Absorption tower configuration for carbon dioxide recovery system, and carbon dioxide absorption method

Abstract

To reduce the height of an absorption tower while maintaining recovery efficiency for carbon dioxide in a gas and recovery efficiency for an absorbent included in the gas after the carbon dioxide is recovered.SOLUTION: An absorption tower comprises a carbon dioxide absorption part which brings a gas to be processed including carbon dioxide into contact with an absorbent, and a washing part which brings the decarbonization, having been brought into contact with the absorbent at the carbon dioxide absorption part, into contact with washing water. The carbon dioxide absorption part has an absorption unit, and absorbs the carbon dioxide from the gas to be processed. The washing part has a recovery unit, and recovers an absorbent component made to accompany the decarbonization gas. The absorption unit and the recovery unit has, at least in part, a storage part which stores a liquid and a diffusion part which jets the gas in the liquid reserved in the storage part.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a configuration of an absorption tower of a carbon dioxide recovery system and a carbon dioxide absorption method.

Background Art

[0002] In recent years, from the perspective of carbon neutrality, attention has been focused on the concentration of carbon dioxide (CO 2 ) contained in the atmosphere. From the perspective of reducing the concentration of carbon dioxide in the atmosphere, a carbon dioxide recovery system for recovering carbon dioxide from exhaust gas is known. For example, in a carbon dioxide recovery system using a chemical absorption method, an absorption liquid is circulated between a regeneration tower and an absorption tower to recover carbon dioxide from exhaust gas.

[0003] For example, Patent Document 1 describes a decarburization process for removing carbon dioxide from combustion exhaust gas, which is a gas containing carbon dioxide, using an absorption liquid containing an amine compound. In this decarburization process, carbon dioxide in the combustion exhaust gas is removed by bringing the combustion exhaust gas into contact with the absorption liquid in an absorption tower. The absorption tower has a carbon dioxide absorption section and a water washing section. In the carbon dioxide absorption section, the absorption liquid and the combustion exhaust gas are brought into contact. As a result, carbon dioxide in the combustion exhaust gas is absorbed and removed by the absorption liquid. The loaded absorption liquid that has absorbed carbon dioxide is sent to a regeneration tower for regeneration and then returned to the absorption tower again. Further, the combustion exhaust gas (decarbonized exhaust gas) decarbonized in the carbon dioxide absorption section is sent to the water washing section. In the water washing section, washing water is discharged from a nozzle into the space through which the decarbonized exhaust gas flows for countercurrent contact to lower the temperature of the decarbonized exhaust gas. As a result, water vapor entrained in the decarbonized exhaust gas condenses and the amine compound, which is the absorption liquid entrained in the decarbonized exhaust gas, is recovered. In particular, the water washing section has a two-stage configuration of a single-stage water washing section and a two-stage water washing section, so that the amine compound entrained in the decarbonized exhaust gas can be efficiently recovered.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in a carbon dioxide recovery system such as the decarboxylation process described above, in the water washing section, washing water is supplied to the gas from above through nozzles. With such a configuration, the height of the absorption tower tends to be high. In particular, when the water washing section is multi-stage as in Patent Document 1, the height of the absorption tower causes complication of the assembly work at the installation location and difficulty in securing a work place. Therefore, a structure that can suppress the height of the absorption tower while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorption liquid component contained in the gas after recovering carbon dioxide is desired.

[0006] The present disclosure has been made to solve the above-mentioned demands, and an object thereof is to make it possible to suppress the height of the absorption tower while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorption liquid component contained in the gas after recovering carbon dioxide.

Means for Solving the Problems

[0007] In order to solve the above problems, the absorption tower according to the present disclosure brings a treatment target gas containing carbon dioxide into contact with an absorption liquid to absorb the carbon dioxide in the absorption liquid, and a carbon dioxide absorption section, and brings the decarboxylated gas after contacting the absorption liquid in the carbon dioxide absorption section into contact with washing water to recover the absorption liquid component entrained in the decarboxylated gas. The carbon dioxide absorption section has an absorption unit that absorbs the carbon dioxide from the treatment target gas in the absorption unit, and the water washing section has a recovery unit that recovers the absorption liquid component entrained in the decarboxylated gas in the recovery unit. At least a part of the absorption unit and the recovery unit has a storage section for storing a liquid and a diffuser section for ejecting a gas in the liquid stored in the storage section.

[0008] In addition, the carbon dioxide recovery system according to the present disclosure includes an absorption tower that brings a gas to be treated containing carbon dioxide into contact with an absorption liquid, and discharges the absorption liquid that has absorbed the carbon dioxide and a decarbonated gas from which the carbon dioxide has been removed; and a regeneration tower that releases the carbon dioxide from the absorption liquid discharged from the absorption tower, and discharges the absorption liquid from which the carbon dioxide has been released and a regeneration tower discharge gas containing the carbon dioxide.

[0009] In addition, the carbon dioxide absorption method according to the present disclosure includes a carbon dioxide absorption step of bringing a gas to be treated containing carbon dioxide into contact with an absorption liquid to absorb the carbon dioxide in the absorption liquid; and a water washing step of bringing the decarbonated gas after contacting the absorption liquid in the carbon dioxide absorption step into contact with washing water to recover the absorption liquid components entrained in the decarbonated gas. At least a part of the carbon dioxide absorption step and the water washing step includes a step of ejecting a gas so as to generate a froth flow in a stored liquid, a step of sending a part of the stored liquid downward in the vertical direction and extracting the gas contained in the liquid and sending it upward in the vertical direction, and a step of sending the gas that has escaped from the liquid upward in the vertical direction.

Advantages of the Invention

[0010] According to the present disclosure, it is possible to suppress the height of the absorption tower while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorption liquid contained in the gas after recovering carbon dioxide.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments for implementing an absorption tower and a carbon dioxide recovery system according to the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to only this embodiment.

[0013] <First Embodiment> (Carbon Dioxide Recovery System) The carbon dioxide recovery system 1 is capable of recovering carbon dioxide (CO 2 ) from the gas to be treated from an exhaust gas source (not shown). Examples of the exhaust gas source include boilers, incinerators, gas turbines, manufacturing plants for SAF (Sustainable Aviation Fuel) and ethanol, etc. That is, examples of the gas to be treated include exhaust gas containing carbon dioxide finally discharged, and process gas containing carbon dioxide used in the middle of various plants. As shown in FIG. 1, the gas to be treated supplied from the exhaust gas source is sent to the carbon dioxide recovery system 1.

[0014] The carbon dioxide recovery system 1 of the present embodiment includes an absorption tower 2, a gas-to-be-treated line 11, a regeneration tower 3, a rich line 13, a lean line 14, an absorption liquid heat exchanger 4, and a regeneration tower discharge line 15.

[0015] The absorption tower 2 is introduced with a gas to be treated containing carbon dioxide. The absorption tower 2 brings the gas to be treated into contact with the absorption liquid to remove carbon dioxide from the gas to be treated. Examples of the absorption liquid include amine-based solutions. Specifically, as this absorption liquid, for example, alkanolamines such as monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (MDEA), diisopropanolamine (DIPA), and diglycolamine (DGA) can be adopted. Also, hindered amines can be adopted. Further, each of these single aqueous solutions or a mixed aqueous solution of two or more of them can also be adopted. The absorption tower 2 separately discharges the absorption liquid that has absorbed carbon dioxide and the absorption tower exhaust gas containing the gas to be treated from which carbon dioxide has been removed. The detailed configuration of the absorption tower 2 will be described later.

[0016] The gas line 11 to be treated introduces the gas to be treated into the absorption tower 2. The gas line 11 to be treated cools the gas to be treated sent from the exhaust gas generation source with a cooling device (not shown) and then sends it to the absorption tower 2. The gas line 11 to be treated is connected to the absorption tower 2.

[0017] The absorption tower discharge line 12 is connected to the top of the absorption tower 2 and discharges the absorption tower exhaust gas discharged from the absorption tower 2 to the outside.

[0018] The regeneration tower 3 dissipates carbon dioxide from the absorption liquid discharged from the absorption tower 2. The regeneration tower 3 heats the absorption liquid with a reboiler 31. Thereby, in the regeneration tower 3, most of the carbon dioxide is dissipated together with the vapor from the absorption liquid to separate carbon dioxide from the absorption liquid. High-temperature steam is supplied to the reboiler 31. In the reboiler 31, the absorption liquid is heated by performing heat exchange between the steam and the absorption liquid. The regeneration tower 3 separately discharges the absorption liquid from which carbon dioxide has been dissipated and the regeneration tower exhaust gas mainly composed of carbon dioxide.

[0019] Rich line 13 supplies the absorption liquid that has absorbed carbon dioxide from absorption tower 2 to regeneration tower 3. Here, the absorption liquid discharged from absorption tower 2 and flowing through rich line 13 is referred to as rich liquid. The rich liquid is the absorption liquid with a high concentration of carbon dioxide after absorbing carbon dioxide in absorption tower 2. Rich line 13 connects the bottom of absorption tower 2 and the upper part of regeneration tower 3. A rich pump 35 is arranged on rich line 13. Rich pump 35 boosts the pressure of the rich liquid and sends it to regeneration tower 3 via absorption liquid heat exchanger 4.

[0020] Lean line 14 supplies the absorption liquid from which carbon dioxide has been dissipated from regeneration tower 3 to absorption tower 2. Here, the absorption liquid discharged from regeneration tower 3 and flowing through lean line 14 is referred to as lean liquid. The lean liquid is the absorption liquid with a low concentration of carbon dioxide after dissipating carbon dioxide in regeneration tower 3. That is, the concentration of carbon dioxide in the lean liquid is lower than that in the rich liquid. Lean line 14 connects the bottom of regeneration tower 3 and the upper part of absorption tower 2. A lean pump 37 is arranged on lean line 14. Lean pump 37 boosts the pressure of the lean liquid and sends it to absorption tower 2 via absorption liquid heat exchanger 4.

[0021] Absorption liquid heat exchanger 4 conducts heat exchange between the rich liquid flowing through rich line 13 and the lean liquid flowing through lean line 14. As a result, in absorption liquid heat exchanger 4, the absorption liquid flowing through rich line 13 and pressurized by rich pump 35 so as to flow from absorption tower 2 to regeneration tower 3 is heated. Also, in absorption liquid heat exchanger 4, the absorption liquid flowing through lean line 14 and pressurized by lean pump 37 so as to flow from regeneration tower 3 to absorption tower 2 is cooled.

[0022] The regeneration tower discharge line 15 discharges the regeneration tower exhaust gas discharged from the regeneration tower 3 to the outside (outside the system) of the carbon dioxide recovery system 1. The regeneration tower discharge line 15 is connected to the top of the regeneration tower 3. The regeneration tower discharge line 15 transfers the regeneration tower exhaust gas to an external transfer destination according to the purpose of use. The regeneration tower exhaust gas mainly composed of carbon dioxide discharged from the regeneration tower discharge line 15 is compressed, liquefied, etc. according to the purpose of use, and is used for storage in a tank, storage inside an oil field through a pipeline, or storage in an aquifer, etc.

[0023] (Absorption tower) As shown in FIG. 2, the absorption tower 2 of the first embodiment includes an absorption tower main body 40, a carbon dioxide absorption section 50, a water washing section 60, a liquid level adjustment section 70, and a demister 80.

[0024] The absorption tower main body 40 is a cylindrical container extending in the vertical direction Dv. Inside the absorption tower main body 40, the gas to be treated can flow from the lower part Dvd in the vertical direction Dv to the upper part Dvu. Near the bottom of the absorption tower main body 40, a gas line 11 to be treated is connected. Near the top of the absorption tower main body 40, an absorption tower discharge line 12 is connected. To the absorption tower main body 40, a rich line 13 is connected at a position below Dvd in the vertical direction Dv with respect to the connection position with the gas line 11 to be treated. To the absorption tower main body 40, a lean line 14 is connected at a position above Dvu in the vertical direction Dv with respect to the connection position with the gas line 11 to be treated and below Dvd in the vertical direction Dv with respect to the connection position with the absorption tower discharge line 12. To the absorption tower main body 40, a washing water supply line 69 is connected at a position above Dvu in the vertical direction Dv with respect to the connection position with the lean line 14 and below Dvd in the vertical direction Dv with respect to the connection position with the absorption tower discharge line 12.

