Control device and control method of carbon dioxide recovery apparatus

Abstract

To conduct replacement or the like of an absorption solvent while maintaining a carbon dioxide recovery amount.SOLUTION: A control device of a carbon dioxide recovery apparatus includes: a model creating unit for creating a model which, in accordance with learning, predicts a degradation state of an absorption solvent in the carbon dioxide recovery apparatus, on the basis of data related to the carbon dioxide recovery apparatus; and a degradation period determining unit for determining a degradation period of the absorption solvent by applying the model created by the model creating unit. Further, the control device includes an arithmetic logical unit for calculating a replacement amount by which the absorption solvent is completely or partly replaced with a new absorption solvent, an additional amount of the new absorption solvent to be added to the absorption solvent, or a replenishment amount of an absorption solvent component with which the absorption solvent is replenished. In addition, the control device includes a controlling unit for controlling the carbon dioxide recovery apparatus, in accordance with the replacement amount, the additional amount, or the replenishment amount that were calculated by the arithmetic logical unit.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] An embodiment of the present invention relates to a control device and a control method for a carbon dioxide capture unit. [Background technology]

[0002] Carbon Dioxide Capture and Storage (CCS) technology has attracted attention as one of the effective measures against global warming. For example, studies are being conducted around the world on the application of CCS technology to facilities that generate large amounts of exhaust gas containing carbon dioxide (such as thermal power plants, steel mills, and cement plants).

[0003] One of the CCS technologies is the chemical absorption method, which separates and captures carbon dioxide by contacting exhaust gas containing carbon dioxide with an absorption solvent (absorption liquid). Examples of absorption solvents used in the chemical absorption method include silicone oil, amine-based solutions, and ionic solutions.

[0004] In some cases, operators of carbon capture equipment using CCS technology have set targets for the amount of carbon dioxide captured. In such cases, the equipment must be operated so that the amount of carbon dioxide captured does not fall below the target.

[0005] On the other hand, desulfurization devices are known that separate and recover sulfur compounds by contacting exhaust gas containing sulfur compounds such as sulfur dioxide with an absorption solvent, similar to carbon dioxide recovery devices. For example, a conventional control device that controls a desulfurization device predicts the sulfur dioxide concentration by performing machine learning on the relationship between the operating data, including the circulation flow rate of the absorption solvent, and the sulfur dioxide concentration at the outlet of the absorption tower. In this case, it is possible to keep the recovery amount of sulfur compounds constant by determining the circulation flow rate of the absorption solvent such that the predicted sulfur dioxide concentration is lower than a preset value.

[0006] However, when the absorbing solvent is used for a long period of time in a carbon dioxide capture device or a desulfurization device, the absorbing solvent components (e.g., amine components) in the absorbing solvent are discharged outside the device when recovering target gases such as carbon dioxide and sulfur compounds, resulting in a loss of the absorbing solvent components in the absorbing solvent. As a result, the concentration of the absorbing solvent components in the absorbing solvent gradually decreases. Therefore, when the operating time of the device increases, the recovery amount of the target gas begins to decrease at a certain point. However, the above-mentioned conventional control device does not perform control taking into account such a decrease in the recovery amount. If the recovery amount of the target gas decreases, there is a risk that the recovery amount of the target gas will fall below the target value.

[0007] In order to suppress such a decrease in the recovery amount, it is possible to periodically replace all or part of the absorption solvent in the device. Alternatively, instead of replacing the absorption solvent, it is possible to add absorption solvent to the device or to replenish the absorption solvent used in the device with an absorption solvent component. However, since the absorption solvent cost accounts for a high proportion of the operating cost of a carbon dioxide recovery device, in order to reduce the operating cost, it is desirable to use the absorption solvent without replacing it until just before the carbon dioxide recovery amount starts to decrease. Furthermore, in a carbon dioxide recovery device in which the entire amount of the absorption solvent is replaced during regular maintenance, if the carbon dioxide recovery amount starts to decrease before the regular maintenance, it is desirable to replace the absorption solvent to the minimum extent necessary to maintain the carbon dioxide recovery amount at a desired value until the regular maintenance. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7193261 Summary of the Invention [Problem to be solved by the invention]

[0009] As described above, when recovering carbon dioxide using an absorption solvent, it is necessary to replace the absorption solvent taking various circumstances into consideration.

[0010] In a carbon dioxide capture device, the concentration of the absorption solvent component in the absorption solvent decreases due to the following factors. First, the concentration of the absorption solvent component decreases when carbon dioxide is captured from the absorption solvent in the regeneration tower. Second, the concentration of the absorption solvent component decreases when condensed water generated in the carbon dioxide capture device is discarded to adjust the moisture concentration in the absorption solvent. Third, the concentration of the absorption solvent component decreases when the absorption solvent deteriorates depending on the operating conditions of the carbon dioxide capture device. In a carbon dioxide capture device, as the operating time of the device increases, the amount of carbon dioxide captured begins to decrease at a certain point.

[0011] Regarding the first and second factors, the decrease in concentration can be suppressed by controlling the operation of the carbon dioxide capture device and suppressing the loss of the absorption solvent components. On the other hand, regarding the third factor, it is difficult to suppress the decrease in concentration because the deterioration of the absorption solvent is unavoidable when the absorption solvent is used to capture carbon dioxide.

[0012] It has been confirmed that when the absorption solvent in the carbon dioxide capture device deteriorates, the amount of carbon dioxide captured tends to decrease rapidly. Therefore, the deterioration of the absorption solvent can be determined by measuring the amount of carbon dioxide captured. However, if the absorption solvent is replaced after a decrease in the amount of carbon dioxide captured is confirmed, the amount of carbon dioxide captured cannot be maintained at the desired value, which is a problem.

