Carbon dioxide recovery device

Abstract

To provide a carbon dioxide recovery device that can appropriately maintain a liquid level height of amine aqueous solution in a carbon dioxide absorption tower.SOLUTION: A carbon dioxide recovery device 10a comprises: a carbon dioxide emission tower 12 which is so configured that carbon dioxide is emitted from amine aqueous solution; a carbon dioxide absorption tower 11 wich is son configured that carbon dioxide contained in a gas fed from the exterior is absorbed by the amine aqueous solution fed from the carbon dioxide emission tower 12; a rich pump 17 which feeds the amine aqueous solution existing in the carbon dioxide absorption tower 11 to the carbon dioxide emission tower 12; a liquid level height measuring unit 16 which can measure a liquid level height of the amine aqueous solution existing in the carbon dioxide absorption tower 11; and a control unit 22 which controls output of the rich pump 17 so that the liquid level height of the amine aqueous solution existing in the carbon dioxide absorption tower 11 falls within a previously regulated range.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] The carbon dioxide capture device disclosed in Patent Document 1 is configured to introduce a gas (target gas) from which carbon dioxide is to be captured, such as combustion exhaust gas, into the carbon dioxide absorption tower, and to circulate a carbon dioxide absorbing solution (amine aqueous solution) between the carbon dioxide absorption tower and the carbon dioxide stripper tower. The carbon dioxide contained in the target gas is absorbed into the carbon dioxide absorbing solution in the carbon dioxide absorption tower, carbon dioxide is stripped from the carbon dioxide absorbing solution in the carbon dioxide stripper tower, and the stripped carbon dioxide is captured in the carbon dioxide stripper tower.

[0003] When the liquid level of the carbon dioxide absorbing solution becomes excessively high in a single-stage absorption tower or the bottom stage of a multi-stage absorption tower (the absorption tower located at the most downstream side of the flow of the carbon dioxide absorbing solution), the carbon dioxide absorbing solution may flow into a path that receives a supply of the target gas from the outside. If the carbon dioxide absorbing solution flows into this path, the amount of the target gas delivered through this path will decrease, and the flowing carbon dioxide absorbing solution may corrode a pump installed in the path.

[0004] Furthermore, if the liquid level of the carbon dioxide absorbing solution becomes excessively low in the single-stage absorption tower or the bottom stage of a multi-stage absorption tower, the target gas may flow into the path for feeding the carbon dioxide absorbing solution to the carbon dioxide stripper tower. If the target gas flows into the carbon dioxide stripper tower through the path, the target gas may be mixed with the carbon dioxide released from the carbon dioxide absorbing solution in the carbon dioxide stripper tower, and the purity of the recovered carbon dioxide may decrease.

[0005] In addition, in a carbon dioxide capture device equipped with a multi-stage absorption tower, when the liquid level of the carbon dioxide absorbing solution in the absorption towers other than the lowest stage becomes excessively low (or when the carbon dioxide absorbing solution is not accumulated in the absorption towers other than the lowest stage), the target gas may flow in (return) through a path that receives the supply of the carbon dioxide absorbing solution from the upper absorption tower (meaning the absorption tower adjacent to the upstream side of the flow of the carbon dioxide absorbing solution and the downstream side of the flow of the target gas). As a result, the amount of the target gas to be treated is reduced by the amount of the returned target gas (in other words, the amount of the target gas delivered from the outside is reduced), and the efficiency of carbon dioxide absorption is reduced. On the other hand, if the liquid level of the carbon dioxide absorbing solution in each absorption tower becomes excessively high, the carbon dioxide absorbing solution may block the path that receives the supply of the target gas from the lower absorption tower, thereby hindering the delivery of the target gas from the lower stage. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2017-90120 A 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 apparatus capable of appropriately maintaining the liquid level of a carbon dioxide absorbing solution in an absorption tower (a single-stage absorption tower and each stage of a multi-stage absorption tower).

[0008] (Means for solving the problem) In order to achieve the above object, the carbon dioxide capture device according to the present invention comprises: A carbon dioxide stripper configured so that the carbon dioxide absorbed in the carbon dioxide absorbing solution is stripped from the carbon dioxide absorbing solution; A first carbon dioxide absorption tower is configured to be connected to a gas path through which a gas containing carbon dioxide is supplied from the outside and a carbon dioxide absorbing solution path capable of supplying the carbon dioxide absorbing solution to the carbon dioxide stripper tower, and the carbon dioxide contained in the gas supplied through the gas path is absorbed in the carbon dioxide absorbing solution; a first pump configured to operate to supply the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower to the carbon dioxide stripper tower via the carbon dioxide absorbing solution path; A first liquid level measuring device capable of measuring a liquid level of the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower; and a control device that uses the measurement result of the liquid level height of the carbon dioxide absorbing solution to control the flow rate of the carbon dioxide absorbing solution by the first pump so that the liquid level height of the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower falls within a predetermined range.

[0009] According to the carbon dioxide capture device of the present invention, the liquid level of the carbon dioxide absorbing solution accumulated inside the first carbon dioxide absorption tower is maintained at a predetermined height (target liquid level height) based on the measurement result of the liquid level height. This makes it possible to prevent or suppress the carbon dioxide absorbing solution accumulated inside the first carbon dioxide absorption tower from flowing into the path of the target gas. In addition, it is possible to prevent or suppress the carbon dioxide absorbing solution accumulated inside the first carbon dioxide absorption tower from flowing into the stripping tower via the path for the target gas inside the first carbon dioxide absorption tower to feed the carbon dioxide absorbing solution to the stripping tower. In other words, the liquid level height can be maintained at a height (appropriate height) at which "the feed of gas from the outside to the absorption tower is not hindered and gas does not flow into the path for feeding the carbon dioxide absorbing solution from the absorption tower to the stripping tower" or can be brought close to such a height. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a second embodiment of the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a third embodiment of the present invention. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a fourth embodiment of the present invention. [Diagram 5] FIG. 5 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Each embodiment of the present invention will be described below. In the following description, the carbon dioxide capture device may be abbreviated as the "capture device", the carbon dioxide absorption tower may be abbreviated as the "absorption tower", and the carbon dioxide stripper tower may be abbreviated as the "stripping tower". Furthermore, the gas that is the target of carbon dioxide capture by the capture device (i.e., gas containing carbon dioxide) may be referred to as the "target gas". The solid arrows in each figure indicate the direction of flow of the carbon dioxide absorbing solution, and the dashed arrows indicate the direction of flow of the target gas.

[0012] An amine aqueous solution is shown as a carbon dioxide absorbing solution used in the recovery devices 10a, 10b, 10c, 10d, and 10e according to each embodiment. The type of amine contained in the amine aqueous solution is not particularly limited, and various amines that are applied to known carbon dioxide recovery devices can be applied. In addition, the source of the target gas and the type of the target gas are also not particularly limited. For example, a carburizing furnace or the like is applied as the source of the target gas, and in this case, the combustion exhaust gas from the carburizing furnace is applied as the target gas.

[0013] First Embodiment Fig. 1 is a schematic diagram showing the configuration of a recovery apparatus 10a according to a first embodiment. The recovery apparatus 10a according to the first embodiment includes one absorption tower 11 (single-stage absorption tower 11). As shown in Fig. 1, the recovery apparatus 10a includes the absorption tower 11, a stripper tower 12 (sometimes referred to as a "carbon dioxide regeneration tower"), a rich path 13, a lean path 14, a heat exchanger 15, a rich pump 17, a lean pump 18, a reboiler 20, a condenser 21, and a control device 22.

[0014] The absorption tower 11 is an example of a first carbon dioxide absorption tower of the present invention. The absorption tower 11 is configured so that the amine aqueous solution absorbs carbon dioxide (in other words, so that carbon dioxide is removed from the target gas) by bringing the amine aqueous solution into gas-liquid contact with the target gas. Inside the absorption tower 11, an upper filler 111 and a lower filler 112 are arranged as members for promoting gas-liquid contact between the target gas and the amine aqueous solution. The upper filler 111 is arranged near the top of the absorption tower 11, and the lower filler 112 is arranged below it. Moreover, a portion inside the absorption tower 11 near the bottom (a portion below the lower filler 112) is configured to be able to store the amine aqueous solution.

[0015] One end of a target gas introduction path 23 is connected to the absorption tower 11. The target gas introduction path 23 is an example of a gas path of the present invention. The target gas introduction path 23 is a path for feeding the target gas into the absorption tower 11, and the other end is connected to a source of the target gas. The target gas introduction path 23 is provided with an air pump (not shown), and the target gas is fed from the source of the target gas to the absorption tower 11 by operating the air pump. One end of the target gas introduction path 23 is connected to a position spaced upward from the bottom surface of the inside of the absorption tower 11 to a certain degree so that the feeding of the target gas to the absorption tower 11 (in other words, the inflow of the target gas) is not hindered by the aqueous amine solution accumulated inside (bottom) of the absorption tower 11. One end of a target gas discharge path 24 is connected to the top of the absorption tower 11 or near the top of the absorption tower 11 and above the upper filler 111. The target gas discharge path 24 is a path for discharging the target gas from the absorption tower 11, and the other end is, for example, open to the atmosphere.

