Chemical loop combustion apparatus, and control device and control method for chemical loop combustion apparatus

Abstract

The objective is to operate a chemical loop combustion system in a way that suppresses the increase in the unburned metal particle rate. [Solution] The control device for controlling the chemical loop combustion apparatus performs a first control that controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidizing the metal particles through reaction with the air, and supplying fuel to the fuel tower, reducing the metal particles through reaction with the fuel; and a second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of metal particles in the fuel tower.

Description

Technical Field

[0001] The present invention relates to a chemical looping combustion apparatus, and a control device and a control method for the chemical looping combustion apparatus.

Background Art

[0002] A chemical looping combustion apparatus is known that includes an air tower that causes oxygen-containing air to react with metal particles to obtain oxidation heat, and a fuel tower that reduces the metal particles through a reaction between the metal particles oxidized in the air tower and fuel (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, there was room for improvement in the operation of the chemical looping combustion apparatus described in Patent Document 1.

[0005] The present invention has been made to solve at least part of the above-described problems, and an object thereof is to perform operation that suppresses an increase in the unburned ratio of metal particles in a chemical looping combustion apparatus.

Means for Solving the Problems

[0006] The present invention has been made to solve at least part of the above-described problems, and can be implemented in the following embodiments.

[0007] (1) According to one embodiment of the present invention, a control device for controlling a chemical loop combustion apparatus is provided. This control device includes a first control that controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidize metal particles by reaction with the air, and supply fuel to the fuel tower, and reduce the metal particles by reaction with the fuel; and a second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of the metal particles in the fuel tower. To do so.

[0008] This configuration allows the reduction rate of metal particles (MP), which increases during normal operation, to be reduced to a value close to that at the start of operation. Therefore, the increase in the unburned rate of metal particles (MP) can be suppressed.

[0009] (2) In the control device of the above embodiment, the second control may control the fuel tower gas supply unit to supply air to the fuel tower for oxidizing the metal particles. This configuration allows the reduction of metal particles (MP), which increases during normal operation, to be reduced to a value closer to that at the start of operation. Therefore, the increase in the unburned rate of metal particles (MP) can be further suppressed.

[0010] (3) In the control device of the above form, the second control may control the fuel tower gas supply unit to supply the fuel tower with the fuel and an amount of air greater than the amount necessary for the complete combustion of the fuel. This configuration allows the reduction of metal particles (MP), which increases during normal operation, to be reduced to a value closer to that at the start of operation. Therefore, the increase in the unburned rate of metal particles (MP) can be further suppressed.

[0011] (4) In the control device of the above form, the second control may change the amount of fuel supplied to the fuel tower according to the temperature inside the tower. This configuration allows the fuel tower to maintain a state where the reduction rate of metal particles (MP), which rises during normal operation, can be reduced to a value close to that at the start of operation. Therefore, the increase in the unburned metal particle MP rate can be further suppressed.

[0012] (5) In the control device of the above form, the second control may control the air tower gas supply unit and supply the fuel to the air tower. This configuration allows for the oxidation of metal particles MP not only inside the fuel tower but also inside the air tower, reducing the reduction level of metal particles MP, which has increased during normal operation, to a value closer to that at the start of operation. Therefore, the increase in the unburned metal particle MP rate can be further suppressed.

[0013] Furthermore, the present invention can be realized in various forms, for example, as a control method for a chemical loop combustion system, a chemical loop combustion system controlled by the above-mentioned control device, a chemical loop combustion plant, a chemical loop combustion apparatus, apparatus and systems comprising these, a method for producing carbon dioxide, a method for synthesizing carbon dioxide, a computer program for executing the above-mentioned control device and control method, a server apparatus for distributing this computer program, and a non-temporary storage medium storing the computer program. [Brief explanation of the drawing]

[0014] [Figure 1] This is an explanatory diagram illustrating the configuration of a chemical loop combustion apparatus as a first embodiment. [Figure 2] This is a flowchart of the operation control performed by the control unit. [Figure 3] This diagram illustrates the normal operation of a chemical loop combustion system. [Figure 4] This diagram illustrates and explains the reduction suppression operation of a chemical loop combustion apparatus. [Figure 5] This is a flowchart illustrating the control of the fuel supply amount to the fuel tower performed by the control unit during reduction suppression operation. [Figure 6] This is a diagram for explaining the reduction degree of metal particles. [Figure 7] This is a diagram for illustrating and explaining a modified example of the reduction suppression operation of the first embodiment. [Figure 8] This is an explanatory diagram illustrating the configuration of a chemical looping combustion apparatus as the second embodiment. [Figure 9] This is a diagram for illustrating and explaining the reduction suppression operation in the chemical looping combustion apparatus as the second embodiment. [Modes for Carrying Out the Invention]

[0015] <First Embodiment> [Configuration of Chemical Looping Combustion Apparatus 1] FIG. 1 is an explanatory diagram illustrating the configuration of the chemical looping combustion apparatus 1 as the first embodiment of the present invention. The chemical looping combustion apparatus 1 is a system that generates heat through an oxidation reaction using metal particles MP circulating inside the apparatus, and generates carbon dioxide and the like through a reduction reaction using the metal particles MP circulating inside the apparatus.

