JP2011057485A - Carbon dioxide recovery apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a CO<SB>2</SB>recovery apparatus capable of reducing the quantity of heat supplied to a reboiler so as to regenerate an absorption liquid (regeneration energy). <P>SOLUTION: In the CO<SB>2</SB>recovery apparatus, a semi-lean liquid 4b with a relatively high CO<SB>2</SB>concentration regenerated in a low temperature regeneration tower 5 with a low treatment temperature is divided into two, one is supplied to the middle part of an absorption tower 3, and the other is supplied to a high temperature regeneration tower 6 with a high treatment temperature. The high temperature regeneration tower 6 removes CO<SB>2</SB>gas from the semi-lean liquid 4b and discharges a lean liquid 4c with a low CO<SB>2</SB>concentration, which is supplied to the top of the absorption tower 3. Since only a part of the absorption liquid circulated in the CO<SB>2</SB>recovery apparatus is regenerated to the lean liquid 4c, regeneration energy can be reduced. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a carbon dioxide recovery device.

  In recent years, for thermal power plants that use large amounts of fossil fuels, a method for separating and recovering carbon dioxide in combustion exhaust gas by bringing the combustion exhaust gas into contact with an amine-based absorbent and releasing the recovered carbon dioxide to the atmosphere Research has been done on how to store without doing.

  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 device including a regeneration tower that regenerates an absorbing solution by releasing carbon dioxide gas from the carbon dioxide 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 such a carbon dioxide recovery device, it is required to reduce the amount of heat (regeneration energy) input to the reboiler in order to regenerate the absorbing solution.

JP 2004-323339 A

  An object of the present invention is to provide a carbon dioxide recovery device that can reduce regenerative energy.

  A carbon dioxide recovery device according to an aspect of the present invention is configured to absorb an absorption liquid into a carbon dioxide contained in combustion exhaust gas and discharge a rich liquid containing carbon dioxide, the rich liquid being supplied, and a first temperature. The first regeneration tower that removes the carbon dioxide gas containing the vapor from the rich liquid and discharges the first lean liquid, and a part of the first lean liquid are supplied, and are higher than the first temperature. A second regeneration tower for removing carbon dioxide gas containing steam from the first lean liquid and discharging the second lean liquid at the second temperature; and the absorption tower and the first regeneration tower. A first regenerative heat exchanger that is provided in between and heats the rich liquid using the first lean liquid discharged from the first regeneration tower and supplied to the absorption tower as a heat source; and the absorption tower And the second regeneration tower, and the second regeneration tower A second regenerative heat exchanger that heats the rich liquid using the second lean liquid discharged from the tank and supplied to the absorption tower as a heat source, and the first lean liquid in the absorption tower The supply position is lower than the supply position of the second lean liquid.

  According to the present invention, the regenerative energy of the carbon dioxide recovery device can be reduced.

1 is a schematic configuration diagram of a carbon dioxide recovery device according to a first embodiment of the present invention. It is a figure which shows the relationship between absorption liquid carbon dioxide concentration and the amount of absorption liquid. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 2nd Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 3rd Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 4th Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 5th Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 6th Embodiment of this invention. It is a schematic block diagram of the carbon dioxide recovery apparatus which concerns on the 7th Embodiment of this invention.

  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 apparatus according to a first embodiment of the present invention. Here, the carbon dioxide recovery device recovers carbon dioxide contained in the 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 apparatus 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 The absorption liquid (hereinafter referred to as semi-lean liquid 4b) in which the rich liquid 4a is heated to discharge the exhaust gas 2c containing steam and carbon dioxide gas, and the carbon dioxide concentration is lower than that of the rich liquid 4a. The low-temperature regeneration tower 5 to be discharged and the semi-lean liquid 4b are heated to discharge the exhaust gas 2d containing steam and carbon dioxide gas, and the absorption liquid (hereinafter, lean) having a very low carbon dioxide concentration (the carbon dioxide concentration is close to 0). And a high temperature regeneration tower 6 for discharging the liquid 4c).

  For example, 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. .

  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.