[0016] Furthermore, one end of a rich path 13 is connected to the absorption tower 11. The rich path 13 is an example of a carbon dioxide absorbing solution path of the present invention, and is a path for feeding the amine aqueous solution from the absorption tower 11 to the stripper tower 12. One end of the rich path 13 is connected to the bottom of the absorption tower 11 or in its vicinity so that the amine aqueous solution stored in the absorption tower 11 can be fed to the stripper tower 12. Note that one end of the rich path 13 is connected below the position where one end of the target gas introduction path 23 is connected. One end of a lean path 14 is connected to the upper part of the absorption tower 11, between the upper filler 111 and the lower filler 112.

[0017] The stripper tower 12 is configured to strip carbon dioxide from the amine aqueous solution by heating the amine aqueous solution. Inside the stripper tower 12, an upper filler 121 and a lower filler 122 are arranged as members for promoting gas-liquid contact between the amine aqueous solution and water vapor described later. The upper filler 121 is arranged near the top, and the lower filler 122 is arranged below it. The other end of the rich path 13 is connected to the upper part of the stripper tower 12 between the upper filler 121 and the lower filler 122, and the other end of the lean path 14 is connected to the bottom of the stripper tower 12 or near the bottom of the stripper tower 12 and below the lower filler 122.

[0018] The reboiler 20 is configured to heat the aqueous amine solution to generate steam at a temperature capable of heating the aqueous amine solution to "a temperature at which a reaction for stripping carbon dioxide occurs." The reboiler 20 is connected to the bottom of the stripper tower 12 via a path for the aqueous amine solution and a path for the steam. The reboiler 20 heats the aqueous amine solution that has flowed in through the path for the aqueous amine solution to generate steam. The steam generated in the reboiler 20 flows into the interior of the stripper tower 12 via the path for the steam.

[0019] One end of a carbon dioxide discharge path 25 is connected to the top of the stripper tower 12 (or in its vicinity) above the upper filler 121. A condenser 21 (a cooler and a gas-liquid separator) is disposed on the carbon dioxide discharge path 25. The condenser 21 is configured to separate water vapor from a mixture of water vapor and carbon dioxide discharged from the stripper tower 12. The condenser 21 is connected to the stripper tower 12 by a return path 26. The return path 26 is configured so that condensed water generated in the condenser 21 flows back above the upper filler 121 of the stripper tower 12.

[0020] A rich pump 17 is provided on the rich path 13. The rich pump 17 is an example of a first pump of the present invention. The rich pump 17 is configured to feed the amine aqueous solution accumulated inside (specifically, at the bottom) of the absorption tower 11 to the stripper tower 12 through the rich path 13 by operating. A known electric liquid feed pump is applied to the rich pump 17.

[0021] The lean path 14 is a path for feeding the amine aqueous solution from the stripper 12 to the absorber 11. One end of the lean path 14 is connected to the top of the absorber 11, and the other end of the lean path 14 is connected to the bottom of the stripper 12. A lean pump 18 and a lean flowmeter 19 are provided on the lean path 14. The lean pump 18 is configured to feed the amine aqueous solution stored inside (specifically, at the bottom) of the stripper 12 to the absorber 11 through the lean path 14 by operating. A known electric liquid feed pump can be used for the lean pump 18. The lean flowmeter 19 can measure the flow rate per unit time of the amine aqueous solution flowing through the lean path 14 (hereinafter, the "flow rate per unit time" will be simply referred to as "flow rate"), that is, the flow rate of the amine aqueous solution fed from the stripper 12 to the absorber 11. A conventionally known flowmeter capable of measuring the flow rate of various liquids can be used for the lean flowmeter 19.

[0022] The heat exchanger 15 is disposed in an intermediate portion of each of the rich path 13 and the lean path 14. The heat exchanger 15 is configured to exchange heat between the amine aqueous solution flowing through the rich path 13 and the amine aqueous solution flowing through the lean path 14. Specifically, the heat exchanger 15 is configured to heat the amine aqueous solution flowing through the rich path 13 and cool the amine aqueous solution flowing through the lean path 14.

[0023] The liquid level measuring device 16 provided in the absorption tower 11 is an example of a first liquid level measuring device of the present invention. The liquid level measuring device 16 is configured to be capable of continuously measuring the liquid level of the amine aqueous solution accumulated inside the absorption tower 11 in real time. Alternatively, the liquid level measuring device 16 is configured to be capable of continuously measuring a predetermined index used for calculating the liquid level of the amine aqueous solution accumulated inside the absorption tower 11 in real time. In this case, the control device 22 described later uses the acquired predetermined index to calculate the liquid level of the amine aqueous solution accumulated inside the absorption tower 11. Hereinafter, the "liquid level of the amine aqueous solution accumulated inside the absorption tower 11" may be abbreviated to simply "liquid level".

[0024] For example, an ultrasonic distance sensor is applied to the liquid level measuring device 16. In this case, the ultrasonic distance sensor is disposed so as to irradiate ultrasonic waves toward the liquid level of the amine aqueous solution accumulated at the bottom of the absorption tower 11 and receive ultrasonic waves reflected by the liquid level. The ultrasonic sensor can measure "the time from irradiating ultrasonic waves to the liquid level of the amine aqueous solution to receiving the reflected waves" as "a predetermined index used in calculating the liquid level".

[0025] The control device 22 is connected to the rich pump 17, the lean pump 18, and the reboiler 20, and is configured to be able to control these. The control device 22 can also continuously acquire the liquid level measured by the liquid level measuring device 16 in real time. Alternatively, the control device 22 can continuously acquire the predetermined index measured by the liquid level measuring device 16 in real time, and continuously calculate the liquid level in real time using the acquired index. As described above, if the liquid level measuring device 16 is an ultrasonic sensor, the control device 22 can calculate the liquid level from the "time from emitting ultrasonic waves to receiving reflected waves" acquired from the ultrasonic sensor and the arrangement position of the ultrasonic sensor in the absorption tower 11. In the following description, "measuring the liquid level" includes "directly measuring the liquid level by the liquid level measuring device" and "calculating the liquid level from the predetermined index measured by the liquid level measuring device." Furthermore, the control device 22 is connected to the lean flow meter 19 and can continuously acquire the "flow rate of the aqueous amine solution fed from the stripper 12 to the absorber 11" measured by the lean flow meter 19 in real time.

[0026] The control device 22 is a device including a computer equipped with a CPU, RAM, ROM, and I / F. A computer program for controlling the collection device 10a is stored in advance in the ROM of the computer. The CPU of the computer reads the computer program stored in the ROM, expands it in the RAM (using the RAM as a work area) and executes it. This controls the collection device 10a.

[0027] The configurations of the absorber 11, the stripper 12, the rich path 13, the lean path 14, the reboiler 20, the condenser 21, and the heat exchanger 15 are not particularly limited, and various conventionally known configurations can be applied.

[0028] Next, the operation of the recovery device 10a will be described. The target gas that flows into the absorber 11 from an external target gas source through the target gas introduction path 23 moves upward inside the absorber 11 from the bottom to the top. The amine aqueous solution that flows into the absorber 11 through the lean path 14 by the operation of the lean pump 18 flows down inside the absorber 11 from the top to the bottom. Then, the amine aqueous solution and the target gas come into gas-liquid contact (countercurrent contact) in the lower filler 112 arranged inside the absorber 11, and carbon dioxide contained in the target gas is absorbed into the amine aqueous solution. That is, carbon dioxide is removed (separated) from the target gas.

[0029] The target gas from which carbon dioxide has been removed (sometimes referred to as off-gas) passes through the upper filler 111 and is discharged to the outside of the absorption tower 11 through the target gas discharge path 24. The target gas from which carbon dioxide has been removed is cooled while passing through the upper filler 111. For this reason, water vapor contained in the target gas is removed from the target gas by condensation.

[0030] The aqueous amine solution that has absorbed carbon dioxide accumulates at the bottom of the absorption tower 11. As described above, the absorption tower 11 is provided with the liquid level gauge 16, which continuously measures the liquid level in real time. The control device 22 continuously acquires the measurement results of the liquid level by the liquid level gauge 16 in real time.

[0031] The aqueous amine solution accumulated at the bottom of the absorption tower 11 is fed to the stripper tower 12 through the rich path 13 and the heat exchanger 15 by the operation of the rich pump 17. The aqueous amine solution fed from the absorption tower 11 to the stripper tower 12 through the rich path 13 is heated (or preheated) by heat exchange with the aqueous amine solution flowing through the lean path 14 in the heat exchanger 15, and then flows into the stripper tower 12 from its upper part.

[0032] The aqueous amine solution that has flowed into the stripper 12 passes through the lower packing 122 and accumulates at the bottom of the stripper 12. A part of the aqueous amine solution that has accumulated at the bottom of the stripper 12 flows into the reboiler 20 and is heated by the reboiler 20. Steam generated in the reboiler 20 flows into the interior of the stripper 12, and then rises from the bottom of the stripper 12 through the lower packing 122. Then, the steam comes into countercurrent contact (gas-liquid contact) with the aqueous amine solution flowing down from the top of the lower packing 122. As a result, the aqueous amine solution flowing down from the top is heated, and carbon dioxide is stripped from the aqueous amine solution.

[0033] A mixture of water vapor generated by heating the amine aqueous solution and carbon dioxide stripped from the amine aqueous solution passes through the upper filler 121 of the stripper tower 12 and flows out of the stripper tower 12 through the carbon dioxide discharge path 25 connected to the top of the stripper tower 12. Then, water vapor is removed from this mixture in the condenser 21 arranged on the carbon dioxide discharge path 25. The condensed water generated in the condenser 21 is sent to the upper filler 121 of the stripper tower 12 through the return path 26. As a result, the condensed water is used to cool the mixture passing through the upper filler 121.

