Carbon dioxide recovery system

Abstract

To provide a carbon dioxide recovery system using an amine-based compound as an adsorbent and capable of suppressing the increase of a pressure loss in a flow path caused by adhesion of the amine-based compound.SOLUTION: This carbon dioxide recovery system for recovering carbon dioxide from an exhaust gas containing the carbon dioxide comprises: a recovery device which contains an absorbent carrying an amine-based compound capable of absorbing the carbon dioxide and into which the exhaust gas flows; a feed-out flow path which is connected to the recovery device and through which a gas fed from the recovery device flows; an index value measurement unit that measures an adhesion index value indicating the adhesion degree of the amine-based compound in the feed-out flow path; a cleaning water supply unit that can supply cleaning water to the feed-out flow path; and a supply control unit that controls supplying of the cleaning water carried out by the cleaning water supply unit. The supply control unit controls the cleaning water supply unit to start supplying of the cleaning water to the feed-out flow path when the addition index value is larger than a threshold value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, there has been known a technique for recovering carbon dioxide by adsorbing carbon dioxide from exhaust gas using an adsorbent and then desorbing the carbon dioxide from the adsorbent. For example, Patent Document 1 discloses a carbon dioxide recovery system that performs a process of adsorbing carbon dioxide onto the adsorbent by bringing the adsorbent into contact with exhaust gas, and a process of desorbing carbon dioxide from the adsorbent by bringing the adsorbent that has adsorbed carbon dioxide into contact with superheated steam. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-69423 Summary of the Invention [Problem to be solved by the invention]

[0004] Amine compounds are sometimes used as adsorbents for adsorption and desorption of carbon dioxide. In general, in such adsorbents, desorption of carbon dioxide is promoted by heating. Furthermore, heat of adsorption is generated when carbon dioxide is adsorbed onto the adsorbent. Amine compounds, which are organic substances, may volatilize due to heating during carbon dioxide desorption or due to heat of adsorption during carbon dioxide adsorption, and then adhere to the inner wall of the pipe forming the flow path downstream of the adsorbent. If such adhesion narrows the area within the flow path through which gas can flow, pressure loss in the flow path increases. Therefore, there has been a demand for technology that can suppress the increase in pressure loss in the flow path due to adhesion of amine compounds in carbon dioxide capture systems that use amine compounds as adsorbents.

[0005] The present invention has been made to solve at least part of the above-mentioned problems, and aims to provide a technology that can suppress an increase in pressure loss in a flow path due to adhesion of an amine-based compound in a carbon dioxide capture system that uses an amine-based compound as an adsorbent. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) According to one aspect of the present invention, there is provided a carbon dioxide capture system for capturing carbon dioxide from exhaust gas containing carbon dioxide, the carbon dioxide capture system comprising: a collector containing an adsorbent carrying an amine compound capable of adsorbing carbon dioxide and into which the exhaust gas flows, a delivery flow path connected to the collector and through which gas delivered from the collector flows, an index value measurement unit for measuring an adhesion index value representing the degree of adhesion of the amine compound in the delivery flow path, a cleaning water supply unit capable of supplying cleaning water to the delivery flow path, and a supply control unit for controlling the supply of cleaning water by the cleaning water supply unit, wherein the supply control unit controls the cleaning water supply unit to start supplying cleaning water to the delivery flow path when the adhesion index value is greater than a threshold value.

[0008] According to this configuration, when the adhesion index value is greater than the threshold value, cleaning water is supplied to the delivery flow path. Because the amine compound is water-soluble, the amine compound adhering to the inner wall of the pipe forming the delivery flow path is removed from the inner wall of the pipe forming the delivery flow path by the supplied cleaning water, thereby suppressing an increase in pressure loss in the delivery flow path due to the adhesion of the amine compound.

[0009] (2) In the carbon dioxide capture system of the above aspect, the cleaning water supply unit may be capable of supplying water vapor as the cleaning water to the delivery passage. According to this configuration, since water vapor is used as cleaning water, the supply of cleaning water can be carried out simultaneously with each of the adsorption process of adsorbing carbon dioxide into the recovery vessel and the desorption process of desorbing carbon dioxide from the recovery vessel.

[0010] (3) In the carbon dioxide capture system of the above aspect, the cleaning water supply unit may be capable of supplying liquid water as the cleaning water to the delivery passage. According to this configuration, since liquid water is used as the cleaning water, it is easier to recover the cleaning water used to clean the delivery flow path compared to when water vapor is used as the cleaning water.

[0011] (4) The carbon dioxide recovery system of the above form may further include a gas-liquid separator provided in the delivery flow path downstream of the supply position of the cleaning water, and a concentration measuring unit that measures the concentration of the amine-based compound in the liquid separated from the gas-liquid separator, and the supply control unit may control the supply amount of the cleaning water according to the difference between the concentration value and a concentration threshold value. According to this configuration, the amount of cleaning water supplied is controlled according to the difference between the concentration value of the amine-based compound in the liquid separated from the gas-liquid separator and the concentration threshold value, so that an appropriate amount of cleaning water can be supplied to the discharge flow path compared to a configuration in which the amount of cleaning water supplied is always constant.

[0012] The present invention can be realized in various forms, for example, in the form of a carbon dioxide capture method, a control method for a carbon dioxide capture system, a computer program for executing these systems and methods, a server device for distributing this computer program, a non-transitory storage medium on which the computer program is stored, etc. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system according to a first embodiment. [Figure 2] FIG. 4 is an explanatory diagram showing the steps performed in each of the first and second collectors. [Figure 3] FIG. 4 is an explanatory diagram showing the relationship between the inner diameter of a flow path and pressure loss. [Figure 4] 5 is a flowchart showing the procedure of a cleaning water supply process in the first embodiment. [Figure 5] FIG. 10 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system according to a second embodiment. [Figure 6] FIG. 10 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system according to a third embodiment. [Figure 7] 10 is a flowchart showing the procedure of a cleaning water supply process in a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] First Embodiment 1 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system 1 according to a first embodiment of the present invention. The carbon dioxide capture system 1 is a system that captures carbon dioxide from exhaust gas containing carbon dioxide. The carbon dioxide capture system 1 includes a control unit 10, a first capture unit 11, and a second capture unit 12.

