forms a part of the common general knowledge in the art, in Australia or any other country.Acknowledgements

[0008] The projects leading to this application have received funding from the European Union’s 2020 innovation programme under grant agreement 884170 for “Low Emissions Intensity Lime and Cement”, and the Australian Commonwealth Government’s support for the project ZETA “The Cement Plant of the Future” under grant agreement CCTPA000012.Summary

[0009] Disclosed herein in a first aspect is a vertically oriented reactor. The reactor is particularly (although not exclusively) suitable for use in a number of applications, such as for the manufacture of energy intensive products that use heat for production. That is, the reactor of the present disclosure is particularly suitable for use in applications involving endothermic reactions. For example, the present reactor is suitable for use in a number of processes such as calcination reactions, phase change reaction, reactions between a powder and a gas, etc., and combinations thereof.

[0010] The reactor can comprise a vertically oriented reactor tube.

[0011] The reactor can also comprise a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube. The powder input may be configured to input the powder into the reactor tube such that the powder falls downwardly into the reactor tube.

[0012] The reactor can further comprise a heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur. For example, the heating system may be configured to provide heat to a portion of the interior of the reactor tube.

[0013] The heating system can be configured to operate using combustion heating and electricity.

[0014] For example, in some embodiments, the heating system may be configured to operate using combustion heating or electricity or both combustion heating and electricity simultaneously.

[0015] Advantageously, the present reactor can allow the energy source to be switched to and from a number of energy sources, e.g., an electrical energy source and combustion, in reactors for industrial applications. Furthermore, the present reactor may be configured to switch between using an electrical energy source and combustion with minimal (or no) impact on the manufacturing of the products before, during and after switching. Efficient switching between energy sources may also reduce and / or minimise the cost of energy associated with operating the reactor, e.g., because electricity can be utilised for the heating system when the cost of electricity is low, but combustion can be utilised for the heating system when the cost of electricity is high. In addition, the present reactor may allow for the stabilisation of high VRE grids by employing electricity when there is excess electricity in the VRE grid. Of further advantage is that the present reactor can also operate using two energy sources (i.e., electricity and combustion) simultaneously. This can allow for a constant energy supply to be provided to the heating system as the energy source is being switched.

[0016] In some embodiments of the first aspect, when the heating system is operated using electricity, the electricity may be generated or sourced from a renewable energy source. For example, the electricity may be from a VRE. Advantageously, because the present reactor is able to use energy from combustion as well as electricity from a VRE, the present reactor may be able to use energy from VRE grids in which a significant percentage of the electricity is generated from renewable sources, such as class 5 and 6 grids. Such grids typically experience greater variability in electricity supply. It is noted that, typically, in class 1-3 grids, only a small percentage of the electricity is generated from renewable sources and, as such, grid management is typically easier. Class 5 grids are defined internationally as those that have surplus VRE in excess of demand up to about 20% on average. Such grids must manage such surpluses for about 2 days per week on average. Class 6 grids are those that have to deal with high surpluses as they have near 100% VRE generation. Advantageously, the present reactor can switch from the use of combustion energy to electric energy from a VRE grid, e.g., when the cost of electricity is lower than combustion energy and / or when there is surplus electricity in the VRE grid. The present reactor can then switch back to using combustion energy, e.g., when the cost of electricity is higher than combustion energy and / or when there is no longer surplus electricity in the VRE grid. Furthermore, the switching may be sufficiently fast to respond quickly to both foreseeable and unforeseeable events arising from weather variations. In this regard, plants comprising the present reactor may be deployed in grids that are evolving towards class 4 grids to lower the foreseeable risk, and may be deployed in class 5-6 grids as the grids build high VRE capacity.

[0017] To the inventor’s knowledge, there is no prior art which discloses the present approach of switchable energy sources during manufacturing for stabilisation of an energy grid while maintaining production. It is noted that many energy-intensive industries must turn down their consumption of electric power from the grid under contracts with grid operators. However, there are no alternative energy sources available. As a result, when the consumption of electric power must be turned down, the operators cannot use their full manufacturing capacity. Such contracts will make manufacturing more difficult as thefrequency of events, such as reduced power supply, increases in high VRE grids. In addition, processes that use heating for production often take many hours to restart.

[0018] Alternatively or additionally, when the heating system is operated using electricity, the electricity may be generated or sourced from stored electricity. For example, the stored electricity can comprise electricity from a battery.

[0019] It is noted that a prime driver for the uptake of VRE grids is that renewable energy reduces CO2 emissions, with many forms of renewable energy being associated with zero CO2 emissions. The costs of renewable energy, e.g., from solar and wind, are being lowered by innovations of both these technologies. The reactor of the present disclosure can advantageously introduce a new paradigm in which manufacturing plants that use energy for heating can lower their operational costs significantly, e.g., by using electricity from the VRE grid when electricity prices are lower than the cost of producing energy from combustion and, conversely, using combustion energy when electricity prices are higher than the cost of producing energy from combustion.

[0020] In some embodiments of the first aspect, the heating system may be configured to use AC or DC electricity when the heating system is operating using electricity. For example, a power grid typically supplies electricity in the form of AC electricity. On the other hand, batteries typically supply electricity in the form of DC electricity.

[0021] In some embodiments of the first aspect, the heating system may be positioned vertically adjacent at least one wall of the reactor tube at an intermediate region of the reactor tube. When the system is operated using combustion heating, the heating system may be configured to indirectly heat the interior of the reactor tube. In some of these embodiments, the heating system may comprise a combustion chamber arranged to surround the reactor tube. The combustion chamber may be configured to combust air and fuel therein. The air and / or fuel may be preheated prior to being combusted in the combustion chamber. Alternatively, in other embodiments, the heating system may comprise a chamber arranged to surround the reactor tube. The chamber may be configured to receive hot exhaust gases from a combustion process. That is, in such embodiments, thecombustion may occur in an external combustion process, with the hot exhaust gases being passed to the chamber surrounding the reactor tube.

[0022] In some embodiments of the first aspect, the heating system may comprise resistive heating elements located adjacent to a wall of the reactor. The resistive heating elements may be configured to be powered by electricity. For example, the resistive heating elements may be configured to be powered by AC and / or DC electricity. The resistive heating elements may be located adjacent the wall of the reactor in the interior of the reactor tube or exterior to the reactor tube. Alternatively, in other embodiments, the walls of the reactor may be comprised of resistive heating elements. The resistive heating elements may be configured to be powered by electricity.

[0023] In some embodiments of the first aspect, the reactor tube may further comprise at least one annulus. The annulus may be configured to divide the heating system into an upper heating system located above the annulus and a lower heating system located below the annulus.

[0024] In some embodiments of the first aspect, a wall of the reactor tube may be configured with one or more bellows. In some of these embodiments, at least one of the one or more bellows may be located in an intermediate region and / or at least one of the one or more bellows may be located below an intermediate region. For example, the one or more bellows may act to separate the wall of the reactor into more than one section, with adjacent sections being connected by a bellow.

[0025] In some of these embodiments, the wall of the reactor tube may be configured with one bellow. In embodiments in which the reactor comprises an annulus, the bellow may be located within the annulus, with the upper heating system located above the bellow and the lower heating system located below the bellow.

[0026] In some variations of the first aspect, the heating system may comprise a combustion heating system arranged to surround a first section of the reactor tube and an electrical heating system arranged to surround a second section of the reactor tube. In some embodiments of these variations, the combustion heating system and the electrical heating system may be separated.

[0027] In some embodiments of these variations, the combustion heating system and the electrical heating system may each be comprised of multiple segments arranged along a length of the reactor tube. Furthermore, in some embodiments, the reactor tube may be comprised of multiple segments. Each of the reactor tube segments may comprise one of the multiple combustion heating system segments and one of the multiple electrical heating system segments.

[0028] In some embodiments of these variations, each segment of the reactor tube may comprise a temperature sensor configured to measure a temperature of the reactor wall. Additionally, the reactor may be configured with a controller operable to increase or decrease an amount of combustion occurring within the combustion heating system based on a measured temperature.

[0029] In some embodiments of the first aspect, the reactor may further comprise a dispersion apparatus located at the upper end of the reactor tube and below the powder input. The dispersion apparatus may be configured to break up clumps of powder and to enhance the dispersion of particles throughout the reactor tube. This may help promote pluming and increased residence time within the reactor tube, i.e., by reducing clustering of the particles, and enhance heat and mass transfer within the reactor tube.

[0030] In some of these embodiments, the dispersion apparatus may comprise rotor blades which, in-use, are located on a vertical axis of the reactor tube and are configured to spin around the vertical axis of the reactor tube.

[0031] In some of these embodiments, the dispersion apparatus may be further configured to reduce a particle size of the powder and to input the resultant powder into the reactor tube. For example, the rotor blades may cause the particle size of the powder to be reduced as the powder impacts the rotor blades. The apparatus may be further configured such that the powder of reduced particle size leaving the rotor blades falls downwardly into the heated interior of the reactor tube.

[0032] In some of these embodiments, the reactor may further comprise an input powder preheater configured to preheat the powder input at the upper end of the reactor tube prior to the powder being heated by the heating system. For example, the powder preheater maybe configured to preheat the powder using energy from one or more of: a powder product output from the reactor tube, an exhaust gas from the reactor tube and / or an exhaust gas from a combustion process. In this way, the reactor can advantageously recycle process heat to preheat the powder.

[0033] In some embodiments of the first aspect, the reactor may further comprise a gas exhaust located adjacent the upper end of the reactor tube. In some of these embodiments, the gas exhaust may comprise a cyclone separator configured to separate entrained powder from an exhaust gas. The gas exhaust may be further configured to reinject the entrained powder into the interior of the reactor tube.

[0034] In some embodiments of the first aspect, the reactor may further comprise a reacted powder hopper located at a lower end of the reactor tube and configured to output a powder product from the reactor.

[0035] In some embodiments of the first aspect, the reactor may be configured with a controller which is operable to switch the energy for the heating system to the use of electric energy when a price of electricity is low or when a quantity of electricity available is high, and to switch the energy for the heating system to the use of combustion when the price of electricity is high or when the quantity of electricity available is low.

[0036] Disclosed herein in a second aspect is a vertically oriented reactor. The reactor is particularly (although not exclusively) suitable for use in a number of applications, such as for the manufacture of energy intensive products that use heat for production. That is, the reactor of the present disclosure is particularly suitable for use in applications involving endothermic reactions. For example, the present reactor is suitable for use in a number of processes such as calcination reactions, phase change reaction, reactions between a powder and a gas, etc., and combinations thereof. The reactor of the second aspect can have the same benefits as the reactor of the first aspect.

[0037] The reactor can comprise a vertically oriented reactor tube.

[0038] The reactor can also comprise a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube.

[0039] The reactor can further comprise a heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur. The heating system can be configured to operate using grid electricity and one or more other energy sources.

[0040] In some embodiments of the second aspect, wherein, in-use, the heating system is configured to operate using the grid electricity or the one or more other energy sources or both the grid electricity and the one or more other energy sources simultaneously.

[0041] In some embodiments of the second aspect, the grid electricity may comprise electricity from a Variable Renewable Energy (VRE) grid.

[0042] Advantageously, the reactor of the second aspect can allow the energy source can be switched to and from a number of energy sources, e.g., grid electricity or energy from one or more other energy sources, to be used in reactors for industrial applications. Furthermore, the reactor of the second aspect may be configured to switch between using an grid electricity and energy from another energy source with minimal (or no) impact on the manufacturing of the products before, during and after switching. Efficient switching between energy sources may also reduce and / or minimise the cost of energy associated with operating the reactor. In addition, the reactor of the second aspect may allow for the stabilisation of high VRE grids by employing grid electricity when there is excess electricity in the VRE grid and by employing energy from another energy source when there the electricity supply of the VRE grid is low or the grid is offline. Of further advantage is that the reactor of the second aspect can also operate using two energy sources (i.e., grid electricity and electricity from another energy source) simultaneously. This can allow for a constant energy supply to be provided to the heating system as the energy source is being switched.

[0043] In some embodiments of the second aspect, at least one of the one or more other energy sources may provide electricity in the form of DC electricity. For example, the one or more other energy sources may comprise energy stored in a battery.

[0044] In some embodiments of the second aspect, at least one of the one or more energy sources may provide energy from combustion. Alternatively or additionally, at least one of the one or more energy sources may provide energy in the form of hot gases, e.g., hot gases from a thermal energy storage system. As a further example, at least one of the one or more energy sources may comprise an electrical plasma heating system.

[0045] In some embodiments of the second aspect, the reactor may be otherwise as defined in the first aspect.

[0046] Disclosed herein in a third aspect is a system for reacting a powder, wherein the reaction comprises an endothermic reaction. The system is particularly (although not exclusively) suitable for use in a number of applications, such as for the manufacture of energy intensive products that use heat for production. That is, the system of the present disclosure is particularly suitable for use in applications involving endothermic reactions. For example, the present system is suitable for use in a number of processes such as calcination reactions, phase change reaction, reactions between a powder and a gas, etc., and combinations thereof.

[0047] The system can comprise one or more reactors, each reactor being as defined in the first aspect. Accordingly, the system of the third aspect can have the attendant benefits of the reactor of the first aspect.

[0048] The system can also comprise an electricity source configured to provide electricity to the heating system of the one or more reactors.

[0049] The system can further comprise a combustion fuel source configured to provide combustion heating to the heating system of the one or more reactors.

[0050] In some embodiments of the third aspect, the electricity source may comprise grid electricity.

[0051] In some embodiments of the third aspect, the system may further comprise an indirect combustion heater configured to combust a fuel source and air. The system may be further configured to pass resultant exhaust gases to the one or more reactors so as to provide combustion heating to the one or more reactors.

[0052] In some embodiments of the third aspect, the system may further comprise a battery storage system configured to store electricity and to provide electricity to the heating system of the one or more reactors.

[0053] In some embodiments of the third aspect, the system may further comprise a carbon capture process configured to capture carbon dioxide from the combustion exhaust gases and / or a process gas from the one or more reactors.

[0054] Disclosed herein in a fourth aspect is a system for reacting a powder, wherein the reaction comprises an endothermic reaction. The system is particularly (although not exclusively) suitable for use in a number of applications, such as for the manufacture of energy intensive products that use heat for production. That is, the system of the present disclosure is particularly suitable for use in applications involving endothermic reactions. For example, the present system is suitable for use in a number of processes such as calcination reactions, phase change reaction, reactions between a powder and a gas, etc., and combinations thereof.

[0055] The system can comprise one or more reactors, each reactor being as defined in the second aspect. Accordingly, the system of the third aspect can have the attendant benefits of the reactor of the second aspect.

[0056] The system can also comprise a grid electricity source configured to provide grid electricity to the heating system of the one or more reactors.

