Abstract:
A CO 2  recovery apparatus is provided with: a CO 2  absorption tower for bringing exhaust gas into contact with a CO 2  absorbing liquid and making the CO 2  absorbing liquid absorb the CO 2  contained in the exhaust gas; a CO 2  absorbing liquid regeneration tower for heating the CO 2  absorbing liquid with steam and releasing CO 2  from the CO 2  absorbing liquid and regenerating the CO 2  absorbing liquid; a flowmeter for determining the flow rates of the exhaust gas introduced into the CO 2  absorption tower; and a control unit for classifying the flow rates of the exhaust gas into multiple flow rate ranges, and controlling the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower on the basis of prescribed set load values which have been previously established in accordance with the multiple flow rate ranges.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a CO 2  recovery apparatus and a CO 2  recovery process, and particularly to a CO 2  recovery apparatus and a CO 2  recovery process that recover CO 2  in a gas to be treated, using a CO 2  absorbing liquid. 
       BACKGROUND ART 
       [0002]    In the related art, CO 2  recovery apparatuses that recover CO 2  exhausted from boilers or the like of thermoelectric power plants are suggested (for example, refer to PTL 1). In the CO 2  recovery apparatuses, after an exhaust gas is introduced into a CO 2  absorption tower and a CO 2  absorbing liquid is brought into contact with CO 2  contained in the exhaust gas to absorb CO 2 , the CO 2  absorbing liquid that has absorbed CO 2  is introduced into a regeneration tower and is decarboxylated, and a high-concentration CO 2  gas is recovered therefrom. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         [PTL 1] Japanese Patent No. 3212524 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    Meanwhile, in recent years, in boilers or the like of thermoelectric power plants, reduction of the amount of consumption of steam used for regeneration of the CO 2  absorbing liquid for further saving of energy has been desired. In the related-art CO 2  recovery apparatuses, the flow rate of an exhaust gas introduced into the CO 2  absorption tower and CO 2  concentration in the exhaust gas are measured, and the flow rate of the CO 2  absorbing liquid and the amount of consumption of steam used for regeneration of the CO 2  absorbing liquid is reduced on the basis of the measured exhaust gas flow rate and CO 2  concentration. 
         [0005]    However, in the related-art CO 2  recovery apparatuses, an efficient operation control may not necessarily be performed for variations of the CO 2  flow rates in the exhaust gas caused by load variations of the boiler or the like, and further improvements in the efficiency and stability of the operation of the CO 2  recovery apparatuses are desired. 
         [0006]    The invention has been made in view of such actual circumstances, and an object thereof is to provide a CO 2  recovery apparatus and a CO 2  recovery process that can improve the total operational efficiency and stability of the apparatus even in a case where the treatment amount of a gas to be treated varies. 
       Solution to Problem 
       [0007]    A CO 2  recovery apparatus of the invention includes a CO 2  absorption tower that brings a gas to be treated containing CO 2  into contact with a CO 2  absorbing liquid and makes the CO 2  absorbing liquid absorb CO 2  contained in the gas to be treated; a CO 2  absorbing liquid regeneration tower that heats the CO 2  absorbing liquid, which has absorbed CO 2 , with steam, releases CO 2  from the CO 2  absorbing liquid, and regenerates the CO 2  absorbing liquid; a flow rate measuring unit that measures the flow rates of the gas to be treated that is introduced into the CO 2  absorption tower; and a control unit that classifies the flow rates of the gas to be treated measured by the flow rate measuring unit into multiple flow rate ranges, and controls the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower, on the basis of set load values that are preset according to the multiple flow rate range ranges. 
         [0008]    According to this CO 2  recovery apparatus, even in a case where the flow rate of the gas to be treated increases or decreases within classifications of the multiple flow rate ranges, it is possible to maintain operation conditions on the basis of the set load values corresponding to the flow rate ranges. Accordingly, the CO 2  recovery apparatus is able to make the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower small even in a case where the flow rate of the gas to be treated may vary at any time within classifications of the multiple flow rate ranges. Thus, it is possible to improve the total operational efficiency and stability of the apparatus. 
         [0009]    A CO 2  recovery apparatus of the invention includes a CO 2  absorption tower that brings a gas to be treated containing CO 2  into contact with a CO 2  absorbing liquid and makes the CO 2  absorbing liquid absorb CO 2  contained in the gas to be treated; a CO 2  absorbing liquid regeneration tower that heats the CO 2  absorbing liquid, which has absorbed CO 2 , with steam, releases CO 2  from the CO 2  absorbing liquid, and regenerates the CO 2  absorbing liquid; a flow rate measuring unit that measures the flow rates of the gas to be treated that is introduced into the CO 2  absorption tower; a CO 2  concentration measuring unit that measures the CO 2  concentration of the gas to be treated that is introduced into the CO 2  absorption tower; and a control unit that classifies CO 2  flow rates in the gas to be treated, which are obtained on the basis of the flow rates of the gas to be treated that are measured by the flow rate measuring unit and the CO 2  concentration in the gas to be treated that is measured by the CO 2  concentration measuring unit, into multiple flow rate ranges, and controls the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower, on the basis of set load values that are preset according to the multiple flow rate range classifications. 
         [0010]    According to this CO 2  recovery apparatus, even in a case where the CO 2  flow rates increase or decrease within classifications of the multiple flow rate ranges, it is possible to maintain the operation conditions on the basis of the set load values corresponding to the flow rate ranges. Accordingly, in the CO 2  recovery apparatus, even in a case where the flow rate of the gas to be treated vary at any time within classifications of the multiple flow rate ranges, the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower can be made small. Thus, it is possible to improve the total operational efficiency and stability of the apparatus. Moreover, since this CO 2  recovery apparatus controls the operation conditions on the basis of the CO 2  flow rates calculated on the basis of the CO 2  concentration in the gas to be treated, it is possible to further improve the total operational efficiency and stability of the apparatus. 
