Patent Publication Number: US-2022226770-A1

Title: Carbon dioxide capture system and method of operating carbon dioxide capture system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2021-005073, filed Jan. 15, 2021; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments of the present invention relate to a carbon dioxide capture system and a method of operating the carbon dioxide capture system. 
     BACKGROUND 
     In recent years, the greenhouse effect of carbon dioxide contained in a combustion exhaust gas generated at the time of burning fossil fuels has been pointed out as one of the causes of global warming. 
     Under such circumstances, in a thermal power plant or the like that uses a large amount of fossil fuel, a carbon dioxide capture system is being studied which suppresses the discharge of the carbon dioxide contained in the combustion exhaust gas generated by burning fossil fuel into the atmosphere. In the carbon dioxide capture system, the combustion exhaust gas is brought into contact with an amine-based absorbing liquid, and the carbon dioxide is separated and captured from the combustion exhaust gas. 
     More specifically, the carbon dioxide capture system includes an absorption column and a regeneration column. The absorption column is configured to cause the carbon dioxide contained in a combustion exhaust gas to be absorbed into an amine-based absorbing liquid. The absorbing liquid (rich liquid) absorbing the carbon dioxide is supplied from the absorption column to the regeneration column, and the regeneration column heats the supplied rich liquid to release the carbon dioxide from the rich liquid and regenerates the absorbing liquid. A reboiler for supplying a heat source is connected to the regeneration column, and the rich liquid is heated in the regeneration column. The absorbing liquid (lean liquid) regenerated in the regeneration column is supplied to the absorption column, and the absorbing liquid is configured to circulate in this system. 
     However, in such a carbon dioxide capture system, the combustion exhaust gas (decarbonated combustion exhaust gas) from which the carbon dioxide is absorbed into the amine-based absorbing liquid in the absorption column accompanies an amine when discharged to the atmosphere from the absorption column. That is, since a large amount of combustion exhaust gas is discharged from a thermal power plant or the like, a large amount of an amino group-containing compound (amine) may be discharged along with the decarbonated combustion exhaust gas. On the other hand, the carbon dioxide-containing gas containing the carbon dioxide also accompanies an amine when discharged from the regeneration column. For this reason, when the carbon dioxide capture system is used in the thermal power plant, it is desired to effectively reduce the amine discharged from the carbon dioxide capture system. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a first embodiment of the present invention; 
         FIG. 2  is a graph illustrating a relationship between a flow rate of a first cleaning liquid and a removal rate of mist-like amine in the carbon dioxide capture system illustrated in  FIG. 1 ; 
         FIG. 3  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a second embodiment of the present invention; 
         FIG. 4  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a third embodiment of the present invention; 
         FIG. 5  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a fourth embodiment of the present invention; 
         FIG. 6  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a fifth embodiment of the present invention; 
         FIG. 7  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a sixth embodiment of the present invention; 
         FIG. 8  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a seventh embodiment of the present invention; 
         FIG. 9  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to an eighth embodiment of the present invention; 
         FIG. 10  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a ninth embodiment of the present invention; and 
         FIG. 11  is a diagram illustrating an overall configuration of a carbon dioxide capture system according to a tenth embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A carbon dioxide capture system according to the embodiment includes a carbon dioxide capturer, an absorbing liquid regenerator, a first washer, a second washer, and an absorbing liquid line. The carbon dioxide capturer causes a carbon dioxide contained in a combustion exhaust gas to be absorbed into an absorbing liquid containing an amine. The absorbing liquid regenerator causes the carbon dioxide to be released from the absorbing liquid discharged from the carbon dioxide capturer to regenerate the absorbing liquid. The first washer washes the combustion exhaust gas discharged from the carbon dioxide capturer with a mist of a first cleaning liquid sprayed by a first spray to capture the amine accompanying the combustion exhaust gas. The second washer washes the combustion exhaust gas discharged from the first washer with a second cleaning liquid to capture the amine accompanying the combustion exhaust gas. The absorbing liquid line supplies the absorbing liquid regenerated in the absorbing liquid regenerator as the first cleaning liquid to the first spray. The first cleaning liquid sprayed by the first spray is supplied as the absorbing liquid to the carbon dioxide capturer. 
     A carbon dioxide capture system according to an embodiment includes a carbon dioxide capturer, an absorbing liquid regenerator, and a regeneration washer. The carbon dioxide capturer causes a carbon dioxide contained in a combustion exhaust gas to be absorbed into an absorbing liquid containing an amine. The absorbing liquid regenerator causes the carbon dioxide to be released from the absorbing liquid discharged from the carbon dioxide capturer to discharge a regeneration exhaust gas containing the carbon dioxide and regenerate the absorbing liquid. The regeneration washer washes the regeneration exhaust gas discharged from the absorbing liquid regenerator with a mist of a regeneration cleaning liquid sprayed by a regeneration spray to capture an amine accompanying the regeneration exhaust gas. 
     A method of operating a carbon dioxide capture system according to an embodiment includes causing a carbon dioxide contained in a combustion exhaust gas to be absorbed into an absorbing liquid containing an amine in a carbon dioxide capturer. The operation method includes causing the carbon dioxide to be released from the absorbing liquid discharged from the carbon dioxide capturer to regenerate the absorbing liquid. The operation method includes washing the combustion exhaust gas discharged from the carbon dioxide capturer with a mist of a first cleaning liquid sprayed by a spray in a first washer and capturing the amine accompanying the combustion exhaust gas. The operation method includes washing the combustion exhaust gas discharged from the first washer with a second cleaning liquid and capturing the amine accompanying the combustion exhaust gas. The absorbing liquid regenerated in regenerating the absorbing liquid is supplied as the first cleaning liquid to the first spray. The first cleaning liquid sprayed by the first spray is supplied as the absorbing liquid to the carbon dioxide capturer. 
     A method of operating a carbon dioxide capture system according to an embodiment includes causing a carbon dioxide contained in a combustion exhaust gas to be absorbed into an absorbing liquid containing an amine in a carbon dioxide capturer. The operation method includes causing the carbon dioxide to be released from the absorbing liquid discharged from the carbon dioxide capturer to discharge a regeneration exhaust gas containing the carbon dioxide and regenerate the absorbing liquid in an absorbing liquid regenerator. The operation method includes washing the regeneration exhaust gas discharged from the absorbing liquid regenerator with a mist of a regeneration cleaning liquid sprayed by a regeneration spray in a regeneration washer and capturing the amine accompanying the regeneration exhaust gas. 
     Hereinafter, with reference to the drawings, a description will be given of a carbon dioxide capture system and a method of operating the carbon dioxide capture system in an embodiment of the present invention. 
     First Embodiment 
     First, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a first embodiment of the present invention will be described with reference to  FIGS. 1 and 2 . 
     As illustrated in  FIG. 1 , a carbon dioxide capture system  1  includes an absorption column  20  that causes carbon dioxide contained in a combustion exhaust gas  2  to be absorbed into an amine-containing absorbing liquid, and a regeneration column  30  that releases the carbon dioxide from the absorbing liquid discharged from the absorption column  20  to regenerate the absorbing liquid. The combustion exhaust gas  2  from which the carbon dioxide is absorbed into the absorbing liquid in the absorption column  20  is discharged as a decarbonated combustion exhaust gas  3  (described later) from the absorption column  20 . Further, a carbon dioxide-containing gas  8  (regeneration exhaust gas) containing carbon dioxide is discharged from the regeneration column  30 . Incidentally, the combustion exhaust gas  2  supplied to the absorption column  20  is not particularly limited. However, the combustion exhaust gas  2  may be, for example, a combustion exhaust gas of a boiler (not illustrated) of a thermal power plant, a process exhaust gas, or the like, and may be supplied to the absorption column  20  after a cooling process as needed. 
     The absorbing liquid circulates through between the absorption column  20  and the regeneration column  30 . The absorbing liquid absorbs carbon dioxide in the absorption column  20  to be a rich liquid  4 , and releases the carbon dioxide in the regeneration column  30  to be a lean liquid  5 . The absorption column  20  and the regeneration column  30  are connected by a rich liquid line  15  and a lean liquid line  16 . The rich liquid line  15  supplies the rich liquid  4  discharged from the absorption column  20  to the regeneration column  30 . The lean liquid line  16  (absorbing liquid line) supplies the lean liquid  5  discharged from the regeneration column  30  to the first spray  21   b  of the absorption column  20 . 
     The absorbing liquid is not particularly limited. However, for example, alcoholic hydroxyl group-containing primary amine such as monoethanolamine and 2-amino-2-methyl-1-propanol, alcoholic hydroxyl group-containing secondary amine such as diethanolamine and 2-methylaminoethanol, alcoholic hydroxyl group-containing tertiary amine such as triethanolamine and N-methyldiethanolamine, polyethylene polyamine such as ethylenediamine, triethylenediamine, and diethylenetriamine, piperazine, piperidine, cyclic amine such as pyrrolidine, polyamine such as xylylenediamine, amino acid such as methylaminocarboxylic acid, and the like, and mixtures thereof can be used. These amine compounds are usually used as an aqueous solution of 10 to 70% by weight. In addition, a carbon dioxide absorption promoter or a corrosion inhibitor, and further, methanol, polyethylene glycol, sulfolane, or the like as another medium can be added to the absorbing liquid. 
     The absorption column  20  includes a carbon dioxide capturer  20   a  and an absorption column container  20   c  that houses the carbon dioxide capturer  20   a.    
     The carbon dioxide capturer  20   a  is configured as a countercurrent gas-liquid contact device. As an example, the carbon dioxide capturer  20   a  includes a carbon dioxide capture packed bed  20   d . The carbon dioxide capture packed bed  20   d  is configured by an internal structure such as packing or particles filled inside to increase the gas-liquid contact area. While the lean liquid  5  supplied from the regeneration column  30  flows down on the surface of the internal structure, the lean liquid  5  is brought into gas-liquid contact with carbon dioxide contained in the combustion exhaust gas  2 , and the carbon dioxide is absorbed into the lean liquid  5 . Accordingly, the carbon dioxide is captured (or removed) from the combustion exhaust gas  2 . 
     In this embodiment, a liquid diffuser  20   b  illustrated in  FIG. 3  and the like to be described later is not provided. The lean liquid  5  is supplied to the carbon dioxide capturer  20   a  from the first spray  21   b  described later. The above-described lean liquid line  16  is connected to the first spray  21   b , and the lean liquid  5  is supplied as the first cleaning liquid  11  to the first spray  21   b . That is, the first cleaning liquid  11  sprayed from the first spray  21   b  is formed of the lean liquid  5 . By spraying the first cleaning liquid  11  from the first spray  21   b , the mist of the first cleaning liquid  11  is diffused and dropped toward the carbon dioxide capturer  20   a . The first cleaning liquid  11  that has reached the carbon dioxide capturer  20   a  is supplied as the lean liquid  5  to the surface of the internal structure of the carbon dioxide capture packed bed  20   d . The pressure of the lean liquid  5  supplied to the first spray  21   b  is increased by a lean liquid pump  34 . 
     In the absorption column container  20   c , a first washer  21 , a second washer  22 , and demisters  81  and  82  which will be described later are housed together with the carbon dioxide capture packed bed  20   d . The absorption column container  20   c  is configured to receive the combustion exhaust gas  2  from the lower portion of the absorption column container  20   c  and discharge the combustion exhaust gas  2  as the decarbonated combustion exhaust gas  3  described later from the top of the absorption column container  20   c.    
