Chemical looping combustion system and method for controlling chemical looping combustion system

Abstract

To stably control output of a chemical looping combustion system.SOLUTION: A chemical looping combustion system comprises: an oxidation tower that oxidizes oxygen carrier particles; a cyclone that separates gas supplied from the oxidation tower from the oxidized oxygen carrier particles and discharges the separated gas; a fuel tower that reduces the oxidized oxygen carrier particles supplied from the cyclone with fuel containing carbon, separates the oxygen carrier particles from gas containing carbon dioxide, and discharges the separated gas; and a pressure adjustment unit that adjusts at least one of a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] A chemical looping combustion (CLC) system capable of essentially separating carbon dioxide is known (see, for example, Patent Document 1 and Non-Patent Document 1). The chemical looping combustion device described in Patent Document 1 is equipped with a riser that moves oxidized oxygen carrier particles from a vertically downward direction to a vertically upward direction by a carrier gas. In this device, the flow rate of the carrier gas is adjusted using the pressure loss of the carrier gas in the riser. Non-Patent Document 1 describes a CLC device in which an oxidation tower that oxidizes oxygen carrier particles and a fuel tower that reduces the oxygen carrier particles are integrally formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-80238 A [Patent Document 2] Patent No. 5071473 [Non-patent literature]

[0004] [Non-Patent Document 1] Osman, Mogahid, et al. "Experimental demonstration of pressurized chemical looping combustion in an internally circulating reactor for power production with integrated CO2 capture." Chemical Engineering Journal Volume 401, December 2020, 125974 Summary of the Invention [Problem to be solved by the invention]

[0005] The amount of heat generated in the CLC system is determined by the circulation amount of oxygen carrier particles supplied to the oxidation tower and fuel tower per unit time. In other words, the operating output of the CLC system is controlled by the circulation amount of oxygen carrier particles. As described in Patent Document 1, the circulation amount of oxygen carrier particles changes by controlling the flow rate of the carrier gas for the oxygen carrier particles. However, when the flow rate of the carrier gas changes, the motion state of the oxygen carrier particles changes, and the stoichiometric balance in the chemical reaction also changes. Therefore, it has not been easy to control the output of the CLC system by controlling the flow rate of the carrier gas for the oxygen carrier particles.

[0006] Patent Document 2 describes a particle circulation control device that circulates particles by blowing air, unlike the CLC system, which is composed of two towers, an oxidation tower that oxidizes oxygen carrier particles and a fuel tower that reduces oxygen carrier particles. In this device, particles separated from gas from a separator are supplied to a fluidized gasifier. A gasifying agent is supplied to the bottom of the fluidized gasifier, and the particles in the fluidized gasifier are sent to an inclined pipe connected to a combustion furnace. In other words, the fluidized gasifier functions as a loop seal. In the technology described in Patent Document 2, the circulation flow rate of particles is controlled by controlling the differential pressure before and after the fluidized gasifier. However, in the connection space with the inclined pipe, where the pressure is measured downstream of the fluidized gasification flow path, a large amount of particles are floating around due to the supplied gasifying agent. Therefore, it is not easy to measure the pressure in the connection space.

[0007] The present invention has been made to solve at least part of the above-mentioned problems, and has an object to stabilize and control the output of a chemical looping combustion system. [Means for solving the problem]

[0008] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0009] (1) According to one aspect of the present invention, there is provided a chemical looping combustion system comprising: an oxidation tower for oxidizing oxygen carrier particles, a cyclone for separating a gas supplied from the oxidation tower and the oxidized oxygen carrier particles and discharging the separated gas, a fuel tower for reducing the oxidized oxygen carrier particles supplied from the cyclone with a fuel containing carbon, separating the oxygen carrier particles from a gas containing carbon dioxide and discharging the separated gas, and a pressure adjusting unit for adjusting at least one of the pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower.

[0010] According to this configuration, the pressure of the exhaust gas from the cyclone and the pressure of the exhaust gas from the fuel tower are adjusted. For example, the pressure in the fuel tower is increased by setting the pressure of the exhaust gas from the fuel tower high. The increase in the pressure in the fuel tower increases the circulation amount of the oxygen carrier particles circulating in the chemical looping combustion system. On the other hand, the pressure of the exhaust gas from the fuel tower is set low, decreasing the circulation amount of the oxygen carrier particles. In this configuration, the flow rate of the gas supplied to the chemical looping combustion system does not change, so that the change in the flow state of the oxygen carrier particles according to the change in the gas flow rate is suppressed. In addition, since the gas flow rate does not change, the circulation amount of the oxygen carrier particles in the oxidation tower and the fuel tower can be easily set according to the amount of chemical substances contained in the gas. That is, in this configuration, the back pressure of the cyclone and the fuel tower is controlled without changing the gas flow rate, so that the output of the chemical looping combustion system is stably controlled.

