Carbon dioxide recovery system

Abstract

To provide a carbon dioxide recovery system which can continuously acquire a state of diffusion of carbon dioxide absorbent solution during the operation thereof.SOLUTION: A carbon dioxide recovery system 10 comprises: a plurality of solution sensors 70 which are disposed on a prescribed cross section of a rotating body 60 where carbon dioxide absorbent solution can be permeated; a torque meter 67 which measures torque to rotate the rotating body 60; and a control unit 24. The control unit is configured to: calculate moment of inertia of the rotating body 60 based on the measured torque; estimate a two-dimensional shape at an area where the carbon dioxide absorbent solution exists on the cross section based on the detection result of the plurality of solution sensors 70; estimate a three-dimensional shape when the two-dimensional shape rotates; and calculate mass of the three-dimensional shape as total mass of the carbon dioxide absorbent solution contained in the rotating body 60 so that the inertial moment of the three-dimensional shape is equal to the difference between the inertial moment calculated from the measurement result of the torque meter 67 and the inertial moment of the rotating body 60 that does not contain the carbon dioxide absorbent solution.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a carbon dioxide capture system. [Background technology]

[0002] Conventionally, carbon dioxide capture systems that capture carbon dioxide from gas generated in a gas source such as a combustion facility have been known. The carbon dioxide capture system includes a carbon dioxide absorption tower that absorbs carbon dioxide contained in the gas into a carbon dioxide absorbing solution, and a carbon dioxide stripper tower that strips carbon dioxide from the carbon dioxide absorbing solution. The carbon dioxide capture system is configured so that the gas generated in the gas source is supplied to the carbon dioxide absorption tower, and so that the carbon dioxide absorbing solution circulates between the carbon dioxide absorption tower and the carbon dioxide stripper tower.

[0003] Patent Document 1 discloses a carbon dioxide capture system equipped with a carbon dioxide absorption tower (referred to as an "RPB absorption device" in Patent Document 1) with a rotatable rotor disposed inside. A filler is housed inside this rotor. Then, the centrifugal force of the rotor's rotation moves the carbon dioxide absorbing solution from the inner periphery to the outer periphery of the filler, and the carbon dioxide absorbing solution and the gas come into gas-liquid contact (countercurrent contact). As a result, the carbon dioxide contained in the gas is absorbed by the carbon dioxide absorbing solution.

[0004] The carbon dioxide capture rate in a carbon dioxide capture system is affected by the state of diffusion of the carbon dioxide absorbing solution inside the rotor. The state of diffusion of the carbon dioxide absorbing solution may fluctuate while the carbon dioxide capture system is in operation. Therefore, to maintain the performance of the carbon dioxide capture system and detect abnormalities, it is necessary to be able to grasp the state of diffusion of the carbon dioxide absorbing solution inside the rotor in real time.

[0005] Patent Document 1 discloses the L / G ratio (ratio of the flow rate of the carbon dioxide absorbing solution to the gas flow rate) suitable for the type of carbon dioxide absorbing solution experimentally defined to achieve a predetermined carbon dioxide recovery rate, the dimensions of the rotor, operating conditions, etc. However, Patent Document 1 does not disclose a configuration for understanding the state of diffusion of the carbon dioxide capture solution inside the rotor (filler) while the carbon dioxide capture system is operating. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2021-529083 Summary of the Invention

[0007] (Problem to be solved by the invention) In view of the above circumstances, one object of the present invention is to provide a carbon dioxide recovery system that can continuously acquire the state of diffusion of a carbon dioxide absorbing solution during operation.

[0008] (Means for solving the problem) The carbon dioxide capture system according to the present disclosure comprises: A carbon dioxide recovery system including a carbon dioxide absorption tower that absorbs carbon dioxide contained in a gas into a carbon dioxide absorbing solution by bringing a carbon dioxide absorbing solution supplied from an outside into gas-liquid contact with the gas containing carbon dioxide supplied from an outside, a rotor configured to allow the carbon dioxide absorbing solution to diffuse therein, disposed inside the carbon dioxide absorption tower, and rotated by a driving force output by a driving force source; and a plurality of solution sensors that are arranged at positions that are different from each other in distance from the rotation center line of the rotating body and in positions parallel to the rotation center line, and that detect the presence of the carbon dioxide absorbing solution.

[0009] According to the carbon dioxide capture system of the present disclosure, a rotating body is provided with multiple solution sensors, making it possible to provide a carbon dioxide capture system that can continuously acquire the state of diffusion of the carbon dioxide absorbing solution during operation based on the detection results of the multiple solution sensors. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a carbon dioxide capture system according to this embodiment. [Figure 2] FIG. 2 is a cross-sectional schematic diagram showing the configuration of the carbon dioxide absorption tower. [Figure 3A] FIG. 3A is an enlarged view of part IIIA in FIG. [Figure 3B] FIG. 3B is an enlarged view of part IIIB in FIG. [Figure 4] FIG. 4 is a partial cross-sectional view showing the configuration of the upper gas-liquid contact section and the upper gas-liquid separation section. [Figure 5] FIG. 5 is a diagram illustrating a method for estimating the mass of a solution. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described. In the following description, the carbon dioxide capture system will be abbreviated as the "capture system," the carbon dioxide absorption tower will be abbreviated as the "absorption tower," the carbon dioxide stripper tower (sometimes referred to as the "carbon dioxide regeneration tower") will be abbreviated as the "stripping tower," and the carbon dioxide absorption solution will be abbreviated as the "solution." Furthermore, the gas from which carbon dioxide is captured by the capture system (i.e., the gas containing carbon dioxide) will be referred to as the "target gas."

[0012] The target gas source 90 is a device or facility that generates a gas containing carbon dioxide. Specifically, a metal melting furnace or a carburizing furnace that utilizes the heat of combustion of a fossil fuel (i.e., uses a fossil fuel as fuel) can be used as the target gas source 90. In this case, the combustion exhaust gas of the fossil fuel is the target gas. The solution used is a solution in which the reaction that absorbs carbon dioxide is an exothermic reaction. In this embodiment, an aqueous amine solution is used as the solution.

[0013] <Configuration of collection system> 1 is a schematic diagram showing the configuration of a recovery system 10 according to this embodiment. The recovery system 10 according to this embodiment includes an absorption tower 11, a stripper tower 12, a target gas introduction path 13, a target gas pump 14, a target gas discharge path 15, a first solution path 16, a second solution path 17, a first solution pump 18, a second solution pump 19, a heat exchanger 20, a reboiler 21, a carbon dioxide recovery path 22, a cooler 23, and a control device 24.

[0014] The absorption tower 11 is configured so that the solution absorbs carbon dioxide (in other words, so that carbon dioxide is removed from the target gas) by bringing the solution into gas-liquid contact with the target gas. The absorption tower 11 includes a tower housing 50, a rotor 60 rotatably disposed inside the tower housing 50, a driving force source 66 for rotating the rotor 60, and a torque meter 67 for measuring the torque with which the driving force source 66 rotates the rotor 60. Inside the tower housing 50 of the absorption tower 11, there are provided, in order from top to bottom, an upper target gas chamber 51, an upper carbon dioxide absorption chamber 52U, an intermediate solution chamber 53, an intermediate target gas chamber 54, and a lower carbon dioxide absorption chamber 52D. As described above, the absorption tower 11 of this embodiment is a multi-stage type (which can also be referred to as a multi-chamber type) equipped with multiple carbon dioxide absorption chambers 52U and 52D. In the drawings and the following description, an example is shown in which the absorption tower 11 is a two-stage type equipped with two carbon dioxide absorption chambers 52U and 52D. In the following description, the "carbon dioxide absorption chamber" may be abbreviated to "absorption chamber."

[0015] The rotor 60 comprises, coaxially arranged in this order from the top, an upper shaft portion 61, an upper gas-liquid contactor 62U, an intermediate shaft portion 63, a lower gas-liquid contactor 62D, and a lower shaft portion 65. The rotor 60 further comprises an upper gas-liquid separation portion 64U arranged above the upper gas-liquid contactor 62U, and a lower gas-liquid separation portion 64D arranged above the lower gas-liquid separation portion 64D. The upper gas-liquid contactor 62U and the upper gas-liquid separation portion 64U are disposed inside the upper absorption chamber 52U, and the lower gas-liquid contactor 62D and the lower gas-liquid separation portion 64D are disposed inside the lower absorption chamber 52D.

