Carbon dioxide capture device

Abstract

To provide a carbon dioxide capture device that can reduce energy consumption. [Solution] The carbon dioxide recovery device 10A comprises a carbon dioxide absorption tower 11A, a carbon dioxide emission tower 12 connected to the carbon dioxide absorption tower 11A, a first solution pump 33 that supplies carbon dioxide absorption solution to the carbon dioxide emission tower 12, and a temperature control device 17A that adjusts the temperature of the internal atmosphere of the carbon dioxide emission tower 12. The first solution pump 33 adjusts the amount of carbon dioxide absorption solution supplied according to at least one of the flow rate of the target gas supplied to the carbon dioxide absorption tower 11A and the carbon dioxide concentration of the target gas. The temperature control device 17A maintains a constant internal atmosphere or solution temperature in the carbon dioxide absorption tower 11A so that carbon dioxide is released from the carbon dioxide absorption solution.

Description

Technical Field

[0001] The present invention relates to a carbon dioxide recovery device.

Background Art

[0002] Conventionally, a carbon dioxide recovery device for recovering carbon dioxide from a gas generated in a gas source such as combustion equipment is known. The carbon dioxide recovery device includes a carbon dioxide absorption tower that absorbs carbon dioxide contained in the gas into a carbon dioxide absorption solution, and a carbon dioxide release tower that releases carbon dioxide from the carbon dioxide absorption solution by heating the carbon dioxide absorption solution. The carbon dioxide absorption tower and the carbon dioxide release tower are configured such that the carbon dioxide absorption solution circulates.

[0003] Patent Document 1 and Patent Document 2 disclose a carbon dioxide recovery device that heats a carbon dioxide absorption solution using water vapor. The carbon dioxide recovery devices disclosed in these documents are configured to determine the circulation amount of the carbon dioxide absorption solution for achieving a target recovery rate of carbon dioxide according to the carbon dioxide concentration of the gas, and to determine the amount of water vapor according to the determined circulation amount. And these patent documents describe that energy reduction can be achieved by such a configuration.

[0004] In such a carbon dioxide recovery device, when the amount of energy required for operation increases, the amount of carbon dioxide that can be actually recovered by the carbon dioxide recovery device decreases. Therefore, reduction of the energy consumed by the carbon dioxide recovery device for recovering carbon dioxide is required.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] (Problems that the invention aims to solve) In view of the above circumstances, one of the objectives of the present invention is to provide a carbon dioxide capture device that can reduce the energy consumed to capture carbon dioxide (in other words, improve energy efficiency).

[0007] (Means for solving the problem) To solve the above problems, the carbon dioxide capture device of this disclosure is A carbon dioxide absorption tower is configured such that carbon dioxide contained in gas supplied from an external gas source is absorbed by a carbon dioxide absorption solution, A carbon dioxide emission tower is connected to the carbon dioxide absorption tower so that the carbon dioxide absorption solution that has absorbed carbon dioxide in the carbon dioxide absorption tower can flow into it. A solution supply device configured to circulate the carbon dioxide absorption solution between the carbon dioxide absorption tower and the carbon dioxide emission tower, The system includes a temperature control device configured to adjust the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower, The solution supplying device adjusts at least one of the amount of carbon dioxide absorption solution supplied from the carbon dioxide absorption tower to the carbon dioxide emission tower and the amount of carbon dioxide absorption solution supplied from the carbon dioxide emission tower to the carbon dioxide absorption tower, according to at least one of the flow rate of the gas supplied from the gas source to the carbon dioxide absorption tower and the carbon dioxide concentration of the gas. The temperature control device releases heat into the carbon dioxide emission tower so that the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower remains constant.

[0008] The carbon dioxide recovery device of the present invention adjusts the flow rate of the carbon dioxide absorption solution supplied to the carbon dioxide evaporation tower in response to fluctuations in at least one of the flow rate of the gas supplied from the gas source and the carbon dioxide concentration of the gas (in other words, fluctuations in the amount of carbon dioxide that can be recovered from the gas per unit time). Furthermore, the carbon dioxide recovery device of the present invention maintains a constant temperature of the internal atmosphere of the carbon dioxide evaporation tower. When the flow rate of the carbon dioxide absorption solution supplied to the carbon dioxide evaporation tower decreases, the amount of heat required to maintain a constant temperature of the internal atmosphere of the carbon dioxide evaporation tower or the temperature of the solution decreases, thus reducing the energy consumption of the carbon dioxide recovery device. Therefore, according to the present invention, it is possible to provide a carbon dioxide recovery device that can reduce energy consumption (in other words, improve energy efficiency). [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram showing an example of the configuration of a carbon dioxide capture device according to the first embodiment. [Figure 2] Figure 2 is a timing chart showing the operation of the carbon dioxide capture device according to the first embodiment. [Figure 3] Figure 3 is a schematic diagram showing an example of the configuration of a carbon dioxide capture device according to the second embodiment. [Figure 4] Figure 4 is a schematic diagram showing an example of the configuration of a carbon dioxide capture device according to the third embodiment. [Figure 5] Figure 5 is a schematic diagram showing an example of the configuration of a carbon dioxide absorption tower in a carbon dioxide recovery system according to the third embodiment. [Figure 6] Figure 6 is a timing chart showing the operation of the carbon dioxide capture device according to the third embodiment. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below. In the following description, the carbon dioxide capture device will be abbreviated as "capture device," the carbon dioxide absorption tower as "absorption tower," the carbon dioxide emission tower (sometimes called a "carbon dioxide regeneration tower") as "emission tower," and the carbon dioxide absorption solution as "solution." In addition, the gas that is the target of carbon dioxide capture by the capture device (i.e., the gas containing carbon dioxide) will be referred to as the "target gas."

[0011] The target gas source 90 is a device or facility that generates gas containing carbon dioxide. Specifically, the target gas source 90 can be a metal melting furnace or carburizing furnace that utilizes the combustion heat of fossil fuels (i.e., uses fossil fuels as fuel). In this case, the combustion exhaust gas of fossil fuels is the target gas. An aqueous amine solution is used as the solution.

[0012] <First Embodiment> Figure 1 is a diagram showing the schematic configuration of the recovery device 10A according to the first embodiment. The recovery device 10A includes an absorption tower 11A, a dispersion tower 12, a target gas introduction path 13, a target gas discharge path 14, a first solution path 15, a second solution path 16, a temperature control device 17A, a carbon dioxide recovery path 18, and a control device 19.

[0013] The absorption tower 11A is configured to absorb carbon dioxide (in other words, to remove carbon dioxide from the target gas) by bringing the solution and the target gas into gas-liquid contact. Inside the absorption tower 11A, an upper packing material 111 and a lower packing material 112 are arranged. Both the upper packing material 111 and the lower packing material 112 are materials through which liquid (specifically the solution) can permeate and gas (specifically the target gas) can pass. For example, porous metals or mesh-like materials with a large specific surface area are used. The upper packing material 111 is located near the top of the absorption tower 11A, and the lower packing material 112 is located below it. The lower packing material 112 is a material that promotes gas-liquid contact between the target gas and the solution. One end of the second solution path 16 is connected to the upper part of the absorption tower 11A, between the upper packing material 111 and the lower packing material 112, and one end of the first solution path 15 is connected to the bottom (or near the bottom) of the absorption tower 11A, below the lower packing material 112. Furthermore, the configuration of the absorption tower 11A is not particularly limited, and conventionally known configurations can be applied.