         [0011]    In the CO 2  recovery apparatus of the invention, it is preferable that the control unit keeps the set load values substantially constant within the multiple flow rate ranges and thereby controls the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower. By virtue of this configuration, the CO 2  recovery apparatus is able to keep the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower substantially constant, even if the flow rate or the like of the gas to be treated may vary at any time within the multiple flow rate ranges. Accordingly, since the CO 2  recovery apparatus can make the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower small, it is possible to further improve the total operational efficiency and stability of the apparatus. 
         [0012]    In the CO 2  recovery apparatus of the invention, it is preferable that the control unit keeps the set load values at maximum values corresponding to the flow rate ranges within the multiple flow rate ranges and thereby controls the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower. By virtue of this configuration, the CO 2  recovery apparatus can control the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower, according to the maximum set load values within the multiple flow rate ranges. Thus, even in a case where the flow rate of the gas to be treated varies within the flow rate ranges, it is possible to appropriately control the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower. 
         [0013]    In the CO 2  recovery apparatus of the invention, it is preferable that there are 7 or less classifications in the multiple flow rate ranges. By virtue of this configuration, in the CO 2  recovery apparatus, the number of the flow rate ranges is in a moderate range. Thus, it is possible to further improve the total operational efficiency and stability of the apparatus. 
         [0014]    A CO 2  recovery process of the invention includes a CO 2  absorption step of bringing a gas to be treated containing CO 2  into contact with a CO 2  absorbing liquid in a CO 2  absorption tower and making the CO 2  absorbing liquid absorb CO 2  contained in the gas to be treated; a regeneration step of heating the CO 2  absorbing liquid, which has absorbed CO 2 , with steam in a CO 2  absorbing liquid regeneration tower, releasing CO 2 , and regenerating the CO 2  absorbing liquid; a step of measuring the flow rates of the gas to be treated that is introduced into the CO 2  absorption tower in a flow rate measuring unit; and a step of classifying the measured flow rates of the gas to be treated into multiple flow rate ranges, and controlling the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower, on the basis of set load values that are preset according to the multiple flow rate range classifications. 
         [0015]    According to this CO 2  recovery process, even in a case where the flow rate of the gas to be treated increases or decreases within classifications of the multiple flow rate ranges, it is possible to maintain operation conditions on the basis of the set load values according to the flow rate ranges. Accordingly, the CO recovery process can make the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower small even in a case where the flow rate of the gas to be treated vary at any time within classifications of the multiple flow rate ranges. Thus, it is possible to improve the total operational efficiency and stability of the apparatus. 
         [0016]    A CO 2  recovery process of the invention includes a CO 2  absorption step of bringing a gas to be treated containing CO 2  into contact with a CO 2  absorbing liquid in a CO 2  absorption tower and making the CO 2  absorbing liquid absorb CO 2  contained in the gas to be treated; a regeneration step of heating the CO 2  absorbing liquid, which has absorbed CO 2 , with steam in a CO 2  absorbing liquid regeneration tower, releasing CO 2 , and regenerating the CO 2  absorbing liquid; a step of measuring the flow rates of the gas to be treated, which is introduced into the CO 2  absorption tower, in a flow rate measuring unit, and measuring the CO 2  concentration of the gas to be treated, which is introduced into the CO 2  absorption tower, in a CO 2  concentration measuring unit; and a step of classifying CO 2  flow rates, which are obtained on the basis of the measured flow rates of the gas to be treated and the measurement value of the CO 2  concentration, into multiple flow rate ranges, and controlling the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower, on the basis of set load values that are preset according to the multiple flow rate range classifications. 
         [0017]    According to this CO 2  recovery process, even in a case where the CO 2  flow rates increase or decrease within classifications of the multiple flow rate ranges, it is possible to maintain operation conditions on the basis of the set load values according to the flow rate ranges. By virtue of this process, the CO 2  recovery process can make the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower even small in a case where the flow rate of the gas to be treated may vary at any time within classifications of the multiple flow rate ranges. Thus, it is possible to improve the total operational efficiency and stability of the apparatus. Moreover, since this CO 2  recovery process controls the operation conditions on the basis of the CO 2  flow rates calculated on the basis of the CO 2  concentration in the gas to be treated, it is possible to further improve the total operational efficiency and stability of the apparatus. 
         [0018]    In the CO 2  recovery process of the invention, it is preferable that the set load values are kept substantially constant within the multiple flow rate ranges and thereby the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower are controlled. By virtue of this process, the CO 2  recovery process can keep the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower substantially constant, even if the flow rate or the like of the gas to be treated may vary at any time within the multiple flow rate ranges. Accordingly, since the CO 2  recovery process can make the variations of the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower small, it is possible to further improve the total operational efficiency and stability of the apparatus. 
         [0019]    In the CO 2  recovery process of the invention, it is preferable that the set load values are kept at maximum values corresponding to the flow rate ranges within the multiple flow rate ranges and thereby the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower are controlled. By virtue of this process, the CO 2  recovery process can control the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower, according to the set maximum load values within the flow rate ranges. Thus, even in a case where the flow rate of the gas to be treated varies within the flow rate ranges, it is possible to appropriately control the flow rate of the CO 2  absorbing liquid supplied to the CO 2  absorption tower and the flow rate of the steam supplied to the CO 2  absorbing liquid regeneration tower. 