[0013] Therefore, an embodiment of the present invention provides a control device and a control method for a carbon dioxide capture apparatus that is capable of replacing an absorption solvent while maintaining the amount of carbon dioxide captured. [Means for solving the problem]

[0014] According to one embodiment, a control device for a carbon dioxide capture device includes a model creation unit that creates a model predicting a deterioration state of an absorption solvent in the carbon dioxide capture device by learning based on data related to the carbon dioxide capture device, and a deterioration time determination unit that determines a deterioration time of the absorption solvent using the model created by the model creation unit. The control device further includes a calculation unit that calculates a replacement amount for replacing all or a part of the absorption solvent with new absorption solvent, an additional amount of new absorption solvent to be added to the absorption solvent, or a replenishment amount of an absorption solvent component to be replenished to the absorption solvent, based on the deterioration time determined by the deterioration time determination unit. The control device further includes a control unit that controls the carbon dioxide capture device based on the replacement amount, the addition amount, or the replenishment amount calculated by the calculation unit. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing a configuration of a carbon dioxide capture device according to a first embodiment. [Diagram 2] 4 is a graph for explaining the operation of the carbon dioxide capture device of the first embodiment. [Diagram 3] 2 is a block diagram showing the configuration of a control device 15 according to the first embodiment. FIG. [Figure 4] 4 is a flowchart for explaining the operation of the control device 15 of the first embodiment. [Diagram 5] 4 is a graph for explaining the operation of the carbon dioxide capture device of the first embodiment. [Figure 6] 4 is a graph for explaining the operation of the carbon dioxide capture device of the first embodiment. [Figure 7] 10 is a flowchart for explaining the operation of a control device 15 according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In Fig. 1 to Fig. 7, the same components are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0017] (First embodiment) FIG. 1 is a schematic diagram showing the configuration of a carbon dioxide capture device according to the first embodiment.

[0018] As shown in FIG. 1, the carbon dioxide recovery apparatus of this embodiment includes an exhaust gas line 1, an oxygen remover 2, an absorption tower 3, a rich liquid pump 4, a regenerative heat exchanger 5, a regeneration tower 6, a reboiler 7, a lean liquid pump 8, a lean liquid cooler 9, a cooler 11, a gas-liquid separator 12, a cooler 13, a gas-liquid separator 14, and a control device 15.

[0019] An exhaust gas line 1 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 of this embodiment. The exhaust gas in the exhaust gas line 1 is sent to an absorption tower 3 via an oxygen remover 2.

[0020] The oxygen remover 2 is disposed on the exhaust gas line 1, and removes oxygen from the exhaust gas introduced into the oxygen remover 2 from the exhaust gas line 1. The exhaust gas from which oxygen has been removed by the oxygen remover 2 is introduced into the absorption tower 3 via the exhaust gas line 1.

[0021] The absorption tower 3 brings the exhaust gas into contact with an absorption solvent (lean liquid) to cause the carbon dioxide in the exhaust gas to be absorbed by the absorption solvent. The absorption tower 3 discharges the absorption solvent (rich liquid) that has absorbed the carbon dioxide from the bottom of the absorption tower 3. Meanwhile, the absorption tower exhaust gas containing the exhaust gas from which the carbon dioxide has been removed is discharged from the top of the absorption tower 3. The absorption solvent is, for example, an amine-based aqueous solution.

[0022] The rich liquid pump 4 sends the absorption solvent discharged from the absorption tower 3 to the regeneration tower 6 via the regenerative heat exchanger 5. At this time, the regenerative heat exchanger 5 exchanges heat between the absorption solvent flowing from the absorption tower 3 to the regeneration tower 6 and the absorption solvent flowing from the regeneration tower 6 to the absorption tower 3.

[0023] The regenerator 6 heats the absorption solvent (rich liquid) supplied from the absorption tower 3 to release carbon dioxide and water vapor from the absorption solvent. The regenerator 6 discharges the absorption solvent (lean liquid) from which carbon dioxide has been released, from the bottom of the regenerator 6. Meanwhile, the regenerator exhaust gas containing the released carbon dioxide and water vapor is discharged from the top of the regenerator 6.

[0024] The reboiler 7 takes in a portion of the absorption solvent discharged from the regeneration tower 6 and heats the absorbent. As a result, carbon dioxide and water vapor are released from the absorption solvent. The released carbon dioxide and water vapor are returned to the regeneration tower 6 together with the absorption solvent and come into contact with the absorption solvent in the regeneration tower 6. As a result, the absorption solvent in the regeneration tower 6 is heated, and carbon dioxide and water vapor are released from the absorption solvent in the regeneration tower 6.

[0025] The lean liquid pump 8 sends another part of the absorption solvent discharged from the regeneration tower 6 to the absorption tower 3 via the regeneration heat exchanger 5 and the lean liquid cooler 9. At this time, the regeneration heat exchanger 5 exchanges heat between the absorption solvent flowing from the regeneration tower 6 to the absorption tower 3 and the absorption solvent flowing from the absorption tower 3 to the regeneration tower 6. Furthermore, the lean liquid cooler 9 cools the absorption solvent flowing from the regeneration tower 6 to the absorption tower 3, and supplies the cooled absorption solvent to the absorption tower 3.

[0026] The cooler 11 cools the absorber exhaust gas discharged from the absorber 3. As a result, the water vapor contained in the absorber exhaust gas is condensed and turns into condensed water. The gas-liquid separator 12 separates the condensed water from the absorber exhaust gas and returns the separated condensed water to the absorber 3. The absorber exhaust gas discharged from the gas-liquid separator 12 is a treated gas whose main component is exhaust gas from which carbon dioxide has been removed, and is released into the atmosphere.

[0027] The cooler 13 cools the regeneration tower exhaust gas discharged from the regeneration tower 6. As a result, the water vapor contained in the regeneration tower exhaust gas is condensed and changes into condensed water. The gas-liquid separator 14 separates the condensed water from the regeneration tower exhaust gas and returns the separated condensed water to the regeneration tower 6. The regeneration tower exhaust gas discharged from the gas-liquid separator 14 is a recovered gas mainly composed of carbon dioxide recovered from the exhaust gas.

