Chemical Looping Combustion System

Abstract

To provide a chemical looping combustion system with an improved energy efficiency of the entirety of the system.SOLUTION: A chemical looping combustion system comprises an air tower for oxidizing metal particles by using air, a fuel tower in which hydrocarbon is supplied as fuel, a gas containing oxidized metal particles and nitrogen is supplied from the air tower, and the metal particles are reduced by using the fuel to exhaust a mixed gas containing carbon dioxide, and a separator for separating carbon dioxide and nitrogen contained in the mixed gas and extracting carbon dioxide.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a chemical looping combustion system. [Background technology]

[0002] A chemical looping combustion system capable of essentially separating carbon dioxide is known (see, for example, Patent Document 1). In the system described in Patent Document 1, a metal as a solid oxygen carrier is oxidized by reacting with oxygen in the air in an air reactor, and the oxidized metal is reduced by fuel in a fuel reactor and then oxidized again in the air reactor. Flue gas containing carbon dioxide and water vapor is discharged from the fuel reactor. The water vapor in the flue gas is separated from the carbon dioxide by cooling or condensation. The separated carbon dioxide is then liquefied or compressed. Non-Patent Document 1 discloses zeolite as an adsorbent that adsorbs carbon dioxide in a mixed gas and separates it. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2013-522149 [Non-patent literature]

[0004] [Non-Patent Document 1] Joe McEwen, Jim-Dario Hayman, and A. Ozgur Yazaydin. "A comparative study of CO2, CH4 and N2 adsorption in ZIF-8, Zeolite-13X and BPL activated carbon." Chemical Physics volume 412, 1 February 2013, Pages 72-76 Summary of the Invention [Problem to be solved by the invention]

[0005] In the system described in Patent Document 1, sulfur oxides, nitrogen oxides, and the like contained in the flue gas discharged from the fuel reactor are removed by supplying the flue gas to a pollutant removal device. However, Patent Document 1 makes no mention of removing nitrogen contained in the air supplied by the air reactor. Meanwhile, a chemical looping combustion system is known that includes a loop seal between the air reactor and the fuel reactor to suppress nitrogen flow from the air reactor to the fuel reactor and increase the carbon dioxide concentration in the flue gas discharged from the fuel reactor. However, achieving complete gas sealing using a loop seal is difficult. Minimizing nitrogen leakage into the fuel reactor requires increasing the number of metal particles in the loop seal. However, increasing the loop seal size increases the time required for the metal particles heated in the air reactor to travel to the fuel reactor. As a result, heat loss from the metal particles traveling through the system increases, and the lost heat must be compensated for by heating the fuel reactor, reducing the energy efficiency of the chemical looping combustion system. Non-Patent Document 1 discloses the adsorption performance of zeolite, but does not mention a chemical looping combustion system.

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and has an object to improve the energy efficiency of the entire chemical looping combustion system. [Means for solving the problem]

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms. 1. A chemical looping combustion system comprising: an air tower that oxidizes metal particles using air, a fuel tower that is supplied with hydrocarbon as fuel and a gas containing the oxidized metal particles and nitrogen from the air tower, and that reduces the metal particles using the fuel to discharge a mixed gas containing carbon dioxide, a separator that separates the carbon dioxide and nitrogen contained in the mixed gas to extract the carbon dioxide, wherein the fuel tower is supplied with a gas containing oxygen in addition to the fuel. 2. A chemical looping combustion system comprising: an air tower that oxidizes metal particles using air, a fuel tower that is supplied with hydrocarbon as fuel and a gas containing the oxidized metal particles and nitrogen from the air tower, and that reduces the metal particles using the fuel to discharge a mixed gas containing carbon dioxide, a separator that separates the carbon dioxide and nitrogen contained in the mixed gas to extract the carbon dioxide, and a loop seal disposed downstream of the air tower and upstream of the fuel tower, the loop seal preventing nitrogen from flowing into the fuel tower from the air tower and receiving the gas containing oxygen. In addition, the present invention can also be realized in the following forms.

[0008] (1) According to one aspect of the present invention, a chemical looping combustion system is provided. The metal looping combustion system comprises an air tower that uses air to oxidize metal particles, a fuel tower that receives a hydrocarbon as fuel and a gas containing the oxidized metal particles and nitrogen from the air tower, reduces the metal particles using the fuel, and discharges a mixed gas containing carbon dioxide, and a separator that separates the carbon dioxide and nitrogen contained in the mixed gas and extracts the carbon dioxide.

[0009] With this configuration, the separator separates the carbon dioxide and nitrogen in the mixed gas discharged from the fuel tower, eliminating the need for a device to prevent nitrogen from entering the fuel tower (such as a large loop seal). As a result, the heat loss of metal particles that occurs when the gas passes through these devices can be reduced, improving the energy efficiency of the entire system.

[0010] (2) The chemical looping combustion system of the above aspect may further include a heat exchanger to which the mixed gas discharged from the fuel tower is supplied and which recovers heat generated in the fuel tower via the mixed gas, and a dehydrator which removes water contained in the mixed gas from which heat has been recovered by the heat exchanger, and the separator may separate carbon dioxide and nitrogen contained in the mixed gas from which water has been removed by the dehydrator, using the heat recovered by the heat exchanger. The mixed gas discharged from the fuel tower is cooled to remove water from the mixed gas using a dehydrator. As a result, the sensible heat of the mixed gas is discarded as waste heat. In this configuration, the waste heat of the mixed gas is used to separate carbon dioxide and nitrogen in the separator, improving the energy efficiency of the entire system.

[0011] (3) In the chemical looping combustion system of the above aspect, a gas containing oxygen may be supplied to the fuel tower in addition to the fuel. The reduction reaction of metal particles in the fuel tower is an endothermic reaction or an exothermic reaction that generates a small amount of heat. With this configuration, when a gas containing oxygen is supplied to the fuel tower, an oxidation reaction occurs between the supplied oxygen and the reduced metal particles, causing the temperature inside the fuel tower to rise. This raises the temperature inside the fuel tower to a temperature suitable for the reduction reaction, accelerating the reduction reaction. Furthermore, the heat of the reaction between the metal particles and oxygen inside the fuel tower is directly used to raise the temperature inside the fuel tower. Therefore, the fuel tower can be heated with less energy than when the fuel tower is heated from the outside.

[0012] (4) The chemical looping combustion system of the above aspect may further include a loop seal disposed downstream of the air tower and upstream of the fuel tower, the loop seal suppressing the inflow of nitrogen from the air tower to the fuel tower and through which a gas containing oxygen is supplied. According to this configuration, a gas containing oxygen is supplied to a loop seal disposed between the air tower and the fuel tower. The oxygen supplied to the loop seal flows into both the air tower and the fuel tower. As a result, the oxygen flowing into the air tower suppresses the nitrogen flowing from the air tower into the loop seal, thereby suppressing the inflow of nitrogen into the fuel tower. Furthermore, the oxygen flowing from the loop seal into the fuel tower generates heat by undergoing an oxidation reaction with reduced metal atoms. This reduces the energy required to separate N2 using the separator, and also enables the fuel tower to be heated with less energy, further improving the energy efficiency of the entire system.