         [0020]    In the CO 2  recovery process of the invention, it is preferable that there are 7 or less classifications in the multiple flow rate ranges. By virtue of this process, the number of the flow rate ranges is in a moderate range. Thus, it is possible to further improve the total operational efficiency and stability of the apparatus. 
       Advantageous Effects of Invention 
       [0021]    According to the invention, it is possible to realize the CO 2  recovery apparatus and the CO 2  recovery process that can improve the total operational efficiency and stability of the apparatus even in a case where the treatment amount of a gas to be treated varies. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0022]      FIG. 1  is a schematic view of a CO 2  recovery apparatus related to a first embodiment. 
           [0023]      FIG. 2  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus related to the first embodiment and changes in exhaust gas flow rate. 
           [0024]      FIG. 3  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus related to the first embodiment and set load values of the CO 2  recovery apparatus. 
           [0025]      FIG. 4  is a flowchart of the operation control of the CO 2  recovery apparatus related to the first embodiment. 
           [0026]      FIG. 5  is a schematic view of a CO 2  recovery apparatus related to a second embodiment. 
           [0027]      FIG. 6  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus related to the second embodiment and changes in CO 2  flow rate. 
           [0028]      FIG. 7  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus related to the second embodiment and set load values of the CO 2  recovery apparatus. 
           [0029]      FIG. 8  is a flowchart of the operation control of the CO 2  recovery apparatus related to the second embodiment. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0030]    The present inventors have paid their attention to the fact that, in the related-art CO 2  recovery apparatuses, operation conditions cannot be necessarily and sufficiently optimized with respect to load variations of a boiler or the like even if the flow rates or the like of an exhaust gas supplied to a CO 2  absorption tower are measured and the operation control off the CO 2  recovery apparatuses is performed. Also, the present inventors have found out that total operational efficiency and stability of the apparatuses are improved by classifying the treatment amounts of the exhaust gas into multiple ranges, setting set load values to the classified ranges in advance, and stepwisely performing operation control, even in cases where load variations of the boiler or the like have occurred, and have completed the invention. 
         [0031]    Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings. In addition, the invention is not limited to the following embodiments, can be appropriately changed and carried out. Additionally, the configurations of CO 2  recovery apparatuses related to the following respective embodiments can be appropriately combined and carried out. 
       First Embodiment 
       [0032]      FIG. 1  is a schematic view of a CO 2  recovery apparatus related to a first embodiment of the invention. As illustrated in  FIG. 1 , the CO 2  recovery apparatus  1  is an apparatus that absorbs CO 2  in an exhaust gas (a gas to be treated)  11 A containing CO 2  exhausted from industrial facilities, such as a boiler and a gas turbine, and recovers a high-concentration CO 2  gas. The CO 2  recovery apparatus  1  includes a cooling tower  12  that cools the exhaust gas  11 A containing CO 2  exhausted from industrial facilities, such as a boiler and a gas turbine; a CO 2  absorption tower  14  that is provided in a subsequent stage of the cooling tower  12 , brings the cooled exhaust gas  11 A into contact with a CO 2  absorbing liquid  13 , and makes the CO 2  absorbing liquid  13  absorb and remove CO 2  in the exhaust gas  11 A; and a CO 2  absorbing liquid regeneration tower  15  that is provided in the subsequent stage of the CO 2  absorption tower  14 , releases CO 2  from the CO 2  absorbing liquid  13  that has absorbed the CO 2 , and regenerates CO 2  absorbing liquid  13  is provided. 
         [0033]    Additionally, the CO 2  recovery apparatus  1  includes a flowmeter (flow rate measuring unit)  101  that is provided in a flue  16  between the cooling tower  12  and the CO 2  absorption tower  14 , and measures the flow rates of the exhaust gas  11 A introduced into the CO 2  absorption tower  14 , and a control unit  102  that classifies the flow rates of the exhaust gas  11 A measured by the flowmeter  101  into multiple flow rate ranges, and controls the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 , on the basis of set load values that are preset according to the multiple flow rate range classifications. The control unit  102  can be realized, for example, using a general-purpose computer or an exclusive computer, such as a central arithmetic unit (CPU), a read-only memory (ROM), or a random access memory (RAM), and programs that operate on this computer. 
         [0034]    In the CO 2  recovery apparatus  1 , the CO 2  absorbing liquid  13  circulates between the CO 2  absorption tower  14  and the CO 2  absorbing liquid regeneration towers  15 . The CO 2  absorbing liquid  13  (lean solution) is supplied to the CO 2  absorbing liquid regeneration tower  15  as the CO 2  absorbing liquid  13  (rich solution) that has absorbed CO 2  in the CO 2  absorption tower  14 . Additionally, the CO 2  absorbing liquid  13  (rich solution) is supplied to the CO 2  absorption tower  14  as the CO 2  absorbing liquid  13  (lean solution) from which substantially all CO 2  has been removed and regenerated in the CO 2  absorbing liquid regeneration tower  15 . 
         [0035]    The cooling tower  12  has a cooling section  121  that cools the exhaust gas  11 A. A circulation line L 1  is provided between a bottom part of the cooling tower  12  and a top part of the cooling section  121 . A heat exchanger  122  that cools cooling water W 1 , and a circulation pump  123  circulate the cooling water W 1  within the circulation line L 1  are provided in the circulation line L 1 . 
         [0036]    In the cooling section  121 , the exhaust gas  11 A is cooled by bringing the exhaust gas  11 A into countercurrent contact with the cooling water W 1 . The heat exchanger  122  cools the cooling water W 1  heated by the heat exchange with the exhaust gas  11 A. The circulation pump  123  supplies the cooling water W 1 , which has flowed down the bottom part of the cooling tower  12 , to the top part of the cooling section  121  via the heat exchanger  122 . 