[0025] The carbon dioxide absorption unit 50 brings the gas to be treated containing carbon dioxide into contact with the absorption liquid. As a result, the carbon dioxide absorption unit 50 causes the absorption liquid to absorb carbon dioxide. The carbon dioxide absorption unit 50 of the first embodiment sequentially absorbs carbon dioxide from the gas to be treated into the absorption liquid in multiple stages. The carbon dioxide absorption unit 50 of the present embodiment includes a lower storage unit 51 and a plurality of absorption units 52.

[0026] The lower storage unit 51 stores the absorption liquid. The absorption liquid with the highest carbon dioxide concentration in the carbon dioxide absorption unit 50 is stored in the lower storage unit 51. The lower storage unit 51 is disposed below the plurality of absorption units 52 in the vertical direction Dv (Dvd). The lower storage unit 51 is disposed near the bottom of the absorption tower main body 40. In the lower storage unit 51, the absorption liquid is stored such that the liquid level of the stored absorption liquid is located below the connection position between the absorption tower main body 40 and the gas line 11 to be treated in the vertical direction Dv (Dvd). In the lower storage unit 51, the absorption liquid is stored such that the connection position between the absorption tower main body 40 and the rich line 13 is disposed in the stored absorption liquid.

[0027] The plurality of absorption units 52 are arranged side by side in the vertical direction Dv. The plurality of absorption units 52 arranged in the vertical direction Dv sequentially absorb carbon dioxide from the gas to be treated. The number of absorption units 52 is preferably two or more and eight or less, and more preferably three or more and five or less.

[0028] The absorption unit 52 ejects the gas to be treated into the stored absorption liquid. That is, the absorption unit 52 generates bubbles (bubbling) by sending the gas to be treated into the absorption liquid, and brings the absorption liquid into contact with the gas to be treated. At this time, the absorption unit 52 sends the gas to be treated into the absorption liquid so as to form a froth flow.

[0029] Here, there are multiple flow states in the gas-liquid two-phase flow where gas is flowing in the liquid. Specifically, when the gas flow rate is low relative to the liquid flow rate, the gas disperses and flows in the liquid as small bubbles. As a result, the gas-liquid two-phase flow is in a bubble flow state without agitation. The bubble flow state indicates that when the gas flow rate is low compared to the liquid flow rate, the gas disperses and flows in the liquid as small bubbles. That is, in the bubble flow state, the liquid level of the stored liquid is in a state where it is hardly disturbed. On the other hand, as the gas flow rate relative to the liquid flow rate increases from the bubble flow state, the bubbles in the liquid gradually grow and violently disrupt the flow. After that, when the gas flow rate is more than a certain level relative to the liquid flow rate, the gas violently agitates the liquid. As a result, the gas-liquid two-phase flow is in a froth flow state with intense agitation. That is, in the froth flow state, the gas-liquid interface is violently disturbed and the gas and liquid are mixed, promoting the transfer of carbon dioxide from the gas to the absorption liquid.

[0030] Also, the liquid level of the liquid stored in the storage section (absorption liquid storage section 55 and washing water storage section 65) described later is the liquid level before the gas is ejected from the air diffuser section (gas to be treated air diffuser section 57 and decarbonated gas air diffuser section 67) described later. That is, it is the liquid level when the absorption tower 2 is stopped. In this state, the stored liquid is hardly rippling, and the position of the liquid level in the vertical direction Dv is maintained at a predetermined position.

[0031] As shown in FIG. 3, the absorption unit 52 of the present embodiment has an absorption liquid storage section (storage section) 55 and a gas to be treated air diffuser section (air diffuser section) 57.

[0032] The absorption liquid storage section 55 stores a liquid with a predetermined depth and flow rate. The absorption liquid storage section 55 forms a space capable of storing the liquid by a flat bottom plate section 551 and the side wall of the absorption tower main body 40. The absorption liquid storage section 55 of the present embodiment stores the absorption liquid as the liquid.

[0033] The gas diffuser 57 for the gas to be treated jets the gas into the absorption liquid stored in the absorption liquid storage section 55. The gas diffuser 57 for the gas to be treated in the present embodiment jets the gas to be treated as the gas. The gas diffuser 57 for the gas to be treated jets the gas to be treated in the absorption liquid in a direction including a component directed downward Dvd in the vertical direction Dv or in the horizontal direction. The gas diffuser 57 for the gas to be treated in the present embodiment jets the gas to be treated directly downward in the vertical direction Dv. Note that the direction including a component directed downward Dvd in the vertical direction Dv is a direction other than the horizontal direction orthogonal to the vertical direction Dv and the direction directed upward Dvu in the vertical direction Dv with respect to the horizontal position. Therefore, the direction including a component directed downward Dvd in the vertical direction Dv also includes the direction directed directly downward in the vertical direction Dv and the direction directed obliquely downward Dvd in the vertical direction Dv. The gas diffuser 57 jets the gas to be treated so that the flow rate ratio, which is the ratio of the liquid volume of the stored liquid to the flow rate of the gas to be treated to be jetted, is 1 to 5 L / Nm 3 The gas diffuser 57 for the gas to be treated jets the gas to be treated so that the flow rate ratio becomes as described above. As shown in FIG. 4, a plurality (four in the present embodiment) of the gas diffusers 57 for the gas to be treated are arranged at positions separated from each other.

[0034] As shown in FIG. 2, the carbon dioxide absorption section 50 of the present embodiment has, as a plurality of absorption units 52, a first absorption unit 521, a second absorption unit 522, and a third absorption unit 523. The first absorption unit 521, the second absorption unit 522, and the third absorption unit 523 have the same structure. The first absorption unit 521 is arranged at the lowest position in the vertical direction Dv among the three absorption units 52. The third absorption unit 523 is arranged at the highest position in the vertical direction Dv among the three absorption units 52.

[0035] The first absorption unit 521 is disposed above the lower storage unit 51 in the vertical direction Dv, i.e., in the upward direction Dvu. That is, in the first absorption unit 521, the gas to be treated in which carbon dioxide has not yet been absorbed is ejected as a gas from the gas to be treated diffuser 57. Further, in the first absorption unit 521, the absorption liquid storage unit 55 stores an absorption liquid having the highest carbon dioxide concentration among the plurality of absorption units 52 and having a lower carbon dioxide concentration than the absorption liquid stored in the lower storage unit 51.

[0036] The second absorption unit 522 is disposed above the first absorption unit 521 in the vertical direction Dv, i.e., in the upward direction Dvu. That is, in the second absorption unit 522, the gas to be treated in which carbon dioxide has been absorbed by the absorption liquid in the first absorption unit 521 is ejected as a gas from the gas to be treated diffuser 57. Further, in the second absorption unit 522, the absorption liquid storage unit 55 stores an absorption liquid having a lower carbon dioxide concentration than the absorption liquid stored in the first absorption unit 521.

[0037] The third absorption unit 523 is disposed above the second absorption unit 522 in the vertical direction Dv, i.e., in the upward direction Dvu. That is, in the third absorption unit 523, the gas to be treated in which carbon dioxide has been absorbed by the absorption liquid in the second absorption unit 522 is ejected as a gas from the gas to be treated diffuser 57. Further, in the third absorption unit 523, the absorption liquid storage unit 55 stores an absorption liquid having a lower carbon dioxide concentration than the absorption liquid stored in the second absorption unit 522. In the third absorption unit 523, the absorption liquid is stored such that the connection position between the absorption tower main body 40 and the lean line 14 is disposed in the stored absorption liquid.

[0038] The water washing section 60 brings the gas to be treated, which has contacted the absorption liquid in the carbon dioxide absorption section 50, into contact with washing water. Thereby, the water washing section 60 recovers the absorption liquid components entrained in the gas to be treated. Here, the gas to be treated after contacting the absorption liquid in the carbon dioxide absorption section 50 is referred to as decarbonated gas. The decarbonated gas is the gas to be treated after passing through the carbon dioxide absorption section 50, from which carbon dioxide has been removed. The decarbonated gas contains almost no carbon dioxide, but instead contains a vapor of the components of the absorption liquid and a large amount of entrained mist. The water washing section 60 of the first embodiment brings the decarbonated gas into contact with the washing water in two stages, and sequentially recovers the absorption liquid from the decarbonated gas. The water washing section 60 of the present embodiment has a plurality of recovery units 61. Here, the washing water refers to the steam condensate generated in the regeneration tower and the condensate generated due to cooling in the water washing section, in which the components of the absorption liquid are dissolved.

[0039] The plurality of recovery units 61 are arranged above the plurality of absorption units 52 in the vertical direction Dv (Dvu). Also, the plurality of recovery units 61 are arranged side by side in the vertical direction Dv. The absorption liquid is sequentially recovered from the decarbonated gas by the plurality of recovery units 61 arranged side by side in the vertical direction Dv. The number of the recovery units 61 is preferably one or more and five or less, and more preferably two or more and three or less.

[0040] The recovery unit 61 ejects the decarbonated gas into the stored washing water. That is, the recovery unit 61 generates bubbles (bubbling) by sending the decarbonated gas into the washing water, and brings the washing water into contact with the decarbonated gas. At that time, the recovery unit 61 sends the decarbonated gas into the washing water so as to form a froth flow.

[0041] The recovery unit 61 of the present embodiment has the same structure as the absorption unit 52. As shown in FIG. 3, the recovery unit 61 has a washing water storage section (storage section) 65 and a decarburized gas diffusing section (diffusing section) 67. That is, the washing water storage section 65 has the same structure as the absorption liquid storage section 55. The washing water storage section 65 of the present embodiment stores washing water instead of the absorption liquid as a liquid. In the following, the absorption liquid storage section 55 and the washing water storage section 65 may be collectively referred to as the storage section. Further, the decarburized gas diffusing section 67 has the same structure as the gas to be treated diffusing section 57. The decarburized gas diffusing section 67 of the present embodiment ejects decarburized gas instead of the gas to be treated as a gas. In the following, the gas to be treated diffusing section 57 and the decarburized gas diffusing section 67 may be collectively referred to as the diffusing section.

[0042] Specifically, the gas to be treated diffusing section 57 and the decarburized gas diffusing section 67 of the present embodiment are box-shaped and have a discharge hole 571, a direction changing section 572, and a jet hole 573.

[0043] The discharge hole 571 discharges gas upward Dvu in the vertical direction Dv. The discharge hole 571 is formed so as to penetrate the bottom plate portion 551 in the vertical direction Dv. The discharge hole 571 projects upward Dvu in the vertical direction Dv so as to form a cylindrical shape from the bottom plate portion 551. The discharge hole 571 opens at a position higher than the liquid level of the liquid stored in the storage section. Thereby, the discharge hole 571 supplies the gas existing in the space below Dvd in the vertical direction Dv with respect to one absorption unit 52 (or recovery unit 61) to a position above Dvu in the vertical direction Dv with respect to the liquid level of the liquid stored in the storage section.

[0044] The direction changing part 572 covers the discharge hole 571 from above in the vertical direction Dv (Dvu) and directs the gas flow direction downward in the vertical direction Dv (Dvd). The direction changing part 572 ejects gas within the liquid. The direction changing part 572 curves the flow direction of the gas discharged from the discharge hole 571 so as to go from above (Dvu) to below (Dvd) in the vertical direction Dv. The direction changing part 572 of the present embodiment is formed in a box shape with an opening at the lower part (Dvd) in the vertical direction Dv so as to cover the opening of the discharge hole 571 from above (Dvu) in the vertical direction Dv. More specifically, the direction changing part 572 has a collision plate 581 and a flow path forming plate 582.

[0045] The collision plate 581 is configured such that the gas discharged from the discharge hole 571 and directed upward in the vertical direction Dv (Dvu) can collide therewith. The collision plate 581 is disposed above the opening of the discharge hole 571 in the vertical direction Dv. The collision plate 581 is formed in a flat plate shape that spreads horizontally at a position facing the opening of the discharge hole 571.

[0046] The flow path forming plate 582 forms a flow path for guiding the gas collided by the collision plate 581 to the ejection hole 573. The flow path forming plate 582 extends in a plate shape from the end of the collision plate 581 downward in the vertical direction Dv (Dvd). The flow path forming part forms a flow path extending in the vertical direction Dv between the outer surface of the discharge hole 571.

[0047] The ejection hole 573 is connected to the lower end in the vertical direction Dv of the flow path forming part. The ejection hole 573 ejects the gas that has flowed through the flow path formed by the flow path forming plate 582 downward in the vertical direction Dv into the liquid. The ejection hole 573 opens downward in the vertical direction Dv. The ejection hole 573 is, for example, a perforated plate in which a plurality of openings are formed.