[0057] The system can further comprise one or more other energy sources configured to provide energy to the heating system of the one or more reactors.

[0058] In some embodiments of the fourth aspect, the grid electricity may comprise a Variable Renewable Energy grid.

[0059] In some embodiments of the fourth aspect, the system may further comprise a battery storage system configured to store electricity and to provide electricity to the heating system of the one or more reactors.

[0060] In some embodiments of the fourth aspect, the system may further comprise an indirect combustion heater configured to combust a fuel source and air, wherein the system is further configured to pass resultant exhaust gases to the one or more reactors so as to provide combustion heating to the one or more reactors.

[0061] In some embodiments of the fourth aspect, the system may further comprise a carbon capture process configured to capture carbon dioxide from the combustion exhaust gases and / or a process gas from the one or more reactors.Brief Description of the Drawings

[0062] Embodiments will now be described by way of example only, with reference to the accompanying drawings in which:

[0063] Figure 1 illustrates a schematic process flow of an indirectly heated manufacturing plant, based on either an indirectly heated reactor, a fluidised bed reactor or a spouted bed reactor shaft system in which variable indirect combustion and variable indirect electric heating are applied.

[0064] Figure 2 is a schematic of a cross-section of a reactor that can be heated using electric and / or combustion heating.

[0065] Figure 3 illustrates a schematic generic energy flow within a heavy industry manufacturing site.

[0066] Figure 4 illustrates a schematic generic process flow of an industrial process with hybrid heating.

[0067] Figure 5 is a schematic of an embodiment of a reactor in which hybrid heating is used to induce reactions that proceed within a single shaft reactor and in which the heating can be provided using either AC or DC electricity or using combustion.

[0068] Figure 6 is a schematic of an embodiment of a reactor in which hybrid heating is used to induce reactions that proceed within a single shaft reactor and in which the heating can be provided using either AC or DC electricity.Detailed Description of Specific Embodiments

[0069] In the following detailed description, reference is made to accompanying drawings which form a part of the detailed description. The illustrative embodiments described in the detailed description, depicted in the drawings and defined in the claims, are not intended to be limiting. Other embodiments may be utilised and other changes may be made without departing from the spirit or scope of the subject matter presented. It will be readily understood that the aspects of the present disclosure, as generally described herein and illustrated in the drawings can be arranged, substituted, combined, separated and designed in a wide variety of different configurations, all of which are contemplated in this disclosure.

[0070] The present disclosure broadly relates to reactors and processes wherein multiple sources of heat for driving endothermic reactions may be employed. For example, the reactors and / or process may be configured to employ and / or switch between the use of electrical energy and / or energy from combustion of a fuel. Alternatively or additionally, the reactors and / or systems may be configured to employ and / or switch between the use of electrical energy from an AC source and / or electrical energy from a DC source. Accordingly, the present disclosure provides embodiments of hybrid reactors and / or systems, because the reactors and / or systems are capable of employing energy from different sources and / or are capable of switching between energy from different sources. In some embodiments, the reactions that occur within the reactors in-use may comprise solid-state reactions, such as, but not limited to, those induced by chemical changes with a gas, e.g., calcination and reduction / oxidation reactions, and / or phase changes of solid reactants or products.

[0071] Reactors that process ground particles, e.g., powders, that have been developed for heavy industry use by manufacturers primarily use combustion of fuels for heating. Such reactors include Rotary Kilns Reactors, Fluidised Bed Reactors, Spouted Bed Reactors andShaft Kiln Reactors and recently Indirectly Heated Reactors. Apart from rotary kilns, these reactors are vertical reactors. Fluidised bed reactors, spouted bed reactors and shaft kiln reactors can be used to process particles up to about several mm in size, whereas rotary kilns can be used to process larger particles of about 3 cm in size, and indirectly heated reactors are typically used to process smaller particles, e.g., up to about 250 pm in size. However, it will be appreciated that these particle size ranges are specific to the reactor design, the powder being processed, the reactions occurring, the fuels employed, etc. Many of these reactors are configured to uniformly process the solids, generally to a completion of at least 95% to about 98%. These requirements arise from limitations of the residence time for completion of the specific reaction, heat transfer rates, and the impact of any gases on the reactions. The residence time depends on various factors including the reactor length and the rate at which heat can be transferred to the particles, and this scales with the endothermic energy required for the reaction.

[0072] It is noted that, although completion rates of 95% or more may be targeted in many applications, in some situations a lower conversion rate may be targeted. For example, in some situations it can be desirable to target partial conversions of less than 90%, or even as low as about 70%. For instance, for the processing of low-grade iron ores, it is thought that targeting a metallisation of less than 90% and even as low as 70% in the reactor may be optimal to support integration with downstream processes, e.g., a downstream electric smelting furnace. As another example, for ocean alkalinity applications, it is thought that partial calcination of the particles can be advantageous. As yet another example, it is thought that targeting lower completion rates might prove cheaper for lime calcination applications.

[0073] Examples of industrial applications disclosed herein to which the hybrid heating concepts may be applied include heavy industry applications which use endothermic processes to generate heat for reactions such as, but not limited to, the production of iron and steel; lime, cement, magnesia and calcined clay for construction; alumina and activated bauxite for aluminium; other metallurgical processes such as lithium and magnesium metal; products from other critical mineral ores; production of cathode active electrode materials and anode active electrode materials for lithium ion and post-lithium ion batteryapplications; thermal treatment of black mass (intermediate product of lithium ion battery recycling); bio-chars and hard carbon processing; nickel, copper, manganese, cobalt processing; and the production of alternative fuels for low emissions combustion.

[0074] Without being bound by theory, it is though that the presently disclosed reactor and / or system configurations in which the energy source can be switched between electric and / or combustion energy can be applied to a number of known industrial processes which employ indirectly heated drop tube reactors. As will be known to and appreciated by those skilled in the relevant art, indirectly heated drop tube reactors employ indirect heating, where the indirectness of heating arises from using other processes, external to the reactor, to provide heat to the walls which radiate the heat to the particles and gases within the interior of the reactor tube. As such, in an indirectly heated reactor, there is no interaction between combustion gases (when the reactor is indirectly heated by combustion) and the powder. The operation and configuration of indirectly heated drop tube reactors are described in detail in several of the applicant’s previous PCT applications including application nos. PCT / AU2022 / 051250, PCT / AU 2007 / 000424, PCT / AU2025 / 050422 the disclosure of the specifications of which are incorporated by way of cross-reference herein in their entirety.

[0075] A common feature of indirectly heated drop tube reactors is the general use of dilute down-flows of powders in the shafts which are heated through the heated walls, generally metal alloy tubes. That is, the powder typically flows in a dilute flow regime, which can optimise the reaction kinetics and reactant conversion. The mass flux in a dilute flow regime is typically in the range of about 0.5- 1.0 kg m'2s'1and the velocity of the powder as it falls downwardly through the tube is typically between about 0.2 m / s to about 3.0 m / s. The powder typically comprises fines with particle sizes ranging from about 50 pm to about 250 pm, such as about 150 pm. However, in some embodiments, the particle sizes may be as small as 5-10 pm or as large as 500-1000 pm. It will be understood and appreciated that the particle size selected will depend on the application and the feed material properties. Gas injected into the drop tube reactor can be either in counterflow or in co-current flow with the downwardly falling powder.

[0076] The endothermic reaction, e.g., such as the endothermic reaction that occurs within the drop tube reactor, may be comprise one or more of a thermal decomposition of the minerals to produce a gas, phase changes of the minerals and / or reactions of the minerals with injected gases, e.g., to produce other gases. In some embodiments, such as where gases are injected, it has been found that the materials produced can be highly reactive because the residence time of the powders for radiative heat transfers is typically in the order of 100s. The reactive materials produced are called nano-active materials because the reactions are generally uniform within the particle because of the small particle size and the processes of sintering, called dead-burning, are suppressed because of the short residence time. A “nano-active” material refers to a material (e.g., a powder) with the same reactivity as a nano-scale powder, but with a larger (e.g., micron) particle size.

[0077] Advantageously, the heat transfer into the interior of the reactor tube from indirect heating is agnostic to the source of heat. That is, energy from either electricity and / or combustion may be employed to heat the reactor walls, so as to indirectly heat the interior of the reactor tube, as long as sufficient energy for the reaction is provided.

[0078] Without being bound by theory, it is thought that embodiments of the hybrid reactor disclosed herein may also be applicable to other drop tube reactor designs, such as fluidised bed reactors and / or spouted bed reactors. As will be appreciated by those skilled in the relevant art, these reactors have been developed using direct heating of the reactants by a combustion gas. Fluidised bed and spouted bed reactors can generally process particles up to about 1.5 mm size, which is higher than indirectly heated reactors, due to the holdup of the particles by the up-flowing internal flue gas as it is formed by combustion to supply the heat for the reaction. For hybrid reactors comprising fluidised bed and / or spouted bed designs, it is envisaged that new sources of heat may be applied through the reactor walls using a switchable combination of electric and combustion heating, and this heat is transferred to the walls of the shaft reactor and then into the interior of the reactor by radiation from the walls, as well as via convection and conduction because of the higher particle mass density fluidised bed and spouted bed reactors.

[0079] An intrinsic property of indirectly heated reactors, fluidised bed reactors and spouted bed reactors is that each of these reactors may be characterised by the steady state wall temperature of the reactor which, as will be appreciated by the skilled person, will be bespoke for each application. The steady state temperatures are measured in the shaft. In some embodiments of the present reactor, when the heating source is switched, the energy provided from combustion may be controlled to maintain a temperature of the shaft walls at or near a desired temperature, being the temperature of the walls before the switching commenced. Thus, the production capacity of the manufacturing plant may be continuous and the impact of switching the energy source on the operation of the reactor may be minimised and / or eliminated altogether.

[0080] In this regard, one or more aspects of the present disclosure may provide reactors and / or systems that allow for relatively fast switching required between electrical energy and combustion heating. Alternatively or additionally, the reactors and / or systems may allow the amount of heat provided by combustion to be increased and / or decreased to compensate for changes in the amount of electrical energy available. For instance, for grids with high variable renewable energy, the electricity available can rapidly and sometimes significantly change due to unpredictable changes in the weather. In aspects of the present disclosure, combustion energy can be used to make up for the energy difference (i.e., the difference between the energy required for the reactor to continue without significant interruption and the amount of electrical energy available from the grid). Accordingly, in some aspects, the reactor may be configured to always operate with some amount of combustion heating, with the combustion heating being increased or decreased in accordance with the energy difference. Alternatively, the reactor may be configured to only operate with combustion heating (instead or in addition to electrical energy) when required.

[0081] As above, reactors and / or systems of the present disclosure can allow for relatively fast switching between electric and combustion sources and / or can allow for combustive heat sources to be rapidly increased so as to compensate for any energy differences. The recent surge of low-cost electric energy generation plants with high VRE from solar and wind produces energy at times when solar and wind energy production is high. However, energy production may be unpredictable due to the intermittent nature of renewable sourcessuch as wind and solar. Typically, electricity produced from high VRE grids cannot be used for most consumers of power because the grid is unstable when supply exceeds demand. The surplus electric energy may be at negative cost. Advantageously, when supply exceeds demand and / or when electricity prices are low and / or negative, the present reactors and / or systems can harness surplus electric energy. The use of the excess energy can stabilise the energy grid for all users. Accordingly, the reactors and / or systems of the present disclosure may provide stability to electric energy grids with a high percentage of VRE, such as class 5 and 6 grids, because the reactors and / or systems can employ electric energy when there is a surplus of electric energy in the energy grid to supply some or all of the energy requirements of the reactor and / or system. Thus, the present reactors and / or systems may be advantageously deployed in grids that are evolving towards class 4 grids to lower the foreseeable risk, and may be deployed in class 5-6 grids as they build high VRE capacity.

[0082] It is noted that the above grid stabilisation benefits may also apply to the grid from a manufacturing process which uses its own VRE source of electric energy, through the ability to lower the plant’s demand on grid energy when the grids’ demand is high.

[0083] Advantageously, the reactors and / or systems disclosed herein can allow manufacturing plants to operate continuously, using electric energy and / or combustion energy. For instance, electric energy can be used when the cost of electrical energy is lower that of combustion energy, which also encompasses periods when the cost of electric energy is negative, and using combustion energy when the cost of electrical energy is higher than that of combustion energy. The manufacturing process may operate continuously before, during and after switching between energy sources, such that the cost of energy associated with operating a manufacturing plant wherein the reactor can use electric energy and / or combustion energy is typically lower than the cost of energy associated with operating a manufacturing plant that is only configured to use either electric power from a stabilised electricity grid, or combustion energy at a fixed cost.

[0084] Alternatively or additionally, one or more embodiments of the reactors and / or systems disclosed herein may be designed to allow for intermittent operation as a way ofoffering grid stabilisation services, whilst maintaining product quality. For example, the reactor can be switched on and use electricity as the energy source when there is a surplus of electricity in the grid. Alternatively, the reactor can be switched off (either altogether or switched to using an alternative energy source) when there is insufficient electricity available in the grid. In this regard, the reactor can be configured to allow for rapid on / off switching, fast heat-up / cool-down (i.e., to allow for intermittent operation) and ramping. It is thought that this is achievable due to the design of the indirectly heated drop tube reactors disclosed herein, which feature short residence times and can be comprised of a metal reactor tube construction and flexible / fibrous insulation (in lieu of hard refractories) and hard faces being vacuum formed, with light weight panelling.

[0085] Without being bound by theory, it is also envisaged that the reactors and / or systems of the present disclosure which are able to use electric energy and / or combustion energy may provide a low cost route to manufacturing near zero emissions products. This is because renewable energy typically has near zero CO2 emissions. Additionally, the combustion process may be based on a near zero emissions process, e.g., by using noncarbon based fuels such as hydrogen. Alternatively or additionally, CO2 capture from combustion is feasible using Carbon Capture and Use (CCSU) technologies. When CCSU is applied to Refuse Derived Fuels (RDF) and / or Biomass fuels, it is thought that some embodiments of the reactor and / or system may be able to produce negative emissions products. With the commercial advantage to operators of using reactors and / or systems that can operate using electrical and / or combustion heating and CCSU to sustainably manufacture near zero emissions products described above, it is thought that large scale manufacturers of energy intensive products and grid operators may, together, reach their individual targets for zero emissions to mitigate climate change.

