JP2014200774A - Carbon dioxide recovery system and method of operating the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carbon dioxide recovery system and a method of operating the carbon dioxide recovery system that can continue a stable operation even when a carbon dioxide concentration and a gas flow rate of processing object gas are rapidly changed.SOLUTION: A carbon dioxide recovery system in one embodiment includes: an absorption tower for making processing object gas including carbon dioxide and an absorbent for absorbing the carbon dioxide come into contact with each other; and a regeneration tower for dissipating the carbon dioxide from the absorbent that is discharged from the absorption tower. The system further includes a processing object gas line for introducing the processing object gas to the absorption tower. The system further includes a first introduction mechanism for introducing first gas having a carbon dioxide concentration higher than that of the processing object gas to the processing object gas line. In addition, the system includes a second introduction mechanism for introducing second gas having a carbon dioxide concentration lower than that of the processing object gas to the processing object gas line.

Description

  Embodiments described herein relate generally to a carbon dioxide recovery system and an operation method thereof.

In recent years, carbon dioxide capture and storage (CCS) technology has attracted attention as an effective measure against the global warming problem. For example, a carbon dioxide recovery system that recovers carbon dioxide in process exhaust gas (processing target gas) generated at a thermal power plant, a steel mill, or the like with an absorbing solution has been studied.
In such a carbon dioxide recovery system, if the boiler load fluctuates due to operational changes such as thermal power plants or steelworks, or if there is a change in the air supply amount or fuel supply amount, the CO2 in the process exhaust gas supplied Carbon concentration and gas flow rate change abruptly. However, the conventional carbon dioxide recovery system cannot cope with these sudden changes by changing the process conditions on the carbon dioxide recovery system side, so the carbon dioxide recovery system becomes unstable or abnormally heated. Resulting in.

JP2013-000729A JP 2010-240629 A

  Therefore, the problem to be solved by the present invention is to provide a carbon dioxide recovery system capable of continuing stable operation even when the carbon dioxide concentration or gas flow rate of the gas to be treated changes rapidly, and an operation method thereof. is there.

  In the carbon dioxide recovery system according to one embodiment, a gas to be treated containing carbon dioxide is brought into contact with an absorption liquid for absorbing the carbon dioxide, and the absorption liquid that has absorbed the carbon dioxide and the carbon dioxide are in contact with each other. An absorption tower for discharging the absorption tower exhaust gas containing the removed gas to be treated is provided. Furthermore, the system is configured to dissipate the carbon dioxide from the absorption liquid discharged from the absorption tower, and to discharge the absorption liquid from which the carbon dioxide has been released and a regeneration tower exhaust gas containing the carbon dioxide. Is provided. Furthermore, the system includes a processing target gas line for introducing the processing target gas into the absorption tower. Furthermore, the system includes a first introduction mechanism that introduces a first gas having a higher carbon dioxide concentration than the processing target gas into the processing target gas line. Furthermore, the system includes a second introduction mechanism that introduces a second gas having a lower carbon dioxide concentration than the processing target gas into the processing target gas line.

It is the schematic which shows the structure of the carbon dioxide collection system of 1st Embodiment. It is the schematic which shows the structure of the carbon dioxide collection system of 2nd Embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram showing the configuration of the carbon dioxide recovery system of the first embodiment.

  The carbon dioxide recovery system of FIG. 1 includes an absorption tower 11, a process exhaust gas line 12, which is an example of a gas line to be processed, a blower 13, a rich liquid pump 14, a regeneration heat exchanger 15, a regeneration tower 16, A reboiler 17, a lean liquid pump 18, and a cooler 19 are provided.

  The absorption tower 11 is constituted by, for example, a counter-current gas-liquid contact device, from which a process exhaust gas 1 containing carbon dioxide is introduced, and from the upper part, an absorption liquid (lean liquid) for absorbing carbon dioxide is introduced. ) 2 is introduced.