  A reboiler 7 is provided in the low temperature regeneration tower 5. The reboiler 7 heats a part of the semi-lean liquid 4b using plant steam supplied from the power generation equipment as a heat source, raises the temperature thereof, generates steam, and supplies the steam to the low temperature regeneration tower 5. When heating the semi-lean liquid 4b in the reboiler 7, a small amount of carbon dioxide gas is released from the semi-lean liquid 4b and supplied to the low-temperature regeneration tower 5 together with the vapor. Then, with this steam, the rich liquid 4a is heated in the low temperature regeneration tower 5, and carbon dioxide gas is released.

  A reboiler 8 is provided in the high temperature regeneration tower 6. The reboiler 8 generates a steam by heating a part of the lean liquid 4 c by using plant steam supplied from the power generation facility as a heat source, and supplies the steam to the high temperature regeneration tower 6. When heating the lean solution 4c in the reboiler 8, a small amount of carbon dioxide gas is released from the lean solution 4c and supplied to the high-temperature regeneration tower 6 together with the vapor. The vapor then heats the semi-lean liquid 4b in the high temperature regeneration tower 6 to release carbon dioxide gas.

  The low temperature regeneration tower 5 and the high temperature regeneration tower 6 are regeneration towers having different treatment temperatures. For example, the treatment temperature of the low temperature regeneration tower 5 is about 100 ° C., and the treatment temperature of the high temperature regeneration tower 6 is about 120 ° C.

  The exhaust gas 2c containing carbon dioxide gas and steam discharged from the low temperature regeneration tower 5 is cooled by the cooler 16, and then the carbon dioxide gas 2e and the condensate are separated by the gas-liquid separator 17. The carbon dioxide gas 2e discharged from the gas-liquid separator 17 is stored in a storage facility (not shown). Further, the condensate in the gas-liquid separator 17 is supplied to the low temperature regeneration tower 5.

  The exhaust gas 2d containing carbon dioxide gas and steam discharged from the high temperature regeneration tower 6 is cooled by the cooler 18, and then the carbon dioxide gas 2f and the condensate are separated by the gas-liquid separator 19. The carbon dioxide gas 2f discharged from the gas-liquid separator 19 is stored in a storage facility (not shown). Further, the condensate in the gas-liquid separator 19 is supplied to the high temperature regeneration tower 6.

  The rich liquid 4a supplied from the absorption tower 3 to the low temperature regeneration tower 5 is heated between the absorption tower 3 and the low temperature regeneration tower 5 by using the semi-lean liquid 4b supplied from the low temperature regeneration tower 5 to the absorption tower 3 as a heat source. A regenerative heat exchanger 11 is provided and configured to recover the heat of the semi-lean liquid 4b.

  Further, between the absorption tower 3 and the high temperature regeneration tower 6, the rich liquid 4 a supplied from the absorption tower 3 to the low temperature regeneration tower 5 is used as a heat source from the lean liquid 4 c supplied from the high temperature regeneration tower 6 to the absorption tower 3. A regenerative heat exchanger 12 for heating is provided and configured to recover the heat of the lean liquid 4c.

  As described above, in the low temperature regeneration tower 5 and the high temperature regeneration tower 6, when carbon dioxide gas is released from the absorbent, the absorbent is heated using the high-temperature steam from the reboilers 7 and 8 as a heat source. Accordingly, the temperatures of the semi-lean liquid 4b and the lean liquid 4c supplied to the regenerative heat exchangers 11 and 12 are relatively high, and the semi-lean liquid 4b and the lean liquid 4c are used as heat sources.

  The ratio of the semi-liquid 4b and the lean liquid 4c can be changed by the opening degree of the valve 9. For example, when the opening degree of the valve 9 is large, the ratio of the semi-lean liquid 4b is large, and when the opening degree of the valve 9 is small, the ratio of the lean liquid 4c is increased by increasing the semi-lean liquid 4b supplied to the high temperature regeneration tower 6. growing.

  The semi-lean liquid 4 b from the regenerative heat exchanger 11 is cooled to a predetermined temperature (for example, 30 ° C.) by the cooler 13 and then supplied to the middle stage of the absorption tower 3. In general, the absorption tower 3 is provided with a plurality of packed beds filled with packing, and the semi-lean liquid 4b is supplied from between the n-th packed bed and the (n + 1) -th packed bed from the top (n Is an integer of 1 or more.