[0013] (5) In the chemical looping combustion system of the above aspect, the dehydrator may be a temperature swing type dehydrator, and may remove water contained in the mixed gas by utilizing the heat recovered by the heat exchanger. According to this configuration, the heat recovered by the heat exchanger can be used not only by the separator but also by the dehydrator. Therefore, by controlling the heat used by each of the separator and the dehydrator, This can further improve the energy efficiency of the entire system.

[0014] (6) In the chemical looping combustion system of the above aspect, a control unit is further provided that acquires a required calorific value required for the air tower, and when the required calorific value is acquired, controls the flow rate of air as the oxygen-containing gas supplied to the fuel tower, and the control unit determines whether the required calorific value is W AR (kW), and the lower heating value of the fuel is LHV fuel (kJ / mol), and the heat generated per 1 mol of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mol), and the amount of heat absorbed per 1 mol of fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mol), and the oxygen concentration in the air is X O2 In this case, the flow rate of the oxygen-containing gas supplied to the fuel tower is calculated by the following formula (1): air _ FR Alternatively, the temperature may be controlled to be 30% or more and 300% or less of the above.

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[0015] (7) The chemical looping combustion system of the above aspect further includes a temperature acquisition unit that acquires a temperature inside the fuel tower, and the control unit controls a flow rate Q of air supplied to the fuel tower according to the temperature acquired by the temperature acquisition unit. air _ FR may be controlled. According to this configuration, the amount of air supplied to the fuel tower is controlled using the temperature acquired by the temperature acquisition unit. Because the temperature inside the fuel tower rises due to the oxidation reaction between the oxygen contained in the air and the metal particles, the temperature inside the fuel tower can be controlled by controlling the flow rate of the supplied air. By controlling the temperature inside the fuel tower to a temperature suitable for the reduction reaction and the oxidation reaction, the energy efficiency of the entire system can be improved.

[0016] (8) In the chemical looping combustion system of the above aspect, when the difference between the target temperature in the fuel tower and the temperature acquired by the temperature acquisition unit is equal to or greater than zero, the control unit multiplies the difference by a preset constant to obtain a flow rate Q air _ FR When the difference is negative, control may be performed so that air containing oxygen is supplied to the fuel tower, and when the difference is negative, control may be performed so that gas containing oxygen is not supplied to the fuel tower. According to this configuration, when the temperature inside the fuel tower is lower than the target temperature, the flow rate of air supplied to the fuel tower is increased. As a result, when the temperature inside the fuel tower is lower than the target temperature, the oxygen in the air supplied to the fuel tower undergoes an oxidation reaction with the metal particles, causing the temperature inside the fuel tower to rise. On the other hand, when the temperature inside the fuel tower is higher than the target temperature, the supply of air to the fuel tower is stopped. As a result, the oxidation reaction inside the fuel tower decreases, causing the temperature inside the fuel tower to fall. In other words, with this configuration, the flow rate of air supplied to the fuel tower is controlled so as to approach the target temperature, thereby improving the energy efficiency of the entire system based on the target temperature.

[0017] The present invention can be realized in various modes, for example, Chemical Lupin The present invention can be realized in the form of a chemical looping combustion system, a chemical looping combustion device, a chemical looping combustion method, a system including these devices, a computer program for executing these devices, a server device for distributing this computer program, a non-transitory storage medium storing the computer program, etc. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic block diagram of a chemical looping combustion system according to one embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram of the amount of CO2 adsorption by zeolite, which changes depending on the CO2 concentration in a mixed gas. [Figure 3] FIG. 1 is an explanatory diagram of the principle of chemical looping combustion. [Figure 4] FIG. 1 is a schematic block diagram of a chemical looping combustion system according to a comparative example. [Figure 5] FIG. 1 is a schematic block diagram of a chemical looping combustion system according to a second embodiment. [Figure 6] FIG. 10 is a schematic block diagram of a chemical looping combustion system according to a third embodiment. [Figure 7] FIG. 10 is a schematic block diagram of a chemical looping combustion system according to a fourth embodiment. [Figure 8] FIG. 10 is a schematic block diagram of a chemical looping combustion system according to a sixth embodiment. [Figure 9] FIG. 10 is a schematic block diagram of a chemical looping combustion system according to a seventh embodiment. [Figure 10] FIG. 13 is a schematic block diagram of a chemical looping combustion system according to an eighth embodiment. [Figure 11] FIG. 13 is a schematic block diagram of a chemical looping combustion system according to a ninth embodiment. [Figure 12] 10 is a flowchart of control of the flow rate of air supplied to the fuel tower. DETAILED DESCRIPTION OF THE INVENTION

[0019] First Embodiment FIG. 1 is a schematic block diagram of a chemical looping combustion system (hereinafter, simply referred to as the "combustion system") 100 according to one embodiment of the present invention. In conventional chemical looping combustion systems, an air tower loop seal (loop seal) 60, located between an air tower 10 that oxidizes metal particles (mg) and a fuel tower 20 that reduces the metal particles (mg), prevents nitrogen from flowing from the air tower 10 to the fuel tower 20, allowing high-purity carbon dioxide (CO2) to be recovered from the fuel tower 20. In contrast, in this embodiment, the greatest advantage of the combustion system 100 is that it eliminates the need to supply carbon dioxide to a heat utilization destination, and the production of high-purity CO2 is considered a secondary benefit. In other words, while the presence of CO2 in the air tower 10 is problematic, the presence of nitrogen (N2) in the fuel tower 20 is not an essential problem. This improves the energy efficiency of the entire combustion system 100.

[0020] The combustion system 100 of this embodiment allows a constant flow rate of N2 to flow from the air tower 10 to the fuel tower 20, and separates N2 and CO2 from the mixed gas containing CO2 obtained from the fuel tower 20 using a separator 50. The separator 50 separates N2 and CO2 in the mixed gas by utilizing waste heat from the fuel tower 20, thereby preventing the air tower side loop seal unit 60 from becoming large and improving the energy efficiency of the entire combustion system 100.

[0021] Within the combustion system 100, metal particles (mg) circulate, repeatedly undergoing oxidation in the air tower 10 and reduction in the fuel tower 20 to transport oxygen (O2) from the air tower 10 to the fuel tower 20. In this embodiment, an example will be described in which FeTiO3 is used as the metal particles (mg). The particle size of the metal particles (mg) is 50 mm or more and 250 mm or less. As shown in FIG. 1, the combustion system 100 of the first embodiment includes an air tower 10, a fuel tower 20, an air tower side loop seal unit 60, a fuel tower side loop seal unit 70, a cyclone 15, a heat exchanger 30, a dehydrator 40, a separator 50, and a heater 25.

[0022] The air tower 10 uses air containing O2 to oxidize FeTiO3 by causing the reaction shown in the following formula (2): The oxidation reaction of formula (2) generates heat, which warms the gas in the air tower 10, and the inside of the air tower 10 is heated to approximately 1000 degrees Celsius (°C).