[0016] Furthermore, the gas-liquid contact sections 62U, 62D of each stage are provided with a plurality of solution sensors 70 (omitted in FIG. 1; see FIG. 4) that can detect the solution present inside the gas-liquid contact sections 62U, 62D of each stage. Furthermore, the rotating body 60 is provided with a telemeter 71 connected to the plurality of solution sensors 70. The telemeter 71 is configured to acquire the results of solution detection by the plurality of solution sensors 70 and transmit the acquired detection results to the control device 24, which will be described later, via wireless communication.

[0017] 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 11. One end of the target gas introduction path 13 is connected to the lower absorption chamber 52D of the absorption tower 11, and the other end is connected to the target gas source 90. The target gas pump 14 is provided on the target gas introduction path 13. The target gas pump 14 is configured to supply (pressure-feed) the target gas (target gas generated in the target gas source 90) at the other end side of the target gas introduction path 13 to one end side of the target gas introduction path 13 (the lower absorption chamber 52D of the absorption tower 11) by operating. A known electric gas pump can be used as the target gas pump 14.

[0018] The target gas discharge path 15 is a path for discharging the target gas (sometimes referred to as off-gas) after carbon dioxide has been absorbed in the absorption tower 11 to the outside of the absorption tower 11. One end of the target gas discharge path 15 is connected to the upper target gas chamber 51 of the absorption tower 11, and the other end is, for example, open to the atmosphere.

[0019] The first solution path 16 is a path for supplying the solution from the absorption tower 11 to the stripper tower 12. One end of the first solution path 16 is connected to the lower absorption chamber 52D of the absorption tower 11, and the other end is connected to the stripper tower 12. A first solution pump 18 and a heat exchanger 20 are provided on the first solution path 16.

[0020] The first solution pump 18 is configured to operate to feed the solution from the lower absorption chamber 52D of the absorption tower 11 toward the stripper tower 12. The configuration of the first solution pump 18 is not particularly limited, and various conventionally known electric liquid feed pumps can be applied.

[0021] The heat exchanger 20 is configured to exchange heat between the solution flowing through the first solution path 16 and the solution flowing through the second solution path 17. By exchanging heat between the solution flowing through the first solution path 16 and the solution flowing through the second solution path 17, the solution flowing through the first solution path 16 is heated and the solution flowing through the second solution path 17 is cooled. The configuration of the heat exchanger 20 is not limited, and various conventionally known heat exchangers can be used.

[0022] The stripper tower 12 is configured so that carbon dioxide is stripped from the solution by heating the solution. An upper filler 121 and a lower filler 122 are disposed inside the stripper tower 12. Both the upper filler 121 and the lower filler 122 are materials through which the solution can permeate and through which gases (steam and carbon dioxide) can pass, such as porous metal or mesh materials with a large specific surface area. The lower filler 122 is a material that promotes gas-liquid contact between the solution and the steam generated by heating the solution. The upper filler 121 is disposed near the top of the stripper tower 12, and the lower filler 122 is disposed below it. The other end of the first solution path 16 is connected to the top of the stripper tower 12, between the upper filler 121 and the lower filler 122, and the other end of the second solution path 17 is connected to the bottom of the stripper tower 12 (or nearby) below the lower filler 122. The configuration of the stripper tower 12 is not particularly limited, and a conventionally known configuration can be applied.

[0023] The reboiler 21 is configured to generate steam at a predetermined temperature (specifically, a temperature at which the solution fed to the stripper column 12 can be heated to "a temperature at which a reaction to strip carbon dioxide occurs") by heating the solution accumulated inside (at the bottom) of the stripper column 12. Specifically, the reboiler 21 is connected to the bottom of the stripper column 12 via a first reboiler path 31 and a second reboiler path 32. The reboiler 21 generates steam by heating the solution that flows in through the first reboiler path 31. The steam generated in the reboiler 21 flows into the stripper column 12 via the second reboiler path 32.

[0024] One end of the carbon dioxide capture path 22 is connected to the top of the stripper tower 12 (or nearby), above the upper filler 121. Arranged on the carbon dioxide capture path 22, in this order from the side closest to the stripper tower 12, are a demister 33, a mixed gas cooler 34, and a gas-liquid separator 35. The demister 33 is configured to remove mist from the mixed gas of the solution vapor and carbon dioxide, and return condensed water resulting from the removed mist to the stripper tower 12. The mixed gas cooler 34 is configured to liquefy the solution vapor by cooling the mixed gas of the solution vapor and carbon dioxide. The gas-liquid separator 35 is configured to separate the solution and carbon dioxide resulting from the liquefaction of the vapor. This configuration allows gaseous carbon dioxide to be separated from the mixed gas of the solution vapor and carbon dioxide that has flowed into the carbon dioxide capture path 22. The separated carbon dioxide is discharged (recovered) outside the capture system 10. The gas-liquid separator 35 and the stripper tower 12 are connected by a solution return path 36. The solution return path 36 is configured so that the solution separated from the carbon dioxide in the gas-liquid separator 35 returns to the stripper column 12 .

[0025] The second solution path 17 is a path for supplying the solution from the stripper tower 12 to the absorber tower 11. One end of the second solution path 17 is connected to the upper absorption chamber 52U of the absorber tower 11, and the other end of the second solution path 17 is connected to the bottom of the stripper tower 12. A second solution pump 19, the heat exchanger 20, and a cooler 23 are provided on the second solution path 17.

[0026] The second solution pump 19 is configured to operate to feed the solution accumulated inside (specifically, at the bottom) of the stripper tower 12 to the absorption tower 11 (specifically, to the upper absorption chamber 52U of the absorption tower 11) through the second solution path 17. A known electric liquid feed pump can be used as the second solution pump 19.

[0027] The cooler 23 is configured to adjust (cool) the temperature of the solution fed to the absorption tower 11 to a temperature at which a reaction for absorbing carbon dioxide occurs. As the cooler 23, various known coolers are applicable.

[0028] The control device 24 is connected to the target gas pump 14, the first solution pump 18, the second solution pump 19, the reboiler 21, the intermediate solution pump 56 (described later), and the driving force source 66, and can control these. The control device 24 can also communicate with a telemeter 71, and can acquire the solution detection results from the solution sensor 70 in real time via the telemeter 71. The control device 24 is also connected to a torque meter 67, and can continuously acquire the torque measurement results from the torque meter 67 in real time. The control device 24 can estimate the amount of solution contained in the gas-liquid contact sections 62U, 62D of each stage using the solution detection results from the solution sensor 70 acquired via the telemeter 71 and the torque measurement results acquired from the torque meter 67.

[0029] The control device 24 is a device including a computer equipped with a CPU, RAM, ROM, storage device, and interface (I / F). The ROM or storage device pre-stores a computer program for controlling the recovery system 10 and a computer program for estimating the mass of the solution contained in the gas-liquid contactors 62U and 62D of each stage. The CPU then reads the computer program stored in the ROM or storage device, expands it into RAM (using the RAM as a work area), and executes it. This allows the recovery system 10 to be controlled and the amount of solution contained in the gas-liquid contactors 62U and 62D of each stage to be estimated.

[0030] <Absorption tower configuration> Next, the detailed configuration of the absorption tower 11 will be described. Fig. 2 is a cross-sectional view showing the configuration of the absorption tower 11. Fig. 3A is an enlarged view of part IIIA in Fig. 2, and Fig. 3B is an enlarged view of part IIIB in Fig. 2. In each drawing, the upper side of the absorption tower 11 is indicated by an arrow Up, and the lower side is indicated by an arrow Dw.

[0031] An upper-stage gas-liquid contactor 62U and an upper-stage gas-liquid separator 64U are rotatably arranged inside the upper-stage absorption chamber 52U. A lower-stage gas-liquid contactor 62D and a lower-stage gas-liquid separator 64D are rotatably arranged inside the lower-stage absorption chamber 52D. The gas-liquid contactors 62U and 62D of each stage are parts that promote gas-liquid contact between the solution and the target gas inside the absorption chambers 52U and 52D of each stage. The gas-liquid separators 64U and 64D of each stage are parts that remove the solution contained in the target gas that flows out from the gas-liquid contactors 62U and 62D of each stage from the target gas (i.e., perform gas-liquid separation).