[0016] The chemical looping combustion system 1 includes an air tower 10, a cyclone 20, a first loop seal part 30, a fuel tower 40, a second loop seal part 50, a circulation pipe 60, a dehydrator DH, an air tower gas supply unit 70, a fuel tower gas supply unit 80, and a control unit 90.

[0017] The air tower 10 is a tower that obtains heat generation while causing metal particles MP to react with oxygen to oxidize the metal particles MP. The air tower 10 is provided with a supply port IG for supplying processing gas and air into the interior of the air tower 10. A pipe (not shown) through which gas flows is connected to the supply port IG, and gas is supplied from an air tower gas supply unit described later into the interior of the air tower 10 via the supply port IG. Inside the air tower 10, the metal particles MP are scattered by the supply of gas, so that the metal particles MP are sent to the side of the cyclone 20 (described later) connected to the portion on the upper side in the gravity direction of the air tower 10.

[0018] Cyclone 20 is connected to the upper part of the air tower 10 in the direction of gravity, and separates the metal particles MP sent from the air tower 10 from the exhaust gas based on the difference in specific gravity.

[0019] The first loop seal section 30 is connected to the lower part of the cyclone 20 in the direction of gravity and receives metal particles MP separated from the exhaust gas in the cyclone 20. The first loop seal section 30 restricts the movement of gas between the air tower 10 and the fuel tower 40 by appropriately supplying water vapor as a sealing gas into its interior. This sealing gas also assists in the flow of the metal particles MP within the first loop seal section 30.

[0020] The fuel tower 40 is equipped with a temperature measuring section 41 and is connected to the first loop seal section 30 via a first pipe 61, which will be described later. The fuel tower reacts metal particles MP oxidized in the air tower 10 with hydrocarbon fuel to reduce the metal particles MP and discharges the gas generated by the reduction of the metal particles MP. The fuel tower 40 is provided with a supply port IF for supplying gas such as hydrocarbon fuel into the fuel tower 40. A pipe (not shown) for circulating the gas is connected to the supply port IF, and the gas supplied from the fuel tower gas supply section, which will be described later, is supplied into the fuel tower 40 via the supply port IF.

[0021] The temperature measuring unit 41 is capable of measuring the internal temperature of the fuel tower 40, and this temperature information is acquired by the control unit 90, which will be described later.

[0022] The second loop seal section 50 is connected to the lower part of the fuel tower 40 in the direction of gravity and receives metal particles MP separated from the gas in the fuel tower 40. Similar to the first loop seal section 30, the second loop seal section 50 restricts the movement of gas between the air tower 10 and the fuel tower 40 by appropriately supplying water vapor as a sealing gas into its interior. This sealing gas also assists the flow of the metal particles MP within the second loop seal section 50.

[0023] The circulation piping 60 is a pipe that circulates metal particles MP between the air tower 10 and the fuel tower 40. The circulation piping 60 includes a first pipe 61 and a second pipe 62. The first pipe 61 is a pipe that connects the first loop seal section 30 and the fuel tower 40, and defines a flow path for metal particles MP to flow from the first loop seal section 30 to the fuel tower 40. Metal particles MP used in the reduction reaction in the fuel tower 40 are sent from the first loop seal section 30 to the fuel tower 40 via the first pipe 61. On the other hand, the second pipe 62 is a pipe that connects the second loop seal section 50 and the air tower 10, and defines a flow path for metal particles MP to flow from the second loop seal section 50 to the air tower 10. Metal particles MP used in the oxidation reaction in the air tower 10 are sent from the second loop seal section 50 to the air tower 10 via the second pipe 62.

[0024] The dewatering unit DH is located above the fuel tower 40 in the direction of gravity and removes water from the gas discharged to the outside of the fuel tower 40. The dewatering unit DH contains an adsorbent material capable of adsorbing moisture, such as silica gel. The gas that passes through the dewatering unit DH contains only carbon dioxide. Furthermore, the dewatering unit DH is not required. Also, the configuration of the dewatering unit DH and the method of dewatering are not limited to those described above. Dewatering may also be performed by cooling the mixed gas.