[0028] The control device 15 controls various operations of the carbon dioxide capture device of this embodiment. For example, the control device 15 controls a replacement process for replacing all or part of the absorption solvent in the carbon dioxide capture device of this embodiment with new absorption solvent. Further details of the control device 15 will be described later.

[0029] FIG. 2 is a graph for explaining the operation of the carbon dioxide capture device of the first embodiment.

[0030] In Figure 2, the horizontal axis represents time and the vertical axis represents CO 2 (Carbon dioxide) gas flow rate. CO shown in Figure 2 2 The gas flow rate is, for example, the CO 2 The curve C1 in Figure 2 represents the flow rate of CO 2 The graph shows the change in gas flow rate over time.

[0031] In this embodiment, when the absorption solvent in the carbon dioxide capture device deteriorates, 2 The gas flow rate drops sharply. In Figure 2, CO 2 The gas flow rate drops sharply from point P1 at time T1, which is called the breakpoint of performance of the absorption solvent.

[0032] FIG. 3 is a block diagram showing the configuration of the control device 15 of the first embodiment.

[0033] 3, the control device 15 includes a measurement unit 21, a database 22, a data import unit 23, a data preprocessing unit 24, a model creation unit 25, a deterioration time determination unit 26, an absorption solvent replacement amount calculation unit 27, and an absorption solvent replacement control unit 28. The database 22 is an example of a storage unit. The absorption solvent replacement amount calculation unit 27 is an example of a calculation unit. The absorption solvent replacement control unit 28 is an example of a control unit.

[0034] Hereinafter, the operation of the control device 15 will be described with reference to Fig. 3. In the following description, Figs. 4 to 6 will also be referred to as appropriate. Fig. 4 is a flowchart for explaining the operation of the control device 15 of the first embodiment. Figs. 5 and 6 are graphs for explaining the operation of the carbon dioxide capture device of the first embodiment.

[0035] [Measurement section 21] The carbon dioxide capture apparatus of this embodiment is equipped with a plurality of sensors that measure various data related to the carbon dioxide capture apparatus. These sensors measure, for example, the flow rate, pressure, and temperature of the absorbing solvent or gas in the carbon dioxide capture apparatus, the concentration of the absorbing solvent component (e.g., amine component) contained in the absorbing solvent in the carbon dioxide capture apparatus, and the liquid level of the absorbing solvent accumulated at the bottom of the absorption tower 3 or the regeneration tower 6. These sensors may also measure other physical quantities of the absorbing solvent or gas in the carbon dioxide capture apparatus. Such data is called plant data (or CCS data) of the carbon dioxide capture apparatus.

[0036] The measurement unit 21 measures plant data using these sensors. For example, the measurement unit 21 receives signals including the plant data from these sensors, thereby acquiring the plant data from these sensors.

[0037] The measurement unit 21 may measure other data. For example, the measurement unit 21 may measure the temperature, air pressure, humidity, and the like of the environment in which the carbon dioxide capture device is installed.

[0038] [Database 22] The database 22 stores the plant data measured by the measurement unit 21. The database 22 further stores start / stop information of devices (for example, the rich liquid pump 4 and the lean liquid pump 8) in the carbon dioxide capture device.

[0039] The database 22 may store other data. For example, the database 22 may store plant data measured by a user instead of the measurement unit 21, or may store operation data and control signals of the carbon dioxide capture device.

[0040] [Data Import Section 23] The data import unit 23 imports the plant data measured by the measurement unit 21 and the plant data stored in the database 22. The data import unit 23 can import current plant data from the measurement unit 21 and can import past plant data from the database 22.

[0041] The data acquisition unit 23 outputs the plant data acquired from the measurement unit 21 and the database 22 to the data pre-processing unit 24. Note that this plant data may be replaced with data including the plant data and other data. This also applies to the plant data that will appear in the following description.

[0042] [Data preprocessing unit 24] The data pre-processing unit 24 performs pre-processing on the plant data imported by the data import unit 23 before inputting the data to the model creation unit 25. The data pre-processing unit 24 inputs the pre-processed plant data to the model creation unit 25. Details of the pre-processing will be described below.

[0043] In general, the degree of deterioration of the absorption solvent in the carbon dioxide capture device changes depending on the operating conditions of the carbon dioxide capture device. For example, if the amount of exhaust gas supplied from the exhaust gas line 1 or the temperature of the equipment in the carbon dioxide capture device is changed without changing the amount of the absorption solvent used for separating and capturing carbon dioxide in the carbon dioxide capture device, the amount of carbon dioxide captured may change. Therefore, the deterioration of the absorption solvent needs to be determined based on the state of the carbon dioxide separation and capture process in the carbon dioxide capture device. Therefore, the data preprocessing unit 24 supplies plant data to the model creation unit 25 to enable accurate determination of the deterioration of the absorption solvent.

[0044] However, the carbon dioxide capture device measures plant data using sensors that includes many data items. Therefore, the plant data supplied to the data preprocessing unit 24 from the data import unit 23 includes various data items. It is difficult for a human being to accurately determine the effect that changes in the plant data of these data items have on the deterioration of the absorption solvent.

[0045] Therefore, the control device 15 of this embodiment predicts the deterioration time of the absorption solvent by applying AI (Artificial Intelligence) technology such as machine learning to the model creation unit 25. The data pre-processing unit 24 of this embodiment performs pre-processing on the plant data imported by the data import unit 23 in order to perform AI processing in the model creation unit 25. The pre-processing will be described in further detail below.

[0046] The plant data supplied to the data preprocessing unit 24 includes data that changes without affecting the deterioration of the absorption solvent. If plant data that does not affect the deterioration of the absorption solvent is included in the learning data for the AI ​​processing, it is considered that the prediction accuracy of the deterioration time of the absorption solvent will decrease.