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[0023] As shown in FIG. 1, the air tower 10 has a cylindrical shape extending vertically. A seal 10S is provided vertically below the air tower 10. The seal 10S is a member with a number of small holes. The seal 10S allows air supplied from vertically below the air tower 10 to flow into the air tower 10 and carry the metal particles mg vertically upward. However, the size of the holes provided in the seal 10S is smaller than the metal particles mg, preventing the metal particles mg from passing through the seal 10S and leaking out of the air tower 10. The gas flow velocity flowing vertically upward within the air tower 10 is set to a terminal velocity at which gravity and the drag force due to the gas flow are balanced, or to a velocity greater than the terminal velocity.

[0024] The metal particles (mg) oxidized in the air tower 10 flow into the cyclone 15 connected via a pipe. The cyclone 15 separates the metal particles (mg) from the heated gas using centrifugal force. As shown in FIG. 1, the gas heated in the air tower 10 flows out vertically above the cyclone 15 and is supplied to the heat utilization destination. The gas supplied to the heat utilization destination is composed mostly of N2 because O2 has been reduced due to the oxidation of the metal particles (mg) in the air tower 10. The metal particles (mg) separated from the gas in the cyclone 15 move to the air tower side loop seal unit 60 through a pipe extending vertically downward in the center of the cyclone 15, as shown in FIG. 1.

[0025] As shown in FIG. 1, the air tower side loop seal unit 60 is located downstream of the air tower 10 and upstream of the fuel tower 20. A seal 60S is provided vertically below the air tower side loop seal unit 60. The seal 60S is a member with multiple fine holes. The fine holes formed in the seal 60S are smaller than the particle size of the metal particles mg. Therefore, as shown in FIG. 1, a particle layer (the hatched area) made of multiple metal particles mg is formed on the upper surface of the seal 60S. Water vapor is used here because even if water vapor flows into the fuel tower 20, it can be removed by the heat exchanger 30 and the dehydrator 40.

[0026] In the air tower side loop seal unit 60, water vapor is supplied from vertically below the seal 60S. The supplied water vapor passes through the seal 60S and flows into the fuel tower 20, which is connected downstream of the air tower side loop seal unit 60. Because water vapor is supplied into the air tower side loop seal unit 60 from below the seal 60S, gas mainly composed of N2, whose flow direction is indicated by the arrow in Figure 1, is prevented from passing through the particle layer and flowing into the fuel tower 20. However, some gas containing N2 passes through the air tower side loop seal unit 60 together with metal particles mg as shown in Figure 1 and flows into the fuel tower 20.

[0027] A fluidized bed that flows from the air tower side loop seal unit 60 to the fuel tower 20 is arranged in the piping that connects the air tower side loop seal unit 60 and the fuel tower 20. Due to the flow of the fluidized bed, the metal particles mg discharged from the cylindrical air tower side loop seal unit 60 move to the fuel tower 20.

[0028] The fuel tower 20 is supplied with methane (CH4) as fuel, and also with a gas containing oxidized metal particles mg and N2 from the air tower 10. The fuel tower 20 reduces the metal particles mg using methane and discharges a mixed gas containing CO2. The fuel tower 20 is shown in FIG. The fuel tower 20 has a cylindrical shape extending vertically so that the fuel tower 20 can be easily opened. A seal 20S is provided vertically below the fuel tower 20. The seal 20S is a member with multiple small holes. In the fuel tower 20, gaseous fuel is supplied from below the seal 20S. The gas flow rate within the fuel tower 20 is set to a rate slower than the terminal velocity, and is controlled based on the information of the fuel tower 20 so that metal particles mg do not fly out.

[0029] In the fuel tower 20, to which CH4 is supplied as fuel, 4Fe2TiO5, which is the metal particles mg oxidized in the air tower 10 as shown in the above formula (2), is reduced by CH4 to FeTiO3 as shown in the following formula (3), generating CO2. The reduction reaction shown in the following formula (3) is an endothermic reaction.

[0030]

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[0031] If we take the sum of the oxidation reaction in the air tower 10 represented by the above formula (2) and the reduction reaction in the fuel tower 20 represented by the above formula (3), the reactions occurring in the air tower 10 and the fuel tower 20 are the same as the combustion of methane, which is the fuel, represented by the following formula (4). In other words, the total amount of heat obtained in the combustion system 100 (the sum of the heat generated by the air tower 10 and the heat absorbed by the fuel tower 20) is the same as that obtained by the combustion of CH4, which is the fuel.

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[0032] As shown in Fig. 1, the mixed gas containing CO2 produced by the reduction reaction in the fuel tower 20 flows out from the vertically upper part of the fuel tower 20 and is sent to the heat exchanger 30. Details of the mixed gas supplied to the heat exchanger 30 will be described later. The metal particles mg reduced by the reduction reaction in the fuel tower 20 move to the fuel tower side loop seal unit 70 through a pipe extending vertically downward provided in the center of the fuel tower 20, as shown in Fig. 1.

[0033] The heater 25 is attached to the cylindrical outer wall of the fuel tower 20. The heater 25 is heated by power supplied from an external power source, thereby heating the inside of the fuel tower 20. Because the reduction reaction expressed by the above formula (3) is an endothermic reaction, the heater 25 raises the temperature inside the fuel element 20, which has been cooled by the endothermic reaction.

[0034] The fuel tower side loop seal unit 70, to which metal particles (mg) are supplied from the fuel tower 20, is located downstream of the fuel tower 20 and upstream of the air tower 10. The fuel tower side loop seal unit 70 has the same configuration as the air tower side loop seal unit 60. A seal 70S is provided vertically below the fuel tower side loop seal unit 70. The seal 70S is a member with multiple small holes. Steam is supplied to the fuel tower side loop seal unit 70 from vertically below the seal 70S. The supplied steam passes through the seal 70S and flows into the air tower 10, which is connected downstream of the fuel tower side loop seal unit 70. A fluidized bed is provided in the piping connecting the fuel tower side loop seal unit 70 and the air tower 10, allowing the metal particles (mg) to flow from the fuel tower side loop seal unit 70 to the air tower 10. The fluidized bed moves the metal particles (mg) in the cylindrical fuel tower side loop seal unit 70 to the air tower 10. As described above, the metal particles mg are oxidized in the air tower 10 and reduced in the fuel tower 20, and circulate between the air tower 10 and the fuel tower 20.

[0035] The mixed gas discharged from vertically above the fuel tower 20 contains CO2 and water vapor (HO) produced by the reduction reaction expressed by the above formula (3), and N2 that has flowed into the fuel tower 20 through the air tower-side loop seal unit 60. The inside of the fuel tower 20 in this embodiment is controlled by the heater 25 to maintain a temperature of approximately 1000°C to promote the reduction reaction. Therefore, the mixed gas discharged from the fuel tower 20 is at a high temperature of approximately 1000°C.

