Carbon dioxide collection system, carbon dioxide collection method, and carbon dioxide collection program

Abstract

To provide a carbon dioxide collection system capable of excellent measurement of absorption liquid.SOLUTION: According to one embodiment, a carbon dioxide collection system includes: an absorption unit configured to bring a gas to be processed containing carbon dioxide and absorption liquid containing an amine-based compound into contact with each other, and cause the absorption liquid to absorb the carbon dioxide; and a regeneration part configured to heat the absorption liquid having absorbed the carbon dioxide and cause the carbon dioxide to be released from the absorption liquid. The system further includes a plurality of measurement devices which measure two or more of pH, electric conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide collection device that includes the absorption part and the regeneration part. The system further includes: an absorption liquid refiner for refining the absorption liquid introduced by the carbon dioxide collection device and delivering the refined absorption liquid to the carbon dioxide collection device; and an information processor for controlling the absorption liquid refiner on the basis of two or more of the pH, the electric conductivity, and the carbon dioxide concentration.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION An embodiment of the present invention relates to a carbon dioxide capture system, a carbon dioxide capture method, and a carbon dioxide capture program. [Background technology]

[0002] In order to achieve the "2°C target" and "1.5°C ambitious target" for limiting global temperature rise set out in the Paris Agreement, countries are being called upon to accelerate their climate change measures. Among these, Carbon dioxide Capture, Utilization and Storage (CCUS), along with hydrogen and renewable energy, is highly anticipated as a measure to reduce carbon dioxide (CO2) emissions, which have a large greenhouse effect.

[0003] Chemical absorption is one method of capturing CO2. In this method, CO2-containing exhaust gas (hereinafter referred to as "exhaust gas") emitted from thermal power plants, steelworks, etc. is brought into contact with an absorbing solution, and the CO2 in the exhaust gas is absorbed by the absorbing solution. An example of an absorbing solution is an aqueous solution containing an amino group-containing compound (hereinafter referred to as "amine compound"). In a carbon dioxide capture device that employs the chemical absorption method, CO2 is captured from the exhaust gas by repeatedly circulating the absorbing solution between an absorption section, where the absorbing solution absorbs CO2, and a regeneration section, where the absorbing solution releases CO2.

[0004] However, when the absorption liquid absorbs CO2, nitrogen oxides (NO x ), sulfur oxides (SO xAcids such as thiocyanate, carbonyl sulfide, hydrogen cyanide, thiocyanic acid, and thiosulfuric acid react with amine compounds in the absorption solution to produce impurities called heat-stable amine salts (HSAS). Furthermore, heating to release CO2 from the absorption solution and reactions between oxygen in the exhaust gas and amine compounds can decompose or denature the amine compounds, promoting the production of heat-stable amine salts. Accumulation of heat-stable amine salts in the absorption solution not only reduces the CO2 absorption efficiency of the absorption solution, but can also cause corrosion of carbon dioxide capture equipment. Therefore, it is desirable to remove heat-stable amine salts from the absorption solution. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-128899 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-097982 [Patent Document 3] Patent No. 5919894 Summary of the Invention [Problem to be solved by the invention]

[0006] In carbon dioxide capture systems, inorganic acids resulting from exhaust gas and organic acids resulting from the decomposition of amine compounds accumulate in the absorption solution. An absorption solution purification system is one of the systems that removes acid components that can form heat-stable amine salts from the absorption solution. The timing for starting operation of the absorption solution purification system is determined, for example, based on the concentration of acid components in the absorption solution. Ion chromatography is widely used as a method for measuring the concentration of acid components in the absorption solution.

[0007] However, due to constraints imposed by the principles of ion chromatography and the configuration of an ion chromatography device, the process of measuring the concentration of acid components in an absorption solution using ion chromatography is rarely performed as online measurement, but is often performed as offline measurement. In online measurement, the concentration of acid components in an absorption solution is measured while the absorption solution is being used in the carbon dioxide capture device, for example, by measuring the concentration of acid components in the absorption solution flowing through an absorption solution pipe in the carbon dioxide capture device. On the other hand, in offline measurement, the concentration of acid components in an absorption solution is measured while the absorption solution is not being used in the carbon dioxide capture device, for example, by measuring the concentration of acid components in the absorption solution collected from the carbon dioxide capture device in an analysis room.

[0008] Therefore, when measuring the concentration of acid components in the absorption solution offline using ion chromatography, it is difficult to immediately determine whether or not to operate the absorption solution purification device unless the environment is one in which ion chromatography can be easily used. For example, if an analysis room is not installed near the carbon dioxide capture device, it takes a long time to perform the above offline measurement, and as a result, it takes a long time to determine whether or not to operate the absorption solution purification device.

[0009] Therefore, an embodiment of the present invention provides a carbon dioxide capture system, a carbon dioxide capture method, and a carbon dioxide capture program that can suitably perform measurements related to an absorption liquid. [Means for solving the problem]

[0010] According to one embodiment, a carbon dioxide capture system includes an absorption unit that contacts a gas to be treated containing carbon dioxide with an absorption liquid containing an amine compound to cause the carbon dioxide to be absorbed by the absorption liquid, and a regeneration unit that heats the absorption liquid that has absorbed the carbon dioxide to release the carbon dioxide from the absorption liquid. The system further includes a plurality of measuring devices provided in a carbon dioxide capture apparatus that includes the absorption unit and the regeneration unit, the measuring devices including two or more of a pH measuring device, an electrical conductivity measuring device, and a concentration measuring device that measure the pH, electrical conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide capture apparatus, respectively. The system further includes an absorption liquid purification device that purifies the absorption liquid introduced from the carbon dioxide capture apparatus and sends the purified absorption liquid to the carbon dioxide capture apparatus, and an information processing device that controls the absorption liquid purification device based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a carbon dioxide capture device 1 of a first embodiment. [Figure 2] 1 is a block diagram showing the configuration of a carbon dioxide capture system according to a first embodiment. [Figure 3] FIG. 10 is a block diagram showing the configuration of a carbon dioxide capture system according to a second embodiment. [Figure 4] FIG. 10 is a block diagram showing the configuration of a carbon dioxide capture system according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. In Figures 1 to 4, the same components are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0013] (First embodiment) FIG. 1 is a schematic diagram showing the configuration of a carbon dioxide capture device 1 of the first embodiment.

