Carbon dioxide recovery device

Abstract

To provide a carbon dioxide recovery device capable of reducing energy consumption.SOLUTION: A carbon dioxide recovery device 10a includes: a multistage type absorption tower 11 having a plurality of absorption chambers 111 connected in series to each other; a first solution path 15 for circulating a solution discharged from the absorption tower 11; a stripping tower 12 which is configured to be connected to the absorption tower 11 through the first solution path 15 and make the solution in the first solution path 15 stripped into an internal space 122; and a first heating device 23 which is configured to heat the solution flowing in the first solution path 15 so that the temperature of the solution stripped in the internal space 122 of the stripping tower 12 becomes equal to or higher than a temperature for stripping the carbon dioxide from the solution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a carbon dioxide capture device. [Background technology]

[0002] The carbon dioxide capture device disclosed in Patent Document 1 is configured to introduce a gas from which carbon dioxide is to be captured into a carbon dioxide absorption tower and circulate a carbon dioxide absorbing solution between the carbon dioxide absorption tower and the carbon dioxide stripper tower. The carbon dioxide contained in the gas is absorbed into the carbon dioxide absorbing solution in the carbon dioxide absorption tower, the carbon dioxide is stripped from the carbon dioxide absorbing solution in the carbon dioxide stripper tower, and the stripped carbon dioxide is captured in the carbon dioxide stripper tower.

[0003] The carbon dioxide diffusion tower of the carbon dioxide capture device disclosed in Patent Document 1 is filled with a packing member configured to allow the carbon dioxide absorbing solution to flow downward. Furthermore, a reboiler that heats the carbon dioxide absorbing solution accumulated inside and generates steam is connected to this carbon dioxide diffusion tower. Then, the carbon dioxide absorbing solution flowing downward inside the packing member comes into gas-liquid contact with the rising steam, heating the carbon dioxide absorbing solution, and carbon dioxide is diffused from the carbon dioxide absorbing solution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-90120 A Summary of the Invention

[0005] (Problem to be solved by the invention) Incidentally, in carbon dioxide recovery equipment, there is a demand for a larger amount of carbon dioxide recovered relative to the amount of energy consumed (i.e., for higher energy efficiency). However, in the configuration disclosed in Patent Document 1, the carbon dioxide absorbing solution flowing down inside the packing member must be heated to "the temperature at which a reaction occurs in which carbon dioxide is stripped from the carbon dioxide absorbing solution," i.e., the stripping temperature, and therefore steam must be generated in the reboiler in an amount and at a temperature that will raise the temperature of the internal space of the carbon dioxide stripper to the aforementioned level or higher. This makes it difficult to reduce energy consumption.

[0006] In view of the above circumstances, one of the objects of the present invention is to provide a carbon dioxide recovery device that can reduce energy consumption without decreasing the amount of carbon dioxide recovered by the carbon dioxide absorbing solution (or while increasing the amount of carbon dioxide recovered). In other words, one of the objects of the present invention is to provide a carbon dioxide recovery device that can improve energy efficiency.

[0007] (Means for solving the problem) In order to achieve the above object, the carbon dioxide capture device according to the present invention comprises: a multi-stage carbon dioxide absorption tower including a plurality of carbon dioxide absorption chambers, the plurality of carbon dioxide absorption chambers being connected in series with each other so that a gas containing carbon dioxide supplied from an external gas supply source passes through the plurality of carbon dioxide absorption chambers in one direction, and a carbon dioxide absorbing solution passes through the plurality of carbon dioxide absorption chambers in a direction opposite to the one direction while contacting the gas in each carbon dioxide absorption chamber, thereby absorbing the carbon dioxide contained in the gas; A first carbon dioxide absorbing solution passage through which the carbon dioxide absorbing solution discharged from the carbon dioxide absorption tower flows; A carbon dioxide diffusion tower that is connected to the carbon dioxide absorption tower via the first carbon dioxide absorbing solution path and is configured so that the carbon dioxide absorbing solution in the first carbon dioxide absorbing solution path is diffused into an internal space; and a first heating device configured to heat the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path so that the temperature of the carbon dioxide absorbing solution diffused in the internal space of the carbon dioxide stripper tower becomes equal to or higher than the temperature at which carbon dioxide is stripped from the carbon dioxide absorbing solution.

[0008] According to the carbon dioxide recovery device of the present invention, it is possible to reduce energy consumption without decreasing the amount of carbon dioxide recovered by the carbon dioxide absorbing solution or while increasing the amount of carbon dioxide recovered. That is, in a conventional configuration in which the flowing solution is heated by steam generated by a reboiler, the internal space of the carbon dioxide stripper must be heated so that the temperature of the flowing carbon dioxide absorbing solution is equal to or higher than the stripping temperature. In contrast, according to a configuration in which the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path is heated by a heating device to a temperature equal to or higher than the stripping temperature, it is possible to reduce energy consumption compared to a configuration in which the internal space of the carbon dioxide stripper is heated. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a carbon dioxide capture device according to this embodiment. [Diagram 2] FIG. 2 is a schematic diagram showing the configuration of a carbon dioxide capture device according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described. In the following description, the carbon dioxide capture device will be abbreviated as "capture device", the carbon dioxide absorption tower will be abbreviated as "absorption tower", the carbon dioxide stripper tower (sometimes called "carbon dioxide regeneration tower") will be abbreviated as "stripping tower", and the carbon dioxide absorption solution will be abbreviated as "solution". In addition, the gas that is the target of carbon dioxide capture by the capture device (i.e., gas containing carbon dioxide) will be referred to as "target gas".

[0011] The target gas source includes devices and equipment that generate gas containing carbon dioxide and heat (exhaust heat). For example, an aluminum melting furnace fueled by LNG (liquefied natural gas) can be an example of the target gas source. In this case, the LNG combustion exhaust gas is the target gas, and the heat generated by the combustion of LNG is the "heat (exhaust heat) of the target gas source." In this case, the target gas is a high-temperature gas whose main component is nitrogen and whose carbon dioxide concentration is about 8%. However, the target gas source is not limited to an aluminum melting furnace fueled by LNG.

[0012] The solution applied is an aqueous amine solution. In this case, the solute contains at least one of a primary amine, a secondary amine, and a tertiary amine. It is preferable that the solute contains at least one of a secondary amine and a tertiary amine.

[0013] 1 is a schematic diagram showing the configuration of a recovery apparatus 10a according to this embodiment. The recovery apparatus 10a according to this embodiment includes an absorption tower 11, a stripper tower 12, a target gas introduction path 13, a target gas discharge path 14, a first solution path 15, a second solution path 16, a third solution path 17, a first solution pump 18, a second solution pump 19, a third solution pump 20, a solution heat exchanger 21, a solution cooler 22, a first heating device 23, a second heating device 24, a carbon dioxide recovery path 25, and a control device 26.

[0014] The absorption tower 11 is a multi-stage (or multi-chamber) absorption tower having a plurality of carbon dioxide absorption chambers 111 connected in series. Specifically, the inside of the absorption tower 11 is partitioned into a plurality of carbon dioxide absorption chambers 111 (spaces) arranged in series in a substantially vertical direction. Hereinafter, the "carbon dioxide absorption chamber 111" may be abbreviated to "absorption chamber 111". One end of the target gas introduction path 13 and one end of the first solution path 15 are connected to the absorption chamber 11 located at the bottom (hereinafter, may be referred to as the "lowest absorption chamber 111D"). The target gas introduction path 13 is a path for feeding the target gas generated in the target gas generation source 90 to the absorption tower 11. The first solution path 15 is a path for feeding the solution from the absorption tower 11 to the stripping tower 12. One end of a second solution path 16 and one end of a target gas discharge path 14 are connected to the uppermost absorption chamber 111 (hereinafter sometimes referred to as the "uppermost absorption chamber 111U"). The second solution path 16 is a path for supplying solution from the stripper tower 12 to the absorption tower 11. The target gas discharge path 14 is a path for discharging the target gas from the stripper tower 12 to the outside.