     The combustion exhaust gas  2  containing carbon dioxide discharged from the outside of the carbon dioxide capture system  1  such as the boiler described above is supplied to a lower portion of the absorption column  20  by a blower (not illustrated). The supplied combustion exhaust gas  2  rises toward the carbon dioxide capture packed bed  20   d  of the carbon dioxide capturer  20   a  in the absorption column  20 . On the other hand, the lean liquid  5  from the regeneration column  30  is sprayed from the first spray  21   b . As a result, the mist of the lean liquid  5  drops and is supplied to the carbon dioxide capture packed bed  20   d . For this reason, the lean liquid  5  flows down on the surface of the internal structure of the carbon dioxide capture packed bed  20   d . In the carbon dioxide capture packed bed  20   d , the combustion exhaust gas  2  and the lean liquid  5  come into gas-liquid contact, and the carbon dioxide contained in the combustion exhaust gas  2  is absorbed into the lean liquid  5  to generate the rich liquid  4 . 
     The generated rich liquid  4  is once stored in the lower portion of the absorption column container  20   c  and is discharged from the lower portion to the rich liquid line  15 . The combustion exhaust gas  2  subjected to gas-liquid contact with the lean liquid  5  is subjected to removal of carbon dioxide, and further rises as the decarbonated combustion exhaust gas  3  from the carbon dioxide capture packed bed  20   d  in the absorption column  20 . 
     A heat exchanger  31  is arranged between the absorption column  20  and the regeneration column  30 . The rich liquid line  15  and the lean liquid line  16  described above pass through the heat exchanger  31 . A rich liquid pump  32  is arranged in the rich liquid line  15 , and the rich liquid  4  discharged from the absorption column  20  is supplied to the regeneration column  30  through the heat exchanger  31  by the rich liquid pump  32 . The heat exchanger  31  exchanges heat between the rich liquid  4  supplied from the absorption column  20  to the regeneration column  30  and the lean liquid  5  supplied from the regeneration column  30  to the absorption column  20 . As a result, the lean liquid  5  serves as a heat source, and the rich liquid  4  is heated to a desired temperature. In other words, the rich liquid  4  serves as a cold heat source, and the lean liquid  5  is cooled to a desired temperature. 
     The regeneration column  30  includes an amine regenerator  30   a  (absorbing liquid regenerator), a liquid diffuser  30   b  arranged above the amine regenerator  30   a , and a regeneration column container  30   c  that houses the amine regenerator  30   a  and the liquid diffuser  30   b.    
     The amine regenerator  30   a  is configured as a countercurrent gas-liquid contact device. As an example, the amine regenerator  30   a  includes an amine regeneration packed bed  30   d . The amine regeneration packed bed  30   d  is configured by an internal structure such as packing or particles filled inside to increase the gas-liquid contact area. While the rich liquid  4  supplied from the absorption column  20  flows down on the surface of the internal structure, the rich liquid  4  is brought into gas-liquid contact with a vapor  7  described later, and the carbon dioxide is released from the rich liquid  4 . Accordingly, the carbon dioxide is captured (or removed) from the rich liquid  4 . 
     The liquid diffuser  30   b  is configured to diffuse and drop the rich liquid  4  toward the amine regenerator  30   a . The rich liquid  4  is supplied to the surface of the internal structure of the amine regeneration packed bed  30   d . The pressure of the rich liquid  4  supplied to the liquid diffuser  30   b  is a pressure that is not so high as compared with the inner pressure of the regeneration column  30 , and the liquid diffuser  30   b  drops the rich liquid  4  to the amine regenerator  30   a  substantially by the action of gravity rather than force. 
     In the regeneration column container  30   c , a regeneration washer  37  and demisters  86  and  87  which will be described later are housed together with the amine regeneration packed bed  30   d  and the liquid diffuser  30   b . The regeneration column container  30   c  is configured to discharge the carbon dioxide-containing gas  8  released from the rich liquid  4  from the top of the regeneration column container  30   c.    
     The reboiler  33  is connected to the regeneration column  30 . The reboiler  33  heats the lean liquid  5  supplied from the regeneration column  30  by the heating medium  6  to generate the vapor  7 , and supplies the generated vapor  7  to the regeneration column  30 . More specifically, a part of the lean liquid  5  discharged from the lower portion of the regeneration column  30  is supplied to the reboiler  33 , and a high-temperature vapor serving as the heating medium  6  is supplied from the outside such as a turbine (not illustrated) or the like. The lean liquid  5  supplied to the reboiler  33  is heated by exchanging heat with the heating medium  6 , and the vapor  7  is generated from the lean liquid  5 . The generated vapor  7  is supplied to the lower portion of the regeneration column  30  and heats the lean liquid  5  in the regeneration column  30 . Incidentally, the heating medium  6  supplied to the reboiler  33  is not limited to high-temperature vapor from the turbine. 
     The vapor  7  is supplied from the reboiler  33  to the lower portion of the regeneration column  30 , and rises toward the amine regeneration packed bed  30   d  of the amine regenerator  30   a  in the regeneration column  30 . On the other hand, the rich liquid  4  from the absorption column  20  is supplied to the liquid diffuser  30   b  and drops from the liquid diffuser  30   b . The rich liquid  4 , then, is supplied to the amine regeneration packed bed  30   d  to flow down on the surface of the internal structure of the amine regeneration packed bed  30   d . In the amine regeneration packed bed  30   d , the rich liquid  4  and the vapor  7  come into gas-liquid contact, and the carbon dioxide gas is released from the rich liquid  4  to generate the lean liquid  5 . In this way, the absorbing liquid is regenerated in the regeneration column  30 . 
     The generated lean liquid  5  is discharged from the lower portion of the regeneration column  30  to the lean liquid line  16 . The vapor  7  subjected to gas-liquid contact with the rich liquid  4  is accompanied by carbon dioxide and is discharged from the top of the regeneration column  30  as the carbon dioxide-containing gas  8 . The discharged carbon dioxide-containing gas  8  also contains vapors. 
     The lean liquid pump  34  is arranged in the lean liquid line  16 . The lean liquid  5  discharged from the regeneration column  30  is supplied to the absorption column  20  through the above-described heat exchanger  31  by the lean liquid pump  34 . As described above, the heat exchanger  31  cools the lean liquid  5  supplied from the regeneration column  30  to the absorption column  20  by exchanging heat with the rich liquid  4  supplied from the absorption column  20  to the regeneration column  30 . Further, the lean liquid line  16  is arranged with a lean liquid cooler  35  (absorbing liquid cooler) that cools the lean liquid  5  supplied from the regeneration column  30  to the carbon dioxide capturer  20   a . In the lean liquid cooler  35 , a cooling medium such as cooling water (for example, cooling water of a cooling tower or seawater) is supplied from the outside, and the lean liquid  5  cooled in the heat exchanger  31  is further cooled to a desired temperature. 
     The lean liquid  5  cooled in the lean liquid cooler  35  is supplied as the first cleaning liquid  11  to the first spray  21   b  of the absorption column  20 . The mist of the first cleaning liquid  11  drops from the first spray  21   b  and passes through a first washing-capturing space  21   a  described later. The mist of the first cleaning liquid  11  is supplied as the lean liquid  5  to the carbon dioxide capture packed bed  20   d  of the carbon dioxide capturer  20   a  to flow down on the surface of the internal structure of the carbon dioxide capture packed bed  20   d . In the carbon dioxide capture packed bed  20   d , the lean liquid  5  comes into gas-liquid contact with the combustion exhaust gas  2 . As a result, the lean liquid  5  becomes the rich liquid  4  by absorbing the carbon dioxide contained in the combustion exhaust gas  2 . In this way, in the carbon dioxide capture system  1 , the absorbing liquid circulates while repeatedly becoming the state of the lean liquid  5  and the state of the rich liquid  4 . 
     The carbon dioxide capture system  1  illustrated in  FIG. 1  includes a gas cooler  40  that cools the carbon dioxide-containing gas  8  discharged from the top of the regeneration column  30  to condense vapors to generate condensed water  9  and a gas-liquid separator  41  that separates the condensed water  9  generated by the gas cooler  40  from the carbon dioxide-containing gas  8 . In this way, the amount of the water contained in the carbon dioxide-containing gas  8  is reduced, and the carbon dioxide-containing gas  8  is discharged as the carbon dioxide gas  10  from the gas-liquid separator  41 . The discharged carbon dioxide gas  10  is supplied to equipment (not illustrated) and stored. On the other hand, the condensed water  9  separated in the gas-liquid separator  41  is supplied to the regeneration column  30  by the condensed water pump  42  and mixed with the absorbing liquid. Incidentally, the gas cooler  40  is externally supplied with a cooling medium (for example, cooling water of a cooling tower or seawater) for cooling the carbon dioxide-containing gas  8 . 
     Incidentally, in the absorption column  20 , the first washer  21  and the second washer  22  are housed. Among them, the first washer  21  washes the decarbonated combustion exhaust gas  3  discharged from the carbon dioxide capturer  20   a  with the mist of the first cleaning liquid  11  and captures the amine as an absorbing liquid component accompanying the decarbonated combustion exhaust gas  3 . The first washer  21  is arranged above the carbon dioxide capturer  20   a.    
     The first washer  21  includes the first washing-capturing space  21   a  and the first spray  21   b  arranged above the first washing-capturing space  21   a.    
     The first washing-capturing space  21   a  is a space arranged below the first spray  21   b . The first washing-capturing space  21   a  in this embodiment is a space arranged from the first spray  21   b  to the carbon dioxide capturer  20   a . The first cleaning liquid  11  is sprayed from the first spray  21   b  into the first washing-capturing space  21   a . The sprayed first cleaning liquid  11  comes into contact with the rising decarbonated combustion exhaust gas  3  while freely dropping in a mist state in the first washing-capturing space  21   a  (that is, dropping without contacting the surface of a structure or the like in the space). Accordingly, the amine accompanying the decarbonated combustion exhaust gas  3  is captured. In the first washer  21 , the mist-like amine can be effectively captured, and the gaseous amine can also be effectively captured. 
     In this embodiment, as described above, the first washing-capturing space  21   a  is formed between the first spray  21   b  and the carbon dioxide capturer  20   a . The first washing-capturing space  21   a  is not provided with a structure such as a packed bed or a shelf for bringing the first cleaning liquid  11  into contact with the decarbonated combustion exhaust gas  3  while flowing down on the surface. The first spray  21   b  faces the carbon dioxide capturer  20   a  via the first washing-capturing space  21   a . That is, a structure or the like in which the first cleaning liquid  11  flows down on the surface is not provided between the first spray  21   b  and the carbon dioxide capturer  20   a , and the first washing-capturing space  21   a  is formed from the first spray  21   b  to the carbon dioxide capturer  20   a . As a result, the first washing-capturing space  21   a  is configured such that the first cleaning liquid  11  comes into contact with the decarbonated combustion exhaust gas  3  while dropping freely. The mist of the first cleaning liquid  11  sprayed from the first spray  21   b  drops in the first washing-capturing space  21   a  where the decarbonated combustion exhaust gas  3  rises, and directly reaches the carbon dioxide capturer  20   a . That is, the first cleaning liquid  11  that passes through the first washing-capturing space  21   a  directly reaches the carbon dioxide capturer  20   a . While dropping, the first cleaning liquid  11  comes into contact with the decarbonated combustion exhaust gas  3 , and the mist-like amine accompanying the decarbonated combustion exhaust gas  3  physically collides with the mist of the first cleaning liquid  11  and is captured. 