[0034] The amine aqueous solution accumulated at the bottom of the stripper tower 12 is fed toward the absorber tower 11 through the lean path 14 by the operation of the lean pump 18. The amine aqueous solution flowing through the lean path 14 exchanges heat with the amine aqueous solution flowing through the rich path 13 in the heat exchanger 15. This cools the amine aqueous solution fed from the stripper tower 12 toward the absorber tower 11 through the lean path 14. The amine aqueous solution that has passed through the heat exchanger 15 is then fed into the absorber tower 11 from its upper portion. The amine aqueous solution fed into the absorber tower 11 flows down inside the absorber tower 11, absorbing carbon dioxide contained in the target gas during the process.

[0035] In this manner, by the operation of the rich pump 17 and the lean pump 18, the amine aqueous solution is circulated through the absorption tower 11, the rich path 13, the stripper tower 12, and the lean path 14 in this order. During circulation, the amine aqueous solution repeats a reaction in which it absorbs carbon dioxide contained in the target gas in the absorption tower 11 and strips the carbon dioxide in the stripper tower 12.

[0036] Next, the operation of the control device 22 will be described.

[0037] As described above, one end of the rich passage 13 is connected to the bottom of the absorption tower 11. Therefore, if the liquid level is excessively low or if the amine aqueous solution is not accumulated at the bottom of the absorption tower 11, one end of the rich passage 13 will not be covered with the amine aqueous solution (in other words, the rich passage 13 will not be liquid-sealed by the amine aqueous solution). In this case, a part of the target gas inside the absorption tower 11 will flow into the stripper tower 12 through the rich passage 13, and the target gas may be mixed with the carbon dioxide released from the amine aqueous solution. If the target gas is mixed with the carbon dioxide, the purity of the carbon dioxide recovered by the recovery device 10a will decrease. On the other hand, if the liquid level becomes excessively high, one end of the target gas introduction passage 23 will be blocked by the amine aqueous solution, and as a result, the delivery (inflow) of the target gas through the target gas introduction passage 23 may be hindered. In addition, if the amine aqueous solution flows back through the target gas introduction passage 23, the target gas introduction passage 23 and the air pump provided on the target gas introduction passage 23 may be corroded.

[0038] For this reason, the liquid level is required to be maintained at an appropriate level, that is, a level at which the rich passage 13 can be sealed with the amine aqueous solution and the amine aqueous solution does not block one end of the target gas introduction passage 23 (the amine aqueous solution does not flow into the target gas introduction passage 23). Therefore, such an appropriate liquid level is set in advance as a target liquid level. This target liquid level may have a certain predetermined range. Then, the control device 22 controls the output of the rich pump 17 so that the actual liquid level becomes the target liquid level (or so that the actual liquid level approaches the target liquid level). For example, the control device 22 performs feedback control (more specifically, PID control) of the output of the rich pump 17 using the liquid level as a control amount. Note that "controlling the output of the rich pump 17" can also be expressed as "controlling the flow rate (feed amount) of the amine aqueous solution by the rich pump 17" (the same applies to other pumps). Note that the target liquid level is stored in the ROM of the control device 22 in advance. Then, when controlling the rich pump 17, the control device 22 reads out the target liquid level from the ROM and uses it.

[0039] Specifically, the control device 22 continuously acquires the liquid level of the absorber 11 in real time. Furthermore, the control device 22 continuously calculates the rate of change of the liquid level with respect to time (hereinafter, may be simply referred to as "rate of change") using the acquired liquid level. Then, the control device 22 controls the output of the rich pump 17 according to the combination of the liquid level and the rate of change.

[0040] For example, when the current liquid level height is the target liquid level height and the magnitude of the absolute value of the rate of change is within a predetermined threshold value, the control device 22 maintains the output of the rich pump 17 at the current output. When the current liquid level height is the target liquid level height, the magnitude of the absolute value of the rate of change exceeds a predetermined threshold value and the rate of change is a positive value (i.e., when the liquid level height is rising), the control device 22 increases the output of the rich pump 17 from the current output. When the current liquid level height is the target liquid level height, the magnitude of the absolute value of the rate of change exceeds a predetermined threshold value and the rate of change is a negative value (i.e., when the liquid level height is falling), the control device 22 decreases the output of the rich pump 17 from the current output.

[0041] Furthermore, when the current liquid level height is higher than the target liquid level height, the control device 22 increases the output of the rich pump 17 from the current output. In this case, the control device 22 adjusts the degree of increase in the output according to the rate of change. Specifically, the greater the rate of change, the greater the degree of increase in the output. On the other hand, when the current liquid level height is lower than the target liquid level height, the control device 22 decreases the output of the rich pump 17 from the current output. In this case as well, the control device 22 adjusts the degree of decrease in the output according to the rate of change. Specifically, the greater the rate of change, the greater the degree of decrease in the output. However, the method of controlling the rich pump 17 by the control device 22 is not limited to the above method.

[0042] In this embodiment, the control device 22 controls the output of the lean pump 18 based on the measurement result of the flow rate of the amine aqueous solution by the lean flowmeter 19 so that the flow rate of the amine aqueous solution fed from the stripper 12 to the absorber 11 becomes the target flow rate (or approaches the target flow rate). As such control, for example, feedback control using the measurement result of the flow rate of the amine aqueous solution (feedback control using the flow rate of the amine aqueous solution as a controlled variable) can be applied. The target flow rate is specified in advance and stored in the ROM of the control device 22 in advance.

[0043] According to this configuration, the liquid level can be maintained at the target liquid level or can be brought close to the target liquid level. That is, the liquid level can be maintained at an appropriate level. Therefore, the target gas is prevented or suppressed from flowing into the stripper 12 through the rich path 13 due to the liquid level being excessively low (or the amine aqueous solution being depleted). Therefore, the purity of the carbon dioxide recovered by the recovery device 10a can be prevented or suppressed from decreasing. Furthermore, according to this configuration, the liquid level can be prevented or suppressed from becoming excessively high, causing the amine aqueous solution to block the target gas introduction path 23 or flow into the target gas introduction path 23. Therefore, the supply of the target gas to the absorption tower 11 is prevented or suppressed from being hindered, and corrosion of the components and pump of the target gas introduction path 23 due to the amine aqueous solution can be prevented or suppressed.

[0044] Second Embodiment Next, a second embodiment will be described. Fig. 2 is a schematic diagram showing the configuration of a recovery device 10b according to the second embodiment. Note that the same reference numerals as in the first embodiment are used to indicate the configurations common to the first embodiment, and the description may be omitted. As shown in Fig. 2, the recovery device 10b according to the second embodiment includes a rich flow meter 30. Other than that, the configurations common to the first embodiment can be applied.

[0045] The rich flowmeter 30 is configured to continuously measure in real time the flow rate of the amine aqueous solution flowing through the rich path 13 from the absorption tower 11 to the stripper tower 12, i.e., the flow rate of the amine aqueous solution fed from the absorption tower 11 to the stripper tower 12. The control device 22 is connected to the rich flowmeter 30, and can obtain the measurement result of the flow rate of the amine aqueous solution by the rich flowmeter 30 in real time. The configuration of the rich flowmeter 30 is not particularly limited, and a conventionally known flowmeter capable of measuring the flow rate of various liquids can be applied.

[0046] The control device 22 continuously acquires in real time the "measurement result of the flow rate of the amine aqueous solution fed to the absorption tower 11" by the lean flowmeter 19 and the "measurement result of the flow rate of the amine aqueous solution fed from the absorption tower 11 to the stripper tower 12" by the rich flowmeter 30. Then, the control device 22 compares both values ​​with a target flow rate, and controls the output of the lean pump 18 and the rich pump 17 so that both values ​​become equal to or approach the target flow rate.

[0047] The control device 22 continuously measures the liquid level in the absorber 11 in real time and calculates the rate of change of the liquid level, as in the first embodiment. Then, the control device 22 controls the output of the rich pump 17 in accordance with the liquid level and the rate of change, as in the first embodiment.

[0048] In this case, the control device 22 first controls the outputs of the rich pump 17 and the lean pump 18 based on the measurement results of the rich flowmeter 30 and the lean flowmeter 19 so that the flow rate of the amine aqueous solution fed from the absorption tower 11 to the stripper tower 12 and the flow rate of the amine aqueous solution fed from the stripper tower 12 to the absorption tower 11 become the target flow rates, respectively. For example, the control device 22 feedback-controls the output of the rich pump 17 using the flow rate of the amine aqueous solution fed from the absorption tower 11 to the stripper tower 12 as the controlled amount. Similarly, the control device 22 feedback-controls the output of the lean pump 18 using the flow rates of the amine aqueous solution fed from the stripper tower 12 to the absorption tower 11 as the controlled amount, respectively. Then, after the values ​​of both have become the target flow rates, the control device 22 controls the output of the rich pump 17 based on the liquid level and the rate of change so that the liquid level of the absorption tower 11 is maintained at the target liquid level or approaches the target liquid level.

[0049] Furthermore, the control device 22 may control the output of the rich pump 17 based on the measurement result of the flow rate of the amine aqueous solution by the rich flowmeter 30, and control the output of the rich pump 17 based on the liquid level and its rate of change in parallel. For example, while the liquid level is at the target liquid level, the control device 22 controls the output of the rich pump 17 based on the measurement result by the rich flowmeter 30 so that the flow rate per unit time of the amine aqueous solution fed from the absorption tower 11 to the stripper tower 12 is maintained at the target flow rate. Then, when the liquid level deviates from the target liquid level (or when the liquid level is about to deviate from the target liquid level), the control device 22 controls the output of the rich pump 17 based on the liquid level and the rate of change.

