CO2 capture system

Abstract

This invention provides a CO2 capture system that offers improved accuracy in calculating reaction completion time and enhanced versatility. [Solution] The CO2 recovery system 1 includes a CO2 recovery device 100 that recovers CO2 by contacting a CO2-containing gas with a reaction solution L consisting of an alkali metal hydroxide aqueous solution or an alkaline earth metal hydroxide aqueous solution stored in a reaction vessel 10 to carry out a CO2 fixation reaction; an analysis unit 61 that pre-analyzes the changes in the temperature of the reaction solution L and the pH of the reaction solution L over time from the start of the CO2 fixation reaction by simulating the CO2 fixation reaction based on at least the specifications of the reaction vessel 10, the amount of reaction solution L stored in the reaction vessel 10, the initial temperature of the reaction solution L, the CO2 concentration of the CO2-containing gas, the flow rate of the CO2-containing gas supplied to the reaction vessel 10, and the temperature of the CO2-containing gas; and an estimation unit 62 that estimates the actual end time of the CO2 fixation reaction based on the analysis results of the analysis unit 61.

Description

[Technical Field]

[0001] This invention relates to a CO2 capture system. [Background technology]

[0002] In recent years, there has been a growing demand to reduce emissions of CO2 as a greenhouse gas, and various CO2 recovery devices have been investigated. For example, Patent Document 1 discloses a device that recovers CO2 by producing NaHCO3 or Na2CO3 as reaction products by contacting a CO2-containing gas with an alkaline aqueous solution such as NaOH that has been stored in a storage tank in advance, thereby immobilizing the CO2. In the configuration disclosed in Patent Document 1, the progress of the reaction to produce the reaction products is determined based on the temperature change of the reaction solution. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2024-113351 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, in the configuration disclosed in Patent Document 1, determining the progress of the reaction requires pre-establishing a correspondence between the temperature of the reaction solution and the progress of the reaction product formation. Therefore, there is room for improvement in calculating the reaction completion time more accurately under various environmental conditions, and it lacks versatility.

[0005] This invention has been made in view of the above problems, and aims to provide a CO2 recovery system that improves the accuracy of calculating the reaction completion time and enhances versatility. [Means for solving the problem]

[0006] One aspect of the present invention is, A CO2 recovery device that recovers CO2 by performing a CO2 immobilization reaction by bringing a CO2-containing gas into contact with a reaction solution composed of an aqueous solution of an alkali metal hydroxide or an aqueous solution of an alkaline earth metal hydroxide stored in a reaction tank, Based on at least the specifications of the reaction tank, the liquid volume of the reaction solution stored in the reaction tank, the initial liquid temperature of the reaction solution, the CO2 concentration of the CO2-containing gas, the flow rate of the CO2-containing gas supplied to the reaction tank, and the temperature of the CO2-containing gas, By simulating the CO2 immobilization reaction, an analysis unit that pre-analyzes the change over time of the liquid temperature of the reaction solution and the change over time of the pH of the reaction solution from the start of the reaction of the CO2 immobilization reaction, An estimation unit that estimates the reaction end time of the actual CO2 immobilization reaction based on the analysis result of the analysis unit, It is in a CO2 recovery system including

Effects of the Invention

[0007] In the CO2 recovery system of the above aspect, since it is not necessary to prepare in advance the correspondence relationship between the temperature of the reaction solution and the progress of the formation reaction of the reaction product, the reaction end time can be calculated more accurately under various environments and conditions, and the versatility is improved.

[0008] As described above, according to the above aspect, it is possible to provide a CO2 recovery system in which the calculation accuracy of the reaction end time and the versatility are improved.

Brief Description of the Drawings

[0009] [Figure 1] Conceptual diagram showing the configuration of the CO2 recovery system in Embodiment 1. [Figure 2] Diagram showing a part of the mesh model of the reaction tank in which the reaction solution is stored in Embodiment 1. [Figure 3] Example of a diagram showing the change over time of the liquid temperature in the analysis result of Embodiment 1. [Figure 4] Example of a diagram showing the change over time of the pH in the analysis result of Embodiment 1. [Figure 5]A flowchart illustrating the usage of the CO2 capture system in Embodiment 1. [Figure 6] In the comparative example, (a) a figure showing the change in liquid temperature over time, and (b) a magnified view of the area near the peak in (a). [Figure 7] A diagram showing the change in pH over time in the comparative example. [Figure 8] An example of a figure showing the change in liquid temperature over time in the analysis results of Embodiment 2. [Figure 9] An example of a diagram showing the change in pH over time in the analysis results of Embodiment 2. [Figure 10] A flowchart illustrating the usage of the CO2 capture system in Embodiment 2. [Figure 11] A diagram showing the change in liquid temperature over time in the comparative example. [Figure 12] A diagram showing the change in pH over time in the comparative example. [Figure 13] A flowchart illustrating the usage of the CO2 capture system in Embodiment 3. [Figure 14] A conceptual diagram showing the configuration of the CO2 capture system in Embodiment 4. [Figure 15] This figure shows the time-dependent changes in the measured liquid temperature, the pre-treated liquid temperature, and the pre-treated and low-pass filtered liquid temperature in Embodiment 4. [Figure 16] A diagram showing the liquid temperature after pretreatment and low-pass filtering in Embodiment 4, and the degree of change in said liquid temperature. [Figure 17] A flowchart illustrating the usage of the CO2 capture system in Embodiment 4. [Figure 18] A flowchart illustrating the usage of the CO2 capture system in Embodiment 5. [Modes for carrying out the invention]

[0010] (Embodiment 1) 1. Overview of CO2 Capture System 1 The CO2 recovery system 1 in Embodiment 1 will be described with reference to Figure 1. As shown in Figure 1, the CO2 recovery system 1 includes a CO2 recovery device 100, an analysis unit 61, and an estimation unit 62. The CO2 recovery device 100 recovers CO2 by bringing a CO2-containing gas into contact with a reaction solution consisting of an alkali metal hydroxide aqueous solution or an alkaline earth metal hydroxide aqueous solution to perform a CO2 fixation reaction. The analysis unit 61 and the estimation unit 62 consist of a computing device and a storage device (not shown) and are configured to execute a program that performs a predetermined function. The CO2 recovery system 1 uses the analysis results obtained by analyzing the CO2 fixation reaction simulated by the analysis unit 61 to estimate the reaction completion time of the actual CO2 fixation reaction using the estimation unit 62.

[0011] 2. Overview of CO2 recovery device 100 As shown in Figure 1, the CO2 recovery device 100 mainly comprises a reaction vessel 10, a reaction liquid input amount adjustment unit 20, a CO2-containing gas supply unit 30, a gas supply amount adjustment unit 40, a liquid temperature sensor 50, an outside air temperature sensor 51, an exhaust unit 55, a product recovery unit 56, and a control unit 58. Each component is described in detail below.