[0025] The air tower gas supply unit 70 receives control from the control unit 90 and supplies gas from the supply port IG into the interior of the air tower 10.

[0026] The fuel tower gas supply unit 80 receives control from the control unit 90 and supplies gas from the supply port IF into the interior of the fuel tower 40.

[0027] The control unit 90 is composed of an ECU (Electronic Control Unit) and controls the chemical loop combustion system 1. The control unit 90 controls the type and amount of gas supplied by the air tower gas supply unit 70 to the air tower 10, and the type and amount of gas supplied by the fuel tower gas supply unit 80 to the fuel tower 40. The control unit 90 controls the chemical loop combustion system 1 and can perform control to make it operate in two modes: normal operation and reduction suppression operation. Normal operation is the operation in which the air tower gas supply section 70 and the fuel tower gas supply section 80 are controlled to supply air to the air tower 10, oxidizing the metal particles MP through reaction with the air, and also supplying fuel to the fuel tower 40, reducing the metal particles MP through reaction with the fuel. Reduction suppression operation is a predetermined operation that controls the air tower gas supply section 70 and the fuel tower gas supply section 80 to suppress the reduction of metal particles MP in the fuel tower 40. In reduction suppression operation, metal particles MP circulating in the chemical loop combustion apparatus 1, which includes the air tower 10 and the fuel tower 40, are oxidized. In other words, in reduction suppression operation, it is sufficient that the amount of metal particles MP oxidized in the entire chemical loop combustion apparatus 1 is greater than the amount reduced. Details of normal operation and reduction-reduced operation will be described later.

[0028] Figure 2 is a flowchart of the operation control performed by the control unit 90. When the control unit 90 receives an operation start command from the operator and starts operation, it first causes the chemical loop combustion device 1 to perform normal operation as shown in step S1. Next, in step S2, it is determined whether the conditions for switching from normal operation to reduction-suppressed operation have been met. If they have not been met, the process returns to step S1 and normal operation continues. On the other hand, if the switching conditions have been met, the process proceeds to step S3. The conditions for switching operations may be met when an operator performs an operation to switch operations, or they may be met after a predetermined amount of time has elapsed.

[0029] In step S3, the control unit 90 causes the chemical loop combustion apparatus 1 to perform reduction suppression operation. Next, in step S4, it is determined whether the conditions for switching from reduction suppression operation to normal operation have been met. If the conditions have not been met, the process returns to step S3 and continues with reduction suppression operation. On the other hand, if the conditions for switching have been met, the process proceeds to step S1 and normal operation is started. The conditions for switching operations may be met when an operator performs an operation switching operation, or they may be met after a predetermined amount of time has elapsed.

[0030] [Normal operation] Figure 3 is a diagram illustrating the normal operation of the chemical loop combustion apparatus 1. In normal operation, the control unit 90 supplies air to the air tower 10 via the supply port IG from the air tower gas supply unit 70. This air causes the metal particles MP to react with oxygen (contained in the air) inside the air tower 10, resulting in oxidation. This oxidation of the metal particles MP generates heat of oxidation. In this embodiment, since the metal particles MP are ilmenite, the oxidation of the metal particles MP inside the air tower 10 is represented by the following equation (1). 8FeTiO3+2O2→4Fe2TiO5+4TiO2…(1) The reaction represented by equation (1) above generates heat. In addition, oxygen is removed from the air during this reaction, resulting in the generation of high-concentration nitrogen gas as exhaust gas. This high-concentration nitrogen gas is expelled from the cyclone 20 through the upper part of the cyclone 20 in the direction of gravity. For the reaction represented by equation (1) above to proceed at a sufficient reaction rate, a temperature of 800°C or higher is required. The gas supplied from the supply port IG does not have to be air. It may contain oxygen, or it may be oxygen alone.