[0086] It is noted that a concern for manufacturers when deciding which electrical-based energy sources to employ to power a process is the need for a stable power supply. In this regard, it will be appreciated that grid operators have the ability to curtail the supply of electric energy, thereby reducing the amount of electric energy available. The nature of electrical energy grids is that they work by balancing energy generation with energy demand, and with high VRE grids, this is done traditionally by turning down VREgeneration. This can be achieved, for example, by turning down wind turbines, or storing excess energy using, for example, big batteries, pumped hydro and interconnectors to move the power to such storage sites and to other grids. These systems have energy losses and are costly to instal. Energy generators cannot use their infrastructure when renewable energy generation is high because demand is lower. When renewable energy generation is lower than demand, even with storage, the grid operator is forced to limit supply by curtailing supply, particularly to heavy industry users under contracts with grid operators in a process called “curtailing”.

[0087] Many heavy industries that use electric energy from the grid are able to turn down their consumption of electric energy from the grid for a curtailment event. Examples of such processing systems include crushing, drying and grinding systems, and reactor ancillaries, such as electric powder feeding systems. For reactors that require heating, the heavy industry plant operators cannot use their full manufacturing capacity of their reactor systems during a curtailment event, and the plants are generally turned off or down when notified of an event, at significant cost to the manufacturer.

[0088] Persons skilled in the art of such curtailment incidents understand that such heavy industry plants using reactors that require heating often take many hours to restart because of heat losses in the reactors. Accordingly, it may be considered to be disadvantageous to use of electricity from high VRE grids for such plants, despite such electricity emitting less CO2 compared to low VRE grids. Advantageously, the present reactors and / or systems may allow for the energy for such reactors to be switched to combustion energy or other forms of stored energy, such as battery energy, during curtailment events. As a result, the need to reduce the manufacturing capacity of the reactor may be reduced and / or eliminated and the need for a full shutdown may be avoided. In addition, and as described above, the present reactors and / or systems can use excess energy from the grid when energy from the VRE grid is in excess of all demands.

[0089] In this regard, disclosed herein in one aspect is a vertically oriented reactor, the reactor comprising: a vertically oriented reactor tube; a powder input located at an upperend of the reactor tube and configured to input a powder into the reactor tube; and a heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur; wherein the heating system is configured to operate using combustion heating and electricity. Also disclosed herein is a vertically oriented reactor, the reactor comprising: a vertically oriented reactor tube; a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube; and a heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur; wherein the heating system is configured to operate using grid electricity and one or more other energy sources. In the illustrated embodiments, the vertically oriented reactors comprise an indirectly heated reactor. However, as above, it will be appreciated that other types of drop tube reactors can instead be employed.

[0090] The reactor can be configured to operate using combustion heating and / or electricity so as to provide a continuous and approximately constant supply of energy to the interior of the reactor tube. The reactor can be configured to switch between using combustion energy and electricity based on, e.g., a cost of the electricity. For example, the reactor can be configured to switch to electricity when a cost of the electricity is low (e.g., lower than the cost of combustion energy) or negative and to switch to combustion energy when a cost of the electricity is high (e.g., higher than the cost of combustion energy). Alternatively or additionally, the reactor can be configured to switch to electricity when there is an excess supply of electricity in the grid and to switch to combustion energy when there is a low supply of electricity in the grid. In this way, the reactor may help stabilise the energy supply in the grid. As above, this may be particularly advantageous when the grid comprises a high VRE grid. The reactor can be further configured to operate using both combustion energy and electricity, e.g., during a switching event in which the energy source is switched from electricity (or combustion energy) to combustion energy (or electricity), so as to maintain a constant energy supply to the reactor. In this regard, in some embodiments, the reactor may be continuously supplied with at least a low quantity of combustion energy, as this can reduce the time required to increase the supply of energyfrom combustion, e.g., when the energy source is being switched from electricity to combustion energy. In other embodiments, the combustion energy may be turned off altogether when the reactor is operating using electricity.

[0091] It is noted that the present reactor can have a number of advantages over prior art solutions for managing electricity supply in VREs, including: the use of hybrid reactors / processes means that interconnectors can be used as a back-up for grid safety, but may not be necessary to manage the supply of excess energy; large battery energy storage systems and / or pumped hydro systems may not be required; traditional grid management techniques such as curtailing, managing high ramps at sunrise / sunset by adding additional gas turbines, adding more VRE, shedding at peak times, etc. may not be required; using excess electricity, e.g., to make additional fuel or byproducts, may not be required for stability.

[0092] The scale up plant may include a number of vertically oriented reactor tubes that are organised into modules with a common powder feed and powder collection points, and a manufacturing plant of a number of modules. That is, the vertically oriented reactor may form part of a system that comprises a plurality of such vertically oriented reactor tubes which operate in parallel.Hybrid Reactor Embodiment

[0093] Turning first to Fig. 1, there is provided a schematic of a vertically oriented reactor 101. The vertically oriented reactor 101 is an embodiment of a hybrid reactor because it is configured to operate using energy from electricity and / or combustion. Powder Pl is (optionally) preheated in a solids preheater, with the preheated solids P2 input into an upper end 102 of the reactor 101. The preheated solids P2 is typically in the form of a powder and is input such that it falls downwardly through the reactor 101. The reactor 101 comprises a single shaft which is divided into five segments. However, it will be appreciated and understood that the reactor can be divided into any number of segments as required / desired. The downwardly falling powder falls through each of the segments within the reactor tube. As the powder falls downwardly through the reactor tube, the powder is1indirectly heated to a temperature at which the powder is caused to react. As above, the reaction can comprise any number of reactions, such as a thermal decomposition, calcination, reaction with an injected gas, etc. In this regard, the reactor 101 can further comprise a gas input (not shown) which allows a gas (such as a reactant gas or an inert gas) to be injected into the interior of the reactor tube. The gas input may be located at the upper end 102 of the reactor 101, i.e., such that the injected gas is caused to flow in co-current flow with the downwardly falling powder. Alternatively, the gas input may be located at the lower end 103 of the reactor 101, i.e., such that the injected gas is caused to flow in counter- current flow with the downwardly falling powder. Alternatively or additionally, the reactor 101 can comprise one or more gas inputs located vertically along the reactor tube.

[0094] The reactor 101 comprises a single shaft which is divided into five segments, wherein a wall temperature of each of the five segments is measured, e.g., using a temperature sensor (not shown), at a predetermined interval, e.g., every second. The input solids powder Pl is preheated to a desired temperature suitable for the reaction that is to occur within the reactor to give a preheated powder P2. The preheated powder P2 is injected into the reactor and falls downwardly through the reactor tube. As the powder falls downwardly through the reactor tube, the desired reaction takes place to give a product powder P3. The product powder P3 is ejected from the lower end 103 of the reactor 101. The product powder P3 can be optionally cooled to give the final reaction product P4. Energy released as the product powder P3 is cooled can be recovered for re-use. For example, the thermal energy can be used to at least partially preheat the input powder Pl .

[0095] In some embodiments, the reaction may produce a (hot) product gas PG1 which is, in the illustrated embodiment of Fig. 1, exhausted at the top 102 of the reactor 101. At the top 102 of the reactor 101, the hot product gas PG1 and powder P2 mix (or are caused to mix). This causes heat energy to be transferred from the hot product gas PG1 to the powder P2, thereby further preheating the powder P2.

[0096] The product gas PG1 exits the reactor via a gas outlet located at the top 102 of the reactor 101. The gas outlet can comprise a suitable form of solids-gas separation, wherebysolids entrained in the process gas PG1 are separated therefrom and reinjected back into the reactor 101. When gases are input into the reactor 101, these gases may also be exhausted as part of the product gas PG1. In the illustrated embodiment, and as will be described in further detail below, a portion PG2 of the product gas is reinjected into the air stream AO, with the residual gas PG3 passed to a Post Combustion Process PCP. The PCP will generally cool the residual gas PG3. The PCP can also, if required, comprise a carbon capture process in which any fossil fuel carbon is condensed and recovered as liquid CO2 in the liquid stream CL1. The cleaned gas PG4 can be disposed of, e.g., vented into the atmosphere. The liquid stream CL1 is combined with liquid stream CL2 that comprises CO2 recovered from any flue gases produced from the combustion of fuel F0. The total liquid CO2 stream CL3 can then be handled using known means, e.g., by storing the CO2 as part of a CCS process.

[0097] In some embodiments, such as when the reactor is a fluidised bed or spouted bed reactor, a fuel and air are injected into the reactor and combust within the reactor, such that the process gas PG1 further comprises flue gas. In such embodiments, the fraction of the gas PG2 that is recycled can be adjusted to maintain a desired residence time of gas particles within the reactor.

[0098] However, in the illustrated embodiment of Fig. 1, the reactor 101 comprises an indirectly heated reactor. The interior of the reactor 101 is indirectly heated via the walls 104 of the reactor tube. Each of the segments of the reactor is configured such that the walls 104 of the reactor tube can be indirectly heated by electricity E0 and / or combustion (i.e., by combusting a fuel F0 with air A0). In this regard, and as will be explained in further detail below with reference to Fig. 2, each reactor segment comprises a heating system. Each heating system comprises an electric heating element HE1, HE2...HE5 and a combustion heating element HC1, HC2...HC5. Typically, the electric heating elements HE1 , HE2... HE5 and the combustion heating elements HC1 , HC2... HC5 are spaced apart from each other. Each of the electric heating elements HE 1 , HE2... HE5 is typically located adjacent a wall 104 of the respective reactor segment. Typically, each electric heating element HE1 , HE2... HE5 comprises a resistive heating element which is configured to be powered by electricity. Alternatively, a section of the reactor wall is itself comprised ofone or more resistive heating elements, the resistive heating elements configured to be powered by electricity. In some embodiments, it is envisaged that the total electric energy EO need not be evenly split, such that each of the electric energy streams El, E2... E5 may be different and may be individually changed.

[0099] Each of the combustion heating elements HC1, HC2...HC5 is located adjacent a wall 104 of the respective reactor segment. Each combustion heating element HC1, HC2...HC5 typically comprises a combustion chamber arranged to surround at least a portion of the reactor tube and configured to combust the fuel Fl, F2...F5 with air Al, A2...A5 therewithin. Heat from the combustion of the fuel Fl, F2...F5 with air Al, A2... A5 heats the reactor walls 104. Alternatively, in other embodiments, the combustion of the fuel and air occurs separately, with the combustion chamber instead arranged to receive hot exhaust gases from a combustion process. The combustion flue gases FGO are collected and cleaned in a flue gas cleaning system FGC. In the flue gas cleaning system FGC, CO2 and other condensable gases are condensed as a liquid stream CL2. The clean flue gas FG1 is then disposed of, e.g., by venting into the atmosphere.

[0100] In some embodiments, the total fuel F0 and air A0 streams are evenly split, such that each of the combustion heating elements HC1, HC2...HC5 receives the same flow of fuel Fl, F2...F5 and air Al, A2...A5. Alternatively, in other embodiments, the flow of each individual fuel Fl, F2.. F5 and air Al, A2... A5 stream may be controllable, thereby allowing each of the combustion heating elements HC1, HC2...HC5 to receive different flows of Fl, F2...F5 and air Al, A2... A5. This can be advantageous when it is desirable to be able to provide different quantities of combustion energy to each reactor segment. The fuel F0 and / or air A0 can be preheated prior to being input into the combustion heating elements HC1, HC2... HC5.

[0101] In use, the heating system is configured to provide heat to the interior of the reactor tube, i.e., using the electric heating elements HE1, HE2...HE5 and / or the combustion heating elements HC1 , HC2... HC5. Advantageously, the reactor is configured with a controller (not shown) which is operable to switch the energy for the heating system between electric energy and combustion.

[0102] In the embodiment of Fig. 1, electric energy E0(t) can be obtained from an energy grid, such as a high VRE energy grid. In this regard, the electric energy E0(t) may be in the form of variable excess energy, i.e., because the reactor 101 can be configured to operate using electric energy when there is surplus energy in the energy grid. The electric energy is distributed to the five segments of the reactor 101 as electric energy El, E2.. E5 to each of the electric heating elements HE1, HE2...HE5. This electric energy El, E2...E5 is transformed to heat in the respective electric heating elements HE1, HE2...HE5 to produce heat energy. The heat may be generated by resistive or inductive heating elements, that may use the properties of, say, the hot metal walls, or by using resistive wiring, or by using alternative approaches such as hanging heating elements. The settings for the transformer may be set during calibration of the switching system as described below. It is noted that some electrical energy many be supplied to the reactor 101 as part of an electric baseload of power. This can increase the speed with which the energy source can be switched and also be used to power ancillaries, e.g., fans for each segment when present. Fans can be present to enhance the flow and mixing of powder / gas within each segment.

[0103] Typically, the energy source used to heat the reactor walls 104 is dictated by the electricity available from the energy grid, e.g., the high VRE grid. As explained above, when the cost of electricity is lower than the cost of producing energy from combustion and / or when there is a surplus of electricity available, it can be advantageous to use electricity as the energy source. Conversely, when the cost of electricity is higher than the cost of producing energy from combustion and / or when there is insufficient electricity supply from the grid for all consumers, it can be advantageous to use combustion as the energy source. Typically, the quantity of energy supplied by electricity is first adjusted, with the energy supplied by combustion then being changed (i.e., by the control system) in response to the change in electricity, e.g., to maintain a constant supply of energy. In the reactor 101 of Fig. 1, the reactor wall temperature is used as the target variable. That is, the quantity of energy supplied by combustion is adjusted to maintain a desired reactor wall temperature.

[0104] In this regard, the distribution of the electric energy El, E2...E5 to the electric heating elements HE1, HE2...HE5 may change, or be changed, during a switch.For example, the amount of the electric energy El, E2...E5 distributed to each of the electric heating elements HE1, HE2... HE5 may be decreased when the reactor 101 is being switched to combustion heating or may be increased when the reactor 101 is being switched from combustion heating to electric energy. Such adaptive electrical transformers do exist.

[0105] As above, temperature sensors located within each of the reactor segments are configured to continuously measure the temperature of the reactor wall. The response to the change of electric energy in each segment is a change in the combustion processes where the fuel Fl, F2...F5 and air Al, A2...A5, is combusted within each of the combustion heating elements HC1, HC2...HC5, producing thermal energy and flue gas FG0. In particular, the combustion processes in each of the combustion heating elements HC1, HC2...HC5 is adjusted so as to maintain a desired wall temperature within each of the reactor segments, i.e., as measured by each of the temperature sensors. For instance, when the reactor is switching from electricity to combustion energy, the flow rate of fuel Fl, F2...F5 and air Al, A2...A5 to each of the combustion heating elements HC1, HC2... HC5 will increase, i.e., such that more energy is produced from combustion. On the other hand, when the reactor is switching from combustion energy to electricity, the flow rate of fuel Fl, F2...F5 and air Al, A2... A5 to each of the combustion heating elements HC1, HC2...HC5 will decrease, i.e., such that less energy is produced from combustion.