[0014] 1, the carbon dioxide recovery system 1 of this embodiment includes an exhaust gas line 11, an oxygen remover 12, an absorption section (absorption tower) 13, a rich liquid pump 14, a regenerative heat exchanger 15, a regeneration section (regeneration tower) 16, a reboiler 17, a lean liquid pump 18, a lean liquid cooler 19, a cooler 21, a gas-liquid separator 22, a cooler 23, a gas-liquid separator 24, and a control device 25. The carbon dioxide recovery system 1 of this embodiment further includes flow paths L1 to L5 for circulating various fluids.

[0015] An exhaust gas line 11 sends exhaust gas containing carbon dioxide from facilities such as a thermal power plant, a steel mill, and a cement factory to the carbon dioxide capture device 1 of this embodiment. The exhaust gas in the exhaust gas line 11 is sent to an absorption unit 13 via an oxygen remover 12. The exhaust gas is an example of a gas to be treated.

[0016] The oxygen remover 12 is disposed on the exhaust gas line 11 and removes oxygen from the exhaust gas introduced into the oxygen remover 12 from the exhaust gas line 11. The exhaust gas from which oxygen has been removed by the oxygen remover 12 is introduced into the absorption section 13 via the exhaust gas line 11.

[0017] The absorption unit 13 brings the exhaust gas into contact with an absorption liquid (lean liquid) to cause the carbon dioxide in the exhaust gas to be absorbed by the absorption liquid. The absorption unit 13 discharges the absorption liquid (rich liquid) that has absorbed the carbon dioxide from the bottom of the absorption unit 13. Meanwhile, the absorption unit exhaust gas containing the exhaust gas from which the carbon dioxide has been removed is discharged from the top of the absorption unit 13. An example of the absorption liquid is an aqueous solution containing an amine compound (amine aqueous solution).

[0018] The rich liquid pump 14 sends the absorption liquid discharged from the absorption section 13 to the regeneration section 16 via the regenerative heat exchanger 15. At this time, the regenerative heat exchanger 15 exchanges heat between the absorption liquid flowing from the absorption section 13 to the regeneration section 16 and the absorption liquid flowing from the regeneration section 16 to the absorption section 13. The absorption liquid flowing from the absorption section 13 to the regeneration section 16 flows through a flow path L1 (rich liquid line), and the absorption liquid flowing from the regeneration section 16 to the absorption section 13 flows through a flow path L2 (lean liquid line).

[0019] The regeneration section 16 heats the absorption liquid (rich liquid) supplied from the absorption section 13 to release carbon dioxide and water vapor from the absorption liquid. The regeneration section 16 discharges the absorption liquid (lean liquid) from which carbon dioxide has been released, from the bottom of the regeneration section 16. Meanwhile, the regeneration section exhaust gas containing the released carbon dioxide and water vapor is discharged from the top of the regeneration section 16.

[0020] The reboiler 17 takes in a portion of the absorption liquid discharged from the regeneration section 16 and heats the absorbent. As a result, carbon dioxide and water vapor are released from the absorption liquid. The released carbon dioxide and water vapor are returned to the regeneration section 16 together with the absorption liquid and come into contact with the absorption liquid in the regeneration section 16. As a result, the absorption liquid in the regeneration section 16 is heated, and carbon dioxide and water vapor are released from the absorption liquid in the regeneration section 16. In this way, the absorption liquid introduced into the regeneration section 16 from the absorption section 13 is regenerated in the regeneration section 16. The reboiler 17 is provided on flow path L3 (branch line) that leads from flow path L2 to the regeneration section 16.

[0021] The lean liquid pump 18 sends another portion of the absorbing liquid discharged from the regenerating section 16 to the absorbing section 13 via the regenerative heat exchanger 15 and the lean liquid cooler 19. At this time, the regenerative heat exchanger 15 exchanges heat between the absorbing liquid flowing from the regenerating section 16 to the absorbing section 13 and the absorbing liquid flowing from the absorbing section 13 to the regenerating section 16. Furthermore, the lean liquid cooler 19 cools the absorbing liquid flowing from the regenerating section 16 to the absorbing section 13, and supplies the cooled absorbing liquid to the absorbing section 13. In this way, the absorbing liquid circulates between the absorbing section 13 and the regenerating section 16.

[0022] The cooler 21 cools the absorber exhaust gas discharged from the absorber 13. As a result, water vapor contained in the absorber exhaust gas is condensed and converted into condensed water. The gas-liquid separator 22 separates the condensed water from the absorber exhaust gas and returns the separated condensed water to the absorber 13. The absorber exhaust gas discharged from the gas-liquid separator 22 is a treated gas mainly composed of exhaust gas from which carbon dioxide has been removed, and is released into the atmosphere. The cooler 21 and the gas-liquid separator 22 are provided on a flow path L4 that runs from the top of the absorber 13 toward a side portion near the top of the absorber 13.

