decarbonization

Abstract

A system (11) is provided comprising a furnace (102), a heat exchanger (104), a gas separator (106) and a first thermochemical reactor (112). The heat exchanger (104) is arranged for receiving and cooling flue gas (121) comprising carbon dioxide and nitrogen from the furnace (102), thereby producing cooled flue gas (122). The gas separator (106) is arranged for receiving the cooled flue gas (122) and separating the cooled flue gas (122) into a nitrogen-rich gas (124) and a carbon dioxide-rich gas (125). The heat exchanger (104) is arranged for heating the nitrogen-rich gas (124) and the carbon dioxide-rich gas (125). The first thermochemical reactor (112) comprises a thermochemical compound. The first thermochemical reactor (112) is configured to receive heated carbon dioxide-rich gas (126) in a first mode of the system (11) and to generate carbon monoxide from carbon dioxide in the heated carbon dioxide-rich gas (126) by oxidation of the thermochemical compound to form a carbon monoxide-rich gas (125).

Description

Technical Field

[0001] This invention relates to systems and methods for reducing carbon emissions in industrial processes, such as in systems that require the generation of heat or carbon dioxide emissions. Background Technology

[0002] Many industrial processes produce carbon dioxide, a greenhouse gas that contributes to anthropogenic climate change. Addressing anthropogenic climate change requires reducing the amount of carbon dioxide emitted into the atmosphere through industrial processes. Many industrial processes require heat, such as steel rolling and forming, forging, heat treatment, and calcination. The heat required for such processes is typically generated by burning hydrocarbons, which produces carbon dioxide. In many cases, utilizing combustion to generate heat may be desirable, as existing systems are based on this heat source. Combustion produces very high heat fluxes coupled into the gas phase, which is difficult to achieve with electric heating. For example, electric arc heating primarily provides heat through radiative flux, while induction heating directly heats the conductive medium via eddy currents. Coupling high heat fluxes from electrical energy into the gas phase can be challenging.

[0003] The desired systems and methods are to reduce carbon dioxide emissions in industrial processes. Summary of the Invention

[0004] According to one aspect of the invention, a system is provided, comprising: a furnace; a heat exchanger arranged to receive and cool flue gas containing carbon dioxide and nitrogen from the furnace to produce cooled flue gas; a gas separator arranged to receive the cooled flue gas and separate the cooled flue gas into nitrogen-rich gas and carbon dioxide-rich gas; wherein the heat exchanger is arranged to heat the nitrogen-rich gas and the carbon dioxide-rich gas; and a first thermochemical reactor containing a thermochemical compound, the first thermochemical reactor being configured to receive the heated carbon dioxide-rich gas in a first mode of the system and to generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through oxidation by the thermochemical compound to form carbon monoxide-rich gas.

[0005] The system may also include a second thermochemical reactor containing the thermochemical compound. The second thermochemical reactor may be configured to receive heated nitrogen-rich gas and generate oxygen through the reduction of the thermochemical compound in the second thermochemical reactor to form oxygen-rich gas.

[0006] The system can operate in a second mode in which the first thermochemical reactor is configured to receive heated nitrogen-rich gas and generate oxygen through the reduction of thermochemical compounds in the first thermochemical reactor to form oxygen-rich gas.

[0007] In the second system mode, the second thermochemical reactor can be configured to receive heated carbon dioxide-rich gas and generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through the oxidation of thermochemical compounds, thereby forming carbon monoxide-rich gas.

[0008] The system can be configured to switch between a first mode and a second mode to maintain the generation of carbon monoxide and oxygen from the first thermochemical reactants and the second thermochemical reactor. Therefore, each thermochemical reactor can operate in a reversible oxidation and reduction cycle depending on its temperature.

[0009] The system can be configured to react oxygen-enriched gas with carbon monoxide-enriched gas to provide heat to the furnace. The reaction between the oxygen-enriched gas and the carbon monoxide-enriched gas can take place in a burner, which can be part of the system.