[0050] According to the second embodiment, it is possible to obtain the same effects as those of the first embodiment. Furthermore, according to the second embodiment, since the output of the rich pump 17 is controlled based on the measurement result of the flow rate of the amine aqueous solution by the rich flowmeter 30, it is easier to maintain the flow rate of the amine aqueous solution at the target flow rate (or to bring it closer to the target flow rate) and to stabilize the flow rate of the amine aqueous solution, compared to control using only the liquid level height and the rate of change.

[0051] <Third embodiment> Next, a third embodiment will be described. Fig. 3 is a schematic diagram showing the configuration of a recovery apparatus 10c according to the third embodiment. The recovery apparatus 10c according to the third embodiment includes a plurality of absorption towers 11U, 11M, and 11D (in other words, multi-stage absorption towers). That is, it can be said that the recovery apparatus 10c according to the third embodiment includes a configuration in which another absorption tower (second carbon dioxide absorption tower of the present invention) different from the absorption tower (first carbon dioxide absorption tower of the present invention) of the recovery apparatus 10a according to the first embodiment is added to the upstream side of the flow of the amine aqueous solution of the absorption tower.

[0052] 3 and the following description, a configuration including three absorption towers 11U, 11M, and 11D (three-stage absorption towers) is illustrated. For ease of explanation, the three absorption towers may be distinguished by referring to the absorption tower located at the most upstream position in the flow of the amine aqueous solution as the "top absorption tower 11U," the absorption tower located at the most downstream position as the "bottom absorption tower 11D," and the absorption tower located between them as the "middle absorption tower 11M." However, the number of absorption towers (the number of stages of the absorption tower) included in the recovery device 10c is not limited.

[0053] The bottom-most stage absorption tower 11D is an example of a first carbon dioxide absorption tower of the present invention. The top-most stage absorption tower 11U and the intermediate stage absorption tower 11M are examples of a second carbon dioxide absorption tower of the present invention. Note that, inside each of the absorption towers 11U, 11M, and 11D of each stage, an upper filler 111 and a lower filler 112 are provided, similar to the absorption tower 11 of the first embodiment. Moreover, the bottom-most stage absorption tower 11D, the intermediate stage absorption tower 11M, and the top-most stage absorption tower 11U are all configured to be able to store an amine aqueous solution inside (at the bottom), similar to the absorption tower 11 of the first embodiment.

[0054] One end of the target gas introduction path 23 and one end of the intermediate gas supply path 34 are connected to the lowest-stage absorption tower 11D. The target gas introduction path 23 is a path for introducing the target gas into the inside of the lowest-stage absorption tower 11D, and the other end is connected to a source of the target gas. One end of the target gas introduction path 23 is connected to a position somewhat above the bottom surface of the inside of the lowest-stage absorption tower 11D (but below the lower packing material 112) so that the amine aqueous solution accumulated inside the lowest-stage absorption tower 11D does not hinder the supply of the target gas to the lowest-stage absorption tower 11D. The intermediate gas supply path 34 is a path for supplying the target gas from the lowest-stage absorption tower 11D to the intermediate-stage absorption tower 11M. One end of the intermediate gas supply path 34 is connected to the upper part of the uppermost packing material 111 near the upper end of the lowest-stage absorption tower 11D.

[0055] One end of the rich path 13 is connected to the lowest absorption tower 11D. The rich path 13 is a path for feeding the amine aqueous solution from the lowest absorption tower 11D to the stripper tower 12. One end of the rich path 13 is connected to the bottom of the lowest absorption tower 11D or in its vicinity, and below the position where one end of the target gas introduction path 23 is connected, so that the amine aqueous solution stored inside the lowest absorption tower 11D can be fed to the stripper tower 12. In addition, one end of the intermediate liquid feed path 32 is connected to the lowest absorption tower 11D. The intermediate liquid feed path 32 is a path for feeding the amine aqueous solution from the intermediate absorption tower 11M to the lowest absorption tower 11D. One end of the intermediate liquid feed path 32 is connected above the lower filler 112 and below the upper filler 111 so that the amine aqueous solution can flow to the lower filler 112 of the lowest absorption tower 11D.

[0056] The other end of the intermediate gas supply passage 34 and one end of the intermediate gas supply passage 33 are connected to the intermediate-stage absorption tower 11M. The intermediate gas supply passages 33, 34 are examples of intermediate gas passages of the present invention. The other end of the intermediate gas supply passage 34 is connected to a position spaced somewhat above the bottom surface of the intermediate-stage absorption tower 11M (but below the lower packing material 112) so that the inflow of the target gas from the lowermost absorption tower 11D is not hindered by the aqueous amine solution accumulated inside the intermediate-stage absorption tower 11M. The intermediate gas supply passage 33 is a passage for supplying the target gas from the intermediate-stage absorption tower 11M to the uppermost absorption tower 11U. One end of the intermediate gas supply passage 33 is connected to the upper part of the uppermost packing material 111 near the upper end of the intermediate-stage absorption tower 11M.

[0057] The other end of the intermediate liquid supply passage 32 is connected to the intermediate-stage absorption tower 11M. The other end of the intermediate liquid supply passage 32 is connected to the bottom of the intermediate-stage absorption tower 11M or in its vicinity, and below the position where the other end of the intermediate gas supply passage 34 is connected, so that the aqueous amine solution accumulated inside the intermediate-stage absorption tower 11M can be supplied to the lowermost absorption tower 11D. In addition, one end of the intermediate liquid supply passage 31 is connected to the intermediate-stage absorption tower 11M. The intermediate liquid supply passage 31 is a passage for supplying the aqueous amine solution from the uppermost absorption tower 11U to the intermediate-stage absorption tower 11M. One end of the intermediate liquid supply passage 31 is connected above the lower filler 112 and below the upper filler 111, so that the aqueous amine solution can flow into the lower filler 112 of the intermediate-stage absorption tower 11M.

[0058] The other end of the intermediate gas supply path 33 and one end of the target gas discharge path 24 are connected to the uppermost absorber 11U. The other end of the intermediate gas supply path 33 is connected to a position spaced some distance above the bottom surface of the interior of the uppermost absorber 11U (but below the lower filler 112) so that the inflow of the target gas from the intermediate absorber 11M is not hindered by the aqueous amine solution accumulated inside the uppermost absorber 11U. The target gas discharge path 24 is a path for discharging the target gas from the uppermost absorber 11U to the outside. One end of the target gas discharge path 24 is connected to above the upper filler 111 near the upper end of the uppermost absorber 11U.

[0059] The other end of the intermediate liquid supply path 31 is connected to the top-most absorber 11U. The other end of the intermediate liquid supply path 31 is connected to the bottom of the top-most absorber 11U or in its vicinity, and below the position where the other end of the intermediate gas supply path 33 is connected, so that the aqueous amine solution stored inside the top-most absorber 11U can be supplied to the intermediate absorber 11M. In addition, one end of a lean path 14 is connected to the top-most absorber 11U. The lean path 14 is a path for supplying the aqueous amine solution from the stripper 12 to the top-most absorber 11U. One end of the lean path 14 is connected above the lower filler 112 and below the upper filler 111, so that the aqueous amine solution can flow to the lower filler 112 of the top-most absorber 11U.

[0060] Intermediate pumps 35, 36 are provided in the intermediate liquid sending paths 31, 32, respectively. The intermediate pumps 35, 36 are examples of the second pump of the present invention. The intermediate pump 35 is configured to be able to send the aqueous amine solution accumulated inside the uppermost stage absorption tower 11U to the intermediate stage absorption tower 11M when operated. The intermediate pump 36 is configured to be able to send the aqueous amine solution accumulated inside the intermediate stage absorption tower 11M to the lowermost stage absorption tower 11D when operated.

[0061] In this manner, the absorption towers 11U, 11M, and 11D of each stage are connected in series with each other by intermediate gas supply paths 33 and 34 so that the target gas flows through the lowest stage absorption tower 11D, the intermediate stage absorption tower 11M, and the highest stage absorption tower 11U in that order. Also, the absorption towers 11U, 11M, and 11D of each stage are connected in series with each other by intermediate liquid supply paths 31 and 32 so that the amine aqueous solution flows through the highest stage absorption tower 11U, the intermediate stage absorption tower 11M, and the lowest stage absorption tower 11D in that order.

[0062] The absorption towers 11U, 11M, 11D of each stage are provided with liquid level measuring devices 16U, 16M, 16D. The liquid level measuring device 16D provided in the lowermost stage absorption tower 11D is an example of a first liquid level measuring device of the present invention, and the liquid level measuring devices 16U, 16M provided in the uppermost stage absorption tower 11U and the intermediate stage absorption tower 11M are examples of a second liquid level measuring device of the present invention. The liquid level measuring devices 16U, 16M, 16D can continuously measure the liquid level of the absorption towers 11U, 11M, 11D of each stage in real time.

