JP2010241649A - Carbon dioxide recovering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carbon dioxide recovering system quickly measuring a carbon dioxide content in a circulated absorption liquid. <P>SOLUTION: The carbon dioxide recovering system 1 includes: an absorption tower 3 in which carbon dioxide is absorbed by an absorption liquid; a regeneration tower 5 in which carbon dioxide is released from the absorption liquid to regenerate the absorption liquid; a regenerating heat exchanger 7 disposed between the absorption tower 3 and the regeneration tower 5 and heating the absorption liquid absorbing the carbon dioxide by using the regenerated absorption liquid as a heat source; a measuring device 20, which partially samples the absorption liquid circulating in the system 1, blowing a mixture gas of carbon dioxide and nitrogen to the sampled absorption liquid, and measuring the concentration of carbon dioxide in the mixture gas in contact with the absorption liquid; a memory unit 40 storing the correspondence relation between the carbon dioxide content in the absorption liquid and the concentration of carbon dioxide in the mixture gas; and a computation control unit 30 which acquires the concentration of carbon dioxide measured by the measuring device 20, referring to the correspondence relation stored in the memory unit 40 and quickly detecting the carbon dioxide content in the sampled absorption liquid. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbon dioxide recovery system.

  In recent years, as one of the causes of global warming, the greenhouse effect of carbon dioxide contained in combustion exhaust gas generated when burning fossil fuel has been pointed out. To address this issue, countries are working to reduce greenhouse gas emissions in accordance with the Kyoto Protocol to the United Nations Framework Convention on Climate Change.

  Under such circumstances, in a thermal power plant that uses a large amount of fossil fuel, the combustion exhaust gas produced by burning fossil fuel is brought into contact with the amine-based absorbent, and carbon dioxide is separated and recovered from the combustion exhaust gas. However, a method for storing the recovered carbon dioxide without releasing it into the atmosphere has been studied.

  Specifically, an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas in an amine-based absorption liquid and an absorption liquid (rich liquid) that has absorbed carbon dioxide are supplied from the absorption tower, the rich liquid is heated, and the rich liquid A carbon dioxide recovery system including a regeneration tower for releasing carbon dioxide gas from the water and regenerating an absorbing solution is known (see, for example, Patent Document 1). A reboiler for supplying a heat source is connected to the regeneration tower. The absorption liquid (lean liquid) regenerated in the regeneration tower is supplied to the absorption tower, and the absorption liquid circulates in this system.

  In order for such a carbon dioxide recovery system to operate stably, it is necessary to always match the amount of carbon dioxide absorbed in the absorption liquid in the absorption tower with the amount of carbon dioxide released from the absorption liquid in the regeneration tower. is there. Therefore, for example, the thermal energy supplied to the reboiler has deteriorated while monitoring the carbon dioxide content so that the carbon dioxide content of the lean liquid at the regeneration tower outlet and the absorption tower inlet stably takes a desired value. It is necessary to adjust the discharge amount of the absorbing liquid and the supply amount of the new absorbing liquid.

  However, the titration method generally used as a method for measuring the carbon dioxide content requires a long time (1 to 2 hours) until a measurement result is obtained. Therefore, from the carbon dioxide content measured by such a method, it is not possible to obtain an optimal adjustment amount such as thermal energy to be input to the reboiler, and it is not possible to improve the stability of the operation of the carbon dioxide recovery system. It was.

JP 2004-323339 A

  An object of this invention is to provide the carbon dioxide recovery system which can measure the carbon dioxide content of a circulating absorption liquid rapidly.

  A carbon dioxide recovery system according to an aspect of the present invention is provided with an absorption tower that absorbs carbon dioxide contained in combustion exhaust gas into an absorption liquid, an absorption liquid that absorbs carbon dioxide from the absorption tower, and vapor from the absorption liquid. A regeneration tower for releasing the carbon dioxide gas contained therein and regenerating the absorption liquid; and the regenerated absorption liquid that is provided between the absorption tower and the regeneration tower and is supplied from the regeneration tower to the absorption tower. As a regeneration heat exchanger for heating an absorption liquid that has absorbed carbon dioxide supplied from the absorption tower to the regeneration tower, a part of the absorption liquid supplied from the absorption tower to the regeneration tower, and the regeneration tower At least one of a part of the absorbing liquid supplied to the absorption tower is collected, a mixed gas containing carbon dioxide is blown into the separated absorbing liquid, and carbon dioxide of the mixed gas in contact with the absorbing liquid A measuring device that measures the degree of carbon dioxide, a storage unit that stores a correspondence relationship between the carbon dioxide content of the absorption liquid and the carbon dioxide concentration of the mixed gas in contact with the absorption liquid, and the carbon dioxide measured by the measurement apparatus An arithmetic control unit that acquires the concentration and refers to the correspondence stored in the storage unit to detect the carbon dioxide content of the sorted absorption liquid.