     The first spray  21   b  sprays and drops the first cleaning liquid  11  toward the first washing-capturing space  21   a . The first spray  21   b  includes a plurality of spray nozzle holes (not illustrated), and sprays the first cleaning liquid  11  supplied at an increased pressure by a first circulation pump  51  described later from the spray nozzle holes. Accordingly, the first cleaning liquid  11  is turned into a mist and is sprayed at a high speed from the first spray  21   b , and drops freely while being evenly distributed in the first washing-capturing space  21   a . That is, the first spray  21   b  applies a first vertical initial velocity as a vertical velocity component to the first cleaning liquid  11 , so as to forcibly drop (spray) freely with the vertical velocity component in the first washing-capturing space  21   a.    
     In this embodiment, a first receiver  21   c  as illustrated in  FIG. 3  and the like to be described later is not provided. The first spray  21   b  faces the carbon dioxide capturer  20   a  via the first washing-capturing space  21   a . The mist of the first cleaning liquid  11  sprayed from the first spray  21   b  drops in the first washing-capturing space  21   a  and reaches the carbon dioxide capturer  20   a.    
     The second washer  22  washes the decarbonated combustion exhaust gas  3  discharged from the first washer  21  with a second cleaning liquid  12  (or second washing water), and captures the amine accompanying the decarbonated combustion exhaust gas  3 . The second washer  22  is arranged above the first washer  21 . 
     The second washer  22  includes a washing capturer  22   a , a cleaning liquid diffuser  22   b  arranged above the washing capturer  22   a , and a second receiver  22   c  arranged below the washing capturer  22   a.    
     The washing capturer  22   a  is configured as a countercurrent gas-liquid contact device. As an example, the washing capturer  22   a  includes a washing capture packed bed  22   d . The washing capture packed bed  22   d  is configured by an internal structure such as packing or particles filled inside to increase the gas-liquid contact area. The second cleaning liquid  12  is brought into gas-liquid contact with the decarbonated combustion exhaust gas  3  while flowing down on the surface of the internal structure, so as to capture (or remove) the amine accompanying the decarbonated combustion exhaust gas  3 . In the second washer  22 , the gaseous amine can be effectively captured, and the mist-like amine can also be effectively captured. 
     The cleaning liquid diffuser  22   b  is configured to diffuse and drop the second cleaning liquid  12  toward the washing capturer  22   a . The second cleaning liquid  12  is supplied to flow down on the surface of the internal structure of the washing capturer  22   a . The pressure of the second cleaning liquid  12  supplied to the cleaning liquid diffuser  22   b  is lower than the pressure of the first cleaning liquid  11  supplied to the first spray  21   b . The pressure of the second cleaning liquid  12  supplied to the cleaning liquid diffuser  22   b  is not so high as the pressure in the absorption column  20 . The second vertical initial velocity, which is a vertical velocity component which the cleaning liquid diffuser  22   b  applies to the second cleaning liquid  12 , is smaller than the first vertical initial velocity which is a vertical velocity component which the first spray  21   b  of the first washer  21  applies to the first cleaning liquid  11 . The second vertical initial velocity applied to the second cleaning liquid  12  is substantially zero, and the cleaning liquid diffuser  22   b  causes the second cleaning liquid  12  to drop freely in the washing capturer  22   a  non-forcibly by the action of gravity. 
     The second receiver  22   c  is configured to receive and store the second cleaning liquid  12  which flows down on the surface of the internal structure of the washing capturer  22   a  and to allow and the decarbonated combustion exhaust gas  3  which is discharged from the first washing-capturing space  21   a  of the first washer  21  and rises to pass therethrough. That is, the second receiver  22   c  includes a receiver body which receives and stores the second cleaning liquid  12 , an opening which is arranged between the receiver bodies and allows the decarbonated combustion exhaust gas  3  to pass therethrough, and a cover which covers the opening from above and suppresses the second cleaning liquid  12  from passing through the opening. 
     A second circulation line  54  which circulates the second cleaning liquid  12  is connected to the second washer  22 . That is, a second circulation pump  55  is arranged in the second circulation line  54 , and extracts the second cleaning liquid  12  stored in the second receiver  22   c  and supplies the second cleaning liquid  12  to the cleaning liquid diffuser  22   b . In this way, the second cleaning liquid  12  is circulated. 
     In this embodiment, a second cleaning liquid cooler  56  which cools the second cleaning liquid  12  is arranged in the second circulation line  54 . The second cleaning liquid cooler  56  is supplied with a cooling medium (for example, cooling water of a cooling tower or seawater) from the outside of the carbon dioxide capture system  1  as a cooling medium for cooling the second cleaning liquid  12 . In this way, the second cleaning liquid cooler  56  is configured to cool the second cleaning liquid  12  flowing through the second circulation line  54 , and the temperature of the second cleaning liquid  12  is lower than the temperature of the first cleaning liquid  11 . However, the temperature of the second cleaning liquid  12  and the temperature of the first cleaning liquid  11  may be configured to be substantially equal. 
     A first washer exit demister  81  is arranged between the first washer  21  and the second washer  22 . The first washer exit demister  81  is arranged between the first washer  21  and the second washer  22  (more specifically, between the first spray  21   b  and the second receiver  22   c ). As a result, the decarbonated combustion exhaust gas  3  discharged from the first washer  21  passes through the first washer exit demister  81  and rises. The first washer exit demister  81  traps the mist accompanying the passing decarbonated combustion exhaust gas  3 . The first washer exit demister  81  can effectively trap the mist-like amine and the mist of the first cleaning liquid  11 . 
     The second washer exit demister  82  is arranged above the second washer  22 . The second washer exit demister  82  is arranged above the second washer  22  (more specifically, between the cleaning liquid diffuser  22   b  and the top of the absorption column container  20   c ). As a result, the decarbonated combustion exhaust gas  3  discharged from the second washer  22  passes through the second washer exit demister  82  and rises. The second washer exit demister  82  traps the mist accompanying the passing decarbonated combustion exhaust gas  3 . The second washer exit demister  82  can effectively trap the mist-like amine and the mist of the second cleaning liquid  12 . In addition, since the second cleaning liquid  12  adheres to the second washer exit demister  82 , the second washer exit demister  82  can also trap the gaseous amine. 
     In this embodiment, the washing capture packed bed  22   d  of the second washer  22  may be configured to so that the pressure loss generated in the flow of the decarbonated combustion exhaust gas  3  passing through the washing capture packed bed  22   d  can be lower than the pressure loss generated in the flow in the second washer exit demister  82 . For example, the porosity of the washing capture packed bed  22   d  may be larger than the porosity of the second washer exit demister  82 . In other words, the specific surface area of the washing capture packed bed  22   d  may be smaller than the specific surface area of the second washer exit demister  82 . 
     As illustrated in  FIG. 1 , no demister is provided between the carbon dioxide capturer  20   a  and the first washer  21 . In general, a demister is often arranged between the carbon dioxide capturer  20   a  and the first washer  21 . However, in this embodiment, the first cleaning liquid  11  is formed of the lean liquid  5 , and the difference between the amine concentration of the lean liquid  5  in the carbon dioxide capturer  20   a  and the amine concentration of the first cleaning liquid  11  in the first washer  21  is small. For this reason, no demister is provided between the carbon dioxide capturer  20   a  and the first washer  21  for the purpose of reducing the pressure loss with respect to the flow of the decarbonated combustion exhaust gas  3 . 
     Incidentally, the flow rate (first flow rate) per unit area and unit time of the first cleaning liquid  11  sprayed from the first spray  21   b  of the first washer  21  is larger than the flow rate (second flow rate) per unit area and unit time of the second cleaning liquid  12  diffused from the cleaning liquid diffuser  22   b  of the second washer  22 . The flow rate of the first cleaning liquid  11  sprayed from the first spray  21   b  is adjusted by the above-described first circulation pump  51  (flow rate adjuster). Similarly, the flow rate of the second cleaning liquid  12  diffused from the cleaning liquid diffuser  22   b  is adjusted by the above-described second circulation pump  55 . 
     Incidentally, the unit area described here is a unit area with respect to the horizontal cross-sectional area where the first spray  21   b  sprays the first cleaning liquid  11  (or the horizontal cross-sectional area of the first washer  21 ) and the horizontal cross-sectional area where the cleaning liquid diffuser  22   b  diffuses the second cleaning liquid  12  (or the horizontal cross-sectional area of the second washer  22 ). In this embodiment, the horizontal cross-sectional areas of the first washer  21  and the second washer  22  are substantially equal, and thus the first flow rate and the second flow rate may be set on the basis of the flow rate per unit time without consideration of the difference between the horizontal cross-sectional areas of the washers (the first washer  21  and the second washer  22 ). 
     When generalization is made to include a case where the horizontal cross-sectional areas of the washers  21  and  22  are different, for example, the flow rate (first flow rate) per unit area and unit time of the first cleaning liquid  11  sprayed from the first spray  21   b  may be 200 L/min/m 2  or more or may be 300 L/min/m 2  or more. The flow rate (second flow rate) per unit area and unit time of the second cleaning liquid  12  diffused from the cleaning liquid diffuser  22   b  may be 50 L/min/m 2  to 150 L/min/m 2  (the normal flow rate range illustrated in  FIG. 2 ). 
     The second cleaning liquid  12  diffused from the cleaning liquid diffuser  22   b  comes into gas-liquid contact with the decarbonated combustion exhaust gas  3  while flowing down on the surface of the internal structure forming the washing capture packed bed  22   d . For this reason, even if the flow rate of the second cleaning liquid  12  per unit area and unit time is larger than 150 L/min/m 2 , the contribution to the improvement of the washing efficiency of the decarbonated combustion exhaust gas  3  is limited. Further, increasing the flow rate of the second cleaning liquid  12  more than necessary increases the capacity of the second circulation pump  55  and increases the operating cost, which is not preferable. However, in the first washer  21 , the first cleaning liquid  11  sprayed from the first spray  21   b  is brought into contact with the decarbonated combustion exhaust gas  3  in a mist state without providing a member such as a packed bed. Increasing the flow rate per unit area and unit time of the first cleaning liquid  11  can contribute to increasing the probability of physical collision with the mist-like amine accompanying the decarbonated combustion exhaust gas  3  and can improve the washing efficiency of the decarbonated combustion exhaust gas  3 . This is illustrated in  FIG. 2 . 
       FIG. 2  is a graph illustrating a relationship between the flow rate of the first cleaning liquid  11  and the mist-like amine removal rate (capture efficiency). This data is obtained under the following test conditions.
         Inner diameter of test device (corresponding to the inner diameter of the part where the first washer  21  is arranged in the absorption column container  20   c ) . . . 157 mm   Flow rate of treatment gas (corresponding to the flow rate of the decarbonated combustion exhaust gas  3 ) . . . 0.7 m/s   Concentration of mist-like amine droplets (particle size 0.61 μm to 0.95 μm) . . . about 10,000/cc   Mean particle size of cleaning liquid mist: about 300 μm   Pressure of cleaning liquid . . . 0.2 MPa       

     As illustrated in  FIG. 2 , the removal rate of the mist-like amine is low in the normal flow rate range of the second cleaning liquid  12 , but the removal rate increases beyond this range. When the flow rate is 300 L/min/m 2  or more, a significant removal effect is exhibited, and when the flow rate is 300 L/min/m 2  or more, the removal effect can be enhanced. When the flow rate is 300 L/min/m 2  or more, the removal rate exceeds 70%, and the removal rate of mist-like amine can be increased. 