         [0037]    The CO 2  absorption tower  14  includes a CO 2  absorption section  141  that is provided on a lower part side of the CO 2  absorption tower  14  and has the exhaust gas  11 A and the CO 2  absorbing liquid  13  (lean solution) cooled in the cooling tower  12  supplied thereto, a main washing section  142  that is provided on an upper part side of the CO 2  absorption tower  14 , and a preliminary washing section  143  that is provided between and the CO 2  absorption section  141  and the main washing section  142 . A liquid storage section  144  that stores washing water W 2  for cleaning an exhaust gas  11 C from which CO 2  has been removed is provided at a bottom part of the main washing section  142 . A circulation line L 2 , through which the washing water W 2 , containing the CO 2  absorbing liquid  13  recovered in the liquid storage section  144 , is supplied and circulated from a top part side of the main washing section  142 , is provided between the liquid storage section  144  and an upper part of the main washing section  142 . The circulation line L 2  is provided with a heat exchanger  21  that cools the washing water W 2 , and a circulation pump  22  that circulates the washing water W 2 , containing the CO 2  absorbing liquid  13  recovered in the liquid storage section  144 , within the circulation line L 2  via the heat exchanger  21 . Additionally, the circulation line L 2  is provided with an extraction line L 3  through which a portion of the washing water W 2  (washing water W 3 ) is extracted and supplied to the preliminary washing section  143 . The extraction line L 3  is provided with an adjusting valve  23  that adjusts the amount of supply of washing water W 3  supplied to the preliminary washing section  143 , and a heat exchanger  24  that cools the washing water W 3  to a predetermined temperature. 
         [0038]    In the CO 2  absorption section  141 , the exhaust gas  11 A containing CO 2  and the CO 2  absorbing liquid  13  containing alkanolamine or the like come into countercurrent contact with each other. Accordingly, CO 2  in the exhaust gas  11 A is absorbed by the CO 2  absorbing liquid  13  through a chemical reaction shown in the following Formula. As a result, the exhaust gas  11 A containing CO 2  becomes an exhaust gas  11 B from which CO 2  has been removed by passing through the CO 2  absorption section  141 . 
         [0000]      R—NH 2 +H 2 O+CO 2 →R—NH 3 HCO 3  
 
         [0039]    In the preliminary washing section  143 , the exhaust gas  11 B from which CO 2  has been removed is brought into gas-liquid contact with the washing water W 3  extracted from the main washing section  142 , and is cleaned. As a result, the exhaust gas  11 B from which CO 2  has been removed becomes the exhaust gas  11 C in which the CO 2  absorbing liquid  13  entrained in the exhaust gas  11 B has decreased. 
         [0040]    In the main washing section  142 , the exhaust gas  11 C from which CO 2  that has passed through the preliminary washing section  143  has been removed rises via a chimney tray  145 . Then, the exhaust gas  11 C is brought into gas-liquid contact with the washing water W 2  supplied from the top part side of the main washing section  142 , and becomes an exhaust gas  11 D from which the CO 2  absorbing liquid  13  entrained in the exhaust gas  11 C has been recovered by circulation cleaning. The exhaust gas  11 D is exhausted to the outside from a tower top part  14   a  of the CO 2  absorption tower  14  after mist in the gas is trapped by a mist eliminator  146 . 
         [0041]    A rich solution supply tube  50  through which the CO 2  absorbing liquid  13  (rich solution), which has absorbed CO 2  in the CO 2  absorption tower  14 , is supplied to an upper part side of the CO 2  absorbing liquid regeneration tower  15  is provided between a tower bottom part  14   b  of the CO 2  absorption tower  14  and an upper part of the CO 2  absorbing liquid regeneration tower  15 . The rich solution supply tube  50  is provided with a rich solvent pump  51  that supplies the CO 2  absorbing liquid  13  (rich solution), which has absorbed CO 2  in the CO 2  absorption tower  14 , toward the CO 2  absorbing liquid regeneration tower  15 , and a rich-lean solution heat exchanger  52  that heats the CO 2  absorbing liquid  13  (rich solution) that has absorbed CO 2 , using the CO 2  absorbing liquid  13  (lean solution) which has been heated with steam and from which CO 2  has been removed. 
         [0042]    A central part of the CO absorbing liquid regeneration tower  15  is provided with a CO 2  absorbing liquid supply section  151  to which the CO 2  absorbing liquid  13  that has absorbed CO 2  is supplied. A tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  is provided with a circulation line L 4  through which the CO 2  absorbing liquid  13  that has flowed down to the tower bottom part  15   b  circulates. The circulation line L 4  is provided with a regenerative heater  31  that heats the CO 2  absorbing liquid  13  with saturated steam S, an adjusting valve  32  that adjusts the amount of saturated steam S supplied to the regenerative heater  31 , and a circulation pump  33  that supplies the CO 2  absorbing liquid  13  of the tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  to a lower part of the CO 2  absorbing liquid supply section  151  of the CO 2  absorbing liquid regeneration tower  15  via the regenerative heater  31 . The adjusting valve  32  is adjusted in opening degree by the control unit  102 , and adjusts the amount of the saturated steam S supplied to the regenerative heater  31 . 