[0063] The basic operation of the recovery device 10c according to the third embodiment is as follows. The amine aqueous solution accumulated inside the stripper 12 is fed to the top-most absorber 11U through the lean path 14 by the operation of the lean pump 18. The amine aqueous solution fed to the top-most absorber 11U flows down through the lower filler 112 and accumulates inside (specifically, at the bottom) of the top-most absorber 11U. The amine aqueous solution accumulated inside the top-most absorber 11U is fed to the intermediate absorber 11M through the intermediate liquid feed path 31 by the operation of the intermediate pump 35. Thereafter, the amine aqueous solution accumulates inside the bottom-most absorber 11D via the intermediate absorber 11M and the intermediate liquid feed path 32, and is fed to the stripper 12 through the rich path 13 by the operation of the rich pump 17. The aqueous amine solution comes into contact with the target gas while flowing inside the lowermost stage absorption tower 11D, the intermediate stage absorption tower 11M, and the uppermost stage absorption tower 11U, and absorbs carbon dioxide contained in the target gas.

[0064] Meanwhile, the target gas that has flowed into the inside of the lowermost absorber 11D through the target gas introduction path 23 flows through the lowermost absorber 11D, the intermediate gas supply path 34, the intermediate absorber 11M, the intermediate gas supply path 33, and the uppermost absorber 11U in that order. The carbon dioxide contained in the target gas comes into contact with the amine aqueous solution and is absorbed while flowing through the inside of the lowermost absorber 11D, the intermediate absorber 11M, and the uppermost absorber 11U. Therefore, the carbon dioxide concentration of the target gas decreases successively. The target gas is then discharged to the outside of the recovery device 10c through the target gas discharge path 24.

[0065] In the recovery apparatus 10c equipped with such a plurality of absorption towers 11U, 11M, 11D (multi-stage absorption towers), if the liquid level of the aqueous amine solution accumulated inside the lowermost absorption tower 11D is excessively low or excessively high, a problem similar to that in the first embodiment may occur.

[0066] Furthermore, when the liquid level of the intermediate-stage absorber 11M is excessively low, a part of the target gas present inside the intermediate-stage absorber 11M may return to the lowest-stage absorber 11D through the intermediate liquid feed path 32. Then, when a part of the target gas returns to the lowest-stage absorber 11D, the target gas introduced into the lowest-stage absorber 11D through the target gas introduction path 23 and the target gas returned to the lowest-stage absorber 11D through the intermediate liquid feed path 32 flow into the intermediate-stage absorber 11M through the intermediate gas feed path 34. Therefore, the amount of target gas introduced from the outside is reduced by the amount of the target gas returned to the lowest-stage absorber 11D through the intermediate liquid feed path 32. Therefore, the amount of target gas treated by the recovery device 10c is reduced. In other words, the efficiency of the recovery device 10c is reduced. Similarly, when the liquid level of the uppermost absorber 11U is excessively low, a part of the target gas present inside the uppermost absorber 11U may return to the intermediate-stage absorber 11M through the intermediate liquid feed path 31. Therefore, in this case as well, the same problem as described above may occur.

[0067] On the other hand, if the liquid level in the top-stage absorber 11U is excessively high, the amine aqueous solution may clog the other end of the intermediate gas supply passage 33, thereby hindering the inflow of the target gas from the intermediate-stage absorber 11M to the top-stage absorber 11U. Similarly, if the liquid level in the intermediate-stage absorber 11M is excessively high, the amine aqueous solution may clog the other end of the intermediate gas supply passage 34, thereby hindering the inflow of the target gas from the bottom-stage absorber 11D to the intermediate-stage absorber 11M. This may reduce the amount of target gas that the recovery device 10c can treat. In other words, the efficiency of the recovery device 10c may decrease.

[0068] In the third embodiment, the control device 22 continuously acquires the measurement results of the liquid level of the absorber 11U, 11M, 11D of each stage by the liquid level measuring device 16U, 16M, 16D of the absorber 11U, 11M, 11D of each stage in real time. Furthermore, the control device 22 continuously calculates the change rate of the absorber 11U, 11M, 11D of each stage in real time from the acquired measurement results of the liquid level. Then, the control device 22 controls the output (flow rate of the amine aqueous solution) of the rich pump 17 and the intermediate pumps 35, 36 according to the liquid level height and the change rate so that the liquid level height of the absorber 11U, 11M, 11D of each stage becomes the target liquid level height (or approaches the target liquid level height). The control method of the output of the rich pump 17 and the intermediate pumps 35, 36 is the same as that of the first embodiment.

[0069] According to such a configuration, the liquid level of the absorption towers 11U, 11M, 11D of each stage can be maintained at the target liquid level or can be brought close to the target liquid level. That is, the liquid level of the absorption towers 11U, 11M, 11D of each stage can be maintained at an appropriate height. Therefore, the same effect as that of the first embodiment can be achieved. Furthermore, it is possible to prevent or suppress the target gas from flowing into the other absorption towers 11M, 11D adjacent to the lower stage side due to the liquid level of the absorption towers 11U, 11M, 11D of each stage becoming excessively low (or the amine aqueous solution being exhausted), and to prevent or suppress the amine aqueous solution from flowing into the other absorption towers 11M, 11D adjacent to the lower stage side due to the liquid level of the absorption towers 11U, 11M, 11D of each stage becoming excessively high. This makes it possible to prevent or suppress a decrease in the purity of the carbon dioxide recovered by the recovery device 10c. In addition, by preventing or suppressing the flow of the aqueous amine solution into the intermediate gas supply paths 33, 34, obstruction of the flow of the target gas through the intermediate gas supply paths 33, 34 into the absorption towers 11U, 11M of each stage is prevented or suppressed.

[0070] <Fourth embodiment> Next, a fourth embodiment will be described. Fig. 4 is a schematic diagram showing the configuration of a recovery device 10d according to the fourth embodiment. As shown in Fig. 4, the recovery device 10d includes a multi-stage absorption tower (absorption towers 11U, 11M, 11D). Furthermore, the recovery device 10d includes a rich flowmeter 30 and intermediate flowmeters 37, 38. The configuration of the absorption towers 11U, 11M, 11D of each stage and the manner of mutual connection are common to the third embodiment.

[0071] The rich flowmeter 30 can continuously measure the "flow rate of the amine aqueous solution fed from the lowermost absorber 11D to the stripper 12" in real time, similar to the rich flowmeter 30 of the second embodiment. The intermediate flowmeter 37 can continuously measure the "flow rate of the amine aqueous solution fed from the uppermost absorber 11U to the intermediate absorber 11M" in real time. The intermediate flowmeter 38 can continuously measure the "flow rate of the amine aqueous solution fed from the intermediate absorber 11M to the lowermost absorber 11D" in real time. In addition, the control device 22 can obtain the measurement results of these intermediate flowmeters 37 and 38 in real time. Note that the other configurations are applicable to the recovery device 10c according to the third embodiment. For this reason, it can be said that the recovery device 10d according to the fourth embodiment has a configuration in which the rich flowmeter 30 and the intermediate flowmeters 37 and 38 are added to the recovery device 10c according to the third embodiment.

[0072] The control device 22 continuously acquires in real time the "measurement result of the flow rate of the amine aqueous solution fed to the uppermost absorber 11U" by the lean flowmeter 19, the "measurement result of the flow rate of the amine aqueous solution fed to the intermediate absorber 11M" by the intermediate flowmeter 37, the "measurement result of the flow rate of the amine aqueous solution fed to the lowermost absorber 11D" by the intermediate flowmeter 38, and the "measurement result of the flow rate of the amine aqueous solution fed from the absorber 11 to the stripper 12" by the rich flowmeter 30. Then, the control device 22 compares these values ​​with the target flow rates, and controls the outputs of the lean pump 18, the intermediate pumps 35, 36, and the rich pump 17 so that these values ​​become the target flow rates or approach the target flow rates.

[0073] The control device 22 continuously measures the liquid level of each absorber 11U, 11M, 11D in real time and calculates the rate of change of the liquid level, as in the first embodiment. Then, the control device 22 controls the output of the intermediate pumps 35, 36 and the rich pump 17 in accordance with the liquid level and the rate of change, as in the first embodiment.

[0074] In this case, the control device 22 first controls the outputs of the rich pump 17, the intermediate pumps 35, 36, and the lean pump 18 based on the measurement results of the rich flowmeter 30, the intermediate flowmeters 37, 38, and the lean flowmeter 19 so that the flow rate of the amine aqueous solution fed from the lowermost absorber 11D to the stripper 12, the flow rate of the amine aqueous solution fed from the stripper 12 to the uppermost absorber 11U, the flow rate of the amine aqueous solution fed from the uppermost absorber 11U to the intermediate absorber 11M, and the flow rate of the amine aqueous solution fed from the intermediate absorber 11M to the lowermost absorber 11D, respectively, become the target flow rates. Then, after these values ​​become the target flow rates, the control device 22 controls the outputs of the intermediate pumps 35, 36, and the rich pump 17 based on the liquid level height and the rate of change so that the liquid level heights of the absorbers 11U, 11M, and 11D of each stage are maintained at the target liquid level heights or approach the target liquid level heights.

[0075] Similarly to the second embodiment, the control device 22 may control, in parallel, the output of the rich pump 17 based on the measurement result of the flow rate of the amine aqueous solution by the rich flowmeter 30, and the output of the rich pump 17 based on the liquid level and its rate of change. Furthermore, the control device 22 may control, in parallel, the output of the intermediate pumps 35, 36 based on the measurement result of the flow rate of the amine aqueous solution by the intermediate flowmeters 37, 38, and the output of the intermediate pumps 35, 36 based on the liquid level and its rate of change.