[0015] Adjacent absorption chambers 111 are connected to each other by the internal target gas paths 112 so that the target gas can flow therethrough, and are also connected to each other by the internal solution paths 113 so that the solution can flow therethrough. That is, the multiple absorption chambers 111 are connected to each other in series by the internal target gas paths 112 and the internal solution paths 113.

[0016] In this manner, the absorption tower 11 is configured so that the target gas delivered from the target gas generation source 90 passes through the multiple absorption chambers 111 in one direction from the lowest absorption chamber 111D to the highest absorption chamber 111U, and is discharged from the uppermost absorption chamber 111U to the outside of the absorption tower 11. The absorption tower 11 is also configured so that the solution delivered from the stripper tower 12 passes through the multiple absorption chambers 111 in the opposite direction from the uppermost absorption chamber 111U to the lowermost absorption chamber 111D, and is discharged from the lowermost absorption chamber 111D to the outside of the absorption tower 11 (delivered to the stripper tower 12). The absorption tower 11 is configured so that the solution and the target gas are brought into gas-liquid contact inside each absorption chamber 111, thereby causing carbon dioxide contained in the target gas to be absorbed by the solution (in other words, so that carbon dioxide is removed from the target gas). In addition, in FIG. 1, an example is shown in which the absorption tower 11 has a five-stage configuration (having five absorption chambers 111), but the number of stages in the absorption tower 11 (the number of absorption chambers 111) is not limited thereto.

[0017] A gas-liquid reaction member 114 is rotatably disposed inside each absorption chamber 111. Each absorption chamber 111 is configured to store a predetermined amount of solution below the gas-liquid reaction member 114 (in other words, at the bottom). The gas-liquid reaction member 114 is a member for promoting the absorption of carbon dioxide by the solution. It can also be said that the gas-liquid reaction member 114 is a member for increasing the contact area between the solution and the target gas. The gas-liquid reaction member 114 is configured so that the solution can permeate and diffuse inside, and the target gas can flow inside. For example, a metal member with a large specific surface area (more specifically, a porous member or a mesh member) is applied to the gas-liquid reaction member 114. The gas-liquid reaction member 114 rotates around a straight line extending in a substantially vertical direction by the driving force of the driving force source 115. For example, a rotating shaft 116 rotated by the driving force source 115 such as an electric motor is provided so as to penetrate each absorption chamber 111 in the vertical direction. The gas-liquid reaction member 114 disposed inside each absorption chamber 111 is attached to the rotating shaft 116 so as to rotate integrally with the rotating shaft 116 .

[0018] The absorption tower 11 is configured so that the target gas flows into each absorption chamber 111 from a position near the bottom of each absorption chamber 111 and near the outer periphery as viewed in the vertical direction, and flows from the inflow position toward a position near the top of each absorption chamber 111 and near the center as viewed in the vertical direction. More specifically, the absorption tower 11 is configured so that the target gas flows into each absorption chamber 111 from below the gas-liquid reaction member 114 and near the outer periphery of the gas-liquid reaction member 114 as viewed in the vertical direction, and flows out of each absorption chamber 111 above the gas-liquid reaction member 114 and near the center of rotation of the gas-liquid reaction member 114 as viewed in the vertical direction. In other words, the gas that flows into each absorption chamber 111 flows from below the outer periphery of the gas-liquid reaction member 114 toward an upward position near the center of rotation of the gas-liquid reaction member 114.

[0019] In order to realize the above-mentioned flow of the target gas in each absorption chamber 111, for example, each internal target gas path 112 is disposed so that its lower end (the end on the upstream side in the flow direction of the target gas) is located near the ceiling surface of each absorption chamber 111 and approximately at the center (near the rotation axis 116) in the vertical view, and its upper end (the end on the downstream side in the flow direction of the target gas) is located near the bottom of the absorption chamber 111 adjacent to the upper side of the absorption chamber 111 to which the lower end is provided (however, at a height where the solution accumulated at the bottom does not flow in) and near the outer periphery in the vertical view. Note that, for the lowest absorption chamber 111D, one end of the target gas introduction path 13 is connected so as to be located near the bottom of the lowest absorption chamber 111D (however, at a height where the solution accumulated at the bottom does not flow in) and near the outer periphery in the vertical view. Moreover, one end of the target gas discharge path 14 is connected to the uppermost absorption chamber 111U so as to be located near the ceiling surface of the uppermost absorption chamber 111U and approximately at the center (near the rotation shaft 116) when viewed in the up-down direction.

[0020] Furthermore, the absorption tower 11 is configured so that the solution flowing into each absorption chamber 111 permeates the gas-liquid reaction component 114 and diffuses into almost the entire gas-liquid reaction component 114. For example, each internal solution path 113 is provided so that its lower end (the end on the downstream side of the solution flow) is located near the upper end of the gas-liquid reaction component 114 and near the center of rotation. Note that, for the uppermost absorption chamber 111U, one end of the second solution path 16 is connected so as to be located near the upper end of the gas-liquid reaction component 114 and near the center of rotation. With such a configuration, the solution flowing into the inside of each absorption chamber 111 through the second solution path 16 or each internal solution path 113 permeates into the inside of the gas-liquid reaction component 114 from the upper end and near the center of rotation. Then, the solution that has permeated into the inside of the gas-liquid reaction component 114 diffuses toward the outer periphery and downward of the inside of the gas-liquid reaction component 114 due to the rotation and gravity of the gas-liquid reaction component 114, and then falls from the gas-liquid reaction component 114 due to gravity. The solution that has fallen from the gas-liquid reaction member 114 temporarily accumulates at the bottom of the absorption chamber 111, and then flows through the internal solution path 113 into the adjacent absorption chamber 111 below.

[0021] The target gas introduction path 13 is a path for supplying the target gas generated in the target gas source 90 to the absorption tower 11. One end of the target gas introduction path 13 is connected to the absorption tower 11, and the other end is connected to the target gas source 90. The target gas introduction path 13 is provided with a target gas purification device 31, a target gas cooler 32, and a target gas pump 33 in this order from the side closer to the target gas source 90 (i.e., the upstream side of the flow of the target gas). The target gas purification device 31 purifies the target gas generated in the target gas source 90 by removing dust and the like from the target gas. The target gas cooler 32 cools the target gas generated in the target gas source 90 to a temperature suitable for absorbing carbon dioxide into the solution in the absorption tower 11. The target gas pump 33 is configured to supply the target gas generated in the target gas source 90 to the lowest absorption chamber 111D of the absorption tower 11 by operating. Various known dust collectors and the like can be applied to the target gas purification device 31. Various known heat exchangers can be used as the target gas cooler 32. A known electric air pump can be used as the target gas pump 33.

[0022] The first solution path 15 is a path for supplying the solution from the absorption tower 11 to the stripper tower 12, and is an example of a first carbon dioxide absorbing solution path of the present invention. One end of the first solution path 15 is connected to the absorption tower 11, and the other end is connected to the stripper tower 12. On the first solution path 15, a first solution pump 18, a solution heat exchanger 21, and a first heating device 23 are provided in this order from the side closer to the absorption tower 11.

