Chemical looping combustion system

Abstract

A chemical looping combustion system has an air tower that oxidizes metal particles using air, a fuel tower, and a separator; a fuel tower in which hydrocarbons are supplied as fuel, and oxidized metal particles and a gas containing nitrogen are supplied from the air tower, the metal particles are reduced by the fuel, and a mixed gas containing carbon dioxide is discharged; and the separator is used for separating carbon dioxide and nitrogen contained in the mixed gas and taking out the carbon dioxide.

Description

Technical Field

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

[0002] Chemical looping combustion systems that can substantially separate carbon dioxide are known (for example, see Patent Document 1). In the system described in Patent Document 1, a metal serving as a solid oxygen carrier reacts with oxygen in the air in an air reactor and is oxidized. 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 and condensing. The separated carbon dioxide is liquefied or compressed. Zeolite as an adsorbent material for adsorbing carbon dioxide in a mixed gas and separating carbon dioxide is disclosed in Non-Patent Document 1.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2013-522149

[0006] Non-patent literature

[0007] Non-Patent Document 1: Joe McEwen, Jim-Dario Hayman and A. Ozgur Yazaydin, “A comparative study of CO2, CH4and N2 adsorption in ZIF-8, Zeolite-13X and BPL activated carbon,” Chemical Physics, Vol. 412, February 1, 2013, pp. 72-76 Summary of the invention

[0008] Problems to be solved by the invention

[0009] In the system described in Patent Document 1, sulfur oxides, nitrogen oxides, etc. contained in the flue gas discharged from the fuel reactor are removed by supplying the flue gas to the pollutant removal device. However, in Patent Document 1, there is no mention of the removal of nitrogen contained in the air supplied by the air reactor. On the other hand, the following chemical loop combustion system is known: in order to suppress the nitrogen flowing from the air reactor into the fuel reactor and thus increase the concentration of carbon dioxide contained in the flue gas discharged from the fuel reactor, there is a loop seal between the air reactor and the fuel reactor. However, it is difficult to achieve a complete gas seal using the loop seal. In order to minimize the leakage of nitrogen to the fuel reactor, it is necessary to increase the metal particles in the loop seal. However, when the loop seal is enlarged in order to increase the loop seal, the time required for the metal particles heated in the air reactor to move to the fuel reactor becomes longer. As a result, the heat loss of the metal particles increases when moving in the system, and it is necessary to heat the lost part of the heat in the fuel reactor, so the energy efficiency of the chemical loop combustion system is reduced. The adsorption performance of zeolite is disclosed in Non-Patent Document 1, but the chemical loop combustion system is not mentioned.

[0010] The present invention has been made to solve at least a part of the above-mentioned problems, and its object is to improve the overall energy efficiency of the chemical looping combustion system.

[0011] Means used to solve problems

[0012] The present invention has been made to solve at least a part of the above-mentioned problems, and can be implemented in the following aspects.

[0013] (1) According to one embodiment of the present invention, a chemical looping combustion system is provided. The chemical looping combustion system comprises: an air tower, which uses air to oxidize metal particles; a fuel tower, in which hydrocarbons are supplied as fuel, and oxidized metal particles and a gas containing nitrogen are supplied from the air tower, and the metal particles are reduced by the fuel and a mixed gas containing carbon dioxide is discharged; and a separator, in which the carbon dioxide and nitrogen contained in the mixed gas are separated and the carbon dioxide is taken out.

[0014] With this configuration, since the carbon dioxide and nitrogen in the mixed gas discharged from the fuel tower are separated by the separator, there is no need to have a device (for example, a large-scale loop seal, etc.) that inhibits the flow of nitrogen into the fuel tower. As a result, the heat loss of metal particles generated by passing through these devices can be suppressed, so in this configuration, the energy efficiency of the entire system is improved.

[0015] (2) In the chemical chain combustion system of the above-mentioned manner, there may also be a heat exchanger, which is supplied with the mixed gas discharged from the fuel tower, and recovers the heat generated in the fuel tower via the mixed gas. The separator uses the heat recovered by the heat exchanger to separate the carbon dioxide and nitrogen contained in the mixed gas.

[0016] In order to remove water from the mixed gas, the mixed gas discharged from the fuel tower is cooled. As a result, the sensible heat of the mixed gas is discarded as waste heat. In this configuration, since the waste heat of the mixed gas is used by the heat exchanger for the separation of carbon dioxide and nitrogen by the separator, the energy efficiency of the entire system is improved.

[0017] (3) In the chemical looping combustion system of the above aspect, in addition to supplying the fuel to the fuel tower, a gas containing oxygen may also be supplied to the fuel tower.

[0018] The reduction reaction of the metal particles in the fuel tower is an endothermic reaction or an exothermic reaction with little heat generated. With this configuration, by supplying a gas containing oxygen to the fuel tower, the supplied oxygen undergoes an oxidation reaction with the reduced metal particles, and the temperature in the fuel tower rises. As a result, the temperature in the fuel tower rises to a temperature suitable for the reduction reaction, promoting the reduction reaction. In addition, the heat of reaction between the metal particles in the fuel tower and the oxygen is directly used to increase the temperature in the fuel tower. Therefore, compared with the case of heating the fuel tower from the outside, the fuel tower can be heated with less energy.

[0019] (4) In the chemical chain combustion system of the above-mentioned method, there may also be a loop seal, which is arranged on the downstream side of the air tower and the upstream side of the fuel tower to inhibit nitrogen from flowing from the air tower into the fuel tower, and a gas containing oxygen is supplied to the loop seal.

[0020] With this configuration, a gas containing oxygen is supplied to a loop seal disposed between an air tower and a 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 inhibits nitrogen from flowing from the air tower into the loop seal, thereby inhibiting nitrogen from flowing into the fuel tower. In addition, heat is released by an oxidation reaction between the oxygen flowing from the loop seal and the reduced metal atoms. As a result, the energy used to separate N2 using a separator is reduced and the interior of the fuel tower can be heated with less energy, thereby further improving the energy efficiency of the entire system.

[0021] (5) The chemical looping combustion system of the above aspect may further include a dehydrator, wherein the dehydrator is of a variable temperature type and removes water contained in the mixed gas by utilizing the heat recovered by the heat exchanger.

[0022] With this configuration, the heat recovered by the heat exchanger can be utilized by the dehydrator in addition to the separator. Therefore, by controlling the heat utilized in each of the separator and the dehydrator, the energy efficiency of the entire system can be further improved.

[0023] (6) In the chemical looping combustion system of the above-mentioned embodiment, there may be further provided a control unit, which obtains the required heat release required by the air tower, and when obtaining the required heat release, controls the flow rate of the air as a gas containing oxygen supplied to the fuel tower, and when the required heat release is W, controls the flow rate of the air as a gas containing oxygen supplied to the fuel tower. AR (kW), the low heat value of the fuel is LHV 燃料 (kJ / mole), the heat released per 1 mole of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mole), the heat absorbed per 1 mole of the fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mole), the oxygen concentration in the air is X O2 In the case of the above, the control unit controls the flow rate of the oxygen-containing gas supplied to the fuel tower to be the flow rate Q calculated by the following formula (1): 空气_FR It is controlled in a manner that is more than 30% and less than 300%.

