PROCESS FOR CARBON DIOXIDE SEPARATION FROM EXHAUST GASES

Description

[0001] The present invention relates to a process for carbon dioxide separation from exhaust gases with internal recovery of the reaction enthalpy.

[0002] To prevent climate change, it is necessary to isolate or reuse the carbon dioxide gas produced by combustion. A wide variety of processes and devices are described in the state of the art for this purpose.

[0003] Carbon dioxide can be separated from exhaust gases by passing them over lime particles (CaO) (calcium looping). The carbon dioxide then reacts according to the process CaO+CO2 -> CaCO3 to form limestone (CaCO3). The CO2 must be expelled from the formed limestone according to the process CaCO3 -> CaO+CO2. This is ensured in current processes by burning a fossil fuel with pure oxygen. Pure oxygen is necessary, as otherwise the CO2 would be recontaminated with air. Combustion with pure oxygen is always energy-intensive. In addition, additional carbon dioxide is produced.

[0004] For example, EP 2 644 256 A1 describes a process and apparatus for efficient carbon dioxide separation. Calcination and carbonation are carried out in different plant sections, with the solids contained in the respective plant sections being reciprocally transferred. WO 2005 / 046862 A1 further describes a process for reactivating limestone absorption media with carbon dioxide. WO 2005 / 046863 A1 further describes a pretreatment of limestone absorption media by hydration. The prior art processes have significant disadvantages, as they are very energy-intensive. Furthermore, the number of regeneration cycles for the limestone is relatively small.

[0005] Furthermore, EP 2 072 111 A2 describes a process for carbon dioxide separation by means of a cyclic chemical reaction with partial pressure swing. The process comprises the reaction of the reactive gas with a bed of reactive solid in an exothermic reaction to produce a second solid and a product gas from which the reactive gas is depleted. WO 00 / 76629 A1 discloses a chemical reactor with pressure swing adsorption. A chemical reaction is carried out with separation of product(s) and reactant(s) by pressure swing adsorption (PSA), using an apparatus having a plurality of adsorbers that interact with first and second valve assemblies in a PSA module. The PSA cycle is characterized by several intermediate pressure levels between higher and lower values of the PSA cycle. Gas streams enter or leave the PSA module at the intermediate pressure levels as well as at the higher and lower pressure levels.from it, entering from the compressor stage(s) and exiting the exhaust or expander stages, respectively, under substantially uniform flow and pressure conditions. Furthermore, US 2003 / 0150163 A1 describes a process for reforming fuels, comprising the step of feeding carbonaceous fuel and steam to a reactor filled with a catalyst for reforming fuels and a CO2 absorbent, and discharging CO2, and adjusting the absorbent to an absorption temperature, whereby the carbonaceous fuel is converted into reformed fuel. FR 2 973 807 A1 describes an agglomerate suitable for a thermocycling process with a short cycle time, comprising a first phase change material and a component having a density with a specific value and forming a core of the agglomerate.

[0006] The object of the present invention is therefore to provide a process which overcomes the disadvantages of the prior art and enables energy-efficient separation of carbon dioxide from combustion products.

[0007] The object is achieved by providing a process which comprises at least one solid reactor according to the main claim.

[0008] A solid-state reactor for storing and releasing carbon dioxide is described, comprising a gas-tight or fluid-tight housing which has an interior space, at least one inlet for feeding in fluids, in particular carbon dioxide-containing exhaust gases, and at least one outlet for feeding out fluids, in particular carbon dioxide-depleted gases, wherein the interior space of the housing is filled with at least two different solids, wherein one solid is provided for storing thermal energy and the other solid is provided for the reversible storage and release of carbon dioxide.

[0009] A solid-state reactor is described, wherein the housing further comprises components which are designed for introducing or discharging the solids.

[0010] A solid-state reactor is described, wherein shut-off devices are arranged in the region of the inlet and in the region of the outlet of gases or fluids, which shut-off devices are designed to change the pressure in the interior of the solid-state reactor and / or to introduce gases or fluids into the solid-state reactor and / or to discharge gases or fluids escaping from the solid-state reactor.

[0011] A solid-state reactor is described, wherein the solids for storing and releasing carbon dioxide are selected from calcium oxide and calcium oxide-containing materials, selected from limestone and dolomite or dolomite stones. According to the invention, the solids to be used may be pre-calcined to enable the absorption of the carbon dioxide.