[0015] The control unit 10 is a computer including a ROM, a RAM, and a CPU, and performs various controls of the carbon dioxide capture system 1. The first capture unit 11 and the second capture unit 12 are connected in parallel to the exhaust gas supply passage 21, the exhaust gas discharge passage 22, the purge gas supply passage 31, and the mixed gas delivery passage 32, which will be described later. The first capture unit 11 and the second capture unit 12 contain a first adsorbent 11a and a second adsorbent 12a, respectively, which support an amine compound capable of adsorbing carbon dioxide, and the exhaust gas flows into the first adsorbent 11a and the second adsorbent 12a. Examples of the amine compound supported on the first adsorbent 11a and the second adsorbent 12a include alkylamines, alkanolamines, polyamines, and diamines. In addition to these amine compounds, amine compounds obtained by introducing a substituent into these amine compounds can also be used.

[0016] The carbon dioxide capture system 1 includes a control unit 10, a first capture device 11, a second capture device 12, an exhaust gas supply flow path 21, an exhaust gas discharge flow path 22, a purge gas supply flow path 31, and a mixed gas delivery flow path 32.

[0017] The exhaust gas supply passage 21 is connected to the first recovery vessel 11 and the second recovery vessel 12 and is a gas passage for supplying exhaust gas from a gas emission source (e.g., a factory combustion furnace) that emits exhaust gas containing carbon dioxide by combustion to the inside of the first recovery vessel 11 and the inside of the second recovery vessel 12. A first exhaust gas supply valve 21a and a second exhaust gas supply valve 21b are provided in the piping that forms the exhaust gas supply passage 21. A dehumidifier that dehumidifies the exhaust gas may also be provided in the piping that forms the exhaust gas supply passage 21. The first exhaust gas supply valve 21a and the second exhaust gas supply valve 21b can open and close the respective passages of the exhaust gas supply passage 21 that supply exhaust gas to the first recovery vessel 11 or the second recovery vessel 12. The opening and closing of the first exhaust gas supply valve 21a and the second exhaust gas supply valve 21b is controlled by the control unit 10. When one of the first exhaust gas supply valve 21a and the second exhaust gas supply valve 21b is opened and exhaust gas is supplied to the first recovery device 11 or the second recovery device 12, carbon dioxide is adsorbed into the first adsorbent 11a or the second adsorbent 12a.

[0018] The exhaust gas discharge flow path 22 is connected to the first collector 11 and the second collector 12, and is a gas flow path for allowing the remaining gas (referred to as exhaust off-gas) of the exhaust gas that has not been adsorbed by the first adsorbent 11a and the second adsorbent 12a to flow downstream from the first collector 11 and the second collector 12. Hereinafter, the downstream side refers to the downstream side of the flow of gas that is supplied to the inside of the first collector 11 and the inside of the second collector 12 and then discharged from the inside of the first collector 11 and the second collector 12. A first exhaust gas discharge valve 22a and a second exhaust gas discharge valve 22b are provided in the piping that forms the exhaust gas discharge flow path 22. The first exhaust gas discharge valve 22a and the second exhaust gas discharge valve 22b are capable of opening and closing the respective flow paths of the exhaust gas discharge flow path 22 that discharge exhaust gas from the first collector 11 or the second collector 12. The opening and closing of the first exhaust gas exhaust valve 22a and the second exhaust gas exhaust valve 22b are controlled by the control unit 10. The control unit 10 opens the first exhaust gas exhaust valve 22a in response to the opening of the first exhaust gas supply valve 21a, and opens the second exhaust gas exhaust valve 22b in response to the opening of the second exhaust gas supply valve 21b. Note that the opening of the first exhaust gas supply valve 21a and the opening of the first exhaust gas exhaust valve 22a do not have to be synchronized. Similarly, the opening of the second exhaust gas supply valve 21b and the opening of the second exhaust gas exhaust valve 22b do not have to be synchronized.

[0019] The purge gas supply passage 31 is connected to the first recovery vessel 11 and the second recovery vessel 12 and is a gas passage for supplying purge gas from a purge gas supply source (e.g., a tank for storing purge gas) to the inside of the first recovery vessel 11 and the inside of the second recovery vessel 12. Examples of purge gases include hydrogen, nitrogen, and water vapor. A first purge gas supply valve 31a and a second purge gas supply valve 31b are provided in the piping that forms the purge gas supply passage 31. The first purge gas supply valve 31a and the second purge gas supply valve 31b can open and close the respective passages of the purge gas supply passage 31 that supply purge gas to the first recovery vessel 11 or the second recovery vessel 12. The opening and closing of the first purge gas supply valve 31a and the second purge gas supply valve 31b is controlled by the control unit 10. When one of the first purge gas supply valve 31a and the second purge gas supply valve 31b is opened and purge gas is supplied to the first recovery vessel 11 or the second recovery vessel 12, the carbon dioxide adsorbed in the first adsorbent 11a or the second adsorbent 12a is desorbed.