  The absorption tower 11 brings the process exhaust gas 1 and the absorption liquid 2 into gas-liquid contact, discharges the absorption liquid (rich liquid) 2 that has absorbed carbon dioxide from the lower part thereof, and removes carbon dioxide from the upper part. Absorption tower exhaust gas 3 containing the processed process exhaust gas 1 is discharged.

  The absorption tower 11 of this embodiment has a structure in which one or more packings or trays are arranged in order to promote gas-liquid contact efficiently.

  The process exhaust gas 1 is introduced into the absorption tower 11 via the process exhaust gas line 12. At this time, the process exhaust gas 1 is pressurized to an arbitrary pressure by the blower 13 on the process exhaust gas line 12. The process exhaust gas 1 is an example of the processing target gas of the present disclosure, and is supplied from, for example, a thermal power plant or a steel mill.

  The absorbing liquid 2 is, for example, an amine aqueous solution such as monoethanolamine or diethanolamine, an alkaline aqueous solution, an ionic liquid or an aqueous solution thereof, but is not limited thereto.

  The absorbent 2 discharged from the absorption tower 11 is transferred to the regeneration tower 16 via the regeneration heat exchanger 15 by the rich liquid pump 14. At this time, the absorbing liquid 2 traveling from the absorption tower 11 to the regeneration tower 16 is heated by heat exchange in the regeneration heat exchanger 15.

  The regeneration tower 16 separates carbon dioxide from the absorbing liquid 2 by heating the introduced absorbing liquid 2 to dissipate most of the carbon dioxide from the absorbing liquid 2 together with the vapor. The regeneration tower 16 is constituted by, for example, a countercurrent gas-liquid contact device, and heats the absorbing liquid 2 by exchanging heat between the high-temperature steam that is externally supplied heat and the absorbing liquid 2 in the reboiler 17.

  Then, the regeneration tower 16 discharges the regeneration tower exhaust gas 4 containing carbon dioxide and steam that has been diffused from the upper part thereof, and exhausts the absorbing liquid (lean liquid) 2 from which the carbon dioxide has been diffused from the lower part thereof.

  The regeneration tower 16 of the present embodiment has a structure in which one or more packings or trays are arranged in order to promote gas-liquid contact efficiently.

  The absorbent 2 discharged from the regeneration tower 16 is returned to the absorption tower 11 by the lean liquid pump 18 via the regeneration heat exchanger 15 and the cooler 19. At this time, the absorbing liquid 2 from the regeneration tower 16 toward the absorption tower 11 is cooled by heat exchange in the regeneration heat exchanger 15 and cooling action in the cooler 19.

  The regeneration tower exhaust gas 4 discharged from the regeneration tower 16 differs in the subsequent processing steps depending on the purpose of use, but in general, the water is condensed and removed by cooling. Thereafter, the regeneration tower exhaust gas 4 from which moisture has been removed is transferred to a state according to the purpose of use, such as a supercritical state or a liquid state, by a compression pump, and stored and transported by a tank, lorry, pipeline, or the like.

  The carbon dioxide recovery system in FIG. 1 further includes a measuring instrument 21, a control unit 22, a regeneration tower exhaust gas valve 23, a gas supply unit 24, and a supply gas valve 25.

  The measuring instrument 21 monitors the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 flowing through the process exhaust gas line 12. In FIG. 1, the measuring instrument 21 measures the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 flowing between the blower 13 and the absorption tower 11.

  Based on the measurement values (carbon dioxide concentration and gas flow rate) of the measuring device 21, the control unit 22 opens the regeneration tower exhaust gas valve 23, operates the gas supply unit 24, and opens the supply gas valve 25. Control the degree.

  For example, the control unit 22 can introduce the regeneration tower exhaust gas 4 from the regeneration tower 16 into the process exhaust gas line 12 to be mixed into the process exhaust gas 1 by opening the regeneration tower exhaust gas valve 23. At this time, the control unit 22 can control the introduction amount of the regeneration tower exhaust gas 4 by adjusting the opening degree and opening time of the regeneration tower exhaust gas valve 23. The regeneration tower exhaust gas valve 23 and the regeneration tower 16 are examples of the first introduction mechanism of the present disclosure. The regeneration tower exhaust gas 4 is an example of a first gas having a carbon dioxide concentration higher than that of the gas to be treated.