[0012] 2-1. Reaction vessel 10 The reaction vessel 10 shown in Figure 1 is configured to accept reaction solution L. Reaction solution L is a reaction solution used to recover CO2 from a CO2-containing gas by contacting it with the reaction vessel. Reaction solution L can be an aqueous solution of alkali metal hydroxide or an aqueous solution of alkaline earth metal hydroxide, and in this embodiment 1, an aqueous NaOH solution was used. The concentration of the aqueous NaOH solution is not limited, but in this embodiment 1, a 5.0% aqueous NaOH solution was used because it is not classified as a hazardous substance and is therefore easy to handle. Considering the impact on the environment and safety for humans, it is preferable to use an aqueous NaOH solution of 5.0% or less, but if it can be properly managed, an aqueous NaOH solution with a concentration higher than 5.0% may also be used.

[0013] The shape of the reaction vessel 10 is not limited, but in this embodiment, it is a bottomed cylindrical shape with an opening 11, where the height direction is the vertical direction Z, and the radial directions are the X and Y directions, which are perpendicular to the vertical direction Z. The X and Y directions are perpendicular to each other, and in Figure 1, the X direction is the front and back direction, and the Y direction is the lateral direction. As shown in Figure 1, the reaction vessel 10 is positioned so that the opening 11 is located at the top. The opening 11 can be closed by the lid 12. The reaction vessel 10 may be provided with a stirring device (not shown) for stirring the reaction liquid L stored in the reaction vessel 10.

[0014] 2-2. Reaction solution input volume adjustment unit 20 The reaction liquid input volume adjustment unit 20 shown in Figure 1 adjusts the amount of reaction liquid L introduced into the reaction tank 10. The amount of reaction liquid L introduced by the reaction liquid input volume adjustment unit 20 can be set by the user as appropriate.

[0015] 2-3. CO2-containing gas supply unit 30 The CO2-containing gas supply unit 30 shown in Figure 1 supplies CO2-containing gas to the reaction vessel 10. "CO2-containing gas" refers to a gas that contains CO2 as a constituent component. This CO2-containing gas may be a gas that contains only CO2 as a constituent component, or it may also contain unavoidable impurities. Furthermore, the CO2-containing gas may be a mixed gas in which CO2 and other substances are present as constituent components. The proportion of CO2 in the mixed gas is not limited, and the main component that accounts for the largest proportion in the mixed gas may be CO2, or it may be a substance other than CO2. For example, the CO2-containing gas can be exhaust gas from a factory, air, etc., and in this embodiment, it is exhaust gas from a factory, etc.

[0016] The CO2-containing gas supply unit 30 includes a gas supply pipe 31, a nozzle 32, a gas discharge unit 33, a CO2 concentration sensor 34, and a gas temperature sensor 35. The gas supply pipe 31 carries the CO2-containing gas. The tip of the gas supply pipe 31 penetrates the lid 12 and is located inside the reaction vessel 10. The nozzle 32 is connected to the tip of the gas supply pipe 31 and is located inside the reaction vessel 10. The gas discharge unit 33 is formed at two locations on the nozzle 32, the middle and the tip, and is configured to discharge the CO2-containing gas supplied via the gas supply pipe 31 and nozzle 32 into the reaction liquid L for bubbling. To improve the frequency of contact between the CO2-containing gas and the reaction liquid L, it is preferable to discharge the CO2-containing gas in the form of microbubbles. Microbubbles can be formed by a microbubble former (not shown) provided at the tip of the gas discharge unit 33.

[0017] The CO2 concentration sensor 34 acquires the CO2 concentration of the CO2-containing gas supplied to the reaction vessel 10. The gas temperature sensor 35 acquires the temperature of the CO2-containing gas supplied to the reaction vessel 10. The acquired CO2 concentration and gas temperature are stored in a storage unit (not shown) and input to the analysis unit 61, which will be described later.

[0018] Then, CO2-containing gas is supplied from the CO2-containing gas supply unit 30 into the reaction vessel 10 and brought into contact with the NaOH aqueous solution, which is the reaction solution L, thereby carrying out the reaction shown in Equation 1 below. After the reaction in Equation 1 is completed, if CO2-containing gas is supplied further, the reaction shown in Equation 2 below will carry out. In this specification, Equations 1 and 2 below are referred to as the CO2 immobilization reaction.

[0019]

number

number

[0020] In reaction vessel 10, NaHCO3 and Na2CO3 are not present before the start of the above reaction. However, depending on the progress of the reaction, one of the following states occurs: Na2CO3 is produced and NaHCO3 is absent; some Na2CO3 reacts with H2O and CO2 to produce NaHCO3 and both are present; or all Na2CO3 is converted to NaHCO3 and there is no Na2CO3 but NaHCO3 is present. Both NaHCO3 and Na2CO3 produced by the above reaction dissolve in the water in reaction vessel 10 and become aqueous solutions. In this specification, NaHCO3, Na2CO3, and mixtures of both are collectively referred to as "products," and their aqueous solutions are collectively referred to as "aqueous product solutions."

[0021] 2-4. Gas supply adjustment unit 40 The gas supply adjustment unit 40 shown in Figure 1 adjusts the flow rate of the CO2-containing gas F1 supplied by the CO2-containing gas supply unit 30. In this embodiment, the gas supply adjustment unit 40 controls the drive of an air pump (not shown) that supplies the CO2-containing gas F1 to the CO2-containing gas supply unit 30.

[0022] 2-5. Liquid temperature sensor 50 (liquid temperature measurement unit) The liquid temperature sensor 50 shown in Figure 1 acquires the initial temperature of the reaction liquid L stored in the reaction vessel 10. The liquid temperature sensor 50 is inserted into the lid 12 so that the detection part at the tip of the liquid temperature sensor 50 is located in the reaction liquid L. Note that the arrangement of the liquid temperature sensor 50 is not limited to this, and it may also be arranged so as to pass through the product recovery unit 56, which will be described later. It also functions as a liquid temperature measurement unit that measures the liquid temperature of the reaction liquid L while the CO2 fixation reaction is underway in the reaction vessel 10. The initial temperature and measured liquid temperature acquired by the liquid temperature sensor 50 are stored in a storage unit (not shown) and input to the analysis unit 61, which will be described later.

[0023] 2-6. Outdoor temperature sensor 51 The ambient temperature sensor 51 shown in Figure 1 is placed outside the reaction vessel 10 to acquire the ambient temperature outside the reaction vessel 10. The ambient temperature acquired by the ambient temperature sensor 51 is stored in a memory unit (not shown) and input to the analysis unit 61, which will be described later.