[0032] The upper gas-liquid contactor 62U is connected to the second solution path 17 via the upper shaft 61 so that the solution can flow therethrough. The upper absorption chamber 52U and the intermediate solution chamber 53 are connected to each other via an intermediate solution path 55 so that the solution can flow therethrough. An intermediate solution pump 56 is disposed on the intermediate solution path 55 and is configured to supply the solution stored in the upper absorption chamber 52U to the intermediate solution chamber 53 when operated. The intermediate solution chamber 53 and the lower gas-liquid contactor 62D are connected to each other via the intermediate shaft 63 of the rotor 60 so that the solution can flow therethrough. The lower absorption chamber 52D is connected to the first solution path 16. With this configuration, the solution supplied from the stripper tower 12 to the absorption tower 11 via the second solution path 17 passes in one direction through the upper absorption chamber 52U (upper gas-liquid contact section 62U), the intermediate solution chamber 53, and the lower absorption chamber 52D (lower gas-liquid contact section 62D), and is discharged from the lower absorption chamber 52D via the first solution path 16 to the outside of the absorption tower 11 (specifically, it is supplied to the stripper tower 12).

[0033] The lower absorption chamber 52D and the intermediate target gas chamber 54 are connected via the lower shaft 65 so that the target gas can flow therethrough. The intermediate target gas chamber 54 and the upper absorption chamber 52U are connected via the intermediate target gas path 57 so that the target gas can flow therethrough. The upper absorption chamber 52U and the upper target gas chamber 51 are connected via the upper shaft 61 so that the target gas can flow therethrough. With this configuration, the target gas delivered from the target gas source 90 through the target gas introduction path 13 passes in the opposite direction to the one direction, successively through the lower absorption chamber 52D (the lower gas-liquid contact section 62D and the lower gas-liquid separation section 64D), the intermediate target gas chamber 54, the upper absorption chamber 52U (the upper gas-liquid contact section 62U and the upper gas-liquid separation section 64U), and the upper target gas chamber 51, and is then discharged from the upper target gas chamber 51 to the outside of the absorption tower 11.

[0034] 4 is a partial cross-sectional view showing the configuration of the upper gas-liquid contactor 62U and the upper gas-liquid separator 64U. The lower gas-liquid contactor 62D and the lower gas-liquid separator 64D have substantially the same configuration as the upper gas-liquid contactor 62U and the upper gas-liquid separator 64U. Each gas-liquid contactor 62U, 62D has a housing 621, a filler 622 (omitted in FIG. 4) filled inside the housing 621, and a plurality of solution sensors 70 arranged inside the housing 621 via sensor support members 72.

[0035] The housing 621 includes an upper plate member 625, a side plate member 623, and a lower plate member 624, and has a generally cylindrical shape with a hollow interior as a whole. The housing 621 is configured so that a liquid (solution) can flow into the interior from the center of the upper surface (a region including the rotation center line C), and the flowing-in liquid can flow out to the outside from the outer periphery and the lower side. The housing 621 is also configured so that a target gas can flow into the interior from the outer periphery and the lower side, and the flowing-in target gas can flow out to the outside from the upper surface (specifically, to the gas-liquid separation units 64U, 64D of each stage).

[0036] The lower plate member 624 and the side plate members 623 are formed of a material that allows the target gas and solution to pass through, such as punched metal, wire mesh, or mesh plate. The lower plate member 624 has a substantially circular plate shape. An intermediate shaft portion 63 is coaxially joined to the underside of the upper-stage lower plate member 624. A lower shaft portion 65 is coaxially joined to the underside of the lower-stage lower plate member 624. The side plate member 623 has a substantially cylindrical shape that is open at both the top and bottom ends. The upper plate member 625 has a substantially circular plate shape. An opening that penetrates in the vertical direction is provided in the center of the upper plate member 625, and a cylindrical portion 626 that protrudes upward is provided to surround this opening. Note that, of the portions of the upper plate member 625 covered by the gas-liquid separators 64U and 64D of each stage, the outer peripheral portion of the cylindrical portion 626 is configured to allow the target gas and solution to pass through.

[0037] Filler 622 is configured to be permeable to the solution and passable to the target gas. For example, a member made of metal wire or metal mesh formed into a predetermined shape (for example, a spherical or cylindrical shape) is used as filler 622. In this case, multiple (many) fillers 622 are filled inside housing 621.

[0038] A lower plate member 624 is attached to the lower side of the side plate member 623, and an upper plate member 625 is attached to the upper side of the side plate member 623. Furthermore, gas-liquid separation units 64U, 64D of each stage are attached to the upper sides of the gas-liquid contact units 62U, 62D of each stage.

[0039] The gas-liquid contactors 62U, 62D of each stage are configured so that the solution flows into them from the center of the upper plate member 625 and flows out to the outside through the side plate member 623 and the lower plate member 624. Specifically, as shown in FIG. 3A , the lower end of the upper shaft portion 61 is connected to the center of the upper plate member 625 of the upper stage gas-liquid contactor 62U. The upper shaft portion 61 has a hollow shaft shape and is equipped with an outer shaft portion 611 and an inner shaft portion 612 that are coaxial with each other. The lower end of the inner shaft portion 612 is exposed to the inside (upper and central portion) of the housing 621 through an opening provided in the center of the upper plate member 625. The upper end of the inner shaft portion 612 is connected to the second solution path 17. Therefore, the solution that has flowed into the inner shaft portion 612 of the upper shaft portion 61 through the second solution path 17 flows from the lower end of the inner shaft portion 612 into the interior of the casing 621 of the upper gas-liquid contactor 62U (in other words, into the packing material 622 packed in the casing 621 of the upper gas-liquid contactor 62U). The solution that has flowed into the interior of the upper gas-liquid contactor 62U (inside the packing material 622) is diffused downward and radially outward by gravity and centrifugal force, and flows out of the upper gas-liquid contactor 62U through the lower plate member 624 and the side plate member 623.

[0040] 3B, the lower end of the intermediate shaft 63 is connected to the center of the upper plate member 625 of the lower gas-liquid contactor 62D. The intermediate shaft 63 is also hollow and includes an outer shaft 631 and an inner shaft 632 that are coaxial with each other. The lower end of the inner shaft 632 is exposed to the interior (upper and central part) of the housing 621 through an opening provided in the center of the upper plate member 625. The inner shaft 632 is configured to allow the solution to flow in from the intermediate solution chamber 53. Specifically, a solution path hole 633 is provided in a portion of the outer shaft 631 of the intermediate shaft 63 that is located inside the intermediate solution chamber 53. Therefore, the solution that has accumulated inside the intermediate solution chamber 53 flows into the outer shaft 631 through the solution path hole 633, and further flows into the inner shaft 632 from the upper end thereof.

[0041] The solution that has flowed into the inner shaft portion 632 of the intermediate shaft portion 63 flows from the lower end of the inner shaft portion 632 into the interior of the lower-stage gas-liquid contact portion 62D (in other words, into the packing material 622 packed in the casing 621 of the lower-stage gas-liquid contact portion 62D). The solution that has flowed into the interior of the lower-stage gas-liquid contact portion 62D (inside the packing material 622) is diffused downward and radially outward by gravity and centrifugal force, and flows out of the lower-stage gas-liquid contact portion 62D through the lower plate member 624 and the side plate member 623.

[0042] The gas-liquid contactors 62U, 62D of each stage are configured so that the target gas flows into the interior from the outside through the side plate member 623 and the lower plate member 624, and flows out to the outside (the gas-liquid separation units 64U, 64D of each stage) through the upper plate member 625. The gas-liquid separation units 64U, 64D of each stage have a substantially cylindrical shape with a bottom that is open at the bottom and closed at the top. The gas-liquid separation units 64U, 64D of each stage are configured to remove mist contained in the target gas that flows out from the gas-liquid contactors 62U, 62D of each stage.