  According to the present invention, the carbon dioxide content of the circulating absorbent can be measured quickly.

1 is a schematic configuration diagram of a carbon dioxide recovery system according to a first embodiment of the present invention. It is a schematic block diagram of the measuring device which concerns on the 1st embodiment. It is a graph which shows an example of the relationship between the carbon dioxide concentration of the mixed gas discharged | emitted from a holding | maintenance container, and the carbon dioxide content of a rich liquid. It is a schematic block diagram of the carbon dioxide recovery system which concerns on the 3rd Embodiment of this invention. It is a schematic block diagram of the carbon dioxide collection system by a modification. It is a schematic block diagram of the carbon dioxide collection system which concerns on the 4th Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery system which concerns on the 5th Embodiment of this invention. It is a principal part schematic block diagram of the carbon dioxide recovery system which concerns on the 6th Embodiment of this invention. It is a principal part schematic block diagram of the carbon dioxide recovery system by a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  (First Embodiment) FIG. 1 shows a schematic configuration of a carbon dioxide recovery system according to a first embodiment of the present invention. Here, the carbon dioxide recovery system recovers carbon dioxide contained in combustion exhaust gas generated by the combustion of fossil fuel using an absorbing liquid capable of absorbing carbon dioxide.

  As shown in FIG. 1, the carbon dioxide recovery system 1 includes an absorption tower 3 that absorbs carbon dioxide contained in the combustion exhaust gas 2a into an absorption liquid, and an absorption liquid that absorbs carbon dioxide from the absorption tower 3 (hereinafter, rich liquid 4a and A regenerating tower that heats the rich liquid 4a, releases carbon dioxide gas containing vapor from the absorbing liquid, discharges exhaust gas 2c containing carbon dioxide gas and steam, and regenerates the absorbing liquid 5. For example, the combustion exhaust gas 2a generated in a power generation facility such as a thermal power plant is supplied to the lower part of the absorption tower 3, and the combustion exhaust gas 2b from which carbon dioxide has been removed is discharged from the top of the absorption tower 3. .

  The absorption tower 3 has an absorption tower tank 3a for storing the rich liquid 4a generated by the absorption liquid absorbing carbon dioxide. Similarly, the regeneration tower 5 has a regeneration tower tank 5a that stores an absorbing liquid regenerated by releasing the carbon dioxide gas from the rich liquid 4a (hereinafter referred to as a lean liquid 4b).

  Here, as the absorbing solution capable of absorbing carbon dioxide, for example, an amine compound aqueous solution in which an amine compound is dissolved in water is used.

  As shown in FIG. 1, a reboiler 6 is provided in the regeneration tower 5. The reboiler 6 generates a steam by heating a part of the lean liquid 4b stored in the regeneration tower tank 5a by using plant steam or the like supplied from the power generation equipment as a heat source to increase the temperature thereof. To supply. When heating the lean solution 4b in the reboiler 6, a small amount of carbon dioxide gas is released from the lean solution 4b and supplied to the regeneration tower 5 together with the vapor. Then, the rich liquid 4a is heated in the regeneration tower 5 by this steam, and carbon dioxide gas is released.

  Regeneration heat exchange between the absorption tower 3 and the regeneration tower 5 using the lean liquid 4b supplied from the regeneration tower 5 to the absorption tower 3 as a heat source and heating the rich liquid 4a supplied from the absorption tower 3 to the regeneration tower 5. A vessel 7 is provided and configured to recover the heat of the lean liquid 4b. Here, as described above, when the carbon dioxide gas is released from the rich liquid 4 a in the regeneration tower 5, the rich liquid 4 a is heated using high-temperature steam from the reboiler 6 as a heat source. Accordingly, the temperature of the lean liquid 4b supplied to the regenerative heat exchanger 7 is relatively high, and this lean liquid 4b is used as a heat source.

