Carbon capture system and method

Abstract

A system comprising a first reaction vessel (1), a second reaction vessel (2) and a heat transfer component (3), wherein: (i) the first reaction vessel is configured to accept a first fluid (4) and convert the first fluid into a second fluid (5); wherein the concentration of CO2 in the second fluid is less than the concentration of CO2 in the first fluid; (ii) the heat transfer component is configured to transfer thermal energy between the first reaction vessel and a third fluid (6); and (iii) the second reaction vessel is configured to accept the third fluid from the heat transfer component.

Description

[0001] CARBON CAPTURE SYSTEM AND METHOD

[0002] Technical Field The invention relates to systems and methods. The systems and methods are particularly useful for carbon capture and storage. The systems and methods are also particularly useful for providing support for an electrical power grid.

[0003] Background of Invention

[0004] Carbon capture and storage (CCS) and large-scale implementation of renewable energy both will play major roles in the global energy transformation. CCS accounts for one- fifth of the total global emission reductions through 2050 as predicted by the International Energy Agency (IEA) (D. Akinyele and R. Rayudu, "Review of energy storage technologies for sustainable power networks," Sustainable Energy Technologies and Assessments, vol. 8, pp. 74-91, 2014). By the year 2070, the Sustainable Development Scenario by the IEA predicts net-zero emissions, and around 10 Gt of CO2 captured in that year (P. Parfomak, "Energy storage for power grids and electric transportation: a technology assessment," Congregational Research Service Report, 2012). The same reference predicts that renewable energy demand will increase from 20 million tonnes of oil equivalent (Mtoe) in 2019 to 9905 Mtoe in 2070, which accounts for almost 65% of the total energy demand in that year. However, the greatest impediment to the widespread use of renewable energy is the intermittency of the energy source and keeping up with the shifts in electricity demand. As the electricity produced from the renewable sources fluctuates, grid-scale electricity storage schemes are essential to balance the electricity production and demand at each instance.

[0005] An electrical power grid must match electricity production to consumption. Due to the intermittency of renewable electricity sources, grid scale electricity storage systems are of paramount importance to achieve matching electricity production and consumption patterns. Whilst there exist some potential solutions to this technological challenge, they each have their associated drawbacks. Summary of Invention

[0006] The invention relates to systems and methods. The systems and methods are particularly useful for carbon capture and storage. The systems and methods are also particularly useful for providing support for an electrical power grid.

[0007] In a first aspect, the invention relates to a system comprising a first reaction vessel, a second reaction vessel and a heat transfer component, wherein:

[0008] (i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid;

[0009] (ii) the heat transfer component is configured to transfer thermal energy between the first reaction vessel and a third fluid; and

[0010] (iii) the second reaction vessel is configured to accept the third fluid from the heat transfer component.

[0011] In some embodiments, the heat transfer component is not in fluid connection with the first reaction vessel. In some embodiments, the heat transfer component is configured such that when the second reaction vessel is in use, it is not in fluid connection with the first reaction vessel. In some embodiments, the heat transfer component is configured such that when it is in use, it is not in fluid connection with the first reaction vessel. In some embodiments, the heat transfer component is configured such that it cannot be made in fluid connection with the first reaction vessel. In some embodiments, there is no output of the first reaction vessel that is in fluid connection with the second reaction vessel. For example, there is no output of the first reaction vessel that is in fluid connection with an input of the second reaction vessel. For example, there is no output of the first reaction vessel that is in fluid connection with the interior of the second reaction vessel.

[0012] In some embodiments, the second reaction vessel is not in fluid connection with the first reaction vessel. For example, there is no fluid pathway between the first reaction vessel and the second reaction vessel. For example, there is no fluid pathway between the interior of the first reaction vessel and the second reaction vessel. In some embodiments, the heat transfer component is not in fluid connection with the first reaction vessel and / or the second reaction vessel is not in fluid connection with the first reaction vessel. For example, the heat transfer component is not in fluid connection with the first reaction vessel or wherein the second reaction vessel is not in fluid connection with the first reaction vessel. For example, the heat transfer component is not in fluid connection with the first reaction vessel and wherein the second reaction vessel is not in fluid connection with the first reaction vessel.

[0013] In some embodiments, the heat transfer component comprises at least one surface which is configured to transfer thermal energy between the interior of the first reaction vessel and the third fluid.

[0014] In some embodiments, the first fluid comprises C02and at least one other fluid. In some embodiments, the concentration of C02in the first fluid is from about o.oi vol% to about 99.9 vol %.

[0015] In some embodiments, the concentration of C02in the second fluid is from about 1% to about 100% less than in the first fluid. In some embodiments, the third fluid comprises a fluid selected from the group consisting of water, 02, N2, H2, CO, C02, hydrocarbons (such as CH4) and mixtures thereof. In some embodiments, the third fluid comprises C02, optionally wherein the concentration of the C02in the third fluid is greater than about 75 vol.%. In some embodiments, the first reaction vessel is configured to convert calcium oxide into calcium carbonate. In some embodiments, the first reaction vessel comprises a first material, the first material comprising calcium oxide.

[0016] In some embodiments, the first reaction vessel comprises a first input, a first output and at least one first fluid pathway between the first input and the first output. In some embodiments, the first reaction vessel comprises a packed bed, for example a thermally well mixed packed bed.

[0017] In some embodiments, the second reaction vessel is configured to convert calcium carbonate into calcium oxide. In some embodiments, the second reaction vessel comprises a second material, the second material comprising calcium carbonate. In some embodiments, the second reaction vessel comprises a second input, a second output and at least one second fluid pathway between the second input and the second output. In some embodiments, the second reaction vessel comprises a packed bed, for example a thermally well mixed packed bed.

[0018] In a second aspect, the invention relates to a system comprising a first reaction vessel, an auxiliary vessel and a first auxiliary heat exchanger, wherein:

[0019] (i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid;

[0020] (ii) the auxiliary vessel is configured to output the first fluid; and

[0021] (iii) the first auxiliary heat exchanger is configured to transfer thermal energy between the first fluid and the second fluid.

[0022] In some embodiments, the auxiliary vessel is configured to accept an input fluid and convert the input fluid into the first fluid. In some embodiments, the auxiliary vessel is a combustion vessel. In a third aspect, the invention relates to a method, the method comprising the steps of: converting a first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; transferring thermal energy between the first reaction vessel and a third fluid in a heat transfer component; and providing the third fluid to a second reaction vessel.

[0023] In some embodiments, the method comprises the step of converting calcium oxide into calcium carbonate in the first reaction vessel. In some embodiments, the method comprises the step of converting convert calcium carbonate into calcium oxide in the second reaction vessel.

[0024] In some embodiments, providing the third fluid to a second reaction vessel comprises providing the third fluid to an input of the second reaction vessel. In a fourth aspect, the invention relates to a method, the method comprising the steps of: outputting a first fluid from an auxiliary vessel; converting the first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; and transferring thermal energy between the first fluid and the second fluid in a first auxiliary heat exchanger. In a fifth aspect, the invention relates to a use of a system described herein in relation to the first aspect.

[0025] In a sixth aspect, the invention relates to a use of a system described herein in relation to the second aspect.

[0026] Brief Description of Drawings

[0027] The present invention will now be described with reference to the accompanying drawings, in which:

[0028] Figures 1 to 2 are schematics of systems according to various embodiments described herein.

[0029] Figures 3 to 6 are schematics of systems according to various embodiments described herein.

[0030] Figure 7 is a schematic of a system according to an embodiment described herein.

[0031] Figure 8 is a schematic of a system according to an embodiment described herein.

[0032] Figure 9 is a schematic of a system according to an embodiment described herein.

[0033] Figure 10 is a flow diagram of a process according to an embodiment described herein. Figure 11 is a flow diagram of a process according to an embodiment described herein. Figure 12 is a diagram of an embodiment described herein.

[0034] Figures 13 to 16 are schematics of vessels according to various embodiments described herein.

[0035] Figure 17 is a schematic of a vessel and heat transfer device according to various embodiments described herein.

[0036] Figures 18 to 19 are schematics of vessels and heat transfer components according to various embodiments described herein.

[0037] Detailed Description

[0038] The invention relates to systems and methods. The systems and methods are particularly useful for carbon capture and storage. The systems and methods are also particularly useful for providing support for an electrical power grid.

[0039] Carbon capture and storage (CCS) and electricity storage are commonly viewed as being two distinct methods of climate change mitigation. However, the present invention is based on technological developments that allow CCS and electricity storage to be combined. The systems and methods described herein combine these principles and are therefore improved methods and systems that can play a major part in the global energy transformation. In a first aspect, the invention relates to a system comprising a first reaction vessel, a second reaction vessel and a heat transfer component, wherein:

[0040] (i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid;

[0041] (ii) the heat transfer component is configured to transfer thermal energy between the first reaction vessel and a third fluid; and (iii) the second reaction vessel is configured to accept the third fluid from the heat transfer component. Figure i shows a system comprising a first reaction vessel (i), a second reaction vessel (2) and a heat transfer component (3). In figure 1, there is shown a first fluid (4), a second fluid (5), and a third fluid (6). Also shown is a fourth fluid (7).

[0042] The first reaction vessel is configured such that the concentration of C02in the second fluid is less than the concentration of C02in the first fluid. As such, the first reaction vessel acts a carbon capture and storage vessel. In this way, C02can be removed from a first fluid (such as a flue gas from an industrial process). For example, the first reaction vessel may be a carbonator. The removal of C02from the first fluid via a carbonation reaction is known to be exothermic. As such, thermal energy is produced. The heat energy produced in conventional carbonators is passed directly to an energy recovery system (such as a system comprising a turbine) to recoveiy the energy in the form of electricity. However, this kind of system merely creates electrical energy at the time that the exothermic reaction is proceeding and therefore cannot assist in electrical energy storage for an electrical grid.