[0048] Also, as shown in FIG. 2, the water washing part 60 of the present embodiment has, as a plurality of recovery units 61, a first recovery unit 611 and a second recovery unit 612. The first recovery unit 611 and the second recovery unit 612 have the same structure.

[0049] The first recovery unit 611 is disposed above the carbon dioxide absorption unit 50 in the vertical direction Dv, i.e., above Dvu. That is, in the first recovery unit 611, the decarbonated gas, which is the gas to be treated in which carbon dioxide has been absorbed by the absorption liquid in the third absorption unit 523, is ejected as a gas from the decarbonated gas diffuser 67. At this time, the decarbonated gas from the third absorption unit 523 is supplied to the first recovery unit 611 after passing through a demister 80 described later. Also, in the first recovery unit 611, the washing water storage unit 65 stores washing water that has the highest concentration of the components of the absorption liquid among the plurality of recovery units 61 and has a significantly lower concentration of the components of the absorption liquid than the absorption liquid stored in the third absorption unit 523.

[0050] The second recovery unit 612 is disposed above the first recovery unit 611 in the vertical direction Dv, i.e., above Dvu. That is, in the second recovery unit 612, the decarbonated gas in which the components of the absorption liquid have been recovered by the washing water in the first recovery unit 611 is ejected from the decarbonated gas diffuser 67. In the second recovery unit 612, for example, washing water is supplied from a washing water supply line 69 connected to the regeneration tower 3. Also, in the second recovery unit 612, the washing water storage unit 65 stores washing water that has a lower concentration of the components of the absorption liquid than the washing water stored in the first recovery unit 611. In the second recovery unit 612, the washing liquid is stored such that the connection position between the absorption tower main body 40 and the washing water supply line 69 is disposed within the stored washing water.

[0051] The liquid level adjustment unit 70 adjusts to maintain the position of the liquid level of the liquid stored in the absorption unit 52 or the recovery unit 61 at a constant position. The liquid level adjustment unit 70 separates the gas supplied from the ejection holes 573 contained in the liquid stored in the absorption unit 52 or the recovery unit 61. The gas is supplied from the upper part of the gas-liquid separation line 71 to the gas phase part of the absorption unit 52 or the recovery unit 61, and the liquid is supplied from the overflow line 72 to merge with the liquid stored in another absorption unit 52 or recovery unit 61 located below Dvd in the vertical direction Dv. The liquid level adjustment unit 70 of the present embodiment includes a gas-liquid separation line 71 and an overflow line 72.

[0052] The gas-liquid separation line 71 is a pipe connecting the liquid phase part stored in the storage part and the space above Dvu in the vertical direction Dv with respect to the liquid in the storage part. During the operation of the device, the gas-liquid separation line 71 is connected to the space above Dvu in the vertical direction Dv with respect to the liquid level in a state where gas coexists in the liquid as gas is ejected from the gas diffusing part. The gas-liquid separation line 71 supplies only the gas in the liquid and gas flowing inside to the space above Dvu in the vertical direction Dv with respect to the liquid level.

[0053] The overflow line 72 allows the liquid after separating the gas in the gas-liquid separation line 71 to flow downward in the vertical direction Dv. The overflow line 72 is connected to the gas-liquid separation line 71 at the same position as the liquid level of the liquid in the storage part when the device is stopped, in the vertical direction Dv. The connection position of the overflow line 72 and the gas-liquid separation line 71 is set lower than the opening position of the discharge hole 571 in the vertical direction Dv. The connection position of the overflow line 72 and the gas-liquid separation line 71 is set higher than the gas ejection position by the ejection holes 573 in the vertical direction Dv. Further, the overflow line 72 is connected to the storage part of another absorption unit 52 or recovery unit 61 located below Dvd in the vertical direction Dv with respect to the storage part to which the gas-liquid separation line 71 is connected.

[0054] The absorption tower 2 of this embodiment has a plurality of liquid level adjustment parts 70. Specifically, as the plurality of liquid level adjustment parts 70, the absorption tower 2 has a first absorption liquid adjustment part 74, a second absorption liquid adjustment part 75, a third absorption liquid adjustment part 76, a first washing water adjustment part 78, and a second washing water adjustment part 79.

[0055] The first absorption liquid adjustment part 74 separates the gas to be treated mixed in the absorption liquid stored in the first absorption unit 521. The first absorption liquid adjustment part 74 supplies the separated gas to be treated to the space above Dvu in the vertical direction Dv with respect to the absorption liquid storage part 55 of the first absorption unit 521. That is, the first absorption liquid adjustment part 74 supplies the separated gas to be treated to the space between the absorption liquid storage part 55 of the first absorption unit 521 and the absorption liquid storage part 55 of the second absorption unit 522 in the vertical direction Dv. The first absorption liquid adjustment part 74 supplies the separated absorption liquid so as to merge with the absorption liquid stored in the lower storage part 51.

[0056] The second absorption liquid adjustment part 75 separates the gas to be treated mixed in the absorption liquid stored in the second absorption unit 522. The second absorption liquid adjustment part 75 supplies the separated gas to be treated to the space above Dvu in the vertical direction Dv with respect to the absorption liquid storage part 55 of the second absorption unit 522. That is, the second absorption liquid adjustment part 75 supplies the separated gas to be treated to the space between the absorption liquid storage part 55 of the second absorption unit 522 and the absorption liquid storage part 55 of the third absorption unit 523 in the vertical direction Dv. The second absorption liquid adjustment part 75 supplies the separated absorption liquid so as to merge with the absorption liquid stored in the absorption liquid storage part 55 of the first absorption unit 521.

[0057] The third absorption liquid adjustment unit 76 separates the gas to be treated mixed in the absorption liquid stored in the third absorption unit 523. The third absorption liquid adjustment unit 76 supplies the separated gas to be treated to the space above Dvu in the vertical direction Dv with respect to the absorption liquid storage unit 55 of the third absorption unit 523. That is, the third absorption liquid adjustment unit 76 supplies the separated gas to be treated to the space between the absorption liquid storage unit 55 of the third absorption unit 523 and the first demister 81 in the vertical direction Dv. The third absorption liquid adjustment unit 76 supplies the separated absorption liquid so as to merge with the absorption liquid stored in the absorption liquid storage unit 55 of the second absorption unit 522.

[0058] The first washing water adjustment unit 78 separates the decarburized gas mixed in the washing water stored in the first recovery unit 611. The first washing water adjustment unit 78 supplies the separated decarburized gas to the space above Dvu in the vertical direction Dv with respect to the washing water storage unit 65 of the first recovery unit 611. That is, the first washing water adjustment unit 78 supplies the separated decarburized gas to the space between the washing water storage unit 65 of the first recovery unit 611 and the washing water storage unit 65 of the second recovery unit 612 in the vertical direction Dv. The first washing water adjustment unit 78 supplies the separated washing water so as to merge with the absorption liquid stored in the absorption liquid storage unit 55 of the third absorption unit 523.

[0059] The second washing water adjustment unit 79 separates the decarburized gas mixed in the washing water stored in the second recovery unit 612. The second washing water adjustment unit 79 supplies the separated decarburized gas to the space between the washing water storage unit 65 of the second recovery unit 612 and the second demister 82 in the vertical direction Dv. The second washing water adjustment unit 79 supplies the separated washing water so as to merge with the washing water stored in the washing water storage unit 65 of the first recovery unit 611.

[0060] The demister 80 is installed to remove the mist (fine droplets) contained in the gas by the gas flowing through. In the demister 80, the gas flows from the lower part Dvd to the upper part Dvu in the vertical direction Dv. The demister 80 is formed, for example, by stacking several layers of nets woven with thin wires. A plurality of demisters 80 are arranged inside the absorption tower main body 40. In the present embodiment, a first demister 81 and a second demister 82 are arranged.

[0061] The first demister 81 is installed inside the absorption tower main body 40 to remove the mist in the gas to be treated after contacting the absorption liquid. The first demister 81 is arranged between the carbon dioxide absorption section 50 and the water washing section 60. Specifically, the first demister 81 is arranged between the third absorption unit 523 and the first recovery unit 611 in the vertical direction Dv. The first demister 81 is arranged above Dvu in the vertical direction Dv with respect to the connection position between the gas-liquid separation line 71 of the third absorption unit 523 and the absorption tower main body 40.

[0062] The second demister 82 is installed inside the absorption tower main body 40 to remove the mist in the decarbonated gas after contacting the washing water. The second demister 82 is arranged between the water washing section 60 and the absorption tower discharge line 12. Specifically, the second demister 82 is arranged between the second recovery unit 612 and the top surface of the absorption tower 2 in the vertical direction Dv. The second demister 82 is arranged above Dvu in the vertical direction Dv with respect to the connection position between the gas-liquid separation line 71 of the second recovery unit 612 and the absorption tower main body 40. The second demister 82 is arranged below Dvd in the vertical direction Dv with respect to the connection position between the absorption tower discharge line 12 and the absorption tower main body 40.

[0063] The cooling unit 90 cools the liquid inside the absorption tower main body 40. At least one cooling unit 90 is arranged for one absorption tower main body 40. In this embodiment, only one cooling unit 90 is arranged. Since the liquid and gas heat up due to the carbon dioxide absorption reaction in the carbon dioxide absorption unit 50, and the amount of water vapor and the amount of absorption liquid components vapor in the decarbonated gas discharged from the absorption tower discharge line 12 increase, the cooling unit 90 is installed for the purpose of suppressing this. By cooling the liquid, it becomes possible to lower the temperature of the liquid and gas. The cooling unit 90 cools the washing water flowing through the cooling water extraction line 94 and supplies it to the space Dvu above the washing water storage section 65 of the second recovery unit 612. Specifically, the cooling unit 90 has a cooling line 91, a cooling pump 92, a washing water cooler 93, and a cooling extraction line 94.

[0064] The cooling pump 92 is installed between the cooling water extraction line 94 and the cooling line 91 and pumps the flowing washing water. The washing water cooler 93 is arranged in the middle of the cooling line 91 and cools the washing water pumped by the cooling pump 92. Specifically, the washing water cooler 93 cools the washing water by exchanging heat between the cooling water supplied from the outside and the washing water flowing through the cooling line 91.

[0065] Also, as conditions for operating the absorption tower 2 as described above, the superficial gas velocity Ug when ejecting gas in the gas dispersion section 57 of the gas to be treated and the decarbonated gas dispersion section 67 is preferably in the range of 0.5 m / s to 2.5 m / s. Also, the gas flow ratio L / G in the liquid when ejecting gas in the gas dispersion section 57 of the gas to be treated and the decarbonated gas dispersion section 67 is 3 ~5.0 L / Nm 3 is preferably in the range. Also, when the ejection hole 573 is a perforated plate, its aperture ratio is preferably between 25% and 70%. At that time, the size of the ejection hole 573 is preferably in the range of 1 to 10 mm.

[0066] Here, as shown in FIG. 3, the height at which the ejection hole 573 is disposed with respect to the bottom plate portion 551 in the vertical direction Dv, that is, the height of the position where the gas is ejected is referred to as the ejection height H1. Further, the height of the connection position between the overflow line 72 and the gas-liquid separation line 71 with respect to the bottom plate portion 551 in the vertical direction Dv is referred to as the overflow height H2. Further, the height of the opening position of the discharge hole 571 with respect to the bottom plate portion 551 in the vertical direction Dv is referred to as the gas return height H3. Further, the height of the liquid level of the stored liquid with respect to the bottom plate portion 551 in the vertical direction Dv during the stoppage of the apparatus is referred to as the liquid level height H4. Further, the height of the highest liquid level in the wavy state after the gas is ejected from the gas diffusing portion with respect to the bottom plate portion 551 in the vertical direction Dv during the operation of the apparatus is referred to as the highest liquid level height H5.

[0067] The overflow height H2 is equal to the liquid level height H4. Further, the ejection height H1 is preferably lower than the overflow height H2. The gas return height H3 is preferably higher than the overflow height H2. The gas return height H3 is preferably lower than the highest liquid level height H5. Further, the height in the vertical direction Dv of the absorption unit 52 and the recovery unit 61 is referred to as the stage height H. The stage height H is higher than the highest liquid level height H5.