[0023] The cooler 23 cools the regeneration section exhaust gas discharged from the regeneration section 16. As a result, the water vapor contained in the regeneration section exhaust gas is condensed and converted into condensed water. The gas-liquid separator 24 separates the condensed water from the regeneration section exhaust gas and returns the separated condensed water to the regeneration section 16. The regeneration section exhaust gas discharged from the gas-liquid separator 24 is a recovered gas whose main component is carbon dioxide recovered from the exhaust gas. The cooler 23 and the gas-liquid separator 24 are provided on a flow path L5 that runs from the top of the regeneration section 16 to the side near the top of the regeneration section 16.

[0024] The control device 25 controls various operations of the carbon dioxide capture device 1 of this embodiment. An example of the control device 25 is an information processing device such as a computer or a control panel. For example, the control device 25 controls the absorption of carbon dioxide in the absorption section 13, the release of carbon dioxide in the regeneration section 16, and the liquid delivery by the rich liquid pump 14 and the lean liquid pump 18.

[0025] The carbon dioxide capture device 1 of this embodiment may have a configuration different from the configuration shown in Fig. 1. For example, the carbon dioxide capture device 1 of this embodiment may further include components not shown in Fig. 1, or may not include some of the components shown in Fig. 1.

[0026] Next, the exhaust gas (gas to be treated) and the absorbing liquid of this embodiment will be described in further detail.

[0027] The exhaust gas in this embodiment is, for example, combustion exhaust gas discharged from a boiler or gas turbine in a thermal power plant, process exhaust gas generated in a steel mill, or combustion exhaust gas generated in an incineration plant. The carbon dioxide capture device 1 of this embodiment may also treat a gas to be treated other than exhaust gas. The gas to be treated is preferably cooled in a cooler and further subjected to treatments such as desulfurization and denitrification before being supplied to the carbon dioxide capture device 1 of this embodiment.

[0028] When the absorbent absorbs CO2 in the gas to be treated, organic acids and heat-stable amine salts accumulate in the absorbent. Organic acids are produced, for example, by the reaction of the absorbent with oxygen contained in the gas to be treated. Heat-stable amine salts are produced, for example, by the reaction of the absorbent with SO2 contained in the gas to be treated. x , NO x They are produced by the reaction of inorganic acids such as carbonyl sulfide, hydrogen cyanide, thiocyanic acid, and thiosulfuric acid with amine compounds. As a representative example, the reaction between alkanolamine and SO2 to produce a heat-stable amine salt is shown in formulas (1) to (5). Here, R represents hydrogen or an alkyl group (which may form a heterocycle).

[0029] SO2 + H2O = H2SO3 (1) H2SO3 + 1 / 2 O2 = H2SO4 (2) H2SO3+ 2RNHCHR'CH2OH = [RNH2CHR'CH2OH]2SO3...(3) [RNH2CHR'CH2OH]2SO3+ 1 / 2 O2= [RNH2CHR'CH2OH]2SO4...(4) H2SO4+ 2RNHCHR'CH2OH = [RNH2CHR'CH2OH]2SO4...(5) The absorbing liquid is preferably an amine-based aqueous solution containing an amine compound (hereinafter referred to as "amine") and water. Examples of amines include "primary amines" such as monoethanolamine and 2-amino-2-methyl-1-propanol, "secondary amines" such as diethanolamine and 2-methylaminoethanol, "tertiary amines" such as triethanolamine and N-methyldiethanolamine, "polyethylene polyamines" such as ethylenediamine, triethylenediamine, and diethylenetriamine, "cyclic amines" such as piperazines, piperidines, and pyrrolidines, "polyamines" such as xylylenediamine, and "amino acids" such as methylaminocarboxylic acid. The absorbing liquid may contain only one of these amines alone, or may contain a mixture of two or more of these amines. The absorbing liquid is, for example, an aqueous solution containing 10 to 70 wt % of an amine.

[0030] The absorbing liquid may contain a reaction accelerator for accelerating the chemical reaction. The absorbing liquid may also contain a nitrogen-containing compound for improving the absorption performance of acidic gases such as CO2 gas. The absorbing liquid may also contain an anticorrosion agent for preventing corrosion of the carbon dioxide recovery device 1. The absorbing liquid may also contain a defoaming agent for preventing foaming of the absorbing liquid, an antioxidant for preventing deterioration of the absorbing liquid, or a pH adjuster for adjusting the pH of the absorbing liquid. The absorbing liquid may contain compounds such as a reaction accelerator, a nitrogen-containing compound, an anticorrosion agent, an antifoaming agent, an antioxidant, and a pH adjuster in any proportion within a range that does not impair the effect of the absorbing liquid.

[0031] FIG. 2 is a block diagram showing the configuration of the carbon dioxide capture system of the first embodiment.

[0032] The carbon dioxide capture system of this embodiment includes a carbon dioxide capture device 1 shown in Fig. 1. The carbon dioxide capture system of this embodiment further includes an information processing device 2 and an absorbent refining device 3.

[0033] [Carbon dioxide capture device 1] The carbon dioxide recovery device 1 shown in Fig. 2 includes a pH measurement device 1a, an electrical conductivity measurement device 1b, and a concentration measurement device 1c in addition to the components shown in Fig. 1. The pH measurement device 1a, the electrical conductivity measurement device 1b, and the concentration measurement device 1c are examples of multiple measurement devices.