[0031] Furthermore, in normal operation, the control unit 90 causes the fuel tower gas supply unit 80 to supply hydrocarbon fuel to the fuel tower 40 via the supply port IF. Hydrocarbon fuel is a fuel that generates carbon dioxide and water upon combustion, and is not limited to hydrocarbons composed only of carbon and hydrogen atoms, but may also be a compound containing atoms other than carbon and hydrogen atoms (for example, oxygen atoms). In this embodiment, methane (CH4) is used as the hydrocarbon fuel. Alcohols such as methanol and ethanol may also be used as the hydrocarbon fuel. Inside the fuel tower 40, the metal particles MP are reduced by reacting with the hydrocarbon fuel. This reduction of the metal particles MP generates a gas containing only carbon dioxide and water. In this embodiment, since the metal particles MP are ilmenite, the reduction of the metal particles MP inside the fuel tower 40 is represented by the following equation (2). 4Fe2TiO5+4TiO2+CH4→8FeTiO3+CO2+2H2O…(2) To promote the reaction represented by formula (2) above, an electric heater may be provided to heat the inside of the fuel tower 40. The gas (containing only carbon dioxide and water) generated by the reaction represented by the above formula (2) is discharged to the outside of the fuel tower 40 from the upper part of the fuel tower 40 in the direction of gravity.

[0032] [Reduction suppression operation] Figure 4 is a diagram illustrating the reduction suppression operation performed by the chemical loop combustion apparatus 1. When performing reduction suppression operation, the control unit 90 causes the air tower gas supply unit 70 to supply air to the air tower 10 via the supply port IG. The supply of air to the air tower 10 is for causing a similar reaction to occur with the metal particles MP and for oxidation, so a detailed explanation is omitted. Furthermore, when performing reduction suppression operation, the control unit 90 does not have to supply gas to the air tower 10 by controlling the air tower gas supply unit 70.

[0033] Furthermore, when performing reduction suppression operation, the control unit 90 instructs the fuel tower gas supply unit 80 to supply hydrocarbon fuel and air to the fuel tower 40 via the supply port IF. Figure 5 is a flowchart of the control of the fuel supply amount to the fuel tower 40 performed by the control unit 90 during reduction suppression operation. During reduction suppression operation, the control unit 90 determines the amount of fuel to be supplied to the fuel tower 40 based on the information shown in Figure 5. When reduction suppression operation starts, the control unit 90 first acquires information regarding the internal temperature of the fuel tower 40 measured by the temperature measurement unit 41 in step S31. Next, in step S32, the control unit 90 uses the internal temperature of the fuel tower 40 and the following equation (3) to determine the fuel supply amount Q to the fuel tower 40. FR _ fuel Determine (t). This fuel supply amount Q FR _ fuel (t) is updated at predetermined time intervals (Δt in Figure 5). Also, the amount of air supplied is greater than the amount of air required for the complete combustion of the fuel supplied to the fuel tower 40.

number

[0034] In reduction-suppressed operation, by supplying more air to the fuel tower 40 than the amount of fuel required for complete combustion, much of the fuel is consumed by the combustion of oxygen and other elements in the air rather than by the reaction with metal particles MP. This makes it possible to raise the internal temperature of the fuel tower 40 to 800°C or higher, which is the condition required for the reaction represented by equation (1) to proceed at a sufficient reaction rate. Under these conditions, the air that was not consumed in the reaction between the metal particles MP and the fuel undergoes the reaction represented by equation (1), resulting in the oxidation of much of the metal particles MP even within the fuel tower 40. Therefore, in reduction-suppressed operation, oxidation of the metal particles MP proceeds not only in the reaction in the air tower 10, but also in the reaction in the fuel tower 40.

[0035] [Degree of reduction of metal particles] Figure 6 is a diagram illustrating the degree of reduction of metal particles MP used in the chemical loop combustion apparatus 1. In the graph of Figure 6, the vertical axis represents the degree of reduction of metal particles MP, and the horizontal axis represents time. When the chemical loop combustion device 1 is started and operating under normal conditions, if the oxidation reaction of metal particles MP lags behind the reduction reaction, the increase in the degree of reduction due to the reduction reaction inside the air tower 10 will exceed the decrease in the degree of reduction due to the oxidation reaction inside the fuel tower 40. Therefore, as shown in Figure 6, as the metal particles MP undergo repeated oxidation and reduction reactions during normal operation of the chemical loop combustion device 1, the degree of reduction of the metal particles MP will gradually increase. Furthermore, when reduction suppression operation is performed in the chemical loop combustion apparatus 1, as described above, the metal particles MP are oxidized in the air tower 10 and the fuel tower 40. Therefore, as shown in Figure 6, if reduction suppression operation is performed for a certain period of time, the reduction of the metal particles MP progresses, and the degree of reduction decreases to a value close to that at the start of operation.

[0036] Continuing normal operation gradually increases the reduction rate of metal particles (MP), and as this progresses, it eventually becomes impossible to reduce the MP, leading to an increase in the unburned rate. However, by performing reduction-suppressed operation, the reduction rate of metal particles (MP) can be reduced to a value close to that at the start of operation, thereby suppressing the increase in the unburned rate of metal particles (MP).