[0068] In the carbon dioxide recovery system 1 configured as described above, as shown in FIG. 1, the gas to be treated flowing through the gas line 11 to be treated is sent to the absorption tower 2. The gas to be treated supplied to the absorption tower 2 contacts the absorption liquid in the absorption tower 2, whereby carbon dioxide is removed. As a result, the absorption tower exhaust gas from which carbon dioxide has been removed is discharged from the absorption tower 2 to the outside through the absorption tower exhaust line 12. Further, in the absorption tower 2, a rich liquid which is an absorption liquid that has absorbed carbon dioxide is generated. The rich liquid is pressurized by a rich pump 35 through a rich line 13 and sent to the absorption liquid heat exchanger 4. The rich liquid is heated in the absorption liquid heat exchanger 4 and further flows through the rich line 13 and is sent to the regeneration tower 3. In the regeneration tower 3, by heating the rich liquid with a reboiler 31, carbon dioxide is dissipated from the rich liquid. As a result, in the regeneration tower 3, a lean liquid which is an absorption liquid from which carbon dioxide has been dissipated is generated. The lean liquid is pressurized by a lean pump 37 through a lean line 14 and sent to the absorption liquid heat exchanger 4. The lean liquid is cooled by exchanging heat with the rich liquid in the absorption liquid heat exchanger 4. The cooled lean liquid is returned to the absorption tower 2. Thus, the absorption liquid circulates between the absorption tower 2 and the regeneration tower 3. Further, in the regeneration tower 3, a regeneration tower exhaust gas mainly composed of carbon dioxide generated by dissipating carbon dioxide from the rich liquid is generated and sent to the regeneration tower exhaust line 15.

[0069] Also, as shown in FIG. 2, in the absorption tower 2, the gas to be treated supplied from the gas line 11 to be treated is first supplied to above Dvu of the lower storage section 51. In the lower storage section 51, an absorption liquid (rich liquid) that has absorbed carbon dioxide in a plurality of absorption units 52 is stored and sent to the rich line 13. Further, the supplied gas to be treated moves upward to Dvu in the vertical direction Dv and is sent to the plurality of absorption units 52.

[0070] Specifically, the gas to be processed is sent to the first absorption unit 521. In the first absorption unit 521, the gas to be processed is ejected from the gas diffuser 57 of the gas to be processed so as to generate a froth flow in the absorption liquid stored in the absorption liquid storage unit 55. More specifically, as shown in FIG. 3, the gas to be processed directed upward Dvu in the vertical direction Dv from the lower storage unit 51 passes through the discharge hole 571 upward Dvu in the vertical direction Dv. The gas to be processed that has passed through the discharge hole 571 collides with the collision plate 581, and the flow direction is changed so as to flow downward Dvd in the vertical direction Dv. The gas to be processed flowing downward Dvd in the vertical direction Dv reaches the ejection hole 573 through the flow path formed by the flow path forming plate 582. Thereafter, the gas to be processed is ejected into the absorption liquid from a plurality of ejection holes 573 so as to flow downward Dvd in the vertical direction Dv. The gas to be processed ejected into the absorption liquid causes the absorption liquid to flow upward Dvu in the vertical direction Dv so as to form a froth flow. As a result, the gas to be processed and the absorption liquid come into intense contact with each other, and a part of the carbon dioxide contained in the gas to be processed is absorbed by the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the lower storage unit 51 via the first absorption liquid adjustment unit 74. Further, the gas to be processed that has escaped from the stored absorption liquid moves upward Dvu in the vertical direction Dv through the space above Dvu of the absorption liquid and is sent to the second absorption unit 522.

[0071] Also in the second absorption unit 522, the gas to be processed flows in the same manner as in the first absorption unit 521. As a result, also in the second absorption unit 522, the gas to be processed and the absorption liquid come into contact with each other, and a part of the carbon dioxide contained in the gas to be processed is absorbed by the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the absorption liquid storage unit 55 of the first absorption unit 521 via the second absorption liquid adjustment unit 75. Further, the gas to be processed that has escaped from the absorption liquid moves upward Dvu in the vertical direction Dv through the space above Dvu of the absorption liquid and is sent to the third absorption unit 523.

[0072] In the third absorption unit 523 as well, the gas to be treated flows through in the same manner as in the first absorption unit 521. At this time, in the absorption liquid storage section 55 of the third absorption unit 523, the lean liquid supplied through the lean line 14 merges with the stored absorption liquid. Then, also in the third absorption unit 523, the gas to be treated comes into contact with the absorption liquid, and a part of the carbon dioxide contained in the gas to be treated is absorbed by the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the absorption liquid storage section 55 of the second absorption unit 522 via the third absorption liquid adjustment section 76. Further, the gas to be treated that has escaped from the stored absorption liquid moves upward in the vertical direction Dv in the space Dvu above the absorption liquid and is sent to the first demister 81.

[0073] Thus, in the carbon dioxide absorption section 50 of the present embodiment, carbon dioxide in the gas to be treated is absorbed by the absorption liquid in three stages of the first absorption unit 521, the second absorption unit 522, and the third absorption unit 523. As a result, most of the carbon dioxide contained in the gas to be treated is removed and becomes decarbonated gas. The decarbonated gas flows upward in the vertical direction Dv and passes through the first demister 81, thereby removing the mist contained in the decarbonated gas. The decarbonated gas from which the mist has been removed is sent to the water washing section 60.

[0074] Specifically, the decarbonated gas is sent to the first recovery unit 611. In the first recovery unit 611, the decarbonated gas flows through in the same manner as the gas to be treated flowing through the first absorption unit 521. Thereby, in the first recovery unit 611, the decarbonated gas comes into contact with the washing water. The washing water that has recovered the absorption liquid component from the decarbonated gas is sent to the absorption liquid storage section 55 of the third absorption unit 523 via the first washing water adjustment section 78. Further, the decarbonated gas that has escaped from the washing water moves upward in the vertical direction Dv in the space Dvu above the washing water and is sent to the second recovery unit 612.

[0075] In the second recovery unit 612 as well, decarburized gas flows in the same manner as in the first recovery unit 611. At this time, in the washing water storage section 65 of the second recovery unit 612, new washing water is supplied via the washing water supply line 69 and merges with the stored washing water. Then, in the second recovery unit 612 as well, the decarburized gas comes into contact with the washing water. The washing water from which the absorbent component has been recovered from the decarburized gas is sent to the washing water storage section 65 of the first recovery unit 611 via the second washing water adjustment section 79. Further, a part of the washing water sent to the first recovery unit 611 is cooled via the cooling section 90 and returned to the washing water storage section 65 of the second recovery unit 612. Also, the decarburized gas that has escaped from the stored washing water moves upward in the vertical direction Dv toward the upper space Dvu above the washing water and is sent to the second demister 82.

[0076] In this way, in the water washing section 60 of the present embodiment, the absorbent components entrained in the decarburized gas are recovered in two stages in the first recovery unit 611 and the second recovery unit 612. As a result, most of the vapor and mist of the entrained absorbent are almost removed from the decarburized gas, and it becomes the absorption tower exhaust gas. The absorption tower exhaust gas flows upward in the vertical direction Dv and passes through the second demister 82, whereby the mist contained in the absorption tower exhaust gas is further removed. The absorption tower exhaust gas from which the mist has been removed is discharged to the outside of the absorption tower main body 40 through the absorption tower discharge line 12.

[0077] (Function and Effect) In such an absorption tower 2, the gas to be treated is jetted into the absorption liquid stored in the absorption unit 52. Therefore, the stored absorption liquid and the gas to be treated can be efficiently brought into contact with each other. As a result, the absorption reaction of carbon dioxide by the absorption liquid is promoted. In particular, in the present embodiment, the gas to be treated is jetted into the absorption liquid so as to form a froth flow. The generation of a froth flow in the absorption liquid causes the absorption liquid to be vigorously agitated by the gas to be treated. Therefore, the absorption liquid and the gas to be treated come into contact with each other more efficiently, and the absorption reaction of carbon dioxide by the absorption liquid is further promoted. Thereby, in the absorption unit 52, even if this height is suppressed, the recovery efficiency of carbon dioxide from the gas to be treated can be improved.

[0078] Furthermore, the decarbonated gas, which is the gas to be treated after passing through the carbon dioxide absorption section 50, is jetted into the washing water stored in the recovery unit 61. Therefore, the stored washing water and the decarbonated gas can be efficiently brought into contact with each other. As a result, the recovery of the absorption liquid components by the washing water is promoted. In particular, in the present embodiment, the decarbonated gas is jetted into the washing water so as to form a froth flow. The generation of a froth flow in the washing water causes the washing water to be vigorously agitated by the decarbonated gas. Therefore, the washing water and the decarbonated gas come into contact with each other more efficiently, and the recovery of the absorption liquid components by the washing water is further promoted. Thereby, in the recovery unit 61, even if this height is suppressed, the recovery efficiency of the absorption liquid components from the decarbonated gas can be improved.

[0079] As a result, it is possible to suppress the height of the absorption tower 2 while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorption liquid components contained in the decarbonated gas after carbon dioxide is recovered, at the same level as that of a conventional-height absorption tower.

[0080] In addition, in the present embodiment, the carbon dioxide absorption unit 50 has a plurality of absorption units 52 arranged in the vertical direction Dv. In this way, by arranging a plurality of absorption units 52 with high carbon dioxide absorption efficiency, the height of the entire carbon dioxide absorption unit 50 can be suppressed while improving the recovery efficiency of carbon dioxide from the gas to be treated as compared with the case of being configured by other devices. Similarly, the water washing unit 60 has a plurality of recovery units 61 arranged in the vertical direction Dv. In this way, by arranging a plurality of recovery units 61 with high recovery efficiency of the absorption liquid components, the height of the water washing unit 60 can be suppressed while improving the recovery efficiency of the absorption liquid components from the decarbonated gas as compared with the case of being configured by other devices. Further, the plurality of recovery units 61 are stacked above the plurality of absorption units 52 in the vertical direction Dvu within the absorption tower main body 40. Even if a plurality of absorption units 52 and a plurality of recovery units 61 are arranged in one absorption tower main body 40 in this way, the height of the entire absorption tower 2 can be suppressed while improving the recovery efficiency of carbon dioxide from the gas to be treated and the recovery efficiency of the absorption liquid components contained in the decarbonated gas.

[0081] In addition, the gas diffusing section 57 for the gas to be treated ejects the gas to be treated downward in the vertical direction Dv within the absorption liquid. Similarly, the decarbonated gas diffusing section 67 ejects the decarbonated gas downward in the extension direction within the washing water. By ejecting the gas downward in the vertical direction Dv in the liquid in this way, the contact time between the liquid and the gas can be increased as compared with the case of ejecting the gas upward in the vertical direction Dv. That is, the contact time between the ejected gas and the liquid increases without increasing the position of the liquid level of the stored liquid. Thereby, the recovery efficiency of carbon dioxide from the gas to be treated and the recovery efficiency of the absorption liquid components contained in the decarbonated gas can be further improved. Therefore, the height of the absorption tower 2 can be further suppressed.

[0082] Further, the treatment target gas diffuser 57 and the decarboxylated gas diffuser 67 have a discharge hole 571, a direction changing part 572, and a jet hole 573. The treatment target gas and the decarboxylated gas are discharged upward Dvu in the vertical direction Dv through the discharge hole 571. Therefore, when the absorption unit 52 and the recovery unit 61 are stacked in the vertical direction Dv, the treatment target gas and the decarboxylated gas can be easily supplied from the absorption unit 52 and the recovery unit 61 located below Dvd in the vertical direction Dv to another absorption unit 52 and recovery unit 61 located above Dvu in the vertical direction Dv through the discharge hole 571. Then, the direction changing part 572 changes the flow direction of the treatment target gas and the decarboxylated gas supplied from the discharge hole 571 and then ejects them from the jet hole 573. Therefore, a configuration in which the treatment target gas and the decarboxylated gas are ejected downward Dvd in the vertical direction Dv inside the stored absorption liquid or washing water can be easily obtained. Therefore, the gas supplied from the absorption unit 52 and the recovery unit 61 below Dvd can be ejected downward Dvd in the vertical direction Dv in the stored liquid with a simple configuration.

[0083] Also, a liquid level adjusting part 70 is arranged to adjust the position of the liquid level of the liquid stored in the absorption unit 52 or the recovery unit 61 to a constant position. Therefore, even if the flow rate of the gas supplied from the treatment target gas diffuser 57 and the decarboxylated gas diffuser 67 changes, the position of the liquid level of the stored liquid can be maintained constant. Thereby, the treatment target gas and the absorption liquid or the decarboxylated gas and the washing water can be stably brought into contact with each other regardless of the fluctuation of the flow rate of the supplied treatment target gas and decarboxylated gas.