  A first rich liquid line 8 for supplying the rich liquid 4a from the bottom of the absorption tower tank 3a to the regenerative heat exchanger 7 is connected between the absorption tower 3 and the regenerative heat exchanger 7. A rich liquid pump 9 for sending the rich liquid 4 a from the absorption tower 3 to the regenerative heat exchanger 7 is provided in the first rich liquid line 8. Further, the first rich liquid line 8 is provided with a measuring device 20, an arithmetic control unit 30, and a storage unit 40 for measuring the carbon dioxide content of the rich liquid 4a. The measuring device 20, the calculation control unit 30, and the storage unit 40 will be described later.

  Between the regeneration heat exchanger 7 and the regeneration tower 5, a second rich liquid line 10 for supplying the rich liquid 4a from the regeneration heat exchanger 7 to the upper portion of the regeneration tower 5 is connected.

  Between the regeneration tower 5 and the regeneration heat exchanger 7, a first lean liquid line 11 for supplying the lean liquid 4b to the regeneration heat exchanger 7 from the bottom of the regeneration tower tank 5a is connected.

  The lean liquid 4 b from the regenerative heat exchanger 7 is sent to the tank 13 by the lean liquid pump 12. The tank 13 stores the absorbent that circulates in the carbon dioxide recovery system 1, is supplied with a new absorbent 4c from the top, and discards the absorbent 4d from the bottom. Thereby, it can prevent that the deteriorated absorption liquid circulates through the carbon dioxide recovery system 1.

  Between the tank 13 and the absorption tower 3, an absorption liquid cooler 14 for cooling the lean liquid 4e supplied from the tank 13 is provided. The absorption liquid cooler 14 uses cooling water (cooling medium) as a cooling source. The lean liquid 4e cooled by the absorption liquid cooler 14 is supplied to the upper part of the absorption tower 3.

  The lean liquid 4e supplied to the upper part of the absorption tower 3 descends from the upper part toward the absorption tower tank 3a in the absorption tower 3. On the other hand, the combustion exhaust gas 2 a supplied to the absorption tower 3 rises from the lower part toward the top in the absorption tower 3. Therefore, the combustion exhaust gas 2a containing carbon dioxide and the lean liquid 4e are in countercurrent contact (direct contact), carbon dioxide is removed from the combustion exhaust gas 2a and absorbed by the lean liquid 4e, and the rich liquid 4a is generated. The combustion exhaust gas 2b from which carbon dioxide has been removed is discharged from the top of the absorption tower 3, and the rich liquid 4a is stored in the absorption tower tank 3a of the absorption tower 3.

  As shown in FIG. 1, exhaust gas 2 c containing carbon dioxide gas and steam discharged from the regeneration tower 5 is condensed (cooled) in the regeneration tower 5 to separate the carbon dioxide gas and the generated condensate. A condenser 17 is connected. The carbon dioxide gas 2d discharged from the condenser 17 is stored in a storage facility (not shown).

  A gas cooling line 15 for supplying the exhaust gas 2c discharged from the regeneration tower 5 to the condenser 17 is connected between the regeneration tower 5 and the condenser 17, and a cooling water (cooling medium) is connected to the gas cooling line 15. Is used to cool the exhaust gas 2c. A condensate line 18 for supplying the condensate from the condenser 17 to the upper part of the regenerator 5 is connected between the condenser 17 and the regenerator 5, and the condensate line 18 from the condenser 17 is connected to the condensate line 18. A condensate pump 19 for feeding the condensate to the regeneration tower 5 is provided.

  FIG. 2 shows a schematic configuration of the measuring device 20. The measuring device 20 includes a sorting line 201, a pump 202, a holding container 203, a heater 204, a mixed gas holding unit 205, a gas flow rate adjustment valve 206, a blowing nozzle 207, a concentration measuring device 208, a pump 209, and a return line 210. .

  The pump 202 separates the rich liquid 4 a flowing through the first rich liquid line 8 via the sorting line 201 and sends it to the holding container 203. The holding container 203 holds the rich liquid 4a that has been fed. The capacity of the holding container 204 is preferably 3 to 5 liters, and the height of the rich liquid 4a to be held is preferably 20 to 50 cm. The heater 204 heats the rich liquid 4a in the holding container 203 and sets it to a desired temperature.

  The mixed gas holding unit 205 holds a mixed gas in which nitrogen and carbon dioxide are mixed. The carbon dioxide concentration of the mixed gas is preferably 10 to 80%. This mixed gas is blown into the rich liquid 4 a in the holding container 203 from the bottom of the holding container 203 through the nozzle 207. The amount of the mixed gas blown is adjusted by a gas flow rate adjustment valve 206. The blowing amount is preferably 50 to 500 ml / min. Although not shown, the nozzle 207 is provided with a sintered metal (wire mesh sintered filter) that is a porous metal that generates bubbles of a mixed gas.