[0012] A solid-state reactor is described, wherein the solids for storing thermal energy are selected from inert mineral materials such as quartz, granite, silicon dioxide, igneous rocks, silicon carbides, zirconium oxides, metallic phase change materials, cast iron, grey cast iron or mixtures of the aforementioned materials.

[0013] A solid-state reactor is described, wherein the at least two different solids are in the form of jacketed solids, consisting of an outer shell and an inner core, wherein the inner core is provided for storing thermal energy and the outer shell is provided for reversibly storing and releasing carbon dioxide.

[0014] It is particularly preferred that the double salts are selected from dolomite, dolomite stone, dolomitic rocks, dolomite or dolomite-containing rocks or mixtures thereof.

[0015] A solid-state reactor is described, wherein the at least two different solids are in the form of double salts, wherein one of the salts of the double salt is suitable for storing thermal energy and the other salt of the double salt is suitable for reversibly storing and releasing carbon dioxide.

[0016] It is particularly preferred that the double salts are selected from dolomite, dolomite stone, dolomitic rocks, dolomite or dolomite-containing rocks or mixtures thereof.

[0017] A solid-state reactor is described, wherein the at least two different solids have a particle size in the cm range.

[0018] A solid-state reactor is also preferred, wherein the solids introduced into the solid-state reactor form a flowable fixed bed.

[0019] A system for storing and releasing carbon dioxide is described, comprising at least one solid-state reactor, at least one compressor for compressing the carbon dioxide-containing fluid or exhaust gas, which is introduced through the inlet of the solid-state reactor, wherein the compressor is designed such that it adiabatically expands the carbon dioxide-depleted gas or fluid, which is discharged from the reactor by means of the outlet of the solid-state reactor, and at least one countercurrent recuperator, which is designed for the heat exchange of the compressed fluid or exhaust gas, which contains carbon dioxide, and the carbon dioxide-depleted gas or fluid.

[0020] A system is described wherein at least one supply device for heated fluids is arranged in the region of the inlet in order to further heat the carbon dioxide-containing fluid after heating in the countercurrent recuperator and before entering the inlet of the solid-state reactor.

[0021] Furthermore, a system is described in which one or more compressors are provided which compress and burn air and / or natural gas and / or heating oil and inject the combustion gas via the supply device.

[0022] A system is also described wherein the supply device is electrically heatable and the supplied fluid is hydrogen gas.

[0023] A system is described in which further pipes and shut-off devices are provided which make the solid reactor detachable from the system and which fluidically connect the solid reactor to the recuperator via the outlet for discharging gases or fluids.

[0024] Furthermore, a system is described, wherein the system has at least two solid reactors, wherein the solid reactors are connected to the components of the system in a gas-technical or fluid-technical manner such that the respective solid reactors are provided independently of one another for the storage or release of carbon dioxide.

[0025] The present invention relates to a process for the storage and release of carbon dioxide, wherein a) providing at least one solid-state reactor for storing and releasing carbon dioxide, wherein the at least one solid-state reactor comprises a fluid-tight housing having an interior space, at least one inlet for feeding fluids, and at least one outlet for discharging fluids, wherein the interior space of the housing is filled with at least two different solids, wherein one solid is provided for storing thermal energy and the other solid is provided for the reversible storage and release of carbon dioxide; b) introducing a carbon dioxide-containing exhaust gas into the solid-state reactor, wherein the carbon dioxide-containing exhaust gas is compressed such that the partial pressure of the carbon dioxide in the carbon dioxide-containing exhaust gas is 1 to 2 bar, wherein the carbon dioxide from the carbon dioxide-containing exhaust gas is stored in the solid for the reversible storage and release of carbon dioxide,c) the introduction of the exhaust gas containing carbon dioxide is stopped when the temperature inside the solid reactor is between 910 and 960 °C, d) the solid reactor is depressurised to a pressure of 0.1 to 0.5 bar after the internal temperature of 910 to 960 °C has been reached, whereby the carbon dioxide stored in the solid for the reversible storage and release of carbon dioxide is released from this solid, e) the carbon dioxide released from the solid reactor by the depressurisation for the reversible storage and release of carbon dioxide is discharged until the temperature inside the solid reactor is between 810 and 850 °C, f) the discharged carbon dioxide is compressed to normal pressure and stored.