[0020] The mixed gas delivery passage 32 is connected to the first recovery vessel 11 and the second recovery vessel 12 and is a gas passage for flowing a mixed gas (described later) downstream from the first recovery vessel 11 and the second recovery vessel 12. The mixed gas is a gas discharged from the first recovery vessel 11 or the second recovery vessel 12 by supplying a purge gas, and is a gas obtained by mixing the purge gas with carbon dioxide desorbed from the first adsorbent 11a or the second adsorbent 12a. A first mixed gas delivery valve 32a and a second mixed gas delivery valve 32b are provided in the piping forming the mixed gas delivery passage 32. The first mixed gas delivery valve 32a and the second mixed gas delivery valve 32b can open and close the respective passages of the mixed gas delivery passage 32 that deliver the mixed gas from the first recovery vessel 11 or the second recovery vessel 12. The opening and closing of the first mixed gas delivery valve 32a and the second mixed gas delivery valve 32b is controlled by the control unit 10. The control unit 10 opens the first mixed gas delivery valve 32a in response to the opening of the first purge gas supply valve 31a, and opens the second mixed gas delivery valve 32b in response to the opening of the second purge gas supply valve 31b. Note that the opening of the first purge gas supply valve 31a and the opening of the first mixed gas delivery valve 32a do not have to be synchronized. Similarly, the opening of the second purge gas supply valve 31b and the opening of the second mixed gas delivery valve 32b do not have to be synchronized. The mixed gas delivery flow path 32 and the above-mentioned exhaust gas discharge flow path 22 correspond to delivery flow paths through which gases delivered from the first recovery device 11 and the second recovery device 12 flow.

[0021] A pressure sensor 23 and a temperature sensor 24 are provided in a pipe forming a portion of the exhaust gas discharge flow path 22 downstream of the positions where the first exhaust gas discharge valve 22a and the second exhaust gas discharge valve 22b are provided. The pressure sensor 23 measures the pressure inside the pipe forming the exhaust gas discharge flow path 22. The temperature sensor 24 measures the temperature of the inner wall of the pipe forming the exhaust gas discharge flow path 22. A cleaning water supply unit 25 and a gas-liquid separator 26 are provided in the pipe forming the downstream portion. The cleaning water supply unit 25 is a device capable of supplying cleaning water to the exhaust gas discharge flow path 22. In this embodiment, the cleaning water supply unit 25 is capable of supplying water vapor as cleaning water to the exhaust gas discharge flow path 22. Examples of the cleaning water supply unit 25 that supplies water vapor include a bubbler-type humidifier, an ultrasonic humidifier, and a sprayer. The gas-liquid separator 26 is provided in the exhaust gas discharge flow path 22 downstream of the cleaning water supply position (the position where the cleaning water supply unit 25 is disposed). The gas-liquid separator 26 separates the exhaust off-gas flowing through the exhaust gas discharge flow path 22 into gas and liquid. The liquid separated by the gas-liquid separator 26 originates from the moisture and cleaning water contained in the exhaust off-gas. The gas separated by the gas-liquid separator 26 is discharged to the outside of the carbon dioxide capture system 1 via a portion of the exhaust gas discharge flow path 22 downstream of the position where the gas-liquid separator 26 is provided.

[0022] The drainage flow path 27 is a flow path for flowing the liquid separated by the gas-liquid separator 26. The drainage flow path 27 is provided with a concentration sensor 28. The concentration sensor 28 measures the concentration of the amine-based compound contained in the liquid flowing through the drainage flow path 27. The concentration sensor 28 corresponds to a concentration measuring unit that measures the concentration of the amine-based compound in the liquid separated from the gas-liquid separator 26.

[0023] The supply control unit 29 refers to information received from the pressure sensor 23, the temperature sensor 24, and the concentration sensor 28, and controls the supply of cleaning water by the cleaning water supply unit 25. The information referred to by the supply control unit 29 is the pressure and temperature in the pipes that form the exhaust gas discharge flow path 22, and the concentration of the amine-based compound contained in the liquid flowing through the drainage flow path 27. The control of the cleaning water supply unit 25 by the supply control unit 29 will be described in detail later.

[0024] A pressure sensor 33 and a temperature sensor 34 are provided in the piping that forms the portion of the mixed gas delivery flow path 32 downstream of the positions where the first mixed gas delivery valve 32a and the second mixed gas delivery valve 32b are provided. The pressure sensor 33 and the temperature sensor 34 measure the pressure and temperature in the piping that forms the mixed gas delivery flow path 32. In addition, a cleaning water supply unit 35 and a gas-liquid separator 36 are provided in the piping that forms the downstream portion. The cleaning water supply unit 35 is a device that can supply cleaning water to the mixed gas delivery flow path 32. In this embodiment, the cleaning water supply unit 35, like the cleaning water supply unit 25, can supply water vapor as cleaning water to the mixed gas delivery flow path 32. Like the cleaning water supply unit 25, the cleaning water supply unit 35 that supplies water vapor can be, for example, a bubbler humidifier, an ultrasonic humidifier, or a sprayer. The gas-liquid separator 36 is provided in the mixed gas delivery flow path 32 downstream of the supply position of the cleaning water (the position where the cleaning water supply unit 35 is arranged). The gas-liquid separator 36 separates the mixed gas flowing in the mixed gas delivery flow path 32 into gas and liquid. The liquid separated by the gas-liquid separator 36 originates from the moisture and cleaning water contained in the mixed gas. The gas separated by the gas-liquid separator 36 is recovered after passing through a portion of the mixed gas delivery flow path 32 downstream of the position where the gas-liquid separator 36 is provided. The recovered gas contains a high concentration of carbon dioxide. In this way, the carbon dioxide capture system 1 captures carbon dioxide from exhaust gas containing carbon dioxide.

[0025] The drainage flow path 37 is a flow path for flowing the liquid separated by the gas-liquid separator 36. A concentration sensor 38 is provided in the drainage flow path 37. The concentration sensor 38 measures the concentration of the amine-based compound contained in the liquid flowing through the drainage flow path 37. Like the concentration sensor 28, the concentration sensor 38 corresponds to a concentration measuring unit that measures the concentration of the amine-based compound in the liquid separated from the gas-liquid separator 36.