         [0043]    A tower top part  15   a  of the CO 2  absorbing liquid regeneration tower  15  is provided with a gas exhaust line L 5  through which a CO 2  gas  41  accompanied by steam is exhausted. The gas exhaust line L 5  is provided with a condenser  42  that condenses moisture in the CO 2  gas  41 , and a separation drum  43  that separates the CO 2  gas  41  from condensed water W 5 . A CO 2  gas  44  from which the condensed water W 5  has been separated is released to the outside from an upper part of the separation drum  43 . A condensed water line L 6  through which the condensed water W 5  separated by the separation drum  43  is supplied to the upper part of the CO 2  absorbing liquid regeneration tower  15  is provided between a bottom part of the separation drum  43  and the upper part of the CO 2  absorbing liquid regeneration tower  15 . The condensed water line L 6  is provided with a condensed water circulation pump  45  that supplies the condensed water W 5  separated by the separation drum  43  to the upper part of the CO 2  absorbing liquid regeneration tower  15 . 
         [0044]    Additionally, the tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  and an upper part of the CO 2  absorption section  141  of the CO 2  absorption tower  14  are provided with a lean solution supply tube  53  through which a lean solution in the tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  is supplied to the upper part of the CO 2  absorption section  141 . The lean solution supply tube  53  is provided with the rich-lean solution heat exchanger  52  that heats the CO 2  absorbing liquid  13  (rich solution), which has absorbed CO 2 , using the CO 2  absorbing liquid  13  (lean solution) which has been heated with steam and from which CO 2  has been removed, a lean solution pump  54  that supplies the lean solution in the tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  to the upper part of the CO 2  absorption section  141 , and a cooling section  55  that cools the CO 2  absorbing liquid  13  (lean solution) to a predetermined temperature. In the lean solution pump  54 , the amount of supply of the CO 2  absorbing liquid  13  (lean solution) is controllable by the control unit  102 . 
         [0045]    Next, the control of the operation conditions of the CO 2  recovery apparatus  1  related to the present embodiment will be described below with reference to  FIGS. 2 and 3 .  FIG. 2  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus  1  related to the present embodiment and changes in exhaust gas flow rate, and  FIG. 3  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus  1  related to the present embodiment and the set load values of the CO 2  recovery apparatus  1 . 
         [0046]    As illustrated in  FIG. 2 , in the CO 2  recovery apparatus  1  related to the present embodiment, for example, the flow rate of an exhaust gas exhausted from industrial facilities, such as a boiler and a gas turbine varies depending on variations or the like of generated electric power accompanied by changes in electric power demand. In the CO 2  recovery apparatus  1  related to the present embodiment, for example, as illustrated in  FIG. 2 , the exhaust gas flow rate varies at any time within a range of 70 or more and 100 or less with the lapse of time. Here, for example, in a case where the exhaust gas flow rate greatly varies within a range of 70 to 100 like within a time range of 0 or more and 1 or less illustrated in  FIG. 2 , the control unit  102  is able to increase the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14 , and increase the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 , thereby optimize the operation conditions. However, in a case where the exhaust gas flow rate varies on a small scale at any time within a range of 90 or more and 100 or less like within a time range of 3 or more and 4 or less illustrated in  FIG. 2 , even if the operation conditions are finely controlled, operation conditions after a change may not be reflected on variations of an actual exhaust gas flow rate, and sufficient operation control may not be able to be performed. 
         [0047]    Therefore, in the present embodiment, the exhaust gas flow rates per unit time measured by the flowmeter  101  are classified into multiple flow rate ranges R 1  to R 7  (R 4  to R 7  are not illustrated) that are set in advance. For example, in the example illustrated in  FIG. 2 , the control unit  102  classifies the exhaust gas flow rates as seven stages having a range where the exhaust gas flow rates of the exhaust gas  11 A measured by the flowmeter  101  are more than 90 and 100 or less as a flow rate range R 1 , a range where the exhaust gas flow rates are more than 80 and 90 or less as a flow rate range R 2 , a range where the exhaust gas flow rates are more than 70 and 80 or less as a flow rate range R 3 , a range where the exhaust gas flow rates are more than 60 and 70 or less as a flow rate range R 4 , a range where the exhaust gas flow rates are more than 50 and 60 or less as a flow rate range R 5 , a range where the exhaust gas flow rate are more than 40 and 50 or less as a flow rate range R 6 , and a range where the exhaust gas flow rates are more than zero and 40 or less as a flow rate range R 7 . 
         [0048]    Also, the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  on the basis of the set load values that are preset according to the flow rate ranges R 1  to R 7  classified into the seven stages, and controls the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 . In addition, the set load values herein are, for example, the specific flow rates of the lean solution pump  54  and the specific opening degrees of the adjusting valve  32  that are preset according to the flow rate ranges R 1  to R 7 . 
         [0049]    In a case where the exhaust gas flow rate is the flow rate range R 1 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 6 or more and 7 or less, and controls the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 . Similarly, in a case where the exhaust gas flow rate is the flow rate range R 2 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 5 or more and 6 or less. 
         [0050]    In a case where the exhaust gas flow rate is the flow rate range R 3 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 4 or more and 5 or less. In a case where the exhaust gas flow rate is the flow rate range R 4 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 3 or more and 4 or less. 
         [0051]    In a case where the exhaust gas flow rate is the flow rate range R 5 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 2 or more and 3 or less. In a case where the exhaust gas flow rate is the flow rate range R 6 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 1 or more and 2 or less. 
         [0052]    In a case where the exhaust gas flow rate is the flow rate range R 7 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are more than 0 and 1 or less. As the control unit  102  controls the operation condition of the CO 2  recovery apparatus  1  in this way, it is possible to appropriately control the operation conditions over variations of the actual exhaust gas flow rate even in a case where the exhaust gas flow rate varies on a small scale at any time within a range of the flow rate ranges R 1  to R 7 . In addition, the control unit  102  may appropriately change the set load values to control operation according to elapsed time as long as it is within a range of the set load values corresponding to the range of the flow rate ranges R 1  to R 7 . 