[0026] It is particularly preferred that the partial pressure of the carbon dioxide in step b) is above 1 bar.

[0027] It is furthermore particularly preferred that the pressure inside the solid reactor in step d) is less than 0.4 bar, particularly preferably less than 0.2 bar.

[0028] It is also particularly preferred that the temperature inside the solid reactor in step c) is more than 910 °C.

[0029] It is further particularly preferred that the temperature inside the solid reactor in step e) is below 850 °C.

[0030] A process is also preferred in which the storage of the carbon dioxide and the subsequent release takes place in the same temperature range and in the same reactor.

[0031] A method is also preferred in which the enthalpy released during carbon dioxide absorption or storage causes the temperature to rise and is thereby stored in the material which remains inert.

[0032] A process is also preferred in which the stored heat is reused after the pressure reduction to release the carbon dioxide.

[0033] The present invention is explained in more detail with the accompanying drawings. It shows: Fig. 1 an equilibrium curve p eq for calcination and carbonization with reaction range at ambient pressure; Fig. 2 an equilibrium curve p eq for calcination and carbonization with reaction areas at overpressure of the exhaust gas and underpressure of the carbon dioxide gas; Fig. 3 a first embodiment of a solid-state reactor during carbonization with basic temperature and partial pressure profiles; Fig. 4 a first embodiment of a solid reactor during calcination; Fig. 5 a second embodiment of a solid reactor during carbonization with basic temperature and partial pressure profiles Fig. 6a second embodiment of a solid reactor during calcination with basic temperature and partial pressure profiles Fig. 7 a first embodiment of a plant diagram for carbonization and calcination; Fig. 8 a second embodiment of a plant diagram for carbonation and calcination; and Fig. 9 a partial view of a plant diagram showing an arrangement of solid-fuel reactors for parallel operation.

[0034] The carbon dioxide reacts according to the chemical equation CaO+CO 2 -> CaCO 3 to form limestone (CaCO 3 ). Figure 1The equilibrium curve of this reaction is shown. For this so-called carbonation reaction, the partial pressure of CO2 must be above the equilibrium pressure. For example, if the partial pressure in the exhaust gas is 0.1 bar, i.e., 10 vol.% CO2, the temperature of the lime (CaO) must be below 760°C. The carbonation reaction is exothermic. The released heat can therefore only be used in other processes that take place significantly below 760°C. The use of the heat is therefore limited. The heat can, for example, be used to generate steam and then convert it into electricity using a turbine.

[0035] The CO2 must be expelled from the formed limestone according to the equation CaCO3 -> CaO+CO2. For this so-called calcination, the equilibrium pressure must be higher than the partial pressure. If pure CO2 is to be produced at 1 bar (ambient pressure), the temperature of the particles must be above 910°C, as this is the temperature for the equilibrium pressure of 1 bar. Calcination is endothermic, requiring heat, specifically at a temperature level above 910°C.

[0036] With the inventive process and the solid-state reactor, carbon dioxide can be separated from combustion gases using significantly less energy than with existing processes. Carbon dioxide separation from exhaust gases during energy generation using fossil fuels and subsequent underground storage or use in other processes is considered worldwide to be an essential component in minimizing global warming. Due to the very low energy requirements of CO2 separation, the reactor is suitable for the worldwide implementation of CO2 sequestration. The reactor can, in principle, be installed downstream of all power plants and industrial facilities such as cement and lime works (which account for 5% of CO2 emissions worldwide).

[0037] The aim of the process according to the invention is to reuse the reaction enthalpy released during carbonization directly in a reactor for endothermic calcination. Therefore, the reactor contains appropriate materials to store the heat. The exothermic and endothermic reaction enthalpies are equal. This eliminates both the cumbersome utilization of waste heat from carbonization and the costly energy generation for calcination. Since, according to the second law of thermodynamics, heat can only flow from higher to lower temperatures, carbonization (CaO+CO 2 -> CaCO 3 ) must take place at a higher temperature than endothermic calcination (CaCO 3 -> CaO+CO 2 ).