     As illustrated in  FIG. 1 , the regeneration column  30  includes the regeneration washer  37  configured to wash the carbon dioxide-containing gas  8  discharged from the above-described amine regenerator  30   a  with the condensed water  9  and captures the amine accompanying the carbon dioxide-containing gas  8 . The regeneration washer  37  is arranged above the amine regenerator  30   a.    
     The regeneration washer  37  includes a regeneration column capturer  37   a  and a liquid diffuser  37   b  arranged above the regeneration column capturer  37   a.    
     The regeneration column capturer  37   a  is configured as a countercurrent gas-liquid contact device. As an example, the regeneration column capturer  37   a  includes a regeneration column capture packed bed  37   d . The regeneration column capture packed bed  37   d  is configured by an internal structure such as packing or particles filled inside to increase the gas-liquid contact area. The condensed water  9  is brought into gas-liquid contact with the carbon dioxide-containing gas  8  while flowing down on the surface of the internal structure, so as to capture (or remove) the amine from the carbon dioxide-containing gas  8 . 
     The liquid diffuser  37   b  is configured to diffuse and drop the condensed water  9  toward the regeneration column capturer  37   a . The condensed water  9  is supplied to the surface of the internal structure of the regeneration column capture packed bed  37   d . The pressure of the condensed water  9  supplied to the liquid diffuser  37   b  is a pressure that is not so high as compared with the inner pressure of the regeneration column  30 , and the liquid diffuser  37   b  drops the condensed water  9  to the regeneration column capture packed bed  37   d  substantially by the action of gravity rather than force. 
     Incidentally, the first regeneration column demister  86  is arranged above the amine regenerator  30   a  of the regeneration column  30 . The first regeneration column demister  86  is arranged between the amine regenerator  30   a  and the regeneration washer  37  (more specifically, between the liquid diffuser  30   b  and the regeneration column capturer  37   a ). As a result, the carbon dioxide-containing gas  8  discharged from the amine regenerator  30   a  passes through the first regeneration column demister  86  and rises. The first regeneration column demister  86  traps the mist accompanying the passing carbon dioxide-containing gas  8 . The first regeneration column demister  86  can effectively trap the mist-like amine. In addition, since the condensed water  9  dropping from the liquid diffuser  37   b  adheres to the first regeneration column demister  86 , the first regeneration column demister  86  can also trap the gaseous amine. 
     The second regeneration column demister  87  is arranged above the regeneration washer  37 . The second regeneration column demister  87  is arranged above the liquid diffuser  37   b  of the regeneration washer  37  (more specifically, between the liquid diffuser  37   b  and the top of the regeneration column container  30   c ). As a result, the carbon dioxide-containing gas  8  discharged from the regeneration washer  37  passes through the second regeneration column demister  87  and rises. The second regeneration column demister  87  can effectively trap the mist-like amine and the mist of the condensed water  9  accompanying the passing carbon dioxide-containing gas  8 . In addition, since the condensed water  9  adheres to the second regeneration column demister  87 , the second regeneration column demister  87  can also trap the gaseous amine. 
     Next, an action of this embodiment having such a configuration, that is, an operation method of the carbon dioxide capture system will be described. 
     During the operation of the carbon dioxide capture system illustrated in  FIG. 1 , in the carbon dioxide capture packed bed  20   d  of the carbon dioxide capturer  20   a  of the absorption column  20 , the lean liquid  5  supplied from the lean liquid cooler  35  is sprayed as the first cleaning liquid  11  from the first spray  21   b  and drops in the first washing-capturing space  21   a . The first cleaning liquid  11  that passes through the first washing-capturing space  21   a  reaches the carbon dioxide capturer  20   a . Then, as the lean liquid  5 , the first cleaning liquid  11  comes into gas-liquid contact with the combustion exhaust gas  2  while flowing down on the surface of the internal structure of the carbon dioxide capture packed bed  20   d . The carbon dioxide contained in the combustion exhaust gas  2  is absorbed into the lean liquid  5 . The combustion exhaust gas  2  is discharged from the carbon dioxide capturer  20   a  as the decarbonated combustion exhaust gas  3 . 
     The decarbonated combustion exhaust gas  3  that passes through the carbon dioxide capturer  20   a  reaches the first washing-capturing space  21   a  of the first washer  21 . 
     As described above, the first cleaning liquid  11  sprayed from the spray nozzle hole of the first spray  21   b  drops in the first washing-capturing space  21   a  and directly reaches the carbon dioxide capturer  20   a . During this time, the first cleaning liquid  11  physically collides with the decarbonated combustion exhaust gas  3  while dropping in a mist state, and the decarbonated combustion exhaust gas  3  is washed with the first cleaning liquid  11 . As a result, the mist-like amine accompanying the decarbonated combustion exhaust gas  3  is effectively captured in the first cleaning liquid  11 . 
     As illustrated in  FIG. 1 , the decarbonated combustion exhaust gas  3  washed with the first cleaning liquid  11  is discharged from the first washing-capturing space  21   a  of the first washer  21 . Then, the decarbonated combustion exhaust gas  3  further rises in the second washer  22  and passes through the second washer exit demister  82 . At this time, the mist-like amine and the mist of the first cleaning liquid  11  accompanying the decarbonated combustion exhaust gas  3 , and the like are trapped by the second washer exit demister  82 . 
     The decarbonated combustion exhaust gas  3  that passes through the second washer exit demister  82  is discharged to the atmosphere from the top of the absorption column container  20   c.    
     Here, a general problem occurring when the decarbonated combustion exhaust gas  3  is washed in the carbon dioxide capture system  1  will be described. 
     In general, in the carbon dioxide capture system  1 , in order to capture the amine accompanying the decarbonated combustion exhaust gas  3 , a packed bed or a shelf for a cleaning liquid flowing down on the surface is arranged in some cases. In this case, the contact area between the decarbonated combustion exhaust gas  3  and the cleaning liquid increases, and the amine can be effectively captured. 
     The amine accompanying the decarbonated combustion exhaust gas  3  is roughly classified into the gaseous amine and the mist-like amine. Among them, the gaseous amine is easily captured by washing using a cleaning liquid, a packed bed, and the like. On the other hand, the mist-like amine is hardly captured by washing using a cleaning liquid, a packed bed, and the like. The mist-like amine is easily trapped by the demister. However, when the particle size of the mist is 5 μm or less, it is difficult to trap the mist-like amine by the demister. In order to improve the removal rate of the mist-like amine having a particle size of 5 μm or less, it is conceivable to use a high-density demister. However, the high-density demister may increase the pressure loss generated in the flow of the decarbonated combustion exhaust gas  3  passing therethrough. In this case, the power of the blower that supplies the combustion exhaust gas  2  to the absorption column  20  is increased, and the operating cost is increased. Further, in a case where a high-density demister is used, a problem that clogging of the demister may occur is also considered. 
     In this regard, in this embodiment, the removal rate (capture efficiency) of the mist-like amine is improved by turning the cleaning liquid into a mist. That is, in this embodiment, the pressure of the first cleaning liquid  11  supplied to the first spray  21   b  of the first washer  21  is increased, and the first cleaning liquid  11  is sprayed from the spray nozzle hole of the first spray  21   b  (particularly immediately after the spray) at high speed. As a result, the mist of the first cleaning liquid  11  physically collides with the mist-like amine accompanying the decarbonated combustion exhaust gas  3 , and the mist-like amine is trapped to be captured by the mist of the first cleaning liquid  11 . The first cleaning liquid  11  capturing the mist-like amine drops into the carbon dioxide capturer  20   a . In this way, the mist-like amine that is hardly trapped in cleaning using a cleaning liquid, a packed bed, or the like, is captured into the first cleaning liquid  11 , and the decarbonated combustion exhaust gas  3  is washed effectively. Further, it is possible to avoid the problem of pressure loss that occurs at the time of using a high-density demister as described above. 
     Here, as a general cleaning liquid, pure water may be used instead of the absorbing liquids  4  and  5 . In this case, the amine concentration of the cleaning liquid is low, and even when the amine is trapped, the amine concentration of the cleaning liquid is lower than the amine concentrations of the absorbing liquids  4  and  5 . Therefore, there is a problem that it is difficult to use such a cleaning liquid as an absorbing liquid. In order to increase the amine concentration, it is conceivable to perform a distillation treatment of the cleaning liquid or a concentration treatment using a membrane. However, in this case, there is a problem that energy consumption increases. 
     On the other hand, in this embodiment, the lean liquid  5  is used for the first cleaning liquid  11 , and the lean liquid  5  is sprayed from the first spray  21   b . The mist of the lean liquid  5  sprayed from the first spray  21   b  physically collides with the mist-like amine accompanying the decarbonated combustion exhaust gas  3 . As a result, the mist-like amine can be effectively trapped by the mist of the lean liquid  5 . The lean liquid  5  that traps the mist-like amine is supplied to the carbon dioxide capturer  20   a  and used as an absorbing liquid. 
     In this embodiment, the first cleaning liquid  11  with increased pressure is supplied to the first spray  21   b  of the first washer  21 , and the first cleaning liquid  11  is sprayed from the first spray  21   b . As a result, a mist of the first cleaning liquid  11  can be formed, and the washing efficiency of the first washer  21  can be improved. For example, when the mist of the first cleaning liquid  11  is formed using ultrasonic vibration energy, the first cleaning liquid  11  becomes in a finely atomized spray state, and a sufficient velocity component in the vertical direction may be difficult to be given to the mist of the first cleaning liquid  11 . Further, when ultrasonic vibration energy is used, the pressure of the first cleaning liquid  11  is 0.1 MPa or less as described later. Thus, also in this point, a sufficient velocity component in the vertical direction may be difficult to be given to the mist of the first cleaning liquid  11 . On the other hand, in this embodiment, as described later, the pressure of the first cleaning liquid  11  supplied to the first spray  21   b  is increased to, for example, 0.1 MPa to 1.0 MPa. Thus, the first cleaning liquid  11  can be sprayed at high speed to be turned into a mist, and the washing efficiency of the first washer  21  can be improved. 
     As described above, the first cleaning liquid  11  sprayed from the first spray  21   b  drops freely in the first washing-capturing space  21   a  which is not provided with the packed bed or the like without contacting the surface of the structure or the like. In this case, the mist of the first cleaning liquid  11  directly reaches the carbon dioxide capturer  20   a  without colliding with a member such as a structure, and thus, the mist of the first cleaning liquid  11  can be suppressed from being made fine. 
     That is, in a case where a capturer (the washing capturer  22   a  illustrated in  FIG. 3  described later) configured by a packed bed or the like is included similarly to the first washer  21  or a second washer  22 , the mist of the first cleaning liquid  11  sprayed at high speed from the first spray  21   b  collides with the packed bed and the like to be made fine. In this case, the particle size of the mist of the first cleaning liquid  11  becomes small, and the mist easily flows back along with the decarbonated combustion exhaust gas  3 . For this reason, the first cleaning liquid  11  capturing the amine is discharged into the atmosphere along with the decarbonated combustion exhaust gas  3 , and the amount of the amine discharged into the atmosphere may increase, which is problematic. 