[0076] According to this embodiment, the same effects as those of the third embodiment can be achieved. Furthermore, in the recovery apparatus 10c equipped with a multi-stage absorption tower, the same effects as those of the recovery apparatus 10b according to the second embodiment equipped with a single-stage absorption tower can be achieved. Note that the recovery apparatus 10d according to the fourth embodiment does not need to be equipped with the rich flowmeter 30. In this case, the same method as that of the third embodiment can be applied to control the output of the rich pump 17.

[0077] <Fifth embodiment> Next, a fifth embodiment will be described. Fig. 5 is a schematic diagram showing the configuration of a recovery device 10e according to the fifth embodiment. The recovery device 10e according to the fifth embodiment includes a multi-stage absorption tower (absorption towers 11U, 11M, 11D) as in the third embodiment. The configuration of the absorption towers 11U, 11M, 11D of each stage and the manner of connection of the absorption towers 11U, 11M, 11D of each stage are the same as in the third embodiment.

[0078] As shown in FIG. 5, the recovery apparatus 10e according to the fifth embodiment includes intermediate pumps 35, 36 and intermediate flow meters 37, 38 provided in the intermediate liquid feed paths 31, 32, a liquid level measuring instrument 16D provided in the lowermost stage absorption tower 11D (i.e., the first carbon dioxide absorption tower of the present invention), and a rich pump 17 provided on the rich path 13. The intermediate pumps 35, 36 are an example of the second pump of the present invention, and the lean pump 18 is an example of the third pump of the present invention. However, the liquid level measuring instruments are not provided in the intermediate stage absorption tower 11M and the uppermost stage absorption tower 11U (i.e., the second carbon dioxide absorption tower of the present invention). For this reason, it can be said that the recovery apparatus 10e according to the fifth embodiment has a configuration in which the liquid level measuring instruments of the uppermost stage absorption tower 11U and the intermediate stage absorption tower 11M (i.e., the second carbon dioxide absorption tower of the present invention) are removed from the recovery apparatus 10c according to the third embodiment, and the intermediate flow meters 37, 38 similar to those of the fourth embodiment are provided in the intermediate liquid feed paths 31, 32. The intermediate flow meters 37 and 38 are configured to be able to measure the flow rate of a fluid in which liquid and gas are mixed.

[0079] The control device 22 continuously acquires in real time the "flow rate of the amine aqueous solution fed to the top-stage absorber 11U" measured by the lean flowmeter 19, the "flow rate of the amine aqueous solution fed from the top-stage absorber 11U to the intermediate-stage absorber 11M" measured by the intermediate flowmeter 37, and the "flow rate of the amine aqueous solution fed from the intermediate-stage absorber 11M to the bottom-stage absorber 11D" measured by the intermediate flowmeter 38. That is, the control device 22 continuously acquires the flow rates of the amine aqueous solution fed to the absorber towers 11U, 11M, and 11D of each stage in real time.

[0080] The controller 22 controls the output of the lean pump 18 based on the measurement results of the flow rate of the amine aqueous solution by the lean flowmeter 19 so that the "flow rate of the amine aqueous solution fed to the top-stage absorber 11U" becomes equal to or approaches the target flow rate, which is a predetermined target value. The controller 22 also controls the output of the intermediate pump 35 based on the measurement results of the flow rate of the amine aqueous solution by the lean flowmeter 19 and the intermediate flowmeter 37 so that the flow rate of the fluid fed from the top-stage absorber 11U to the intermediate-stage absorber 11M becomes greater than the flow rate of the amine aqueous solution fed from the stripper 12 to the top-stage absorber 11U. Similarly, the controller 22 controls the output of the intermediate pump 36 based on the measurement results of the flow rate of the amine aqueous solution by the intermediate flowmeters 37 and 38 so that the flow rate of the fluid fed from the intermediate-stage absorber 11M to the bottom-stage absorber 11D becomes greater than the flow rate of the amine aqueous solution fed from the top-stage absorber 11U to the intermediate-stage absorber 11M.

[0081] For example, the control device 22 calculates the difference between the measurement results of the flow rate of the amine aqueous solution by the lean flowmeter 19 and the intermediate flowmeter 37 and the measurement result of the flow rate of the fluid by the intermediate flowmeter 37, and controls the output of the intermediate pump 35 so that the calculated difference becomes a predetermined target value. In this case, the output of the lean pump 18 is controlled so that the flow rate of the amine aqueous solution fed to the uppermost absorber 11U becomes a predetermined target value. Similarly, the control device 22 calculates the difference between the measurement results of the flow rate of the fluid by the intermediate flowmeter 37 and the intermediate flowmeter 38, and controls the output of the intermediate pump 36 so that the calculated difference becomes a predetermined value (target value). In other words, the control device 22 performs feedback control using these differences as control amounts.

[0082] When the output of the intermediate pump 35 is controlled so that "the flow rate of the fluid fed from the top-stage absorber 11U to the intermediate-stage absorber 11M is greater than the flow rate of the amine aqueous solution fed from the stripper 12 to the top-stage absorber 11U," the total amount of "the amine aqueous solution fed from the top-stage absorber 11U to the intermediate-stage absorber 11M" and an amount of "the target gas present in the top-stage absorber 11U" corresponding to the magnitude of the output of the intermediate pump 35 are fed from the top-stage absorber 11U to the intermediate-stage absorber 11M. As a result, the top-stage absorber 11U is maintained in a state in which the amine aqueous solution does not accumulate therein, and the target gas in an amount corresponding to the output of the intermediate pump 35 returns to the intermediate-stage absorber 11M. The same applies to the intermediate pump 36 and the intermediate-stage absorber 11M.

[0083] The control device 22 continuously acquires the liquid level measurement results by the liquid level gauge 16D of the lowest absorber 11D in real time, and continuously calculates the rate of change of the liquid level of the lowest absorber 11D in real time. Then, the control device 22 controls the output of the rich pump 17 (flow rate of the amine aqueous solution) according to the liquid level and the rate of change so that the liquid level of the lowest absorber 11D becomes the target liquid level (or approaches the target liquid level). The method of controlling the output of the rich pump 17 is the same as in the first embodiment.

[0084] In this manner, the control device 22 controls the output of the intermediate pumps 35, 36 and the rich pump 17 so that the amine aqueous solution is maintained in a state where it accumulates inside the lowest absorption tower 11D and so that the amine aqueous solution is maintained in a state where it does not accumulate inside the absorption towers 11U, 11M other than the lowest one.

[0085] According to such control, the top-stage absorber 11U and the intermediate-stage absorber 11M are maintained in a state in which no aqueous amine solution accumulates therein. Therefore, the inflow of the target gas into the top-stage absorber 11U through the intermediate gas supply path 33 is not hindered. Similarly, the inflow of the target gas into the intermediate-stage absorber 11M through the intermediate gas supply path 34 is not hindered. Therefore, it is possible to prevent or suppress a decrease in the efficiency of the recovery device 10e.

[0086] On the other hand, as the output of the intermediate pumps 35, 36 increases, the flow rate of the target gas returning from the top absorber 11U to the intermediate absorber 11M and the amount of the target gas returning from the intermediate absorber 11M to the bottom absorber 11D increase. That is, the amount of the target gas returning from the upstream absorber (upper stage) of the flow of the amine aqueous solution to the downstream absorber (lower stage) increases. And, when the amount of the target gas returning to the downstream absorber increases, the efficiency of the recovery device 10e decreases as described above. Therefore, the control device 22 controls the output of each intermediate pump 35, 36 so that the flow rate of the fluid sent from the absorber 11U, 11M of each stage except the bottom absorber 11D to the adjacent absorber 11M, 11D on the downstream side becomes larger than the flow rate of the amine aqueous solution sent to the absorber 11U, 11M of each stage, but the difference is as small as possible.

[0087] According to such control, it is possible to prevent or suppress the target gas from being blocked from flowing into the absorption towers 11U, 11M of each stage other than the lowest absorption tower 11D due to the intermediate gas supply paths 33, 34 being blocked by the amine aqueous solution, while preventing or suppressing the target gas from returning to the downstream absorption towers 11M, 11D through the intermediate liquid supply paths 31, 32. Therefore, it is possible to prevent or suppress a decrease in the efficiency of the recovery device 10e.

[0088] According to the fifth embodiment, the absorbers 11U and 11M other than the lowest one do not require a liquid level measuring device. Also, since the output of the rich pump 17 is controlled based on the liquid level of the lowest absorber 11D, a flow meter equivalent to the rich flow meter 30 of the fourth embodiment is not required.

[0089] <Summary of the embodiment> The recovery devices 10a, 10b, 10c, 10d, and 10e according to the respective embodiments are A carbon dioxide stripping tower (stripping tower 12) configured so that carbon dioxide absorbed in the carbon dioxide absorbing solution (amine aqueous solution) is stripped from the carbon dioxide absorbing solution (amine aqueous solution); a first carbon dioxide absorption tower (absorption tower 11, lowermost absorption tower 11D) configured to be connected to a gas path (target gas introduction path 23) through which a gas containing carbon dioxide (target gas) is supplied from the outside and a carbon dioxide absorbing solution path (rich path 13) capable of supplying a carbon dioxide absorbing solution (amine aqueous solution) to a carbon dioxide stripper tower (stripping tower 12), and to absorb carbon dioxide contained in the gas (target gas) supplied via the gas path (target gas introduction path 23) into the carbon dioxide absorbing solution (amine aqueous solution); a first pump (rich pump 17) configured to operate to supply a carbon dioxide absorbing solution (amine aqueous solution) present inside the first carbon dioxide absorption tower (absorption tower 11, lowest stage absorption tower 11D) to the carbon dioxide stripper tower (stripping tower 12) via a carbon dioxide absorbing solution path (rich path 13); A first liquid level measuring device (liquid level measuring device 16, 16D) capable of measuring the liquid level of a carbon dioxide absorbing solution (amine aqueous solution) present inside the first carbon dioxide absorption tower (absorption tower 11, lowest stage absorption tower 11D); and a control device 22 that uses the measurement results of the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) to control the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the first pump (rich pump 17) so that the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) present inside the first carbon dioxide absorption tower (absorption tower 11, lowermost absorption tower 11D) falls within a predetermined range.