[0106] It is noted that it can be desirable that the impact of changes to the electricity supply El, E2...E5 are reflected in the reactor wall temperature relatively quickly. This can enable slower adjustments to the combustion processes to be made which can, e.g., reduce the risk of overshooting the desired temperature. In some embodiments, the flow of fuel and air are continuously adjusted.

[0107] It is further noted that it can be advantageous to configured the system such that the temperature changes are measured more quickly than any other variables during a switch. In some embodiments, the target may be a response time of temperature change of ±1°C within 1 second. In some embodiments, the ability of the combustion system to respond so quickly maybe offset using energy storage systems within the manufacturing plant including within the reactor, to absorb or deliver excess heat more quickly than isfeasible by a combustion system. For example, a combustion system may take up to 5 minutes to respond to a change. Accordingly, and as will be explained in further detail below in reference to Fig. 2, in some embodiments the reactor may be able to store and release heat to respond to a fast change. It is noted that, when a heat storage system is employed, a switching event in which the energy source is switched between electrical and combustion, may be faster than about 30 seconds. When no heat storage system is employed, the same switching event may be faster than about 5 minutes. Accordingly, the use of a heat storage system can increase the speed at which the switching event can occur.

[0108] It is noted that, in the embodiment of Fig. 1, the combustion gases are drawn into a tube alongside the shaft reactor and emerge from the system as a single flue gas stream FGO. This configuration means that, with the exception of the lowermost reactor segment, all of the upper segments are coupled. Without being bound by theory, it is thought that the condition that controlling the reactor wall temperature during the switch such that the reactor wall temperature is equal to the reactor wall temperature prior to the switch is sufficient to find a reasonable new steady state condition for each segment, and, as a result, the need to solve the energy and mass balances for each segment may be avoided. This can account for the many timescales of processes of reaching a steady state, including the slow settling of optimum heat recuperation or reactants and products and combustion processes including the minimisation of the total combustion energy demand. Another advantage of using the reactor wall temperature profile as the measure to control the combustion energy during switching is that, in theory, the reactor wall heat transfer is the only reaction variable that changes during a fast switch. Other processes, such as preheating and CO2 capture, are designed to change slowly and can be operator controlled for the plant as a whole, as would be the case for a plant operating without switching.

[0109] In some embodiments, it is thought that, to find a steady state solution, the search algorithm can use a structured search based on data which may lead to an Artificial Intelligence search process that, over time learns the preferred solution which leads to a hierarchy of fast solutions that may be chosen by a SC AD A system to meet other criteria, such as the solution which selects the minimal thermal stresses in the shaft reactor as a whole.

[0110] It is also noted that the calibration of the vertical tube reactor is an important operational consideration. For example, with for fluidised bed and spouted bed reactors, the heat demand for combustion at high or low excess electricity demand should be such that the bed neither collapses nor elutriates significantly during the switch between electricity and combustion energy. Without being bound by theory, it is thought that there are solutions to this possibility, such as reinjection of at least part of the product gas stream PG2 described above. Without being bound by theory, it is envisaged that both indirectly heated reactors and fluidised bed / spouted bed reactors could be deployed in one bespoke manufacturing plant to retain the benefits of each process where applicable.

[0111] In this regard, in terms of scale-up, it is envisaged that a plurality of such vertically oriented reactors 101 of Fig. 1 can be employed in parallel in a manufacturing process in which the reaction occurs within the shaft of each reactor. Each reactor is refractory lined and may be configured so that each reactor may be operated independently. An alternative embodiment, not shown, is that the reaction occurs within the spaces between shafts, and each shaft is used solely to generate the indirect electric heating and indirect combustion heating.

[0112] The reactor 101 is primarily described herein with reference to a manufacturing process which employs a plurality of such reactors 101, such that the reaction occurs in a multi-vertical shaft system. The system can be comprised of .s vertically oriented reactors 101, arranged in m modules, wherein each module has a common feed of solids and gases which are bespoke for the industrial processes, and the plant has p systems of the modules of reactors altogether. The temperature measurement of reactor walls is measured at n points within each reactor tube to provide data to control the amount of energy being supplied by electricity and / or combustion. That is, for the plant in this example there are smpn temperature control points. These temperature control points can be, e.g., used by the plant operators to set core production processes of the plant to enable fast switching. A segment of the vertical shaft is defined to be a region of the shaft in which the temperature of the shaft walls is known to not vary significantly within or around the perimeter of the segment. As described above, a controllable fraction of indirect electrical heating of the shaft walls is applied to each of the smpn segments. The fraction of electricalheating is changed (i.e., increased or decreased) during a switch, with a compensation of the total energy by combustion heating (i.e., the quantity of energy from combustion is decreased or increased to maintain the desired reactor wall temperature). It is thought that the overall control of the plant using these requirements is robust because smpn»2.

[0113] In this regard, the process of increasing or decreasing the energy from combustion to match the electrical energy change is managed by maintaining the reactor wall temperature surfaces at or near the operating temperature condition before switching. A benefit of controlling the switching process by measuring and reducing temperature transients in each reactor segment is that the temperature is readily measurable for such control purposes. It is noted that, in some embodiments, an ideal switching process is one in which the wall temperature profiles within each reactor are maintained at the same profile during the switching process.

[0114] In some embodiments, it is envisaged that the switching will not require operator control and that the reactor is configured with automatic control mechanisms, e.g., via a suitable controller. Consider a case in which a plant is characterised by 6 reactors in a module, 3 modules in a plant, and 10 segments per reactor tube. The total number of temperature measurements is 180 which are recorded by a SC DA system in, e.g., 1 second intervals. Typically, the manufacturing plant as a whole is based on maintaining an average constant production of products over all the 18 reactor tubes in the plant as the switch is made. The selection of options can be caried out using the SCADA system which takes a command to switch the electrical power higher or lower, and the transformer system delivers to each reactor segment a new electrical energy command to which the electrical heating system quickly responds. The energy provided from combustion is then changed, i.e., to maintain a constant temperature profile within each of the reactors. In this regard, the first action may be to the change the fuel input to each combustor segment, followed by iterative changes to the air injection to rebalance the temperature, which would result in changes to the combustion settings of all segments because they are all coupled, in the present case where a combined combustion exhaust is collected. The SCADA system would adjust such parameters, i.e., fuel and air flow, to minimise the changes of temperature in each reactor segment. It is noted that large electrical energy changes willtake longer to settle. The use of energy storage systems, in the reactor or other systems can also be used to help maintain a constant energy supply during switching.

[0115] Turning now to Fig. 2, a schematic cross-section of a segment of the reactor 101 of Fig. 1 is provided. The cross-section illustrates the reactor tube 201, surrounded by the systems which enable (a) the transfer of heat to configure hybrid heating of a reactor segment, and (b) the measurement of one temperature of a shaft reactor segment to enable control of the switching. More specifically, the reactor tube 201 is surrounded by an annulus that comprises an electrical heating system 202 and a combustion heating system 203. In the embodiment of Fig. 2, there is a 180° separation between the electric heating system 202 and the combustion heating system 203. The heating systems 202, 203 are separated by segments comprised of a thermal energy storage material 204. It is noted that any material occupying the space between the heating systems 202, 203 will store heat energy. In some embodiments, the material is comprised of a material with a high thermal conductivity and a high energy storage capacity, allowing for a fast thermal response, such as a silicon metal in a system with very low thermal expansion so that variations do not exert thermal stresses. In such embodiments, the role of the thermal energy storage material 204 is to quickly provide energy to the reactor tube 201 or absorb energy from the reactor tube 201 so as to reduce variations in the measured temperature during switching.

[0116] To allow energy to be transferred to the reactor tube 201, the reactor walls 206 are comprised of a highly thermally conductive material. In use, heat is transferred from the heating systems 202, 203 to the reactor tube 201 via the reactor walls 206. Similarly, heat stored in the energy storage elements 204 is transferred to the reactor walls 206.

[0117] The exterior of the energy storage material 204 and, optionally, the heating systems 202, 203 are typically surrounded by a refractory material and an external metal covering 207 to minimise heat losses.

[0118] In the embodiment of Fig. 2, the temperature measurement system 205 is located on the exterior surface of the electric heating system near the reactor wall 206. Thereactor wall is designed to be thin enough such that the heat conduction through the reactor wall is sufficiently fast so that the temperature gradient through the reactor wall is small. The temperature measurement system 205 is configured to convey the temperature information (e.g., in 1 s increments) to the SC AD A (or equivalent) system. In some embodiments, the temperature measurement system 205 is configured to pick up a change of ±1°C in 1 second and convey that information to the SCADA system.

[0119] In some embodiments, both heating systems 202, 203 are operational at all times, such that the combustion process does not commence with a start-up of no combustion, particularly with combustion flames. Additionally, it can be advantageous if the electric heating system is configured such that electric heating is faster than combustion heating so that “hunting loops” are able to be minimised and if the reactor is configured such that the electrical energy distribution can be fixed, e.g., by a transformer setting that can be calibrated periodically to deal with issues such as wall fouling. The placement of temperature measurement system 205 in Fig. 2 is advantageous because allows temperature variations that occur as a result of changes in the electric heating system 202 to be efficiently detected and, in addition, the risk of the temperature measurement system 20 being corroded by either the reactor materials in the reactor tube 201 or in the combustion system 203 is minimised and / or eliminated. It is noted that, alternatively or additionally, the temperatures at other points around the reactor tube can be measured and / or other configurations of distributed temperature measurement systems can be employed.

[0120] It is envisaged that the design of the system in Fig. 2 will use finite element analysis (FEA) methods to ensure that the collapse of the reactor from stresses, in particular the buckling of the reactor walls 206 is mitigated, not only to deal with fast switching, but also with start-up and shut down processes. The data from the FEA analysis of the whole structure is bespoke for each reaction / reactor and is stored in the SCADA system to select options for switching that minimise the thermal stresses. It is noted that the width of the heating elements 202, 203 is a design consideration, with the requirement that the segment widths are sufficiently small that the measurement of one temperature per segment leads to fast convergence of the heat distribution during switching and the thermal stresses along and around the shaft are minimised. One approach is to rotate the system shown in Fig. 2by 90° between adjacent segments in a spiral down the shaft. The FEA analysis can also take into account such measures to reduce thermal stresses. In some embodiments, it is thought that each of 202, 203 and 204 can be constructed with a continuous spiral where the feed-ins of electrical energy, air, fuel, flames and flue gas, and temperature measurement systems define the segments.

[0121] In Fig. 2, in some embodiments, the reactor is designed to minimise the radial and vertical variations in each segment. For example, the design of the electrical heater, the combustion heater and the optional energy storage systems, with the presence of the reaction materials can be such that a profile with low radial variations of temperature during switching, turn down and turn on processes is generated. An example is the design of the combustor system, which may be based on either flameless combustion or radially flat flame systems.

[0122] It is noted that indirectly heated drop tube reactors inherently require small shaft diameters, i.e., to ensure heating of the powder within the reactor shaft by radiative heat transfer. As a result, large manufacturing plants using indirectly heated drop tube reactor technology require many shafts. Such an approach may use modules of reactors, wherein each the reactors of each module are fed by a common grinding system using pneumatic conveying. For example, each module can comprise 10 reactors.

[0123] As an example, consider a plant producing lime from limestone using the hybrid reactor described above with reference to Figs. 1 and 2 and wherein the reactor comprises an indirectly heated reactor. As above, the indirectly heated reactor uses electric energy and natural combustion to process the limestone. The limestone powder input Pl typically has a mean particle size in a range of 50-250 pm, such as about 150 pm although, as above, the mean particle size may be as low as 5-10 pm or as high as 500-1000 pm, and is injected into an upper end 102 of the reactor 101, such that it falls downwardly through the reactor. A CO2 process gas stream is generated as the limestone is calcined in the reactor. The reactor 101 operates in counterflow such that the process gas stream rises. The process gas PG1 exits the reactor 101 at the upper end 102 thereof via a gas outlet. Theprocess gas PG1 is cleaned in the post combustion process PCP, thereby producing a pure CO2 stream that can be cooled for liquid CO2 production. High temperature steel is used for the reactor walls 104. The maximum reactor wall temperature during operation is typically about 1050°C, to limit the impact of the creep in a vertical metal reactor. For limestone calcination, the reactor typically comprises two segments of about 20 m height each with bellows connecting the two sections and has a diameter of about 1.8 m. As an example, for the production of 7 tonnes / hr of lime in one reactor tube, calcination process heat loss of up to 30% may occur, primarily due to inefficient heat recuperation, with an overall heat consumption of about 8.8 MW per reactor tube. For a plant with 6 reactor tubes per module and 4 modules per plant, the total heat consumption would be about 210 MW for a lime plant producing about 170 tph of product. This estimate does not include grinding energy and ancillary costs associated with CCSU for the CO2 processing or specific fuel side processes. Such a plant may have 10 reactor segments per reactor tube, so that the SCADA system would report 240 temperature measurements per second. The maximum switch to electrical energy may be, say, about 95% of the heat consumption, with the remaining 5% of the heating energy being supplied by the combustion system, i.e., such that the combustion system is always active. In this embodiment, the lime plant can switch 200 MW of power between electricity and combustion energy. For a grid supplying 1.0 GW of stabilised electrical power to customers, this plant can consume 20% of excess power at a negative cost. Such a plant may be used in the stabilisation of class 5 or class 6 variable renewable energy grids. It is noted that limestone calcination is the first step of cement production, and most grids of this scale will support a cement plant using a larger consumption of lime than assumed above.

[0124] As another example, a manufacturing plant may comprise 5 modules of 6 vertical reactor tubes processing and average of about 10 MW of heat per reactor tube, with each reactor tube having a 10-30 m height with controllable heating segments of not less than about 0.5 -1.0 m in length and operating with a measurable average temperature of about 1000°C with a control of temperature of ±2°C within each segment. Such a plant would have a name-plate capacity, defined by the full capacity, of about 300 MW. In this example, the plant may have about 600 controllable heating segments to enable switchingof about 95% of the heating energy, equivalent to 285 MW, in one switching event with a maximum response time of 5 minutes. The remaining 5% of energy, which is deemed to be non-switchable, arises from the desirability of maintaining both the electric and combustion systems operating at all times to maintain the fast-switching.

[0125] Such a plant can moderate the switchable energy from the grid to a maximum of 285 MW (and to any amount below that) with a precision of ± 0.001 MW in less than several minutes. The modest use of energy storage systems or small batteries to store excess electrical energy or provide additional energy can enable the switching to occur in seconds. Such intermediate storage systems are to the benefit of the grid. In some embodiments, the plant may be operated on AC power so the plant does not require expensive AC to DC transformers, in which case the bridging heat source may by a fast response energy storage system.