[0043] The target gas flowing out from the lower gas-liquid contactor 62D flows inside the lower gas-liquid separator 64D toward the center, passes over the upper side of the cylindrical portion 626 of the upper plate member 625, and flows into the gap between the cylindrical portion 626 and the intermediate shaft 63. The target gas that has flowed into this gap then flows into the interior of the intermediate shaft 63 (the space between the outer shaft 631 and inner shaft 632 of the intermediate shaft 63) through an upstream target gas path hole 634 provided in the outer shaft portion 631, and then flows into the intermediate target gas chamber 54 through a downstream target gas path hole 635 provided in the outer shaft 631.

[0044] The target gas flowing out from the upper gas-liquid contactor 62U flows inside the upper gas-liquid separator 64U toward the center, passes over the upper side of the cylindrical portion 626 of the upper plate member 625, and flows into the gap between the cylindrical portion 626 and the upper shaft portion 61. The target gas that has flowed into this gap then flows into the interior of the upper shaft portion 611 (the space between the outer shaft portion 611 and inner shaft portion 612) through the target gas path hole 613 provided in the outer shaft portion 611 of the upper shaft portion 61, and then flows into the upper target gas chamber 51 from the upper end of the outer shaft portion 611.

[0045] The plurality of solution sensors 70 are configured to be able to detect the solution present inside the housing 621 of the gas-liquid contactors 62U, 62D of each stage. In this embodiment, a thermocouple is used as the solution sensor 70. The thermocouple, which is the solution sensor 70, includes a temperature measuring junction and a measuring instrument (voltmeter). The temperature measuring junction of the thermocouple is disposed inside the housing 621 of the gas-liquid contactor 62U, 62D of each stage.

[0046] Because the reaction in which the solution absorbs carbon dioxide (the reaction in which the amine combines with carbon dioxide) is an exothermic reaction, the temperature of the solution rises when the solution absorbs carbon dioxide inside the gas-liquid contact sections 62U, 62D of each stage. For this reason, in this embodiment, when the temperature detected by a certain solution sensor 70 is equal to or higher than a predetermined temperature, it is considered that the solution is in contact with the temperature measuring junction of the certain solution sensor 70 (i.e., the solution is present at the location where the temperature measuring junction of the certain solution sensor 70 is located). Note that the predetermined temperature is not particularly limited and is set appropriately depending on the type and amount of amine contained in the solution, the temperature of the solution flowing into the absorption tower 11, etc.

[0047] FIG. 4 is a cross-sectional view showing the configuration of the upper gas-liquid contactor 62U and the upper gas-liquid separator 64U. The configurations of the lower gas-liquid contactor 62D and the lower gas-liquid separator 64D are also substantially the same as those of the upper gas-liquid contactor 62U and the upper gas-liquid separator 64D. The temperature measuring junctions of the solution sensors 70 are arranged so as to detect the presence or absence of a solution at each of "multiple locations at different radial distances from the rotation center line C of the housing 621 and different vertical positions" in the filler 622 filled in the housing 621. In this embodiment, the temperature measuring junctions of the solution sensors 70 are arranged at 100 to 1000 different locations on the cross section of each gas-liquid contactor 62U, 62D. In this embodiment, the temperature measuring junctions of the solution sensors 70 are arranged inside the housing 621 (in other words, inside the filler 622) via a sensor support member 72. The sensor support member 72 has a plurality of horizontal bar portions 722 extending in a substantially horizontal direction (a direction substantially perpendicular to the rotation center line C of the rotating body 60) and a plurality of vertical bar portions 721 extending in a substantially vertical direction (a direction substantially parallel to the rotation center line C of the rotating body 60), and has a net-like plate-like configuration (which can also be called a lattice-like configuration) as a whole. The temperature measuring junctions of the plurality of solution sensors 70 are disposed at the points where the vertical bar portions 721 and the horizontal bar portions 722 intersect.

[0048] The sensor support member 72, to which the temperature measuring junctions of the multiple solution sensors 70 are attached, is arranged on one radial side of an imaginary plane including the rotation center line C of the rotating body 60 (in other words, so as to include this imaginary plane). More specifically, when a cross section is imagined by cutting the housing 621 filled with the filler 622 along the imaginary plane including the rotation center line C, the sensor support member 72 is arranged so as to exist over the entire area on one radial side of the rotation center line C of the cross section. Therefore, the temperature measuring junctions of the multiple solution sensors 70 are arranged in a matrix with approximately equal density at positions that are different from each other in distance from the rotation center line C and in position in the up-down direction (direction parallel to the rotation center line C) over the entire area on one radial side of the rotation center line C of the cross section.

[0049] According to this configuration, the plurality of solution sensors 70 can detect the temperature (whether or not a solution is present) at "plurality of locations that are at different distances from the rotation center line C of the housing 621 and at different positions in the up-down direction." This configuration can also be said to be such that the temperature measuring junctions of the plurality of solution sensors 70 are arranged so as to be able to detect whether or not a solution is present at each of a plurality of different locations on an imaginary plane that includes the rotation center line C of the housing 621. The method of fixing the solution sensors 70 to the sensor support member 72 is not particularly limited, and for example, methods such as bonding with an adhesive or fixing by brazing can be applied.

[0050] Furthermore, when multiple solution sensors 70 are arranged two-dimensionally on a cross section including the rotation center line C of the rotating body 60, it is easier to arrange the solution sensors 70 than when multiple solution sensors 70 are arranged at different positions around the circumference of the rotating body 60.

[0051] Furthermore, when the multiple solution sensors 70 are arranged via a mesh-plate-shaped sensor support member 72, it is easy to arrange the multiple solution sensors 70 in the "cross section including the rotation center line C" inside the filler 622. Furthermore, when the sensor support member 72 is a mesh-plate-shaped member, the configuration of the sensor support member 72 can be simplified, thereby preventing or suppressing an increase in the price of the sensor support member 72 (an increase in parts cost). Furthermore, by arranging the temperature measurement junction of the solution sensor 70 at the intersection of the mesh-plate-shaped member, it is easy to position the temperature measurement junction of the solution sensor 70. Furthermore, the wiring of the solution sensor 70 (the wiring drawn out from the temperature measurement junction) can be easily fixed to the sensor support member 72.

[0052] Furthermore, the thermocouple measuring instruments serving as the solution sensors 70 are disposed, for example, on the upper surface of the gas-liquid separators 64U, 64D of each stage or inside the gas-liquid separators 64U, 64D of each stage. Conductive wires (metal wires) connecting each temperature measuring junction to each measuring instrument are fixed to the horizontal bar portion 722 and the vertical bar portion 721 of the sensor support member 72. Furthermore, each measuring instrument is connected to a telemeter 71. Like each measuring instrument, the telemeter 71 is disposed on the upper surface of the gas-liquid separators 64U, 64D of each stage or inside the gas-liquid separators 64U, 64D of each stage. The telemeter 71 acquires the detection results of each temperature measuring junction by each measuring instrument and transmits the acquired detection results to the control device 24 via wireless communication. It is preferable that the telemeter 71 have multiple channels. In this case, multiple solution sensors 70 (thermocouple measuring instruments) corresponding to the number of channels are connected to one telemeter 71. The configuration of the telemeter 71 is not particularly limited, and a conventionally known configuration can be applied.

[0053] As a configuration for supplying operating power to the multiple solution sensors 70 and the telemeter 71, for example, a configuration using a contactless power supply device including a power supply coil and a power receiving coil can be applied. In this case, the power supply coil of the contactless power supply device is fixed coaxially with the rotor 60 to the lower surface of the upper partition plate portion 501 that forms the ceiling surface of the upper absorption chamber 52U and the lower surface of the lower partition plate portion 502 that forms the ceiling surface of the lower absorption chamber 52D. Furthermore, the power receiving coil of the contactless power supply device is disposed on the upper surface of each gas-liquid separator 64U, 64D so as to coaxially face the power supply coil. This allows operating power to be supplied to the multiple solution sensors 70 and the telemeter 71 from outside the absorption tower 11.

[0054] However, the configuration for supplying operating power to the multiple solution sensors 70 and telemeter 71 is not limited to the above configuration. For example, a configuration in which power is supplied by a slip ring may be used. In this case, a configuration in which a slip ring is provided on one of the rotating body 60 and the tower housing 50, and a brush that contacts the slip ring is attached to the other may be used. Also, a configuration in which a battery is mounted on the rotating body 60, and this battery supplies operating power to the multiple solution sensors 70 and telemeter 71 may be used.