  The lean liquid 4 c from the regenerative heat exchanger 12 is cooled to a predetermined temperature (for example, 40 to 50 ° C.) by the cooler 14 and then supplied to the top of the absorption tower 3. In other words, the lean solution 4c is supplied from the upper part of the first packed bed from the top.

  The semi-lean liquid 4b and the lean liquid 4c supplied to the absorption tower 3 descend 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, the semi-lean liquid 4b, and the lean liquid 4c are in countercurrent contact (direct contact), and the carbon dioxide is removed from the combustion exhaust gas 2a and absorbed by the semi-lean liquid 4b and the lean liquid 4c. 4a is generated. As the combustion exhaust gas in the absorption tower 3 moves upward (as it rises), carbon dioxide is absorbed in the absorbent and the carbon dioxide concentration decreases. And the combustion exhaust gas 2b from which the carbon dioxide was removed is discharged | emitted from the top part of the absorption tower 3. FIG.

  In general, the carbon dioxide recovery device aims to recover 90% or more of the carbon dioxide in the combustion exhaust gas 2a. Therefore, when the amount of carbon dioxide in the combustion exhaust gas 2a is 100, the carbon dioxide recovery device 1 has a carbon dioxide amount in the combustion exhaust gas 2b discharged from the absorption tower 3 of 10 or less, and the carbon dioxide absorbed in the absorption liquid. It will drive | operate so that quantity may be 90 or more.

  In order to satisfy this condition, it is necessary to further absorb carbon dioxide from the exhaust gas having a low carbon dioxide concentration in the upper part of the absorption tower 3. Accordingly, the lean liquid 4c supplied from the top of the absorption tower 3 needs to have a very low (close to 0) carbon dioxide concentration.

  On the other hand, in the middle part of the absorption tower 3, since the absorbing solution comes into contact with the exhaust gas having a high carbon dioxide concentration, the carbon dioxide concentration in the absorbing solution may be high to some extent. In general, when the absorption liquid is regenerated, the necessary regeneration energy increases as the carbon dioxide concentration in the absorption liquid approaches zero.

  The carbon dioxide recovery device according to the present embodiment takes the above-described circumstances into consideration, and divides the absorption liquid (semi-lean liquid 4b having a higher carbon dioxide concentration than the lean liquid 4c) regenerated in the low temperature regeneration tower 5. One is supplied to the middle stage of the absorption tower 3, and the other is supplied to the high temperature regeneration tower 6.

  The semi-lean liquid 4 b supplied to the high temperature regeneration tower 6 further releases carbon dioxide in the high temperature regeneration tower 6, is discharged as a lean liquid 4 c having a very low carbon dioxide concentration, and is supplied to the top of the absorption tower 3.

  The lean liquid 4c absorbs carbon dioxide from the combustion exhaust gas having a low carbon dioxide concentration in the upper part of the absorption tower 3. The semi-liquid 4b has a higher carbon dioxide concentration than the lean liquid 4c, but is supplied from the middle stage of the absorption tower 3 and has a high carbon dioxide concentration in the exhaust gas in contact therewith, so that it can sufficiently absorb carbon dioxide from the exhaust gas.

  In the carbon dioxide recovery device 1, a part of the absorbing solution is regenerated only by the low temperature regeneration tower 5, and returned to the absorption tower 3 in a state where the carbon dioxide concentration is somewhat high. For this reason, the total amount of heat (regeneration energy) input to the reboilers 7 and 8 of the low temperature regeneration tower 5 and the high temperature regeneration tower 6 is reduced to the reboiler when all the absorption liquids have extremely low (close to 0) carbon dioxide concentration. It can be made smaller than the amount of heat input.