[0034] The pH measuring device 1a measures the pH of the absorbing solution in the carbon dioxide capture device 1 and outputs a signal including the measured pH value to the information processing device 2 via a transmission wiring. The pH measuring device 1a measures, for example, the pH of the absorbing solution present in the equipment of the carbon dioxide capture device 1 (for example, in the absorption section 13 or the regeneration section 16) or the pH of the absorbing solution flowing in the flow paths of the carbon dioxide capture device 1 (for example, in the flow paths L1 and L2). This makes it possible to measure the pH of the absorbing solution being used in the carbon dioxide capture device 1 by online measurement.

[0035] The electrical conductivity measuring device 1b measures the electrical conductivity of the absorbing solution in the carbon dioxide capture device 1 and outputs a signal including the measured value of electrical conductivity to the information processing device 2 via a transmission wiring. The electrical conductivity measuring device 1b measures, for example, the electrical conductivity of the absorbing solution present in the equipment of the carbon dioxide capture device 1 (for example, in the absorption unit 13 or the regeneration unit 16) and the electrical conductivity of the absorbing solution flowing in the flow paths of the carbon dioxide capture device 1 (for example, in the flow paths L1 and L2). This makes it possible to measure the electrical conductivity of the absorbing solution being used in the carbon dioxide capture device 1 by online measurement.

[0036] The concentration measuring device 1c measures the carbon dioxide concentration of the absorption liquid in the carbon dioxide capture device 1, and outputs a signal including the measured value of the carbon dioxide concentration to the information processing device 2 via the transmission wiring. Specifically, the concentration measuring device 1c measures the concentration of carbon dioxide dissolved in the absorption liquid. The concentration measuring device 1c measures, for example, the carbon dioxide concentration of the absorption liquid present in the equipment of the carbon dioxide capture device 1 (for example, in the absorption section 13 or the regeneration section 16) or the carbon dioxide concentration of the absorption liquid flowing in the flow path of the carbon dioxide capture device 1 (for example, in the flow path L1 or the flow path L2). This makes it possible to measure the carbon dioxide concentration of the absorption liquid being used in the carbon dioxide capture device 1 by online measurement. The concentration measuring device 1c is, for example, a total organic carbon (TOC) meter.

[0037] [Information processing device 2] The information processing device 2 executes various information processes related to the carbon dioxide capture system of this embodiment. Examples of the information processing device 2 are computers such as PCs (Personal Computers) and WSs (Work Stations). The information processing device 2 may be disposed outside the carbon dioxide capture device 1 as shown in FIG. 2, or alternatively, may be disposed inside the carbon dioxide capture device 1. For example, the information processing device 2 may be the control device 25 shown in FIG. 1, or may be a device different from the control device 25 shown in FIG. 1.

[0038] 2, the information processing device 2 includes a calculation unit 2a, a communication unit 2b, a display unit 2c, and an input unit 2d. The calculation unit 2a includes, for example, a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and a hard disk drive (HDD). The communication unit 2b includes, for example, a communication interface for performing wired or wireless communication with devices other than the information processing device 2, and a memory interface for inserting a recording medium such as a semiconductor memory. The display unit 2c includes, for example, a liquid crystal display and an indicator. The input unit 2d includes, for example, a keyboard and a mouse.

[0039] The communication unit 2b receives a signal including a measured value of pH, a signal including a measured value of electrical conductivity, and a signal including a measured value of carbon dioxide concentration via a transmission wiring. The calculation unit 2a acquires the measured values of pH, electrical conductivity, and carbon dioxide concentration from the communication unit 2b.

[0040] The calculation unit 2a controls the operation of the absorption liquid refiner 3 based on the acquired pH, electrical conductivity, and carbon dioxide concentration. Specifically, the calculation unit 2a calculates the concentration of the acid component in the absorption liquid based on the pH, electrical conductivity, and carbon dioxide concentration, and controls the operation of the absorption liquid refiner 3 based on the calculated concentration of the acid component. This makes it possible to measure (calculate) the acid component concentration of the absorption liquid being used in the carbon dioxide capture device 1 in a short time by online measurement, and to determine a control policy for the absorption liquid refiner 3 based on the acid component concentration in a short time.

[0041] In this embodiment, the calculation unit 2a stores in advance in a HDD a formula or table for calculating the acid component concentration from pH, electrical conductivity, and carbon dioxide concentration, and calculates the acid component concentration based on this formula or table. This makes it possible to calculate the acid component concentration in a short time by simple calculation. The calculation unit 2a may store in advance in the HDD information other than the formula or table for calculating the acid component concentration, as long as it can calculate the acid component concentration in a short time, similar to the formula or table. Furthermore, the calculated value of the acid component concentration by the calculation unit 2a may be a value with theoretically high accuracy, or may be a value equivalent to an estimated value that may contain error.

[0042] As shown in FIG. 2, the display unit 2c has a screen S for displaying various information. When the calculation unit 2a of this embodiment calculates the acid component concentration based on the pH, electrical conductivity, and carbon dioxide concentration, it outputs the calculated acid component concentration to the display unit 2c. As shown in FIG. 2, the display unit 2c displays the acid component concentration on the screen S. This makes it possible to notify the manager of the carbon dioxide capture system of the acid component concentration. The acid component concentration may be displayed using numbers or letters as shown in FIG. 2, or alternatively, may be displayed using a graphic (e.g., a graph). Furthermore, the calculation unit 2a may generate information other than the acid component concentration (e.g., an alert to the manager) based on the pH, electrical conductivity, and carbon dioxide concentration, and the display unit 2c may display this information on the screen S. This information is an example of predetermined information. The calculation unit 2a may remotely display the acid component concentration and other information on a screen of a device other than the information processing device 2.