[0055] Furthermore, in this embodiment, the lower plate member 624, the upper plate member 625, and the side plate member 623 of the housing 621 of each stage of the gas-liquid contactor 62U, 62D are shown as separate members, but the configuration of the housing 621 is not limited to this. For example, the lower plate member 624 and the side plate member 623 may be integrally formed. The key is that the housing 621 is configured so that the filler 622 can be filled therein and multiple solution sensors 70 can be disposed therein. Furthermore, in this embodiment, the gas-liquid contactor 62U, 62D of each stage includes the housing 621 and the filler 622 filled therein. However, the configuration of the gas-liquid contactor 62U, 62D of each stage is not limited to this. For example, the gas-liquid contactor 62U, 62D of each stage may be formed of a material, such as porous metal, that is permeable to the solution and permeable to the target gas. In this case, a configuration can be applied in which a slit or hole is formed in the gas-liquid contact portions 62U, 62D of each stage, and the temperature measuring junction of the solution sensor 70 is disposed inside the slit or hole.

[0056] <Basic operation of the collection system> Next, the basic operation of the recovery system 10 will be described. The target gas generated in the target gas source 90 is pumped (fed) to the lower absorption chamber 52D of the absorption tower 11 by the operation of the target gas pump 14. The target gas that flows into the lower absorption chamber 52D passes sequentially through the lower absorption chamber 52D, the intermediate target gas chamber 54, the upper absorption chamber 52U, and the upper target gas chamber 51. The solution, whose temperature has been adjusted (cooled) to a temperature suitable for carbon dioxide absorption in the heat exchanger 20 and the cooler 23, flows into the upper absorption chamber 52U of the absorption tower 11 through the second solution path 17 by the operation of the second solution pump 19. The solution that flows into the upper absorption chamber 52U passes through the upper gas-liquid contactor 62U and temporarily accumulates at the bottom of the upper absorption chamber 52U. It is then pumped to the intermediate solution chamber 53 by the operation of the intermediate solution pump 56 and further flows into the lower absorption chamber 52D. The absorbing liquid that has flowed into the lower absorption chamber 52D passes through the lower gas-liquid contact section 62D and accumulates at the bottom of the lower absorption chamber 52D.

[0057] During operation of the recovery system 10, the rotor 60 is rotated by the driving force of the driving force source 66. Therefore, the solution that has flowed into the gas-liquid contactors 62U, 62D of each stage moves radially outward and downward inside the gas-liquid contactors 62U, 62D of each stage while diffusing due to centrifugal force and gravity. Then, the solution that has passed through the gas-liquid contactors 62U, 62D of each stage flows out of the gas-liquid contactors 62U, 62D of each stage through the side plate members 623 and the lower plate members 624.

[0058] The solution and the target gas then come into gas-liquid contact in the gas-liquid contact sections 62U and 62D of each stage, thereby absorbing the carbon dioxide contained in the target gas into the solution. Therefore, the concentration of carbon dioxide contained in the target gas gradually decreases as it passes through the lower absorption chamber 52D and the upper absorption chamber 52U. Meanwhile, as the solution flows through the upper absorption chamber 52U and the lower absorption chamber 52D, the carbon dioxide absorption rate of the solution gradually increases (the carbon dioxide loading value increases). In other words, the solution changes from a carbon dioxide-lean state to a carbon dioxide-rich state. The target gas (off-gas) from which carbon dioxide has been removed is discharged from the upper absorption chamber 52U through the upper target gas chamber 51 and the target gas discharge path 15 to the outside of the absorption tower 11. The solution accumulated at the bottom of the lower absorption chamber 52D is pumped from the absorption tower 11 to the stripper tower 12 via the first solution path 16 by the operation of the first solution pump 18. The solution flowing through the first solution path 16 is heated by heat exchange with the solution flowing through the second solution path 17 in the heat exchanger 20, and then sent to the stripper tower 12.

[0059] The solution that flows into the stripper column 12 passes through the lower packing 122 and accumulates at the bottom of the stripper column 12. A portion of the solution that accumulates at the bottom of the stripper column 12 flows into the reboiler 21 through the first reboiler path 31 and is heated in the reboiler 21. The steam generated in the reboiler 21 flows into the interior of the stripper column 12 through the second reboiler path 32, and then passes through the lower packing 122 while rising from the bottom of the stripper column 12. The steam then comes into gas-liquid contact (countercurrent contact) in the lower packing 122 with the solution flowing down from the top. As a result, the solution flowing down the lower packing 122 is heated, and carbon dioxide is stripped from the solution.

[0060] The mixture of carbon dioxide stripped from the solution and the remaining unliquefied vapor passes through the upper filler 121 and flows into the carbon dioxide capture path 22 from the top of the stripper tower 12. The upper filler 121 is a porous or mesh-like member. Therefore, when the mixture passes through the upper filler 121, the mist contained in the mixture is removed to a certain extent.

[0061] In a demister 33 provided in the carbon dioxide capture path 22, steam mist is removed from the gas-air mixture that has flowed into the carbon dioxide capture path 22. Furthermore, the gas-air mixture is cooled in a gas-air mixture cooler 34, causing the steam to condense (liquefy). Then, in a gas-liquid separator 35, the gas-air mixture is separated into gaseous carbon dioxide and a liquid solution. The carbon dioxide separated in the gas-liquid separator 35 is discharged to the outside via the carbon dioxide capture path 22. That is, the carbon dioxide is captured via the carbon dioxide capture path 22. Meanwhile, the solution separated in the gas-liquid separator 35 returns to the stripper tower 12 through a solution return path 36 and flows down through the upper filler 121. This cools the upper filler 121, accelerating the condensation of the steam contained in the gas-air mixture that passes through the upper filler 121.

[0062] The solution accumulated at the bottom of the stripper tower 12 is fed from the stripper tower 12 to the absorber tower 11 through the second solution path 17 by the operation of the second solution pump 19. The solution flowing through the second solution path 17 is cooled by heat exchange with the solution flowing through the first solution path 16 in the heat exchanger 20, and is further cooled by releasing heat in the cooler 23. This brings the solution to a temperature suitable for absorbing carbon dioxide. The solution then flows into the upper absorption chamber 52U of the absorber tower 11.

[0063] In this way, by the operation of the first solution pump 18 and the second solution pump 19, the solution is circulated through the absorption tower 11, first solution path 16, stripper tower 12, and second solution path 17 in that order. During circulation, the solution repeats the following reaction: it absorbs carbon dioxide contained in the target gas in the absorption chambers 52U and 52D of each stage of the absorption tower 11, and then strips the absorbed carbon dioxide in the stripper tower 12. The carbon dioxide stripped from the solution in the stripper tower 12 is discharged from the recovery system 10 via the carbon dioxide recovery path 22.

[0064] <Method for estimating the mass of solution contained in the gas-liquid contact area of ​​each stage> Next, a method for estimating the amount of solution contained in the gas-liquid contact sections 62U, 62D of each stage will be described. In the following description, the term "moment of inertia" means "the moment of inertia with the rotation center line C of the rotor 60 as the rotation axis," and the term "cross section of the gas-liquid contact sections 62U, 62D of each stage" means "a region on one side in the radial direction from the rotation center line C of a cross section obtained by cutting the gas-liquid contact sections 62U, 62D of each stage along an imaginary plane including the rotation center line C."

[0065] (First method) FIG. 5 is a schematic diagram illustrating a method for estimating the mass of the solution contained in the gas-liquid contactors 62U and 62D of each stage. As shown in FIG. 5, the temperature measurement junctions of multiple solution sensors 70 are arranged in a matrix of Z rows and X columns on the cross section of each gas-liquid contactor 62U and 62D of each stage. For ease of explanation, the temperature measurement junction of the solution sensor 70 located in the zth row from the top and the xth column from the center may be referred to as the "temperature measurement junction in the zth row and xth column" (1≦z≦Z, 1≦x≦X). In FIG. 5, the temperature measurement junction in the zth row and xth column is referred to as S(z, x). The vertical spacing between the temperature measurement junctions (the spacing between rows) is Δz, and the horizontal spacing between the temperature measurement junctions (the spacing between columns) is Δx. Multiple temperature measurement junctions in the same column are located at the same distance from the rotation center line C.