[0011] (2) In the chemical looping combustion system of the above aspect, the pressure adjustment unit may include a first pressure adjustment valve that adjusts the pressure of the gas discharged from the cyclone, a second pressure adjustment valve that adjusts the pressure of the gas discharged from the fuel tower, and an aperture adjustment unit that adjusts at least one of the aperture of the first pressure adjustment valve and the aperture of the second pressure adjustment valve. According to this configuration, the pressure of the exhaust gas from the cyclone is adjusted by the aperture of the first pressure regulating valve. Similarly, the pressure of the exhaust gas from the fuel tower is adjusted by the aperture of the second pressure regulating valve. In this configuration, the back pressure of the cyclone and the back pressure of the fuel tower are easily adjusted by using the aperture of the existing pressure regulating valves.

[0012] (3) In the chemical looping combustion system of the above aspect, the opening adjustment unit may adjust at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve by using a difference between a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower. According to this configuration, the aperture of at least one of the first pressure regulating valve and the second pressure regulating valve is adjusted according to the pressure difference between the pressure of the exhaust gas from the cyclone and the pressure of the exhaust gas from the fuel tower. That is, the aperture of the first pressure regulating valve and the aperture of the second pressure regulating valve are easily adjusted by one parameter, the pressure difference.

[0013] (4) The chemical looping combustion system of the above aspect may further include a temperature acquisition unit that acquires a temperature of the cyclone, and the opening adjustment unit may adjust at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve using the temperature of the cyclone in addition to the pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower. According to this configuration, the opening degree of at least one of the first pressure regulating valve and the second pressure regulating valve is adjusted using the pressure of the exhaust gas from the cyclone and the pressure of the exhaust gas from the fuel tower, as well as the temperature of the cyclone. In principle, oxygen carrier particles are not contained in the exhaust gas from the cyclone and the exhaust gas from the fuel tower. However, some of the oxygen carrier particles circulating in the chemical looping combustion system may be crushed and contained in the exhaust gas. In this case, there is a risk that the pressure of the exhaust gas obtained by the crushed oxygen carrier particles may contain an error in the back pressure. In this configuration, the temperature of the cyclone is used to adjust the opening degree of the pressure regulating valve, thereby suppressing the influence of the error generated in the back pressure.

[0014] The present invention can be realized in various forms, for example, 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 on which the computer program is stored, etc. [Brief description of the drawings]

[0015] [Figure 1]FIG. 1 is a schematic block diagram of a chemical looping combustion system according to one embodiment of the present invention. [Diagram 2] FIG. 1 is an explanatory diagram of the principle of chemical looping combustion. [Diagram 3] 4 is a flowchart of pressure control in the first embodiment. [Figure 4] FIG. 1 is a schematic block diagram of a CLC system for confirming the particle circulation amount of metal particles. [Diagram 5] FIG. 4 is an explanatory diagram of a particle circulation amount of metal particles that changes depending on a back pressure difference. [Figure 6] FIG. 11 is a schematic block diagram of a CLC system according to a second embodiment. [Figure 7] 10 is a flowchart of pressure control in a second embodiment. [Figure 8] FIG. 1 is a schematic block diagram of a CLC system for determining temperature changes within a cyclone. [Figure 9] FIG. 2 is an explanatory diagram of temperature changes in a cyclone and an air tower when metal particles are circulating. [Figure 10] FIG. 1 is an explanatory diagram of temperature changes in a cyclone and an air tower when metal particles are not circulating. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] First Embodiment FIG. 1 is a schematic block diagram of a chemical looping combustion system (hereinafter, also simply referred to as a "CLC system") 100 according to one embodiment of the present invention. In the CLC system 100, an air tower (oxidation tower) 10 oxidizes metal particles (oxygen carrier particles) mg as oxygen carrier particles. The metal particles mg and gas discharged from the air tower 10 are supplied to a cyclone 30. The cyclone 30 separates the supplied metal particles mg and gas, and discharges the separated gas. The oxidized metal particles mg are supplied from the cyclone 30 to a fuel tower 20. The fuel tower 20 oxidizes methane (CH 4 The fuel tower 20 reduces the metal particles mg with carbon dioxide (CO 2) and discharge the gas. In this embodiment, the pressure of the gas discharged from the cyclone 30 and the pressure of the gas discharged from the fuel tower 20 are adjusted, so that the output of the CLC system 100 is stably controlled.

[0017] In the CLC system 100, oxidation in the air tower 10 and reduction in the fuel tower 20 are repeated to convert oxygen (O 2 ) from the air tower 10 to the fuel tower 20. In this embodiment, the metal particles mg are Fe 3 O 4 An example using the oxidation reaction of is described below. The particle size of the metal particles mg is 50 μm or more and 250 μm. As shown in FIG. 1, the CLC system 100 of the first embodiment includes an air tower 10, a fuel tower 20, a cyclone 30, an air tower side loop seal 40, a fuel tower side loop seal 50, filters F2 and F3, a first regulating valve (first pressure regulating valve) V3, a second regulating valve (second pressure regulating valve) V2, pressure sensors SS1 and SS2, a regulator 60, a dehydrator 70, and a heater 21 for heating the fuel tower 20.