[0010] The system may include a burner configured to burn carbon monoxide-rich gas to provide heat to the furnace, wherein the burner is located inside or outside the furnace. The burner does not require the use of oxygen generated from the second thermochemical reactor. While it is desirable to use oxygen generated from either the first or second thermochemical reactor (operating in a mode of reducing thermochemical compounds) for combustion, this is not necessary, and atmospheric oxygen can be used alternatively.

[0011] The system may include an additional gas separator configured to produce purified carbon monoxide gas from the carbon monoxide-rich gas. In some embodiments, at least a portion of the carbon monoxide gas may be captured in purified form, for example, for use in other industrial processes that require carbon monoxide.

[0012] The system can be configured to receive flue gas from thermal power plants (such as waste power plants and / or biomass power plants).

[0013] The furnace can be a high-temperature furnace, configured to operate at a temperature of at least 800°C; or a medium-low temperature furnace, configured to operate at a temperature below 800°C.

[0014] The thermochemical compound may include metal oxides, perovskite materials, or double perovskite materials.

[0015] The first thermochemical reactor and optionally the second thermochemical reactor may be configured to receive input electrical energy to heat the thermochemical reactor.

[0016] The system is configured to receive at least 90% of the net input energy in the form of electrical energy (e.g., input to the first thermochemical reactor and the second thermochemical reactor).

[0017] According to the second aspect, an industrial method is provided, comprising: The flue gas is cooled in a heat exchanger to produce cooled flue gas containing carbon dioxide and nitrogen. The cooled flue gas is separated into nitrogen-rich gas and carbon dioxide-rich gas; Use a heat exchanger to heat nitrogen-rich gas and carbon dioxide-rich gas; In the first thermochemical reactor, carbon dioxide in the carbon dioxide-rich gas is converted into carbon monoxide through the oxidation of thermochemical compounds, thus forming a carbon monoxide-rich gas.

[0018] The method of the first aspect can be performed using the system according to the first aspect, including any optional features thereof. The method of the first aspect can be performed using any embodiment described in the detailed embodiments, including any optional features thereof.

[0019] The method may also include generating oxygen by reducing thermochemical compounds in a second thermochemical reactor to form oxygen-enriched gas.

[0020] The method may also include generating oxygen in the first thermochemical reactor by reducing a thermochemical compound in the first thermochemical reactor to form an oxygen-enriched gas.

[0021] In the second system mode, the second thermochemical reactor is configured to receive heated carbon dioxide-rich gas and generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through the oxidation of thermochemical compounds, thereby forming carbon monoxide-rich gas.

[0022] The method may include switching between a first mode and a second mode to maintain the generation of carbon monoxide and oxygen from a first thermochemical reactant and a second thermochemical reactor.

[0023] The method may include generating heat for the furnace by reacting oxygen-rich gas with carbon monoxide-rich gas.

[0024] The method may include burning carbon monoxide-rich gas in a burner to provide heat to the furnace, wherein the burner is located inside or outside the furnace.

[0025] The method may also include generating purified carbon monoxide gas from carbon monoxide-rich gas.

[0026] Flue gas can come from thermal power plants, such as waste power plants and / or biomass power plants.

[0027] The method may include providing heat (from the combustion of carbon monoxide) to the following device: i) A high-temperature furnace operating at a temperature of at least 800°C; or ii) Low-temperature furnaces operating at temperatures below 800°C.

[0028] The thermochemical compound may include metal oxides, perovskite materials, or double perovskite materials.

[0029] The first thermochemical reactor and optionally the second thermochemical reactor can receive renewable input electrical energy to heat the thermochemical reactor.

[0030] The furnace can be used to process (e.g., heat treat) titanium and / or titanium alloys.