[0026] The supply control unit 39 controls the supply of cleaning water by the cleaning water supply unit 35 by referring to information received from the pressure sensor 33, the temperature sensor 34, and the concentration sensor 38. The information referred to by the supply control unit 39 is the pressure and temperature in the pipe forming the mixed gas delivery flow path 32, and the concentration of the amine-based compound contained in the liquid flowing through the drainage flow path 37.

[0027] 2 is an explanatory diagram showing the processes performed in each of the first recovery device 11 and the second recovery device 12. In each of the first recovery device 11 and the second recovery device 12, an adsorption process is performed in which exhaust gas is introduced into the first recovery device 11 and the second recovery device 12 to adsorb carbon dioxide onto the first adsorbent 11a and the second adsorbent 12a. Then, a desorption process is performed in which purge gas is introduced into the first recovery device 11 and the second recovery device 12 to desorb carbon dioxide from the first adsorbent 11a and the second adsorbent 12a. Specifically, when the adsorption process is performed in the first recovery device 11, a desorption process is performed in the second recovery device 12. Furthermore, when the desorption process is performed in the first recovery device 11, an adsorption process is performed in the second recovery device 12. That is, the control unit 10 controls the opening and closing of various valves so that different processes are repeatedly performed in each of the first recovery device 11 and the second recovery device 12.

[0028] When the adsorption process is performed in the first recovery device 11, the first exhaust gas supply valve 21a and the first exhaust gas discharge valve 22a are in an open state, and the second exhaust gas supply valve 21b and the second exhaust gas discharge valve 22b are in a closed state. In this state, carbon dioxide contained in the exhaust gas supplied to the first recovery device 11 via the exhaust gas supply passage 21 is adsorbed by the first adsorbent 11a. The remaining gas (exhaust off-gas) in the exhaust gas that has not been adsorbed is released to the outside of the carbon dioxide recovery system 1 via the exhaust gas discharge passage 22.

[0029] When the desorption step is performed in the first recovery vessel 11, the first purge gas supply valve 31a and the first mixed gas delivery valve 32a are open, and the second purge gas supply valve 31b and the second mixed gas delivery valve 32b are closed. In this state, the carbon dioxide adsorbed to the first adsorbent 11a is desorbed by the purge gas supplied to the first recovery vessel 11 via the purge gas supply passage 31. The mixed gas containing carbon dioxide then passes through the mixed gas delivery passage 32 and is recovered.

[0030] On the other hand, when the adsorption process or desorption process is performed in the second recovery vessel 12, various valves in the second recovery vessel 12 corresponding to the various valves in the first recovery vessel 11 are opened and closed, just as in the first recovery vessel 11 when the above-mentioned adsorption process and desorption process are performed.

[0031] Desorption of carbon dioxide from the adsorbent is promoted by heating. Therefore, when carbon dioxide is desorbed from each of the first adsorbent 11a and the second adsorbent 12a, each of the first adsorbent 11a and the second adsorbent 12a is heated to, for example, 60°C or higher. At this time, the amine-based compounds, which are organic substances supported on each of the first adsorbent 11a and the second adsorbent 12a, may volatilize due to heating and then adhere to the inner walls of the pipes forming the delivery flow paths (exhaust gas discharge flow path 22 and mixed gas delivery flow path 32) downstream of each of the first adsorbent 11a and the second adsorbent 12a. If such adhesion narrows the range through which gas can flow in these delivery flow paths, the pressure loss in these delivery flow paths increases.

[0032] FIG. 3 is an explanatory diagram showing the relationship between the inner diameter of the flow channel and pressure loss. The horizontal axis represents the inner diameter of the flow channel corresponding to the range within which gas can flow within the flow channel. The vertical axis represents pressure loss. FIG. 3 shows that the inner diameter and pressure loss of a flow channel formed in a straight, unbent flow channel when no amine-based compounds adhere to the inner wall are both set to 1. The graph shows that the pressure loss increases as the inner diameter of the flow channel decreases due to an increase in the amount of amine-based compounds adhered. As shown by point P in FIG. 3, a 3% reduction in the inner diameter of the flow channel increases the pressure loss by 20%. This increase in pressure loss increases the energy consumed to supply exhaust gas and purge gas to the first recovery unit 11 and the second recovery unit 12, respectively, and leads to instability of combustion and extinction of the flame in the gas emission source (e.g., a factory combustion furnace) that emits exhaust gas. In this regard, the carbon dioxide capture system 1 of the first embodiment suppresses an increase in pressure loss in the delivery flow channel by supplying cleaning water from the cleaning water supply units 25 and 35. It should be noted that devices that consume energy to supply exhaust gas and purge gas include a blower (not shown) and a vacuum pump (not shown).

[0033] 4 is a flowchart showing an example of the procedure for the cleaning water supply process. The cleaning water supply process is a process that is carried out to suppress an increase in pressure loss in the delivery flow path (the exhaust gas discharge flow path 22 and the mixed gas delivery flow path 32). The cleaning water supply process is repeatedly carried out when the adsorption process or desorption process is being carried out in the first recovery device 11 and the second recovery device 12. Here, the cleaning water supply process that is carried out for the exhaust gas discharge flow path 22 when the adsorption process is being carried out in the first recovery device 11 or the second recovery device 12 will be described.

[0034] When the cleaning water supply process is started, the supply control unit 29 determines whether an adhesion index value, which indicates the degree of adhesion of amine compounds in the exhaust gas discharge flow path 22, is greater than a threshold value (step S11). In this embodiment, the adhesion index value is the pressure inside the pipe forming the exhaust gas discharge flow path 22. That is, the pressure sensor 23 corresponds to an index value measurement unit that measures the adhesion index value. In step S11, the supply control unit 29 specifically determines whether the pressure value Pm inside the pipe measured by the pressure sensor 23 is greater than a pressure threshold value Ps. The pressure threshold value Ps is an arbitrary threshold value that is set to detect adhesion of amine compounds to the inner wall of the pipe forming the exhaust gas discharge flow path 22. It is desirable to set the pressure threshold value Ps in consideration of an upper limit of pressure loss that allows stable operation of the gas emission source, a target value of energy consumed to supply exhaust gas and purge gas to each of the first recovery device 11 and the second recovery device 12, etc. If it is determined that the value Pm is not greater than the pressure threshold value Ps (step S11: NO), the supply control section 29 ends the cleaning water supply process.