[0036] As shown in Fig. 1, the mixed gas discharged from the fuel tower 20 is supplied to a heat exchanger 30 that recovers heat. The heat exchanger 30 recovers heat generated in the fuel tower 20 via the mixed gas supplied from the fuel tower 20. The heat exchanger 30 has water flowing inside as a heat medium, and recovers heat via the mixed gas by exchanging heat between the mixed gas and the heat medium. In other words, heat is removed from the mixed gas by the heat exchanger 30.

[0037] The mixed gas from which heat has been recovered by the heat exchanger 30 is supplied to the dehydrator 40. The dehydrator 40 removes HO contained in the mixed gas from which heat has been recovered by the heat exchanger 30. Therefore, the mixed gas discharged from the dehydrator 40 contains CO and N from which HO has been removed, as shown in FIG.

[0038] The mixed gas discharged from the dehydrator 40 is supplied to the separator 50. The separator 50 is a temperature swing separator that uses heat recovered by the heat exchanger 30 to separate CO2 and N2 contained in the mixed gas from which H2O has been removed, thereby extracting CO2. The separator 50 is composed of multiple shell-and-tube adsorption towers. The tube side of each shell-and-tube adsorption tower is filled with zeolite, which can adsorb and desorb CO2. During CO2 adsorption, the zeolite is cooled with water at approximately 25°C, and during CO2 desorption, it is heated using the heat recovered by the heat exchanger 30. The separator 50 can continuously separate CO2 and N2 by separately controlling the multiple adsorption towers into adsorption towers and desorption towers. Note that because zeolite adsorbs not only CO2 but also H2O, the dehydrator 40 is located upstream of the separator 50.

[0039] The mixed gas from which N2 has been separated and discharged from the separator 50 is high-purity CO2. This high-temperature gas is sent to a destination where the CO2 will be used, such as a storage tank where the CO2 is liquefied or pressurized and stored.

[0040] FIG. 2 is an explanatory diagram of the change in the CO2 adsorption amount of zeolite depending on the CO2 concentration in the mixed gas. In FIG. 2, the change in the CO2 adsorption amount per unit gram of 13-type zeolite depending on the CO2 concentration in the mixed gas is shown as curve C1. The horizontal axis of FIG. 2 represents the concentration in the mixed gas flowing into the inlet of separator 50, and the vertical axis represents the adsorption amount (mmol) adsorbed by zeolite per gram. For comparison, FIG. 2 also shows the change in the CH4 adsorption amount adsorbed by zeolite depending on the CH4 concentration in the mixed gas as curve C2. For comparison, FIG. 2 also shows the change in the N2 adsorption amount adsorbed by zeolite depending on the N2 concentration in the mixed gas as curve C3.

[0041] As shown in Figure 2, the higher the concentration of CO2, CH4, and N2 in the mixed gas, the greater the adsorption amount of zeolite. At the same inlet concentration, the CO2 adsorption amount is much greater than either the CH4 or N2 adsorption amount. The CH4 and N2 adsorption amounts increase linearly with increasing inlet concentration. Meanwhile, the CO2 adsorption amount, represented by curve C1, decreases almost linearly as the inlet concentration gradually decreases from 100% until the inlet concentration reaches approximately 30%. When the inlet concentration is less than 30%, the rate at which the CO2 adsorption amount decreases relative to the decrease in inlet concentration decreases significantly. This suggests that zeolite will adequately adsorb CO2 unless the CO2 concentration in the mixed gas supplied to the separator 50 is extremely low, such as less than 30%.

[0042] Figure 3 is an explanatory diagram of the principle of chemical looping combustion. Figure 3 shows a schematic block diagram of a fuel system 100x of a comparative example. The fuel system 100x of the comparative example includes an air tower 10 that oxidizes metal particles, a fuel tower 20 that reduces the oxidized metal particles, and a dehydrator 40 that removes HO from the mixed gas supplied from the fuel tower 20. In Figure 3, the metal atoms (or molecules) used as the metal particles mg are represented as Me.

[0043] Air is supplied to the air tower 10, and the reaction heat from the oxidation reaction of the metal particles (mg) is supplied to the heat utilization destination as high-temperature N2 containing no CO2. In the fuel tower 20, the oxidized metal particles (mg) are reduced to fuel such as CH4, and the mixed gas containing CO2 produced by the reduction reaction is supplied to the dehydrator 40. The dehydrator 40 removes H2O from the mixed gas, and the mixed gas containing high-purity CO2 is supplied to the CO2 utilization destination.

[0044] <Comparative Example> Fig. 4 is a schematic block diagram of a chemical looping combustion system (combustion system) 100x of a comparative example. Compared to the combustion system 100 shown in Fig. 1, the combustion system 100x of the comparative example shown in Fig. 4 does not include the heat exchanger 30 and the separator 50. Instead, the combustion system 100x of the comparative example includes an air tower side loop seal unit 60x that is larger than the air tower side loop seal unit 60 of the embodiment.

[0045] In the combustion system 100x of the comparative example, N2 in the mixed gas discharged from the fuel tower 20 is not separated by the separator 50, so it is necessary to suppress the inflow of N2 into the fuel tower 20. To achieve this, the air tower side loop seal unit 60x of the comparative example is enlarged. The enlargement of the air tower side loop seal unit 60x increases the particle layer formed by multiple metal particles mg within the air tower side loop seal unit 60x. As a result, the enlarged particle layer can suppress the inflow of N2 into the fuel tower 20. However, as the particle layer increases, it takes longer for the metal particles mg discharged from the cyclone 15 to flow into the fuel tower 20. Therefore, the temperature of the metal particles mg heated by the oxidation reaction in the air tower 10 drops before they flow into the fuel tower 20. In the fuel tower 20, the temperature effect of the metal particles mg needs to be compensated for by heating with the heater 25, etc. In order to reduce the energy used for heating the heater 25, etc., it is preferable that the air tower side loop seal portion 60x is made small and the particle layer formed in the air tower side loop seal portion 60x is small.

[0046] In contrast, the combustion system 100 of this embodiment is equipped with a separator 50 that separates CO2 and N2 contained in the mixed gas and extracts CO2. In the combustion system 100, heat generated by the oxidation reaction of metal particles (mg) in the air tower 10 is supplied to the heat utilization destination via N2, which does not contain CO2, as shown in FIG. 1. Because the gas supplying heat does not contain CO2, mixing of CO2 with impurities specific to the heat supply destination is suppressed, thereby preventing carbon dioxide from being unable to be recovered from the destination. Furthermore, in this embodiment, N2 in the mixed gas discharged from the fuel tower 20 is separated by the separator 50, so high-purity CO2 can be recovered even if nitrogen flows into the fuel tower 20. Because the separator 50 separates N2 from the mixed gas, there is no need to enlarge the air tower-side loop seal unit 60x, as in the comparative fuel system 100x. As a result, the time that metal particles (mg) remain in the air tower-side loop seal unit 60 can be shortened, thereby suppressing heat loss during the movement of metal particles (mg) from the air tower 10 to the fuel tower 20. Therefore, the energy efficiency of the entire combustion system 100 of this embodiment can be improved. The combustion system 100 of this embodiment is a system that was arrived at based on the idea that the greatest advantage of a chemical looping combustion system is that it is not necessary to supply CO2 to the heat supply destination, and that while the inflow of CO2 into the air tower 10 is a problem, the inflow of N2 into the fuel tower 20 is not a problem. The combustion system 100 of this embodiment is simply a system for separating N2. Not only is the separator 50 provided, but also allowing N2 to flow into the fuel tower 20 improves the energy efficiency of the entire combustion system 100.