[0014] The target gas introduction path 13 is a path for supplying the target gas generated in the target gas source 90 to the absorption tower 11A. One end of the target gas introduction path 13 is connected to the lower end of the absorption tower 11A or its vicinity. The other end of the target gas introduction path 13 is connected to the target gas source 90. A target gas pump 31 and a target gas flow meter 32 are installed on the target gas introduction path 13. The target gas pump 31 is configured to supply (pressure-feed) the target gas from the other end of the target gas introduction path 13 (the side of the target gas source 90) to the one end (the side of the absorption tower 11A). A known electric air pump can be used for the target gas pump 31. The target gas flow meter 32 can continuously measure the flow rate of the target gas flowing through the target gas introduction path 13 in real time. The configuration of the target gas flow meter 32 is not particularly limited, and a conventionally known flow meter capable of measuring the flow rate of gases can be used.

[0015] The target gas discharge path 14 is a path for discharging the target gas (sometimes called off-gas) after carbon dioxide has been absorbed in the absorption tower 11A to the outside of the absorption tower 11A. One end of the target gas discharge path 14 is connected to the upper end of the absorption tower 11A or its vicinity and is above the upper packing material 111, while the other end is opened to the atmosphere, for example.

[0016] The first solution path 15 is a path for supplying the solution from the absorption tower 11A to the evaporation tower 12. One end of the first solution path 15 is connected to the lower part of the absorption tower 11A, and the other end is connected to the upper part of the evaporation tower 12. A first solution pump 33, a first solution flow meter 151, and a solution heat exchanger 34 are provided on the first solution path 15. The first solution pump 33 is an example of a solution supply device of the present invention. The first solution pump 33 is configured to supply the solution from the absorption tower 11A to the evaporation tower 12 when it operates. The configuration of the first solution pump 33 is not particularly limited, and various conventionally known electric liquid supply pumps can be applied. The solution heat exchanger 34 is configured to exchange heat between the solution flowing through the first solution path 15 and the solution flowing through the second solution path 16, which will be described later. In the solution heat exchanger 34, heat is exchanged between the solution flowing through the first solution path 15 and the solution flowing through the second solution path 16, thereby heating the solution flowing through the first solution path 15 and cooling the solution flowing through the second solution path 16. The configuration of the solution heat exchanger 34 is not limited, and conventionally known heat exchangers capable of heat exchange between liquids can be used.

[0017] The stripping tower 12 is configured such that carbon dioxide is stripped from the solution by heating the solution. Inside the stripping tower 12, an upper packing material 121 and a lower packing material 122 are arranged. Both the upper packing material 121 and the lower packing material 122 are members through which the solution can penetrate and gases (vapor and carbon dioxide) can pass. For example, porous metals or mesh-like members with a large specific surface area are applicable. The lower packing material 122 is a member for promoting the gas-liquid contact between the solution and the vapor generated by heating the solution. The upper packing material 121 is arranged near the top of the stripping tower 12, and the lower packing material 122 is arranged below it. At the upper part of the stripping tower 12, between the upper packing material 121 and the lower packing material 122, the other end of the first solution path 15 is connected, and at the bottom of the stripping tower 12 or near it, below the lower packing material 122, the other end of the second solution path 16 is connected. Note that the configuration of the stripping tower 12 is not particularly limited, and a conventionally known configuration can be applied.

[0018] A stripping tower thermometer 123 is provided in the stripping tower 12. The stripping tower thermometer 123 is configured to be able to continuously measure the temperature of the internal atmosphere of the stripping tower 12 in real time. Note that the stripping tower thermometer 123 may be configured to be able to measure the temperature of the solution present (pooled at the bottom) inside the stripping tower 12.

[0019] The temperature adjustment device 17A is configured to be able to adjust the temperature of the internal atmosphere of the diffusion tower 12 or the temperature of the solution existing inside the diffusion tower 12 by releasing heat inside the diffusion tower 12. In the present embodiment, an example in which the temperature adjustment device 17A is configured to be able to adjust the temperature of the solution existing inside the diffusion tower 12 is shown. And, the temperature adjustment device 17A can adjust the temperature of the internal atmosphere of the diffusion tower 12 by adjusting the temperature of the solution existing inside the diffusion tower 12. The temperature adjustment device 17A includes a temperature control medium path 171, a high-temperature medium path 172, a first heat exchanger 173, a second heat exchanger 174, and a temperature control medium pump 175. The temperature control medium path 171 is a closed-loop path configured such that the temperature control medium, which is a fluid, can circulate. The temperature control medium pump 175 is provided on the temperature control medium path 171. And, the temperature adjustment device 17A is configured such that the temperature control medium circulates through the temperature control medium path 171 by the operation of the temperature control medium pump 175. Note that the temperature control medium pump 175 is configured to be able to change the flow rate of the temperature control medium. The configuration of the temperature control medium pump 175 is not particularly limited, and various conventionally known liquid transfer pumps are applicable.

[0020] The high-temperature medium path 172 is a path configured such that a high-temperature medium, which is a fluid supplied from the outside and has a high temperature (higher than the temperature at which the reaction in which the solution releases carbon dioxide occurs), can pass through. The first heat exchanger 173 is provided on the temperature control medium path 171 and the high-temperature medium path 172. And, the first heat exchanger 173 is configured to perform heat exchange between the temperature control medium flowing (circulating) through the temperature control medium path 171 and the high-temperature medium flowing through the high-temperature medium path 172. The second heat exchanger 174 is provided on the temperature control medium path 171. Also, the second heat exchanger 174 is provided at a position near the bottom inside the diffusion tower 12 and immersed in the solution accumulated inside the diffusion tower 12. And, the second heat exchanger 174 is configured to perform heat exchange between the temperature control medium flowing through the temperature control medium path 171 and the solution existing inside the diffusion tower 12. The configurations of the first heat exchanger 173 and the second heat exchanger 174 are not particularly limited, and various conventionally known heat exchangers can be applied.

[0021] In this configuration of the temperature control device 17A, the temperature-controlled medium is heated in the first heat exchanger 173 by the heat of a high-temperature medium supplied from the outside, and the solution inside the diffusion tower 12 is heated in the second heat exchanger 174 by the heat of the temperature-controlled medium. The temperature of the internal atmosphere of the diffusion tower 12 is then adjusted by the heat of the heated solution. As the high-temperature medium, for example, a fluid (more specifically, oil) heated by the waste heat of a target gas source can be used. In this case, the target gas source 90 is provided with a heat exchanger (not shown) that heats the high-temperature medium by heat exchange between the waste heat and the high-temperature medium. The high-temperature medium path 172 is connected to the heat exchanger of the target gas source 90, and the temperature control device 17A is configured so that the high-temperature medium heated in the heat exchanger of the target gas source 90 passes through the high-temperature medium path 172 to the first heat exchanger 173 of the temperature control device 17A.