  FIG. 2 is a diagram for explaining the difference in regenerative energy. FIG. 2A shows a case where all of the absorbing liquid (rich liquid 4a) is regenerated into an absorbing liquid having a very low carbon dioxide concentration (lean liquid 4c), and FIG. 2B shows a part of the semi-lean liquid 4b. Show the case. The concentration C1 indicates the carbon dioxide concentration of the lean liquid 4c, the concentration C2 indicates the carbon dioxide concentration of the semi-lean liquid 4b, and the concentration C3 indicates the carbon dioxide concentration of the rich liquid 4a. In FIG. 2 (a), the absorption liquid amount V indicates the total amount of the absorption liquid. In FIG. 2B, the absorption liquid amount V 'represents the total amount of the absorption liquid, the absorption liquid amount V1 represents the liquid amount of the lean liquid 4c, and the absorption liquid amount V'-V1 represents the liquid amount of the semi-lean liquid 4b. The diagonal line in the figure indicates the amount of absorbed carbon dioxide. V ′ is larger than V, and the absorbed carbon dioxide amount shown in FIG. 2A is the same as the absorbed carbon dioxide amount shown in FIG.

  Comparing FIG. 2 (a) and FIG. 2 (b), the carbon dioxide concentration in the case where a part of the absorbing liquid is the semi-lean liquid 4b (FIG. 2 (b)) as in this embodiment. Although the amount of absorbing liquid that is reduced from C3 to C2 increases, the amount of absorbing liquid that reduces the carbon dioxide concentration to C1 can be reduced. The regeneration energy of the absorption liquid increases as the carbon dioxide concentration of the absorption liquid decreases. Therefore, the case where a part of the absorbing liquid is a semi-lean liquid as shown in FIG. 2B is more necessary than the case where all the absorbing liquids are made a lean liquid as shown in FIG. It can be seen that the renewable energy is small.

  In this way, two regeneration towers having different treatment temperatures are provided, and an absorbing liquid (semi-lean liquid 4b) having a somewhat high carbon dioxide concentration is supplied to the middle stage of the absorbing tower 3, so that an absorbing liquid having a very low carbon dioxide concentration (lean liquid). By supplying 4c) to the top of the regeneration tower 3, the regeneration energy can be reduced while maintaining the carbon dioxide recovery efficiency in the combustion exhaust gas.

  In the absorption tower 3, in order to efficiently absorb carbon dioxide, the absorption tower 3 as a whole has a uniform temperature from the viewpoint of the temperature-dependence of the vapor-liquid equilibrium and the absorption rate, or the upper part of the absorption tower 3 It is desirable that the temperature is higher than the lower part. However, since the amine absorbing solution generates heat of dissolution by absorbing carbon dioxide, the temperature tends to become higher toward the lower part of the absorption tower 3.

  As in the present embodiment, a low-temperature absorption liquid (semi-lean liquid 4b) is introduced from the middle stage of the absorption tower 3 to suppress an increase in liquid temperature at the lower part of the absorption tower 3, thereby increasing the carbon dioxide absorption efficiency. The height of 3 can be lowered.

  In the above embodiment, two regeneration towers having different processing temperatures are provided, but three or more regeneration towers may be provided. In this case, the lower the temperature of the regenerated absorption liquid (the higher the carbon dioxide concentration), the lower the supply position to the absorption tower 3. In addition, a regenerative heat exchanger that heats the rich liquid 4 a using an absorption liquid regenerated in each regeneration tower and supplied to the absorption tower 3 as a heat source may be provided between each regeneration tower and the absorption tower 3. As long as the regenerative heat exchanger can sufficiently heat the rich liquid 4a, it is not necessary to provide the same number as the regenerative tower, and at least one regenerative heat exchanger is sufficient.

  (Second Embodiment) FIG. 3 shows a schematic configuration of a carbon dioxide recovery apparatus according to a second embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that a regenerative heat exchanger 21 is provided. In FIG. 3, the same parts as those of the first embodiment shown in FIG.

  The regenerative heat exchanger 21 is provided between the low temperature regeneration tower 5 and the high temperature regeneration tower 6 and is semi-lean introduced from the low temperature regeneration tower 5 to the high temperature regeneration tower 6 using the lean liquid 4c from the high temperature regeneration tower 6 as a heat source. The liquid 4b is heated.