[0043] In contrast, the present systems include (ii) a heat transfer component that is configured to transfer thermal energy between the first reaction vessel and a third fluid; and (iii) a second reaction vessel that is configured to accept the third fluid from the heat transfer component. In this way, the thermal energy produced in the first reaction vessel can be passed to a second reaction vessel and thus provide the thermal energy to a reaction to in the second reaction vessel. In this way, the thermal energy does not need to be immediately converted to electricity but can instead be used to create a store of energy. For example, the thermal energy can be provided to a second reaction vessel which is configured to produce C02(such as a calciner), thus providing a sink for the thermal energy.

[0044] One example of such a system is conceptually shown in figure 12. In figure 12 a first fluid is provided to a carbonator which produces a second fluid (which has a concentration of C02that is less than the concentration of C02in the first fluid). Thermal energy is usually required to initiate this reaction (for example to provide the first fluid at an optimum temperature and pressure). Thermal energy produced by this exothermic reaction is then passed to a calciner which produces C02in a storable form. As such, when the carbonator and the calciner are operating, the system removes C02from a first fluid and produces C02in a storable form (thereby acting as carbon capture and storage system). Because this operation requires energy (for example, electrical energy taken from an electrical grid), the system acts a battery. This mode ideally operates when the required energy is relatively cheap (for example when there is little demand on the electrical grid and the price of energy is therefore reduced). However, when the price of energy is relatively expensive (for example when there is a great demand on the electrical grid and the price of energy is therefore increased), the system can reduce or stop the rate of the calcination reaction and instead use the thermal energy produced by the carbonator to directly supply energy to the electrical grid (whilst at the same time, removing C02from the fist fluid). In this way, the system can provide energy when needed to the electrical grid whilst removing C02from the first fluid. This system is therefore capable of continuously removing C02from the first fluid whilst being able to conveniently either providing energy to an electrical grid or removing energy from an electrical grid. As such, the present systems act as a new form of carbon capture battery.

[0045] Heat Transfer Component

[0046] A heat transfer component is a device / component which is configured to transfer heat (thermal energy) between a first medium and a second medium. The heat transfer component is configured to transfer thermal energy between the first reaction vessel and a third fluid. As used herein, the transfer of thermal energy may be by conduction or radiation. For example, the heat transfer component of the first aspect is configured to conduct thermal energy between the first reaction vessel and the third fluid. The heat transfer component may be any device / component which fulfils the purpose of being able to transfer thermal energy between the first reaction vessel and a third fluid.

[0047] In some embodiments, the heat transfer component is not in fluid connection with the first reaction vessel. For example, the heat transfer component comprises an interior volume which is configured to comprise the third fluid. The interior volume of the heat transfer component may not be in fluid connection with an interior of the first reaction vessel. In some embodiments, the heat transfer component is configured such that when the second reaction vessel is in use, it is not in fluid connection with the first reaction vessel. In some embodiments, the heat transfer component is configured such that when it is in use, it is not in fluid connection with the first reaction vessel. In some embodiments, the heat transfer component is configured such that it cannot be made in fluid connection with the first reaction vessel.

[0048] When it is said that the second reaction vessel is “in use”, it may mean when the second reaction vessel receives the third fluid or when the second reaction vessel is in operation (such as when a chemical reaction is taking place within the second reaction vessel).

[0049] In some embodiments, there is no output of the first reaction vessel that is in fluid connection with the second reaction vessel. For example, there is no output of the first reaction vessel that is in fluid connection with an input of the second reaction vessel. For example, there is no output of the first reaction vessel that is in fluid connection with the interior of the second reaction vessel.

[0050] In some embodiments, the second reaction vessel is not in fluid connection with the first reaction vessel. For example, there is no fluid pathway between the first reaction vessel and the second reaction vessel. For example, there is no fluid pathway between the interior of the first reaction vessel and the second reaction vessel.

[0051] Particularly advantageous heat transfer components are shown in figures 18 and 19 in which the heat transfer components are shown relative to the first reaction vessel.

[0052] The heat transfer components described herein are particularly advantageous because they allow thermal energy from the first reaction vessel to be transferred to a third fluid. The third fluid can then be provided to the second reaction vessel. This allows thermal energy to be removed from the first reaction vessel, thereby helping to maintain the first reaction vessel at an approximately constant temperature throughout. For example, a temperature that is optimal for the reaction to proceed within the first reaction vessel.

[0053] The heat transfer components described herein are also particularly advantageous because they help to reduce the thermal gradient along a longitudinal axis of the first reaction vessel. Usually, the first reaction vessel will have a first end which is configured to accept the first fluid and a second end that is configured to output the second fluid. Along the longitudinal axis of the first reaction vessel, C02can be removed from the first fluid by an exothermic reaction (such as a carbonation reaction). This means that towards the end of the first reaction vessel that is configured to accept the first fluid, the temperature of the reaction vessel will be greater than towards the end of the first reaction vessel that is configured to output the second fluid. Minimising this thermal gradient increases the efficiency of the carbonation reaction.

[0054] In some embodiments, the heat transfer component comprises at least one surface which is configured to transfer thermal energy between the interior of the first reaction vessel and the third fluid. For example, the heat transfer component comprises at least one surface which is configured to conduct thermal energy between the interior of the first reaction vessel and the third fluid.

[0055] The at least one surface of the heat transfer component may be any surface(s) that fulfils the purpose of being able to transfer thermal energy between the interior of the first reaction vessel and the third fluid. For example, each of the at least one surface may comprise a material that allows thermal energy to be transferred between the interior of the first reaction vessel and the third fluid. Such materials may be selected from the group consisting of metals, metal alloys, polymers, ceramics, composite materials and mixtures thereof. For example, each of the at least one surface may individually comprise stainless steel, aluminium, ceramic materials (such as silicon carbide and alumina) or graphite.

[0056] Preferably, the heat transfer component is (partially or wholly) within an interior of the first reaction vessel. However, the interior of the heat transfer component is not in fluid connection with an interior of the first reaction vessel. As such, the third fluid may not be in fluid connection with the interior of the first reaction vessel.

[0057] The first reaction vessel may comprise a shell (for example, an outer shell) and an interior volume (within the shell). The interior of the first reaction vessel may be a single cavity within a shell (exterior wall). The interior of the first reaction vessel may be multiple cavities within a shell (exterior wall). In this way, the shell defines the exterior of the first reaction vessel. The cavity / cavities within the shell / exterior wall defines the interior of the first reaction vessel. In some embodiments, first reaction vessel has one or more shells. For example, the first reaction vessel has one, two or three shells. Each of the one or more shells may be made of stainless steel, alumina and / or quartz. In some embodiments, the heat transfer component comprises or consists of one or more tubular members. The one or more tubular members may be configured to comprise the third fluid. The one or more tubular members may comprise the third fluid. The one or more tubular members are not in fluid connection with the interior of the first reaction vessel. The one or more tubular members may be (partially or wholly) within an interior of the first reaction vessel. For example, the one or more tubular members may be positioned within a section of the interior of the first reaction vessel. Alternatively or additionally, the one or more tubular members may (partially or wholly) on an exterior of the first reaction vessel. The purpose of the tubular members is to provide a surface area which allows the transfer thermal energy between the interior of the first reaction vessel and the third fluid. As such, the one or more tubular members may comprise at least one surface which is configured to transfer thermal energy between the interior of the first reaction vessel and the third fluid.

[0058] In some embodiments, the heat transfer component comprises one or more tubular members which are positioned (partially or wholly) within the first reaction vessel. For example, one or more tubular members may be positioned within the first reaction vessel such that they are substantially perpendicular with a longitudinal axis of the first reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned within the first reaction vessel in a helical or coil-like arrangement.

[0059] In some embodiments, the heat transfer component comprises one or more tubular members which are positioned (partially or wholly) on the exterior of the first reaction vessel. For example, one or more tubular members may be positioned on the exterior of the first reaction vessel such that they are substantially perpendicular with a longitudinal axis of the first reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned on the exterior of the first reaction vessel in a helical or coil-like arrangement.

[0060] When the heat transfer component comprises one or more tubular members, each of the tubular members may be in fluid connection with each other. In some embodiments, the first reaction vessel comprises one or more internal volumes. The one or more internal volumes may be separated by the heat transfer component or by portions of the heat transfer component. For example, the first reaction vessel may comprise one, two, three, four, five or six internal volumes. The one or more internal volumes may be tubular members (for example tubular members configured such that a chemical reaction can take place within their interior). The heat transfer component may comprise the volume wholly or partially surrounding the one or more internal volumes. Each heat transfer component described herein may comprise an input and an output. The input may be configured to accept the third fluid. The output may be configured to output the third fluid. The heat transfer component may comprise one or more inputs (for example one, two or three inputs). At least one of the one or more inputs may be configured to accept the third fluid. The heat transfer component may comprise one or more outputs (for example one, two or three outputs). At least one of the one or more outputs may be configured to output the third fluid.

[0061] At least one of the one or more outputs may be configured to output the third fluid at a temperature that is greater than the temperature of the third fluid accepted by the input of the heat transfer component.

[0062] First Reaction Vessel

[0063] The first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid. As such, the first reaction vessel may be any reaction vessel that fulfils this purpose. For example, the first reaction vessel is configured to reduce the concentration of C02in the first fluid and thereby produce the second fluid. For example, the first reaction vessel is not an absorption / adsorption vessel.

[0064] A reaction vessel as used herein is a vessel which is configured such that a chemical reaction can take place within its interior. The first reaction vessel may comprise a shell (for example, an outer shell) and an interior volume (within the shell). The interior of the first reaction vessel may be a single cavity within a shell (exterior wall). The interior of the first reaction vessel may be multiple cavities within a shell (exterior wall). In this way, the shell defines the exterior of the first reaction vessel. The cavity / cavities within the shell / exterior wall defines the interior of the first reaction vessel.