[0035] On the other hand, when it is determined that the value Pm is greater than the pressure threshold Ps, the supply control unit 29 controls the cleaning water supply unit 25 to start supplying cleaning water to the exhaust gas discharge flow path 22 (step S12). At this time, in this embodiment, the supply of water vapor as cleaning water is started. In this embodiment, the supply amount of cleaning water is assumed to be constant. In detail, the supply control unit 29 refers to the temperature measured by the temperature sensor 24 (the temperature of the inner wall of the pipe forming the exhaust gas discharge flow path 22) and controls the cleaning water supply unit 25 to start supplying water vapor with a dew point temperature equal to or higher than that temperature. Such water vapor condenses on the surface of the inner wall of the pipe forming the exhaust gas discharge flow path 22 to become liquid water, and is used to remove amine compounds adhering to the inner wall.

[0036] Next, the supply control unit 29 determines whether or not a time T has elapsed since executing step S12 (step S13). If it is determined that the time T has not elapsed (step S13: NO), the supply control unit 29 repeatedly executes step S13.

[0037] When it is determined that the time T has elapsed (step S13: YES), the supply control unit 29 determines whether the concentration value Cm of the amine-based compounds measured by the concentration sensor 28 is smaller than the concentration threshold Cs (step S14). Because amine-based compounds are water-soluble, the concentration of the amine-based compounds in the liquid flowing through the drainage flow path 27 increases after the supply of cleaning water to the exhaust gas discharge flow path 22 is started. In the cleaning water supply process, the process of step S14 is not executed until the time T has elapsed (step S13: YES) in order to wait for the concentration of the amine-based compounds in the liquid flowing through the drainage flow path 27 to increase sufficiently. In step S14, after the time T has elapsed since the supply of cleaning water was started, it is determined whether the amine-based compounds attached to the inner wall of the pipe forming the exhaust gas discharge flow path 22 have been sufficiently removed by the cleaning water, using as an index whether the value Cm is smaller than the concentration threshold Cs. In other words, the concentration threshold Cs is an arbitrary threshold value set to detect whether the amine-based compounds attached to the inner wall of the pipe forming the exhaust gas discharge flow path 22 have been sufficiently removed by the cleaning water. If it is determined that the value Cm is not smaller than the concentration threshold Cs (step S14: NO), that is, if the value Cm is equal to or greater than the concentration threshold Cs, the supply control unit 29 repeats step S14.

[0038] On the other hand, when it is determined that the value Cm is smaller than the concentration threshold Cs (step S14: YES), the supply control unit 29 controls the cleaning water supply unit 25 to stop the supply of cleaning water to the exhaust gas discharge flow path 22 (step S15). At this time, the cleaning water supply unit 25 stops the supply of cleaning water. In order to stop the supply of cleaning water when the amine-based compounds adhering to the inner wall are completely removed by the cleaning water, the concentration threshold Cs used in step S14 should be set to 0. Thereafter, the supply control unit 29 ends the cleaning water supply process.

[0039] Here, the cleaning water supply process performed for the exhaust gas discharge flow path 22 has been described. However, as described above, when the desorption process is being performed in the first recovery device 11 or the second recovery device 12, the cleaning water supply process for the mixed gas delivery flow path 32 is also performed. In this cleaning water supply process, a pressure sensor 33, a temperature sensor 34, a cleaning water supply device 35, a concentration sensor 38, and a supply control device 39 are used instead of the pressure sensor 23, the temperature sensor 24, the cleaning water supply device 25, the concentration sensor 28, and the supply control device 29 used in the cleaning water supply process performed for the exhaust gas discharge flow path 22. In this case, the pressure sensor 33, like the pressure sensor 23, corresponds to an index value measurement device that measures an adhesion index value. The pressure threshold value Ps (step S11) and the concentration threshold value Cs (step S14) used in the cleaning water supply process performed for the mixed gas delivery flow path 32 are set to values ​​different from the pressure threshold value Ps (step S11) and the concentration threshold value Cs (step S14) used in the cleaning water supply process performed for the exhaust gas discharge flow path 22.

[0040] In a cleaning water supply process (cleaning water supply process for the exhaust gas discharge passage 22) that is repeatedly performed during the adsorption process in one of the first recovery vessels 11 and the second recovery vessels 12 in response to the start of the adsorption process, the desorption process that is the next process after the adsorption process in that one of the recovery vessels will not be started unless it is determined that the value Pm is not greater than the pressure threshold value Ps (step S11: NO). Similarly, in a cleaning water supply process (cleaning water supply process for the mixed gas delivery passage 32) that is repeatedly performed during the desorption process in that one of the first recovery vessels 11 and the second recovery vessels 12 in response to the start of the desorption process, the adsorption process that is the next process after the adsorption process in that one of the recovery vessels will not be started unless it is determined that the value Pm is not greater than the pressure threshold value Ps (step S11: NO).

[0041] According to the carbon dioxide capture system 1 of the first embodiment described above, when the pressure value Pm in the pipe forming the exhaust gas discharge flow path 22 (mixed gas delivery flow path 32) is greater than the pressure threshold value Ps, cleaning water is supplied to the exhaust gas discharge flow path 22 (mixed gas delivery flow path 32). Because amine compounds are water-soluble, any amine compounds adhering to the inner wall of the pipe forming the exhaust gas discharge flow path 22 (mixed gas delivery flow path 32) are removed from the inner wall of the pipe forming the exhaust gas discharge flow path 22 (mixed gas delivery flow path 32) by the supplied cleaning water, thereby making it possible to suppress an increase in pressure loss in the exhaust gas discharge flow path 22 (mixed gas delivery flow path 32) due to the adhesion of amine compounds.