  Further, the control unit 22 can introduce the supply gas 5 from the gas supply unit 24 into the process exhaust gas line 12 by mixing the process exhaust gas 1 by opening the supply gas valve 25. At this time, the control unit 22 can control the introduction amount of the supply gas 5 by adjusting the opening degree and the opening time of the supply gas valve 25. The supply gas valve 25 and the gas supply unit 24 are examples of the second introduction mechanism of the present disclosure. The supply gas 5 is an example of a second gas having a lower carbon dioxide concentration than the gas to be processed.

  The supply gas 5 is, for example, air, an inert gas, or a mixed gas obtained by mixing air and an inert gas. Examples of the inert gas include nitrogen gas, helium gas, and argon gas.

(1) Control of carbon dioxide concentration and gas flow rate of process exhaust gas 1 Next, control of the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 will be described with reference to FIG.

  The carbon dioxide concentration and gas flow rate of the process exhaust gas 1 depend on the operating state of the discharge source boiler, but show stable behavior if the boiler is in steady operation. However, if there is a change in the boiler load, a change in the air supply amount or the fuel supply amount, a sudden change such as a soot blow, a rapid increase or decrease in the carbon dioxide concentration or gas flow rate of the process exhaust gas 1 occurs.

  The conventional carbon dioxide recovery system can cope with the increase in gas flow rate by reducing the amount of gas introduced into the system by setting the blower or adjusting the adjustment valve. The decrease cannot be handled by the carbon dioxide recovery system.

  In a conventional carbon dioxide recovery system, if a sudden increase or decrease in carbon dioxide concentration or a rapid decrease in gas flow occurs, the plant will be stable even if the carbon dioxide recovery system changes the corresponding process conditions quickly. Takes a long time.

  Therefore, hunting in which carbon dioxide is repeatedly emitted and stopped in the regeneration tower due to abnormal heat generation in the absorption tower, sudden fluctuations in the liquid level of the absorption tower and regeneration tower, sudden fluctuations in pressure in the regeneration tower, etc. The abnormal behavior such as the above may occur, and the carbon dioxide recovery system may fall into an uncontrollable state. A sudden change in process conditions can also cause abnormal behavior such as hunting.

  Therefore, when the carbon dioxide recovery system of the present embodiment senses that the carbon dioxide concentration and the gas flow rate of the process exhaust gas 1 have fluctuated outside of the arbitrarily set allowable range, the exhaust gas discharged from the regeneration tower into the process exhaust gas line 12 is detected. 4 and supply gas 5 are introduced. At this time, the carbon dioxide recovery system of the present embodiment is configured so that the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 are returned to the allowable range and maintained, and the regeneration tower exhaust gas valve 23 and the supply gas valve 25 are maintained. Adjust the opening and opening time. Thereby, in this embodiment, even if the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 change rapidly, the stable operation of the carbon dioxide recovery system can be continued.

  Specifically, when the measuring device 21 senses that the carbon dioxide concentration of the process exhaust gas 1 is lower than the lower limit value of the allowable concentration range, the control unit 22 opens the regeneration tower exhaust gas valve 23. Thereby, the regeneration tower exhaust gas 4 is introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, whereby the carbon dioxide concentration of the process exhaust gas 1 is increased.

  On the other hand, when the measuring device 21 senses that the carbon dioxide concentration of the process exhaust gas 1 is higher than the upper limit value of the allowable concentration range, the control unit 22 opens the supply gas valve 25. As a result, the supply gas 5 is introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, whereby the carbon dioxide concentration of the process exhaust gas 1 is lowered.