[0084] Further, in the liquid level adjustment unit 70, the gas-liquid separation line 71 and the overflow line 72 are connected at the same position as the liquid level of the liquid stored in the absorption liquid storage unit 55 and the cleaning water storage unit 65. Therefore, when the liquid is likely to be stored beyond the connection position between the gas-liquid separation line 71 and the overflow line 72, the stored liquid is sent from the overflow line 72 to the absorption liquid storage unit 55 of another absorption unit 52 or the cleaning water storage unit 65 of the recovery unit 61 below Dvd in the vertical direction Dv. Therefore, the position of the liquid level of the liquid stored in the absorption liquid storage unit 55 and the cleaning water storage unit 65 can be maintained without using a complicated device.

[0085] Also, the gas return height H3 is higher than the overflow height H2, and the blowing height H1 is lower than the overflow height H2. That is, in the vertical direction Dv, the opening position of the discharge hole 571 is higher and the gas ejection position by the ejection hole 573 is lower with respect to the connection position between the gas-liquid separation line 71 and the overflow line 72. Due to the opening position of the discharge hole 571 being higher with respect to the connection position between the liquid separation line and the overflow line 72, the liquid level height H4, which is the liquid level during the operation stop of the absorption tower 2, is always lower than the gas return height H3 associated with the opening position of the discharge hole 571 and is always higher than the blowing height H1 associated with the installation position of the ejection hole 573. Therefore, it is possible to suppress an event in which gas is ejected into the liquid at the start of operation of the absorption towers 2 and 2A. Further, if the opening position of the discharge hole 571 is lower with respect to the connection position between the liquid separation line and the overflow line 72, the liquid level height H4 drops to the gas return height H3 during the operation stop of the absorption tower 2 and cannot be maintained at the overflow height H2. However, in the present embodiment, the liquid level height H4, which is the liquid level of the liquid during the operation stop of the absorption tower 2, can always be maintained at the overflow height H2 and can always be higher than the blowing height H1 associated with the installation position of the ejection hole 573. Therefore, gas and liquid can be stably brought into contact immediately after the start of operation.

[0086] In the absorption tower main body 40, the temperature of the absorption liquid and the gas rises due to the heat generated during the absorption reaction of carbon dioxide by the absorption liquid. In particular, when carbon dioxide is absorbed by the absorption liquid in a plurality of absorption units 52 as in the present embodiment, the temperature of the first absorption unit 521 to the third absorption unit 523 rises step by step. If the temperature rises excessively in the absorption unit 52, an increase in the amount of water vapor in the decarbonated gas and an increase in the absorption liquid component vapor may occur. However, the cooling unit 90 cools the washing water present in the second recovery unit 612. That is, the cooling unit 90 cools the space near the connection position with the absorption tower discharge line 12, and the water vapor and the absorption liquid components in the decarbonated gas at the outlet of the recovery unit 61 condense and are recovered together with the washing water of the water washing unit, thereby suppressing the discharge of the absorption liquid components in the decarbonated gas.

[0087] Moreover, by providing the absorption tower 2 as described above, a carbon dioxide treatment system can be provided even in a case where there is a limit on the height of the installation location.

[0088] <Second Embodiment> Next, the carbon dioxide recovery system 1A according to the second embodiment of the present disclosure will be described. In the second embodiment described below, the same reference numerals are given to the components common to the first embodiment in the drawings, and the description thereof is omitted. In the second embodiment, the configuration of the absorption tower 2A is different from that of the first embodiment.

[0089] As shown in FIG. 5, the absorption tower 2A of the second embodiment includes a first absorption tower main body 41, a second absorption tower main body 42, a main body connection line 43, a carbon dioxide absorption unit 50A, a water washing unit 60A, a liquid level adjustment unit 70A, and a demister 80.

[0090] The first absorption tower main body 41 is a cylindrical container extending in the vertical direction Dv. Inside the first absorption tower main body 41, the gas to be treated can flow from the lower part Dvd in the vertical direction Dv to the upper part Dvu. Near the bottom of the first absorption tower main body 41, the gas line 11 to be treated is connected. Near the top of the first absorption tower main body 41, the main body connection line 43 is connected. To the first absorption tower main body 41, at a position above Dvu in the vertical direction Dv with respect to the connection position with the gas line 11 to be treated and at a position below Dvd in the vertical direction Dv with respect to the connection position with the main body connection line 43, the lean line 14 is connected.

[0091] The second absorption tower main body 42 is a cylindrical container extending in the vertical direction Dv. The second absorption tower main body 42 is formed to have a lower height in the vertical direction Dv compared to the absorption tower main body 40 and the first absorption tower main body 41 of the first embodiment. The second absorption tower main body 42 is arranged horizontally separated from the first absorption tower main body 41. The position of the top of the second absorption tower main body 42 is arranged so as not to protrude above Dvu in the vertical direction Dv with respect to the position of the top of the first absorption tower main body 41. Inside the second absorption tower main body 42, the decarbonated gas can flow from the lower part Dvd in the vertical direction Dv to the upper part Dvu. Near the top of the second absorption tower main body 42, the absorption tower discharge line 12 is connected. To the second absorption tower main body 42, at a position below Dvd in the vertical direction Dv with respect to the connection position with the absorption tower discharge line 12, the washing water supply line 69 is connected. Near the bottom of the second absorption tower main body 42, the main body connection line 43 is connected. To the second absorption tower main body 42, at a position below Dvd in the vertical direction Dv with respect to the connection position with the main body connection line 43, the washing water discharge line 14' is connected. The washing water discharge line merges into the lean line 14 via a pump (not shown).

[0092] The main body connection line 43 connects the first absorption tower main body 41 and the second absorption tower main body 42. The main body connection line 43 sends the decarbonated gas discharged from the first absorption tower main body 41 to the second absorption tower main body 42. The main body connection line 43 is connected near the top of the first absorption tower main body 41 and is connected near the bottom of the second absorption tower main body 42.

[0093] The carbon dioxide absorption section 50A of the second embodiment includes a downward air diffusing section 53 and a plurality of absorption units 52A.

[0094] The downward air diffusing section 53 stores the absorption liquid and ejects the gas to be treated into the absorption liquid. The downward air diffusing section 53 is disposed below the plurality of absorption units 52A in the vertical direction Dv (Dvd). The downward air diffusing section 53 is disposed near the bottom of the first absorption tower main body 41. The downward air diffusing section 53 includes a first bottom storage section 531, an air diffusing pipe 532, a downward gas-liquid separation line 533, and a downward liquid level adjustment tank 534.

[0095] The first bottom storage section 531 stores the absorption liquid. The absorption liquid stored in the first bottom storage section 531 has the highest carbon dioxide concentration in the carbon dioxide absorption section 50A. In the first bottom storage section 531, the absorption liquid is stored such that the liquid level of the stored absorption liquid is located above (Dvu) in the vertical direction Dv with respect to the connection position between the first absorption tower main body 41 and the gas line 11 to be treated.

[0096] The air diffusing pipe 532 extends into the stored absorption liquid from the connection position between the first absorption tower main body 41 and the gas line 11 to be treated. The air diffusing pipe 532 is horizontally disposed and has a plurality of holes facing downward (Dvd) in the vertical direction Dv. The air diffusing pipe 532 ejects the gas to be treated into the stored absorption liquid. The air diffusing pipe 532 ejects the gas to be treated downward (Dvd) in the vertical direction Dv so as to form a froth flow in the absorption liquid.

[0097] The lower gas-liquid separation line 533 is a pipe that connects the inside of the absorption liquid stored in the first bottom storage section 531 and the space above Dvu in the vertical direction Dv with respect to the absorption liquid in the first bottom storage section 531. The lower gas-liquid separation line 533 is capable of supplying the absorption liquid stored in the first bottom storage section 531 and the gas to be treated contained in the absorption liquid upward in the vertical direction Dv to Dvu. The lower gas-liquid separation line 533 is connected to the space above Dvu in the vertical direction Dv with respect to the liquid surface in a wavy state after the gas to be treated is ejected from the air diffuser pipe 532. The lower gas-liquid separation line 533 supplies only the gas to be treated among the absorption liquid and the gas to be treated flowing through the inside to the space above Dvu in the vertical direction Dv with respect to the liquid surface.

[0098] The lower liquid level adjustment tank 534 stores the absorption liquid so as to be located below Dvd in the vertical direction Dv with respect to the liquid surface of the absorption liquid stored in the first bottom storage section 531. The lower liquid level adjustment tank 534 is connected to the lower gas-liquid separation line 533 at the same position as the liquid surface during the stop of operation of the absorption liquid stored in the first bottom storage section 531 in the vertical direction Dv. The rich line 13 is connected to the lower liquid level adjustment tank 534 at a position below Dvd in the vertical direction Dv with respect to the connection position with the lower gas-liquid separation line 533.

[0099] The plurality of absorption units 52A are arranged within the first absorption tower main body 41. The carbon dioxide absorption section 50A of the second embodiment has, as the plurality of absorption units 52A, a first absorption unit 521A, a second absorption unit 522A, a third absorption unit 523A, and a fourth absorption unit 524A. The first absorption unit 521A, the second absorption unit 522A, the third absorption unit 523A, and the fourth absorption unit 524A have the same structure. In the second embodiment, the first absorption unit 521A, the second absorption unit 522A, the third absorption unit 523A, and the fourth absorption unit 524A are arranged in order from bottom to top in the vertical direction Dv with respect to the downward air diffusing section 53. That is, the first absorption unit 521A is arranged at the lowest position in the vertical direction Dv among the four absorption units 52A. The fourth absorption unit 524A is arranged at the highest position in the vertical direction Dv among the four absorption units 52A.

[0100] Also, in the plurality of absorption units 52A, the absorption liquid arranged above in the vertical direction Dv has a lower carbon dioxide concentration. Further, in the fourth absorption unit 524A, the absorption liquid is stored such that the connection position between the first absorption tower main body 41 and the lean line 14 is arranged within the stored absorption liquid.

[0101] The water washing section 60A of the second embodiment has a second bottom storage section 63 and a plurality of recovery units 61A. The second bottom storage section 63 stores washing water. The second bottom storage section 63 stores the washing water with the highest concentration of the components of the absorption liquid among the water washing section 60A. In the second bottom storage section 63, the washing water is stored such that the liquid level of the stored washing water is positioned below in the vertical direction Dv with respect to the connection position between the second absorption tower main body 42 and the main body connection line 43. In the second bottom storage section 63, the washing water is stored such that the connection position between the second absorption tower main body 42 and the washing water discharge line 14' is arranged within the stored washing water.

[0102] The plurality of recovery units 61A are arranged inside the second absorption tower main body 42. That is, the plurality of recovery units 61A are arranged side by side at positions horizontally separated from the plurality of absorption units 52A. Further, the plurality of recovery units 61A are arranged side by side in the vertical direction Dv. Also, the water washing section 60A of the second embodiment has, as the plurality of recovery units 61A, a first recovery unit 611A and a second recovery unit 612A. The first recovery unit 611A and the second recovery unit 612A have the same structure.

[0103] The first recovery unit 611A is arranged above Dvu in the vertical direction Dv with respect to the second bottom storage section 63. In the second embodiment, they are arranged in the order of the first recovery unit 611A and the second recovery unit 612A upward Dvu in the vertical direction Dv with respect to the second bottom storage section 63.

[0104] In the second recovery unit 612A, for example, washing water is supplied from a washing water supply line 69 connected to the regeneration tower 3. In the second recovery unit 612A, the washing liquid is stored such that the connection position between the second absorption tower main body 42 and the washing water supply line 69 is arranged in the stored washing water.

[0105] Also, the absorption unit 52A and the recovery unit 61A of the second embodiment further include a partition plate 59. The partition plate 59 is arranged at at least a part of the absorption unit 52A and the recovery unit 61A. In the second embodiment, the partition plate 59 is arranged in all the absorption units 52A and the recovery units 61A.

[0106] The partition plate 59 divides the storage portion into a plurality of regions arranged horizontally. The partition plate 59 extends above the liquid level of the absorption liquid stored in the storage portion in the upper direction Dvu in the vertical direction Dv. The partition plate 59 is a plate-shaped member that extends straight upward in the vertical direction Dv from the bottom plate portion 551. In the present embodiment, the partition plate 59 divides the storage portion into two regions arranged horizontally. Further, as shown in FIG. 6, the partition plate 59 has communication holes 591 that open in the liquid stored in the storage portion. A plurality (for example, two in the present embodiment) of communication holes 591 are formed. Liquids are allowed to move through the communication holes 591 between the plurality of regions.