[0022] The second heat exchanger 174 may be configured to exchange heat between the temperature-controlled medium and the gas (air and solution vapor) present inside the diffusion tower 12. For example, the second heat exchanger 174 may be configured to be in direct contact with the internal atmosphere of the diffusion tower 12 without being immersed in the solution present inside the diffusion tower 12. In this case, the temperature control device 17A can directly adjust the temperature of the internal atmosphere of the diffusion tower 12 without adjusting the temperature of the solution. Thus, the temperature control device 17A only needs to be configured to adjust the temperature of the internal atmosphere of the diffusion tower 12 or the temperature of the solution present inside the diffusion tower 12. The temperature control device 17A can also be configured to adjust the temperature of the internal atmosphere of the diffusion tower 12 directly or indirectly through the solution present inside the diffusion tower 12.

[0023] One end of the carbon dioxide recovery path 18 is connected to the top (or near the top) of the diffusion tower 12, above the upper packing material 121. On the carbon dioxide recovery path 18, in order from the side closest to the diffusion tower 12, are a demister 41, a mixture cooler 42, and a gas-liquid separator 43. The demister 41 is configured to remove mist of the solution vapor from the mixture of the solution vapor and carbon dioxide, and to return the condensed water produced by the removed mist back to the diffusion tower 12. The mixture cooler 42 is configured to liquefy the solution vapor by cooling the mixture of the solution vapor and carbon dioxide. The gas-liquid separator 43 is configured to separate the solution and carbon dioxide produced by the liquefaction of the vapor. With this configuration, gaseous carbon dioxide can be separated from the mixture of solution vapor and carbon dioxide flowing into the carbon dioxide recovery path 18. The separated carbon dioxide is discharged (recovered) outside the recovery device 10A. The gas-liquid separator 43 and the diffusion tower 12 are connected by a solution reflux path 44. This solution reflux path 44 is configured so that the solution separated from carbon dioxide in the gas-liquid separator 43 returns to the evaporation tower 12.

[0024] The second solution path 16 is a path for supplying the solution from the evaporation tower 12 to the absorption tower 11A. One end of the second solution path 16 is connected to the top of the absorption tower 11A, and the other end of the second solution path 16 is connected to the bottom of the evaporation tower 12. The second solution pump 35, the aforementioned solution heat exchanger 34, the solution cooler 161, and the second solution flow meter 162 are provided on the second solution path 16.

[0025] The second solution pump 35 is also an example of a solution supply device of the present invention. The second solution pump 35 is configured to supply the solution accumulated inside (specifically at the bottom) of the evaporation tower 12 to the absorption tower 11A through the second solution path 16. A known electric liquid supply pump can be used for the second solution pump 35. The solution cooler 161 is configured to regulate (cool) the temperature of the solution supplied to the absorption tower 11A to the temperature at which the reaction for absorbing carbon dioxide occurs. Various known coolers (heat sinks) can be used for the solution cooler 161. The second solution flow meter 162 is configured to continuously measure the flow rate of the solution flowing through the second solution path 16 in real time.

[0026] The control device 19 is connected to the target gas pump 31, the first solution pump 33, the second solution pump 35, and the temperature-regulating medium pump 175, and can control these devices. The control device 19 is also connected to the target gas flow meter 32, the first solution flow meter 151, the second solution flow meter 162, and the diffusion tower thermometer 123, and can continuously acquire measurement results from these measuring instruments in real time. The control device 19 is a device including a computer with a CPU, RAM, ROM, and an I / F. The ROM contains a computer program for controlling the recovery device 10A, including the aforementioned devices. The CPU reads the computer program stored in the ROM, loads it into the RAM (using the RAM as a work area), and executes it. This enables control of the recovery device 10A.

[0027] Next, the basic operation of the recovery device 10A will be explained. The target gas generated in the target gas source 90 is supplied (pressurized) to the absorption tower 11A by the operation of the target gas pump 31. The target gas that flows into the absorption tower 11A passes sequentially through the lower packing material 112 and the upper packing material 111. In addition, the solution that has been heated (cooled) to a temperature suitable for carbon dioxide absorption in the solution heat exchanger 34 and the solution cooler 161 flows into the absorption tower 11A through the second solution path 16 by the operation of the second solution pump 35. The solution that flows into the absorption tower 11A passes through the lower packing material 112 and accumulates at the bottom of the absorption tower 11A. Then, the solution flowing down and the target gas rising in the lower packing material 112 come into gas-liquid contact (countercurrent contact), and the carbon dioxide contained in the target gas is absorbed into the solution. Also, the carbon dioxide loading value increases as the solution passes through the lower packing material 112. That is, the solution changes from a carbon dioxide lean state to a carbon dioxide rich state.

[0028] The target gas (off-gas) from which carbon dioxide has been removed is discharged to the outside of the absorption tower 11A through the target gas discharge path 14. The solution accumulated at the bottom of the absorption tower 11A is sent from the absorption tower 11A to the diffusion tower 12 through the first solution path 15 by the operation of the first solution pump 33. The solution flowing through the first solution path 15 is heated by heat exchange with the solution flowing through the second solution path 16 in the solution heat exchanger 34, and then flows into the diffusion tower 12.

[0029] The solution flowing into the diffusion tower 12 passes through the lower packing material 122 and then accumulates at the bottom of the diffusion tower 12. The solution accumulated at the bottom of the diffusion tower 12 is heated by heat exchange with the temperature control medium in the second heat exchanger 174 of the temperature control device 17A, and a portion of the heated solution evaporates. The generated steam rises from the bottom of the diffusion tower 12 and passes through the lower packing material 122. The steam then comes into gas-liquid contact (countercurrent contact) with the solution flowing down from the top of the lower packing material 122. As a result, the solution flowing down the lower packing material 122 is heated, and carbon dioxide is released from the solution.

[0030] The mixture of carbon dioxide released from the solution and the remaining vapor that did not liquefy passes through the upper packing material 121 and flows into the carbon dioxide recovery path 18 from the top of the diffusion tower 12. The upper packing material 121 is a porous or mesh-like material. Therefore, as the mixture passes through the upper packing material 121, some of the mist contained in the mixture is removed.

[0031] In the demister 41 located in the carbon dioxide recovery path 18, steam mist is removed from the mixture flowing into the carbon dioxide recovery path 18. Furthermore, the mixture is cooled in the mixture cooler 42, causing the steam to condense (liquefy). Then, in the gas-liquid separator 43, the mixture is separated into gaseous carbon dioxide and liquid solution. The carbon dioxide separated in the gas-liquid separator 43 is discharged to the outside via the carbon dioxide recovery path 18. In other words, carbon dioxide is recovered through the carbon dioxide recovery path 18. On the other hand, the solution separated in the gas-liquid separator 43 returns to the evaporation tower 12 via the solution reflux path 44 and flows down the upper packing material 121. This cools the upper packing material 121, thus promoting the condensation of steam contained in the mixture passing through the upper packing material 121.

[0032] The solution accumulated at the bottom of the evaporation tower 12 is supplied from the evaporation tower 12 to the absorption tower 11A via the second solution path 16 by the operation of the second solution pump 35. The solution flowing through the second solution path 16 is cooled by heat exchange with the solution flowing through the first solution path 15 in the solution heat exchanger 34, and is further cooled in the solution cooler 161. As a result, the solution reaches a temperature suitable for carbon dioxide absorption. After that, the solution flows into the absorption tower 11A.