  The pump 209 returns the rich liquid 4 a in the holding container 203 to the first rich liquid line 8 via the return line 210. When measuring the carbon dioxide concentration of the rich liquid 4a, the pumps 202 and 209 are continuously operated, and the rich liquid 4a is separated from the first rich liquid line 8 and the rich liquid 4a is returned from the holding container 203 continuously. Shall.

  The concentration measuring device 208 measures the carbon dioxide concentration of the mixed gas discharged from the top of the holding container 203 and notifies the calculation control unit 30 of the measurement result. For the concentration measuring device 208, for example, an infrared spectrophotometer or a diaphragm electrode can be used.

  The mixed gas blown into the holding container 203 rises from the bottom toward the top in the absorption tower 3. The mixed gas and the rich liquid 4a come into contact with each other, and (part of) carbon dioxide in the mixed gas is absorbed by the rich liquid 4a. Therefore, the carbon dioxide concentration of the mixed gas is lower when discharged from the top of the holding container 203 than before being blown into the holding container 203.

  Here, the carbon dioxide concentration of the mixed gas discharged from the top of the holding container 203 changes according to the carbon dioxide content of the rich liquid 4 a in the holding container 203. For example, when the carbon dioxide content of the rich liquid 4a is low, the carbon dioxide gas in the mixed gas absorbed by the rich liquid 4a increases while the mixed gas rises from the lower part of the absorption tower 3 to the top. Therefore, the carbon dioxide concentration of the mixed gas discharged from the holding container 203 is lowered.

  On the other hand, when the rich liquid 4a has a large carbon dioxide content, the carbon dioxide gas in the mixed gas absorbed by the rich liquid 4a decreases while the mixed gas rises from the lower part of the absorption tower 3 to the top. Therefore, the carbon dioxide concentration of the mixed gas discharged from the holding container 203 is increased.

  In the present embodiment, the relationship between the carbon dioxide concentration of the mixed gas discharged from the holding container 203 and the carbon dioxide content of the rich liquid 4 a is examined in advance, and the carbon dioxide concentration of the mixed gas measured by the concentration measuring device 208. From this, the carbon dioxide content of the rich liquid 4a is detected.

  FIG. 3A shows an example of the relationship between the carbon dioxide concentration of the mixed gas discharged from the holding container 203 and the carbon dioxide content of the rich liquid 4a. FIG. 3A shows that the mixed gas has a carbon dioxide concentration of 50%, the holding container 203 has a height of 50 cm, an inner diameter of 110 mm, the liquid surface height of the rich liquid 4a in the holding container 203 is 40 cm, and a sintered metal. An example is given under the conditions of SUS316 10 μ, temperature of about 30 ° C., and blowing rate of 400 ml / min. A plurality of correspondence relationships in which conditions such as temperature and sintered metal are changed are stored in the storage unit 40. For example, when the temperature is raised among the conditions in FIG. 3A, the correspondence relationship shown in FIG. 3B is obtained.

  The calculation control unit 30 refers to the correspondence stored in the storage unit 40 using the carbon dioxide concentration notified from the concentration measuring device 208, and obtains the carbon dioxide content of the rich liquid 4a.

  In the present embodiment, the mixed gas is blown into the rich liquid 4 a taken from the first rich liquid line 8 held in the holding container 203, and the rich liquid 4 a in the holding container 203 is raised and discharged from the holding container 203. By simply measuring the carbon dioxide concentration of the mixed gas, the carbon dioxide carbon content of the rich liquid 4a can be quickly calculated from the correspondence as previously shown in FIG.

  The measuring device 20 can be attached not only to the first rich liquid line 8 but also to various places where the absorbing liquid flows. Therefore, it is possible to quickly measure the carbon dioxide content at an arbitrary location of the absorbent circulating in the carbon dioxide recovery system.

  It should be noted that the amount of the absorbing liquid taken from the line by the measuring device 20 and contacting the mixed gas and returning to the line again is very small compared to the amount of the absorbing liquid circulating in the carbon dioxide recovery system 1. Therefore, even if the absorbing liquid that has absorbed the carbon dioxide in the mixed gas in the holding container 203 of the measuring device 20 is returned to the carbon dioxide recovery system 1, the balance of the entire system is not affected. Further, the mixed gas discharged from the top of the holding container 203 is very small.