[0107] As shown in FIG. 5, the absorption tower 2A of the second embodiment includes, as a plurality of liquid level adjustment units 70A, a first absorption liquid adjustment unit 74A, a second absorption liquid adjustment unit 75A, a third absorption liquid adjustment unit 76A, a fourth absorption liquid adjustment unit 77A, a first washing water adjustment unit 78A, and a second washing water adjustment unit 79A.

[0108] The first absorption liquid adjustment unit 74A is connected to the first absorption tower main body 41. The first absorption liquid adjustment unit 74A separates the gas to be treated from the absorption liquid stored in the first absorption unit 521A. The first absorption liquid adjustment unit 74A supplies the separated gas to be treated to the space above the absorption liquid storage portion 55 of the first absorption unit 521A in the upper direction Dvu in the vertical direction Dv. The first absorption liquid adjustment unit 74A supplies the separated absorption liquid so as to merge with the absorption liquid stored in the first bottom storage portion 531.

[0109] The second absorption liquid adjustment unit 75A is connected to the first absorption tower main body 41. The second absorption liquid adjustment unit 75A separates the gas to be treated from the absorption liquid stored in the second absorption unit 522A. The second absorption liquid adjustment unit 75A supplies the separated gas to be treated to the space above the absorption liquid storage portion 55 of the second absorption unit 522A in the upper direction Dvu in the vertical direction Dv. The second absorption liquid adjustment unit 75A supplies the separated absorption liquid so as to merge with the absorption liquid stored in the absorption liquid storage portion 55 of the first absorption unit 521A.

[0110] The third absorption liquid adjustment unit 76A is connected to the first absorption tower main body 41. The third absorption liquid adjustment unit 76A separates the gas to be treated from the absorption liquid stored in the third absorption unit 523A. The third absorption liquid adjustment unit 76A supplies the separated gas to be treated to the space above Dvu in the vertical direction Dv with respect to the absorption liquid storage section 55 of the third absorption unit 523A. The third absorption liquid adjustment unit 76A supplies the separated absorption liquid so as to merge with the absorption liquid stored in the absorption liquid storage section 55 of the second absorption unit 522A.

[0111] The fourth absorption liquid adjustment unit 77A is connected to the first absorption tower main body 41. The fourth absorption liquid adjustment unit 77A separates the gas to be treated from the absorption liquid stored in the fourth absorption unit 524A. The fourth absorption liquid adjustment unit 77A supplies the separated gas to be treated to the space above Dvu in the vertical direction Dv with respect to the absorption liquid storage section 55 of the fourth absorption unit 524A. The fourth absorption liquid adjustment unit 77A supplies the separated absorption liquid so as to merge with the absorption liquid stored in the absorption liquid storage section 55 of the third absorption unit 523A.

[0112] The first washing water adjustment unit 78A is connected to the second absorption tower main body 42. The first washing water adjustment unit 78A separates the decarbonated gas from the washing water stored in the first recovery unit 611A. The first washing water adjustment unit 78A supplies the separated decarbonated gas to the space above Dvu in the vertical direction Dv with respect to the washing water storage section 65 of the first recovery unit 611A. The first washing water adjustment unit 78A supplies the separated washing water so as to merge with the washing water stored in the second bottom storage section 63.

[0113] The second washing water adjustment unit 79A is connected to the second absorption tower main body 42. The second washing water adjustment unit 79A separates the decarbonated gas from the washing water stored in the second recovery unit 612A. The second washing water adjustment unit 79A supplies the separated decarbonated gas to the space above Dvu in the vertical direction Dv with respect to the washing water storage section 65 of the second recovery unit 612A. The second washing water adjustment unit 79A supplies the separated washing water so as to merge with the washing water stored in the washing water storage section 65 of the first recovery unit 611A.

[0114] The first demister 81A of the second embodiment is arranged inside the first absorption tower main body 41 such that the gas to be treated after contacting the absorption liquid can flow therethrough. The first demister 81A is arranged above the fourth absorption unit 524A in the vertical direction Dv. The first demister 81A is arranged below the connection position between the first absorption tower main body 41 and the main body connection line 43 in the vertical direction Dv (Dvd).

[0115] The second demister 82A of the second embodiment is arranged inside the second absorption tower main body 42 such that the decarbonated gas after contacting the washing water can flow therethrough. The second demister 82A is arranged above the second recovery unit 612A in the vertical direction Dv (Dvu). The second demister 82A is arranged below the connection position between the absorption tower discharge line 12 and the second absorption tower main body 42 in the vertical direction Dv (Dvd).

[0116] The cooling units 90 of the second embodiment are respectively arranged on the first absorption tower main body 41 and the second absorption tower main body 42. That is, the absorption tower 2A of the second embodiment has two cooling units 90. Specifically, the absorption tower 2A of the second embodiment has a first cooling unit 90A and a second cooling unit 90B.

[0117] The first cooling unit 90A is arranged on the first absorption tower main body 41. The first cooling unit 90A has a first cooling line 91A, a first cooling pump 92A, and a first cooler 93A. The first cooling line 91A is connected to the overflow line 72 of the fourth absorption liquid adjustment unit 77A. The first cooling line 91A supplies a part of the absorption liquid flowing through the overflow line 72 to the space above the absorption liquid storage part 55 of the fourth absorption unit 524A in the vertical direction Dv (Dvu).

[0118] The first cooling pump 92A is installed between the first cooling lines 91A and pumps the circulating absorbent liquid. The first cooler 93A is disposed in the middle of the first cooling line 91A and cools the absorbent liquid pumped by the first cooling pump 92A. Specifically, the first cooler 93A cools the absorbent liquid by exchanging heat between the cooling water supplied from the outside and the absorbent liquid flowing through the first cooling line 91A.

[0119] The second cooling section 90B is disposed in the second absorption tower main body 42. The second cooling section 90B includes a second cooling line 91B, a second cooling pump 92B, and a second cooler 93B. The second cooling line 91B is connected to the overflow line 72 of the second washing water adjustment section 79A. The second cooling line 91B supplies a part of the washing water flowing through the overflow line 72 to the space above Dvu in the vertical direction Dv with respect to the washing water storage section 65 of the second recovery unit 612A.

[0120] The second cooling pump 92B is installed between the second cooling lines 91B and pumps the circulating washing water. The second cooler 93B is disposed in the middle of the second cooling line 91B and cools the washing water pumped by the second cooling pump 92B. Specifically, the second cooler 93B cools the washing water by exchanging heat between the cooling water supplied from the outside and the washing water flowing through the second cooling line 91B.

[0121] In the absorption tower 2A of the second embodiment, the gas to be treated supplied from the gas line 11 to be treated first is supplied to the lower air diffusing section 53 in the first absorption tower main body 41. In the lower air diffusing section 53, the supplied gas to be treated is ejected by the diffusing section into the absorption liquid stored in the first bottom storage section 531. As a result, the gas to be treated ejected into the absorption liquid flows downward Dvd in the vertical direction Dv of the absorption liquid so as to form a froth flow. Thereby, the gas to be treated and the absorption liquid come into contact with each other so as to be violently mixed, and carbon dioxide contained in the gas to be treated is supplied to the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the lower liquid level adjustment tank 534 through the lower gas-liquid separation line 533. The absorption liquid sent to the lower liquid level adjustment tank 534 is rich liquid, and after being temporarily stored, it is sent to the rich line 13. Further, the supplied gas to be treated moves upward Dvu in the vertical direction Dv and is sent to a plurality of absorption units 52A.

[0122] After that, the gas to be treated flows in the order of the first absorption unit 521A, the second absorption unit 522A, the third absorption unit 523A, and the fourth absorption unit 524A in the same manner as in the first embodiment.

[0123] The gas to be treated supplied to the first absorption unit 521A is ejected into the absorption liquid and comes into contact with the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the first bottom storage section 531 through the first absorption liquid adjustment section 74A. Further, the gas to be treated that has escaped from the absorption liquid moves upward Dvu in the vertical direction Dv in the space above Dvu of the absorption liquid and is sent to the second absorption unit 522A.

[0124] The gas to be treated supplied to the second absorption unit 522A is ejected into the absorption liquid and comes into contact with the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the absorption liquid storage section 55 of the first absorption unit 521A through the second absorption liquid adjustment section 75A. Further, the gas to be treated that has escaped from the absorption liquid moves upward Dvu in the vertical direction Dv in the space above Dvu of the absorption liquid and is sent to the third absorption unit 523A.

[0125] The gas to be treated supplied to the third absorption unit 523A is ejected into the absorption liquid and comes into contact with the absorption liquid. The absorption liquid that has absorbed carbon dioxide is sent to the absorption liquid storage section 55 of the second absorption unit 522A via the third absorption liquid adjustment section 76A. Further, the gas to be treated that has escaped from the absorption liquid moves upward in the vertical direction Dv in the space Dvu above the absorption liquid and is sent to the fourth absorption unit 524A.

[0126] In the fourth absorption unit 524A, the gas to be treated flows in the same manner as in the other absorption units 52A. At this time, in the absorption liquid storage section 55 of the fourth absorption unit 524A, the lean liquid supplied via the lean line 14 merges with the stored absorption liquid. And also in the fourth absorption unit 524A, the gas to be treated and the absorption liquid come into contact. The absorption liquid that has absorbed carbon dioxide is sent to the absorption liquid storage section 55 of the third absorption unit 523A via the fourth absorption liquid adjustment section 77A. Further, the gas to be treated that has escaped from the absorption liquid becomes decarbonated gas, moves upward in the vertical direction Dv in the space Dvu above the absorption liquid, and is sent to the first demister 81A. By passing through the first demister 81A, the mist contained in the decarbonated gas is removed. The decarbonated gas from which the mist has been removed is sent to the main body connection line 43. Through the main body connection line 43, the decarbonated gas exits the first absorption tower main body 41 and flows into the second absorption tower main body 42.

[0127] Thus, in the carbon dioxide absorption section 50A of the present embodiment, carbon dioxide in the gas to be treated is absorbed by the absorption liquid in five stages: the downward air diffusing section 53, the first absorption unit 521A, the second absorption unit 522A, the third absorption unit 523A, and the fourth absorption unit 524A. As a result, most of the carbon dioxide contained in the gas to be treated is removed, and it becomes decarbonated gas. The decarbonated gas flows upward in the vertical direction Dv and passes through the first demister 81A, whereby the mist contained in the decarbonated gas is removed. The decarbonated gas from which the mist has been removed is sent to the water washing section 60A.

[0128] In the second absorption tower main body 42, the decarbonated gas is sent above the second bottom storage section 63.

[0129] The second bottom storage part 63 stores the washing water. In the second bottom storage part 63, the washing water with the highest concentration of the absorption liquid in the second absorption tower main body 42 is stored. In the second bottom storage part 63, the washing water is stored such that the liquid level of the stored washing water is located below Dvd in the vertical direction Dv with respect to the connection position between the second absorption tower main body 42 and the washing water discharge line 14'.

[0130] The washing water that has recovered the mist of the absorption liquid is sent to the washing water discharge line 14'. Thereafter, the washing water discharge line 14' merges with the lean liquid supplied from the regeneration tower 3 (not shown) and is sent to the absorption liquid storage part 55 of the fourth absorption unit 524A through the lean line 14. Also, the supplied decarburized gas moves upward Dvu in the vertical direction Dv and is sent to a plurality of recovery units 61A.

[0131] Thereafter, the decarburized gas flows in the order of the first recovery unit 611A and the second recovery unit 612A in the same manner as in the first embodiment. Passing through the second recovery unit 612A, the decarburized gas that has escaped from the washing water moves upward in the vertical direction Dv in the space above Dvu of the washing water and is sent to the second demister 82A. As a result, the absorption liquid that has been entrained in the decarburized gas is removed, and the absorption tower exhaust gas is obtained. The absorption tower exhaust gas flows upward Dvu in the vertical direction Dv and passes through the second demister 82A, whereby the mist contained in the absorption tower exhaust gas is further removed. The absorption tower exhaust gas from which the mist has been removed is discharged from the absorption tower discharge line 12 to the outside of the second absorption tower main body 42.