[0037] [Examples of reduction suppression operation] Figure 7 is a diagram illustrating and explaining a modified example of the reduction suppression operation performed by the chemical loop combustion apparatus 1. The chemical loop combustion apparatus 1 of the first embodiment may, under control from the control unit 90, perform the reduction suppression operation shown in Figure 4, or the reduction suppression operation shown in Figure 7 (hereinafter referred to as reduction suppression operation A).

[0038] When performing reduction suppression operation A, the control unit 90 instructs the fuel tower gas supply unit 80 to supply hydrocarbon fuel and air to the fuel tower 40 via the supply port IF. The amount of fuel supplied to the fuel tower 40 is calculated using Equation 3 above, based on the flowchart in Figure 5, similar to the reduction suppression operation. The amount of air supplied is also greater than the amount of air required for the complete combustion of the fuel supplied to the fuel tower 40. Therefore, in reduction suppression operation A, the same reaction as in reduction suppression operation takes place in the fuel tower 40.

[0039] Furthermore, when performing reduction suppression operation A, the control unit 90 causes the air tower gas supply unit 70 to supply fuel and air to the air tower 10 via the supply port IG. The amount of fuel supplied to the air tower 10 may be determined under the same control as the amount of fuel supplied to the fuel tower 40, or it may be determined under different control. Therefore, in reduction suppression operation A, metal particles MP are oxidized not only in the fuel tower 40 but also in the air tower 10, and reduction is suppressed.

[0040] In other words, even when performing reduction suppression operation A, the degree of reduction of metal particles MP can be reduced to a value close to that at the start of operation, thereby suppressing the increase in the unburned rate of metal particles MP.

[0041] <Second Embodiment> [Configuration of Chemical Loop Combustion Device 1A] Figure 8 is an explanatory diagram illustrating the configuration of a chemical loop combustion system 1A as a second embodiment of the present invention. Similar to the chemical loop combustion apparatus 1 of the first embodiment, the chemical loop combustion system 1A is a system that generates heat through an oxidation reaction using metal particles MP circulating within the apparatus, and generates carbon dioxide and the like through a reduction reaction using metal particles MP circulating within the apparatus.

[0042] The chemical loop combustion system 1A comprises an air tower 10, a cyclone 20, a first loop seal section 30, a fuel tower 40A, a second loop seal section 50, a circulation pipe 60, a dewaterer DH, an air tower gas supply section 70, a fuel tower gas supply section 80, and a control section 90A. Note that the following description will focus on configurations different from those of the chemical loop combustion apparatus 1 of the first embodiment, and will omit descriptions of similar configurations.

[0043] The fuel tower 40A is equipped with a temperature measuring unit 41 and a heater 42, and is connected to the first loop seal unit 30 via a first pipe 61, which will be described later. The fuel tower reacts metal particles MP oxidized in the air tower 10 with hydrocarbon fuel to reduce the metal particles MP and discharges the gas generated by the reduction of the metal particles MP. The fuel tower 40 is provided with a supply port IF for supplying gas such as hydrocarbon fuel into the fuel tower 40. A pipe (not shown) for circulating the gas is connected to the supply port IF, and the gas supplied from the fuel tower gas supply unit, which will be described later, is supplied into the fuel tower 40 via the supply port IF.

[0044] The temperature measuring unit 41 is capable of measuring the internal temperature of the fuel tower 40, and this temperature information is acquired by the control unit 90, which will be described later.

[0045] The heater 42, under the control of the control unit 90A, heats the inside of the fuel tower 40A in the reduction suppression operation B described later, in order to promote the reaction of metal particles MP.

[0046] The control unit 90A is composed of an ECU (Electronic Control Unit) and controls the chemical loop combustion system 1A. The control unit 90A controls the type and amount of gas supplied by the air tower gas supply unit 70 to the air tower 10, the type and amount of gas supplied by the fuel tower gas supply unit 80 to the fuel tower 40, and the amount of heating by the heater 42 to heat the inside of the fuel tower 40A. The control unit 90A controls the chemical loop combustion system 1A and can perform control to make it operate in two modes: normal operation and reduction suppression operation B. The switching control between normal operation and reduction suppression operation B is controlled based on the flowchart shown in Figure 2, similar to the control unit 90 in the first embodiment. Furthermore, for normal operation, the control unit 90A performs the same control on the chemical loop combustion device 1 as in the first embodiment.