         [0053]    Additionally, in the CO 2  recovery apparatus  1  related to the present embodiment, it is preferable that the control unit  102  keeps the set load values substantially constant to control the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the saturated steam S supplied to the CO 2  absorbing liquid regeneration tower  15 , within the above-described multiple flow rate ranges R 1  to R 7 . For example, as illustrated at the times  3  to  4  of  FIGS. 2 and 3 , the set load value is kept at  7  in a case where the exhaust gas flow rate is in the flow rate range R 1 . Accordingly, even if the flow rate or the like of the exhaust gas  11 A varies within the flow rate range R 1 , it is possible to keep the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the saturated steam S supplied to the CO 2  absorbing liquid regeneration tower  15  substantially constant. Accordingly, since the variations of the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15  can be made small, it is possible to improve the total operational efficiency and stability of the apparatus. 
         [0054]    Moreover, in the CO 2  recovery apparatus  1  related to the present embodiment, it is preferable that the control unit  102  keeps the set load values at maximum values corresponding to the flow rate ranges R 1  to R 7  to control the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15 , within the multiple flow rate ranges R 1  to R 7 . For example, as illustrated at the times  3  to  4  of  FIGS. 2 and 3 , in a case where the exhaust gas flow rate is in the flow rate range R 1 , the set load value is kept at  7  that is a maximum value of 6 or more and 7 or less corresponding to the flow rate range R 1 . Accordingly, the operation conditions of the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the saturated steam S supplied to the CO 2  absorbing liquid regeneration tower  15 , according to the set maximum load values within the flow rate ranges R 1  to R 7 , can be controlled. Thus, even in a case where the flow rate of the exhaust gas  11 A varies within the flow rate ranges R 1  to R 7 , it is possible to appropriately control the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15 . 
         [0055]    Additionally, in the CO 2  recovery apparatus  1  related to the present embodiment, it is preferable that the control unit  102  classifies the flow rate ranges of the exhaust gas flow rates of the exhaust gas  11 A to be set in advance into the seven stages. Accordingly, since the number of the flow rate ranges R 1  to R 7  to be set in advance is in a moderate range, it is possible to improve the total operational efficiency and stability of the CO 2  recovery apparatus  1 . In addition, the flow rate ranges of the exhaust gas flow rates are not limited to the seven stages, and the exhaust gas flow rates may be classified into seven stages or more, or less than seven stages. 
         [0056]    Next, the overall operation of the CO 2  recovery apparatus  1  related to the present embodiment will be described with reference to  FIG. 4 .  FIG. 4  is a flowchart of the operation control of the CO 2  recovery apparatus  1  related to the present embodiment. As illustrated in  FIG. 4 , in the CO 2  recovery apparatus  1  related to the present embodiment, the flowmeter  101  measures the exhaust gas flow rates of the exhaust gas  11 A introduced into the CO 2  absorption tower  14  (Step S 11 ), and the control unit  102  classifies the exhaust gas flow rates detected by the flowmeter  101  into the preset flow rate ranges, and calculates the set load value according to the classified flow rate ranges (Step S 12 ). Then, the control unit  102  calculates the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15  according to the set load values (Step S 13 ), and adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  so that the calculated flow rates are obtained (Step S 14 ). 
         [0057]    The exhaust gas  11 A containing CO 2  exhausted from industrial facilities, such as a boiler and a gas turbine, is introduced into the cooling tower  12 , and is brought into countercurrent contact with and cooled by the cooling water W 1 . The cooled exhaust gas  11 A is introduced into the CO 2  absorption tower  14  via the flue  16 , and the flow rates of the exhaust gas  11 A introduced into the CO 2  absorption tower  14  are measured. The exhaust gas  11 A introduced into the CO 2  absorption tower  14  is brought into countercurrent contact with and cooled by the CO 2  absorbing liquid  13  containing alkanolamine or the like in the CO 2  absorption section  141 , and becomes the exhaust gas  11 B from which CO 2  in the exhaust gas  11 A has been absorbed by the CO 2  absorbing liquid  13  and CO 2  has been removed. 
         [0058]    The exhaust gas  11 B from which CO 2  has been removed is brought into gas-liquid contact with and cleaned by the washing water W 3 , which is a portion of the washing water W 2  extracted from the main washing section  142 , in the preliminary washing section  143 , and becomes the exhaust gas  11 C in which the CO 2  absorbing liquid  13  entrained in the exhaust gas  11 B has decreased. The exhaust gas  11 C rises via the chimney tray  145 , is brought into gas-liquid contact with the washing water W 2  supplied from the top part side of the main washing section  142 , and becomes the exhaust gas  11 D from which the CO 2  absorbing liquid  13  entrained in the exhaust gas  11 C has been recovered by circulation cleaning. The exhaust gas  11 D is exhausted to the outside from the tower top part  14   a  of the CO 2  absorption tower  14  after mist in the gas is trapped by a mist eliminator  146 . 