[0024]

[0025] With this configuration, the flow rate of oxygen-containing air supplied to the fuel tower is Q 空气_FR 30% or more and less than 300% of the total air flow. 空气_FR 300%, so the carbon dioxide concentration in the mixed gas discharged from the fuel tower can be suppressed to less than 30%. In the separator, the lower the carbon dioxide concentration in the mixed gas is, the more rapidly the energy required for separating the nitrogen increases. In this configuration, since the carbon dioxide concentration in the mixed gas is above 30%, the energy required for separation can be suppressed. In addition, in this configuration, when the flow rate of oxygen supplied to the fuel tower is too small, the effect produced by the oxidation reaction of oxygen and metal particles in the fuel tower is suppressed. However, by controlling the lower limit of the flow rate of air supplied to the fuel tower to the flow rate Q 空气_FR 30% of the reaction heat generated by the oxidation reaction in the fuel tower can be fully obtained.

[0026] (7) In the chemical looping combustion system of the above-mentioned embodiment, there may be a temperature acquisition unit for acquiring the temperature in the fuel tower, and the control unit controls the flow rate Q of the air supplied to the fuel tower according to the temperature acquired by the temperature acquisition unit. 空气_FR Take control.

[0027] With this configuration, the amount of air supplied to the fuel tower is controlled using the temperature acquired by the temperature acquisition unit. Since the temperature in the fuel tower rises due to the oxidation reaction between oxygen contained in the air and the metal particles, the temperature in the fuel tower can be controlled by controlling the flow rate of the supplied air. By controlling the temperature in 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.

[0028] (8) In the chemical looping combustion system of the above-mentioned embodiment, 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, the control unit may multiply the difference by a predetermined constant to obtain a flow rate Q 空气_FR The control unit may control the fuel tower in such a manner that the air is supplied to the fuel tower, and when the difference is negative, the control unit may control the fuel tower in such a manner that the gas containing oxygen is not supplied to the fuel tower.

[0029] With this configuration, when the temperature in 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 in the fuel tower is lower than the target temperature, the temperature in the fuel tower rises by increasing the oxygen in the air supplied to the fuel tower to react with the metal particles for oxidation. On the other hand, when the temperature in 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 in the fuel tower is reduced and the temperature in the fuel tower is lowered. That is, in this configuration, the flow rate of air supplied to the fuel tower is controlled in a manner close to the target temperature, so that the overall energy efficiency of the system can be improved based on the target temperature.

[0030] It should be noted that the present invention can be implemented in various ways, for example, it can be implemented in the form of a chemical chain combustion system, a chemical chain combustion device, a chemical chain combustion method and a system having these devices, a computer program for executing these devices, a server device for distributing the computer program, a non-temporary storage medium storing the computer program, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] [ Figure 1 ] is a schematic block diagram of a chemical chain combustion system as an embodiment of the present invention.

[0032] [ Figure 2 ] is an explanatory diagram of the CO2 adsorption amount of zeolite that changes according to the CO2 concentration in the mixed gas.

[0033] [ Figure 3 ] is a diagram illustrating the principle of chemical looping combustion.

[0034] [ Figure 4 ] is a schematic block diagram of a chemical chain combustion system of a comparative example.

[0035] [ Figure 5 ] is a schematic block diagram of a chemical chain combustion system of a second embodiment.

[0036] [ Figure 6 ] is a schematic block diagram of a chemical chain combustion system of a third embodiment.

[0037] [ Figure 7 ] is a schematic block diagram of a chemical chain combustion system of a fourth embodiment.

[0038] [ Figure 8 ] is a schematic block diagram of a chemical chain combustion system of the sixth embodiment.

[0039] [ Fig. 9 ] is a schematic block diagram of the chemical chain combustion system of the seventh embodiment.

[0040] [ Fig.10 ] is a schematic block diagram of the chemical chain combustion system of the eighth embodiment.

[0041] [ Fig.11 ] is a schematic block diagram of a chemical chain combustion system of the ninth embodiment.

[0042] [ Fig.12 ] is a flow chart for controlling the flow rate of air supplied to the fuel tower. DETAILED DESCRIPTION

[0043] <First embodiment>

[0044] Figure 1 The present invention is a schematic block diagram of a chemical loop combustion system (hereinafter also referred to as a "combustion system") 100 as an embodiment of the present invention. In the conventional chemical loop combustion system, the air tower side loop seal portion (loop seal) 60 disposed between the air tower 10 for oxidizing the metal particles mg and the fuel tower 20 for reducing the metal particles mg is used to suppress the nitrogen gas flowing from the air tower 10 to the fuel tower 20, thereby recovering high-purity carbon dioxide (CO2) from the fuel tower 20. In contrast, in the present embodiment, the greatest advantage of the combustion system 100 is that carbon dioxide does not need to be supplied to the heat utilization site, and as a secondary effect, high-purity CO2 can be obtained. That is, considering that the presence of CO2 in the air tower 10 is a problem, while the presence of nitrogen (N2) in the fuel tower 20 is not an essential problem, the overall energy efficiency of the combustion system 100 is improved.

[0045] The combustion system 100 of this embodiment allows a certain flow rate of N2 to flow from the air tower 10 into the fuel tower 20, and uses the separator 50 to separate N2 and CO2 from the mixed gas containing CO2 obtained from the fuel tower 20. The separator 50 uses the waste heat of the fuel tower 20 to separate N2 and CO2 in the mixed gas, thereby suppressing the enlargement of the air tower side loop seal part 60 and improving the overall energy efficiency of the combustion system 100.

[0046] In the combustion system 100, the metal particles mg are repeatedly oxidized in the air tower 10 and reduced in the fuel tower 20, and oxygen (O2) in the air is transported from the air tower 10 to the fuel tower 20. The metal particles mg circulate in the combustion system 100. In this embodiment, an example of using FeTiO3 as the metal particles mg is described. The particle size of the metal particles mg is greater than 50 mm and less than 250 mm. Figure 1 As shown, the combustion system 100 of the first embodiment has an air tower 10, a fuel tower 20, an air tower side loop seal portion 60, a fuel tower side loop seal portion 70, a cyclone separator 15, a heat exchanger 30, a dehydrator 40, a separator 50 and a heater 25.

[0047] The air tower 10 uses air containing O2 to cause the reaction represented by the following formula (2) to oxidize FeTiO3. The oxidation reaction of formula (2) generates heat, and the gas in the air tower 10 is heated, and the air tower 10 is heated to about 1000 degrees Celsius (°C).

[0048]

[0049] like Figure 1 As shown, the air tower 10 has a cylindrical shape extending in the vertical direction. A seal 10S is provided at the vertical lower part of the air tower 10. The seal 10S is a component with a plurality of pores. With the seal 10S, the air supplied from the vertical lower part of the air tower 10 flows into the air tower 10, and the metal particles mg are transported vertically upward. On the other hand, since the size of the hole provided in the seal 10S is smaller than the metal particles mg, the metal particles mg are prevented from leaking out of the air tower 10 through the seal 10S. It should be noted that the gas flow velocity toward the vertical upper part in the air tower 10 is set to a terminal velocity or a velocity above the terminal velocity at which gravity and the resistance generated by the air flow are balanced.