[0047] Furthermore, the heat exchanger 30 of this embodiment recovers heat generated in the fuel tower 20 via the mixed gas supplied from the fuel tower 20. The separator 50 uses the heat recovered by the heat exchanger 30 to separate CO2 and N2 contained in the mixed gas and extract CO2. In the fuel system 100x of the comparative example, the heat of the high-temperature mixed gas supplied to the dehydrator 40 was wasted in order to remove H2O by the dehydrator 40, but in this embodiment, the waste heat of the mixed gas is used for N2 separation by the separator 50. As a result, the energy efficiency of the entire combustion system 100 of this embodiment can be improved.

[0048] Second Embodiment 5 is a schematic block diagram of a chemical looping combustion system (combustion system) 100a of the second embodiment. The fuel system 100a of the second embodiment differs from the combustion system 100 of the first embodiment in that air is supplied as a gas containing O2 to the fuel tower 20a in addition to CH4 as fuel. In the second embodiment, only the configurations different from those of the first embodiment will be described, and a description of the same configurations will be omitted.

[0049] In the second embodiment, air is supplied together with CH4 from below the seal 20S of the fuel tower 20a. The supply of air generates heat through an oxidation reaction between O2 contained in the air and the metal particles (mg) reduced to CH4 of the fuel. The N2 contained in the air supplied to the fuel tower 20a is separated from CO2 by the separator 50, just like the N2 flowing from the air tower 10 into the fuel tower 20a.

[0050] As described above, in the combustion system 100a of the second embodiment, air is supplied to the fuel tower 20a as a gas containing oxygen in addition to the fuel CH4. The reduction reaction between the metal particles mg and CH4 in the fuel tower 20a is an endothermic reaction. According to the combustion system 100a of the present embodiment, air containing O2 is supplied to the fuel tower 20a, and an oxidation reaction occurs between the O2 in the supplied air and the reduced metal particles mg, raising the temperature inside the fuel tower 20a. This raises the temperature inside the fuel tower 20a to a temperature suitable for the reduction reaction, accelerating the reduction reaction. Furthermore, the heat of the reaction between the metal particles mg and O2 in the fuel tower 20a is directly used to raise the temperature inside the fuel tower 20a. Therefore, the fuel tower 20a can be heated with less energy than when the fuel tower 20a is heated by the heater 25.

[0051] <Third embodiment> 6 is a schematic block diagram of a chemical looping combustion system (combustion system) 100b of the third embodiment. The fuel system 100b of the third embodiment differs from the combustion system 100 of the first embodiment in that air is supplied as an O2-containing gas to the air tower side loop seal section 60b. In the third embodiment, only the configurations different from those of the first embodiment will be described, and a description of the same configurations will be omitted.

[0052] In the third embodiment, air is supplied together with water vapor from below the seal 60S of the air tower side loop seal portion 60b. When air is supplied to the air tower side loop seal portion 60b, part of the air flows into the fuel tower 20, and the remaining air flows into the cyclone 15. The O2 in the air flowing into the fuel tower 20 reacts with the metal particles mg reduced in the fuel tower 20, similar to the O2 in the air supplied to the fuel tower 20a in the second embodiment. The heat generated by the oxidation reaction between O2 and the metal particles mg raises the temperature inside the fuel tower 20. In addition, the air supplied from below the seal 60S suppresses N2 that attempts to flow from the air tower 10 into the air tower side loop seal portion 60b, just like water vapor, and therefore suppresses the inflow of N2 into the fuel tower 20. As a result, the required water vapor flow rate can be reduced, and the energy required to generate water vapor (the energy required to heat water) can be reduced. ) can be reduced.

[0053] As described above, in the combustion system 100b of the third embodiment, air as an O2-containing gas is supplied to the air tower side loop seal unit 60b. In the third embodiment, air containing O2 is supplied to the air tower side loop seal unit 60b, which is disposed between the air tower 10 and the fuel tower 20. The air supplied to the air tower side loop seal unit 60b flows into both the air tower 10 and the fuel tower 20. As a result, the air flowing into the air tower 10 suppresses N2 flowing from the air tower 10 into the air tower side loop seal unit 60b, thereby suppressing N2 flow into the fuel tower 20 with a smaller steam flow rate. Furthermore, the oxygen flowing into the fuel tower 20 from the air tower side loop seal unit 60b generates heat by oxidation reaction with the reduced metal atoms mg. This reduces the energy required to separate N2 by the separator 50, reduces the energy required to generate steam, and further reduces the energy required to heat the fuel tower 20, thereby further improving the energy efficiency of the entire combustion system 100b.

[0054] <Fourth embodiment> 7 is a schematic block diagram of a chemical looping combustion system (combustion system) 100c of the fourth embodiment. The fuel system 100c of the fourth embodiment differs from the combustion system 100a of the second embodiment in that it does not include a heater 25, heat recovered by a heat exchanger 30 is utilized in a dehydrator 40c and a separator 50c, and the flow rates of air and fuel supplied to a fuel tower 20a are controlled. In the fourth embodiment, by controlling the flow rates of air and fuel supplied to the fuel tower 20a, the heat generated by the heater 25 is compensated for by heat generated by the oxidation reaction of metal particles mg in the fuel tower 20a. Note that in the fourth embodiment, only the configurations different from those of the second embodiment will be described, and a description of the same configurations will be omitted.

[0055] The combustion system 100c of the fourth embodiment includes a control unit 80 that controls the flow rates of air and CH4 as fuel supplied to the fuel tower 20a. The control unit 80 is configured with a well-known device such as a mass flow controller. The control unit 80 compensates for the heat generated by the oxidation reaction of the metal particles mg in the fuel tower 20a to compensate for the heat generated by the external heat source such as the heater 25 for heating the fuel tower 20a.

[0056] Assume that 1 kW of heat is continuously generated in the air tower 10. In this case, the fuel tower 20 requires the reduction of metal particles (mg) with CH4 at a flow rate of 1.5 slm. The heat absorbed by the reduction reaction at this flow rate is 0.116 kW. To compensate for this heat absorption by reoxidizing the metal particles (mg) in the fuel tower 20a, air at a flow rate of 1.9 slm and CH4 at a flow rate of 0.2 slm are required. The specific heat values ​​in the fuel tower 20a are 0.132 kW generated by the air at a flow rate of 1.9 slm and 0.016 kW absorbed by the CH4 at a flow rate of 0.2 slm, resulting in a net heat of 0.116 kW. When air at a flow rate of 1.9 slm and CH4 at a flow rate of 0.2 slm are supplied to the fuel tower 20a, the composition of the mixed gas after H2O removal supplied to the separator 50c is 53% CO2 and 47% N2. 2, it can be seen that zeolite can sufficiently adsorb CO2 in the mixed gas even when the inlet CO2 concentration in the mixed gas is 53%. In other words, even without heating the fuel tower 20a with the heater 25, the temperature inside the fuel tower 20a can be controlled to a temperature at which the reduction reaction occurs by utilizing the reoxidation of the metal particles mg after reduction in the fuel tower 20a.