         [0059]    The CO 2  absorbing liquid  13  (rich solution) that has absorbed CO 2  in the CO 2  absorption tower  14  is supplied to the upper part of the CO 2  absorbing liquid regeneration tower  15  by the rich solvent pump  51  after being heat-exchanged with the CO 2  absorbing liquid  13  (lean solution) in the rich-lean solution heat exchanger  52  via the rich solution supply tube  50 . The CO 2  absorbing liquid  13  supplied to the CO 2  absorbing liquid regeneration tower  15  has CO 2  removed therefrom and becomes a semi-lean solution, while flowing down to the tower bottom part  15   b  via the CO 2  absorbing liquid supply section  151 . This semi-lean solution while is circulates through the circulation line L 4  by the circulation pump  33 , is heated by the saturated steam S in the regenerative heater  31 , and becomes a lean solution. Here, the control unit  102  controls the opening degree of the adjusting valve  32  so that the amount of supply of the saturated steam S is obtained on the basis of set load values according to the flow rate ranges of the exhaust gas flow rates of the exhaust gas  11 A measured by the flowmeter  101 . The saturated steam S after being heated becomes the steam condensed water W 4 . The CO 2  gas  41  removed from the CO 2  absorbing liquid  13  is released to the outside as the CO 2  gas  44  from which the condensed water W 5  has been separated through the upper part of the separation drum  43  after the moisture thereof is condensed by the condenser  42 . 
         [0060]    The CO 2  absorbing liquid  13  (lean solution) of the tower bottom part  15   b  of the CO 2  absorbing liquid regeneration tower  15  is supplied to the upper part of the CO 2  absorption section  141  of the CO 2  absorption tower  14  by the lean solution pump  54  after being heat-exchanged with the CO 2  absorbing liquid  13  (rich solution) by the rich-lean solution heat exchanger  52  via the lean solution supply tube  53 . Here, the control unit  102  controls the flow rate of the lean solution pump  54  on the basis of the set load values according to the flow rate ranges R 1  to R 7  of the exhaust gas flow rates of the exhaust gas  11 A measured by the flowmeter  101 . 
         [0061]    As described above, according to the present embodiment, even in a case where the flow rate of the exhaust gas  11 A increases or decreases within classifications of the multiple flow rate ranges R 1  to R 7 , it is possible to maintain the operation conditions on the basis of the set load values corresponding to the flow rate ranges R 1  to R 7 . Accordingly, in the CO 2  recovery apparatus, even in a case where the flow rate of the exhaust gas  11 A may vary at any time within classifications of the multiple flow rate ranges R 1  to R 7 , the variations of the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15  can be made small. Thus, it is possible to improve the total operational efficiency and stability of the apparatus. 
         [0062]    In addition, an example in which the exhaust gas  11 A containing CO 2  exhausted from industrial facilities, such as a boiler and a gas turbine, is treated by the CO 2  absorbing liquid  13  has been described in the above-described embodiment. However, as gases to be treated that is treated by the CO 2  absorbing liquid  13 , various gases can be applied if they are gases containing CO 2 . 
       Second Embodiment 
       [0063]    Next, a second embodiment of the invention will be described. In addition, constituent elements common to those of the CO 2  recovery apparatus  1  related to the above-described first embodiment will be designated by the same reference signs, and duplication of description thereof will be avoided. 
         [0064]      FIG. 5  is a schematic view of a CO 2  recovery apparatus  2  related to a second embodiment of the invention. A CO 2  recovery apparatus  2  related to the present embodiment includes a CO 2  concentration meter (CO 2  concentration measuring unit)  103  that measures CO 2  concentration in the exhaust gas  11 A, in the flue  16 , in addition to the configuration of the CO 2  recovery apparatus  1  related to the above-described first embodiment. The control unit  102  obtains CO 2  flow rates in the exhaust gas  11 A, on the basis of the exhaust gas flow rates of the exhaust gas  11 A measured by the flowmeter  101  and the CO 2  concentration in the exhaust gas  11 A measured by a CO 2  concentration meter  103 . The CO 2  concentration meter  103  is not particularly limited if the CO 2  concentration in the exhaust gas  11 A can be measured. 
         [0065]    Next, the control of the operation conditions of the CO 2  recovery apparatus  2  related to the present embodiment will be described below with reference to  FIGS. 6 and 7 .  FIG. 6  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus  2  related to the present embodiment and changes in CO 2  flow rate, and  FIG. 7  is a view illustrating the relationship between the operation time of the CO 2  recovery apparatus  2  related to the present embodiment and the set load values of the CO 2  recovery apparatus  2 . 
         [0066]    As illustrated in  FIG. 6 , in the present embodiment, the control unit  102  calculates CO 2  flow rates on the basis of the exhaust gas flow rates of the exhaust gas  11 A measured by the flowmeter  101  and the CO 2  concentration of the exhaust gas  11 A measured by the CO 2  concentration meter  103 , and classifies the calculated CO 2  flow rates into multiple flow rate ranges R 11  to R 17  (R 14  to R 17  are not illustrated). For example, in the example illustrated in  FIG. 6 , the control unit  102  classifies the CO 2  flow rates as seven stages having a range where the CO 2  flow rates of the exhaust gas  11 A measured by the flowmeter  101  are more than 90 and 100 or less as a flow rate range R 11 , a range where the CO 2  flow rates are more than 80 and 90 or less as a flow rate range R 12 , a range where the CO 2  flow rates are more than 70 and 80 or less as a flow rate range R 13 , a range where the CO 2  flow rates are more than 60 and 70 or less as a flow rate range R 14 , a range where the CO 2  flow rates are more than 50 and 60 or less as a flow rate range R 15 , a range where the CO 2  flow rates are more than 40 and 50 or less as a flow rate range R 16 , a range where the CO 2  flow rates are more than zero and 40 or less as a flow rate range R 17  in advance. 
         [0067]    Also, the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  within a range of the set load values that are preset according to the flow rate ranges R 11  to R 17  classified into the seven stages, and controls the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 . In addition, the set load values herein are, for example, the specific flow rates of the lean solution pump  54  and the specific opening degrees of the adjusting valve  32  that are preset according to the flow rate ranges R 11  to R 17 . 