[0050] The metal particles mg oxidized in the air tower 10 flow into the cyclone separator 15 connected via a pipeline. The cyclone separator 15 separates the metal particles mg from the heated gas using centrifugal force. Figure 1As shown in FIG. 1 , the gas heated in the air tower 10 flows out from the vertical upper part of the cyclone separator 15 and is supplied to a heat utilization location. The composition of the gas supplied to the heat utilization location is mostly composed of N2, as O2 is reduced due to the oxidation of the metal particles mg in the air tower 10. Figure 1 As shown, the metal particles mg separated from the gas in the cyclone separator 15 move toward the air tower side loop seal portion 60 through the inside of a duct extending vertically downward provided in the center portion of the cyclone separator 15 .

[0051] like Figure 1 As shown, the air tower side loop seal part 60 is arranged on the downstream side of the air tower 10 and the upstream side of the fuel tower 20. A seal 60S is provided vertically below the air tower side loop seal part 60. The seal 60S is a member having a plurality of pores. The pores formed in the seal 60S are smaller than the particle size of the metal particles mg. Therefore, as shown in FIG. Figure 1 As shown, a particle layer (hatched portion) composed of a plurality of 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.

[0052] In the air tower side loop seal part 60, water vapor is supplied from vertically below the seal 60S. The supplied water vapor flows into the fuel tower 20 connected to the downstream side of the air tower side loop seal part 60 through the seal 60S. Since the water vapor is supplied to the air tower side loop seal part 60 from below the seal 60S, the Figure 1 The gas containing N2 as the main component, the flow direction of which is indicated by arrows in FIG. 2 , flows into the fuel tower 20 through the particle layer. Figure 1 As shown, a portion of the gas containing N 2 flows into the fuel tower 20 together with the metal particles mg through the air tower side loop seal portion 60 .

[0053] A fluidized bed flowing from the air tower side loop seal unit 60 to the fuel tower 20 is arranged in the pipe connecting the air tower side loop seal unit 60 and the fuel tower 20. The metal particles mg discharged from the cylindrical air tower side loop seal unit 60 move to the fuel tower 20 due to the flow of the fluidized bed.

[0054] Methane (CH4) is supplied as fuel to the fuel tower 20, and oxidized metal particles mg and gas containing N2 are supplied from the air tower 10. The fuel tower 20 reduces the metal particles mg using methane and discharges a mixed gas containing CO2. Figure 1As shown, the fuel tower 20 has a cylindrical shape extending in the vertical direction. A seal 20S is provided vertically below the fuel tower 20. The seal 20S is a component with a plurality of pores. In the fuel tower 20, gas fuel is supplied from below the seal 20S. It should be noted that the gas flow rate in the fuel tower 20 is set to a speed slower than the terminal speed, and is controlled so that the metal particles mg do not fly out from the top of the fuel tower 20.

[0055] In the fuel tower 20 supplied with CH4 as fuel, 4Fe2TiO5, which is the metal particle 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.

[0056]

[0057] When 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) are taken as the sum, the reaction carried out in the air tower 10 and the fuel tower 20 is the same reaction as the combustion of methane as a fuel represented by the following formula (4). That is, the total amount of heat obtained in the combustion system 100 (the sum of the heat released by the air tower 10 and the heat absorbed by the fuel tower 20) is the same as the combustion of CH4 as a fuel.

[0058]

[0059] like Figure 1 As shown, the mixed gas containing CO2 generated by the reduction reaction in the fuel tower 20 flows out from the vertical upper part of the fuel tower 20 and is sent to the heat exchanger 30. It should be noted that the details of the mixed gas supplied to the heat exchanger 30 will be described later. Figure 1 As shown, the metal particles mg reduced by the reduction reaction in the fuel tower 20 move toward the fuel tower side loop seal portion 70 through the inside of the pipe extending vertically downward provided in the central portion of the fuel tower 20 .

[0060] The heater 25 is mounted on the cylindrical outer wall of the fuel tower 20. The heater 25 heats the inside of the fuel tower 20 by raising the temperature using the power supplied from the external power supply. Since the reduction reaction represented by the above formula (3) is an endothermic reaction, the heater 25 raises the temperature of the inside of the fuel tower 20 which has been cooled by the endothermic reaction.

[0061] The fuel tower side loop seal part 70 to which metal particles mg are supplied from the fuel tower 20 is arranged on the downstream side of the fuel tower 20 and the upstream side of the air tower 10. The fuel tower side loop seal part 70 has the same structure as the air tower side loop seal part 60. A seal 70S is provided vertically below the fuel tower side loop seal part 70. The seal 70S is a member having a plurality of pores. In the fuel tower side loop seal part 70, water vapor is supplied from the vertically below the seal 70S. The supplied water vapor flows into the air tower 10 connected to the downstream side of the fuel tower side loop seal part 70 through the seal 70S. A fluidized bed flowing from the fuel tower side loop seal part 70 to the air tower 10 is arranged in the pipeline connecting the fuel tower side loop seal part 70 and the air tower 10. The metal particles mg in the cylindrical fuel tower side loop seal part 70 move to the air tower 10 through the flow of the fluidized bed. As described above, the metal particles mg are oxidized in the air tower 10 , reduced in the fuel tower 20 , and circulate between the air tower 10 and the fuel tower 20 .

[0062] The mixed gas discharged from the vertical upper part of the fuel tower 20 contains CO2 and water vapor (H2O) generated by the reduction reaction shown in the above formula (3) and N2 flowing into the fuel tower 20 through the air tower side loop seal part 60. The fuel tower 20 of this embodiment is controlled to about 1000°C by the heater 25 to promote the reduction reaction. Therefore, the mixed gas discharged from the fuel tower 20 is a high temperature of about 1000°C.

[0063] like Figure 1 As shown, the mixed gas discharged from the fuel tower 20 is supplied to the heat exchanger 30 for recovering heat. The heat exchanger 30 recovers the 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, the mixed gas is deheated by the heat exchanger 30.

[0064] The mixed gas from which heat is recovered by the heat exchanger 30 is supplied to the dehydrator 40. The dehydrator 40 removes H2O contained in the mixed gas from which heat is recovered by the heat exchanger 30. Figure 1 As shown, the mixed gas discharged from the dehydrator 40 contains CO 2 and N 2 from which H 2 O has been removed.

[0065] The mixed gas discharged from the dehydrator 40 is supplied to the separator 50. The separator 50 is a temperature-variable separator that uses the heat recovered by the heat exchanger 30 to separate CO2 and N2 contained in the mixed gas from which H2O has been removed, and to remove CO2. The separator 50 is composed of a plurality of shell-and-tube adsorption towers. The tube side of each shell-and-tube adsorption tower is filled with zeolite that can adsorb and desorb CO2. When adsorbing CO2, the zeolite is cooled with water at about 25°C, and when desorbing CO2, the heat recovered by the heat exchanger 30 is used for heating. The separator 50 is controlled by dividing a plurality of adsorption towers into an adsorption tower for adsorption and an adsorption tower for desorption, so that CO2 and N2 can be separated continuously. It should be noted that the zeolite not only adsorbs CO2, but also adsorbs H2O, so the dehydrator 40 is arranged on the upstream side of the separator 50.