[0031] The features of each aspect can be combined, including optional features. Each aspect may also include features derived from any of the exemplary embodiments described herein. Attached Figure Description

[0032] Exemplary embodiments will be described with reference to the accompanying drawings. These embodiments are not intended to be limiting, but are merely exemplary. The scope of the invention should be determined with reference to the appended claims.

[0033] Figure 1 This is a block diagram of a system used to heat a high-temperature furnace and reduce carbon dioxide emissions; Figure 2 This is a block diagram of a system for heating a medium-temperature furnace and reducing carbon dioxide emissions; and Figure 3 This is a block diagram of a system used to capture and convert carbon from thermal power plants to reduce carbon dioxide emissions. Detailed Implementation

[0034] refer to Figure 1 The system 11 is shown, including: furnace 102, heat exchanger 104, gas separator 106, first thermochemical reactor 112 and second thermochemical reactor 114.

[0035] In this embodiment, furnace 102 can be a high-temperature furnace designed to operate at temperatures exceeding 800°C (e.g., or above 900°C). Furnace 102 can be used in any industrial process, such as metal rolling and forming (e.g., steel, aluminum, titanium), forging, heat treatment, and calcination. Furnace 102 includes a burner 103 that receives carbon monoxide-rich gas 128 and oxygen-rich gas 127. The carbon monoxide and oxygen-rich gas burn to release heat within the furnace.

[0036] The result of this combustion process is hot flue gas 121 containing carbon dioxide and relatively low levels of nitrogen (N2) and carbon monoxide. Assuming complete combustion, the carbon monoxide content in hot flue gas 121 will be very low (e.g., less than 400 ppm by volume or less than 100 ppm by volume). If the oxygen-enriched gas 127 is relatively pure oxygen, the amount of nitrogen in hot flue gas 121 may be relatively low (e.g., less than 50% by volume or less than 20% by volume). Hot flue gas 121 may contain at least 50% carbon dioxide, or at least 30% carbon dioxide (by volume). The hot flue gas may contain trace amounts of hydrogen and water (e.g., less than 5% or less than 1% by volume, or less than 0.1% by volume).

[0037] Heat exchanger 104 receives hot flue gas 121 and extracts heat from it to produce cooled flue gas 122. The temperature of the cooled flue gas 122 can be below 400°C (or below 250°C), which makes gas separation easier. Heat exchanger 104 is arranged to provide the heat extracted from the hot flue gas 121 to the inlet stream of cold carbon dioxide-rich gas 123 and the inlet stream of cold nitrogen-rich gas 124, thereby producing heated carbon dioxide-rich gas 125 and heated nitrogen-rich gas 126.

[0038] In addition to providing cooler gas to gas separator 106, heat exchanger 104 also reheats the separated gases 123 and 124 output from gas separator 106. This benefits the operation of the first thermochemical reactor 112 and the second thermochemical reactor 114, which typically require relatively high temperatures (e.g., about 700°C or about 800°C, as described below). Heat exchanger 104 may also be configured as a heat storage tank and / or temperature regulator so that changes in the heat flux received from hot flue gas 121 and changes in the demand for heated separated gases 123, 124 do not cause changes in the output temperature of the reheated separated gases. In some embodiments, heat exchanger 104 may receive electrical energy to provide additional heat to one or both of gas streams 123 and 124.

[0039] The reheated gases 123 and 124 can reach a temperature of approximately 700°C when they leave the heat exchanger 104.

[0040] Gas separator 106 is arranged to receive cooled flue gas 122, separate carbon dioxide from other gases in the cooled flue gas 122, and output cooled carbon dioxide-rich gas 123 (which may contain at least 90% carbon dioxide, and small amounts of nitrogen and carbon monoxide) and cooled nitrogen-rich gas 124 (which may contain at least 90% nitrogen, and small amounts of carbon dioxide and carbon monoxide). Any suitable technology may be used for gas separation, such as (but not limited to): adsorption, membrane, or chemical receiver.