[0066] The method for estimating the mass of solution contained in the gas-liquid contactors 62U, 62D of each stage includes a preparation stage and an estimation stage. The preparation stage is performed before the estimation stage and is performed when the recovery system 10 is not operating (in other words, when no solution is supplied to the absorption tower 11, or in other words, when the gas-liquid contactors 62U, 62D of each stage of the rotor 60 do not contain any solution). The estimation stage is performed while the recovery system 10 is operating (while the operation of recovering carbon dioxide from the target gas is being performed) and is a stage for estimating the mass of solution contained in the gas-liquid contactors 62U, 62D of each stage while the recovery system 10 is operating. Note that in both the preparation stage and the estimation stage, the control device 24 continuously acquires torque measurement results from the torque meter 67 in real time. Furthermore, in the estimation stage, the control device 24 continuously acquires solution detection results from each solution sensor 70 in real time.

[0067] (Preparation stage) The control device 24 calculates the moment of inertia I of the rotor 60 when the gas-liquid contact sections 62U and 62D of each stage do not contain the solution. D Calculate the calculated moment of inertia I D is stored in the storage device. The moment of inertia of the rotor 60 is expressed as the product of the angular acceleration and torque of the rotor 60. The control device 24 operates the driving force source 66 to rotate the rotor 60 in a state where the gas-liquid contact sections 62U, 62D of each stage of the rotor 60 do not contain any solution. At this time, the control device 24 rotates the rotor 60 at a predetermined angular acceleration that is not zero by varying the output of the driving force source 66, and acquires torque measurement results using the torque meter 67. The control device 24 then calculates the difference between the torque while the rotor 60 is being rotated at a constant angular velocity and the torque while the rotor 60 is being rotated at a predetermined angular acceleration, and multiplies the calculated angular acceleration by the calculated torque difference. As a result, the moment of inertia I of the rotor 60 in a state where the gas-liquid contact sections 62U, 62D of each stage do not contain any solution is calculated. D The controller 24 calculates the calculated moment of inertia I D is stored in the storage device. Hereafter, this moment of inertia I D "Moment of inertia in dry state I D " is sometimes written as ".

[0068] (Estimation stage) The estimation stage includes the following four stages: Stage 1 to Stage 4. (1) First step: The moment of inertia I of the rotating body 60 is calculated based on the torque measurement result by the torque meter 67. W (Wet moment of inertia I W ) (2) Second stage: A stage for estimating the two-dimensional shape of the region where the solution exists in the cross section of the gas-liquid contact section 62U, 62D of each stage. (3) Third step: The moment of inertia of the three-dimensional shape obtained by rotating the estimated two-dimensional shape 360° around the rotation center line C of the rotating body 60 (solution moment of inertia I S)" (4) Fourth step: Calculated wet moment of inertia I W and the resulting solution moment of inertia I S A step of calculating (estimating) the mass of the solution using a formula for calculating

[0069] (1) First Stage The control device 24 rotates the rotating body 60 at a predetermined non-zero angular acceleration by varying the output of the driving force source 66 while operating the driving force source 66. The control device 24 then calculates the difference between the torque measurement result by the torque meter 67 while the rotating body 60 is being rotated at a constant angular velocity and the torque measurement result by the torque meter 67 when the rotating body 60 is being rotated at a predetermined angular acceleration. Furthermore, the control device 24 calculates the moment of inertia I of the rotating body 60 by multiplying the "predetermined angular acceleration" and the "difference in the torque measurement result." W This moment of inertia I W "Wet moment of inertia I W " Moment of inertia when wet I W is the moment of inertia of the rotor 60 when the gas-liquid contact portions 62U and 62D of each stage contain the solution.

[0070] (2) Second Stage The control device 24 estimates the "two-dimensional shape of the region where the solution is present in the cross section of the gas-liquid contactors 62U, 62D of each stage" using the solution detection results obtained from each solution sensor 70. Specifically, when a detection result indicating "solution is present" is obtained from the solution sensor 70 whose hot junction is located at z row and x column (when the temperature of the hot junction at z row and x column is equal to or higher than a predetermined temperature), the control device 24 considers that the solution is present in a minute region Δa(z, x) including the position of the hot junction at z row and x column. In this embodiment, this minute region Δa(z, x) is a quadrilateral (two-dimensional shape) whose center is the position of the hot junction at z row and x column (the position of the point at a distance r (r = (Δr / 2) + (x - 1) × Δr) from the rotation center line C and at a height position h (h = (Δh / 2) + (z - 1) × Δh)), and whose horizontal dimension is Δr and whose vertical dimension is Δh.

[0071] The two-dimensional shape formed by arranging (connecting) the minute regions Δa deemed to have a solution in accordance with their actual positions is the "two-dimensional shape of the region where a solution exists" in the cross section of the gas-liquid contactors 62U, 62D of each stage. The control device 24 acquires the solution detection results from all of the solution sensors 70, evaluates the acquired detection results, and estimates the "two-dimensional shape of the region where a solution exists" in the cross section of the gas-liquid contactors 62U, 62D of each stage by arranging the minute regions Δa including the temperature measuring junctions of the solution sensors 70 determined to have a solution in accordance with their actual positions. In FIG. 5, the solid lines indicate an example of the "two-dimensional shape of the region where a solution exists in the cross section of the gas-liquid contactors 62U, 62D of each stage."

[0072] (3) Third Stage The control device 24 calculates the moment of inertia I of the solution contained in the gas-liquid contact portions 62U and 62D of each stage. S This moment of inertia is calculated as the solution moment of inertia I S The moment of inertia of the solution in each stage is I Sis expressed as the product of the "three-dimensional shape of the region where the solution exists in the gas-liquid contact sections 62U, 62D of each stage" and the "density of the three-dimensional shape." The centrifugal force acting on the gas-liquid contact sections 62U, 62D of each stage is uniform in the circumferential direction. Therefore, the solution contained in the gas-liquid contact sections 62U, 62D of each stage is considered to be uniformly dispersed in the circumferential direction. In other words, the "two-dimensional shape of the region where the solution exists" is considered to be the same at any position in the circumferential direction. In this embodiment, the "three-dimensional shape obtained by rotating the two-dimensional shape estimated in the second stage by 360° around the rotation center line C of the rotor 60" is used as the "three-dimensional shape of the region where the solution exists." In other words, the solution moment of inertia I S In the calculation of (a), the density of this three-dimensional shape is assumed to be uniform. It can also be said that this three-dimensional shape is the three-dimensional shape of the solution present inside the gas-liquid contact portions 62U and 62D of each stage.

[0073] The control device 24 generates a calculation formula by regarding this three-dimensional shape as "a combination of multiple cylindrical shapes of different diameters arranged coaxially." In this case, one cylindrical shape is applied with a shape obtained by rotating a region (the shape of a region where minute regions Δa are arranged in the row direction) where a solution is deemed to exist based on the detection results obtained from sensors whose temperature measuring junctions are located at the same distance from the rotation center line C (i.e., sensors whose temperature measuring junctions are included in the same row) by 360° around the rotation center line C. In Figure 5, the hatched region corresponds to one cylindrical shape. The moment of inertia i of one cylindrical shape corresponding to a sensor included in the xth row is S The formula for calculating (x) is: i S (x)=(1 / 2)·m(x)·((x·Δr) 2 +((x-1) Δr) 2 ) Formula (1) m(x): Mass of one cylindrical shape corresponding to the sensor in the xth column The mass m(x) of one cylindrical shape corresponding to the sensor included in the xth column is the product of the area of ​​the cylindrical shape in top view, the height of the cylindrical shape, and the density of the cylindrical shape, so it is expressed as follows: m(x)=π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh·ρ Equation (2) π: Pi n: Number of hot junctions where solution was determined to exist ρ: Density of the cylindrical shape In equations (1) and (2), n is a value that can be obtained from the detection results of the sensor, so the only unknown value is the density ρ of the cylindrical shape.