[0066] The mixed gas discharged from the separator 50 from which N2 is separated is high-purity CO2. This high-temperature gas is sent to a CO2 utilization site. The CO2 utilization site may be, for example, a tank that stores CO2 in a liquefied or high-pressure state.

[0067] Figure 2 This is a diagram illustrating the CO2 adsorption amount of zeolite that changes according to the CO2 concentration in the mixed gas. Figure 2 2 shows the change in the amount of CO 2 adsorbed per gram unit of the 13-type zeolite according to the CO 2 concentration in the mixed gas as a curve C1. Figure 2 The horizontal axis is the concentration of the mixed gas flowing into the inlet of the separator 50, and the vertical axis is the amount (mmol) adsorbed per 1 gram of zeolite. Figure 2 In FIG. 1 , for comparison, the change in the amount of CH4 adsorbed by the zeolite according to the CH4 concentration in the mixed gas is shown in the form of curve C2. Figure 2 In FIG. 1 , for comparison, a curve C3 shows a change in the amount of N 2 adsorbed by the zeolite according to the N 2 concentration in the mixed gas.

[0068] like Figure 2 As shown, the higher the concentration of CO2, CH4, and N2 in the mixed gas, the more the adsorption amount of zeolite increases. The CO2 adsorption amount at the same inlet concentration is much greater than either the CH4 adsorption amount and the N2 adsorption amount. The CH4 adsorption amount and the N2 adsorption amount increase linearly with the increase of the inlet concentration. On the other hand, the CO2 adsorption amount represented by the curve C1 gradually decreases from 100% as the inlet concentration decreases, and decreases almost linearly to an inlet concentration of about 30%. When the inlet concentration is less than 30%, the reduction in the adsorption amount of CO2 is greatly reduced relative to the reduction in the inlet concentration. It is therefore believed that as long as the CO2 concentration in the mixed gas supplied to the separator 50 is not as small as less than 30%, it is fully adsorbed by the zeolite.

[0069] Figure 3 This is a diagram illustrating the principle of chemical looping combustion. Figure 3 A schematic block diagram of a fuel system 100x of a comparative example is shown in FIG. The fuel system 100x of the comparative example includes an air tower 10 for oxidizing metal particles, a fuel tower 20 for reducing oxidized metal particles, and a dehydrator 40 for removing H2O from the mixed gas supplied from the fuel tower 20. Figure 3 In , the metal atom (or molecule) used as the metal particle mg is represented by Me.

[0070] In the air tower 10, air is supplied, and the reaction heat generated by the oxidation reaction of the metal particles mg is supplied to a heat utilization site in the form of high-temperature N2 that does not contain CO2. In the fuel tower 20, the oxidized metal particles mg are reduced by a fuel such as CH4, and a mixed gas containing CO2 generated by the reduction reaction is supplied to the dehydrator 40. In the dehydrator 40, H2O in the mixed gas is removed, and the mixed gas containing high-purity CO2 is supplied to a CO2 utilization site.

[0071] <Comparative Example>

[0072] Figure 4 FIG. 1 is a schematic block diagram of a chemical looping combustion system (combustion system) 100x of a comparative example. Figure 1 Compared to the combustion system 100 shown, Figure 4 The combustion system 100x of the comparative example shown 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 portion 60x that is larger than the air tower side loop seal portion 60 of the embodiment.

[0073] In the combustion system 100x of the comparative example, since N2 in the mixed gas discharged from the fuel tower 20 is not separated by the separator 50, it is necessary to suppress the inflow of N2 into the fuel tower 20. Therefore, the air tower side loop seal part 60x of the comparative example is enlarged. Since the air tower side loop seal part 60x is enlarged, the particle layer formed by a plurality of metal particles mg in the air tower side loop seal part 60x is increased. As a result, the enlarged particle layer can suppress the inflow of N2 into the fuel tower 20. However, due to the increase in the particle layer, the time required for the metal particles mg discharged from the cyclone separator 15 to flow into the fuel tower 20 becomes longer. Therefore, the temperature of the metal particles mg heated by the oxidation reaction of the air tower 10 is reduced before flowing into the fuel tower 20. In the fuel tower 20, it is necessary to supplement the temperature effect of the metal particles mg by heating by the heater 25, etc. In order to reduce the energy used for heating by the heater 25, the air tower side loop seal portion 60x is preferably miniaturized and the particle layer formed in the air tower side loop seal portion 60x is small.

[0074] In contrast, the combustion system 100 of the present embodiment has a separator 50 for separating CO 2 and N 2 contained in the mixed gas and removing CO 2. Figure 1 As shown, the heat generated by the oxidation reaction of the metal particles mg in the air tower 10 is supplied to the heat utilization place via N2 that does not contain CO2. Since CO2 is not contained in the gas supplied with heat, it is possible to suppress the mixing of CO2 with impurities specific to the heat supply object, and it is possible to suppress the situation where carbon dioxide cannot be recovered from the supply object. In addition, in this embodiment, since N2 in the mixed gas discharged from the fuel tower 20 is separated by the separator 50, high-purity CO2 can be recovered even if nitrogen flows into the fuel tower 20. Since N2 in the mixed gas is separated by the separator 50, it is not necessary to enlarge the air tower side loop seal part 60x as in the fuel system 100x of the comparative example. As a result, the time that the metal particles mg are retained in the air tower side loop seal part 60 can be shortened, and the heat dissipation loss during the movement of the metal particles mg from the air tower 10 to the fuel tower 20 can be suppressed. Therefore, the overall energy efficiency of the combustion system 100 of this embodiment can be improved. The combustion system 100 of the present embodiment is a system derived from the following concept, that is, it is considered that the greatest advantage of the chemical looping combustion system is that CO2 does not need to be supplied to the heat supply object, and the flow of CO2 into the air tower 10 is a problem, but the flow of N2 into the fuel tower 20 itself is not a problem. The combustion system 100 of the present embodiment not only has the separator 50 for separating N2, but also allows N2 to flow into the fuel tower 20, which can improve the overall energy efficiency of the combustion system 100.

[0075] In addition, the heat exchanger 30 of the present embodiment recovers the heat generated in the fuel tower 20 via the mixed gas supplied from the fuel tower 20. The separator 50 separates CO2 and N2 contained in the mixed gas using the heat recovered by the heat exchanger 30, and takes out CO2. In the fuel system 100x of the comparative example, the heat of the high-temperature mixed gas is discarded in order to remove H2O, but in the present embodiment, the waste heat of the mixed gas is used for N2 separation in the separator 50 using the heat exchanger 30. As a result, the overall energy efficiency of the combustion system 100 of the present embodiment can be improved.

[0076] <Second embodiment>

[0077] Figure 5 1 is a schematic block diagram of a chemical loop combustion system (combustion system) 100a of the second embodiment. Compared with the combustion system 100 of the first embodiment, the fuel system 100a of the second embodiment is different in that air as a gas containing O2 is supplied to the fuel tower 20a in addition to the fuel CH4. In the second embodiment, the configurations different from the first embodiment are described, and the description of the same configurations is omitted.