[0057] The dehydrator 40c of the fourth embodiment is a temperature swing type dehydrator. The separator 50c of the fourth embodiment is a temperature swing type separator. The dehydrator 40c of the fourth embodiment removes H2O from the mixed gas by utilizing the heat of the mixed gas recovered by the heat exchanger 30.

[0058] As described above, in the fourth embodiment, the heater 25 for heating the fuel tower 20a is not required, The inside of the fuel tower 20a is heated by the heat generated by the reoxidation of the metal particles mg in the fuel tower 20a. Furthermore, in addition to the separator 50c, the dehydrator 40c can also use the heat recovered by the heat exchanger 30. Therefore, by controlling the heat used in each of the separator 50c and the dehydrator 40c, the energy efficiency of the entire combustion system 100c can be further improved.

[0059] Fifth Embodiment The chemical looping combustion system of the fifth embodiment has the same configuration as the fuel system 100c of the fourth embodiment, but differs in the control content by the control unit 80. Therefore, in the fifth embodiment, only the control content of the control unit 80 that differs from that of the fourth embodiment will be described, and a description of the other configurations will be omitted.

[0060] The control unit 80 of the fifth embodiment acquires the required calorific value required by the heat utilization destination, that is, the calorific value WAR (kW) of the oxidation reaction of the metal particles mg in the air tower 10, and then controls the flow rate Q of the air containing O2 according to the calorific value WAR. air _ FR (slm) and the flow rate of CH4 as fuel Q fuel _ add _ AR The control unit 80 calculates the calculated air flow rate Q air _ FR and the fuel flow rate Q fuel _ add _ AR The flow rate of each of the above is controlled to be 30% or more and 300% or less to be supplied to the fuel tower 20a.

[0061] Air flow rate Q air _ FR and fuel flow rate Q fuel _ add _ AR are expressed as the following formulas (1) and (5). In the following formulas (1) and (5), the calorific value LHV fuel (kJ / mol), calorific value Δh AR (kJ / mol), endothermic amount Δh FR (kJ / mol), oxygen concentration X O2, and the molar amount b (mol / mol) are defined as follows:

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[0062] As described above, in the fifth embodiment, the flow rate of the air containing O2 supplied to the fuel tower 20 is the flow rate Q air _ FR When the fuel is CH4, the air flow rate Q air _ FR Since the upper limit of the flow rate of O2 supplied to the fuel tower 20 is 300%, it is possible to prevent the CO2 content in the mixed gas discharged from the fuel tower 20 from becoming less than 30%. As shown in FIG. 2, the zeolite used in the separator 50c requires a rapid increase in the energy required to separate N2 as the CO2 content in the mixed gas decreases from less than 30%. In this embodiment, the CO2 content in the mixed gas is 30% or more, so the energy required for separation can be reduced. Furthermore, if the flow rate of O2 supplied to the fuel tower 20 is too low, the effect of the oxidation reaction between O2 and the metal particles mg in the fuel tower 20 is reduced. However, if the lower limit of the flow rate of air supplied to the fuel tower 20 is the flow rate Q air _ FR By controlling the temperature to 30% of the above, sufficient reaction heat can be obtained from the oxidation reaction in the fuel tower 20.

[0063] Sixth Embodiment 8 is a schematic block diagram of a chemical looping combustion system (combustion system) 100d of the sixth embodiment. The fuel system 100d of the sixth embodiment differs from the combustion system 100c of the fourth embodiment in that it includes a heat exchanger 35 and a vacuum pump 55. In the sixth embodiment, only the configurations that are different from those of the fourth embodiment will be described, and descriptions of the same configurations will be omitted.

[0064] 8, a fuel system 100d of the sixth embodiment includes a heat exchanger 35 that recovers heat from the high-temperature N2 discharged from the cyclone 15, and a vacuum pump 55 disposed downstream of the separator 50c. In this embodiment, when the heat exchanger 30, to which the mixed gas is supplied from the fuel tower 20a, recovers less heat from the mixed gas than is necessary to operate the dehydrator 40c and the separator 50c, the heat exchanger 35 recovers a portion of the heat supplied to the heat utilization destination and supplies it to at least one of the dehydrator 40c and the separator 50c. When the desorption rate of the zeolite during desorption in the separator 50c is insufficient, the desorption rate is improved by using a pressure swing by the vacuum pump 55 in combination with a temperature swing.

[0065] As described above, in the combustion system 100d of the sixth embodiment, the heat exchanger 35 recovers and utilizes a portion of the heat supplied to the heat utilization destination, and the vacuum pump 55 separates N2 and CO2 using a pressure swing. This improves the energy efficiency of the entire combustion system 100d. Note that the fuel systems of other embodiments may not include either the heat exchanger 35 or the vacuum pump 55.

[0066] Seventh Embodiment 9 is a schematic block diagram of a chemical looping combustion system (combustion system) 100e of the seventh embodiment. The fuel system 100e of the seventh embodiment differs from the combustion system 100d of the sixth embodiment in that it does not include a heat exchanger 35 and that the dehydrator 40e and the separator 50e are pressure swing types. Since the dehydrator 40e is a pressure swing type, the combustion system 100e includes a vacuum pump 45 connected to the dehydrator 40e. In the seventh embodiment, only the configurations that are different from those of the sixth embodiment will be described, and a description of the same configurations will be omitted.

[0067] The dehydrator 40e of the seventh embodiment removes H2O from the mixed gas by a pressure swing system using a vacuum pump 45 that is operated using energy supplied from an external source. The separator 50e is a pressure swing system, which differs from the separator of the sixth embodiment that uses both a temperature swing system and a pressure swing system. The heat exchanger 30e of the seventh embodiment recovers heat from the mixed gas supplied from the fuel tower 20a and discards it as waste heat outside the combustion system 100e.

[0068] As described above, even in the combustion system 100e of the seventh embodiment, if the energy loss of the sensible heat of the mixed gas discharged from the fuel tower 20a is smaller than the heat dissipation loss due to the enlargement of the air tower side loop seal section 60 and the energy loss due to heating by the heater 25, the energy efficiency of the entire combustion system 100e can be improved.

[0069] Eighth Embodiment 10 is a schematic block diagram of a chemical looping combustion system (combustion system) 100f of the eighth embodiment. The fuel system 100f of the eighth embodiment differs from the combustion system 100e of the seventh embodiment in that it includes a heater 25 and that only fuel is supplied to the fuel tower 20 without air being supplied to it. In the eighth embodiment, only the configurations that are different from those of the seventh embodiment will be described, and descriptions of the same configurations will be omitted.