[0065] In some embodiments, first reaction vessel has one or more shells. For example, the first reaction vessel has one, two or three shells. Each of the one or more shells may be made of stainless steel, alumina and / or quartz.

[0066] In some embodiments, the first reaction vessel is configured such that its interior may be at an elevated pressure, for example a pressure of between about i xio5Pa and about 25 xio5Pa. In some embodiments, the first reaction vessel has an interior that is at an elevated pressure, for example a pressure of between about 1 xio5Pa and about 25 xio5Pa.

[0067] In some embodiments, the first reaction vessel is configured such that its interior may be at an elevated temperature, for example a temperature of between about 500 °C and about 1000 °C. In some embodiments, the first reaction vessel has an interior that is at an elevated temperature, for example a temperature of between about 500 °C and about 1000 °C. In some embodiments, the first reaction vessel comprises a first material. The first material may be configured to convert the first fluid into the second fluid. In some embodiments, the first reaction vessel comprises a first material which is able to convert the first fluid into the second fluid. The first material may be any material known to the skilled person that fulfils the purpose of converting the first fluid into the second fluid.

[0068] In some embodiments, the first material comprises a metal oxide or a combination of metal oxides. In some embodiments, the metal of each of the metal oxides is independently selected from the group consisting of alkali metals, alkali earth metals, transition metals and mixtures thereof. Preferably, the metal of each of the metal oxides is independently selected from the group consisting of alkali earth metals. For example, the metal of each of the metal oxides is independently selected from the group consisting of Be, Mg, Ca, Sr, Ba, Ra and mixtures thereof. Preferably, the metal of each of the metal oxides is Ca. For example, the metal oxide comprises or consists of calcium oxide (CaO). For example, the first material comprises or consists of calcium oxide (CaO). In some embodiments, the first material comprises a particulate material. For example, the first material is a particulate metal oxide (such as particulate CaO). In some embodiments, the particulate material (particulate metal oxide) has a particle size of between about too micrometres to 10000 micrometres (as measured by sieve analysis).

[0069] In some embodiments, the particulate material (particulate metal oxide) has an average (D50) particle size of between about too micrometres to 10000 micrometres (as measured by sieve analysis). In some embodiments, the first material comprises a support material. For example, the first material comprises an additional / support material selected from the group consisting of MgO, CaZrO3, A12O3, Ca3Al2Oe, Cai2Ali4O33, Nd2O3, Y2O3, La2O3, and Ce02.

[0070] In some embodiments, the first reaction vessel is configured to convert the metal oxide (or the combination of metal oxides) into a metal carbonate (or a combination of corresponding metal carbonates). For example, the first reaction vessel is configured to convert the metal oxide (e.g. CaO) into a metal carbonate (e.g. CaCO3). Preferably, the first reaction vessel is configured to convert calcium oxide into calcium carbonate. For example, the first reaction vessel may be a carbonator (a reaction vessel configured to allow carbonation of a metal oxide). The conversion of a metal oxide to a metal carbonate may be an exothermic reaction. For example the conversion of calcium oxide and C02to calcium carbonate is exothermic (AH -178 k. J / mol C02).

[0071] In some embodiments, the first reaction vessel is configured to react C02in the first fluid with the first material and thereby produce the second fluid. For example, the first reaction vessel may be configured to react a proportion of the C02in the first fluid with the first material and thereby produce the second fluid.

[0072] In some embodiments, the first reaction vessel comprises an input, an output and at least one fluid pathway between the input and the output. The fluid pathway of the first reaction vessel is any fluid pathway between the input of the first reaction vessel and the output of the first reaction vessel. The first reaction vessel may comprise one or more fluid pathways. For example, the first reaction vessel may comprise one, two, three or four fluid pathways. The first material may be positioned along / in the at least one fluid pathway. In some embodiments, the first reaction vessel comprises a packed bed. The packed bed may comprise the first material described herein. For example, the first reaction vessel may be a packed bed reactor. The first reaction vessel may be a fluidised bed reactor or a fixed bed reactor. Preferably, the first reaction vessel is a fixed bed reactor. The packed bed may be positioned along / in the at least one fluid pathway.

[0073] The first reaction vessel may comprise a thermally well mixed packed bed. That is, the packed bed is able to maintain an approximately constant temperature throughout when in use.

[0074] In some embodiments, the first reaction vessel comprises a heat transfer device. The heat transfer device may be a sealed / closed device. That is, the heat transfer device comprises an interior volume that is not in fluid connection with the exterior of the heat transfer device (or the interior of the first reaction vessel). The heat transfer device may comprise a working fluid. The purpose of the heat transfer device is to transfer thermal energy between the interior of the first reaction vessel and the working fluid. In operation, thermal energy in the interior of the first reaction vessel is transferred to a proportion of the working fluid. The thermal energy can then be transferred to an area of the first reaction vessel which has a lower temperature (by the working fluid via a thermal gradient).

[0075] A particularly advantageous heat transfer device is shown in figure 17 in which the heat transfer device is shown relative to the first reaction vessel. The heat transfer device described herein is particularly advantageous because it helps to reduce the thermal gradient along a longitudinal axis of the first reaction vessel. Usually, the first reaction vessel will have a first end which is configured to accept the first fluid and a second end that is configured to output the second fluid. Along the longitudinal axis of the first reaction vessel, C02can be removed from the first fluid by an exothermic reaction (such as a carbonation reaction). This means that towards the end of the first reaction vessel that is configured to accept the first fluid, the temperature of the reaction vessel will be greater than towards the end of the first reaction vessel that is configured to output the second fluid. Minimising this thermal gradient increases the efficiency of the carbonation reaction. The heat transfer device may comprise or consist of one or more tubular members. The one or more tubular members may be configured to comprise a working fluid. The one or more tubular members may comprise the working fluid. The one or more tubular members are not in fluid connection with the interior of the first reaction vessel. The one or more tubular members may be (partially or wholly) within an interior of the first reaction vessel. For example, the one or more tubular members may be positioned within a section of the interior of the first reaction vessel. Alternatively or additionally, the one or more tubular members may (partially or wholly) on an exterior of the first reaction vessel. The purpose of the tubular members is to provide a surface area which allows the transfer thermal energy between the interior of the first reaction vessel and the working fluid. As such, the one or more tubular members may comprise at least one surface which is configured to transfer thermal energy between the interior of the first reaction vessel and the working fluid. In some embodiments, the heat transfer device comprises one or more tubular members which are positioned (partially or wholly) within the first reaction vessel. For example, one or more tubular members may be positioned within the first reaction vessel such that they are substantially perpendicular with a longitudinal axis of the first reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned within the first reaction vessel in a helical or coil-like arrangement.

[0076] Preferably, the heat transfer device comprises one or more tubular members which are positioned (partially or wholly) on the exterior of the first reaction vessel. For example, one or more tubular members may be positioned on the exterior of the first reaction vessel such that they are substantially perpendicular with a longitudinal axis of the first reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned on the exterior of the first reaction vessel in a helical or coil-like arrangement. When the heat transfer device comprises one or more tubular members, each of the tubular members may be in fluid connection with each other.

[0077] The working fluid may comprise a refrigerant, water ammonia or mixtures thereof. In some embodiments, the working fluid comprises naphthalene, dowtherm, mercury, sulphur, caesium, rubidium, potassium, or sodium. Second Reaction Vessel

[0078] The second reaction vessel is configured to accept the third fluid from the heat transfer component. The second reaction vessel may be configured to output a fourth fluid which comprises C02. For example, the second reaction vessel may be configured to produce C02. As such, the second reaction vessel may be any reaction vessel that fulfils this purpose. For example, the first reaction vessel is not an absorption / adsorption vessel. A reaction vessel as used herein is a vessel which is configured such that a chemical reaction can take place within its interior. The second reaction vessel may comprise a shell (for example, an outer shell) and an interior volume (within the shell). The interior of the second reaction vessel may be a single cavity within a shell (exterior wall). The interior of the second reaction vessel may be multiple cavities within a shell (exterior wall). In this way, the shell defines the exterior of the first reaction vessel. The cavity / cavities within the shell / exterior wall defines the interior of the second reaction vessel.

[0079] In some embodiments, second reaction vessel has one or more shells. For example, the second reaction vessel has one, two or three shells. Each of the one or more shells may be made of stainless steel, alumina and / or quartz.

[0080] In some embodiments, the second reaction vessel is configured such that its interior may be at an atmospheric or reduced pressure, for example a pressure of between about 1 xio4Pa and about 1 xio5Pa. In some embodiments, the second reaction vessel has an interior that is at an atmospheric or reduced pressure, for example a pressure of between about 1 xio4Pa and about 1 xio5Pa.

[0081] In some embodiments, the second reaction vessel is configured such that its interior may be at an elevated temperature, for example a temperature of between about 600 °C and about 1200 °C. In some embodiments, the first reaction vessel has an interior that is at an elevated temperature for example a temperature of between about 600 °C and about 1200 °C. The second reaction vessel may be configured to produce C02by a chemical reaction. For example, the second reaction vessel may be configured to produce C02by converting a second material into a third material, thereby producing C02. For example, the second reaction vessel may be configured to convert a metal carbonate into a metal oxide, thereby producing C02. In some embodiments, the second reaction vessel comprises a second material. The second material may be configured to produce a fourth fluid. In some embodiments, the second reaction vessel comprises a second material which is able to be converted into a third material, thereby producing C02. The second material may be any material known to the skilled person that fulfils this purpose.

[0082] In some embodiments, the second material comprises a metal carbonate or a combination of metal carbonates. In some embodiments, the metal of each of the metal carbonates is independently selected from the group consisting of alkali metals, alkali earth metals, transition metals and mixtures thereof. Preferably, the metal of each of the metal carbonates is independently selected from the group consisting of alkali earth metals. For example, the metal of each of the metal carbonates is independently selected from the group consisting of Be, Mg, Ca, Sr, Ba, Ra and mixtures thereof. Preferably, the metal of each of the metal carbonates is Ca. For example, the metal carbonates comprises or consists of calcium carbonate (CaCO3). For example, the second material comprises or consists of calcium carbonate (CaCO3).