[0078] In the second embodiment, air is supplied from below the seal 20S of the fuel tower 20a together with CH4. When the air is supplied, heat is released by the oxidation reaction between O2 contained in the air and the metal particles mg reduced by the fuel CH4. N2 contained in the air supplied to the fuel tower 20a is separated from CO2 by the separator 50 in the same manner as N2 flowing into the fuel tower 20a from the air tower 10.

[0079] As described above, in the combustion system 100a of the second embodiment, in addition to supplying the fuel CH4 to the fuel tower 20a, air as a gas containing oxygen is also supplied. The reduction reaction of the metal particles mg in the fuel tower 20a and CH4 is an endothermic reaction. According to the combustion system 100a of this embodiment, by supplying air containing O2 to the fuel tower 20a, the O2 in the supplied air and the reduced metal particles mg undergo an oxidation reaction, and the temperature in the fuel tower 20a rises. As a result, the temperature in the fuel tower 20a rises to a temperature suitable for the reduction reaction, promoting the reduction reaction. In addition, the heat of reaction between the metal particles mg in the fuel tower 20a and O2 is directly used for heating the fuel tower 20a. Therefore, compared with the case where the fuel tower 20a is heated by the heater 25, the fuel tower 20a can be heated with less energy.

[0080] <Third Embodiment>

[0081] Figure 6 1 is a schematic block diagram of a chemical loop combustion system (combustion system) 100b of the third embodiment. Compared with the combustion system 100 of the first embodiment, the fuel system 100b of the third embodiment is different in that air as a gas containing O2 is supplied to the air tower side loop seal part 60b. In the third embodiment, the configuration different from the first embodiment is described, and the description of the same configuration is omitted.

[0082] In the third embodiment, air is supplied together with water vapor from below the seal 60S of the air tower side loop seal part 60b. When air is supplied to the air tower side loop seal part 60b, a part of the air flows into the fuel tower 20, and the remaining air flows into the cyclone separator 15. O2 in the air flowing into the fuel tower 20 reacts with the reduced metal particles mg in the fuel tower 20, similarly to O2 in the air supplied to the fuel tower 20a in the second embodiment. The temperature in the fuel tower 20 rises due to the heat release of the oxidation reaction of O2 and the metal particles mg. In addition, the air supplied from below the seal 60S suppresses N2 from flowing into the air tower side loop seal part 60b from the air tower 10, similarly to water vapor, and thus suppresses N2 from flowing into the fuel tower 20. As a result, the water vapor flow rate required here can be reduced, and the energy required for water vapor generation (energy for heating water) can be reduced.

[0083] As described above, in the combustion system 100b of the third embodiment, air as a gas containing O2 is supplied to the air tower side loop seal part 60b. In the third embodiment, air containing O2 is supplied to the air tower side loop seal part 60b disposed between the air tower 10 and the fuel tower 20. The air supplied to the air tower side loop seal part 60b flows into both the air tower 10 and the fuel tower 20. As a result, since the air flowing into the air tower 10 suppresses N2 from flowing into the air tower side loop seal part 60b from the air tower 10, it is possible to suppress N2 from flowing into the fuel tower 20 with a smaller water vapor flow rate. In addition, the oxygen flowing into the fuel tower 20 from the air tower side loop seal part 60b releases heat by oxidation reaction with the reduced metal particles mg. As a result, the energy used to separate N2 using the separator 50 is reduced, and the energy required to generate water vapor is reduced, and the fuel tower 20 can be heated with less energy, so the overall energy efficiency of the combustion system 100b can be further improved.

[0084] <Fourth embodiment>

[0085] Figure 7 This is a schematic block diagram of a chemical chain combustion system (combustion system) 100c of the fourth embodiment. Compared with the combustion system 100a of the second embodiment, the fuel system 100c of the fourth embodiment is different in that it does not have a heater 25, the heat recovered by the heat exchanger 30 is used by the dehydrator 40c and the separator 50c, and the flow rate of air and fuel supplied to the fuel tower 20a is controlled. In the fourth embodiment, by controlling the flow rate of air and fuel supplied to the fuel tower 20a, the heat released by the oxidation reaction of the metal particles mg in the fuel tower 20a is supplemented by the heating part generated by the heater 25. It should be noted that in the fourth embodiment, the configuration different from the second embodiment is described, and the description of the same configuration is omitted.

[0086] The combustion system 100c of the fourth embodiment has a control unit 80 for controlling the flow rates of air and CH4 as fuel supplied to the fuel tower 20a. The control unit 80 is composed of a well-known device such as a mass flow controller. The control unit 80 supplements the heat to be supplemented by the heating part of the fuel tower 20a generated by an external heat source such as a heater 25 by the heat generated by the oxidation reaction of the metal particles mg in the fuel tower 20a.

[0087] Here, it is assumed that 1 kW of heat release is continuously obtained in the air tower 10. In this case, it is necessary to reduce the metal particles mg at a flow rate of 1.5 slm of CH4 in the fuel tower 20. The heat absorption generated by the reduction reaction at this flow rate is 0.116 kW. In order to supplement this heat absorption by reoxidation of the metal particles mg in the fuel tower 20a, an air flow rate of 1.9 slm and a CH4 flow rate of 0.2 slm are required. As for the specific heat release in the fuel tower 20a, the heat release generated by the air flow rate of 1.9 slm is 0.132 kW, and the heat absorption generated by the CH4 flow rate of 0.2 slm is 0.016 kW, which offsets the heat release of 0.116 kW. When the fuel tower 20a is supplied with an air flow rate of 1.9 slm and a CH4 flow rate of 0.2 slm, the composition of the mixed gas after removing H2O supplied to the separator 50c is composed of 53% CO2 and 47% N2. Figure 2 As shown in the curve C1 of the CO2 adsorption amount of the zeolite, even if the inlet concentration of CO2 in the mixed gas is 53%, the zeolite can fully adsorb CO2 in the mixed gas. That is, even if the fuel tower 20a is not heated by the heater 25, the temperature in the fuel tower 20a can be controlled to a temperature at which a reduction reaction occurs by utilizing the reoxidation of the reduced metal particles mg in the fuel tower 20a.

[0088] The dehydrator 40c of the fourth embodiment is a temperature-variable dehydrator. The separator 50c of the fourth embodiment is a temperature-variable separator. The dehydrator 40c of the fourth embodiment removes H2O in the mixed gas by using the heat of the mixed gas recovered by the heat exchanger 30.

[0089] As described above, in the fourth embodiment, the heater 25 for heating the fuel tower 20a is not required, and 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. 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.

[0090] <Fifth embodiment>

[0091] The chemical looping combustion system of the fifth embodiment has the same configuration as the fuel system 100c of the fourth embodiment, except for the control contents of the control unit 80. Therefore, in the fifth embodiment, the control contents of the control unit 80 that are different from the fourth embodiment are described, and descriptions of other configurations are omitted.