[0018] Fig. 2 is an explanatory diagram of the principle of chemical looping combustion. Fig. 2 shows a schematic block diagram of a CLC system 100. In Fig. 2, the metal atom (or molecule) used as the metal particle mg is represented as Me.

[0019] In the air tower 10, air is supplied as an oxidizing gas, and the reaction heat from the oxidation reaction of the metal particles mg is converted into CO 2 High temperature N-free 2 In the fuel tower 20, the oxidized metal particles mg are mixed with carbon-containing CH 4 The CO produced by the reduction reaction is 2 The mixed gas containing H is supplied to the dehydrator 70. 2 O is removed to produce high purity CO 2 A gas mixture containing CO 2 It is supplied to the user.

[0020] The air tower 10 of this embodiment is O 2 Using air containing Fe as metal particles mg 3 O 4 is oxidized by causing the reaction shown in the following formula (1). The oxidation reaction of formula (1) is an exothermic reaction. Therefore, the reaction of formula (1) 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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[0021] As shown in FIG. 1, the air tower 10 has a cylindrical shape extending in the vertical direction. A seal 10S is provided vertically below the air tower 10. The seal 10S is a member with a plurality 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. On the other hand, the size of the holes provided in the seal 10S is smaller than the metal particles mg, so that the metal particles mg are prevented from passing through the seal 10S and leaking out of the air tower 10. The gas flow velocity moving vertically upward in 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 a velocity greater than the terminal velocity.

[0022] The metal particles (mg) oxidized in the air tower 10 flow into the cyclone 30 connected via a pipe. The cyclone 30 separates the oxidized metal particles (mg) from the heated gas by using centrifugal force. As shown in FIG. 1, the gas heated in the air tower 10 is discharged from the vertically upper side of the cyclone 30. The composition of the exhaust gas from the cyclone 30 is O, which is the amount of metal particles (mg) oxidized in the air tower 10, and O. 2 is decreasing, so most of the 2The exhaust gas from the cyclone 30 is sent to a heat utilization destination after crushed metal particles (mg) are removed by the filter F3. The first regulating valve V3 arranged downstream of the filter F3 is a pressure regulating valve whose opening is adjusted by an adjusting unit 60 (described later) to adjust the pressure of the exhaust gas from the cyclone 30. The pressure sensor SS1 detects the pressure P of the exhaust gas that has passed through the filter F3 and before passing through the first regulating valve V3. 1 Detect.

[0023] The metal particles mg separated from the gas in the cyclone 30 move to the air tower side loop seal 40 through a piping extending vertically downward in the center of the cyclone 30 as shown in FIG.

[0024] As shown in FIG. 1, the air tower side loop seal 40 is disposed downstream of the air tower 10 and upstream of the fuel tower 20. A seal 40S is provided vertically below the air tower side loop seal 40. The seal 40S is a member with multiple small holes, like the seal 10S of the air tower 10. The small holes formed in the seal 40S are smaller than the particle size of the metal particles mg. Therefore, as shown in FIG. 1, a particle layer (hatched portion) formed of multiple metal particles mg is formed on the upper surface of the seal 40S.

[0025] Steam is supplied from vertically below the seal 40S. The supplied steam passes through the seal 40S and flows into the fuel tower 20 connected to the downstream side of the air tower side loop seal 40. Since steam is supplied into the air tower side loop seal 40 from below the seal 40S, N 2 This prevents the gas, the main component of which is water vapor, from passing through the particle layer and flowing from the cyclone 30 into the fuel tower 20. Note that water vapor is removed by the dehydrator 70 when the exhaust gas discharged from the fuel tower 20 passes through.

[0026] A fluidized bed that flows from the air tower side loop seal 40 to the fuel tower 20 is disposed in the piping that connects the air tower side loop seal 40 and the fuel tower 20. The metal particles mg discharged from the cylindrical air tower side loop seal 40 move to the fuel tower 20 due to the flow of the fluidized bed.

[0027] In this embodiment, the fuel tower 20 contains methane (CH 4 ) and the like are supplied from the air tower 10, and a gas containing oxidized metal particles mg and water vapor supplied to the air tower side loop seal 40 is supplied. The fuel tower 20 is 4 The metal particles (mg) are reduced using fuel such as CO. 2 The mixed gas containing the reduced metal particles (mg) is separated and discharged. The exhaust gas from the fuel tower 20 is filtered by the filter F2 to remove the crushed metal particles (mg), and then the CO 2 The exhaust gas that has passed through the second regulating valve V2 is sent to a destination. The second regulating valve V2, which is disposed downstream of the filter F2, is a pressure regulating valve whose opening is adjusted by an adjusting unit 60, which will be described later. The exhaust gas that has passed through the second regulating valve V2 is dehydrated by a dehydrator 70, and then is dehydrated into CO 2 It is supplied to the user. 2 Examples of uses of CO 2 The pressure sensor SS2 detects the pressure P of the exhaust gas that has passed through the filter F2 and before passing through the second regulating valve V2. 2 Detect.