[0083] In some embodiments, the first material comprises a particulate material. For example, the first material is a particulate metal carbonate (such as particulate CaCO3). In some embodiments, the particulate material (particulate metal carbonate) has a particle size of between about too micrometres to 10000 micrometres (as measured by sieve analysis). In some embodiments, the particulate material (particulate metal carbonate) has an average (D50) particle size of between about 100 micrometres to 10000 micrometres (as measured by sieve analysis). In some embodiments, the second material comprises a support material. For example, the second material comprises an additional / support material selected from the group consisting of MgO, CaZrO3, A12O3, Ca3Al2Oe, Cai2Ali4O33, Nd2O3, Y2O3, La2O3, and Ce02.

[0084] In some embodiments, the second reaction vessel is configured to convert the metal carbonate (or the combination of metal carbonates) into a metal oxide (or a combination of corresponding metal oxides). For example, the second reaction vessel is configured to convert the metal carbonate (e.g. CaCO3) into a metal oxide (e.g. CaO). Preferably, the second reaction vessel is configured to convert calcium carbonate into calcium oxide (and thereby produce C02). For example, the second reaction vessel may be a calciner (a reaction vessel configured to allow calcination of a metal carbonate). The conversion of a metal carbonate to a metal oxide may be an endothermic reaction.

[0085] For example, the conversion of calcium carbonate to calcium oxide and C02is endothermic (AH 178 k. J / mol C02).

[0086] In some embodiments, the second reaction vessel comprises an input, an output and at least one fluid pathway between the input and the output. The fluid pathway of the second reaction vessel is any fluid pathway between the input of the second reaction vessel and the output of the second reaction vessel. The second reaction vessel may comprise one or more fluid pathways. For example, the second reaction vessel may comprise one, two, three or four fluid pathways.

[0087] In some embodiments, the second reaction vessel comprises a packed bed. The packed bed may comprise the second material described herein. For example, the second reaction vessel may be a packed bed reactor. The second reaction vessel may be a fluidised bed reactor or a fixed bed reactor. Preferably, the second reaction vessel is a fixed bed reactor.

[0088] The second reaction vessel may comprise a thermally well mixed packed bed. That is, the packed bed is able to maintain an approximately constant temperature throughout when in use.

[0089] In some embodiments, the second reaction vessel comprises one or more interior volumes or cavities. For example, the second reaction vessel may comprise one, two, three, four, five or six interior volumes or cavities. Each of the one or more interior volumes or cavities may be coupled to another of the one or more interior volumes or cavities. For example, each of the one or more interior volumes or cavities is coupled to the other of the one or more interior volumes or cavities. In some embodiments, each of the one or more interior volumes or cavities is coupled to another of the one or more interior volumes or cavities by a fluid pathway. Each of the fluid pathways may include a valve. Each of the valves may be configured such that a user can control which of the one or more interior volumes or cavities is in fluid connection with the input of the second reaction vessel. In this way, a user can determine how many of the one or more interior volumes or cavities is coupled to the input of the second reaction vessel (and thereby the third fluid). The user can therefore vaiy the capacity of the second reaction vessel and thus improve the round-trip efficiency of the system. In some embodiments, each of the one or more interior volumes or cavities comprises a heater (for example an electrical heater). For example, the heater may comprise a resistive heating element. Each of the heater(s) may be configured to heat the internal volume or cavity. Each of the heater(s) may be configured to heat the second material. Each of the heater(s) may be configured to heat the third fluid.

[0090] The heater(s) described herein help to maintain the first reaction vessel at an approximately constant temperature. For example, a temperature that is optimal for the reaction to proceed within the second reaction vessel. The heater(s) described herein also help to ensure that each segment (volume or cavity) is capable of allowing the reaction to proceed within a specific segment of the second reaction vessel.

[0091] A particularly advantageous first reaction vessel is shown in figure 13 in which heater(s) are shown relative to the second reaction vessel. The heater(s) described herein are particularly advantageous as they allow the second reaction vessel to have an approximately constant temperature throughout. That is, the heater(s) described herein minimise the thermal gradient within the second reaction vessel. This means that the round-trip efficiency of the system can be increased or optimised. In some embodiments, it is advantageous for the system to include the heater(s) described herein because it reduces the need to further heat or pressurise the third fluid before the input of the second reaction vessel. The heater(s) also increase the efficiency of fixed beds, thereby reducing the need to use a fluidised bed.

[0092] In some embodiments, the second reaction vessel comprises one or more electrically conductive elements. The electrically conductive elements may be positioned in the interior volume of the second reaction vessel such that they define one or more interior volumes or cavities. For example, the second reaction vessel may comprise one, two, three, four, five or six interior volumes or cavities. Alternatively, the electrically conductive elements may be positioned throughout the second reaction vessel (for example in a random distribution or uniform distribution). The electrically conductive elements may be positioned throughout the whole or a part of the second reaction vessel (for example in a random distribution or uniform distribution).

[0093] Particularly advantageous first reaction vessels are shown in figures 14, 15 and 16 in which electrically conductive element(s) are shown relative to the second reaction vessel.

[0094] The electrically conductive elements may be made of an electrically conductive material. For example, the electrically conductive elements may comprise (i) graphite, silicon carbide (SiC), zirconia (Zr02), refractory metals, ceramic composites, and / or high-temperature alloys; or (ii) graphite, silicon carbide (SiC), molybdenum disilicide (MoSi2), tungsten, zirconia (Zr02), boron nitride (BN), refractoiy metals (such as tantalum, niobium, or rhenium), ceramic composites (such as alumina reinforced with silicon carbide whiskers), and / or high-temperature alloys (such as Inconel or Hastelloy).

[0095] Each of the one or more interior volumes or cavities may be coupled to another of the one or more interior volumes or cavities. For example, each of the one or more interior volumes or cavities is coupled to the other of the one or more interior volumes or cavities. In some embodiments, each of the one or more interior volumes or cavities is coupled to another of the one or more interior volumes or cavities by a fluid pathway. Each of the fluid pathways may include a valve. Each of the valves may be configured such that a user can control which of the one or more interior volumes or cavities is in fluid connection with the input of the second reaction vessel. In this way, a user can determine how many of the one or more interior volumes or cavities is coupled to the input of the first reaction vessel (and thereby the third fluid). The user can therefore vary the capacity of the second reaction vessel and thus improve the round-trip efficiency of the system. In some embodiments, each of the one or more electrically conductive elements can be heated by applying a voltage to the respective one or more electrically conductive elements. For example, by applying a voltage that creates a current through the element and heats up the element through Joules heating. For example, the electrically conductive elements may comprise graphite, silicon carbide (SiC), molybdenum disilicide (MoSi2), tungsten, zirconia (Zr02), boron nitride (BN), refractory metals (such as tantalum, niobium, or rhenium), ceramic composites (such as alumina reinforced with silicon carbide whiskers), and / or high-temperature alloys (such as Inconel or Hastelloy).

[0096] In some embodiments, each of the one or more electrically conductive elements can be heated by applying a magnetic field to the respective one or more electrically conductive elements. For example, by positioning an electrically conductive material in a magnetic field, electrical current is induced within the material and heats it up through Joules heating. For example, the electrically conductive elements may comprise graphite, silicon carbide (SiC), zirconia (Zr02), refractoiy metals, ceramic composites, and / or high-temperature alloys

[0097] Each of the one or more electrically conductive elements may be configured to heat the internal volume or cavity. Each of the one or more electrically conductive elements may be configured to heat the second material.

[0098] The electrically conductive element(s) described herein help to maintain the first reaction vessel at an approximately constant temperature. For example, a temperature that is optimal for the reaction to proceed within the second reaction vessel. The electrically conductive element(s) described herein are particularly advantageous as they allow the second reaction vessel to have an approximately constant temperature throughout. That is, the electrically conductive element(s) described herein minimise the thermal gradient within the second reaction vessel. This means that the round-trip efficiency of the system can be increased or optimised. In some embodiments, it is advantageous for the system to include the electrically conductive element(s) described herein because it reduces the need to further heat or pressurise the third fluid before the input of the second reaction vessel. The electrically conductive element(s) also increase the efficiency of fixed beds, thereby reducing the need to use a fluidised bed. Use of the heater(s) or electrically conductive element(s) described herein is also particularly advantageous because they can provide thermal energy required for an endothermic reaction. For example, in a calciner where the reaction is endothermic, the reaction may require thermal energy in excess of that provided by the third fluid. In some embodiments, the second reaction vessel comprises a heat transfer device. The heat transfer device may be a sealed / closed device. That is the heat transfer device comprises an interior volume that is not in fluid connection with the exterior of the heat transfer device (or the interior of the second reaction vessel). The heat transfer device may comprise a working fluid. The purpose of the heat transfer device is to transfer thermal energy between the interior of the second reaction vessel and the working fluid. In operation, thermal energy in the interior of the second reaction vessel is transferred to a proportion of the working fluid. The thermal can then be transferred to an area of the second reaction vessel which has a lower temperature (by the working fluid via a thermal gradient). The heat transfer device may comprise or consist of one or more tubular members. The one or more tubular members may be configured to comprise a working fluid. The one or more tubular members may comprise the working fluid. The one or more tubular members are not in fluid connection with the interior of the second reaction vessel. The one or more tubular members may be (partially or wholly) within an interior of the second reaction vessel. For example, the one or more tubular members may be positioned within a section of the interior of the second reaction vessel. Alternatively or additionally, the one or more tubular members may (partially or wholly) on an exterior of the second reaction vessel. The purpose of the tubular members is to provide a surface area which allows the transfer thermal energy between the interior of the second reaction vessel and the working fluid. As such, the one or more tubular members may comprise at least one surface which is configured to transfer thermal energy between the interior of the second reaction vessel and the working fluid.