[0047] Therefore, as preprocessing, the data preprocessing unit 24 selects plant data that affects the deterioration of the absorption solvent from the plant data supplied from the data import unit 23. Specifically, the data preprocessing unit 24 calculates correlation values ​​between the carbon dioxide recovery amount, which is the amount that changes when the absorption solvent deteriorates, and the plant data of various data items. Then, the data preprocessing unit 24 selects only plant data that is recognized to have a strong correlation from the plant data of these data items. The data preprocessing unit 24 supplies the selected process data to the model creation unit 25.

[0048] For example, the temperature of the absorption solvent, the temperature of the regenerator 6, the amount of plant wastewater discharged, etc. tend to have a strong correlation with the amount of carbon dioxide captured. However, it is considered that the plant data that exhibits a strong correlation will vary depending on the scale of the carbon dioxide capture apparatus and the characteristics of the equipment that supplies the exhaust gas. Therefore, the selection of plant data in this embodiment is not performed in common for multiple carbon dioxide capture apparatuses, but is performed individually for each carbon dioxide capture apparatus.

[0049] The data preprocessing unit 24 may use a method different from the above to select the plant data to be supplied to the model creation unit 25. Hereinafter, this process will be referred to as a selection process.

[0050] On the other hand, the plant data supplied to the data preprocessing unit 24 may contain outliers or missing data, which may cause errors when predicting the deterioration time of the absorption solvent.

[0051] Therefore, as preprocessing, the data preprocessing unit 24 removes data related to outliers and missing data from the plant data supplied from the data acquisition unit 23. The data preprocessing unit 24 supplies the process data from which the data related to outliers and missing data has been removed to the model creation unit 25.

[0052] For example, the data preprocessing unit 24 performs a test (e.g., Smirnoff-Grubbs test) to detect outliers in the process data, and removes data determined to be outliers from the process data. In addition, when missing data is found in some of the multiple data items selected by preprocessing, the data preprocessing unit 24 removes not only the process data of the data items with missing data, but also the process data of the data items with no missing data, for the period in which the missing data occurs. This is because removing only the process data of the data items with missing data will cause differences in the relationships between the data items.

[0053] The data pre-processing unit 24 may remove unnecessary data from the plant data by a method different from the above method. Hereinafter, this processing will be referred to as a removal processing (or a numerical processing).

[0054] The data pre-processing unit 24 of this embodiment selects plant data that affects the deterioration of the absorption solvent from the plant data supplied from the data import unit 23, and removes data related to outliers and missing data from the selected plant data. Then, the data pre-processing unit 24 of this embodiment supplies the plant data from which the data related to outliers and missing data has been removed to the model creation unit 25. The plant data supplied to the model creation unit 25 includes the current plant data imported from the measurement unit 21 and the past plant data imported from the database 22.

[0055] In addition, the data pre-processing unit 24 may perform only one of the selection process and the removal process instead of performing both the selection process and the removal process. In addition, the plant data supplied to the model creation unit 25 may include only one of the current plant data acquired from the measurement unit 21 and the past plant data acquired from the database 22.

[0056] [Model Creation Part 25] The model creation unit 25 creates a model that predicts the deterioration state of the absorption solvent in the carbon dioxide capture device through learning, based on the plant data input from the data pre-processing unit 24. The deterioration state of the absorption solvent is the state of the absorption solvent from the perspective of the deterioration of the absorption solvent. The model created by the model creation unit 25 is referred to as a CCS model. The model creation unit 25 creates a CCS model by using the input plant data as learning data for AI processing. The model creation unit 25 creates, for example, a CCS model that can reproduce the curve C1 shown in FIG. 2.

[0057] The process of creating a CCS model can be rephrased as the process of modeling a carbon dioxide capture device. Examples of modeling techniques include a modeling method that takes into account the effect of time on changes in training data, and a modeling method that takes into account the characteristics of training data when the training data is in a normal state.

[0058] The former method is applied, for example, when the prediction target fluctuates due to a large influence of the passage of time. The prediction target in this embodiment is, for example, the amount of carbon dioxide captured by a carbon dioxide capture device and the deterioration time of the absorption solvent predicted from the amount of carbon dioxide captured. The amount of carbon dioxide captured usually shows a constant value and decreases rapidly when the absorption solvent deteriorates. Therefore, when predicting the deterioration time from the amount of carbon dioxide captured, the prediction result of the deterioration time is easily influenced by the period during which the amount of carbon dioxide captured shows a constant value. This may reduce the prediction accuracy of the deterioration time. According to this method, it is possible to suppress such a decrease in accuracy by performing modeling taking into account the influence of the passage of time on the change in the learning data.

[0059] On the other hand, the latter method makes it possible to determine the magnitude of deviation of the current plant data from the plant data in the normal state by comparing the plant data in the normal state with the current plant data. This method is applied, for example, to determining anomalies in the current plant data. As mentioned above, the deterioration of the absorption solvent may be influenced by various data items of plant data. This method makes it possible to predict the deterioration time by taking into account not only changes in the carbon dioxide capture amount but also changes in the plant data of various data items as the deterioration of the absorption solvent progresses.

[0060] Representative examples of the modeling method include HBOD (Histogram-Based Outlier Detection), PCA (Principal Component Analysis), KNN (K-Nearest Neighbors Detector), etc. The model creation unit 25 may use any of the methods depending on the characteristics of the plant data in the carbon dioxide capture apparatus of this embodiment.

[0061] [Deterioration time determination unit 26] The deterioration time determination unit 26 determines the deterioration time of the absorbing solvent in the carbon dioxide capture device by using the CCS model created by the model creation unit 25. For example, the deterioration time determination unit 26 determines the deterioration time of the absorbing solvent according to the flow shown in Fig. 4. The details of Fig. 4 will be described later.

[0062] The deterioration time determination unit 26 calculates an abnormality determination score indicating the deterioration state of the absorption solvent using the CCS model. The abnormality determination score is, for example, a numerical value indicating the magnitude of deviation of the current plant data from the plant data in a normal state. In this embodiment, the deterioration state of the absorption solvent is quantified as the abnormality determination score. This process is shown in step S1 of FIG. 4.