[0028] As shown in Fig. 1, 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 member having a plurality of small holes, like the seal 10S. In the fuel tower 20, gaseous CH 4 The gas flow velocity in the fuel tower 20 is set to a velocity slower than the terminal velocity, and is controlled based on information about the fuel tower 20 so that metal particles mg do not fly out.

[0029] CH4 as fuel4 In the fuel tower 20 to which the air column 10 is supplied, the metal particles mg oxidized in the air column 10, represented by the above formula (1), are Fe 2 O 3 As shown in the following formula (2), 4 Reduced to Fe 3 O 4 Changes to CO 2 The reduction reaction represented by the following formula (2) is an endothermic reaction. The inside of the fuel tower 20, where the temperature drops due to the endothermic reaction, is heated by the heater 21.

[0030]

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[0031] The oxidation reaction in the air tower 10 represented by the above formula (1) and the CH 4 When the reduction reaction of CH in the fuel tower 20 is added, 4 The reactions in the air column 10 and the fuel column 20, including the reduction reaction by CH 4 This is the same reaction as the combustion of metal particles mg and CH 4 The total amount of heat obtained by the reduction of metal particles (mg) by the air column 10 and the fuel column 20 is CH 4 This is identical to the combustion of

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[0032] The metal particles mg reduced by the reduction reaction in the fuel tower 20 move to the fuel tower side loop seal 50 through a piping extending vertically downward in the center of the fuel tower 20, as shown in FIG. 1.

[0033] The fuel tower side loop seal 50, to which the metal particles mg are supplied from the fuel tower 20, is disposed downstream of the fuel tower 20 and upstream of the air tower 10. The fuel tower side loop seal 50 has the same configuration as the air tower side loop seal 40. A seal 50S is provided vertically below the fuel tower side loop seal 50. The seal 50S is a member with multiple small holes, like the seal 10S. In the fuel tower side loop seal 50, water vapor is supplied from vertically below the seal 50S. The supplied water vapor passes through the seal 50S and flows into the air tower 10 connected downstream of the fuel tower side loop seal 50. A fluidized bed that flows from the fuel tower side loop seal 50 to the air tower 10 is disposed in the piping that connects the fuel tower side loop seal 50 and the air tower 10. The fluidized bed causes the metal particles mg in the cylindrical fuel tower side loop seal 50 to move to the air tower 10. As described above, the metal particles mg are oxidized in the air tower 10, reduced in the fuel tower 20, and circulated between the air tower 10 and the fuel tower 20.

[0034] The adjusting unit 60 adjusts at least one of the pressure of the exhaust gas from the cyclone 30 and the pressure of the exhaust gas from the fuel tower 20. In this embodiment, the adjusting unit 60 adjusts the pressure of each exhaust gas by adjusting the opening degree of the first adjusting valve V3 and the opening degree of the second adjusting valve V2. The adjusting unit 60 adjusts the pressure P of the exhaust gas from the cyclone 30 detected by the pressure sensor SS1. 1 and the pressure P of the exhaust gas from the fuel tower 20 detected by the pressure sensor SS2. 2 The adjustment unit 60 acquires the acquired pressure P 1 and pressure P 2 The adjustment unit 60 adjusts at least one of the opening degree of the first adjustment valve V3 and the opening degree of the second adjustment valve V2 using the back pressure difference ΔP between the pressure P 2 Pressure P 1 The back pressure difference ΔP is calculated by subtracting the back pressure difference ΔP from the back pressure difference ΔP. Note that the adjustment unit 60, the first adjustment valve V3, and the second adjustment valve V2 correspond to a pressure adjustment unit.

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[0035] The adjustment unit 60 adjusts the back pressure difference ΔP to a preset target back pressure difference ΔP tar The opening degree of at least one of the first regulating valve V3 and the second regulating valve V2 is adjusted so that the pressure P 1 ,P 2 (Step S1). Step S1 corresponds to the first and second acquisition steps.

[0036] The adjustment unit 60 adjusts the acquired pressure P 1 ,P 2 Using the above formula (4), the back pressure difference ΔP is calculated (step S2). The adjustment unit 60 checks whether the calculated back pressure difference ΔP is equal to or smaller than the target back pressure difference ΔP tar The opening degree of at least one of the first regulating valve V3 and the second regulating valve V2 is adjusted so as to satisfy the following condition (Step S3). Steps S2 and S3 correspond to a pressure regulating step.

[0037] The adjustment unit 60 determines whether or not to terminate the operation of the CLC system 100 (step S4). If it is determined that the operation is not to be terminated because an end signal or the like has not been received from the user (step S4: NO), the adjustment unit 60 repeats the processes from step S1 onward. If it is determined that the operation of the CLC system 100 is to be terminated (step S4: YES), the adjustment unit 60 terminates the pressure control flow.