[0033] In this way, the solution circulates in the order of absorption tower 11A, first solution path 15, decongestion tower 12, and second solution path 16 through the operation of the first solution pump 33 and the second solution pump 35. As the solution circulates, it repeatedly absorbs carbon dioxide contained in the target gas in absorption tower 11A and releases the absorbed carbon dioxide in decongestion tower 12. The carbon dioxide released from the solution in decongestion tower 12 is discharged from recovery device 10A through carbon dioxide recovery path 18.

[0034] Next, the specific operation of the recovery device 10A will be explained. In the following explanation, "recovered energy" refers to the energy consumed by the recovery device 10A to recover a unit mass of carbon dioxide (=(energy consumed by the recovery device 10A (J)) / (mass of carbon dioxide recovered (t))). A smaller value for recovered energy is preferable. Unless otherwise specified, "flow rate" and "heat quantity" refer to "flow rate per unit time" and "heat quantity per unit time," respectively.

[0035] The control device 19 controls the output of the target gas pump 31 according to the operating status of the target gas source 90. For example, when the target gas source 90 is not operating, the control device 19 reduces the output of the target gas pump 31 compared to when the target gas source 90 is operating. As a result, the flow rate of the target gas supplied from the target gas source 90 may fluctuate over time depending on the operating status of the target gas source 90. The carbon dioxide concentration of the supplied target gas may also fluctuate over time depending on the operating status of the target gas source 90. When the flow rate of the target gas supplied from the target gas source 90 decreases, when the carbon dioxide concentration of the target gas decreases, or both, the amount of carbon dioxide that can be recovered per unit time from the target gas decreases. As a result, if the energy consumption of the recovery device 10A is constant, the value of the recovered energy will increase in any of the above cases.

[0036] The control device 19 controls the flow rate of the solution according to the flow rate of the target gas supplied to the absorption tower 11A. The specific control is as follows: The control device 19 continuously acquires the measurement results of the flow rate of the target gas from the target gas flow meter 32 (i.e., the measurement results of the flow rate of the target gas supplied to the diffusion tower 12) in real time. The control device 19 then controls the output of the first solution pump 33 and the second solution pump 35 so that the flow rate of the solution (the flow rate of the solution supplied from the absorption tower 11A to the diffusion tower 12 (supply amount), and the flow rate of the solution supplied from the diffusion tower 12 to the absorption tower 11A (supply amount)) approaches (typically matches) the target flow rate determined according to the acquired measurement results of the target gas flow rate. Specifically, the control device 19 controls the output of the first solution pump 33 using the measurement results acquired from the first solution flow meter 151 and controls the output of the second solution pump 35 using the measurement results acquired from the second solution flow meter 162. Therefore, at least one of the flow rate (amount supplied) of solution delivered from the absorption tower 11A to the evaporation tower 12 and the flow rate (amount supplied) of solution delivered from the evaporation tower 12 to the absorption tower 11A is adjusted by at least one of the first solution pump 33 and the second solution pump 35.

[0037] Furthermore, in conjunction with the above control, the control device 19 controls the operation of the temperature control device 17A (i.e., the heat released into the diffuser 12 by the temperature control device 17A) so that the temperature of the internal atmosphere of the diffuser 12 reaches a predetermined target temperature. Specifically, the control device 19 continuously acquires the measurement results of the internal atmosphere temperature of the diffuser 12 from the diffuser thermometer 123 in real time. The control device 19 then controls (feedback control) the output of the temperature conditioning medium pump 175 of the temperature control device 17A (i.e., the flow rate of the temperature conditioning medium) so that the temperature of the internal atmosphere of the diffuser 12 approaches (typically matches) the target temperature. For example, if the temperature of the internal atmosphere of the diffuser 12 becomes higher than the target temperature, the control device 19 reduces the output of the temperature conditioning medium pump 175 (reduces the flow rate of the temperature conditioning medium). In other words, it reduces the heat released into the diffuser 12. Furthermore, if the temperature of the internal atmosphere of the diffusion tower 12 falls below the target temperature, the output of the temperature-regulating medium pump 175 is increased (the flow rate of the temperature-regulating medium is increased). In other words, the amount of heat released into the interior of the diffusion tower 12 is increased.

[0038] The control device 19 may also control the operation of the temperature control device 17A so that the temperature of the solution inside the diffusion tower 12 is maintained at a predetermined target temperature. The target temperature of the solution is the temperature at which the internal atmosphere temperature of the diffusion tower 12 can be maintained at "the temperature at which the reaction in which carbon dioxide is released from the solution occurs (the aforementioned target temperature of the internal atmosphere)" by the heat of the solution. In this case, the diffusion tower thermometer 123 is configured to measure the temperature of the solution inside the diffusion tower 12. The control device 19 then controls (feedback control) the output of the temperature control medium pump 175 of the temperature control device 17A (i.e., the flow rate of the temperature control medium) so that the temperature of the solution inside the diffusion tower 12 approaches (typically matches) the target temperature. For example, the control device 19 reduces the output of the temperature-regulating medium pump 175 (decreases the flow rate of the temperature-regulating medium) when the temperature of the solution inside the diffusion tower 12 rises above the target temperature, and increases the output of the temperature-regulating medium pump 175 (increases the flow rate of the temperature-regulating medium) when the temperature of the solution inside the diffusion tower 12 falls below the target temperature.

[0039] The target flow rate of the solution (the flow rate (amount supplied) of the solution sent from the absorption tower 11A to the evaporation tower 12, and the flow rate (amount supplied) of the solution sent from the evaporation tower 12 to the absorption tower 11A) is a value determined according to the flow rate of the target gas. Furthermore, the read / write flow rate of the solution is a value determined to have a positive correlation with the flow rate of the target gas. The specific value of the target flow rate of the solution is not limited and is set appropriately according to the properties of the solution (type and concentration of solute), etc. The target temperature of the internal atmosphere of the evaporation tower 12 is the temperature at which carbon dioxide can be released from the solution flowing down the lower packing material 112 (in other words, the temperature at which a reaction that releases carbon dioxide can be generated). If the second heat exchanger 174 of the temperature control device 17A is configured to heat the solution (a configuration that exchanges heat between the temperature control medium and the solution), the specific value is set appropriately according to the components of the solution (type and concentration of solute), etc. In this embodiment, the target temperature of the internal atmosphere of the diffusion tower 12 (or the target temperature of the solution) is a constant value (fixed value).

[0040] The target flow rate of the solution and the target temperature of the internal atmosphere of the diffusion tower 12 (or the target temperature of the solution) are pre-stored in the ROM of the control device 19's computer. In this case, the control device 19 reads and uses the target flow rate of the solution and the target temperature of the internal atmosphere of the diffusion tower 12 from the ROM. Alternatively, a calculation formula for determining the target flow rate of the solution from the flow rate of the target gas (for example, a function with the flow rate of the target gas as a variable) may be pre-stored in the ROM of the control device 19. In this case, the control device 19 calculates (determines) the target flow rate of the solution by applying the measurement result of the end of the target gas flow obtained from the target gas flow meter 32 to this calculation formula.