[0024] 2-7. Exhaust section 55 The exhaust unit 55 shown in Figure 1 releases CO2-removed gas to the outside, which is gas from which CO2 has been removed by the CO2 fixation reaction. An impurity removal filter (not shown) is connected to the exhaust unit 55, and the CO2-removed gas discharged from the exhaust unit 55 is released to the outside after impurities, including harmful substances, have been removed by the impurity removal filter.

[0025] 2-8. Product recovery section 56 The product recovery unit 56 shown in Figure 1 is provided in the reaction vessel 10. In this embodiment, the product recovery unit 56 is provided with a drain cock 57, and by opening the drain cock 57, the aqueous product solution containing the target product generated in the reaction vessel 10 can be removed from the reaction vessel 10 via the product recovery unit 56. The aqueous product solution recovered by the product recovery unit 56 can be purified to obtain the target product and used as a resource, for example, as a detergent, preservative, or deodorant.

[0026] 2-9. Control Unit 58 The control unit 58 shown in Figure 1 controls the operation of the CO2 recovery device 100, including the gas supply rate adjustment unit 40. The control unit 58 may be, for example, a PLC (Programmable Logic Controller), a dedicated ECU (Electronic Control Unit), a personal computer (PC), a server, a cloud, or other information device, and can be configured to include a CPU, storage device, and communication device. The control unit 58 may be located near the reaction vessel 10, or it may be located away from the reaction vessel 10 and operated remotely. For example, when introducing CO2-containing gas F1, the control unit 58 controls the gas supply rate adjustment unit 40 to control the flow rate of CO2-containing gas F1 and the on / off switching of its flow. The gas flow rate may be adjusted by selecting an appropriate pump.

[0027] 3.Analysis Department 61 The analysis unit 61 shown in Figure 1 analyzes the time-dependent changes in the temperature of the reaction solution L and the pH of the reaction solution L from the start of the CO2 fixation reaction in the reaction vessel 10 by simulating the CO2 fixation reaction. The analysis in the analysis unit 61 is performed based on at least the specifications of the reaction vessel 10, the volume of the reaction solution L stored in the reaction vessel 10, the initial temperature of the reaction solution L, the CO2 concentration of the CO2-containing gas, the flow rate of the CO2-containing gas supplied to the reaction vessel 10, and the temperature of the CO2-containing gas.

[0028] The specifications of the reaction vessel 10 include dimensions including the thickness of the reaction vessel 10 and the material of the reaction vessel 10. The volume of reaction liquid L stored in the reaction vessel 10 is the volume of reaction liquid L adjusted by the reaction liquid input volume adjustment unit 20. The initial temperature of the reaction liquid L is obtained by the liquid temperature sensor 50. The CO2 concentration of the CO2-containing gas is obtained by the CO2 concentration sensor 34. The flow rate of the CO2-containing gas is the flow rate of the CO2-containing gas adjusted by the gas supply volume adjustment unit 40. The temperature of the CO2-containing gas is obtained by the gas temperature sensor 35.

[0029] 3-1. Method for calculating the change in reaction solution temperature over time The method for calculating the change in the temperature of the reaction solution L over time by the analysis unit 61 is not limited, but in this embodiment, a mesh model M of the reaction vessel 10 and reaction solution L shown in Figure 2 is created in advance. Note that the mesh model M shown in Figure 2 is one of six equal divisions around the axis of the reaction vessel 10. The mesh element size in the mesh model M is not limited and can be set as appropriate. In this embodiment, as shown in Figure 2, the computational load is reduced by increasing the mesh element size in the region away from the gas discharge unit 33.

[0030] Then, the analysis unit 61 uses the mesh model M shown in Figure 2 to calculate the change in the liquid temperature T of the reaction solution L over time using the following equation 3.

number

[0031] The temperature change ΔT in Equation 3 above is calculated by Equation 4 below.

number

[0032] The heat generation Q1 per unit volume in Equation 4 above is the amount of heat generated in the CO2 recovery system 1, and can be expressed as the sum of the heat of reaction of the CO2 fixation reaction, the heat of dissolution of CO2, and the heat received from the CO2-containing gas, and is calculated by Equation 5 below.

number

[0033] In equation 5 above, the reaction enthalpies (1)ΔH1, (2)ΔH2, and (3)ΔH3 are the reaction enthalpies in the respective chemical reaction equations (1), (2), and (3) shown in equation 6 below.

number

[0034] Furthermore, the chemical reaction rate (1)v in equation 5 above r1 , chemical reaction rate (2)v r2 , chemical reaction rate (3)v r3 These are the reaction rates of the respective chemical reaction equations (1), (2), and (3) shown in Equation 6 above, and can be calculated using Equation 7 below.

number

[0035] Furthermore, the CO2 dissolution rate V in the above equation 5 rg This is calculated using Equation 8 below.

number

[0036] On the other hand, the heat dissipation amount Q2 per unit volume in the above equation 4 is calculated by the following equation 9. [Number]

[0037] As described above, the change over time of the liquid temperature T of the reaction solution L calculated by Equations 3 to 9 is represented, for example, as shown in FIG. 3. In the example shown in FIG. 3 in this embodiment, the change over time of the liquid temperature T has an analysis result with a peak. The peak of the liquid temperature T refers to the maximum temperature when the maximum temperature is exhibited before the end of the reaction, and the time when the peak is exhibited is the peak time t peak is referred to as.

[0038] 3-2. Method for calculating the change over time of the pH of the reaction solution Next, the method for calculating the change over time of the pH of the reaction solution L by the analysis unit 61 is not limited either, but in this embodiment, it is calculated by the following Equation 10. [Number]

[0039] The change over time of the pH of the reaction solution L calculated by the above Equation 10 is represented, for example, as shown in FIG. 4. In this embodiment, the target product is Na2CO3, and the timing when the reaction of the above Equation 1 is completed is defined as the reaction end time. Therefore, the time when the pH of the reaction solution L reaches about 11.8 is defined as the reaction end time, and the change over time of the pH of the reaction solution L is calculated up to t end until it reaches about 11.8 shown in FIG. 4.

[0040] 4. Estimation unit 62 The estimation unit 62 shown in FIG. 1 estimates the reaction end time t end of the actual CO2 fixation reaction based on the analysis result of the analysis unit 61.

[0041] In this embodiment, as shown in FIG. 3, the change over time of the liquid temperature T of the reaction solution L in the analysis result has a peak. The estimation unit 62 calculates the peak time ratio t peak which is the ratio of the peak time t end in the analysis result to the reaction end time t end / t peakThe following is calculated: the time at which the liquid temperature during the CO2 fixation reaction, as measured by the liquid temperature sensor 50 as the liquid temperature measurement unit, reaches its peak, and the peak time ratio t. end / t peak Based on this, the reaction completion time of the CO2 fixation reaction is estimated.