  In the first embodiment, it is necessary to heat the reboiler 8 of the high temperature regeneration tower 6 by the difference between the processing temperatures of the low temperature regeneration tower 5 and the high temperature regeneration tower 6. The regenerative heat exchanger 21 can recover the heat amount of the lean liquid 4 c and reduce the heat energy consumed by the reboiler 8.

  The lean liquid 4c from the high temperature regeneration tower 6 is introduced into the regeneration heat exchanger 12 because it is hotter than the semi-lean liquid 4b discharged from the low temperature regeneration tower even after being used as a heat source for the regeneration heat exchanger 21. The rich liquid 4a is used to raise the temperature to the inlet temperature of the low temperature regeneration tower 5.

  Thus, the regeneration energy of the carbon dioxide recovery device 1 can be further reduced by using the amount of heat of the rich liquid 4a to raise the temperature of the semi-lean liquid 4b supplied to the high temperature regeneration tower 6.

  Although not shown, the lean liquid 4c used as the heat source of the regenerative heat exchanger 12 may be used as a heat source for heating the rich liquid 4a before being introduced into the regenerative heat exchanger 11.

  (Third Embodiment) FIG. 4 shows a schematic configuration of a carbon dioxide recovery apparatus according to a third embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that a mixer 31 is provided. In FIG. 4, the same parts as those of the first embodiment shown in FIG.

  The mixer 31 mixes the semi-lean liquid 4 b cooled by the cooler 13 and the absorption liquid extracted from the middle stage of the absorption tower 3, and supplies the mixed absorption liquid to the middle stage of the absorption tower 3.

  By providing the mixer 31, the absorption liquid below the middle stage of the absorption tower 3 can be sufficiently cooled, and the carbon dioxide absorption efficiency can be improved.

  Although not shown, the absorption tower 3 may be divided into two, a first absorption tower and a second absorption tower, and a mixer 31 may be provided between the first absorption tower and the second absorption tower. .

  (Fourth Embodiment) FIG. 5 shows a schematic configuration of a carbon dioxide recovery apparatus according to a fourth embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that a measuring instrument 41 and a calculation control unit 42 are provided. In FIG. 5, the same parts as those of the first embodiment shown in FIG.

  The measuring instrument 41 measures the carbon dioxide concentration of the semi-lean liquid 4 b supplied to the middle stage of the absorption tower 3 and notifies the calculation control unit 42 of the measurement result.

  The arithmetic control unit 42 controls the opening degree of the valve 9 based on the notified measurement result.

  For example, when the ratio of the semi-lean liquid 4b and the lean liquid 4c was operated at 50:50, the carbon dioxide concentration in the semi-lean liquid 4b measured by the measuring instrument 41 became larger than a desired value (a value in a desired range). In this case, the arithmetic control unit 42 controls the opening degree of the valve 9 so as to reduce the ratio of the semi-lean liquid 4b. As a result, if the ratio of the semi-lean liquid 4b and the lean liquid 4c is 40:60, the amount of heat recovered in the regenerative heat exchanger 11 is reduced, but the regenerative heat exchanger 12 in which the high-temperature lean liquid 4c is the heat source. Therefore, the rich liquid 4a at the inlet of the low temperature regeneration tower 5 has a higher temperature than before the opening of the valve 9 is changed, and the carbon dioxide concentration in the semi-lean liquid 4b decreases.

  Conversely, when the carbon dioxide concentration in the semi-lean liquid 4b measured by the measuring instrument 41 becomes smaller than the desired value, the arithmetic control unit 42 controls the opening degree of the valve 9 so as to increase the ratio of the semi-lean liquid 4b. To do. As a result, if the ratio of the semi-lean liquid 4b and the lean liquid 4c is 60:40, the amount of heat recovered by the regenerative heat exchanger 11 increases, but the regenerative heat exchanger 12 in which the high-temperature lean liquid 4c is the heat source. Therefore, the rich liquid 4a at the inlet of the low temperature regeneration tower 5 has a lower temperature than before the opening of the valve 9 is changed, and the carbon dioxide concentration in the semi-lean liquid 4b increases.