  Further, when the measuring device 21 senses that the gas flow rate of the process exhaust gas 1 is lower than the lower limit value of the allowable flow range, the control unit 22 turns on both the regeneration tower exhaust gas valve 23 and the supply gas valve 25. Open. As a result, the regeneration tower exhaust gas 4 and the supply gas 5 are introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, thereby increasing the gas flow rate of the process exhaust gas 1.

  At this time, the ratio of the introduction amounts of the regeneration tower exhaust gas 4 and the supply gas 5 is set so that the carbon dioxide concentration of the process exhaust gas 1 after mixing with these gases is within the allowable concentration range. Thereby, in this embodiment, the gas flow rate of the process exhaust gas 1 can be increased without greatly changing the carbon dioxide concentration of the process exhaust gas 1. The ratio of the introduction amounts of the regeneration tower exhaust gas 4 and the supply gas 5 can be set using, for example, a function prepared in advance.

  Thereafter, the control unit 22 gradually relaxes the various conditions of the carbon dioxide recovery system to the conditions suitable for the state at the time when the carbon dioxide concentration and the gas flow rate of the process exhaust gas 1 converge and become stable. Change to Thereby, in this embodiment, the stable operation of the system can be continued while suppressing the occurrence of abnormal behavior such as heat generation and hunting of the carbon dioxide recovery system.

(2) Details of the regeneration tower exhaust gas 4 and the supply gas 5 Next, the regeneration tower exhaust gas 4 and the supply gas 5 will be described in detail with reference to FIG.

  The regeneration tower exhaust gas 4 introduced into the process exhaust gas line 12 in this embodiment may be at any stage. For example, the regeneration tower exhaust gas 4 may be the one before or after removing impurities such as moisture, the one returned to a gas from a supercritical state or a liquid state, a tank, a lorry, It may be the one before or after being stored with an adsorbent or the like.

  In the present embodiment, the regeneration tower exhaust gas 4 is used as a gas for increasing the carbon dioxide concentration of the process exhaust gas 1, but other gases having a higher carbon dioxide concentration than the process exhaust gas 1 are used. May be. In this case, the gas may be supplied from a gas cylinder, a tank, a gas line from the outside of the carbon dioxide recovery system, or the like.

  Similarly, the supply gas 5 of the present embodiment may be introduced into the process exhaust gas line 12 by any method. The supply gas 5 can be introduced from, for example, a gas cylinder, a tank, a gas line from the outside of the carbon dioxide recovery system, or the like.

  Examples of the supply gas 5 include a gas containing an inert gas having an arbitrary concentration. In this case, the gas composition and inert gas concentration of the supply gas 5 may be any composition and concentration that can be adjusted with the carbon dioxide concentration of the process exhaust gas 1 within an allowable range by being mixed with the process exhaust gas 1. Or concentration. Another example of the supply gas 5 is air.

  Note that the use of an inert gas as the supply gas 5 has an advantage that corrosion of the gas flow path and the like can be suppressed. Further, the use of air as the supply gas 5 has an advantage that the supply gas 5 can be prepared at low cost. The supply gas 5 of the present embodiment may contain carbon dioxide as long as the carbon dioxide concentration is lower than that of the process exhaust gas 1.

  As described above, the carbon dioxide recovery system of the present embodiment introduces the first gas (for example, the regeneration tower exhaust gas 4) having a higher carbon dioxide concentration than the processing target gas 1 into the processing target gas line 12. And a second introduction mechanism for introducing a second gas (e.g., supply gas 5) having a carbon dioxide concentration lower than that of the processing object gas 1 into the processing object gas line 12.

  Therefore, according to the present embodiment, even if the carbon dioxide concentration or the gas flow rate of the processing target gas 1 is rapidly changed, it is possible to continue the stable operation of the carbon dioxide recovery system.

(Second Embodiment)
FIG. 2 is a schematic diagram showing the configuration of the carbon dioxide recovery system of the second embodiment.