[0092] The control unit 80 of the fifth embodiment obtains the required heat generation required for the heat utilization, that is, the heat generation W of the oxidation reaction of the metal particles mg in the air tower 10.AR (kW), according to the heat release W AR Calculate the flow rate Q of air containing O2 空气_FR (slm) and the flow rate Q of CH4 as fuel 燃料_添加_AR The control unit 80 calculates the air flow rate Q 空气_FR and the fuel flow rate Q 燃料_添加_AR The flow rates of 30% or more and 300% or less of each are controlled so as to be supplied to the fuel tower 20a.

[0093] Air flow rate Q 空气_FR and the fuel flow rate Q 燃料_添加_AR It is represented by the following formula (1) and (5). It should be noted that in the following formula (1) and (5), the heat release LHV 燃料 (kJ / mole), heat release Δh AR (kJ / mol), endothermic heat Δh FR (kJ / mole), oxygen concentration X O2 and the molar amount b (mol / mol) are each defined as described below.

[0094]

[0095]

[0096] LHV 燃料 : Heat released per 1 mol of fuel (kJ / mol)

[0097] Δh AR : Heat released by oxidation reaction per 1 mol of O2 in the air tower 10 (kJ / mol)

[0098] Δh FR : The heat absorption of the reduction reaction per 1 mol of fuel in the fuel tower 20a (kJ / mol)

[0099] X O2 : Oxygen concentration in the air

[0100] b: The amount of O2 required for complete combustion of 1 mole of fuel (mol / mol)

[0101] 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 空气_FR When the fuel is CH4, the air flow rate Q 空气_FR The upper limit of is 300%, so it is possible to suppress the CO2 in the mixed gas discharged from the fuel tower 20 to be less than 30%. For the zeolite used in the separator 50c, such as Figure 2As shown, the more CO2 in the mixed gas decreases from less than 30%, the more energy required to separate N2 increases sharply. In this embodiment, since CO2 in the mixed gas is more than 30%, the energy required for separation can be suppressed. In addition, when the flow rate of O2 supplied to the fuel tower 20 is too small, the effect produced by the oxidation reaction of O2 and metal particles mg in the fuel tower 20 is suppressed. However, by controlling the lower limit of the flow rate of air supplied to the fuel tower 20 to the flow rate Q 空气_FR 30% of the total heat generated by the oxidation reaction in the fuel tower 20 can be fully obtained.

[0102] <Sixth embodiment>

[0103] Figure 8 1 is a schematic block diagram of a chemical looping combustion system (combustion system) 100d of the sixth embodiment. Compared with the combustion system 100c of the fourth embodiment, the fuel system 100d of the sixth embodiment is different in that it has a heat exchanger 35 and a vacuum pump 55. In the sixth embodiment, the configurations different from the fourth embodiment are described, and the description of the same configurations is omitted.

[0104] like Figure 8 As shown in FIG. 1 , the fuel system 100d of the sixth embodiment includes a heat exchanger 35 for recovering heat from high-temperature N2 discharged from the cyclone separator 15 and a vacuum pump 55 disposed on the downstream side of the separator 50c. In this embodiment, when the heat recovered from the mixed gas by the heat exchanger 30 supplied with the mixed gas from the fuel tower 20a does not meet the energy required for the operation of the dehydrator 40c and the separator 50c, the heat exchanger 35 recovers a part of the heat supplied to the heat utilization site and supplies it to at least one of the dehydrator 40c and the separator 50c. When the desorption rate of the zeolite in the desorption in the separator 50c is insufficient, the desorption rate is increased by using the pressure change and temperature change by the vacuum pump 55.

[0105] As described above, in the combustion system 100d of the sixth embodiment, a part of the heat supplied to the heat utilization location is recovered and utilized by the heat exchanger 35, and N2 and CO2 are separated by pressure change using the vacuum pump 55. As a result, the overall energy efficiency of the combustion system 100d is improved. It should be noted that the fuel system of other embodiments may not have either the heat exchanger 35 or the vacuum pump 55.

[0106] <Seventh embodiment>

[0107] Fig. 91 is a schematic block diagram of a chemical loop combustion system (combustion system) 100e of the seventh embodiment. Compared with the combustion system 100d of the sixth embodiment, the fuel system 100e of the seventh embodiment is different in that it does not have a heat exchanger 35, and the dehydrator 40e and the separator 50e are of variable pressure type. Since the dehydrator 40e is of variable pressure type, the combustion system 100e has a vacuum pump 45 connected to the dehydrator 40e. In the seventh embodiment, the configuration different from the sixth embodiment is described, and the description of the same configuration is omitted.

[0108] The dehydrator 40e of the seventh embodiment removes H2O from the mixed gas by utilizing the pressure change type generated by the vacuum pump 45 operated by energy supplied from the outside. The separator 50e is a pressure change type, which is different from the separator using both the temperature change type and the pressure change type in the sixth embodiment. The heat exchanger 30e of the seventh embodiment recovers the heat of the mixed gas supplied from the fuel tower 20a and discards it as waste heat to the outside of the combustion system 100e.

[0109] As described above, even in the combustion system 100e of the seventh embodiment, if the energy loss of the sensible heat portion of the mixed gas discharged from the fuel tower 20a is smaller than the heat dissipation loss caused by the enlargement of the air tower side loop seal part 60 and the energy loss caused by the heating of the heater 25, the overall energy efficiency of the combustion system 100e can be improved.

[0110] <Eighth Embodiment>

[0111] Fig.10 1 is a schematic block diagram of a chemical looping combustion system (combustion system) 100f of the eighth embodiment. Compared with the combustion system 100e of the seventh embodiment, the fuel system 100f of the eighth embodiment is different in that a heater 25 is provided and only fuel is supplied to the fuel tower 20 without supplying air. In the eighth embodiment, the configurations different from the seventh embodiment are described, and the description of the same configurations is omitted.

[0112] Since the air containing O2 is not supplied to the fuel tower 20 of the eighth embodiment, the reoxidation reaction of the reduced metal particles mg does not occur in the fuel tower 20. Instead, the fuel tower 20 is heated by the heater 25 heated by external energy. Even in the combustion system 100f of the eighth embodiment, if the total of the energy loss of the sensible heat part of the mixed gas discharged from the fuel tower 20a and the energy required for heating by the heater 25 is less than the heat dissipation loss caused by the enlargement of the air tower side loop seal part 60, the energy efficiency of the combustion system 100f as a whole can be improved.

[0113] <Ninth embodiment>

[0114] Fig.11 FIG. 1 is a schematic block diagram of a chemical looping combustion system (combustion system) 100g of a ninth embodiment. Figure 7 ), the chemical looping combustion system of the ninth embodiment is different in that it has a temperature sensor (temperature acquisition unit) 90 for detecting the temperature in the fuel tower 20a, and the control content of the control unit 80g is different. Therefore, in the ninth embodiment, the configuration and control content that are different from the fourth embodiment are described, and the description of other configurations and the like is omitted.

[0115] The control unit 80g of the ninth embodiment controls the flow rate Q of the air supplied to the fuel tower 20a according to the temperature acquired by the temperature sensor 90. 空气_FR Specifically, the target temperature in the fuel tower 20a is T 目标 In the case of 目标 The air flow rate Q is controlled by subtracting the temperature difference ΔT obtained by the temperature T1 detected by the temperature sensor 90. 空气_FR When the temperature difference ΔT is equal to or greater than zero, the flow rate Q expressed by the following equation (6) is 空气_FR The air is supplied to the fuel tower 20a. It should be noted that k in the following formula (6) is a preset proportional constant.