[0090] According to the recovery devices 10a, 10b, 10c, 10d, and 10e of the embodiments of the present invention, the liquid level of the first carbon dioxide absorption tower (absorption tower 11, lowest stage absorption tower 11D) can be maintained at or brought close to the target liquid level. Therefore, the liquid level is prevented or suppressed from being excessively low (or from being depleted of the carbon dioxide absorbing solution (amine aqueous solution)) and the gas (target gas) flows into the carbon dioxide stripper tower (stripping tower 12) through the carbon dioxide absorbing solution path (rich path 13). Therefore, the reduction in the purity of the carbon dioxide recovered by the recovery devices 10a, 10b, 10c, 10d, and 10e can be prevented or suppressed. In addition, according to such a configuration, the liquid level of the first carbon dioxide absorption tower (absorption tower 11, lowest stage absorption tower 11D) can be prevented or suppressed from being excessively high and the carbon dioxide absorbing solution (amine aqueous solution) clogging the gas path (target gas introduction path 23) or flowing into the gas path (target gas introduction path 23). This prevents or suppresses obstruction of the supply of gas (target gas) to the first carbon dioxide absorption tower (absorption tower 11, lowest absorption tower 11D), and also prevents or suppresses corrosion of the components and pumps of the gas path (target gas introduction path 23) due to the carbon dioxide absorption solution (aqueous amine solution).

[0091] The recovery devices 10b and 10d according to the second and fourth embodiments are as follows: A first flow meter (rich flow meter 30) is provided that is configured to measure the flow rate of the carbon dioxide absorbing solution (amine aqueous solution) supplied from the first carbon dioxide absorption tower (absorption tower 11, lowest stage absorption tower 11D) to the carbon dioxide stripper tower (stripping tower 12) through a carbon dioxide absorbing solution path (rich path 13), The control device 22 uses the measurement results of the liquid level height of the carbon dioxide absorbing solution (aqueous amine solution) and the measurement results of the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) to control the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the first pump (rich pump 17) so that the liquid level height of the carbon dioxide absorbing solution (aqueous amine solution) present inside the first carbon dioxide absorption tower (absorption tower 11, lowermost absorption tower 11D) falls within a predetermined range.

[0092] According to such a configuration, the output of the first pump (rich pump 17) is controlled based on the measurement results of the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the first flow meter (rich flow meter 30). Therefore, compared to control using only the liquid level height and the rate of change, it is easier to maintain the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) at the target flow rate (or to bring it close to the target flow rate), and the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) can be stabilized.

[0093] The recovery devices 10c and 10d according to the third and fourth embodiments are: a plurality of carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M, bottom-most stage absorption tower 11D) including one first carbon dioxide absorption tower (bottom-most stage absorption tower 11D) and one or more second carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M) different from the one first carbon dioxide absorption tower (bottom-most stage absorption tower 11D), the carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M, bottom-most stage absorption tower 11D) being connected in series to each other by intermediate carbon dioxide absorbing solution paths (intermediate liquid supply paths 31, 32) through which a carbon dioxide absorbing solution (aqueous amine solution) can flow and intermediate gas paths (intermediate gas supply paths 33, 34) through which a gas (target gas) can flow, such that the first carbon dioxide absorption tower (bottom-most stage absorption tower 11D) is located at the most downstream side of a flow of the carbon dioxide absorbing solution (aqueous amine solution); a second pump (intermediate pump 35, 36) configured to operate to supply a carbon dioxide absorbing solution (an aqueous amine solution) present inside one of the carbon dioxide absorption towers adjacent to each other (the uppermost stage absorption tower 11U, the intermediate stage absorption tower 11M) to the other carbon dioxide absorption tower (the intermediate stage absorption tower 11M, the lowermost stage absorption tower 11D); The second carbon dioxide absorption tower (top stage absorption tower 11U, middle stage absorption tower 11M) is equipped with a second liquid level measuring instrument (liquid level measuring instruments 16U, 16M) capable of measuring the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) present inside the second carbon dioxide absorption tower (top stage absorption tower 11U, middle stage absorption tower 11M).

[0094] In addition, the recovery device 10d according to the fourth embodiment further includes: The second flowmeter (intermediate flowmeters 37, 38) are provided, which are configured to be able to measure the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) fed by the second pump (intermediate pumps 35, 36).

[0095] The control device 22 of the recovery device 10c according to the third embodiment uses the measurement result of the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) by the second liquid level gauge (liquid level gauges 16U, 16M) to control the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the intermediate pumps 35, 36 so that the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) present inside the second carbon dioxide absorption tower (top stage absorption tower 11U, middle stage absorption tower 11M) falls within a predetermined range.

[0096] The control device 22 of the recovery device 10d according to the fourth embodiment uses the measurement results of the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) by the second liquid level measuring instruments (liquid level measuring instruments 16U, 16M) and the measurement results of the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the second flow meters (intermediate flow meters 37, 38) to control the flow rate of the carbon dioxide absorbing solution by the second pump (intermediate pumps 35, 36) so that the liquid level of the carbon dioxide absorbing solution (aqueous amine solution) present inside the second carbon dioxide absorption tower (top stage absorption tower 11U, intermediate stage absorption tower 11M) falls within a predetermined range.

[0097] According to such a configuration, in a configuration including a multi-stage absorption tower, the liquid level of each stage of the carbon dioxide absorption tower (the uppermost stage absorption tower 11U, the intermediate stage absorption tower 11M, and the lowermost stage absorption tower 11D) can be maintained at the target liquid level or can be brought close to the target liquid level. Specifically, it is possible to prevent or suppress the gas (target gas) from flowing (returning) through a path that receives the supply of the carbon dioxide absorbing solution (amine aqueous solution) from the upper carbon dioxide absorption tower (meaning the carbon dioxide absorption tower adjacent to the upstream side of the flow of the carbon dioxide absorbing solution (amine aqueous solution) and the downstream side of the flow of the target gas) due to the liquid level of each stage of the carbon dioxide absorption tower (the uppermost stage absorption tower 11U, the intermediate stage absorption tower 11M) becoming excessively low (or due to the carbon dioxide absorbing solution (amine aqueous solution) disappearing). As a result, it is possible to prevent or suppress the amount of the target gas to be treated from decreasing by the amount of the returned gas (target gas) (in other words, the amount of the gas (target gas) delivered from the outside is decreased), and therefore it is possible to prevent or suppress the efficiency of carbon dioxide absorption from decreasing. Furthermore, the gas (target gas) is prevented or suppressed from flowing into the carbon dioxide stripper (stripping tower 12) via the carbon dioxide absorbing solution path (rich path 13) due to the liquid level of the first carbon dioxide absorption tower (lowest stage absorption tower 11D) becoming excessively low (or the carbon dioxide absorbing solution (aqueous amine solution) becoming depleted). This makes it possible to prevent or suppress a decrease in the purity of the carbon dioxide recovered by the recovery devices 10c, 10d. Also, it is possible to prevent or suppress the carbon dioxide absorbing solution (aqueous amine solution) from flowing into other carbon dioxide absorption towers adjacent to the lower stage (middle stage absorption tower 11M, lowest stage absorption tower 11D) due to the liquid level of each stage of the carbon dioxide absorption towers (top stage absorption tower 11U, middle stage absorption tower 11M, lowest stage absorption tower 11D) becoming excessively high. In addition, by preventing or suppressing the carbon dioxide absorption solution (aqueous amine solution) from flowing into the intermediate gas path (intermediate air supply paths 33, 34), obstruction of the flow of gas (target gas) through the intermediate gas path (intermediate air supply paths 33, 34) into each stage of carbon dioxide absorption towers (top stage absorption tower 11U, intermediate stage absorption tower 11M) is prevented or suppressed.