  (Second Embodiment) A carbon dioxide recovery system according to a second embodiment of the present invention has the same configuration as the carbon dioxide recovery system shown in FIG. 1, and will be described with reference to FIG. In the present embodiment, the arithmetic control unit 30 controls the amount of the absorption liquid that circulates in the carbon dioxide recovery system 1 based on the carbon dioxide content of the rich liquid 4a flowing through the first rich liquid line 8. The amount of circulating absorption liquid can be controlled by adjusting the amount supplied by the pumps 9 and 12 and the like.

  A method of controlling the amount of circulating absorbent by the arithmetic control unit 30 will be described. When the calculated carbon dioxide content of the rich liquid 4a flowing through the first rich liquid line 8 is smaller than the assumed value, the arithmetic control unit 30 decreases the amount of the absorbing liquid to be circulated. This is because it is considered that sufficient carbon dioxide absorption capacity can be secured even if the amount of circulating absorption liquid is reduced.

  On the other hand, when the calculated carbon dioxide content of the rich liquid 4a flowing through the first rich liquid line 8 is larger than the assumed value, the arithmetic control unit 30 increases the amount of the absorbing liquid to be circulated. This is because the amount of circulating absorption liquid is considered insufficient.

  The carbon dioxide content of the rich liquid 4a is quickly calculated by the measuring device 20, the calculation control unit 30, and the storage unit 40. Therefore, according to the present embodiment, the amount of circulating absorption liquid in the carbon dioxide recovery system can be controlled to an optimum value, and the operation stability of the carbon dioxide recovery system can be improved.

  (Third Embodiment) FIG. 4 shows a schematic configuration of a carbon dioxide recovery system according to a third embodiment of the present invention. In the present embodiment, the measuring device 20 is also provided at the inlet of the absorption tower 3 (the absorption liquid supply line to the upper part of the absorption tower 3), and the other configuration is the same as that of the first embodiment shown in FIG. It has become. In FIG. 4, the same parts as those of the first embodiment shown in FIG.

  The carbon dioxide content of the absorption liquid (lean liquid 4e) supplied to the absorption tower 3 can be calculated by the measuring device 20 provided at the entrance of the absorption tower 3, the arithmetic control unit 30, and the storage unit 40.

  The arithmetic control unit 30 obtains the difference between the carbon dioxide content of the lean liquid 4e and the carbon dioxide content of the rich liquid 4a (= the carbon dioxide content of the rich liquid 4a−the carbon dioxide content of the lean liquid 4e). Based on this difference, the absorbent replacement amount is controlled. This difference corresponds to the carbon dioxide absorption capacity of the absorption liquid in the absorption tower 3. The absorbent replacement amount refers to the amount of new absorbent 4c supplied to the tank 13 and the amount of absorbent 4d discarded from the tank 13.

  As the absorbent is used in the carbon dioxide recovery system, it deteriorates due to heat, oxygen, sulfides, nitrides, etc., and the carbon dioxide absorption capacity decreases. When the ratio of the deteriorated absorption liquid increases, the carbon dioxide absorption amount in the absorption tower 3 decreases, and the difference decreases.

  When the difference is equal to or smaller than the predetermined value, the arithmetic control unit 30 determines that the ratio of the deteriorated absorbing liquid is large, and performs control so as to increase the absorbing liquid replacement amount. As a result, the proportion of the absorbing solution that has deteriorated decreases, and the absorption tower 3 absorbs the desired amount of carbon dioxide.

  The measuring device 20, the calculation control unit 30, and the storage unit 40 quickly calculate the carbon dioxide contents of the rich liquid 4a and the lean liquid 4e, and obtain the difference. Therefore, according to this embodiment, the carbon dioxide absorption capacity of the absorbent can be maintained at an optimum value, and the stability of the operation of the carbon dioxide recovery system can be improved.

  In addition, as shown in FIG. 5, the measuring apparatus 20 is provided in the exit (1st lean liquid line 11) of the regeneration tower 5, the carbon dioxide content of the lean liquid 4b is measured, and absorption liquid replacement amount based on a measurement result May be controlled.

  In spite of applying the same amount of heat by the reboiler 6, when the carbon dioxide content of the lean liquid 4b is increased, it is considered that the ratio of the deteriorated absorbing liquid is increased. Therefore, the calculation control unit 30 controls to increase the replacement amount of the absorbing liquid when the carbon dioxide content of the lean liquid 4b becomes equal to or greater than a predetermined value.