[0132] (Function and effect) In such an absorption tower 2A, the carbon dioxide absorption section 50A has a plurality of absorption units 52A arranged in the vertical direction Dv within the first absorption tower main body 41. And the water washing section 60A has a plurality of recovery units 61A arranged in the vertical direction Dv within the second absorption tower main body 42 disposed horizontally away from the first absorption tower main body 41. That is, the carbon dioxide absorption section 50A and the water washing section 60A are arranged side by side in the horizontal direction instead of the vertical direction Dv. In addition, the second absorption tower main body 42 is arranged such that the position of its top does not protrude above Dvu in the vertical direction Dv with respect to the position of the top of the first absorption tower main body 41. Therefore, while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorption liquid contained in the decarbonated gas after recovering carbon dioxide at the same level as that of the conventional-height absorption tower, the height of the entire absorption tower 2A can be suppressed to be much smaller than that of the absorption tower 2 of the first embodiment.

[0133] Also, in the carbon dioxide absorption section 50A, a downward air diffuser 53 is provided upstream (in the upstream position in the flow direction of the gas to be treated) of the plurality of absorption units 52A. The downward air diffuser 53 jets the gas to be treated into the stored absorption liquid. In particular, in the present embodiment, the gas to be treated is jetted into the absorption liquid so as to form a froth flow. Therefore, the absorption liquid and the gas to be treated come into contact more efficiently, and the absorption reaction of carbon dioxide by the absorption liquid is further promoted. Thus, a large amount of carbon dioxide can be recovered from the gas to be treated before being supplied to the plurality of absorption units 52A. As a result, the recovery efficiency of carbon dioxide from the gas to be treated can be further improved.

[0134] In addition, a partition plate 59 is disposed in the absorption liquid storage section 55 and the washing water storage section 65. By the partition plate 59, the absorption liquid storage section 55 and the washing water storage section 65 are partitioned into a plurality of regions arranged in the horizontal direction. Therefore, the regions for storing the liquid in the absorption liquid storage section 55 and the washing water storage section 65 are separated. As a result, even if unstable flow (the shaking of the stored liquid) of the storage section, which is assumed when the flow rate distribution at the air diffuser pipe 532 is not uniform, occurs and the liquid surface undulates, the displacement amount in the vertical direction Dv of the liquid surface can be suppressed. Further, since the communication holes 591 are formed in the partition plate 59, the liquid stored in each region can freely move between the regions. Therefore, it is possible to suppress a difference in the amount of liquid stored in each region and a difference in the height of the liquid surface. By these, while maintaining the height of the liquid surface of the liquid stored in the absorption liquid storage section 55 and the washing water storage section 65 at a constant position, the displacement in the vertical direction Dv of the liquid surface can also be suppressed.

[0135] In addition, not only the second cooling section 90B that cools the washing water existing in the second recovery unit 612A, but also the first cooling section 90A that cools the absorption liquid existing in the fourth absorption unit 524A is disposed. By being cooled in the fourth absorption unit 524A located at the uppermost Dvu in the vertical direction Dv among the plurality of absorption units 52A, the absorption liquid can be effectively cooled. Further, the first cooling section 90A is disposed in the first absorption tower main body 41, and the second cooling section 90B is disposed in the second absorption tower main body 42, respectively. Since the vapor pressure of the amine in the absorption liquid increases due to the temperature rise of the absorption liquid, the absorption liquid component in the decarbonated gas increases. By performing cooling in the fourth absorption unit 524A, the temperature rise of the absorption liquid in the first absorption tower main body 41 can be suppressed, and the absorption efficiency can be improved. Further, by performing cooling in the second recovery unit 612A, the absorption liquid component from the second absorption tower main body 42 can be suppressed. Thus, since each tower main body is cooled respectively, it becomes possible to improve the absorption efficiency in the first absorption tower main body 41 and suppress the absorption liquid component in the second absorption tower main body 42.

[0136] (Other Embodiments) As described above, the embodiments of the present disclosure have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included.

[0137] Note that the number of absorption units 52, 52A and recovery units 61, 61A to be arranged is not limited to the number in the embodiments. For example, the number of absorption units 52, 52A may be two instead of three, or four or more. Similarly, three or more recovery units 61, 61A may be arranged. That is, in the absorption tower 2 of the first embodiment, two or less or four or more absorption units 52 may be arranged, and in the absorption tower 2A of the second embodiment, three or less or five or more absorption units 52A may be arranged. Also, in the absorption towers 2, 2A of the first and second embodiments, one or three or more recovery units 61, 61A may be arranged. Further, the plurality of absorption units 52, 52A and recovery units 61, 61A are not limited to having the same structure. The plurality of absorption units 52, 52A and recovery units 61, 61A may have different structures as long as they can eject gas in the liquid.

[0138] Also, the configurations of the gas diffusing section 57 for the gas to be treated and the decarburized gas diffusing section 67 are not limited to the configurations of the above embodiments. That is, the gas diffusing section 57 for the gas to be treated and the decarburized gas diffusing section 67 are not limited to having a structure including discharge holes 571, a direction changing section 572, and ejection holes 573. Also, the gas diffusing section 57 for the gas to be treated and the decarburized gas diffusing section 67 are not limited to having the same structure. The gas diffusing section 57 for the gas to be treated and the decarburized gas diffusing section 67 may have different structures and arrangements according to the stages where they are arranged. Also, the structures of the discharge holes 571, the direction changing section 572, and the ejection holes 573 are not limited to the structures of the above embodiments.

[0139] Also, the liquid level adjusting sections 70, 70A are not limited to the arrangements as in the first and second embodiments. The liquid level adjusting sections 70, 70A may have different structures and arrangements according to the stages where they are arranged.

[0140] Further, the cooling unit 90 is not limited to the arrangement as in the first embodiment or the second embodiment. The cooling unit 90 may be arranged in other stages. Also, the cooling unit 90 may be arranged for each of the plurality of liquid level adjustment units 70, 70A. Note that the first cooling unit 90A for cooling the absorption liquid disclosed in the second embodiment may be applied to the first embodiment.

[0141] Also, the lower air diffusing unit 53 of the second embodiment may be arranged in place of the lower storage unit 51 of the first embodiment. Also, the lower storage unit 51 of the first embodiment may be arranged in place of the lower air diffusing unit 53 of the second embodiment.

[0142] Also, the partition plate 59 is not limited to the structure that divides the storage unit into two regions as in the present embodiment. The partition plate 59 may divide the storage unit into two or more regions. That is, a plurality of partition plates 59 may be arranged for one storage unit. The partition plate 59 may be arranged only for a part of the plurality of stages of absorption units or recovery units. The partition plate 59 of the second embodiment may be arranged in the first embodiment.

[0143] <Appendix> The absorption towers 2, 2A and the carbon dioxide recovery systems 1, 1A described in each embodiment are understood as follows, for example.

[0144] (1) The absorption towers 2 and 2A according to the first aspect bring a gas to be treated containing carbon dioxide into contact with an absorption liquid to cause the absorption liquid to absorb the carbon dioxide, and have a carbon dioxide absorption section 50, 50A and a water washing section 60, 60A. The carbon dioxide absorption section 50, 50A brings the decarbonated gas after contacting with the absorption liquid in the carbon dioxide absorption section 50, 50A into contact with washing water to recover the absorption liquid components entrained in the decarbonated gas. The carbon dioxide absorption section 50, 50A has absorption units 52, 52A that absorb the carbon dioxide from the gas to be treated, and the water washing section 60, 60A has recovery units 61, 61A that recover the absorption liquid components entrained in the decarbonated gas. At least a part of the absorption units 52, 52A and the recovery units 61, 61A has a storage section for storing a liquid and a diffuser section for ejecting a gas into the liquid stored in the storage section.

[0145] According to such a configuration, the gas to be treated is ejected into the absorption liquid stored in the absorption units 52, 52A. Therefore, the stored absorption liquid and the gas to be treated can be efficiently brought into contact with each other. As a result, the absorption reaction of carbon dioxide by the absorption liquid is promoted. Thereby, in the absorption units 52, 52A, even if the height of the storage section in which the absorption liquid is stored and the height of the space Dvu above the absorption liquid are suppressed, the recovery efficiency of carbon dioxide from the gas to be treated can be improved.

[0146] Furthermore, the decarbonated gas after passing through the carbon dioxide absorption sections 50, 50A is ejected into the washing water stored in the recovery units 61, 61A. Therefore, the stored washing water and the decarbonated gas can be efficiently brought into contact with each other. As a result, the recovery of the absorption liquid components by the washing water is promoted. Thereby, in the recovery units 61, 61A, even if the height of the storage section in which the washing water is stored and the height of the space Dvu above the washing water are suppressed, the recovery efficiency of the absorption liquid components from the gas to be treated can be improved.

[0147] By these means, while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorbent components contained in the decarbonated gas after recovering carbon dioxide, the heights of the absorption towers 2 and 2A can be suppressed.

[0148] (2) The absorption towers 2 and 2A according to the second aspect are the absorption towers 2 and 2A of (1), wherein in the absorption units 52 and 52A, the liquid is the absorbent, the gas is the gas to be treated, and in the recovery units 61 and 61A, the liquid is the washing water and the gas is the decarbonated gas that has passed through the carbon dioxide absorption units 50 and 50A.

[0149] (3) The absorption towers 2 and 2A according to the third aspect are the absorption towers 2 and 2A of (1) or (2), wherein the carbon dioxide absorption units 50 and 50A are arranged with a plurality of the absorption units 52 and 52A side by side in the vertical direction Dv, and the carbon dioxide is sequentially absorbed from the gas to be treated by the plurality of absorption units 52 and 52A. The water washing units 60 and 60A are arranged with a plurality of the recovery units 61 and 61A side by side in the vertical direction Dv, and the absorbent components entrained in the decarbonated gas are sequentially recovered by the plurality of recovery units 61 and 61A.

[0150] (4) The absorption towers 2 and 2A according to the fourth aspect are any one of the absorption towers 2 and 2A of (1) to (3), and the air diffusing unit ejects the gas in a direction including a component directed downward Dvd in the vertical direction Dv or in a horizontal direction within the liquid.

[0151] According to such a configuration, by ejecting the gas in a direction including a component directed downward Dvd in the vertical direction Dv or in a horizontal direction within the liquid, the contact time between the liquid and the gas can be increased as compared with the case where the gas is ejected upward Dvu in the vertical direction Dv. That is, the contact time between the ejected gas and the liquid increases without increasing the position of the liquid level of the stored liquid. Thereby, the recovery efficiency of carbon dioxide from the gas to be treated and the recovery efficiency of the absorbent components contained in the decarbonated gas can be further improved. Therefore, the heights of the absorption towers 2 and 2A can be further suppressed.

[0152] (5) The absorption towers 2 and 2A according to the fifth aspect are any one of the absorption towers 2 and 2A from (1) to (4), and the gas diffusing section includes a discharge hole 571 that discharges the gas upward Dvu in the vertical direction Dv, a direction changing section 572 that covers the discharge hole 571 from above Dvu in the vertical direction Dv and directs the flow direction of the gas downward Dvd in the vertical direction Dv, and a jet hole 573 that jets the gas flowing through the direction changing section 572 into the liquid.

[0153] According to such a configuration, the gas is discharged upward Dvu in the vertical direction Dv by the discharge hole 571. Therefore, when the absorption units 52 and 52A and the recovery units 61 and 61A are stacked in the vertical direction Dv, the gas can be easily supplied from the absorption units 52 and 52A and the recovery units 61 and 61A located below Dvd in the vertical direction Dv to another absorption unit 52 or 52A and recovery unit 61 or 61A located above Dvu in the vertical direction Dv through the discharge hole 571. Then, after changing the flow direction of the gas supplied from the discharge hole 571 by the direction changing section 572, it is jetted from the jet hole 573. Therefore, the gas supplied from the absorption units 52 and 52A and the recovery units 61 and 61A below Dvd can be jetted downward Dvd in the vertical direction Dv in the stored liquid with a simple configuration.

[0154] (6) The absorption towers 2 and 2A according to the sixth aspect are any one of the absorption towers 2 and 2A from (1) to (5), and further include a gas-liquid separation line 71 that connects the liquid stored in the storage section and the space above Dvu in the vertical direction Dv with respect to the liquid in the storage section, and an overflow line 72 that is connected to the gas-liquid separation line 71 at the same position as the liquid level at the time of apparatus stop of the liquid stored in the storage section in the vertical direction Dv and allows the liquid flowing through the gas-liquid separation line 71 to flow downward Dvd in the vertical direction Dv.

[0155] According to such a configuration, when the liquid is likely to be stored beyond the connection position between the gas-liquid separation line 71 and the overflow line 72, the stored liquid is sent from the overflow line 72 to the storage parts of other absorption units 52, 52A or recovery units 61, 61A below Dvd in the vertical direction Dv. Therefore, the position of the liquid level of the liquid stored in the water storage part can be maintained without using a complicated device.