[0038] 4 and 5 are explanatory diagrams of the effect of controlling the particle circulation amount. FIG. 4 shows a schematic block diagram of a CLC system 100A for confirming the particle circulation amount of metal particles (mg) circulating in the CLC system. In the CLC system 100A shown in FIG. 4, 4Since no fuel such as argon is supplied, the oxidation-reduction reaction of the metal particles mg does not occur. Therefore, compared to the CLC system 100 shown in Fig. 1, the CLC system 100A does not include a heater 21, filters F2 and F3, and a dehydrator 70. In addition, the air tower 10, the fuel tower 20, the air tower side loop seal 40, and the fuel tower side loop seal 50 are made of transparent acrylic. Therefore, the circulation behavior of the metal particles mg inside the air tower 10 etc. can be visually confirmed.

[0039] FIG. 5 shows the particle circulation amount of metal particles (mg) that changes according to the back pressure difference ΔP. FIG. 5 shows the particle circulation amount Ms of the simulation result shown by the solid line connecting black circles, and the actual particle circulation amount Mr circulating in the CLC system 100A shown by the dashed line connecting white circles. Note that the particle circulation amount Mr where the back pressure difference ΔP is less than 1.1 kPa is not plotted because no data was measured. As shown by the particle circulation amounts Ms and Mr in FIG. 5, it was confirmed that the metal particles (mg) circulating in the CLC system 100A increases with an increase in the back pressure difference ΔP.

[0040] As described above, in the CLC system 100 of this embodiment, metal particles mg as oxygen carrier particles oxidized in the air tower 10 are supplied to the cyclone 30. The cyclone 30 separates the supplied metal particles mg from the gas and discharges the separated gas. The fuel tower 20 oxidizes the oxidized metal particles mg supplied from the cyclone 30 into CH as a carbon-containing fuel. 4 The fuel tower 20 is a mixture of metal particles mg and CO 2 The pressure regulation unit 60 regulates the pressure P of the exhaust gas from the cyclone 30. 1 and the pressure P of the exhaust gas from the fuel tower 20 2 In this embodiment, for example, the pressure P of the exhaust gas from the fuel tower 20 is adjusted. 2 By setting the pressure in the fuel tower 20 high by the adjusting unit 60, the pressure in the fuel tower 20 also increases. By increasing the pressure in the fuel tower 20, the amount of metal particles mg circulating in the CLC system 100 increases. On the other hand, the pressure P2 is set low, the circulation amount of the metal particles mg decreases. When the gas flow rate is low, the metal particles mg are fixed in the fluidized bed and do not move. When the gas flow rate increases from this state, the metal particles mg change to a fluidized bed state in which they flow with complex gas bubbles. When the gas flow rate increases further, the metal particles mg enter a turbulent fluidized state. Therefore, in order to generate particle circulation, it is necessary to maintain an appropriate fluidized state, and there is a limit to the range of gas flow rates that can be changed for this purpose. In addition, when the gas flow rate changes, the amount of supplied chemical substances contained in the gas changes, so the reactions in the air tower 10 and the fuel tower 20 also change. In this regard, in this embodiment, the gas flow rate supplied into the CLC system 100 does not change, so the change in the fluidized state of the metal particles mg according to the change in gas flow rate is suppressed. In addition, since the gas flow rate does not change, the circulation amount of the metal particles mg corresponding to the amount of chemical substances contained in the gas can be easily set in the air tower 10 and the fuel tower 20. That is, in this embodiment, the back pressure of the cyclone 30 and the fuel tower 20 is controlled without changing the gas flow rate, thereby stably controlling the output of the CLC system 100.

[0041] In this embodiment, the first regulating valve V3 regulates the pressure P 1 The second regulating valve V2 regulates the pressure P of the exhaust gas from the fuel tower 20. 2 The adjusting unit 60 adjusts the opening degree of the first adjusting valve V3 and the opening degree of the second adjusting valve V2 to adjust the pressure P 1 and pressure P 2 In this embodiment, the back pressure of the cyclone 30 and the back pressure of the fuel tower 20 are simply adjusted using the opening degree of an existing pressure regulating valve.

[0042] In addition, the adjustment unit 60 of the present embodiment adjusts the acquired pressure P 1 and pressure P 2 At least one of the opening degree of the first regulating valve V3 and the opening degree of the second regulating valve V2 is adjusted using the back pressure difference ΔP between the first regulating valve V3 and the second regulating valve V2. In this embodiment, the opening degree of the first regulating valve V3 and the opening degree of the second regulating valve V2 are easily adjusted by one parameter, the back pressure difference ΔP.