[0041] Thus, the control device 19 reduces the flow rate of the solution when the flow rate of the target gas supplied from the target gas source 90 decreases. This reduces the amount (flow rate) of solution supplied from the absorption tower 11A to the diffusion tower 12. When the amount of solution supplied to the diffusion tower 12 decreases, the amount of heat supplied to the solution necessary to maintain the temperature of the internal atmosphere of the diffusion tower 12 (or the target temperature of the solution) at the target temperature also decreases. In this case, the control device 19 reduces the flow rate of the temperature-regulating medium flowing through the temperature-regulating medium path 171. As a result, the amount of heat that the temperature-regulating medium receives from the high-temperature medium in the temperature control device 17A (i.e., the energy consumed by the temperature control device 17A) decreases. Therefore, with this control, it is possible to prevent or suppress an increase in the value of recovered energy when the flow rate of the target gas supplied from the target gas source 90 decreases.

[0042] Figure 2 is a timing chart showing a specific example of the operation of the recovery device 10A. In Figure 2, in addition to the control according to this embodiment, the operation of steady-state control and liquid volume control are also shown as comparative examples. Steady-state control is a control that maintains a constant flow rate of the solution and the amount of heat supplied to the solution regardless of the flow rate of the target gas. Liquid volume control adjusts the flow rate of the solution according to the flow rate of the target gas, but maintains a constant amount of heat supplied to the solution regardless of the flow rate of the target gas. In each timing chart, time points T1 and T3 indicate the point in time when the flow rate of the target gas decreases, and time points T2 and T4 indicate the point in time when the flow rate of the target gas increases (the point in time when it returns to the flow rate before the decrease). For example, the period up to time point T1, the period from time point T2 to time point T3, and the period from time point T4 onwards are periods when the target gas source 90 is in operation, and the period from time point T1 to time point T2, and the period from time point T3 to time point T4 are periods when the target gas source 90 is not in operation.

[0043] In steady-state control, the flow rate of the solution is kept constant regardless of the flow rate of the target gas. Therefore, as shown in Figure 2, during periods when the flow rate of the target gas decreases (specifically, the period from time T1 to time T2, and the period from time T3 to time T4), the carbon dioxide concentration in the solution (loading value) decreases. When the flow rate of the solution is constant and the carbon dioxide concentration in the solution decreases, the amount of carbon dioxide recovered per unit time from the target gas decreases. Also, under steady-state control, the amount of heat supplied to the solution in the diffusion tower 12 is kept constant. Therefore, under steady-state control, the recovered energy during periods when the flow rate of the target gas decreases is greater than during other periods. Furthermore, the average value of the recovered energy is greater than the value of the recovered energy during periods when the flow rate of the target gas does not decrease.

[0044] In flow rate control, when the flow rate of the target gas decreases, the flow rate of the solution is reduced in accordance with the flow rate of the target gas. Therefore, flow rate control can reduce the energy consumption of the first solution pump 33 and the second solution pump 35. Consequently, flow rate control can reduce energy consumption compared to steady-state control. In other words, the average value of recovered energy under flow rate control (shown as a dashed line labeled "Ave" in the figure) can be made smaller than the average value of recovered energy under steady-state control. However, although the concentration of carbon dioxide in the solution is maintained at a nearly constant level, the flow rate of the solution decreases, so the amount of carbon dioxide recovered per unit time from the target gas decreases during these periods. Furthermore, under flow rate control, even when the flow rate of the solution decreases, the amount of heat supplied to the solution in the diffusion tower 12 is maintained at a constant level. Therefore, during periods when the flow rate of the target gas is decreasing, the recovered energy is greater than during other periods, similar to steady-state control.

[0045] Furthermore, the reaction in which the solution releases carbon dioxide is an endothermic reaction. Therefore, under steady-state control, the amount of heat absorbed by the solution decreases during periods when the solution flow rate decreases. And, since the amount of heat supplied to the solution in the radiating column 12 is constant, the temperature of the solution inside the radiating column 12 rises during these periods, as shown in Figure 2. Also, under flow rate control, the amount of heat absorbed per unit mass of the solution increases during periods when the solution flow rate decreases. Therefore, as shown in Figure 2, the temperature of the amine aqueous solution inside the radiating column 12 rises during periods when the solution flow rate decreases.

[0046] In contrast, according to the control of this embodiment, the flow rate of the solution is adjusted according to the flow rate of the target gas, and the temperature of the internal atmosphere of the diffusion tower 12 is maintained at a constant level. Therefore, during periods when the flow rate of the solution is decreasing, the energy consumption of the first solution pump 33 and the second solution pump 35 can be reduced, and the amount of heat supplied to the solution can be reduced. In this embodiment, the amount of heat supplied to the solution is reduced by reducing the flow rate of the high-temperature medium. With this configuration, as shown in Figure 2, the value of recovered energy can be reduced compared to steady-state operation and liquid flow control. In particular, compared to liquid flow control, it is possible to prevent or suppress the increase in the value of recovered energy during periods when the flow rate is decreasing, thus reducing the recovered energy.

[0047] The above description illustrates a control method in which the target flow rate is set according to the flow rate of the target gas supplied from the target gas source 90, but the system is not limited to this configuration. For example, the control method may adjust the flow rate of the solution according to the carbon dioxide concentration of the target gas supplied from the target gas source 90. In this case, a carbon dioxide concentration meter is installed on the target gas introduction path 13 instead of the target gas flow meter 32. The control device 19 then continuously acquires the measurement results of the carbon dioxide concentration of the target gas from the carbon dioxide concentration meter in real time and sets the target flow rate of the solution according to the acquired measurement results. In this case, the value of the target flow rate of the solution is set to have a positive correlation with the carbon dioxide concentration. That is, the target flow rate is defined to increase when the carbon dioxide concentration increases and decrease when the carbon dioxide concentration decreases.

[0048] Furthermore, the control device 19 may also control the target flow rate according to both the flow rate of the target gas supplied from the target gas source 90 and the carbon dioxide concentration of the target gas. In this case, a carbon dioxide concentration meter is provided on the target gas introduction path 13 in addition to the target gas flow meter 32. The control device 19 then continuously acquires the measurement results of the flow rate of the target gas from the target gas flow meter 32 and the measurement results of the carbon dioxide concentration of the target gas from the carbon dioxide concentration meter in real time, and sets the target flow rate according to the acquired measurement results. In this case, the value of the target flow rate is set to have a positive correlation with the flow rate of the target gas and the carbon dioxide concentration. That is, the target flow rate is set to increase when the flow rate of the target gas increases and to decrease when the flow rate of the target gas decreases. Also, the target flow rate is set to increase when the carbon dioxide concentration increases and to decrease when the carbon dioxide concentration decreases.

[0049] Furthermore, in this case, the control device 19 may calculate the carbon dioxide flow rate from the measurement results of the flow rate of the target gas by the target gas flow meter 32 and the measurement results of the carbon dioxide concentration of the target gas by the carbon dioxide concentration meter, and set a target flow rate according to the calculated carbon dioxide flow rate. In this case, the value of the target flow rate is set to have a positive correlation with the carbon dioxide flow rate. That is, the target flow rate is set to increase when the carbon dioxide flow rate increases and to decrease when the carbon dioxide flow rate decreases.

[0050] Thus, the control device 19 is configured to control the flow rate of the solution according to at least one of the flow rate of the target gas and the carbon dioxide content of the target gas.