[0126] Each phase of a 3 -phase electrical power system maybe hard wired to 1 / 3 of the controllable segments, and the wiring of these segments can be such that the phase shift for each electrically active segment can be selected such that the phase of the electric process can be controlled by the selection of heater shaft elements to be maintained to achieve the desired outcome of switching without change of the phase during switching, while also maintaining the amplitude of each phaseHeavy Industry Manufacturing Site

[0127] Turning now to Fig. 3, a block flow diagram of an example of energy flows within a manufacturing site 300 is illustrated. The site 300 employs a hybrid heating system, in that it is able to use electricity from an electricity source and / or combustion energy to provide energy to a manufacturing system 307. Typically, the manufacturing system 307 employs a hybrid reactor, such as the hybrid reactor described above with reference to Figs. 1 or 2, or the hybrid reactors described below with reference to Fig. 5. For a larger scale manufacturing system 307, the system 307 can comprise a plurality of such hybrid reactors which operate in parallel. Typically, the system 307 is on in which there is an endothermic reaction occurring within the reactor(s).

[0128] The site 300 is connected into an electricity grid, in this case, a VRE grid 3-1. The VRE grid 3-1 supplies electricity in the form of high voltage AC electricity 301. It is noted that other grid users (not shown) can also be supplied with electricity from the VRE grid 3-1 at the same time. In the illustrated embodiment of Fig. 3, the site 300 is also connected to a local VRE source 3-2. The local VRE source 3-2 typically comprises a renewable energy source, such as wind and / or solar. The site 300 also receives supply of fuel 3-3 that is suitable for combustion. The fuel 3-3 is stored as on site in a suitable fuel storage 308.

[0129] During operation, AC electricity from the VRE grid 301 is transformed and rectified 304, with lower voltage DC electricity produced. A first portion 303 of the lower voltage DC electricity is used to provide electric heating energy to an electric heater system 310 of the manufacturing plant 307. For example, the electric heater system 310 can comprise one or more of the electrical heating systems of a hybrid reactor (or modules of hybrid reactors), such as the hybrid reactor described above with reference to Figs. 1 and 2 or as described below with reference to Fig. 5. In this regard, electricity 303 is provided to the electric heater system 310 when the heater system of the hybrid reactor (or reactors) is using electricity as the energy source (and when the electricity is being sourced from the VRE grid 3-1). When the heater system of the hybrid reactor (or reactors) is using combustion as the energy source, then there will be no electricity 303 flow to the electric heater system 310. A second portion 302 of the lower voltage DC electricity can be used to provide electric energy to the manufacturing plant’s battery energy storage system 306. It is noted that electricity 302 need not be continuously supplied to the battery energy storage system 306. For instance, electricity 302 can be supplied to the battery energy storage system 306 when there is surplus electricity in the VRE grid 301 and / or when the battery energy storage system 306 is not fully charged. Electricity from the VRE grid 301 can also be supplied to the various ancillaries within the manufacturing system 307, as will be understood by those skilled in the relevant art.

[0130] The manufacturing system 307 further comprises a combustion heater system 311. For example, the combustion heater system 311 can comprise one or more of the combustion heating systems of a hybrid reactor (or modules of hybrid reactors), suchas the hybrid reactor described above with reference to Figs. 1 and 2 or as described below with reference to Fig. 5. In this regard, fuel 312 from the fuel store 308, along with air (not shown), is passed to the combustion heater system 311, when the hybrid reactor (or reactors) is using combustion as the energy source. In some embodiments, the fuel and air are combusted within an external combustion chamber (not shown), with the heat flow from the combustion chamber used to heat the heater system 311. In other embodiments, the fuel and air are combusted within the heater system itself.

[0131] As above, the site 300 can be connected to a local VRE source 3-2. The local VRE source 3-2 typically produces electricity on an intermittent basis, i.e., because it primarily relies on renewable sources to generate electricity. Electricity from the local VRE source 3-2 is passed through a high voltage equipment generator 305, which steps up low voltages to higher voltages. The electricity is then stored in the battery storage system 306. During operation of the manufacturing system 307, the electric heater system 310 can use electricity 313 from the battery storage system 306 when it is operating using electricity and, e.g., when the VRE grid 3-1 does not have sufficient electricity available to meet demand. Alternatively or additionally, electricity 313 from the battery storage system 306 can be used as an energy source during a switching event, i.e., when the energy source for the hybrid reactor (or reactors) is being switched between electricity and combustion. For example, when there is a sudden drop in the electricity available from the VRE grid 3-1, electricity from the battery storage system 306 can be used to supplement the grid electricity. The amount of energy being supplied by the battery storage system 306 can then be decreased in a controlled manner, as the amount of energy from combustion is being increased, thereby smoothing the transition from electricity to combustion energy.

[0132] In the manufacturing system 307, the heat is used to manufacture products, e.g., within the hybrid reactor (or reactors). In addition, combustion gases can be processed so that the combustion energy is consumed and any CO2 emissions are captured as products, e.g., for use or sequestration.

[0133] The energy flows in Fig. 3 that provide the energy within the site 300 are thus from multiple sources. Firstly, electrical energy is provided by the VRE grid 3-1.31Transformed and rectified 304 electricity from the VRE grid is either used directly 303 in the electric heater system 310 or is stored in the battery storage system 306. Furthermore, when no electrical energy from the VRE grid is required, then these energy flows 301, 302, 303 can be switched off. Secondly, electrical energy is sourced from the local VRE source 3-2. The electrical energy from the local VRE source 3-2 can be used directly by the electric heater 310 (not shown) or stored in the battery storage system 306. Furthermore, when no electrical energy from the local VRE source is required, then the generator 305 can be switched off. Thirdly, combustion energy is sourced from the combustion of fuel 3-3 with air (not shown). As described in detail with reference to the various embodiments of the hybrid reactors, the energy source can be switched between electricity and combustion as required to ensure continuous or close to continuous manufacturing. The type of energy employed can be selected depending on various factors, including electricity price, electricity availability, etc.

[0134] Advantageously, various embodiments of the hybrid reactors disclosed herein are able to quickly switch between the use of these various energy sources. It is thought that, in some scenarios, the switching process may occur about twice a day.

[0135] It is noted that, where fuel combustion is used, the switching time between the use of electricity and combustion can be reduced by anticipating changes in electricity supply. For example, by using local weather forecasts to understand when solar and / or wind generated power may decrease. Alternatively or additionally, a mixture of fuels may be used to quickly boost production of combustion heat. As a further alternative, electricity from the battery storage system can be used to supplement grid electricity if the quantity of grid electricity available suddenly decreases. It is advantageous to switch between energy sources in such a way that the energy being supplied to the manufacturing system remains approximately constant such that the reactor temperature is maintained during switching. This can reduce the impact on production during switching.

[0136] It is noted that, in certain locations, an electricity grid may not exist or may use too much fossil fuels to meet the manufacturer’s requirement for products made withlow to zero emissions sources, or the cost of grid power is too high. In such locations, the use of a local VRE source may be advantageous.Hybrid Manufacturing Plant Process Flow Diagram

[0137] Turning now to Fig. 4, a block flow diagram of another example of mass and energy flows within a manufacturing site 400 is illustrated. In the manufacturing site 400 of Fig. 4, the manufacturing system comprises a powder reactor system 403 which, in the illustrated embodiment, is in the form of an indirectly heated drop tube reactor that is configured with a hybrid heating arrangement. That is, the drop tube reactor is configured to use energy from electricity and / or combustion to heat powder as it falls downwardly through the reactor. It is noted that although Fig. 4 is described with reference to an indirectly heated reactor, the same concepts can be applied to other reactor configurations, such as fluidised bed reactors, spouted bed reactors, shaft reactors, etc., wherein each of the reactors employs some degree of indirect heating.

[0138] At a high-level, the primary inputs to the reactor 403 of Fig. 4 are the input powder 4-1 and a compressed input gas 4-2 (if required). The primary outputs from the reactor 403 are the solid product 4-3, a condensed product gas 4-4 and any product uncondensed gases 4-5. The manufacturing site 400 comprises a combustion heating system 412, with the primary inputs being fuel 4-6 and an oxidising gas, such as air, 4-7 and the primary outputs being clean air 4-8 and scrubbed waste materials 4-9. The manufacturing site 400 is further provided with electrical power from a grid, such as a VRE grid 4-10.

[0139] The input powder 4-1 is optionally passed through a powder grinder circuit 401 in which the powder is ground into the desired particle size distribution required for the reactor 403 and hopper 402. When the reactor 403 comprises an indirectly heated drop tube reactor, the powder is typically ground to particle sizes between about 50 pm to about 250 pm. The ground powder 413 is stored in the hopper 402.

[0140] The reactor 403 typically comprises a hybrid reactor of the type described above with reference to Figs. 1 and 2 or as described below with reference to Fig. 5. In thisregard, the stored powder 414 is injected in the upper end of the reactor 403 and falls downwardly through the reactor. As will be described in further detail below, heat energy is indirectly provided to the reactor 403, e.g., via the reactor walls. The heat energy heats the downwardly falling powder so as to cause the powder to react. Typically, the reaction comprises an endothermic reaction. Optionally, a gas 415 is injected into the reactor 403. For example, the gas 415 can comprise a gas that is to be reacted with the powder in the reactor 403. Alternatively, the gas 415 can be an inert gas or a gas that suppresses unwanted side reactions within the powder. Typically, the gas 415 comprises a compressed gas and is stored onsite in a gas storage 406 area. The gas 415 can be injected into a lower end of the reactor 403, i.e., such that the powder and gas are in counter-current flow within the reactor tube. Alternatively, the gas 415 can be injected into an upper end of the reactor 403, i.e., such that the powder and gas are in co-current flow within the reactor tube. As a further alternative, the gas 415 can be injected at multiple injection points along a length of the reactor 403. When a gas 415 is used, the gas is typically injected so as to maintain a desired operating pressure, which is about 1 bar in some embodiments.

[0141] As the powder 414 falls downwardly through the reactor 403, the powder 414 reacts, thereby forming a hot powder product. The hot powder product 416 is collected from a lower end of the reactor 403. The hot powder product 416 can be collected either continuously or periodically. The hot powder product 416 is passed to a powder product clean-up system 404 in which the powder is cleaned. For example, the powder may undergo one or more of cooling, drying, further grinding, etc. Typically, the hot powder product 416 is at least cooled, with the heat energy 4-H1 from the cooling of the hot powder product 416 being recovered for re-used in, e.g., in the reactor 403. The cleaned powder 417 is stored in a powder product hopper 405 and discharged as the powder flow output 4-3.

[0142] Process gas 418 is collected from a gas exhaust located at an upper end of the reactor 403. The process gas 418 can comprise gas produced by the reaction of the powder (e.g., when the reaction is a calcination reaction, CO2 will be produced in the reactor), as well as gas 415 injected into the reactor 403 that did not react with the powder. Typically, entrained powder is separated from the process gas 418, e.g., using a suitable gas-powder separator (not shown), with the separated powder reinjected into the reactor403. The process gas 418 is passed to a reactor gas condenser 407 in which condensable components of the process gas 418 are condensed. For example, when the process gas 418 water and / or CO2, such gases may be condensed in the reactor gas condenser 407. When the process gas 418 comprises more than one condensable gas, the condensable gases may be condensed as a single product or may be condensed as individual products. Condensing the gases as individual products may be advantageous because, e.g., condensed water can be collected for use as process water and condensed CO2 can be collected for use or sequestration. In this regard, the condensed gas 4-4 (or gases) is typically collected. The uncondensed gas 4-5 may be suitable for venting into the atmosphere. The energy 4-E2 required to operate the reactor gas condenser 407 is typically sourced from the VRE grid 4-10. Thermal energy 4-H3 produced from the reactor gas condenser 407 is recovered for use in the process, e.g., for heating the reactor 403 and / or preheating the ground powder 414.

[0143] In the illustrated embodiment of Fig. 4, the reactor 403 comprises a hybrid reactor which is configured to use energy from electricity and / or combustion. In this regard, the reactor 403 comprises a heating system which is comprise of an indirect electric heater 409 and an indirect combustion heater 412 which are each configured to supply energy 4-H4, 4-H5 respectively to the heating system of the reactor 403. In Fig. 4, the indirect heaters 409, 412 are shown as separate components so that the flow of energy within the site 400 can be more easily understood. However, it will be understood and appreciated, that the indirect heaters 409, 412 can form part of the reactor 403, i.e., as described above with reference to Figs. 1 and 2 and as described below with reference to Fig. 5. The indirect heaters 409, 412 are each configured to provide heat to the reactor 403. In particular, the indirect heaters 409, 412 are each configured to heat the walls of the reactor 403. Heat from the heated reactor walls is then radiated into the interior of the reactor tube, causing the downwardly falling powder and flowing gas (when present) to be heated. In this way, the powder and gas (when present) are indirectly heated.

[0144] The energy required for the reactor 403 can be provided by electricity, such as grid electricity or electricity stored in batteries, and / or by combustion heating. In this regard, the site 400 is connected to a local electricity grid 4-10. Typically, the grid 4-10provides electricity in the form of AC 50 Hz electricity. The grid 4-10 is typically a high VRE grid, wherein electrical energy is generated by variable energy generators, such as solar and wind generators (not shown). The grid electricity 4-10 flows from a local grid node 408. It is noted that, typically, grid electricity 4-E1, 4-E2 is used to operate the ancillaries of the site 400, including, respectively, the powder grinding 401 and the reactor gas condenser 407, as well as any other electrical ancillaries not illustrated in Fig. 4 as required.

[0145] Importantly, electricity 4-E4 from the node 408 can be directly used as an energy source for the indirect electric heater 409, which then supplies energy 4-H4 to the reactor 403. In addition, electricity 4-E3 from the node 408 can be used to charge a site battery storage system 411. For example, electricity 4-E3 can be used to charge the battery storage system 411 when there is an oversupply of electricity in the grid 4-10 and / or when the battery storage system 411 requires recharging. In some embodiments, the battery storage system is instead able to be charged using electricity generated from renewable energy generators, such as solar and / or wind. As explained above, the indirect electric heater 409 can alternatively or additionally use electricity 4-E5 from the battery storage system 411 to generate the heat 4-H4, as required. For example, during switching events to smooth the supply of electricity. It is noted that electricity 4-E5 from the battery storage system 411 will typically be in the form of DC electricity.