     However, in this embodiment, the first washing-capturing space  21   a  is formed below the first spray  21   b , and no member such as a structure such as a packed bed is provided. For this reason, the mist of the first cleaning liquid  11  can be suppressed from being made fine, and the decrease in the washing efficiency of the first washer  21  can be suppressed. For example, by setting the distance from the first spray  21   b  to the carbon dioxide capture packed bed  20   d  to at least 1 m or more, preferably 1.5 m or more, a sufficient first washing-capturing space  21   a  can be provided. In this case, when the mist of the first cleaning liquid  11  reaches the carbon dioxide capture packed bed  20   d , the speed can be reduced, and it is possible to suppress that the mist collides with the carbon dioxide capture packed bed  20   d  to be made fine. Further, in order to suppress that the sprayed mist of the first cleaning liquid  11  accompanies the decarbonated combustion exhaust gas  3 , the distance from the first spray  21   b  to the carbon dioxide capture packed bed  20   d  may be set to 5 m or less. 
     As described above, according to this embodiment, the decarbonated combustion exhaust gas  3  discharged from the carbon dioxide capturer  20   a  is washed with the first cleaning liquid  11  sprayed by the first spray  21   b  of the first washer  21 , and the amine accompanying the decarbonated combustion exhaust gas  3  is captured. As a result, the first cleaning liquid  11  can be turned into a mist, and the mist of the first cleaning liquid  11  can physically collides with the mist-like amine accompanying the decarbonated combustion exhaust gas  3  discharged from the carbon dioxide capturer  20   a . For this reason, the mist-like amine can be effectively captured into the first cleaning liquid  11 , and the washing efficiency of the decarbonated combustion exhaust gas  3  can be improved. As a result, the amount of amine discharged to the atmosphere can be reduced, and the amount of amine discharged to the outside of the carbon dioxide capture system  1  can be reduced. 
     Further, according to this embodiment, the lean liquid line  16  can supply the lean liquid  5  discharged from the amine regenerator  30   a  of the regeneration column  30  as the first cleaning liquid  11  to the first spray  21   b . As a result, the first cleaning liquid  11  using the lean liquid  5  can be sprayed from the first spray  21   b , and the mist of the first cleaning liquid  11  can be brought into physical collision with the mist-like amine accompanying the decarbonated combustion exhaust gas  3 . For this reason, the mist-like amine can be trapped by the lean liquid  5  without using a liquid different from the lean liquid  5  such as washing water. The trapped amine is contained in the lean liquid  5  and can be used as an absorbing liquid. As a result, the amine captured from the decarbonated combustion exhaust gas  3  can be easily used. 
     Further, according to this embodiment, the first washer  21  has the first washing-capturing space  21   a  in which the mist of the first cleaning liquid  11  sprayed from the first spray  21   b  comes into contact with the decarbonated combustion exhaust gas  3  while freely dropping. As a result, it is possible to suppress that the mist of the first cleaning liquid  11  sprayed from the first spray  21   b  collides with a member such as a structure. For this reason, it is possible to suppress that the mist of the first cleaning liquid  11  is made fine to accompany the decarbonated combustion exhaust gas  3 . 
     According to this embodiment, the first spray  21   b  faces the carbon dioxide capturer  20   a . As a result, the mist of the first cleaning liquid  11  sprayed from the first spray  21   b  can pass through the first washing-capturing space  21   a  and reach the carbon dioxide capturer  20   a . Then, the first cleaning liquid  11  can be supplied as the lean liquid  5  to the carbon dioxide capturer  20   a . For this reason, the decarbonated combustion exhaust gas  3  discharged from the carbon dioxide capturer  20   a  can be washed with the lean liquid  5  without using a liquid different from the lean liquid  5  such as washing water. In this case, the configuration of a first circulation line  50  and the like illustrated in  FIG. 3  and the like can be made unnecessary. As a result, the configuration from the carbon dioxide capturer  20   a  to the first washer  21  can be simplified. 
     Incidentally, in the above-described embodiment, an example has been described in which the carbon dioxide capturer  20   a  includes the carbon dioxide capture packed bed  20   d . However, the present invention is not limited to this, and the carbon dioxide capturer  20   a  may be configured by a shelf (not illustrated). The same applies to the washing capturer  22   a , the amine regenerator  30   a , and the regeneration column capturer  37   a.    
     Second Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a second embodiment of the present invention will be described with reference to  FIG. 3 . 
     The second embodiment illustrated in  FIG. 3  is mainly different in that the absorbing liquid line is connected to the first circulation line that supplies the first cleaning liquid in the first receiver to the first spray, and other configurations are substantially the same as those of the first embodiment illustrated in  FIGS. 1 and 2 . Incidentally, in  FIG. 3 , the same parts as those in the first embodiment illustrated in  FIGS. 1 and 2  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 3 , the first washer  21  further includes the first receiver  21   c  arranged below the first washing-capturing space  21   a . The first washing-capturing space  21   a  is formed from the first spray  21   b  to the carbon dioxide capturer  20   a . The mist of the first cleaning liquid  11  sprayed from the first spray  21   b  drops in the first washing-capturing space  21   a , and directly reaches the first receiver  21   c . That is, the first cleaning liquid  11  that passes through the first washing-capturing space  21   a  is directly received by the first receiver  21   c . The first receiver  21   c  includes a receiver body which receives and stores the first cleaning liquid  11 , an opening which is arranged between the receiver bodies and allows the decarbonated combustion exhaust gas  3  to pass therethrough, and a cover which covers the opening from above and suppresses the first cleaning liquid  11  from passing through the opening. 
     A first circulation line  50  which circulates the first cleaning liquid  11  is connected to the first washer  21 . That is, the first circulation pump  51  is arranged in first circulation line  50 . A part of the first cleaning liquid  11  stored in the first receiver  21   c  is extracted from the first receiver  21   c  by the first circulation pump  51 , and is supplied to the first spray  21   b  through the first circulation line  50 . In this way, the first cleaning liquid  11  circulates. The pressure of the first cleaning liquid  11  supplied to the first spray  21   b  is increased by the first circulation pump  51 . 
     The first washing-capturing space  21   a  according to this embodiment can be defined by a distance from the first spray  21   b  to the first receiver  21   c . In this case, by setting the distance from the first spray  21   b  to the first receiver  21   c  to at least 1 m or more, preferably 1.5 m or more, a sufficient first washing-capturing space  21   a  can be arranged. Further, the distance from the first spray  21   b  to the first receiver  21   c  may be 5 m or less. 
     The lean liquid line  16  according to this embodiment is connected to the first circulation line  50 . The lean liquid line  16  may be connected to an upstream position of the first circulation line  50  with respect to the first circulation pump  51 . More specifically, the downstream end of the lean liquid line  16  may be connected to the upstream position of the first circulation line  50  with respect to the first circulation pump  51 . The lean liquid  5  supplied from the lean liquid line  16  is mixed into the first cleaning liquid  11  flowing through the first circulation line  50 . The first cleaning liquid  11  mixed with the lean liquid  5  passes through the first circulation pump  51  and is supplied to the first spray  21   b.    
     In this embodiment, the liquid diffuser  20   b  is arranged above the carbon dioxide capturer  20   a . The liquid diffuser  20   b  is configured to diffuse and drop the first cleaning liquid  11  supplied from a bypass line  60  described later as the lean liquid  5  toward the carbon dioxide capturer  20   a . From this liquid diffuser  20   b , the lean liquid  5  is supplied to the surface of the internal structure of the carbon dioxide capture packed bed  20   d . The pressure of the lean liquid  5  supplied to the liquid diffuser  20   b  is a pressure that is not so high as compared with the inner pressure of the absorption column  20 , and the liquid diffuser  20   b  drops the lean liquid  5  to the carbon dioxide capture packed bed  20   d  substantially by the action of gravity rather than force. 
     The first receiver  21   c  and the liquid diffuser  20   b  are connected by the bypass line  60 . The bypass line  60  supplies a part of the first cleaning liquid  11  in the first receiver  21   c  to the liquid diffuser  20   b . The bypass line  60  may be arranged with a pump (not illustrated), but may not be arranged. Even in the latter case, the first cleaning liquid  11  stored in the first receiver  21   c  can be supplied to the liquid diffuser  20   b  by the action of gravity. 
     As described above, according to this embodiment, the lean liquid line  16  is connected to the first circulation line  50  that supplies the first cleaning liquid  11  in the first receiver  21   c  to the first spray  21   b . As a result, the lean liquid  5  can be mixed into the first cleaning liquid  11  and supplied to the first spray  21   b . For this reason, the mist-like amine accompanying the decarbonated combustion exhaust gas  3  can be trapped by the mist of the first cleaning liquid  11  sprayed from the first spray  21   b.    
     According to this embodiment, the mist of the first cleaning liquid  11  sprayed from the first spray  21   b  is received by the first receiver  21   c . As a result, the lean liquid  5  that traps the mist-like amine can be stored in the first receiver  21   c . When a flow rate adjustment valve (not illustrated) is arranged in at least one of the first circulation line  50  and the bypass line  60 , the supply amount of the first cleaning liquid  11  supplied to the first spray  21   b  and the supply amount of the lean liquid  5  supplied from the liquid diffuser  20   b  can be adjusted. For this reason, it is possible to perform an appropriate operation according to the situation. For example, the spray amount of the first cleaning liquid  11  from the first spray  21   b  may be larger than the supply amount of the lean liquid  5  supplied from the liquid diffuser  20   b . In this case, the spray amount of the first cleaning liquid  11  from the first spray  21   b  can be increased, and the ability to trap the mist-like amine can be enhanced. 
     According to this embodiment, the lean liquid line  16  is connected to the upstream position of the first circulation line  50  with respect to the first circulation pump  51 . As a result, it is possible to prevent the lean liquid  5  from flowing back in the lean liquid line  16 . That is, when the spray amount of the first cleaning liquid  11  from the first spray  21   b  is increased, the discharge amount of the first circulation pump  51  is increased. When the lean liquid line  16  is connected to a downstream position of the first circulation line  50  with respect to the first circulation pump  51 , the lean liquid  5  may flow back in the lean liquid line  16  depending on the discharge amount of the first circulation pump  51 . However, according to this embodiment, the lean liquid line  16  is connected to the upstream position with respect to the first circulation pump  51 . As a result, it is possible to suppress the lean liquid  5  from flowing back in the lean liquid line  16 . 
     According to this embodiment, the bypass line  60  supplies the first cleaning liquid  11  in the first receiver  21   c  to the carbon dioxide capturer  20   a . As a result, the first cleaning liquid  11  that traps the mist-like amine can be supplied to the liquid diffuser  20   b  by the bypass line  60 , and can be used as an absorbing liquid. For this reason, the amine captured from the decarbonated combustion exhaust gas  3  can be easily used. 
     Third Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a third embodiment of the present invention will be described with reference to  FIG. 4 . 
