Control method and monitoring system

Abstract

The present invention provides a technique capable of appropriately detecting deterioration of an adsorbent provided in a carbon dioxide recovery device. The control method according to the present invention calculates the adsorption rate of a collection unit, which represents the performance thereof at adsorbing carbon dioxide, on the basis of the ratio of carbon dioxide concentration before and after a gas has passed through the collection unit (see fig. 1).

Description

Control method, monitoring system

[0001] The present invention relates to a technique for monitoring the performance of a carbon dioxide capture device that captures carbon dioxide from a gas.

[0002] CCUS (Carbon dioxide Capture, Utilization, and Storage) is a general term for technologies that capture and store carbon dioxide. Methods for capturing carbon dioxide include, for example, DAC (Direct Air Capture, which captures carbon dioxide in the air using an adsorption filter, etc.). When extracting carbon dioxide adsorbed to an adsorbent, parameters such as pressure and temperature are swung. For example, in the pressure swing method, carbon dioxide is captured from the air by repeating pressurized adsorption and reduced pressure desorption, and the captured carbon dioxide is then extracted from the adsorbent.

[0003] Patent Document 1 below describes a technology related to a carbon dioxide capture device. The document aims to provide a carbon dioxide capture device that can stably capture high-purity carbon dioxide over an extended period of time, and discloses the following technology (see abstract): The carbon dioxide capture device according to the present disclosure includes a carbon dioxide separator that is provided in a carbon dioxide-containing gas supply flow path and separates carbon dioxide using a separation membrane; a pressure reduction pump that reduces the pressure on the permeate side of the separation membrane via a first recovery gas flow path; a plurality of adsorbers filled with adsorbents for adsorbing carbon dioxide contained in the carbon dioxide-containing gas that has not permeated the separation membrane, the plurality of adsorbers alternately repeating the adsorption and regeneration steps, one of which undergoes an adsorption step while the other undergoes a regeneration step; a recovery pump that reduces the pressure in the adsorbers via a second recovery gas flow path to recover carbon dioxide from the adsorbents; and a controller that controls the capacity of the pressure reduction pump in accordance with the cumulative operating time of the recovery pump.

[0004] Japanese Patent Application Laid-Open No. 2022-161050

[0005] In the process of a carbon dioxide capture device capturing carbon dioxide through swing operation, the adsorbent deteriorates over time, gradually reducing the adsorption efficiency (adsorption rate). When the adsorption rate decreases, the desired amount of carbon dioxide cannot be obtained even when swing operation is performed. Therefore, it is desirable to detect the deterioration of the adsorbent in a timely manner. In conventional technologies such as Patent Document 1, how to detect the deterioration of the adsorbent has not been fully considered.

[0006] The present invention has been made in view of the above-mentioned problems, and aims to provide a technique that can appropriately detect deterioration of an adsorbent provided in a carbon dioxide capture device.

[0007] The control method according to the present invention calculates an adsorption rate, which indicates the ability of the trapping section to adsorb carbon dioxide, based on the ratio of carbon dioxide concentrations before and after the gas passes through the carbon dioxide trapping section.

[0008] The control method according to the present invention can provide a technology that can appropriately detect deterioration of the adsorbent provided in the carbon dioxide capture device. Other objects, configurations, advantages, etc. of the present invention will become clear from the description of the following embodiments.

[0009] 1 is a configuration diagram of a carbon dioxide capture device 1 and a monitoring system 2 according to Embodiment 1. FIG. 2 is a graph showing changes over time in carbon dioxide concentration detected by sensors 131 and 132, respectively.

[0010] 1 is a configuration diagram of a carbon dioxide capture device 1 and a monitoring system 2 according to a first embodiment of the present invention. The carbon dioxide capture device 1 is a device that captures carbon dioxide contained in a gas (for example, the atmosphere). The monitoring system 2 is a system that monitors the deterioration of an adsorbent provided in the carbon dioxide capture device 1.

[0011] The carbon dioxide capture device 1 includes a capture unit 11, a storage unit 12, and sensors 131 to 134. The capture unit 11 captures carbon dioxide using an adsorbent provided in the capture unit 111. The carbon dioxide captured by the capture unit 11 is sent to the storage unit 12, which stores the carbon dioxide. The sensors 131 to 134 will be described later.

[0012] The monitoring system 2 includes an acquisition unit 21 and a calculation unit 22. The acquisition unit 21 acquires values ​​detected by the sensors 131 to 134. The calculation unit 22 calculates the efficiency (adsorption rate) of carbon dioxide adsorption by the adsorbent included in the collection unit 111 based on the values ​​acquired by the acquisition unit 21. The calculation procedure will be described later.