[0043] <Modification of the first embodiment> In the first embodiment, an example of pressure control using the back pressure difference ΔP has been described, but the pressure control using the back pressure difference ΔP can be modified. For example, the adjustment unit 60 controls the opening degree of the first adjustment valve V3 to adjust the pressure P 1 (t+Δt) is the pressure P at time t 1 It may be adjusted as shown in the following formula (5) using (t).

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[0044] In addition, the adjusting unit 60 controls the opening degree of the second adjusting valve V2 instead of the first adjusting valve V3, thereby reducing the pressure P detected by the pressure sensor SS2 after Δt seconds from the time t. 2 (t+Δt) is the pressure P at time t 2 It may be adjusted as shown in the following formula (6) using (t).

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[0045] <Second embodiment> 6 is a schematic block diagram of a CLC system 100a according to the second embodiment. In the CLC system 100a according to the second embodiment, the pressure P 1 and the pressure P of the exhaust gas from the fuel tower 20 2 In addition, the temperature T 1 Using the pressure P 1 and pressure P 2 The second embodiment differs from the first embodiment in that at least one of the above is adjusted.

[0046] 6, the CLC system 100a of the second embodiment includes, in addition to the components of the CLC system 100 of the first embodiment, a temperature sensor (temperature acquisition unit) SS3 that detects the temperature inside the cyclone 30. The temperature sensor SS3 is disposed vertically downward inside the cyclone 30.

[0047] The adjustment unit 60a of the second embodiment adjusts the pressure P of the exhaust gas from the cyclone 30. 1 and the pressure P of the exhaust gas from the fuel tower 20 2 In addition, the temperature T 1 Using the above, the pressure P 1 and pressure P 2 The adjustment unit 60a adjusts at least one of the preset target temperature T tar As shown in the following equation (7), the pressure P at time t 1 (t) is the pressure P after Δt seconds from time t 1 (t+Δt). Note that the target temperature T tar is the control target temperature. In the following formula (7), k1 is a proportionality constant determined in advance.

[0048]

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[0049] Pressure P using the above formula (7) 1 The temperature T in the cyclone 30 is controlled by adjusting the opening of the first adjusting valve V3. 1 is the target temperature T tar If less than the pressure P 1 decreases, the back pressure difference ΔP increases, and the circulation amount of metal particles mg increases. On the other hand, the temperature T 1 If exceeds the target temperature, the pressure P 1 increases, the back pressure difference ΔP decreases, and the circulation amount of metal particles mg decreases.

[0050] 7 is a flow chart of pressure control in the second embodiment. As shown in the pressure control flow of FIG. 7, the adjustment unit 60a in the second embodiment adjusts the pressure P 1,P 2 (Step S11). The adjustment unit 60a further acquires the temperature T 1 (Step S12). The adjustment unit 60a acquires the acquired pressure P 1 ,P 2 and temperature T 1 Using the above formula (7), the pressure P 1 (t+Δt) (step S13). The adjustment unit 60a calculates the calculated pressure P 1 The opening degree of the first adjustment valve V3 is adjusted so that the time t becomes (t+Δt) (step S14). The adjustment unit 60a determines whether or not to terminate the operation of the CLC system 100a (step S15). If it is determined not to terminate the operation (step S15: NO), the adjustment unit 60a repeats the processes from step S11 onwards. If it is determined to terminate the operation of the CLC system 100a (step S15: YES), the adjustment unit 60a ends the pressure control flow.

[0051] Each of the diagrams from FIG. 8 to FIG. 10 shows the temperature T 1 FIG. 8 is an explanatory diagram of the temperature T in the cyclone 30 according to the presence or absence of particle circulation of metal particles mg circulating in the CLC system. 1 8 shows a schematic block diagram of a CLC system 100B for confirming the change in temperature T 2 The temperature sensor SS4 is disposed vertically downward in the air tower 10. Therefore, the temperature sensor SS4 detects the temperature T 2 In the CLC system 100B, unlike the CLC system 100A shown in Fig. 4, the air tower 10, the fuel tower 20, the air tower side loop seal 40, and the fuel tower side loop seal 50 are made of SUS310S. Therefore, even if the oxidation and reduction of the metal particles mg occurs in the air tower 10 and the fuel tower 20, the air tower 10 and the fuel tower 20 are not damaged.

[0052] FIG. 9 shows the temperature T 1 ,T 2 On the other hand, FIG. 10 shows the change in temperature T 1 ,T 2 9 and 10, the change in temperature T 1 The change in temperature T in the air tower 10 detected by the temperature sensor SS4 is shown by a dashed line. 2 The change in temperature T in the air tower 10 is shown by a solid line. 2 increases over time regardless of whether the metal particles mg are circulated or not. On the other hand, the temperature T 1 When the metal particles mg are circulating, the temperature T in the cyclone 30 rises as shown in FIG. 9, but when the metal particles mg are not circulating, the temperature T does not change as shown in FIG. 10. When the metal particles mg are circulating, the metal particles mg that generate heat due to oxidation do not remain in the air tower 10 but move. Therefore, the temperature T in the cyclone 30 1 In other words, from the results of Figures 9 and 10, the temperature T 1 increases when metal particles mg circulate through the CLC system B.