     The third embodiment illustrated in  FIG. 4  is mainly different in that the first circulation line is arranged with a cleaning liquid distributor capable of adjusting the amount of the first cleaning liquid supplied to the first spray and the amount of the first cleaning liquid supplied to the carbon dioxide capturer, and other configurations are substantially the same as those of the second embodiment illustrated in  FIG. 3 . Incidentally, in  FIG. 4 , the same parts as those in the second embodiment illustrated in  FIG. 3  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 4 , a cleaning liquid distributor  61  is arranged in the first circulation line  50 . The cleaning liquid distributor  61  is arranged on the downstream side with respect to the connection position between the first circulation line  50  and the lean liquid line  16 . A cleaning liquid distribution line  62  for supplying the first cleaning liquid  11  to the carbon dioxide capturer  20   a  is connected to the cleaning liquid distributor  61 . The upstream end of the cleaning liquid distribution line  62  is connected to the cleaning liquid distributor  61 , and the downstream end of the cleaning liquid distribution line  62  is connected to the liquid diffuser  20   b . In this embodiment, the bypass line  60  illustrated in  FIG. 3  is not provided. 
     The cleaning liquid distributor  61  can distribute the first cleaning liquid  11  to the first spray  21   b  and the carbon dioxide capturer  20   a . More specifically, the cleaning liquid distributor  61  can adjust the amount of the first cleaning liquid  11  supplied to the first spray  21   b  and the amount of the first cleaning liquid  11  supplied to the carbon dioxide capturer  20   a . That is, the cleaning liquid distributor  61  can adjust the supply amount of the first cleaning liquid  11  supplied to the first spray  21   b  and the supply amount of the first cleaning liquid  11  supplied to the liquid diffuser  20   b . For example, the amount of the first cleaning liquid  11  supplied to the first spray  21   b  may be larger than the amount of the first cleaning liquid  11  supplied to the liquid diffuser  20   b.    
     For example, the amount of the first cleaning liquid  11  to be distributed may be adjusted on the basis of the amount of water (more specifically, the content of water) in the absorbing liquids  4  and  5 . Examples of the water flowing into the absorbing liquids  4  and  5  include water contained in the combustion exhaust gas  2 . On the other hand, examples of the water flowing out of the absorbing liquids  4  and  5  include the water or amine contained in the decarbonated combustion exhaust gas  3 . Further, in order to adjust the amount of water in the absorbing liquids  4  and  5 , the water discharged from the absorbing liquids  4  and  5  to the outside of the carbon dioxide capture system  1  is also exemplified. For this reason, the flow rate of the lean liquid  5  supplied to the carbon dioxide capturer  20   a  and the flow rate of the lean liquid  5  discharged from the regeneration column  30  may not match each other. The cleaning liquid distributor  61  may adjust the flow rate of the first cleaning liquid  11  distributed by the cleaning liquid distributor  61  for the purpose of keeping the amount of water in the absorbing liquids  4  and  5  constant. In this case, the storage amount of the lean liquid  5  stored in a buffer tank (not illustrated) may be measured, and the amount to be distributed by the cleaning liquid distributor  61  may be adjusted on the basis of the storage amount. For example, when the storage amount is large, the amount of the first cleaning liquid  11  supplied to the first spray  21   b  is increased, and when the storage amount is small, the amount of the first cleaning liquid  11  supplied to the carbon dioxide capturer  20   a  is increased. Instead of the storage amount of the lean liquid  5 , the amount of water contained in the lean liquid  5  may be measured to adjust the amount to be distributed by the cleaning liquid distributor  61 . For example, a measuring instrument using the principle of the Karl Fischer titration method or gas chromatography may be used for measuring the water amount. In this case, in the measured value, by adjusting the amount of water in the absorbing liquids  4  and  5 , it is possible to suppress a decrease in the ability to capture the carbon dioxide and to suppress an increase in the viscosity of the absorbing liquids  4  and  5 . For example, the buffer tank may be arranged between the heat exchanger  31  and the lean liquid cooler  35  in the lean liquid line  16 . 
     As described above, according to this embodiment, the first circulation line  50  is arranged with the cleaning liquid distributor  61  capable of adjusting the amount of the first cleaning liquid  11  supplied to the first spray  21   b  and the amount of the first cleaning liquid  11  supplied to the carbon dioxide capturer  20   a . As a result, the amount of the first cleaning liquid  11  supplied to the first spray  21   b  and the amount of the first cleaning liquid  11  supplied to the carbon dioxide capturer  20   a  can be adjusted. For this reason, it is possible to adjust the amount of water in the absorbing liquid  4  or  5  and to stabilize the operation of the carbon dioxide capture system  1 . 
     Fourth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a fourth embodiment of the present invention will be described with reference to  FIG. 5 . 
     The fourth embodiment illustrated in  FIG. 5  is mainly different in that the absorbing liquid line is arranged with an absorbing liquid distributor capable of adjusting the amount of the absorbing liquid supplied to the first circulation line and the amount of the absorbing liquid supplied to the carbon dioxide capturer, and other configurations are substantially the same as those of the second embodiment illustrated in  FIG. 3 . Incidentally, in  FIG. 5 , the same parts as those in the second embodiment illustrated in  FIG. 3  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 5 , an absorbing liquid distributor  63  is arranged in the lean liquid line  16 . The absorbing liquid distributor  63  is arranged on the downstream side of the lean liquid line  16  with respect to the lean liquid cooler  35 . An absorbing liquid distribution line  64  for supplying the lean liquid  5  to the carbon dioxide capturer  20   a  is connected to the absorbing liquid distributor  63 . The upstream end of the absorbing liquid distribution line  64  is connected to the absorbing liquid distributor  63 , and the downstream end of the absorbing liquid distribution line  64  is connected to the liquid diffuser  20   b.    
     The absorbing liquid distributor  63  can distribute the lean liquid  5  to the first circulation line  50  and the carbon dioxide capturer  20   a . More specifically, the absorbing liquid distributor  63  can adjust the amount of the lean liquid  5  supplied to the first circulation line  50  and the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a . That is, the absorbing liquid distributor  63  can adjust the supply amount of the lean liquid  5  supplied to the first circulation line  50  and the supply amount of the lean liquid  5  supplied to the liquid diffuser  20   b . For example, the amount of the lean liquid  5  to be distributed may be adjusted so that the storage amount of the first cleaning liquid  11  stored in the first receiver  21   c  becomes constant. In this case, the liquid level of the first cleaning liquid  11  stored in the first receiver  21   c  may be measured, and the amount of the lean liquid  5  to be distributed may be adjusted so that the liquid level is constant. For example, when the storage amount is large, the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a  is increased, and when the storage amount is small, the amount of the lean liquid  5  supplied to the first circulation line  50  is increased. In this way, it is possible to secure the amount of the first cleaning liquid  11  sprayed from the first spray  21   b  and to secure the ability to trap the mist-like amine. 
     As described above, according to this embodiment, the lean liquid line  16  is arranged with the absorbing liquid distributor  63  capable of adjusting the amount of the lean liquid  5  supplied to the first circulation line  50  and the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a . As a result, the amount of the lean liquid  5  supplied to the first circulation line  50  and the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a  can be adjusted. For this reason, for example, the storage amount of the first cleaning liquid  11  stored in the first receiver  21   c  can be made constant, the amount of the first cleaning liquid  11  sprayed from the first spray  21   b  can be secured, and the ability to trap the mist-like amine can be secured. 
     According to this embodiment, the absorbing liquid distributor  63  is arranged on the downstream side with respect to the lean liquid cooler  35 . As a result, even when the temperature of the lean liquid  5  discharged from the heat exchanger  31  is high, the temperature of the lean liquid  5  supplied to the carbon dioxide capturer  20   a  can be lowered to a temperature at which the capture efficiency of carbon dioxide is excellent. For this reason, in the carbon dioxide capturer  20   a , the capture efficiency of carbon dioxide from the combustion exhaust gas  2  can be improved. 
     Fifth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a fifth embodiment of the present invention will be described with reference to  FIG. 6 . 
     The fifth embodiment illustrated in  FIG. 6  is mainly different in that an absorbing liquid cooler is arranged in the absorbing liquid distribution line, and other configurations are substantially the same as those of the fourth embodiment illustrated in  FIG. 5 . Incidentally, in  FIG. 6 , the same parts as those in the fourth embodiment illustrated in  FIG. 5  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 6 , an absorbing liquid distributor  65  is arranged in the lean liquid line  16 . An absorbing liquid distribution line  66  for supplying the lean liquid  5  to the carbon dioxide capturer  20   a  is connected to the absorbing liquid distributor  65 . The upstream end of the absorbing liquid distribution line  66  is connected to the absorbing liquid distributor  65 , and the downstream end of the absorbing liquid distribution line  66  is connected to the liquid diffuser  20   b.    
     The absorbing liquid distributor  65  can adjust the amount of the lean liquid  5  supplied to the first circulation line  50  and the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a . That is, the absorbing liquid distributor  65  can adjust the supply amount of the lean liquid  5  supplied to the first circulation line  50  and the supply amount of the lean liquid  5  supplied to the liquid diffuser  20   b.    
     The lean liquid cooler  35  according to this embodiment is arranged in the absorbing liquid distribution line  66 . The absorbing liquid distributor  65  is arranged on the upstream side with respect to the lean liquid cooler  35 . More specifically, the absorbing liquid distributor  65  is arranged between the heat exchanger  31  and the lean liquid cooler  35 . 
     Here, the mist-like amine accompanying the decarbonated combustion exhaust gas  3  is hardly captured by washing using a cleaning liquid, a packed bed, and the like. For this reason, in this embodiment, the mist of the first cleaning liquid  11  sprayed from the first spray  21   b  of the first washer  21  is brought into collision with the mist-like amine, and the mist-like amine is captured into the mist of the first cleaning liquid  11 . However, when the particle size of the mist-like amine decreases (for example, when the thickness is 0.5 μm or less), the capture efficiency of the mist-like amine decreases. For this reason, in order to increase the capture efficiency of the mist-like amine, it is effective to increase the particle size of the mist-like amine. 
     As a method for increasing the particle size of the mist-like amine, it is conceivable to make the temperature of the second washer  22  lower than the temperature of the first washer  21  to increase the temperature difference therebetween. In this case, the decarbonated combustion exhaust gas  3  is cooled when passing through the second washer  22 , the water vapor contained in the decarbonated combustion exhaust gas  3  is condensed, and the condensed water is trapped by the mist-like amine, so that the particle size of the mist-like amine can be increased. 
     There are two possible methods for making the temperature of the second washer  22  lower than the temperature of the first washer  21 . The first method is a method of heating the first washer  21 , and the second method is a method of cooling the second washer  22 . 
     The cleaning liquid may be cooled for the purpose of reducing the amine vapor pressure in the cleaning liquid. However, while the operation temperature of a general cleaning liquid is about 30° C. to 40° C., the temperature of the cooled cleaning liquid remains about 20° C. to 30° C., and the temperature difference obtained by cooling becomes small. Thus, it is difficult to increase the temperature difference between the first washer  21  and the second washer  22  by cooling the second cleaning liquid  12 . Further, when the second cleaning liquid  12  is cooled using a chiller or the like having a high cooling ability in order to increase the temperature difference, the energy required for cooling increases rapidly although the temperature of the cleaning liquid can be further lowered. One of the major problems of the carbon dioxide capture system  1  is how to reduce the energy required for capturing carbon dioxide. For this reason, it is not preferable to increase the energy for cooling the decarbonated combustion exhaust gas  3 . 