  Even with such a configuration, the carbon dioxide absorption capacity of the absorbing liquid can be maintained at an optimum value, and the operation stability of the carbon dioxide recovery system can be improved, as described above.

  (Fourth Embodiment) FIG. 6 shows a schematic configuration of a carbon dioxide recovery system according to a fourth embodiment of the present invention. In the present embodiment, the measuring device 20 is provided at the inlet of the absorption tower 3 (absorption liquid supply line to the upper part of the absorption tower 3) and the outlet of the regeneration tower (first lean liquid line 11). Is the same as that of the first embodiment shown in FIG. In FIG. 6, the same parts as those of the first embodiment shown in FIG.

  The carbon dioxide content of the lean liquid 4b and the carbon dioxide content of the lean liquid 4e are calculated by the two measuring devices 20, the calculation control unit 30, and the storage unit 40. The arithmetic control unit 30 monitors whether an abnormality has occurred in the tank 13 based on the transition between the carbon dioxide content of the lean liquid 4b and the carbon dioxide content of the lean liquid 4e. If the relationship between the carbon dioxide content of the lean liquid 4b and the carbon dioxide content of the lean liquid 4e is not within a predetermined range, it can be determined that a problem has occurred in the absorbing liquid replacement operation in the tank 13. If the arithmetic control unit 30 determines that an abnormality has occurred in the tank 13, the arithmetic control unit 30 displays a warning or emits a warning sound.

  The measuring device 20, the calculation control unit 30, and the storage unit 40 can quickly calculate the carbon dioxide contents of the lean liquid 4b and the lean liquid 4e, so that the abnormality of the tank 13 can be detected quickly. Therefore, according to the present embodiment, it is possible to prevent the operation from continuing while the tank 13 is abnormal, and it is possible to improve the stability of the operation of the carbon dioxide recovery system.

  (Fifth Embodiment) FIG. 7 shows a schematic configuration of a carbon dioxide recovery system according to a fifth embodiment of the present invention. In the present embodiment, the measuring device 20 includes an inlet of the absorption tower 3 (an absorption liquid supply line to the upper part of the absorption tower 3), an outlet of the absorption tower 3 (first rich liquid line 8), and an outlet of the regeneration tower (first The other configuration is the same as that of the first embodiment shown in FIG. In FIG. 7, the same parts as those of the first embodiment shown in FIG.

  The three measuring devices 20, the calculation control unit 30, and the storage unit 40 calculate the carbon dioxide content of the rich liquid 4a, the carbon dioxide content of the lean liquid 4b, and the carbon dioxide content of the lean liquid 4e. .

  The arithmetic control unit 30 calculates a difference value between the carbon dioxide content of the lean liquid 4e and the carbon dioxide content of the rich liquid 4a (first difference value = carbon dioxide content of the rich liquid 4a−carbon dioxide content of the lean liquid 4e. (Quantity). The arithmetic control unit 30 also calculates a difference value between the carbon dioxide content of the lean liquid 4b and the carbon dioxide content of the rich liquid 4a (second difference value = carbon dioxide content of the rich liquid 4b−dioxide dioxide of the lean liquid 4e. Determine the carbon content.

  In order to stably operate the carbon dioxide separation and recovery system, it is important to match the amount of carbon dioxide absorbed by the absorption tower 3 with the amount of carbon dioxide released by the regeneration tower 5. That is, an operation in which the first difference value and the second difference value are matched is necessary.

  The arithmetic control unit 30 controls the input heat energy to the reboiler 6 so that the first difference value and the second difference value match when the first difference value and the second difference value do not match. For example, when the second difference value is larger than the first difference value, more heat energy than necessary is input to the reboiler 15. Therefore, the arithmetic control unit 30 performs control so as to reduce the input heat energy to the reboiler 6.

  The carbon dioxide content of the rich liquid 4a, the lean liquid 4b, and the lean liquid 4e is quickly calculated by the measurement device 20, the arithmetic control unit 30, and the storage unit 40, and the first difference value and the second difference value match. It is possible to quickly detect whether or not the heat is input and control the heat energy input to the reboiler 6. Therefore, according to the present embodiment, the input heat energy to the reboiler 6 becomes an optimum value, the stability of the operation of the carbon dioxide recovery system can be improved, and the operating cost can be reduced.