[0116]

[0117] 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. 空气_FR 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.

[0118] Fig.12 is the flow rate Q of air supplied to the fuel tower 20a 空气_FR Flow chart for control. Fig.12 In the control flow shown in FIG. 1 , the control unit 80g sets the preset initial flow rate Q 空气_0 The air is supplied to the fuel tower 20 (step S1). The control unit 80g obtains the detected temperature T1 in the fuel tower 20a detected by the temperature sensor 90 (step S2). The control unit 80g determines whether the target temperature T 目标 Whether the temperature difference ΔT obtained by subtracting the detected temperature T1 is equal to or greater than zero (step S3 ) or not, if it is determined that the temperature difference ΔT is less than zero (step S3 : No), the processing after step S2 is repeated.

[0119] When it is determined that the temperature difference ΔT is equal to or greater than zero (step S3: Yes), the control unit 80g supplies the liquid at the flow rate Q calculated in the above formula (6).空气_FR The supply flow rate to the fuel tower 20a is controlled in the manner of air (step S4). Then, it is determined whether to terminate the control of the chemical chain combustion system (step S5). The termination judgment of the control is performed, for example, by receiving an input of termination control from the outside. When it is determined that the control is not terminated (step S5: No), the processing after step S2 is repeated. When it is determined that the control is terminated (step S5: Yes), the control of the chemical chain combustion system is terminated. It should be noted that the termination judgment of the control can be performed during the Fig.12 The judgment is made during any of the processes shown.

[0120] 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 according to the temperature acquired by the temperature sensor 90. 空气_FR In the fuel tower 20a, the temperature in the fuel tower 20a rises due to the oxidation reaction between O2 contained in the air and the metal particles mg. Therefore, by controlling the flow rate Q of the supplied air 空气_FR By controlling the temperature in the fuel tower 20a, the temperature in the fuel tower 20a can be controlled. 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.

[0121] In addition, when the target temperature T in the fuel tower 20a is 目标 When the temperature difference ΔT obtained by subtracting the temperature T1 detected by the temperature sensor 90 is equal to or greater than zero, the control unit 80g of the ninth embodiment controls the flow rate Q expressed by the following equation (1): 空气_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. 空气_FR According to the combustion system 100g of the present embodiment, the detected temperature T1 in the fuel tower 20a is lower than the target temperature T 目标 In the case of 空气_FR As a result, when the detected temperature T1 is lower than the target temperature T 目标 In the case of increasing the amount of O2 in the air supplied to the fuel tower 20a, the metal particles mg undergo an oxidation reaction, and the temperature in the fuel tower 20a rises. On the other hand, when the detected temperature T1 is higher than the target temperature T 目标 In the case of the above, the air supply to the fuel tower 20a is stopped. As a result, the oxidation reaction in the fuel tower 20a is reduced, and the temperature in the fuel tower 20a is lowered. That is, in the combustion system 100g of the present embodiment, the temperature is kept close to the target temperature T 目标 The flow rate Q of the air supplied to the fuel tower 20a is 空气_FRThe target temperature T 目标 As a benchmark, improve the overall energy efficiency of the combustion system 100g.

[0122] <Modification of the embodiment>

[0123] The present invention is not limited to the above-mentioned embodiments, and can be implemented in various ways without departing from the scope of the present invention, and can also be modified as follows. In addition, in the above-mentioned embodiments, part of the structure implemented by hardware can be replaced by software, and conversely, part of the structure implemented by software can be replaced by hardware.

[0124] In the first to ninth embodiments, an example of a chemical looping combustion system is described, but the chemical looping combustion system can be modified within the range of having the air tower 10, the fuel tower 20, and the separator 50. For example, the combustion system 100 may not have the air tower side loop seal part 60 and the fuel tower side loop seal part 70. The air tower 10 and the air tower side loop seal part 60b ( Figure 6 ) and fuel tower 20a( Figure 5 The oxygen-containing gas of the present invention may be a gas other than air as long as it contains oxygen. When a gas other than air is supplied, the oxygen concentration X shown in the above formula (1) may be appropriately changed. O2 , calculated as the flow rate Q 空气_FR The air tower 10 may also be referred to as an oxidation tower to which the metal particles mg are oxidized by the supply of the gas containing oxygen. The heat supplied to the separator 50 may not be supplied by the heat exchanger 30 ( Figure 8 ) is not the heat recovered from the mixed gas discharged from the fuel tower 20a, but may be only the heat recovered by the heat exchanger 35 from the high-temperature N2 gas discharged from the cyclone separator 15.

[0125] The metal particles mg circulating in the combustion system 100 may be made of a known material other than FeTiO3. Similarly, the fuel supplied to the fuel tower 20 may be made of a known material other than CH4, such as C2H6, C3H8, etc. For example, nickel (Ni) or copper (Cu) may be used as the metal particles mg, and C2H6 may be used as the fuel. In this case, the reduction reaction occurring in the fuel tower 20 is as shown in the following equations (7) and (8).

[0126]

[0127]

[0128] In addition, as the zeolite material capable of adsorbing and desorbing CO 2 filled in the separator 50, other known materials such as activated carbon may be used. The flow rate Q represented by the formula (1) in the fifth embodiment is 空气_FR The air can be varied within the range of oxygen-containing gases. Similarly, the flow rate Q shown in the above formula (5) 燃料_添加_AR The fuel can be changed within the range of the fuel capable of reducing the metal particles mg in the fuel tower 20. The parameters in the above formulas (1) and (5) can be changed according to the oxygen-containing gas and the fuel.

[0129] The combustion system 100 of the first embodiment has the dehydrator 40, but the combustion systems of other embodiments may not have the dehydrator 40. In the first embodiment, the zeolite of the separator 50 also adsorbs H2O, so the dehydrator 40 is arranged on the upstream side of the separator 50. However, for example, if the separator 50 is composed of an adsorbent that does not adsorb H2O but can separate CO2 and N2, the combustion system may not have the dehydrator 40. In addition, by increasing the amount of zeolite of the separator 50, the zeolite can adsorb H2O in addition to adsorbing CO2.

[0130] The present invention has been described above based on the embodiments and variations, but the embodiments of the above-mentioned embodiments are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be changed or improved without departing from the gist and claims, and its equivalents are included in the present invention. In addition, if its technical features are not described as essential features in this specification, they may be appropriately deleted.

[0131] The present invention can also be implemented as the following aspects.

[0132] [Application Example 1]

[0133] A chemical looping combustion system having:

[0134] an air tower that uses air to oxidize the metal particles;

[0135] a fuel tower in which hydrocarbon is supplied as a fuel, and oxidized metal particles and a gas containing nitrogen are supplied from the air tower, the metal particles are reduced by the fuel and a mixed gas containing carbon dioxide is discharged; and

[0136] A separator is provided in which the carbon dioxide contained in the mixed gas is separated from the nitrogen and the carbon dioxide is taken out.