[0063] Figure 5 shows the CO in the carbon dioxide capture device, similar to Figure 2. 2 5 shows a curve C1 indicating a change in gas flow rate over time. FIG. 5 further shows a curve C2 indicating an example of a change in the abnormality judgment score over time. The deterioration time judgment unit 26 judges the deterioration time of the absorption solvent based on the abnormality judgment score. The deterioration time judgment unit 26 calculates the abnormality judgment score by adopting, for example, a calculation method for the abnormality judgment score in the modeling method used by the model creation unit 25.

[0064] The abnormality judgment score in this embodiment is calculated using plant data of a plurality of data items. Specifically, a score indicating the magnitude of deviation of the current plant data from the plant data in a normal state is calculated for each data item. Next, the average value of the scores of the plurality of data items is calculated. The deterioration time judgment unit 26 in this embodiment adopts this average value as the abnormality judgment score. The deterioration time judgment unit 26 in this embodiment calculates the abnormality judgment score based on the current plant data measured by the measurement unit 21 and the data output from the CCS model. The normal state plant data used at this time may be the current plant data measured by the measurement unit 21, may be past plant data stored in the database 22, or may be plant data derived based on the current plant data and / or the past plant data. The deterioration time judgment unit 26 in this embodiment uses the plant data preprocessed by the data preprocessing unit 24 as the current plant data and / or the past plant data.

[0065] The abnormality determination score is often higher as the deterioration of the absorption solvent increases. However, immediately after the start of the deterioration time determination, the abnormality determination score is high because the normal data (plant data in a normal state) of each data item has not been determined. Therefore, if the deterioration time is determined by simply comparing the abnormality determination score with a threshold value, it is erroneously determined that the absorption solvent has already deteriorated immediately after the deterioration time determination is started. In general, when an unused absorption solvent is started to be used for carbon dioxide recovery, the deterioration of the absorption solvent does not become significant for a while after the start of use of the absorption solvent. Therefore, in this embodiment, the deterioration time determination based on the abnormality determination score is stopped during this period. Then, the deterioration time determination is started from the point when the abnormality determination score decreases and becomes constant. This process is shown in steps S2 and S11 of FIG. 4.

[0066] In addition, even after the abnormality determination score becomes constant, it is expected that the abnormality determination score will vary depending on the operating conditions of the carbon dioxide capture device. Such noise may cause an erroneous determination that the absorption solvent has deteriorated. Therefore, in this embodiment, moving average processing is performed on the abnormality determination score, and it is determined whether the abnormality determination score (moving average score) after the moving average processing is constant. If the moving average score is constant, the deterioration time is not determined. On the other hand, if the moving average score is not constant, the deterioration time is determined. This processing is shown in steps S3, S4, and S12 of FIG. 4.

[0067] When determining the deterioration time, it is determined whether the abnormality determination score exceeds a preset threshold value. If it is determined that the abnormality determination score is less than the threshold value, the deterioration time determination unit 26 determines that the absorption solvent has not yet deteriorated and does not determine the deterioration time. On the other hand, if it is determined that the abnormality determination score is equal to or greater than the threshold value, the deterioration time determination unit 26 determines the deterioration time. The deterioration time determination unit 26 may present the determined deterioration time, for example, on the screen of a display device electrically connected to the control device 15. This process is shown in steps S5, S13, and S14 of FIG. 4.

[0068] In FIG. 5, the abnormality judgment score increases from point P2 at time T2. Since the abnormality judgment score indicates the magnitude of deviation of the current plant data from the plant data in a normal state, a phenomenon like point P2 appears in the abnormality judgment score as a sign of deterioration of the absorbing solvent. In FIG. 5, at time T1, which is later than time T2, a CO 2A decrease in the gas flow rate occurs. In this embodiment, when such a sign appears in the abnormality determination score at a certain time (here, time T2), deterioration of the absorbing solvent is detected at a certain time thereafter (here, time T1). Therefore, the deterioration time determination unit 26 of this embodiment detects a sign related to deterioration of the absorbing solvent based on the abnormality determination score, and determines the deterioration time of the absorbing solvent based on the detected sign. For example, the deterioration time determination unit 26 detects point P2 as the sign, and calculates a predicted value of time T1 from time T2 at which point P2 occurred. In this case, this predicted value becomes the deterioration time of the absorbing solvent.

[0069] The rate at which the deterioration of the absorption solvent progresses is considered to differ depending on the scale and characteristics of the carbon dioxide capture device. The tendency for signs of deterioration of the absorption solvent to appear is also considered to differ depending on the scale and characteristics of the carbon dioxide capture device. Therefore, it is desirable to confirm the period during which the deterioration time can be determined and the rules for predicting the deterioration time from the signs during the trial run of each carbon dioxide capture device. For example, the rules for calculating the predicted value of time T1 from time T2 may be automatically set by the deterioration time determination unit 26 or the like during the trial run of the carbon dioxide capture device.

[0070] [Absorption solvent replacement amount calculation unit 27] The absorption solvent replacement amount calculation unit 27 calculates a replacement amount for replacing all or part of the absorption solvent in the carbon dioxide capture apparatus with new absorption solvent based on the deterioration time determined by the deterioration time determination unit 26. Hereinafter, the absorption solvent replacement amount calculation unit 27 is abbreviated as "calculation unit 27". When an absorption solvent is added instead of replacing the absorption solvent, the calculation unit 27 calculates an additional amount of new absorption solvent to be added to the absorption solvent in the carbon dioxide capture apparatus. When an absorption solvent component is replenished instead of replacing the absorption solvent, the calculation unit 27 calculates a replenishment amount of the absorption solvent component to be replenished to the absorption solvent in the carbon dioxide capture apparatus. The "replacement amount" that appears in the following description can be replaced with "addition amount" or "replenishment amount".