[0053] As described above, the adjusting unit 60a of the second embodiment adjusts the pressure P 1 and the pressure P of the exhaust gas from the fuel tower 20 2 In addition, the temperature T 1 Using the above, the pressure P 1 and pressure P 2In the CLC system 100a, in principle, the exhaust gas from the cyclone 30 and the exhaust gas from the fuel tower 20 do not contain metal particles mg. However, some of the metal particles mg circulating in the CLC system 100a may be crushed and contained in the exhaust gas. In this case, the crushed metal particles mg mixed in the exhaust gas may increase the exhaust gas pressure P 1 ,P 2 In this embodiment, the temperature T 1 is used to adjust the opening degree of the first regulating valve V3 and the second regulating valve V2, the influence of errors occurring in the back pressure can be suppressed.

[0054] <Modification of the second embodiment> In the second embodiment, the temperature T 1 An example of back pressure control using the temperature T 1 The back pressure control using the pressure P 1 ,P 2 and temperature T 1 The opening degree of the second regulating valve V2 is controlled using the above. As a result, the pressure P detected by the pressure sensor SS2 after Δt seconds from the time t is 2 (t+Δt) is the pressure P at time t 2 The adjustment may be performed as shown in the following formula (8) using (t): k2 in the following formula (8) is a proportionality constant determined in advance.

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[0055] <Modifications of the embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the present invention, for example, the following modifications are possible: In the above-described embodiment, a part of the configuration realized by hardware may be replaced by software, and conversely, a part of the configuration realized by software may be replaced by hardware.

[0056] <Variation 1> The CLC system 100, 100a of the first and second embodiments is an example, and can be modified within a range in which at least one of the pressure of the gas separated and discharged in the cyclone 30 and the pressure of the gas separated and discharged in the fuel tower 20 is adjusted. For example, the CLC system 100 may not include the air tower side loop seal 40, the fuel tower side loop seal 50, and the filters F2, F3. The back pressure of one of the first and second regulating valves V3 and V2 may be fixed, and the regulating unit 60 may adjust the other regulating valve to control the circulation amount of the metal particles mg. In addition, at least one of the pressure of the exhaust gas from the cyclone 30 and the pressure of the exhaust gas from the fuel tower 20 may be adjusted by a method that does not use a pressure regulating valve such as a vacuum pump. The back pressure difference ΔP is calculated as the difference between the detection values ​​of the two pressure sensors SS1 and SS2, but may be directly detected as a differential pressure.

[0057] The metal particles, which are oxygen carrier particles circulating in the CLC system, are FeTiO 3 Similarly, the carbon-containing fuel fed to the fuel tower 20 may be CH 4 Other than C 2 H 6 Or C 3 H 8 For example, nickel (Ni) or copper (Cu) is used as the metal particles mg, and C is used as the fuel. 2 H 6 In this case, the reduction reaction occurring in the fuel tower 20 is expressed by the following formulas (9) and (10).

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[0058] The gas fed to the air column 10 may be other than air, and may be O 2 The gas may be any gas containing O.2 In other words, it is an oxidation tower to which a gas containing is supplied and oxidizes the metal particles mg. In addition, the air tower 10 and the fuel tower 20 do not have to be formed as two independent towers, and may be formed as an integrated device including an air tower side loop seal 40 and a fuel tower side loop seal 50, as described in Non-Patent Document 1.

[0059] <Variation 2> In the CLC system 100a of the second embodiment, the adjustment unit 60a adjusts the pressure P 1 ,P 2 However, the adjustment unit of the modified example uses the temperature T 1 Alternatively, at least one of the first regulating valve V3 and the second regulating valve V2 may be adjusted using only the temperature sensor SS3. Since the temperature sensor SS3 is less expensive than the pressure sensors SS1 and SS2, in this modified example, the output of the CLC system is controlled stably and at low cost. In this case, the temperature sensor SS3 and the adjustment unit 60a correspond to a pressure adjustment unit. As a result, the opening degree R of the first regulating valve V3 Δt seconds after time t is V3 (t+Δt) is the temperature T of the temperature sensor SS4 at time t 1 The adjustment may be performed as shown in the following formula (11) using (t): k3 in the following formula (11) is a proportionality constant determined in advance.