[0051] <Second Embodiment> Next, a second embodiment will be described. Figure 3 is a schematic diagram showing the configuration of the recovery device 10B according to the second embodiment. Compared to the recovery device 10A according to the first embodiment, the recovery device 10B according to the second embodiment differs in the configuration and control of the temperature control device 17B. In the following description, components common to the first embodiment will be denoted by the same reference numerals as in the first embodiment, and their descriptions may be omitted.

[0052] As shown in Figure 3, the temperature control device 17B comprises a high-temperature medium path 172, a third heat exchanger 177, and a high-temperature medium pump 178. The high-temperature medium path 172 is a path configured to allow the high-temperature medium supplied from outside the recovery device 10B to flow through. The third heat exchanger 177 is located on the high-temperature medium path 172 and inside the diffusion tower 12, and is configured to allow heat exchange between the high-temperature medium and the solution inside the diffusion tower 12. The high-temperature medium pump 178 can adjust the flow rate of the high-temperature medium flowing through the high-temperature medium path 172 (or, more precisely, through the third heat exchanger 177) under control from the control device 19.

[0053] Similar to the first embodiment, the control device 19 acquires the measurement results of the flow rate of the target gas by the target gas flow meter 32 in real time and controls the output of the first solution pump 33 and the second solution pump 35 so that the flow rate of the solution approaches the target flow rate corresponding to the measurement results. In addition, the control device 19 continuously acquires the measurement results of the temperature of the internal atmosphere of the diffusion tower 12 by the diffusion tower thermometer 123 in real time and controls the output of the high-temperature medium pump 178 so that the temperature of the internal atmosphere of the diffusion tower 12 remains constant. This adjusts the flow rate of the high-temperature medium flowing through the third heat exchanger 177.

[0054] Thus, in order to maintain a constant temperature of the internal atmosphere of the diffusion tower 12, the control device 19 of the recovery device 10B according to the second embodiment controls (adjusts) the output of the high-temperature medium pump 178 (flow rate of high-temperature medium). Specifically, the control device 19 increases the output of the high-temperature medium pump 178 (increases the flow rate of high-temperature medium) when the temperature of the internal atmosphere of the diffusion tower 12 falls below the target temperature, and decreases the output of the high-temperature medium pump 178 (decreases the flow rate of high-temperature medium) when the temperature of the internal atmosphere of the diffusion tower 12 reaches the target temperature. This is a difference from the first embodiment, which controls (adjusts) the output of the temperature-regulating medium pump 175 (flow rate of temperature-regulating medium). Otherwise, the operation is the same as the first embodiment. Furthermore, the fluctuation of the solution flow rate when the flow rate of the target gas decreases, the carbon dioxide concentration of the solution, the amount of heat supplied to the solution inside the diffusion tower 12, and the time course of the recovered energy are the same as in the first embodiment (see Figure 2). And, according to the recovery device 10B according to the second embodiment, the same effects as the recovery device 10A according to the first embodiment can be achieved.

[0055] <Third Embodiment> Next, a third embodiment will be described. Figure 4 is a schematic diagram showing the configuration of the recovery device 10C according to the third embodiment. Figure 5 is a schematic cross-sectional view showing the configuration of the absorption tower 11C of the recovery device 10C according to the third embodiment. The recovery device 10C according to the third embodiment differs from the recovery devices 10A and 10B according to the first and second embodiments in the configuration of the absorption tower 11C. Otherwise, the same configuration as the first or second embodiment can be applied. In the following description, components common to the first or second embodiment will be denoted by the same reference numerals as in the first or second embodiment. Also, the description of components common to the first or second embodiment may be omitted. In the following description, the recovery device 10C is shown to have a temperature control device 17A with the same configuration as the recovery device 10A according to the first embodiment, but it may also have a temperature control device 17B with the same configuration as the recovery device 10B according to the second embodiment.

[0056] As shown in Figure 5, a rotating body 60 is arranged inside the absorption tower 11C so as to be rotatable about an axis that is approximately parallel to the vertical direction. In Figure 5, the upper side is indicated by the arrow Up and the lower side by the arrow Dw. The rotating body 60 rotates due to the driving force output by the rotational drive source 62. The rotational drive source 62 is controlled by the control device 19.

[0057] The rotating body 60 includes a gas-liquid contact section 61. The gas-liquid contact section 61 is a component that promotes the absorption of carbon dioxide by the solution. The gas-liquid contact section 61 can also be described as a component that increases the contact area between the solution and the target gas. The gas-liquid contact section 61 comprises a housing 611 that is substantially cylindrical and has a space formed inside, and a filler material 612 that fills the inside of the housing 611. An opening (through hole) is provided in the center of the top plate of the housing 611, and the ends of the second solution path 16 and the target gas discharge path 14 are located at this opening. That is, the internal space of the housing 611 communicates with the second solution path 16 and the target gas discharge path 14 through the opening (through hole) in the center of the top plate. In addition, the side plates and bottom plate of the housing 611 are configured to allow gas and liquid to pass through. For example, the side plates and bottom plate of the housing 611 are formed of perforated metal. The filler material 612 is configured to allow the solution to penetrate and diffuse inside, and to allow the target gas to flow inside. For example, the filler 612 may be a metal component with a large specific surface area (more specifically, a porous component, a mesh component, or a cotton-like component).

[0058] The flow of the solution and target gas in the absorption tower 11C equipped with the rotating body 60 configured in this way is as follows. In Figure 5, solid arrows schematically show the flow of the solution, and dashed arrows schematically show the flow of the target gas. The solution supplied via the second solution path 16 flows into the packing material 612 filling the housing 611 of the gas-liquid contact portion 61 from near the center of rotation on the upper surface of the gas-liquid contact portion 61 of the rotating body 60. The solution that has flowed into the packing material 612 permeates and diffuses downward and radially outward of the gas-liquid contact portion 61 due to gravity and the centrifugal force of the rotation of the rotating body 60. The solution that has passed through the inside of the packing material 612 then flows out of the gas-liquid contact portion 61 from the side or bottom surface of the housing 611 and temporarily accumulates at the bottom of the absorption tower 11C.

[0059] The target gas, which flows into the absorption tower 11C through the target gas introduction path 13, enters the housing 611 of the gas-liquid contact section 61 from the outer circumferential surface and the bottom surface of the housing 611 of the gas-liquid contact section 61, and passes through the inside of the packing material 612. Subsequently, the target gas flows into the target gas discharge path 14 from the opening in the upper plate of the housing 611 and is discharged to the outside of the absorption tower 11C through the target gas discharge path 14. As the target gas passes through the inside of the packing material 612, it comes into contact with the solution diffusing and permeating inside the packing material 612, and the carbon dioxide contained in the target gas is absorbed by the solution.

[0060] As the rotating body 60 rotates, the centrifugal force causes the solution to diffuse and penetrate into the packing material 612 of the gas-liquid contact area 61, thus increasing the surface area of ​​gas-liquid contact at the gas-liquid contact area 61. Furthermore, as the rotational speed of the rotating body 60 increases, the relative velocity between the target gas and the solution at the gas-liquid contact area 61 increases, resulting in more opportunities for the target gas to come into contact with the solution. Therefore, as the rotational speed of the rotating body 60 increases, the solution becomes more likely to absorb carbon dioxide contained in the target gas (in other words, more carbon dioxide is absorbed by the solution).