[0043] The input unit 2d is used by the administrator to input information about the amine components and / or acid components in the absorbing solution into the information processing device 2. Examples of the information about the amine components include information about the types of amines contained in the amine components and information about the concentrations of each type of amine contained in the amine components. Examples of the information about the acid components include information about the types of acids contained in the acid components and information about the content ratios of multiple types of acids contained in the acid components. For example, the administrator inputs the types of organic acids and inorganic acids expected to accumulate in the absorbing solution and the content ratios of these organic acids and inorganic acids in the absorbing solution into the information processing device 2 in advance. The information input by the administrator is stored in the HDD. The calculation unit 2a of this embodiment calculates (estimates) the acid component concentration based on the pH, electrical conductivity, and carbon dioxide concentration acquired from the communication unit 2a and information stored in the HDD using the input unit 2d (e.g., the types and concentrations of amine components and the types and content ratios of acid components). This makes it possible to calculate the acid component concentration of the absorbing solution even if various acids are contained in the absorbing solution. The information stored in the HDD by the administrator may be changeable by the administrator at any time.

[0044] The information processing described above and below, which is performed by the information processing device 2, is realized by, for example, a computer program. For example, the function of the information processing device 2 to perform the information processing may be realized by installing a computer program recorded on a recording medium such as a non-volatile memory into the information processing device 2. The computer program may also be installed in the information processing device 2 by being downloaded to the information processing device 2 via a network. The computer program is an example of a carbon dioxide capture program.

[0045] Next, the pH, electrical conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide recovery device 1 will be described in further detail.

[0046] As a result of the investigation, it was found that the acid component concentration of the absorbing solution can be calculated using the measured value of the pH of the absorbing solution. When the acid component concentration of the absorbing solution is measured by ion chromatography, the acid component concentration is generally measured by offline measurement. On the other hand, the pH of the absorbing solution can be measured by online measurement using the pH measuring device 1a. As a result, by calculating the acid component concentration of the absorbing solution from the pH of the absorbing solution, it becomes possible to measure the acid component concentration by online measurement in a short time. According to this embodiment, by calculating the acid component concentration from the pH, it becomes possible to control the absorbing solution purification device 3 in real time based on the acid component concentration.

[0047] The same applies to the electrical conductivity and the carbon dioxide concentration. As a result of the investigation, it was found that the acid component concentration of the absorbing solution can be calculated using the measured value of the electrical conductivity of the absorbing solution, or that it can be calculated using the measured value of the carbon dioxide concentration of the absorbing solution. According to this embodiment, by calculating the acid component concentration from the electrical conductivity, it becomes possible to control the absorbing solution purifier 3 in real time based on the acid component concentration. Similarly, according to this embodiment, by calculating the acid component concentration from the carbon dioxide concentration, it becomes possible to control the absorbing solution purifier 3 in real time based on the acid component concentration.

[0048] However, the pH of the absorbing solution changes not only depending on the acid component concentration in the absorbing solution but also depending on the amine component concentration in the absorbing solution. Similarly, the electrical conductivity of the absorbing solution changes not only depending on the acid component concentration in the absorbing solution but also depending on the amine component concentration in the absorbing solution. Therefore, when the acid component concentration is calculated based only on the pH or only on the electrical conductivity, the calculated acid component concentration may be inaccurate.

[0049] Therefore, in this embodiment, the acid component concentration is calculated based on pH and electrical conductivity. As a result of investigation, it was found that the way in which pH changes depending on the amine component concentration and the way in which electrical conductivity changes depending on the amine component concentration are different from each other. Therefore, according to this embodiment, by calculating the acid component concentration based on pH and electrical conductivity, it is possible to reduce the influence of the amine component concentration on the calculated value of the acid component concentration, and it is possible to improve the accuracy of the calculated acid component concentration.

[0050] Similarly, the carbon dioxide concentration of the absorbing solution is also affected by the amine component concentration of the absorbing solution. This is because the ability of the absorbing solution to absorb carbon dioxide is mainly due to the amines in the absorbing solution. According to this embodiment, the acid component concentration is calculated based on the pH, electrical conductivity, and carbon dioxide concentration, thereby making it possible to further improve the accuracy of the calculated acid component concentration.

[0051] As described above, the input unit 2d is used by the administrator to input information about the amine components and / or acid components in the absorbing solution to the information processing device 2, and the calculation unit 2a calculates the acid component concentration based on the pH, electrical conductivity, and carbon dioxide concentration acquired from the communication unit 2a and the information stored in the HDD using the input unit 2d. According to this embodiment, the accuracy of the calculated acid component concentration can be further improved by calculating the acid component concentration based on the information about the amine components in the absorbing solution.

[0052] Although the acid component concentration in this embodiment is calculated based on pH, electrical conductivity, and carbon dioxide concentration, it may alternatively be calculated based on only two of pH, electrical conductivity, and carbon dioxide concentration. For example, the acid component concentration in this embodiment may be calculated using pH and electrical conductivity without using carbon dioxide concentration. In this case, the carbon dioxide recovery device 1 does not need to be equipped with the concentration measurement device 1c.

[0053] Carbon dioxide (CO2) is x or NO x is an acid, just like the above. Therefore, the acid component concentration calculated in this embodiment may be the concentration of an acid component containing carbon dioxide. In this case, the acid component concentration is the sum of the carbon dioxide concentration and the concentration of the acid component excluding carbon dioxide. On the other hand, the acid component concentration calculated in this embodiment may be the concentration of the acid component excluding carbon dioxide.