[0023] The first solution pump 18 is an example of a pump of the present invention. The first solution pump 18 is configured to feed the solution accumulated at the bottom of the lowest absorption chamber 111D of the absorption tower 11 toward the stripper tower 12 by operating. The configuration of the first solution pump 18 is not particularly limited, and various conventionally known electric liquid-feed pumps can be applied.

[0024] The solution heat exchanger 21 is an example of a heat exchanger of the present invention. The solution heat exchanger 21 is configured to exchange heat between the solution flowing through the first solution path 15 and the solution flowing through the second solution path 16, thereby heating the solution flowing through the first solution path 15 and cooling the solution flowing through the second solution path 16. It can also be said that the solution heat exchanger 21 is configured to preheat the solution flowing through the first solution path 15. The configuration of the solution heat exchanger 21 is not limited, and various conventionally known heat exchangers can be applied.

[0025] The first heating device 23 is configured to heat the solution flowing through the first solution path 15 to a temperature equal to or higher than the "temperature at which a reaction occurs in which carbon dioxide is dissipated from the solution" by utilizing the exhaust heat of the target gas generation source 90. It can also be said that the first heating device 23 is configured to control the temperature of the solution introduced into the stripping tower 12. Hereinafter, the "temperature at which a reaction occurs in which carbon dioxide is dissipated from the solution" may be referred to as the "dissipation temperature". The first heating device 23 includes a first medium path 231, a first medium pump 232, a first heat receiver 233, and a first heater 234. The first medium path 231 is a closed loop path configured to circulate the heating medium. The heating medium is a medium for heating the solution, and is, for example, a fluid such as oil or steam. The first medium pump 232 is configured to circulate the heating medium by operating.

[0026] The first heat receiver 233 is configured to heat the heating medium by exhaust heat from the target gas generation source 90. Specifically, the first heat receiver 233 is connected to a heat transfer path 91 to which a medium (e.g., a fluid such as steam or oil) heated in the target gas generation source 90 is delivered (or circulated). The first heat receiver 233 is configured to heat the heating medium circulating in the first medium path 231 by exchanging heat between the medium delivered from the target gas generation source 90 and the heating medium circulating in the first medium path 231. The first heat receiver 233 may be configured to receive heat from other heat sources in addition to the target gas generation source 90. According to such a configuration, when the amount of heat is insufficient only with the medium delivered from the target gas generation source 90, the shortage of the amount of heat can be compensated for by the heat received from the other heat sources. As the other heat source, a heat source using electricity or a heat source using gas combustion can be applied. The first heater 234 is configured to heat the solution flowing through the first solution path 15 by exchanging heat between the heating medium (heating medium heated in the first heat receiver 233) circulating through the first medium path 231 and the solution flowing through the first solution path 15. The configurations of the first medium pump 232, the first heat receiver 233, and the first heater 234 are not particularly limited. Any of various conventionally known electric liquid delivery pumps can be applied to the first medium pump 232, and any of various conventionally known heat exchangers can be applied to the first heat receiver 233 and the first heater 234.

[0027] The diffusion tower 12 is configured so that carbon dioxide is diffused from the solution fed through the first solution path 15. An internal space 122 capable of diffusing the solution is provided inside the diffusion tower 12 and below a packing member 121 described below. Furthermore, the bottom of the diffusion tower 12 is configured so as to be capable of storing a predetermined amount of solution.

[0028] The other end of the first solution path 15 is connected to an upper portion (e.g., the top) of the stripper tower 12. The stripper tower 12 is configured to be able to diffuse the solution fed through the first solution path 15 into the internal space 122. Specifically, a first diffuser 123 is provided at the upper portion of the stripper tower 12, and the solution fed through the first solution path 15 is diffused into the internal space 122 of the stripper tower 12 by this first diffuser 123. For example, a spray nozzle that sprays the solution (diffuses it in a mist) is applied to the first diffuser 123. Note that such a configuration can also be said to be "the first diffuser 123 is provided at the other end of the first solution path 15."

[0029] A third solution path 17 is connected to the stripper tower 12. The third solution path 17 is an example of a carbon dioxide absorption solution return path of the present invention. The third solution path 17 is a path connected to the stripper tower 12 at both ends, and is configured so that the solution flows out of the stripper tower 12 and flows back to the internal space 122 of the stripper tower 12 again. One end of the third solution path 17 is connected to the bottom of the stripper tower 12 or its vicinity so that the solution accumulated at the bottom of the stripper tower 12 flows in. The other end of the third solution path 17 is connected to a position higher than the liquid level of the amine aqueous solution accumulated at the bottom. The stripper tower 12 is configured to be able to diffuse the solution that flows back through the third solution path 17 into the internal space 122. Specifically, a second diffuser 124 is provided on the inner peripheral surface of the stripper tower 12, and the solution flowing through the third solution path 17 is diffused into the internal space 122 of the stripper tower 12 by this second diffuser 124. The second diffuser 124 may be, for example, a spray nozzle that sprays the solution (diffuses it in a mist) or a shower head that diffuses it in a shower shape.

[0030] A second heating device 24 and a third solution pump 20 are provided on the third solution path 17. The second heating device 24 is configured to heat the solution flowing through the third solution path 17 to a temperature equal to or higher than the dissipation temperature by utilizing exhaust heat from the target gas generation source 90. It can also be said that the second heating device 24 is configured to control the temperature of the solution diffused into the internal space 122 of the stripping tower 12. The second heating device 24 includes a second medium path 241, a second medium pump 242, a second heat receiver 243, and a second heater 244. The second medium path 241 is a closed loop path configured to circulate the heating medium. The heating medium is a medium for heating the solution flowing through the third solution path 17, and is, for example, a fluid such as oil or steam. The second medium pump 242 is configured to circulate the heating medium by operating.

[0031] The second heat receiver 243 is configured to heat the heating medium by exhaust heat from the target gas generation source 90. Specifically, the second heat receiver 243 is connected to a heat transfer path 91 to which a medium (e.g., a fluid such as steam or oil) heated in the target gas generation source 90 is delivered (or circulated). The second heat receiver 243 is configured to heat the heating medium circulating in the second medium path 241 by exchanging heat between the medium delivered from the target gas generation source 90 and the heating medium circulating in the second medium path 241. Note that the second heat receiver 243 may be configured to receive heat from other heat sources in addition to the target gas generation source 90, similar to the first heat receiver 233. The second heater 244 is configured to heat the solution flowing in the third solution path 17 by exchanging heat between the heating medium circulating in the second medium path 241 (the heating medium heated in the second heat receiver 243) and the solution flowing in the third solution path 17. There is no particular limitation on the configuration of the second medium pump 242, the second heat receiver 243, and the second heater 244. Any of various conventionally known electric liquid delivery pumps can be used as the second medium pump 242, and any of various conventionally known heat exchangers can be used as the second heat receiver 243 and the second heater 244.

[0032] One end of a carbon dioxide recovery path 25 is connected to the top (or vicinity) of the stripping tower 12 and above the packing member 121. The carbon dioxide recovery path 25 is a path for discharging the carbon dioxide stripped from the solution from the stripping tower 12. The other end of the carbon dioxide recovery path 25 is connected to, for example, equipment for capturing and utilizing carbon dioxide.

[0033] On the carbon dioxide capture path 25, a demister 41, a mixed gas cooler 42, and a gas-liquid separator 43 are connected in this order from the side closer to the stripper 12. The demister 41 is configured to remove the mist of the vapor of the solution from the mixed gas of the vapor of the solution and carbon dioxide, and return the removed mist to the stripper 12 as a solution. The mixed gas cooler 42 is configured to liquefy the vapor of the solution by cooling the mixed gas of the vapor of the solution and carbon dioxide. The gas-liquid separator 43 is configured to separate the solution and carbon dioxide generated by the liquefaction of the vapor. With this configuration, gaseous carbon dioxide can be separated from the mixed gas of the vapor of the solution and carbon dioxide flowing into the carbon dioxide capture path 25. The separated carbon dioxide is discharged (recovered) to the outside of the capture device 10a. The gas-liquid separator 43 and the stripper 12 are connected by a solution return path 44. This solution return path 44 is configured to return the solution separated from the carbon dioxide in the gas-liquid separator 43 to the stripper 12.