[0042] The analysis unit 61 and estimation unit 62 shown in Figure 1 may be information devices such as a PLC (Programmable Logic Controller), a dedicated ECU (Electronic Control Unit), a personal computer (PC), a server, or a cloud, and may be configured to include a CPU (Central Processing Unit), a storage device, and a communication device. The analysis unit 61 and estimation unit 62 may be located away from the reaction vessel 10, or they may be located near the reaction vessel 10. The temperature of the CO2-containing gas from the gas temperature sensor 35, the initial temperature obtained by the liquid temperature sensor 50, and the measured liquid temperature are stored in the storage unit, but the storage unit and the analysis unit 61 and estimation unit 62 may be located in different information devices or in the same information device. Furthermore, the control unit 58, analysis unit 61, estimation unit 62, and storage unit may be located in the same information device or in different information devices.

[0043] 5. Usage of the CO2 recovery system 1 of Embodiment 1 The usage of the CO2 recovery system 1 in Embodiment 1 will be explained with reference to the flow diagram shown in Figure 5. In step S1 of Figure 5, various items of the working environment of the CO2 recovery device 100 are measured. In this embodiment, the initial liquid temperature of the reaction solution L is measured by the liquid temperature sensor 50, the ambient temperature outside the reaction vessel 10 is measured by the ambient temperature sensor 51, the CO2 concentration in the CO2-containing gas is measured by the CO2 concentration sensor 34, and the temperature of the CO2-containing gas is obtained by the gas temperature sensor 35. The measurement results are then stored in a memory unit (not shown).

[0044] Next, in step S2, analysis conditions are input to the analysis unit 61. In this embodiment, the analysis conditions are: thickness of the reaction vessel 10, reaction vessel transfer coefficient λ of the reaction vessel 10, volume V of the reaction solution, flow rate of CO2-containing gas, constant-pressure specific heat capacity Cp, atmospheric heat transfer coefficient h2, solution density ρl, and OH in the reaction solution L. - Input the initial concentration and reaction enthalpy (1)~(3)ΔH1~ΔH3.

[0045] Then, in step S3, the analysis unit 61 analyzes the liquid temperature and pH of the reaction solution L based on the measurement results obtained in step S1 and the analysis conditions entered in step S2, and calculates the time-dependent changes in liquid temperature and pH. Then, in step S4, the time-dependent change in the liquid temperature T of the reaction solution L is calculated based on equations 3 to 9 above, and the time-dependent change in the pH of the reaction solution L is calculated based on equation 10 above. After that, in step S5, the estimation unit 62 calculates the peak time ratio t end / t peak The result is calculated, and the analysis by the analysis unit 61 is terminated.

[0046] Then, in step S6, the control unit 58 starts the operation of the CO2 recovery device 100 and bubbles the CO2-containing gas F1 into the reaction liquid L in the reaction vessel 10 according to the analysis conditions. Subsequently, in step S7, the estimation unit 62 determines whether the measured liquid temperature of the reaction liquid L obtained by the liquid temperature sensor 50 has reached its peak, and if it has not reached its peak, step S7 is repeated.

[0047] On the other hand, if it is determined in step S7 that the measured liquid temperature of the reaction solution L has reached its peak, then in step S8, the estimation unit 62 calculates the peak time ratio t end / t peak The time obtained by accumulating the time when the measured liquid temperature of the reaction solution L reaches its peak is estimated as the reaction completion time of the operating CO2 recovery device 100. Then, in step S9, when the estimated reaction completion time is reached, the control unit 58 stops the supply of CO2-containing gas F1 and terminates the operation of the CO2 recovery device 100. The flow is then terminated.

[0048] 6. Confirmation Test of Embodiment 1 Next, a confirmation test was conducted to determine the reaction completion time estimated based on the usage of the CO2 recovery system 1 described above. In this confirmation test, as a comparative example, the CO2 immobilization reaction was carried out in the CO2 recovery device 100 according to the analysis conditions described above, and the liquid temperature and pH of the reaction solution L were measured as needed. The time at which the pH reached the pH corresponding to the completion of the reaction for the target product was obtained. The change over time of the liquid temperature of the reaction solution L measured in the comparative example is shown in Figure 6(a), a magnified view of the area near the peak in Figure 6(a) is shown in Figure 6(b), and the change over time of the pH of the reaction solution L measured in the comparative example is shown in Figure 7.

[0049] According to the verification test, the change in liquid temperature over time in the analysis results shown in Figure 3 was generally similar to the measured change in liquid temperature over time shown in Figures 6(a) and 6(b), and the difference between the estimated reaction completion time and the measured reaction completion time in the comparative example was very small. Furthermore, the change in pH over time in the analysis results shown in Figure 4 was generally similar to the measured change in pH over time shown in Figure 7. Thus, it was confirmed that the CO2 recovery system 1 of Embodiment 1 can estimate the reaction completion time with high accuracy.

[0050] 7. Effects of the CO2 recovery system 1 of Embodiment 1 According to the CO2 recovery system 1 of this embodiment 1, there is no need to pre-prepare a correspondence between the liquid temperature of the reaction solution L and the progress of the reaction to form the reaction product. Therefore, the reaction completion time can be calculated with greater accuracy under various environmental conditions, thereby improving versatility. Furthermore, since a pH sensor is not required to calculate the change in pH over time, the system can be kept from becoming too large and costs can be reduced.

[0051] Furthermore, when determining the end of a reaction using conventional real-time measurement (immediate measurement), the noise during measurement and variations in the reaction state within the reaction vessel 10 make it difficult to accurately calculate the reaction end time. Also, when determining the end of a reaction using simulations based solely on conditional calculations, it is difficult to consider all the changes in CO2 concentration that occur in the actual reaction solution L and CO2-containing gas F1, making it difficult to accurately calculate the reaction end time. In contrast to these, the CO2 recovery system 1 of this embodiment 1 analyzes the changes in the temperature and pH of the reaction solution over time to determine the end of the reaction. This eliminates the effects of noise during measurement and variations in the reaction state, while also considering the changes in CO2 concentration in the actual reaction solution L and CO2-containing gas F1, allowing for an accurate calculation of the reaction end time. Moreover, while variations in the reaction state within the reaction vessel 10 increase when the capacity of the reaction vessel 10 is large, the CO2 recovery system 1 of this embodiment 1, as described above, can eliminate the effects of variations in the reaction state, allowing for an accurate calculation of the reaction end time.