[0047] [Reduction suppression operation B] Figure 9 is a diagram illustrating the reduction suppression operation B performed by the chemical loop combustion apparatus 1A. When performing reduction suppression operation B, the control unit 90A causes the air tower gas supply unit 70 to supply air to the air tower 10 via the supply port IG. The supply of air to the air tower 10 is for causing a similar reaction to occur with the metal particles MP and for oxidation, so a detailed explanation is omitted.

[0048] Furthermore, when performing reduction suppression operation B, the control unit 90A controls the fuel tower gas supply unit 80 and the heater 42 so that the reaction represented by formula (1) above takes place inside the fuel tower 40A with respect to the metal particles MP. Therefore, the control unit 90A causes the fuel tower gas supply unit 80 to supply to the fuel tower 40, via the supply port IF, an amount of air sufficient to allow the metal particles MP to carry out the reaction represented by the above formula (1). Furthermore, the control unit 90A instructs the heater 42 to heat the fuel tower 40 so that the internal temperature of the fuel tower 40 reaches 800°C or higher, which is the condition required for the reaction represented by the above formula (1) to proceed at a sufficient reaction rate.

[0049] In reduction suppression operation B, the supply of air to the fuel tower 40A and the heating of the inside of the fuel tower 40A by the heater 42 cause the metal particles MP and the supplied air to undergo the reaction represented by the above formula (1), resulting in the oxidation of most of the metal particles MP even inside the fuel tower 40. Therefore, in reduction-suppressed operation B, oxidation of the metal particles MP proceeds not only in the reaction in the air tower 10 but also in the reaction in the fuel tower 40A, and reduction is suppressed.

[0050] In other words, by performing reduction suppression operation B, the degree of reduction of metal particles MP can be reduced to a value close to that at the start of operation, thereby suppressing the increase in the unburned rate of metal particles MP.

[0051] Furthermore, when performing reduction suppression operation B, the control unit 90A does not need to control the air tower gas supply unit 70 to supply gas to the air tower 10. Alternatively, in reduction suppression operation B, the control unit 90A may also supply fuel and air to the air tower 10 via the supply port IG through the air tower gas supply unit 70, similar to reduction suppression operation A performed by the chemical loop combustion device 1 of the first embodiment. In this case, the amount of fuel supplied to the air tower 10 may be determined under the same control as the amount of fuel supplied to the fuel tower 40 in reduction suppression operation A, or it may be determined under different control. Even when this control is performed, in reduction suppression operation B, metal particles MP will be oxidized and reduction will be suppressed not only in the fuel tower 40A but also in the air tower 10.

[0052] [Variation of reduction suppression operation B] In the second embodiment, the chemical loop combustion apparatus 1A may, under control from the control unit 90A, perform reduction suppression operation C instead of reduction suppression operation B shown in Figure 9. In reduction suppression operation C, the control unit 90A causes the air tower gas supply unit 70 to supply air to the air tower 10 via the supply port IG. The supply of air to the air tower 10 is for the same reaction to occur with the metal particles MP and to cause oxidation, so a detailed explanation is omitted. Note that when performing reduction suppression operation, the control unit 90 does not have to control the air tower gas supply unit 70 to supply gas to the air tower 10.

[0053] Furthermore, in reduction suppression operation C, the control unit 90 causes the heater 42 to heat. Also, the control unit 90A does not supply air to the fuel tower 40A via the supply port IF. This keeps the internal conditions of the fuel tower 40A away from conditions that are conducive to the reduction of metal particles MP. As a result, in reduction suppression operation C, the reduction of metal particles MP is suppressed in the fuel tower 40A.

[0054] When reduction suppression operation C is performed, the metal particles MP are oxidized inside the air tower 10, and further reduction inside the fuel tower 40A is suppressed. Therefore, when reduction suppression operation C is performed, oxidation proceeds for most of the metal particles MP. In other words, even when reduction suppression operation C is performed, the degree of reduction of the metal particles MP can be reduced to a value close to that at the start of operation, and the increase in the unburned rate of the metal particles MP can be suppressed.

[0055] Furthermore, when performing reduction suppression operation C, the control unit 90A does not need to control the air tower gas supply unit 70 to supply gas to the air tower 10. Alternatively, in reduction suppression operation C, the control unit 90A may also supply fuel and air to the air tower 10 via the supply port IG through the air tower gas supply unit 70, similar to reduction suppression operation A performed by the chemical loop combustion device 1 of the first embodiment. In this case, the amount of fuel supplied to the air tower 10 may be determined under the same control as the amount of fuel supplied to the fuel tower 40 in reduction suppression operation A, or it may be determined under different control. Even when this control is performed, in reduction suppression operation C, metal particles MP will be oxidized and reduction will be suppressed not only in the fuel tower 40A but also in the air tower 10.