[0034] The second solution path 16 is a path for supplying the solution from the stripper tower 12 to the absorption tower 11, and is an example of a second carbon dioxide absorption solution path of the present invention. One end of the second solution path 16 is connected to the upper part of the absorption tower 11 (the uppermost absorption chamber 111U), and the other end of the second solution path 16 is connected to the bottom of the stripper tower 12. A second solution pump 19, the above-mentioned solution heat exchanger 21, and a solution cooler 22 are provided on the second solution path 16.

[0035] The second solution pump 19 is configured to feed the solution accumulated inside (specifically, at the bottom) of the stripper tower 12 to the absorption tower 11 (specifically, the uppermost absorption chamber 111U of the absorption tower 11) through the second solution path 16 by operating. The second solution pump 19 is provided between the absorption tower 11 and the solution heat exchanger 21 (it can also be said that the second solution pump 19 is provided downstream of the solution heat exchanger 21 in the solution flow). In this embodiment, the second solution pump 19 is provided between the solution heat exchanger 21 and the solution cooler 22. A known electric liquid feed pump can be used as the second solution pump 19.

[0036] The solution cooler 22 cools the solution fed to the absorption tower 11 to a predetermined temperature. Specifically, the solution cools to "a temperature at which a reaction occurs in which carbon dioxide is absorbed by the solution." The solution cooler 22 is configured to cool the solution, for example, by exchanging heat between the solution and a refrigerant (e.g., air) fed from the outside. The solution cooler 22 is provided between the solution heat exchanger 21 and the absorption tower 11.

[0037] The control device 26 is connected to the first solution pump 18, the second solution pump 19, the third solution pump 20, the first heating device 23, the second heating device 24, the target gas pump 33, and the driving force source 115, and can control them. The control device 26 is a device including a computer equipped with a CPU, a RAM, a ROM, and an I / F. A computer program for controlling the recovery device 10a including each of the above devices is stored in the ROM of the computer in advance. The CPU of the computer reads the computer program stored in the ROM, expands it in the RAM (using the RAM as a work area) and executes it. This controls the recovery device 10a. The control device 26 can control the first heating device 23 and the second heating device 24 independently of each other. That is, the control device 26 can control the amount of heat (or the heating temperature of the solution) given to the solution in the first heating device 23 and the amount of heat (or the heating temperature of the solution) given to the solution in the second heating device 24 independently of each other.

[0038] Next, the operation of the recovery device 10a will be described.

[0039] By the operation of the second solution pump 19, the solution whose temperature has been adjusted (cooled) to a temperature suitable for absorbing carbon dioxide in the solution heat exchanger 21 and the solution cooler 22 flows into the uppermost absorption chamber 111 of the absorption tower 11 through the second solution path 16. Then, the flowing-in solution passes through the multiple absorption chambers 111 in sequence from the uppermost absorption chamber 111U to the lowermost absorption chamber 111D. Specifically, the solution temporarily accumulates at the bottom of each absorption chamber 111, and then flows out through the internal solution path 113 toward the adjacent absorption chamber 111 below (the lower absorption chamber 111). Then, the solution accumulates at the bottom of the lowermost absorption chamber 111D.

[0040] Meanwhile, the target gas generated in the target gas generation source 90 flows through the target gas introduction path 13 toward the absorption tower 11 by the operation of the target gas pump 33. Then, solid matter such as dust contained in the target gas is removed in the target gas purification device 31 provided in the target gas introduction path 13, and the target gas is further cooled in the target gas cooler 32. Thereafter, the target gas flows into the lowermost absorption chamber 111D of the absorption tower 11. The target gas that has flowed into the lowermost absorption chamber 111D passes through the multiple absorption chambers 111 connected in series, successively from the lowermost absorption chamber 111D toward the uppermost absorption chamber 111U.

[0041] Then, in each absorption chamber 111 of the absorption tower 11, the solution and the target gas come into gas-liquid contact, and the carbon dioxide contained in the target gas is absorbed by the solution. That is, carbon dioxide is removed (separated) from the target gas. Therefore, the concentration of carbon dioxide contained in the target gas decreases successively as the solution passes through each absorption chamber 111. Meanwhile, while the solution flows through the multiple absorption chambers 111 from the uppermost absorption chamber 111U to the lowermost absorption chamber 111D, the absorption ratio of carbon dioxide in the solution increases successively (the carbon dioxide loading value increases). That is, the solution goes from a carbon dioxide lean state to a carbon dioxide rich state. The target gas from which carbon dioxide has been removed (sometimes referred to as off-gas) is discharged from the uppermost absorption chamber 111U to the outside of the absorption tower 11 through the target gas discharge path 14. Meanwhile, the solution accumulated at the bottom of the lowermost absorption chamber 111D is discharged to the outside of the absorption tower 11 through the first solution path 15 by the operation of the first solution pump 18, and is sent to the stripping tower 12.

[0042] As described above, the absorption tower 11 is configured so that the target gas flowing into each absorption chamber 111 flows from the lower part of the outer periphery to the upper part of the center, and the solution flowing into each absorption chamber 111 diffuses into the gas-liquid reaction member 114 starting from the vicinity and upper part of the rotation center of the gas-liquid reaction member 114. Therefore, in each absorption chamber 111, the target gas flowing inside the gas-liquid reaction member 114 from the lower part of the outer periphery to the upper part of the center and the solution diffusing inside the gas-liquid reaction member 114 from the upper part of the center to the lower part of the outer periphery come into gas-liquid contact in a manner of approximately countercurrent contact. Therefore, the contact rate between the target gas and the solution can be increased. In addition, since the solution is diffused over approximately the entire gas-liquid reaction member 114, the contact area between the target gas and the solution can be increased. Therefore, the amount of carbon dioxide absorbed by the solution in each absorption chamber 111 can be increased.

[0043] Furthermore, since the absorption tower 11 includes a plurality of absorption chambers 111, the carbon dioxide contained in the target gas is absorbed into the solution in each absorption chamber 111 while the target gas flows from the lowest absorption chamber 111D to the highest absorption chamber 111U. Therefore, compared to the single-stage absorption tower 11, the carbon dioxide loading value of the solution can be made larger, and a larger amount of carbon dioxide contained in the target gas can be absorbed. Therefore, the concentration of carbon dioxide contained in the target gas (off-gas) discharged from the absorption tower 11 can be kept low.

[0044] The solution (carbon dioxide-rich solution) accumulated at the bottom of the lowest absorption chamber 111D is discharged from the absorption tower 11 by the operation of the first solution pump 18, and is fed toward the stripper tower 12 through the first solution path 15. Then, while flowing through the first solution path 15 toward the stripper tower 12, the solution is heated in the solution heat exchanger 21 by the heat of the solution flowing through the second solution path 16, and then heated in the first heating device 23 to a temperature equal to or higher than the stripping temperature.