[0041] The first thermochemical reactor 112 receives heated carbon dioxide-rich gas 125 and reduces / decomposes the carbon dioxide through oxidation of thermochemical compounds within the reactor, generating carbon monoxide-rich gas 128. The temperature of the first thermochemical reactor 112 can be approximately 800°C. The temperature of the carbon monoxide-rich gas 125 as it exits the first thermochemical reactor 112 can be approximately 800°C (e.g., ±25°C).

[0042] The second thermochemical reactor 114 receives heated nitrogen-enriched gas 126 and generates oxygen-enriched gas 127 (containing oxygen and nitrogen) through the reduction of thermochemical compounds. The temperature of the second thermochemical reactor can be approximately 700°C. Nitrogen is used as an inert carrier gas / purge gas. In some cases, the heated nitrogen-enriched gas may contain trace amounts of hydrogen, which can increase the reduction of thermochemical compounds. The oxygen-enriched gas 127 may contain at least 20% or at least 50% oxygen by volume, with the balance consisting of nitrogen and trace amounts of hydrogen and carbon monoxide. The temperature of the oxygen-enriched gas 127 as it exits the second thermochemical reactor 114 can be approximately 700°C (e.g., ±25°C).

[0043] Oxygen-rich gas 127 and carbon monoxide-rich gas 128 are burned together in burner 103 to generate heat.

[0044] The thermochemical compounds in the first and second thermochemical reactors 112 are preferably capable of undergoing reversible thermochemical cycles. In the first part of the cycle, the thermochemical compounds are oxidized and carbon monoxide is generated from carbon dioxide; in the second part of the cycle (at an elevated temperature compared to the first part of the cycle), the thermochemical compounds are reduced and oxygen is generated.

[0045] System 11 can be configured to cycle between a first thermochemical reactor and a second thermochemical reactor. In the first system mode, the first thermochemical reactor 112 generates carbon monoxide, and the second thermochemical reactor 114 generates oxygen. In the second system mode, the first thermochemical reactor 112 generates oxygen, and the second thermochemical reactor 114 generates carbon monoxide.

[0046] System 11 may include an electrically operated valve and a temperature control system. The electrically operated valve is capable of redirecting gas flow to achieve this mode switching, and the temperature control system is used to change the operating temperature of the thermochemical reactors 112 and 114 according to their operating modes. For example, the first part of the thermochemical cycle may require a temperature of approximately 700°C, while the second part of the cycle may require a temperature of 800°C or higher.

[0047] The two main classes of materials capable of thermochemically cycling carbon dioxide to carbon monoxide are simple metal oxides or mixed metal oxides, such as perovskites. Cerium dioxide (cerium oxide) is one example of a metal oxide that can be used to decompose carbon dioxide in good yields; however, it requires high temperatures, such as 1400 °C for reduction and 900 °C for oxidation. Cerium dioxide is a non-stoichiometric oxygen carrier, meaning that less than one mole of oxygen is released per mole of cerium dioxide. Other metal oxides that can be used include volatile metal oxides and iron oxides. Volatile metal oxides are stoichiometric oxygen carriers, and their pure metallic melting points are below the reduction temperatures of the metal oxides.

[0048] Perovskites are non-stoichiometric mixed metal oxides with the ideal chemical formula ABO3, where A and B are metallic elements. An example of a perovskite used in thermochemical cycles is La. 1-x Sr x MnO3 group, which can be reduced at about 1400°C and oxidized at about 900°C, has a fuel yield ten times higher than that of cerium dioxide.

[0049] Ba2Ca 0.66 Nb 1.34-x Fe x O6 (x=0, 0.34, 0.66 and 1) is a double perovskite that can be reduced and decomposed into CO2 at about 800°C, making it particularly suitable for thermochemical cycles to generate carbon monoxide from carbon dioxide.

[0050] Examples of perovskites suitable for decomposing carbon dioxide into carbon monoxide in the implementation plan include those listed in Table 1 below:

[0051] Table 1: Examples of perovskites used for carbon dioxide decomposition The thermochemical reaction is reversible, and the thermochemical compound is reduced to produce oxygen. In the first example, all the oxygen produced by the thermochemical reaction is burned with carbon monoxide, thus providing heat for furnace 102.