[0074] and the solution moment of inertia I S teeth, I S =Σi S (x) =Σ(1 / 2) m(x) ((x Δr) 2 +((x-1) Δr) 2 ) =Σ(1 / 2)·(π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh·ρ)·((x·Δr) 2 +(x-1 Δr) 2 ) Formula (3) This equation (3) is the solution moment of inertia I S is a formula for calculating the density ρ of the cylindrical shape. On the right side of equation (3), Δr and Δh are known values ​​that are specified in advance, and n is a value that is determined based on the detection results obtained from the solution sensor 70. Therefore, the only unknown value on the right side of equation (3) is the density ρ of the cylindrical shape. The control device 24 generates equation (3) using the two-dimensional shape estimated in the second stage.

[0075] (4) Fourth Stage Wet moment of inertia I calculated in the first stage of the estimation Wand the dry moment of inertia I calculated in the preparation stage D and the solution moment of inertia I calculated using the formula generated in the third stage of the estimation stage. S What is that? (Solution moment of inertia I S )=(Wet moment of inertia I W )-(dry moment of inertia I D ) Formula (4) The relationship is expressed as follows: Moment of inertia when wet I W and dry moment of inertia I D is a value calculated from the angular acceleration of the rotor 60 and the torque measured by the torque meter 67. The solution moment of inertia I S is expressed as a one-variable function with density ρ as a variable. The control device 24 calculates density ρ by using equation (4). Furthermore, the control device 24 calculates the volume of the three-dimensional shape using the two-dimensional shape estimated in the second stage of the estimation step, and calculates the mass of the three-dimensional shape by multiplying the calculated density ρ and volume V. In other words, the total mass M of the solution contained in the gas-liquid contact portions 62U and 62D of each stage is given by M=ρ·Σ(π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh) Equation (5) This formula (5) is a calculation formula for calculating the total mass of the solution contained in the gas-liquid contact sections 62U, 62D of each stage. The control device 24 uses this formula (5) to calculate the total mass of the solution contained in the gas-liquid contact sections 62U, 62D of each stage.

[0076] In this way, the control device 24 calculates the moment of inertia I of the estimated three-dimensional shape of the rotating body 60 with the rotation center line C as the rotation axis. S (Solution moment of inertia I S ) is the moment of inertia I calculated from the measurement results of the torque meter 67. W (Wet moment of inertia I W ) and the moment of inertia I of the rotating body 60 not containing the solution D (Dry moment of inertia ID In this embodiment, this mass is the total mass of the solution present inside the gas-liquid contact portions 62U, 62D of each stage.

[0077] With this configuration, the total mass of the solution diffused inside the gas-liquid contact sections 62U, 62D of each stage of the rotor 60 (which can also be referred to as the solution contained in the gas-liquid contact sections 62U, 62D of each stage of the rotor 60) can be continuously obtained during operation of the recovery system 10. Therefore, according to the present disclosure, it is possible to provide a recovery system 10 that can continuously obtain the state of solution diffusion during operation.

[0078] When the number of solution sensors 70 is between 100 and 1000, the area of ​​the region where the solution exists relative to the area of ​​the cross section can be measured with an accuracy of 0.1 to 1%.

[0079] Also, here, the moment of inertia i S Although the method for calculating (x) has been described above, the method is not limited to this. For example, the moment of inertia may be calculated for each minute region Δa. Alternatively, the moment of inertia may be calculated for each row.

[0080] (Second method) Next, the second method of the estimation stage will be described. In the first method, the total mass of the solution was estimated assuming that the density ρ of the three-dimensional shape is uniform, but in the second method, the total mass of the solution is estimated assuming that the density of the three-dimensional shape is non-uniform. When the solution is supplied from the center to the gas-liquid contact sections 62U, 62D of each stage, the amount of solution contained in the packing material 622 per unit volume decreases as the distance from the rotation center line C increases. In other words, the density of the three-dimensional shape decreases as the distance from the rotation center line C increases. Therefore, in the estimation stage related to the second method, the solution moment of inertia I S In the calculation of (a) and the calculation (estimation) of the total mass of the solution, the density of the three-dimensional shape is changed according to the distance from the rotation center line C. Note that the first and second stages may be the same as those in the first method, and therefore a description thereof will be omitted.

[0081] The mass m(x) of one cylinder is m(x)=π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh·ρ b ·α(x) Equation (6) ρ b :Reference density (unknown) α(x): Density correction coefficient (known) The reference density ρ b and the density correction coefficient α(x), is the density of one cylindrical shape corresponding to the sensor in the xth column. The value of the density correction coefficient α(x) is preset so that it decreases as the distance from the rotation center line C increases (the column is farther away from the rotation center line C). In this embodiment, the value of the density correction coefficient α(x) is set so that it decreases as the value x (xth column), which indicates the radial position of the temperature measuring junction of each solution sensor 70, increases, within a range of 1 or less and exceeding 0. Note that the specific value of this density correction coefficient α(x) is not particularly limited and can be set as appropriate.

[0082] Solution moment of inertia I S The formula for calculating m(x) is the same as formula (3), except for the content of m(x). The mass m(x) of one cylindrical shape corresponding to the sensor included in the x-th column is M=π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh·ρ b ·α(x) Equation (7) Therefore, the total mass is M=Σ(π·((x·Δr) 2 -((x-1) Δr) 2 )·n·Δh·ρ b ·α(x)) Equation (8) This formula (8) is a calculation formula for calculating the total mass of the solution contained in the gas-liquid contact sections 62U, 62D of each stage in the second method. The control device 24 calculates the total mass using this formula (8).

[0083] The second method can achieve the same effects as the first method, and further improves the accuracy of estimating the total mass of the solution.

[0084] <Summary of the embodiment> (1) The carbon dioxide capture system 10 according to this embodiment includes: A carbon dioxide recovery system (10) including a carbon dioxide absorption tower (11) that absorbs carbon dioxide contained in a gas into a carbon dioxide absorbing solution by bringing a carbon dioxide absorbing solution supplied from the outside into gas-liquid contact with the gas containing carbon dioxide supplied from the outside, a rotor 60 configured to allow the carbon dioxide absorbing solution to diffuse therein, disposed inside the carbon dioxide absorption tower 11, and rotated by a driving force output by a driving force source 66; a plurality of solution sensors 70 that are arranged at positions that are different from each other in distance from the rotation center line C of the rotating body 60 and in positions in a direction parallel to the rotation center line C, and that detect the presence of the carbon dioxide absorbing solution; Equipped with.

[0085] According to the carbon dioxide capture system 10 of this embodiment, it is possible to provide a carbon dioxide capture system 10 that can continuously acquire the state of diffusion of the carbon dioxide absorbing solution during operation based on the detection results of the multiple solution sensors 70. The plurality of solution sensors 70 can continuously acquire, during operation, the region inside the rotor 60 where the carbon dioxide absorbing solution is diffused (which can also be referred to as the region where the carbon dioxide absorbing solution is present) and the total amount of the carbon dioxide absorbing solution diffused inside the rotor 60 (which can also be referred to as the carbon dioxide absorbing solution contained in the rotor 60). Therefore, according to the present disclosure, it is possible to provide a carbon dioxide capture system 10 that can continuously acquire the state of diffusion of the carbon dioxide absorbing solution during operation.

[0086] (2) The carbon dioxide capture system 10 according to this embodiment includes: a torque meter 67 for measuring the torque of the driving force applied by the driving force source 66 to rotate the rotating body 60; The moment of inertia I of the rotor 60 containing the carbon dioxide absorbing solution is calculated from the torque measured by the torque meter 67. W and estimates the three-dimensional shape of the area where the carbon dioxide absorbing solution exists from the detection results of the presence of the carbon dioxide absorbing solution by the plurality of solution sensors 70.

[0087] According to the carbon dioxide capture system 10 of this embodiment, the moment of inertia I of the rotor 60 containing the carbon dioxide absorbing solution is calculated from the torque measured by the torque meter 67. W Calculate the calculated moment of inertia I W By using this, it is possible to estimate the total amount of the carbon dioxide absorbing solution that has diffused inside the rotor 60. In this way, based on the torque measurement results by the torque meter 67, it is also possible to continuously estimate the region inside the rotor 60 where the carbon dioxide absorbing solution has diffused (this can also be referred to as the region where the carbon dioxide absorbing solution is present) and the total mass of the carbon dioxide absorbing solution that has diffused inside the rotor 60 (this can also be referred to as the carbon dioxide absorbing solution contained in the rotor) during operation.