[0038] The objects of the present invention have the following features and advantages: Modification of existing systems, such as with oxyfuel, is not necessary. The solid-state reactor contains dolomite and / or limestone or lime particles and inert inorganic material, e.g., gravel particles, which can store heat. Phase change materials of the known type are also suitable. Dolomite has the advantage that the internal magnesite content already serves as a storage medium. To absorb the carbon dioxide according to CaO+CO2 -> CaCO3 (carbonization), the exhaust gas is passed through the fixed bed under positive pressure. This raises the temperature level of this carbonization reaction. The subsequent calcination (CaCO3 -> CaO+CO2) is carried out under negative pressure. This lowers the temperature level of this calcination reaction. The CO2 partial pressure of the exhaust gas during carbonization must be higher than that of the pure CO2 gas during calcination, as in Figure 2This means that exothermic carbonization occurs at a higher temperature than endothermic calcination. The heat released during carbonization is stored in the inert material and can subsequently be used for calcination.

[0039] In a particularly preferred embodiment of the present invention, lumpy limestone or dolomitic stones in the cm range are present in the reactor. The area near the surface absorbs the carbon dioxide (in Figure 5 (indicated by a dark ring-shaped area for the stones depicted as spherical). The reaction enthalpy released during absorption is conducted into the interior of the stones, thereby heating them. The reaction enthalpy is thus stored as latent enthalpy.

[0040] The size of the stones is chosen so that the mass of the unreacted, inert core is sufficient to store the reaction enthalpy. Only a region close to the surface can absorb carbon dioxide, because the resulting increase in volume causes the CaCO3 shell to become dense, preventing further carbon dioxide from diffusing into the core.

[0041] Dolomitic stones are preferred. Firstly, the inert MgO content serves as a storage mass, and secondly, the MgO content prevents sintering of the CaO content, allowing multiple cycles to be carried out without the lime experiencing what is known as dead burning. Preliminary tests conducted over 500 cycles without any decrease in absorption capacity. In previous processes using particles in the µm range, the original absorption capacity had dropped to approximately 10% after 10 cycles.

[0042] After the pressure reduction for calcination, the endothermic reaction enthalpy is then covered by the stored, latent enthalpy and the stones cool down again, as in Figure 6 is shown.

[0043] According to the invention, it is particularly advantageous for the stones used in the reactor to have a size in the cm range. This ensures that when the stones are loaded with carbon dioxide, which increases their volume, the passage of gases or fluids is not disrupted. The size of the stones also allows for an increase in the number of cycles, as sintering is avoided. Stone sizes of 0.5 cm to 10 cm are preferred, and 2 cm to 5 cm are most preferred.

[0044] The following embodiments explain the invention in more detail without limiting the scope of the invention.

[0045] The inventive basic idea of the process according to the invention is that the exhaust gas is compressed for carbonization and that the subsequent calcination is carried out under negative pressure. The pressure ratio must be adjusted so that the CO 2 partial pressure during carbonization is higher than the CO 2 pressure during calcination. This principle is implemented with the Figure 2explained. In this example, it is assumed that the exhaust gas is compressed so that the CO 2 partial pressure is 1 bar. An exhaust gas with 10 vol.% CO 2 would therefore have to be compressed to 10 bar. The calcination is carried out here at 0.2 bar absolute pressure. The corresponding equilibrium temperatures are 910 °C and 810 °C, respectively. The carbonization can now be carried out in the temperature range from 810 °C to 910 °C, since in this range the CO 2 partial pressure is always greater than the equilibrium pressure. Calcination can also be carried out in the same temperature range, since the condition for this, equilibrium pressure greater than CO 2 pressure, is met (see Figure 2 ).

[0046] A solid reactor is used to transfer the heat from carbonization to calcination. This reactor consists of a Figure 3from lime particles and inert solid particles, such as quartz particles. The inert particles serve to store the heat generated during carbonation. Depending on the temperature difference between carbonation and calcination, the volume ratio between the inert particles and the lime particles is between 10 and 15. The smaller the temperature difference, the more inert particles are required for storage. Figure 3In the example shown, it is assumed that the fixed bed has a temperature of 850 °C after calcination. If an exhaust gas with, for example, 1 bar CO2 partial pressure flows in at 910 °C, the gas cools down. The partial pressure is then higher than the equilibrium pressure, meaning the CO2 can be separated from the lime particles. The heat of reaction heats the fixed bed up to 910 °C over time. The partial pressure and temperature profiles that result over time are shown schematically. Temperatures higher than 910 °C are not possible, as the reaction then stops. The maximum temperature of the reactor can be set using the CO2 partial pressure. The higher this is, the higher the maximum possible temperature.