[0045] Then, the solution heated by the solution heat exchanger 21 and the first heating device 23 is diffused (sprayed) into the internal space 122 of the stripper tower 12 by the first diffuser 123. Because the solution is heated to a temperature equal to or higher than the stripping temperature, when the solution is diffused into the internal space 122 of the stripper tower 12, carbon dioxide is dissipated from the solution. As a result, the diffused solution is separated into the liquid solution, vapor generated by vaporizing the solution, and carbon dioxide. Then, the solution accumulates at the bottom of the stripper tower 12. Also, a portion of the vapor is liquefied and accumulates at the bottom of the stripper tower 12.

[0046] A part of the solution accumulated at the bottom of the stripper tower 12 flows into the third solution path 17 by the operation of the third solution pump 20. Then, the solution flowing through the third solution path 17 is heated to a temperature equal to or higher than the stripping temperature by the second heating device 24, and then diffused into the internal space 122 of the absorption tower 11 by the second diffuser 124. Therefore, similar to the case where the solution is diffused by the first diffuser 123, the carbon dioxide remaining in the solution is diffused from the solution, and as a result, the diffused solution is separated into a liquid, a vapor of the solution (vapor containing the amine), and carbon dioxide. Then, the solution accumulates at the bottom of the stripper tower 12. Also, a part of the vapor is liquefied and accumulates at the bottom of the stripper tower 12.

[0047] The mixture of carbon dioxide and the remaining unliquefied steam passes through the filling member 121 and flows into the carbon dioxide capture path 25 from the top of the stripping tower 12, and is discharged to the outside of the stripping tower 12. The filling member 121 is a porous or mesh-like member. Therefore, when the mixture passes through the filling member 121, the mist contained in the mixture is removed to a certain extent.

[0048] In the demister 41 provided in the carbon dioxide capture path 25, steam mist is removed from the mixed gas flowing into the carbon dioxide capture path 25. Furthermore, the mixed gas is cooled in the mixed gas cooler 42, so that the steam is liquefied. Then, in the gas-liquid separator 43, the mixed gas is separated into gaseous carbon dioxide and a liquid solution. The carbon dioxide separated in the gas-liquid separator 43 is sent to the outside via the carbon dioxide capture path 25. That is, the carbon dioxide is captured via the carbon dioxide capture path 25. On the other hand, the solution separated in the gas-liquid separator 43 returns to the stripper 12 through the solution return path 44 and flows down the packing member 121. This cools the packing member 121, accelerating the liquefaction of the steam contained in the mixed gas passing through the packing member 121.

[0049] The solution accumulated at the bottom of the stripper tower 12 is fed from the stripper tower 12 to the absorber tower 11 through the second solution path 16 by the operation of the second solution pump 19. The solution flowing through the second solution path 16 is cooled by heat exchange with the solution flowing through the first solution path 15 in the solution heat exchanger 21, and is further cooled in the solution cooler 22. This brings the solution to a temperature suitable for absorbing carbon dioxide. The solution then flows into the uppermost absorption chamber 111U of the absorber tower 11.

[0050] In this manner, the operation of the first solution pump 18 and the second solution pump 19 causes the solution to circulate through the absorption tower 11, the first solution path 15, the stripper tower 12, and the second solution path 16 in that order. During circulation, the solution repeats a reaction in which it absorbs carbon dioxide contained in the target gas in each absorption chamber 111 of the absorption tower 11 and strips the absorbed carbon dioxide in the stripper tower 12. The carbon dioxide stripped in the stripper tower 12 is discharged via the carbon dioxide capture path 25.

[0051] According to such a configuration, the amount of carbon dioxide recovered relative to the energy consumed can be increased (in other words, the energy efficiency can be increased). That is, in a conventional configuration in which the solution flowing down inside the stripper tower is heated by steam generated by a reboiler, the temperature of the internal space of the stripper tower must be raised so that the temperature of the solution flowing down inside the stripper tower becomes equal to or higher than the stripper temperature. In contrast, according to this embodiment, the first heating device 23 is used to heat the solution to a temperature equal to or higher than the stripper temperature, so that the amount of energy consumed can be reduced compared to a configuration in which the temperature of the internal space of the stripper tower is raised. As a result, the energy efficiency can be increased.

[0052] Furthermore, the solution diffused by the first diffuser 123 accumulates at the bottom of the stripper tower 12. The accumulated solution is then heated to the stripping temperature through the third solution path 17, and is then diffused into the internal space 122 of the stripper tower 12. For this reason, carbon dioxide that was not diffused when diffused by the first diffuser 123 (i.e., carbon dioxide remaining in the solution) is diffused from the solution when the solution is diffused again into the internal space 122 of the stripper tower 12. For this reason, the amount of carbon dioxide remaining in the solution can be reduced (the carbon dioxide loading value of the solution can be reduced), and the amount of carbon dioxide recovered can be increased.

[0053] In this embodiment, the first heating device 23 and the second heating device 24 are controlled separately and independently. That is, the heating temperature of the solution diffused into the internal space 122 of the stripper 12 through the first solution path 15 (in other words, the amount of heat given to the solution) and the temperature of the solution diffused into the internal space 122 of the stripper 12 through the third solution path 17 are controlled independently of each other. With this configuration, the amount of energy consumed by the entire recovery device 10a can be reduced compared to a configuration in which the first heating device 23 and the second heating device 24 are controlled together, in other words, a configuration in which the heating temperature of the solution diffused into the internal space 122 of the stripper 12 through the first solution path 15 and the heating temperature of the solution diffused into the internal space 122 of the stripper 12 through the third solution path 17 are controlled to the same temperature. In other words, the solution diffused into the internal space 122 of the stripping tower 12 through the first solution path 15 and the solution diffused into the internal space 122 of the stripping tower 12 through the third solution path 17 are each heated to a heating temperature suitable for the dissipation of carbon dioxide, thereby reducing energy waste.

[0054] Furthermore, such a configuration makes it possible to reduce the size of the stripper tower 12 while improving energy efficiency. That is, in a conventional stripper tower having a configuration in which the solution flows down from the top to the bottom and is heated by a reboiler, reducing the size of the stripper tower (particularly by reducing the height dimension) shortens the heating time of the solution flowing down. For this reason, in order to prevent or suppress a decrease in the amount of carbon dioxide that can be recovered in the conventional configuration, the amount of heat given to the solution by the reboiler must be increased. For this reason, with the conventional configuration, it is difficult to reduce the size of the stripper tower without reducing energy efficiency.

[0055] In contrast, according to the present embodiment, since carbon dioxide is dissipated from the solution when the solution heated to the dissipation temperature by the first heating device 23 is diffused into the internal space 122 of the dissipation tower 12, the time required for dissipation of carbon dioxide can be shortened compared to the conventional configuration. Therefore, the dissipation tower 12 can be made smaller (particularly, the height of the dissipation tower 12 can be reduced) without increasing the amount of heat given to the solution. In other words, the dissipation tower 12 can be made smaller while improving energy efficiency.

[0056] The solution may be an aqueous amine solution containing at least one of a primary amine, a secondary amine, and a tertiary amine as a solute. In this embodiment, for the following reasons, it is preferable to use an aqueous amine solution containing at least one of a secondary amine and a tertiary amine as a solute. In this case, the solution may or may not contain a primary amine as a solute.

[0057] Secondary amines and tertiary amines have a slower absorption rate of carbon dioxide and a faster dissipation rate of carbon dioxide than primary amines. Therefore, when an amine aqueous solution containing a primary amine as a solute and not containing a secondary amine and a tertiary amine is applied as a solution, in order to separate carbon dioxide from the solution in the stripper tower 12, the stripper tower 12 must be enlarged to ensure the time for carbon dioxide to diffuse from the solution (to lengthen the time for the solution to flow down), and the amount of heat given to the solution in the stripper tower 12 must be increased. On the other hand, when an amine aqueous solution containing at least one of a secondary amine and a tertiary amine as a solute is applied as a solution, carbon dioxide is more likely to dissipate from the solution than when an amine aqueous solution containing a primary amine as a solute and not containing a secondary amine or a tertiary amine is applied. Therefore, compared to the conventional configuration, the stripper tower 12 can be made smaller without reducing the amount of carbon dioxide recovered. In addition, compared to the configuration in which an amine aqueous solution containing a primary amine as a solute is applied as a solution, the amount of heat given to the solution can be reduced.