[0052] Furthermore, in this embodiment 1, a liquid temperature sensor 50 is provided as a liquid temperature measurement unit to measure the liquid temperature of the reaction solution L during the CO2 fixation reaction in the reaction vessel 10. The estimation unit 62, when the change in liquid temperature over time in the analysis results has a peak, calculates the time from the start of the reaction to the peak time of liquid temperature and the time from the end of the reaction to the end of the reaction t in the analysis results. end The peak time ratio t is the ratio of to end / t peak Next, calculate the time at which the liquid temperature measured by the liquid temperature sensor 50 reached its peak, and the peak time ratio t. end / t peak Based on this, the reaction completion time of the CO2 fixation reaction is estimated. This allows for a more accurate estimation of the reaction completion time.

[0053] Furthermore, in this embodiment 1, the analysis unit 61 calculates the heat generation Q1, which is the amount of heat generated in the CO2 recovery system 1, and the heat dissipation Q2, which is released to the outside from the reaction vessel 10. Based on the heat generation Q1 and the heat dissipation Q2, the analysis unit 61 calculates the change in the liquid temperature T of the reaction solution L over time. This makes it possible to calculate the change in liquid temperature T over time more accurately, and further improves the accuracy of calculating the reaction completion time.

[0054] Furthermore, after calculating the change in the liquid temperature of the reaction solution L over time in step S4 of this embodiment 1, a step may be added to determine whether or not there is a peak in the liquid temperature. If it is determined that there is no peak in the liquid temperature, the subsequent steps may be changed to perform calculations that do not consider the peak in the liquid temperature, as described in Embodiment 2 later.

[0055] As described above, this embodiment 1 provides a CO2 recovery system 1 that offers improved accuracy in calculating the reaction completion time and enhanced versatility.

[0056] (Embodiment 2) In the CO2 recovery system 1 of Embodiment 1 described above, the change in liquid temperature over time in the analysis results of the analysis unit 61 showed a peak in liquid temperature. However, in the CO2 recovery system 1 of Embodiment 2, the change in liquid temperature over time in the analysis results of the analysis unit 61 does not show a peak in liquid temperature. For example, the change in liquid temperature over time in Embodiment 2 is represented as shown in Figure 8. Also, the change in pH over time in Embodiment 2 is represented as shown in Figure 9.

[0057] In this second embodiment, the estimation unit 62 determines the reaction completion time t in the analysis results of the analysis unit 61. end The amount of rise in liquid temperature ΔT during the change in liquid temperature T over time. end The reaction completion time t of the CO2 fixation reaction is calculated based on the rise in liquid temperature. end This estimates the reaction completion time t in the analysis results. endThis is the time from the start of the reaction until the pH of the reaction solution L reaches a preset pH at the end of the reaction, depending on the target product produced by the CO2 immobilization reaction, as in the first embodiment. The other configurations of the CO2 recovery system 1 in this second embodiment are the same as those of the CO2 recovery system 1 shown in Figure 1.

[0058] 8. Usage of the CO2 recovery system 1 of Embodiment 2 The usage of the CO2 recovery system 1 in this second embodiment will be explained with reference to the flow diagram shown in Figure 10. First, steps S1 to S4 in the flow diagram shown in Figure 10 in this second embodiment are the same as steps S1 to S4 in the first embodiment shown in Figure 5, so the explanation will be omitted. Then, after step S4 shown in Figure 10, in step S51, the liquid temperature rise amount ΔT end The following is calculated, and in step S52, the time at which the liquid temperature rise ΔTend occurs is estimated as the reaction completion time.

[0059] Then, in step S6 shown in Figure 10, similar to step S6 in Embodiment 1, the control unit 58 starts the operation of the CO2 recovery device 100 and bubbles the CO2-containing gas F1 into the reaction liquid L in the reaction vessel 10 according to the analysis conditions. Subsequently, in step S9, similar to step S9 in Embodiment 1, when the estimated reaction completion time is reached, the control unit 58 stops the supply of the CO2-containing gas F1 and terminates the operation of the CO2 recovery device 100. Then, the flow is terminated.

[0060] 9. Confirmation Test of Embodiment 2 Similar to the confirmation test in Embodiment 1, a confirmation test was conducted on the estimated reaction completion time in Embodiment 2. According to this confirmation test, the change in liquid temperature over time and the amount of liquid temperature rise in the analysis results shown in Figure 6 were generally similar to the measured change in liquid temperature over time and the amount of liquid temperature rise shown in Figure 11, and the difference between the estimated reaction completion time and the measured reaction completion time in the comparative example was very small. In addition, the change in pH over time in the analysis results shown in Figure 9 was generally similar to the measured change in pH over time shown in Figure 12. Thus, it was confirmed that the CO2 recovery system 1 of Embodiment 2 can estimate the reaction completion time with high accuracy.

[0061] 10. Effects of the CO2 recovery system 1 of Embodiment 2 According to the CO2 recovery system 1 of Embodiment 2, even if the liquid temperature change over time in the analysis results of the analysis unit 61 does not have a peak in liquid temperature, it is not necessary to pre-prepare a correspondence between the liquid temperature of the reaction solution L and the progress of the reaction to form the reaction product. Therefore, the reaction completion time can be calculated with greater accuracy under various environmental conditions, improving versatility. In addition, since a pH sensor is not required to calculate the change in pH over time, the system can be kept from becoming too large and costs can be reduced.

[0062] As a variation of this second embodiment, a peak determination step may be added after step S4 to determine whether or not there is a peak in the liquid temperature. In this peak determination step, for example, if a change is detected in which the liquid temperature rises by a predetermined amount and then falls by a predetermined amount, it can be determined that there is a peak in the liquid temperature, and if no such change is detected, it can be determined that there is no peak in the liquid temperature. If it is determined in this peak determination step that there is no peak in the liquid temperature, the steps from S51 onwards of this embodiment shown in Figure 10 may be performed, and if it is determined that there is a peak in the liquid temperature, the steps from S5 onwards of the first embodiment shown in Figure 5 may be performed. This variation also provides the same effects as the first and second embodiments.

[0063] (Embodiment 3) In the CO2 recovery system 1 of the above-described embodiment 2, the estimation unit 62 determines the reaction end time t when the change in liquid temperature over time in the analysis results of the analysis unit 61 does not have a peak in liquid temperature. end Liquid temperature rise ΔT end Although the above was calculated, in the CO2 recovery system 1 of Embodiment 3, instead, the estimation unit 62 calculates the reaction completion time t from the start of the reaction until the pH of the reaction solution L reaches a preset pH at the end of the reaction according to the target product produced by the CO2 immobilization reaction. end Based on this, the reaction completion time of the CO2 fixation reaction is estimated. The other configurations of the CO2 recovery system 1 in this embodiment 1 are the same as those of the CO2 recovery system 1 shown in Figure 1.