[0146] The site 400 is also provided with a combustible fuel source 4-7, which can be stored onsite in the site combustion storage system 410. The configuration of the combustion storage system 410 will depend on the type of fuel source 4-7. For example, the combustion storage system 410 can comprise hoppers for solid fuels such as biomass or waste, tanks for liquid fuels or compressed gas storage systems for gaseous fuels. The storage system can be refilled on timescales of days or longer, depending on the storage capacity and the rate of use of the fuel. Combustion fuel 419 is then passed to the indirect combustion heater 412 as required, e.g., when it is required or desirable to provide combustion energy 4-H5 to the reactor 403. The combustion fuel 419 is mixed with a suitable oxidant 4-6, such as air, and is combusted. Heat 4-H5 from the combustion of the fuel and oxidant is used to heat the reactor 403. For example, the combustion can take placein a chamber that is located adjacent a wall of the reactor. Alternatively, the combustion can take place in an external chamber, with the hot flue gas then passed through a chamber that is located adjacent a wall of the reactor. In either case, the flue gases 420 are collected and treated in a gas clean-up system 413. In the gas clean-up system 413, excess heat energy 4-H2 is extracted and reused 4-H2 to partially heat the reactor 403. In addition, toxic and environmentally harmful gases, including CO2, SOx and NOx, are removed. When CO2 is present, the CO2 is condensed and collected 4-8 for reuse or sequestration. The remaining exhaust gas 4-9 is, e.g., vented into the atmosphere.

[0147] The plant operator of the site 400 can switch the heat source for the heating system of the reactor 403, e.g., between electrical heating 4-H4 (including selecting AC-grid electricity 4-E4 or DC battery energy 4-E5) and / or combustion energy 4-H5. Alternatively or additionally, the site 400 / reactor 403 can be configured with a controller which automatically switches the energy for the heating system of the reactor 403 between the use of electric energy 4-H4 (including selecting AC-grid electricity 4-E4 or DC battery energy 4-E5) and combustion energy 4-H5. For example, as described above, the energy source can be switched between electricity and combustion depending on a price and / or availability of the electricity. As above, the switching between the energy sources can be so as to maintain a constant or near-constant supply of energy to the heating system of the reactor 403. Advantageously, this can help maintain steady production within the reactor 403 before, during and after switching energy sources.

[0148] It is noted that the heating of the reactor is primarily from the heat flows 4-H4, i.e., electricity from the grid and / or the battery, and / or the heat flow 4-H5, i.e., combustion energy. Smaller quantities of heat energy are provided via the recovered energy streams, i.e., energy recovered from the hot product powder 4-H1, the hot process gas 4-H3 and from the combustion flue gas 4-H2. In the event that the switching occurs in such a way that the primary heat flows to the reactor remain approximately constant and at steady-state conditions, it is not anticipated that the heat flows 4-H1, 4-H2 and 4-H3 will vary significantly during a switching event, i.e., because the process operates under steadystate conditions.

[0149] It is noted that the site 400 can be employed for any number of industrial processes, including those already described above. In one embodiment, the site 400 can be used to make the highly reactive CO2-sorbents of lime, dolime or mixtures thereof from solid inputs such as limestone or dolomite, or mixtures thereof. The CO2 sorbents can then be used to capture the CO2 in the flue gas stream, and CO2 emitted by the powder, as lime or dolime. Moreover, it is noted that the lime or dolime may be used in any pyro-process from carbon-based fuels to provide a near zero emissions combustion process.Hybrid Reactor Alternate Embodiment

[0150] Fig. 5 is a schematic cross-section of an alternative embodiment of a hybrid reactor 550. The hybrid reactor 550 comprises a heating system that is configured to operate using electricity and energy from at least one other energy source. For example, in the illustrated embodiment of Fig. 5, the hybrid reactor 550 is configured to operate using electricity and combustion. That is, the heating system is configured to operate using combustion heating or electricity or both combustion heating and electricity simultaneously. The electricity can be grid electricity, such as electricity from a high VRE grid, and / or stored electricity, such as electricity from a battery.

[0151] The reactor 550 is an indirectly heated drop tube reactor. The operation and configuration of indirectly heated drop tube reactors are described in detail in several of the applicant’s previous PCT applications including application nos. PCT / AU2022 / 051250, PCT / AU 2007 / 000424, PCT / AU2025 / 050422 and so will not be described again in detail here. In this regard, the reactor 550 comprises a cylindrical reactor shaft. In one embodiment, the reactor walls that form the shaft 550 are comprised of a steel alloy, 253 MA, with a wall thickness that can, aided by a surrounding structure, substantially and safely support the reactor 550 up to an operating temperature of about 1050°C.

[0152] The reactor 550 comprises an input powder hopper 500 located at the upper end thereof. The input powder hopper 500 is configured input powder 5-1 into the reactor shaft 515, e.g., via an input powder feeder 501. The powder 5-1 is typically a ground powder. In some embodiments, the reactor 550 comprises a powder preheater configuredto preheat the powder input at the upper end of the reactor prior to the powder being input into the shaft 515. The powder preheater can be configured to preheat powder using energy from elsewhere in a process, such as heat energy from the powder product output from the reactor, an exhaust gas from the reactor and / or an exhaust gas from a combustion process.

[0153] The powder is input into the reactor shaft 515 such that it is caused to fall downwardly through the reactor shaft 515. In the illustrated embodiment, there is no gas input to the reactor 550. It is noted that such a configuration can be employed when there is no need to inject gases into the reactor 550. Examples of such processes include the common industrial processes of calcination of powder inputs, such as is used for the production of lime, calcined cement meal, dolime and magnesite; the dehydroxylation of powders to make alumina from gibbsite for aluminium production, and calcined clays; and phase changes of minerals such as spodumene for lithium production. However, it will be understood and appreciated that, in some variations, the reactor 550 can comprise a gas input, which allows a process gas to be injected into the reactor 550. Such variations can be used in processes where it is required or desirable to inject a process gas. Examples of such processes include the production of HDRI from iron ores or copper metal production from copper oxides using injected hydrogen.

[0154] The reactor 550 of Fig. 5 is fed, typically in units of kg s-1, by ground powder 5-1 at an input steady state mass flow and is processed in the reactor 550 to a produce a hot product powder and a hot gas 5-3. During steady state operation, it can be assumed that the mass flows between the inputs and outputs are preserved on the basis that fouling is not significant. As above, the powder falls downwardly through the shaft 515. The shaft comprises a spinner 507 located at the upper end thereof. The spinner 507 is comprised of rotor blades which, in-use, are located on a vertical axis of the reactor tube and are configured to spin around the vertical axis of the reactor tube. In some embodiments, the spinner 507 acts as a dispersion apparatus, whereby the rotor blades cause the powder to become dispersed the powder impacts the rotor blades. More specifically, the spinner 507 is configured to break up clumps of powder and to enhance the dispersion of particles throughout the reactor tube. This may help promote pluming and increased residence time within the reactor tube, i. e. , by reducing clustering of the particles,and enhance heat and mass transfer within the reactor tube, thereby increasing calcination / reaction rates and productivity.

[0155] In some of these embodiments, the spinner 507 may be further configured to act as a comminution apparatus, whereby the rotor blades cause a particle size of the powder to be reduced as the powder impacts the blades, such that the powder of reduced particle size leaving the rotor blades falls downwardly into the heated interior of the reactor tube. Alternatively or additionally, the spinner 507 can also act to draw exhaust process gas from the shaft 515 into the gas exhaust 516, which is also located at the upper end of the reactor 550.

[0156] It is noted that, in alternative embodiments, the spinner 507 may be replaced by other dispersion mechanisms that are likewise configured to disperse the powder throughout the reactor shaft 515 and break up clumps of powder. The design and configuration of dispersion mechanisms will be known to and appreciated by those skilled in the relevant art. Such dispersion mechanisms include static breakers (e.g., baffle and plate type geometry) and pneumatic / gas breakers. As an example, it is thought that a gas may be injected into the upper end of the reactor shaft 515. The gas can comprise a hot gas which has been heated using heat recovered from elsewhere in the process, e.g., from cooling the powder product. The gas may be injected in the upper end of the reactor shaft 515 so as to aid powder dispersion, preheat the powder and support heat recovery.

[0157] As will be described in further detail below, as the powder falls through the shaft 515, the powder is heated by the heating system of the reactor 550 and is caused to react. In particular, the heating system indirectly heats the powder by heating the reactor walls 518. The heated reactor walls 518 then radiate energy into the interior of the reactor shaft 515, causing the powder to be heated. In this regard, the reactor walls 518 are typically comprised of a metal or metal alloy with high thermal conductivity. Surrounding the reactor 550 is a refractory wall 504, which is comprised of a refractory material.

[0158] The powder product accumulates within a reacted powder hopper 511 located at the lower end of the shaft 515. In particular, the powder product forms a moving powder bed 513 within the powder hopper 511. The powder product is removed from thehopper 511 via a hot powder ejector 512. The powder product is collected as a hot powder product 5-2 of the reactor 550. As described with reference to Fig. 4, heat from the hot powder product 5-2 can be collected for re-use in the process. In the illustrated embodiment of Fig. 5, the walls of the reactor 550 around the moving bed 513 are lined with a suitable energy storage material, such as bricks. The energy storage material provides insulation to the moving bed 513.

[0159] The overall heat loss from the reactor 550 is the heat energy 5-12. This heat loss can be minimised by, e.g., surrounding the reactor 550 with an insulating material.

[0160] Process gas, such as gas produced from the reaction of the powder in the shaft 515 and any gases that are injected into the reactor, is collected at the gas exhaust 516, which is located at the upper end of the reactor 550. The gas exhaust 516 typically comprises a cyclone separator 505 which is configured to separate any entrained powder from the process gas. The entrained powder is reinjected into the shaft 515 via the recycled solids feeder 506. The process gas 5-3 is collected and, e.g., further processed in a reactor gas condenser.

[0161] The heat inputs, in units of kJ / s, required for processing the powder in the reactor 550 comprises the heat recovery streams described above with reference to Fig. 4. Fig. 5 illustrates an embodiment of how the various heat streams may be delivered to reactor 550. In this regard, in the illustrated embodiment of the reactor 550 of Fig. 5, the reactor 550 is comprised of five segments: the segment housing the spinner 507, an upper heating segment 508, an annulus segment 514 which houses expansion bellows 509, the lower heating segment 510 and the reacted powder hopper 511. It is noted that each of the upper heating segment and the lower heating segment can further divided into further segments. For example, each of the upper and lower heating segments may be further segmented to allow additional regenerative combustion segments. It is thought that for reactors comprising more reactor segments switching between electric and combustion segments can better attain a similar temperature profile during switching events. Alternatively, in other embodiments, the reactor may comprise only a single heating segment.

[0162] In the illustrated embodiment of Fig. 5, the segment housing the spinner 507 is configured to be heated using recycled heat from elsewhere in the process, namely heat from the hot powder product 5-2, hot process gas 5-3 and, when present, combustion flue gases, as well as other ancillary gases. Heat from each of these streams is recovered using an air stream (or other gas stream), thereby producing a hot gas 5-4. The segment housing the spinner 507 comprises a chamber 517 arranged to surround the reactor walls 518. Hot gas 5-4 with thermal energy H-5-4 is input into the chamber 517 and is caused to flow through the chamber 517. As the hot gas 5-4 flows through the chamber 517, heat energy H-5-4 is transferred from the hot gas 5-4 to the reactor walls 518. The heated reactor walls 518 then radiate thermal energy into the interior of the reactor shaft 515. The rotation of the spinner 507 creates turbulence at the reactor walls 518 to further facilitate the heat transfer. It is noted that other embodiments may use multiple air flows and / or other conventional heat exchanger methods to transfer energy. The cooled gas 5-2 exiting the chamber 517 can still comprise some residual thermal energy H-5-2. Accordingly, in some embodiments, the cooled gas 5-2 is used to preheat the injected powders from the input powder hopper 500 and the recycled solids feeder 506.

[0163] In alternative embodiments, the segment comprising the spinner 507 does not comprise any additional heating system(s). In such embodiments, the downwardly falling powder that is injected at the top of the reactor shaft 515 is preheated by the hot product gas that flows upwardly through the reactor shaft 515. Alternatively or additionally, heat from combustion exhaust gases may be vented through this segment of the reactor shaft, with heat energy from the exhaust gases also used to preheat the downwardly falling powder. In such embodiments, the reactor may comprise an external preheater in which the powder 5-1 is preheated prior to being fed to the input powder hopper 500. For example, as above, the power 5-1 can be preheated using recycled heat from elsewhere in the process, namely heat from the hot powder product 5-2, hot process gas 5-3 and, when present, combustion flue gases, as well as other ancillary gases.

[0164] The upper heating segment 508 and the lower heating segment 510 each comprise a heating system that can use either electricity or another energy source. For example, the other energy source typically comprises combustion energy. However, inother embodiments, it is envisaged that the other energy source can instead comprise hot gases, e.g., from a thermal energy storage system. In this regard, the upper heating segment 508 and the lower heating segment 510 each comprise a hybrid heating system. In the illustrated embodiment of Fig. 5, each of the heating segments 508, 510 comprise an electric heating system and a combustion heating system (i.e., the other energy source comprises combustion energy). As described above with reference to Fig. 2, the electric heating system and the combustion heating system can be configured to surround the reactor shaft such that the heating systems are separated.

[0165] In the illustrated embodiment, the electric heating systems 5-6, 5-9 (respectively) are in the form of resistive heating elements that are located adjacent the reactor wall 518. It is noted that, in some embodiments, the reactor wall 518 itself can be comprised of resistive heating elements. The combustion heating systems each comprise a combustion chamber 520, 521 (respectively) that is configured to surround the reactor shaft 515. The combustion chambers are configured to combust air and fuel therein or, in some embodiments, to allow a hot flue gas (from the combustion of fuel and air in an external combustion chamber) to be circulated therewithin. However, it is thought that combusting the air and fuel directly in the combustion chamber is more thermally efficient, with reduced heat losses compared to embodiments in which the fuel and air are externally combusted. As described above with reference to Figs. 1 and 2, the exhaust gas from the chambers 520, 521 can be collected as a single exhaust stream (not shown). In addition, each of the heating systems comprises at least one temperature sensor (not shown) which allows the temperature profile within the reactor 550 to be continuously measured (e.g., on a 1 second basis). As described above in detail, the temperature information is used to adjust the amount of energy being supplied to the heating system via combustion. For example, during a switching event, the energy from combustion is adjusted so as to maintain an approximately constant temperature profile within the reactor 550.

[0166] The electric heating systems 5-6, 5-9 are configured to heat the heating system using electricity H-5-6, H-5-9, i.e., by resistive heating of the metal alloy walls of the reactor. The electricity can comprise electricity from a grid, e.g., a high VRE grid, and / or stored electricity, e.g., from a battery, as described above in detail with reference toFigs. 3 and 4. In contrast, the combustion heating systems comprising the chambers 520, 521 are configured to heat the heating system using heat from combustion H-5-7, H-5-9. In this regard, the combustion chambers 520, 521 are configured to allow gas 5-7, 5-9 to be input therein. The gas can comprise a mixture of fuel and an oxidant, which is combusted within the chambers, or a hot flue gas. As the gas 5-7, 5-9 is circulated within the combustion chambers 520, 521, heat from combustion (or from the hot flue gas) is transferred to the reactor walls 518 and, ultimately, radiated into the reactor shaft 515. The exhaust gases 5-8, 5-11 are collected and, as described above with reference to Fig. 4, passed through a gas clean-up system. Residual thermal energy H-5-8, H-5-11, can be collected for use.