[0013] <Embodiment 1: Operation of the Monitoring System> The capture unit 11 takes in gas (e.g., air) and captures the carbon dioxide contained in the gas using the capture unit 111. The capture unit 11 adsorbs carbon dioxide to the adsorbent provided in the capture unit 111 by swinging, for example, pressure or temperature, and then desorbs the carbon dioxide from the adsorbent and sends it to the storage unit 12. It is desirable to perform these operations efficiently and with low power consumption. However, if the adsorbent deteriorates and the adsorption rate decreases, the efficiency of carbon dioxide capture decreases and power consumption increases. Furthermore, even if the swing operation is performed, the desired amount of carbon dioxide cannot be obtained. Therefore, the monitoring system 2 monitors the deterioration of the adsorbent using the following procedure.

[0014] The sensor 131 detects the concentration of carbon dioxide contained in the gas (first concentration) before the gas passes through the collection unit 111. The sensor 132 detects the concentration of carbon dioxide contained in the gas (second concentration) after the gas has passed through the collection unit 111. The acquisition unit 21 acquires these detected values. The calculation unit 22 calculates the ratio between the first concentration and the second concentration (second concentration / first concentration). This ratio corresponds to the adsorption rate.

[0015] The calculation unit 22 estimates the degree of deterioration of the adsorbent based on the calculated adsorption rate. For example, the degree of deterioration of the adsorbent can be estimated based on the difference or ratio between the initial value and the current value of the adsorption rate. Alternatively, the degree of deterioration of the adsorbent can be estimated by comparing the time change rate of the adsorption rate (the rate of change of the adsorption rate relative to the operating time of the collection unit 111) with a threshold value. The calculation unit 22 can also estimate the time when the adsorbent should be replaced. For example, when the degree of deterioration of the adsorbent estimated by the above procedure reaches or exceeds a threshold value, an alert can be issued recommending replacement.

[0016] The carbon dioxide adsorbed by the collection unit 111 may contain chemical substances that were not intended to be collected. This may result in an unintended increase in costs, such as adding a process to purify the collected material. Therefore, the monitoring system 2 monitors the quality of the collected material using the following procedure.

[0017] The sensor 133 detects components contained in the output when carbon dioxide desorbed from the collection unit 111 is delivered to the storage unit 12. For example, in addition to carbon dioxide, the sensor 133 detects impurities (e.g., NOx) that are typically adsorbed in the adsorption process. The acquisition unit 21 acquires the detected values ​​(output component data). The calculation unit 22 calculates a quality index of the carbon dioxide contained in the output based on the detected values. For example, the ratio or difference between carbon dioxide and other substances contained in the output can be calculated as the quality index. Other appropriate quality indexes may also be used.

[0018] The sensor 134 detects the volume of carbon dioxide contained in the output sent from the capture unit 111 to the storage unit 12. The acquisition unit 21 acquires the detected value, and the calculation unit 22 records the amount of carbon dioxide captured by the capture unit 11 based on the detected value. This capture amount represents the overall capture performance of the carbon dioxide capture device 1. This capture amount can be used in combination with the adsorption rate, and the capture amount can also be used as an indicator of the economic effect of the carbon dioxide capture device 1, for example.

[0019] Because the collection unit 111 adsorbs carbon dioxide as gas passes through it, the ventilation performance of the collection unit 111 deteriorates over time. For example, the ventilation performance deteriorates when dust adheres to the adsorbent, causing clogging. Alternatively, the ventilation performance deteriorates when the propeller of the ventilation fan malfunctions or its performance deteriorates. The deterioration in ventilation performance leads to a deterioration in performance or failure of the collection unit 111. Therefore, the monitoring system 2 monitors the ventilation performance of the collection unit 111 using the following procedure.

[0020] The sensors 131 and 132 may detect the flow rates of the gas before and after the gas passes through the collection unit 111, respectively. The acquisition unit 21 may acquire the detected values, and the calculation unit 22 may estimate the gas permeability of the gas in the collection unit 111 based on the detected values. For example, the permeability can be estimated based on the ratio or difference between the gas flow rate before passage detected by the sensor 131 and the gas flow rate after passage detected by the sensor 132. Specifically, if the flow rate after passage is significantly lower than the flow rate before passage, clogging or fan failure may have occurred in the collection unit 111. The calculation unit 22 can estimate the permeability of the collection unit 111 using the above procedure. A decrease in permeability may affect the adsorption rate of the collection unit 111, for example, by requiring greater fan power. Therefore, monitoring the permeability is useful from this perspective.

[0021] The adsorbent provided in the capture unit 111 may adsorb substances other than carbon dioxide (interfering substances). This may reduce the efficiency with which the adsorbent adsorbs carbon dioxide, potentially causing problems such as a shortened lifespan of the carbon dioxide capture device 1. Therefore, the monitoring system 2 estimates the possibility that the capture unit 111 has adsorbed such interfering substances by the following procedure.