[0047] Once the reactor is charged to 910 °C, the exhaust gas stream is directed into another, discharged reactor (see Figure 4The pressure in the charged reactor is then reduced to 0.4 bar. The equilibrium pressure is now higher than the partial pressure, so the reactive particles calcine. The process is analogous to the evaporation of water from a moist, porous body whose temperature is higher than the saturated steam temperature of the surrounding water vapor. During evaporation, the porous body cools down to generate the enthalpy of vaporization. Analogously, the fixed bed cools down to the equilibrium temperature of 850 °C to generate the enthalpy of reaction. The resulting CO2 stream transfers the heat between the inert and the reactive particles. If the CO2 stream is not sufficient for heat transfer, CO2 can be recycled if necessary to increase the flow in the reactor. After discharging, the reactor is recharged. Thus, a regenerative enthalpy exchange takes place.

[0048] In the Figures 5 and 6A further and particularly preferred embodiment of the reactor according to the invention is now presented. A solid reactor is used to transfer the heat from carbonization to calcination. This reactor consists of Figure 5 lumpy limestones and dolomitic rocks. The inert core serves to store the heat generated during carbonation. Depending on the temperature difference between carbonation and calcination, the volume ratio between the inert core and the reacting shell is 5 to 10. In the case of the carbonate shown in the figure Figure 5In the example shown, it is assumed that the fixed bed has a temperature of 810 °C after calcination. If an exhaust gas with, for example, 1 bar CO2 partial pressure flows in at 910 °C, the gas cools down. The partial pressure is then higher than the equilibrium pressure, and the CO2 can therefore be separated out. The heat of reaction heats the fixed bed up to 910 °C over time. The partial pressure and temperature profiles that result over time are shown schematically. Temperatures higher than 910 °C are not possible, as the reaction then stops. The maximum temperature of the reactor can be set via the CO2 partial pressure. The higher this is, the higher the maximum possible temperature.

[0049] Once the reactor is charged to 910 °C, the exhaust gas stream is directed into another, discharged reactor, as described in the Figure 6The pressure in the charged reactor is then reduced to, for example, 0.2 bar. The equilibrium pressure is now higher than the partial pressure, so the reactive stones calcine. The process is analogous to the evaporation of water from a moist, porous body whose temperature is higher than the saturated steam temperature of the surrounding water vapor. During evaporation, the porous body cools to generate the enthalpy of vaporization. Analogously, the fixed bed cools to the equilibrium temperature of 810 °C to generate the enthalpy of reaction. After discharging, the reactor is recharged. Thus, a regenerative enthalpy exchange takes place.

[0050] In the Figure 7A plant diagram 100 for the overall process is shown. For a better understanding of the process, the temperatures specified in this exemplary embodiment refer to the example in which carbonization is carried out at a CO2 partial pressure of 1 bar and calcination under pure CO2 at 0.4 bar. All temperatures apply to an adiabatic, reversible ideal process. The exhaust gas 13 has a temperature of 20 °C, an ambient pressure of 1 bar and 10% CO2. A pressure of 10 bar and 910 °C are then required for carbonization. The exhaust gas 13 is therefore first compressed to 10 bar, during which time the temperature rises to 293 °C. The clean gas emerges from the carbonizer 1a at 850 °C. This gas heats the exhaust gas to approximately 800 °C in a countercurrent recuperator 6. Natural gas 9 is required for the residual heating to 910 °C. This natural gas stream 9 represents the main energy requirement of the overall process.The energy released during the expansion of the clean gas is used for compression. This requires only a relatively small electrical current to compress the exhaust gas. The carbon dioxide stream emerges from the calcination process at 850 °C. This heat is used to generate electricity, e.g., by ORC 18. This current is sufficient to compress the carbon dioxide stream to ambient pressure.