[0167] During operation, the ambient ground powder 5-1 is injected into the input powder hopper 500 and then fed into the reactor shaft 515 via the input powder feeder 501. Typically the input powder feeder 501 incorporates a loss in weight / metered screw feeding system and a valve (e.g., flap, rotary, butterfly valve etc., or combinations thereof) which acts as a gas block preventing loss of process gas through to the feed side and conversely bleeding of gases from the feed side. In some embodiments, the input powder feeder 501 can comprise a screw feeder specified to minimise agglomeration. In other embodiments, such as when the ground powder is too fine for processing in the reactor, the input powder feeder can instead be configured to exert a pressure to agglomerate the powder to optimise the reactor performance. In such embodiments, the input powder feeder can comprise a combination of a feeding system (such as, but not limited to, a screw feeder) and an agglomerator.

[0168] In the illustrated embodiment of Fig. 5, the injected powder, flowing downward under gravity is impacted by a rotating spinner 507 to break up larger agglomerates which may have been formed upstream. The spinner 507 is designed and operated to break-up agglomerates that would otherwise fall through the reactor shaft 515 too quickly to be fully reacted and to aid in the dispersal of the powder throughout the reactor shaft 515 and in the formation of a plume. As above, in other embodiments, the spinner 507 may be replaced by other dispersion mechanisms.

[0169] The particles in this segment are heated by hot gas 5-4 as described above. In particular, heat energy H-5-4 from the hot gas 5-4 heats the steel walls in this segment.

[0170] In this uppermost reactor segment, i.e., the segment with the spinner, powder is entrained in the rising hot gas stream. This net up-flowing gas stream, along with the entrained powder, flows into gas exhaust 516 and to the gas cyclone separator 505. In other embodiments, a cyclone stack may be used to maximise the recovery of entrained powder, although this may result in a higher heat loss of the separated gas and powder streams. The separated hot gas 5-3 is exhausted and heat energy is extracted therefrom, as described above with reference to Fig. 4 and used as an energy input elsewhere, e.g., for preheating the input powder 5-1. In some embodiments, the gas exhaust 516 is configured and operated to maintain a gas pressure in the reactor of about 1 bara. The hot powder recovered in the cyclone 505 is reinjected into the reactor shaft 515 using the recycled solids feeder 506. In some embodiments, the recycled solids feeder 506 is also a screw feeder.

[0171] It is noted the systems of the spinner, the cyclone(s), the input powder feeder, the recycled solids feeder, and the gas heat recovery system can be designed as a sub-system to minimise both heat losses as well as powder losses in the hot process gas 5-3 and to deliver an optimised particle size distribution for processing in the lower sections of the reactor. These designs are bespoke for the powder material being processed in the reactor.

[0172] In the upper heating segment 508, the reactor walls 518 are heated by electric energy 2-6 (e.g., by resistive heating) and / or by combustion of the gas 2-7. In some embodiments, the gas heating may be optimised by injecting the gas 2-7 at a height of the chamber 517 that is offset from the centre line (not shown) and by exhausting the gas 5-8 at a height of the chamber 517 that is offset from the centre line (not shown). Vertically off-setting the gas entrances and exits (not shown) can introduce a swirl to the gas flow within the chamber 517, which can increase the heat transfer rate to and from the reactor walls 518 and inhibit formation of deposits of materials on the metals and refractories from which the combustion chamber and walls are constructed. As above, the reactor 550 isconfigured such that the energy source can be switched between electric energy and combustion. This switching between electric energy and combustion is described above in detail. For instance, the heating system of the reactor 550 can be configured to use electricity when a cost of the electricity is low and / or when there is an oversupply of grid electricity. Conversely, the heating system can be configured to use combustion when a cost of electricity is high and / or when there is insufficient grid electricity to meet the demands of all customers on the grid. In some embodiments, the heating system may always supply a fraction of the energy required from combustion. This can increase the speed of switching events because the combustion system is always active.

[0173] In the illustrated embodiment of Fig. 5, the reactor 550 comprises at least one horizontal annulus 514 which is configured to divide the heating system into the upper heating segment 508 and the lower heating segment 510. It is thought that the annulus 514 is not an essential feature of the reactor 550 and may therefore be omitted or modified to optimise the heater transfers within the reactor. For example, in some embodiments, the annulus can be omitted such that there is only a single heating segment in the reactor. In such embodiments, the flow of gas through the combustion chamber may be modified along the whole reactor tube, e.g., to increase the efficiency of the heat transfer which can reduce the reactor height.

[0174] The walls 518 of the reactor 550 are configured with one or more bellows 509. In the illustrated embodiment, the bellows 509 are located in an intermediate region of the reactor. The bellows 509 separate the reactor wall 518 into an upper section and a lower section. In the illustrated embodiment, the bellows 509 are located within the annulus 514. It is noted that locating the bellows 509 within the annulus 514 may be useful role in terms of inhibiting fouling of the bellows by combustion gases, i.e., because the bellows 509 are fluidly isolated from each of the combustion chambers 520, 521. However, it will be appreciated that the bellows 509 can be otherwise located. In addition, the bellows 509 can be present even in embodiments in which there are no annuli 514. In such embodiments, the bellows 509 can separate the reactor walls into different sections. The bellows 509 can also provide a gas tight seal between the upper heating segment 508 and the lower heating segment 510.

[0175] The bellows 509 are configured to expand and contract as the reactor walls 518 are heated and cooled, such that the total reactor length is unchanged during heat-up, cool-down and any switching events. In this regard, the bellows 509 can act as an expansion joint to accommodate for thermal expansion and provide a means of supporting the reactor shaft at different points along the reactor shaft. This can help to manage mechanical stress on the reactor shaft. In addition to the bellows 509, the reactor can further comprise additional mounting and / or support points to reduce mechanical stress on the reactor shaft. Without being bound by theory, it is thought that the reactor walls can be configured with other types of expansion joints, such as rope seals, etc.

[0176] The bellows 509 can be made from the same steel as used in steel walls for ease of welding. In addition, the bellows 509 can be configured to either provide an electrical connection between reactor segments, e.g., for single zonal heating. Alternatively, the bellows 509 can be configured such that the reactor segments are electrically isolated, allowing for independent temperature control of the different zones / reactor segments. It is noted that the use of such bellows has not been previously disclosed in the prior art for indirectly heated reactors, and these bellows maybe used in indirectly heated reactors which are not designed for the switching events disclosed herein. That is, it is thought that the bellows can be used in indirectly heated reactors that are not hybrid reactors.

[0177] In the illustrated embodiment of Fig. 5, the segment of the reactor comprising the bellows 509 is not shown to be indirectly heated. However, it is noted that the reactor wall would be heated through the thermal conductivity of the reactor walls, the refractory walls, and the heated materials in the reactor and the radiation heating from adjacent wall segments.

[0178] It is noted that the grounding of the electric heating elements has not been specified. This is purposeful because the grounding determines the AC and DC current flows in the steel alloy along of the reactor walls and hence the heating rates and temperatures. Grounding may be specified in conjunction with the wiring of ACtransformers considered herein. In a simple case, the electric grounding may be either at the annuli 514 or at the base of the lower heating segment 510.

[0179] The lower heating segment 510 is configured in a similar manner and so will not be described again in detail. In particular, as with the upper heating segment 508, the lower heating segment 510 is configured to use electric energy H-5-9 and / or energy H-5-10 from combustion of gas 5-10 to heat the walls 518 of the reactor. Again, the lower heating segment 510 is able to switch between these energy sources.

[0180] As explained above, the powder hopper 511 receives the downflowing reacted powder which settles to form a moving bed 513 for extraction by the hot powder ejector 512. The hot powder ejector 512 is designed to extract powders over a wide range of temperatures. The gas pressure in the reactor shaft 515, as described above, is about 1 bara.

[0181] In some embodiments, the powder in the moving bed 513 is sufficiently porous from the process of generating gases, such that further gases may be emitted from the powder in the moving bed, allowing the completion (or near completion) of the reaction process. It is noted, however, that such further reaction can result in some sintering of the product. Such processes may be set and / or controlled by controlling the powder temperature at the base of the lower heating segment 510 and the residence time of the powder in the moving bed 513.

[0182] It is noted that the reactor 550 can be configured to operate using electricity and energy from one or more other energy sources. For example, the reactor 550 can be configured to operate using electricity (as described above in detail) and thermal energy from a hot gas. The hot gas may be from a thermal energy storage system. In such embodiments, the hot gas can be circulated through the chambers 520, 521 to provide thermal energy to the reactor walls 518. It is thought that, in some embodiments, the hot gas may be used in combination with combustion. It is thought that this can improve the response time of the hybrid reactor 550 to changes in VRE grid electricity supply.

[0183] Without being bound by theory, it is thought that the reactor may be configured to use energy from an electrical plasma heating system (in addition to or instead of electricity and / or combustion). Electrical plasma heating systems can be used for both indirect heating (e.g., in an indirectly heated reactor) and direct heating (e.g., in a fluidised bed or spouted bed reactor) applications. The heating system of the reactor may also comprise a plasma heating finishing stage located at the outlet. This may enable higher outlet temperatures to be achieved. Plasma fluids may include one or more of nitrogen, argon, hydrogen, oxygen and CO2. When direct heating is used and in applications where CO2 is produced from the reaction occurring in the reactor shaft, such as in calcination of limestone / dolomite, it can be advantageous to operate using CO2 as the plasma, as this can reduce dilution of the outlet CO2.Hybrid AC and / or DC Electrically Heated Reactor

[0184] Fig. 6 shows an embodiment of a reactor 660 in which the heating system uses only electricity. The reactor 660 of Fig. 6 is configured to switch between AC grid electricity and DC electric energy, such as energy stored in batteries at the production site. That is, no combustion is used. In particular, the reactor 660 can be configured to use electrical energy stored in batteries when, e.g., a cost of grid electricity is high and / or there is an insufficient supply of grid electricity.

[0185] The configuration of the reactor 660 is similar to the configuration of the reactor 550, except that the reactor 660 does not comprise combustion chambers adjacent the upper heating segment 608 and the lower heating segment 610, i.e., because the upper heating segment 608 and lower heating segment 610 are only configured to use electricity. In this regard, in some embodiments, the shaft 615 of the reactor 660 may be configured with suspended plates which are able to provide heat via resistive heating and are able to use both AC or DC electricity. Accordingly, it is thought that the reactor 660 of Fig. 6 may provide a simpler, lower cost system. Additionally, it is thought that the packing of the reactors to provide a large-scale manufacturing plant may result in a smaller footprint forthe same production capacity, compared to when the hybrid reactor 550 of Fig. 5 is employed.

[0186] The configuration and operation of the reactor 660 will not be described again in detail. At a high-level, as with the reactor 550, the reactor 660 also comprises five segments: the segment housing the spinner 607, an upper heating segment 608, an annulus segment 614 which houses expansion bellows 609, the lower heating segment 610 and the reacted powder hopper 611. As above, the hot gas 6-4 used to heat the segment housing the spinner 607 comprises energy recovered from the hot powder product 6-2, hot process gas 6-3, and any ancillaries. Residual heat present in the cooled gas 6-5 can be used to preheat the powder injected from the input powder feeder 601 and / or the recycled solids feeder 606. The electric energy flows 3-6 and 3-7 are employed to provide heat by resistive heating of the metal alloy walls 603 of the reactor, by either or both AC and DC sources.

[0187] As above, the ground powder 6-1 is injected into the input powder hopper 600 and then into the reactor shaft 615 via the input powder feeder 601. The input powder feeder 601 typically incorporates a screw feeding system and a valve and a valve (e.g., flap, rotary, butterfly valve etc., or combinations thereof) which acts as a gas block preventing loss of process gas through to the feed side and conversely bleeding of gases from the feed side. In this regard, in some embodiments, the feeder 601 can comprise a screw feeder specified to minimise agglomeration. Alternatively, if the ground powder is too fine for processing in the reactor, the powder input feeder can instead be configured to exert a pressure to agglomerate the powder to optimise the reactor performance. The injected powder falls downwardly under gravity and is impacted by the rotating spinner 607, which acts to break up larger agglomerates which may have been formed upstream. The powder in this segment are heated by hot gas 6-4.

[0188] In this uppermost reactor segment, powder is entrained in the rising hot process gas stream. This net up-flowing gas stream flows into gas exhaust 616. The gas exhaust 616 comprises a cyclone 605 (or stack of cyclones) which separates entrained powder from the process gas. The (hot) process gas is exhausted 6-3 and heat energy extracted therefrom, as described above. The extracted heat energy is recovered for use.The powder recovered in the cyclone 605 is reinjected into the shaft 615 via the recycled solids feeder 606. As above, the systems of the spinner, the gas exhaust, the input powder feeder, the recycled solids feeder, and the gas heat recovery system may be designed as a sub-system to minimise both heat losses as well as powder losses and deliver an optimised particle size distribution for processing in the lower sections of the reactor.

[0189] The powder continues to fall downwardly through the upper heating segment 608, wherein the reactor walls 603 are heated by electric energy H-6-6 via resistive heating. The source 6-6 of the electric energy H-6-6 can comprise AC and / or DC electricity. Furthermore, the system is designed such that the source 6-6 can be switched between an AC source and a DC source. The operation and configuration of the lower heating segment 610 is the same as that of the upper heating segment 608 and so will not be described again in detail.

[0190] As above, the reactor comprises an annulus 614, which separates the upper heating segment 608 and the lower heating segment 610. The annulus 614 comprises bellows 609 configured to expand and contract as the reactor is cooled and / or heated. This can allow the length of the metal alloy reactor walls to remain approximately constant during the heat-up, cool-down and any switching events. The bellows 609 may be made from the same steel as used in the reactor walls, to allow for fabrication of the bellow from welding.

[0191] As above, the grounding of the electric heating elements is not specified. This is purposeful because the grounding determines the AC and DC current flows in the steel alloy along the reactor walls and hence the heating rates and temperatures. The grounding can be specified in conjunction with the wiring of AC transformers. In simple cases, the electric grounding may be located at the annuli 614 or at the base of the lower heating segment 610.

[0192] The operation and configuration of the lower heating segment 610 is the same as that of the upper heating segment 608 and so will not be described again in detail. That is, as above, the lower heating segment 610 is configured to heat the reactor wallsusing electrical energy, whereby the electrical energy can be in the form of AC and / or DC electricity.