[0099] In some embodiments, the heat transfer device comprises one or more tubular members which are positioned (partially or wholly) within the second reaction vessel.

[0100] For example, one or more tubular members may be positioned within the second reaction vessel such that they are substantially perpendicular with a longitudinal axis of the second reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned within the second reaction vessel in a helical or coil-like arrangement.

[0101] Preferably, the heat transfer device comprises one or more tubular members which are positioned (partially or wholly) on the exterior of the second reaction vessel. For example, one or more tubular members may be positioned on the exterior of the second reaction vessel such that they are substantially perpendicular with a longitudinal axis of the second reaction vessel. Alternatively or additionally, the one or more tubular members may be positioned on the exterior of the second reaction vessel in a helical or coil-like arrangement.

[0102] When the heat transfer device comprises one or more tubular members, each of the tubular members may be in fluid connection with each other.

[0103] The working fluid may comprise a refrigerant, water ammonia or mixtures thereof. In some embodiments, the working fluid comprises naphthalene, dowtherm, mercury, sulphur, caesium, rubidium, potassium, or sodium.

[0104] First Mode

[0105] The system may be configured to operate in a first mode or a second mode. When the system is configured to operate in the first mode, the second reaction vessel is configured to accept the third fluid from the heat transfer component. For example, the heat transfer component is in fluid connection with the second reaction vessel (for example, the interior of the second reaction vessel).

[0106] Preferably, the heat transfer component comprises an output and the second reaction vessel comprises an input, wherein the output of the heat transfer component is coupled to the input of the second reaction vessel. That is, the output of the heat transfer component is in fluid connection with the input of the second reaction vessel. In this way, the third fluid is in fluid connection with the second reaction vessel (for example, the interior of the second reaction vessel). This is particularly useful because when the first reaction vessel is configured to convert a metal carbonate into a metal oxide, the chemical decomposition reaction may require thermal energy input. Part of this thermal energy input can be provided by the thermal energy of the third fluid. This reduces the need to increase use heaters or compressors and thus increases the roundtrip efficiency of the system.

[0107] The first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid. The first reaction vessel may be configured to accept the first fluid at an elevated temperature and / or pressure. For example, the first reaction vessel may be configured to accept the first fluid at a temperature of between about 300 °C and about 700 °C and / or a pressure of between about 1 xio5Pa and about 25 xio5Pa. In some embodiments, the system comprises an auxiliary vessel configured to output the first fluid. The auxiliary vessel may be configured to accept an input fluid and convert the input fluid into the first fluid. For example, the auxiliary vessel may be configured to increase the temperature of the input fluid such that it is converted into the first fluid. Additionally or alternatively, the auxiliary vessel may be configured to change the composition of the input fluid such that it is converted into the first fluid. For example, the auxiliary vessel may be configured to increase the temperature and / or C02concentration of the input fluid. In this way, the auxiliary vessel may convert the input fluid into the first fluid.

[0108] Use of an auxiliary vessel is particularly advantageous because it can be used to ensure that the first fluid has the optimal composition and temperature to result in a high round trip efficiency of the system. Preferably, the auxiliary vessel is a reaction vessel (such a combustions vessel). For example, the auxiliary vessel is a combustion vessel. That is, the auxiliary vessel described herein may be configured to allow a combustion reaction to proceed within it. The features of such vessels depend on the kind of combustion reaction that occurs within and will be known to the skilled person.

[0109] In some embodiments, the input fluid is a fluid from an industrial process. In some embodiments, the input fluid is a waste fluid or by-product from an industrial process.

[0110] In some embodiments, the input fluid is a fluid from a process that generates C02. For example, the process may be a power generation process (such as process for converting fossil fuels into electrical energy), a cement manufacturing process, petrochemical processing process, a steel manufacturing process, or a metal processing process. The input fluid may comprise C02. In some embodiments, the input fluid comprises from about 0.1 vol% to about too vol%, about 99.9 vol%, about 99 vol%, about 95 vol%, about 90 vol%, about 80 vol%, about 70 vol%, about 60 vol%, about 50 vol%, about 40 vol%, about 30 vol%, about 20 vol%, about 10 vol%, or about 5 vol% of C02. For example, the input fluid comprises from about 0.1 vol% to about 20 vol%, about 10 vol%, or about 5 vol% of C02. In some embodiments, the input fluid comprises from about o.i vol%, about i vol%, about 2 vol%, about 5 vol%, about 10 vol%, about 20 vol%, about 30 vol%, about 40 vol%, about 50 vol%, about 60 vol%, about 70 vol%, about 80 vol%, about 90 vol%, or about 95 vol% to about too vol% of C02.

[0111] In some embodiments, the input fluid comprises C02and at least one other fluid. In some embodiments, the input fluid comprises N2, H2, CO, 02, water or mixtures thereof. For example, the input fluid comprises CO, water and H2. In some embodiments, the input fluid comprises less than 1 vol. % particulates. As used herein, particulates refer to particulate such as dust, smoke, soot or mixtures thereof.

[0112] In some embodiments, the system comprises a first auxiliary heat exchanger. The first auxiliary heat exchanger may be coupled to the output of the auxiliary vessel and to the input of the first reaction vessel. As such, there is a fluid pathway from the output of the auxiliary vessel to the input of the first reaction vessel (through the first auxiliary heat exchanger). That is, the system is configured such that the first fluid can be outputted from the auxiliary vessel, pass through the first auxiliary heat exchanger and be accepted by the first reaction vessel.

[0113] Figure 3 shows a system comprising a first reaction vessel (1), a second reaction vessel (2), a heat transfer component (3), and a first auxiliary heat exchanger (9). In figure 3, there is shown a first fluid (4), a second fluid (5), and a third fluid (6). Also shown is a fourth fluid (7).

[0114] Figure 5 shows a system comprising a first reaction vessel (1), a second reaction vessel (2), a heat transfer component (3), a first auxiliary heat exchanger (9), and an auxiliary vessel (11). In figure 5, there is shown a first fluid (4), a second fluid (5), a third fluid (6), and an input fluid (10). Also shown is a fourth fluid (7).

[0115] The purpose of the first auxiliary heat exchanger is to remove thermal energy from the first fluid outputted by the auxiliary vessel. In this way the temperature of the first fluid can be optimised for input into the first reaction vessel (where it may react with a metal oxide as described herein). Additionally, the first auxiliary heat exchanger may be configured to transfer thermal energy between the first fluid and the second fluid. For example, a second fluid that is outputted from the first reaction vessel (thereby optimising the temperature of the second fluid).

[0116] The first auxiliary heat exchanger may be any heat exchanger that can fulfil the purpose of transferring thermal energy from one medium (for example the first fluid) to another medium (for example the second fluid). For example, the first auxiliary heat exchanger is configured to transfer thermal energy between the first fluid and another medium (for example the second fluid). In some embodiments, the system comprises a first turbine. The first turbine may be coupled to the output of the first reaction vessel. As such, there may be a fluid pathway from the output of the first reaction vessel to the first turbine (for example the input of a turbine). The first turbine may be directly coupled to the output of the first reaction vessel (for example by a tubular member such as a pipe). As such, there may be a direct fluid pathway from the output of the first reaction vessel to the first turbine (for example the input of the first turbine). Alternatively, the first turbine may be coupled to the output of the first reaction vessel via a further component. For example, the first auxiliary heat exchanger may be position between the output of the first reaction vessel and the turbine. In this way, the first auxiliary heat exchanger may transfer thermal energy to the second fluid outputted from the first reaction vessel.

[0117] The first turbine may be any turbine. The purpose of the first turbine is to accept the second fluid and output electrical energy. The first turbine may be any turbine that fulfils this purpose. For example, the turbine may be a gas turbine.

[0118] In some embodiments, the system comprises a first fluid compressor coupled to the first reaction vessel. For example, the system comprises a first fluid compressor directly coupled to the input of first reaction vessel. The purpose of the first fluid compressor is to compress the first fluid so that it is at an optimum pressure for entry into the first reaction vessel. Additionally or alternatively, the purpose of the first fluid compressor is to compress the first fluid so that it is at an optimum pressure for entry into the auxiliary vessel. For example, the system comprises a first fluid compressor directly coupled to the input of first auxiliary heat exchanger. In some embodiments, the system comprises a second auxiliaiy heat exchanger. The second auxiliary heat exchanger may be coupled to the output of the heat transfer component and to the input of the second reaction vessel. As such, there is a fluid pathway from the output of the heat transfer component and to the input of the second reaction vessel (through the second auxiliary heat exchanger). That is, the system is configured such that the third fluid can be outputted from the heat transfer component, pass through the second auxiliary heat exchanger and be accepted by the second reaction vessel.

[0119] Figure 2 shows a system comprising a first reaction vessel (i), a second reaction vessel (2), a heat transfer component (3), and a second auxiliary heat exchanger (8). In figure 2, there is shown a first fluid (4), a second fluid (5), a third fluid (6) and a fourth fluid

[0120] (7)-

[0121] Figure 4 shows a system comprising a first reaction vessel (1), a second reaction vessel (2), a heat transfer component (3), a first auxiliary heat exchanger (9) and a second auxiliary heat exchanger (8). In figure 4, there is shown a first fluid (4), a second fluid (5), a third fluid (6), and a fourth fluid (7).

[0122] Figure 6 shows a system comprising a first reaction vessel (1), a second reaction vessel (2), a heat transfer component (3), and a first auxiliary heat exchanger (9) and an auxiliary vessel (11). In figure 6, there is shown a first fluid (4), a second fluid (5), a third fluid (6), a fourth fluid (7) and an input fluid (10).