  Thus, by adjusting the opening degree of the valve 9, the temperature of the rich liquid 4a supplied to the low temperature regeneration tower 5 can be changed, and the carbon dioxide concentration of the semi-lean liquid 4b can be controlled. Since the carbon dioxide concentration of the semi-liquid 4b can be controlled to a concentration suitable for carbon dioxide absorption from the combustion exhaust gas, the carbon dioxide absorption efficiency can be improved.

  Further, the arithmetic control unit 42 may be configured to control the heat energy input to the reboiler 7. When it is difficult to control the carbon dioxide concentration of the semi-lean liquid 4b only by changing the opening of the valve 9, such as at the start of the start of the carbon dioxide recovery device 1, the heat energy input to the reboiler 7 is controlled.

  (Fifth Embodiment) FIG. 6 shows a schematic configuration of a carbon dioxide recovery apparatus according to a fifth embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that a measuring instrument 51 and a calculation control unit 52 are provided. In FIG. 6, the same parts as those of the first embodiment shown in FIG.

  The measuring instrument 51 measures the carbon dioxide concentration of the exhaust gas 2 b discharged from the absorption tower 3 and the carbon dioxide concentration and temperature of the lean liquid 4 c supplied to the top of the absorption tower 3. The measuring instrument 51 notifies the calculation control unit 52 of the measurement result.

  The arithmetic control unit 52 controls the cooling amount of the cooler 14, the opening degree of the valve 9, or the input heat amount to the reboiler 8 based on the measurement result notified from the measuring device 51. A control method will be described.

  First, the calculation control unit 52 determines whether or not the assumed carbon dioxide recovery rate has been achieved from the carbon dioxide concentration of the exhaust gas 2b. If it has been achieved, control is performed to maintain the current state.

  When the carbon dioxide concentration of the exhaust gas 2b is larger than a desired value and the assumed carbon dioxide recovery rate cannot be achieved, the arithmetic control unit 52 determines the carbon dioxide concentration of the exhaust gas 2b and the carbon dioxide concentration of the lean liquid 4c. In light of the liquid equilibrium relationship, the recovery rate is not achieved because the carbon dioxide absorption rate is insufficient, or the recovery rate is not achieved because the carbon dioxide concentration of the lean liquid 4c is too high. It is determined whether.

  When the carbon dioxide concentration of the lean liquid 4c is higher than the predetermined value, the arithmetic control unit 52 determines that the recovery rate is not achieved because the carbon dioxide concentration of the lean liquid 4c is too high, and the amount of heat input to the reboiler 8 Control to increase.

  On the other hand, when the carbon dioxide concentration of the lean solution 4c is not high, the arithmetic control unit 52 determines that the carbon dioxide absorption rate is insufficient, and the cause is the temperature shortage of the lean solution 4c or the lean solution. Whether the amount of liquid 4c is insufficient is determined with reference to a database (not shown). Past cases are stored in the database.

  When the measured temperature of the lean solution 4c is lower than the predetermined value, the arithmetic control unit 52 determines that the cause is the temperature shortage of the lean solution 4c and controls the cooling amount of the cooler 14 to be reduced.

  On the other hand, when the measured temperature of the lean solution 4c is not low, the arithmetic control unit 52 determines that the amount of the lean solution 4c is insufficient, reduces the amount of the semi-lean solution 4b, and reduces the amount of the lean solution 4c. The opening degree of the valve 9 is controlled so as to increase.

  In addition, when the calculation control unit 52 cannot determine whether the cause is the temperature of the lean solution 4c or the amount of the lean solution 4c is insufficient even after referring to the database, the calculation control unit 52 first changes the cooling amount of the cooler 14. From the trend of carbon dioxide recovery rate, determine which is the cause. Further, the arithmetic control unit 52 combines the cause and the measurement result, and stores them in the database as a new case.

  Thus, based on the measurement results of the carbon dioxide concentration of the exhaust gas 2b discharged from the absorption tower 3, the carbon dioxide concentration of the lean liquid 4c supplied to the top of the absorption tower 3, and the temperature, the cooling amount of the cooler 14 Alternatively, a desired carbon dioxide recovery rate can be achieved by controlling the opening of the valve 9 or the amount of heat input to the reboiler 8.