[0193] As above, the reacted powder hopper 611 receives the downflowing reacted powder product, which forms a moving bed 613 in the hopper. Powder from the moving bed 613 is ejected via a hot powder ejector 612 as a hot powder product 6-2. The hot powder ejector 612 is designed to extract powders 6-2 over a wide range of temperatures. The heat energy from the hot powder product 6-2 is recovered, as described above in detail.

[0194] The overall radiative heat loss of the entire reactor 660 is H-6-8. The amount of radiative heat loss may be reduced and / or minimised by surrounding the reactor 660 with an insulating material.

[0195] Without being bound by theory, it is thought that the reactor may be configured to use energy from an electrical plasma heating system (in addition to or instead of electricity and / or combustion). Electrical plasma heating systems can be used for both indirect heating (e.g., in an indirectly heated reactor) and direct heating (e.g., in a fluidised bed or spouted bed reactor) applications. The heating system of the reactor may also comprise a plasma heating finishing stage located at the outlet. This may enable higher outlet temperatures to be achieved. Plasma fluids may include one or more of nitrogen, argon, hydrogen, oxygen and CO2. When direct heating is used and in applications where CO2 is produced from the reaction occurring in the reactor shaft, such as in calcination of limestone / dolomite, it can be advantageous to operate using CO2 as the plasma, as this can reduce dilution of the outlet CO2.

[0196] Without being bound by theory, it is further thought that the reactor 660 may be configured to operate intermittently as a way of offering grid stabilisation services, whilst maintaining product quality. For example, the reactor can be switched on and use grid electricity as the energy source when there is a surplus of electricity in the grid. Alternatively, the reactor can be switched off (either altogether or switched to using stored electricity) when there is insufficient electricity available in the grid. In this regard, the reactor can be configured to allow for rapid on / off switching, fast heat-up / cool-down (i.e., to allow for intermittent operation) and ramping. It is thought that this is achievable due tothe design of the indirectly heated drop tube reactors disclosed herein, which feature short residence times and can be comprised of a metal reactor tube construction and flexible / fibrous insulation (in lieu of hard refractories) and being vacuum formed, with light weight panelling.Process Scale-Up

[0197] It is noted that indirectly heated drop tube reactors inherently require small shaft diameters, i.e., to ensure heating of the powder within the reactor shaft by radiative heat transfer. As a result, large manufacturing plants using indirectly heated drop tube reactor technology require many shafts. Such an approach may use modules of reactors, wherein each the reactors of each module are fed by a common grinding system using pneumatic conveying. For example, each module can comprise 10 reactors.

[0198] As an example, consider a plant producing lime from limestone using the hybrid reactor approach disclosed above in which the reaction occurs within an indirectly heated drop tube reactor. Such indirectly heated reactor systems can be used to process limestone with a 150 pm mean particle in a counterflow reactor designed to produce a pure CO2 stream that can be cooled for liquid CO2 production. 253 MA steel may be used for the reactor walls, resulting in an upper temperature limit of about 1050°C for a vertical suspended metal reactor, for which the length of the reactor is typically 25 m high with a diameter of about 1.5 m for the reactor shaft. As an example embodiment, the production of 7 tonnes / hr of lime in one shaft may be associated with a calcination process heat loss of about 30%, primarily due to inefficient heat recuperation. Thus, the heat consumption is 8.8 MW per shaft. For a plant with 10 reactors per module and 4 modules per plant, the total heat consumption would be about 350 MW for a lime plant producing about 300 tph of product. This estimate does not include grinding energy and ancillary costs associated with CCSU for the CO2 processing or specific fuel side processes. If each reactor has 10 temperature measurements, a SCADA system would report 400 temperature measurements per second. This may warrant the use of artificial intelligence (Al) to determine the optimum utilisation of resources and energy distributions, including forecasts for gridenergy capacity and demand, and combustion energy requirements. In this example, the lime plant may switch over 200 MW of power, such that at least some of the power is being generated by combustion at all times. For a grid supplying 1.5 GW of stabilised electrical power to customers, this plant can consume 20% of excess power at a negative cost and revert to combustion with CCSU when the cost of power is high. Such a plant may be used for the stabilisation of class 5 and / or class 6 VRE grids. By also charging some batteries on site, larger grid may be stabilised.

[0199] Variations and modifications may be made to the parts previously described without departing from the spirit or ambit of the disclosure. For example, the hybrid reactors can comprise any number of heating segments. As another example, the hybrid reactors can be configured with a gas input to allow a process gas to be injected into the reactor during use.

[0200] As yet another example, it is thought that the indirectly heated reactor can comprise a tubeless reactor comprising internal plates or tubes that are electrically heated and / or combustion heated. The configuration and operation of such reactors are described in detail in the applicant’s co-pending PCT application no. PCT / AU2025 / 050422, the disclosure of which is incorporated herein in its entirety by way of cross-reference.

[0201] In particular, PCT / AU2025 / 050422 discloses a vertically oriented reactor that comprises an elongate reactor body comprising one or more material feed inlets located toward an in-use upper end of the reactor body, the material feed inlets configured to feed a powder to be reacted such that said powder falls downwards in the reactor body; optional gas input ports arranged toward an in-use lower end of the reactor body for feeding a gas into the reactor body (when required); a powder outlet positioned toward the lower end of the reactor body; and heating elements positioned in an interior space of the reactor body and configured to transfer heat into the interior space of the reactor body, so as to heat the gas and the falling powder and cause the powder to react.

[0202] The heating elements can comprise electric heating elements. The electric heating elements can comprise one or more sheets or tubes that are located (e.g.,suspended) within the interior space of the reactor body and configured to be electrified so as to transfer heat directly into the reactor body. The heating elements can additionally comprise combustion heating elements. In some variations the combustion heating elements comprise tubes that are suspended within the interior space of the reactor body and configured to allow the combustion of fuel and air therewithin. Alternatively or additionally, the combustion heating elements can comprise (or further comprise) an outer shell surrounding the reactor body configured to allow combustion of fuel and air therewithin. It is noted that, in yet other embodiments, the combustion heating elements are instead configured to allow a hot gas, such as a hot exhaust gas from an external combustion process or a hot gas from a thermal energy storage system, to be passed through the combustion heating elements, such that heat is transferred from the combustion heating elements to the interior space of the reactor body. As described above in detail, the reactor can be configured to switch between using electricity and combustion (or hot gas) as the energy source. In this regard, it will also be appreciated that the hybrid concepts disclosed herein are applicable to a wide variety of reactor configurations.

[0203] In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” or variations such as “comprises” or “comprising” is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the reactors and systems as disclosed herein.

Claims

Claims1. A vertically oriented reactor, the reactor comprising:a vertically oriented reactor tube;a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube; anda heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur;wherein the heating system is configured to operate using combustion heating and electricity.

2. A reactor as claimed in claim 1 , wherein, in-use, the heating system is configured to operate using combustion heating or electricity or both combustion heating and electricity simultaneously.

3. A reactor as claimed in claim 1 or 2, wherein, when the heating system is operated using electricity, the electricity is generated from a renewable energy source and / or from stored electricity.

4. A reactor as claimed in any one of the preceding claims, wherein the heating system is configured to use AC or DC electricity when the heating system is operating using electricity.

5. A reactor as claimed in any one of the preceding claims, wherein the heating system is positioned vertically adjacent at least one wall of the reactor tube at an intermediate region of the reactor tube and, when the system is operated using combustion heating, is configured to indirectly heat the interior of the reactor tube.

6. A reactor as claimed in claim 5, wherein the heating system comprises a combustion chamber arranged to surround the reactor tube, the combustion chamber configured to combust air and fuel therein.

7. A reactor as claimed in claim 5, wherein the heating system comprises a chamber arranged to surround the reactor tube, the chamber configured to receive hot exhaust gases from a combustion process.

8. A reactor as claimed in any one of the preceding claims, wherein the heating system comprises resistive heating elements located adjacent to a wall of the reactor, the resistive heating elements configured to be powered by electricity.

9. A reactor as claimed in any one of claims 1 to 7, wherein the walls of the reactor are comprised of resistive heating elements, the resistive heating elements configured to be powered by electricity.

10. A reactor as claimed in any one of the preceding claims, the reactor tube further comprising at least one annulus, the annulus configured to divide the heating system into an upper heating system located above the annulus and a lower heating system located below the annulus.

11. A reactor as claimed in any one of the preceding claims, wherein a wall of the reactor tube is configured with one or more bellows.

12. A reactor as claimed in claim 11, wherein at least one of the one or more bellows is located in an intermediate region and / or wherein at least one of the one or more bellows is located below an intermediate region.

13. A reactor as claimed in claim 11 or 12, wherein the wall of the reactor tube is configured with one bellow.

14. A reactor as claimed in claim 13 when dependent on claim 10, wherein the bellow is located within the annulus, with the upper heating system located above the bellow and the lower heating system located below the bellow.

15. A reactor as claimed in any one of claims 1 to 5, wherein the heating system comprises a combustion heating system arranged to surround a first section of the reactor tube and an electrical heating system arranged to surround a second section of the reactor tube.

16. A reactor as claimed in claim 15, wherein the combustion heating system and the electrical heating system are separated.

17. A reactor as claimed in claim 15 or 16, wherein the combustion heating system and the electrical heating system are each comprised of multiple segments arranged along a length of the reactor tube.

18. A reactor as claimed in claim 17, wherein the reactor tube is comprised of multiple segments, each of the reactor tube segments comprising one of the multiple combustion heating system segments and one of the multiple electrical heating system segments.

19. A reactor as claimed in claim 17 or 18, wherein each segment of the reactor tube comprises a temperature sensor configured to measure a temperature of the reactor wall.

20. A reactor as claimed in claim 19, wherein the reactor is configured with a controller operable to increase or decrease an amount of combustion occurring within the combustion heating system based on a measured temperature.

21. A reactor as claimed in any one of the preceding claims, further comprising a dispersion apparatus located at the upper end of the reactor tube and below the powder input and configured to disperse the powder as the powder is input into the reactor tube.

22. A reactor as claimed in claim 21, wherein the dispersion apparatus comprises rotor blades which, in-use, are located on a vertical axis of the reactor tube and are configured to spin around the vertical axis of the reactor tube.

23. A reactor as claimed in claim 22, wherein the dispersion apparatus is further configured to reduce a particle size of the powder as the powder impacts the rotor blades, such that the powder of reduced particle size leaving the rotor blades falls downwardly into the heated interior of the reactor tube.

24. A reactor as claimed in any one of claims 21 to 23, further comprising an input powder preheater configured to preheat the powder input at the upper end of the reactor tube prior to the powder being heated by the heating system.

25. A reactor as claimed in claim 24, wherein the powder preheater is configured to preheat the powder using energy from one or more of: a powder product output from the reactor tube, an exhaust gas from the reactor tube and / or an exhaust gas from a combustion process.

26. A reactor as claimed in any one of the preceding claims, further comprising a gas exhaust located adjacent the upper end of the reactor tube.

27. A reactor as claimed in claim 26, wherein the gas exhaust comprises a cyclone separator configured to separate entrained powder from an exhaust gas and wherein the gas exhaust is further configured to reinject the entrained powder into the interior of the reactor tube.

28. A reactor as claimed in any one of the preceding claims, the reactor further comprise a reacted powder hopper located at a lower end of the reactor tube and configured to output a powder product from the reactor.

29. A reactor as claimed in any one of the preceding claims, wherein the reactor is configured with a controller which is operable to switch the energy for the heating system to the use of electric energy when a price of electricity is low or when a quantity ofelectricity available is high, and to switch the energy for the heating system to the use of combustion when the price of electricity is high or when the quantity of electricity available is low.

30. A vertically oriented reactor, the reactor comprising:a vertically oriented reactor tube;a powder input located at an upper end of the reactor tube and configured to input a powder into the reactor tube; anda heating system configured to provide heat to an interior of the reactor tube, so as to heat the powder in the interior of the reactor tube to a temperature whereby an endothermic reaction of the powder is caused to occur;wherein the heating system is configured to operate using grid electricity and one or more other energy sources.

31. A reactor as claimed in claim 30, wherein, in-use, the heating system is configured to operate using the grid electricity or the one or more other energy sources or both the grid electricity and the one or more other energy sources simultaneously.

32. A reactor as claimed in claim 30 or 31, wherein the grid electricity comprises electricity from a Variable Renewable Energy grid.

33. A reactor as claimed in any one of claims 30 to 32, wherein at least one of the one or more other energy sources provides electricity in the form of DC electricity.

34. A reactor as claimed in claim 33, wherein the one or more other energy sources comprise energy stored in a battery.

35. A reactor as claimed in any one of claims 30 to 34, wherein at least one of the one or more energy sources provides energy from combustion.

36. A reactor as claimed in any one of claims 30 to 35, the reactor being otherwise as defined in any one of claims 5 to 29.

37. A system for reacting a powder, wherein the reaction comprises an endothermic reaction, the system comprising:one or more reactors, each reactor being as claimed in any one of claims 1 to 29;an electricity source configured to provide electricity to the heating system of the one or more reactors; anda combustion fuel source configured to provide combustion heating to the heating system of the one or more reactors.

38. A system as claimed in claim 37, wherein the electricity source comprises grid electricity.

39. A system as claimed in claim 37 or 38, the system further comprising an indirect combustion heater configured to combust a fuel source and air, wherein the system is further configured to pass resultant exhaust gases to the one or more reactors so as to provide combustion heating to the one or more reactors.

40. A system as claimed in any one of claims 37 to 39, the system further comprising a battery storage system configured to store electricity and to provide electricity to the heating system of the one or more reactors.

41. A system as claimed in any one of claims 37 to 40, the system further comprising a carbon capture process configured to capture carbon dioxide from the combustion exhaust gases and / or a process gas from the one or more reactors.

42. A system for reacting a powder, wherein the reaction comprises an endothermic reaction, the system comprising:one or more reactors, each reactor being as claimed in any one of claims 30 to 36;a grid electricity source configured to provide grid electricity to the heating system of the one or more reactors; andone or more other energy sources configured to provide energy to the heating system of the one or more reactors.

43. A system as claimed in claim 42, wherein the grid electricity comprises a Variable Renewable Energy grid.

44. A system as claimed in 42 or 43, the system further comprising a battery storage system configured to store electricity and to provide electricity to the heating system of the one or more reactors.

45. A system as claimed in claim 42 or 44, the system further comprising an indirect combustion heater configured to combust a fuel source and air, wherein the system is further configured to pass resultant exhaust gases to the one or more reactors so as to provide combustion heating to the one or more reactors.

46. A system as claimed in claim 45, the system further comprising a carbon capture process configured to capture carbon dioxide from the combustion exhaust gases and / or a process gas from the one or more reactors.

Images