[0070] Since air containing O2 is not supplied to the fuel tower 20 of the eighth embodiment, a reoxidation reaction of the reduced metal particles mg does not occur within the fuel tower 20. Instead, the fuel tower 20 is heated by the heater 25, which is heated by external energy. Even in the combustion system 100f of the eighth embodiment, the energy efficiency of the entire combustion system 100f can be improved if the sum of the energy loss due to the sensible heat of the mixed gas discharged from the fuel tower 20a and the energy required for heating by the heater 25 is smaller than the heat loss due to the enlargement of the air tower side loop seal unit 60.

[0071] Ninth Embodiment 11 is a schematic block diagram of a chemical looping combustion system (combustion system) 100g of the ninth embodiment. The chemical looping combustion system of the ninth embodiment differs from the fuel system 100c (FIG. 7) of the fourth embodiment in that it includes a temperature sensor (temperature acquisition unit) 90 that detects the temperature inside the fuel tower 20a and in the control content by the control unit 80g. Therefore, in the ninth embodiment, only the configuration and control content that are different from the fourth embodiment will be described, and a description of other configurations, etc. will be omitted.

[0072] The control unit 80g of the ninth embodiment controls the flow rate Q of the air supplied to the fuel tower 20a in accordance with the temperature acquired by the temperature sensor 90. air _ FR Specifically, the control unit 80g controls the target temperature in the fuel tower 20a to be T tar If the target temperature T tar The air flow rate Q is determined according to the temperature difference ΔT obtained by subtracting the detected temperature T1 detected by the temperature sensor 90 from the temperature difference ΔT. air _ FR When the temperature difference ΔT is equal to or greater than zero, the flow rate Q shown in the following equation (6) is controlled. air _ FR This air is supplied to the fuel tower 20a. Note that k in the following equation (6) is a preset proportionality constant.

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[0073] When the temperature difference ΔT is negative, the control unit 80g controls the flow rate Q of the air supplied to the fuel tower 20a. air _ FR is set to zero. That is, when the temperature in the fuel tower 20a is higher than the target temperature, air is not supplied to the fuel tower 20a.

[0074] FIG. 12 shows the flow rate Q of air supplied to the fuel tower 20a. air _ FR In the control flow shown in FIG. 12, the control unit 80g controls the flow rate of the predetermined initial flow rate Q air The control unit 80g acquires the detected temperature T1 in the fuel tower 20a detected by the temperature sensor 90 (step S2). The control unit 80g calculates the target temperature T tar It is determined whether the temperature difference ΔT obtained by subtracting the detected temperature T1 from the temperature difference ΔT is equal to or greater than zero (step S3). If it is determined that the temperature difference ΔT is less than zero (step S3: NO), the processes from step S2 onwards are repeated.

[0075] If it is determined that the temperature difference ΔT is equal to or greater than zero (step S3: YES), the control unit 80g calculates the flow rate Q air _ FR The supply flow rate to the fuel tower 20a is controlled so as to supply air of this amount (step S4). Thereafter, it is determined whether or not to terminate the control of the chemical looping combustion system (step S5). The determination of whether to terminate the control is made, for example, by receiving an input of control termination from an external source. If it is determined not to terminate the control (step S5: NO), the processing from step S2 onwards is repeated. If it is determined to terminate the control (step S5: YES), the control of the chemical looping combustion system is terminated. The determination of whether to terminate the control may be made while any of the processing shown in FIG. 12 is being performed.

[0076] As described above, the control unit 80g of the ninth embodiment controls the flow rate Q of the air supplied to the fuel tower 20a in accordance with the temperature acquired by the temperature sensor 90. air _ FRIn the fuel tower 20a, the temperature inside the fuel tower 20a rises due to an oxidation reaction between O2 contained in the air and the metal particles mg. Therefore, the flow rate Q of the supplied air is controlled. air _ FR By controlling the temperature in the fuel tower 20a to a temperature suitable for the reduction reaction and the reoxidation reaction, the energy efficiency of the entire combustion system 100g can be improved.

[0077] In addition, the control unit 80g of the ninth embodiment controls the target temperature T tar When the temperature difference ΔT obtained by subtracting the detected temperature T1 detected by the temperature sensor 90 from the temperature difference ΔT is equal to or greater than zero, the flow rate Q air _ FR On the other hand, when the temperature difference ΔT is negative, the control unit 80g controls the flow rate Q of the air supplied to the fuel tower 20a. air _ FR is set to zero. According to the combustion system 100g of this embodiment, the target temperature T tar When the detected temperature T1 in the fuel tower 20a is lower than air _ FR As a result, the detected temperature T1 increases to the target temperature T tar If the detected temperature T1 is lower than the target temperature T2, the O2 in the air supplied to the fuel tower 20a increases and reacts with the metal particles mg, causing the temperature inside the fuel tower 20a to rise. tar If the temperature is higher than the target temperature T , the supply of air into the fuel tower 20a is stopped. As a result, the oxidation reaction in the fuel tower 20a decreases, and the temperature in the fuel tower 20a drops. That is, in the combustion system 100g of this embodiment, tar The flow rate Q of air supplied into the fuel tower 20a is set to be close to air _ FR is controlled, the target temperature T tar Based on this, the energy efficiency of the entire combustion system (100g) can be improved.

[0078] <Modifications of the embodiment> The present invention is not limited to the above-described embodiment, and can be implemented in various forms without departing from the spirit of the present invention, including, for example, the following modifications: In the above-described embodiment, part of the configuration realized by hardware may be replaced by software, and conversely, part of the configuration realized by software may be replaced by hardware.

[0079] In the first to ninth embodiments, an example of a chemical looping combustion system has been described, but the chemical looping combustion system can be modified as long as it includes the air tower 10, the fuel tower 20, and the separator 50. For example, the combustion system 100 does not need to include the air tower side loop seal unit 60 or the fuel tower side loop seal unit 70. The oxygen-containing gas supplied to the air tower 10, the air tower side loop seal unit 60b (FIG. 6), and the fuel tower 20a (FIG. 5) may be other than air as long as it contains oxygen. When a gas other than air is supplied, the oxygen concentration X O2 is changed appropriately and the flow rate Q air _ FR An oxygen-containing gas may be calculated instead of air. The air tower 10 can also be described as an oxidation tower to which an oxygen-containing gas is supplied to oxidize the metal particles (mg). The heat supplied to the separator 50 may be only the heat recovered by the heat exchanger 35 from the high-temperature N2 gas discharged from the cyclone 15, rather than the heat recovered by the heat exchanger 30 (FIG. 8) from the mixed gas discharged from the fuel tower 20a.

[0080] The metal particles mg circulating through the combustion system 100 can be made of well-known materials other than FeTiO3. Similarly, the fuel supplied to the fuel tower 20 can be made of well-known materials other than CH4, such as C2H6 or C3H8. For example, nickel (Ni) or copper (Cu) can be used as the metal particles mg, and C2H6 can be used as the fuel. In this case, the reduction reaction occurring in the fuel tower 20 is expressed by the following equations (7) and (8).