[0098] The recovery device 10e according to the fifth embodiment is a plurality of carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M, bottom-most stage absorption tower 11D) including one first carbon dioxide absorption tower (lowest stage absorption tower 11D) and one or more second carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M) different from the one first carbon dioxide absorption tower (lowest stage absorption tower 11D), the plurality of carbon dioxide absorption towers (top-most stage absorption tower 11U, middle stage absorption tower 11M, bottom-most stage absorption tower 11D) being connected in series to each other by intermediate carbon dioxide absorbing solution paths (intermediate liquid supply paths 31, 32) through which a carbon dioxide absorbing solution (aqueous amine solution) can flow and intermediate gas paths (intermediate gas supply paths 33, 34) through which a gas (target gas) can flow, such that the first carbon dioxide absorption tower (bottom stage absorption tower 11D) is located at the most downstream side of a flow of the carbon dioxide absorbing solution (aqueous amine solution); a second pump (intermediate pumps 35, 36) configured to operate to supply fluid present inside the second carbon dioxide absorption tower (top-most stage absorption tower 11U, intermediate stage absorption tower 11M) to other carbon dioxide absorption towers (intermediate stage absorption tower 11M, bottom-most stage absorption tower 11D) connected to the second carbon dioxide absorption tower (top-most stage absorption tower 11U, intermediate stage absorption tower 11M) via intermediate carbon dioxide absorbing solution paths (intermediate liquid supply paths 31, 32); a third pump (lean pump 18) configured to operate to supply the carbon dioxide absorbing solution (aqueous amine solution) present inside the carbon dioxide stripper (stripping tower 12) to the single second carbon dioxide absorption tower (top stage absorption tower 11U) or to the second carbon dioxide absorption tower (top stage absorption tower 11U) located most upstream in the flow of the carbon dioxide absorbing solution (aqueous amine solution) among the plurality of second carbon dioxide absorption towers (top stage absorption tower 11U, middle stage absorption tower 11M); a second flow meter (intermediate flow meter 37, 38) configured to be capable of measuring the flow rate of a fluid delivered by a second pump (intermediate pump 35, 36), and a third flow meter (lean flow meter 19) configured to be capable of measuring the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) delivered by the third pump (lean pump 18), The control device 22 controls the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the second pump (intermediate pumps 35, 36) and the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) by the third pump (lean pump 18) based on the measurement results of the fluid flow rate by the second flowmeter (intermediate flowmeters 37, 38) and the measurement results of the carbon dioxide absorbing solution (aqueous amine solution) by the third flowmeter (lean flowmeter 19) so that the flow rate of the fluid fed from the second carbon dioxide absorption tower (top stage absorption tower 11U, intermediate stage absorption tower 11M) to the other carbon dioxide absorption towers (intermediate stage absorption tower 11M, bottom stage absorption tower 11D) is greater than the flow rate of the carbon dioxide absorbing solution (aqueous amine solution) fed to the second carbon dioxide absorption tower (top stage absorption tower 11U, intermediate stage absorption tower 11M).

[0099] According to such control, the second carbon dioxide absorption tower (top-most stage absorption tower 11U, intermediate stage absorption tower 11M) is maintained in a state in which the amine aqueous solution does not accumulate therein. Therefore, the inflow of gas (target gas) into the second carbon dioxide absorption tower (top-most stage absorption tower 11U) through the intermediate gas path (intermediate gas supply path 33) is not hindered. Similarly, the inflow of gas (target gas) into the second carbon dioxide absorption tower (intermediate stage absorption tower 11M) through the intermediate gas path (intermediate gas supply path 34) is not hindered. Therefore, it is possible to prevent or suppress a decrease in the efficiency of the recovery device 10e. Furthermore, according to such a configuration, it is not necessary to provide a liquid level measuring device in the second carbon dioxide absorption tower (top-most stage absorption tower 11U, intermediate stage absorption tower 11M).

[0100] Although each embodiment of the present invention has been described above, the technical scope of the present invention is not limited to each of the above-mentioned embodiments. Various modifications of the present invention are possible without departing from the spirit of the present invention, and these modifications are also included in the technical scope of the present invention. In addition, although the carbon dioxide absorbing solution is an amine aqueous solution in each of the above-mentioned embodiments, this is not limited thereto, and other carbon dioxide absorbing solutions may be used.

[0101] For example, in each of the above embodiments, one-stage and three-stage absorption towers are shown, but the number of stages of the absorption tower is not limited. For example, it may be two-stage, four-stage, five-stage or more. In the case of a two-stage type, the recovery device includes an uppermost stage absorption tower 11U and a lowermost stage absorption tower 11D, but does not include an intermediate stage absorption tower 11M. In this case, the uppermost stage absorption tower 11U and the lowermost stage absorption tower 11D are directly connected. In the case of a four-stage or more type, the recovery device includes a plurality of intermediate stage absorption towers 11M connected in series with each other. [Explanation of symbols]

[0102] 10a, 10b, 10c, 10d, 10e...carbon dioxide recovery device, 11, 11U, 11M, 11D...carbon dioxide absorption tower, 12...carbon dioxide diffusion tower, 13...rich path, 14...lean path, 16, 16U, 16M, 16D...liquid level measuring device, 17...rich pump, 22...control device.

Claims

1. A carbon dioxide stripper configured so that the carbon dioxide absorbed in the carbon dioxide absorbing solution is stripped from the carbon dioxide absorbing solution; A first carbon dioxide absorption tower is configured to be connected to a gas path through which a gas containing carbon dioxide is supplied from the outside and a carbon dioxide absorbing solution path capable of supplying the carbon dioxide absorbing solution to the carbon dioxide stripper tower, and the carbon dioxide contained in the gas supplied through the gas path is absorbed in the carbon dioxide absorbing solution; a first pump configured to operate to supply the amine aqueous solution present inside the first carbon dioxide absorption tower to the carbon dioxide stripper tower through the carbon dioxide absorption solution path; A first liquid level measuring device capable of measuring a liquid level of the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower; a control device that controls a flow rate of the carbon dioxide absorbing solution by the first pump using a measurement result of the liquid level of the carbon dioxide absorbing solution so that the liquid level of the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower falls within a predetermined range; A carbon dioxide capture device comprising:

2. The carbon dioxide capture device according to claim 1, A first flow meter configured to measure a flow rate of the carbon dioxide absorbing solution sent from the first carbon dioxide absorption tower to the carbon dioxide stripper tower through the carbon dioxide absorbing solution path, The control device controls the flow rate of the carbon dioxide absorbing solution by the first pump using a measurement result of the liquid level of the carbon dioxide absorbing solution by the first liquid level measuring device and a measurement result of the flow rate of the carbon dioxide absorbing solution by the first flow meter so that the liquid level of the carbon dioxide absorbing solution present inside the first carbon dioxide absorption tower falls within a predetermined range. Carbon dioxide capture equipment.

3. The carbon dioxide capture device according to claim 1 or 2, a plurality of carbon dioxide absorption towers including one first carbon dioxide absorption tower and one or more second carbon dioxide absorption towers different from the one first carbon dioxide absorption tower, the carbon dioxide absorbing solution being connected in series to each other by an intermediate carbon dioxide absorbing solution path through which the carbon dioxide absorbing solution can flow and an intermediate gas path through which the gas can flow, and the first carbon dioxide absorption tower being located at the most downstream side of a flow of the carbon dioxide absorbing solution; a second pump configured to operate to deliver the carbon dioxide absorbing solution from the second carbon dioxide absorption tower to another carbon dioxide absorption tower connected to the second carbon dioxide absorption tower via the intermediate carbon dioxide absorbing solution pathway; a second liquid level measuring device capable of measuring a liquid level of the carbon dioxide absorbing solution present inside the second carbon dioxide absorption tower; Equipped with The control device controls the flow rate of the carbon dioxide absorbing solution by the second pump using a measurement result of the liquid level of the carbon dioxide absorbing solution by the second liquid level measuring device so that the liquid level of the carbon dioxide absorbing solution present inside the second carbon dioxide absorption tower is within a predetermined range. Carbon dioxide capture equipment.

4. The carbon dioxide capture device according to claim 3, A second flow meter configured to be able to measure the flow rate of the carbon dioxide absorbing solution fed by the second pump, The control device controls the flow rate of the carbon dioxide absorbing solution by the second pump using a measurement result of the liquid level of the carbon dioxide absorbing solution by the second liquid level measuring device and a measurement result of the flow rate of the carbon dioxide absorbing solution by the second flow meter so that the liquid level of the carbon dioxide absorbing solution present inside the second carbon dioxide absorption tower falls within a predetermined range. Carbon dioxide capture equipment.

5. The carbon dioxide capture device according to claim 1 or 2, a plurality of carbon dioxide absorption towers including one first carbon dioxide absorption tower and one or more second carbon dioxide absorption towers different from the one first carbon dioxide absorption tower, the carbon dioxide absorbing solution being connected in series to each other by an intermediate carbon dioxide absorbing solution path through which the carbon dioxide absorbing solution can flow and an intermediate gas path through which the gas can flow, and the first carbon dioxide absorption tower being located at the most downstream side of a flow of the carbon dioxide absorbing solution; a second pump configured to operate to supply fluid present inside the second carbon dioxide absorption tower to another carbon dioxide absorption tower connected to the second carbon dioxide absorption tower via the intermediate carbon dioxide absorbing solution path; a third pump configured to operate to supply the carbon dioxide absorbing solution present inside the carbon dioxide stripper tower to the single second carbon dioxide absorption tower or the second carbon dioxide absorption tower located most upstream in the flow of the carbon dioxide absorbing solution among the plurality of second carbon dioxide absorption towers; a second flowmeter configured to be able to measure the flow rate of the fluid delivered by the second pump, and a third flowmeter configured to be able to measure the flow rate of the carbon dioxide absorbing solution delivered by the third pump; Equipped with the control device controls the flow rate of the carbon dioxide absorbing solution by the second pump and the flow rate of the carbon dioxide absorbing solution by the third pump, based on a measurement result of the flow rate of the fluid by the second flowmeter and a measurement result of the flow rate of the carbon dioxide absorbing solution by the third flowmeter, so that a flow rate of the fluid fed from the second carbon dioxide absorption tower to another carbon dioxide absorption tower is greater than a flow rate of the carbon dioxide absorbing solution fed to the second carbon dioxide absorption tower. Carbon dioxide capture equipment.

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