[0071] The calculation unit 27 calculates the replacement amount of the absorption solvent based on the deterioration time determined by the deterioration time determination unit 26 and the scheduled maintenance time of the carbon dioxide capture device. The scheduled maintenance time means the time when maintenance of the carbon dioxide capture device is scheduled to be performed. In this embodiment, the scheduled maintenance time is also called the maintenance implementation date or maintenance timing (see FIG. 6). On the other hand, the deterioration prediction timing shown in FIG. 6 means the timing when the deterioration time of the absorption solvent is predicted (determined). The scheduled maintenance time in this embodiment is the time when regular maintenance of the carbon dioxide capture device is scheduled to be performed. In this embodiment, at the time of regular maintenance of the carbon dioxide capture device, the entire amount of the absorption solvent in the carbon dioxide capture device is replaced with new absorption solvent (full amount replacement). The calculation unit 27 in this embodiment is capable of acquiring information on the scheduled maintenance time of the carbon dioxide capture device before the maintenance is performed.

[0072] FIG. 6(a) shows a case where the deterioration time (point P1) determined by the deterioration time determination unit 26 is before the maintenance implementation date. When the calculation unit 27 determines that the deterioration time will come before the maintenance implementation date, it calculates the minimum necessary replacement amount of the absorbing solvent in order not to reduce the amount of carbon dioxide captured from the current time until the maintenance implementation date. In this case, at or near the deterioration time, a part of the absorbing solvent in the carbon dioxide capture device is replaced with new absorbing solvent by the calculated replacement amount. The reason why only the minimum necessary amount is replaced is because the entire amount is replaced on the maintenance implementation date. If an amount more than the minimum necessary is replaced, the non-deteriorated absorbing solvent is replaced by the entire amount, resulting in waste. However, the calculation unit 27 may calculate a replacement amount of the absorbing solvent that is more than the minimum necessary when there is little waste or when waste is not a problem. After calculating the replacement amount, the calculation unit 27 may present the deterioration time of the absorbing solvent and the replacement amount of the absorbing solvent, for example, may be displayed on the above-mentioned screen. FIG. 6(b) shows a case where the CO 2This shows that the gas flow rate changes from curve C1 to curve C1', and the deterioration time (performance turning point) changes from point P1 to point P1'.

[0073] On the other hand, when the calculation unit 27 determines that the deterioration time comes after the maintenance implementation date, it sets the replacement amount of the absorbing solvent to zero. In this case, the replacement of the absorbing solvent in the carbon dioxide capture device will not be performed before the maintenance implementation date. After setting the replacement amount, the calculation unit 27 may present the deterioration time of the absorbing solvent and the replacement amount of the absorbing solvent (zero), for example, on the above-mentioned screen. Instead of presenting the replacement amount of zero, other information indicating that the replacement amount is zero may be presented.

[0074] In this way, the calculation unit 27 sets the replacement amount of the absorbing solvent to zero when the deterioration time is after the maintenance implementation date, and sets the replacement amount of the absorbing solvent to a value other than zero (a positive value) when the deterioration time is before the maintenance implementation date. Note that when the deterioration time is before the maintenance implementation date, the calculation unit 27 may calculate a replacement amount such that the entire amount of the absorbing solvent is replaced, instead of calculating a replacement amount such that a part of the absorbing solvent is replaced.

[0075] The minimum required replacement amount of the absorbing solvent is considered to differ depending on the scale and characteristics of the carbon dioxide capture apparatus. Therefore, it is desirable to confirm the rules for calculating the minimum required replacement amount of the absorbing solvent and the delay in the deterioration time caused by replacement of the absorbing solvent during the test run for each carbon dioxide capture apparatus. For example, the calculation unit 27 may create an arithmetic formula or decision table for calculating the minimum required replacement amount of the absorbing solvent based on data during the test run. The arithmetic formula or decision table may be created based on the past performance of a carbon dioxide capture apparatus of the same scale as the carbon dioxide capture apparatus of this embodiment. The arithmetic formula or decision table may be created outside the control device 15 and provided to the calculation unit 27.

[0076] [Absorption solvent replacement control unit 28] The absorption solvent replacement control unit 28 controls the carbon dioxide capture apparatus based on the replacement amount calculated by the calculation unit 27. Hereinafter, the absorption solvent replacement control unit 28 is abbreviated as "control unit 28". When an absorption solvent is added instead of replacing the absorption solvent, the control unit 28 controls the carbon dioxide capture apparatus based on the addition amount calculated by the calculation unit 27. When an absorption solvent component is replenished instead of replacing the absorption solvent, the control unit 28 controls the carbon dioxide capture apparatus based on the replenishment amount calculated by the calculation unit 27. The "replacement amount" that appears in the following description can be replaced with the "addition amount" or the "replenishment amount".

[0077] When the calculation unit 27 determines that the deterioration time comes before the maintenance date, it calculates the minimum replacement amount of the absorbing solvent necessary to prevent a decrease in the carbon dioxide capture amount from the current time to the maintenance date. In this case, the control unit 28 controls the carbon dioxide capture device so that a part of the absorbing solvent in the carbon dioxide capture device is replaced with new absorbing solvent by the replacement amount at or near the deterioration time. For example, the control unit 28 drives a device for replacing the absorbing solvent (e.g., a pump) provided in the carbon dioxide capture device so that such replacement of the absorbing solvent is performed. As a result, a part of the absorbing liquid is replaced in the carbon dioxide capture device. Note that, when the calculation unit 27 calculates the replacement amount for the total replacement of the absorbing solvent, the control unit 28 controls the carbon dioxide capture device so that the total replacement of the absorbing solvent is performed.