[0054] [Absorbent purification unit 3] The absorption liquid refiner 3 is connected to the carbon dioxide capture apparatus 1 by a flow path P for receiving and sending the absorption liquid. The absorption liquid refiner 3 introduces a portion of the absorption liquid used in the carbon dioxide capture apparatus 1 through the flow path P and refines the introduced absorption liquid. According to this embodiment, degradation products are removed from the absorption liquid by purifying the absorption liquid. Thereafter, the absorption liquid refiner 3 sends the purified absorption liquid to the carbon dioxide capture apparatus 1 through the flow path P. In this way, the purified absorption liquid is returned to the carbon dioxide capture apparatus 1. Note that the flow path P may separately include a flow path from the carbon dioxide capture apparatus 1 to the absorption liquid refiner 3 and a flow path from the absorption liquid refiner 3 to the carbon dioxide capture apparatus 1.

[0055] The operation of the absorbent refiner 3 is preferably controlled according to the concentrations of organic acids and inorganic acids accumulated in the absorbent. Therefore, the calculation unit 2a of this embodiment calculates the acid component concentration of the absorbent based on the pH, electrical conductivity, and carbon dioxide concentration of the absorbent, and controls the operation of the absorbent refiner 3 via the communication unit 2b based on the calculated acid component concentration. In Fig. 2, a signal for controlling the absorbent refiner 3 is output from the communication unit 2b to the absorbent refiner 3 via a transmission wiring.

[0056] The calculation unit 2a may determine the control content of the absorbent purifier 3 (e.g., whether to start or stop the operation of the absorbent purifier 3) based on the acid component concentration and output a signal indicating this control content to the absorbent purifier 3, or alternatively, may output a signal including the acid component concentration itself to the absorbent purifier 3. In the former case, the control unit in the absorbent purifier 3 controls the start or stop of the operation of the absorbent purifier 3 based on the control content indicated by the signal. In the latter case, the control unit in the absorbent purifier 3 determines the control content of the absorbent purifier 3 (e.g., whether to start or stop the operation of the absorbent purifier 3) based on the acid component concentration indicated by the signal and controls the start or stop of the operation of the absorbent purifier 3 based on this control content. In the latter case, not only the information processing device 2 but also the control unit in the absorbent purifier 3 correspond to examples of information processing devices that control the absorbent purifier 3.

[0057] In the following description, it is assumed that the control content of the absorbent refinement apparatus 3 is determined by the calculation unit 2a. However, the following description is also applicable to the case where the control content of the absorbent refinement apparatus 3 is determined by a control unit within the absorbent refinement apparatus 3.

[0058] The calculation unit 2a, for example, compares the acid component concentration with a reference value and controls the absorption liquid refiner 3 based on the result of this comparison. The reference value is stored in advance in the HDD of the calculation unit 2a. For example, when the acid component concentration is higher than the reference value, the operation of the absorption liquid refiner 3 is started. During operation of the absorption liquid refiner 3, the absorption liquid refiner 3 introduces the absorption liquid from the carbon dioxide capture apparatus 1, purifies the introduced absorption liquid, and returns the purified absorption liquid to the carbon dioxide capture apparatus 1. On the other hand, when the acid component concentration is lower than the reference value, the operation of the absorption liquid refiner 3 is stopped. During the stoppage of the absorption liquid refiner 3, the absorption liquid refiner 3 does not introduce or refine the absorption liquid.

[0059] The calculation unit 2a may control the absorption liquid purifier 3 so that the absorption liquid remaining in the absorption liquid purifier 3 after the operation of the absorption liquid purifier 3 is stopped is discharged to the carbon dioxide capture device 1 via the flow path P. This makes it possible to prevent the absorption liquid before or after purification from remaining in the absorption liquid purifier 3.

[0060] In addition, when the control content of the absorbing liquid refiner 3 is determined by a control unit in the absorbing liquid refiner 3, the reference value may be stored in advance in the absorbing liquid refiner 3, or the reference value stored in advance in the HDD of the calculation unit 2a may be provided to the absorbing liquid refiner 3 by attaching it to the above signal.

[0061] Next, the configuration of the absorbent purification device 3 will be described in further detail.

[0062] The absorption liquid purifier 3 can employ a distillation method, an electrodialysis method, an ion exchange method, etc. as a method for purifying the absorption liquid. These methods can remove heat-stable amine salts from the absorption liquid.

[0063] Distillation has the advantage of being able to remove both ionic degradants (such as organic and inorganic acids) and nonionic degradants (such as amines formed by decomposition of the original amine). However, distillation has the disadvantage of easily accelerating the degradation of certain amines (such as high-boiling-point amines) due to heat. Furthermore, distillation tends to be costly when performed under reduced pressure.

[0064] Electrodialysis and ion exchange have the advantages of being relatively easy to operate and being able to deal with problems involving high-boiling-point amines. However, they have the disadvantage of being unable to remove nonionic degradants. Furthermore, electrodialysis has the problem that it is not suitable for cases where the carbon dioxide concentration in the absorption solution is high, and the removal efficiency tends to decrease when the concentration of the degradants to be removed is low. On the other hand, ion exchange, like electrodialysis, has the problem of being unsuitable for cases where the carbon dioxide concentration in the absorption solution is high, and has the problem that it requires large amounts of water and chemicals to regenerate the ion exchange resin, which tends to result in a large amount of wastewater as industrial waste.

[0065] However, according to the present embodiment, the operation timing of the absorbent purifier 3 can be automatically managed using any reference value, and therefore, whichever method is adopted, it is possible to achieve suitable operation of the absorbent purifier 3. For example, it is possible to avoid operation in an inefficient state, suppress excessive deterioration and wastewater, and reduce operation costs such as labor costs.