[0061] The operation of the control device 19 of the recovery device 10C is the same as in the first or second embodiment, except that control of the rotational speed of the rotating body 60 (output of the rotational drive power source 62) is added. In the recovery device 10C according to the third embodiment, the control device 19 controls (adjusts) the rotational speed of the rotating body 60 according to the flow rate of the target gas (measurement result by the target gas flow meter 32). Specifically, the control device 19 increases the rotational speed of the rotating body 60 when the flow rate of the target gas increases, and decreases the rotational speed of the rotating body 60 when the flow rate of the target gas decreases. That is, the control device 19 controls the output of the rotational drive power source 62 (rotational speed of the rotating body 60) so that the rotational speed of the rotating body 60 has a positive correlation with the flow rate of the target gas. The rotational speed of the rotating body 60 according to the flow rate of the target gas is stored in advance in the ROM of the computer of the control device 19. The CPU of the computer of the control device 19 reads the rotational speed of the rotating body 60 from the ROM and uses it to control the rotational drive power source 62.

[0062] Figure 6 is a timing chart showing the operation of the recovery device 10C. Similar to the timing chart in Figure 2, the period from time T1 to time T2, and the period from time T3 to time T4, indicate the period during which the flow rate of the target gas decreased.

[0063] As shown in Figure 6, the fluctuations in the solution flow rate, the carbon dioxide concentration in the solution, the amount of heat supplied to the solution inside the diffusion tower 12, and the time course of recovered energy when the flow rate of the target gas decreases are the same as in the first embodiment (see Figure 2). During the period when the flow rate of the target gas decreases (the period from time T1 to time T2, and the period from time T3 to time T4), the rotation speed of the rotating body 60 is reduced compared to other periods. With this control, during the period when the flow rate of the target gas is low, the energy required to operate the drive source can be reduced without reducing the amount of carbon dioxide absorbed by the solution. Therefore, a decrease in the energy efficiency of the recovery device 10C can be prevented or suppressed. With this configuration, the same effects as in the first or second embodiment can be achieved.

[0064] <Summary of Embodiments> (1) The carbon dioxide recovery devices 10A, 10B, and 10C according to this embodiment are: A carbon dioxide absorption tower (absorption tower 11A, 11C) is configured such that carbon dioxide contained in the gas (target gas) supplied from an external gas source (target gas source 90) is absorbed by a carbon dioxide absorption solution (solution), A carbon dioxide emission tower (emission tower 12) is connected to the carbon dioxide absorption towers (absorption towers 11A, 11C) so that the carbon dioxide absorption solution (solution) that has absorbed carbon dioxide in the carbon dioxide absorption towers (absorption towers 11A, 11C) can flow into it. A solution supply device (first solution pump 33, second solution pump 35) is configured to circulate the carbon dioxide absorption solution (solution) between the carbon dioxide absorption towers (absorption towers 11A, 11C) and the carbon dioxide emission tower (emission tower 12), Temperature control devices 17A and 17B are configured to adjust the internal atmosphere of the carbon dioxide emission tower (emission tower 12) or the temperature of the carbon dioxide absorption solution present inside the carbon dioxide emission tower (emission tower 12), Equipped with, The solution supply device (first solution pump 33, second solution pump 35) adjusts at least one of the amount of carbon dioxide absorption solution (solution) supplied from the carbon dioxide absorption tower (absorption tower 11A, 11C) to the carbon dioxide emission tower (emission tower 12) and the amount of carbon dioxide absorption solution supplied from the carbon dioxide emission tower (emission tower 12) to the carbon dioxide absorption tower (absorption tower 11A, 11C) according to at least one of the flow rate of the gas (target gas) supplied from the gas source (target gas source 90) to the carbon dioxide absorption tower (absorption tower 11A, 11C) and the carbon dioxide concentration of the gas (target gas). The temperature control devices 17A and 17B release heat into the carbon dioxide emission tower (emission tower 12) so that the temperature of the internal atmosphere of the carbon dioxide emission tower (emission tower 12) or the carbon dioxide absorption solution (solution) present inside the carbon dioxide emission tower (emission tower 12) becomes constant.

[0065] The carbon dioxide recovery device (recovery device 10A, 10B, 10C) of the present invention reduces the flow rate of the carbon dioxide absorption solution (solution) supplied to the carbon dioxide emission tower (emission tower 12) when at least one of the flow rate of the gas (target gas) supplied from the gas source (target gas source 90) or the carbon dioxide concentration of the gas (target gas) decreases (in other words, when the amount of carbon dioxide that can be recovered per unit time from the gas (target gas) decreases). On the other hand, the carbon dioxide recovery device (recovery device 10A, 10B, 10C) of the present invention ensures that the temperature of the internal atmosphere of the carbon dioxide emission tower (emission tower 12) or the temperature of the solution present inside the carbon dioxide emission tower (emission tower 12) remains constant (target temperature). When the flow rate of the carbon dioxide absorption solution (solution) supplied to the carbon dioxide evaporation tower (diffusion tower 12) decreases, the amount of heat required to maintain a constant temperature of the internal atmosphere of the carbon dioxide evaporation tower (diffusion tower 12) or the temperature of the solution inside the carbon dioxide evaporation tower (diffusion tower 12) decreases. Therefore, the amount of energy required to operate the carbon dioxide recovery device (recovery device 10A, 10B, 10C) can be reduced. Accordingly, according to the present invention, it is possible to provide a carbon dioxide recovery device (recovery device 10A, 10B, 10C) that can reduce energy consumption (in other words, improve energy efficiency).

[0066] (2) The temperature control device 17A is A temperature control medium path 171 is configured to allow the temperature control medium (temperature control medium) to circulate, A heat exchanger (first heat exchanger 173) is provided on the temperature control medium path 171 and configured to adjust the temperature of the temperature control medium (temperature control medium) by heat exchange between the high-temperature medium supplied from the outside and the temperature control medium (temperature control medium), A heat emitter (second heat exchanger 174) is provided on the temperature control medium path 171 and configured to release the heat contained in the temperature control medium (temperature control medium) into the carbon dioxide emission tower (emission tower 12), A temperature-regulating medium circulation device (temperature-regulating medium pump 175) is configured to circulate the temperature-regulating medium (temperature-regulating medium) through the temperature-regulating medium path 171, Equipped with, The temperature-regulating medium circulation device (temperature-regulating medium pump 175) adjusts the flow rate of the temperature-regulating medium (temperature-regulating medium) circulating through the temperature-regulating medium path 171 according to the temperature of the internal atmosphere of the carbon dioxide emission tower (emission tower 12) or the temperature of the carbon dioxide absorption solution (solution) present inside the carbon dioxide emission tower (emission tower 12).

[0067] With this configuration, the flow rate of the carbon dioxide absorption solution (solution) is reduced in at least one of the following cases: when the flow rate of the gas (target gas) decreases, or when the carbon dioxide concentration of the gas (target gas) decreases. When the flow rate of the carbon dioxide absorption solution (solution) decreases, the amount of heat required to maintain a constant temperature in the internal atmosphere of the carbon dioxide emission tower (emission tower 12) decreases, thus reducing the amount of heat transferred from the high-temperature medium to the temperature-regulating medium. Therefore, the energy consumption of the carbon dioxide recovery device (recovery device 10A) can be reduced.