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[0081] In addition, instead of zeolite as the material capable of absorbing and desorbing CO2 filled in the separator 50, other well-known materials such as activated carbon can be used. air _ FR The air can be transformed into a gas containing oxygen. Similarly, the flow rate Q shown in equation (5) above fuel _ add _ AR The fuel can be varied within the range of fuel that can reduce the metal particles mg in the fuel tower 20. The parameters in the above formulas (1) and (5) may be changed depending on the oxygen-containing gas and fuel.

[0082] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0083] The present invention can also be realized in the following forms. [Application example 1] 1. A chemical looping combustion system comprising: an air tower that oxidizes metal particles using air; a fuel tower to which hydrocarbon is supplied as fuel and to which a gas containing oxidized metal particles and nitrogen is supplied from the air tower, the fuel being used to reduce the metal particles and discharging a mixed gas containing carbon dioxide; a separator that separates carbon dioxide and nitrogen contained in the mixed gas and extracts carbon dioxide; A chemical looping combustion system comprising: [Application example 2] The chemical looping combustion system according to Application Example 1, further comprising: a heat exchanger to which the mixed gas discharged from the fuel tower is supplied and which recovers heat generated in the fuel tower via the mixed gas; a dehydrator that removes water contained in the mixed gas from which heat has been recovered by the heat exchanger, The separator utilizes the heat recovered by the heat exchanger to separate the carbon dioxide and nitrogen contained in the mixed gas from which water has been removed by the dehydrator. [Application example 3] The chemical looping combustion system according to Application Example 1 or Application Example 2, A chemical looping combustion system, wherein the fuel tower is supplied with a gas containing oxygen in addition to the fuel. [Application example 4] The chemical looping combustion system according to any one of Application Examples 1 to 3, further comprising: a loop seal disposed downstream of the air tower and upstream of the fuel tower, the loop seal preventing nitrogen from flowing from the air tower into the fuel tower and supplying oxygen-containing gas; A chemical looping combustion system with seals. [Application example 5] The chemical looping combustion system according to any one of Application Examples 1 to 4, The dehydrator is It is a temperature swing type dehydrator, A chemical looping combustion system that uses the heat recovered by the heat exchanger to remove water contained in the mixed gas. [Application Example 6] The chemical looping combustion system according to any one of Application Example 1 to Application Example 5, further comprising: a control unit that acquires a required calorific value required for the air tower, and controls a flow rate of air as an oxygen-containing gas to be supplied to the fuel tower when the required calorific value is acquired; The control unit determines whether the required heat generation amount is W AR (kW), and the lower heating value of the fuel is LHV fuel(kJ / mol), and the heat generated per 1 mol of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mol), and the amount of heat absorbed per 1 mol of fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mol), and the oxygen concentration in the air is X O2 In this case, the flow rate of the oxygen-containing gas supplied to the fuel tower is calculated by the following formula (1): air _ FR A chemical looping combustion system that controls the combustion temperature to be between 30% and 300% of the original level.

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[0084] 10...Air Tower 10S...Seal 15...Cyclone 20,20a…Fuel tower 20S...Seal 25...Heater 30,30e,35…heat exchanger 40,40c,40e…Dehydrator 45,55...Vacuum pump 50,50c,50e…separator 60, 60b, 60x...Air tower side loop seal 60S...Seal 70...Fuel tower side loop seal 70S...Seal 80,80g...Control unit 90...Temperature sensor 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100x...Fuel system b...The amount of moles of O2 required to completely combust 1 mole of fuel C1, C2, C3...CO2 adsorption curve LHV fuel …calorific value per 1 mol of fuel mg…metal particles Q air _ FR …Air flow rate Q air _0...Initial air flow rate Q fuel _ add _ FR …Fuel flow rate ΔT…Temperature difference T1: Detected temperature T tar …Target temperature WAR: Amount of heat generated during oxidation reaction X O2 …Oxygen concentration Δh AR …The heat generated by the oxidation reaction per 1 mol of O2 Δh FR …Amount of heat absorbed by the reduction reaction per 1 mol of fuel

Claims

1. 1. A chemical looping combustion system comprising: an air tower that oxidizes metal particles using air; a fuel tower to which hydrocarbon is supplied as fuel and to which a gas containing oxidized metal particles and nitrogen is supplied from the air tower, the fuel being used to reduce the metal particles and discharging a mixed gas containing carbon dioxide; a separator that separates carbon dioxide and nitrogen contained in the mixed gas and extracts carbon dioxide; Equipped with A chemical looping combustion system, wherein the fuel tower is supplied with a gas containing oxygen in addition to the fuel.

2. A chemical looping combustion system, comprising: an air tower that oxidizes metal particles using air; a fuel tower to which hydrocarbon is supplied as fuel and to which a gas containing oxidized metal particles and nitrogen is supplied from the air tower, the fuel being used to reduce the metal particles and discharging a mixed gas containing carbon dioxide; a separator that separates carbon dioxide and nitrogen contained in the mixed gas and extracts carbon dioxide; a loop seal disposed downstream of the air tower and upstream of the fuel tower, the loop seal suppressing the inflow of nitrogen from the air tower to the fuel tower and receiving a gas containing oxygen; A chemical looping combustion system comprising:

3. The chemical looping combustion system according to claim 1 or 2, further comprising: a control unit that acquires a required calorific value required for the air tower, and controls a flow rate of air as an oxygen-containing gas to be supplied to the fuel tower when the required calorific value is acquired; The control unit determines the required heat generation amount as W AR (kW), and the lower heating value of the fuel is LHV fuel (kJ / mol), and the heat generation rate per 1 mol of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mol), and the amount of heat absorbed per 1 mol of the fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mol), and the oxygen concentration in the air is X O2 In this case, the flow rate of the oxygen-containing gas supplied to the fuel tower is calculated by the following formula (1): air _ FR A chemical looping combustion system that controls the combustion temperature to be between 30% and 300% of the original level. [0011]

4. 4. The chemical looping combustion system of claim 3, further comprising: a temperature acquisition unit that acquires a temperature inside the fuel tower, The control unit controls the flow rate Q of air supplied to the fuel tower in accordance with the temperature acquired by the temperature acquisition unit. air _ FR A chemical looping combustion system that controls

5. 5. The chemical looping combustion system of claim 4, The control unit When the difference obtained by subtracting the temperature acquired by the temperature acquisition unit from the target temperature in the fuel tower is equal to or greater than zero, a flow rate Q obtained by multiplying the difference by a preset constant is calculated. air _ FR air is supplied to the fuel tower; When the difference is negative, the chemical looping combustion system controls so that no oxygen-containing gas is supplied to the fuel tower.

6. The chemical looping combustion system according to claim 1 or 2, further comprising: a heat exchanger to which the mixed gas discharged from the fuel tower is supplied and which recovers heat generated in the fuel tower via the mixed gas; The separator separates the carbon dioxide and nitrogen contained in the mixed gas by utilizing the heat recovered by the heat exchanger.

7. 7. The chemical looping combustion system of claim 6, further comprising: A chemical looping combustion system of a temperature swing type, comprising a dehydrator that removes water contained in the mixed gas by utilizing the heat recovered by the heat exchanger.

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