[0078] This is also true when addition or replenishment is performed instead of replacement. When addition of absorbing solvent is performed instead of replacement of absorbing solvent, the control unit 28 controls the carbon dioxide capture apparatus so that new absorbing solvent is added to the absorbing solvent in the carbon dioxide capture apparatus by the above-mentioned additional amount at or near the above-mentioned deterioration time. Also, when replenishment of an absorbing solvent component is performed instead of replacement of the absorbing solvent, the control unit 28 controls the carbon dioxide capture apparatus so that the absorbing solvent component is replenished to the absorbing solvent in the carbon dioxide capture apparatus by the above-mentioned replenishment amount at or near the above-mentioned deterioration time.

[0079] On the other hand, when the calculation unit 27 determines that the deterioration time comes after the maintenance implementation date, it sets the replacement amount of the absorbing solvent to zero. In this case, the control unit 28 controls the carbon dioxide capture device so that the absorbing solvent in the carbon dioxide capture device is not replaced before the maintenance implementation date. This is also the case when addition or replenishment is performed instead of replacement.

[0080] In this way, when the deterioration time is after the maintenance implementation date, the control unit 28 does not perform the above replacement, addition, or replenishment, and when the deterioration time is before the maintenance implementation date, the control unit 28 performs the above replacement, addition, or replenishment. In this embodiment, two or more of the above replacement, addition, and replenishment may be performed.

[0081] As described above, the control device 15 of this embodiment creates a CCS model based on plant data, determines the deterioration time of the absorbing solvent using the CCS model, calculates the replacement amount of the absorbing solvent based on the deterioration time, and controls the replacement of the absorbing solvent based on the replacement amount. Therefore, according to this embodiment, it is possible to replace the absorbing solvent while maintaining the carbon dioxide capture amount. This makes it possible to reduce the operating costs of the carbon dioxide capture device, for example.

[0082] The carbon dioxide capture device controlled by the control device 15 may have a configuration different from that shown in FIG. 1. The control device 15 may be realized by a computer program or an electric circuit. For example, the control device 15 may be realized by installing a computer program recorded in a recording medium such as a non-volatile memory into a computer. The control performed by the control unit 28 may be performed by a human being instead, based on the replacement amount output from the calculation unit 27. The above also applies to a second embodiment described later.

[0083] Second embodiment The carbon dioxide capture apparatus of this embodiment has the configuration shown in Fig. 1, similar to the carbon dioxide capture apparatus of the first embodiment. Moreover, the control device 15 of this embodiment has the configuration shown in Fig. 3, similar to the control device 15 of the first embodiment. Hereinafter, the carbon dioxide capture apparatus and the control device 15 of this embodiment will be described in detail.

[0084] When the operating conditions of the equipment that supplies exhaust gas to the carbon dioxide capture unit change and the amount of exhaust gas supplied to the carbon dioxide capture unit increases, it is necessary to increase the amount of carbon dioxide captured by the carbon dioxide capture unit. In this case, measures such as increasing the amount of absorption solvent used in the carbon dioxide capture unit are taken.

[0085] For example, if such a situation occurs after the deterioration time determination unit 26 has determined the deterioration time of the absorbing solvent, the burden on the absorbing solvent increases compared to before the determination. Therefore, it is considered that the deterioration of the absorbing solvent starts earlier than the determined deterioration time. That is, point P1 shown in FIG. 6(a) may move to the left. As a result, point P1' shown in FIG. 6(a) may move to the left of the maintenance timing. This means that the carbon dioxide capture amount decreases before the maintenance implementation date. In this case, it becomes impossible to maintain the carbon dioxide capture amount.

[0086] Therefore, the deterioration time determination unit 26 of this embodiment sequentially determines the deterioration time of the absorption solvent. As a result, if the operating conditions of the carbon dioxide capture apparatus are changed after determining the deterioration time of the absorption solvent, the deterioration time determination unit 26 can re-determine the deterioration time of the absorption solvent by taking the change in the operating conditions of the carbon dioxide capture apparatus into consideration. The change in the operating conditions of the carbon dioxide capture apparatus can be taken into consideration, for example, by determining the deterioration time based on plant data measured by the measurement unit 21 after the change. The change in the operating conditions of the carbon dioxide capture apparatus can occur when the operating conditions of the equipment that supplies exhaust gas to the carbon dioxide capture apparatus change, as described above.

[0087] In this case, the calculation unit 27 of this embodiment recalculates the replacement amount, addition amount, or replenishment amount based on the deterioration time re-determined by the deterioration time determination unit 26. Furthermore, the control unit 28 of this embodiment controls the carbon dioxide capture device based on the replacement amount, addition amount, or replenishment amount recalculated by the calculation unit 27. This makes it possible to maintain the carbon dioxide capture amount even if the operating conditions of the carbon dioxide capture device are changed.

[0088] FIG. 7 is a flowchart for explaining the operation of the control device 15 of the second embodiment.

[0089] Fig. 7 shows the flow of the operation of the deterioration time determination unit 26 when re-determining the deterioration time of the absorbing solvent. Fig. 7 is a flowchart in which step S2 in Fig. 4 is replaced with step S2'.

[0090] In Figure 7, it is assumed that the absorption solvent was replaced before the deterioration time was re-evaluated. In this case, it is considered that the abnormality judgment score changed from increasing to decreasing when the absorption solvent was replaced. In addition, it is considered that the abnormality judgment score does not become sufficiently small because the properties of the absorption solvent after replacement are different from those of the absorption solvent before replacement due to the replacement of the absorption solvent.

[0091] Therefore, in step S2', instead of stopping the determination of the deterioration time based on the abnormality determination score for a predetermined period (see step S2), it is determined again whether the abnormality determination score has become constant after the absorption solvent is replaced. If it is determined that the abnormality determination score has become constant, step S3 is started.

[0092] According to this embodiment, even if the operating conditions of the carbon dioxide capture device are changed, it is possible to replace the absorption solvent while maintaining the carbon dioxide capture amount.