  (Sixth Embodiment) FIG. 8 shows a schematic configuration of a main part of a carbon dioxide recovery system according to a sixth embodiment of the present invention. In the present embodiment, the measuring device 20 is provided in the middle part of the absorption tower 3. By setting it as such a structure, the carbon dioxide content of the absorption liquid in the middle step part of the absorption tower 3 can be measured. From the transition of the measured carbon dioxide content, it is possible to detect the state inside the tower.

  As shown in FIG. 9, you may provide the measuring apparatus 20 in three places, the upper stage part of the absorption tower 3, a middle stage part, and a lower stage part. Thereby, the carbon dioxide content of the absorption liquid in three places of the upper stage part, middle stage part, and lower stage part of the absorption tower 3 can be measured. When it is considered that an abnormality has occurred inside the absorption tower 3, the cause of the abnormality can be elucidated at an early stage from the carbon dioxide content of these three absorbents.

  The measuring device 20, the calculation control unit 30, and the storage unit 40 can quickly calculate the carbon dioxide content of the absorption liquid in the absorption tower 3, and early detection of abnormal parts and the like. Therefore, according to this embodiment, the stability of the operation of the carbon dioxide recovery system can be improved.

  In the present embodiment, the example in which the measuring device 20 is provided in the absorption tower 3 has been described, but it may be provided in the regeneration tower 5.

  (Seventh Embodiment) A mechanism for selectively attaching 0 to 10 wire mesh sintered filters to the nozzle 207 of the measuring device 20 according to the first to sixth embodiments is provided, and the size of the bubble of the blown gas is provided. May be adjusted. The smaller the bubble, the larger the total surface area of the bubble that becomes the gas-liquid contact interface, and the more carbon dioxide is absorbed by the absorbing liquid. On the other hand, when the bubbles become large, the total surface area of the bubbles decreases, and the amount of carbon dioxide absorbed by the absorbing liquid decreases.

  When the carbon dioxide content of the absorbent separated from the carbon dioxide recovery system is large, the absorption rate of carbon dioxide contained in the blown mixed gas is reduced. In such a case, by increasing the number of wire mesh sintered filters so as to reduce the bubbles and increasing the absorption rate, it is possible to measure even an absorption liquid having a high carbon dioxide content.

  Moreover, when the carbon dioxide content of the sorted absorption liquid is small, the absorption rate of carbon dioxide contained in the blown gas is too fast, and there is a possibility that all the carbon dioxide gas in the blown mixed gas may be absorbed. In such a case, it is possible to measure even an absorbing solution having a low carbon dioxide content by reducing the number of wire mesh sintered filters so that bubbles are enlarged.

  Thus, the measurement accuracy of the carbon dioxide content can be improved by adjusting the size of the bubbles according to the number of wire mesh sintered filters.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

DESCRIPTION OF SYMBOLS 1 Carbon dioxide recovery system 3 Absorption tower 5 Regeneration tower 6 Reboiler 7 Regenerative heat exchanger 13 Tank 14 Absorbent liquid cooler 16 Gas cooler 17 Condenser 20 Measuring device 30 Operation control part 40 Storage part

Claims (8)