[0056] Based on the above, in the chemical loop combustion apparatus 1 and 1A, the control units 90 and 90A control the air tower gas supply unit 70 and the fuel tower gas supply unit 80 to supply air to the air tower 10, oxidize the metal particles by reaction with the air, and supply fuel to the fuel towers 40 and 40A, reducing the metal particles MP by reaction with the fuel. They also perform predetermined operations, known as reduction suppression operation and reduction suppression operation A to C, by controlling the air tower gas supply unit 70 and the fuel tower gas supply unit 80 to suppress the reduction of metal particles MP by oxidation in the fuel towers 40 and 40A. Therefore, the metal particles MP circulating in the chemical loop combustion apparatus 1 are oxidized, the degree of reduction of metal particles MP which has increased due to normal operation can be reduced, and the increase in the unburned rate of metal particles MP can be suppressed.

[0057] Furthermore, during reduction suppression operation and reduction suppression operations A to C, the control unit 90 controls the fuel tower gas supply unit 80 to supply air to the fuel towers 40 and 40A to oxidize the metal particles MP. Therefore, during reduction suppression operation and reduction suppression operations A to C, the metal particles MP are oxidized not only inside the air tower 10 but also inside the fuel towers 40 and 40A. In other words, the circulating metal particles MP are oxidized throughout the entire chemical loop combustion device 1. Consequently, the degree of reduction of the metal particles MP, which has increased during normal operation, can be reduced, and the increase in the unburned metal particles MP can be further suppressed.

[0058] Furthermore, in reduction suppression operation and reduction suppression operation A, the control unit 90 controls the fuel tower gas supply unit 80 to supply air for oxidizing metal particles MP and fuel to the fuel tower 40, and the amount of air supplied to the fuel tower 40 is greater than the amount necessary for the complete combustion of the fuel. Therefore, conditions are created inside the fuel tower 40 that make it easier for metal particles MP to oxidize, and as the metal particles MP are oxidized more, the metal particles MP circulating in the chemical loop combustion device 1 are oxidized, which reduces the degree of reduction of metal particles MP that has increased during normal operation, and further suppresses the increase in the unburned rate of metal particles MP.

[0059] Furthermore, the chemical loop combustion apparatus 1 is equipped with a temperature measuring unit 41 for measuring the internal temperature of the fuel tower 40, and the control unit 90 changes the amount of fuel supplied to the fuel tower 40 based on the above equation (3) according to the internal temperature of the tower measured by the temperature measuring unit 41 during reduction suppression operation and reduction suppression operation A. As a result, the internal temperature of the fuel tower 40 can be maintained at a temperature at which metal particles MP are more easily oxidized, and because the metal particles MP are more oxidized, the metal particles MP circulating in the chemical loop combustion apparatus 1 are oxidized, which reduces the degree of reduction of metal particles MP that has increased due to normal operation, and further suppresses the increase in the unburned rate of metal particles MP.

[0060] Furthermore, in reduction suppression operation A, the control unit 90 controls the air tower gas supply unit 70 and supplies fuel to the air tower 10. Therefore, conditions are created inside the air tower 10 that make it easier for the metal particles MP to oxidize, and as the metal particles MP are oxidized more, the metal particles MP circulating in the chemical loop combustion device 1 are oxidized, which reduces the degree of reduction of the metal particles MP that has increased due to normal operation, and further suppresses the increase in the unburned rate of the metal particles MP.

[0061] <Modified examples of embodiments> The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit, for example, the following modifications are also possible.

[0062] [Example 1] In reduction suppression operation, reduction suppression operation A, and reduction suppression operation B, the air supplied to the inside of fuel towers 40 and 40A does not have to be air, as long as it has the effect of oxidizing metal particles.

[0063] [Differentiation 2] While ilmenite particles were used as the material for the metal particles MP, this is not the only option. For example, instead of iron, materials containing copper, nickel, etc., may be used.

[0064] The embodiments of this specification have been described above based on the embodiments and modifications described above. The embodiments described above are for the purpose of facilitating understanding of this specification and do not limit it. This specification may be modified and improved without departing from its spirit and the scope of the claims, and equivalents thereof are included in this specification. Furthermore, any technical features that are not described as essential in this specification may be deleted as appropriate.