[0156] (7) The absorption towers 2, 2A according to the seventh aspect are the absorption towers 2, 2A of (6), and in the vertical direction Dv, the opening position of the discharge hole 571 is higher than the connection position between the gas-liquid separation line 71 and the overflow line 72, and in the vertical direction Dv, the gas ejection position by the ejection hole 573 is lower than the connection position between the gas-liquid separation line 71 and the overflow line 72.

[0157] According to such a configuration, in the vertical direction Dv, the opening position of the discharge hole 571 is higher and the gas ejection position by the ejection hole 573 is lower with respect to the connection position between the gas-liquid separation line 71 and the overflow line 72. Since the opening position of the discharge hole 571 is higher than the connection position between the liquid separation line and the overflow line 72, the liquid level height, which is the liquid level during the stop of the operation of the absorption towers 2, 2A, is always at a position higher than the opening position of the discharge hole 571. Therefore, it is possible to suppress the occurrence of an event in which gas is ejected into the liquid at the start of the operation of the absorption towers 2, 2A.

[0158] (8) The absorption towers 2, 2A according to the eighth aspect are the absorption towers 2, 2A of any one of (1) to (7), and at least a part of the absorption units 52, 52A and the recovery units 61, 61A extends above Dvu in the vertical direction Dv from the liquid level of the liquid stored in the storage part, and further includes a partition plate 59 that divides the storage part into a plurality of regions arranged in the horizontal direction. The partition plate 59 has a communication hole 591 that opens in the liquid stored in the storage part.

[0159] According to such a configuration, a region for storing the liquid is separated in the storage section. As a result, even if the stored liquid sways (unstable flow) and the liquid surface undulates, the displacement amount of the liquid surface in the vertical direction Dv can be suppressed. Furthermore, since the communication hole 591 is formed in the partition plate 59, the liquid stored in each region can freely move between the regions. If there is a difference in the amount of liquid stored in each region, a difference in the reaction time between the absorbent liquid and the gas to be treated will occur, resulting in an imbalance in the carbon dioxide absorption performance, but this can be suppressed. By these means, while maintaining the position of the liquid surface of the liquid stored in the storage section at a constant position, the displacement of the liquid surface in the vertical direction Dv can also be suppressed.

[0160] (9) The absorption towers 2 and 2A according to the ninth aspect are any one of the absorption towers 2 and 2A in (1) to (8), and further include a cooling section 90 for cooling the liquid.

[0161] According to such a configuration, the cooling section 90 can suppress the temperature rise by cooling the liquid. Thereby, it is possible to suppress a decrease in absorption efficiency and an increase in absorbent liquid components due to the temperature rise of the absorbent liquid in the absorption towers 2 and 2A.

[0162] (10) The absorption towers 2 and 2A according to the tenth aspect are any one of the absorption towers 2 and 2A in (1) to (9), and the carbon dioxide absorption sections 50 and 50A are arranged below the absorption units 52 and 52A in the vertical direction Dv, and have a lower air diffusing section 53 for storing the absorbent liquid and ejecting the gas to be treated into the absorbent liquid.

[0163] According to such a configuration, carbon dioxide can be absorbed more efficiently by ejecting it into the absorbent liquid stored in the first bottom storage section 531.

[0164] (11) The absorption towers 2 and 2A according to the eleventh aspect are any one of the absorption towers 2 and 2A in (1) to (10), and the carbon dioxide absorption sections 50 and 50A and the water washing sections 60 and 60A are arranged side by side in the horizontal direction.

[0165] According to such a configuration, while maintaining the recovery efficiency of carbon dioxide from the gas and the recovery efficiency of the absorbent contained in the decarbonated gas after recovering carbon dioxide, the overall height of the absorption towers 2 and 2A can be significantly reduced.

[0166] (12) The carbon dioxide recovery systems 1 and 1A according to the 12th aspect contact a treatment target gas containing carbon dioxide with an absorbent, and discharge the absorbent that has absorbed the carbon dioxide and an absorption tower exhaust gas containing the treatment target gas from which the carbon dioxide has been removed, using any one of the absorption towers 2 and 2A in (1) to (11). The carbon dioxide is diffused from the absorbent discharged from the absorption towers 2 and 2A, and the regenerator 3 discharges the absorbent from which the carbon dioxide has been diffused and a regenerator exhaust gas containing the carbon dioxide.

[0167] (13) The carbon dioxide absorption method according to the 13th aspect includes a carbon dioxide absorption step of bringing a treatment target gas containing carbon dioxide into contact with an absorbent to absorb the carbon dioxide in the absorbent, and a water washing step of bringing the decarbonated gas after contacting the absorbent in the carbon dioxide absorption step into contact with washing water to recover the absorbent components entrained in the decarbonated gas. At least a part of the carbon dioxide absorption step and the water washing step includes a step of ejecting gas so as to generate a froth flow in the stored liquid, a step of sending a part of the stored liquid downward in the vertical direction, extracting the gas contained in the liquid, and sending it upward in the vertical direction, and a step of sending the gas that has escaped from the liquid upward in the vertical direction.

[0168] According to such steps, by forming a froth flow, the gas-liquid interface is violently disturbed and the gas and liquid are mixed, which can promote the transfer of carbon dioxide from the target treatment gas to the absorbent or the recovery of the absorbent components from the decarbonated gas to the washing water. As a result, carbon dioxide can be efficiently recovered from the treatment target gas, and the absorbent components contained in the decarbonated gas after carbon dioxide recovery can be recovered, and the height of the absorption tower can be suppressed.

Description of Symbols

[0169] 1, 1A... Carbon dioxide recovery system 2, 2A... Absorption tower 11... Gas line to be treated 12... Absorption tower discharge line 3... Regeneration tower 31... Reboiler 13... Rich line 35... Rich pump 14... Lean line 14’... Wash water discharge line 37... Lean pump 4... Absorbent heat exchanger 15... Regeneration tower discharge line 40... Absorption tower body 50, 50A... Carbon dioxide absorption section 51... Lower storage section 52, 52A... Absorption unit 521, 521A... First absorption unit 522, 522A... Second absorption unit 523, 523A... Third absorption unit 55... Absorbent storage section 551... Bottom plate section 57... Gas dispersion section for gas to be treated 571... Discharge hole 572... Direction change section 573... Ejection hole 581... Collision plate 582... Flow path forming plate 60, 60A... Water washing section 61, 61A... Recovery unit 611, 611A... First recovery unit 612, 612A... Second recovery unit 65... Wash water storage section 67... Decarburized gas dispersion section 69... Wash water supply line 70, 70A... Liquid level adjustment section 71... Gas-liquid separation line 72... Overflow line 74, 74A... First absorbent adjustment section 75, 75A… Second Absorbent Regulating Unit 76, 76A… Third Absorbent Regulating Unit 77A… Fourth Absorbent Regulating Unit 78, 78A… First Wash Water Regulating Unit 79, 79A… Second Wash Water Regulating Unit 80… Demister 81, 81A… First Demister 82, 82A… Second Demister 90… Cooling Unit 91… Cooling Line 92… Cooling Pump 93… Wash Water Cooler 94, 94A, 94B… Cooling Unit Extraction Line 41… First Absorption Tower Body 42… Second Absorption Tower Body 43… Body Connection Line 524A… Fourth Absorption Unit 53… Lower Air Diffusion Section 531… First Bottom Storage Section 532… Air Diffusion Pipe 533… Lower Gas-Liquid Separation Line 534… Lower Liquid Level Adjustment Tank 59… Partition Plate 591… Communication Hole 63… Second Bottom Storage Section 90A… First Cooling Unit 91A… First Cooling Line 92A… First Cooling Pump 93A… First Cooler 90B… Second Cooling Unit 91B… Second Cooling Line 92B… Second Cooling Pump 93B… Second Cooler Dv… Vertical Direction Dvu… Upward Dvd… Downward

Claims

1. A carbon dioxide absorption unit brings a gas to be treated containing carbon dioxide into contact with an absorbent liquid, and the absorbent liquid absorbs the carbon dioxide. The system includes a washing section that brings the decarbonated gas, which has come into contact with the absorbent liquid in the carbon dioxide absorption section, into washing water and recovers the absorbent liquid components entrained in the decarbonated gas, The carbon dioxide absorption unit has an absorption unit, and the absorption unit absorbs the carbon dioxide from the gas to be treated. The washing section has a recovery unit, and the recovery unit recovers the absorbent liquid components entrained in the decarbonated gas. An absorption tower having at least a portion of the absorption unit and the recovery unit, a storage section for storing liquid, and a diffuser section for ejecting gas within the liquid stored in the storage section.

2. In the aforementioned absorption unit, the liquid is the absorbent liquid, and the gas is the gas to be processed. The absorption tower according to claim 1, wherein in the recovery unit, the liquid is the washing water and the gas is the decarbonated gas that has passed through the carbon dioxide absorption section.

3. The carbon dioxide absorption section has multiple absorption units arranged in a vertical direction, and the multiple absorption units sequentially absorb carbon dioxide from the gas to be treated. The absorption tower according to claim 1 or 2, wherein the washing section is configured to have a plurality of recovery units arranged in the vertical direction, and the plurality of recovery units sequentially recover the absorbent liquid components entrained in the decarbonated gas.

4. The absorption tower according to claim 1 or 2, wherein the diffuser ejects the gas in the liquid in a direction that includes a component directed vertically downward or in a horizontal direction.

5. The aforementioned aeration unit is A discharge port for discharging the gas upward in the vertical direction, A direction changing section that covers the discharge hole from above in the vertical direction and directs the gas flow direction downward in the vertical direction, An absorption tower according to claim 1 or 2, further comprising an ejection port for ejecting the gas that has flowed through the direction-changing section into the liquid.

6. A gas-liquid separation line connects the liquid stored in the storage section to the space above the liquid in the storage section in the vertical direction, The absorption tower according to claim 5, further comprising: an overflow line connected to the gas-liquid separation line at the same position as the liquid level of the liquid stored in the storage section in the vertical direction, and which causes the liquid flowing through the gas-liquid separation line to flow downward in the vertical direction.

7. In the aforementioned vertical direction, the opening position of the discharge hole is higher than the connection position between the gas-liquid separation line and the overflow line. The absorption tower according to claim 6, wherein in the vertical direction, the gas ejection position from the ejection hole is lower than the connection position between the gas-liquid separation line and the overflow line.

8. At least a portion of the absorption unit and the recovery unit further comprises partition plates that extend vertically above the liquid level of the liquid stored in the storage section and divide the storage section into a plurality of horizontally aligned regions. The absorption tower according to claim 1 or 2, wherein the partition plate has a communication hole that opens in the liquid stored in the storage section.

9. The absorption tower according to claim 1 or 2, further comprising a cooling section for cooling the aforementioned liquid.

10. The absorption tower according to claim 1 or 2, wherein the carbon dioxide absorption section is positioned vertically below the absorption unit, stores the absorbent liquid, and has a downward diffuser section for ejecting the gas to be treated into the absorbent liquid.

11. The absorption tower according to claim 1 or 2, wherein the carbon dioxide absorption section and the water washing section are arranged side by side in the horizontal direction.

12. An absorption tower according to claim 1 or 2, wherein a gas to be treated containing carbon dioxide is brought into contact with an absorbent liquid, and the absorption tower exhaust gas containing the absorbent liquid from which the carbon dioxide has been absorbed and the gas to be treated from which the carbon dioxide has been removed is discharged, A carbon dioxide recovery system comprising: a regeneration tower that releases carbon dioxide from the absorbent liquid discharged from the absorption tower, and discharges the absorbent liquid from which the carbon dioxide has been released and the regeneration tower exhaust gas containing the carbon dioxide.

13. A carbon dioxide absorption step involves bringing a gas to be treated containing carbon dioxide into contact with an absorbent liquid, and allowing the absorbent liquid to absorb the carbon dioxide. The process includes a washing step in which the decarbonated gas that has come into contact with the absorbent liquid in the carbon dioxide absorption step is brought into contact with washing water to recover the absorbent liquid components entrained in the decarbonated gas, At least a portion of the carbon dioxide absorption step and the washing step is The steps include: injecting gas into the stored liquid to create a floss flow, The steps include sending a portion of the stored liquid vertically downwards, and extracting the gas contained in the liquid and sending it vertically upwards, A method for absorbing carbon dioxide, comprising the step of sending the gas that has escaped from the liquid upward in the vertical direction.

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