An absorption tower for absorbing carbon dioxide contained in the combustion exhaust gas into the absorption liquid;
An absorption liquid that absorbs carbon dioxide from the absorption tower is supplied, and a regeneration tower that regenerates the absorption liquid while releasing carbon dioxide gas containing steam from the absorption liquid;
The carbon dioxide supplied from the absorption tower to the regeneration tower is absorbed by the regenerated absorption liquid provided between the absorption tower and the regeneration tower and supplied from the regeneration tower to the absorption tower as a heat source. A regenerative heat exchanger for heating the absorption liquid;
At least one of a part of the absorption liquid supplied from the absorption tower to the regeneration tower and a part of the absorption liquid supplied from the regeneration tower to the absorption tower are separated, and the separated absorption liquid is subjected to carbon dioxide. A measuring device that blows in a mixed gas containing carbon and measures the carbon dioxide concentration of the mixed gas in contact with the absorbing liquid;
A storage unit that stores a correspondence relationship between the carbon dioxide content of the absorbing liquid and the carbon dioxide concentration of the mixed gas in contact with the absorbing liquid;
An operation control unit that acquires the carbon dioxide concentration measured by the measurement device, refers to the correspondence stored in the storage unit, and detects the carbon dioxide content of the sorted absorption liquid;
A carbon dioxide recovery system. The measuring device is
A preparative line for separating the absorption liquid from the absorption liquid line through which the absorption liquid flows;
A holding container for holding the sorted absorption liquid;
A heater for heating the holding container;
A gas holding unit for holding the mixed gas;
A nozzle that is provided at the bottom of the holding container and blows the mixed gas into the absorbing liquid held in the holding container;
A concentration measuring device that is in contact with the absorbing liquid, measures the carbon dioxide concentration of the mixed gas discharged from the top of the holding container, and notifies the calculation control unit of the measurement result;
A return line for returning the absorption liquid held in the holding container to the absorption liquid line;
The carbon dioxide recovery system according to claim 1, comprising: The measuring device is provided between the absorption liquid outlet of the absorption tower and the regenerative heat exchanger,
The said calculation control part detects the carbon dioxide content of the absorption liquid which absorbed the carbon dioxide in the said absorption tower, and controls the amount of circulating absorption liquids based on a detection result, The dioxide dioxide of Claim 2 characterized by the above-mentioned. Carbon capture system. A tank provided between the absorption tower and the regenerative heat exchanger, storing the regenerated absorption liquid, supplied with a new absorption liquid from the top, and discarding the absorption liquid from the bottom;
The measuring device is provided between the absorption liquid outlet of the absorption tower and the regeneration heat exchanger, and between the absorption liquid inlet of the absorption tower and the tank,
The calculation control unit is a first carbon dioxide content that is a carbon dioxide content of an absorption liquid that has absorbed carbon dioxide in the absorption tower, and a carbon dioxide content of an absorption liquid that is supplied to the absorption tower. 2 is detected, the difference between the carbon dioxide content of 1 and the carbon dioxide content of 2 is calculated, and the supply amount and absorption of the new absorbent in the tank are calculated based on the difference. The carbon dioxide recovery system according to claim 1, wherein a waste amount of the liquid is controlled. A tank provided between the absorption tower and the regenerative heat exchanger, storing the regenerated absorption liquid, supplied with a new absorption liquid from the top, and discarding the absorption liquid from the bottom;
The measuring device is provided between the absorption liquid outlet of the regeneration tower and the regeneration heat exchanger,
The arithmetic control unit detects the carbon dioxide content of the absorbent regenerated in the regeneration tower, and controls the supply amount of the new absorbent and the discarded amount of the absorbent in the tank based on the detection result. The carbon dioxide recovery system according to claim 1, wherein the system is a carbon dioxide recovery system. A tank provided between the absorption tower and the regenerative heat exchanger, storing the regenerated absorption liquid, supplied with a new absorption liquid from the top, and discarding the absorption liquid from the bottom;
The measuring device is provided between the absorption liquid outlet of the regeneration tower and the regeneration heat exchanger, and between the absorption liquid inlet of the absorption tower and the tank,
The arithmetic control unit detects the carbon dioxide content of the absorption liquid regenerated in the regeneration tower and the carbon dioxide content of the absorption liquid supplied to the absorption tower, and the tank has an abnormality based on the detection result. It is determined whether it has generate | occur | produced, The carbon dioxide recovery system of Claim 1 characterized by the above-mentioned. A tank that is provided between the absorption tower and the regeneration heat exchanger, stores the regenerated absorption liquid, is supplied with a new absorption liquid from the top, and discards the absorption liquid from the bottom;
A reboiler that is provided in the regeneration tower, generates steam by heating a part of the absorption liquid in the regeneration tower, and supplies the steam to the regeneration tower;
Further comprising
The measuring device includes an absorption liquid outlet of the absorption tower and the regeneration heat exchanger, an absorption liquid inlet of the absorption tower and the tank, an absorption liquid outlet of the regeneration tower and the regeneration heat exchange. Between the container and
The measuring device includes a first carbon dioxide content that is a carbon dioxide content of an absorption liquid that has absorbed carbon dioxide in the absorption tower, and a second carbon dioxide content that is an absorption liquid supplied to the absorption tower. And the third carbon dioxide content that is the carbon dioxide content of the absorbent regenerated in the regeneration tower, and the carbon dioxide content of 1 and the carbon dioxide content of 2 The thermal energy input to the reboiler is adjusted so that the difference between the difference between the carbon dioxide content of 1 and the difference between the carbon dioxide content of 3 and the carbon dioxide content of 3 matches. Carbon capture system.   The carbon dioxide recovery according to any one of claims 1 to 7, wherein the measuring device is provided at one of at least one of the absorption tower and the regeneration tower or at a plurality of places having different heights. system.

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