[0042] Furthermore, in the carbon dioxide capture system 1 of the first embodiment, since water vapor is used as the cleaning water, the supply of cleaning water can be carried out simultaneously with each of the adsorption step and the desorption step.

[0043] Second Embodiment 5 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system 2 according to a second embodiment of the present invention. The carbon dioxide capture system 2 of the second embodiment differs from the carbon dioxide capture system 1 of the first embodiment (see FIG. 1) mainly in that it is provided with flow paths 22D and 32D, and that liquid water is supplied as cleaning water.

[0044] Flow path 22D is a flow path branched off from position P2 (shown in FIG. 5) of exhaust gas discharge flow path 22. Flow path 22D also corresponds to a delivery flow path through which gas delivered from first recovery device 11 and second recovery device 12 flows. A valve 22d, a cleaning water supply unit 25d, and a gas-liquid separator 26d are provided in the piping forming flow path 22D. Valve 22d is capable of opening and closing flow path 22D. The cleaning water supply unit 25d and the gas-liquid separator 26d are similar to the cleaning water supply unit 25 and the gas-liquid separator 26. The gas-liquid separator 26d is connected to drainage flow path 27 together with gas-liquid separator 26. That is, in the second embodiment, drainage flow path 27 is a flow path for flowing the liquids separated by gas-liquid separator 26 and gas-liquid separator 26d. In addition, the flow path downstream of position P2 in the exhaust gas discharge flow path 22 is referred to as flow path 22C. The piping that forms the flow path 22C is provided with a valve 22c as well as the valve 22d. The opening and closing of the valves 22c and 22d is controlled by the control unit .

[0045] Flow path 32D is a flow path branched off from position P3 (shown in FIG. 5) of mixed gas delivery flow path 32. Flow path 32D also corresponds to a delivery flow path through which gas delivered from first recovery device 11 and second recovery device 12 flows. A valve 32d, a cleaning water supply unit 35d, and a gas-liquid separator 36d are provided in the piping forming flow path 32D. Valve 32d is capable of opening and closing flow path 32D. The cleaning water supply unit 35d and the gas-liquid separator 36d are similar to the cleaning water supply unit 35 and the gas-liquid separator 36. The gas-liquid separator 36d is connected to a drainage flow path 37 together with the gas-liquid separator 36. That is, in the second embodiment, drainage flow path 37 is a flow path for flowing the liquids separated by the gas-liquid separator 36 and the gas-liquid separator 36d. In addition, the flow path downstream of position P3 in the mixed gas delivery flow path 32 is referred to as flow path 32C. The piping that forms the flow path 32C is provided with a valve 32c as well as the valve 32d. The opening and closing of the valves 32c and 32d is controlled by the control unit 10.

[0046] In the carbon dioxide capture system 2 of the second embodiment, the flow path 22C and the flow path 22D are both gas flow paths for flowing exhaust off-gas downstream. The flow path 32C and the flow path 32D are both gas flow paths for flowing mixed gas downstream. Furthermore, each of the cleaning water supply units 25, 25d, 35, and 35d is capable of supplying liquid water as cleaning water. In the carbon dioxide capture system 2 of the second embodiment, a cleaning water supply process is executed for each of the flow paths 22C, 22D, 32C, and 32D. In the flow paths where cleaning water is supplied by the cleaning water supply process, the supply of exhaust off-gas and mixed gas from the upstream side is stopped. Specifically, for example, when cleaning water is supplied to the flow path 22D, the valve 22d is closed to stop the supply of exhaust off-gas from the first adsorbent 11a or the second adsorbent 12a. At this time, since liquid water is supplied as cleaning water through flow path 22D, it is difficult to circulate exhaust off-gas and mixed gas through it, so the supply of exhaust off-gas from the upstream side is stopped. On the other hand, the flow paths to which cleaning water is not supplied by the cleaning water supply process are used to circulate exhaust off-gas and mixed gas from the upstream side. In the carbon dioxide capture system 2 of the second embodiment, two gas flow paths are provided for flowing exhaust off-gas downstream and two gas flow paths are provided for flowing mixed gas downstream. Therefore, even if one of the two gas flow paths is being cleaned, the other gas flow path can be used to circulate exhaust off-gas and mixed gas from the upstream side downstream. In other words, carbon dioxide capture can continue even if one gas flow path is being cleaned.

[0047] In the carbon dioxide capture system 2 of the second embodiment described above, it is also possible to suppress an increase in pressure loss in each of the flow paths 22C, 22D, 32C, and 32D due to adhesion of the amine compound.

[0048] Furthermore, in the carbon dioxide capture system 2 of the second embodiment, liquid water is used as the wash water, and therefore the wash water used to clean each of the flow paths 22C, 22D, 32C, and 32D can be more easily recovered than when water vapor is used as the wash water as in the carbon dioxide capture system 1 of the first embodiment. In particular, when water vapor is used as the wash water, it is difficult to recover the wash water unless the water vapor is cooled and liquefied during separation in the gas-liquid separators 26, 26d, 36, and 36d. On the other hand, when liquid water is used as the wash water, there is no need to perform such cooling during separation in the gas-liquid separators 26, 26d, 36, and 36d, and therefore the wash water can be more easily recovered.

[0049] <Third embodiment> 6 is an explanatory diagram illustrating the configuration of a carbon dioxide capture system 3 according to a third embodiment of the present invention. The carbon dioxide capture system 3 of the third embodiment differs from the carbon dioxide capture system 1 of the first embodiment (see FIG. 1) mainly in that it does not include concentration sensor 28 and concentration sensor 38.