[0123] The purpose of the second auxiliary heat exchanger is to increase the thermal energy of the third fluid outputted by the heat transfer component. In this way the temperature of the third fluid can be optimised for input into the second reaction vessel (where it may provide thermal energy required to assist in the progress of the decomposition of a metal carbonate as described herein). Additionally, the second auxiliary heat exchanger may be configured to transfer thermal energy between the third fluid and the fourth fluid. For example, a fourth fluid that is outputted from the second reaction vessel (thereby optimising the temperature of the fourth fluid). Preferably, the second auxiliary heat exchanger is configured to transfer thermal energy from the fourth fluid to the third fluid (for example, before the third fluid is accepted by the second reaction vessel). The second auxiliary heat exchanger may be any heat exchanger that can fulfil the purpose of transferring thermal energy from one medium (for example the third fluid) to another medium (for example the fourth fluid). For example, the second auxiliary heat exchanger is configured to transfer thermal energy between the third fluid and another medium (for example the fourth fluid). The second reaction vessel may be configured to output a fourth fluid which comprises C02. The output of the second reaction vessel may be coupled to a storage apparatus. The storage apparatus may comprise a compressor and a storage vessel. The compressor may compress the fourth fluid such that it is suitable for storage in a storage vessel (such as a gas cylinder or tank). This is particularly preferred when the fourth fluid comprises a high concentration of C02. In this way, the C02produced by the second reaction vessel may be stored for later use or sale.

[0124] In some embodiments, the system comprises a third auxiliary heat exchanger. In some embodiments, the output of the second reaction vessel is coupled to an input of the third auxiliary heat exchanger. In some embodiments, the system comprises a second auxiliary heat exchanger and a third auxiliary heat exchanger. In such embodiments, the second auxiliary heat exchanger is positioned between the output of the second reaction vessel and the input of the third auxiliary heat exchanger. In this way, the second auxiliary heat exchanger may be coupled to the output of the second reaction vessel and to the input of the third auxiliary heat exchanger. As such, there is a fluid pathway from the output of the second reaction vessel to the input of the third auxiliary heat exchanger (through the second auxiliary heat exchanger). That is, the system is configured such that the fourth fluid can be outputted from the second reaction vessel, pass through the second auxiliary heat exchanger and be accepted by the third auxiliary heat exchanger.

[0125] Figure 7 shows a system comprising a first reaction vessel, a second reaction vessel, a heat transfer component, a second auxiliary heat exchanger and a third auxiliary heat exchanger. In figure 7, there is shown a first fluid (1, 2), a second fluid (3, 4), a third fluid (5, 6, 7, 8), a fourth fluid (9, 10, 11), and a third medium (12, 13, 14, 15). Various other optional components as described herein are also shown.

[0126] The purpose of the third auxiliary heat exchanger is to transfer thermal energy from the fourth fluid outputted by the second reaction vessel. In this way the thermal energy of the fourth fluid can be transferred to a third medium. The third medium may then be used to power a second turbine. The second turbine may be any turbine. For example, the second turbine may the same or different to the first turbine.

[0127] The third medium may be any fluid. The third medium may comprise or consist of (i) water, (ii) C02), or (iii) an organic fluid such as R-i34a (1,1,1,2-tetrafluoroethane), R-

[0128] 245fa (1,1,1,3,3-pentafluoropropane), R-123 (2,2-dichloro-i,i,i-trifluoroethane), isopentane (2-methylbutane), isobutane (2-methylpropane), n-pentane, n-butane, cyclopentane, dodecane, pentene, toluene, butene, or isohexane (2-methylpentane). Preferably, the third medium comprises or consists of water.

[0129] The third auxiliary heat exchanger may be any heat exchanger that can fulfil the purpose of transferring thermal energy from one medium (for example the fourth fluid) to another medium (for example the third medium). For example, the first auxiliary heat exchanger is configured to transfer thermal energy between the fourth fluid and another medium (for example the third medium). Preferably, the third auxiliary heat exchanger is an evaporator or a superheater.

[0130] In some embodiments, the output of the second reaction vessel may be coupled to the input of the heat transfer component. In such embodiments, part or all of the fourth fluid may be provided to the input of the heat transfer component. When the system comprises a second auxiliary heat exchanger, it may be the output of the second auxiliary heat exchanger that is coupled to the input of the heat transfer component. When the system comprises a third auxiliary heat exchanger, it may be the output of the second auxiliary heat exchanger and / or the third auxiliary heat exchanger that is coupled to the input of the heat transfer component.

[0131] Second Mode

[0132] When the system is configured to operate in the second mode, the second reaction vessel does not need to be operational. As such, the third fluid can be directed to power a third turbine (instead of being directed to the input of the second reaction vessel). For example, the output of the heat transfer component is not coupled to the input of the input of the second reaction vessel. All other features of the system when configured to operate in the second mode may individually be the same as described herein in relation to the first mode. When the system is configured to operate in the second mode, the output of the heat transfer component may be coupled to a third turbine. That is, there is a fluid pathway from the output of the heat transfer component to the third turbine. The third turbine may be any turbine. For example, the third turbine may the same or different to the first turbine.

[0133] In some embodiments, the system comprises a fourth auxiliaiy heat exchanger. In some embodiments, the output of the heat transfer component is coupled to an input of the fourth auxiliary heat exchanger. In some embodiments, the system comprises a first auxiliary heat exchanger and a fourth auxiliary heat exchanger. In such embodiments, the first auxiliary heat exchanger is positioned between the output of the first reaction vessel and the input of the fourth auxiliary heat exchanger. In this way, the first auxiliary heat exchanger may be coupled to the output of the first reaction vessel and to the input of the fourth auxiliary heat exchanger. As such, there is a fluid pathway from the output of the first reaction vessel to the input of the fourth auxiliary heat exchanger

[0134] (through the first auxiliary heat exchanger). That is, the system is configured such that the second fluid can be outputted from the first reaction vessel, pass through the first auxiliary heat exchanger and be accepted by the fourth auxiliaiy heat exchanger. The purpose of the fourth auxiliary heat exchanger is to transfer thermal energy from the second fluid outputted by the second reaction vessel. In this way the thermal energy of the second fluid can be transferred to the third fluid. The third fluid may then be used to power a third turbine. The third turbine may be any turbine. For example, the third turbine may the same or different to the first turbine.

[0135] When the system is configured to operate in the second mode, the third fluid may be any fluid. For example, the third fluid may be as described herein for the third fluid of the first mode. The third fluid may comprise or consist of (i) water, (ii) C02), or (iii) an organic fluid such as R-i34a (1,1,1,2-tetrafluoroethane), R-245fa (1, 1,1, 3,3- pentafluoropropane), R-123 (2,2-dichloro-i,i,i-trifluoroethane), isopentane (2- methylbutane), isobutane (2-methylpropane), n-pentane, n-butane, cyclopentane, dodecane, pentene, toluene, butene, or isohexane (2-methylpentane). Preferably, the third fluid comprises or consists of water. The fourth auxiliary heat exchanger may be any heat exchanger that can fulfil the purpose of transferring thermal energy from one medium (for example the second fluid) to another medium (for example the third fluid). For example, the fourth auxiliary heat exchanger is configured to transfer thermal energy between the second fluid and another medium (for example the third fluid). Preferably, the fourth auxiliary heat exchanger is an evaporator or a superheater.

[0136] When the system is configured to operate in the second mode, it is particularly advantageous that the system comprises the auxiliary vessel and first auxiliary heat exchanger as described here. Other Components / Connections

[0137] In some embodiments, the systems described herein may comprise additional components. The additional components are known to the skilled person. The skilled person knows how to employ / deploy / use the additional components to achieve the desired function.

[0138] For example, the systems described herein may comprise one or more valves, one or more pumps, one or more additional heaters, one or more fans, one or more fluid compressors, one or more condensers, one or more turbines, one or more particulate filters, one or more flow regulators, one or more storage vessels, one or more heat recovery systems, one or more temperature sensors, one or more flow meters, one or more pressure sensors, one or more combustion chambers (furnaces) and / or one or more connecting members (for example tubular members). In some embodiments, the systems described herein may comprise sources of the fluids described herein. For example, the systems described herein may comprise a source of input fluid, a source of first fluid, and / or a source of third fluid.

[0139] In some embodiments, the systems described herein may comprise the first fluid as described herein. In some embodiments, the systems described herein may comprise the second fluid as described herein. In some embodiments, the systems described herein may comprise the third fluid as described herein. In some embodiments, the systems described herein may comprise the fourth fluid as described herein. First Fluid In some embodiments, the first fluid is a fluid from an industrial process. In some embodiments, the first fluid is a waste fluid or by-product from an industrial process.

[0140] In some embodiments, the first fluid is a fluid from a process that generates C02. For example, the process may be a power generation process (such as process for converting fossil fuels into electrical energy), a cement manufacturing process, petrochemical processing process, a steel manufacturing process, or a metal processing process. The first fluid comprises C02. In some embodiments, the first fluid comprises from about o.i vol% to about too vol%, about 99.9 vol%, about 99 vol%, about 95 vol%, about 90 vol%, about 80 vol%, about 70 vol%, about 60 vol%, about 50 vol%, about 40 vol%, about 30 vol%, about 20 vol%, about 10 vol%, or about 5 vol% of C02. For example, the first fluid comprises from about 0.1 vol% to about 20 vol%, about 10 vol%, or about 5 vol% of C02.

[0141] In some embodiments, the first fluid comprises from about 0.1 vol%, about 1 vol%, about 2 vol%, about 5 vol%, about 10 vol%, about 20 vol%, about 30 vol%, about 40 vol%, about 50 vol%, about 60 vol%, about 70 vol%, about 80 vol%, about 90 vol%, or about 95 vol% to about too vol% of C02.

[0142] In some embodiments, the first fluid comprises C02and at least one other fluid. In some embodiments, the first fluid comprises N2, H2, CO, 02, water or mixtures thereof. For example, the first fluid comprises CO, water and H2.