[0068] (3) The temperature control device 17B is, A high-temperature medium path 172 is configured to allow a high-temperature medium supplied from an external source to flow through, A heat emitter (third heat exchanger 177) is provided on the high-temperature medium path 172 and is configured to release the heat contained in the high-temperature medium into the carbon dioxide emission tower (emission tower 12), A high-temperature medium circulation device (high-temperature medium pump 178) for circulating the high-temperature medium through the high-temperature medium path 172, Equipped with, The high-temperature medium flow device (high-temperature medium pump 178) adjusts the flow rate of the high-temperature medium flowing through the high-temperature medium path 172 according to the temperature of the internal atmosphere of the carbon dioxide emission tower (emission tower 12) or the carbon dioxide absorption solution (solution) present inside the carbon dioxide emission tower (emission tower 12).

[0069] With this configuration, the flow rate of the carbon dioxide absorption solution (solution) is reduced when either the flow rate of the gas (target gas) decreases or the carbon dioxide concentration of the gas (target gas) decreases. When the flow rate of the carbon dioxide absorption solution (solution) decreases, the amount of heat required to maintain a constant temperature inside the carbon dioxide emission tower (emission tower 12) decreases, thus reducing the amount of heat released from the high-temperature medium into the carbon dioxide emission tower (emission tower 12). Therefore, the energy consumption of the carbon dioxide recovery device (recovery device 10B) can be reduced.

[0070] (4) The carbon dioxide recovery device (recovery device 10C) according to this embodiment is A rotating body 60 is rotatably positioned inside the carbon dioxide absorption tower (absorption tower 11C), and is configured such that the carbon dioxide absorption solution (solution) supplied from the carbon dioxide emission tower (emission tower 12) permeates and diffuses into the interior, and the gas (target gas) supplied from the gas source (target gas source 90) passes through the interior. A rotational drive force source 62 for rotating the rotating body 60, Equipped with, The rotational drive source 62 controls the rotational speed of the rotating body 60 according to at least one of the flow rate of the gas (target gas) supplied from the gas source (target gas source 90) to the carbon dioxide absorption tower (absorption tower 11C) and the carbon dioxide concentration of the gas (target gas).

[0071] With this configuration, the flow rate of the carbon dioxide absorption solution (solution) is reduced when either the flow rate of the gas (target gas) decreases or the carbon dioxide concentration of the gas (target gas) decreases. When the flow rate of the carbon dioxide absorption solution (solution) decreases, the rotational speed of the rotating body 60 is reduced. Therefore, when the flow rate of the carbon dioxide absorption solution (solution) decreases, the energy consumed by the rotational drive power source 62 can be reduced, thereby reducing the energy consumption of the carbon dioxide recovery device (recovery device 10C).

[0072] Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to these embodiments. The present invention can be modified in various ways without departing from its spirit, and these modifications are also included within the technical scope of the present invention.

[0073] For example, in each of the embodiments described above, the recovery devices 10A, 10B, and 10C are equipped with a single control device 19, and this single control device 19 controls each of the devices included in the recovery devices 10A, 10B, and 10C (first solution pump 33, second solution pump 35, and intermediate solution pump 56). However, the present invention is not limited to such a configuration. For example, the recovery devices 10A, 10B, and 10C may be equipped with multiple control devices 19, and each of the multiple control devices 19 may control one or more of the multiple devices included in the recovery devices 10A, 10B, and 10C.

[0074] Furthermore, while each embodiment shows a configuration in which the flow rate of the solution is controlled according to the flow rate of the target gas, the present invention is not limited to such configurations. The flow rate of the solution may be controlled according to the carbon dioxide concentration of the target gas, or the flow rate of the solution may be controlled according to both the flow rate of the target gas and the carbon dioxide concentration of the target gas. In other words, any configuration in which the flow rate of the solution is controlled according to at least one of the flow rate of the target gas and the carbon dioxide concentration of the target gas is sufficient.

[0075] Furthermore, although each embodiment shows a configuration in which the temperature of the internal atmosphere of the diffusion tower 12 is controlled to be kept constant, a configuration in which the temperature of the solution present inside the diffusion tower 12 is controlled to be kept constant may also be used. [Explanation of Symbols]

[0076] 10A, 10B, 10C…Carbon dioxide capture device, 11A, 11C…Carbon dioxide absorption tower, 12…Carbon dioxide emission tower, 13…Target gas introduction route, 15…First solution route, 16…Second solution route, 17A, 17B…Temperature control device, 171…Temperature-controlled medium route, 172…High-temperature medium route, 173…First heat exchanger, 174…Second heat exchanger, 175…Temperature-controlled medium pump, 176…Temperature-controlled medium flow meter, 19…Control device, 33…First solution pump, 36…Second solution pump, 90…Target gas source

Claims

1. A carbon dioxide absorption tower is configured such that carbon dioxide contained in gas supplied from an external gas source is absorbed by a carbon dioxide absorption solution, A carbon dioxide emission tower is connected to the carbon dioxide absorption tower so that the carbon dioxide absorption solution that has absorbed carbon dioxide in the carbon dioxide absorption tower can flow into it. A solution supply device configured to circulate the carbon dioxide absorption solution between the carbon dioxide absorption tower and the carbon dioxide emission tower, A temperature control device configured to adjust the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower, Equipped with, The solution supplying device adjusts at least one of the amount of carbon dioxide absorption solution supplied from the carbon dioxide absorption tower to the carbon dioxide emission tower and the amount of carbon dioxide absorption solution supplied from the carbon dioxide emission tower to the carbon dioxide absorption tower, according to at least one of the flow rate of the gas supplied from the gas source to the carbon dioxide absorption tower and the carbon dioxide concentration of the gas. The temperature control device is a carbon dioxide recovery device that releases heat into the carbon dioxide emission tower so that the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower becomes constant.

2. A carbon dioxide recovery device according to claim 1, The temperature control device is A temperature control medium path configured to allow the temperature control medium to circulate, A heat exchanger is provided on the temperature control medium path and configured to adjust the temperature of the temperature control medium by heat exchange between a high-temperature medium supplied from the outside and the temperature control medium, A heat emitter provided on the temperature control medium path and configured to release the heat contained in the temperature control medium into the carbon dioxide emission tower, A temperature-regulating medium circulation device configured to circulate the temperature-regulating medium through the temperature-regulating medium path, Equipped with, The temperature-controlled medium circulation device adjusts the flow rate of the temperature-controlled medium circulating through the temperature-controlled medium path according to the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower. Carbon dioxide capture device.

3. A carbon dioxide recovery device according to claim 1, The temperature control device is A high-temperature medium pathway configured to allow the circulation of a high-temperature medium supplied from an external source, A heat emitter provided on the high-temperature medium path and configured to release the heat contained in the high-temperature medium into the interior of the carbon dioxide emission tower, A high-temperature medium circulation device for circulating the high-temperature medium through the high-temperature medium path, Equipped with, The high-temperature medium flow device adjusts the flow rate of the high-temperature medium flowing through the high-temperature medium path according to the temperature of the internal atmosphere of the carbon dioxide emission tower or the carbon dioxide absorption solution present inside the carbon dioxide emission tower. Carbon dioxide capture device.

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