[0066] As described above, the carbon dioxide capture system of this embodiment measures the pH, electrical conductivity, and carbon dioxide concentration of the absorbing solution in the carbon dioxide capture device 1, and calculates the acid component concentration and controls the absorbing solution refiner 3 based on the pH, electrical conductivity, and carbon dioxide concentration. Therefore, according to this embodiment, it is possible to preferably measure the pH, electrical conductivity, and carbon dioxide concentration of the absorbing solution online, and preferably calculate the acid component concentration and control the absorbing solution refiner 3 based on the online measurement, thereby making it possible to preferably perform measurements related to the absorbing solution.

[0067] (Second embodiment) FIG. 3 is a block diagram showing the configuration of the carbon dioxide capture system of the second embodiment.

[0068] The carbon dioxide capture system of this embodiment has the same components as those of the carbon dioxide capture system of the first embodiment. However, while the absorption liquid refinement apparatus 3 of the first embodiment is automatically controlled by the information processing device 2, the absorption liquid refinement apparatus 3 of this embodiment is manually controlled by an administrator of the carbon dioxide capture system.

[0069] In this embodiment, the manager views the acid component concentration displayed on the screen S of the display unit 2c. The manager controls the operation of the absorbent purifier 3 based on the acid component concentration. For example, when the acid component concentration is higher than the reference value, the manager operates the absorbent purifier 3 to start operation of the absorbent purifier 3. On the other hand, when the acid component concentration is lower than the reference value, the manager operates the absorbent purifier 3 to stop operation of the absorbent purifier 3. The reference value may be displayed on the screen S of the display unit 2c. Alternatively, the manager may control the operation of the absorbent purifier 3 without using the reference value. Alternatively, the manager may control the operation of the absorbent purifier 3 based on the above-mentioned alarm displayed on the screen S of the display unit 2c.

[0070] According to this embodiment, it is possible to suitably perform measurements related to the absorbing solution, such as measuring the pH, electrical conductivity, and carbon dioxide concentration of the absorbing solution by online measurement, and suitably calculating the acid component concentration based on the online measurement and controlling the absorbing solution purifier 3. In this embodiment, the calculation of the acid component concentration is performed automatically, and the control of the absorbing solution purifier 3 is performed manually.

[0071] (Third embodiment) FIG. 4 is a block diagram showing the configuration of a carbon dioxide capture system according to the third embodiment.

[0072] The carbon dioxide capture system of this embodiment has the same components as the carbon dioxide capture system of the second embodiment. However, whereas the transfer of the absorbing liquid between the carbon dioxide capture device 1 and the absorption liquid refinement device 3 of the second embodiment is performed automatically, the transfer of the absorbing liquid between the carbon dioxide capture device 1 and the absorption liquid refinement device 3 of this embodiment is performed manually.

[0073] In this embodiment, when the acid component concentration displayed on the screen S is higher than the reference value, the manager transfers part of the absorption liquid in the carbon dioxide capture apparatus 1 to the absorption liquid refiner 3. The transfer may be performed by any means, for example, the manager may open a valve between the carbon dioxide capture apparatus 1 and the absorption liquid refiner 3, or the manager may arrange for transportation means to carry the absorption liquid from the carbon dioxide capture apparatus 1 to the absorption liquid refiner 3. Thereafter, the manager starts operation of the absorption liquid refiner 3, and the absorption liquid is purified by the absorption liquid refiner 3. The absorption liquid refined by the absorption liquid refiner 3 is transferred to the carbon dioxide capture apparatus 1 in the same manner as in the transfer described above.

[0074] On the other hand, when the acid component concentration displayed on the screen S is lower than the reference value, the manager of this embodiment stops the operation of the absorption liquid refiner 3. In this case, the manager may discharge the absorption liquid remaining in the absorption liquid refiner 3 after the operation of the absorption liquid refiner 3 is stopped to the carbon dioxide capture apparatus 1. The discharge can be performed, for example, in the same manner as the transfer described above.

[0075] According to this embodiment, it is possible to suitably perform measurements related to the absorbing solution, such as measuring the pH, electrical conductivity, and carbon dioxide concentration of the absorbing solution by online measurement, and suitably calculating the acid component concentration based on the online measurement and controlling the absorbing solution purifier 3. In this embodiment, the calculation of the acid component concentration is performed automatically, and the control of the absorbing solution purifier 3 is performed manually.

[0076] The absorbing liquid purifier 3 of this embodiment may be arranged outside the carbon dioxide capture system, rather than within the carbon dioxide capture system. Furthermore, the purification of the absorbing liquid of this embodiment may be performed without using the absorbing liquid purifier 3. For example, the purification of the absorbing liquid of this embodiment may be performed in some facility capable of implementing the above-mentioned distillation method, electrodialysis method, or ion exchange method.

[0077] Furthermore, the information processing device 2 in the first to third embodiments may be an information device other than a PC or a WS, and may be, for example, a mobile device such as a tablet device. For example, by bringing the mobile device to the carbon dioxide capture site, the administrator in the second or third embodiment can grasp the acid component concentration at the carbon dioxide capture site using the mobile device, and can manually control the absorption liquid refinement device 3 while viewing the acid component concentration on site.