  The carbon dioxide recovery system of FIG. 2 includes a measuring device 31 for measuring the carbon dioxide concentration of the absorption tower exhaust gas 3 and the absorption tower exhaust gas 3 instead of the gas supply unit 24 and the supply gas valve 25 shown in FIG. An absorption tower exhaust gas valve 32 for introduction into the process exhaust gas line 12 is provided. The absorption tower exhaust gas valve 32 and the absorption tower 11 are examples of the second introduction mechanism of the present disclosure. The absorption tower exhaust gas 3 is an example of a second gas having a carbon dioxide concentration lower than that of the gas to be processed.

  In the following sentence, in order to distinguish the measuring instrument 21 and the measuring instrument 31, the measuring instrument 21 is called a first measuring instrument, and the measuring instrument 31 is called a second measuring instrument.

  The carbon dioxide recovery system of this embodiment detects that the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 have fluctuated outside an arbitrarily set allowable range. Absorption tower exhaust gas 3 is introduced. At this time, the carbon dioxide recovery system of the present embodiment is used for the regeneration tower exhaust gas valve 23 and the absorption tower exhaust gas so that the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 are maintained within the allowable range. The opening degree and opening time of the valve 32 are adjusted.

  Specifically, when the first measuring instrument 21 senses that the carbon dioxide concentration of the process exhaust gas 1 is lower than the lower limit value of the allowable concentration range, the control unit 22 opens the regeneration tower exhaust gas valve 23. To. Thereby, the regeneration tower exhaust gas 4 is introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, whereby the carbon dioxide concentration of the process exhaust gas 1 is increased.

  On the other hand, when the first measuring instrument 21 senses that the carbon dioxide concentration of the process exhaust gas 1 is higher than the upper limit value of the allowable concentration range, the control unit 22 opens the absorption tower exhaust gas valve 32. As a result, the absorption tower exhaust gas 3 is introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, whereby the carbon dioxide concentration of the process exhaust gas 1 is lowered.

  At this time, the carbon dioxide concentration of the absorption tower exhaust gas 3 varies depending on the carbon dioxide absorption efficiency in the absorption tower 11. Therefore, in the present embodiment, the carbon dioxide concentration of the absorption tower exhaust gas 3 is measured by the second measuring instrument 31 in order to determine the introduction amount of the absorption tower exhaust gas 3.

  In this embodiment, the concentration measurement value is fed back to the control unit 22 to determine the introduction amount of the absorption tower exhaust gas 3. Specifically, when the concentration measurement value is high, the introduction amount is decreased, and when the concentration measurement value is low, the introduction amount is increased.

  When the first measuring instrument 21 senses that the gas flow rate of the process exhaust gas 1 is lower than the lower limit value of the allowable flow range, the control unit 22 uses the regeneration tower exhaust gas valve 23 and the absorption tower exhaust gas. Both valves 32 are opened. Thereby, the regeneration tower exhaust gas 4 and the absorption tower exhaust gas 3 are introduced into the process exhaust gas line 12 and mixed with the process exhaust gas 1, thereby increasing the gas flow rate of the process exhaust gas 1.

  At this time, the ratio of the introduction amounts of the regeneration tower exhaust gas 4 and the absorption tower exhaust gas 3 is determined so that the carbon dioxide concentration of the process exhaust gas 1 after mixing with these gases falls within the allowable concentration range. This is the same as in the first embodiment. However, in this embodiment, when determining the ratio of these introduction amounts, the carbon dioxide concentration of the absorption tower exhaust gas 3 measured by the second measuring device 31 together with the measured value of the first measuring device 21. Is used.

  Thereafter, the control unit 22 gradually relaxes the various conditions of the carbon dioxide recovery system to the conditions suitable for the state at the time when the carbon dioxide concentration and the gas flow rate of the process exhaust gas 1 converge and become stable. Change to Thereby, in the present embodiment, as in the first embodiment, the stable operation of the system can be continued while suppressing the occurrence of abnormal behavior such as heat generation and hunting of the carbon dioxide recovery system.