[0137] [Application Example 2]

[0138] The chemical looping combustion system as described in Application Example 1 further comprises a heat exchanger, the heat exchanger is supplied with the mixed gas discharged from the fuel tower, and recovers heat generated in the fuel tower via the mixed gas.

[0139] The separator separates carbon dioxide and nitrogen contained in the mixed gas using heat recovered by the heat exchanger.

[0140] [Application Example 3]

[0141] In the chemical looping combustion system as described in Application Example 1 or Application Example 2, in addition to supplying the fuel to the fuel tower, a gas containing oxygen is also supplied to the fuel tower.

[0142] [Application Example 4]

[0143] A chemical chain combustion system as described in any one of Application Examples 1 to Application Examples 3, which also has a loop seal, wherein the loop seal is arranged on the downstream side of the air tower and the upstream side of the fuel tower, suppressing nitrogen from flowing from the air tower into the fuel tower, and a gas containing oxygen is supplied to the loop seal.

[0144] [Application Example 5]

[0145] The chemical looping combustion system as described in any one of Application Examples 1 to 4 further comprises a dehydrator, wherein the dehydrator is of a variable temperature type and utilizes the heat recovered by the heat exchanger to remove water contained in the mixed gas.

[0146] [Application Example 6]

[0147] A chemical chain combustion system as described in any one of Application Example 1 and Application Example 5, wherein the control unit further comprises a control unit, wherein the control unit obtains the required heat release required by the air tower, and when obtaining the required heat release, controls the flow rate of air as a gas containing oxygen supplied to the fuel tower,

[0148] The required heat release is W AR (kW), the low heat value of the fuel is LHV 燃料 (kJ / mole), the heat released per 1 mole of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mole), the heat absorbed per 1 mole of the fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mole), the oxygen concentration in the air is X O2 In the case of the above, the control unit controls the flow rate of the oxygen-containing gas supplied to the fuel tower to be the flow rate Q calculated by the following formula (1): 空气_FR It is controlled in a manner that is more than 30% and less than 300%.

[0149]

[0150] [Application Example 7]

[0151] The chemical looping combustion system as described in any one of Application Example 1 and Application Example 6, further comprising a temperature acquisition unit for acquiring the temperature in the fuel tower,

[0152] The control unit controls the flow rate Q of the air supplied to the fuel tower according to the temperature acquired by the temperature acquisition unit. 空气_FR Take control.

[0153] [Application Example 8]

[0154] A chemical looping combustion system as described in any one of Application Example 1 or Application Example 7, wherein:

[0155] 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, the control unit controls the flow rate Q obtained by multiplying the difference by a preset constant. 空气_FR The way in which air is supplied to the fuel tower is controlled,

[0156] When the difference is negative, the control unit performs control so as not to supply the oxygen-containing gas to the fuel tower.

[0157] Explanation of symbols

[0158] 10…Air Tower

[0159] 10S…Seals

[0160] 15…Cyclone separator

[0161] 20, 20a…Fuel tower

[0162] 20S…Seals

[0163] 25…Heater

[0164] 30, 30e, 35…Heat exchanger

[0165] 40, 40c, 40e…Dehydrator

[0166] 45, 55…Vacuum pump

[0167] 50, 50c, 50e…separator

[0168] 60, 60b, 60x…Air tower side loop seal

[0169] 60S...Seals

[0170] 70…Fuel tower side loop seal

[0171] 70S…Seals

[0172] 80, 80g…control unit

[0173] 90…Temperature sensor

[0174] 100, 100a, 100b, 100c, 100d, 100e, 100f, 100g, 100x… fuel system

[0175] b…the amount of O2 required to completely burn 1 mole of fuel

[0176] C1, C2, C3...CO2 adsorption curve

[0177] LHV 燃料 ...heat release per 1 mole of fuel

[0178] mg…metal particles

[0179] Q 空气_FR ...air flow

[0180] Q 空气_0 ...initial flow of air

[0181] Q 燃料_添加_AR …the flow rate of fuel

[0182] ΔT…Temperature difference

[0183] T1…Detection temperature

[0184] T 目标 ...target temperature

[0185] W AR ...heat release during oxidation reaction

[0186] X O2 …oxygen concentration

[0187] Δh AR ...heat released by oxidation reaction per 1 mol of O2

[0188] Δh FR ...heat absorption of the reduction reaction per 1 mole of fuel

Claims

1. A chemical looping combustion system having: an air tower that uses air to oxidize the metal particles; a fuel tower in which hydrocarbon is supplied as a fuel, and oxidized metal particles and a gas containing nitrogen are supplied from the air tower, the metal particles are reduced by the fuel and a mixed gas containing carbon dioxide is discharged; and A separator is provided in which the carbon dioxide contained in the mixed gas is separated from the nitrogen and the carbon dioxide is taken out.

2. The chemical looping combustion system according to claim 1, wherein: A heat exchanger is further provided, the heat exchanger is supplied with the mixed gas discharged from the fuel tower, and recovers heat generated in the fuel tower via the mixed gas. The separator separates carbon dioxide and nitrogen contained in the mixed gas using heat recovered by the heat exchanger.

3. The chemical looping combustion system according to claim 2, wherein: In addition to supplying the fuel to the fuel tower, a gas containing oxygen is also supplied to the fuel tower.

4. The chemical looping combustion system according to claim 2, wherein: A loop seal is further provided. The loop seal is disposed on the downstream side of the air tower and the upstream side of the fuel tower to suppress the flow of nitrogen from the air tower into the fuel tower. A gas containing oxygen is supplied to the loop seal.

5. The chemical looping combustion system according to claim 2, wherein: The invention further comprises a dehydrator which is a temperature-variable type and removes water contained in the mixed gas by utilizing the heat recovered by the heat exchanger.

6. The chemical looping combustion system according to any one of claims 3 to 5, wherein: The fuel tower further includes a control unit that obtains a required heat release amount required by the air tower and controls a flow rate of air as a gas containing oxygen supplied to the fuel tower when obtaining the required heat release amount. The required heat release is W AR (kW), the low heat value of the fuel is LHV 燃料 (kJ / mole), the heat released per 1 mole of oxygen during the oxidation reaction in the air tower is Δh AR (kJ / mole), the heat absorbed per 1 mole of the fuel during the reduction reaction in the fuel tower is Δh FR (kJ / mole), the oxygen concentration in the air is X O2 In the case of the above, the control unit controls the flow rate of the oxygen-containing gas supplied to the fuel tower to be the flow rate Q calculated by the following formula (1): 空气_FR The control is carried out in a manner that is more than 30% and less than 300%, 。 7. The chemical looping combustion system according to claim 6, wherein: It also includes a temperature acquisition unit for acquiring the temperature inside the fuel tower, The control unit controls the flow rate Q of the air supplied to the fuel tower according to the temperature acquired by the temperature acquisition unit. 空气_FR Take control.

8. The chemical looping combustion system according to claim 7, wherein: 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, the control unit controls the flow rate Q obtained by multiplying the difference by a preset constant. 空气_FR The way in which air is supplied to the fuel tower is controlled, When the difference is negative, the control unit performs control so as not to supply the oxygen-containing gas to the fuel tower.

Images