[0051] The Figure 7The system according to the invention shown is described in more detail below. The fluid to be freed of carbon dioxide, namely the exhaust gas, is introduced into the system via the exhaust gas inlet 13. By means of the compressor 7, the exhaust gas is compressed to the corresponding partial pressure of the CO 2 and passed through the inlet line 4 through the countercurrent recuperator 6. The exhaust gas heated in this way is introduced into the reactor 1a for carbonation via the inlet 3. In the reactor 1a, the CO 2 is bound as calcium carbonate and the now CO 2-poor exhaust gas is passed back into the countercurrent recuperator 6 via the outlet line 5. The now purified exhaust gas is released via an expansion device 8 under normal pressure via the exhaust gas outlet 14. In order to heat the carbon dioxide-containing exhaust gas 13 to the required reaction temperature of 910 °C, a fuel, e.g.Natural gas is introduced via inlet 9, compressed in compressor 10 to reaction pressure (here 10 bar), and injected into the exhaust gas via feed line 12. The amount of fuel is so small that the oxygen in the exhaust gas is sufficient for combustion. Combustion reduces the oxygen content in the exhaust gas by only about 1% to 1.5%. For stable combustion, air 11 can be compressed by compressor 10 and burned with natural gas 9. The combustion gas is then injected into the exhaust gas 13 via gas supply line 12. Alternatively, for stable combustion, part of the exhaust gas flow can be diverted. The natural gas is injected into this diverted exhaust gas flow. The amount of diverted exhaust gas flow is so large that the temperature rises above 1200°C, at which complete combustion is guaranteed.

[0052] If the solid-state reactor 1 is now in state 1b of CO2 discharge, the CO2 bound in the calcium carbonate is discharged from the solid-state reactor via outlet 2 as it cools down. The CO2 is cooled in the low-pressure heat exchanger 15, then brought to ambient pressure in the compressor 16, and cooled again in the normal-pressure heat exchanger 17. The heat removed in the heat exchangers 15 and 17 is converted into electricity in the ORC system 18, which could also be a steam turbine. This electricity is used in the system for the compressors. Pure CO2 now escapes through outlet 19 under normal conditions. The energetic coupling of the fluid flows achieves high energy efficiency, so that only a small amount of external energy needs to be introduced into the system to carry out the corresponding reaction processes of carbonization and calcination.

[0053] In the Figure 8A second embodiment of the system according to the invention is shown. Figure 8A plant diagram 100 for the overall process is shown. For a better understanding of the process, the temperatures specified in this exemplary embodiment refer to the example in which carbonization is carried out at a CO2 partial pressure of 1 bar and calcination under pure CO2 at 0.2 bar. All temperatures apply to an adiabatic, reversible ideal process. The exhaust gas 13 has a temperature of 20 °C, an ambient pressure of 1 bar, and 10% CO2. A pressure of 10 bar and 910 °C are then required for carbonization. The exhaust gas 13 is therefore first compressed to 10 bar, during which time the temperature rises to 293 °C. The clean gas emerges from the carbonizer 1a at 810 °C. This gas heats the exhaust gas to approximately 700 °C in a countercurrent recuperator 6.For the final heating to 910 °C, electrical energy can be used via heating elements; hydrogen can be injected and burned if the exhaust gas still contains some oxygen; or a combustion gas can be injected. The latter, however, would generate additional carbon dioxide. This gas stream 9 represents the main energy requirement of the entire process. The energy released when the clean gas is expanded is used for compression. As a result, only a relatively small amount of electrical power is required to compress the exhaust gas. The carbon dioxide stream exits the calcination process at 810 °C. This heat could be used, for example, to generate electricity, e.g., by ORC 18.

[0054] The Figure 8The system according to the invention shown is described in more detail below. The fluid to be freed of carbon dioxide, namely the exhaust gas, is introduced into the system via the exhaust gas inlet 13. By means of the compressor 7, the exhaust gas is compressed to the corresponding partial pressure of the CO 2 and passed through the inlet line 4 through the countercurrent recuperator 6. The exhaust gas thus heated is introduced into the reactor 1a for carbonation via the inlet 3. In the reactor 1a, the CO 2 is bound as calcium carbonate and the now CO 2-poor exhaust gas is passed back into the countercurrent recuperator 6 via the outlet line 5. The now purified exhaust gas is discharged via an expansion device 8 under normal pressure via the exhaust gas outlet 13.In order to heat the carbon dioxide-containing exhaust gas 14 to the required reaction temperature of 910 °C, hydrogen can be injected via lances 21, the gas can flow through electrical heating coils 22 or a hot combustion gas can be injected via lances 12.

[0055] If the solid-state reactor 1 is now in state 1b of CO2 discharge, the CO2 bound in the calcium carbonate is discharged from the solid-state reactor via outlet 2 as the reactor cools down. The CO2 is cooled in the low-pressure heat exchanger 15, then brought to ambient pressure in the compressor 16, and cooled again in the normal-pressure heat exchanger 17. Pure CO2 now escapes through outlet 19 under normal conditions. The energetic coupling of the gas streams achieves high energy efficiency, so that only a small amount of external energy needs to be introduced into the system to carry out the corresponding reaction processes of carbonization and calcination.