[0050] Fig. 7 is a flowchart showing the procedure of the cleaning water supply process in the third embodiment. The cleaning water supply process in the third embodiment differs from the cleaning water supply process in the first embodiment shown in Fig. 4 in that step S13 is not executed and step S14a is executed instead of step S14.

[0051] In the first embodiment, it is determined whether the concentration value Cm of the amine-based compounds measured by the concentration sensor 28 is smaller than the concentration threshold value Cs (step S14), and if it is determined that the value Cm is smaller than the concentration threshold value Cs (step S14: YES), the supply control unit 29 controls the wash water supply unit 25 to stop the supply of wash water to the exhaust gas discharge flow path 22 (step S15). On the other hand, in the third embodiment, the concentration sensor 28 and the concentration sensor 38 are not provided, and therefore the supply control unit 29 controls the wash water supply unit 25 to stop the supply of wash water in accordance with a determination based on the pressure (step S14a)

[0052] Step S14a will be described in detail. In the cleaning water supply process of the third embodiment, after the supply of cleaning water to the exhaust gas discharge flow path 22 is started (step S12), the supply control unit 29 determines whether (Ps-P0) / P0 is equal to or less than (Pm,v0-Pm,v) / Pm,v (step S14a). It should be noted that the amount of cleaning water supplied is also constant in this embodiment. P0 is the pressure value of the exhaust off-gas (or mixed gas) flowing through the pipe forming the flow path (the flow path that is the target of the cleaning water supply process) in a state where no amine-based compound adheres to the inner wall of the pipe. Ps is the pressure threshold Ps described in the first embodiment. Pm,v0 is the pressure value in the pipe measured by the pressure sensor 23 (or pressure sensor 33) when the supply of cleaning water starts. Pm,v is the current pressure value in the pipe measured by the pressure sensor 23 (or pressure sensor 33) while cleaning water is being supplied. That is, the value indicated by (Pm,v0-Pm,v) / Pm,v increases over time after the supply of cleaning water starts.

[0053] If it is determined that (Ps-P0) / P0 is not equal to or less than (Pm,v0-Pm,v) / Pm,v (step S14a: NO), that is, if (Ps-P0) / P0 is greater than (Pm,v0-Pm,v) / Pm,v, the supply control unit 29 repeatedly executes step S14a.

[0054] On the other hand, if it is determined that (Ps-P0) / P0 is equal to or less than (Pm,v0-Pm,v) / Pm,v (step S14a: YES), the supply control unit 29 controls the cleaning water supply unit 25 to stop the supply of cleaning water (step S15). At this time, the cleaning water supply unit 25 stops the supply of cleaning water. Thereafter, the supply control unit 29 ends the cleaning water supply process.

[0055] In the carbon dioxide capture system 3 of the third embodiment described above, it is also possible to suppress an increase in pressure loss in each of the flow paths 22C, 22D, 32C, and 32D due to adhesion of the amine compound.

[0056] Furthermore, the carbon dioxide capture system 3 of the third embodiment is not provided with concentration sensors 28 and 38, and a decision to stop the supply of cleaning water is made based on the value measured by pressure sensor 23 (or pressure sensor 33). Therefore, the cleaning water supply process can be operated without providing concentration sensors 28 and 38, and the cost required to construct the carbon dioxide capture system 3 can be reduced.

[0057] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0058] In the above-described embodiment, two collectors are provided, but the present invention is not limited to this and the carbon dioxide capture system may include three or more collectors.

[0059] In the above-described embodiment, the adhesion index value is determined by the pressure inside the pipe forming the flow path. However, this is not limiting. For example, the adhesion index value may be determined by the concentration of amine-based compounds in the liquid separated from the gas-liquid separator. The liquid used to measure the concentration does not originate from the cleaning water because it is measured before the start of cleaning water supply, but originates from moisture contained in the exhaust off-gas or the mixed gas. To ensure the amount of liquid originating from moisture contained in the mixed gas, it is preferable to use water vapor as the purge gas. Note that, when the concentration of amine-based compounds in the liquid separated from the gas-liquid separator is used as the adhesion index value, the concentration sensors 28 and 38 correspond to index value measurement units that measure the adhesion index value. Alternatively, concentration sensors may be provided as index value measurement units in the pipe forming the exhaust gas discharge flow path 22 and the pipe forming the mixed gas delivery flow path 32, and the adhesion index value may be determined by multiplying the exhaust off-gas (mixed gas) flow rate by the concentration of amine-based compounds measured by the concentration sensors.

[0060] In the above embodiment, it is determined whether the value Cm of the concentration of amine-based compounds measured by the concentration sensor 28 (38) is smaller than the concentration threshold Cs (step S14). If it is determined that the value Cm is smaller than the concentration threshold Cs (step S14: YES), the supply control unit 29 controls the wash water supply unit 25 to stop the supply of wash water to the exhaust gas discharge flow path 22 (step S15). However, this is not limited to this. For example, the supply control unit 29 may control the amount of wash water supplied in accordance with the difference between the value Cm and the concentration threshold Cs. That is, the supply control unit 29 may control the amount of wash water supplied so that it decreases as the difference between the value Cm and the concentration threshold Cs decreases. In such a case, the amount of wash water supplied is controlled in accordance with the difference between the value of the concentration of amine-based compounds in the liquid separated from the gas-liquid separator and the concentration threshold. Therefore, an appropriate amount of wash water can be supplied to the discharge flow path, compared to a configuration in which the amount of wash water supplied is always constant. Furthermore, when the difference between the value Cm and the concentration threshold Cs becomes equal to or smaller than the set threshold, the supply control unit 29 may control the cleaning water supply unit 25 to stop the supply of cleaning water. Note that, in the above description, an example has been described in which the concentration of the amine-based compounds in the liquid separated from the gas-liquid separator is used as the criterion for the supply of cleaning water, but the pH of the liquid separated from the gas-liquid separator may also be used as the criterion for the supply of cleaning water. Furthermore, the supply amount of cleaning water may be adjusted so that the value Cm of the concentration of the amine-based compounds measured by the concentration sensor 28 (38) remains constant, and as a result, the supply of cleaning water may be stopped by bringing the supply amount of cleaning water as close to 0 as possible.