[0052] Many materials can undergo thermochemical cycling, but Ba2Ca 0.66 Nb 0.34 FeO6 (BCNF1) may be used due to its high yield, low reaction temperature, 100% selectivity for CO, and low activation energy for oxidation. BCNF1 is a bis-perovskite material. When BCNF1 is reduced under nitrogen at 700°C, the crystal structure loses oxygen, forming oxygen vacancies and releasing oxygen.

[0053] Where δ equals the degree of non-stoichiometry. BCNF1 is oxidized at 800°C under carbon dioxide, causing CO2 to decompose into CO, and oxygen is reincorporated into the lattice by filling oxygen vacancies, thus reforming the original perovskite.

[0054]

[0055] This allows the reduction and oxidation cycle to be repeated, thus decomposing CO2. It was found that BCNF1 can convert 10.1% of CO2 into CO per cycle (average of five cycles). Using an electric heater with an efficiency of 85%, 150m³ of CO2 was produced. 3 / hr of CO requires 5700 kWh of electricity. At an electricity price of £0.11 / kWh, the cost of producing carbon monoxide at this power plant would be £0.19 per kilogram. At an electricity price of £0.05 (the average US industrial electricity price), the cost of carbon monoxide would be £0.11 per kilogram.

[0056] While BCNF1 is particularly promising as a thermochemical compound, any suitable material can be used. The temperatures of the first and second thermochemical reactors described herein are relative to BCNF1, but different temperatures may be required if other thermochemical compounds (such as those listed in the table above) are used.

[0057] Each of the first thermochemical reactor 112 and the second thermochemical reactor 114 can receive heat from electrical energy 129, which is preferably derived from renewable energy sources (e.g., wind, solar, pumped storage, hydropower, hydrothermal, etc.). The electrical energy input to the first thermochemical reactor 112 and the second thermochemical reactor 114 can account for a large portion (e.g., more than 90%) of the energy supplied to the system 11.

[0058] System 11 can be a closed-loop system that essentially converts electrical energy into chemical potential energy in the form of carbon monoxide, which is then released in burner 103 by burning the carbon monoxide to heat furnace 102. This heat release method is very similar to existing furnace systems that currently rely on fossil fuels. The closed gas loop means that almost no carbon dioxide is emitted into the atmosphere, so this method can be used to eliminate carbon emissions in certain industrial processes that require heating.

[0059] Figure 1 An example is shown where furnace 102 is designed to operate at high temperatures, such as above 800°C. In such a system, combustion may take place within the furnace (and burner 103).

[0060] In systems requiring lower temperatures (e.g., below 800°C) within the furnace 102, the high-temperature gases produced by combustion can be cooled before being introduced into the furnace 102 to prevent excessively high temperatures within the furnace 102.

[0061] Figure 2 Example system 12 is shown, which includes: furnace 102, burner 103, heat exchanger 104, gas separator 106, first thermochemical reactor 112, and second thermochemical reactor 114. System 12 operates in conjunction with... Figure 1 The system shown is similar, except that the burner 103 is separated from the furnace 102 and exchanges the heat generated by the combustion of carbon monoxide with the gas streams 130 and 131 input to the first thermochemical reactor 112 and the second thermochemical reactor 114.

[0062] More specifically, carbon monoxide-rich gas 125 and oxygen-rich gas 126 are fed into burner 103, where carbon monoxide reacts with oxygen to generate hot flue gas 120 containing carbon dioxide. Part of the heat from the hot flue gas is transferred to the heated carbon dioxide-rich gas 125 (from heat exchanger 104) and the heated nitrogen-rich gas 126 (from heat exchanger 104), forming further heated carbon dioxide-rich gas 130 and further heated nitrogen-rich gas 131, respectively. The further heated carbon dioxide-rich gas 130 is fed into the first thermochemical reactor 112, and the further heated nitrogen-rich gas 131 is fed into the second thermochemical reactor 114.