     In this regard, in this embodiment, attention is paid to the fact that the lean liquid  5  discharged from the heat exchanger  31  is cooled by the lean liquid cooler  35 . That is, the temperature of the first washer  21  during operation is about 30° C. to 40° C., and the temperature of the lean liquid  5  discharged from the heat exchanger  31  is about 50° C. to 60° C. The lean liquid  5  before being cooled by the lean liquid cooler  35  is supplied to the first washer  21 . As a result, the temperature of the first cleaning liquid  11  is increased, and the temperature difference between the first washer  21  and the second washer  22  can be increased. For this reason, the amount of condensed water in the second washer  22  can be increased. The temperature of the first washer  21  is preferably higher by 5° C. to 50° C., and more preferably higher by 10° C. to 30° C. than the temperature at the upper end of the carbon dioxide capturer  20   a.    
     As illustrated in  FIG. 6 , the bypass line  60  is arranged with a bypass cooler  67  that cools the first cleaning liquid  11 . As described above, since the temperature of the first cleaning liquid  11  is increased, it is preferable to cool the first cleaning liquid  11  supplied from the first receiver  21   c  to the liquid diffuser  20   b . For this reason, the bypass cooler  67  is arranged in the bypass line  60 . The first cleaning liquid  11  stored in the first receiver  21   c  is cooled by the bypass cooler  67  and then supplied to the liquid diffuser  20   b . The bypass cooler  67  may cool the first cleaning liquid  11  to the same degree as the temperature of the lean liquid  5  cooled in the lean liquid cooler  35  illustrated in  FIG. 1  and the like. 
     As described above, according to this embodiment, the lean liquid line  16  is arranged with the absorbing liquid distributor  65  capable of adjusting the amount of the lean liquid  5  supplied to the first circulation line  50  and the amount of the lean liquid  5  supplied to the carbon dioxide capturer  20   a . As a result, the temperature of the lean liquid  5  supplied to the first circulation line  50  can be increased, and the temperature of the first cleaning liquid  11  can be made higher than the temperature of the second cleaning liquid  12 . For this reason, the difference between the temperature of the first cleaning liquid  11  and the temperature of the second cleaning liquid  12  can be increased, and the particle size of the mist-like amine can be increased. As a result, the capture efficiency of the mist-like amine can be improved. The amount of amine discharged into the atmosphere can be further reduced. 
     According to this embodiment, the bypass line  60  is arranged with the bypass cooler  67  that cools the first cleaning liquid  11 . As a result, the first cleaning liquid  11  supplied to the liquid diffuser  20   b  can be cooled, and the temperature of the first cleaning liquid  11  can be lowered. For this reason, in the carbon dioxide capturer  20   a , the capture efficiency of carbon dioxide from the combustion exhaust gas  2  can be improved. 
     Sixth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a sixth embodiment of the present invention will be described with reference to  FIG. 7 . 
     The sixth embodiment illustrated in  FIG. 7  is mainly different in that the first washer exit demister is formed sparser than the second washer exit demister, and other configurations are substantially the same as those of the fifth embodiment illustrated in  FIG. 6 . Incidentally, in  FIG. 7 , the same parts as those in the fifth embodiment illustrated in  FIG. 6  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 7 , the first washer exit demister  81  is formed sparser than the second washer exit demister. 
     The fact that the demister is formed sparsely or densely can be explained, for example, on the basis of the porosity of the demister. More specifically, the magnitude of the porosity of the demister may correspond to the sparseness or denseness of the demister. In this case, the fact that the first washer exit demister  81  is formed more sparsely than the second washer exit demister  82  means that the porosity of the first washer exit demister  81  is larger than the porosity of the second washer exit demister  82 . As a result, the space of the first washer exit demister  81  through which the decarbonated combustion exhaust gas  3  passes increases, and the decarbonated combustion exhaust gas  3  easily passes therethrough. For this reason, the pressure loss generated in the flow of the decarbonated combustion exhaust gas  3  can be reduced. For example, in a case where the first washer exit demister  81  and the second washer exit demister  82  are mesh-like demisters, the mesh of the first washer exit demister  81  may be coarser than the mesh of the second washer exit demister  82 . 
     The fact that the demister is formed sparsely or densely can also be explained, for example, on the basis of the mist removal (or capture) rate characteristics of the demister. More specifically, when the characteristics of the demister are indicated by the mist removal rate in a predetermined particle size range (for example, 0.1 μm to 10 μm), the magnitude of the removal rate may be made to correspond to the sparseness or denseness of the dense demister. In this case, the fact that the first washer exit demister  81  is formed more sparsely than the second washer exit demister  82  means that the removal rate of the mist in the predetermined particle size range in the first washer exit demister  81  is smaller than the removal rate of the second washer exit demister  82 . 
     The mist of the first cleaning liquid  11  sprayed from the first spray  21   b  is larger than the particle size of the mist-like amine accompanying the decarbonated combustion exhaust gas  3 , and has, for example, a diameter of 100 μm or more. The first washer exit demister  81  according to this embodiment is formed sparser than the second washer exit demister  82 . As a result, the first washer exit demister  81  can be configured by a demister coarser than the second washer exit demister  82 . For this reason, it is possible to suppress an increase in pressure loss, and it is possible to suppress an increase in the power of the blower that supplies the combustion exhaust gas  2  to the absorption column  20 . Further, even when the mist of the first cleaning liquid  11  having a large particle size accompanies the decarbonated combustion exhaust gas  3 , occurrence of clogging in the first washer exit demister  81  can be suppressed. Further, even when a large amount of mist of the first cleaning liquid  11  accompanies the decarbonated combustion exhaust gas  3 , the occurrence of clogging in the first washer exit demister  81  can be suppressed. 
     On the other hand, the second washer exit demister  82  can be configured by a fine-grained demister and can effectively trap the mist-like amine that cannot be trapped by the first washer exit demister  81 . That is, the second washer exit demister  82  can remove not only the mist of the second cleaning liquid  12  but also the mist of the first cleaning liquid  11  having a relatively small particle size. Further, the second washer exit demister  82  can trap the mist-like amine having a relatively small particle size that passes through the first washer exit demister  81 . When passing through the second washer  22 , the particle size is enlarged by condensation of water, and the mist-like amine is also trapped by the second washer exit demister  82 . 
     As described above, according to this embodiment, the first washer exit demister  81  is formed sparser than the second washer exit demister  82 . As a result, it is possible to suppress an increase in pressure loss in the first washer exit demister  81  and to suppress the occurrence of clogging while effectively trapping the mist-like amine and the mist of the first cleaning liquid  11  accompanying the decarbonated combustion exhaust gas  3 . In this case, the power of the blower for supplying the combustion exhaust gas  2  to the absorption column  20  can be reduced, and the operating cost can be reduced. 
     Seventh Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a seventh embodiment of the present invention will be described with reference to  FIG. 8 . 
     The seventh embodiment illustrated in  FIG. 8  is mainly different in that a cleaning liquid mist capturer arranged between the first washer and the second washer has a mist capture packed bed for capturing the mist of the first cleaning liquid, and other configurations are substantially the same as those of the fifth embodiment illustrated in  FIG. 6 . Incidentally, in  FIG. 8 , the same parts as those in the fifth embodiment illustrated in  FIG. 6  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 8 , the cleaning liquid mist capturer  83  is arranged between the first washer  21  and the second washer  22 . The cleaning liquid mist capturer  83  is arranged above the first spray  21   b  and below the second receiver  22   c . The cleaning liquid mist capturer  83  captures the mist of the first cleaning liquid  11  accompanying the decarbonated combustion exhaust gas  3  discharged from the first washer  21 . 
     The cleaning liquid mist capturer  83  may be configured as a countercurrent gas-liquid contact device. As an example, the cleaning liquid mist capturer  83  includes a mist capture packed bed  83   a . The mist capture packed bed  83   a  is configured by an internal structure such as packing or particles filled inside to increase the gas-liquid contact area. A mist of the first cleaning liquid  11  accompanying the decarbonated combustion exhaust gas  3  discharged from the first washer  21  is brought into contact with and adhered to the surface of the internal structure. Accordingly, the mist of the first cleaning liquid  11  is captured (or removed) from the decarbonated combustion exhaust gas  3 . 
     In this embodiment, the mist capture packed bed  83   a  of the cleaning liquid mist capturer  83  may be configured so that the pressure loss generated in the flow of the decarbonated combustion exhaust gas  3  passing through the mist capture packed bed  83   a  can be lower than the pressure loss generated in the flow in the second washer exit demister  82 . For example, the porosity of the mist capture packed bed  83   a  may be larger than the porosity of the second washer exit demister  82 . In other words, the specific surface area of the mist capture packed bed  83   a  may be smaller than the specific surface area of the second washer exit demister  82 . That is, as described later, the mist capture packed bed  83   a  aims to trap the mist of the first cleaning liquid  11  having a relatively large particle size. On the other hand, the second washer exit demister  82  aims to trap the mist-like amine accompanying the decarbonated combustion exhaust gas  3 , but the mist-like amine has a relatively small particle size. Consequently, in order to reduce the pressure loss, the porosity of the mist capture packed bed  83   a  may be larger than the porosity of the second washer exit demister  82 , and the mist of the first cleaning liquid  11  can be effectively trapped. 
     As described above, according to this embodiment, the cleaning liquid mist capturer  83  arranged between first washer  211  and second washer  22  includes mist capture packed bed  83   a  that captures the mist of first cleaning liquid  11 . As a result, it is possible to suppress an increase in pressure loss in the cleaning liquid mist capturer  83  and to suppress the occurrence of clogging while effectively trapping the mist-like amine and the mist of the first cleaning liquid  11  accompanying the decarbonated combustion exhaust gas  3 . In this case, the power of the blower for supplying the combustion exhaust gas  2  to the absorption column  20  can be reduced, and the operating cost can be reduced. 
     Eighth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to an eighth embodiment of the present invention will be described with reference to  FIG. 9 . 
     The eighth embodiment illustrated in  FIG. 9  is mainly different in that the second washer sprays the second cleaning liquid with the second spray to capture the amine accompanying the combustion exhaust gas with the mist of the second cleaning liquid, and other configurations are substantially the same as those of the fifth embodiment illustrated in  FIG. 6 . Incidentally, in  FIG. 9 , the same parts as those in the fifth embodiment illustrated in  FIG. 6  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 9 , the second washer  22  sprays the second cleaning liquid  12  with a second spray  22   f  to capture the amine accompanying the decarbonated combustion exhaust gas  3  with the mist of the second cleaning liquid  12 . More specifically, the second washer  22  includes a second washing-capturing space  22   e , a second spray  22   f  arranged above the second washing-capturing space  22   e , and the second receiver  22   c  arranged below the second washing-capturing space  22   e.    
     The second washing-capturing space  22   e  is a space arranged below the second spray  22   f . In this embodiment, the second washing-capturing space  22   e  is a space arranged from the second spray  22   f  to the second receiver  22   c . The second cleaning liquid  12  is sprayed from the second spray  22   f  into the second washing-capturing space  22   e . The sprayed second cleaning liquid  12  comes into contact with the rising decarbonated combustion exhaust gas  3  while freely dropping in a mist state in the second washing-capturing space  22   e  (that is, dropping without contacting the surface of a structure or the like in the space). Accordingly, the amine accompanying the decarbonated combustion exhaust gas  3  is captured. In the second washer  22 , the mist-like amine can be effectively captured, and the gaseous amine can also be effectively captured. 