         [0068]    In a case where the CO 2  flow rates are in the flow rate range R 11 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 6 or more and 7 or less, and controls the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of steam supplied to the CO 2  absorbing liquid regeneration tower  15 . Similarly, in a case where the CO 2  flow rates are in the flow rate range R 12 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 5 or more and 6 or less. 
         [0069]    Additionally, in a case where the CO 2  flow rates are in the flow rate range R 13 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  so that the preset load value of the CO 2  recovery apparatus  2  is within a range of 4 or more and 5 or less. In a case where the CO 2  flow rates are in the flow rate range R 14 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 3 or more and 4 or less. 
         [0070]    Moreover, in a case where the CO 2  flow rates are in the flow rate range R 15 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 2 or more and 3 or less. In a case where the CO 2  flow rates are in the flow rate range R 16 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 1 or more and 2 or less. 
         [0071]    Additionally, in a case where the CO 2  flow rates are in the flow rate range R 17 , the control unit  102  adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  in a range where the preset load values are 0 or more and 1 or less. As the control unit  102  controls the operation condition of the CO 2  recovery apparatus  2  in this way, it is possible to appropriately control the operation conditions over variations of the actual CO 2  flow rates even in a case where the CO 2  flow rates vary on a small scale at any time within a range of the flow rate ranges R 11  to R 17 . In addition, the control unit  102  may appropriately change the set load values to control operation according to elapsed time as long as the exhaust gas flow rate is within a range of the set load values corresponding to the range of the flow rate ranges R 11  to R 17 . 
         [0072]    Next, the overall operation of the CO 2  recovery apparatus  2  related to the present embodiment will be described with reference to  FIG. 8 .  FIG. 8  is a flowchart of the operation control of the CO 2  recovery apparatus  2  related to the present embodiment. As illustrated in  FIG. 8 , in the CO 2  recovery apparatus  2  related to the present embodiment, the flowmeter  101  measures the exhaust gas flow rates of the exhaust gas  11 A introduced into the CO 2  absorption tower  14 , and the CO 2  concentration meter  103  measures CO 2  concentration in the exhaust gas  11 A (Step S 21 ). Next, the control unit  102  obtains CO 2  flow rates per unit time, on the basis of the measured exhaust gas flow rates and CO 2  concentration of the exhaust gas  11 A (Step S 22 ). Next, the control unit  102  classifies the obtained CO 2  flow rates into preset flow rate ranges, and calculates set load values according to the classified flow rate ranges (Step S 23 ). Then, the control unit  102  calculates the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15  according to the set load values (Step S 24 ), and adjusts the flow rate of the lean solution pump  54  and the opening degree of the adjusting valve  32  so that the calculated flow rates are obtained (Step S 25 ). 
         [0073]    As described above, according to the present embodiment, the control unit  102  performs operation control, on the basis of the CO 2  flow rates obtained by measuring the flow rates of the exhaust gas  11 A and the CO 2  concentration in the exhaust gas  11 A. Thus, the flow rate of the CO 2  absorbing liquid  13  supplied to the CO 2  absorption tower  14  and the flow rate of the steam S supplied to the CO 2  absorbing liquid regeneration tower  15  can be more precisely controlled. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               1 ,  2 : CO 2  RECOVERY APPARATUS 
               11 A,  11 B,  11 C,  11 D: EXHAUST GAS 
               12 : COOLING TOWER 
               121 : COOLING SECTION 
               122 : HEAT EXCHANGER 
               123 : CIRCULATION PUMP 
               13 : CO 2  ABSORBING LIQUID 
               14 : CO 2  ABSORPTION TOWER 
               14   a : TOWER TOP PART 
               14   b : TOWER BOTTOM PART 
               141 : CO 2  ABSORPTION SECTION 
               142 : MAIN WASHING SECTION 
               143 : PRELIMINARY WASHING SECTION 
               144 : LIQUID STORAGE SECTION 
               145 : CHIMNEY TRAY 
               146 : MIST ELIMINATOR 
               15 : CO 2  ABSORBING LIQUID REGENERATION TOWER 
               15   a : TOWER TOP PART 
               151 : CO 2  ABSORBING LIQUID SUPPLY SECTION 
               16 : FLUE 
               21 : HEAT EXCHANGER 
               22 : CIRCULATION PUMP 
               23 : ADJUSTING VALVE 
               24 : HEAT EXCHANGER 
               31 : REGENERATIVE HEATER 
               32 : ADJUSTING VALVE 
               33 : CIRCULATION PUMP 
               41 ,  44 : CO 2  GAS 
               42 : CONDENSER 
               43 : SEPARATION DRUM 
               45 : CONDENSED WATER CIRCULATION PUMP 
               50 : RICH SOLUTION SUPPLY TUBE 
               51 : RICH SOLVENT PUMP 
               52 : RICH-LEAN SOLUTION HEAT EXCHANGER 
               53 : LEAN SOLUTION SUPPLY TUBE 
               54 : LEAN SOLUTION PUMP 
               55 : COOLING SECTION 
               101 : FLOWMETER 
               102 : CONTROL UNIT 
               103 : CO 2  CONCENTRATION METER 
             L 1 , L 2 , L 4 : CIRCULATION LINE 
             L 3 : EXTRACTION LINE 
             L 5 : GAS EXHAUST LINE 
             L 6 : CONDENSED WATER LINE 
             S: SATURATED STEAM 
             W 1 : COOLING WATER 
             W 2 , W 3 : WASHING WATER 
             W 4 : STEAM CONDENSED WATER 
             W 5 : CONDENSED WATER