[0063] The first thermochemical reactor 112 and the second thermochemical reactor 114 produce carbon monoxide-rich gas 128 and oxygen-rich gas 127, which are used for combustion in burner 103, in a manner similar to that described in the reference. Figure 1 The system described above operates in the same manner as the first thermochemical reactor 112 and the second thermochemical reactor 114. The characteristics of these reactors also apply to this embodiment.

[0064] Compared to system 11, the temperature of the carbon dioxide-containing flue gas 121 discharged from furnace 102 in system 12 is reduced, but it is still hot enough (e.g., >600°C or more than 400°C) to allow cooling of flue gas 121 in heat exchanger 104 to improve gas separation in gas separator 106.

[0065] See Figure 3 An example is shown where a thermal power plant 101 generates electricity 140 by burning fuel to produce carbon dioxide-containing flue gas 121. The thermal power plant 101 can generate energy, for example, by burning waste or biomass, or by burning methane obtained through biological digestion. The energy 140 can be supplied to a power distribution system (e.g., a national grid) so that it can be consumed by end users.

[0066] like Figure 3 As shown, system 13 includes: heat exchanger 104, gas separator 106, first auxiliary heat exchanger 104a, second auxiliary heat exchanger 104b, first thermochemical reactor 112, second thermochemical reactor 114, auxiliary gas separator 106a, and carbon monoxide storage tank 116.

[0067] The flue gas 121 from the thermal power plant 101 can have a temperature of 250-1000°C and mainly contains carbon dioxide, water and nitrogen.

[0068] Flue gas 121 is received by heat exchanger 104, see reference Figure 1 and Figure 2 It operates in a similar manner to that described. The heat exchanger 104 receives hot flue gas 121 and extracts heat from it to produce cooled flue gas 122. The temperature of the cooled flue gas 122 can be between 100 and 250°C (e.g., 150°C).

[0069] Gas separator 106 reference Figure 1 and Figure 2 The gas separator 106 described herein operates in a similar manner. The gas separator 106 receives cooled flue gas 122 and separates it into a cold (<400°C or below <250°C) stream rich in carbon dioxide 123, a stream rich in nitrogen 124, and water (vapor) 129. Water 129 can be discharged into the atmosphere.

[0070] The first thermochemical reactor 112 and the second thermochemical reactor 114 refer to Figure 2 They operate in a similar manner as described, receiving further heated carbon dioxide-rich gas 130 and further heated nitrogen-rich gas 131, respectively. As described above, the first thermochemical reactor 112 and the second thermochemical reactor 114 can circulate between different operating modes to generate carbon monoxide and oxygen.

[0071] The first auxiliary heat exchanger 104a imparts heat from the carbon monoxide-rich gas 128 to the heated carbon dioxide-rich gas 126.

[0072] Carbon monoxide-rich gas 128 exiting from the first thermochemical reactor 112 is cooled by a first auxiliary heat exchanger 104a to produce cold carbon monoxide-rich gas 134. An auxiliary gas separator 106a receives the cold carbon monoxide-rich gas 134, separates any carbon dioxide 135 from the cold carbon monoxide-rich gas 134, and returns the separated carbon dioxide 135 to the first thermochemical reactor 112 (where the carbon dioxide will be converted into carbon monoxide).

[0073] An additional gas separator 106a thereby produces a purified stream of cold carbon monoxide 136, which is stored in a carbon monoxide reservoir 116. The reservoir 116 may be a gas reservoir for receiving and storing carbon monoxide in gaseous form. In some embodiments, carbon monoxide may also be stored in liquid form.