[0064] 11. Usage of the CO2 recovery system 1 of Embodiment 3 The usage of the CO2 recovery system 1 in this third embodiment will be explained with reference to the flow diagram shown in Figure 13. Steps S1 to S4 in the flow diagram shown in Figure 13 in this third embodiment are the same as steps S1 to S4 in the first embodiment shown in Figure 5, so their explanation will be omitted. Then, after step S4 shown in Figure 13, in step S53, the reaction completion time t is set from the start of the reaction until the pH of the reaction solution L reaches the pH at the end of the reaction, which is predetermined according to the target product produced by the CO2 immobilization reaction. end This is estimated as the reaction completion time for the CO2 fixation reaction.

[0065] Subsequently, in step S6 shown in Figure 13, similar to step S6 in Embodiment 1, the control unit 58 starts the operation of the CO2 recovery device 100 and bubbles the CO2-containing gas F1 into the reaction liquid L in the reaction vessel 10 according to the analysis conditions. Then, in step S9, similar to step S9 in Embodiment 1, when the estimated reaction completion time is reached, the control unit 58 stops the supply of the CO2-containing gas F1 and terminates the operation of the CO2 recovery device 100. The flow is then terminated.

[0066] 12. Effects of the CO2 recovery system 1 of Embodiment 3 The CO2 recovery system 1 of Embodiment 3 also produces the same effects and advantages as in Embodiment 2 described above.

[0067] In this embodiment 3, the estimation unit 62 estimates the reaction completion time t from the start of the reaction until the pH of the reaction solution L reaches a preset pH at the end of the reaction according to the target product produced by the CO2 immobilization reaction. end Based on this, the reaction completion time of the CO2 fixation reaction was estimated. Alternatively, the reaction completion time of the CO2 fixation reaction may be estimated when the pH of the reaction solution L reaches a predetermined pH according to the target product.

[0068] (Embodiment 4) In the CO2 recovery system 1 of the above-described embodiment 1, the estimation unit 62 uses the measured liquid temperature of the reaction solution L acquired by the liquid temperature sensor 50 as the liquid temperature measurement unit to estimate the reaction completion time of the actual CO2 fixation reaction. In this embodiment 4, instead, as shown in Figure 14, the system is equipped with a data processing unit 63 that performs data processing to smooth the measured liquid temperature of the reaction solution L acquired by the liquid temperature sensor 50 as the liquid temperature measurement unit to mitigate fluctuations in the measured value, and the estimation unit 62 estimates the reaction completion time of the actual CO2 fixation reaction based on the analysis results of the analysis unit 61 and the smoothed liquid temperature smoothed by the data processing unit 63.

[0069] 13. Data Processing Unit 63 The data processing unit 63 shown in Figure 14 performs data processing to smooth the measured liquid temperature of the reaction solution L and mitigate fluctuations in the measured value, as shown in Figure 15. The data processing is not limited to any method of smoothing, but for example, low-pass filtering, interval averaging, and moving average can be used, and among these, low-pass filtering is preferred. Furthermore, the data processing may be performed in multiple stages of smoothing. In this embodiment, the data processing applies a low-pass filter after preprocessing and interval averaging.

[0070] Since the measured liquid temperature of reaction solution L is discrete data, the data processing unit 63 uses a discretized low-pass filter. The low-pass filter transfer function is shown in equation 11 below, and the discretized low-pass filter can be shown in equation 12 below.

[0071]

number

[0072]

number

[0073] The cutoff frequency in the low-pass filter can be set to a predetermined value. In this embodiment 4, the cutoff frequency is set so that there are no intervals in which the duration of the period during which the smoothed liquid temperature change rate, which is the measured value of the smoothed liquid temperature, i.e., the differential value at each time, is 0 or less is less than a predetermined time.

[0074] 14. Confirmation Test of Embodiment 4 As a confirmation test for Embodiment 4, a confirmation test was conducted on the smoothing of the measured liquid temperature by the data processing unit 63. In this confirmation test, the measured liquid temperature of the reaction solution L obtained by the liquid temperature sensor 50, which acts as the liquid temperature measurement unit, was compared with the measured value obtained by pre-processing and averaging over an interval, and with the measured value obtained by applying a low-pass filter to the pre-processed value. The sampling time for the measured value was 10 seconds, the averaging interval for the interval averaging was 60 seconds, and six measured values ​​were averaged. The cutoff frequency of the low-pass filter was set to 0.0005 Hz.

[0075] The results of the verification test are shown in Figure 15. As shown in Figure 15, the measured values ​​indicated by symbol A show a very large number of fluctuations. In contrast, the pre-processed data indicated by symbol B is smoothed to some extent, but small peaks are still visible in areas such as the dashed lines, which may be misidentified as peaks in liquid temperature. On the other hand, the data processed with pre-processing and a low-pass filter, indicated by symbol C, is smooth overall, and no small peaks that could be misidentified as peaks in liquid temperature are present, indicating sufficient smoothing. Thus, pre-processing and low-pass filtering can prevent misidentification of peaks in liquid temperature due to fluctuations in the measured values.

[0076] Regarding the setting of the cutoff frequency of the low-pass filter in the verification test, Figure 16 shows the smoothed liquid temperature C, which is the measured liquid temperature after pretreatment and processing with the low-pass filter, and the degree of change ΔTc of the smoothed liquid temperature C. As shown in Figure 16, by setting the cutoff frequency of the low-pass filter to 0.0005 Hz, it is set so that there are no intervals in which the duration of the period in which the degree of change of the smoothed liquid temperature C is 0 or less is less than the preset time, and the peak time t peak It is now possible to detect it accurately.

[0077] 15.Estimation part 62 In this fourth embodiment, the estimation unit 62 calculates a peak time ratio when the analysis results of the analysis unit 61 show a peak in the change of liquid temperature over time. This ratio is the time from the start of the reaction to the time when the liquid temperature peaks in the simulation of the analysis unit 61, and the reaction completion time from the start of the reaction to the time when the pH of the reaction solution L reaches a preset pH according to the target product produced by the CO2 fixation reaction. The estimation unit 62 then estimates the reaction completion time of the actual CO2 fixation reaction based on the time when the smoothed liquid temperature reaches its peak in the actual CO2 fixation reaction and the peak time ratio in the simulation of the analysis unit 61.

[0078] Other components in Embodiment 4 are the same as those in Embodiment 1, and are denoted by the same reference numerals as in Embodiment 1, and their descriptions are omitted.

[0079] 16. Usage of the CO2 recovery system 1 of Embodiment 4 The usage of the CO2 recovery system 1 in this embodiment 4 will be explained with reference to the flow diagram shown in Figure 17. Steps S1 to S6 in the flow diagram shown in Figure 17 in this embodiment 4 are the same as steps S1 to S6 in embodiment 1 shown in Figure 5, so their explanation will be omitted. Then, in step S71 in Figure 17, the data processing unit 63 performs preprocessing of the measured liquid temperature of the reaction solution L and processing with a low-pass filter to calculate the smoothed liquid temperature. The cutoff frequency of the low-pass filter is set to an optimal value in advance.