  (Sixth Embodiment) FIG. 7 shows a schematic configuration of a carbon dioxide recovery apparatus according to a sixth embodiment of the present invention. This embodiment is different from the first embodiment shown in FIG. 1 in that a measuring instrument 61 and a calculation control unit 62 are provided. In FIG. 7, the same parts as those of the first embodiment shown in FIG.

The measuring device 61 measures the temperature of the absorbent in the middle stage of the absorption tower 3 immediately after the semi-lean liquid 4b is supplied, and notifies the calculation control unit 62 of the measurement result.

  The arithmetic control unit 62 controls the cooling amount of the cooler 13 based on the measurement result notified from the measuring device 61. For example, the arithmetic control unit 62 controls the cooling amount of the cooler 13 to be increased when the measured absorption liquid temperature in the middle stage of the absorption tower 3 is higher than the expected (range) temperature. Conversely, when the measured absorption liquid temperature in the middle stage of the absorption tower 3 is lower than the expected (range) temperature, the arithmetic control unit 62 controls to reduce the cooling amount of the cooler 13. To do.

  Thereby, the temperature inside the absorption tower 3 can be set to a temperature suitable for carbon dioxide recovery.

  (Seventh Embodiment) FIG. 8 shows a schematic configuration of a carbon dioxide recovery apparatus according to a seventh embodiment of the present invention. In the present embodiment, the radius of the packed bed 71 above the semi-lean liquid 4b supply point in the absorption tower 3 is larger than the radius of the packed bed 72 below the supply point, as compared with the first embodiment shown in FIG. The difference is that it is getting smaller. In FIG. 8, the same parts as those of the first embodiment shown in FIG.

  The packed bed 72 below the supply location of the semi-liquid 4b has a larger amount of absorbing liquid to be processed than the packed bed 71 above the supply location of the semi-lean solution 4b. Therefore, by adopting the configuration as shown in FIG. 8, it is possible to prevent the amount of the absorbed liquid from being excessively large with respect to the packed bed and deviating from the preferable liquid flow rate condition.

Moreover, you may use a different packing for the filling layer in the upper part from a semi-lean liquid 4b supply location, and the filling layer in the lower part from a semi-lean liquid 4b supply location. A filler having a large specific surface area is used for the upper packed bed, and a filler having a small specific surface area is used for the lower packed bed. Moreover, you may use the same type and the filling from which a radius differs. A packing with a large radius is used for the lower packing layer where the amount of the absorbing liquid is large, and a packing with a small radius is used for the upper packing layer.

In this way, it is possible to prevent the liquid from being deviated from a suitable liquid flow rate condition by changing the packing material between the upper packed bed and the lower packed bed in the absorption tower 3. Further, the type of packing may be changed between the upper packed bed and the lower packed bed in the absorption tower 3.

  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 constituent elements 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 device 3 Absorption tower 5 Low temperature regeneration tower 6 High temperature regeneration tower 7, 8 Reboiler 9 Valve 11, 12 Regenerative heat exchanger

Claims (9)