[0078] Although several embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel systems, methods, and programs described herein may be embodied in various other forms. Furthermore, various omissions, substitutions, and modifications may be made to the forms of the systems, methods, and programs described herein without departing from the spirit of the invention. The appended claims and their equivalents are intended to cover such forms and modifications that fall within the scope and spirit of the invention. [Explanation of symbols]

[0079] 1: carbon dioxide recovery device, 1a: pH measurement device, 1b: electrical conductivity measurement device, 1c: concentration measuring device, 2: information processing device, 2a: calculation unit, 2b: communication unit, 2c: display unit, 2d: input unit, 3: absorption liquid purification device, 11: exhaust gas line, 12: oxygen remover, 13: absorption section, 14: Rich liquid pump, 15: Regenerative heat exchanger, 16: Regeneration unit, 17: Reboiler, 18: Lean liquid pump, 19: Lean liquid cooler, 21: Cooler, 22: Gas-liquid separator, 23: Cooler, 24: Gas-liquid separator, 25: Control device

Claims

1. an absorption section that brings a gas to be treated containing carbon dioxide into contact with an absorption liquid containing an amine compound, and causes the carbon dioxide to be absorbed by the absorption liquid; a regeneration unit that heats the absorption liquid that has absorbed the carbon dioxide to release the carbon dioxide from the absorption liquid; a plurality of measuring devices provided in a carbon dioxide capture device including the absorption unit and the regeneration unit, the measuring devices including two or more of a pH measuring device, an electrical conductivity measuring device, and a concentration measuring device that measure the pH, electrical conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide capture device, respectively; an absorption liquid purification device that purifies the absorption liquid introduced from the carbon dioxide capture device and sends the purified absorption liquid to the carbon dioxide capture device; an information processing device that controls the absorption liquid purification device based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration; A carbon dioxide capture system comprising:

2. the plurality of measurement devices include the pH measurement device, the electrical conductivity measurement device, and the concentration measurement device; the information processing device controls the absorption liquid purification device based on the pH, the electrical conductivity, and the carbon dioxide concentration. The carbon dioxide capture system of claim 1 .

3. 2. The carbon dioxide capture system according to claim 1, wherein the information processing device calculates a concentration of an acid component in the absorption solution based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration, and controls the absorption solution purification device based on the concentration of the acid component.

4. 4. The carbon dioxide capture system according to claim 3, wherein the information processing device calculates the concentration of the acid component based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration, and information related to the amine compound and / or the acid component input to the information processing device.

5. the information about the amine compound is information about the type or concentration of the amine compound, The information about the acid component is information about the type of acid contained in the acid component, or information about the content ratio of multiple types of acids contained in the acid component. The carbon dioxide capture system of claim 4.

6. The carbon dioxide capture system according to claim 3 , wherein the information processing device compares the concentration of the acid component with a reference value and controls the absorbent refining device based on a result of the comparison.

7. The carbon dioxide capture system according to claim 3 , wherein the information processing device controls the start and / or stop of operation of the absorption liquid purification device based on the concentration of the acid component.

8. 8. The carbon dioxide capture system according to claim 7, wherein the information processing device controls the absorption liquid refinement device so that the absorption liquid remaining in the absorption liquid refinement device is discharged to the carbon dioxide capture device after operation of the absorption liquid refinement device is stopped.

9. The carbon dioxide capture system according to claim 1 , wherein the information processing device is a control device that controls the carbon dioxide capture device.

10. 2. The carbon dioxide capture system according to claim 1, wherein the information processing device generates predetermined information based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration, and displays the predetermined information on a screen.

11. 11. The carbon dioxide capture system according to claim 10, wherein the information processing device calculates a concentration of an acid component in the absorption liquid based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration, and displays the concentration of the acid component on the screen.

12. bringing a gas to be treated containing carbon dioxide into contact with an absorbing solution containing an amine compound in an absorption section, and causing the carbon dioxide to be absorbed by the absorbing solution; the absorption liquid that has absorbed the carbon dioxide is heated by a regeneration unit to release the carbon dioxide from the absorption liquid; a plurality of measuring devices provided in a carbon dioxide capture device including the absorption unit and the regeneration unit, the plurality of measuring devices including two or more of a pH measuring device, an electrical conductivity measuring device, and a concentration measuring device, measuring two or more of the pH, electrical conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide capture device; calculating a concentration of an acid component in the absorption liquid by an information processing device based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration; A carbon dioxide capture method comprising:

13. 13. The carbon dioxide capture method according to claim 12, further comprising controlling an absorption liquid purification device that purifies the absorption liquid introduced from the carbon dioxide capture device and sends the purified absorption liquid to the carbon dioxide capture device, based on the concentration of the acid component.

14. The carbon dioxide recovery method according to claim 13, wherein the absorbent refining device is controlled by the information processing device based on the concentration of the acid component.

15. an absorption section that brings a gas to be treated containing carbon dioxide into contact with an absorption liquid containing an amine compound, and causes the carbon dioxide to be absorbed by the absorption liquid; a regeneration unit that heats the absorption liquid that has absorbed the carbon dioxide to release the carbon dioxide from the absorption liquid; a plurality of measuring devices provided in a carbon dioxide capture device including the absorption unit and the regeneration unit, the measuring devices including two or more of a pH measuring device, an electrical conductivity measuring device, and a concentration measuring device that measure the pH, electrical conductivity, and carbon dioxide concentration of the absorption liquid in the carbon dioxide capture device, respectively; an absorption liquid purification device that purifies the absorption liquid introduced from the carbon dioxide capture device and sends the purified absorption liquid to the carbon dioxide capture device; A carbon dioxide capture program that causes an information processing device to execute information processing regarding a carbon dioxide capture system comprising: The information processing calculating a concentration of an acid component in the absorption solution based on two or more of the pH, the electrical conductivity, and the carbon dioxide concentration; controlling the absorption liquid purification device based on the concentration of the acid component; Carbon capture programs, including:

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