[0080] Subsequently, in step S72, the estimation unit 62 determines whether the smoothed liquid temperature calculated by the data processing unit 63 has reached a peak. If it has not reached a peak, step S71 is repeated.

[0081] On the other hand, if it is determined in step S72 that the smoothed liquid temperature has reached its peak, in step S81 the estimation unit 62 estimates the time obtained by integrating the peak time ratio tend / tpeak with the time when the smoothed liquid temperature reached its peak as the reaction completion time of the operating CO2 recovery device 100. Then, in step S9, when the estimated reaction completion time is reached, the control unit 58 stops the supply of CO2-containing gas F1 and terminates the operation of the CO2 recovery device 100. The flow is then terminated.

[0082] 17. Effects of the CO2 recovery system 1 of Embodiment 4 The CO2 recovery system 1 of Embodiment 4 includes a liquid temperature measurement unit (liquid temperature sensor 50) that measures the liquid temperature of the reaction solution L during the actual CO2 fixation reaction in the reaction vessel 10, and a data processing unit 63 that performs data processing to smooth the measured liquid temperature of the reaction solution L measured by the liquid temperature measurement unit (liquid temperature sensor 50) and mitigate fluctuations in the measured value. The estimation unit 62 then estimates the reaction completion time of the actual CO2 fixation reaction based on the analysis results of the analysis unit 61 and the smoothed liquid temperature C, which is the measured liquid temperature of the reaction solution L in the actual CO2 fixation reaction that has been smoothed by the data processing unit 63. This mitigates fluctuations in the measured liquid temperature of the reaction solution L and prevents false detection of liquid temperature peaks. As a result, the accuracy of the reaction completion time estimation can be further improved.

[0083] Furthermore, especially when the reaction vessel 10 and other components are enlarged or scaled up, differences in the rate of reaction of the reaction solution L are likely to occur depending on the location within the reaction vessel 10. Moreover, when the external environment, such as the ambient temperature, changes, differences in the temperature of the reaction solution L are likely to occur depending on the location within the reaction vessel 10, making differences in the rate of reaction of the reaction solution L due to the location within the reaction vessel 10 even more likely. In the CO2 recovery system 1 of Embodiment 4, even when the reaction vessel 10 and other components are enlarged or scaled up in this way, the reaction completion time can be estimated with high accuracy, so that the reaction solution L can be used efficiently. This makes it possible to stabilize and improve the quality of CO2 recovery and resource recovery from reaction products, and also makes it possible to ensure safety and reduce environmental impact by eliminating unreacted reaction solution L.

[0084] Furthermore, in this embodiment 4, the data processing in the data processing unit 63 includes a low-pass filter with a predetermined cutoff frequency. This allows for appropriate mitigation of fluctuations in the measured liquid temperature of the reaction solution L, further preventing false detection of liquid temperature peaks.

[0085] Furthermore, in this embodiment 4, the data processing unit 63 sets the cutoff frequency so that there are no intervals in which the duration of the period during which the degree of change of the smoothed liquid temperature is 0 or less is less than a preset time. This makes it possible to appropriately mitigate fluctuations in the measured liquid temperature of the reaction solution L, and further prevents false detection of liquid temperature peaks.

[0086] Furthermore, in this embodiment 4, the data processing unit 63 performs a preprocessing step to smooth the measured liquid temperature of the reaction solution L, which is different from that of the low-pass filter, as part of the data processing, and then performs the low-pass filter processing. This optimizes the mitigation of fluctuations in the measured liquid temperature of the reaction solution L, and further prevents false detection of liquid temperature peaks.

[0087] Furthermore, in this embodiment 4, if the liquid temperature change over time in the analysis results of the analysis unit 61 has a peak, the estimation unit 62 determines the peak time t in the simulation of the analysis unit 61. peak The reaction completion time t is the time from the start of the reaction to the pH of the reaction solution reaching the preset pH at the end of the reaction, as simulated by the analysis unit 61. end The peak time ratio t is the ratio of to end / t peak We calculate the time t at which the smoothed liquid temperature C reaches its peak in the actual CO2 fixation reaction. peak And, the peak time ratio t in the simulation of the analysis unit 61 end / t peak Based on this, the reaction completion time t of the actual CO2 fixation reaction end This estimates the reaction end time t. This reduces fluctuations in the measured liquid temperature of reaction solution L, preventing false detection of the liquid temperature peak. end The estimation accuracy can be further improved. Furthermore, this fourth embodiment also provides the same effects and advantages as the first embodiment described above.

[0088] (Embodiment 5) In the CO2 recovery system 1 of Embodiment 4 described above, it is assumed that the reaction completion time cannot be estimated if some trouble occurs in the system 1, such as a malfunction of the liquid temperature sensor 50, and the liquid temperature cannot be obtained. Therefore, in Embodiment 5, the estimation unit 62 sets a maximum reaction time for the actual CO2 fixation reaction in advance, and when the elapsed time from the start of the reaction is greater than or equal to the maximum reaction time, it estimates the maximum reaction time as the reaction completion time of the actual CO2 fixation reaction. The other configurations are the same as in Embodiment 4.

[0089] 18. Usage of the CO2 recovery system 1 of Embodiment 5 The usage of the CO2 recovery system 1 in this 5 embodiment will be explained with reference to the flow chart shown in Figure 18. Steps S1 to S6 in the flow chart shown in Figure 18 in this 5 embodiment are performed in the same way as in the case of Embodiment 4. Step S10 is performed in parallel with steps S3 to S5. In step S10, the maximum reaction time for the CO2 fixation reaction is calculated based on the analysis conditions entered in step S2.

[0090] In Embodiment 5, after step S6, the process proceeds to step S11, where the estimation unit 62 determines whether the elapsed time from the start of the reaction in the actual CO2 fixation reaction is equal to or greater than a preset maximum reaction time.

[0091] In step S11, if it is determined that the elapsed time from the start of the actual CO2 fixation reaction is not equal to or greater than the maximum reaction time set in step S10, the process proceeds to step S11 No. and steps SS71 onwards are carried out in the same manner as in Embodiment 4. In step S72, if the estimation unit 62 determines that the smoothed liquid temperature calculated by the data processing unit 63 has not reached its peak, the process returns to step S11.

[0092] On the other hand, if in step S11 it is determined that the elapsed time from the start of the actual CO2 fixation reaction is equal to or greater than the maximum reaction time set in step S10, the process proceeds to Yes in step S11. In step S12, the maximum reaction time is estimated to be the reaction completion time of the actual CO2 fixation reaction, and the control unit 58 stops the supply of CO2-containing gas F1, thereby ending the operation of the CO2 recovery device 100. The process then ends.