[0058] In addition, secondary amines and tertiary amines can absorb a larger amount of carbon dioxide than primary amines. On the other hand, secondary amines and tertiary amines have a slower carbon dioxide absorption rate than primary amines. If the absorption tower 11 is a multi-stage type, the time for gas-liquid contact between the solution and the target gas can be extended. Therefore, even if an amine aqueous solution containing at least one of secondary amines and tertiary amines as a solute is applied as the solution, the carbon dioxide loading value of the solution can be increased, so that carbon dioxide can be absorbed at a high concentration from the target gas. Therefore, with this configuration, the amount of carbon dioxide absorbed can be increased without increasing the size of the absorption tower 11 (or while reducing the size of the absorption tower 11). In addition, energy efficiency can be improved.

[0059] However, an amine aqueous solution containing a primary amine as a solute may be used. A solution containing a primary amine as a solute has a high carbon dioxide absorption rate, and therefore, when such a solution is used, the absorption tower 11 can be made smaller without reducing the amount of carbon dioxide absorbed (or while increasing the amount of carbon dioxide absorbed). In this case, the solute may contain only a primary amine and not a secondary amine or a tertiary amine. Also, the solute may contain at least one of a secondary amine and a tertiary amine in addition to a primary amine.

[0060] Furthermore, since the first heating device 23 and the second heating device 24 use the exhaust heat of the target gas generation source 90 to heat the solution, a heat source other than the target gas generation source 90 (a heat source separate and independent from the target gas generation source 90) is not required for heating the solution. Therefore, the amount of energy consumed by the recovery device 10a can be reduced compared to a configuration that uses a heat source other than the target gas generation source 90 to heat the solution. In other words, the energy efficiency can be increased.

[0061] However, the recovery device 10a may include another heating device in addition to the first heating device 23 in order to heat the solution flowing through the first solution path 15 (in other words, another heating device may be used in combination). Similarly, the recovery device 10a may include another heating device in addition to the second heating device 24 in order to heat the solution flowing through the third solution path 17. In addition, in this embodiment, the first heating device 23 and the second heating device 24 each heat the solution only by the exhaust heat of the target gas generation source 90, but are not limited to such a configuration. For example, the first heating device 23 and the second heating device 24 may be configured to heat the solution by heat supplied from another heat source in addition to the exhaust heat of the target gas generation source 90. Even with such a configuration, the energy consumption of the recovery device 10a can be reduced compared to a configuration that does not use the exhaust heat of the target gas generation source 90. Furthermore, with such a configuration, when the amount of heat exhausted from the target gas generation source 90 is insufficient, the insufficient amount of heat can be compensated for.

[0062] Furthermore, when the first solution pump 18 is disposed between the absorption tower 11 and the solution heat exchanger 21, the effect of heat received by the solution on the first solution pump 18 can be suppressed. That is, the temperature of the solution flowing through the first solution path 15 is lower the closer to the absorption tower 11, higher on the downstream side of the solution heat exchanger 21, and further higher on the downstream side of the first heating device 23. For this reason, from the viewpoint of reducing the effect of heat received by the solution on the first solution pump 18, it is preferable to dispose the first solution pump 18 upstream of the solution heat exchanger 21 in the flow of the solution.

[0063] Furthermore, when the second solution pump 19 is disposed between the solution heat exchanger 21 and the solution cooler 22, the effect of heat on the second solution pump 19 from the solution can be reduced while stabilizing the flow of the solution (or preventing or suppressing instability). That is, from the viewpoint of stabilizing the flow of the solution in the second solution path 16, the second solution pump 19 is preferably disposed at a position closer to the stripper tower 12 (upstream of the flow of the solution) than the solution heat exchanger 21 and the solution cooler 22. On the other hand, the temperature of the solution flowing through the second solution path 16 is higher the closer to the stripper tower 12, lower on the downstream side of the solution heat exchanger 21, and further lower on the downstream side of the solution cooler 22. Therefore, from the viewpoint of reducing the effect of heat on the second solution pump 19 from the solution, the second solution pump 19 is preferably disposed on the downstream side of the solution flow of the solution heat exchanger 21 and the solution cooler 22. Therefore, according to this embodiment, it is possible to achieve both stabilization of the flow of the solution and reduction of the effect of heat from the solution.

[0064] However, the positions of the first solution pump 18 and the second solution pump 19 are not limited to these positions. For example, when emphasis is placed on stability of the flow of the solution, the second solution pump 19 may be provided closer to the stripper tower 12 than the solution cooler 22 and the solution heat exchanger 21. On the other hand, when emphasis is placed on reducing the influence of heat from the solution, the second solution pump 19 may be provided closer to the absorption tower 11 than the solution cooler 22 and the solution heat exchanger 21.

[0065] Also, in the first heating device 23, in order to reduce the effect of heat that the first medium pump 232 receives from the heating medium, the first medium pump 232, the first heat receiver 233, and the first heater 234 are arranged so that the heating medium circulates through the first medium path 231 in the above-mentioned order. Similarly, in the second heating device 24, the second medium pump 242, the second heat receiver 243, and the second heater 244 are arranged so that the heating medium circulates through the second medium path 241 in the above-mentioned order.

[0066] Next, a recovery device 10b according to a modified example will be described. FIG. 2 is a schematic diagram showing the configuration of the recovery device 10b according to the modified example. Note that the same reference numerals are used to denote configurations common to the above embodiment, and descriptions thereof may be omitted. As shown in FIG. 2, the recovery device 10b according to the modified example includes a fourth solution path 52, a valve 51, and a fourth solution pump 53. Other than that, the configurations common to the above embodiment can be applied.

[0067] The fourth solution path 52 is a path that connects the solution return path 44 and the second solution path 16 so that the solution can flow through them. One end of the fourth solution path 52 is connected to the solution return path 44 via a valve 51. The other end of the fourth solution path 52 is connected to the second solution path 16 between the second solution pump 19 and the solution cooler 22. The fourth solution path 52 is provided with a fourth solution pump 53. The fourth solution pump 53 operates to feed the solution separated in the gas-liquid separator 43 from between the second solution pump 19 and the solution cooler 22 to the second solution path 16 through the valve 51 and the fourth solution path 52. Therefore, the solution flowing through the fourth solution path 52 merges with the solution flowing through the second solution path 16 and is fed to the absorption tower 11.

[0068] According to this configuration, since the low-temperature solution cooled in the mixture cooler 42 does not return to the stripper 12, a decrease in temperature of the internal space 122 of the stripper 12 can be prevented or suppressed. Therefore, a decrease in the amount of carbon dioxide dissipated in the stripper 12 can be prevented or suppressed. Also, since a decrease in temperature of the internal space 122 of the stripper 12 can be prevented or suppressed compared to when the solution returns to the inside of the stripper 12, even if the amount of heat given to the solution in the first heating device 23 and the second heating device 24 is reduced, a decrease in the amount of carbon dioxide dissipated in the stripper 12 can be prevented or suppressed. Therefore, the amount of energy consumed in the recovery device 10b can be further reduced.