     In this embodiment, as described above, the second washing-capturing space  22   e  is formed between the second spray  22   f  and the second receiver  22   c . The second washing-capturing space  22   e  is not provided with a structure such as a packed bed or a shelf for bringing the second cleaning liquid  12  into contact with the decarbonated combustion exhaust gas  3  while flowing down on the surface. That is, a structure or the like in which the second cleaning liquid  12  flows down on the surface is not provided between the second spray  22   f  and the second receiver  22   c , and the second washing-capturing space  22   e  is formed from the second spray  22   f  to the second receiver  22   c . As a result, the second washing-capturing space  22   e  is configured such that the second cleaning liquid  12  comes into contact with the decarbonated combustion exhaust gas  3  while dropping freely. The mist of the second cleaning liquid  12  sprayed from the second spray  22   f  drops in the second washing-capturing space  22   e  where the decarbonated combustion exhaust gas  3  rises, and directly reaches the second receiver  22   c . That is, the second cleaning liquid  12  that passes through the second washing-capturing space  22   e  is directly received by the second receiver  22   c . While dropping, the second cleaning liquid  12  comes into contact with the decarbonated combustion exhaust gas  3 , and the mist-like amine accompanying the decarbonated combustion exhaust gas  3  physically collides with the mist of the second cleaning liquid  12  and is captured. 
     The second spray  22   f  sprays and drops the second cleaning liquid  12  toward the second washing-capturing space  22   e . The second spray  22   f  may be configured similarly to the first spray  21   b . The second receiver  22   c  receives and stores the second cleaning liquid  12  that drops in the second washing-capturing space  22   e . The second circulation line  54  which circulates the second cleaning liquid  12  is connected to the second receiver  22   c . The second cleaning liquid  12  stored in the second receiver  22   c  is extracted and supplied to the second spray  22   f . In this way, the second cleaning liquid  12  is circulated. 
     As described above, according to this embodiment, the second cleaning liquid  12  is sprayed by the second spray  22   f , and the amine accompanying the decarbonated combustion exhaust gas  3  is captured by the mist of the second cleaning liquid  12 . As a result, the mist of the second cleaning liquid  12  can physically collide with the mist-like amine accompanying the decarbonated combustion exhaust gas  3  discharged from the first washer  21 . For this reason, the mist-like amine can be effectively captured in the second cleaning liquid  12 . Further, since the second cleaning liquid  12  has an amine concentration lower than that of the first cleaning liquid  11 , it is also possible to capture the gaseous amine accompanying the decarbonated combustion exhaust gas  3 . For this reason, the washing efficiency of the decarbonated combustion exhaust gas  3  can be further improved, and the amount of amine discharged into the atmosphere can be further reduced. 
     Ninth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a ninth embodiment of the present invention will be described with reference to  FIG. 10 . 
     The ninth embodiment illustrated in  FIG. 10  is mainly different in that a third washer for washing the combustion exhaust gas discharged from the second washer with a third cleaning liquid and capturing the amine accompanying the combustion exhaust gas is further arranged, and other configurations are substantially the same as those of the eighth embodiment illustrated in  FIG. 9 . Incidentally, in  FIG. 10 , the same parts as those in the eighth embodiment illustrated in  FIG. 9  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 10 , a third washer  23  is further housed in the absorption column  20 . The third washer  23  washes the decarbonated combustion exhaust gas  3  discharged from the second washer  22  with the third cleaning liquid  13  (or third washing water), and captures the amine as an absorbing liquid component accompanying the decarbonated combustion exhaust gas  3 . The third washer  23  is arranged above the second washer  22 . 
     The third washer  23  may be configured similarly to the second washer  22  illustrated in  FIG. 1  and the like. That is, the third washer  23  includes a washing capturer  23   a , a cleaning liquid diffuser  23   b  arranged above the washing capturer  23   a , and a third receiver  23   c  arranged below the washing capturer  23   a.    
     The washing capturer  23   a  is configured as a countercurrent gas-liquid contact device. As an example, the washing capturer  23   a  includes a washing capture packed bed  23   d . In the third washer  23 , the gaseous amine can be effectively captured, and the mist-like amine can also be effectively captured. 
     A third circulation line  57  which circulates the third cleaning liquid  13  is connected to the third washer  23 . That is, a third circulation pump  58  is arranged in the third circulation line  57 , and extracts the third cleaning liquid  13  stored in the third receiver  23   c  and supplies the third cleaning liquid  13  to the cleaning liquid diffuser  23   b . In this way, the third cleaning liquid  13  is circulated. In this embodiment, a third cleaning liquid cooler  59  which cools the third cleaning liquid  13  is arranged in the third circulation line  57 . The third cleaning liquid cooler  59  can be configured similarly to the second cleaning liquid cooler  56 . 
     As described above, according to this embodiment, the decarbonated combustion exhaust gas  3  discharged from the second washer  22  is washed with the third cleaning liquid  13 . As a result, the third washer  23  can mainly capture the gaseous amine accompanying the decarbonated combustion exhaust gas  3 . More specifically, in the first washer  21 , the first cleaning liquid  11  can capture the mist-like amine, and the first cleaning liquid  11  that captures the mist-like amine can be used as the lean liquid  5 . In the second washer  22 , the second cleaning liquid  12  can capture the mist-like amine that cannot be captured in the first washer  21  and capture the gaseous amine. In the third washer  23 , mainly the gaseous amine can be captured. Since the amine concentration of the third cleaning liquid  13  is lower than the amine concentration of the second cleaning liquid  12 , the third cleaning liquid  13  can effectively capture the gaseous amine in the third washer  23 . As a result, the amount of amine discharged to the atmosphere can be further reduced, and the amount of amine discharged to the outside of the carbon dioxide capture system  1  can be further reduced. 
     Tenth Embodiment 
     Next, a carbon dioxide capture system and a method of operating the carbon dioxide capture system according to a tenth embodiment of the present invention will be described with reference to  FIG. 11 . 
     The tenth embodiment illustrated in  FIG. 11  is mainly different in that a regeneration washer for washing regeneration exhaust gas discharged from the absorbing liquid regenerator with a mist of a regeneration cleaning liquid sprayed by a regeneration spray to capture the amine accompanying the regeneration exhaust gas is further arranged, and other configurations are substantially the same as those of the first embodiment illustrated in  FIGS. 1 and 2 . Incidentally, in  FIG. 11 , the same parts as those in the first embodiment illustrated in  FIGS. 1 and 2  are denoted by the same reference numerals, and detailed description will be omitted. 
     In this embodiment, as illustrated in  FIG. 11 , the regeneration washer  37  sprays the condensed water  9  (regeneration cleaning liquid) by a regeneration spray  37   f  to capture the amine accompanying the carbon dioxide-containing gas  8  with the mist of the condensed water  9 . More specifically, the regeneration washer  37  includes a washing-capturing space  37   e  and the regeneration spray  37   f  arranged above the washing-capturing space  37   e.    
     The washing-capturing space  37   e  is a space arranged below the regeneration spray  37   f . In this embodiment, the washing-capturing space  37   e  is a space arranged from the regeneration spray  37   f  to the first regeneration column demister  86 . The condensed water  9  is sprayed from the regeneration spray  37   f  into the washing-capturing space  37   e . The sprayed condensed water  9  comes into gas-liquid contact with the rising carbon dioxide-containing gas  8  while freely dropping in a mist state in the washing-capturing space  37   e  (that is, dropping without contacting the surface of a structure or the like in the space). Accordingly, the amine accompanying the carbon dioxide-containing gas  8  is captured. In the regeneration washer  37 , the mist-like amine can be effectively captured, and the gaseous amine can also be effectively captured. 
     In this embodiment, as described above, the washing-capturing space  37   e  is formed between the regeneration spray  37   f  and the first regeneration column demister  86 . The washing-capturing space  37   e  is not provided with a structure such as a packed bed or a shelf for bringing the condensed water  9  into contact with the carbon dioxide-containing gas  8  while flowing down on the surface. That is, a structure or the like in which the condensed water  9  flows down on the surface is not provided between the regeneration spray  37   f  and the first regeneration column demister  86 , and the washing-capturing space  37   e  is formed from the regeneration spray  37   f  to the first regeneration column demister  86 . As a result, the washing-capturing space  37   e  is configured such that the condensed water  9  comes into contact with the carbon dioxide-containing gas  8  while freely dropping. The mist of the condensed water  9  sprayed from the regeneration spray  37   f  drops in the washing-capturing space  37   e  where the carbon dioxide-containing gas  8  rises, and directly reaches the first regeneration column demister  86 . That is, the condensed water  9  that passes through the washing-capturing space  37   e  directly reaches the first regeneration column demister  86 . While dropping, the condensed water  9  comes into contact with the carbon dioxide-containing gas  8 , and the mist-like amine accompanying the carbon dioxide-containing gas  8  physically collides with the mist of the condensed water  9  and is captured. 
     The regeneration spray  37   f  sprays and drops the condensed water  9  toward the washing-capturing space  37   e . The regeneration spray  37   f  may be configured similarly to the first spray  21   b  or the second spray  22   f.    
     As described above, according to this embodiment, the condensed water  9  is sprayed by the regeneration spray  37   f , and the amine accompanying the carbon dioxide-containing gas  8  is captured by the mist of the condensed water  9 . As a result, the mist of the condensed water  9  can physically collide with the mist-like amine accompanying the carbon dioxide-containing gas  8  discharged from the amine regenerator  30   a . For this reason, the mist-like amine can be effectively captured in the condensed water  9 . Further, since the condensed water  9  has a low amine concentration, it is also possible to capture the gaseous amine accompanying the carbon dioxide-containing gas  8 . For this reason, the washing efficiency of the carbon dioxide-containing gas  8  can be further improved, and the amount of amine discharged into the atmosphere can be further reduced. Further, since the amine can be removed from the carbon dioxide-containing gas  8 , it is possible to increase the purity of carbon dioxide in the carbon dioxide-containing gas. For this reason, the application of carbon dioxide can be expanded. 
     Incidentally, the regeneration washer  37  according to the above-described embodiment is not limited to being applied to the carbon dioxide capture system  1  illustrated in  FIG. 11 , and can be applied to various carbon dioxide capture systems  1 . For example, the regeneration washer  37  illustrated in  FIG. 11  can also be applied to the carbon dioxide capture system  1  illustrated in  FIGS. 3 to 10 . Further, the first washer  21  in the absorption column  20  is not limited to having the configuration including the first spray  21   b . For example, the first washer  21  may have a configuration similar to that of the second washer  22  illustrated in  FIG. 1 , and the carbon dioxide capturer  20   a  may be supplied with the lean liquid  5  from the liquid diffuser  20   b  illustrated in  FIG. 3  and the like. In this case, the lean liquid  5  may be directly supplied from the lean liquid line  16  to the liquid diffuser  20   b , and the bypass line  60  illustrated in  FIG. 3  and the like may not be connected. 
     According to the above-described embodiments, the amount of discharged amine can be reduced. 
     Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in other various forms, and various omissions, replacements and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and the gist of the invention and are included in the invention described in the claims and the equivalent scope thereof. Further, as a matter of course, these embodiments can be partially combined as appropriate within the scope of the gist of the present invention.