  As described above, the carbon dioxide recovery system of this embodiment introduces the first introduction mechanism for introducing the regeneration tower exhaust gas 4 into the processing target gas line 12 and the absorption tower exhaust gas 3 into the processing target gas line 12. And a second introduction mechanism.

  Therefore, according to the present embodiment, as in the first embodiment, it is possible to continue the stable operation of the carbon dioxide recovery system even if the carbon dioxide concentration or the gas flow rate of the processing target gas 1 is rapidly changed. Become.

  In addition, when the absorption tower exhaust gas 3 and the regeneration tower exhaust gas 4 are used as the gas to be introduced into the processing target gas line 12, the introduction gas is prepared at a low cost as in the case of using air as the supply gas 5. There is an advantage that you can.

(Modification of the first and second embodiments)
Hereinafter, modifications of the first and second embodiments will be described.

  The first measuring instrument 21 of the first and second embodiments measures the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 between the blower 13 and the absorption tower 11. However, if the control unit 22 can control the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 before being introduced into the absorption tower 11, the first measuring instrument 21 may have the carbon dioxide concentration of the process exhaust gas 1 at other points. Alternatively, the gas flow rate may be measured. Similarly, the second measuring instrument 31 may measure the carbon dioxide concentration of the absorption tower exhaust gas 3 other than the points shown in FIG.

  Further, either the introduction point of the regeneration tower exhaust gas 4 or the introduction point of the supply gas 5 to the process exhaust gas line 12 may be upstream. Similarly, whichever of the introduction point of the regeneration tower exhaust gas 4 and the introduction point of the absorption tower exhaust gas 3 to the process exhaust gas line 12 may be upstream. However, the introduction point of these gases is preferably upstream of the measurement point of the first measuring instrument 21 in the process exhaust gas line 12. The reason is that the introduction point of these gases is set upstream of the measurement point, so that the carbon dioxide concentration and gas flow rate of these gases are reflected in the measurement values of the first measuring instrument 21, and the measurement values are feedback-controlled. This is because it can be used.

  Further, in the first and second embodiments, the carbon dioxide concentration and gas flow rate of the process exhaust gas 1 are automatically controlled by feedback control such as PID control by the control unit 22, but may be controlled manually instead. . For example, in the first and second embodiments, the opening and opening time of the valves 23, 25, and 32 are automatically adjusted by the control unit 22, but these valves 23, 25, and 32 are used as manual valves. The field operator may make adjustments manually.

  In the first and second embodiments, a measuring instrument for grasping the gas composition of the process exhaust gas 1 may be installed, and the measurement result may be used for feedback control by the control unit 22.

  In the first and second embodiments, both the carbon dioxide concentration and the gas flow rate of the process exhaust gas 1 are controlled, but only one of these may be controlled. In this case, the first measuring instrument 21 may measure only one of these.

  Further, instead of the first and second embodiments, a carbon dioxide recovery system having both configurations of the first and second embodiments may be adopted. This carbon dioxide recovery system can introduce the absorption tower exhaust gas 3, the regeneration tower exhaust gas 4, and the supply gas 5 into the process exhaust gas line 12.

  According to at least one embodiment described above, it is possible to continue stable operation of the carbon dioxide recovery system even if the carbon dioxide concentration or gas flow rate of the gas to be processed changes rapidly.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1: Process exhaust gas (processing target gas), 2: Absorbing liquid,
3: Absorption tower exhaust gas, 4: Regeneration tower exhaust gas, 5: Supply gas,
11: Absorption tower, 12: Process exhaust gas line (treatment target gas line),
13: Blower, 14: Rich liquid pump, 15: Regenerative heat exchanger,
16: regeneration tower, 17: reboiler, 18: lean liquid pump, 19: cooler,
21: Measuring instrument (first measuring instrument), 22: Control unit, 23: Valve for regeneration tower exhaust gas,
24: Gas supply unit, 25: Valve for supply gas,
31: Measuring instrument (second measuring instrument), 32: Absorption tower exhaust gas valve