[0022] Sensor 131 detects the amount of interfering substances (e.g., NOx) contained in the gas before the gas passes through collection unit 111. Sensor 132 detects the amount of the same interfering substances contained in the gas after the gas has passed through collection unit 111. Acquisition unit 21 acquires these detected values. Calculation unit 22 estimates the possibility that collection unit 111 has adsorbed interfering substances based on the ratio or difference between these amounts. For example, if sensor 131 detects 200 ppm of sulfur and sensor 132 detects 10 ppm, there is a possibility that collection unit 111 adsorbed sulfur as the gas passed through collection unit 111. On the other hand, if the difference between the two is sufficiently small, the possibility of adsorption is considered to be low.

[0023] Summary of First Embodiment The monitoring system 2 according to the first embodiment calculates the adsorption rate of the carbon dioxide adsorbent based on the ratio of the carbon dioxide concentrations before and after the gas passes through the collection unit 111. This makes it possible to estimate the deterioration of the collection unit 111.

[0024] The monitoring system 2 according to the first embodiment estimates the ventilation performance of the collection unit 111 by comparing the flow rate of the gas before and after the gas passes through the collection unit 111. This makes it possible to estimate the occurrence of clogging, fan failure, etc. in the collection unit 111.

[0025] The monitoring system 2 according to the first embodiment estimates the possibility that the adsorbent has adsorbed a substance other than carbon dioxide by comparing the substances other than carbon dioxide before and after the gas passes through the collection unit 111. This makes it possible to estimate the possibility of a malfunction occurring due to the adsorption of an interfering substance by the adsorbent.

[0026] The monitoring system 2 according to the first embodiment calculates a quality index of the carbon dioxide delivered to the storage unit 12. This makes it possible to provide quality assurance in the utilization process after storage.

[0027] <Embodiment 2> In the first embodiment, a configuration example for estimating the adsorption rate of the collection unit 111 and the like is described. In the second embodiment of the present invention, an operation example for optimizing the timing at which the recovery unit 11 performs the swing operation is described. The configuration of each device is the same as in the first embodiment.

[0028] 2 is a graph showing changes over time in the carbon dioxide concentration detected by sensors 131 and 132. The vertical axis on the right represents the carbon dioxide concentration (second concentration) after the gas has passed through collection unit 111. The vertical axis on the left represents the ratio of the carbon dioxide concentration (first concentration) before the gas has passed through collection unit 111 to the carbon dioxide concentration (second concentration) after the gas has passed through collection unit 111. The change over time here refers to the operating time from when collection unit 111 starts to adsorb carbon dioxide until desorption is performed.

[0029] Immediately after the trapping unit 111 starts operating, the second concentration is small because the gas passing through the trapping unit 111 efficiently adsorbs carbon dioxide. As the trapping unit 111 continues to operate, the amount of carbon dioxide that the trapping unit 111 can adsorb gradually becomes saturated, and once this reaches a certain level, it can no longer adsorb any more. This is represented by the upward-sloping curve in Figure 2.

[0030] Similarly, when comparing the carbon dioxide concentrations before and after the gas passes through the collection unit 111, immediately after the start of operation, the concentration is high before passing and drops significantly after passing, so the ratio of the two (first concentration / second concentration) is large. As the collection unit 111 continues to operate, the collection unit 111 gradually becomes unable to adsorb carbon dioxide, so the second concentration increases and the ratio of the two decreases. This is represented by the downward-sloping curve in Figure 2. The downward-sloping slope represents the adsorption rate.

[0031] If the adsorbent is operated until the adsorbent reaches its limit of carbon dioxide adsorption capacity and then desorbs carbon dioxide, the amount of carbon dioxide that can be recovered in one adsorption operation can be maximized. On the other hand, since the adsorption rate gradually decreases from adsorption to desorption, as shown by the downward-sloping curve in Figure 2, adsorbing carbon dioxide to the adsorption limit is not desirable from the viewpoint of operational efficiency. Therefore, the monitoring system 2 attempts to balance the trade-off between these two.

[0032] Specifically, the calculation unit 22 acquires detection values ​​from the sensors 131 and 132, and uses these detection values ​​to calculate the values ​​on the vertical axes in Fig. 2. The calculation unit 22 optimizes the balance between the amount of carbon dioxide that can be recovered in one adsorption / desorption and the adsorption rate. For example, using an evaluation formula with these values ​​as parameters, desorption by swing operation is performed at the timing when the evaluation value is maximized.