[0088] (3) The carbon dioxide capture system 10 according to this embodiment includes: The estimated moment of inertia I of the rotating body 60 of the three-dimensional shape with the center of rotation as the rotation axis S is the moment of inertia I calculated from the measurement results of the torque meter 67. W and the moment of inertia I of the rotating body not containing the carbon dioxide absorbing solution. D and a calculation device (control device 24) that calculates the mass of the three-dimensional shape that is equal to the difference between the mass and the mass of the carbon dioxide absorbing solution contained in the rotor 60 as the total mass of the carbon dioxide absorbing solution contained in the rotor 60.

[0089] In the carbon dioxide capture system 10 according to this embodiment, the estimated moment of inertia I S The moment of inertia I calculated from the measurement results of the torque meter 67 W and the moment of inertia I of the rotor not containing the carbon dioxide absorbing solution. D Therefore, the estimated moment of inertia I S is the moment of inertia I calculated from the measurement results of the torque meter 67. W and the moment of inertia I of the rotating body not containing the carbon dioxide absorbing solution. D The mass of the three-dimensional shape when the mass is equal to the difference between the mass of the carbon dioxide absorbing solution and the mass of the carbon dioxide absorbing solution contained in the rotating body 60 is the total mass of the carbon dioxide absorbing solution contained in the rotating body 60. Therefore, according to the carbon dioxide capture system 10 according to this embodiment, the total mass of the carbon dioxide absorbing solution contained in the rotating body 60 can be calculated (estimated).

[0090] (4) In this embodiment, The plurality of solution sensors 70 are two-dimensionally arranged on a cross section including the rotation center line C of the rotating body 60, The calculation device (control device 24) estimates the two-dimensional shape of the area in the cross section where the carbon dioxide absorbing solution is present from the detection results of the presence of the carbon dioxide absorbing solution by the multiple solution sensors 70, and estimates the shape obtained by rotating the estimated two-dimensional shape around the rotation center line C of the rotating body 60 as the three-dimensional shape.

[0091] When multiple solution sensors 70 are arranged two-dimensionally on a cross section including the rotation center line C of the rotating body 60, it is easier to arrange the solution sensors 70 than when multiple solution sensors 70 are arranged at different positions around the circumference of the rotating body 60.

[0092] (5) In this embodiment, The number of the solution sensors 70 is 100 to 1000, and the solution sensors are arranged so as to be able to detect the presence of the carbon dioxide absorbing solution at 100 to 1000 locations spaced apart from one another on the cross section.

[0093] When the number of solution sensors 70 is between 100 and 1000, the "area of ​​the region where the solution exists" relative to the area of ​​the cross section including the rotation center line C of the rotating body 60 (more specifically, the gas-liquid contact sections 62U, 62D of each stage) can be measured with an accuracy of 0.1 to 1%.

[0094] (6) In this embodiment, The rotating body 60 includes a substantially cylindrical housing 621 having a cavity therein, a sensor support member 72 having a substantially flat shape and disposed inside the housing 621 so as to include the cross section, and a filler 622 configured to allow the carbon dioxide absorbing solution to diffuse and gas to pass through, and filled inside the housing; The plurality of solution sensors 70 are fixed to the sensor support member 72 .

[0095] According to this configuration, it is easy to arrange the plurality of solution sensors 70 inside the filler 622 in the "cross section including the rotation center line C."

[0096] (7) In this embodiment, The sensor support member 72 is a mesh plate-like member.

[0097] This configuration simplifies the configuration of the sensor support member 72, thereby preventing or minimizing an increase in the price (increase in parts costs) of the sensor support member 72. Furthermore, by arranging the temperature measurement junction of the solution sensor 70 at the intersection of the mesh plate-like member, it is easy to position the temperature measurement junction of the solution sensor 70. Furthermore, the wiring of the solution sensor 70 (the wiring drawn out from the temperature measurement junction) can be easily fixed to the sensor support member 72.

[0098] (8) In this embodiment, The carbon dioxide absorbing solution is a solution in which the reaction of absorbing carbon dioxide is an exothermic reaction, The plurality of solution sensors 70 are thermocouples.

[0099] With this configuration, the presence of the carbon dioxide absorbing solution can be detected by the heat of reaction that is generated when the carbon dioxide absorbing solution absorbs carbon dioxide.

[0100] Although the embodiments and modifications of the present invention have been described above, the technical scope of the present invention is not limited to the above-described embodiments and modifications. The present invention can be modified in various ways without departing from the spirit of the invention, and these modifications are also included in the technical scope of the present invention.

[0101] For example, in the above embodiment, an example was shown in which the absorption tower 11 is a two-stage type, but the number of stages (the number of carbon dioxide absorption chambers 52U, 52D) of the absorption tower 11 is not limited to 2. For example, the absorption tower 11 may be a one-stage type, or may be a three-stage or more type. [Explanation of symbols]

[0102] 10... Carbon dioxide recovery system, 11... Carbon dioxide absorption tower (absorption tower), 24... Control device, 50... Tower housing, 60... Rotating body, 62U, 62D... Gas-liquid contact portion, 66... ​​Driving force source, 67... Torque meter, 70... Solution sensor, 72... Sensor support member

Claims

1. A carbon dioxide recovery system including a carbon dioxide absorption tower that absorbs carbon dioxide contained in a gas into a carbon dioxide absorbing solution by bringing a carbon dioxide absorbing solution supplied from an outside into gas-liquid contact with the gas containing carbon dioxide supplied from an outside, a rotor configured to allow the carbon dioxide absorbing solution to diffuse therein, disposed inside the carbon dioxide absorption tower, and rotated by a driving force output by a driving force source; a plurality of solution sensors that are arranged at positions that are different from each other in distance from the rotation center line of the rotating body and in positions in a direction parallel to the rotation center line, and that detect the presence of the carbon dioxide absorbing solution; A carbon dioxide capture system comprising:

2. 2. The carbon dioxide capture system of claim 1, a torque meter that measures the torque of the driving force that rotates the rotating body by the driving force source, a moment of inertia of the rotating body containing the carbon dioxide absorbing solution is calculated from the torque measured by the torque meter, and a three-dimensional shape of an area where the carbon dioxide absorbing solution is present is estimated from detection results of the presence of the carbon dioxide absorbing solution by the plurality of solution sensors.

3. 3. The carbon dioxide capture system of claim 2, a calculation device that calculates, as the total mass of the carbon dioxide absorbing solution contained in the rotating body, the mass of the three-dimensional shape such that the estimated moment of inertia of the rotating body with the center of rotation of the rotating body as its rotation axis is equal to the difference between the moment of inertia calculated from the measurement results of the torque meter and the moment of inertia of the rotating body not containing the carbon dioxide absorbing solution.

4. 4. The carbon dioxide capture system of claim 3, the plurality of solution sensors are two-dimensionally arranged on a cross section including the rotation center line of the rotor, the arithmetic device estimates a two-dimensional shape of a region in the cross section where the carbon dioxide absorbing solution is present from the detection results of the presence of the carbon dioxide absorbing solution by the plurality of solution sensors, and estimates, as the three-dimensional shape, a shape obtained by rotating the estimated two-dimensional shape around the rotation center of the rotating body. Carbon dioxide capture system.

5. 5. The carbon dioxide capture system of claim 4, the number of the solution sensors is 100 or more and 1000 or less, and the solution sensors are arranged so as to be able to detect the presence of the carbon dioxide absorbing solution at 100 or more and 1000 or less locations spaced apart from each other on the cross section; Carbon dioxide capture system.

6. The carbon dioxide recovery system according to claim 4 or claim 5, the rotating body comprises a substantially cylindrical housing having a cavity therein, a sensor support member having a substantially flattened shape and disposed inside the housing so as to include the cross section, and a filler configured to allow the carbon dioxide absorbing solution to diffuse and gas to pass through, the filler being filled inside the housing, the plurality of solution sensors are fixed to the sensor support member; Carbon dioxide capture system.

7. 7. The carbon dioxide capture system of claim 6, The sensor support member is a mesh plate-like member. Carbon dioxide capture system.

8. 2. The carbon dioxide capture system of claim 1, The carbon dioxide absorbing solution is a solution in which the reaction of absorbing carbon dioxide is an exothermic reaction, the plurality of solution sensors are thermocouples; Carbon dioxide capture system.

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