Claims (8)

A treatment target gas containing carbon dioxide and an absorption liquid for absorbing the carbon dioxide are brought into contact with each other to absorb the carbon dioxide, and an absorption tower containing the treatment target gas from which the carbon dioxide has been removed. An absorption tower for discharging exhaust gas,
A regeneration tower for releasing the carbon dioxide from the absorption liquid discharged from the absorption tower, discharging the absorption liquid from which the carbon dioxide has been released, and a regeneration tower exhaust gas containing the carbon dioxide;
A gas line to be treated for introducing the gas to be treated into the absorption tower;
A first introduction mechanism for introducing a first gas having a carbon dioxide concentration higher than that of the processing target gas into the processing target gas line;
A second introduction mechanism for introducing a second gas having a carbon dioxide concentration lower than that of the processing target gas into the processing target gas line;
A carbon dioxide recovery system.   The carbon dioxide recovery system according to claim 1, wherein the first gas is the regeneration tower exhaust gas.   The carbon dioxide recovery system according to claim 1 or 2, wherein the second gas is air, an inert gas, or a mixed gas obtained by mixing air and an inert gas.   The carbon dioxide recovery system according to claim 1 or 2, wherein the second gas is the absorption tower exhaust gas. A measuring instrument for measuring at least one of the carbon dioxide concentration and gas flow rate of the gas to be treated;
A control unit for controlling the amount of the first or second gas introduced into the processing target gas line based on the measurement value of the measuring instrument;
A carbon dioxide recovery system according to any one of claims 1 to 4. A first measuring instrument for measuring at least one of a carbon dioxide concentration and a gas flow rate of the processing target gas;
A second measuring instrument for measuring the carbon dioxide concentration of the absorption tower exhaust gas;
Based on the measured value of the first measuring instrument, the amount of the first gas introduced into the processing target gas line is controlled, and based on the measured value of the first and second measuring instruments, A control unit for controlling the amount of the second gas introduced into the processing target gas line;
A carbon dioxide recovery system according to claim 4. A treatment target gas containing carbon dioxide and an absorption liquid for absorbing the carbon dioxide are brought into contact with each other to absorb the carbon dioxide, and an absorption tower containing the treatment target gas from which the carbon dioxide has been removed. An absorption tower for discharging exhaust gas,
A regeneration tower for releasing the carbon dioxide from the absorption liquid discharged from the absorption tower, discharging the absorption liquid from which the carbon dioxide has been released, and a regeneration tower exhaust gas containing the carbon dioxide;
A gas line to be treated for introducing the gas to be treated into the absorption tower;
A method of operating a carbon dioxide recovery system comprising:
When the carbon dioxide concentration of the processing target gas is lower than a lower limit value, a first gas having a higher carbon dioxide concentration than the processing target gas is introduced into the processing target gas line,
When the carbon dioxide concentration of the processing target gas is higher than an upper limit value, a second gas having a lower carbon dioxide concentration than the processing target gas is introduced into the processing target gas line.
How to operate the carbon dioxide recovery system. A treatment target gas containing carbon dioxide and an absorption liquid for absorbing the carbon dioxide are brought into contact with each other to absorb the carbon dioxide, and an absorption tower containing the treatment target gas from which the carbon dioxide has been removed. An absorption tower for discharging exhaust gas,
A regeneration tower for releasing the carbon dioxide from the absorption liquid discharged from the absorption tower, discharging the absorption liquid from which the carbon dioxide has been released, and a regeneration tower exhaust gas containing the carbon dioxide;
A gas line to be treated for introducing the gas to be treated into the absorption tower;
A method of operating a carbon dioxide recovery system comprising:
When the gas flow rate of the processing target gas is lower than a lower limit value, the processing target gas line has a first gas having a higher carbon dioxide concentration than the processing target gas and a carbon dioxide concentration higher than the processing target gas. Introducing a low second gas,
How to operate the carbon dioxide recovery system.

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