[0143] In some embodiments, the first fluid comprises less than 1 vol. % particulates. As used herein, particulates refer to particulate such as dust, smoke, soot or mixtures thereof.

[0144] Second Fluid

[0145] In some embodiments, the concentration of C02in the second fluid is from about 1% to about 100% less than in the first fluid.

[0146] For example, the concentration of C02in the second fluid is from about 1% to about 100%, about 99%, about 95%, about 90%, about 85%, about 80%, about 75%, about 70%, about 65%, about 60%, about 55%, about 50%, about 40%, about 30%, about 20%, about 10%, or about 5% less than in the first fluid.

[0147] For example, the concentration of C02in the second fluid is from about 1%, about 5%, about 10%, about 20%, about 30%, about 40%, about 50%, about 55%, about 60%, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99% to about 100% less than in the first fluid.

[0148] In some embodiments, the second fluid comprises or consists of N2, H2, CO, 02, water or mixtures thereof. For example, the second fluid comprises or consists of CO, water and H2.

[0149] In some embodiments, the second fluid comprises or consists of C02and at least one other fluid. In some embodiments, the second fluid comprises or consists of N2, H2, CO, 02, water or mixtures thereof. For example, the second fluid comprises or consists of CO, water and H2.

[0150] In some embodiments, the second fluid comprises less than 1 vol. % particulates. As used herein, particulates refer to particulate such as dust, smoke, soot or mixtures thereof.

[0151] Third Fluid

[0152] In some embodiments, the third fluid comprises a fluid selected from the group consisting of water, 02, N2, H2, CO, C02, hydrocarbons (such as CH4) and mixtures thereof. In some embodiments, the third fluid comprises C02, optionally wherein the concentration of the C02in the third fluid is greater than about 99 vol.%. Preferably, the third fluid comprises C02or water. Preferably, the third fluid consists of C02or water.

[0153] In some embodiments, the third fluid comprises or consists of C02. For example, when the system is configured to operate in the first mode, the third fluid comprises or consists of C02. In some embodiments, the third fluid comprises or consists of water. For example, when the system is configured to operate in the second mode, the third fluid comprises or consists of water. Fourth Fluid

[0154] The fourth fluid may be the same or different to the third fluid. For example, if the third fluid comprises C02and at least one other fluid, the concentration of C02in the fourth fluid may be greater than the concentration of C02in the third fluid. For example, if the third fluid consists of C02, the concentration of C02in the fourth fluid may be the same as the concentration of C02in the third fluid.

[0155] System In a second aspect, the invention relates to a system comprising a first reaction vessel, an auxiliary vessel and a first auxiliary heat exchanger, wherein:

[0156] (i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; (ii) the auxiliary vessel is configured to output the first fluid; and

[0157] (iii) the first auxiliary heat exchanger is configured to transfer thermal energy between the first fluid and the second fluid.

[0158] In some embodiments, the auxiliary vessel is configured to accept an input fluid and convert the input fluid into the first fluid.

[0159] In some embodiments, the auxiliaiy vessel is a combustion vessel.

[0160] The system of the second aspect may comprise any one or more of the components or fluids described herein in relation to the first aspect or any other aspect or embodiment described herein. Each of the components or fluids of the second aspect may individually be the same as described herein in relation to any other aspect or embodiment described herein. Figure 8 shows a system comprising a first reaction vessel (1), a first auxiliary heat exchanger (9), and an auxiliary vessel (11). In figure 8, there is shown a first fluid (4), a second fluid (5), and an input fluid (10). Figure 9 shows a system comprising a first reaction vessel, a heat transfer component, a first auxiliary heat exchanger and a third auxiliary heat exchanger. In figure 9, there is shown an input fluid (1, 2, 3, 4), a first fluid (5, 6), a second fluid (8, 9, 10, 11), a third fluid (12, 13, 14, 15, 16). Various other optional components as described herein are also shown.

[0161] Methods

[0162] In a third aspect, the invention relates to a method, the method comprising the steps of: converting a first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; transferring thermal energy between the first reaction vessel and a third fluid in a heat transfer component; and providing the third fluid to a second reaction vessel.

[0163] Each of the first fluid, second fluid, third fluid, first reaction vessel, second reaction vessel, and heat transfer component may individually be the same as described herein in relation to any other embodiment described herein. In particular, each of the first fluid, second fluid, third fluid, first reaction vessel, second reaction vessel, and heat transfer component may individually be the same as described herein in relation to the first aspect, second aspect first mode and / or second mode.

[0164] The method may also comprise one or more of the following steps:

[0165] Providing the first fluid to the first reaction vessel. For example, providing the first fluid to the input of the first reaction vessel. In some embodiments, the method comprises the step of directing the first fluid to the first reaction vessel.

[0166] Providing the first fluid to the first reaction vessel at a temperature of between about 300 °C and about 700 °C.

[0167] Providing the first fluid to the first reaction vessel at a pressure of between about 1 xio5Pa and about 25 xio5Pa. Providing the first fluid to the first reaction vessel at a temperature of between about 300 °C and about 700 °C and at a pressure of between about 1 xio5Pa and about 25 xio5Pa. Converting a metal oxide (or a combination of metal oxides) into a metal carbonate (or a combination of corresponding metal carbonates) in the first reaction vessel. For example, converting the metal oxide (e.g. CaO) into a metal carbonate (e.g. CaCO3) in the first reaction vessel. Preferably, converting calcium oxide into calcium carbonate in the first reaction vessel.

[0168] Providing the third fluid to the second reaction vessel. For example, providing the third fluid to the input of the second reaction vessel. In some embodiments, the method comprises the step of directing the third fluid to the second reaction vessel.

[0169] Providing the third fluid to the second reaction vessel at a temperature of between 600 °C and about 1200 °C.

[0170] Providing the third fluid to the second reaction vessel at a pressure of between about 1 xio4Pa and about 1 xio5Pa.

[0171] Providing the third fluid to the second reaction vessel at a temperature of between 600 °C and about 1200 °C and at a pressure of between about 1 xio4Pa and about 1 xio5Pa about 1 xio4Pa and about 1 xio5Pa.

[0172] Converting a metal carbonate (or the combination of metal carbonates) into a metal oxide (or a combination of corresponding metal oxides) in the second reaction vessel. Converting the metal carbonate (e.g. CaCO3) into a metal oxide (e.g. CaO) in the second reaction vessel. Preferably, converting calcium carbonate into calcium oxide (and thereby produce C02) in the second reaction vessel.

[0173] Converting the third fluid into a fourth fluid in the second reaction vessel.

[0174] In some preferred embodiments, the method comprises the steps of: Providing the first fluid to the first reaction vessel;

[0175] Converting a metal oxide (or a combination of metal oxides) into a metal carbonate (or a combination of corresponding metal carbonates) in the first reaction vessel;

[0176] Providing the third fluid to the second reaction vessel; and Converting a metal carbonate (or the combination of metal carbonates) into a metal oxide (or a combination of corresponding metal oxides) in the second reaction vessel. The methods described herein may also comprise one or more of the following steps:

[0177] Providing the second fluid to a first turbine; and / or providing the second fluid to a first auxiliary heat exchanger.

[0178] Providing the third fluid to a second auxiliary heat exchanger.

[0179] Providing the fourth fluid to a second auxiliary heat exchanger. Providing the fourth fluid to a third auxiliary heat exchanger.

[0180] In some preferred embodiments, the method comprises the steps of:

[0181] Providing the second fluid to a first turbine; and / or providing the second fluid to a first auxiliary heat exchanger; Providing the third fluid to a second auxiliary heat exchanger;

[0182] Providing the fourth fluid to a second auxiliary heat exchanger; and Providing the fourth fluid to a third auxiliary heat exchanger.

[0183] The methods described herein may also comprise one or more of the following steps: Providing an input fluid to an auxiliary vessel.

[0184] Outputting the first fluid from the auxiliary vessel.

[0185] Storing the fourth fluid in a storage vessel.

[0186] The methods described herein may also comprise one or more of the following steps: Providing the third fluid to a fourth auxiliary heat exchanger.

[0187] Providing the third fluid to a third turbine.

[0188] Providing the second fluid to a fourth auxiliary heat exchanger; and / or a first turbine. In some embodiments, the method is a method of removing C02from a fluid. In some embodiments, the method is a method of storing C02.

[0189] Each of the fourth fluid, input fluid, metal oxide (or a combination of metal oxides), metal carbonate (or a combination of metal carbonates), first turbine, third turbine, first auxiliary heat exchanger, second auxiliary heat exchanger, third auxiliary heat exchanger, fourth auxiliaiy heat exchanger and auxiliary vessel may individually the same as described herein in relation to any other embodiment described herein. In particular, each of the fourth fluid, input fluid, metal oxide (or a combination of metal oxides), metal carbonate (or a combination of metal carbonates), first turbine, third turbine, first auxiliary heat exchanger, second auxiliary heat exchanger, third auxiliary heat exchanger, fourth auxiliary heat exchanger and auxiliary vessel may individually the same as described herein in relation to the first aspect, second aspect first mode and / or second mode.

[0190] In a fourth aspect, the invention relates to a method, the method comprising the steps of: outputting a first fluid from an auxiliary vessel; converting the first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; and transferring thermal energy between the first fluid and the second fluid in a first auxiliary heat exchanger.

[0191] Each of the first fluid, second fluid, auxiliary vessel and first auxiliary heat exchanger may individually the same as described herein in relation to any other embodiment described herein. In particular, each of the first fluid, second fluid, auxiliary vessel and auxiliary heat exchanger may individually the same as described herein in relation to the first aspect, second aspect first mode and / or second mode.

[0192] The method may also comprise one or more of the following steps: Providing the first fluid to the first reaction vessel. For example, providing the first fluid to the input of the first reaction vessel. In some embodiments, the method comprises the step of directing the first fluid to the first reaction vessel.