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[0060] Although the present aspect has been described above based on the embodiment and modified examples, the above-mentioned embodiment of the aspect is intended to facilitate understanding of the present aspect and does not limit the present aspect. The present aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents are included in the present aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0061] The present invention can also be realized in the following forms. [Application example 1] 1. A chemical looping combustion system comprising: an oxidation tower for oxidizing the oxygen carrier particles; a cyclone for separating the gas supplied from the oxidation tower and the oxidized oxygen carrier particles and discharging the separated gas; a fuel tower that reduces the oxidized oxygen carrier particles supplied from the cyclone with a fuel containing carbon, separates the oxygen carrier particles from a gas containing carbon dioxide, and discharges the separated gas; a pressure adjusting unit that adjusts at least one of the pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower; A chemical looping combustion system comprising: [Application example 2] The chemical looping combustion system according to Application Example 1, The pressure adjustment unit is a first pressure regulating valve for regulating the pressure of the gas discharged from the cyclone; a second pressure regulating valve for regulating the pressure of the gas discharged from the fuel tower; an opening adjustment unit that adjusts at least one of the opening degree of the first pressure regulating valve and the opening degree of the second pressure regulating valve; A chemical looping combustion system having: [Application example 3] The chemical looping combustion system according to Application Example 1 or Application Example 2, the opening adjustment unit adjusts at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve using a difference between a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower. [Application example 4] The chemical looping combustion system according to any one of Application Examples 1 to 3, further comprising: A temperature acquisition unit for acquiring a temperature of the cyclone, the opening adjustment unit adjusts at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve using a temperature of the cyclone in addition to a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower. [Application example 5] 1. A method for controlling a chemical looping combustion system, comprising: A first obtaining step of obtaining the pressure of a gas separated from the oxygen carrier particles and discharged by a cyclone to which gas and the oxidized oxygen carrier particles are supplied from an oxidation tower that oxidizes the oxygen carrier particles; A second acquisition step of acquiring the pressure of a gas containing carbon dioxide separated from the oxygen carrier particles and discharged by a fuel tower that reduces the oxidized oxygen carrier particles supplied from the cyclone with a fuel containing carbon; a pressure adjusting step of adjusting at least one of the acquired pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower; A control method for performing the above. [Explanation of symbols]

[0062] 10...Air tower (oxidation tower) 10S…Air tower seal 20…Fuel tower 20S…Fuel tower seal 21…Heater 30…Cyclone 40…Air tower side loop seal 40S…Seal of air tower side loop seal 50…Fuel tower side loop seal 50S…Fuel tower side loop seal 60, 60a...Adjustment section (opening adjustment section) 70...Dehydrator 100, 100a, 100A, 100B...CLC system (Chemical Looping Combustion System) F2, F3: Filter P 1 …Pressure of exhaust gas from cyclone P2 …Pressure of exhaust gas from fuel tower SS1, SS2...Pressure sensor SS3: Temperature sensor (temperature acquisition section) SS4...Temperature sensor T 1 …Temperature inside the cyclone T 2 …Temperature in the air tower T tar …Target temperature V2: Second regulating valve (second pressure regulating valve) V3…First adjustment valve (first pressure adjustment valve) mg…metal particles (oxygen carrier particles) ΔP…back pressure difference ΔP tar …Target back pressure difference

Claims

1. 1. A chemical looping combustion system comprising: an oxidation tower for oxidizing the oxygen carrier particles; a cyclone for separating the gas supplied from the oxidation tower and the oxidized oxygen carrier particles and discharging the separated gas; a fuel tower that reduces the oxidized oxygen carrier particles supplied from the cyclone with a fuel containing carbon, separates the oxygen carrier particles from a gas containing carbon dioxide, and discharges the separated gas; a pressure adjusting unit that adjusts at least one of the pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower; A chemical looping combustion system comprising:

2. 2. The chemical looping combustion system of claim 1, comprising: The pressure adjustment unit is a first pressure regulating valve for regulating the pressure of the gas discharged from the cyclone; a second pressure regulating valve for regulating the pressure of the gas discharged from the fuel tower; an opening degree adjustment unit that adjusts at least one of an opening degree of the first pressure regulating valve and an opening degree of the second pressure regulating valve; A chemical looping combustion system having:

3. 3. The chemical looping combustion system of claim 2, comprising: the opening adjustment unit adjusts at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve using a difference between a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower.

4. The chemical looping combustion system according to claim 2 or 3, further comprising: A temperature acquisition unit for acquiring a temperature of the cyclone, the opening adjustment unit adjusts at least one of the opening of the first pressure regulating valve and the opening of the second pressure regulating valve using a temperature of the cyclone in addition to a pressure of the gas discharged from the cyclone and a pressure of the gas discharged from the fuel tower.

5. 1. A method for controlling a chemical looping combustion system, comprising: a first obtaining step of obtaining the pressure of a gas separated from the oxygen carrier particles and discharged by a cyclone to which gas and the oxidized oxygen carrier particles are supplied from an oxidation tower that oxidizes the oxygen carrier particles; A second acquisition step of acquiring the pressure of a gas containing carbon dioxide separated from the oxygen carrier particles by a fuel tower that reduces the oxidized oxygen carrier particles supplied from the cyclone with a fuel containing carbon, and being discharged; a pressure adjusting step of adjusting at least one of the acquired pressure of the gas discharged from the cyclone and the pressure of the gas discharged from the fuel tower; A control method for performing the above.

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