[0065] The present invention can also be realized in the following forms. [Application Example 1] A control device for controlling a chemical loop combustion apparatus, The chemical loop combustion apparatus comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, and a fuel tower gas supply unit for supplying gas to the fuel tower. The control device is A first control system controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidizing the metal particles through reaction with the air, and supplying fuel to the fuel tower, reducing the metal particles through reaction with the fuel. A second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of the metal particles in the fuel tower, To do, A control device characterized by the following features. [Application Example 2] The control device described in Application Example 1, In the second control described above, Control the fuel tower gas supply unit to supply air to the fuel tower for oxidizing the metal particles. A control device characterized by the following features. [Application Example 3] The control device described in Application Example 2, In the second control described above, The fuel tower gas supply unit is controlled to supply the fuel tower with the fuel and an amount of air greater than the amount required for the complete combustion of the fuel. A control device characterized by the following features. [Application Example 4] The control device described in Application Example 3, The aforementioned chemical loop combustion apparatus is equipped with a temperature measuring unit for measuring the temperature inside the fuel tower, which is the temperature inside the fuel tower. In the second control described above, The amount of fuel supplied to the fuel tower is changed according to the temperature inside the tower. A control device characterized by the following features. [Application Example 5] A control device described in any one of Application Examples 1 to 4, In the second control described above, Controlling the air tower gas supply unit and supplying the fuel to the air tower, A control device characterized by the following features. [Application Example 6] A chemical loop combustion device, The system comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, a fuel tower gas supply unit for supplying gas to the fuel tower, and a control device as described in any one of Application Examples 1 to 4. A chemical loop combustion apparatus characterized by the following features. [Application Example 7] A method for controlling a chemical loop combustion apparatus, The chemical loop combustion apparatus comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, and a fuel tower gas supply unit for supplying gas to the fuel tower. A first control system controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidizing the metal particles through reaction with the air, and supplying a predetermined fuel to the fuel tower, reducing the metal particles through reaction with the fuel. A second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of the metal particles in the fuel tower, To do, A control method for a chemical loop combustion apparatus, characterized by the following features. [Explanation of Symbols]

[0066] 1.1A...Chemical Loop Combustion System 10...Air tower 20...Cyclone 30...First loop seal section 40,40A…Fuel tower 41...Temperature measurement unit 42... Heater 50...Second loop seal section 60...Circulation piping 61...First piping 62...Second piping 70... Air tower gas supply section 80…Fuel Tower Gas Supply Section 90, 90A... Control Unit MP…metal particles DH…Dehydrator IF... Supply port IG…supply port

Claims

1. A control device for controlling a chemical loop combustion apparatus, The chemical loop combustion apparatus comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, and a fuel tower gas supply unit for supplying gas to the fuel tower. The control device is A first control system controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidizing the metal particles through reaction with the air, and supplying fuel to the fuel tower, reducing the metal particles through reaction with the fuel. A second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of the metal particles in the fuel tower, To do, A control device characterized by the following features.

2. A control device according to claim 1, In the second control described above, Control the fuel tower gas supply unit to supply air to the fuel tower for oxidizing the metal particles. A control device characterized by the following features.

3. A control device according to claim 2, In the second control described above, The fuel tower gas supply unit is controlled to supply the fuel tower with the fuel and an amount of air greater than the amount required for the complete combustion of the fuel. A control device characterized by the following features.

4. A control device according to claim 3, The aforementioned chemical loop combustion apparatus is equipped with a temperature measuring unit for measuring the temperature inside the fuel tower, which is the temperature inside the fuel tower. In the second control described above, The amount of fuel supplied to the fuel tower is changed according to the temperature inside the tower. A control device characterized by the following features.

5. A control device according to any one of claims 1 to 4, In the second control described above, Controlling the air tower gas supply unit and supplying the fuel to the air tower, A control device characterized by the following features.

6. A chemical loop combustion device, The system comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, a fuel tower gas supply unit for supplying gas to the fuel tower, and a control device according to any one of claims 1 to 4. A chemical loop combustion apparatus characterized by the following features.

7. A method for controlling a chemical loop combustion apparatus, The chemical loop combustion apparatus comprises an air tower, an air tower gas supply unit for supplying gas to the air tower, a fuel tower, and a fuel tower gas supply unit for supplying gas to the fuel tower. A first control system controls the air tower gas supply unit and the fuel tower gas supply unit to supply air to the air tower, oxidize the metal particles by reaction with the air, and supply a predetermined fuel to the fuel tower, reducing the metal particles by reaction with the fuel. A second control that controls the air tower gas supply unit and the fuel tower gas supply unit to perform a predetermined operation that suppresses the reduction of the metal particles in the fuel tower, To do, A control method for a chemical loop combustion apparatus, characterized by the following features.

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