[0061] In the above-described embodiment, the cleaning water supply process for the exhaust gas discharge passage 22 is performed when the adsorption process is being performed, and the cleaning water supply process for the mixed gas delivery passage 32 is performed when the desorption process is being performed. Also, in the cleaning water supply process, unless it is determined that the value Pm is not greater than the pressure threshold Ps (step S11: NO), the next adsorption process or the next desorption process is not started, but this is not limited to this. The cleaning water supply process for the exhaust gas discharge passage 22 and the cleaning water supply process for the mixed gas delivery passage 32 may be performed independently of the next adsorption process and the next desorption process.

[0062] In the third embodiment, (Ps-P0) / P0 is compared with (Pm,v0-Pm,v) / Pm,v in step S14a, but this is not limiting. The value compared with (Pm,v0-Pm,v) / Pm,v may be the sum of (Ps-P0) / P0 and ΔP. ΔP is a value that takes into account errors in the pressure value measured by pressure sensor 23 (or pressure sensor 33), and may be, for example, a value obtained by multiplying (Ps-P0) / P0 by 0.05.

[0063] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0064] The present invention can also be realized in the following forms. [Application example 1] A carbon dioxide capture system that captures carbon dioxide from exhaust gas containing carbon dioxide, a recovery vessel containing an adsorbent material carrying an amine compound capable of adsorbing carbon dioxide, into which the exhaust gas flows; a delivery flow path connected to the collector and through which gas delivered from the collector flows; an index value measuring unit that measures an adhesion index value that represents the degree of adhesion of the amine-based compound in the delivery flow path; a cleaning water supply unit capable of supplying cleaning water to the delivery flow path; a supply control unit that controls the supply of the cleaning water by the cleaning water supply unit, The supply control unit controls the cleaning water supply unit to start supplying the cleaning water to the delivery flow path when the adhesion index value is greater than a threshold value. [Application example 2] The carbon dioxide capture system according to Application Example 1, The cleaning water supply unit is capable of supplying water vapor as the cleaning water to the delivery passage. [Application example 3] The carbon dioxide capture system according to Application Example 1, The carbon dioxide capture system, wherein the cleaning water supply unit is capable of supplying liquid water as the cleaning water to the delivery flow path. [Application example 4] The carbon dioxide capture system according to any one of Application Examples 1 to 3, further comprising: a gas-liquid separator provided in the delivery flow path downstream of the supply position of the cleaning water; a concentration measuring unit for measuring the concentration of the amine compound in the liquid separated from the gas-liquid separator, The supply control unit controls the amount of cleaning water supplied in accordance with the difference between the concentration value and a concentration threshold value. [Explanation of symbols]

[0065] 1-3...Carbon dioxide capture system 10...Control unit 11...First collector 11a...first adsorbent 12...Second collector 12a...Second adsorbent 21...Exhaust gas supply passage 21a...First exhaust gas supply valve 21b...Second exhaust gas supply valve 22...Exhaust gas discharge passage 22C...flow path 22D...flow path 22a...First exhaust gas discharge valve 22b...Second exhaust gas discharge valve 22c...valve 22d...Valve 23...Pressure sensor 24...Temperature sensor 25... Cleaning water supply section 25d... Cleaning water supply section 26…Gas-liquid separator 26d…Gas-liquid separator 27…Drainage channel 28...Concentration sensor 29...Supply control unit 30...Dehumidifier 31... Purge gas supply passage 31a...First purge gas supply valve 31b...Second purge gas supply valve 32...Mixed gas delivery passage 32C...flow path 32D...flow path 32a...First mixed gas delivery valve 32b...Second mixed gas delivery valve 32c...valve 32d...valve 33...Pressure sensor 34...Temperature sensor 35... Cleaning water supply section 35d... Cleaning water supply section 36…Gas-liquid separator 36d…Gas-liquid separator 37…Drainage channel 38...Concentration sensor 39...Supply control unit

Claims

1. A carbon dioxide capture system that captures carbon dioxide from exhaust gas containing carbon dioxide, a recovery vessel containing an adsorbent material carrying an amine compound capable of adsorbing carbon dioxide, into which the exhaust gas flows; a delivery flow path connected to the collector and through which gas delivered from the collector flows; an index value measuring unit that measures an adhesion index value that represents the degree of adhesion of the amine-based compound in the delivery flow path; a cleaning water supply unit capable of supplying cleaning water to the delivery flow path; a supply control unit that controls the supply of the cleaning water by the cleaning water supply unit, The supply control unit controls the cleaning water supply unit to start supplying the cleaning water to the delivery flow path when the adhesion index value is greater than a threshold value.

2. 2. The carbon dioxide capture system of claim 1, The cleaning water supply unit is capable of supplying water vapor as the cleaning water to the delivery passage.

3. 2. The carbon dioxide capture system of claim 1, The carbon dioxide capture system, wherein the cleaning water supply unit is capable of supplying liquid water as the cleaning water to the delivery flow path.

4. The carbon dioxide recovery system according to claim 2 or claim 3, further comprising: a gas-liquid separator provided in the delivery flow path downstream of the supply position of the cleaning water; a concentration measuring unit for measuring the concentration of the amine compound in the liquid separated from the gas-liquid separator, The supply control unit controls the amount of cleaning water supplied in accordance with the difference between the concentration value and a concentration threshold value.

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