[0093] 19. Effects of the CO2 recovery system 1 of Embodiment 5 In the CO2 recovery system 1 of Embodiment 5, the estimation unit 62 determines whether the elapsed time from the start of the actual CO2 fixation reaction is equal to or greater than a preset maximum reaction time. If it is determined that the elapsed time is equal to or greater than the maximum reaction time, the maximum reaction time is estimated to be the reaction end time of the actual CO2 fixation reaction. This allows the reaction to be stopped appropriately by estimating the reaction end time in the event that the liquid temperature cannot be obtained due to some trouble in the system 1, such as a malfunction of the liquid temperature sensor 50. In this Embodiment 5, the same effects and advantages as in Embodiment 4 described above are achieved.

[0094] The present invention is not limited to the above embodiments 1 to 5, and can be applied to various embodiments without departing from its spirit. [Explanation of Symbols]

[0095] 1. CO2 Capture System 10 reaction vessels 20 Reaction solution input volume adjustment unit 30 CO2-containing gas supply unit 31 Gas supply piping 32 nozzles 33 Gas discharge section 34 CO2 concentration sensor 35 Gas temperature sensor 40 Gas supply adjustment unit 50 Liquid temperature sensor 51 Outdoor temperature sensor 55 Exhaust section 56 Product Recovery Section 57 Drain cock 58 Control Unit 61 Analysis Department 62 Estimation part 63 Data Processing Unit 100 CO2 recovery device L reaction solution M Mesh Model

Claims

1. CO2 is added to the reaction solution, which consists of an aqueous alkali metal hydroxide solution or an aqueous alkaline earth metal hydroxide solution, stored in the reaction vessel. ２ CO2 is brought into contact with the contained gas. ２ By performing the immobilization reaction, CO ２ CO2 recovery ２ Recovery device and At least the specifications of the reaction tank, the liquid volume of the reaction solution stored in the reaction tank, the initial liquid temperature of the reaction solution, and the CO ２ concentration of the CO ２ -containing gas, the flow rate of the CO ２ -containing gas supplied to the reaction tank, and the temperature of the CO ２ -containing gas, by simulating the immobilization reaction, an analysis unit that pre-analyzes the change over time of the liquid temperature of the reaction solution and the change over time of the pH of the reaction solution from the start of the immobilization reaction,​​​​ Based on the analysis results of the analysis unit, the actual CO ２ An estimation unit that estimates the reaction completion time of the immobilization reaction, CO ２ Collection system.

2. Actual CO in the reaction tank ２ It is equipped with a liquid temperature measurement unit that measures the liquid temperature of the reaction solution during the immobilization reaction, The estimation unit, When the change in liquid temperature over time in the analysis results has a peak, the peak time is the time from the start of the reaction in the simulation to the time when the liquid temperature peaks, and the pH of the reaction solution in the simulation is the CO2 ２ The peak time ratio is calculated, which is the ratio of the reaction completion time to the time it takes to reach a predetermined pH at the end of the reaction, depending on the target product produced by the immobilization reaction. The actual CO2 measured by the liquid temperature measurement unit ２ Based on the time at which the liquid temperature reached its peak in the immobilization reaction and the ratio of the peak time in the simulation, the actual CO ２ The CO2 according to claim 1, for estimating the reaction completion time of an immobilization reaction. ２ Collection system.

3. If the estimation unit does not detect a peak in the liquid temperature over time from the analysis results, it will determine from the analysis results that the pH of the reaction solution in the simulation is the CO ２ The amount of temperature rise in the liquid as it changes over time to reach a predetermined pH at the end of the reaction, depending on the target product produced by the immobilization reaction, is calculated, and based on this temperature rise, the actual CO2 ２ The CO2 according to claim 1, for estimating the reaction completion time of an immobilization reaction. ２ Collection system.

4. If the estimation unit does not detect a peak in the liquid temperature over time from the analysis results, then the pH of the reaction solution from the start of the reaction in the simulation is the CO ２ Based on the reaction completion time until the pH at the end of the reaction, which is predetermined according to the target product produced by the immobilization reaction, the actual CO ２ The CO2 according to claim 1, for estimating the reaction completion time of an immobilization reaction. ２ Collection system.

5. The analysis unit determines the CO in the simulation. ２ The amount of heat generated in the recovery system and the amount of heat released to the outside from the reaction vessel are calculated, and the CO ２ The CO2 recovery system is used to calculate the change in liquid temperature over time in the simulation, based on the amount of heat generated and the amount of heat released, according to any one of claims 1 to 4. ２ Collection system.

6. Actual CO in the reaction tank ２ A liquid temperature measurement unit for measuring the liquid temperature of the reaction solution during the immobilization reaction, A data processing unit performs data processing to smooth the measured values ​​of the reaction liquid temperature measured by the liquid temperature measurement unit and reduce fluctuations in the measured values. Equipped with, The estimation unit uses the analysis results from the analysis unit and the actual CO2 that has been smoothed by the data processing unit. ２ Based on the measured value of the reaction solution temperature in the immobilization reaction, which is the smoothed liquid temperature, the actual CO ２ The CO2 according to claim 1, for estimating the reaction completion time of an immobilization reaction. ２ Collection system.

7. The data processing in the data processing unit includes a low-pass filter with a predetermined cutoff frequency set, as described in claim 6. ２ Collection system.

8. The cutoff frequency is set so that there is no interval in which the duration of the period in which the degree of change in the smoothed liquid temperature is 0 or less is less than a predetermined time, as described in claim 7 of CO ２ Collection system.

9. The data processing unit performs a pre-processing step, which smooths the measured liquid temperature of the reaction solution, which is different from that of the low-pass filter, as part of the data processing, and then performs the low-pass filter, according to claim 7 of the CO2 ２ Collection system.

10. The estimation unit, When the change in liquid temperature over time in the analysis results has a peak, the peak time is the time from the start of the reaction in the simulation to the time when the liquid temperature peaks, and the pH of the reaction solution in the simulation is the CO2 ２ The peak time ratio is calculated, which is the ratio of the reaction completion time to the time it takes to reach a predetermined pH at the end of the reaction, depending on the target product produced by the immobilization reaction. The actual CO ２ Based on the time at which the smoothed liquid temperature reached its peak in the immobilization reaction and the peak time ratio in the simulation, the actual CO ２ CO according to claim 6 or 7, for estimating the reaction completion time of the immobilization reaction. ２ Collection system.

11. The estimation unit determines the actual CO ２ It is determined whether the elapsed time from the start of the immobilization reaction is equal to or greater than a predetermined maximum reaction time. If it is determined that the elapsed time is equal to or greater than the maximum reaction time, the maximum reaction time is set to the actual CO2. ２ The CO2 according to claim 1, which estimates the reaction completion time of the immobilization reaction. ２ Collection system.

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