[0074] The second auxiliary heat exchanger 104b imparts heat from the oxygen-enriched gas 127 to the heated nitrogen-enriched gas 125. The oxygen-enriched gas 127 output from the second thermochemical reactor 114 is cooled by the second auxiliary heat exchanger 104b to produce cold oxygen-enriched gas 133, which can be released into the atmosphere (or further purified and collected in a storage device similar to a carbon monoxide storage device).

[0075] Heat exchanger 104, the first auxiliary heat exchanger 104a, and the second auxiliary heat exchanger 104b may each be configured as a heat storage device and / or a temperature regulator, such that changes in heat flux and gas flow rate do not cause changes in the output temperature of the reheated gas. In some embodiments, at least one (or all) of heat exchanger 104, as well as the first auxiliary heat exchanger 104a and the second auxiliary heat exchanger 104b, may receive electrical energy to provide additional heat to the gas flow output therefrom.

[0076] Such as Figure 3 The illustrated implementation scheme can be used to reduce carbon dioxide emissions from thermal power plant 101 by generating carbon monoxide from carbon dioxide. For example... Figure 1 and Figure 2 As described, electrical energy 129 is supplied to the first thermochemical reactor 112 and the second thermochemical reactor 114 to maintain them at suitable temperatures for oxidation and reduction reactions (forming carbon monoxide through oxidation of thermochemical compounds and forming oxygen through reduction of thermochemical compounds).

[0077] In some implementations, the furnace can operate under a variety of different conditions (e.g., temperature). The system can be configured to operate the furnace at temperatures above or below 800°C (i.e., the multi-furnace can operate as at least two of the following: a high-temperature furnace, a medium-temperature furnace, and a low-temperature furnace (e.g., in response to a control signal)).

[0078] Embodiments of the present invention are particularly suitable for processing titanium alloys prone to hydrogen embrittlement. Using carbon monoxide as the furnace fuel source can potentially eliminate hydrogen in the furnace, making carbon monoxide-fueled furnaces a potentially advantageous method for titanium processing. Similarly, carbon monoxide-fueled furnaces may be attractive for other hydrogen-sensitive processes.

[0079] In any of the examples above, the furnace can operate continuously (e.g., via a conveyor system). In some implementations, intermittent furnaces may be used. In intermittent processing, heat storage devices may be required to conserve energy and stabilize system operation.

[0080] In each of the above examples, a buffer tank / storage tank may be required for any gas flow (e.g., carbon monoxide-rich gas before entering the burner).

[0081] Although specific examples have been described, variations may be made within the scope of the appended claims.

Claims

1. A system comprising: furnace; A heat exchanger is arranged to receive and cool flue gas containing carbon dioxide and nitrogen from the furnace, thereby producing cooled flue gas. A gas separator is arranged to receive the cooled flue gas and separate the cooled flue gas into nitrogen-rich gas and carbon dioxide-rich gas; wherein, a heat exchanger is arranged to heat the nitrogen-rich gas and the carbon dioxide-rich gas. as well as A first thermochemical reactor comprising a thermochemical compound is configured to receive heated carbon dioxide-rich gas in a first mode of the system and to generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through oxidation by the thermochemical compound, thereby forming a carbon monoxide-rich gas.

2. The system of claim 1 further includes a second thermochemical reactor, the second thermochemical reactor containing the thermochemical compound, the second thermochemical reactor being configured to receive heated nitrogen-rich gas and generate oxygen by reduction of the thermochemical compound in the second thermochemical reactor to form oxygen-rich gas.

3. The system according to any of the preceding claims, wherein, The system can operate in a second mode, in which the first thermochemical reactor is configured to receive heated nitrogen-rich gas and generate oxygen through the reduction of thermochemical compounds in the first thermochemical reactor to form oxygen-rich gas.

4. The system according to claim 3, comprising the subject matter of claim 2, wherein, In the second system mode, the second thermochemical reactor is configured to receive heated carbon dioxide-rich gas and generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through oxidation by the thermochemical compound, thereby forming carbon monoxide-rich gas.