[0033] The calculation unit 22 can also estimate the life of the adsorbent based on the slope of the downward-sloping curve in FIG. 2. Ideally, the adsorption rate returns to its initial value each time adsorption / desorption is performed. However, in reality, as the cumulative operating time of the collection unit 111 increases, the value after the adsorption rate has returned becomes lower than the initial value. Specifically, the slope of the downward-sloping curve in FIG. 2 gradually becomes gentler. The calculation unit 22 can estimate the life of the adsorbent based on the change in this slope over time. Alternatively, the time required from the start of adsorption to reaching the adsorption limit gradually increases as the adsorbent deteriorates, and by monitoring this time, the life can be similarly estimated.

[0034] <Regarding Modifications of the Present Invention> In the above-described embodiments, the calculation unit 22 can be configured by hardware such as a circuit device that implements its functions, or can be configured by a calculation device such as a CPU (Central Processing Unit) that executes software that implements its functions.

[0035] In the above embodiment, the sensors 131 to 134 have been described as measuring the carbon dioxide concentration, gas flow rate, etc., but sensors that measure other physical quantities (e.g., temperature, humidity, etc.) may also be used in combination. For example, if the performance of the carbon dioxide capture device 1 varies depending on the environmental temperature, the calculation unit 22 may adjust the gas flow rate based on the measured temperature. Other appropriate optimizations may also be performed.

[0036] 1: Carbon dioxide recovery device 111: Collection unit 12: Storage unit 131 to 134: Sensors 2: Monitoring system 22: Calculation unit

Claims

1. A method for controlling a monitoring system for monitoring the performance of a carbon dioxide recovery apparatus that recovers carbon dioxide from a gas, the carbon dioxide recovery apparatus comprising a collection unit that adsorbs carbon dioxide contained in the gas, the monitoring system comprising a calculation unit that monitors the performance of the carbon dioxide recovery apparatus, the method comprising causing the calculation unit to perform steps of: obtaining a first concentration of carbon dioxide contained in the gas before the gas passes through the collection unit; obtaining a second concentration of carbon dioxide contained in the gas after the gas passes through the collection unit; calculating an adsorption rate representing the performance of the collection unit to adsorb carbon dioxide based on a ratio between the first concentration and the second concentration. A control method characterized by the above.

2. The control method according to claim 1, further comprising causing the calculation unit to perform a step of estimating a degree of deterioration of the collection unit based on a change amount of the adsorption rate while the collection unit is operating.

3. The control method according to claim 1, further comprising causing the calculation unit to perform a step of estimating a replacement time of the collection unit based on a change amount of the adsorption rate while the collection unit is operating.

4. The carbon dioxide recovery apparatus comprises a storage unit that stores carbon dioxide adsorbed by the collection unit, and the method further comprises causing the calculation unit to perform steps of: obtaining delivery product component data representing a result of detecting components contained in a delivery product delivered from the collection unit to the storage unit; calculating a quality index of carbon dioxide stored in the storage unit based on the delivery product component data. The control method according to claim 1, characterized by the above.

5. The control method according to claim 1, further comprising causing the calculation unit to perform a step of estimating a ventilation performance of the collection unit based on a ratio between a flow rate of the gas before the gas passes through the collection unit and a flow rate of the gas after the gas passes through the collection unit.

6. The method further causes the arithmetic unit to estimate the possibility that the collection unit has adsorbed an interfering substance that interferes with the collection unit's adsorption of carbon dioxide by comparing a component other than carbon dioxide contained in the gas before the gas passes through the collection unit with a component other than carbon dioxide contained in the gas after the gas has passed through the collection unit. The control method according to claim 1, characterized in that this is carried out.

7. The method further causes the arithmetic unit to optimize the trade-off between the remaining amount that the collection unit can adsorb carbon dioxide and the adsorption rate by optimizing the timing for desorbing carbon dioxide from the collection unit based on the adsorption rate. The control method according to claim 1, characterized in that this is carried out.

8. In the step of optimizing, the trade-off between the remaining amount and the adsorption rate is optimized by monitoring at least one of whether the adsorption rate has dropped below a threshold value or whether the time required for the collection unit to reach the adsorption limit has reached a threshold value or more. The control method according to claim 7, characterized in that this is carried out.

9. A monitoring system for monitoring the performance of a carbon dioxide recovery device that recovers carbon dioxide from a gas, the carbon dioxide recovery device comprising a collection unit that adsorbs carbon dioxide contained in the gas, the monitoring system comprising an arithmetic unit that monitors the performance of the carbon dioxide recovery device, the arithmetic unit performing the steps of obtaining a first concentration of carbon dioxide contained in the gas before the gas passes through the collection unit, obtaining a second concentration of carbon dioxide contained in the gas after the gas has passed through the collection unit, and calculating an adsorption rate representing the performance of the collection unit to adsorb carbon dioxide based on the ratio between the first concentration and the second concentration. A monitoring system characterized in that this is carried out.

Images