[0056] In the Figure 9A partial view of a system according to the invention is shown in a first embodiment. The solid-state reactors 1 are arranged parallel to one another and are each fluidically connected to the inlet 3, the outlet line 5, and the outlet 2, with shut-off devices 20 arranged in such a way as to connect each of the two reactors independently of one another to the lines 3 and 5 for the carbonization process or to the outlet 2 for the calcination process. This makes it possible to operate the respective solid-state reactors 1, which may be in different operating states, separately. This means that one of the fixed-bed reactors is in state 1a of loading with CO2, while the other fixed-bed reactor is in state 1b of discharging the CO2.In other embodiments of the present invention, additional fixed-bed reactors 1 may be provided, each of the reactors being operated in one of the states 1a or 1b (not shown). The invention also provides for the arrangement of additional solid-state reactors, the number of which need not be limited according to the invention. List of reference symbols

[0057] 1 Solid-state reactor 1a Solid-state reactor loaded with CO 2 1b Solid-state reactor unloading CO 2 2 Outlet 3 Inlet 4 Inlet line 5 Outlet line 6 Countercurrent recuperator 7 Exhaust gas compressor 8 Clean gas expansion device 9 Fuel gas supply 10 Compressor 11 Air supply 12 Combustion gas supply 13 Exhaust gas inlet or exhaust gas 14 Exhaust gas outlet (low CO 2) 15 Low-pressure heat exchanger 16 CO 2 compressor 17 Normal-pressure heat exchanger 18 ORC plant for power generation 19 CO 2 outlet 20 Shut-off devices 21 Hydrogen injection 22 Electrical heating 100 System for storing and releasing carbon dioxide

Claims

1. Method for storage and release of carbon dioxide, wherein one a) provides at least one solids reactor for storage and release of carbon dioxide, wherein the at least one solids reactor (1) comprises a fluid-tight housing, which has an interior, at least one inlet (3) for feeding in fluids and at least one outlet (2) for discharging of fluids, wherein the interior of the housing is filled with at least two different solids, wherein the one solid is provided for storage of thermal energy and the other solid is provided for reversible storage and release of carbon dioxide; b) introduces a carbon dioxide-containing exhaust gas into the solids reactor, wherein one compresses the carbon dioxide-containing exhaust gas in such a way that the partial pressure of the carbon dioxide in the carbon dioxide-containing exhaust gas is 1 to 2 bar, wherein the carbon dioxide from the carbon dioxide-containing exhaust gas is stored in the solid for reversible storage and release of the carbon dioxide; c) stops the introduction of the carbon dioxide-containing exhaust gas when the temperature in the interior of the solids reactor is 910 to 960 °C; d) releases the tension of the solids reactor to a pressure of 0.1 to 0.5 bar, after reaching the internal temperature of 910 °C to 960 °C, wherein the carbon dioxide stored in the solid for reversible storage and release of carbon dioxide is released from said solid; e) discharges from the solids reactor the carbon dioxide released again by the tension release from the solid for reversible storage and release of carbon dioxide, namely as long as the temperature in the interior of the solids reactor is 810 to 850 °C; f) compresses the discharged carbon dioxide to normal pressure and stores it.

2. Method according to claim 1, characterized in that the partial pressure of the carbon dioxide in step b) is above 1 bar.

3. Method according to claims 1 or 2, characterized in that the pressure in the interior of the solids reactor in step d) is less than 0.4 bar, particularly preferred less than 0.2 bar.

4. Method according to any of claims 1 to 3, characterized in that the temperature in the interior of the solids reactor in step c) is more than 910 °C.

5. Method according to any of claims 1 to 4, characterized in that the temperature in the interior of the solids reactor in step e) is below 850 °C.

6. Method according to claim 1, characterized in that the storage of the carbon dioxide and the subsequent release takes place in the same temperature range and in the same reactor.

7. Method according to claim 1, characterized in that the enthalpy released during the carbon dioxide absorption or the storage, respectively, causes the temperature increase and is thereby stored in the material that remains inert.

8. Method according to claim 1, characterized in that the stored heat is reused after the pressure reduction for the release of the carbon dioxide.