5. The system according to claim 3 or 4, wherein, The system is configured to switch between the first mode and the second mode to maintain the generation of carbon monoxide and oxygen from the first thermochemical reactor and the second thermochemical reactor.

6. The system according to any one of claims 2-5, wherein, The system is configured to react the oxygen-enriched gas with the carbon monoxide-enriched gas to provide heat to the furnace.

7. The system according to any of the preceding claims, wherein, The system includes a burner configured to burn the carbon monoxide-rich gas to provide heat to the furnace, wherein the burner is located inside or outside the furnace.

8. The system according to any of the preceding claims, wherein, The system includes an additional gas separator configured to generate purified carbon monoxide gas from the carbon monoxide-rich gas.

9. The system according to any of the preceding claims, wherein, The system is configured to receive flue gas from waste-to-energy plants and / or biomass power plants.

10. The system according to any one of claims 1-9, wherein, The furnace is a high-temperature furnace arranged to operate at a temperature of at least 800°C; or a medium-low temperature furnace arranged to operate at a temperature below 800°C.

11. The system according to any of the preceding claims, wherein, The thermochemical compounds include metal oxides, perovskite materials, or double perovskite materials.

12. The system according to any of the preceding claims, wherein, The first thermochemical reactor and optionally the second thermochemical reactor are configured to receive input electrical energy to heat the thermochemical reactor.

13. The system according to any of the preceding claims, wherein, The system is configured to receive at least 90% of the net input energy in the form of electrical energy.

14. An industrial method comprising: The flue gas is cooled in a heat exchanger to produce cooled flue gas containing carbon dioxide and nitrogen. The cooled flue gas is separated into nitrogen-rich gas and carbon dioxide-rich gas; The nitrogen-rich gas and the carbon dioxide-rich gas are heated using a heat exchanger; Carbon monoxide is generated from carbon dioxide in the carbon dioxide-rich gas through oxidation of thermochemical compounds in the first thermochemical reactor, thus forming a carbon monoxide-rich gas.

15. The method of claim 14, further comprising generating oxygen by reducing the thermochemical compound in a second thermochemical reactor to form an oxygen-enriched gas.

16. The method according to claim 14 or 15, further comprising generating oxygen in the first thermochemical reactor by reducing a thermochemical compound in the first thermochemical reactor to form an oxygen-enriched gas.

17. The method of claim 16, comprising the subject matter of claim 2, wherein, In the second system mode, the second thermochemical reactor is configured to receive heated carbon dioxide-rich gas and generate carbon monoxide from the carbon dioxide in the heated carbon dioxide-rich gas through oxidation by the thermochemical compound, thereby forming carbon monoxide-rich gas.

18. The method of claim 16 or 17, further comprising switching between the first mode and the second mode to maintain the generation of carbon monoxide and oxygen from the first thermochemical reactor and the second thermochemical reactor.

19. The method according to any one of claims 15-18, comprising generating heat for the furnace by reacting an oxygen-rich gas with a carbon monoxide-rich gas.

20. The method according to any one of claims 14-19, comprising burning the carbon monoxide-rich gas in a burner to provide heat to the furnace, wherein the burner is located inside or outside the furnace.

21. The method according to any one of claims 14-20, further comprising generating purified carbon monoxide gas from the carbon monoxide-rich gas.

22. The method according to any one of claims 14-21, wherein, The flue gas originates from a waste-to-energy plant and / or a biomass power plant.

23. The method according to any one of claims 14-21, comprising providing heat to: i) A high-temperature furnace operating at a temperature of at least 800°C; or ii) Low-temperature furnaces operating at temperatures below 800°C.

24. The method according to any one of claims 14-23, wherein, The thermochemical compounds include metal oxides, perovskite materials, or double perovskite materials.

25. The method according to any one of claims 14-24, wherein, The first thermochemical reactor and optionally the second thermochemical reactor receive renewable input electrical energy to heat the thermochemical reactor.

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