[0069] <Summary of the embodiment> The carbon dioxide capture devices 10a and 10b according to this embodiment are: a multi-stage carbon dioxide absorption tower 11 including a plurality of carbon dioxide absorption chambers 111 connected in series with each other so that a gas (target gas) containing carbon dioxide supplied from an external gas supply source (target gas generation source 90) passes through the plurality of carbon dioxide absorption chambers 111 in one direction, and a carbon dioxide absorbing solution passes through the plurality of carbon dioxide absorption chambers 111 in a direction opposite to the one direction while coming into contact with the gas (target gas) in each carbon dioxide absorption chamber 111, thereby absorbing carbon dioxide contained in the gas (target gas); a first carbon dioxide absorbing solution path (first solution path 15) through which the carbon dioxide absorbing solution discharged from the carbon dioxide absorption tower 11 flows; A carbon dioxide diffusion tower 12 that is connected to the carbon dioxide absorption tower 11 via a first carbon dioxide absorbing solution path (first solution path 15) and is configured so that the carbon dioxide absorbing solution in the first carbon dioxide absorbing solution path (first solution path 15) is diffused into an internal space 122; a first heating device 23 configured to heat the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path (first solution path 15) so that the temperature of the carbon dioxide absorbing solution diffused in the internal space 122 of the carbon dioxide stripper 12 becomes equal to or higher than the temperature at which carbon dioxide is stripped from the carbon dioxide absorbing solution; Equipped with.

[0070] According to such a configuration, the amount of carbon dioxide that can be recovered relative to the energy consumed can be increased (i.e., the energy efficiency can be increased). That is, in a conventional carbon dioxide stripper configured to heat the carbon dioxide absorbing solution flowing down by steam generated by a reboiler, the internal space of the carbon dioxide stripper must be heated so that the temperature of the carbon dioxide absorbing solution flowing down is equal to or higher than the stripping temperature. In this case, a large amount of energy is required to heat the entire internal space of the carbon dioxide stripper. In contrast, according to the present embodiment, the first heating device 23 is configured to heat the carbon dioxide absorbing solution before entering the carbon dioxide stripper 12, i.e., the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path (first solution path 15), to a temperature equal to or higher than the temperature at which carbon dioxide is stripped, so that the amount of energy consumed can be reduced compared to a configuration in which the internal space of the carbon dioxide stripper is heated.

[0071] Furthermore, such a configuration can improve energy efficiency while miniaturizing the carbon dioxide stripper tower 12. That is, in a conventional configuration using a reboiler, the carbon dioxide absorbing solution is not heated to the stripping temperature or higher before flowing into the carbon dioxide stripper tower. Therefore, the carbon dioxide absorbing solution that flows into the carbon dioxide stripper tower is heated to the stripping temperature or higher in the internal space of the carbon dioxide stripper tower before stripping carbon dioxide. Therefore, the size (particularly the height) of the internal space of the carbon dioxide stripper tower is set to a size that allows the above-mentioned heating step and stripping step to be performed within the internal space.

[0072] When attempting to downsize (particularly reduce the height) a conventional carbon dioxide stripper in which the size of the internal space is set as described above, the time during which the carbon dioxide absorbing solution is heated in the internal space of the carbon dioxide stripper is shortened. In order to heat the carbon dioxide absorbing solution to the stripping temperature or higher during a short heating time, the amount of heat provided to the carbon dioxide absorbing solution by the reboiler must be increased, resulting in reduced energy efficiency. Thus, with the conventional configuration, it is difficult to downsize the carbon dioxide stripper while preventing or suppressing a decrease in energy efficiency.

[0073] In contrast, according to this embodiment, since the carbon dioxide absorbing solution is already heated to the dissipation temperature or higher before flowing into the carbon dioxide diffusion tower 12, the carbon dioxide absorbing solution dissipates carbon dioxide immediately when it flows into the carbon dioxide diffusion tower 12 and diffuses. That is, the size of the internal space 122 of the carbon dioxide diffusion tower 12 can be set to a size (height) that can realize the dissipation process of the carbon dioxide absorbing solution. In other words, it is not necessary to provide a space for realizing the temperature increase process of the carbon dioxide absorbing solution in the internal space 122 of the carbon dioxide diffusion tower 12 according to this embodiment. Therefore, the internal space of the carbon dioxide diffusion tower 12 can be made smaller than before. Therefore, the carbon dioxide diffusion tower 12 can be made smaller without increasing the amount of heat given to the carbon dioxide absorbing solution. That is, the carbon dioxide diffusion tower 12 can be made smaller while improving energy efficiency.

[0074] Furthermore, by providing the carbon dioxide capture devices 10a, 10b with the multistage carbon dioxide absorption tower 11, it is possible to increase the amount of carbon dioxide that can be absorbed in the carbon dioxide absorption tower 11, compared to a configuration including a single-stage carbon dioxide absorption tower. And, by providing the carbon dioxide capture devices 10a, 10b with the multistage carbon dioxide absorption tower 11 and the carbon dioxide stripper tower 12 having the above-described configuration, it is possible to increase the amount of carbon dioxide captured from gas (target gas) while reducing energy consumption.

[0075] The first heating device 23 is configured to heat the carbon dioxide absorbing solution by using exhaust heat from the gas supply source (target gas generation source 90).

[0076] According to such a configuration, a heat source other than the gas supply source (target gas generation source 90) is not required for heating the carbon dioxide absorbing solution. Even in a configuration in which a heat source other than the gas supply source (target gas generation source 90) is used in combination, the amount of heat that the heat source other than the gas supply source (target gas generation source 90) gives to the carbon dioxide absorbing solution can be reduced. Therefore, the amount of energy consumed by the carbon dioxide recovery devices 10a, 10b can be reduced compared to a configuration in which the exhaust heat of the gas supply source (target gas generation source 90) is not used to heat the carbon dioxide absorbing solution.

[0077] The carbon dioxide capture devices 10a and 10b are A second carbon dioxide absorbing solution path (second solution path 16) which is a path for supplying a carbon dioxide absorbing solution from the carbon dioxide stripper 12 to the carbon dioxide absorption tower 11; A heat exchanger (solution heat exchanger 21) configured to exchange heat between the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path (first solution path 15) and the carbon dioxide absorbing solution flowing through the second carbon dioxide absorbing solution path (second solution path 16); A pump (first solution pump 18) configured to operate to supply the carbon dioxide absorbing solution from the carbon dioxide absorption tower 11 to the carbon dioxide stripper tower 12; Equipped with The first heating device 23 is disposed between the heat exchanger (the solution heat exchanger 21) on the first carbon dioxide absorbing solution path (the first solution path 15) and the carbon dioxide stripper 12, The pump (first solution pump 18) is disposed between the heat exchanger (solution heat exchanger 21) and the carbon dioxide absorbing tower 11 on the first carbon dioxide absorbing solution path (first solution path 15).

[0078] When the first solution pump 18 is disposed between the absorption tower 11 and the solution heat exchanger 21 (in other words, when the first solution pump 18 is disposed upstream of the solution heat exchanger 21 in the flow of the carbon dioxide absorbing solution), the influence of heat that the first solution pump 18 receives from the carbon dioxide absorbing solution can be suppressed. That is, the temperature of the carbon dioxide absorbing solution flowing through the first solution path 15 is lower the closer to the absorption tower 11, higher on the downstream side of the solution heat exchanger 21, and further higher on the downstream side of the first heating device 23. For this reason, from the viewpoint of reducing the influence of heat that the first solution pump 18 receives from the carbon dioxide absorbing solution, it is preferable that the first solution pump 18 be disposed between the absorption tower 11 and the solution heat exchanger 21.