[0093] 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 device and method described in this specification can be implemented in various other forms. In addition, various omissions, substitutions, and modifications can be made to the forms of the device and method described in this specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to include such forms and modifications that fall within the scope and spirit of the invention. [Explanation of symbols]

[0094] 1: exhaust gas line, 2: oxygen remover, 3: absorption tower, 4: rich liquid pump, 5: regenerative heat exchanger, 6: regenerator, 7: reboiler, 8: lean liquid pump, 9: lean liquid cooler, 11: Cooler, 12: Gas-liquid separator, 13: cooler, 14: gas-liquid separator, 15: control device, 21: measurement unit, 22: database, 23: data acquisition unit, 24: data preprocessing unit, 25: model creation unit, 26: deterioration time determination unit, 27: Absorption solvent replacement amount calculation unit, 28: Absorption solvent replacement control unit

Claims

1. a model creation unit that creates a model for predicting a deterioration state of an absorption solvent in the carbon dioxide capture apparatus through learning based on data related to the carbon dioxide capture apparatus; a deterioration time determination unit that determines a deterioration time of the absorption solvent by using the model created by the model creation unit; a calculation unit that calculates a replacement amount for replacing all or a part of the absorption solvent with a new absorption solvent, an additional amount of new absorption solvent to be added to the absorption solvent, or a replenishment amount of an absorption solvent component to be replenished to the absorption solvent, based on the deterioration time determined by the deterioration time determination unit; and A control unit that controls the carbon dioxide capture device based on the replaced amount, the added amount, or the replenished amount calculated by the calculation unit; A control device for a carbon dioxide capture device comprising:

2. 2. The control device for a carbon dioxide capture apparatus according to claim 1, wherein the deterioration time determination unit calculates an abnormality determination score indicating a deterioration state of the absorption solvent using the model created by the model creation unit, and determines a deterioration time of the absorption solvent based on the abnormality determination score.

3. 3. The control device for a carbon dioxide capture apparatus according to claim 2, wherein the deterioration time determination unit detects a sign of deterioration of the absorption solvent based on the abnormality determination score, and determines a deterioration time of the absorption solvent based on the detected sign.

4. 2. The control device for a carbon dioxide capture device according to claim 1, wherein the calculation unit calculates the replacement amount, the addition amount, or the replenishment amount based on the deterioration time determined by the deterioration time determination unit and a scheduled maintenance time for the carbon dioxide capture device.

5. 5. The control device for a carbon dioxide capture device according to claim 4, wherein the calculation unit sets the replacement amount, the addition amount, or the replenishment amount to zero when the deterioration time is after the scheduled maintenance time, and sets the replacement amount, the addition amount, or the replenishment amount to a positive value when the deterioration time is before the scheduled maintenance time.

6. 5. The control device for a carbon dioxide capture device as described in claim 4, wherein the control unit does not perform the replacement, addition, or replenishment before the planned maintenance time if the deterioration time is after the planned maintenance time, and performs the replacement, addition, or replenishment before the planned maintenance time if the deterioration time is before the planned maintenance time.

7. 2. The control device for a carbon dioxide capture device according to claim 1, wherein the control unit controls the carbon dioxide capture device so that all or a part of the absorption solvent is replaced with the new absorption solvent by the replacement amount, or so that the new absorption solvent is added to the absorption solvent by the additional amount, or so that the absorption solvent is replenished with the absorption solvent component by the replenishment amount.

8. A measurement unit that measures data related to the carbon dioxide capture device; A storage unit that stores data related to the carbon dioxide capture device, The control device for a carbon dioxide capture apparatus according to claim 1 , wherein the model creation unit creates the model based on data measured by the measurement unit and data stored in the storage unit.

9. a data acquisition unit that acquires data measured by the measurement unit and data stored in the storage unit; a data pre-processing unit that performs pre-processing on the data imported by the data import unit before the data is input to the model creation unit, The control device for a carbon dioxide capture apparatus according to claim 8 , wherein the model creation unit creates the model by using the pre-processed data as learning data.

10. The control device for a carbon dioxide capture apparatus according to claim 9 , wherein the data pre-processing unit selects predetermined data from the data acquired by the data acquisition unit as the pre-processing.

11. The control device for a carbon dioxide capture device according to claim 10 , wherein the data preprocessing unit selects the predetermined data based on a correlation value between the data acquired by the data acquisition unit and an amount of carbon dioxide captured by the carbon dioxide capture device.

12. The control device for a carbon dioxide capture apparatus according to claim 9 , wherein the data pre-processing unit removes predetermined data from the data acquired by the data acquisition unit as the pre-processing.

13. The control device for a carbon dioxide capture apparatus according to claim 12 , wherein the predetermined data is data relating to outliers or missing values ​​in the data acquired by the data acquisition unit.

14. the deterioration time determination unit, when an operating condition of the carbon dioxide capture device is changed after determining the deterioration time of the absorption solvent, re-determines the deterioration time of the absorption solvent taking into account the change in the operating condition of the carbon dioxide capture device; The calculation unit recalculates the replacement amount, the addition amount, or the replenishment amount based on the deterioration time re-determined by the deterioration time determination unit, The control unit controls the carbon dioxide capture device based on the replaced amount, the added amount, or the replenishment amount recalculated by the calculation unit. The control device for a carbon dioxide capture device according to claim 1 .

15. A model creation unit creates a model that predicts a deterioration state of an absorption solvent in the carbon dioxide capture apparatus through learning based on data related to the carbon dioxide capture apparatus; A deterioration time determination unit determines a deterioration time of the absorbing solvent using the model created by the model creation unit; a calculation unit calculates, based on the deterioration time determined by the deterioration time determination unit, a replacement amount for replacing all or a part of the absorption solvent with a new absorption solvent, an addition amount of new absorption solvent to be added to the absorption solvent, or a replenishment amount of an absorption solvent component to be replenished to the absorption solvent, The carbon dioxide capture device is controlled by a control unit based on the replacement amount, the addition amount, or the replenishment amount calculated by the calculation unit. A method for controlling a carbon dioxide capture device, comprising:

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