[0193] Providing the first fluid to the first reaction vessel at a temperature of between about 300 °C and about 700 °C. Providing the first fluid to the first reaction vessel at a pressure of between about 1 xio5Pa and about 25 xio5Pa.

[0194] Providing the first fluid to the first reaction vessel at a temperature of between about 300 °C and about 700 °C and at a pressure of between about 1 xio5Pa and about 25 xio5Pa. Providing the second fluid to the first auxiliary heat exchanger. Converting a metal oxide (or a combination of metal oxides) into a metal carbonate (or a combination of corresponding metal carbonates) in the first reaction vessel. For example, converting the metal oxide (e.g. CaO) into a metal carbonate (e.g. CaCO3) in the first reaction vessel. Preferably, converting calcium oxide into calcium carbonate in the first reaction vessel.

[0195] In some preferred embodiments, the method comprises the steps of:

[0196] Providing the first fluid to the first reaction vessel;

[0197] Converting a metal oxide (or a combination of metal oxides) into a metal carbonate (or a combination of corresponding metal carbonates) in the first reaction vessel; and

[0198] Providing the second fluid to the first auxiliary heat exchanger.

[0199] The methods described herein may also comprise one or more of the following steps: Providing an input fluid to the auxiliary vessel.

[0200] Providing the second fluid to a first turbine.

[0201] The methods described herein may also comprise one or more of the following steps: Providing the third fluid to a fourth auxiliary heat exchanger. Providing the third fluid to a third turbine.

[0202] Providing the second fluid to a fourth auxiliary heat exchanger; and / or a first turbine.

[0203] In some preferred embodiments, the method comprises the steps of: Providing the third fluid to a fourth auxiliary heat exchanger;

[0204] Providing the third fluid to a third turbine; and

[0205] Providing the second fluid to the fourth auxiliary heat exchanger; and / or a first turbine. In some embodiments, the method is a method of removing C02from a fluid. In some embodiments, the method is a method of storing C02.

[0206] Each of the input fluid, metal oxide (or a combination of metal oxides), metal carbonate (or a combination of metal carbonates), first turbine, third turbine, first auxiliary heat exchanger, fourth auxiliary heat exchanger and auxiliary vessel may individually the same as described herein in relation to any other embodiment described herein. In particular, each of the input fluid, metal oxide (or a combination of metal oxides), metal carbonate (or a combination of metal carbonates), first turbine, third turbine, first auxiliary heat exchanger, fourth auxiliary heat exchanger and auxiliary vessel may individually the same as described herein in relation to the first aspect, second aspect, third aspect, first mode and / or second mode.

[0207] In a fifth aspect, the invention relates to a use of system described herein in relation to the first aspect. For example, the invention relates to a use of system described herein in relation to the first aspect for producing C02. For example, the invention relates to a use of system described herein in relation to the first aspect for removing C02from a first fluid / input fluid.

[0208] In a sixth aspect, the invention relates to a use of system described herein in relation to the second aspect. For example, the invention relates to a use of system described herein in relation to the first aspect for producing electricity.

[0209] For example, the invention relates to a use of system described herein in relation to the first aspect for producing electricity and removing C02from a first fluid / input fluid. Definitions

[0210] Any fluid described herein may be a gas or a liquid. As such, the term fluid refers to a gas, a liquid, or a combination of a gas and a liquid. Whether a specific fluid component is a gas or a liquid will depend on its temperature and / or pressure. In some embodiments, the fluid described herein is a liquid. Preferably, in some embodiments, the fluid described herein is a gas.

[0211] The term “water” refers to fluid water. That is, the water described herein may be liquid water or gaseous water (sometimes referred to as steam or water vapour). In some embodiments, the water described herein is liquid water. Preferably, the water described herein is gaseous water.

[0212] The fluids described herein may comprise components such as C02, water, and / or other fluids. The skilled person is aware of how to measure the concentration of such components in a fluid. The term vol% means volume %. Unless otherwise stated, the term vol% refers to the volume % of a specific component relative to the total volume of the composition that the specific component is comprised in. When a system or method is said to include a “second” component, it should be understood that the term “second” is used to identify the “second” component. It is not intended to mean that the system or method must comprise a “first” component in addition to the “second” component. This applies equally for use of the terms first, second, third, and fourth.

[0213] The materials described herein are described as being between inputs and outputs of vessels. In such embodiments, the materials may be positioned in any way such that the relevant fluid passes across and / or through the material when moving from the input towards the output. The materials may be positioned spatially in any way to achieve this purpose.

[0214] As used herein, the term “A is coupled to B” means that A is in fluid connection with B. As used herein, the term “A is between B and C” means that A is between B and C and is in fluid connection with B and C.

[0215] When component A is described as being “coupled” to component B, it means that A is suitable for and is coupled to B. That is, A has features that make it suitable to be coupled to B, and B has features that make it suitable to be coupled to A. The term “in fluid connection with” means that there is a path that a fluid can flow between specific components. The skilled person understands how each component described herein can be made in fluid connection with eveiy other component described herein. In some embodiments, when a first component is not in fluid connection with a second component, it means that the first component is configured such that it is not in fluid connection with the second component when one or more of the first component or a further component are in use. For example, the heat transfer component may be configured such that when the second reaction vessel is in use, it is not in fluid connection with the first reaction vessel. Components described herein may be coupled to other components described herein. For example, the components may be coupled directly to other components. In such embodiments, the relevant components may be joined directly to each other so that they are in fluid connection with each other. In some embodiments, the relevant components may be coupled to each other by a tubular member. The term tubular member includes pipes, conduits, tubing, hoses or any other member that provides the function of allowing a fluid to move within its core. The cross section of the tubular member may be circular, substantially circular, square, rectangular, or any other cross section able to provide the required function. The vessels described herein may be reaction vessels. That is, the vessels described herein may be configured to allow a reaction to proceed within them. The features of such vessels depend on the kind of reaction that occurs within and will be known to the skilled person. Examples, of reaction vessels include fixed bed reactors (such as a packed bed reactors) or fluidised bed reactors.

Claims

Claims1. A system comprising a first reaction vessel, a second reaction vessel and a heat transfer component, wherein:(i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; (ii) the heat transfer component is configured to transfer thermal energy between the first reaction vessel and a third fluid; and(iii) the second reaction vessel is configured to accept the third fluid from the heat transfer component.

2. The system according to claim 1, wherein the heat transfer component is not in fluid connection with the first reaction vessel and / or wherein the second reaction vessel is not in fluid connection with the first reaction vessel.

3. The system according to claim 1 or 2, wherein the heat transfer component comprises at least one surface which is configured to transfer thermal energy between the interior of the first reaction vessel and the third fluid.

4. The system according to any one of claims 1 to 3, wherein the first fluid comprises C02and at least one other fluid.

5. The system according to any one of claims 1 to 4, wherein the concentration of C02in the first fluid is from about 0.01 vol% to about 99.9 vol %.

6. The system according to any one of claims 1 to 5, wherein the concentration ofC02in the second fluid is from about 1% to about 100% less than in the first fluid.

7. The system according to any one of claims 1 to 6, wherein the third fluid comprises a fluid selected from the group consisting of water, 02, N2, H2, CO, C02, hydrocarbons (such as CH4) and mixtures thereof.

8. The system according to any one of claims 1 to 7, wherein the third fluid comprises C02, optionally wherein the concentration of the C02in the third fluid is greater than about 75 vol.%.

9. The system according to any one of claims 1 to 8, wherein the first reaction vessel is configured to convert calcium oxide into calcium carbonate.

10. The system according to any one of claims 1 to 9, wherein the first reaction vessel comprises a first material, the first material comprising calcium oxide.

11. The system according to any one of claims 1 to 10, wherein the first reaction vessel comprises a first input, a first output and at least one first fluid pathway between the first input and the first output.

12. The system according to any one of claims 1 to 11, wherein the first reaction vessel comprises a packed bed, for example a thermally well mixed packed bed.

13. The system according to any one of claims 1 to 12, wherein the second reaction vessel is configured to convert calcium carbonate into calcium oxide.

14. The system according to any one of claims 1 to 13, wherein the second reaction vessel comprises a second material, the second material comprising calcium carbonate.

15. The system according to any one of claims 1 to 14, wherein the second reaction vessel comprises a second input, a second output and at least one second fluid pathway between the second input and the second output.

16. The system according to any one of claims 1 to 15, wherein the second reaction vessel comprises a packed bed, for example a thermally well mixed packed bed.

17. A system comprising a first reaction vessel, an auxiliary vessel and a first auxiliary heat exchanger, wherein:(i) the first reaction vessel is configured to accept a first fluid and convert the first fluid into a second fluid; wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid;(ii) the auxiliary vessel is configured to output the first fluid; and(iii) the first auxiliary heat exchanger is configured to transfer thermal energy between the first fluid and the second fluid.

18. The system according to claim 17, wherein the auxiliary vessel is configured to accept an input fluid and convert the input fluid into the first fluid.

19. The system according to claim 18 or 19, wherein the auxiliary vessel is a combustion vessel.

20. A method, the method comprising the steps of: converting a first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; transferring thermal energy between the first reaction vessel and a third fluid in a heat transfer component; and providing the third fluid to a second reaction vessel.

21. A method according to claim 17, the method comprising the step of converting calcium oxide into calcium carbonate in the first reaction vessel.

22. A method according to claim 17 or 18, the method comprising the step of converting convert calcium carbonate into calcium oxide in the second reaction vessel.

23. A method according to any one of claims 17 to 19, wherein providing the third fluid to a second reaction vessel comprises providing the third fluid to an input of the second reaction vessel.

24. A method, the method comprising the steps of: outputting a first fluid from an auxiliary vessel; converting the first fluid into a second fluid in a first reaction vessel, wherein the concentration of C02in the second fluid is less than the concentration of C02in the first fluid; andtransferring thermal energy between the first fluid and the second fluid in a first auxiliary heat exchanger.