[0079] The carbon dioxide capture devices 10a and 10b are A carbon dioxide absorbing solution reflux path (third solution path 17) whose both ends are connected to the carbon dioxide diffusion tower 12, and which is configured so that the carbon dioxide absorbing solution flowing in from one end is diffused into the internal space 122 of the carbon dioxide diffusion tower 12 from the other end; a second heating device 24 that heats the carbon dioxide absorbing solution flowing through the carbon dioxide absorbing solution reflux path (third solution path 17) so that the temperature of the carbon dioxide absorbing solution diffused from the other end of the carbon dioxide absorbing solution reflux path (third solution path 17) into the internal space 122 of the carbon dioxide stripper 12 becomes equal to or higher than the temperature at which carbon dioxide is stripped from the carbon dioxide absorbing solution (stripping temperature); and a control device 26 that controls the amount of heat provided to the carbon dioxide absorbing solution by the first heating device 23 and the amount of heat provided to the carbon dioxide absorbing solution by the second heating device 24 independently of each other.

[0080] According to such a configuration, the carbon dioxide remaining in the carbon dioxide absorbing solution accumulated at the bottom of the carbon dioxide stripper tower 12 (i.e., the carbon dioxide that remains in the carbon dioxide absorbing solution without being stripped from the carbon dioxide absorbing solution when diffused from the first carbon dioxide absorbing solution path (first solution path 15) into the internal space 122 of the carbon dioxide stripper tower 12) is stripped when diffused from the carbon dioxide absorbing solution reflux path (third solution path 17) into the internal space 122 of the carbon dioxide stripper tower 12. As a result, the amount of carbon dioxide remaining in the carbon dioxide absorbing solution can be reduced (the carbon dioxide loading value can be reduced), and the amount of carbon dioxide recovered can be increased.

[0081] In addition, in a configuration in which the first heating device 23 and the second heating device 24 are controlled separately and independently, the carbon dioxide absorbing solution diffused into the internal space 122 of the carbon dioxide stripper 12 through the first carbon dioxide absorbing solution path (first solution path 15) and the carbon dioxide absorbing solution diffused into the internal space 122 of the carbon dioxide stripper 12 through the carbon dioxide absorbing solution reflux path (third solution path 17) are each given a quantity of heat to reach a heating temperature suitable for dissipating carbon dioxide, thereby reducing energy waste. Therefore, compared with a configuration in which the first heating device 23 and the second heating device 24 are controlled collectively, the total energy consumption of the carbon dioxide recovery devices 10a, 10b can be reduced.

[0082] The carbon dioxide absorbing solution is an aqueous solution containing at least one of a primary amine, a secondary amine, and a tertiary amine as a solute. In this case, the carbon dioxide absorbing solution is preferably an aqueous solution containing at least one of a secondary amine and a tertiary amine as a solute.

[0083] Secondary amines and tertiary amines absorb more carbon dioxide than primary amines. Therefore, if the carbon dioxide absorbing solution is an aqueous solution containing at least one of a secondary amine and a tertiary amine as a solute, the amount of carbon dioxide absorbed in the carbon dioxide absorption tower 11 can be increased. In addition, secondary amines and tertiary amines have a slower absorption rate of carbon dioxide and a faster dissipation rate of carbon dioxide than primary amines. However, since the carbon dioxide recovery devices 10a and 10b are equipped with a multi-stage carbon dioxide absorption tower 11, even if the carbon dioxide absorbing solution is an aqueous solution containing at least one of a secondary amine and a tertiary amine as a solute, the time of gas-liquid contact between the carbon dioxide absorbing solution and the target gas can be extended, so that the amount of carbon dioxide absorbed from the gas (target gas) can be increased. In addition, since carbon dioxide is easily dissipated in the carbon dioxide dissipation tower 12, the amount of heat given to the carbon dioxide absorbing solution can be reduced.

[0084] Although the embodiment of the present invention and its modified examples have been described above, the technical scope of the present invention is not limited to the above-mentioned embodiment and modified examples. Various modifications of the present invention are possible without departing from the spirit of the present invention, and such modifications are also included in the technical scope of the present invention. [Explanation of symbols]

[0085] Reference Signs List 10a, 10b... carbon dioxide recovery device, 11... carbon dioxide absorption tower, 12... stripping tower, 15... first solution path, 16... second solution path, 18... first solution pump, 19... second solution pump, 23... first heating device, 25... control device, 90... target gas generation source, 111... carbon dioxide absorption chamber

Claims

1. a multi-stage carbon dioxide absorption tower including a plurality of carbon dioxide absorption chambers, the plurality of carbon dioxide absorption chambers being connected in series with each other so that a gas containing carbon dioxide supplied from an external gas supply source passes through the plurality of carbon dioxide absorption chambers in one direction, and a carbon dioxide absorbing solution passes through the plurality of carbon dioxide absorption chambers in a direction opposite to the one direction while contacting the gas in each carbon dioxide absorption chamber, thereby absorbing the carbon dioxide contained in the gas; A first carbon dioxide absorbing solution passage through which the carbon dioxide absorbing solution discharged from the carbon dioxide absorption tower flows; A carbon dioxide diffusion tower that is connected to the carbon dioxide absorption tower via the first carbon dioxide absorbing solution path and is configured so that the carbon dioxide absorbing solution in the first carbon dioxide absorbing solution path is diffused into an internal space; A first heating device configured to heat the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path so that the temperature of the carbon dioxide absorbing solution diffused in the internal space of the carbon dioxide stripper is equal to or higher than the temperature at which carbon dioxide is stripped from the carbon dioxide absorbing solution; A carbon dioxide capture device comprising:

2. The carbon dioxide capture device according to claim 1, The carbon dioxide recovery apparatus, wherein the first heating device is configured to heat a carbon dioxide absorbing solution with exhaust heat from the gas supply source.

3. The carbon dioxide capture device according to claim 1, A second carbon dioxide absorbing solution path which is a path for supplying a carbon dioxide absorbing solution from the carbon dioxide stripper to the carbon dioxide absorption tower; A heat exchanger configured to exchange heat between the carbon dioxide absorbing solution flowing through the first carbon dioxide absorbing solution path and the carbon dioxide absorbing solution flowing through the second carbon dioxide absorbing solution path; a pump configured to operate to pump a carbon dioxide absorbing solution from the carbon dioxide absorption tower to the carbon dioxide stripper tower; Equipped with The first heating device is disposed between the heat exchanger and the carbon dioxide stripper on the first carbon dioxide absorbing solution path, The carbon dioxide recovery apparatus, wherein the pump is disposed between the heat exchanger and the carbon dioxide absorption tower on the first carbon dioxide absorbing solution path.

4. The carbon dioxide capture device according to claim 1, A carbon dioxide absorbing solution reflux path, both ends of which are connected to the carbon dioxide diffusion tower, configured so that the carbon dioxide absorbing solution flowing in from one end is diffused into the internal space of the carbon dioxide diffusion tower from the other end; a second heating device that heats the carbon dioxide absorbing solution flowing through the carbon dioxide absorbing solution reflux path so that the temperature of the carbon dioxide absorbing solution diffused from the other end of the carbon dioxide absorbing solution reflux path into the internal space of the carbon dioxide stripper is equal to or higher than the temperature at which carbon dioxide is stripped from the carbon dioxide absorbing solution; A control device that independently controls the amount of heat provided to the carbon dioxide absorbing solution by the first heating device and the amount of heat provided to the carbon dioxide absorbing solution by the second heating device; A carbon dioxide capture device comprising:

5. The carbon dioxide capture device according to claim 1, The carbon dioxide absorbing solution is an aqueous solution containing at least one of a primary amine, a secondary amine, and a tertiary amine as a solute.

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