An absorption tower for absorbing carbon dioxide contained in the combustion exhaust gas into the absorption liquid and discharging a rich liquid containing carbon dioxide;
A first regeneration tower that is supplied with the rich liquid, removes carbon dioxide gas containing steam from the rich liquid at a first temperature, and discharges the first lean liquid;
A part of the first lean liquid is supplied, and at a second temperature higher than the first temperature, carbon dioxide gas containing steam is removed from the first lean liquid and the second lean liquid is discharged. A second regeneration tower that
The rich liquid is heated using the first lean liquid provided between the absorption tower and the first regeneration tower and discharged from the first regeneration tower and supplied to the absorption tower as a heat source. A first regenerative heat exchanger;
The rich liquid is heated using the second lean liquid that is provided between the absorption tower and the second regeneration tower and is discharged from the second regeneration tower and supplied to the absorption tower as a heat source. A second regenerative heat exchanger;
With
The carbon dioxide recovery device according to claim 1, wherein a supply position of the first lean liquid in the absorption tower is lower than a supply position of the second lean liquid.   The second lean liquid that is provided between the first regeneration tower and the second regeneration tower and is discharged from the second regeneration tower and supplied to the absorption tower is used as the heat source. The carbon dioxide recovery according to claim 1, further comprising a third regeneration heat exchanger that heats the first lean liquid that is discharged from the regeneration tower and supplied to the second regeneration tower. apparatus. Further comprising a mixer for mixing the first lean liquid and the absorbing liquid taken out from a predetermined position in the absorption tower, and supplying the mixed liquid to the absorption tower;
The carbon dioxide recovery apparatus according to claim 1 or 2, wherein a supply position of the mixed liquid in the absorption tower is lower than a supply position of the second lean liquid. A valve that adjusts the ratio of the liquid amount of the first lean liquid supplied to the absorption tower and the liquid amount of the first lean liquid supplied to the second regeneration tower according to the opening;
A measuring instrument for measuring the carbon dioxide concentration of the first lean liquid;
When the measured carbon dioxide concentration is greater than a predetermined value, the opening of the valve is controlled so that the amount of the first lean liquid supplied to the absorption tower is reduced, and the measured carbon dioxide concentration An arithmetic control unit for controlling the opening of the valve so that the amount of the first lean liquid supplied to the absorption tower increases when the value is smaller than the predetermined value;
The carbon dioxide recovery device according to claim 1, further comprising: A cooler for cooling the second lean liquid supplied to the absorption tower;
A valve that adjusts the ratio of the liquid amount of the first lean liquid supplied to the absorption tower and the liquid amount of the first lean liquid supplied to the second regeneration tower according to the opening;
A measuring instrument for measuring the carbon dioxide concentration of the flue gas discharged from the absorption tower and the carbon dioxide concentration and temperature of the cooled second lean liquid;
The amount of heat input to the second regeneration tower when the measured carbon dioxide concentration of the flue gas is higher than a first predetermined value and the measured carbon dioxide concentration of the second lean liquid is higher than a second predetermined value. The measured carbon dioxide concentration of the flue gas is higher than the first predetermined value, the measured carbon dioxide concentration of the second lean liquid is equal to or lower than a second predetermined value, and the measurement When the temperature of the second lean liquid is less than a third predetermined value, the cooling amount of the cooler is controlled to be small, and the measured carbon dioxide concentration of the combustion exhaust gas is higher than the first predetermined value. When the measured carbon dioxide concentration of the second lean liquid is not more than a second predetermined value and the measured temperature of the second lean liquid is not less than the third predetermined value, it is supplied to the absorption tower. Liquid of the first lean liquid An arithmetic control unit which controls the opening degree of the valve so reduced,
The carbon dioxide recovery device according to claim 1, further comprising: A cooler for cooling the first lean liquid supplied to the absorption tower;
A measuring instrument for measuring the temperature of the absorption liquid in the absorption tower at a position lower than the supply position of the first lean liquid;
When the measured temperature is higher than a predetermined value, control is performed to increase the cooling amount of the cooler, and when the measured temperature is lower than the predetermined value, control is performed to decrease the cooling amount of the cooler. An arithmetic control unit;
The carbon dioxide recovery device according to claim 1, further comprising:   The absorption tower has a plurality of packed beds filled with packing, and the radius of the packed bed at a position higher than the first lean liquid supply position is lower than the first lean liquid supply position. The carbon dioxide recovery device according to any one of claims 1 to 6, wherein the carbon dioxide recovery device is smaller than a radius of a certain packed bed.   The absorption tower has a plurality of packed beds filled with packed material, and the packed bed packed at a position higher than the first lean liquid supplying position is lower than the first lean liquid supplying position. The carbon dioxide recovery device according to any one of claims 1 to 6, wherein the specific surface area is larger than that of the packing in the packed bed. and further comprising n (n is an integer of 1 or more) regeneration towers and n regeneration heat exchangers,
The carbon dioxide recovery apparatus according to claim 1, wherein the lean liquid discharged from the regeneration tower and supplied to the absorption tower has a lower supply position in the absorption tower as the temperature is lower.

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